NEET MDS Synopsis
Parathyroid Hormone
Biochemistry
Parathyroid Hormone
Parathyroid hormone (PTH), parathormone or parathyrin, is secreted by the chief cells of the parathyroid glands.
It acts to increase the concentration of calcium (Ca2+) in the blood, whereas calcitonin (a hormone produced by the parafollicular cells of the thyroid gland) acts to decrease calcium concentration.
PTH acts to increase the concentration of calcium in the blood by acting upon the parathyroid hormone 1 receptor (high levels in bone and kidney) and the parathyroid hormone 2 receptor (high levels in the central nervous system, pancreas, testis, and placenta).
Effect of parathyroid hormone in regulation of serum calcium.
Bone -> PTH enhances the release of calcium from the large reservoir contained in the bones. Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH forming new osteoclasts, which ultimately enhances bone resorption.
Kidney -> PTH enhances active reabsorption of calcium and magnesium from distal tubules of kidney. As bone is degraded, both calcium and phosphate are released. It also decreases the reabsorption of phosphate, with a net loss in plasma phosphate concentration. When the calcium:phosphate ratio increases, more calcium is free in the circulation.
Intestine -> PTH enhances the absorption of calcium in the intestine by increasing the production of activated vitamin D. Vitamin D activation occurs in the kidney. PTH converts vitamin D to its active form (1,25-dihydroxy vitamin D). This activated form of vitamin D increases the absorption of calcium (as Ca2+ ions) by the intestine via calbindin.
Multiphase and Multistage random sampling
Public Health DentistryMultiphase and multistage random sampling are advanced
sampling techniques used in research, particularly in public health and social
sciences, to efficiently gather data from large and complex populations. Both
methods are designed to reduce costs and improve the feasibility of sampling
while maintaining the representativeness of the sample. Here’s a detailed
explanation of each method:
Multiphase Sampling
Description: Multiphase sampling involves conducting a
series of sampling phases, where each phase is used to refine the sample
further. This method is particularly useful when the population is large and
heterogeneous, and researchers want to focus on specific subgroups or
characteristics.
Process:
Initial Sampling: In the first phase, a large sample is
drawn from the entire population using a probability sampling method (e.g.,
simple random sampling or stratified sampling).
Subsequent Sampling: In the second phase, researchers
may apply additional criteria to select a smaller, more specific sample from
the initial sample. This could involve stratifying the sample based on
certain characteristics (e.g., age, health status) or conducting follow-up
surveys.
Data Collection: Data is collected from the final
sample, which is more targeted and relevant to the research question.
Applications:
Public Health Surveys: In a study assessing health
behaviors, researchers might first sample a broad population and then focus
on specific subgroups (e.g., smokers, individuals with chronic diseases) for
more detailed analysis.
Qualitative Research: Multiphase sampling can be used
to identify participants for in-depth interviews after an initial survey has
highlighted specific areas of interest.
Multistage Sampling
Description: Multistage sampling is a complex form of
sampling that involves selecting samples in multiple stages, often using a
combination of probability sampling methods. This technique is particularly
useful for large populations spread over wide geographic areas.
Process:
First Stage: The population is divided into clusters
(e.g., geographic areas, schools, or communities). A random sample of these
clusters is selected.
Second Stage: Within each selected cluster, a further
sampling method is applied to select individuals or smaller units. This
could involve simple random sampling, stratified sampling, or systematic
sampling.
Additional Stages: More stages can be added if
necessary, depending on the complexity of the population and the research
objectives.
Applications:
National Health Surveys: In a national health survey,
researchers might first randomly select states (clusters) and then randomly
select households within those states to gather health data.
Community Health Assessments: Multistage sampling can
be used to assess oral health in a large city by first selecting
neighborhoods and then sampling residents within those neighborhoods.
Key Differences
Structure:
Multiphase Sampling involves multiple phases of
sampling that refine the sample based on specific criteria, often
leading to a more focused subgroup.
Multistage Sampling involves multiple stages of
sampling, often starting with clusters and then selecting individuals
within those clusters.
