Thumb and Finger movements

EDD

Calculation of Estimated Delivery Date

Question N0-05

Bilirubin is secreted by:?

A. Bile salts
B. Bile pigment
C. Secretin
D. CCK 




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Answer - Bile Salts

Choleretics are substances that increase the volume of secretion of bile from the liver as well as the amount of solids secreted.

Bile salts are amongst the most important physiological choleretics.Investigators have recognized the importance of bile salts in stimulating biliary secretion by the liver.

Question N0-04

Do identical twins have identical DNA?


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It is a basic tenet of human biology, taught in grade schools everywhere: Identical twins come from the same fertilized egg and, thus, share identical genetic profiles.

But according to new research, though identical twins share very similar genes, identical they are not. The discovery opens a new understanding of why two people who hail from the same embryo can differ in phenotype, as biologists refer to a person’s physical manifestation.

The new findings appear in the March issue of The American Journal of Human Genetics, in a study conducted by scientists at the University of Alabama at Birmingham and universities in Sweden and the Netherlands. The scientists examined the genes of 10 pairs of monozygotic, or identical, twins, including 9 pairs in which one twin showed signs of dementia or Parkinson’s disease and the other did not.

It has long been known that identical twins develop differences that result from environment. And in recent years, it has also been shown that some of their differences can spring from unique changes in what are known as epigenetic factors, the chemical markers that attach to genes and affect how they are expressed — in some cases by slowing or shutting the genes off, and in others by increasing their output.

These epigenetic changes — which accumulate over a lifetime and can arise from things like diet and tobacco smoke — have been implicated in the development of cancer and behavioral traits like fearfulness and confidence, among other things. Epigenetic markers vary widely from one person to another, but identical twins were still considered genetically identical because epigenetics influence only the expression of a gene and not the underlying sequence of the gene itself.

“When we started this study, people were expecting that only epigenetics would differ greatly between twins,” said Jan Dumanski, a professor of genetics at the University of Alabama at Birmingham and an author of the study. “But what we found are changes on the genetic level, the DNA sequence itself.”

The specific changes that Dr. Dumanski and his colleagues identified are known as copy number variations, in which a gene exists in multiple copies, or a set of coding letters in DNA is missing. Not known, however, is whether these changes in identical twins occur at the embryonic level, as the twins age or both.

“Copy number variations were discovered only a few years ago, but they are immensely important,” said Dr. Carl Bruder, another author of the study at the university. Certain copy variations have been shown in humans to confer protection against diseases likeAIDS, while others are believed to contribute to autism, lupus and other conditions. By studying pairs of identical twins in which one sibling has a disease and the other does not, scientists should be able to identify more easily the genes involved in disease.

John Witte, a professor of genetic epidemiology at the University of California, San Francisco, said the findings were part of a growing focus on genetic changes after the parents’ template had been laid. This and other research, Dr. Witte said, shows “you’ve got a little bit more genetic variation than previously thought.”

In the meantime, a lot of biology textbooks may need updating.

Dr. Dumanski pointed out, for example, that as his study was going to press, the following statement could be found on the Web site of the National Human Genome Research Institute, the group that financed the government project to decode the human genome: “Most of any one person’s DNA, some 99.9 percent, is exactly the same as any other person’s DNA. (Identical twins are the exception, with 100 percent similarity).”

That, we now know, no longer appears to be the case.

THE BOTTOM LINE

Identical twins apparently do not have identical DNA.

Question No - 03

A 55 year old diabetic woman with recurrent foot ulcers presents with pain and swelling of her foot centered around her ulcer. Cellulitis is suspected, a swab of pus from her ulcer reveals Group A streptococci. She has a history of severe allergy to penicillin.
Treatment should ideally include


a) Course of vancomycin
b) stripping of varicose veins
c) Percutaneous thrombolysis
d) Pulmonary Ventilation/Perfusion scintigraphy
e) Administer low-molecular-weight-heparin


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 Answer: Course of vancomycin


Explanation:
Depending on culture sensitivities, the therapy directed against Group A streptococci usually is penicillin G, 1 to 2 million units intravenously every 2 to 3 hours. Penicillin-allergic patients may be treated with a cephalosporin such as cefazolin. Vancomycin may be used in cases in which cross-reactivity between penicillin and cephalosporin is of concern, If Haemophilus infiuenzae infection is suspected, then ampicillin is administered in six divided dosages. Alternatively, because of recent emergence of beta-lactamase-producing ampicillin strains, a cephalosporin (cefuroxime or cefotaxime) may be chosen. In the course

Question N0-02

The Cell Junctions allowing exchange of cytoplasmic molecules between two cells are called:

A. Gap Junctions
B. Tight Junctions
C. Anchoring Junctions
D. Focal Junctions


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Answer is A. Gap Junctions.

Gap Junctions are a type of intercellular junction comprising a narrowed portion (about 3 nm) of the intercellular space, that contains channels or pores (2 nm) composed of hexagonal arrays of membrane spanning proteins around a central lumen (connexon) through which pass ions and small molecules such as most sugars, amino acids, nucleotides, vitamins, hormones and cyclic AMP.

Gap junctions were so named because of the "gap" shown to be present at these special junctions between two cells. One gap junction is composed of two connexons (or hemichannels) which connect across the intercellular space. It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells.

To come to a definite conclusion about this answer, let us review the different types of cell connections. There are 3 major  forms of direct cell connections. 

1. Desmosomes: Small 'spot-welds' that hold adjacent cells together. Fibres on the outer surface of each desmosome interlock with each other. Internally, they are anchored by fibres of the cytoskeleton.   
• Adjacent Skin Cells are typical examples of desmosome.
2. Gap Junctions: Formed when membrane channels of adjacent plasma membranes adhere to each other. These serve two effects:
   
   • Form gaps or tunnels that join cytoplasm of two cells.
   • Fuse the two plasma membranes into a single structure
   • Examples include Myocardial Fibres, Central Nervous System
3. Tight Junctions: Occur in cells that are joined by collars of tightly fused membranes. Molecules cannot penetrate or spread through cracks in between cells.
• Example includes Lining of the intestine (the only way molecules can get past is through controlled channels or carrier molecules in plasma membrane).

Question N0-01

A pleural aspiration on the 50 year-old women whose chest x-ray is shown below.

PLEURAL ASPIRATION ANALYSIS

*Total Protein = 2.35 G/L
*Lactic Dehydrogenase (LDH) = 156 IU/L
*pH = 7.36
*Microbiology (Gram stain and culture) = Nil Growth

#Question
What is the most likely cause of the effusion from your interpretation?

(a) Bronchial carcinoma
(b) Hypothyroidism
(c) Pneumonia
(d) Rheumatoid disease
(e) Pulmonary embolus


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Answer - Hypothyroidism

Pleural effusions are divided into exudates and transudates. This is based on the total protein content of pleural fluid.

Exudate = greater than 30 g/l of protein

Transudate = less than 30 g/l of protein

Exudates tend to be unilateral and trasudates bilateral due to the nature of the causative factors.

The X-Ray shows bilateral pleural effusions – albeit larger on the left. The aspirate analysis also shows a transudate. The only option within the list which causes a transudate is hypothyroidism.