NEET MDS Synopsis
Aminoglycoside
Pharmacology
Aminoglycoside
Aminoglycosides are a group of antibiotics that are effective against certain types of bacteria. They include amikacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, streptomycin, and tobramycin. Those which are derived from Streptomyces species
Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth.
Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Streptomycin was the first effective drug in the treatment of tuberculosis, though the role of aminoglycosides such as streptomycin and amikacin have been eclipsed (because of their toxicity and inconvenient route of administration) except for multiple drug resistant strains.
Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis.
Because of their potential for ototoxicity and renal toxicity, aminoglycosides are administered in doses based on body weight. Blood drug levels and creatinine are monitored during the course of therapy.
There is no oral form of these antibiotics: they are generally administered intravenously, though some are used in topical preparations used on wounds.
Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses.
Classification of Cementum
Dental Anatomy
Classification of Cementum
Embryologically
Primary and secondary
2. According to cellular component
Acellular: Thin, Amorphous, First layer to seal the dentin tubules
Cellular: Thick, Better structure, Apical surface
Layers of cellular and acellular cementum alternate (randomly)
3. Based on the origin of the collagenous matrix
Extrinsic
Intrinsic
Mixed
4. Combined classification
a. Primary acellular intinsic fiber cementum
b. Primary acellualar extrinsic fiber cementum
c. Secondary cellular intrinsic fiber cementum
d. Secondary cellular mixed fiber cementum
e. Acellular afibrillar cementum
5. Depending on the location and patterning
Intermediate and mixed stratified cementum
Participating Cells
Cementoblasts
Active
Cells are round, plump with basophilic cytoplasm (rough endoplasmic reticulum)
Inactive
Cells have little cytoplasm
Cementocytes
Cementocyte lacuna
cementocyte canaliculus
Cells have fewer organelles compared to cementoblasts. They are found in lacunae and have numerous processes toward the periodontal ligament. Eventually they die due to avascularity
Cementicles
a) free
b) attached
c) embedded
Time for tooth development
Dental Anatomy
Time for tooth development
Entire primary dentition initiated between 6 and 8 weeks of embryonic development.
Successional permanent teeth initiated between 20th week in utero and 10th month after birth Permanent molars between 20th week in utero (first molar) and 5th year of life (third molar)
Gastric acid secretion inhibitors
Pharmacology
Gastric acid secretion inhibitors (antisecretory drugs):
HCl is secreted by parietal cells of the gastric mucosa which contain receptors for acetylcholine (muscarinic receptors: MR), histamine (H2R), prostaglandins (PGR) and gastrin (GR) that stimulate the production, except PGs which inhibit gastric acid production.
Therefore, antagonists of acetylcholine, histamine and gastrin inhibit gastric acid secretion (antisecretory). On the other hand, inhibitors of PGs biosynthesis such as NSAIDs with reduce cytoprotective mechanisms and thus promote gastric mucosal erosion. Also, the last step in gastric acid secretion from parietal cells involve a pump called H+ -K+-ATPase (proton pump). Drugs that block this pump will inhibit gastric acid secretion. Antisecretory drugs include:
1. Anticholinergic agents such as pirenzepine, dicyclomine, atropine.
2. H2-receptors blocking agents such as Cimetidine, Ranitidine, Famotidine, Nizatidine (the pharmacology of these agents has been discussed previously).
3. Gastrin-receptor blockers such as proglumide.
4. Proton pump inhibitors such as omeprazole, lansoprazole.
Major clinical indications of antisecretory drugs:
• Prevention & treatment of peptic ulcer disease.
• Zollinger Ellison syndrome.
• Reflux esophagitis.
Fluid Resuscitation in Emergency Care
Oral and Maxillofacial SurgeryFluid Resuscitation in Emergency Care
Fluid resuscitation is a critical component of managing patients in shock,
particularly in cases of hypovolemic shock due to trauma, hemorrhage, or severe
dehydration. The goal of fluid resuscitation is to restore intravascular volume,
improve tissue perfusion, and stabilize vital signs. Below is an overview of the
principles and protocols for fluid resuscitation.
Initial Fluid Resuscitation
Bolus Administration:
Adults: Initiate fluid resuscitation with a 1000
mL bolus of Ringer's Lactate (RL) or normal saline.
Children: Administer a 20 mL/kg bolus of
RL or normal saline, recognizing that children may require more careful
dosing based on their size and clinical condition.
Monitoring Response:
After the initial bolus, monitor the patient’s response to therapy
using clinical indicators, including:
Blood Pressure: Assess for improvements in
systolic and diastolic blood pressure.