Purpose:
Multiphase Sampling is typically used to narrow
down a broad sample to a more specific group for detailed study.
Multistage Sampling is used to manage large
populations and geographic diversity, making it easier to collect data
from a representative sample.
Adrenocortical Hyperfunction
General Pathology
Adrenocortical Hyperfunction (Hyperadrenalism)
Hypercortisolism (Cushing Syndrome) is caused by any condition that produces an elevation in glucocorticoid levels. The causes of this syndrome are
A. Exogenous through administration of exogenous glucocorticoids; the most common causeB. Endogenous
1. Hypothalamic-pituitary diseases causing hypersecretion of ACTH (Cushing disease)
2. Adrenocortical hyperplasia or neoplasia
3. Ectopic ACTH secretion by nonendocrine neoplasms (paraneoplastic)
Pathological features
- The main lesions of Cushing syndrome are found in the pituitary and adrenal glands.
- The most common change in the pituitary, results from high levels of endogenous or exogenous glucocorticoids, is termed Crooke hyaline change. In this condition, the normal granular, basophilic cytoplasm of the ACTH-producing cells in the anterior pituitary is replaced by homogeneous, lightly basophilic material. This is due to accumulation of intermediate keratin filaments in the cytoplasm.
- There is one of four changes in the adrenal glands, which depends on the cause.
1. Cortical atrophy
2. Diffuse hyperplasia
3. Nodular hyperplasia
4. Adenoma, rarely a carcinoma
1. In patients in whom the syndrome results from exogenous glucocorticoids, suppression of endogenous ACTH results in bilateral cortical atrophy, due to a lack of stimulation of the cortex by ACTH. In cases of endogenous hypercortisolism, in contrast, the adrenals either are hyperplastic or contain a cortical neoplasm.
2. In Diffuse hyperplasia the adrenal cortex is diffusely thickened and yellow, as a result of an increase in the size and number of lipid-rich cells in the zonae fasciculata and reticularis.
3. Nodular hyperplasia, which takes the form of bilateral, up to 2.0-cm, yellow nodules scattered throughout the cortex.
4. Primary adrenocortical neoplasms causing Cushing syndrome may be benign or malignant. The adrenocortical adenomas are yellow tumors surrounded by capsules, and most weigh < 30 gm .
Methyl salicylate
Pharmacology
Methyl salicylate
also known as oil of wintergreen, betula oil, methyl ester) is a natural product of many species of plants Structurally, it is methylated salicylic acid It is used as an ingredient in deep heating rubs
Classification of Periodontal Pockets
PeriodontologyClassification of Periodontal Pockets
Periodontal pockets are an important aspect of periodontal disease,
reflecting the health of the supporting structures of the teeth. Understanding
the classification of these pockets is essential for diagnosis, treatment
planning, and management of periodontal conditions.
Classification of Pockets
Gingival Pocket:
Also Known As: Pseudo-pocket.
Formation:
Formed by gingival enlargement without destruction of the
underlying periodontal tissues.
The sulcus is deepened due to the increased bulk of the gingiva.
Characteristics:
There is no destruction of the supporting periodontal tissues.
Typically associated with conditions such as gingival
hyperplasia or inflammation.
Periodontal Pocket:
Definition: A pocket that results in the
destruction of the supporting periodontal tissues, leading to the
loosening and potential exfoliation of teeth.
Classification Based on Location:
Suprabony Pocket:
The base of the pocket is coronal to the alveolar bone.
The pattern of bone destruction is horizontal.
The transseptal fibers are arranged horizontally in the
space between the base of the pocket and the alveolar bone.
Infrabony Pocket:
The base of the pocket is apical to the alveolar bone,
meaning the pocket wall lies between the bone and the tooth.
The pattern of bone destruction is vertical.
The transseptal fibers are oblique rather than horizontal.
Classification of Periodontal Pockets
Suprabony Pocket (Supracrestal or Supraalveolar):
Location: Base of the pocket is coronal to the
alveolar bone.
