Biochemistry
2 questionsIn Zellweger syndrome, which of the following is absent?
Glutamine is increased in CSF, blood & urine WITHOUT elevated orotic acid in which defect:
NEET-PG 2019 - Biochemistry NEET-PG Practice Questions and MCQs
Question 231: In Zellweger syndrome, which of the following is absent?
- A. Golgi apparatus
- B. Peroxisomes (Correct Answer)
- C. Mitochondria
- D. ER
Explanation: ***Peroxisomes*** - **Zellweger syndrome** is an **autosomal recessive disorder** characterized by a severe reduction or absence of functional peroxisomes. - Peroxisomes are essential organelles involved in **lipid metabolism**, particularly the breakdown of very long-chain fatty acids (VLCFAs) and branched-chain fatty acids, leading to their accumulation in the blood and tissues. *Golgi apparatus* - The **Golgi apparatus** is an intact and functional organelle in Zellweger syndrome. - It plays a crucial role in modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles, functions that remain unaffected in this condition. *Mitochondria* - **Mitochondria**, responsible for cellular respiration and ATP production, are present and functional in Zellweger syndrome. - While metabolic disturbances occur, they are not due to primary mitochondrial dysfunction. *ER* - The **endoplasmic reticulum (ER)**, a network of membranes involved in protein and lipid synthesis, is also intact and functional. - It is not directly implicated in the pathogenesis of Zellweger syndrome.
Question 232: Glutamine is increased in CSF, blood & urine WITHOUT elevated orotic acid in which defect:
- A. Arginase
- B. Argininosuccinate lyase deficiency
- C. CPS-I (Correct Answer)
- D. Arginosuccinate synthetase
- E. OTC
Explanation: ***CPS-I*** - A deficiency in **Carbamoyl Phosphate Synthetase I (CPS-I)** leads to a severe block in the **urea cycle**, resulting in profound hyperammonemia. - The elevated ammonia is then shunted to produce more **glutamine** (via glutamine synthetase), which serves as a detoxification mechanism but also causes high levels of glutamine in CSF, blood, and urine. *Arginase* - **Arginase deficiency** primarily leads to elevated **arginine** levels and mild to moderate hyperammonemia, but not typically a dramatic increase in glutamine due to the block occurring later in the cycle. - Clinical features include progressive spasticity, growth retardation, and intellectual disability. *Argininosuccinate lyase deficiency* - This deficiency causes accumulation of **argininosuccinate** in body fluids, which is a diagnostic marker, rather than primarily increased glutamine. - It presents with severe hyperammonemia, neurological symptoms, and often hepatomegaly. *Arginosuccinate synthetase* - A deficiency in **argininosuccinate synthetase** (also known as citrullinemia type I) leads to a buildup of **citrulline** and severe hyperammonemia. - While hyperammonemia can indirectly increase glutamine, the primary diagnostic marker is elevated citrulline, and the glutamine increase is not as pronounced or directly symptomatic as in CPS-I deficiency. *OTC* - **Ornithine Transcarbamylase (OTC) deficiency** is the most common urea cycle disorder and leads to severe hyperammonemia, accompanied by elevated **orotic acid** due to carbamoyl phosphate shunting to pyrimidine synthesis. - While hyperammonemia drives glutamine synthesis, the presence of elevated orotic acid is a key differentiator from CPS-I deficiency, which does not have increased orotic acid.
Internal Medicine
2 questionsHIV patient presented with diarrhea. On stool examination, acid-fast organisms (Isospora belli) were seen. What is the drug of choice in this patient?
Which apolipoprotein is most strongly associated with increased risk of Alzheimer's disease?
NEET-PG 2019 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 231: HIV patient presented with diarrhea. On stool examination, acid-fast organisms (Isospora belli) were seen. What is the drug of choice in this patient?
