What is cervical cancer? |

Related conditions:
Squamous intraepithelial lesion (SIL), dysplasia, human papillomavirus (HPV) infection

Definition:

Cervical cancer is a slow-growing cancer of the female reproductive organs. The two primary types of cervical cancer are squamous cell carcinoma and adenocarcinoma. Classified by microscopic examination, squamous cell carcinoma accounts for 90 percent of diagnosed cases. The majority of the remaining cases are classified as adenocarcinoma, a cancer that develops from the mucus-producing gland cells in the endocervix. Additionally, a very small minority of cervical cancer cases demonstrate characteristics of both types and are therefore classified as adenosquamous or mixed carcinomas.

Risk factors: The most significant risk factor for developing cervical cancer is infection with high-risk types of human papillomavirus (HPV). HPV is sexually transmitted, and certain sexual behaviors can increase the risk of infection: sex at an early age, multiple sexual partners (directly or indirectly through a partner who has multiple sexual partners), and sex with an uncircumcised partner. Although use of condoms does not eliminate the potential for HPV infection because any skin-to-skin contact can be sufficient to transmit the virus, condoms nonetheless do provide limited protection. Studies have identified the following additional risk factors:

• Obesity/low-fiber diet





• Smoking





• Concomitant infection with another sexually transmitted disease such as human immunodeficiency virus (HIV), herpes simplex virus (HSV), or chlamydia





• Long-term oral contraceptive use





• Multiple full-term pregnancies





• In utero exposure to diethylstilbestrol (DES, a hormone prescribed from 1940 to 1971 for some pregnant patients considered at high risk for miscarriage)





• Family history of cervical cancer

Etiology and the disease process: Human papillomavirus (HPV) is a group of more than one hundred distinct viruses, with approximately forty strains capable of infecting the genital tract. Researchers have classified fifteen HPV types as high risk for cancer development, with a nearly two-thirds prevalence of types 16 and 18 in cervical cancer samples. In the vast majority of cases, HPV infection is spontaneously cleared by a healthy immune system. In a minority of cases, however, the virus can remain latent for years before eventually converting normal cervical cells to cancerous ones. Because only a small percentage of women infected with HPV progress to cervical cancer, lifestyle and immune system competence are believed to play a vital role in the progression of the disease.

Incidence: Cancer of the cervix is second only to breast cancer in prevalence among women worldwide. Nearly 500,000 new cases are diagnosed each year, with a greater than 80 percent occurrence in developing countries.

Age-standardized incidence rates fall in the 15 per 100,000 range for most first-world countries. In the United States, more than 11,000 new cases are diagnosed each year, with nearly 4,000 deaths annually.

Symptoms: Early cervical cancer does not generally produce any distinguishable signs or symptoms. Abnormalities found in screening tests are the most common and effective method for detecting the presence of precancerous and cancerous cervical cells. As untreated disease progresses, symptoms may include unusual vaginal bleeding (after intercourse, between periods, postmenopausal); watery, bloody, and foul-smelling vaginal discharge; pelvic pain; or pain during intercourse.

Screening and diagnosis: Extensive cervical screening programs designed to detect early, precancerous cervical changes are well established in most developed countries. Exfoliative cytology (Pap test) is the primary component of these programs, although molecular HPV deoxyribonucleic acid (DNA) testing is also commonly incorporated. Colposcopy is a second-level diagnostic procedure used as a follow-up to abnormal screening results.

Named after the physician who developed the procedure (Papanikolaou), exfoliative cytology, or Pap test, is a screening procedure involving the collection and microscopic evaluation of cervical cells. During a routine pelvic examination, cervical cells are collected by broom, brush, spatula, or other means. These cells are either smeared directly onto a microscope slide (as in the traditional, “dry” Pap smear) or transferred into a liquid medium to concentrate the cells for subsequent transfer onto a slide. This new liquid-based cytology has demonstrated greater test sensitivity because more cells can be analyzed.

The HPV DNA test is a molecular analysis of a cervical sample to determine the presence of HPV and its type. This test is used in conjunction with an abnormal Pap test as an additional diagnostic tool.

A colposcopy is a pelvic examination in which a light source and binocular microscope are used to enable a direct magnified inspection of the patient’s cervix, vagina, and vulva. Application of a weak acetic acid solution also serves to highlight any suspicious abnormalities.

Following abnormal screening results, additional tests may be ordered to confirm diagnosis and determine how far the cancer has spread (staging):

• Biopsy: Analysis of a small section of tissue collected from the cervix





• Proctoscopy: Visual inspection of the rectum for the presence of cancer





• Imaging (such as X ray, magnetic resonance imaging, computed tomography, positron emission tomography): Patient/organ appropriate imaging to inspect for cancer spread (metastasis)

Cervical cancer is staged based on tumor size, invasive nature, and degree of metastasis (spread to lymph nodes/organs). Cervical cancer is staged with the International Federation of Gynecology and Obstetrics (FIGO) system:

• Stage 0: Carcinoma in situ; superficial cancer is detected in the cervical lining.





• Stage I: Cancer has invaded the cervix but has not spread.





• Stage IA: Microscopic amounts of cancer cells are present.





• Stage IA1: Cancer invasion is less than 3 millimeters (mm) deep and less than 7 mm wide.





• Stage IA2: Cancer invasion is between 3 and 5 mm deep and less than 7 mm wide.





• Stage IB: Cancer is greater than 5 mm deep and greater than 7 mm wide.





• Stage IB1: Cancer is visible but less than 4 centimeters (cm).





• Stage IB2: Cancer is visible and greater than 4 cm.





• Stage II: Cancer has spread beyond the cervix but is contained within the pelvis.





• Stage IIA: Cancer has spread to the upper part of the vagina.





• Stage IIB: Cancer has spread to the parametrial tissue (next to the cervix).





• Stage III: Cancer has spread to the lower part of the vagina or the pelvic wall.





• Stage IIIA: Cancer has spread to the lower third of the vagina.





• Stage IIIB: Cancer has spread to the pelvic wall or blocks urine flow.





• Stage IV: Cancer has spread to nearby organs.





• Stage IVA: Cancer has spread to the bladder or rectum.





• Stage IVB: Cancer has spread to more distant organs.

Treatment and therapy: Treatment of cervical cancer largely depends on disease stage. The three treatment options are surgery, radiation, and chemotherapy.

Surgical removal is used primarily for nonmetastatic lesions. Cryosurgery uses a metal probe cooled with liquid nitrogen to freeze cancerous cells. Laser surgery uses a laser to burn (vaporize) cancerous cells. In conization, a thin, heated wire (LEEP, or loop electrosurgical excision procedure) or surgical/laser knife (cold knife cone biopsy) removes the affected tissue. Rarely used as a sole treatment, conization aids in diagnosis before additional surgery or alternative treatment. In a hysterectomy, the degree of the removal of uterine tissue (simple vs. radical) depends on the stage and patient circumstances.

Radiation employs high-energy X rays to kill cancer cells, either externally (external beam radiation) or internally via a radioactive capsule (brachytherapy).

Chemotherapy uses anticancer drugs (such as cisplatin, paclitaxel, topotecan, ifosfamide, or fluorouracil) taken orally or intravenously to treat metastasized cancer.

Prognosis, prevention, and outcomes: Early detection through effective screening programs offers a high probability for complete cancer eradication. Continued adherence to annual cervical screening and healthy habits is integral to continued remission.

A new vaccine, Gardasil, approved by the Food and Drug Administration offers protection against the most dangerous, high-risk HPV types 16 and 18. It also protects against types 6 and 11, which cause genital warts. For greatest efficacy, the vaccine should be administered before the patient has become sexually active. The Federal Advisory Committee on Immunization Practices (ACIP) recommends vaccination for girls aged eleven and twelve. The committee also recommends that nonvaccinated women from age thirteen to twenty-six receive catch-up vaccinations. Although the American Cancer Society (ASC) agrees with the initial vaccination protocol, it recommends catch-up vaccinations for young women aged thirteen to eighteen only. ACS recommends that older women discuss the potential benefit of the vaccination with regard to their personal risk factors for previous exposure to HPV.

Devita, Vincent T., Jr., Samuel Hellman, and Steven A. Rosenberg, eds. Cancer: Principles and Practice of Oncology. 7th ed. Philadelphia: Lippincott Williams & Wilkins, 2005.

Saslow, D., et al. “American Cancer Society Guideline for Human Papillomavirus (HPV) Vaccine Use to Prevent Cervical Cancer and Its Precursors.” CA: A Cancer Journal for Clinicians 57 (2007): 7-28.

Stewart, Bernard W., and Paul Kleihues, eds. World Cancer Report. Lyon, France: IARC Press, 2003.

What is vibrio? |

Definition

Vibrio, among the most common forms of bacteria of
the surface waters of the earth, is a motile aerobic rod that causes the human
disease cholera, other forms of gastroenteritis, and some extraintestinal infections.

