NEET MDS Synopsis
Characteristics of Facilitated Diffusion & Active Transport
PhysiologyCharacteristics of Facilitated Diffusion & Active Transport - both require the use of carriers that are specific to particular substances (that is, each type of carrier can 'carry' one type of substance) and both can exhibit saturation (movement across a membrane is limited by number of carriers & the speed with which they move materials
Antihypertensives drugs -RENIN-ANGIOTENSIN SYSTEM INHIBITORS
Pharmacology
RENIN-ANGIOTENSIN SYSTEM INHIBITORS
The actions of Angiotensin II include an increase in blood pressure and a stimulation of the secretion of aldosterone (a hormone from the adrenal cortex) that promotes sodium retention. By preventing the formation of angiotensin II, blood pressure will be reduced. This is the strategy for development of inhibitors. Useful inhibitors of the renin-angiotensin system are the Angiotensin Converting Enzyme Inhibitors
First line treatment for: Hypertension , Congestive heart failure [CHF]
ACE-Inhibitor’s MOA (Angiotensin Converting Enzyme Inhibitors)
Renin-Angiotensin Aldosterone System:
. Renin & Angiotensin = vasoconstrictor
. constricts blood vessels & increases BP
. increases SVR or afterload
. ACE Inhibitors blocks these effects decreasing SVR & afterload
. Aldosterone = secreted from adrenal glands
. cause sodium & water reabsorption
. increase blood volume
. increase preload
. ACE I blocks this and decreases preload
Types
Class I: captopril
Class II (prodrug) : e.g., ramipril, enalapril, perindopril
Class III ( water soluble) : lisinopril.
Mechanism of Action
Inhibition of circulating and tissue angiotensin- converting enzyme.
Increased formation of bradykinin and vasodilatory prostaglandins.
Decreased secretion of aldosterone; help sodium excretion.
Advantages
- Reduction of cardiovascular morbidity and mortality in patients with atherosclerotic vascular disease, diabetes, and heart failure.
- Favorable metabolic profile.
- Improvement in glucose tolerance and insulin resistance.
- Renal glomerular protection effect especially in diabetes mellitus.
- Do not adversely affect quality of life.
Indications
- Diabetes mellitus, particularly with nephropathy.
- Congestive heart failure.
- Following myocardial infraction.
Side Effects
- Cough (10 - 30%): a dry irritant cough with tickling sensation in the throat.
- Skin rash (6%).
- Postural hypotension in salt depleted or blood volume depleted patients.
- Angioedema (0.2%) : life threatening.
- Renal failure: rare, high risk with bilateral renal artery stenosis.
- Hyperkalaemia
- Teratogenicity.
Considerations
- Contraindications include bilateral renal artery stenosis, pregnancy, known allergy, and hyperkalaemia.
- High serum creatinine (> 3 mg/dl) is an indication for careful monitoring of renal function, and potassium. Benefits can still be obtained in spite of renal insufficiency.
- A slight stable increase in serum creatinine after the introduction of ACE inhibitors does not limit use.
- ACE-I are more effective when combined with diuretics and moderate salt restriction.
ACE inhibitors drugs
Captopril 50-150 mg
Enalapril 2.5-40 mg
Lisinopril 10-40 mg
Ramipril 2.5-20 mg
Perindopril 2-8 mg
Angiotensin Receptor Blocker
Losartan 25-100 mg
Candesartan 4-32 mg
Telmisartan 20-80 mg
Mechanism of action
They act by blocking type I angiotensin II receptors generally, producing more blockade of the renin -angiotensin - aldosterone axis.
Advantages
• Similar metabolic profile to that of ACE-I.
• Renal protection.
• They do not produce cough.
Indications
Patients with a compelling indication for ACE-I and who can not tolerate them because of cough or allergic reactions.
Connective Tissue of the Gingiva
PeriodontologyConnective Tissue of the Gingiva and Related Cellular Components
The connective tissue of the gingiva, known as the lamina propria,
plays a crucial role in supporting the gingival epithelium and maintaining
periodontal health. This lecture will cover the structure of the lamina propria,
the types of connective tissue fibers present, the role of Langerhans cells, and
the changes observed in the periodontal ligament (PDL) with aging.
Structure of the Lamina Propria
Layers of the Lamina Propria:
The lamina propria consists of two distinct layers:
Papillary Layer:
The upper layer that interdigitates with the epithelium,
containing finger-like projections that increase the surface
area for exchange of nutrients and waste.
Reticular Layer:
The deeper layer that provides structural support and
contains larger blood vessels and nerves.
