NEET MDS Synopsis
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.
Fluconazole
Pharmacology
Fluconazole: an antifungal used orally, intravenously or vaginally to treat yeast and fungal infections. Side-effects of systemic administration include hepatotoxicity (liver damage).
For vaginal candidiasis (vaginal thrush), a once-only oral dose is often sufficient.
Different Systems of the CNS & their functions
Pharmacology
Different Systems of the CNS & their functions
These systems are pathways formed of specific parts of the brain and the neurons connecting them.
They include:
1.The pyramidal system
2.The extrapyramidal system
3.The limbic system
4.The reticular formation
5.The tuberohypophyseal system
The pyramidal system:
It originates from the motor area of the cerebral cortex and passes through the spinal cord, therefore it is also known as the “corticospinaltract”.
It is responsible for the regulation of the fine voluntary movements.
The extrapyramidal system:
It also controls the motor functionbut involves areas other than the corticospinal tract.
It is involved in the regulation of gross voluntary movements, thus it complements the function of the pyramidal system.
The “basal ganglia” constitute an essential part of this system.
Degenerative changes in the pathway running from the “substantianigra”to the “corpus striatum”(or nigrostriatal pathway) may cause tremors and muscle rigidity characteristic of “Parkinson’s disease”.
The limbic system:
The major parts of this system are: the hypothalamus, the basal ganglia, the hippocampus(responsible for short term memory), and some cortical areas.
The limbic system is involved in the control of “behavior”& “emotions”.
The reticular formation:
It is composed of interlacing fibers and nerve cells that run in all directions beginning from the upper part of the spinal cord and extending upwards.
It is important in the control of “consciousness” and “wakefulness”.
The tuberohypophyseal system:
It is a group of short neurons running from the hypothalamusto the hypophysis(pituitary gland) regulating its secretions.
INVESTING
Dental Materials
INVESTING
Mixing investment with distilled water is done according to the manufacturers ratio in a clean dry bowl without entrapment of the air into the mix.
Mixing methods:
a. Hand mixing and the use of the vibrator to remove air bubbles.
b. Vacuum mixing- This is the better method because it removes air bubbles as well as gases that are produced and thus produces a smoother mix.
Methods of investing:
a. Hand investing
b. Vacuum investing
Hand investing:
First the mixed investment is applied on all the surfaces of the pattern with a soft brush. Blow off any excess investment gently, thus leaving a thin film of investment over the pattern, then apply again.
Then the coated pattern can be invested by two methods;
1. Placing the pattern in the ring first and then filling the ring full with investment.
2. Filling the ring with the investment first and then force the pattern through into it.
Vacuum investing :
Vacuum investing unit: This consists of the chamber of small cubic capacity from which air can be evacuated quickly and in which casting ring can be placed.
Evacuation of air can be done by electrically or water driven vacuum pump.
Procedure:
The ring filled with investment is placed in the vacuum chamber. Air entry tube is closed. Then the vacuum is applied. The investment will rise with froth vigorously for about 10-15 sec and then settles back. This indicates that air has been extracted from the ring. The pressure is now restored to atmospheric by opening the air entry tap gradually at first and then more rapidly as the investment settles back around the pattern. Then the ring is removed from the chamber and the investment is allowed to set. Modern investing unit does both mixing and investing under vacuum and is considered better than hand mixing and pouring.
Then there are two alternatives to be followed depending upon what type of expansion is to be achieved in order to compensate for metal shrinkage. They are:
1. If hygroscopic expansion of the investment is to be achieved then immediately immerse the filled ring in water at the temperature of 37C.
Or “under controlled water adding technique”. A soft flexible rubber ring is used instead of usual lined metal ring. Pattern is invested as usual. Then specified amount of water is added on top of the investment in the rubber ring and the investment is allowed to set at room temperature. In this way only enough water is added to the investment to provide the desired expansion.
2. If thermal expansion of the investment is to be achieved, then investment is allowed to set by placing the ring on the bench for 1 hour or as recommended by the manufacturer.
Krebs Cycle
Biochemistry
Glycolysis enzymes are located in the cytosol of cells. Pyruvate enters the mitochondrion to be metabolized further
Mitochondrial compartments: The mitochondrial matrix contains Pyruvate Dehydrogenase and enzymes of Krebs Cycle, plus other pathways such as fatty acid oxidation.
Pyruvate Dehydrogenase catalyzes oxidative decarboxylation of pyruvate, to form acetyl-CoA
FAD (Flavin Adenine Dinucleotide) is a derivative of the B-vitamin riboflavin (dimethylisoalloxazine-ribitol). The flavin ring system undergoes oxidation/reduction as shown below. Whereas NAD+ is a coenzyme that reversibly binds to enzymes, FAD is a prosthetic group, that is permanently part of the complex.
FAD accepts and donates 2 electrons with 2 protons (2 H):
Thiamine pyrophosphate (TPP) is a derivative of thiamine (vitamin B1). Nutritional deficiency of thiamine leads to the disease beriberi. Beriberi affects especially the brain, because TPP is required for carbohydrate metabolism, and the brain depends on glucose metabolism for energy
Acetyl CoA, a product of the Pyruvate Dehydrogenase reaction, is a central compound in metabolism. The "high energy" thioester linkage makes it an excellent donor of the acetate moiety
For example, acetyl CoA functions as:
input to the Krebs Cycle, where the acetate moiety is further degraded to CO2.
donor of acetate for synthesis of fatty acids, ketone bodies, and cholesterol.
ATPs formed in TCA cycle from one molecule of Pyruvate
1. 3ATP 7. 3ATP 5. 3 ATP
8. 1 ATP 9. 2 ATP 11.3 ATP Total =15 ATP.
