NEET MDS Synopsis
FACTORS AFFECTING ENZYME ACTIVITY
Biochemistry
FACTORS AFFECTING ENZYME ACTIVITY
Velocity or rate of enzymatic reaction is assessed by the rate of change in concentration of substrate or product at a given time duration. Various factors which affect the activity of enzymes include:
1. Substrate concentration
2. Enzyme concentration
3. Product concentration
4. Temperature 5. Hydrogen ion concentration (pH)
6. Presence of activators
7. Presence of inhibitor
Effect of substrate Concentration : Reaction velocity of an enzymatic process increases with constant enzyme concentration and increase in substrate concentration.
Effect of enzyme Concentration: As there is optimal substrate concentration, rate of an enzymatic reaction or velocity (V) is directly proportional to the enzyme concentration.
Effect of product concentration In case of a reversible reaction catalyzed by a enzyme, as per the law of mass action the rate of reaction is slowed down with equilibrium. So, rate of reaction is slowed, stopped or even reversed with increase in product concentration
Effect of temperature: Velocity of enzymatic reaction increases with temperature of the medium which they are most efficient and the same is termed as optimum temperature.
Effect of pH: Many enzymes are most efficient in the region of pH 6-7, which is the pH of the cell. Outside this range, enzyme activity drops off very rapidly. Reduction in efficiency caused by changes in the pH is due to changes in the degree of ionization of the substrate and enzyme.
Highly acidic or alkaline conditions bring about a denaturation and subsequent loss of enzymatic activity
Exceptions such as pepsin (with optimum pH 1-2), alkaline phosphatase (with optimum pH 9-10) and acid phosphatase (with optimum pH 4-5)
Presence of activators Presence of certain inorganic ions increases the activity of enzymes. The best examples are chloride ions activated salivary amylase and calcium activated lipases.
Effect of Inhibitors The catalytic enzymatic reaction may be inhibited by substances which prevent the formation of a normal enzyme-substrate complex. The level of inhibition then depends entirely upon the relative concentrations of the true substrate and the inhibitor
Classifications of epidemiologic research
Public Health Dentistry
Classifications of epidemiologic research
1. Descriptive research —involves description, documentation, analysis, and interpretation of data to evaluate a current event or situation
a. incidence—number of new cases of a specific disease within a defined population over a period of time
b. Prevalence—number of persons in a population affected by a condition at any one time
c. Count—simplest sum of disease: number of cases of disease occurrence
d. Proportion—use of a count with the addition of a denominator to determine prevalence:
does not include a time dimension: useful to evaluate prevalence of caries in schoolchildren or tooth loss in adult populations
e. Rate— uses a standardized denominator and includes a time dimension. for example. the number of deaths of newborn infants within first year of life per 1000 births
2. Analytical research—determines the cause of disease or if a causal relationship exists between a factor and a disease
a. Prospective study—planning of the entire study is completed before data are collected and analyzed; population is followed through time to determine which members develop the disease; several hypotheses may be tested at on time
b. Cohort study—individuals are classified into groups according to whether or not they pos- sess a particular characteristic thought to be related to the condition of interest; observations occur over time to see who develops dis ease or condition
c. Retrospective study— decision to carry out an investigation using observations or data that have been collected in the past; data may be incomplete or in a manner not appropriate for study
d. Cross-sectional study— study of subgroups of individuals in a specific and limited time frame to identify either initially to describe current status or developmental changes in the overall group from the perspective of what is typical in each subgroup
e. Longitudinal study—investigation of the same group of individuals over an extended period of time to identify a change or devel opment in that group
3. Experimental research—used when the etiology of the disease is established and the researcher wishes to determine the effectiveness of altering some factor or factors; deliberate applying or withholding of the supposed cause of a condition and observing the result
Complement Fixation Test (CFT)
General MicrobiologyComplement Fixation Test (CFT)
This test is based upon two properties of the complement viz:
a. Complent combines with all antigen-antibody complexes whether or not it is required for that reaction
b. Complement is needed in immunolytic reaction.
Test system
It contains an antigen and a serum suspected to be having antibody to that antigen. The serum is heat treated prior to the test to destroy its complement. Complement Is added in measured quantity to this system. This complement is the form of guinea pig serum which is considered a rich source of complement. The test system is incubated.
