NEET MDS Synopsis
Quinolone
Pharmacology
Quinolone
Quinolones and fluoroquinolones form a group of broad-spectrum antibiotics. They are derived from nalidixic acid.
Fluoroquinolone antibiotics are highly potent and considered relatively safe.
MOA : Quinolones act by inhibiting the bacterial DNA gyrase enzyme. This way they inhibit nucleic acid synthesis and act bacteriocidically.
Drugs :Nalidixic acid, Ciprofloxacin , Levofloxacin, Norfloxacin ,Ofloxacin, Moxifloxacin , Trovafloxacin
Cell Functions
General Microbiology
Cell Functions:
-> Autolysis
- degradative reactions in cells caused by indigenous intracellular enzymes – usually occurs after cell death
- Irreversible (along with Coagulative necrosis or infarcts) – reversible: fatty degeneration, & hydropic degeneration
-> Autolysin:
• Ab causing cellular lysis in the presence of complement
• Autolytic enzymes produced by the organism degrade the cell’s own cell wall structures
-> In the presence of cephalosporins & penicillins, growing bacterial cells lyse
• W/o functional cell wall structures, the bacterial cell bursts
-> Heterolysis: cellular degradation by enzymes derived from sources extrinsic to the cell (e.g., bacteria)
-> Necrosis: sum of intracellular degradative reactions occurring after individual cell death w/in a living organism
FORMATION OF THE ROOT AND ITS ROLE IN ERUPTION
Dental Anatomy
FORMATION OF THE ROOT AND ITS ROLE IN ERUPTION
- As dentin and enamel is deposited the shape of the future crown appears.
- The cells just superficial to the horizontal diaphragm start to proliferate and grow pushing the horizontal diaphragm down into the mesenchym.
- This forms a tube.
- This tube is the epithelial root sheath of Hertwig's.
- The mesenchym cells lying inside the tube nearest to the epithelial root sheath are induced to differentiate into odontoblasts, which then start to deposit dentin.
- After the first dentin of the root has been laid down the inner epithelial cells of the sheath start to deposit an enameloid substance called intermediate cementum.
- The root sheath cells then separate from the intermediate cementum and breaks up in a network of epithelial strands.
- The mesenchym on the outside comes into contact with the intermediate cementum and differentiate into
cementoblasts, which will deposit the cementum.
- This cementum traps the collagenic fibres, of the periodontal ligament, which are also formed.
- Epithelium of the root sheath persists as epithelial rests of Malassez. Because the epithelium of the root sheath forms from enamel epithelium it can develop into ameloblasts which will deposit enamel pearls.
- There is little space for the root to develop.
- To create space the crown is pushed out.
Food Poisoning
Social and Preventive Medicine
Food Poisoning
Common pathogens attributed to food poisoning include Norovirus, Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, and Escherichia coli.
Incubation periods depend on the cause, and range from a few hours to days. The clinical presentation associated with food poisoning varies, but typical symptoms include diarrhea, nausea, vomiting, and abdominal cramping.
Staphylococcal food poisoning
Pathogen: Staphylococcus aureus
Gram-positive bacterium
Some strains produce heat-stable enterotoxins that cause staphylococcal food poisoning.
Transmission: ingestion of preformed toxins in contaminated food
Characteristics
Typically involves a short latency period; resolution of symptoms after 24–48 hours
Bacteria proliferate in inadequately refrigerated food (canned meats, mayonnaise/potato salad, custards).
Incubation period: 1–4 hours
Clinical findings: nausea, vomiting, abdominal discomfort, diarrhea
Bacillus cereus infection
Pathogen: Bacillus cereus, a heat-stable, spore-forming bacterium that produces two different enterotoxins
Transmission: The bacterium grows in heated food that cools down too slowly or is improperly refrigerated. Reheated rice is a common source of infection.
