Renin secretion is stimulated by all EXCEPT:

# Renin secretion is stimulated by all EXCEPT:

A. Cardiac failure

B. Low Na+ in proximal tubule

C. Sympathetic stimulation

D. High Na+ in proximal tubule

The correct answer is D. High Na+ in proximal tubule.

Explanation: Renin secretion, primarily by the juxtaglomerular cells in the kidneys, is stimulated by factors that signal a need to increase blood pressure or sodium retention. These include:

A. Cardiac failure: Reduced cardiac output lowers renal perfusion, stimulating renin release to activate the renin-angiotensin-aldosterone system (RAAS) to restore blood pressure.

B. Low Na+ in proximal tubule: Detected by the macula densa, low sodium levels signal reduced filtrate delivery, triggering renin secretion to promote sodium reabsorption and increase blood volume.

C. Sympathetic stimulation: Activation of the sympathetic nervous system, via beta-adrenergic receptors, directly stimulates renin release to address stress or low blood pressure.

D. High Na+ in proximal tubule, however, does not stimulate renin secretion. High sodium levels in the proximal tubule (or at the macula densa in the distal tubule) typically indicate adequate or excessive sodium delivery, suppressing renin release as there is no need to activate RAAS.

As no dental biomaterial is absolutely free from the potential risk of adverse reactions, the testing of biocompatibility is related to:

 # As no dental biomaterial is absolutely free from the potential risk of adverse reactions, the testing of biocompatibility is related to:

A. Risk factors

B. Risk assessment

C. Risk markers

D. Risk predictors

The correct answer is B. Risk assessment.

Explanation: Biocompatibility testing for dental biomaterials focuses on evaluating the potential for adverse biological reactions, such as toxicity or irritation, when the material interacts with the body. This process is a key component of risk assessment, which involves systematically identifying, analyzing, and evaluating risks to ensure the material is safe for use. By assessing these risks, manufacturers and clinicians can minimize potential harm to patients.

Traumatic injury of a nerve causing paresthesia is:

 # Traumatic injury of a nerve causing paresthesia is:

A. Neuropraxia

B. Neurotmesis

C. Axonotmesis

D. Toxolysis

The correct answer is A. Neuropraxia.

Explanation:

• Neuropraxia is the mildest form of traumatic nerve injury, involving a temporary conduction block due to compression or mild trauma. It often causes paresthesia (tingling or numbness) without significant structural damage to the nerve. Recovery is usually complete within days to weeks.
• Neurotmesis is the most severe nerve injury, involving complete nerve transection with disruption of the nerve and its sheath, leading to permanent loss of function unless surgically repaired. Paresthesia may occur, but it’s not the primary feature.
• Axonotmesis involves damage to the axons but preservation of the nerve’s connective tissue. It causes more severe symptoms than neuropraxia, with longer recovery times (weeks to months), and paresthesia may be present but is less characteristic.
• Toxolysis is not a standard term in nerve injury classification and is incorrect in this context.

Since the question specifies a traumatic nerve injury causing paresthesia (a sensory symptom like tingling), neuropraxia is the most fitting answer due to its association with mild, reversible sensory disturbances.

A tumor characterized by rapid rate of growth which almost doubles its size by next day:

 # A tumor characterized by rapid rate of growth  which almost doubles its size by next day:

A. Hodgkin’s Lymphoma

B. Malignant melanoma

C. African Burkitt’s jaw lymphoma

D. Squamous cell carcinoma

The correct answer is C. African Burkitt’s jaw lymphoma.

African Burkitt’s lymphoma, particularly the endemic form, is characterized by an extremely rapid growth rate, with tumors often doubling in size within 24 hours. This aggressive B-cell non-Hodgkin lymphoma is commonly seen in children in equatorial Africa and is strongly associated with Epstein-Barr virus (EBV). It frequently presents as a rapidly enlarging jaw or facial mass. While Hodgkin’s lymphoma, malignant melanoma, and squamous cell carcinoma can be aggressive, they do not typically exhibit such an exceptionally rapid doubling time as seen in Burkitt’s lymphoma.