Natural Habitat and Features

Vibrios are gram-negative bacteria with a curved rod shape. They are aerobic
and motile, with a polar flagellum. Vibrios are common in salt water and fresh
water around the world. The bacteria can be carried by numerous animals that live
in the sea and may be ingested through human consumption of crabs, clams, and
oysters. V. cholerae is the most medically important species, as
it causes the disease cholera, which is endemic to India and
Southeast Asia.

Vibrios produce smooth, rounded colonies that are opaque when exposed to light.
They grow well at 98.6° Fahrenheit (37° Celsius) on
thiosulfate-citrate-bile-sucrose agar and on many other media. When cultured over
time, the curved rods may become straight and resemble gram-negative intestinal
bacteria. Cholerae grows rapidly on blood agar with a pH
(acidity) level near 9. Typical colonies are identifiable in about eighteen
hours.

Vibrios are differentiated from other intestinal gram-negative bacteria by being oxidase positive. A positive oxidase test is important in preliminary identification of cholerae and other vibrios. They grow well in high pH but are rapidly killed by acid. For this reason, any condition or medication that decreases stomach acidity may predispose a person to infection.

Antigenic structures of vibrios include a single heat-labile flagellar H antigen. Cholerae has O lipopolysaccharides that define serologic specificity. (A minimum of 139 O-antigen groups exist.) Antibodies to O antigens may protect some animals from infection. Enterotoxins produced by cholerae can cause prolonged hypersecretion of water and electrolytes in humans, causing profuse diarrhea. Cholera enterotoxin may stimulate the production of neutralizing antibodies. Although an attack of cholera may be followed by immunity, the duration and degree is unpredictable.

Pathogenicity and Clinical Significance

Cholerae is pathogenic only in humans. It is not an invasive infection. It remains in the intestinal tract attached to the microvilli of intestinal epithelial cells, where it releases toxins but does not enter the bloodstream. Up to 60 percent of infections may be asymptomatic. The development of symptoms depends on the size of the inoculum. When symptoms do occur, they follow an incubation period of one to four days. Typically, symptoms develop suddenly and may include cramping, abdominal pain, nausea, vomiting, and profuse diarrhea. The term “rice water diarrhea” is used to describe the stools, which contain copious mucus, epithelial cells, and large numbers of vibrios. Diarrhea and vomiting lead to rapid depletion of fluid and electrolytes.

Untreated cholera may result in profound dehydration,
anuria, circulatory collapse, and death. Mortality rates as high as 50 percent may
be seen during an epidemic. Diagnosis of epidemic or endemic cholera is not
difficult, but sporadic or isolated cases may be confused with other causes of
gastroenteritis.

Other vibrios causing human disease include parahaemolyticus, which causes gastroenteritis following ingestion of Vibrio-infected seafood. Incubation is twelve to twenty-four hours, which is followed by nausea, vomiting, fever, and diarrhea that may be bloody. The symptoms usually subside without treatment in one to four days. Parahaemolyticus does not produce a toxin. It is present worldwide and may infect humans who eat raw seafood.

Vulnificus is a free-living organism found in ocean estuaries
worldwide. In the United States, vulnificus is found
predominantly along the Gulf Coast. People swimming in these waters with an open
wound may become infected, and the infection may cause sepsis.
Vulnificus may be found in oysters during warm months and may
cause gastroenteritis if eaten raw. Although wound infections may be mild,
vulnificus may have a mortality rate as high as 50 percent if
sepsis develops. Other vibrios that may cause diarrhea include
mimicus, hollisae, and
fluvialis. Other vibrios that cause wound infections include
damsela and alginolyticus.

Drug Susceptibility

Vibrio gastroenteritis is usually self-limited, and most people will recover as
long as adequate hydration and nutrition are available. Most vibrios are sensitive
to antibiotics, but antibiotic therapy may not shorten the
course of intestinal illness. Antibiotics are more important in vibrio wound
infection or in bacteremia. In these cases, intensive medical therapy,
including intravenous antibiotics, management of septic shock,
and aggressive surgical debridement, may be needed.

Antibiotics that are effective against cholera include tetracycline and
ciprofloxacin. In wound infections and bacteremia caused by noncholera
Vibrio species, the combination of doxycycline, ceftazidime,
and a broad-spectrum type penicillin, such as ticarcillin, is the treatment of
choice. Many Vibrio species have developed resistance to commonly
used antibiotics. Vibrios have been found to be susceptible to several novel
antibiotics, such as tigecycline, daptomycin, and linezolid.

Bibliography

Brooks, George F. and Carroll, Karen C. Jawetz, Melnick, and Adelberg’s Medical Microbiology. 25th ed. New York: McGraw-Hill, 2010. Chapter 17 of this textbook gives an excellent introduction to the vibrios including their morphology, identification, antigenic structure, and growth characteristics.

Fauci, Anthony, et al., eds. Harrison’s Principles of Internal Medicine. 17th ed. New York: McGraw-Hill, 2008. Chapter 149 covers cholera and other vibrio infections. Includes a good discussion of vibrio infections other than cholera gastroenteritis.

Ho, Hoi. “Vibrio Infections.” Available at http://emedicine.medscape.com/article/232038-overview. Examines vibrio infection, including aggressive treatment of noncholera wound infection and bacteremia.

Vaseeharan, B., et al. “In Vitro Susceptibility of Antibiotics Against Vibrio spp. and Aeromonas spp. Isolated from Penaeus monodon Hatcheries and Ponds.” Journal of Antimicrobial Agents 26 (2005): 285-291. Provides a good background on antibiotic susceptibilities of Vibrio species and the emergence of resistant strains.

Why does Miss Maudie garden in To Kill a Mockingbird?

In To Kill a Mockingbird, Miss Maudie gardened because of her background and her values. We learn in Chapter 5 that Miss Atkinson was the daughter of Dr. Frank Buford. His "profession was medicine and his obsession was anything that grew in the ground, so he stayed poor." Growing up with a father who apparently valued botany over his livelihood would have fostered a strong appreciation in a young Maudie. Miss Maudie was also a...

In To Kill a Mockingbird, Miss Maudie gardened because of her background and her values. We learn in Chapter 5 that Miss Atkinson was the daughter of Dr. Frank Buford. His "profession was medicine and his obsession was anything that grew in the ground, so he stayed poor." Growing up with a father who apparently valued botany over his livelihood would have fostered a strong appreciation in a young Maudie. Miss Maudie was also a Baptist, not a strongly religious one, but she loved God and His creations, so almost all of her waking hours were spent outside gardening. This was her alternative to worshiping the way most of the ladies in Maycomb did. It wasn't that she didn't have an impressive knowledge of scripture; she could quote passages along with the "foot-washing Baptists" in the county. I think she found more value in her personal relationship with her spirituality than in organized religion, where much corruption and hypocrisy could be found. Miss Maudie was a widower, and it is possible that her obsession with her garden was an outlet for her grief, and a way for her to nurture something and add beauty to her life. 

Miss Maudie hated her house: time spent indoors was time wasted... She loved everything that grew in God’s earth, even the weeds.

What are the effects of addiction to cigarettes and cigars?

History of Use

Smoking tobacco was introduced in Europe in the sixteenth century and in the United States in the seventeenth century. Matches and cigarettes were first commercially produced in the nineteenth century, facilitating the habit of smoking. By 1901, 80 percent of American men smoked at least one cigar a day; that same year, 6 million cigars and 3.5 million cigarettes were sold in the United States.

In 1913, the R. J. Reynolds Tobacco Company introduced Camel cigarettes, and ten years later, Camels were smoked by 45 percent of American smokers. By 1940, the number of cigarette smokers had doubled from that of 1930. Tobacco company advertising and marketing in the twentieth century especially targeted military personnel and women.

In 1950, the first evidence linking lung cancer and tobacco smoking was published in a British medical journal. In 1965, a US federal law mandated that a warning from the US surgeon general be placed on all packages of cigarettes and all cigarette advertising, stating the risks of smoking tobacco. In 1971, cigarette advertising was banned from television. In 1972, Marlboro became the best-selling brand of cigarettes in the world, and it remains the best-selling brand. In 1988, the US surgeon general determined that nicotine was an addictive substance. Nine years later, a US federal judge ruled that the US Food and Drug Administration
can regulate tobacco as a drug.

Worldwide, nearly 5.4 million people die annually from tobacco-related illnesses, including heart disease, stroke, and cancer. For every person who dies of a smoking-related disease, twenty people are living with a serious smoking-related disease. Men who do not smoke live 13.2 years longer than men who do smoke, and women who do not smoke live 14.5 years longer than women who do smoke.

Effects and Potential Risks

The smoking of tobacco leads to nicotine addiction. Repeated introduction of nicotine into the body causes increased production of dopamine in the pleasure centers of the brain. As the dopamine level drops, the smoker feels depressed and lights the next cigarette or cigar to regain the heightened sense of pleasure and well-being.

