Microbiology
2 questionsA patient with sore throat has a positive Paul Bunnell test, indicating infectious mononucleosis. The causative organism is?
Which of the following statements is true regarding T cell independent antigens?
NEET-PG 2012 - Microbiology NEET-PG Practice Questions and MCQs
Question 751: A patient with sore throat has a positive Paul Bunnell test, indicating infectious mononucleosis. The causative organism is?
- A. EBV (Correct Answer)
- B. Adenovirus
- C. CMV
- D. HSV (Herpes Simplex Virus)
Explanation: ***Correct: EBV*** - The **Paul-Bunnell test** (monospot test) detects **heterophile antibodies**, which are characteristic of acute **Epstein-Barr virus (EBV)** infection. - **EBV** is the primary causative agent of **infectious mononucleosis**, commonly known as "mono." *Incorrect: Adenovirus* - **Adenoviruses** can cause various infections, including **pharyngitis** and **conjunctivitis**, but are not associated with a positive **Paul-Bunnell test** or heterophile antibodies. - While it can cause sore throat, the presence of a **positive Paul-Bunnell test** differentiates it from EBV. *Incorrect: CMV* - **Cytomegalovirus (CMV)** can cause a mononucleosis-like syndrome, but it typically results in a **negative Paul-Bunnell test** (i.e., it is heterophile antibody-negative). - CMV mononucleosis is often seen in individuals who are **immunocompromised** or in infants as a congenital infection. *Incorrect: HSV (Herpes Simplex Virus)* - **Herpes simplex virus (HSV)** causes infections such as **oral herpes (cold sores)** and **genital herpes**, and in some cases, **pharyngitis**. - HSV infection is not associated with a positive **Paul-Bunnell test** or the production of heterophile antibodies.
Question 752: Which of the following statements is true regarding T cell independent antigens?
- A. They primarily activate T-cells.
- B. They primarily activate B-cells. (Correct Answer)
- C. They primarily activate macrophages.
- D. They primarily activate CD8+ T cells.
Explanation: ***Correct: They primarily activate B-cells*** - T-cell independent antigens are typically **polysaccharides** (TI-2) or **lipopolysaccharides** (TI-1) with repeating epitopes that can directly cross-link B cell receptors (BCRs) - This direct binding and cross-linking provide a strong enough signal to activate B cells and induce **antibody production** (mainly IgM) without the need for T cell help - They induce a rapid but limited immune response with minimal memory formation *Incorrect: They primarily activate T-cells* - T-cell independent antigens do not require processing and presentation by **MHC molecules**, which is essential for T cell activation - T cells recognize processed peptides presented by MHC, a mechanism not utilized by T-cell independent antigens - By definition, these antigens activate B cells **without** T cell involvement *Incorrect: They primarily activate macrophages* - While macrophages are antigen-presenting cells, their primary role in adaptive immunity is to process and present antigens to T cells - Macrophages are involved in **phagocytosis** and antigen processing, but are not the primary target cells for T-independent antigens - The key feature of TI antigens is direct B cell activation, not macrophage activation *Incorrect: They primarily activate CD8+ T cells* - **CD8+ T cells** are activated by processed antigens presented on **MHC class I molecules**, typically derived from intracellular pathogens - T-cell independent antigens do not utilize this pathway and are primarily involved in **humoral immunity** through direct B cell activation - TI antigens cannot activate CD8+ T cells as they bypass the T cell-dependent pathway entirely
Ophthalmology
2 questionsWhat is the primary complication associated with Eale's disease?
What is the most common type of congenital cataract?
NEET-PG 2012 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 751: What is the primary complication associated with Eale's disease?
- A. Retinal hemorrhage
- B. Vitreous hemorrhage (Correct Answer)
- C. Conjunctival hemorrhage
- D. Choroidal hemorrhage
Explanation: ***Vitreous hemorrhage*** - **Vitreous hemorrhage** is a common and often visually debilitating complication of Eale's disease, resulting from the rupture of fragile new vessels. - The proliferative stage of Eale's disease involves the development of **neovascularization** on the retina, which can bleed into the vitreous humor. *Retinal hemorrhage* - While **retinal hemorrhages** can occur in Eale's disease, they are often precursors to or components of vitreous hemorrhage, not the primary, most significant complication. - Retinal hemorrhages alone may cause less severe vision loss compared to the extensive obscuration by vitreous bleeding. *Conjunctival hemorrhage* - **Conjunctival hemorrhage** involves bleeding in the superficial layers of the eye and is not typically associated with the underlying vasculitis of Eale's disease. - This is a benign condition and not a primary complication of a retinal vascular disorder. *Choroidal hemorrhage* - **Choroidal hemorrhage** occurs beneath the retina and is usually associated with trauma, surgery, or degenerative conditions like age-related macular degeneration, not Eale's disease. - Eale's disease primarily affects the **retinal vasculature**, leading to bleeding internally into the vitreous.
