NEET MDS Synopsis
Valproic acid
Pharmacology
Valproic acid: broad spectrum (for most seizure types)
Mechanism: blocks Ca T currents in thalamic neurons (prevents reverberating activity in absence seizures), ↓ reactivation of Na channels (in tonic/clonic seizures; prolongs refractory periods of neurons, prevents high frequency cell firing)
Side effects: very low toxicity; common = anorexia, N/V; at high doses inhibits platelet function (bruising and gingival bleeding); rarely see idiosyncratic hepatotoxicity
Drug interactions: induces hepatic microsomal enzymes (↓ effectiveness of other drugs), binds tightly to plasma proteins so displaces other drugs
Hepatitis
General Pathology
Hepatitis
Hepatitis viruses—this group of viruses causes hepatitis, a disease affecting the liver.
1. General characteristics of hepatitis.
a. The general presentation of hepatitis is the same regardless of the infecting virus; however, the time and severity of symptoms may differ.
b. Symptoms of hepatitis include fever, anorexia, malaise, nausea, jaundice, and brown-colored urine.
c. Complications of a hepatitis infection include cirrhosis, liver failure, and hepatorenal failure.
ANTIDEPRESSANTS
Pharmacology
ANTIDEPRESSANTS
Monoamine uptake inhibitors
1. Tricyclic antidepressants (TCAs)
2. Selective serotonin reuptake inhibitors (SSRIs)
3. Serotonin-norepinephrine reuptake inhibitors(SNRIs)
4. Norepinephrine reuptake inhibitor
Monoamine oxidase inhibitors (MAOIs)
Monoamine receptor antagonists
BradyKinin
Pharmacology
BradyKinin
An endogenous vasodilator occurring in blood vessel walls.
At least two distinct receptor types, B1 and B2, appear to exist for BradyKinin
Roles of bradykinin:
1) Mediator of inflammation and pain.
2) Regulation of microcirculation.
3) Their production is interrelated with clotting and fibrinolysin systems.
4) Responsible for circulatory change after birth.
5) Involved in shock and some immune reactions.
TRIGLYCEROL
Biochemistry
TRIGLYCEROL
Triacylglycerols (formerly triglycerides) are the esters of glycerol with fatty acids. The fats and oils that are widely distributed in both plants and animals are chemically triacylglycerols.
They are insoluble in water and non-polar in character and commonly known as neutral fats.
Triacylglycerols are the most abundant dietary lipids. They are the form in which we store reduced carbon for energy. Each triacylglycerol has a glycerol backbone to which are esterified 3 fatty acids. Most triacylglycerols are "mixed." The three fatty acids differ in chain length and number of double bonds
Structures of acylglycerols :
Monoacylglycerols, diacylglycerols and triacylglycerols, respectively consisting of one, two and three molecules of fatty acids esterified to
a molecule of glycerol
Lipases hydrolyze triacylglycerols, releasing one fatty acid at a time, producing diacylglycerols, and eventually glycerol
Glycerol arising from hydrolysis of triacylglycerols is converted to the Glycolysis intermediate dihydroxyacetone phosphate, by reactions catalyzed by:
(1) Glycerol Kinase
(2) Glycerol Phosphate Dehydrogenase
Free fatty acids, which in solution have detergent properties, are transported in the blood bound to albumin, a serum protein produced by the liver.
Several proteins have been identified that facilitate transport of long chain fatty acids into cells, including the plasma membrane protein CD36
The Eye and Orbit
AnatomyThe Eye and Orbit
The orbit (eye socket) appears as a bony recess in the skull when it is viewed from anteriorly.
It almost surrounds the eye and their associated muscles, nerves and vessels, together with the lacrimal apparatus.
The orbit is shaped somewhat like a four-side pyramid lying on its side, with its apex pointing posteriorly and its base anteriorly.
Osteomyelitis of the Jaw (OML)
Oral and Maxillofacial SurgeryOsteomyelitis of the Jaw (OML)
Osteomyelitis of the jaw (OML) is a serious infection of the bone that can
lead to significant morbidity if not properly diagnosed and treated.
Understanding the etiology and microbiological profile of OML is crucial for
effective management. Here’s a detailed overview based on the information
provided.
Historical Perspective on Etiology
Traditional View: In the past, the etiology of OML was
primarily associated with skin surface bacteria, particularly Staphylococcus
aureus. Other bacteria, such as Staphylococcus epidermidis and
hemolytic streptococci, were also implicated.
Reevaluation: Recent findings indicate that S.
aureus is not the primary pathogen in cases of OML affecting
tooth-bearing bone. This shift in understanding highlights the complexity of
the microbial landscape in jaw infections.
Microbiological Profile
Common Pathogens:
Aerobic Streptococci:
α-Hemolytic Streptococci: Particularly Streptococcus
viridans, which are part of the normal oral flora and can
become pathogenic under certain conditions.
Anaerobic Streptococci: These bacteria thrive in
low-oxygen environments and are significant contributors to OML.
Other Anaerobes:
Peptostreptococcus: A genus of anaerobic
bacteria commonly found in the oral cavity.
Fusobacterium: Another group of anaerobic
bacteria that can be involved in polymicrobial infections.
Bacteroides: These bacteria are also part of
the normal flora but can cause infections when the balance is
disrupted.
Additional Organisms:
Gram-Negative Organisms:
Klebsiella, Pseudomonas, and Proteus species
may also be isolated in some cases, particularly in chronic or
complicated infections.
Specific Pathogens:
Mycobacterium tuberculosis: Can cause
osteomyelitis in the jaw, particularly in immunocompromised
individuals.
Treponema pallidum: The causative agent of
syphilis, which can lead to specific forms of osteomyelitis.
Actinomyces species: Known for causing
actinomycosis, these bacteria can also be involved in jaw
infections.
Polymicrobial Nature of OML
Polymicrobial Disease: Established acute OML is
typically a polymicrobial infection, meaning it involves multiple types of
bacteria. The common bacterial constituents include:
Streptococci (both aerobic and anaerobic)
Bacteroides
Peptostreptococci
Fusobacteria
Other opportunistic bacteria that may contribute to the infection.
Clinical Implications
Sinus Tract Cultures: Cultures obtained from sinus
tracts in the jaw may often be misleading. They can be contaminated with
skin flora, such as Staphylococcus species, which do not accurately
represent the pathogens responsible for the underlying osteomyelitis.
Diagnosis and Treatment: Understanding the
polymicrobial nature of OML is essential for effective diagnosis and
treatment. Empirical antibiotic therapy should consider the range of
potential pathogens, and cultures should be interpreted with caution.
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.