Biochemistry spotters

Biochemistry For Medics 1

Biochemistry Spotters

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10/28/2012

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Make a Diagnosis A 29 year- old officer presented to emergency department complaining of chills and breathing difficulty. He was a heroin abuser who was admitted in the same hospital 7 years ago because of drug over dosage. He had lost 10 kg of body weight since his last clinical visit. On examination, he had multiple enlarged lymph nodes. Several red nodules were present on the skin of chest and arms. The chest radiograph showed diffuse pneumonia. Sputum smear revealed numerous Pneumocystis organisms. Skin biopsy revealed Kaposi’s sarcoma as shown in the picture

10/28/2012


Diagnosis

10/28/2012

This is a case of HIV infection. History of drug abuse, weight loss, typical presence of lymphadenopathy and AIDS markers- Kaposi sarcoma and Pneumocystis pneumonia signify HIV infection.


Identify the structure and mention any two of its important uses

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Answer

It is Liposome, used for-1) Drug delivery and 2) Gene therapy

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Identify the Protein and mention any two of its important functions

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Answer It is a structure of collagen. Collagen is rich in glycine, proline and hydroxy proline amino acids as shown in the figure. It is mostly found in tendons, ligaments and skin, and is also abundant in cornea, cartilage, bone, blood vessels, the gut, and intervertebral disc. The fibroblast is the most common cell which creates collagen.

10/28/2012


Make a Diagnosis

A 16-year-old African American girl was admitted to the emergency room with complaints of fever and recurrent pain in her arms and legsHer laboratory tests revealed the following: Hemoglobin 8.0 g/dlHaemtocrit 9.1%Serum Iron- 11μg/dlSerum Albumin 4.4g/dl

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Make a Diagnosis

Blood Smear showed target cells, poikilocytes, hypochromasia, sickle red cells, nucleated RBCs, and Howell-Jolly bodiesHb Electrophoresis -showed a slow moving band. What is the most probable diagnosis?

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AnswerThe patient is suffering from sickle cell anemia The Sickle cell disease, also called as sickle cell anemia is due to a single nucleotide alteration (point mutation) in the β globin gene of hemoglobin resulting in rigid misshapen erythrocytes- sickle shaped erythrocytes.Such sickled cells frequently block the flow of blood in the narrow capillaries. The interruption in the supply of oxygen leads to tissue anoxia, causing pain and eventually death of cells (infarction) in the vicinity of blockage.

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Make a Diagnosis

A 12 –year-old girl has been brought by her parents for consultation. She has pale skin, blonde hair and pink iris. She is otherwise healthy, but is unable to fix the gaze. Parents reveal that their first two children, a boy and a girl, had similar symptoms, but the parents themselves are normal.What is the most probable diagnosis?

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Make a Diagnosis

Normal parents having two affected children, male and female, is suggestive of Autosomal recessive inheritance of oculo-cutaneous albinism. The baby has defect in the synthesis of melanin . Pale skin, blonde hair and pink color of iris, are all due to the absence of melanin. The visual impairment is also typical of albinism.

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Make a Diagnosis

A 3-year-old child has been brought to the clinic because of excessive exhaustion and fatigue. On further questioning of the mother, she reports that she was previously breastfeeding but had to stop to return to work. To feed all of her other children, she had to dilute her formula with water to make the formula last longer for the entire family.

10/28/2012


Make a Diagnosis

The child is irritable, has starved appearance, weight is much below for height, mid-arm muscle circumference is 12 cm and triceps thickness is 2mm. The creatinine-height index (the 24-h urinary creatinine excretion compared with normal values based on height) is low but serum Albumin is normal.

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Answer

The child is suffering from Nutritional Marasmus. Marasmus is a state in which virtually all available body fat stores are exhausted due to starvation. The given patient has starved appearance diagnostic of Marasmus. The low body weight, diminished skin-fold thickness and reduced arm muscle circumference reflect the loss of fat reserves and the catabolism of proteins throughout the body. The low creatinine-height index also reflects the loss of muscle mass while the normal serum albumin differentiates it from Kwashiorkor which is primarily due to protein deficiency.

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Spot Question

A 60- year- old woman presents with chest pain radiating to her left arm. She is diagnosed with having had a myocardial infarct and is prescribed a statin medication. Statin is known as a Hypolipidemic drug. What is the mechanism of action of this drug ?

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Answer

The Statins act as competitive inhibitors of the enzyme HMG-CoA reductase, the rate limiting enzyme of the pathway of cholesterol biosynthesis.

Lovastatin is a member of a class of drugs (Atorvastatin, fluvastatin, pravastatin and Simvastatin are others in this class) called statins that are used to treat hypercholesterolemia.

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Make a diagnosis

An 11-year-old girl has been brought by her parents to the accident & emergency department in a confused state with symptoms of acute abdomen, respiratory difficulty & acetone-like smell of breath. She is a known case of Type 1 Diabetes Mellitus but is non compliant to insulin therapy.What is the likely diagnosis? What is the expected outcome of urine analysis ?

