NEET MDS Synopsis
Precipitation Reaction
General Microbiology
Precipitation Reaction
This reaction takes place only when antigen is in soluble form. Such an antigen when
comes in contact with specific antibody in a suitable medium results into formation of an insoluble complex which precipitates. This precipitate usually settles down at the bottom of the tube. If it fails to sediment and remains suspended as floccules the reaction is known as flocculation. Precipitation also requires optimal concentration of NaCl, suitable temperature and appropriate pH.
Zone Phenomenon
Precipitation occurs most rapidly and abundantly when antigen and antibody are in optimal proportions or equivalent ratio. This is also known as zone of equivalence. When antibody is in great excess, lot of antibody remains uncombined. This is called zone of antibody excess or prozone. Similarly a zone of antigen excess occurs in which all antibody has combined with antigen and additional uncombined antigen is present.
Applications of Precipitation Reactions
Both qualitative determination as well as quantitative estimation of antigen and antibody can be performed with precipitation tests. Detection of antigens has been found to be more sensitive.
Agglutination
In agglutination reaction the antigen is a part of the surface of some particulate material such as erythrocyte, bacterium or an inorganic particle e.g. polystyrene latex which has been coated with antigen. Antibody added to a suspension of such particles combines with the surface antigen and links them together to form clearly visible aggregate which is called as agglutination.
Application of precipitation reactions
Precipitation reaction Example
Ring test Typing of streptococci, Typing of pneumococci
Slide test (flocculation) VDRL test
Tube test (flocculation) Kahn test
Immunodiffusion Eleks test
Immunoelectrophoresis Detection Of HBsAg, Cryptococcal antigen in CSF
Intravenous Anesthetic Agents
AnaesthesiaIntravenous Anesthetic Agents
Intravenous anesthetic agents are crucial in modern anesthesia practice,
providing rapid onset of sedation and analgesia. This lecture will cover the
most commonly used intravenous anesthetic agents, including their indications,
contraindications, and required doses.
1. Benzodiazepines
Overview
Benzodiazepines are primarily used for their anxiolytic (anxiety-reducing)
and amnesic properties. They are frequently used in procedural sedation and as
adjuncts in general anesthesia.
Common Agents
Diazepam
Dose: 5-10 mg IV (may repeat every 5-15 minutes as
needed)
Indications: Anxiety, sedation, muscle relaxation,
seizure control.
Contraindications: Hypersensitivity, severe
respiratory depression, acute narrow-angle glaucoma.
Lorazepam
Dose: 1-4 mg IV (may repeat every 6-8 hours as
needed)
Indications: Anxiety, sedation, preoperative
medication.
Contraindications: Hypersensitivity, severe
respiratory depression, acute narrow-angle glaucoma.
Midazolam
Dose: 1-5 mg IV (may repeat every 2-5 minutes as
needed)
Indications: Procedural sedation, induction of
anesthesia, anxiety reduction.
Contraindications: Hypersensitivity, severe
respiratory depression, acute narrow-angle glaucoma.
2. Etomidate
Overview
Etomidate is an imidazole derivative used for rapid intravenous induction of
anesthesia. It is known for its minimal cardiovascular effects.
Dose
Dose: 0.2-0.3 mg/kg IV (administered over 30-60
seconds)
Indications
Induction of anesthesia, particularly in patients with cardiovascular
instability.
Contraindications
Hypersensitivity to etomidate, adrenal insufficiency (due to suppression
of adrenal function).
3. Ketamine
Overview
Ketamine is a unique intravenous anesthetic that provides dissociative
anesthesia and analgesia. It is known for its ability to increase cerebral blood
flow.
Dose
Dose: 1-2 mg/kg IV (for induction)
Indications
Induction of anesthesia, analgesia for painful procedures, and in
patients with asthma or reactive airway disease.
Contraindications
Hypersensitivity, severe hypertension, or increased intracranial
pressure.
Additional Notes
Ketamine may offer neuroprotective effects and is often used in
pediatric patients due to its safety profile.
4. Barbiturates
Overview
Barbiturates are central nervous system depressants that have been used for
induction of anesthesia. They act primarily at the GABA receptor.
Common Agents
Thiopental
Dose: 3-5 mg/kg IV (for induction)
Methohexital
Dose: 1-2 mg/kg IV (for induction)
Thiamylal
Dose: 3-5 mg/kg IV (for induction)
Indications
Induction of anesthesia, sedation, and as anticonvulsants.
Contraindications
Hypersensitivity, porphyria, severe respiratory depression.
5. Propofol
Overview
Propofol is an alkylated phenol that provides rapid sedation and is widely
used for induction and maintenance of anesthesia.
Dose
Dose: 1-2.5 mg/kg IV (for induction)
Indications
Induction and maintenance of anesthesia, sedation for procedures.
Contraindications
Hypersensitivity to propofol or its components, egg or soy allergy.
Additional Notes
Propofol is favored for outpatient procedures due to its rapid recovery
profile and low incidence of nausea and vomiting.