Popsicle panniculitis can occur:

 # Popsicle panniculitis can occur:

A. Following prolonged exposure to analgesic powder

B. Following prolonged exposure to hot beverages

C. Following prolonged exposure to frozen food

D. Following prolonged exposure to a sharp tooth

The correct answer is C. Following prolonged exposure to frozen food.

Popsicle panniculitis is a form of cold-induced panniculitis, an inflammation of the subcutaneous fat, typically seen in infants or young children. It occurs due to prolonged exposure to cold objects, such as frozen food (e.g., popsicles), which can cause localized fat necrosis and inflammation. The condition is often seen on the cheeks or chin after contact with cold items. The other options—analgesic powder, hot beverages, or a sharp tooth—are not associated with this condition. 

The most common pathogens responsible for nosocomial pneumonias in the ICU are:

 # The most common pathogens responsible for nosocomial pneumonias in the ICU are:

A. Gram positive organisms

B. Gram negative organisms

C. Mycoplasma

D. Virus infections

The correct answer is B. Gram negative organisms.

Gram-negative bacteria, such as Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter species, are the most common pathogens responsible for nosocomial (hospital-acquired) pneumonias in the ICU. These organisms are often associated with ventilator-associated pneumonia (VAP) and thrive in the ICU environment due to factors like prolonged mechanical ventilation, invasive procedures, and antibiotic resistance. Gram-positive organisms (e.g., Staphylococcus aureus) are less common but still significant, while Mycoplasma and viral infections are rare causes of ICU-acquired pneumonia.

Chicken fat clot is:

# Chicken fat clot is:

A. Postmortem clot

B. Thrombus

C. Infarct

D. None of the above

The correct answer is A. Postmortem clot.

A chicken fat clot is a type of postmortem clot, typically seen in autopsies. It forms after death due to the settling of red blood cells and plasma, creating a layered appearance with a yellowish "chicken fat" layer of plasma and fibrin on top and a darker red blood cell layer below. Unlike a thrombus, which forms in living tissue and can obstruct blood flow, a chicken fat clot occurs post-mortem and is not associated with disease processes like infarction.

Therapy of choice for pockets with an edematous wall is:

 # Therapy of choice for pockets with an edematous wall is:

A. Scaling and root planing

B. Gingivectomy

C. Apically displaced flap

D. Root resection

The correct answer is A. Scaling and root planing.

This non-surgical procedure is typically the first line of treatment for periodontal pockets with edema, as it addresses the underlying inflammation and infection by removing plaque, tartar, and bacterial toxins from the tooth surfaces and root, promoting healing and reduction of pocket depth.

Paederus Dermatitis: What You Need to Know About This Painful Insect Reaction - Acid Fly - Nairobi Fly Dermatitis

 

Paederus Dermatitis: What You Need to Know About This Painful Insect Reaction

Introduction

Paederus dermatitis, also known as "rove beetle dermatitis" or "Nairobi fly dermatitis," is a painful and often alarming skin condition caused by contact with certain species of rove beetles, particularly those from the Paederus genus. These small insects don’t bite or sting, but their body fluids contain a potent toxin called pederin, which can cause severe skin irritation. I recently experienced this myself, resulting in a large, scary wound that prompted me to raise awareness about this little-known but dreadful insect. This article will explain what Paederus dermatitis is, its symptoms, causes, treatment, and prevention strategies to help you avoid the same discomfort.

Day 3 Crusting and healing of wound

Day 2 After contact with the Acid Fly

What is Paederus Dermatitis?

Paederus dermatitis is a type of irritant contact dermatitis caused by crushing a Paederus beetle against the skin. These beetles, often mistaken for ants or small flies, are typically 7–10 mm long, with a distinctive appearance featuring black and orange or red markings. They are commonly found in tropical and subtropical regions, including parts of Africa, Asia, South America, and Australia, often in warm, humid environments near agricultural fields or rivers.