Nicotine also stains the teeth and fingers yellow, sours the breath, diminishes the senses of smell and taste, and reduces one’s appetite. People who smoke experience hair loss and wrinkle formation at a younger age. Women who smoke have an increased risk of miscarriage, premature labor, and giving birth to an underweight baby.

Along with nicotine, tobacco smoke contains carbon monoxide, which reduces the blood’s ability to carry oxygen to cells. To ensure that adequate oxygen reaches vital organs, the body reduces the blood flow to the extremities. Smoking stresses the heart and thereby increases the risks of heart disease and stroke.

The toxicity of tobacco smoke damages the lips, tongue, gums, throat, larynx, esophagus, and lungs. This progressive damage leads to chronic bronchitis and emphysema and an increased likelihood of death from cancer of the mouth, lungs, kidneys, bladder, pancreas, and stomach.

Nonsmokers who breathe environmental, or secondhand, cigarette and cigar smoke are also exposed to the toxins and carcinogens contained in that smoke. Nonsmokers are thus exposed to the same health risks as smokers.

In the 2010s, e-cigarettes, which provide users with nicotine in the form of a vaporized liquid without the tobacco smoke, have become popular as a less dangerous alternative to smoking. However, studies have suggested that use of e-cigarettes is still associated with respiratory problems, and nicotine itself has been linked to cardiovascular, respiratory, gastrointestinal, and reproductive disorders, and may be a carcinogen.

Bibliography

Bellenir, Karen. Tobacco Information for Teens: Health Tips about the Hazards of Using Cigarettes, Smokeless Tobacco, and Other Nicotine Products. Aston: Omnigraphics, 2010. Print.

Carr, Allen. The Easy Way to Stop Smoking: Join the Millions Who Have Become Non-Smokers Using Allen Carr’s Easy Way Method. New York: Sterling, 2010. Print.

De Lange, Catherine. “Smoke Without Fire.” New Scientist 1 Nov. 2014: 35–39. Print.

Lester, Robin A. J., ed. Nicotinic Receptors. New York: Humana, 2014. Print.

Mishra, Aseem, et al. "Harmful Effects of Nicotine." Indian Journal of Medical and Paediatric Oncology 36.1 (2015): 24–31. Print.

Rose, Jed Eugene, et al. “Personalized Smoking Cessation: Interactions between Nicotine Dose, Dependence, and Quit-Success Genotype Score.” Molecular Medicine 16 (2010): 247–53. Print.

What are behavioral therapies for addictions?

The Behavioral Perspective

From the behavioral perspective, an addiction is a maladaptive way to cope with difficulties and to satisfy unmet needs in life. Behaviorally, the person who is addicted to drugs or alcohol is experiencing a learned sequence of behaviors acquired over time in response to problems or circumstances in life.

An addiction is a learned behavior that may have resulted from observing other persons coping with stressors through the use of substances. An addiction also can develop after a person has a rewarding experience with the physiological effects of alcohol or drugs. Once a person finds that the depressive or stimulating properties of drugs or alcohol have desirable effects, that person will use the substances to cope with stressors and other negative states. Substance abuse can become a preferred coping behavior, as substances work fairly rapidly. Also, ingesting these substances usually takes little effort. Repeatedly using a substance to cope with personal or situational problems leads to an addictive pattern of abuse.

Addiction from the behavioral perspective can be summarized as follows: a stressor triggers the need for coping, a substance is obtained and used, its effects are experienced, the negative feelings from the stressor are blunted, and, consequently, the substance is used in greater quantities to mitigate personal or situational problems. This learned pattern then becomes an addiction from which the person is unwilling or unable to break.

Learning Theory Foundations

The behavioral therapies for addictions are based upon the early research conducted by Ivan Pavlov and B. F. Skinner. Pavlov studied the concept of classical conditioning, in which a neutral stimulus that previously did not evoke any positive or negative response could be conditioned to produce a positive or negative response. This classical conditioning paradigm involved the pairing of the neutral stimulus with a reward or punishment. When associated with a rewarding stimulus, a positive response to the neutral stimulus emerged. A negative or punishing stimulus when paired with the neutral stimulus would produce a negative or avoidance response.

Skinner is known for his work with operant conditioning
, which showed the power of positive reinforcement or reward in producing and maintaining responses. Skinner showed that a person will learn behavior that has been positively reinforced and will keep responding to earn the reward.

The foundations of classical and operant conditioning demonstrate that the pattern of addiction can be explained through the application of learning principles. Neutral settings may become classically conditioned to promote substance use and abuse through the power of rewards. Operant conditioning strengthens the behaviors associated with addictions, as the substance may initially manage stressors in a person’s life and then reward the person for engaging in the addictive actions. The behavioral therapies focus on reversing the previous patterns of classical and operant conditioning that produced the addiction patterns.

Treatment from the Behavioral Perspective

The behavioral therapies for addictions focus on the emotional or situational factors that promote episodes of substance use and on the underlying factors that maintain the behaviors. These therapies seek to break the learned pattern that promotes addiction and to replace the maladaptive pattern with new adaptive behaviors. The triggers for the learned pattern are identified as the antecedents for the maladaptive addiction. This helps a therapist determine the occasions or reasons for the substance use.

A number of antecedents to the pattern of maladaptive substance use exists, so therapists seek to identify what has produced the pattern of addiction. Some common triggers or antecedents are social pressures, interpersonal conflicts, depressive moods, anger or frustration in life, chronic pain, poor role models, or settings where substances are routinely abused. Once a pattern has been learned, a number of factors can contribute to its maintenance.

The addictive pattern can continue because of the physiological effects of a substance, because of a reduction in anxiety, or because of social reinforcement from others with similar addictions. For each person affected, treatment involves identifying the most common and powerful triggers or antecedents and developing behavioral strategies to learn effective ways to manage the triggering factors that had created the learned pattern of addiction.

Treatment can be difficult because each person may have significant behavioral deficits to overcome. Some persons may never have learned the coping skills or behaviors that would help them to handle personal or situational distress. Behavioral therapies not only try to break the pattern of addiction but also try to overcome skill deficits that keep a person from facing problems in an adaptive fashion.

Coping Skills

To overcome the detrimental long-term consequences of addictive behavior, treatment includes coping-skills training, a behavioral therapy designed to achieve abstinence and to learn adaptive behaviors. This training involves an initial functional analysis to determine the role of the addiction in the person’s life. Functional analysis shows what skills are lacking in the person’s behavioral repertoire, especially those skills needed to cope with situational or personal stressors, and shows how addictive behaviors have been used as ways to cope.

The clinical interview is used for the functional analysis in conjunction with a variety of assessment instruments. These instruments provide objective measures to identify the extent of the addiction behaviors. It has often been found in the functional analysis that a person’s emotional state is closely tied to the addiction. Feelings of depression, anxiety, loneliness, inadequacy, estrangement, and weakness are often inadequately managed because the person lacks effective coping skills. Substance use and abuse or some other behavioral addiction become conditioned responses to unpleasant emotional states.

With the completion of the functional analysis, behavioral therapy then enters a treatment planning phase that focuses on skills to overcome addictive behavior. Two major categories of skills make up the treatment planning phase: intrapersonal and interpersonal.

Intrapersonal skills involve the person’s decision-making patterns and problem-solving capabilities. Intrapersonal-skills training helps to improve a person’s ability to think through stressor situations (and anticipate problems) and then to select adaptive ways of coping with the situation or feeling. New ways of acting and thinking about problems or feeling states can be reinforced, resulting in a new pattern of behavior learned through the assistance of a behavioral therapist.

Interpersonal-skills training seeks to overcome problems with familial and social interactions. Behavioral therapies attempt to refresh or teach the skills needed for effective interpersonal relationships. The person with a substance abuse problem needs to learn how to refuse invitations from others to take substances and to avoid the social contexts that may reinforce addictive behaviors.

Having inadequate social skills also can contribute to feelings of loneliness and inadequacy. Interpersonal-skills training can bolster self-esteem and enhance a person’s resistance to addiction.

Training in Action

Coping-skills training begins with the establishment of specific behavioral goals that focus on the elimination and management of the triggers for substance abuse or behavioral addictions. Behavioral goals, which are regularly reviewed at the beginning of each therapy session, can be covered in an individual, group, or family format. Contingency management, the major technique used in behavioral therapy, attempts to modify a behavioral response by controlling the consequences of that response. Patients are rewarded when their adaptive behavior adheres with their behavioral goals. Failure to adhere to the behavioral goals in a treatment plan leads to a loss of reinforcement or reward. Contingency management is based upon the basic principles of operant conditioning, which predict that if a good or desirable behavior is rewarded, it is more likely to be repeated.

A component of contingency management is stimulus control. This is a procedure that is used to help a patient avoid or leave a situation that leads to substance abuse or behavioral addictions. Stimulus control is basically learning to pay attention to characteristics in the environment that can promote or trigger the pattern of addiction. Behavioral therapy is expanded for individual patients to whatever areas can promote adaptive function; it can include skill development in the areas of communication, parenting, time management, and occupational training.

