Biochemistry
1 questionsClinical effect of vitamin D is reduced by ?
NEET-PG 2013 - Biochemistry NEET-PG Practice Questions and MCQs
Question 581: Clinical effect of vitamin D is reduced by ?
- A. Simultaneous ingestion of lactose
- B. Simultaneous ingestion of phytates (Correct Answer)
- C. None of the options
- D. Acidic environment
Explanation: ***Simultaneous ingestion of phytates*** - **Phytates (phytic acid)** found in whole grains, nuts, seeds, and legumes can **reduce the clinical effect of vitamin D** through multiple mechanisms - Phytates **chelate calcium** and form insoluble calcium-phytate complexes, reducing calcium absorption - Since **vitamin D and calcium metabolism are closely linked**, impaired calcium absorption indirectly reduces vitamin D efficacy - Phytates can also **directly bind to vitamin D** in the gastrointestinal tract, reducing its bioavailability - Studies show that **high phytate intake increases vitamin D requirements** and can impair vitamin D status *Simultaneous ingestion of lactose* - Lactose does **not reduce** vitamin D absorption or efficacy - In fact, **dairy products are commonly fortified** with vitamin D, and the presence of lactose does not interfere with its beneficial effects - Lactose may actually **enhance calcium absorption**, which works synergistically with vitamin D *Acidic environment* - Vitamin D is a **fat-soluble vitamin** absorbed primarily in the small intestine - An acidic environment (stomach acid) is **not known to inhibit** vitamin D absorption - The absorption process occurs in the **alkaline environment of the small intestine** where fat-soluble vitamins are absorbed with dietary fats *None of the options* - This is **incorrect** as phytates do reduce the clinical effect of vitamin D through calcium chelation and direct binding mechanisms
Community Medicine
1 questionsWhich of the following is the most effective method of health communication for promoting vaccination awareness in rural communities?
NEET-PG 2013 - Community Medicine NEET-PG Practice Questions and MCQs
Question 581: Which of the following is the most effective method of health communication for promoting vaccination awareness in rural communities?
- A. Providing medical information without considering cultural context
- B. One-way communication from health provider to patient without feedback
- C. Use of mass media only for disseminating health information
- D. Interactive communication involving active participation of both provider and patient (Correct Answer)
Explanation: ***Correct Option: Interactive communication involving active participation of both provider and patient*** - This is the **most effective method** for promoting vaccination awareness in rural communities because it allows for **two-way dialogue** and addresses specific community concerns. - It enables **culturally sensitive communication** by incorporating local beliefs, values, and practices into the health messaging. - Promotes **trust-building** between healthcare providers and community members, which is crucial for vaccination acceptance. - Allows for **immediate clarification** of doubts, myths, and misconceptions about vaccines. - Facilitates **shared decision-making** and empowers individuals to take ownership of their health decisions. - In rural communities with varying literacy levels, interactive communication can be adapted to suit different educational backgrounds. *Incorrect Option: One-way communication from health provider to patient without feedback* - While it can deliver information, **lack of feedback mechanism** prevents addressing concerns or clarifying misinformation. - Does not foster **trust or engagement**, which are crucial for behavior change in vaccination uptake. - Cannot adapt to the specific needs, concerns, or cultural contexts of rural communities. *Incorrect Option: Use of mass media only for disseminating health information* - Mass media can raise general awareness but is **too impersonal and broad** to address specific community concerns effectively. - Limited by **lack of personalization** and opportunities for direct interaction or clarification. - May not reach all segments of rural populations due to literacy barriers, language differences, or limited access to media. *Incorrect Option: Providing medical information without considering cultural context* - This is **highly ineffective** because cultural beliefs, values, and practices heavily influence health perceptions and vaccination behaviors. - Ignoring cultural context leads to **misunderstanding, mistrust**, and rejection of health messages. - Can cause **cultural insensitivity** and alienate the target community, reducing vaccination acceptance.
