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4 Aug 2018

Case Study Section 4 – Nitrogen Metabolism Based on “A Sickeningly Sweet Baby Boy: A Case Study on Autosomal Recessive Inheritance” by Jacqueline Washington and Anne Zayaitz (National Center for Case Study Teaching in Science) The Patient: Mathew Miller is a 7-day-old infant that is rushed to the emergency room by his parents Emma and Jacob Miller, Mennonites from Lancaster County, PA. Emma’s pregnancy and delivery with Mathew was normal but he started having trouble nursing and now has completely stopped feeding. By the time they reach the emergency room Mathew’s limbs were rigid and he had had a seizure. The initial examination showed no infection and his x-rays were normal. The family history collected by the Doctor revealed that Emma and Jacob had had a previous son, Samuel that died at 9 days-of-age. There also is a history of unexplained childhood mortality on both sides of the family; Emma’s mother had two sisters who died in the first year of their lives and Jacob’s father had a sister who died at 7 months of age. Emma also points out to the Doctor that Mathew’s diaper has a funny smell to it. Blood and urine samples were taken for testing and skin biopsies from Mathew, Emma, and Jacob were taken and tested for enzyme activity. The tests results showed that:

• Mathew’s urine had elevated levels of the branched chain amino acids and their α-keto acid derivatives (which caused the sweet smell in his diapers)

• Both Emma and Jacob’s skin biopsies had nearly normal levels of branched chain amino acid metabolism/enzyme activity

• Mathew’s enzyme activity was less than 2% of normal

Question 1: What is the most likely diagnosis for Mathew?

A. Argininemia

B. Diabetes mellitus '

C. Maple syrup urine disease

D. Phenylketonuria

Question2: What enzyme did the skin biopsy test measure?

A. Carbamoyl phosphate synthetase I

B. Alanine aminotransferase

C. Phenylalanine hydroxylase

D. Branched-chain α-keto acid dehydrogenase complex

Question 3: This enzyme functions VERY similarly to two other enzymes that we have discussed, what are they?

A. Phosphofructokinase-1 and fructose 1,6-bisphosphatase (FBPAse-1)

B. Pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex

C. Urease and arginase

D. Isocitrate dehydrogenase and malate dehydrogenase

Question 4: How did Mathew (and presumably Samuel) inherit the disease if both Emma and Jacob have normal enzyme activity levels?

A. Emma and Jacob must both be carriers for the disease but their one normal gene is enough to maintain enzyme activity levels.

B. The disease can happen spontaneously, there is no genetic link.

C. Jacob is not really the father of the boys.

D. The disease can skip generations.

Question 5: What would be the best diet for Mathew to follow to control his disease?

A. Atkin’s diet (low carbohydrates, high fat, and high protein)

B. Low protein

C. Low fat

D. No special diet will control the disease

Over the next 4 years Mathew’s metabolic disease is controlled by his special diet but he still suffers approximately 3 metabolic crises a year. These occur when amino acids accumulate in his blood leading to the swelling of his brain. Even something as simple as a cold or the flu can affect his amino acid levels and send his metabolism into crisis. Jacob and Emma decide that “We cannot continue to live in constant fear that a minor infection or a simple cold or ear infection could kill our son. Even though we are doing everything we are supposed to, he is still getting sick and we are afraid we may lose Mathew.” They learn that some children with Mathew’s disease have undergone liver transplants and are effectively cured.

Question 6: How/why would a liver transplant effectively cure Mathew’s condition?

A. A new liver would be able to spread it’s genes throughout the body and correct the genetic disorder.

B. A new liver would more effectively respond to metabolic hormonal control.

C. A new liver would express the functional enzyme needed to metabolize the amino acids causing Mathew’s condition.

D. A new liver would produce more hemoglobin to transport oxygen more effectively.

The family is directed to Dr. Morton of Children’s Hospital of Pittsburgh, where transplant experts agree to list Mathew for a liver transplant. Jacob and Emma learn that children who receive a liver transplant have to take strong immunosuppressive drugs for the rest of their lives. It was also clear that there was a 40% possibility that Mathew could reject the liver and need a second transplant (which also might be rejected) or he could die from surgical complications.

Question 7: Assuming the liver transplant was successful and Mathew did not reject the new liver, what type of diet would Mathew be able to/need to eat?

A. He would still need to eat his special diet but he would be at less risk of a metabolic crisis

B. He could eat a normal diet

C. He would need to change to a high protein diet like Atkin’s

D. He would be on an all liquid diet

Question 8: Emma and Jacob decide they want to try to have another child. What would be the chance that this child would also have the disorder that Mathew and Samuel have/had?

A. 0 %

B. 25%

C. 50%

D. 75%

E. 100%

Question 9: If Mathew grew up, got married, and decided to have children, what would be the chance that his children would have the disorder? A. 0%, the liver transplant would have cured him

B. 25%

C. 50%

D. 100%

E. It would depend on his wife, if she was normal than there would be a 0% chance of his children having the disorder but 100% would be carriers, if she was a carrier than there would be a 50% chance of his children having the disorder and a 50% chance that they would be a carrier.