Bibliography

Azrin, Donahue, et al. “Family Behavior Therapy for Substance Abuse and Other Associated Problems: A Review of Its Intervention Components and Applicability.” Behavior Modification 33 (2009): 495–519. Print.

Hougue, Aaron, et al. “Family Based Treatment for Adolescent Substance Abuse: Controlled Trials and New Horizons in Services Research.” Journal of Family Therapy 31 (2009): 126–54. Print.

Potenza, March, et al. “Neuroscience of Behavioral and Pharmacological Treatments for Addictions.” Neuron 69 (2011): 695–712. Print.

Witkiewitz, Katie, et al. “Behavioral Therapy across the Spectrum.” Alcohol Research 33 (2010): 313–19. Print.

In Ch. 15 of To Kill a Mockingbird, why does Atticus wait outside of the jailhouse?

Tom Robinson is moved to the jailhouse prior to the trial and Sheriff Heck Tate warns Atticus that there is a group of men who are unhappy about it, who have been drinking, and who might plan on making trouble. What he really means is that these men might well end up going to the jail and hurting Tom Robinson. At first, Atticus does not believe this is a possibility.

"Don't be foolish, Heck," Atticus...

Tom Robinson is moved to the jailhouse prior to the trial and Sheriff Heck Tate warns Atticus that there is a group of men who are unhappy about it, who have been drinking, and who might plan on making trouble. What he really means is that these men might well end up going to the jail and hurting Tom Robinson. At first, Atticus does not believe this is a possibility.

"Don't be foolish, Heck," Atticus said, "this is Maycomb."

But Tate argues that it is not the men of Maycomb, but a group from "Old Sarum," who are getting upset.

So, in order to be a visible show of protection for Tom Robinson, Atticus goes to the jail and sits outside. It turns out Sheriff Tate is correct and the mob ends up confronting Atticus. Fortunately, his kids and Dill show up and Scout diffuses the whole situation by striking up a conversation with Mr. Cunningham. After the mob leaves, without doing any harm, it's revealed that Mr. Underwood was watching them, with his shotgun at hand. This proves how real the threat was.

How do soil properties affect vegetation type?

Soil is a rich medium for life. There are numerous types of soils, all possessing different compositions and properties. Key components of soil are organic matter, inorganic particles, living organisms (microbes), and air (or pore spaces). The composition of soils consists of varying percentages of each of these "ingredients." The amount of each of these different components determines what properties the soil will have, and which types of plants will thrive there. 

Every plant requires...

Soil is a rich medium for life. There are numerous types of soils, all possessing different compositions and properties. Key components of soil are organic matter, inorganic particles, living organisms (microbes), and air (or pore spaces). The composition of soils consists of varying percentages of each of these "ingredients." The amount of each of these different components determines what properties the soil will have, and which types of plants will thrive there. 

Every plant requires that certain nutrients are available in the soil in specific amounts. The quantity required is usually an ideal range of nutrients. It may be helpful to consider the nutrient needs of humans. For example, an average 150-pound person will do best drinking 75-150 ounces of water per day. If the person drinks less than 75 ounces or more than 150 ounces, their health may suffer. As long as the human obtains the amount of water within the range (75-150 oz.), his or her water needs as an organism will be met. 

Similarly, every plant has its own optimal intake of water and other nutrients. Soil is the medium that provides water and nutrients to plants, and the soil properties determine which plants will grow there. Soils that lack specific nutrients or do not provide the required quantities of a particular nutrient will not be a suitable medium for some plants to grow. Different types of plants have different nutrient requirements, so a soil that is ideal for one plant may not be suitable for another.

What is a medical diagnosis?

Indications and Procedures

When individuals see health care professionals for treatment, they are evaluated to determine the nature of their concerns. The process of evaluation usually involves a combination of assessment, screening, reassessment, and then formal diagnosis. They typically initially describe their experience, concerns, and history, and then the professional asks more questions and may follow up with screening questions.

Screening questions identify risk for any more serious conditions and for which additional assessment is needed. Screening is inexpensive and involves a small amount of time on questions that are easy to ask and answer, providing a determination of whether the person is at risk for a specific problem. If the screening result is positive, then the risk is there and further evaluation is needed; if it is negative, then the risk is deemed absent and no further evaluation is needed. Unfortunately, no screening process is perfect, and so sometimes there are false negatives. This is why it is important that if problems continue, individuals seeking care get second opinions or return for evaluation.

If a screening result is positive, then additional assessment is conducted to determine if a diagnosable condition is present. This usually involves a complete symptom history, comparing the symptoms described to known disorders, and doing differential diagnosis. If the information collected does not yield anything, then the screening process resulted in a false positive. If, on the other hand, the collection of information yields enough information to show that the criteria for a condition are satisfied, then a diagnosis is confirmed. The most common diagnostic systems in use are the Diagnostic and Statistical Manual of Mental Disorders: DSM-5 (rev. 5th ed., 2013), and the International Classification of Diseases
(2011).

An example of how diagnosis may work is as follows. A person comes to an emergency room, has alcohol on the breath and no other medical problems, and is screened positive for alcohol problems by a nurse asking a few questions. Additional assessment is done by a psychologist, and they determine that the individual meets the criteria for alcohol dependence. Alcohol dependence is a condition with seven criteria, and an individual who demonstrates three or more in any twelve-month period qualifies for the diagnosis. The patient might report having tolerance (using more to get the same effect), withdrawal (insomnia when stopping using), and a persistent desire to quit, all in the past year. The psychologist then diagnoses the patient with alcohol dependence, and treatment will address that problem.

Uses and Complications

Diagnoses are useful in facilitating effective and quick communications among treatment professionals and other stakeholders in the care of the client. These stakeholders include other treatment providers, insurance companies, researchers in epidemiology and other areas of science, and the clients and their families.

One complication related to diagnoses, however, is that some diagnoses have symptoms that overlap and that methods of differential diagnoses are always developing. As such, it is possible for misdiagnoses to occur. When this occurs, individuals may be treated for the wrong problem, or even overdiagnosed or underdiagnosed, and thus not properly treated. As such, it is often advised for more serious conditions that are costly to treat for patients to use multiple methods of diagnosis and even seek secondary opinions to confirm the diagnosis.

Perspective and Prospects

All forms of healers and health care providers have been involved, since the beginning human societies, in the process of diagnosis in one form or another. As science has advanced in its understanding of causes of death and illness, procedures for diagnosis have also evolved. The procedures and rules for making diagnoses in many areas of health care continue to evolve as new technology and research develop. New technologies take many forms, ranging from improved questionnaires, to new interview procedures, to automated tests and screening online, to the use of new magnetic resonance imaging (MRI), and to even the use of virtual reality-assisted robots entering the body and allowing diagnosticians to see what is happening inside specific organs. All these methods aid in quicker diagnoses and faster paths to effective treatment.

One challenge to evolving diagnostic methods is that the world has become more interconnected over the last century. As a result, it is important for diagnosticians of all types to recognize cultural differences in terms of how symptoms are experienced, expressed, and understood. This is true for both physical and mental health problems. Therefore, relevant screening, assessment, and other diagnostic technologies may need to adjust both in terms of how early symptoms are identified and in how information about diagnoses is conveyed to individuals of different backgrounds. This is the case as well because while diagnosis does involve technology, it is also a procedure involving human communication. As definitions and understandings of illness and health vary by culture, so too will communications about diagnosis need to adjust as cultures and health care providers interact more and more.

Bibliography

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: DSM-5. Rev. 5th ed. Washington, DC: Author, 2013.

Doherty, Gerard M., and Lawrence W. Way. Current Surgical Diagnosis and Treatment. 13th ed. New York: Lange Medical/McGraw-Hill, 2010.

Helman, Cecil G., ed. Culture, Health, and Illness. 5th ed. London: Hodder Education, 2007.

Merck Research Laboratories. The Merck Manual of Diagnosis and Therapy. 19th ed. Whitehouse Station: Author, 2011.

World Health Organization. International Statistical Classification of Diseases and Related Health Problems: 10th Revision–ICD-10. 2010 ed. Geneva, Switzerland: Author, 2011.

What is the California Psychological Inventory (CPI)?

Introduction

The California Psychological Inventory (CPI) is a paper-and-pencil test designed for a comprehensive analysis of traits that describe a normal adult personality. The test itself consists of 462 statements about feelings and opinions, ethical and social attitudes, personal relationships, and characteristic behavior. The testee responds to each item as “true” or “false.” Responses to these statements are analyzed, first of all, according to how well they fit twenty different patterns, each of which corresponds to a specified personality characteristic. The personality characteristics that are assessed include such everyday traits as sociability, dominance, independence, responsibility, self-control, tolerance, and achievement. The individual test-taker’s scores on each scale are evaluated by how these scores compare with the range of scores established by a nationwide comparison group or norm group. Such comparisons also permit evaluating the test-taker on three structural scales that summarize patterns underlying the twenty primary scales at a more abstract and basic level: externality-internality (self-confident assertive extraversion versus introversion), norm-favoring versus norm-questioning (allegiance to the conventional social rules versus its lack), and the degree of one’s “realization” of these tendencies, an index of self-fulfillment or satisfaction.