Unlike bites or stings, the reaction occurs when the beetle’s hemolymph (body fluid), which contains pederin, comes into contact with the skin. This toxin is highly irritating and can cause painful, burning lesions that may last for days or weeks if not properly managed.

Symptoms of Paederus Dermatitis

The symptoms of Paederus dermatitis typically appear 12–48 hours after contact with the beetle and can vary in severity. Common symptoms include:

• Redness and Burning Sensation: The affected area becomes red and feels intensely warm or burning.
• Blisters and Lesions: Small blisters or pustules form, often progressing to larger, open sores or ulcers.
• Itching and Pain: The lesions are often itchy and painful, making it difficult to ignore.
• Linear Marks: The lesions may appear in streaks or linear patterns, as the beetle is often unknowingly brushed across the skin.
• Secondary Infections: Scratching the affected area can introduce bacteria, leading to infections that worsen the condition.

In my case, I developed a large, red, and painful wound that looked alarming and took weeks to heal fully. The delayed onset of symptoms can make it hard to connect the reaction to the beetle, as many people don’t recall encountering the insect.

Causes and Risk Factors

Paederus beetles are attracted to artificial lights, which often brings them into homes or outdoor areas at night. Crushing the beetle, either intentionally or accidentally (e.g., swatting it or brushing it off the skin), releases pederin, triggering the dermatitis. Key risk factors include:

• Geographic Location: Living in or visiting tropical or subtropical regions where these beetles are prevalent.
• Seasonal Factors: Outbreaks are more common during rainy seasons when beetle populations increase.
• Nighttime Exposure: The beetles are nocturnal and drawn to lights, increasing the risk of contact in the evening.
• Unawareness: Many people, including myself, are unaware of the beetle’s danger and may crush it, worsening the exposure.

Treatment and Management

If you suspect Paederus dermatitis, prompt action can reduce the severity of symptoms. Here’s what to do:

1. Wash the Area Immediately: If you believe you’ve come into contact with a beetle, wash the affected area with soap and water to remove any residual pederin. This can help minimize the reaction if done quickly.
2. Avoid Scratching: Scratching can worsen the lesions and lead to secondary infections.
3. Apply Cold Compresses: A cold compress can reduce burning and inflammation.
4. Use Topical Treatments: Over-the-counter hydrocortisone cream or antihistamines can help with itching and inflammation. For severe cases, consult a doctor for stronger topical or oral steroids.
5. Monitor for Infection: If the wound shows signs of infection (e.g., increased redness, swelling, or pus), seek medical attention. Antibiotics may be needed.
6. Keep the Area Clean and Dry: Proper hygiene can prevent complications and promote healing.

In my experience, washing the area and using a mild corticosteroid cream helped, but the wound still took time to heal. Consulting a healthcare professional early can make a significant difference.

Prevention Tips

Preventing Paederus dermatitis requires awareness and caution, especially in areas where these beetles are common. Here are some practical tips:

• Avoid Crushing Beetles: If you see a small black-and-orange insect, gently brush it off or blow it away rather than crushing it.
• Use Insect Screens: Install fine mesh screens on windows and doors to keep beetles out, especially at night.
• Limit Light Exposure: Turn off unnecessary outdoor lights or use yellow bulbs, which are less attractive to beetles.
• Wear Protective Clothing: Long sleeves and pants can reduce skin exposure when outdoors in beetle-prone areas.
• Check Bedding and Clothing: Shake out clothes, towels, or bedding before use, as beetles may hide in fabrics.
• Stay Informed: Learn to recognize Paederus beetles and their habitats, especially if you live in or travel to affected regions.

Conclusion

Paederus dermatitis is a painful and distressing condition that can catch anyone off guard, as it did me when I developed a large, alarming wound after unknowingly crushing a rove beetle. By understanding the causes, symptoms, and prevention strategies, you can protect yourself and your loved ones from this dreadful insect. If you suspect contact with a Paederus beetle, act quickly to minimize the reaction and seek medical advice if symptoms worsen. Awareness is key—stay vigilant, especially in warm, humid environments, and share this knowledge to help others avoid the same ordeal.