Question 10: The disorder is found in 1 in 200,000 infants throughout the US but 1 in 200 in the Amish and Mennonites of Lancaster County, PA. Why is there such a difference in the prevalence of the disease?

A. There are environmental factors associated with being Amish or Mennonites that increase the prevalence.

B. There is a large amount of genetic similarity within these populations because they tend to marry within the population so recessive disorders such as this are more likely.

C. The gene mutation is preferentially carried in Caucasians so when you average the prevalence across all races in the US the prevalence drops.

D. It is unknown why the prevalence is so much greater in Amish and Mennonites.

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7 Aug 2018

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Case Study 1: Case Presentation

John, a healthy twenty-eight year old electrical engineer, was driving home from work one evening when he experienced sudden stabbing pain in his right pectoral and right lateral axillary regions. He began to feel out of breath and both his respiratory rate and heart rate increased dramatically. As luck would have it, John passed a hospital each day on his way home and was able to get himself to the hospital’s emergency room. The emergency room physician listened to John’s breathing with a stethoscope and requested blood gas analysis and a chest x-ray. John answered a few of the doctor’s questions. The doctor noted that John had no history of respiratory problems but was a heavy smoker.

After viewing the chest radiograph, the doctor informed John that he had experienced a spontaneous pneumothorax, or what is commonly called a collapsed lung. The doctor explained that a hole had opened in John’s right lung and that this hole had allowed air to leak into the cavity surrounding the lung. Then, as a result of the lung’s own elastic nature, the lung had collapsed. The doctor said he could not be certain of the cause of the pneumothorax, but smoking cigarettes had certainly increased the likelihood of it happening. He told John he was fortunate the pneumothorax was small, which meant that relatively little air had escaped from the lung into the surrounding cavity, and it should heal on its own. He instructed John to quit smoking, avoid high altitudes, flying in nonpressurized aircraft, and scuba diving. He also had John make an appointment for a re-check and another chest x-ray.

Case Background

Spontaneous pneumothorax occurs when a blister on the surface of the lung opens, allowing air from the lung to move into the pleural cavity. This occurs because alveolar pressure is normally greater than the pressure in the pleural cavity. As air escapes from the lung, the lung tissues will recoil, and the lung will begin to collapse. The lung will continue to collapse until the difference between the alveolar pressure and pleural pressure disappears or until the collapsing of the lung causes the opening to seal.

The pneumothorax decreases the efficiency of the respiratory system, which in turn results in decreased blood oxygen concentration, increased respiratory rate, and increased heart rate. If the pneumothorax is small, the air that escapes into the pleural cavity can be reabsorbed into the lung once the opening has sealed shut. If the pneumothorax is large, a needle or chest tube may have to be inserted into the pleural cavity to draw the air out and allow for the reexpansion of the lung.

Questions

Define the following terms and explain how they may have been affected by John’s spontaneous pneumothorax.

Visceral pleura

Parietal pleura

Pleural cavity

As a result of a pneumothorax, the lung tissues recoil, and the lung collapses. Explain how recoil and collapse are prevented in a healthy lung?

How does elastic recoil function in breathing?

Why was John instructed to avoid high altitudes and flying in nonpressurized aircraft?

Case Study 2: The Case of the Coughing Housewife

Jessica, a fifty-nine year old mother of four, moved from a ranch in Colorado to Los Angeles, after the death of her husband, to be closer to her oldest son and his family. She has been in Los Angeles for 18 months and has noticed that she is experiencing shortness of breath which has worsened over the last six months. For the last week, she has been coughing and bringing up yellow mucus. She also noticed swelling in her ankles so she decided to visit a physician about her condition.

Jessica's family and medical history include a negative history of asthma or allergies, lack of occupational or home exposure to asbestos, a previous smoking history (one package of cigarettes per day between the ages of 16 and 52), episodes of bronchitis, treated with antibiotics on an outpatient basis, and a positive history of heart disease (father at 52 and brother at 56). Jessica has no history of serious illness, including heart disease, and her weight is within five pounds of her "desired" weight. She usually coughs in the morning to "clear her throat", but there is usually only a small amount of white mucus.

Her nurse practitioner conducts a general physical examination with the following results. Jessica's skin is normal (no rashes or cyanosis) and her nervous system is functioning normally. Her body temperature was 98.4oF while her pulse was regular at 95 beats per minute with an occasional premature beat. Jessica's blood pressure was within normal limits, however her jugular veins were slightly distended. Her respiratory rate was 28 breaths per minute; she breathed with pursed lips and used her accessory respiratory muscles more than would be expected. Jessica presented with a barrel chest and mild dyspnea when climbing onto the examination table. When listening to her breathing, the nurse practitioner noticed that Jessica had prolonged expiration accompanied by expiratory wheezes. Evaluation of her abdomen indicated no masses or tenderness, but she presented with both hepatomegaly and splenomegaly. All of her extremities were normal with the exception of bilaterally pedal edema.

