Anatomy
1 questionsT cells in lymph node are present in:
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 591: T cells in lymph node are present in:
- A. Paracortical area (Correct Answer)
- B. Mantle layer
- C. Medullary cords
- D. Cortical follicles
Explanation: ***Paracortical area*** - The **paracortical area** contains a high concentration of **T cells**, particularly activated T cells in response to antigenic stimulation [1]. - It plays a crucial role in **immune responses**, bridging the cortex and medulla of the lymph node [1]. *Mantle layer* - The **mantle layer** surrounds the follicles and primarily consists of **B cells**, not T cells. - It is involved in the initial immune response but does not contain a significant number of T lymphocytes. *Medullary cords* - **Medullary cords** mainly contain **plasma cells** and macrophages, with very few T cells present. - Their primary function is the secretion of antibodies rather than T cell activation or response. *Cortical follicles* - **Cortical follicles** are primarily sites for **B cell activation and proliferation**. - While they may have some T cells at their periphery, the majority of T cells are located in the paracortical area.
Biochemistry
1 questionsWhat is the role of Anandamide in the human body?
NEET-PG 2013 - Biochemistry NEET-PG Practice Questions and MCQs
Question 591: What is the role of Anandamide in the human body?
- A. Opioid
- B. D2 blocker
- C. Cannabinoid neurotransmitter (Correct Answer)
- D. CCK1 antagonist
Explanation: ***Cannabinoid neurotransmitter*** - **Anandamide** is an **endogenous cannabinoid neurotransmitter** that binds to **CB1** and **CB2 receptors**. - It plays a role in **pain modulation**, **appetite stimulation**, and **memory regulation**. *Opioid* - **Opioids** bind to **opioid receptors** (mu, delta, kappa) and are known for their **analgesic** and **euphoric effects**. - Examples include **morphine** and **endorphins**, which are chemically distinct from anandamide and have different receptor targets. *CK 1 antagonist* - This option refers to a **cholecystokinin 1 (CCK1) receptor antagonist**, which would block the effects of **CCK**. - **CCK** is a hormone involved in **digestion** and **satiety**, and its role is unrelated to anandamide. *D2 blocker* - A **D2 blocker** is an agent that antagonizes the **dopamine D2 receptor**. - These are typically **antipsychotic medications** that modulate **dopamine pathways** in the brain, unrelated to the function of anandamide.
Community Medicine
1 questionsMalaria is transmitted in Rural areas by?
NEET-PG 2013 - Community Medicine NEET-PG Practice Questions and MCQs
Question 591: Malaria is transmitted in Rural areas by?
- A. Anopheles stephensi
- B. Anopheles dirus
- C. Anopheles culicifacies (Correct Answer)
- D. None of the options
Explanation: ***Anopheles culicifacies*** - **_Anopheles culicifacies_** is the **primary vector of malaria in rural areas of India** and is also found in Southeast Asia. - Its breeding habitats often include **rice fields, irrigation channels, and temporary water collections** common in rural agricultural settings. - It accounts for a major proportion of rural malaria transmission in the Indian subcontinent. *Anopheles stephensi* - **_Anopheles stephensi_** is a significant malaria vector primarily found in **urban and semi-urban areas**, including parts of the Middle East, India, and Iran. - Its preferred breeding sites are **artificial containers found in urban environments**, such as water storage tanks, overhead tanks, and cisterns. *Anopheles dirus* - **_Anopheles dirus_** is a dominant malaria vector in **forested and hilly regions of Southeast Asia**, often associated with forest malaria. - It's known for outdoor feeding behavior and maintaining transmission in relatively undisturbed natural environments. *None of the options* - This option is incorrect because **_Anopheles culicifacies_** is a well-established and significant vector for malaria in rural areas of India. - Identification of a specific primary vector for rural transmission makes this choice invalid.
Pharmacology
7 questionsAminophylline inhibits which of the following enzymes?
Most clinically significant side effect of topiramate requiring immediate medical attention?
What serious side effect may lead to the discontinuation of felbamate?
Which of the following is a metabolite of hydroxyzine?
Which second generation antihistaminic does not produce an active metabolite?
Which of the following is NOT a function of Prostaglandin E1 (PGE1)?
What is a common side effect of salmeterol?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 591: Aminophylline inhibits which of the following enzymes?
