NEET MDS Synopsis
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.
Human tooth development - Permanent
Dental Anatomy
Maxillary (upper) teeth
Permanent teeth
Central
incisor
Lateral
incisor
Canine
First
premolar
Second
premolar
First
molar
Second
molar
Third
molar
Initial calcification
3–4 mo
10–12 mo
4–5 mo
1.5–1.75 yr
2–2.25 yr
at birth
2.5–3 yr
7–9 yr
Crown completed
4–5 yr
4–5 yr
6–7 yr
5–6 yr
6–7 yr
2.5–3 yr
7–8 yr
12–16 yr
Root completed
10 yr
11 yr
13–15 yr
12–13 yr
12–14 yr
9–10 yr
14–16 yr
18–25 yr
Mandibular (lower) teeth
Initial calcification
3–4 mo
3–4 mo
4–5 mo
1.5–2 yr
2.25–2.5 yr
at birth
2.5–3 yr
8–10 yr
Crown completed
4–5 yr
4–5 yr
6–7 yr
5–6 yr
6–7 yr
2.5–3 yr
7–8 yr
12–16 yr
Root completed
9 yr
10 yr
12–14 yr
12–13 yr
13–14 yr
9–10 yr
14–15 yr
18–25 yr
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
Classification
Pharmacology
Classification
1. Natural Alkaloids of Opium
Phenanthrenes -> morphine, codeine, thebaine
Benzylisoquinolines -> papaverine, noscapine
2. Semi-synthetic Derivatives
diacetylmorphine (heroin) hydromorphone, oxymorphone hydrocodone, oxycodone
3. Synthetic Derivatives
phenylpiperidines pethidine, fentanyl, alfentanyl, sufentnyl
benzmorphans pentazocine, phenazocine, cyclazocine
propionanilides methadone
morphinans levorphanol
HERPES ZOSTER (Shingles)
General Pathology
HERPES ZOSTER (Shingles)
An infection with varicella-zoster virus primarily involving the dorsal root ganglia and characterized by vesicular eruption and neuralgic pain in the dermatome of the affected root ganglia.
caused by varicella-zoster virus
Symptoms and Signs
Pain along the site of the future eruption usually precedes the rash by 2 to 3 days. Characteristic crops of vesicles on an erythematous base then appear, following the cutaneous distribution of one or more adjacent dermatomes
Eruptions occur most often in the thoracic or lumbar region and are unilateral. Lesions usually continue to form for about 3 to 5 days
Geniculate zoster (Ramsay Hunt's syndrome) results from involvement of the geniculate ganglion. Pain in the ear and facial paralysis occur on the involved side. A vesicular eruption occurs in the external auditory canal, and taste may be lost in the anterior two thirds of the tongue
Stimulants
Pharmacology
Stimulants:
Amphetamines: amphetamine is a substrate of serotonin and NE uptake transporters so in cytoplasm, it competes for transport into storage vesicles → ↑ [ ] in cytoplasm then excess amines bind to membrane transporter and are transported out of cell
Drugs:
a. Dextroamphetamine: psychomotor stimulant (↓ fatigue), short-term weight loss, prevents narcolepsy
b. Methylphenidate (Ritalin): prevents narcolepsy, treatment for ADD and ADHD
c. Methamphetamine: psychomotor stimulant, abused widely (cheap, easy to make)
Side effects:
a. CNS: euphoria, anxiety, agitation, delirium, paranoia, panic, suicidal/homicidal impulses, psychoses, tolerance (develops rapidly to most CNS effects), physical dependence (not clinically relevant)
b. CV: headache, chills, arrhythmias and HTN (may be fatal)
Reflexes
PhysiologyReflexes
A reflex is a direct connection between stimulus and response, which does not require conscious thought. There are voluntary and involuntary reflexes.
The Stretch Reflex:
The stretch reflex in its simplest form involves only 2 neurons, and is therefore sometimes called a 2-neuron reflex. The two neurons are a sensory and a motor neuron. The sensory neuron is stimulated by stretch (extension) of a muscle. Stretch of a muscle normally happens when its antagonist contracts, or artificially when its tendon is stretched, as in the knee jerk reflex. Muscles contain receptors called muscle spindles. These receptors respond to the muscles's stretch. They send stimuli back to the spinal cord through a sensory neuron which connects directly to a motor neuron serving the same muscle. This causes the muscle to contract, reversing the stretch. The stretch reflex is important in helping to coordinate normal movements in which antagonistic muscles are contracted and relaxed in sequence, and in keeping the muscle from overstretching.
Since at the time of the muscle stretch its antagonist was contracting, in order to avoid damage it must be inhibited or tuned off in the reflex. So an additional connection through an interneuron sends an inhibitory pathway to the antagonist of the stretched muscle - this is called reciprocal inhibition.
The Deep Tendon Reflex:
Tendon receptors respond to the contraction of a muscle. Their function, like that of stretch reflexes, is the coordination of muscles and body movements. The deep tendon reflex involves sensory neurons, interneurons, and motor neurons. The response reverses the original stimulus therefore causing relaxation of the muscle stimulated. In order to facilitate that the reflex sends excitatory stimuli to the antagonists causing them to contract - reciprocal activation.
The stretch and tendon reflexes complement one another. When one muscle is stretching and stimulating the stretch reflex, its antagonist is contracting and stimulating the tendon reflex. The two reflexes cause the same responses thus enhancing one another.
The Crossed Extensor Reflex -
The crossed extensor reflex is just a withdrawal reflex on one side with the addition of inhibitory pathways needed to maintain balance and coordination. For example, you step on a nail with your right foot as you are walking along. This will initiate a withdrawal of your right leg. Since your quadriceps muscles, the extensors, were contracting to place your foot forward, they will now be inhibited and the flexors, the hamstrings will now be excited on your right leg. But in order to maintain your balance and not fall down your left leg, which was flexing, will now be extended to plant your left foot (e.g. crossed extensor). So on the left leg the flexor muscles which were contracting will be inhibited, and the extensor muscles will be excited
Sutures
Oral and Maxillofacial Surgery
Absorbable
Natural
Catgut
Tansor fascia lata
Collagen tape
Synthetic
Polyglycolic acid (Dexon)
Polyglactin (Vicryl)
Polydioxanone (PDS)
Non-absorbable
Natural
Linen
Cotton
Silk
Synthetic
Nylon
Terylene (Dacron)
Polypropylene (Prolene)