Saladin/Nolan

Clinical Applications Manual

ANSWERS TO END-OF-CHAPTER QUESTIONS

Chapter 1

1. The mental and physiological signs of the disease result from ingestion and inhalation of lead by the children. These children were exposed to lead (and other heavy metals) at the manufacturing plant where they scavenged materials.

2. The children’s risk factors for lead poisoning include the presence of lead-based paint, dust containing crushed and pulverized paint chips, and metal-contaminated soil around the factory. The risk factor for the elderly woman is her habit of chewing on the lead foil wrapping from wine bottles.

3. Lead is a poison but not a toxin, because toxins are of animal or plant origin.

4. Idiopathic diseases are those with no known cause. Since there is an identifiable cause in all the cases in this scenario, none of these people has idiopathic lead poisoning.

5. Yes, lead poisoning could be considered a syndrome. The signs, symptoms and changes in physiology are characteristic of lead poisoning.

6. Since blood is a tissue, the diagnostic findings on the blood (traces of lead and reduced RBC count) are histopathological.

7. High morbidity? Yes, among the children but not among adults, because a large percentage of children in the housing project exhibit signs of the disease. High mortality? No, because no deaths were reported. High prevalence? Yes, high morbidity in this case is equivalent to the high prevalence of the disease among the children. High incidence? There is insufficient information to evaluate incidence in this case, because no data were available to document the number of new cases in a given time period.

8. Yes, lead poisoning among the children of this community can be considered an epidemic because it occurs in a far higher percentage of individuals (more than 70 of the 112 children examined) than it does in the general population. Lead poisoning is not an infectious disease, however, because it is not caused by an infectious agent (such as a virus or bacterium) and it is not transmitted from person to person.

9. (a) joint pain = symptom; (b) difficulty walking = sign; (c) excessive salivation = sign; (d) personality changes = sign; (e) low RBC count = sign; (f) subnormal intelligence = sign; (g) dimness of vision = symptom; (h) lead in the urine = sign. (Remember that the criterion for a symptom is something that can only be known by the patient, while a sign is capable of being objectively verified by another observer.)

10. You could advise the daughter to buy wine without lead foil or to dispose of the foil wrappers carefully so that her mother cannot get at them. You might also do a blood test on the mother to check for iron-deficiency anemia and prescribe a multivitamin and mineral supplement if necessary. If the mother insists on chewing on something, you could recommend substituting something nontoxic such as ice or gum.

Chapter 2

1. Ellen’s symptoms include sore throat, pain while swallowing, headache, exhaustion, and the feeling of being cold. Her hoarseness, flushed face, watery eyes, and fever (elevated body temperature) are specific signs that she is ill.

2. Ellen’s chief complaint is a sore throat.

3. Questions that could be asked of Ellen include: When did you first develop a sore throat? Have you recently been around anyone with similar symptoms? Have you had trouble eating or drinking? How long have you had a headache? Is the headache worse in the presence of light?

4. Ellen’s risk factors for disease include lack of sleep, inadequate diet, contact with a roommate who may have transmitted the illness, stress (due to final exams and other factors), exertion, and exposure to inclement weather.

5. Yes, a sphygmomanometer will be needed because it is used to determine blood pressure, which is one of the vital signs and therefore a routine step in the initial examination of all patients.

6. When feeling the sides of Ellen’s neck, the physician is using palpation.

7. Using the stethoscope to listen to Ellen’s heart and lungs is an example of auscultation.

8. An otoscope is used to examine the ears.

9. The physician is obtaining cells for culture to test for the presence of microorganisms that may be causing the disease. In this case, he is most likely going to test for Streptococcus, a bacterium commonly associated with throat infections (strep throat).

10. The physician would most likely complete a physical examination and order additional tests, such as urinalysis and various blood tests, including a CBC.

Chapter 3

1. Phase I is not designed to show whether the drug has an effect on cancer pain. It is designed only to establish that there are no unacceptable side effects of the drug and to establish the maximum safe dosage. The volunteers in phase I are not suffering from cancer or pain. Therefore, there is no harm in the subjects knowing that they are receiving the drug. Phase II, however, is designed to determine whether the drug really has a measurable effect on the pain felt by cancer patients. Pain relief is highly subject to psychosomatic effects, so a placebo group is needed to control for this effect. Otherwise, if patients reported that NoPain did not relieve their discomfort, the researchers would have no way of knowing whether this relief was due to a pharmacological action of NoPain or merely to a placebo (psychosomatic) effect.

2. Variation from patient to patient and atypical responses would have a strong effect on averages based on a small number of patients. Testing a small sample of people also may fail to reveal side effects and unusual responses that could affect a significant number of people if a drug is approved for the market and used by millions of people. Therefore, clinical trials must use a large enough sample that such responses have a high probability of being detected and individual variations do not greatly skew the data and lead to false conclusions.

3. NoPain is a palliative treatment because it is able to relieve patients’ pain and thereby make them more comfortable, but not able to cure or prevent their cancer.

4. Explain to Mae that U.S. regulations governing the safe development of drugs require years of clinical trials and the expenditure of millions of dollars before the drug company can market the product. Also, at any point during the process, the drug may fail to qualify for human use, in which case the expenses incurred during clinical trials may never be recovered. Even after a drug is approved, unexpected side effects can arise and force a company to withdraw it from the market. Therefore, drug companies must price a drug so as to recover the costs of its development, cover the risks of failure, and still make a sufficient profit to stay in business.

