NEET MDS Synopsis
Cholangitis
General Pathology
Cholangitis
Cholangitis is inflammation of the bile ducts.
1. It is usually associated with biliary duct obstruction by gallstones or carcinoma, which leads to infection with enteric organisms. This results in purulent exudation within the bile ducts and bile stasis.
2. Clinically, cholangitis presents with jaundice, fever, chills. leukocytosis, and right upper quadrant pain
Microscopic structure
Anatomy
Cartilage model is covered with perichondrium that is converted to periosteum
Diaphysis-central shaft
Epiphysis-located at either end of the diaphysis
Growth in length of the bone is provided by the emetaphyseal plate located between the epiphyseal cartilage and the diaphysis
Blood capillaries and the mesenchymal cells infiltrate the spaces left by the destroyed chondrocytes
Osteoblasts are derived from the undifferentiated cells; form an osseous matrix in the cartilage
Bone appears at the site where there was cartilage
Microscopic structure
Compact bone is found on the exterior of all bones; canceIlous bone is found in the interior
Surface of compact bone is covered by periosteum that is attached by Sharpey's fibers
Blood vessels enter the periosteum via Volkmann's canals and then enter the haversian canals that are formed by the canaliculi and lacunae
Marrow
FiIls spaces of spongy bone
Contains blood vessels and blood ceIls in various stages of development
Types
Red bone marrow
Formation of red blood ceIls (RBCs) and some white blood cells (WBCs) in this location
Predominate type of marrow in newborn
Found in spongy bone of adults (sternum, ribs, vertebrae, and proximal epiphyses of long bones)
Yellow bone marrow
Fatty marrow
Generally replaces red bone marrow in the adult, except in areas mentioned above
Ossification is completed as the proximal epiphysis joins with the diaphysis between the twentieth and twenty-fifth year
MAXILLARY SECOND MOLAR
Dental Anatomy
MAXILLARY SECOND MOLAR
The second molars are often called 12-year molars because they erupt when a child is about 12 years
Facial: The crown is shorter occluso-cervically and narrower mesiodistally whe compared to the first molar. The distobuccal cusp is visibly smaller than the mesiobuccal cusp. The two buccal roots are more nearly parallel. The roots are more parallel; the apex of the mesial root is on line with the with the buccal developmental groove. Mesial and distal roots tend to be about the same length.
Lingual: The distolingual cusp is smaller than the mesiolingual cusp. The Carabelli trait is absent.
Proximal: The crown is shorter than the first molar and the palatal root has less diverence. The roots tend to remain within the crown profile.
Occlusal: The distolingual cusp is smaller on the second than on the first molar. When it is much reduced in size, the crown outline is described as 'heart-shaped.' The Carabelli trait is usually absent. The order of cusp size, largest to smallest, is the same as the first but is more exaggerated: mesiolingual, mesiobuccal, distobuccal, and distolingual.
Contact Points; Height of Curvature: Both mesial and distal contacts tend to be centered buccolingually below the marginal ridges. Since themolars become shorter, moving from first to this molar, the contacts tend to appear more toward the center of the proximal surfaces.
Roots: There are three roots, two buccal and one lingual. The roots are less divergent than the first with their apices usually falling within the crown profile. The buccal roots tend to incline to the distal.
Note: The distolingual cusp is the most variable feature of this tooth. When it is large, the occlusal is somewhat rhomboidal; when reduced in size the crown is described as triangual or 'heart-shaped.' At times, the root may be fused.
Cephalometric Landmarks
OrthodonticsKey Cephalometric Landmarks
Sella (S):
The midpoint of the sella turcica, a bony structure located at the
base of the skull. It serves as a central reference point in
cephalometric analysis.
Nasion (N):
The junction of the frontal and nasal bones, located at the bridge
of the nose. It is often used as a reference point for the anterior
cranial base.
A Point (A):
The deepest point on the maxillary arch, located between the
anterior nasal spine and the maxillary alveolar process. It is crucial
for assessing maxillary position.
B Point (B):
The deepest point on the mandibular arch, located between the
anterior nasal spine and the mandibular alveolar process. It is
important for evaluating mandibular position.
