NEET MDS Synopsis
Selective serotonin reuptake inhibitors
Pharmacology
Selective serotonin reuptake inhibitors (SSRIs)
e.g. fluoxetine, paroxetine, citalopram, and sertraline
- Most commonly used antidepressant category
- Less likely to cause anticholinergic side effects
- Relatively safest antidepressant group in overdose
- Selectively inhibits reuptake of serotonin(5-HT)
Mode of Action;
- Well absorbed when given orally
- Plasma half-lives of 18-24 h allowing once daily dosagedaily dosage
- Metabolised through CYP450 system and most SSRIs inhibit some CYP isoforms
- Therapeutic effect is delayed for 2-4 weeks
ADVERSE DRUG REACTIONS
- Insomnia, increased anxiety, irritability
- Decreased libido
- Erectile dysfunction, anorgasmia, and ejaculatory delay
- Bleeding disorders
- Withdrawal syndrome
Immunodeficiency
General Pathology
Immunodeficiency
This may be :-
Congenital (Primary)
Acquired (Secondary)
Features : Complete or near complete lack of T & B lymphoid tissue. Fatal early in life Even with marrow grafting, chances of graft versus host reaction is high.
B. T Cell Defects :
Thymic dysplasia
Digeorge’s syndrome
Nazelof’s syndrome
Ataxia teltngiectaisa
Wiscott Aldrich’s syndrome
These lessons show predominantly defective cell mediated immunity. But they may also show partial immunoglobulin defects cell mediated immunity. But they may also show partial immunoglobulin defects due to absence og T-B co-operation.
C. Humoral immunity defects.
Bruron type- aggammaglobulinaemia.
Dysgammaglobulinaemias-variable immunodeficiency’s of one or more classes.
Acquired deficiency
A. Immuno suppression by :
Irradiation.
Corticoids.
Anti metabolites.
Anti lymphocyte serum.
B. Neaplasia of lymphoid system :
Hodgkin's and Non Hodgkin's lymphomas.
Chronic lymphocytic leukaemia..
Multime myeloma and other paraproteinaemias (normal immunoglobulins reduced in spite of hyperglobulinaemia).
c. excessive protein loss.
Nephrotic Syndrome.
Protein losing enteropathy.
Thalassaemia
General Pathology
Thalassaemia. Genetic based defect in synthesis of one of the normal chains.
Beta thalassaemia ---> reduced Hb A and increased HbF (α2, Y2) HBA2(α2)
Alpha thalassaemia ---> reduced Hb-A, Hb-A2 and Hb-F-with formation of Hb-H(β4) and Hb Barts (Y4).
Thalassaemia may manifest as trait or disease or with intermediate manifestation.
Features:
• Microcytic hypochromic RBC is in iron deficjency.
• Marked anisopoikilocytsis with prominent target cells.
• Reticulocytosis and nucleated RBC seen.
• Mongoloid facies and X-ray findings characteristic of marrow hyperplasia
• Decreased osmotic. fragility.
• Increased marrow iron (important difference from iron deficiency anaemia).
• Haemosiderosis, especially with repeated transfusions.
Diagnosis is by Hb electrophoresis and by Alkali denaturation test (for HbF).
Mercury hygiene
Dental Materials
Mercury hygiene
Do not contact mercury with skin
Clean up spills to minimize mercury vaporization
Store mercury or precapsulated products in tight containers
Only triturate amalgam components-in tightly- sealed capsules
Use amalgam with covers
Store spent amalgam under water or fixer in a tightly sealed jar
Use high vacuum suction during amalgam alloy placement, setting, or removal when mercury may be vaporized
Polishing amalgams generally causes localized melting of silver-mercury phase with release of mercury vapor, so water cooling and evacuation must be used
The stomach
PhysiologyThe Stomach :
The wall of the stomach is lined with millions of gastric glands, which together secrete 400–800 ml of gastric juice at each meal. Three kinds of cells are found in the gastric glands
parietal cells
chief cells
mucus-secreting cells
Parietal cells : secrete
Hydrochloric acid : Parietal cells contain a H+ ATPase. This transmembrane protein secretes H+ ions (protons) by active transport, using the energy of ATP.
Intrinsic factor: Intrinsic factor is a protein that binds ingested vitamin B12 and enables it to be absorbed by the intestine. A deficiency of intrinsic factor as a result of an autoimmune attack against parietal cells causes pernicious anemia.
Chief Cells : The chief cells synthesize and secrete pepsinogen, the precursor to the proteolytic enzyme pepsin.
Secretion by the gastric glands is stimulated by the hormone gastrin. Gastrin is released by endocrine cells in the stomach in response to the arrival of food.