Indicator system
To test system, after incubation, is added the indicator system which consists of sheep
RBCs and antibody to sheep RBCs (haemolysin) and another incubation is allowed.
If there is specific antibody in the test system, it will bind to antigen and to this complex the complement will also get fixed. Hence, no complement will be available to combine with indicator system which though contains RBCs and their specific antibody, cannot undergo haemolysis unless complement gets attached. Absence of haemolysis shall indicated positive test or presence of specific antibody in the serum which has been added in the test system. Erythrocytes lysis is obtained in negative test.
Rheumatic fever
General Pathology
Rheumatic fever
Before antibiotic therapy, this was the most common cause of valvular disease.
1. Usually preceded by a group A streptococci respiratory infection; for example, strep throat.
2. All three layers of the heart may be affected. The pathologic findings include Aschoff bodies, which are areas of focal necrosis surrounded by a dense inflammatory infiltration.
3. Most commonly affects the mitral valve, resulting in mitral valve stenosis, regurgitation, or both.
COMPOSITE RESINS - Finishing and Polishing
Dental Materials
Finishing and Polishing
Remove oxygen-inhibited layer .Use stones or carbide burs for gross reduction.Use highly fluted carbide burs or special diamonds for fine reduction.Use aluminum oxide strips or disks for finishing. Use fine aluminum oxide finishing pastes. Microfills develop smoothest finish because of small size of filler particles
Composite Cavity Preparation
Conservative DentistryComposite Cavity PreparationComposite cavity preparations are designed to optimize the placement and
retention of composite resin materials in restorative dentistry. There are three
basic designs for composite cavity preparations: Conventional, Beveled
Conventional, and Modified. Each design has specific characteristics and
indications based on the clinical situation.
1. Conventional Preparation DesignA. Characteristics
Design: Similar to cavity preparations for amalgam
restorations.
Shape: Box-like cavity with slight occlusal
convergence, flat floors, and undercuts in dentin.
Cavosurface Angle: Near 90° (butt joint), which
provides a strong interface for the restoration.
B. Indications
Moderate to Large Class I and Class II Restorations:
Suitable for larger cavities where significant tooth structure is missing.
Replacement of Existing Amalgam: When an existing
amalgam restoration needs to be replaced, a conventional preparation is
often indicated.
Class II Cavities Extending onto the Root: In cases
where the cavity extends onto the root, a conventional design is preferred
to ensure adequate retention and support.
2. Beveled Conventional PreparationA. Characteristics
Enamel Cavosurface Bevel: Incorporation of a bevel at
the enamel margin to increase surface area for bonding.
End-on-Etching: The bevel allows for more effective
etching of the enamel rods, enhancing adhesion.
Benefits:
Improves retention of the composite material.
Reduces microleakage at the restoration interface.
Strengthens the remaining tooth structure.
B. Preparation Technique
Bevel Preparation: The bevel is created using a
flame-shaped diamond instrument, approximately 0.5 mm wide and angled at 45°
to the external enamel surface.
C. Indications
Large Area Restorations: Ideal for restoring larger
areas of tooth structure.
Replacing Existing Restorations: Suitable for class
III, IV, and VI cavities where composite is used to replace older
restorations.
Rarely Used for Posterior Restorations: While
effective, this design is less commonly used for posterior teeth due to
aesthetic considerations.
3. Modified PreparationA. Characteristics
Depth of Preparation: Does not routinely extend into
dentin; the depth is determined by the extent of the carious lesion.
Wall Configuration: No specified wall configuration,
allowing for flexibility in design.
Conservation of Tooth Structure: Aims to conserve as
much tooth structure as possible while obtaining retention through
micro-mechanical means (acid etching).
Appearance: Often has a scooped-out appearance,
reflecting its conservative nature.
B. Indications
Small Cavitated Carious Lesions: Best suited for small
carious lesions that are surrounded by enamel.
Correcting Enamel Defects: Effective for addressing
minor enamel defects without extensive preparation.
C. Modified Preparation Designs
Class III (A and B): For anterior teeth, focusing on
small defects or carious lesions.
Class IV (C and D): For anterior teeth with larger
defects, ensuring minimal loss of healthy tooth structure.
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.
Midazolam
Pharmacology
Midazolam -Intravenous Anesthetics
Midazolam is a benzodiazepine used for preoperative sedation, induction of anesthesia, or maintenance of anesthesia in short procedures.