Pogonion (Pog):
The most anterior point on the contour of the chin. It is used to
assess the position of the mandible in relation to the maxilla.
Gnathion (Gn):
The midpoint between Menton and Pogonion, representing the most
inferior point of the mandible. It is used in various angular
measurements.
Menton (Me):
The lowest point on the symphysis of the mandible. It is used as a
reference for vertical measurements.
Go (Gonion):
The midpoint of the contour of the ramus and the body of the
mandible. It is used to assess the angle of the mandible.
Frankfort Horizontal Plane (FH):
A plane defined by the points of the external auditory meatus (EAM)
and the lowest point of the orbit (Orbitale). It is used as a reference
plane for various measurements.
Orbitale (Or):
The lowest point on the inferior margin of the orbit (eye socket).
It is used in conjunction with the EAM to define the Frankfort
Horizontal Plane.
Ectocanthion (Ec):
The outer canthus of the eye, used in facial measurements and
assessments.
Endocanthion (En):
The inner canthus of the eye, also used in facial measurements.
Alveolar Points:
Points on the alveolar ridge of the maxilla and mandible, often used
to assess the position of the teeth.
Importance of Cephalometric Landmarks
Diagnosis: These landmarks help orthodontists diagnose
skeletal and dental discrepancies, such as Class I, II, or III
malocclusions.
Treatment Planning: By understanding the relationships
between these landmarks, orthodontists can develop effective treatment plans
tailored to the individual patient's needs.
Monitoring Progress: Cephalometric landmarks allow for
the comparison of pre-treatment and post-treatment radiographs, helping to
evaluate the effectiveness of orthodontic interventions.
Research and Education: These landmarks are essential
in orthodontic research and education, providing a standardized method for
analyzing craniofacial morphology.
Lithium carbonate
Pharmacology
Lithium carbonate: 1st choice (controls mania in bipolar disorders); delay before onset of therapeutic benefit; no psychotropic effects in normal humans
i. Mechanism: blocks enzymes in inositol phosphate signaling pathway; no consistent effects of lithium on NE, 5-HT, and DA
ii. Side effects: severe CNS (ataxia, delirium, coma, convulsions) and CV (cardiac dysrhythmias)
Selective serotonin reuptake inhibitors
Pharmacology
Selective serotonin reuptake inhibitors (SSRIs)
e.g. fluoxetine, paroxetine, citalopram, and sertraline
- Most commonly used antidepressant category
- Less likely to cause anticholinergic side effects
- Relatively safest antidepressant group in overdose
- Selectively inhibits reuptake of serotonin(5-HT)
Mode of Action;
- Well absorbed when given orally
- Plasma half-lives of 18-24 h allowing once daily dosagedaily dosage
- Metabolised through CYP450 system and most SSRIs inhibit some CYP isoforms
- Therapeutic effect is delayed for 2-4 weeks
ADVERSE DRUG REACTIONS
- Insomnia, increased anxiety, irritability
- Decreased libido
- Erectile dysfunction, anorgasmia, and ejaculatory delay
- Bleeding disorders
- Withdrawal syndrome
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.
Bacterial infectious diseases
General Medicine
Bacterial infectious diseases
Anthrax
- an acute infectious disease caused by the bacteria Bacillus anthracis
- Anthrax can enter the human body through the intestines (ingestion), lungs (inhalation), or skin (cutaneous).
1. Pulmonary (pneumonic, respiratory, or inhalation) anthrax
Respiratory infection initially presents with cold or flu-like symptoms for several days, followed by severe (and often fatal) respiratory collapse.
A lethal dose of anthrax is reported to result from inhalation of 10,000-20,000 spores. This form of the disease is also known as Woolsorters' disease or as Ragpickers' disease.
2. Gastrointestinal (gastroenteric) anthrax
Gastrointestinal infection often presents with serious gastrointestinal difficulty, vomiting of blood, and severe diarrhea. Untreated intestinal infections result in 25-65% mortality.