- A. MAO
- B. Alcohol dehydrogenase
- C. Cytochrome P450
- D. Phosphodiesterase (Correct Answer)
Explanation: ***Phosphodiesterase*** - **Aminophylline** is a methylxanthine derivative that primarily acts as a **phosphodiesterase (PDE) inhibitor** [1], [2]. - By inhibiting PDE, aminophylline increases intracellular levels of **cAMP** and **cGMP**, leading to **bronchodilation** and other effects [2], [3]. *MAO* - **MAO (monoamine oxidase)** inhibitors are antidepressants that prevent the breakdown of neurotransmitters like serotonin, norepinephrine, and dopamine. - Aminophylline does not significantly inhibit MAO. *Alcohol dehydrogenase* - **Alcohol dehydrogenase** is an enzyme responsible for metabolizing alcohol (ethanol) in the liver. - Aminophylline has no direct inhibitory effect on alcohol dehydrogenase. *Cytochrome P450* - **Cytochrome P450 (CYP450)** enzymes are a group of enzymes primarily involved in the metabolism of drugs and other xenobiotics in the liver [4]. - While aminophylline (and its active metabolite theophylline) can be metabolized by and *affect* certain **CYP450** isoenzymes (e.g., CYP1A2), it does not act as a general inhibitor of the entire CYP450 system; its primary therapeutic action is not through CYP450 inhibition.
Question 592: Most clinically significant side effect of topiramate requiring immediate medical attention?
- A. Weight loss
- B. Visual impairment (Correct Answer)
- C. Insomnia
- D. Hemolysis
Explanation: ***Visual impairment*** - Topiramate can cause **acute angle-closure glaucoma**, a medical emergency that typically occurs within the **first month of therapy**. - Mechanism: Topiramate causes **ciliary body swelling** and **uveal effusion**, leading to anterior rotation of the iris-lens diaphragm and angle closure. - Clinical presentation: Rapid-onset **blurred vision**, **eye pain**, **headache**, **redness**, and may progress to permanent vision loss if untreated. - Management: **Immediate discontinuation** of topiramate and urgent **ophthalmology referral** for intraocular pressure management. *Weight loss* - Weight loss is a common and often desired side effect of topiramate, related to its effect on **appetite suppression** and enhanced satiety. - While it can be significant, it does not typically require immediate medical attention unless it becomes excessive or leads to nutritional deficiencies. - This side effect is sometimes therapeutically exploited in migraine prophylaxis. *Insomnia* - Insomnia is a known side effect of topiramate and can impact quality of life but is generally not life-threatening or an immediate medical emergency. - Management often involves adjusting the dosage, timing of administration (dosing earlier in the day), or prescribing sleep aids. *Hemolysis* - Hemolysis is **not a recognized side effect** of topiramate. - Topiramate is not known to directly cause the destruction of red blood cells. - Other serious side effects of topiramate include metabolic acidosis, kidney stones, and cognitive impairment, but not hemolysis.
Question 593: What serious side effect may lead to the discontinuation of felbamate?
- A. Seizures
- B. Renal impairment
- C. Gastrointestinal disorder
- D. Aplastic anemia (Correct Answer)
Explanation: ***Aplastic anemia*** - Felbamate is known to cause **aplastic anemia**, a severe and life-threatening condition where the **bone marrow stops producing enough new blood cells**. - Felbamate carries a **black box warning** for both aplastic anemia and **hepatotoxicity (severe liver failure)**, which are the two most serious adverse effects leading to discontinuation. - Due to this significant risk, felbamate is reserved for severe, refractory epilepsy cases, and patients require **regular monitoring** of blood counts and liver function tests. *Renal impairment* - While some medications can cause renal impairment, **felbamate is not primarily associated** with this side effect to the extent of requiring discontinuation. - Its metabolism and excretion are predominantly **hepatic (liver)**, and renal effects are less common or severe. *Gastrointestinal disorder* - Gastrointestinal side effects like nausea or vomiting are **common with many medications**, including felbamate, but are generally **mild and manageable**, rarely leading to discontinuation. - These effects are usually **dose-dependent** and can often be mitigated with supportive care. *Seizures* - Felbamate is an **antiepileptic drug (AED)**, so it is used to treat seizures, not cause them. - If a patient experiences seizures while on felbamate, it usually indicates **inadequate treatment response** or seizure exacerbation, rather than a direct side effect necessitating discontinuation for toxicity.
Question 594: Which of the following is a metabolite of hydroxyzine?
- A. Fexofenadine
- B. Terfenadine
- C. Cetirizine (Correct Answer)
- D. Azelastine
Explanation: ***Cetirizine*** - **Cetirizine** is the principal active metabolite of **hydroxyzine**, formed through the oxidation of the primary alcohol group of hydroxyzine [2]. - Both hydroxyzine and cetirizine are **H1-receptor antagonists**, but cetirizine is a **second-generation antihistamine** known for being less sedating due to its limited ability to cross the blood-brain barrier [2]. *Fexofenadine* - **Fexofenadine** is an active metabolite of **terfenadine**, not hydroxyzine [2]. - **Fexofenadine** is a second-generation antihistamine used to treat allergies, known for its non-sedating properties [3]. *Terfenadine* - **Terfenadine** is a second-generation antihistamine that was withdrawn from the market due to its cardiotoxicity, particularly the risk of **QT prolongation** and **Torsades de Pointes**. - Its active metabolite is **fexofenadine**, which does not cause similar cardiac issues [2]. *Azelastine* - **Azelastine** is an antihistamine primarily available as a **nasal spray** for the treatment of allergic rhinitis and conjunctivitis [1], [3]. - It is not a metabolite of hydroxyzine but a distinct therapeutic compound.