Types of Connective Tissue Fibers:
The lamina propria contains three main types of connective tissue
fibers:
Collagen Fibers:
Type I Collagen: Forms the bulk of the
lamina propria and provides tensile strength to the gingival
fibers, essential for maintaining the integrity of the gingiva.
Reticular Fibers:
These fibers provide a supportive network within the
connective tissue.
Elastic Fibers:
Contribute to the elasticity and flexibility of the gingival
tissue.
Type IV Collagen:
Found branching between the Type I collagen bundles, it is
continuous with the fibers of the basement membrane and the walls of
blood vessels.
Langerhans Cells
Description:
Langerhans cells are dendritic cells located among keratinocytes at
all suprabasal levels of the gingival epithelium.
They belong to the mononuclear phagocyte system and play a critical
role in immune responses.
Function:
Act as antigen-presenting cells for lymphocytes, facilitating the
immune reaction.
Contain specific granules known as Birbeck’s granules and
exhibit marked ATP activity.
Location:
Found in the oral epithelium of normal gingiva and in small amounts
in the sulcular epithelium.
Absent from the junctional epithelium of normal gingiva.
Changes in the Periodontal Ligament (PDL) with Aging
Aging Effects:
With aging, several changes have been reported in the periodontal
ligament:
Decreased Numbers of Fibroblasts: This
reduction can lead to impaired healing and regeneration of the PDL.
Irregular Structure: The PDL may exhibit a more
irregular structure, paralleling changes in the gingival connective
tissues.
Decreased Organic Matrix Production: This can
affect the overall health and function of the PDL.
Epithelial Cell Rests: There may be a decrease
in the number of epithelial cell rests, which are remnants of the
Hertwig's epithelial root sheath.
Increased Amounts of Elastic Fibers: This
change may contribute to the altered mechanical properties of the
PDL.
Riboflavin: Vitamin B2
Biochemistry
Riboflavin: Vitamin B2
Riboflavin, or vitamin B2, helps to release energy from foods, promotes good vision, and healthy skin. It also helps to convert the amino acid tryptophan (which makes up protein) into niacin.
RDA Males: 1.3 mg/day; Females: 1.1 mg/day
Deficiency : Symptoms of deficiency include cracks at the corners of the mouth, dermatitis on nose and lips, light sensitivity, cataracts, and a sore, red tongue.
Blood Transfusions
PhysiologyBlood Transfusions
Some of these units ("whole blood") were transfused directly into patients (e.g., to replace blood lost by trauma or during surgery).
Most were further fractionated into components, including:
RBCs. When refrigerated these can be used for up to 42 days.
platelets. These must be stored at room temperature and thus can be saved for only 5 days.
plasma. This can be frozen and stored for up to a year.
safety of donated blood
A variety of infectious agents can be present in blood.
viruses (e.g., HIV-1, hepatitis B and C, HTLV, West Nile virus
bacteria like the spirochete of syphilis
protozoans like the agents of malaria and babesiosis
prions (e.g., the agent of variant Crueutzfeldt-Jakob disease)
and could be transmitted to recipients. To minimize these risks,
donors are questioned about their possible exposure to these agents;
each unit of blood is tested for a variety of infectious agents.
Most of these tests are performed with enzyme immunoassays (EIA) and detect antibodies against the agents. blood is now also checked for the presence of the RNA of these RNA viruses:
HIV-1
hepatitis C
West Nile virus
by the so-called nucleic acid-amplification test (NAT).
Congenital heart defect
General Pathology
Congenital heart defect
Congenital heart defects can be broadly categorised into two groups,
o acyanotic heart defects ('pink' babies) :
An acyanotic heart defect is any heart defect of a group of structural congenital heart defects, approximately 75% of all congenital heart defects.
It can be subdivided into two groups depending on whether there is shunting of the blood from the left vasculature to the right (left to right shunt) or no shunting at all.
Left to right shunting heart defects include
- ventricular septal defect or VSD (30% of all congenital heart defects),
- persistent ductus arteriosus or PDA,
- atrial septal defect or ASD,
- atrioventricular septal defect or AVSD.
Acyanotic heart defects without shunting include
- pulmonary stenosis, a narrowing of the pulmonary valve,
- aortic stenosis
- coarctation of the aorta.
cyanotic heart defects ('blue' babies).
obstructive heart defects
cyanotic heart defect is a group-type of congenital heart defect. These defects account for about 25% of all congenital heart defects. The patient appears blue, or cyanotic, due to deoxygenated blood in the systemic circulation. This occurs due to either a right to left or a bidirectional shunt, allowing significant proportions of the blood to bypass the pulmonary vascular bed; or lack of normal shunting, preventing oxygenated blood from exiting the cardiac-pulmonary system (as with transposition of the great arteries).