6. Opioid Analgesics
Overview
Opioids are potent analgesics that act centrally on μ-receptors in the brain
and spinal cord. They are often used in conjunction with other anesthetic
agents.
Common Agents
Meperidine
Dose: 25-100 mg IV (for analgesia)
Fentanyl-based compounds
Dose: 25-100 mcg IV (for analgesia)
Morphine
Dose: 2-10 mg IV (for analgesia)
Codeine
Dose: 15-60 mg IV (for analgesia)
Oxymorphone
Dose: 1-5 mg IV (for analgesia)
Indications
Pain management, adjunct to anesthesia.
Contraindications
Hypersensitivity, respiratory depression, severe asthma, or head injury.
Additional Notes
Opioids have differing potencies, and equianalgesic doses can result in
similar degrees of respiratory depression. Therefore, there is no completely
safe opioid analgesic.
Anchorage in Orthodontics
Orthodontics
Anchorage in orthodontics refers to the resistance that the anchorage area
offers to unwanted tooth movements during orthodontic treatment. Proper
understanding and application of anchorage principles are crucial for achieving
desired tooth movements while minimizing undesirable effects on adjacent teeth.
Classification of Anchorage
1. According to Manner of Force Application
Simple Anchorage:
Achieved by engaging a greater number of teeth than those being
moved within the same dental arch.
The combined root surface area of the anchorage unit must be at
least double that of the teeth to be moved.
Stationary Anchorage:
Defined as dental anchorage where the application of force tends to
displace the anchorage unit bodily in the direction of the force.
Provides greater resistance compared to anchorage that only resists
tipping forces.
Reciprocal Anchorage:
Refers to the resistance offered by two malposed units when equal
and opposite forces are applied, moving each unit towards a more normal
occlusion.
Examples:
Closure of a midline diastema by moving the two central incisors
towards each other.
Use of crossbite elastics and dental arch expansions.
2. According to Jaws Involved
Intra-maxillary Anchorage:
All units offering resistance are situated within the same jaw.
Intermaxillary Anchorage:
Resistance units in one jaw are used to effect tooth movement in the
opposing jaw.
Also known as Baker's anchorage.
Examples:
Class II elastic traction.
Class III elastic traction.
3. According to Site
Intraoral Anchorage:
Both the teeth to be moved and the anchorage areas are located
within the oral cavity.
Anatomic units include teeth, palate, and lingual alveolar bone of
the mandible.
Extraoral Anchorage:
Resistance units are situated outside the oral cavity.
Anatomic units include the occiput, back of the neck, cranium, and
face.
Examples:
Headgear.
Facemask.
Muscular Anchorage:
Utilizes forces generated by muscles to aid in tooth movement.
Example: Lip bumper to distalize molars.
4. According to Number of Anchorage Units
Single or Primary Anchorage:
A single tooth with greater alveolar support is used to move another
tooth with lesser support.
Compound Anchorage:
Involves more than one tooth providing resistance to move teeth with
lesser support.
Multiple or Reinforced Anchorage:
Utilizes more than one type of resistance unit.
Examples:
Extraoral forces to augment anchorage.
Upper anterior inclined plane.
Transpalatal arch.
Joint pathology
General Pathology
Joint pathology
1. Rheumatoid arthritis
a. Cause is autoimmune in nature.
b. More common in women aged 20 to 50.
c. Characterized by inflammation of the synovial membrane. Granulation tissue, known as pannus, will form in the synovium and expand over the articular cartilage. This causes the destruction of the underlying cartilage and results in fibrotic changes and ankylosis.
Scarring, contracture, and deformity of the joints may occur.
d. Clinical symptoms include swollen joints. It can affect any joint in the body.
2. Osteoarthritis
a. Most common arthritis.
b. Cause is unknown.
c. Higher incidence in women, usually after age 50.
d. Characterized by degeneration of the articular cartilage and the formation of osteophytes (bony spurs) at the margins of affected areas.
Clinical signs and symptoms include:
(1) Stiff and painful joints affecting joints in the hand (phalangeal joints) and weight-bearing joints.
(2) Heberden’s nodes—nodules at the distal interphalangeal joint.
(3) Bocard’s nodes—nodules at the proximal interphalangeal joint.
Oral Surgery NEET MDS Discussion part 1
NEET MDS
Enamel
Dental Anatomy
Enamel
Structural characteristics and microscopic features
a. Enamel rods or prisms
(1) Basic structural unit of enamel.
(2) Consists of tightly packed hydroxyapatite crystals. Hydroxyapatite crystals in enamel are four times larger and more tightly packed than hydroxyapatite found in other calcified
tissues (i.e., it is harder than bone).
(3) Each rod extends the entire thickness of enamel and is perpendicular to the dentinoenamel junction (DEJ).
b. Aprismatic enamel
(1) The thin outer layer of enamel found on the surface of newly erupted teeth.
(2) Consists of enamel crystals that are aligned perpendicular to the surface.