Microbiology
2 questionsMost common organism causing ventilator associated pneumonia -
Macrophage tropic strains of HIV use which co-receptor?
NEET-PG 2013 - Microbiology NEET-PG Practice Questions and MCQs
Question 581: Most common organism causing ventilator associated pneumonia -
- A. Legionella
- B. Pneumococcus
- C. Pseudomonas (Correct Answer)
- D. Coagulase negative staphylococcus
Explanation: ***Pseudomonas*** - **Pseudomonas aeruginosa** is one of the most common causes of **ventilator-associated pneumonia (VAP)**, particularly in **late-onset VAP** (≥5 days) and in patients with prolonged mechanical ventilation, prior antibiotic exposure, or underlying lung disease. - Its ability to form **biofilms** and its intrinsic antibiotic resistance contribute to its prevalence in hospital-acquired infections. - Along with **Staphylococcus aureus** (especially MRSA), Pseudomonas is consistently among the leading causes of VAP in ICU settings. *Legionella* - **Legionella** is a less common cause of VAP and is typically associated with contaminated water sources, manifesting as **Legionnaires' disease**. - It usually causes severe, rapidly progressive pneumonia and is often harder to culture than other bacteria. *Pneumococcus* - **Streptococcus pneumoniae (Pneumococcus)** is the most common cause of **community-acquired pneumonia (CAP)**, but it is less frequently implicated in VAP. - While it can cause severe pneumonia and may be seen in **early-onset VAP**, its incidence in late-onset VAP is lower compared to Gram-negative rods like Pseudomonas. *Coagulase negative staphylococcus* - **Coagulase-negative Staphylococci** (e.g., *Staphylococcus epidermidis*) are common **contaminants** in cultures and primarily cause device-related infections, such as those associated with central venous catheters. - They are rarely a primary cause of VAP, as they typically have low virulence in the respiratory tract.
Question 582: Macrophage tropic strains of HIV use which co-receptor?
- A. CCR5 (Correct Answer)
- B. CXCR4
- C. CCR3
- D. CCR2
Explanation: ***CCR5*** - **Macrophage-tropic** HIV strains, also known as **R5 strains**, primarily use the **CCR5 co-receptor** to enter target cells. - These strains are typically involved in the **initial infection** and transmission of HIV. - CCR5-tropic viruses are usually the **predominant strains transmitted** during sexual transmission. *CXCR4* - **T-cell-tropic** HIV strains, or **X4 strains**, preferentially utilize the **CXCR4 co-receptor** for cell entry. - These strains are associated with a **more rapid decline in CD4+ T-cell counts** during later stages of HIV infection. - Emergence of X4 strains is linked to **disease progression**. *CCR3* - While a chemokine receptor, **CCR3** is not a primary co-receptor used by common HIV strains for entry into macrophages or T cells. - CCR3 is primarily involved in **eosinophil chemotaxis** and allergic responses. *CCR2* - **CCR2** is another chemokine receptor but is **not a major co-receptor** for HIV entry. - While some laboratory-adapted strains may show minor usage, it is not clinically significant for macrophage-tropic HIV strains.
Pharmacology
6 questionsFirst generation cephalosporins are active against?
Which of the following medications is most likely to cause reflex tachycardia?
Which anticancer drug is known to inhibit spindle formation during cell division?
Which drug is used for sympathectomy in experimental animals?
What is the mechanism of action of Warfarin?
Ranibizumab is a monoclonal antibody against?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 581: First generation cephalosporins are active against?