- A. Niclosamide
- B. Nitazoxanide
- C. Primaquine
- D. TMP-SMX (Correct Answer)
Explanation: ***TMP-SMX*** - **Trimethoprim-sulfamethoxazole (TMP-SMX)** is the primary treatment for **Isospora belli** infections, especially in HIV-positive patients [1]. - It is highly effective in eradicating the parasite and preventing relapses in immunocompromised individuals [1]. *Niclosamide* - **Niclosamide** is an antihelminthic drug primarily used for treating **tapeworm infections** [2]. - It is not effective against protozoal parasites like *Isospora belli*. *Nitazoxanide* - **Nitazoxanide** is an antiparasitic drug that can be used for various protozoal and helminthic infections, including *Cryptosporidium* and *Giardia*. - While it has some efficacy against *Isospora belli*, it is generally considered a second-line agent, with **TMP-SMX** being the drug of choice [1]. *Primaquine* - **Primaquine** is an antimalarial drug specifically used to prevent relapse of **Plasmodium vivax** and **Plasmodium ovale** malaria by targeting hypnozoites. - It has no role in the treatment of **Isospora belli** infection.
Question 232: Which apolipoprotein is most strongly associated with increased risk of Alzheimer's disease?
- A. APOE3
- B. APOE4 (Correct Answer)
- C. APOC3
- D. APOE2
Explanation: APOE4 - The APOE4 allele is the strongest genetic risk factor for late-onset Alzheimer's disease, increasing risk and lowering the age of onset in a gene-dose dependent manner. - Individuals with one copy of APOE4 have a 2-3 times increased risk, and those with two copies have an 8-12 times increased risk compared to those with APOE3. APOE3 - APOE3 is the most common allele and is considered a neutral risk factor for Alzheimer's disease. - It plays a normal role in lipid metabolism and brain function without significantly increasing or decreasing AD risk. APOC3 - APOC3 is involved in triglyceride metabolism and is primarily linked to cardiovascular disease risk, not Alzheimer's disease. - While it modulates lipid levels, it does not have a direct, strong genetic association with AD pathogenesis. APOE2 - APOE2 is associated with a reduced risk of Alzheimer's disease, offering a protective effect against its development. - It is thought to improve the clearance of amyloid-beta (A̠) plaques, a hallmark of AD pathology.
Microbiology
3 questionsA neonate was found to have cataract, deafness and cardiac defects. Which group of viruses was the mother infected with?
Flask-shaped ulcers in the intestine are caused by which of the following?
A person working in an abattoir presented with malignant pustule on hand. What is the causative agent?
NEET-PG 2019 - Microbiology NEET-PG Practice Questions and MCQs
Question 231: A neonate was found to have cataract, deafness and cardiac defects. Which group of viruses was the mother infected with?
- A. Togaviridae family (includes Rubella virus) (Correct Answer)
- B. Flaviviridae family (includes Zika virus)
- C. Bunyaviridae family (includes Rift Valley fever virus)
- D. Arenaviridae family (includes Lassa fever virus)
Explanation: ***Togaviridae family (includes Rubella virus)*** - The classic triad of **congenital rubella syndrome (CRS)** includes **cataracts**, **deafness**, and **cardiac defects** (e.g., patent ductus arteriosus, pulmonary artery stenosis). - Rubella virus is a member of the **Togaviridae family** and causes significant fetal damage if the mother is infected during the first trimester. *Flaviviridae family (includes Zika virus)* - While congenital Zika syndrome can cause severe birth defects, it is primarily associated with **microcephaly**, intracranial calcifications, and ocular abnormalities, not typically the classic rubella triad. - **Deafness** and **linear cataracts** are not characteristic features of congenital Zika infection. *Bunyaviridae family (includes Rift Valley fever virus)* - Rift Valley fever virus is primarily transmitted by mosquitoes and causes **febrile illness** in humans and livestock, with potential for **hemorrhagic fever** or **encephalitis**. - It is not known to cause congenital abnormalities resembling cataracts, deafness, and cardiac defects in neonates. *Arenaviridae family (includes Lassa fever virus)* - Lassa fever virus causes a severe **hemorrhagic fever** in humans, primarily through contact with infected rodents or person-to-person transmission. - It is not associated with congenital malformations such as cataracts, deafness, and cardiac defects.
Question 232: Flask-shaped ulcers in the intestine are caused by which of the following?