 

Temporary Anchorage Devices in Orthodontics: A Patient’s Guide

If you’re undergoing orthodontic treatment, you may have heard your orthodontist mention Temporary Anchorage Devices (TADs). These small, innovative tools have revolutionized modern orthodontics, offering precise and efficient solutions for complex tooth movements. This article explains what TADs are, how they work, their benefits, and what you can expect if they’re part of your treatment plan.

What Are Temporary Anchorage Devices (TADs)?

Temporary Anchorage Devices, or TADs, are small, screw-like devices made of biocompatible materials, such as titanium, that are temporarily placed in the jawbone to assist with orthodontic treatment. Think of them as stable anchors that provide a fixed point for moving teeth in ways that traditional braces or aligners alone might not achieve.

TADs are typically 6–12 mm long and about 1–2 mm in diameter, similar in size to a small earring post. They’re placed in specific areas of the mouth by an orthodontist or oral surgeon and removed once they’ve served their purpose.

How Do TADs Work?

Orthodontic treatment often involves applying controlled forces to move teeth into their desired positions. TADs act as anchors to support these forces, ensuring that only the targeted teeth move while others stay in place. Here’s a simple breakdown of how they work:

1. Placement: The orthodontist numbs the area with local anesthesia and gently inserts the TAD into the bone through the gum tissue. This is a quick, minimally invasive procedure, often taking just a few minutes.
2. Anchoring: Once in place, the TAD provides a stable point to attach orthodontic appliances, such as wires, springs, or elastic bands.
3. Tooth Movement: The TAD helps direct precise forces to move specific teeth or groups of teeth, allowing for complex movements like closing gaps, correcting bite issues, or aligning teeth more effectively.
4. Removal: After the desired tooth movement is achieved, the TAD is easily removed, and the area heals quickly.

Why Are TADs Used?

TADs are used to address a variety of orthodontic challenges that might be difficult or impossible to achieve with braces or aligners alone. Some common uses include:

• Closing Large Gaps: TADs can help close spaces between teeth, such as those caused by missing teeth.
• Correcting Severe Misalignments: They assist in moving teeth that are significantly out of position.
• Improving Bite Issues: TADs are often used to correct overbites, underbites, or open bites.
• Reducing the Need for Extractions: By providing precise control, TADs can sometimes eliminate the need to remove teeth to create space.
• Supporting Complex Cases: They’re especially helpful in adult orthodontics or cases where traditional methods are less effective.

Benefits of TADs

TADs offer several advantages that make them a valuable tool in orthodontics:

• Precision: They allow for highly controlled tooth movements, leading to more predictable results.
• Efficiency: TADs can reduce treatment time by enabling faster and more direct tooth movements.
• Minimally Invasive: Placement and removal are quick and typically involve minimal discomfort.
• Versatility: They can be used in a wide range of cases, from minor adjustments to complex treatments.
• Reduced Reliance on Patient Compliance: Unlike headgear or elastics, which depend on consistent wear, TADs work without requiring extra effort from the patient.

What to Expect During TAD Placement

If your orthodontist recommends TADs, here’s what you can expect:

• The Procedure: The area where the TAD will be placed is numbed with local anesthesia, so you’ll feel little to no pain. Some patients report mild pressure during insertion. The process is quick, often taking less than 10 minutes.
• After Placement: You may experience mild soreness or sensitivity for a day or two, similar to what you feel after getting braces adjusted. Over-the-counter pain relievers, like ibuprofen, can help if needed.
• Care Instructions: Keeping the area clean is important to prevent irritation or infection. Your orthodontist will provide guidance on brushing gently around the TAD and avoiding hard or sticky foods that could dislodge it.
• Duration: TADs are typically left in place for a few months to a year, depending on your treatment plan. Once their job is done, they’re removed in a simple procedure, and the gum tissue heals quickly.

Are There Any Risks?

TADs are generally safe, but like any dental procedure, there are minor risks, including:

• Mild Discomfort: Some soreness or irritation around the TAD site is normal but usually temporary.
• Loosening: In rare cases, a TAD may become loose and need repositioning or replacement.
• Infection: Proper oral hygiene minimizes this risk, but it’s important to follow your orthodontist’s care instructions.

