MDS PREP
What is the mechanism of action of Clostridium difficile toxins in pseudomembranous colitis?
1) Direct damage to the intestinal mucosal cells
2) Formation of pseudomembranes
3) Inhibition of intestinal peristalsis
4) Alteration of intestinal microbiota composition
The toxins produced by Clostridium difficile cause ribosylation of small GTPases like Rho, leading to disruption of the actin cytoskeleton, increased cytokine release, and epithelial cell apoptosis, which in turn results in the formation of pseudomembranes and the symptoms of pseudomembranous colitis.
Which of the following is NOT a common cause of pseudomembranous colitis?
1) Clostridium difficile
2) Salmonella enterotoxin
3) Staphylococcus aureus toxin
4) Escherichia coli toxins
Pseudomembranous colitis is generally caused by Clostridium difficile toxins, which are not produced by Salmonella or E. coli. These latter organisms are associated with food poisoning due to different types of enterotoxins.
Pulsus paradoxus is seen in
1) Mitral stenosis
2) Atrial fibrillation
3) Aortic stenosis
4) Asthma
General Medicine
Answer: 4
Pulsus paradoxus is a clinical sign characterized by a drop in blood pressure during inspiration. It is commonly seen in conditions like asthma, where airway obstruction leads to significant changes in intrathoracic pressure.
Which of the following is a hallmark of alcoholic cirrhosis?
1) Massive hepatic necrosis
2) Fatty infiltration of hepatocytes
3) Extensive scar tissue and regenerative nodules
4) Inflammatory cell infiltration
Alcoholic cirrhosis is characterized by the presence of extensive scar tissue (fibrosis) and regenerative nodules within the liver. This results from chronic alcohol-induced damage to hepatocytes and the subsequent wound healing response.
What is the typical frequency of phlebotomy in the initial phase of treatment for hemochromatosis?
1) Once a week
2) Once every two weeks
3) Once a month
4) Once every three months
In the initial phase of treatment for hemochromatosis, phlebotomy is usually performed once a week to rapidly reduce iron stores. Once transferrin saturation and serum ferritin levels become normal, the frequency is typically reduced to every three months for maintenance.
Most likely precursor to bronchiectasis is
1) TB
2) Carcinoma
3) Bronchial adenoma
4) Bronchopneumonia
General Medicine
Answer: 4
The most likely precursor to bronchiectasis is bronchopneumonia
What is the target organ for ACTH in the regulation of cortisol secretion?
1) Thyroid gland
2) Adrenal cortex
3) Ovary
4) Testis
Adrenocorticotropic hormone (ACTH) is produced by the pituitary gland and acts on the adrenal cortex to stimulate the secretion of cortisol, an essential glucocorticoid hormone. The adrenal cortex is the target organ for ACTH in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis.
What is the primary function of the ATP7B protein in the context of Wilson's disease?
1) Copper uptake in the gut
2) Copper incorporation into ceruloplasmin
3) Copper excretion from hepatocytes
4) Copper metabolism in erythrocytes
The ATP7B protein is essential for copper excretion from hepatocytes into bile, and its deficiency leads to copper accumulation in the liver and other tissues in Wilson's disease.