- A. TB
- B. Giardia
- C. Entamoeba histolytica (Correct Answer)
- D. Typhoid
Explanation: ***Entamoeba histolytica*** - *Entamoeba histolytica* is a protozoan that causes **amoebiasis**, which is characterized by **flask-shaped (bottle-shaped) ulcers** in the colon - this is the **pathognomonic feature** of intestinal amoebiasis. - The trophozoites invade the intestinal mucosa and submucosa, creating a **narrow neck at the mucosal surface** and a **wider base in the submucosa**, giving them their unique flask-like appearance. - These ulcers are most commonly found in the **cecum and ascending colon**. *TB* - Intestinal tuberculosis typically causes **transverse ulcers** (perpendicular to the bowel axis) due to lymphatic spread and caseous necrosis, often in the ileocecal region. - These ulcers are usually associated with **granulomas** and acid-fast bacilli, which are histologically distinct from flask-shaped ulcers. *Giardia* - *Giardia lamblia* (or *intestinalis*) is a flagellate that causes **giardiasis**, primarily adhering to the small intestinal villi and causing malabsorption and diarrhea. - It is **non-invasive** and does not penetrate the intestinal wall or cause ulcer formation; its pathology is mainly due to **mucosal inflammation** and villous blunting. *Typhoid* - Typhoid fever, caused by *Salmonella Typhi*, commonly leads to **longitudinal ulcers** (parallel to the bowel axis) in the **Peyer's patches** of the ileum due to bacterial invasion and necrosis of lymphoid tissue. - These ulcers may perforate but do not present with the flask-shaped morphology characteristic of amoebiasis.
Question 233: A person working in an abattoir presented with malignant pustule on hand. What is the causative agent?
- A. Clostridium botulinum
- B. Bacillus anthracis (Correct Answer)
- C. Streptococcus pyogenes
- D. Clostridium perfringens
Explanation: **Bacillus anthracis** - The presence of a **malignant pustule** on the hand, especially in an individual working in an **abattoir** (exposure to animals/animal products), is highly characteristic of **cutaneous anthrax**. - **Bacillus anthracis** is a **spore-forming bacterium** that causes anthrax, and the cutaneous form typically presents as a painless ulcer that develops into a black eschar. *Clostridium botulinum* - This bacterium causes **botulism**, a severe **neuroparalytic disease** characterized by flaccid paralysis. - It does not cause cutaneous lesions like a malignant pustule and is typically associated with **food poisoning** or wound infections leading to toxin production. *Streptococcus pyogenes* - This bacterium is a common cause of various infections, including **strep throat**, **impetigo**, **erysipelas**, and **necrotizing fasciitis**. - While it can cause skin infections, it does not typically present as a "malignant pustule" with the characteristic eschar seen in anthrax. *Clostridium perfringens* - This bacterium is a common cause of **gas gangrene** (myonecrosis) and **food poisoning**. - While it can cause severe tissue infections, it does not present as a malignant pustule.
Pathology
1 questionsWhich of the following is positive in Follicular lymphoma?
NEET-PG 2019 - Pathology NEET-PG Practice Questions and MCQs
Question 231: Which of the following is positive in Follicular lymphoma?
- A. Cyclin D1 (Bcl-1)
- B. Bcl-2 protein (Correct Answer)
- C. Bcl-10 signaling protein
- D. Bcl-6 transcription factor
Explanation: ***Bcl-2 protein*** - The characteristic **t(14;18) chromosomal translocation** in follicular lymphoma leads to the **overexpression of the Bcl-2 protein**, which promotes cell survival by inhibiting apoptosis [1], [4]. - This constitutive activation makes the tumor cells resistant to programmed cell death, contributing to their accumulation [2]. - **Bcl-2 positivity is highly specific for follicular lymphoma** among lymphomas, making it the most diagnostically useful marker [3]. *Cyclin D1 (Bcl-1)* - **Cyclin D1** overexpression is characteristic of **Mantle Cell Lymphoma**, typically due to a **t(11;14) translocation**. - It plays a role in cell cycle progression rather than directly inhibiting apoptosis in the same manner as Bcl-2. *Bcl-10 signaling protein* - **Bcl-10** is involved in **NF-ΙB activation**, particularly in certain types of **MALT lymphoma** and other lymphoid neoplasms. - It is not a primary diagnostic marker for follicular lymphoma. *Bcl-6 transcription factor* - **Bcl-6** is a germinal center marker and is **positive in most follicular lymphomas** since they are germinal center-derived B-cell neoplasms. - However, Bcl-6 is also expressed in other germinal center-derived lymphomas like **DLBCL of germinal center subtype**, making it **less specific** than Bcl-2 [3], [5]. - While both Bcl-2 and Bcl-6 can be positive in follicular lymphoma, **Bcl-2 overexpression due to t(14;18) is the defining molecular hallmark** and most diagnostically specific feature [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 602-604. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 310-311. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 604. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 561-562. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 563-564.