Question 752: What is the most common type of congenital cataract?
- A. Blue dot (Correct Answer)
- B. Capsular
- C. Coralliform
- D. Zonular
Explanation: ***Blue dot*** - **Blue dot (punctate) cataracts** are the **most common type of congenital cataract overall**. - They appear as **multiple small, blue-white opacities** scattered throughout the lens cortex. - These cataracts are typically **bilateral, non-progressive, and asymptomatic**, rarely affecting visual acuity. - Often considered **physiological variants**, they usually do not require surgical intervention. *Zonular (Lamellar)* - **Zonular (lamellar) cataracts** are the **most common visually significant** congenital cataract. - They feature **opacities arranged in layers or lamellae** within the lens, classically with alternating clear and opaque zones. - Unlike blue dot cataracts, these **often require surgical intervention** due to visual impairment. *Capsular* - **Capsular cataracts** involve the anterior or posterior lens capsule and are relatively uncommon. - They appear as **small, well-circumscribed opacities** on the lens capsule. - Visual impact depends on size and location relative to the visual axis. *Coralliform* - **Coralliform cataracts** are a rare type characterized by **coral-like branching opacities**. - This distinctive morphology makes them one of the less common congenital cataract types.
Pathology
1 questionsER positive status in carcinoma breast indicates?
NEET-PG 2012 - Pathology NEET-PG Practice Questions and MCQs
Question 751: ER positive status in carcinoma breast indicates?
- A. Prognosis (Correct Answer)
- B. Etiology
- C. Site
- D. None of the options
Explanation: ***Prognosis*** - **ER positive status** in breast cancer indicates a better prognosis, as these tumors often respond well to hormone therapy [1][2]. - Patients with **ER positive** breast cancer usually have a lower risk of metastasis compared to **ER negative** tumors, making the outcome more favorable [1]. *Site* - ER status does not provide information regarding the **anatomical location** of the breast cancer, as it can be present in different sites of the breast. - It primarily focuses on the **biologic characteristics** of the tumor rather than its site of occurrence [1]. *None* - Selecting 'None' suggests that ER positive status has no relevance, which is incorrect as it is significant for treatment and prognosis [1]. - It is a crucial indicator for deciding on **endocrine therapy**, impacting management strategies in breast cancer patients [1]. *Etiology* - ER positive status does not directly indicate the **cause** of breast cancer, as various genetic and environmental factors contribute to its development. - It mainly reflects tumor behavior and response to therapies, not the **underlying factors** that lead to the disease [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, p. 1056. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Breast, pp. 1064-1066.
Pharmacology
5 questionsWhat is Dinoprost?
Which diuretic exhibits paradoxical antidiuretic activity in diabetes insipidus?
Which of the following is the most common side effect of Cimetidine?
Romiplostim mimics which of the following receptors?
Which of the following is not a selective serotonin reuptake inhibitor?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 751: What is Dinoprost?
- A. Prostaglandin E2 (PGE2)
- B. Prostaglandin F2α (PGF2α) (Correct Answer)
- C. Prostaglandin I2 (PGI2)
- D. Prostaglandin E1 (PGE1)
Explanation: ***Prostaglandin F2α (PGF2α)*** - **Dinoprost** is the generic name for **Prostaglandin F2α**. - It works by stimulating **myometrial contractions** and promoting cervical ripening, making it useful in obstetrics. *Prostaglandin E2 (PGE2)* - **PGE2** is known as **Dinoprostone** and is also used for cervical ripening and labor induction. - While similar in function, **Dinoprostone** (PGE2) is distinct from **Dinoprost** (PGF2α). *Prostaglandin I2 (PGI2)* - **PGI2** is also known as **Prostacyclin** and acts as a potent **vasodilator** and **inhibitor of platelet aggregation**. - Its primary therapeutic uses are in conditions like **pulmonary hypertension**, which differs from Dinoprost's obstetric uses. *Prostaglandin E1 (PGE1)* - **PGE1** is also known as **Alprostadil** and is used to maintain the **patency of the ductus arteriosus** in neonates with certain congenital heart defects. - It is distinct from Dinoprost and has different clinical applications.
Question 752: Which diuretic exhibits paradoxical antidiuretic activity in diabetes insipidus?