Question 595: Which second generation antihistaminic does not produce an active metabolite?
- A. Loratadine
- B. Terfenadine
- C. Cetirizine (Correct Answer)
- D. None of the options
Explanation: ***Cetirizine*** - Cetirizine is unique among second-generation antihistamines as it is an **active metabolite** of hydroxyzine and **does not undergo further significant metabolism** to an active compound. - This characteristic contributes to its relatively **predictable pharmacokinetics** and reduced potential for drug interactions related to metabolism. *Loratadine* - Loratadine is a **prodrug** that is extensively metabolized in the liver by **CYP3A4 and CYP2D6** to its active metabolite, **desloratadine**. - Desloratadine is responsible for most of the **antihistaminic effects** of loratadine. *Terfenadine* - Terfenadine is a **prodrug** that is extensively metabolized by **CYP3A4** to its active metabolite, **fexofenadine**. - Due to its **cardiotoxicity** (QT prolongation) when its metabolism was inhibited, terfenadine was withdrawn from the market, and fexofenadine was developed as a safer alternative. *None of the options* - This option is incorrect because **cetirizine** does not produce an active metabolite, making it a valid answer for the question.
Question 596: Which of the following is NOT a function of Prostaglandin E1 (PGE1)?
- A. Plays a role in initiating puberty (Correct Answer)
- B. Modulates inflammatory responses
- C. Used in the management of erectile dysfunction
- D. Maintains the patency of the ductus arteriosus
Explanation: ***Plays a role in initiating puberty*** - **Prostaglandin E1 (PGE1)** is primarily involved in smooth muscle relaxation, vasodilation, and inflammation, and does not have a direct role in initiating **puberty**. - The initiation of puberty is mainly controlled by the **hypothalamic-pituitary-gonadal (HPG) axis** and surge of **gonadotropin-releasing hormone (GnRH)**. *Used in the management of erectile dysfunction* - **PGE1 formulations** (alprostadil) are used as a topical or intracavernosal injection to treat **erectile dysfunction** by inducing vasodilation in the penis. - Its vasodilatory effects increase blood flow to the corpora cavernosa, leading to **penile erection**. *Modulates inflammatory responses* - **PGE1** is involved in **inflammatory processes**, often exerting both pro- and anti-inflammatory effects depending on the context and specific receptors activated. - It can help to **reduce inflammation** and pain, as well as influencing immune cell function. *Maintains the patency of the ductus arteriosus* - In newborns with **congenital heart defects**, **PGE1** is administered to maintain the **patency of the ductus arteriosus**, allowing for blood flow between the aorta and pulmonary artery. - This is crucial for conditions where pulmonary or systemic blood flow is dependent on a patent ductus, bridging the infant to surgery or other interventions.
Question 597: What is a common side effect of salmeterol?
- A. Tremors (Correct Answer)
- B. Seizures
- C. Hypertension
- D. Hyperkalemia
Explanation: ***Tremors*** - **Salmeterol** is a **long-acting beta-2 adrenergic agonist (LABA)** that can stimulate beta-2 receptors in skeletal muscle, leading to **fine muscle tremors**. - This side effect is dose-dependent and more common with higher doses or in patients sensitive to sympathomimetic effects. *Seizures* - **Seizures** are a rare and atypical side effect of **salmeterol** and other beta-2 agonists; they are not considered a common adverse event. - While systemic absorption can occur, the central nervous system effects leading to seizures are not frequently observed. *Hypertension* - While beta-2 agonists can cause a slight increase in **heart rate** due to systemic absorption, **hypertension** is not a common side effect of inhaled salmeterol. - Other cardiovascular effects like palpitations can occur, but significant or sustained hypertension is rare. *Hyperkalemia* - **Hyperkalemia** (elevated potassium) is not a side effect of **salmeterol**; in fact, beta-2 agonists commonly cause the **opposite effect - hypokalemia** (decreased serum potassium). - Beta-2 receptor stimulation activates Na⁺-K⁺-ATPase pumps, driving potassium from serum into cells, causing transient hypokalemia. - This effect is clinically relevant and requires monitoring, especially when combined with other medications that lower potassium.