Skin Perfusion: Evaluate capillary refill time,
skin temperature, and color.
Urinary Output: Monitor urine output as an
indicator of renal perfusion; a urine output of at least 0.5
mL/kg/hour is generally considered adequate.
Mental Status: Observe for changes in
consciousness, alertness, and overall mental status.
Further Resuscitation Steps
Second Bolus:
If there is no transient response to the initial bolus (i.e., no
improvement in blood pressure, skin perfusion, urinary output, or mental
status), administer a second bolus of fluid (1000 mL
for adults or 20 mL/kg for children).
Assessment of Ongoing Needs:
If ongoing resuscitation is required after two boluses, it is likely
that the patient may need transfusion of blood
products. This is particularly true in cases of significant hemorrhage
or when there is evidence of inadequate perfusion despite adequate fluid
resuscitation.
Transfusion Considerations:
Indications for Transfusion: Consider transfusion
if the patient exhibits signs of severe anemia, persistent hypotension,
or ongoing blood loss.
Type of Transfusion: Depending on the clinical
scenario, packed red blood cells (PRBCs), fresh frozen plasma (FFP), or
platelets may be indicated.
Management of Skin Loss in the Face
Oral and Maxillofacial SurgeryManagement of Skin Loss in the Face
Skin loss in the face can be a challenging condition to manage, particularly
when it involves critical areas such as the lips and eyelids. The initial
assessment of skin loss may be misleading, as retraction of skin due to
underlying muscle tension can create the appearance of tissue loss. However,
when significant skin loss is present, it is essential to address the issue
promptly and effectively to prevent complications and promote optimal healing.
Principles of Management
Assessment Under Anesthesia: A thorough examination
under anesthesia is necessary to accurately assess the extent of skin loss
and plan the most suitable repair strategy.
No Healing by Granulation: Unlike other areas of the
body, wounds on the face should not be allowed to heal by granulation. This
approach can lead to unacceptable scarring, contracture, and functional
impairment.
Repair Options: The following options are available for
repairing skin loss in the face:
Skin Grafting: This involves transferring a piece
of skin from a donor site to the affected area. Skin grafting can be
used for small to moderate-sized defects.
Local Flaps: Local flaps involve transferring
tissue from an adjacent area to the defect site. This approach is useful
for larger defects and can provide better color and texture match.
Apposition of Skin to Mucosa: In some cases, it may
be possible to appose skin to mucosa, particularly in areas where the
skin and mucosa are closely approximated.
Types of skin grafts:
Split-thickness skin graft (STSG):The most common type, where only the epidermis
and a thin layer of dermis are harvested.
Full-thickness skin graft (FTSG):Includes the entire thickness of the skin,
typically used for smaller areas where cosmetic appearance is crucial.
Epidermal skin graft (ESG):Only the outermost layer of the epidermis is
harvested, often used for smaller wounds.
Considerations for Repair
Aesthetic Considerations: The face is a highly visible
area, and any repair should aim to restore optimal aesthetic appearance.
This may involve careful planning and execution of the repair to minimize
scarring and ensure a natural-looking outcome.
Functional Considerations: In addition to aesthetic
concerns, functional considerations are also crucial. The repair should aim
to restore normal function to the affected area, particularly in critical
areas such as the lips and eyelids.
Timing of Repair: The timing of repair is also
important. In general, early repair is preferred to minimize the risk of
complications and promote optimal healing.
Codeine
Pharmacology
Codeine
Codeine is methyl morphine, with a methyl substitution on the phenolic hydroxyl group of morphine. It is more lipophilic than morphine and thus crosses the blood–brain barrier faster.
classified as a simple, or mild analgesic, codeine is often used in low doses as an oral analgesic has a much better oral/parenteral absorption ratio than morphine.
Effective for mild to moderate pain.
Constipation occurs
Dizziness may occur in ambulatory patients.
More potent histamine-releasing action than does morphine.
Should not be administered by IV injection.
Extremely effective antitussive agent and is used therapeutically for suppressing cough.
In contrast to morphine, codeine overdose can occasionally lead to the production of seizures.
Seizures can be treated with barbiturates.
Respiratory depression can be counteracted with Naloxone.
orally, 30 mg of codeine is equi-analgesic to 600 mg of aspirin, however, the effects of the two are additive, and occasionally synergistic
Fifth Generation:
Pharmacology
Fifth Generation:
These are extended spectrum antibiotics.
Ceftaroline, Ceftobiprole