Based on these results, the nurse practitioner suspected a pulmonary disorder and, after consultation with a physician, ordered laboratory tests (blood and sputum), spirometry and chest x-rays. The results of the laboratory tests were as follows: plasma bicarbonate = 38 mEq/L, hematocrit = 49%, white blood cell count = 9000, pH = 7.38; PaCO2 = 56, and PaO2 = 54. Analysis of the sputum sample indicated the presence of epithelial cells, polymorphonucleocytes and gram positive diplococci. Jessica's 1 second forced expiratory volume (FEV1) was 1.5 L/sec and her forced vital capacity (FVC) was 4 L. These values were 40% and 83% of normal, respectively. Results of the chest x-ray indicated scarring and hyperinflation of the lungs.

The results of these tests coupled with the physical examination and history lead to a diagnosis of emphysema. Jessica was prescribed antibiotics for the infection and oxygen by nose as well as a b2-agonist nebulizer as an acute treatment and requested to stay for observation and stabilization. After Jessica's condition was stabilized she was discharged and given a prescription for an inhaler containing a b2-agonist to be used as needed. She was also encouraged to exercise regularly and follow the nutritional guidelines she was given. Jessica was also informed that if the symptoms either worsened or did not lessen within the next week, to return and her treatment would be reevaluated and would possibly include nocturnal oxygen and an inhaler containing corticosteroids.

Answer the following questions about this case

Define the bold terms in the text. (8 points)

What risk factors and symptoms did Jessica present with prior to the physical examination that suggested a pulmonary disorder?

How did the physical examination, chest X-ray and spirometry confirm this hypothesis?

Identify muscles involved in respiration and how these muscles are responsible for the process of ventilation.

How will the b2-agonist in the inhaler help with the respiratory problems Jessica presents with?

Why is it important that a b2-agonist and not simply an b-agonist is used in the inhaler?

If her condition does not progress, why would corticosteroids be used in the inhaler?

Investigation of Possible Bioterrorism-Related Activity


Patient History:

A 38-year-old woman who resided in the Northeast was admitted to the hospital with fever, myalgia, and weakness, which progressed over 3 days to respiratory failure requiring mechanical ventilation. On day 22, after 3 weeks of intensive care, the patient was still febrile. Cultures of blood were negative.

Hospital personnel interviewed family members who reported no history of traditional risk factors for fever of unknown origin (e.g., relevant food, infected animal contact, or travel history). On day 24, the patient's family reported to hospital personnel that the patient's illness might have been caused by exposure to laboratory flasks and cultures kept in her apartment by her boyfriend. He was described as a foreign national studying biology, but recently he had returned to his country of citizenship. On day 25, the patient's family brought laboratory flasks, Petri dishes, and culture media to the hospital from the patient's apartment. Several contained an unidentified clear liquid. The patient’s unresponsiveness and the acknowledged potential for some bacterial species to be used as bioterrorist agents raised concerns among the infection control staff that this case might be associated with a bioterrorist event or unintentional exposure to contaminated materials in the patient's home. The hospital contacted local law enforcement, the Department of Public Health, and the Federal Bureau of Investigation about the unusual circumstances surrounding the case.

On day 30, under the authority of state communicable disease statutes and in cooperation with the local police department, fire department, and hazardous materials unit, NHDHHS personnel entered the patient's apartment to assess any possibility of an ongoing public health hazard. Remaining flasks were removed and cultured. After 48 hours, growth of a translucent, pinpoint, and smooth colony appeared on blood agar and chocolate agar.

Gram stain of the colonies revealed faintly staining Gram-negative rods that were catalase positive, oxidase positive, and rapidly urea positive. On day 33, the patient began to get better after extensive antibiotic therapy.

Early detection is essential to ensure a prompt response to a biological terrorist event. Local public health authorities must rely on clinicians to recognize and report suspicious or unusual presentations of disease. However, correlating suspicious cases originating from diverse locations or discerning an increase in common presentations above the normal baseline is difficult. As in this case, public health practitioners coordinating disease surveillance may be able to receive reports of rare diseases and to determine whether they are occurring at a higher than normal rate in a large surveillance area.

The CDC, in collaboration with local, state, and territorial health departments, is enhancing existing disease surveillance systems for specific diseases that are normally rare in the United States but thought to have a high potential for public health impact if used as biological terrorism agents. This is being accomplished by improving training of clinical, laboratory, and public health personnel in recognizing suspicious disease presentations and by expanding of existing, disease-specific surveillance infrastructure. In addition, surveillance is being improved for disease presentations, such as acute respiratory distress, hemorrhagic, or meningeal symptoms normally caused by common infectious agents, but that could indicate an increase in illnesses caused by a biological agent used in terrorism. Surveillance mechanisms to rapidly assess changes in rates of disease include monitoring of calls to local emergency medical systems, regularly reviewing emergency department discharge diagnoses, and linking infection control practitioner networks.

Assignment:

For this case study, write a 1-page report that describes the possible agent of bioterrorism along with pathogenesis, treatment, and prevention. Include a brief discussion of sentinel labs and their role in recognizing potential episodes of bioterrorism.

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