NEET MDS Synopsis
Classification for antiasthmatic drugs.
Pharmacology
SYMPATHOMIMETICS
β2 -agonists are invariably used in the symptomatic treatment of asthma.
Epinephrine and ephedrine are structurally related to the catecholamine norepinephrine, a neurotransmitter of the adrenergic nervous system
Some of the important β 2 agonists like salmeterol, terbutaline and salbutamol are invariably used as bronchodilators both oral as well as
aerosol inhalants
SALBUTAMOL
It is highly selective β2 -adrenergic stimulant h-aving a prominent bronchodilator action.
It has poor cardiac action compared to isoprenaline.
TERBUTALINE
It is highly selective β2 agonist similar to salbutamol, useful by oral as well as inhalational route.
SALMETEROL
Salmeterol is long-acting analogue of salbutamol
BAMBUTEROL
It is a latest selective adrenergic β2 agonist with long plasma half life and given once daily in a dose of 10-20 mg orally.
METHYLXANTHINES (THEOPHYLLINE AND ITS DERIVATIVES)
THEOPHYLLINE
Theophylline has two distinct action:
smooth muscle relaxation (i.e. bronchodilatation) and suppression of the response of the airways to stimuli (i.e. non-bronchodilator prophylactic effects).
ANTICHOLINERGICS
Anticholinergics, like atropine and its derivative ipratropium bromide block cholinergic pathways that cause airway constriction.
MAST CELL STABILIZERS
SODIUM CROMOGLYCATE
It inhibits degranulation of mast cells by trigger stimuli.
It also inhibits the release of various asthma provoking mediators e.g. histamine, leukotrienes, platelet activating factor (PAF) and interleukins (IL’s) from mast cell
KETOTIFEN
It is a cromolyn analogue. It is an antihistaminic (H1 antagonist) and probably inhibits airway inflammation induced by platelet activating factor (PAF) in primate.
It is not a bronchodilator. It is used in asthma and symptomatic relief in atopic dermatitis, rhinitis, conjunctivitis and urticaria.
LEUKOTRIENE PATHWAY INHIBITORS
MONTELUKAST
It is a cysteinyl leukotriene receptor antagonist indicated for the management of persistent asthma.
PERTUSSIS
General Pathology
PERTUSSIS (Whooping Cough)
An acute, highly communicable bacterial disease caused by Bordetella pertussis and characterized by a paroxysmal or spasmodic cough that usually ends in a prolonged, high-pitched, crowing inspiration (the whoop).
Transmission is by aspiration of B. pertussis
Symptoms and Signs
The incubation period averages 7 to 14 days (maximum, 3 wk). B. pertussis invades the mucosa of the nasopharynx, trachea, bronchi, and bronchioles, increasing the secretion of mucus, which is initially thin and later viscid and tenacious. The uncomplicated disease lasts about 6 to 10 wk and consists of three stages: catarrhal, paroxysmal, and convalescent.
Pantothenic Acid
Biochemistry
Pantothenic Acid
Pantothenic Acid is involved in energy production, and aids in the formation of hormones and the metabolism of fats, proteins, and carbohydrates from food.
RDA The Adequate Intake (AI) for Pantothenic Acid is 5 mg/day for both adult males and females.
Pantothenic Acid Deficiency
Pantothenic Acid deficiency is uncommon due to its wide availability in most foods.
Surgical Gut (Catgut)
Oral and Maxillofacial Surgery
Surgical Gut (Catgut)
Surgical gut, commonly known as catgut, is a type of
absorbable suture material derived from the intestines of animals, primarily
sheep and cattle. It has been widely used in surgical procedures due to its
unique properties, although it has certain limitations. Below is a detailed
overview of surgical gut, including its composition, properties, mechanisms of
absorption, and clinical applications.
Composition and Preparation
Source: Surgical gut is prepared from:
Submucosa of Sheep Small Intestine: This layer is
rich in collagen, which is essential for the strength and absorbability
of the suture.
Serosal Layer of Cattle Small Intestine: This layer
also provides collagen and is used in the production of surgical gut.
Collagen Content: The primary component of surgical gut
is collagen, which is treated with formaldehyde to enhance its properties.
This treatment helps stabilize the collagen structure and prolongs the
suture's strength.
Suture Characteristics:
Multifilament Structure: Surgical gut is a
capillary multifilament suture, meaning it consists of multiple strands
that can absorb fluids, which can be beneficial in certain surgical
contexts.
Smooth Surface: The sutures are machine-ground and
polished to yield a relatively smooth surface, resembling that of
monofilament sutures.
Sterilization
Sterilization Methods:
Ionizing Radiation: Surgical gut is typically
sterilized using ionizing radiation, which effectively kills pathogens
without denaturing the protein structure of the collagen.
Ethylene Oxide: This method can also be used for
sterilization, and it prolongs the absorption time of the suture, making
it suitable for specific applications.