Junctional Epithelium
PeriodontologyJunctional Epithelium
The junctional epithelium (JE) is a critical component of the periodontal
tissue, playing a vital role in the attachment of the gingiva to the tooth
surface. Understanding its structure, function, and development is essential for
comprehending periodontal health and disease.
Structure of the Junctional Epithelium
Composition:
The junctional epithelium consists of a collar-like band of stratified
squamous non-keratinized epithelium.
This type of epithelium is designed to provide a barrier while
allowing for some flexibility and permeability.
Layer Thickness:
In early life, the junctional epithelium is approximately 3-4
layers thick.
As a person ages, the number of epithelial layers can increase
significantly, reaching 10 to 20 layers in older
individuals.
This increase in thickness may be a response to various factors,
including mechanical stress and inflammation.
Length:
The length of the junctional epithelium typically ranges from 0.25
mm to 1.35 mm.
This length can vary based on individual anatomy and periodontal
health.
Development of the Junctional Epithelium
The junctional epithelium is formed by the confluence of the
oral epithelium and the reduced enamel epithelium during the
process of tooth eruption.
This fusion is crucial for establishing the attachment of the gingiva to
the tooth surface, creating a seal that helps protect the underlying
periodontal tissues from microbial invasion.
Function of the Junctional Epithelium
Barrier Function: The junctional epithelium serves as a
barrier between the oral cavity and the underlying periodontal tissues,
helping to prevent the entry of pathogens.
Attachment: It provides a strong attachment to the
tooth surface, which is essential for maintaining periodontal health.
Regenerative Capacity: The junctional epithelium has a
high turnover rate, allowing it to regenerate quickly in response to injury
or inflammation.
Clinical Relevance
Periodontal Disease: Changes in the structure and
function of the junctional epithelium can be indicative of periodontal
disease. For example, inflammation can lead to increased permeability and
loss of attachment.
Healing and Repair: Understanding the properties of the
junctional epithelium is important for developing effective treatments for
periodontal disease and for managing healing after periodontal surgery.
INFARCTION
General Pathology
INFARCTION
An infarct is an area of ischemic necrosis caused by occlusion of either the arterial supply or the venous drainage in a particular tissue
Nearly 99% of all infarcts result from thrombotic or embolic events
other mechanisms include: local vasospasm, expansion of an atheroma, extrinsic compression of a vessel (e.g., by tumor); vessel twisting (e.g., in testicular torsion or bowel volvulus; and traumatic vessel rupture
MORPHOLOGY OF INFARCTS
infarcts may be either red (hemorrhagic) or white (anemic) and may be either septic or aseptic
All infarcts tend to be wedge-shaped, with the occluded vessel at the apex and the periphery of the organ forming the base
The margins of both types of infarcts tend to become better defined with time
The dominant histological characteristic of infarction is ischemic coagulative necrosis
most infarcts are ultimately replaced by scar. The brain is an exception, it results in liquefactive necrosis
RED INFARCTS:
occur in
(1) venous occlusions (such as in ovarian torsion)
(2) loose tissues (like lung) that allow blood to collect in the infarcted zone
(3) tissues with dual circulations (lung and small intestine)
(4) previously congested tissues because of sluggish venous outflow
(5) when flow is re-established to a site of previous arterial occlusion and necrosis
WHITE INFARCTS
occur with:
1) arterial occlusions
2) solid organs (such as heart, spleen, and kidney).
Septic infarctions - occur when bacterial vegetations from a heart valve embolize or when microbes seed an area of necrotic tissue. - the infarct is converted into an abscess, with a correspondingly greater inflammatory response
FACTORS THAT INFLUENCE DEVELOPMENT OF AN INFARCT
- nature of the vascular supply
- rate of development of the occlusion (collateral circulation )
- vulnerability to hypoxia - Neurons undergo irreversible damage
- 3 to 4 minutes of ischemia. - Myocardial cells die after only 20 to 30 minutes of ischemia
- the oxygen content of blood
Gallium Alloys as Amalgam Substitutes
Conservative DentistryGallium Alloys as Amalgam Substitutes
Gallium Alloys: Gallium alloys, such as those made with
silver-tin (Ag-Sn) particles in gallium-indium (Ga-In), represent a
potential substitute for traditional dental amalgam.
Melting Point: Gallium has a melting point of 28°C,
allowing it to remain in a liquid state at room temperature when combined
with small amounts of other elements like indium.
Advantages
Mercury-Free: The substitution of Ga-In for mercury in
amalgam addresses concerns related to mercury exposure, making it a safer
alternative for both patients and dental professionals.