- A. Gram negative bacteria
- B. Gram positive bacteria (Correct Answer)
- C. Anaerobes
- D. Dermatophytes
Explanation: ***Gram positive bacteria*** - First-generation cephalosporins, such as **cefazolin** and **cephalexin**, primarily exhibit excellent activity against many **Gram-positive cocci**, including **staphylococci** and **streptococci**. - They are commonly used for skin and soft tissue infections and surgical prophylaxis due to this Gram-positive coverage. *Gram negative bacteria* - While first-generation cephalosporins have *some* activity against limited Gram-negative bacteria (e.g., *E. coli*, *Klebsiella pneumoniae*, *P. mirabilis*), their spectrum is generally weak and unreliable compared to later generations of cephalosporins. - They are not the drug of choice for serious Gram-negative infections. *Anaerobes* - First-generation cephalosporins have **poor activity** against most **anaerobic bacteria**. - For infections involving anaerobes, other antibiotics like **metronidazole**, **clindamycin**, or later-generation cephalosporins (e.g., cefoxitin, cefotetan) are generally preferred. *Dermatophytes* - Dermatophytes are **fungi** that cause skin, hair, and nail infections. - Cephalosporins are **antibacterial agents** and have **no activity** against fungi. Antifungal medications are required to treat dermatophyte infections.
Question 582: Which of the following medications is most likely to cause reflex tachycardia?
- A. Nifedipine (Correct Answer)
- B. Verapamil
- C. Propranolol
- D. Amlodipine
Explanation: ***Nifedipine*** - Nifedipine is a **dihydropyridine calcium channel blocker** that causes significant peripheral vasodilation, leading to a rapid drop in blood pressure. - This sudden drop in blood pressure triggers a **baroreflex response**, compensatory increase in heart rate. *Verapamil* - Verapamil is a **non-dihydropyridine calcium channel blocker** that primarily acts on the cardiac pacemaker cells and slows AV nodal conduction. - While it can cause vasodilation, its direct negative chronotropic effect on the heart often **blunts or prevents reflex tachycardia**. *Propranolol* - Propranolol is a **non-selective beta-blocker** that blocks beta-1 and beta-2 adrenergic receptors. - It directly **decreases heart rate and myocardial contractility**, thereby preventing reflex tachycardia. *Amlodipine* - Amlodipine is a **dihydropyridine calcium channel blocker**, similar to nifedipine, but it has a **slower onset of action and a longer half-life**. - Its more gradual onset of vasodilation often results in a significantly **less pronounced or absent reflex tachycardia** compared to nifedipine.
Question 583: Which anticancer drug is known to inhibit spindle formation during cell division?
- A. Busulfan
- B. Vinca alkaloids (Correct Answer)
- C. 5-FU
- D. Methotrexate
Explanation: ***Vinca alkaloids*** - **Vinca alkaloids**, such as **vincristine** and **vinblastine**, bind to **tubulin** and prevent its polymerization into microtubules. - This action effectively **inhibits the formation of the mitotic spindle**, leading to metaphase arrest and ultimately cell death. *Busulfan* - **Busulfan** is an **alkylating agent** that **cross-links DNA**, thereby interfering with DNA replication and transcription. - Its primary mechanism is **DNA damage**, not direct inhibition of spindle formation. *5-FU* - **5-fluorouracil (5-FU)** is an **antimetabolite** that inhibits **thymidylate synthase**, thereby impairing DNA synthesis and repair. - It acts by **mimicking pyrimidine bases** and incorporating into DNA and RNA, leading to cellular dysfunction. *Methotrexate* - **Methotrexate** is an **antifolate** drug that inhibits **dihydrofolate reductase**, an enzyme crucial for the synthesis of purines and pyrimidines. - This enzyme inhibition leads to **impaired DNA and RNA synthesis**, impacting rapidly dividing cells.
Question 584: Which drug is used for sympathectomy in experimental animals?