Incubation period and clinical findings
Enterotoxin I (emetic form): 30 min to 6 h after ingestion → nausea and vomiting
Enterotoxin II (diarrheal form): 6–15 h after ingestion → watery diarrhea for 24–48 h
Food poisoning from reheated rice - (B. cereus).
Pterygomandibular Space
Oral and Maxillofacial SurgeryPterygomandibular Space is an important anatomical area in the head and neck
region, particularly relevant in dental and maxillofacial surgery. Understanding
its boundaries, contents, and clinical significance is crucial for procedures
such as local anesthesia, surgical interventions, and the management of
infections. Here’s a detailed overview of the pterygomandibular space:
Boundaries of the Pterygomandibular Space
Laterally:
Medial Surface of the Ramus of the Mandible: This
boundary is formed by the inner aspect of the ramus, which provides a
lateral limit to the space.
Medially:
Lateral Surface of the Medial Pterygoid Muscle: The
medial boundary is defined by the lateral aspect of the medial pterygoid
muscle, which is a key muscle involved in mastication.
Posteriorly:
Deep Portion of the Parotid Gland: The posterior
limit of the pterygomandibular space is formed by the deep part of the
parotid gland, which is significant in terms of potential spread of
infections.
Anteriorly:
Pterygomandibular Raphe: This fibrous band connects
the pterygoid muscles and serves as the anterior boundary of the space.
Roof:
Lateral Pterygoid Muscle: The roof of the
pterygomandibular space is formed by the lateral pterygoid muscle. The
space just below this muscle communicates with the pharyngeal spaces,
which is clinically relevant for the spread of infections.
Contents of the Pterygomandibular Space
The pterygomandibular space contains several important structures:
Nerves:
Lingual Nerve: This nerve provides sensory
innervation to the anterior two-thirds of the tongue and is closely
associated with the inferior alveolar nerve.
Mandibular Nerve (V3): The third division of the
trigeminal nerve, which supplies sensory and motor innervation to the
lower jaw and associated structures.
Vessels:
Inferior Alveolar Artery: A branch of the maxillary
artery that supplies blood to the lower teeth and surrounding tissues.
Mylohyoid Nerve and Vessels: The mylohyoid nerve, a
branch of the inferior alveolar nerve, innervates the mylohyoid muscle
and the anterior belly of the digastric muscle.
Connective Tissue:
Loose Areolar Connective Tissue: This tissue
provides a supportive framework for the structures within the
pterygomandibular space and allows for some degree of movement and
flexibility.
Clinical Significance
Local Anesthesia: The pterygomandibular space is a
common site for administering local anesthesia, particularly for inferior
alveolar nerve blocks, which are essential for dental procedures involving
the lower jaw.
Infection Spread: Due to its anatomical connections,
infections in the pterygomandibular space can spread to adjacent areas,
including the parotid gland and the pharyngeal spaces, necessitating careful
evaluation and management.
Surgical Considerations: Knowledge of the boundaries
and contents of this space is crucial during surgical procedures in the
mandible and surrounding areas to avoid damaging important nerves and
vessels.
Nerves of the Tongue
Anatomy
Anterior 2/3 of tongue
Posterior 1/3 of tongue
Motor Innervation
All muscles by hypoglossal nerve (CN XII) except palatoglossus muscle (by the pharyngeal plexus)
General Sensory Innervation
Lingual nerve (branch of mandibular nerve CN V3)
Glossopharyngeal nerve (CN IX)
Special Sensory Innervation
Chorda tympani nerve (branch of facial nerve)
Glossopharyngeal nerve (CN IX)
Organic Nitrates
Pharmacology
Organic Nitrates
Relax smooth muscle in blood vessel
Produces vasodilatation
– Decreases venous pressure and venous return to the heart Which decreases the cardiac work load and oxygen demand.