Development

Harrison Gough, the author of the CPI, began assembling items relevant to the measurement of everyday personality characteristics in the late 1940s. It was 1957, however, before the completed eighteen scales of the CPI were published by Consulting Psychologist Press. In 1987, modest revisions in the scale were initiated. At this time, a few items were modified to reflect cultural changes, and two new primary scales, independence and empathy, were added to the original eighteen. The most important change, however, was the addition of the three summary, structural scales.

Two important principles governed the CPI’s development. The first of these was Gough’s interest in measuring “folk concepts,” characteristics which in many cultures and over centuries made sense to ordinary people. This principle was in contrast to many existing tests that assessed concepts based on psychiatric diagnosis or academic personality theories or were abstracted from a mathematical procedure called factor analysis.

A second guiding principle was that of empirical criterion keying, which means that the validity of items on scales, as well as the scales themselves, should be established by actual research. In such research, items and scales are tested to assure that people who show evident differences in real-life functioning answer the item or the scale in the different ways one would expect. For example, the socialization scale was conceived to measure moral uprightness in the sense of observing society’s rules and customs. One would expect that convicted felons would answer questions on this scale in ways different from Eagle Scouts, and felons would be expected to score much lower on this scale. Research verifying this difference supported the validity of the item and the scale. Hundreds of such predictions derived from the meaning of various CPI scales were tested. Only thereafter was the test considered valid.

Evaluation

A major criticism of the CPI is that there is much overlap between highly similar scales. Dominance and capacity for status, for example, seem to involve only slightly nuanced measurements of almost the same thing. It has been argued, therefore, that the essential information could be gleaned from fewer, simpler scales. Gough answered this criticism by pointing out that everyday descriptions of others by ordinary folk also show this sort of overlap. He also pointed out that the structural scales, added in 1987, permit such simple, efficient description of a personality without depriving the test-taker of the refined and detailed analysis offered by assessing twenty primary traits.

It has also been charged that the CPI is often employed beyond the uses for which its validity has been established. Clinicians are prone to apply the test to abnormal populations for which validity data is incomplete. The test has also been frequently used for people from cultures outside the United States and for minorities within the United States. Although Gough selected his “folk concepts” for their apparent cross-cultural relevance, validity studies in minority and Third World subcultures have been neglected. Interpreting the test results of those from different cultural backgrounds must, therefore, be done with caution.

These admitted limitations could be addressed by adding more studies of minority or clinical populations to the already impressive research with this instrument. For more than half a century, the CPI has served such purposes as predicting vocational choice, academic success, and antisocial behavior. Few other personality tests have been as thoroughly validated. Its many scales permit a detailed description of a person in language that makes sense. Useful and much used, the CPI remains one of the best personality tests for normal populations.

Bibliography

Anastasi, Anne, and Susan Urbina. Psychological Testing. 7th ed. Upper Saddle River: Prentice, 1997. Print.

Bolton, B. “Review of the California Psychological Inventory, Revised Edition.” Eleventh Mental Measurements Yearbook. Ed. J. J. Framer and J. C. Conly. Lincoln: Buros Institute of Mental Measurements, 1992. Print.

Gough, H. G. “The California Psychological Inventory.” Testing in Counseling Practice. Ed. C. E. Walker and V. L. Campbell. Hillsdale.: Erlbaum, 1992. Print.

Gough, H. G., and P. Bradley. “Delinquent and Criminal Behavior as Assessed by the Revised California Psychological Inventory.” Journal of Clinical Psychology 48 (1992): 298–308. Print.

Groth-Marnat, Gary. Handbook of Psychological Assessment. Rev. ed. New York: Wiley, 2009. Print.

Kulas, John T., Richard C. Thompson, and Michael G. Anderson. "California Psychological Inventory Dominance Scale Measurement Equivalence: General Population Normative and Indian, UK, and US Managerial Samples." Educational & Psychological Measurement 71.1 (2011): 245–57. Print.

Megargee, E. I. The California Psychological Inventory Handbook. San Francisco: Jossey, 1977. Print.

Melton, Gary B., et al. Psychological Evaluations for the Courts: A Handbook for Mental Health Professionals and Lawyers. 3d ed. New York: Guilford, 2007. Print.

Nestor, Paul, and Russell K. Schutt. Research Methods in Psychology: Investigating Human Behavior. Los Angeles: SAGE, 2012. Print.

Reynolds, Cecil R., and Ronald B. Livingston. Mastering Modern Psychological Testing: Theory & Methods. Boston: Pearson Education, 2012. Print.

What is a corneal transplantation?

Indications and Procedures

The cornea, which has four distinct layers, is the transparent outer coating of the eye. It serves both to protect the eye and to provide the main refracting surface as light reaches the eye and is transmitted to the lens and retina. Its total thickness is approximately 0.52 millimeter. The layers of specialized tissue are the epithelium, the stroma, Descemet’s membrane, and the endothelium, or inner surface of the cornea.

Several types of corneal disorders may lead to a decision to perform partial or total keratoplasty. Most of these fall under the general term “corneal dystrophy.” The most common, or classical, cases of corneal dystrophy involve the deposit of abnormal material in the cornea, resulting in irritation and eventually damage. Frequently, such disorders stem from genetic factors, making it possible to diagnose the dystrophy during the patient’s childhood and perform a lamellar keratoplasty. Other dystrophies include granular dystrophy and macular dystrophy. The former involves lesions in the center of the cornea, which may multiply and coalesce. At that stage, they may extend into the deeper layers of the stroma, the second layer of the cornea. Macular dystrophy actually begins in the stroma, causing all layers to become opaque.

Entirely different types of disorders that may call for corneal transplantation are interstitial
keratitis (a type of inflammation) and trachoma
. The latter condition can reach near epidemic levels in underdeveloped areas of the world, where low levels of hygiene allow the implantation and rapid multiplication of bacteria in the cornea. The effect is a breakdown of tissue accompanied by the discharge of mucus.

Whether the cornea has been affected by disease or injury, the goal of corneal transplantation is to eliminate any opacity that can hamper vision. The graft operation itself may be described in only a few stages, each marked by the need for a high degree of technical skill to increase the likelihood of success. First, the surgeon must calculate the exact size of the graft in question. This is done through the use of a special tool called a trephine, which will make the cuts to remove both the donor and the host eye corneas. Some trephines are equipped with transparent lenses to give the surgeon maximum levels of accuracy. When the two vital incisions are made, great care is taken to obtain a perfectly vertical cut.

Beginning with this initial stage, the surgeon may add a bubble of air through the incision to protect the endothelium and reduce the likelihood of an immune system reaction once the donor cornea has been transplanted. As the transfer occurs, another air bubble is introduced. After suturing, this bubble will be replaced by a balanced salt solution called acetylcholine.

This suturing, which must be very precise, almost always begins with four sutures at the cardinal points to ensure even tension. The last stage of the operation involves checking the wound for leakage of acetylcholine. This step is necessary not only to avoid infection but also to guard against rejection of the cornea by the host organ.

Uses and Complications

Significant differences in the healing process following corneal transplantation occur according to the method of suturing. A choice is made between a continuing or an interrupted series of sutures around the circumference of the cornea. Interrupted sutures may be preferred if there is a chance of uneven healing of the wound, something the physician may judge following examination of the degree of vascularization in particular corneal graft beds. In some cases, surgeons may opt for double suturing.

The chief complication that can follow corneal transplantation is rejection by the immune system. Surgeons try to obviate this risk by close study of the factors that can affect the receptivity of the eye to a new cornea. Earlier literature on corneal transplantation tended to assume that there was a lack of antigenicity—the production of disease-fighting antigens, or antibodies, as a defense system against viruses, bacteria, or foreign tissues—in the cornea. As ophthalmologists developed a fuller understanding of the immunological role of blood vessels and the lymphatic system, however, the need to give considerable attention to the degree of vascularization of the graft bed zone became more obvious. One method that surgeons can use to reduce antigen activity and enhance host acceptance is part of the transplantation operation itself: constant maintenance of a liquid layer between the host tissue and the new cornea tissue being transplanted. In the late 1990s, researchers at the University of Texas Southwestern Medical Center at Dallas announced the creation of an oral vaccine that may prevent rejection. Processed corneal cells in liquid form fed to laboratory mice produced a marked reduction in rejection rates. Current studies focus on the success of the vaccine with humans.

Although the period for healing and suture removal varies from patient to patient, the surgeon looks for the normal development of a gray-tinged scar tissue in the incision area as a sign of success. Failure, if discovered in time, may lead to a second transplantation attempt.