(3) It is aprismatic (i.e., prismless) and is more mineralized than the enamel beneath it.
(4) It results from the absence of Tomes processes on the ameloblasts during the final stages of enamel deposition.
c. Lines of Retzius (enamel striae)
(1) Microscopic features
(a) In longitudinal sections, they are observed as brown lines that extend from the DEJ to the
tooth surface.
(b) In transverse sections, they appear as dark, concentric rings similar to growth rings in a tree.
(2) The lines appear weekly during the formation of enamel.
(3) Although the cause of striae formation is unknown, the lines may represent appositional or incremental growth of enamel. They may also result from metabolic disturbances of ameloblasts.
(4) Neonatal line
(a) An accentuated, dark line of Retzius that results from the effect of physiological changes
on ameloblasts at birth.
(b) Found in all primary teeth and some cusps of permanent first molars.
d. Perikymata
(1) Lines of Retzius terminate on the tooth surface in shallow grooves known a perikymata.
(2) These grooves are usually lost through wear but may be observed on the surfaces of developing teeth or nonmasticatory surfaces of formed teeth.
e. Hunter-Schreger bands
(1) Enamel rods run in different directions. In longitudinal sections, these changes in direction result in a banding pattern known as HunterSchreger bands.
(2) These bands represent an optical phenomenon of enamel and consist of a series of alternating dark and light lines when the section is viewed with reflected or polarized
light.
f. Enamel tufts
(1) Consist of hypomineralized groups of enamel rods.
(2) They are observed as short, dark projections found near or at the DEJ.
(3) They have no known clinical significance.
g. Enamel lamellae
(1) Small, sheet-like cracks found on the surface of enamel that extend its entire thickness.
(2) Consist of hypocalcified enamel.
(3) The open crack may be filled with organic material from leftover enamel organ components, connective tissues of the developing tooth, or debris from the oral cavity.
(4) Both enamel tufts and lamellae may be likened to geological faults in mature enamel.
h. Enamel spindle
(1) Remnants of odontoblastic processes that become trapped after crossing the DEJ during the differentiation of ameloblasts.
(2) Spindles are more pronounced beneath the cusps or incisal edges of teeth (i.e., areas where occlusal stresses are the greatest).
Obstetric forceps delivery
Obstetrics and Gynaecology
a forcep is a metal device that enables gentle rotation and/or traction of the fetal head during vaginal delivery
Types
Kielland: enables rotation and traction of the fetal head
Simpson: only enables traction of the fetal head
Barton: used for occiput transverse position of the fetal head
Piper: used to deliver the fetal head during breech delivery
Classification
Outlet: fetal head lies on the pelvic floor
Low: fetal head is below +2 station (not on the pelvic floor)
Mid: fetal head is below 0 station (not at +2 station)
High: fetal head is not engaged
Indications
Prolonged second stage of labor
Breech presentation
Nonreassuring fetal heart rate
To avoid/assist maternal pushing efforts
Prerequisites
Clinically adequate pelvic dimensions (see “Mechanics of childbirth”)
Full cervical dilation
Engagement of the fetal head
Knowledge of exact position and attitude of the fetal head
Emptied maternal bladder
No suspicion of fetal bleeding or bone mineralization disorders
Advantages
Scalp injuries are less common
Cannot undergo decompression and “pop off”
Complications
Maternal: obstetric lacerations (cervix, vagina, uterus)
Fetal: head or soft-tissue trauma (e.g., scalp lacerations, injured ears), facial nerve palsy
The pancreas
PhysiologyThe pancreas
The pancreas consists of clusters if endocrine cells (the islets of Langerhans) and exocrine cells whose secretions drain into the duodenum.
Pancreatic fluid contains:
sodium bicarbonate (NaHCO3). This neutralizes the acidity of the fluid arriving from the stomach raising its pH to about 8.
pancreatic amylase. This enzyme hydrolyzes starch into a mixture of maltose and glucose.
pancreatic lipase. The enzyme hydrolyzes ingested fats into a mixture of fatty acids and monoglycerides. Its action is enhanced by the detergent effect of bile.
4 zymogens— proteins that are precursors to active proteases. These are immediately converted into the active proteolytic enzymes:
trypsin. Trypsin cleaves peptide bonds on the C-terminal side of arginines and lysines.
chymotrypsin. Chymotrypsin cuts on the C-terminal side of tyrosine, phenylalanine, and tryptophan residues (the same bonds as pepsin, whose action ceases when the NaHCO3 raises the pH of the intestinal contents).
elastase. Elastase cuts peptide bonds next to small, uncharged side chains such as those of alanine and serine.
carboxypeptidase. This enzyme removes, one by one, the amino acids at the C-terminal of peptides.
nucleases. These hydrolyze ingested nucleic acids (RNA and DNA) into their component nucleotides.
The secretion of pancreatic fluid is controlled by two hormones:
secretin, which mainly affects the release of sodium bicarbonate, and
cholecystokinin (CCK), which stimulates the release of the digestive enzymes.