– May have little effect on the coronary arteries CAD causes stiffening and lack of
– responsiveness in the coronary arteries
– Dilate arterioles, lowering peripheral vascular resistance Reducing the cardiac workload
Main effect related to drop in blood pressure by
– Vasodilation- pools blood in veins and capillaries, decreasing the volume of blood that the heart has to pump around (the preload)
– relaxation of the vessels which decreases the resistance the heart has to pump against (the afterload)
Indications
- Myocardial ischemia
– Prevention
– Treatment
Nitroglycerin (Nitro-Bid)
• Used
– To relive acute angina pectoris
– Prevent exercise induced angina
– Decrease frequency and severity of acute anginal episodes
Type
• Oral - rapidly metabolized in the liver only small amount reaches circulation
• Sublingual – Transmucosal tablets and sprays
• Transdermal – Ointment s
– Adhesive discs applied to the skin
• IV preparations
Sublingual Nitroglycerine
• Absorbed directly into the systemic circulation, Acts within 1-3 minutes , Lasts 30-60 min
Topical Nitroglycerine
• Absorbed directly into systemic circulation, Absorption at a slower rate. , Longer duration of action
Ointment - effective for 4-8 hours
Transdermal disc - effective for 18-24 hours
Isosorbide dinitrate
• Reduces frequency and severity of acute anginal episodes
• Sublingual or chewable acts in 2 min. effects last 2-3 hours
• Orally, systemic effects in about 30 minutes and last about 4 hours after oral administration
Tolerance to Long-Acting Nitrates
• Long-acting dosage forms of nitrates may develop tolerance
– Result in episodes of chest pain
– Short acting nitrates less effective
Prevention of Tolerance
• Use long-acting forms for approximately 12-16 hours daily during active periods and omit them during inactive periods or sleep
• Oral or topical should be given every 6 hours X 3 doses allowing a rest period of 6 hours
Isosorbide dinitrate (Isordil, Sorbitrate) is used to reduce the frequency and severity of acute anginal episodes.
When given sublingually or in chewable tablets, it acts in about 2 minutes, and its effects last 2 to 3 hours. When higher doses are given orally, more drug escapes metabolism in the liver and produces systemic effects in approximately 30 minutes. Therapeutic effects last about 4 hours after oral administration
Isosorbide mononitrate (Ismo, Imdur) is the metabolite and active component of isosorbide dinitrate. It is well absorbed after oral administration and almost 100% bioavailable. Unlike other oral nitrates, this drug is not subject to first-pass hepatic metabolism. Onset of action occurs within 1 hour, peak effects occur between 1 and 4 hours, and the elimination half-life is approximately 5 hours. It is used only for prophylaxis of angina; it does not act rapidly enough to relieve acute attacks.
Drugs used in cough.
Pharmacology
PHARYNGEAL DEMULCENTS
Administered in the form of lozenges, cough drops and cough linctus.
Produce soothing action on throat directly and by increasing the flow of saliva and provide symptomatic relief from dry cough.
EXPECTORANT
Expectorants are the drugs which increase the production of bronchial secretion and reduce its viscosity to facilitate its removal by coughing.
ANTITUSSIVES
They are central cough suppressants and act centrally to raise the threshold of cough centre and inhibit the cough reflex by suppressing the coordinating cough centre in the medulla oblongata.
Codeine - it depresses cough centre but is less constipating and abuse liability is low.
Pholcodeine is similar to codeine in efficacy and is longer acting. It has no analgesic or addicting property.
Noscapine is another opium alkaloid of benzylisoquinoline group. It is used as antitussive with no analgesic and drug abuse or drug dependence property.
Dextromethorphan is a synthetic compound and its dextroisomer is used as antitussive and is as effective as codeine
Pipazethate is another synthetic compound of phenothiazine category used as antitussive with little analgesic and sedative properties.
ANTIHISTAMINICS
They do not act on cough centre but provide relief due to their sedative and anticholinergic action.
BRONCHODILATORS
Bronchodilators are helpful in individuals with cough and bronchoconstriction due to bronchial hyperreactivity. They help by improving the effectiveness of cough in clearing secretions.