ATPS formed from one molecule of Acetyl CoA =12ATP
ATPs formed from one molecule of glucose after complete oxidation
One molecule of glucose -->2 molecules of pyruvate
['By glycolysis] ->8 ATP
2 molecules of pyruvate [By TCA cycle] -> 30 ATP
Total = 38 ATP
Platelet-Derived Growth Factor
PeriodontologyPlatelet-Derived Growth Factor (PDGF)
Platelet-Derived Growth Factor (PDGF) is a crucial glycoprotein involved in
various biological processes, particularly in wound healing and tissue repair.
Understanding its role and mechanisms can provide insights into its applications
in regenerative medicine and periodontal therapy.
Overview of PDGF
Definition:
PDGF is a glycoprotein that plays a significant role in cell growth,
proliferation, and differentiation.
Source:
PDGF is carried in the alpha granules of platelets
and is released during the process of blood clotting.
Discovery:
It was one of the first growth factors to be described in scientific
literature.
Originally isolated from platelets, PDGF was found to exhibit mitogenic
activity specifically in smooth muscle cells.
Functions of PDGF
Mitogenic Activity:
PDGF stimulates the proliferation of various cell types, including:
Smooth muscle cells
Fibroblasts
Endothelial cells
This mitogenic activity is essential for tissue repair and
regeneration.
Role in Wound Healing:
PDGF is released at the site of injury and plays a critical role in:
Promoting cell migration to the wound site.
Stimulating the formation of new blood vessels (angiogenesis).
Enhancing the synthesis of extracellular matrix components,
which are vital for tissue structure and integrity.
Involvement in Periodontal Healing:
In periodontal therapy, PDGF can be utilized to enhance healing in
periodontal defects and promote regeneration of periodontal tissues.
It has been studied for its potential in guided tissue regeneration
(GTR) and in the treatment of periodontal disease.
Clinical Applications
Regenerative Medicine:
PDGF is being explored in various regenerative medicine
applications, including:
Bone regeneration
Soft tissue healing
Treatment of chronic wounds
Periodontal Therapy:
PDGF has been incorporated into certain periodontal treatment
modalities to enhance healing and regeneration of periodontal tissues.
It can be used in conjunction with graft materials to improve
outcomes in periodontal surgery.
Ariston pHc Alkaline Glass Restorative
Conservative DentistryAriston pHc Alkaline Glass Restorative
Ariston pHc is a notable dental restorative material developed by Ivoclar
Vivadent in 1990. This innovative material is designed to provide both
restorative and preventive benefits, particularly in the management of dental
caries.
1. Introduction
Manufacturer: Ivoclar Vivadent (Liechtenstein)
Year of Introduction: 1990
2. Key Features
A. Ion Release Mechanism
Fluoride, Hydroxide, and Calcium Ions: Ariston pHc
releases fluoride, hydroxide, and calcium ions when the pH within the
restoration falls to critical levels. This release occurs in response to
acidic conditions that can lead to enamel and dentin demineralization.
B. Acid Neutralization
Counteracting Decalcification: The ions released by
Ariston pHc help neutralize acids in the oral environment, effectively
counteracting the decalcification of both enamel and dentin. This property
is particularly beneficial in preventing further carious activity around the
restoration.
3. Material Characteristics
A. Light-Activated
Curing Method: Ariston pHc is a light-activated
material, allowing for controlled curing and setting. This feature enhances
the ease of use and application in clinical settings.
B. Bulk Thickness
Curing Depth: The material can be cured in bulk
thicknesses of up to 4 mm, making it suitable for various cavity
preparations, including larger restorations.
4. Indications for Use
A. Recommended Applications
Class I and II Lesions: Ariston pHc is recommended for
use in Class I and II lesions in both deciduous (primary) and permanent
teeth. Its properties make it particularly effective in managing carious
lesions in children and adults.
5. Clinical Benefits
A. Preventive Properties
Remineralization Support: The release of fluoride and
calcium ions not only helps in neutralizing acids but also supports the
remineralization of adjacent tooth structures, enhancing the overall health
of the tooth.
B. Versatility
Application in Various Situations: The ability to cure
in bulk and its compatibility with different cavity classes make Ariston pHc
a versatile choice for dental practitioners.
Aspects of Pathology
General Pathology
Pathology gives explanations of a disease by studying the following four aspects of the disease.
1. Etiology,
2. Pathogenesis,
3. Morphologic changes and
4. Functional derangements and clinical significance.
1. Etiology Etiology of a disease means the cause of the disease. If the cause of a disease is known it is called primary etiology. If the cause of the disease is unknown it is called idiopathic. Knowledge or discovery of the primary cause remains the backbone on which a diagnosis can be made, a disease understood, & a treatment developed. There are two major classes of etiologic factors: genetic and acquired (infectious, nutritional, chemical, physical, etc).
2. Pathogenesis Pathogenesis means the mechanism through which the cause operates to produce the pathological and clinical manifestations. The pathogenetic mechanisms could take place in the latent or incubation period. Pathogenesis leads to morphologic changes.
3. Morphologic changes The morphologic changes refer to the structural alterations in cells or tissues that occur following the pathogenetic mechanisms. The structural changes in the organ can be seen with the naked eye or they may only be seen under the microscope. Those changes that can be seen with the naked eye are called gross morphologic changes & those that are seen under the microscope are called microscopic changes. the morphologic changes will lead to functional alteration & to the clinical signs & symptoms of the disease.
4. Functional derangements and clinical significance The morphologic changes in the organ influence the normal function of the organ. By doing so, they determine the clinical features (symptoms and signs), course, and prognosis of the disease.