Limitations of Autoclaving: Autoclaving is not suitable
for surgical gut because it denatures the protein, leading to a significant
loss of tensile strength.
Mechanism of Absorption
The absorption of surgical gut after implantation occurs through a twofold
mechanism primarily involving macrophages:
Molecular Bond Cleavage:
Acid hydrolytic and collagenolytic activities cleave the molecular
bonds in the collagen structure of the suture.
Digestion and Absorption:
Proteolytic enzymes further digest the collagen, leading to the
gradual absorption of the suture material.
Foreign Body Reaction: Due to its collagenous
composition, surgical gut stimulates a significant foreign body reaction in
the implanted tissue, which can lead to inflammation.
Rate of Absorption and Loss of Tensile Strength
Variability: The rate of absorption and loss of tensile
strength varies depending on the implantation site and the surrounding
tissue environment.
Premature Absorption: Factors that can lead to premature
absorption include:
Exposure to gastric secretions.
Presence of infection.
Highly vascularized tissues.
Conditions in protein-depleted patients.
Strength Loss Timeline:
Medium chromic gut loses about 33% of its original
strength after 7 days of implantation and about 67% after 28
days.
Types of Surgical Gut
Plain Gut:
Characteristics: Produces a severe tissue reaction
and loses tensile strength rapidly, making it less useful in surgical
applications.
Applications: Limited due to its inflammatory
response and quick absorption.
Chromic Gut:
Treatment: Treated with chromium salts to increase
tensile strength and resistance to digestion while decreasing tissue
reactivity.
Advantages: Provides a more controlled absorption
rate and is more suitable for surgical use compared to plain gut.
Handling Characteristics
Good Handling: Surgical gut generally exhibits good
handling characteristics, allowing for easy manipulation during surgical
procedures.
Weakness When Wet: It swells and weakens when wet,
which can affect knot security and overall performance during surgery.
Disadvantages
Intense Inflammatory Reaction: Surgical gut can provoke
a significant inflammatory response, which may complicate healing.
Variability in Strength Loss: The unpredictable rate of
loss of tensile strength can be a concern in surgical applications.
Capillarity: The multifilament structure can absorb
fluids, which may lead to increased tissue reaction and complications.
Sensitivity Reactions: Some patients, particularly
cats, may experience sensitivity reactions to surgical gut.
Clinical Applications
Use in Surgery: Surgical gut is used in various
surgical procedures, particularly in soft tissue closures where absorbable
sutures are preferred.
Adhesion Formation: The use of surgical gut is
generally unwarranted in situations where adhesion formation is desired due
to its inflammatory properties.
The Sphenoid Bone
Anatomy-> This is a wedge-shaped bone (G. sphen, wedge) is located anteriorly to the temporal bones.
-> It is a key bone in the cranium because it articulates with eight bones (frontal, parietal, temporal, occipital, vomer, zygomatic, palatine, and ethmoid).
-> It main parts are the body and the greater and lesser wings, which spread laterally from the body.
-> The superior surface of its body is shaped like a Turkish saddle (L. sella, a saddle); hence its name sella turcica.
-> It forms the hypophyseal fossa which contains the hypophysis cerebri or pituitary gland.
-> The sella turcica is bounded posteriorly by the dorsum sellae, a square plate of bone that projects superiorly and has a posterior clinoid process on each side.
-> Inside the body of the sphenoid bone, there are right and left sphenoid sinuses. The floor of the sella turcica forms the roof of these paranasal sinuses.
-> Studies of the sella turcica and hypophyseal fossa in radiographs or by other imaging techniques are important because they may reflect pathological changes such as a pituitary tumour or an aneurysm of the internal carotid artery. Decalcification of the dorsum sellae is one of the signs of a generalised increase in intracranial pressure.
Levels of Organization
PhysiologyLevels of Organization:
CHEMICAL LEVEL - includes all chemical substances necessary for life (see, for example, a small portion - a heme group - of a hemoglobin molecule); together form the next higher level
CELLULAR LEVEL - cells are the basic structural and functional units of the human body & there are many different types of cells (e.g., muscle, nerve, blood)
TISSUE LEVEL - a tissue is a group of cells that perform a specific function and the basic types of tissues in the human body include epithelial, muscle, nervous, and connective tissues
ORGAN LEVEL - an organ consists of 2 or more tissues that perform a particular function (e.g., heart, liver, stomach)
SYSTEM LEVEL - an association of organs that have a common function; the major systems in the human body include digestive, nervous, endocrine, circulatory, respiratory, urinary, and reproductive.
There are two types of cells that make up all living things on earth: prokaryotic and eukaryotic. Prokaryotic cells, like bacteria, have no 'nucleus', while eukaryotic cells, like those of the human body, do.