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Answer

The girl is suffering from Diabetic ketoacidosis, the most frequent complication of Type 1 DM.Urine analysis is expected to reveal the presence of glucose and ketone bodies while blood biochemistry would reveal, hyperglycemia, metabolic acidosis, and volume depletion due to osmotic diuresis.

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20

Spot Question

The above Line weaver-Burk plot shows the mechanism of action of a drug used for the treatment of gout. The said drug acts by inhibiting xanthine oxidase enzyme.Which type of inhibition is shown in the graph?Name a similarly acting drug used for the treatment of hypertension.

10/28/2012 Biochemistry For Medics


Answer

Since the Km has increased and Vmax is constant , it is competitive inhibition. Allopurinol acts by inhibiting Xanthine oxidase enzyme. Captopril, an antihypertensive drug acts similarly to competitively inhibit, Angiotensin Converting Enzyme (ACE).

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Make a diagnosis

A 24- year- old patient was brought to medical OPD with acute abdominal pain, depression and extreme weakness. Urine analysis revealed purple color and the presence of ALA and PBG (Delta amino Levulinic acid and Porphobilinogen). What is the probable diagnosis and defect in this disease ?

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AnswerIt is a case of Acute intermittent Porphyria. Purple colored urine, presence of ALA (Delta amino levuliinic acid) and PBG (Porphobilinogen) and Psychiatric symptoms are diagnostic of Acute intermittent Porphyria.There is deficiency of PBG deaminase enzyme (Porphobilinogen deaminase)

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Spot Question

State at least 2 metabolic complications of obesity and give the reason for obesity upon excessive carbohydrate consumption. 10/28/2012


Obesity Obesity is associated with hypertension, dyslipidemia, insulin resistance, diabetes mellitus, IHD and gall bladder disease.Excessive carbohydrate consumption provides glycerol and Acetyl co A through formation of Pyruvate from Glucose and NADPH through HMP pathway. This helps in fatty acid biosynthesis and more formation of triglycerides.10/28/2012


Spot Question

Name two chief nutrients of milk and state the reason for milk intolerance in certain individuals.

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Answer

The important components of milk are lactose as milk sugar, casein, lactalbumin and lactglobulins as milk proteins. The average distribution of nutrients is- 87.7% water, 4.9% lactose (carbohydrate), 3.4% fat, 3.3% protein, and 0.7% minerals.

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Milk intolerance (Lactose intolerance) occurs due to deficiency of lactase enzyme, there is inability to digest lactose and the associated symptoms are due to accumulated lactose .


Spot Question

Based on the findings in the peripheral blood film, the patient has been diagnosed with megaloblastic anemia. Name at least two vitamins known to cause megaloblastic anemia

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Answer

Megaloblastic anemia is observed in vitamin B12 and folic acid deficiencies.Macrocytes are observed and some of the red blood cells show ovalocytosis. A 6-lobed polymorph nuclear leucocyte is present. Oval macrocytes, usually with considerable anisocytosis and poikilocytosis, are the main feature. The MCV is usually >100 fL unless a cause of microcytosis (e.g., iron deficiency or thalassemia trait) is present.

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Make a diagnosis

A 1-year-old girl is brought to her pediatrician’s office with concerns about her development. She had an uncomplicated birth. The mother reports that the baby is not achieving the normal milestones for a baby of her age. She also reports an unusual odor to her urine and some areas of hypo pigmentation on her skin and hair.

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Make a diagnosis

On exam, the girl is noted to have some muscle hypotonia and microcephaly. The urine collected is found to have a “mousy” odor.What is the most likely diagnosis?What is the biochemical basis of the hypo pigmented skin and hair?10/28/2012


Answer

Likely diagnosis- Phenyl ketonuriaBiochemical defect- Deficiency of phenyl alanine hydroxylaseBiochemical basis of hypopigmentation: Phenylalanine is competitive inhibitor of tyrosinase (key enzyme in melanin synthesis)

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Spot Question

A 37-year-old female presents to your clinic to discuss her plans for a new vegetarian diet. The patient heard from a friend about a new vegetarian diet that promised rapid weight loss. The diet consists of many leafy vegetables with no pork, chicken, beef, eggs, or milk. She is also planning on working out regularly with the goal of running a marathon within the year. After listening to the patient, you refer her to a nutritionist for further assistance and guidance

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34

Spot Question

What is an essential amino acid, and how many are there? List the essential amino acids.

10/28/2012 Biochemistry For Medics


Answer

Essential amino acids: The amino acids that cannot be synthesized by the body. There are a total of ten essential amino acids.List of essential amino acids: Isoleucine, leucine, lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and ValineHistidine and Arginine are semi essential amino acids, that can be synthesized but their demand increases during growth, repair and reproduction.

10/28/2012

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