- A. Thiazide diuretics (Correct Answer)
- B. Aldosterone antagonists (Spironolactone)
- C. Loop diuretics (Furosemide)
- D. Potassium-sparing diuretics (Triamterene)
Explanation: ***Thiazide diuretics*** - Thiazides cause a modest **volume depletion**, leading to increased proximal tubular reabsorption of water and solutes [1]. - They also lower the **glomerular filtration rate**, further reducing the amount of fluid delivered to the collecting ducts, thus paradoxically reducing urine output in diabetes insipidus [2]. - This effect is particularly useful in **nephrogenic diabetes insipidus**, where the kidneys cannot respond to ADH [2]. *Potassium-sparing diuretics (Triamterene)* - Triamterene is a **potassium-sparing diuretic** that blocks epithelial sodium channels in the late distal tubule and collecting duct. - It increases sodium and water excretion, which would worsen, not improve, the polyuria of diabetes insipidus. *Aldosterone antagonists (Spironolactone)* - Spironolactone is a **mineralocorticoid receptor antagonist** that increases sodium and water excretion while conserving potassium in the collecting duct. - Its primary action is to counteract aldosterone, and it does not exhibit the paradoxical antidiuretic effect seen with thiazides in diabetes insipidus. *Loop diuretics (Furosemide)* - Loop diuretics like furosemide act on the **thick ascending limb of the loop of Henle** to inhibit sodium, potassium, and chloride reabsorption. - They cause significant diuresis and would **exacerbate the polyuria** in patients with diabetes insipidus, rather than improving it.
Question 753: Which of the following is the most common side effect of Cimetidine?
- A. Diarrhea
- B. Impotence
- C. CNS effects (confusion, dizziness) (Correct Answer)
- D. Gynaecomastia
Explanation: ***CNS effects (confusion, dizziness)*** - **Cimetidine** is a **H2-receptor antagonist** that can cross the **blood-brain barrier**, leading to **central nervous system (CNS) side effects**. - These effects, including **confusion, dizziness**, and **headache**, are more common in elderly patients or those with renal impairment due to reduced drug clearance. *Impotence* - While **cimetidine** can cause **endocrine effects** due to its anti-androgenic activity, **impotence** is a less common side effect compared to CNS disturbances. - It results from the drug's interference with **testosterone metabolism** and binding to **androgen receptors**. *Gynaecomastia* - **Gynaecomastia** is a known **endocrine side effect** of **cimetidine** due to its **anti-androgenic activity** and promotion of **prolactin release**. - However, CNS side effects are generally encountered more frequently in clinical practice. *Diarrhea* - **Gastrointestinal side effects** like **diarrhea** are possible with various medications, but they are not the most common or characteristic side effect of **cimetidine**. - Nausea and constipation are also reported, but generally less frequently than CNS effects.
Question 754: Romiplostim mimics which of the following receptors?
- A. IL 6
- B. IL 8
- C. PGE 1
- D. Thrombopoietin (Correct Answer)
Explanation: ***Thrombopoietin*** - **Romiplostim** is a **thrombopoietin receptor agonist**, meaning it binds to and activates the **thrombopoietin receptor** [1]. - This activation mimics the effect of endogenous thrombopoietin, stimulating the production of **platelets** in the bone marrow [2].*IL 6* - **Interleukin-6 (IL-6)** is a cytokine involved in inflammation, immune response, and hematopoiesis, but it is not the primary target of romiplostim. - While IL-6 can influence platelet production indirectly, romiplostim directly targets the thrombopoietin pathway.*IL 8* - **Interleukin-8 (IL-8)** is a chemokine primarily involved in neutrophil chemotaxis and inflammation. - It plays no direct role in the mechanism of action of romiplostim.*PGE 1* - **Prostaglandin E1 (PGE1)** is a lipid compound with various effects, including vasodilation and inhibition of platelet aggregation. - Romiplostim's mechanism of action is distinct from that of prostaglandins, as it specifically targets platelet production rather than platelet function or vascular tone.
Question 755: Which of the following is not a selective serotonin reuptake inhibitor?
- A. Buspirone (Correct Answer)
- B. Citalopram
- C. Fluoxetine
- D. Fluvoxamine
Explanation: ***Buspirone*** - **Buspirone** is an anxiolytic that primarily acts as a **serotonin 5-HT1A receptor partial agonist**, not an SSRI. - It does not significantly affect the reuptake of serotonin, distinguishing it from SSRIs. *Fluoxetine* - **Fluoxetine** is a well-known and widely used **SSRI**. - It works by selectively inhibiting the reuptake of serotonin, thereby increasing its concentration in the synaptic cleft. *Fluvoxamine* - **Fluvoxamine** is another antidepressant classified as an **SSRI**. - It is often used for the treatment of **obsessive-compulsive disorder (OCD)** due to its strong serotonin reuptake inhibition. *Citalopram* - **Citalopram** is an **SSRI** frequently prescribed for depression and anxiety disorders. - Its mechanism involves potent and selective inhibition of **serotonin reuptake**.