Your orthodontist will discuss these risks and ensure TADs are a good fit for your treatment.

Frequently Asked Questions

Will TADs hurt?
The placement is done under local anesthesia, so you won’t feel pain during the procedure. Any post-placement discomfort is typically mild and short-lived.

Will TADs change my appearance?
TADs are small and placed in discreet areas of the mouth, so they’re usually not noticeable when you smile or talk.

How do I care for TADs?
Brush gently around the TAD to keep the area clean, and avoid chewing hard or sticky foods near the device. Your orthodontist will provide specific instructions.

Can anyone get TADs?
TADs are suitable for many patients, but your orthodontist will evaluate factors like bone density and oral health to determine if they’re right for you.

Conclusion

Temporary Anchorage Devices are a game-changer in orthodontics, offering a precise, efficient, and minimally invasive way to achieve a beautiful, healthy smile. If your orthodontist suggests TADs, rest assured they’re a safe and effective tool to enhance your treatment. Feel free to ask your orthodontist any questions to better understand how TADs will work in your unique case. With TADs, you’re one step closer to the smile you’ve always wanted!

Nepal's National Oral Health Policy 2070

 CLICK ON THIS LINK TO DOWNLOAD THE PDF FILE OF NEPAL'S NATIONAL ORAL HEALTH POLICY 2070 DOCUMENT

 DOWNLOAD THE PDF FILE 

Which anti tubercular drug crosses the blood brain barrier (BBB)?

 # Which anti tubercular drug crosses the blood brain barrier (BBB)?

A. INH

B. Rifampicin

C. Ethambutol

D. Streptomycin

The correct answer is A. INH (Isoniazid).

Explanation:

INH (Isoniazid): 

- Crosses the blood-brain barrier (BBB) effectively, even in the absence of inflammation. 

- First-line drug for tuberculous meningitis due to excellent CSF penetration.

- Critical for treating CNS tuberculosis.

Other Options:

B. Rifampicin: Penetrates the BBB only when meninges are inflamed (e.g., in active meningitis). Not as reliable as INH under normal conditions.

C. Ethambutol and D. Streptomycin: Poor BBB penetration, making them unsuitable for CNS tuberculosis.

Key Takeaway:

INH is the most reliable anti-tubercular drug for crossing the BBB, especially in latent or early CNS infections. Rifampicin’s efficacy depends on meningeal inflammation.

Which of the following can be diagnosed using dark field microscopy?

 # Which of the following can be diagnosed using dark field microscopy?

A. Spirochaetes

B. Streptococci

C. Corynebacteria

D. Mycobacteria

The correct answer is A. Spirochaetes.

Explanation:

Dark field microscopy is particularly useful for observing organisms that are difficult to stain, such as Spirochaetes (e.g., Treponema pallidum, the causative agent of syphilis). These bacteria are thin and motile, making dark field microscopy ideal for visualizing their morphology and movement.

Streptococci (B), Corynebacteria (C), and Mycobacteria (D) are typically diagnosed using Gram staining, Albert staining, or acid-fast staining, respectively. They do not require dark field microscopy.

Lateral Cephalogram Samples for Analysis

 These are some samples of Lateral cephalograms you can use to study and do analyses. 

Sagittal and Lambdoid Synostosis, Low set ears

 # A two-month-old boy is referred for evaluation because he has an abnormal head shape. Physical examination shows low-set ears, and short-webbed fingers. A CT scan shows sagittal and lambdoid synostosis. Which of the following genes is most likely to cause this syndrome ?

A. TWIST1

B. FGFR1

C. FGFR2

D. RAB23

The correct answer C. FGFR2.

The most likely gene to cause the syndrome described, characterized by sagittal and lambdoid synostosis, low-set ears, and short-webbed fingers in a two-month-old boy, is C. FGFR2.