Perspective and Prospects

The first attempts to perform corneal transplantation—all unsuccessful—date from the nineteenth century. In the 1820s, German doctor F. Reisinger experimented with corneal grafts using rabbits and chickens. In the 1830s, Samuel Bigger of Ireland and R. S. Kissam of the United States tried to pioneer surgical grafts on humans, but both made the error of trying to replace human corneas with animal corneas. Success with living tissue (as opposed to the application of a glass product) finally came in 1905 when Moravian doctor Edward Zirm transplanted a child donor’s cornea to the eye of a chemical burn victim. Zirm’s success was based on cumulative medical knowledge of antiseptics, anesthesia, and technical aids such as the ophthalmoscope and the trephine. After a long period without major changes, in 1935 a Russian scientist named Filatov experimented with two innovations that were copied in other countries: the use of egg membrane to enhance a firm fix and the insertion of a delicate spatula between the cornea and lens to protect the intraocular tissues.

The greatest advances were made soon after antibiotics and steroids were introduced in the 1940s. By the 1950s, the use of extremely delicate surgical needles helped reduce postsurgical rejection rates. Major contributions to the development of delicate surgical instruments were made by the Spanish ophthalmologist Ramón Castroviejo, who performed many operations in the United States. By the 1980s, Castroviejo was urging others to follow the example of Townley Paton, who founded New York’s first eye bank some two decades earlier.

By the turn of the twenty-first century, forty thousand people in the United States had received corneal transplants using cells taken from the eyes of donors who had died. However, many patients with severe corneal damage cannot be helped by conventional cornea transplants. Two research teams, one in Taiwan, at the University of Taoyuan, and one at the University of California at Davis School of Medicine, used stem cells
to continually produce new corneal cells within the eye. In Taiwan, stem cells were placed on amniotic membrane, taken from placentas, to grow the tissue. In California, cells were first grown in laboratory dishes and then placed on the amniotic membrane to produce the tissue, which was transplanted to the damaged corneas. The use of this kind of tissue showed improved or restored vision for patients with corneal damage. While these procedures hold great potential for worldwide application, they have been called “investigational” and by no means eliminate the need for cornea donors.

The prospects for increasingly higher success rates in the field of corneal transplantation are linked to technical progress in donor organ conservation and the level of precision that can be achieved in carrying out transplantation operations.

Bibliography

Brightbill, Frederick S., ed. Corneal Surgery: Theory, Technique and Tissue. 4th ed. St. Louis, Mo.: Mosby, 2009.

De la Rocha, Kelly. "Corneal Transplant." Health Library, February 28, 2012.

Foster, C. Stephen, Dimitri T. Azar, and Claes H. Dohlman, eds. Smolin and Thoft’s The Cornea: Scientific Foundations and Clinical Practice. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2005.

Parker, James N., and Philip M. Parker, eds. The Official Patient’s Sourcebook on Corneal Transplant Surgery. San Diego, Calif.: Icon Health, 2002.

Spaeth, George L., ed. Ophthalmic Surgery: Principles and Practice. 4th ed. Philadelphia: W. B. Saunders, 2012.

Sutton, Amy L., ed. Eye Care Sourcebook: Basic Consumer Health Information About Eye Care and Eye Disorders. 3d ed. Detroit, Mich.: Omnigraphics, 2008.

Vorvick, Linda J. "Corneal Transplant." MedlinePlus, September 3, 2012.

What are protozoa classification and types?

Definition

Protozoa are members of an informal grouping of simple,
usually unicellular, heterotrophic phyla that share similar characteristics. Some
protozoa are pathogenic.

Classification

Traditionally, the kingdom Protista (also known as Protoctista) is
made up of simple eukaryotic organisms that do not fit neatly into any of the
other kingdoms. Often its members are more closely related to members of other
kingdoms than to each other. For many years, this kingdom has been informally
divided into three subgroups: the algae, which are photoautotrophs; the protozoa,
which are ingestive heterotrophs; and the fungus-like protists, which are absorptive heterotrophs. These informal groupings
sometimes break down, as among the euglenids and dinoflagellates, in which there
are species that are photoautotrophs, species that are either absorptive or
ingestive heterotrophs, and species that can switch between autotrophy and
heterotrophy. Most taxonomists agree that the kingdom Protista is artificial (not
monophyletic) and should be split into multiple kingdoms.

Like the taxonomy of the protists in general, the taxonomy of the protozoa is continually changing, as more species are subjected to rigorous cytochemical and genomic analysis. All protozoa are nucleated and are considered to be eukaryotic, although some may show both eukaryotic and prokaryotic characteristics. The normal classification hierarchy that starts with kingdom is often not used with Protista. The species are simply placed in taxa according to possible evolutionary and biochemical similarities without labeling the taxa.

Characteristics and Habitat

Protists can live in fresh- or marine-aquatic habitats, in damp soil, or in other organisms such as parasitic or commensal organisms. All can reproduce asexually, while some, like the alveolates, can also reproduce sexually.

Most excavates reproduce asexually and have flagella, a cytoskeleton of
microtubules, modified mitochondria, and a large ventral groove used in feeding.
Diplomonads, like Giardia spp., have two haploid nuclei, multiple
flagella, and a modified mitochondrion, the mitosome, that is unable to perform
cellular respiration because it lacks electron transport. All are anaerobic with
bacteria-like anaerobic metabolism, and some are parasitic in the guts of animals.
The related parabasalids also have a modified mitochondria-like structure called a
hydrogenosome. This double membrane structure produces hydrogen as a by-product of
the oxidation of pyruvate, much like hydrogen-producing bacteria. Parabaslids also
have a prominent Golgi body (or Golgi apparatus) called the parabasal body that is
involved in protein synthesis. Parabasalids also have an undulating
membrane thought to be involved in locomotion. Many digest cellulose in the guts
of termites and ruminants, while others, such as Trichomonas
spp., are commensal or parasitic in animals.

The euglenoid kinetoplastids have a single large mitochondrion with discoid inner membranes. The mitochondrial deoxyribonucleic acid (DNA) is enclosed in a structure called the kinetoplast. Kinetoplastids also have Golgi bodies and a haploid nucleus. Some are parasitic, such as Trypanosoma spp., Leishmania spp., and Chrythidia spp. Among the nonparasitic kinetoplastids are some of the few colonial protozoa.

Alveolates are recognized by their alveoli, the membrane-bound vesicles just
inside the plasma membrane. Almost all have plastids of red algal origin. Among
the heterotrophic dinoflagellates are no important human pathogens, although many
photosynthetic dinoflagellates produce toxins that can affect humans and other
animals. All apicomplexans, formerly called sporozoa, are nonmotile parasites,
contain a modified plastid called the apicoplast, produce spores, and have sexual
reproduction. The most prevalent protistan disease of humans, malaria, is
caused by the apicomplexan Plasmodium spp. All ciliates, as the
name implies, have cilia, either on the entire surface or clustered in tufts or
rings. They also have two types of nuclei, macronuclei and micronuclei, and
reproduce both sexually and asexually. All, except for the occasionally pathogenic
Balantidium, are nonpathogenic.

Amebozoans all have lobe- or tube-like pseudopodia for locomotion and lack cilia or flagella at any stage of the life cycle. Most cannot reproduce sexually. The nucleus has a prominent nucleolar region called the endosome, and many can produce resting stages called cysts. Gymnamebas, like Amoeba proteus, are free-living, unicellular amoeba that produce multiple pseudopods. They usually are aquatic and feed on bacteria or detritus. Entamoeba spp. are also unicellular, produce a single pseudopod at a time, and are parasitic in animals.

Impact

Many protozoa are parasitic pathogens. They cause a number of
diseases in humans and exact a huge toll on the peoples of developing countries.
The various Plasmodium spp., for example, cause the different
forms of malaria, a disease that has had a devastating effect on the developing
world.

The protozoan Giardia intestinalis (also known as G.
lamblia) causes diarrhea in hikers and backpackers, especially, and
Trichomonas vaginalis causes vaginitis and
urethritis. Trypanosomes are responsible for sleeping
sickness (T. brucei) and Chagas’
disease (T. cruzi), and because they can
change their surface proteins, they often elude the host’s immune
system. Leishmania spp. most commonly cause
cutaneous leishmaniasis, an ulcerative disease of the skin.
Toxoplasma gondii can be transmitted to humans through cat
feces and can cause toxoplasmosis. Entamoeba
hystolytica is the only major amebic pathogen in humans and causes
amebic
dysentery.

Bibliography

Katz, Laura, and Debashish Bhattacharya, eds. Genomics and Evolution of Microbial Eukaryotes. New York: Oxford University Press, 2008. A collection of articles about the modern evolutionary taxonomy of the protists.

Margulis, Lynn, and Michael Chapman. Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth. 4th ed. New York: Academic Press/Elsevier, 2009. Describes many protozoa, including their morphology and natural history.