Histology of the Periodontal Ligament (PDL)
Dental Anatomy
Histology of the Periodontal Ligament (PDL)
Embryogenesis of the periodontal ligament
The PDL forms from the dental follicle shortly after root development begins
The periodontal ligament is characterized by connective tissue. The thinnest portion is at the middle third of the root. Its width decreases with age. It is a tissue with a high turnover rate.
FUNCTIONS OF PERIODONTIUM
Tooth support
Shock absorber
Sensory (vibrations appreciated in the middle ear/reflex jaw opening)
The following cells can be identified in the periodontal ligament:
a) Osteoblasts and osteoclasts b) Fibroblasts, c) Epithelial cells
Rests of Malassez
d) Macrophages
e) Undifferentiated cells
f) Cementoblasts and cementoclasts (only in pathologic conditions)
The following types of fibers are found in the PDL
-Collagen fibers: groups of fibers
-Oxytalan fibers: variant of elastic fibers, perpendicular to teeth, adjacent to capillaries
-Eluanin: variant of elastic fibers
Ground substance
PERIODONTAL LIGAMENT FIBERS
Principal fibers
These fibers connect the cementum to the alveolar crest. These are:
a. Alveolar crest group: below CE junction, downward, outward
b. Horizontal group: apical to ACG, right angle
c. Oblique group: numerous, coronally to bone, oblique direction
d. Apical group: around the apex, base of socket
e. Interradicular group: multirooted teeth
Gingival ligament fibers
This group is not strictly related to periodontium. These fibers are:
a. Dentogingival: numerous, cervical cementum to f/a gingiva
b. Alveologingival: bone to f/a gingiva
c. Circular: around neck of teeth, free gingiva
d. Dentoperiosteal: cementum to alv. process or vestibule (muscle)
e. Transseptal: cementum between adjacent teeth, over the alveolar crest
Blood supply of the PDL
The PDL gets its blood supply from perforating arteries (from the cribriform plate of the bundle bone). The small capillaries derive from the superior & inferior alveolar arteries. The blood supply is rich because the PDL has a very high turnover as a tissue. The posterior supply is more prominent than the anterior. The mandibular is more prominent than the maxillary.
Nerve supply
The nerve supply originates from the inferior or the superior alveolar nerves. The fibers enter from the apical region and lateral socket walls. The apical region contains more nerve endings (except Upper Incisors)
Dentogingival junction
This area contains the gingival sulcus. The normal depth of the sulcus is 0.5 to 3.0 mm (mean: 1.8 mm). Depth > 3.0 mm is considered pathologic. The sulcus contains the crevicular fluid
The dentogingival junction is surfaced by:
1) Gingival epithelium: stratified squamous keratinized epithelium 2) Sulcular epithelium: stratified squamous non-keratinized epithelium The lack of keratinization is probably due to inflammation and due to high turnover of this epithelium.
3) Junctional epithelium: flattened epithelial cells with widened intercellular spaces. In the epithelium one identifies neutrophils and monocytes.
Connective tissue
The connective tissue of the dentogingival junction contains inflammatory cells, especially polymorphonuclear neutrophils. These cells migrate to the sulcular and junctional epithelium.
The connective tissue that supports the sulcular epithelium is also structurally and functionally different than the connective tissue that supports the junctional epithelium.
Histology of the Col (=depression)
The col is found in the interdental gingiva. It is surfaced by epithelium that is identical to junctional epithelium. It is an important area because of the accumulation of bacteria, food debris and plaque that can cause periodontal disease.
Blood supply: periosteal vessels
Nerve supply: periodontal nerve fibers, infraorbital, palatine, lingual, mental, buccal
EMBOLISM
General Pathology
EMBOLISM
Definition: transportation of an abnormal mass of an abnormal mass of undissolved material from one part of circulation to another. The mass transported is called embolus.
Types
I .Thrombi and clots.
2. Gas or air.
3. Fat
4.Amniotic fluid.
5.Tumour
Thromboembolism
This is the commonest type of embolus and may be formed of the primary thrombus or more often of propagated clot region which is loosely attached.
Emboli from venous thrombi can result In impaction in the pulmonary arteries and result in sudden death.
Embolism from cardiac or arterial thrombi results in systemic embolism causing infraction and gangrene.
Gaseous
This occurs when gas is introduced into the circulation:
• Accidental opening of large veins during surgery.
• Mismanaged transfusion. .
As air is readily absorbed into blood only sudden introduction or large quantities of air produces effects
Caisson’s Disease bubbling of nitrogen from the blood during sudden decompression as seen during deep sea diving.
Fat Embolism
Causes
• Fractures especially of long bones and multiple
• Crush injuries.
Sites of impaction:
o Lungs.
o Systemic: causing -
→ petechial skin haemorrhages.
→ Embolism to brain leading to coma and death.
→ Conjunctival and retinal haemorrhages
Tumor Embolism.
Invasion of vascular channe1.s is a feature of malignant neoplasms and this leads to:
• Metastatic deposits,
• DlC