Explanation:

The clinical presentation suggests a craniosynostosis syndrome, with sagittal and lambdoid synostosis indicating premature fusion of cranial sutures, and additional features like low-set ears and short-webbed fingers (syndactyly) pointing toward a syndromic form. Among the options, mutations in FGFR2 (Fibroblast Growth Factor Receptor 2) are strongly associated with syndromic craniosynostoses, particularly Apert syndrome and Crouzon syndrome, both of which can present with multisuture synostosis (including sagittal and lambdoid) and distinctive features.

Apert syndrome (caused by FGFR2 mutations) is characterized by coronal synostosis (though sagittal and lambdoid can also be involved), syndactyly (webbed fingers/toes), midface hypoplasia, and occasionally low-set ears due to associated craniofacial anomalies. The short-webbed fingers in the question align well with Apert’s syndactyly.

Crouzon syndrome (also FGFR2-related) involves craniosynostosis (often coronal, but sagittal and lambdoid can occur) and facial anomalies like low-set ears, though syndactyly is less common.

Analysis of other options:

A. TWIST1: Associated with Saethre-Chotzen syndrome, which typically involves coronal synostosis and milder limb anomalies (e.g., partial syndactyly or brachydactyly). Multisuture involvement (sagittal and lambdoid) is less common, and severe syndactyly is not typical.

B. FGFR1: Linked to Pfeiffer syndrome in some cases, but FGFR2 is more commonly implicated. Pfeiffer includes broad thumbs/toes and partial syndactyly, but sagittal and lambdoid synostosis as the primary sutures is less frequent.

D. RAB23: Associated with Carpenter syndrome, a rare condition with craniosynostosis (often sagittal or coronal), polysyndactyly (extra digits), and other anomalies. The absence of polysyndactyly or obesity in the description makes this less likely, and short-webbed fingers align better with Apert’s syndactyly.

Conclusion: FGFR2 mutations are most likely to cause a syndrome with sagittal and lambdoid synostosis, low-set ears, and short-webbed fingers, as seen in Apert syndrome, making C. FGFR2 the best answer.

Which of the following antibiotics acts by inhibiting cell wall synthesis?

 # Which of the following antibiotics acts by inhibiting cell wall synthesis?

a) Doxycycline

b) Aminoglycosides

c) Erythromycin

d) Cefepime

The correct answer is D. Cefepime.

The correct answer is d) Cefepime.

Explanation:

Cefepime is a fourth-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking, and leading to cell lysis.

Doxycycline (a tetracycline) inhibits protein synthesis by binding to the 30s ribosomal subunit, preventing tRNA attachment.

Aminoglycosides (e.g., gentamicin) also target protein synthesis by binding to the 30s ribosomal subunit, causing misreading of mRNA.

Erythromycin (a macrolide) inhibits protein synthesis by binding to the 50s ribosomal subunit, blocking peptide chain elongation.

Thus, only Cefepime acts by inhibiting cell wall synthesis.

Traumatic injury to primary tooth leads to intrusion. After how much time, the tooth usually re-erupts?

 # Traumatic injury to primary tooth leads to intrusion. After how much time, the tooth usually re-erupts?

a) 30 days

b) 3 months

c) 6 months

d) 12 months

The correct answer is C. 6 months.

Explanation:

Intrusion of a primary tooth occurs when a traumatic force displaces the tooth apically into the alveolar bone. The potential for re-eruption depends on factors such as the degree of intrusion, the integrity of the periodontal ligament, the child's age, and the absence of complications like ankylosis or damage to the underlying permanent tooth bud. In pediatric dentistry, re-eruption is a common outcome for intruded primary teeth due to the elasticity of the periodontal ligament and ongoing alveolar growth.

While some studies suggest re-eruption can occur within 2–4 months for mild to moderate intrusions, the 6-month timeframe is more plausible in clinical practice for several reasons:

Variable Healing Dynamics: Moderate to severe intrusions may require longer for the periodontal ligament to reorganize and facilitate re-eruption, especially if there is initial swelling or minor alveolar bone remodeling.