Defects in this group include
hypoplastic left heart syndrome,
tetralogy of Fallot,
transposition of the great arteries,
tricuspid atresia,
pulmonary atresia,
persistent truncus arteriosus.
Naber’s Probe and Furcation Involvement
Periodontology Naber’s Probe and Furcation Involvement
Furcation involvement is a critical aspect of periodontal disease that
affects the prognosis of teeth with multiple roots. Naber’s probe is a
specialized instrument designed to assess furcation areas, allowing clinicians
to determine the extent of periodontal attachment loss and the condition of the
furcation. This lecture will cover the use of Naber’s probe, the classification
of furcation involvement, and the clinical significance of these
classifications.
Naber’s Probe
Description: Naber’s probe is a curved, blunt-ended
instrument specifically designed for probing furcation areas. Its unique
shape allows for horizontal probing, which is essential for accurately
assessing the anatomy of multi-rooted teeth.
Usage: The probe is inserted horizontally into the
furcation area to evaluate the extent of periodontal involvement. The
clinician can feel the anatomical fluting between the roots, which aids in
determining the classification of furcation involvement.
Classification of Furcation Involvement
Furcation involvement is classified into four main classes using Naber’s
probe:
Class I:
Description: The furcation can be probed to a depth
of 3 mm.
Clinical Findings: The probe can feel the
anatomical fluting between the roots, but it cannot engage the roof of
the furcation.
Significance: Indicates early furcation involvement
with minimal attachment loss.
Class II:
Description: The furcation can be probed to a depth
greater than 3 mm, but not through and through.
Clinical Findings: This class represents a range
between Class I and Class III, where there is partial loss of attachment
but not complete penetration through the furcation.
Significance: Indicates moderate furcation
involvement that may require intervention.
Class III:
Description: The furcation can be completely probed
through and through.
Clinical Findings: The probe passes from one
furcation to the other, indicating significant loss of periodontal
support.
Significance: Represents advanced furcation
involvement, often associated with a poor prognosis for the affected
tooth.
Class III+:
Description: The probe can go halfway across the
tooth.
Clinical Findings: Similar to Class III, but with
partial obstruction or remaining tissue.
Significance: Indicates severe furcation
involvement with a significant loss of attachment.
Class IV:
Description: Clinically, the examiner can see
through the furcation.
Clinical Findings: There is complete loss of tissue
covering the furcation, making it visible upon examination.
Significance: Indicates the most severe form of
furcation involvement, often leading to tooth mobility and extraction.
Measurement Technique
Measurement Reference: Measurements are taken from an
imaginary tangent connecting the prominences of the root surfaces of both
roots. This provides a consistent reference point for assessing the depth of
furcation involvement.
Clinical Significance
Prognosis: The classification of furcation involvement
is crucial for determining the prognosis of multi-rooted teeth. Higher
classes of furcation involvement generally indicate a poorer prognosis and
may necessitate more aggressive treatment strategies.
Treatment Planning: Understanding the extent of
furcation involvement helps clinicians develop appropriate treatment plans,
which may include scaling and root planing, surgical intervention, or
extraction.
Monitoring: Regular assessment of furcation involvement
using Naber’s probe can help monitor disease progression and the
effectiveness of periodontal therapy.
Digital Radiology
Radiology
Digital Radiology
Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen.
DIGITAL IMAGE RECEPTORS
- charged coupled device (CCD) used
- Pure silicon divided into pixels.
- Electromagnetic energy from visible light or X-rays interacts with pixels to create an electric charge that can be stored.
- Stored charges are transmitted electronically and create an analog output signal and displayed via digital converter (analog to digital converter).
ADVANTAGES OF DIGITAL TECHNIQUE
Immediate display of images.
Enhancement of image (e.g., contrast, gray scale, brightness).
Radiation dose reduction up to 60%.
Major disadvantage: High initial cost of sensors. Decreased image resolution and contrast as compared to D speed ?lms.
DIRECT IMAGING
- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.
- Performance is comparable to ?lm radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.
INDIRECT IMAGING
- Radiographic ?lm is used as the image receiver (detector).
- Image is digitized from signals created by a video device or scanner that views the radiograph.
Sensors
STORAGE PHOSPHOR IMAGING SYSTEMS
Phosphor screens are exposed to ionizing radiation which excites BaFBR:EU+2 crystals in the screen storing the image.
A computer-assisted laser then promotes the release of energy from the crystals in the form of blue light.
The blue light is scanned and the image is reconstructed digitally.
ELECTRONIC SENSOR SYSTEMS
X-rays are converted into light which is then read by an electronic sensor such as a CCD or CMOS.
Other systems convert the electromagnetic radiation directly into electrical impulses.
Digital image is created out of the electrical impulses.