3. Cutaneous (skin) anthrax
Cutaneous infection often presents with large, painless necrotic ulcers (beginning as an irritating and itchy skin lesion or blister that is dark and usually concentrated as a black dot, somewhat resembling bread mold) at the site of infection.
Treatment
- large doses of intravenous and oral antibiotics, such as penicillin, ciprofloxacin, doxycycline, erythromycin, and vancomycin.
- Antibiotic prophylaxis is crucial in cases of pulmonary anthrax to prevent death.
Cholera
- a water-borne disease caused by the bacterium Vibrio cholerae, which are typically ingested by drinking contaminated water, or by eating improperly cooked fish, especially shellfish.
Symptoms
- general GI tract upset: profuse diarrhea (eg 1L/hour), abdominal cramping, fever, nausea and vomiting.
- Dehydration
- severe metabolic acidosis with potassium depletion, anuria, circulatory collapse and cyanosis
- Death is through circulatory volume shock (massive loss of fluid and electrolytes)
Treatment
- rehydration and replacement of electrolytes
- Tetracycline antibiotics may have a role in reducing the duration and severity of cholera
Diphtheria
- Diphtheria is an upper respiratory tract illness characterized by sore throat, low-grade fever, and an adherent membrane (a pseudomembrane) on the tonsil(s), pharynx, and/or nose
Signs and symptoms
- Incubation time of 1-4 days
- Symptoms include fatigue, fever, a mild sore throat and problems swallowing
- Children infected have symptoms that include nausea, vomiting, chills, and a high fever,
Treatment
- Antibiotics are used in patients or carriers to eradicate C. diphtheriae and prevent its transmission to others
- Erythromycin (orally or by injection) for 14 days (40 mg/kg per day with a maximum of 2 g/d), or
- Procaine penicillin G given intramuscularly for 14 days (300,000 U/d for patients weighing <10 kg and 600,000 U/d for those weighing >10 kg).
- Patients with allergies to penicillin G or erythromycin can use rifampin or clindamycin.
- In more severe cases lymph nodes in the neck may swell, and breathing and swallowing will be more difficult throat may require intubation or a tracheotomy
Pertussis
- Pertussis, also known as "whooping cough", is a highly contagious disease caused by certain species of the bacterium Bordetella—usually B. pertussis
- The disease is characterized initially by mild respiratory infections symptoms such as cough, sneezing, and runny nose (catarrhal stage).
- After one to two weeks the cough changes character, with paroxysms of coughing followed by an inspiratory "whooping" sound (paroxysmal stage)
- Other complications of the disease include pneumonia, encephalitis, pulmonary hypertension, and secondary bacterial superinfection.
- The disease is spread by contact with airborne discharges from the mucous membranes of infected people.
- Laboratory diagnosis include; Calcium alginate throat swab, culture on Bordet-Gengou medium, immunofluorescence and serological methods.
-Treatment of the disease with antibiotics (often erythromycin, azithromycin, clarithromycin or trimethoprim-sulfamethoxazole)
- Vaccination in children as preventive measure . The immunizations are often given in combination with tetanus and diphtheria immunizations, at ages 2, 4, and 6 months, and later at 15–18 months and 4–6 years
Tetanus
Tetanus is a serious and often fatal disease caused by the neurotoxin tetanospasmin which is produced by the Gram-positive, obligate anaerobic bacterium Clostridium tetani.
Symptoms
-The incubation period for tetanus is 3 days to as long as 15 weeks
- For neonates, the incubation period is 4 to 14 days, with 7 days being the average
- The first sign of tetanus is a mild jaw muscle spasm called lockjaw (trismus), followed by stiffness of the neck and back, risus sardonicus, difficulty swallowing, and muscle rigidity in the abdomen.
- Typical signs of tetanus include an increase in body temperature by 2 to 4°C, diaphoresis (excessive sweating), an elevated blood pressure, and an episodic rapid heart rate
Treatment
- Penicillin and metronidazole
- Human anti-tetanospasmin immunoglobulin should be given.