5. Available sterilization techniques include pressurized steam, dry heat, irradiation, and chemicals. The technique used depends on what equipment is available and how soon the sterile swabs are needed. Pressurized steam and irradiation are both relatively easy to accomplish with the appropriate equipment, and the sterilization process can be completed in less than 2 hours in most cases. Chemical sterilization, especially with alcohol and phenol, would not be suitable because it most often requires placing the item to be sterilized in direct contact with the chemical. In the case of cotton swabs, the chemical would then come in contact with patients’ skin.

6. Immunotherapy, chemotherapy, and radiotherapy are all used to treat cancer.

7. Although the hospital tries to minimize the presence and spread of infectious agents in many different ways, it is impossible to maintain a sterile environment in a hospital room. This infection probably occurred when the patient was exposed to a person carrying the infectious agent, such as another patient or a visitor, or the infectious agent may have been airborne.

8. The physician would most likely use an injection to rapidly produce a high circulating antibiotic concentration. For a more prolonged dose, the physician would probably follow the injection with oral medication to be taken at regular intervals.

9. International units provide a way of determining the response expected from a given amount of a compound. The biological activity of the same compound may differ based on the means of preparation. As a result, using the mass (weight) may not produce reproducible effects. Therefore, international units provide a means of producing a uniform response, regardless of the means of preparation.

10. Gastrotomy refers to an incision in the stomach. Gastrectomy means removal of part or all of the stomach. Gastroscopy means viewing the stomach, normally with an endoscope. Gastrocentesis means puncturing the stomach to remove fluid. Gastroclysis means irrigating the stomach with fluid.

Chapter 4

1. bradycardia = slow heart rate, usually less than 60 beats per minute; hypotension = decreased blood pressure; lymphadenopathy = chronic or excessive enlargement of the lymph nodes; cervical lymph nodes = lymph nodes located in the cervical region of the body; inguinal lymph nodes = lymph nodes located in the inguinal region; albuminuria = the presence of albumin in the urine; petechiae = small, purplish spots on the skin resulting from hemorrhages.

2. Jason and Mary’s WBC counts are abnormally low. They are exhibiting leukopenia. The change in white blood cell count is relevant to the diagnosis because it suggests a pathology affecting the immune system.

3. Attempts to control dengue fever usually focus on controlling the reproduction of the Aedes mosquito, the vector for the causative agent, Flavivirus. Methods of limiting the mosquito population include minimizing the presence of standing water and using insecticides. Tourists might be advised to avoid areas of known mosquito infestation, to use insect repellent, and if possible to sleep under bed nets at night as a protective barrier against insects.

4. The invasion of a cell by viruses increases the cell’s osmolarity. This occurs because the viruses act like any other particle. As the number of viruses increases, the number of particles in the cells increases as well. This increased particle number gives the cells an increased osmolarity that could eventually lead to cellular lysis.

5. Cells with high metabolic rates are highly dependent on ATP and therefore on functionally normal mitochondria. Thus, they are the most vulnerable to cytopathies that disturb mitochondrial function.

6. Prokaryotic organisms are all bacteria and are unicellular. All multicellular organisms are eukaryotic. Parasitic worms and arthropods are multicellular; therefore, they are eukaryotic.

7. Children do not inherit Kearns-Sayre syndrome from their fathers because only the mitochondria in the egg cell are passed on to the next generation. The mitochondria of the sperm cell that fertilizes the egg do not survive.

8. Since giardiasis is transmitted through water contaminated with sewage, a knowledgeable epidemiologist would hypothesize that the school’s water supply is contaminated with sewage and the students are getting Giardia from sources such as the drinking fountains or cafeteria food. Since the school is old and run-down, it is possible that its water and sewage lines are not in good repair, and these should be inspected for leaks.

9. The main risk factor for Gaucher disease is family history because it is a hereditary disease; this risk factor is unavoidable. A main risk factor for malaria is exposure to the vector, which is avoidable. Risk factors for toxoplasmosis include diet (undercooked meat, unpasteurized milk) and exposure to infected cats or their feces; these risk factors are avoidable.

10. If this disorder were expressed in the zygote (fertilized egg), the first cell divisions after fertilization could not occur. All such zygotes would perish before a woman was even aware of her pregnancy. Some genes, however, are expressed later in life or only under certain conditions. In such a case, the hereditary disorder might affect growth at any stage from embryo to adult, or it might affect the growth of selected organs. It could cause sterility due to the inability to produce eggs and sperm through meiosis, or it could produce premature aging because organs would be unable to replace cells at a sufficient rate to keep pace with their normal death.

Chapter 5

1. The following individuals demonstrate principle 1: Bill, Terry, Greg, and Jenny.

2. The following individuals represent principle 2: Carl, Terry, and Greg. (The fact that Terry and Greg have the disease whereas their father was not even a carrier is just as relevant as the fact that Bill had the disease but did not pass it on to his son Carl.)

3. The following individuals represent principle 3: Florence, Jessica, Terry, and Greg.

4. Males cannot carry hemophilia because it is an X-linked disease and males only have a single X chromosome. If the male has an X with the recessive allele for hemophilia, he has the disease.

5. The probability of Marcy and Tom having a child with hemophilia is 12.5%. This is because Marcy has a 50% chance of being a carrier (receiving a recessive X allele from her mother). Marcy’s children in turn have a 50% chance of receiving a copy of the X chromosome with the recessive allele from her. Thus, there is a 25% chance that any of the children would receive a copy of the recessive X allele from Marcy—(0.5)(0.5) = 0.25. Tom does not have hemophilia, so we know that the gene on his X chromosome is normal. Thus, there is no chance that his daughters could receive an X chromosome with the allele for hemophilia from him. Therefore, only Marcy and Tom’s sons could have hemophilia. Since there is a 50% chance that any child will be male, the total probability of Marcy and Tom having a child with hemophilia is 12.5%—(0.5)(0.5)(0.5) = .125.