Parker, Steve. Protozoans, Algae, and other Protists. Mankato, Minn.: Compass Point Books, 2009. Although written for middle-school students, this book provides good coverage for all general readers studying the basics of protozoa.

Rogers, Kara. Fungi, Algae, and Protists. New York: Britannica Educational Press, 2011. A middle- and high-school-level book with broad coverage of protozoa.

What are carbohydrates? |

Digestion and Absorption

Dietary carbohydrates include monosaccharides, such as glucose, fructose, and lactose; disaccharides (two monosaccharides linked together), such as sucrose and lactose; and polysaccharides (many monosaccharides linked together in polymers), such as starches and fiber.

Starches are first broken down in the mouth by salivary alpha-amylase and then in the small intestine by alpha-amylases of both salivary and pancreatic origin. The resulting simpler sugars
are further digested by enzymes linked to the inner lining of the small intestine: maltase, sucrase, and trehalase, which yield absorbable monosaccharides. These sugars cross the cells lining the small intestine via specialized molecular transport mechanisms and then diffuse into the intestinal capillaries and reach the bloodstream.

Metabolism

In the body, the main role of carbohydrates is energy production and storage. Carbohydrates can also be joined to proteins (glycoproteins, for cell-cell interactions) or fatty acids (glycolipids, which provide energy and can be markers for cellular recognition).

The body converts most digestible carbohydrates into glucose, which is a universal energy source for cells. Excess glucose is stored as glycogen (glycogenesis), which can then be broken down (glycogenolysis) when energy is needed. Glucose is maintained at a constant level in the blood by the interplay of insulin, gulcagon, and other hormones.

Carbohydrate-related diseases are often genetic in nature, linked to inborn errors in enzymes or cellular transporters. Examples are galactosemia, glycogen storage diseases, and lactose intolerance. Diabetes mellitus is a metabolic disorder characterized by excessive blood glucose. Type 1 diabetes is caused by insulin deficiency; type 2 can be the result of insulin resistance, impaired insulin secretion, and increased glucose production.

According to current recommendations, carbohydrates, preferably starches and natural sugars, should represent 40 to 60 percent of total calorie intake. Refined simple sugars provide calories but very little nutrition, and their intake should therefore be limited.

Perspective and Prospects

Food availability in developed countries has reached unprecedented levels, and the per capita consumption of carbohydrates, particularly in the form of refined sugars, increased dramatically in the late twentieth and early twenty-first centuries. Since the 1990s, the incidence of obesity has been climbing steadily, and so has the incidence of diabetes and related health problems. Current research in nutrition and carbohydrate metabolism is addressing the problem, which has reached epidemic proportions. Great progress is being made in dietary manipulations and drug development.

Bibliography

A.D.A.M. Medical Encyclopedia. "Carbohydrates." MedlinePlus, May 16, 2012.

Centers for Disease Control and Prevention. "Carbohydrates." Centers for Disease Control and Prevention, December 11, 2012.

Mayo Clinic. "Carbohydrates: How Carbs Fit into a Healthy Diet." Mayo Foundation for Medical Education and Research, February 8, 2011.

McGraw-Hill Encyclopedia of Science and Technology. 10th ed. 20 vols. New York: McGraw-Hill, 2007.

Sherwood, Lauralee. “The Digestive System.” In Human Physiology: From Cells to Systems. 7th ed. Pacific Grove, Calif.: Brooks, 2010.

Stanhope, K. L., and P. J. Havel. “Fructose Consumption: Considerations for Future Research on Its Effects on Adipose Distribution, Lipid Metabolism, and Insulin Sensitivity in Humans.” Journal of Nutrition 139, no. 6 (June, 2009): 1236S–41S.

What are ear infections and disorders?

Causes and Symptoms

The hearing mechanism, one of the most intricate and delicate structures of the human body, consists of three sections: the outer ear, the middle ear, and the inner ear. The outer ear converts sound waves into the mechanical motion of the eardrum (tympanic membrane), and the middle ear transmits this mechanical motion to the inner ear, where it is transformed into nerve impulses sent to the brain.

The outer ear consists of the visible portion, the ear canal, and the eardrum. The middle ear is a small chamber containing three tiny bones—the auditory ossicles, termed malleus (hammer), incus (anvil), and stapes (stirrup)—which transmit the vibrations of the eardrum (attached to the hammer) into the inner ear. The chamber is connected to the back of the throat by the Eustachian tube, which allows equalization with the external air pressure. The inner ear, or cochlea, is a fluid-filled cavity containing the complex structure necessary to convert the mechanical vibrations of the cochlear fluid into nerve pulses. The cochlea, shaped something like a snail’s shell, is divided lengthwise by a slightly flexible partition into upper and lower chambers. The upper chamber begins at the oval window, to which the stirrup is attached. When the oval window is pushed or pulled by the stirrup, vibrations of the eardrum are transformed into cochlear fluid vibrations.

The lower surface of the cochlear partition, the basilar membrane, is set into vibration by the pressure difference between the fluids of the upper and lower ducts. Lying on the basilar membrane is the organ of Corti, containing tens of thousands of hair
cells attached to the nerve transmission lines leading to the brain. When the basilar membrane vibrates, the cilia of these cells are bent, stimulating them to produce electrochemical impulses. These impulses travel along the auditory nerve to the brain, where they are interpreted as sound.

Although well protected against normal environmental exposure, the ear, because of its delicate nature, is subject to various infections and disorders. These disorders, which usually lead to some
hearing loss, can occur in any of the three parts of the ear.

The ear canal can be blocked by a buildup of waxy secretions or by infection. Although
earwax serves the useful purpose of trapping foreign particles that might otherwise be deposited on the eardrum, if the canal becomes clogged with an excess of wax, less sound will reach the eardrum, and hearing will be impaired.

Swimmer’s ear, or
otitis externa, is an inflammation caused by contaminated water that has not been completely drained from the ear canal. A moist condition in a region with little light favors fungal growth. Symptoms of swimmer’s ear include an itchy and tender ear canal and a small amount of foul-smelling drainage. If the canal is allowed to become clogged by the concomitant swelling, hearing will be noticeably impaired.

A perforated eardrum may result from a sharp blow to the side of the head, an infection, the insertion of objects into the ear, or a sudden change in air pressure (such as a nearby explosion). Small perforations are usually self-healing, but larger tears require medical treatment.

Inflammation of the middle ear, acute
otitis media, is one of the most common ear infections, especially among children. Infection usually spreads from the throat to the middle ear through the Eustachian tube. Children are particularly susceptible to this problem because their short Eustachian tubes afford bacteria in the throat easy access to the middle ear. When the middle ear becomes infected, pus begins to accumulate, forcing the eardrum outward. This pressure stretches the auditory ossicles to their limit and tenses the ligaments so that vibration conduction is severely impaired. Untreated, this condition may eventually rupture the eardrum or permanently damage the ossicular chain. Furthermore, the pus from the infection may invade nearby structures, including the facial nerve, the mastoid bones, the inner ear, or even the brain. The most common symptom of otitis is a sudden severe pain and an impairment of hearing resulting from the reduced mobility of the eardrum and the ossicles.

Secretory otitis media is caused by occlusion of the Eustachian tube as a result of conditions such as a head cold, diseased tonsils and adenoids, sinusitis, improper blowing of the nose, or riding in unpressurized airplanes. People with allergic nasal blockage are particularly prone to this condition. The blocked Eustachian tube causes the middle-ear cavity to fill with a pale yellow, noninfected discharge which exerts pressure on the eardrum, causing pain and impairment of hearing. Eventually, the middle-ear cavity is completely filled with fluid instead of air, impeding the movement of the ossicles and causing hearing impairment.

A mild, temporary hearing impairment resulting from airplane flights is termed aero-otitis media. This disorder results when a head cold or allergic reaction does not permit the Eustachian tube to equalize the air pressure in the middle ear with atmospheric pressure when a rapid change in altitude occurs. As the pressure outside the eardrum becomes greater than the pressure within, the membrane is forced inward, while the opening of the tube into the upper part of the throat is closed by the increased pressure. Symptoms are a severe sense of pressure in the ear, pain, and hearing impairment. Although the pressure difference may cause the eardrum to rupture, more often the pain continues until the middle ear fills with fluid or the tube opens to equalize pressure.

Chronic otitis media may result from inadequate drainage of pus during the acute form of this disease or from a permanent eardrum
perforation that allows dust, water, and bacteria easy access to the middle-ear cavity. The main symptoms of this disease are fluids discharging from the outer ear and hearing loss. Perforations of the eardrum result in hearing loss because of the reduced vibrating surface and a buildup of fibrous tissue that further induces conductive losses. In some cases, an infection may heal but still cause hearing loss by immobilizing the ossicles. There are two distinct types of chronic otitis, one relatively harmless and the other quite dangerous. An odorless, stringy discharge from the mucous membrane lining the middle ear characterizes the harmless type. The dangerous type is characterized by a foul-smelling discharge coming from a bone-invading process beneath the mucous lining. If neglected, this process can lead to serious complications, such as meningitis, paralysis of the facial
nerve, or complete sensorineural deafness.