Bone Destruction: Horizontal pattern of bone loss.
Transseptal Fibers: Arranged horizontally.
Infrabony Pocket (Intrabony, Subcrestal, or
Intraalveolar):
Location: Base of the pocket is apical to the
alveolar bone.
Bone Destruction: Vertical pattern of bone loss.
Transseptal Fibers: Arranged obliquely.
Classification of Pockets According to Involved Tooth Surfaces
Simple Pocket:
Definition: Involves only one tooth surface.
Example: A pocket that is present only on the
buccal surface of a tooth.
Compound Pocket:
Definition: A pocket present on two or more
surfaces of a tooth.
Example: A pocket that involves both the buccal and
lingual surfaces.
Spiral Pocket:
Definition: Originates on one tooth surface and
twists around the tooth to involve one or more additional surfaces.
Example: A pocket that starts on the mesial surface
and wraps around to the distal surface.
SULPHONAMIDES
Pharmacology
SULPHONAMIDES
Derivative of sulphonilamide (Para-amino Benzene (PABA ) sulphonamide).
Anti-bacterial spectrum
Bacteriostatic to gram + and gram - bacteria. but bactericidal concentrations arce attained in urine. S pyogencs. H influenzae.E coli, few- Staph aureus. gonococci. pneumococci, proteus, shigella and Lymphogranuloma venereum.
Mechanism of action
Inhibits bacterial folate synthetase as they compete with PABA
Less soluble in acid urine and may precipitate to cause crystalluria.
Accumulate in patients with renal failure and can cause toxicity
Classification
Shart Acting (4-8 Hrs) sulphadiazine, sulphamethizole.
Intermediate acting(8-16 Hrs): sulphamethoxazole , sulphaphenazole
Long Acting(l-7days): sulphamethoxypyridazine.
Ultralong Acting(3-8days): sulfaline
Adverse effects
I. nausea, vomiting and epigastric pain
2. crystalluria
3. hypersensitivity-like polyarthritis nodosa. Steven-Johnson Syndrome. photosenstivity
4.hemolysis in G-6PD deficiency
5. kernicterus
They inhibit metabolism of phenytoin. tolbutamide. methotrexate
Therapeutic Use
UTI Meningitis, Streptococcal pharyngitis, Bacillary Dysentery
Uses of NSAIDs
Pharmacology
Uses of NSAIDs
NSAIDs are usually indicated for the treatment of acute or chronic conditions where pain and inflammation are present. Research continues into their potential for prevention of colorectal cancer, and treatment of other conditions, such as cancer and cardiovascular disease.
NSAIDs are generally indicated for the symptomatic relief of the following conditions.
rheumatoid arthritis, osteoarthritis, inflammatory arthropathies (e.g. ankylosing spondylitis, psoriatic arthritis, Reiter's syndrome), acute gout, dysmenorrhoea, metastatic bone pain ,headache and migraine, postoperative pain, mild-to-moderate pain due to inflammation and tissue injury, pyrexia, renal colic
Aspirin, the only NSAID able to irreversibly inhibit COX-1, is also indicated for inhibition of platelet aggregation; an indication useful in the management of arterial thrombosis and prevention of adverse cardiovascular events.
VITAMIN C
Biochemistry
VITAMIN C: ASCORBIC ACID, ASCORBATE
Vitamin C benefits the body by holding cells together through collagen synthesis; collagen is a connective tissue that holds muscles, bones, and other tissues together. Vitamin C also aids in wound healing, bone and tooth formation, strengthening blood vessel walls, improving immune system function, increasing absorption and utilization of iron, and acting as an antioxidant.
RDA The Recommended Dietary Allowance (RDA) for Vitamin C is 90 mg/day for adult males and 75 mg/day for adult females
Vitamin C Deficiency
Severe vitamin C deficiency result in the disease known as scurvy, causing a loss of collagen strength throughout the body. Loss of collagen results in loose teeth, bleeding and swollen gums, and improper wound healing.