NEET MDS Shorts
14282
INI CET
The enteric nervous system plexuses receive input from both sympathetic and parasympathetic divisions.
94525
Dental MaterialsPolycarboxylate cement is a luting agent that provides adhesion to calcified dental tissues
56184
Microbiology
The biologic standard used to test the efficiency of sterilization typically
involves the use of spores of a harmless bacillus. This method is widely
recognized in the scientific community and is based on the principle that if a
sterilization process can effectively destroy the most heat-resistant
microorganisms, it is assumed to be capable of killing all other less resistant
microbes.
The choice of using spores of a harmless bacillus is rooted in the fact that
bacterial spores are the most heat-resistant forms of microbial life. Spores are
metabolically inactive, which makes them very hardy and capable of surviving in
adverse environmental conditions for extended periods. For sterilization
validation, scientists often employ a biological indicator that contains spores
of a known heat-resistant bacterium, such as Geobacillus stearothermophilus
(formerly Bacillus stearothermophilus) or Bacillus subtilis. These organisms are
chosen because they have well-characterized resistance profiles, and their
destruction indicates that the sterilization process has achieved the necessary
lethality to eradicate all microbial life forms, including vegetative bacteria,
fungi, and viruses.
Let's examine the other options provided:
1. Spores of Clostridium tetani: While C. tetani is a spore-forming bacterium,
its spores are not commonly used as a biological indicator for sterilization
efficiency. C. tetani is a pathogen that causes tetanus, a serious disease.
However, it is not typically used for this purpose because there are safer and
more universally accepted biological indicators available.
2. Streptococcus pneumoniae: S. pneumoniae is a bacterium that can cause
pneumonia and other infections, but it is not a spore-former. Moreover, it is
generally less resistant to heat and sterilization methods compared to
spore-forming bacteria. Thus, it is not suitable as a standard for testing
sterilization efficiency.
3. Spores of a harmless bacillus: As previously mentioned, this is the most
appropriate choice for a biologic standard in sterilization testing. These
spores serve as reliable and safe indicators of sterilization efficacy because
they mimic the resistance of pathogenic spores without posing the actual risk of
infection.
4. Infectious hepatitis virus: While viruses can be highly resistant to some
sterilization methods, they are generally more sensitive to heat than bacterial
spores. Moreover, using infectious viruses as biological indicators poses
significant biosafety risks and is not a standard practice in routine
sterilization testing. For viral resistance testing, specific viruses or
virus-like particles may be used, but these are not typically employed as the
primary biological indicators for sterilization validation due to the complexity
and high containment requirements of such testing.
63896
PedodonticsPostural position does not affect occlusal adjustment.
28324
Radiology
Talon cusp (TC) and dens in dente (DiD) are both developmental anomalies of
the teeth, but they differ in their formation and appearance. A talon cusp
arises from the palatal or lingual aspect of an incisor tooth, typically in the
maxillary central or lateral incisors. It is composed of enamel and dentin, and
its shape can vary from a mild bulge to a fully formed cusp that extends to the
incisal edge of the tooth. It can be mistaken for a supernumerary tooth on
radiographs due to its pointed projection and density.
In contrast, dens in dente is a condition where a tooth has an invagination in
its crown that contains a smaller tooth-like structure, known as the "dental
lamina," which is enclosed within it. This invagination is usually filled with
pulp tissue and dentin, and the internal structure resembles a tooth within a
tooth. The smaller structure within the affected tooth can mimic a supernumerary
tooth on radiographs, but it is not a separate tooth.
74255
Dental Materials
Epoxy resins
· Abrasion resistance is many times greater than gypsum
· More expensive
· Undergoes 0.1 – 0.2% shrinkage, thus their shrinkage is approximately equal to gypsum. This is less of problem with newer formulations & polyurethane resin.
· Their detail reproduction is better.
· Hydrocolloids, polysulfides are not compatible with them.
85206
PhysiologySpermatogenesis is the process of sperm cell development. It takes place in the seminiferous tubules within the testes. These tubules are lined with spermatogonia, which mature into primary spermatocytes, then secondary spermatocytes, and finally into spermatids, which mature into spermatozoa.
41205
PharmacologyCarbamazepine is the primary and most effective medication used to treat trigeminal neuralgia. It is an anticonvulsant drug that works by reducing nerve impulses that cause pain.
26897
Conservative DentistryThe discoloration of amalgam restorations is often due to the formation of silver sulfide on the surface, which can occur due to the reaction of silver with sulfur compounds in the oral environment. The gamma I phase is a strong component of amalgam, while the gamma II phase is weaker and less stable. Oxides can form as well, but sulfides are more directly associated with the discoloration observed in clinical settings.
44729
NEETMDS
Fexofenadine is the active metabolite of terfenadine that does not block delayed rectifier K channels in the heart and does not prolong QTc interval. It is free of arrhythmogenic potential, does not cross the blood-brain barrier, and does not produce sedation. It has a plasma half-life of 11-16 hrs and duration of action 24 hrs.