The ossicles may be disrupted by infection or by a jarring blow to the head. Most often, a separation of the linkage occurs at the weakest point, where the anvil joins the stirrup. A partial separation results in a mild hearing loss, while complete separation causes severe hearing impairment.

Disablement of the mechanical linkage of the middle ear may also occur if the stirrup becomes calcified, a condition known as otosclerosis. The normal bone is resorbed and replaced by very irregular, often richly vascularized bone. The increased stiffness of the stirrup produces conductive hearing loss. In extreme cases, the stirrup becomes completely immobile and must be surgically removed. Although the exact cause of this disease is unknown, it seems to be hereditary. About half of the cases occur in families in which one or more relatives have the same condition, and it occurs more frequently in females than in males. There is also some evidence that the condition may be triggered by a lack of fluoride in drinking water and that increasing the intake of fluoride may retard the calcification process.

Tinnitus
is characterized by ringing, hissing, or clicking noises in the ear that seem to come and go spontaneously without any sound stimulus. While tinnitus is not a disease of the ear, it is a common symptom of various ear problems. Possible causes of tinnitus are earwax lodged against the eardrum, a perforated or inflamed eardrum, otosclerosis, high aspirin dosage, or excessive use of the telephone. Tinnitus is most serious when caused by an inner-ear problem or by exposure to very intense sounds, and it often accompanies hearing loss at high frequencies.

Ménière’s disease is caused by production of excess cochlear fluid, which increases the pressure in the cochlea. This condition may be precipitated by allergy, infection, kidney disease, or a number of other causes, including severe stress. The increased pressure is exerted on the walls of the semicircular canals as well as on the cochlear partition. The excess pressure in the semicircular canals (the organs of balance) is interpreted by the brain as a rapid spinning motion, and the victim experiences abrupt attacks of
vertigo and nausea. The excess pressure in the cochlear partition has the same effect as a very loud sound and rapidly destroys hair cells. A single attack causes a noticeable hearing loss and could result in total deafness without prompt treatment.

Of all ear diseases, damage to the hair cells in the cochlea causes the most serious impairment. Cilia may be destroyed by high fevers or from a sudden or prolonged exposure to intensely loud sounds. Problems include destroyed or missing hair cells, hair cells that fire spontaneously, and damaged hair cells that require unusually strong stimuli to excite them. At the present time, there is no means of repairing damaged cilia or of replacing those that have been lost.

Viral nerve deafness is a result of a viral infection in one or both ears. The mumps virus is one of the most common causes of severe nerve damage, with the measles and influenza viruses as secondary causes.

Ototoxic (ear-poisoning) drugs can cause temporary or permanent hearing impairment by damaging auditory nerve tissues, although susceptibility is highly individualistic. A temporary decrease of hearing (in addition to tinnitus) accompanies the ingestion of large quantities of aspirin or quinine. Certain antibiotics, such as those of the mycin family, may also cause permanent damage to the auditory nerves.

Repeated exposure to loud noise (in excess of 90 decibels) will cause a gradual deterioration of hearing by destroying cilia. The extent of damage, however, depends on the loudness and the duration of the sound. Rock bands often exceed 110 decibels; farm machinery averages 100 decibels.

Presbycusis (hearing loss with age) is the inability to hear high-frequency sounds because of the increasing deterioration of the hair cells. By age thirty, a perceptible high-frequency hearing loss is present. This deterioration progresses into old age, often resulting in severe impairment. The problem is accelerated by frequent unprotected exposure to noisy environments. The extent of damage depends on the frequency, intensity, and duration of exposure, as well as on the individual’s predisposition to hearing loss.

Treatment and Therapy

The simplest ear problems to treat are a buildup of earwax, swimmer’s ear, and a perforated eardrum. A large accumulation of wax in the ear canal is best removed by having a medical professional flush the ear with a warm solution under pressure. One should never attempt to remove wax plugs with a sharp instrument. A small accumulation of earwax may be softened with a few drops of baby oil left in the ear overnight and then washed out with warm water and a soft rubber ear syringe. Swimmer’s ear can usually be prevented by thoroughly draining the ears after swimming. The disease can be treated with an application of antibiotic ear drops after the ear canal has been thoroughly cleaned. A small perforation of the eardrum will usually heal itself. Larger tears, however, require an operation, tympanoplasty, that grafts a piece of skin over the perforation.

Fortunately, the bacteria that usually cause acute otitis respond quickly to antibiotics. Although antibiotics may relieve the symptoms, complications can arise unless the pus is thoroughly drained. The two-part treatment—draining the fluid from the middle ear and antibiotic therapy—resolves the acute otitis infection within a week. Secretory otitis is cured by finding and removing the cause of the occluded Eustachian tube. The serous fluid is then removed by means of an aspirating needle or by an incision in the eardrum so as to inflate the tube by forcing air through it. In some cases, a tiny polyethylene tube is inserted through the eardrum to aid in reestablishing normal ventilation. If the Eustachian tube remains inadequate, a small plastic grommet may be inserted. The improvement in hearing is often immediate and dramatic. The pain and hearing loss of aero-otitis is usually temporary and disappears of its own accord. If, during or immediately after flight, yawning or swallowing does not allow the Eustachian tube to open and equalize the pressure, medicine or surgical puncture of the eardrum may be required. The harmless form of chronic otitis is treated with applied medications to kill the bacteria and to dry the chronic drainage. The eardrum perforation may then be closed to restore the functioning of the ear and to recover hearing. The more dangerous chronic form of this disease does not respond well to antibacterial agents, but careful x-ray examination allows diagnosis and surgical removal of the bone-eroding cyst.

Ossicular interruption can be surgically treated to restore the conductive link by repositioning the separated bones. This relatively simple operation has a very high success rate. Otosclerosis is treated by operating on the stirrup in one of several ways. The stirrup can be mechanically freed by fracturing the calcified foot plate or by fracturing the foot plate and one of the arms. Although this operation is usually successful, recalcification often occurs. Alternatively, the stirrup can be completely removed and replaced with a prosthesis of wire or silicon, yielding excellent and permanent results.

Since tinnitus has many possible, and often not readily identifiable, causes, few cases are treated successfully. The tinnitus masker has been invented to help sufferers live with this annoyance. The masker, a noise generator similar in appearance to a hearing aid, produces a constant, gentle humming sound that masks the tinnitus.

Ménière’s disease, usually treated with drugs and a restricted diet, may also require surgical correction to relieve the excess pressure in severe cases. If this procedure is unsuccessful, the nerves of the inner ear may be cut. In drastic cases, the entire inner ear may be removed.

Presently there is no cure for damaged hair cells; the only treatment is to use a hearing aid. It is more advantageous to take preventive measures, such as reducing noise at the source, replacing noisy equipment with quieter models, or using ear-protection devices. Recreational exposure to loud music should be severely curtailed, if not completely eliminated.

Perspective and Prospects

For many centuries, treatment of the ear was associated with that of the eye. In the nineteenth century, the development of the laryngoscope (to examine the larynx) and the otoscope (to examine the ears) enabled doctors to examine and treat disorders such as croup, sore throat, and draining ears, which eventually led to the control of these diseases. As an offshoot of the medical advances made possible by these technological devices, the connection between the ear and throat became known, and otologists became associated with laryngologists.

The study of ear diseases did not develop scientifically until the early nineteenth century, when Jean-Marc-Gaspard Itard and Prosper Ménière made systematic investigations of ear physiology and disease. In 1853, William R. Wilde of Dublin published the first scientific treatise on ear diseases and treatments, setting the field on a firm scientific foundation. Meanwhile, the scientific investigation of the diseased larynx was aided by the laryngoscope, invented in 1855 by Manuel Garcia, a Spanish singing teacher who used his invention as a teaching aid. During the late nineteenth century, this instrument was adopted for detailed studies of larynx pathology by Ludwig Türck and Jan Czermak, who also adapted this instrument to investigate the nasal cavity, which established the link between laryngology and rhinology. Friedrich Voltolini, one of Czermak’s assistants, further modified the instrument so that it could be used in conjunction with the otoscope. In 1921, Carl Nylen pioneered the use of a high-powered binocular microscope to perform ear surgery. The operating microscope opened the way for delicate
operations on the tiny bones of the middle ear. With the founding of the American Board of Otology in 1924, otology (later otolaryngology) became the second medical specialty to be formally established in North America.

Prior to World War II, the leading cause of deafness was the various forms of ear infection. Advances in technology and medicine have now brought ear infections under control. Today the leading type of hearing loss in industrialized countries is conductive loss, which occurs in those who are genetically predisposed to such loss and who have had lifetime exposure to noise and excessively loud sounds. In the future, protective devices and reasonable precautions against extensive exposure to loud sounds should reduce the incidence of hearing loss to even lower levels.

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