- Diazepam and DPT vaccine booster are also given
Syphilis
- a sexually transmitted disease (STD) that is caused by a spirochaete bacterium, Treponema pallidum
- The route of transmission for syphilis is almost invariably by sexual contact
Stages of syphilis
1.Primary syphilis
Chancres on penis due to primary syphilitic infection
Primary syphilis is manifested after an incubation period of 10-90 days (the average is 21 days) with a primary sore.
During the initial incubation period, individuals are asymptomatic.
The sore, called a chancre, is a firm, painless skin ulceration localized at the point of initial exposure to the bacterium, often on the penis, vagina or rectum.
Local lymph node swelling can occur. The primary lesion may persist for 4 to 6 weeks and then heal spontaneously.
2. Secondary syphilis
characterized by a skin rash that appears 1-6 months (commonly 6 to 8 weeks) after the primary infection
This is a symmetrical reddish-pink non-itchy rash on the trunk and extremities , nvolves the palms of the hands and the soles of the feet
in moist areas of the body the rash becomes flat broad whitish lesions called condylomata lata. Mucous patches may also appear on the genitals or in the mouth
common other symptoms include fever, sore throat, malaise, weight loss, headache, meningismus, and enlarged lymph nodes
3. Tertiary syphilis
occurs from as early as one year after the initial infection but can take up to ten years to manifest
This stage is characterised by gummas, soft, tumor-like growths, readily seen in the skin and mucous membranes, but which can occur almost anywhere in the body, often in the skeleton
Other characteristics of untreated syphilis include Charcot's joints (joint deformity),
Clutton's joints (bilateral knee effusions).
The more severe manifestations include neurosyphilis and cardiovascular syphilis.
Cardiovascular complications include aortic aortitis, aortic aneurysm, aneurysm of sinus of Valsalva, and aortic regurgitation, and are a frequent cause of death
Syphilitic aortitis can cause de Musset's sign
4.Congenital syphilis
Congenital syphilis is syphilis present in utero and at birth, and occurs when a child is born to a mother with secondary or tertiary syphilis.
Manifestations of congenital syphilis include abnormal x-rays; Hutchinson's teeth (centrally notched, widely-spaced peg-shaped upper central incisors);
mulberry molars (sixth year molars with multiple poorly developed cusps);
frontal bossing; saddle nose; poorly developed maxillae; enlarged liver; enlarged spleen; petechiae;
other skin rash; anemia; lymph node enlargement; jaundice; pseudoparalysis; and snuffles, the name given to rhinitis in this situation.
Rhagades, linear scars at the angles of the mouth and nose result from bacterial infection of skin lesions.
Death from congenital syphilis is usually through pulmonary hemorrhage.
Diagnosis
First effective test for syphilis, the Wassermann test
Rapid Plasma Reagin (RPR) and Venereal Disease Research Laboratory (VDRL) test are not as effective
Newer tests based on monoclonal antibodies and immunofluorescence, including Treponema pallidum haemagglutination assay (TPHA) and Fluorescent Treponemal Antibody Absorption (FTA-ABS) are more specific, but are still unable to rule out non-syphillis Treponomal infections such as Yaws and Pinta.
Microscopy of chancre fluid using dark ground illumination can be extremely quick and effective.
Treatment
first choice treatment for syphilis remains penicillin, in the form of benzathine penicillin G or aqueous procaine penicillin G injections
oral tetracyclines. In patients allergic to penicillins
Typhoid fever
- Typhoid fever (Enteric fever) is an illness caused by the bacterium Salmonella typhi
Symptoms
After infection, symptoms include:
a high fever from 39 °C to 40 °C (103 °F to 104 °F) that rises slowly
chills
bradycardia (slow heart rate)
weakness
diarrhea
headaches
myalgia (muscle pain)
lack of appetite
constipation
stomach pains
in some cases, a rash of flat, rose-colored spots called "rose spots"
extreme symptoms such as intestinal perforation or hemorrhage, delusions and confusion are also possible.
Diagnosis
Widal test (demonstration of salmonella antibodies against antigens O-somatic and H-flagellar)
Treatment
Antibiotics, such as ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, and ciprofloxacin, are commonly used to treat typhoid fever in developed countries
Usage of Ofloxacin along with Lactobacillus acidophilus is also recommended.