Pharmacology
1 questionsTolvaptan is used for:-
NEET-PG 2019 - Pharmacology NEET-PG Practice Questions and MCQs
Question 231: Tolvaptan is used for:-
- A. SIADH (Correct Answer)
- B. Von Willebrand disease
- C. Central DI
- D. Catecholamine resistant Shock
Explanation: ***SIADH*** - **Tolvaptan** is a **vasopressin V2 receptor antagonist** that promotes water excretion without affecting sodium, making it ideal for treating **euvolemic and hypervolemic hyponatremia** associated with SIADH. - In **syndrome of inappropriate antidiuretic hormone secretion (SIADH)**, there is excessive **ADH** leading to water retention and dilutional hyponatremia; tolvaptan effectively counters this by blocking vasopressin's action. *Von Willebrand disease* - This is a **bleeding disorder** caused by a deficiency or dysfunction of **von Willebrand factor**, treated with **desmopressin** or factor replacement, not tolvaptan. - Tolvaptan has no role in coagulation pathways or the management of bleeding disorders. *Central DI* - **Central diabetes insipidus (DI)** results from reduced **ADH production** by the hypothalamus or posterior pituitary, leading to excessive water loss. - It is treated with **desmopressin** (synthetic ADH) to replace the deficient hormone, which is the opposite effect of tolvaptan. *Catecholamine resistant Shock* - **Catecholamine-resistant shock** is characterized by persistent hypotension despite high doses of **vasopressors**. - Treatment often involves agents like **vasopressin** (not tolvaptan) or corticosteroids to improve vascular tone, as tolvaptan would worsen the hypotension by promoting diuresis.
Surgery
1 questionsDohlman surgery in Zenker's diverticulum is:-
NEET-PG 2019 - Surgery NEET-PG Practice Questions and MCQs
Question 231: Dohlman surgery in Zenker's diverticulum is:-
- A. Endoscopic electrocautery technique (Correct Answer)
- B. Endoscopic suturing of pouch
- C. Laser division of pouch
- D. Endoscopic stapling of septum
Explanation: ***Endoscopic electrocautery technique*** - The **Dohlman procedure** (Dohlman-Mattsson procedure, 1960) is an **endoscopic electrosurgical technique** that uses **diathermy/electrocautery** to divide the cricopharyngeal muscle (the septum between the esophagus and the diverticulum). - This method creates a common cavity between the esophagus and the diverticulum, allowing food to pass freely and preventing pooling. - It is one of the **classic endoscopic approaches** for treating Zenker's diverticulum and remains widely used. *Endoscopic suturing of pouch* - Endoscopic suturing is not the primary technique for the Dohlman procedure. - The goal is to **divide the septum**, not to suture or reduce the pouch itself. *Laser division of pouch* - **Laser division** of the cricopharyngeal muscle is another endoscopic approach, often called **endoscopic laser diverticulostomy**. - While effective, this is a **different technique** from the Dohlman procedure, which specifically uses electrocautery. *Endoscopic stapling of septum* - **Endoscopic stapling** (using an endoscopic stapler to divide the septum) is associated with the **Collard-Peracchia technique** or endoscopic stapling diverticulostomy. - While this is a modern and effective approach, it is **not the Dohlman procedure**, which historically and traditionally refers to the electrocautery technique.