Clinical Monitoring Period: Dentists often observe intruded teeth for up to 6 months to confirm complete re-eruption or to detect complications (e.g., failure to re-erupt, ankylosis, or pulpal necrosis). The 6-month mark is a standard endpoint in guidelines (e.g., American Academy of Pediatric Dentistry) for assessing outcomes.

Conservative Estimate: The 6-month duration accounts for cases where re-eruption is slower due to partial intrusion or minor displacement, ensuring the tooth returns to its original position without intervention.

In contrast, 30 days is too short for complete re-eruption, as initial healing and tissue reorganization take longer. 3 months may suffice for milder cases but may not cover the full spectrum of intrusion severities. 12 months is excessively long unless complications delay the process significantly. Thus, 6 months is a clinically relevant and plausible timeframe for the re-eruption of most intruded primary teeth, balancing biological healing with practical observation periods.

Bulk of lamina propria of the gingiva is made of collagen type:

 # Bulk of lamina propria of the gingiva is made of collagen type:

a) I

b) II

c) III

d) IV

The correct answer is A. Type I.

The bulk of the lamina propria of the gingiva is made of collagen type I.

Explanation:

The lamina propria of the gingiva, a connective tissue layer supporting the gingival epithelium, primarily consists of collagen type I, which provides structural strength and resilience. Collagen type I is the most abundant collagen in connective tissues like the gingiva, while other types (e.g., II in cartilage, III in reticular fibers, IV in basement membranes) are less dominant in this context.

Secretin does not cause:

 # Secretin does not cause:

a) Bicarbonate secretion

b) Augments the action of CCK

c) Contraction of pyloric sphincter

d) Gastric secretion increase

The correct answer is D. Gastric secretion increase.

Secretin does not cause d) Gastric secretion increase.

Explanation:

a) Bicarbonate secretion: Secretin stimulates the pancreas to secrete bicarbonate to neutralize acidic chyme in the duodenum.

b) Augments the action of CCK: Secretin works synergistically with cholecystokinin (CCK) to enhance pancreatic enzyme and bile secretion.

c) Contraction of pyloric sphincter: Secretin promotes relaxation of the pyloric sphincter to allow chyme to pass into the duodenum.

d) Gastric secretion increase: Secretin inhibits gastric acid secretion and gastric motility to slow digestion in the stomach, making this the correct answer.

Major and frequent influence for arterial thrombus formation is:

 # Major and frequent influence for arterial thrombus formation is:

a) Alteration in blood flow

b) Hypercoagulability

c) Endothelial damage

d) Fatty streak

The correct answer is C. Endothelial damage.

For a single-choice question on thrombus formation, the answer depends on the clinical context:

1. Arterial Thrombosis (e.g., Myocardial Infarction)

Correct Answer: [c) Endothelial Damage]

Rationale: Arterial thrombi typically form at sites of disrupted atherosclerotic plaques. Endothelial injury directly exposes prothrombotic subendothelial collagen and tissue factor, triggering platelet adhesion/aggregation and coagulation activation.

2. Venous Thrombosis (e.g., DVT)

Correct Answer: [a) Alteration in Blood Flow] or [b) Hypercoagulability]

Rationale: Venous thrombi often arise from stasis (e.g., immobility) or hypercoagulable states (e.g., Factor V Leiden). If forced to choose one, prioritize [a) Alteration in Blood Flow] as stasis is the most common trigger.

Why Not Other Options?

[d) Fatty Streak] is incorrect because it represents early atherosclerosis, not active thrombosis.

Note: In practice, all three Virchow triad components (a/b/c) contribute, but exam questions often focus on the most context-specific factor.

Exam Strategy:

If the question mentions "myocardial infarction" or "artery", choose c.

If it refers to "DVT", "surgery", or "immobility", choose a.

If genetic clotting disorders (e.g., Leiden mutation) are explicitly mentioned, choose b.

Vestibular toxicity is associated with which of the following tetracyclines?

Vestibular toxicity is associated with which of the following tetracyclines?

A. Doxycycline
B. Minocycline
C. Chlorotetracycline
D. Oxytetracycline