- A. Guanethidine (Correct Answer)
- B. Atropine
- C. Diazoxide
- D. Thebaine
Explanation: ***Guanethidine*** - **Guanethidine** is a potent **adrenergic neuron blocking drug** that is taken up by noradrenergic neurons and prevents the release of norepinephrine, leading to a chemical sympathectomy. - In experimental animal models, it is used to induce a **pharmacological sympathectomy** to study the effects of sympathetic nervous system blockade on various physiological processes. *Atropine* - **Atropine** is a **muscarinic acetylcholine receptor antagonist** that blocks the effects of acetylcholine at parasympathetic postganglionic terminals. - It is primarily used to block **parasympathetic responses**, not sympathetic ones, and therefore would not induce a sympathectomy. *Diazoxide* - **Diazoxide** is a direct **arteriolar vasodilator** that works by opening potassium channels in vascular smooth muscle. - It is used to quickly reduce blood pressure in **hypertensive emergencies** and for treating hypoglycemia due to insulin oversecretion, and does not cause sympathectomy. *Thebaine* - **Thebaine** is an **opioid alkaloid** found in opium, structurally similar to morphine and codeine, but with primarily stimulatory rather than depressant effects. - It acts as a **convulsant** and is used as a precursor in the synthesis of other opioids, but has no role in causing sympathectomy.
Question 585: What is the mechanism of action of Warfarin?
- A. Inhibition of Vitamin K epoxide reductase (Correct Answer)
- B. Inhibition of gamma glutamyl carboxylase
- C. Activation of Vitamin K epoxide reductase
- D. Activation of gamma glutamyl carboxylase
Explanation: ***Inhibition of Vitamin K epoxide reductase*** - Warfarin blocks **Vitamin K epoxide reductase (VKORC1)** [1, 2, 3], an enzyme essential for recycling oxidized vitamin K into its active reduced form [1, 3]. - This reduction prevents the activation of **vitamin K-dependent clotting factors** (II, VII, IX, X), leading to anticoagulation [1, 3]. *Inhibition of gamma glutamyl carboxylase* - **Gamma-glutamyl carboxylase** uses reduced vitamin K as a cofactor to carboxylate specific glutamic acid residues on clotting factors [1, 3]. - While essential for clotting factor activation, this enzyme itself is **not directly inhibited by warfarin** [1, 3]. *Activation of Vitamin K epoxide reductase* - Activating **VKORC1** would increase the production of reduced vitamin K, thereby **promoting coagulation** rather than inhibiting it [1, 2]. - This is the opposite of warfarin's intended therapeutic effect. *Activation of gamma glutamyl carboxylase* - Activating **gamma-glutamyl carboxylase** would enhance the carboxylation and activation of **clotting factors**, leading to procoagulant effects [1, 3]. - This mechanism contradicts warfarin's role as an **anticoagulant**.
Question 586: Ranibizumab is a monoclonal antibody against?
- A. VEGF (Correct Answer)
- B. Interleukin-6
- C. Cluster of Differentiation 20
- D. Epidermal Growth Factor Receptor
Explanation: ***VEGF*** - **Ranibizumab** is a **monoclonal antibody** specifically designed to inhibit **vascular endothelial growth factor A (VEGF-A)**. - By binding to VEGF-A, ranibizumab prevents its interaction with receptors on endothelial cells, thereby inhibiting **angiogenesis** and reducing vascular permeability, which is crucial in treating conditions like **wet age-related macular degeneration (AMD)** and **diabetic macular edema**. *Interleukin-6* - **Interleukin-6 (IL-6)** is a **pro-inflammatory cytokine** involved in various autoimmune and inflammatory diseases. - Monoclonal antibodies targeting IL-6, such as **tocilizumab**, are used in conditions like **rheumatoid arthritis** and **cytokine release syndrome**, not for ocular neovascularization. *Cluster of Differentiation 20* - **Cluster of Differentiation 20 (CD20)** is a protein found on the surface of **B lymphocytes**. - Monoclonal antibodies against CD20, like **rituximab**, are used in the treatment of **B-cell lymphomas**, **leukemia**, and certain **autoimmune diseases**, not for conditions requiring anti-VEGF therapy. *Epidermal Growth Factor Receptor* - The **epidermal growth factor receptor (EGFR)** is a **tyrosine kinase receptor** involved in cell growth and proliferation. - Monoclonal antibodies targeting EGFR, such as **cetuximab** and **panitumumab**, are used in the treatment of various **cancers**, particularly **colorectal cancer** and **head and neck cancer**.