Diseases from Str. pyogenes (Group A strep)
1. Streptococcal pharyngitis. Most frequent Group A infection. Throat has gray-white exudate. Infection may become systemic into blood, sinuses, jugular vein, meninges. In less than a week the M-protein and capsule production decrease, and transmission declines.
2. Skin infections, such as impetigo. Especially in children. Different M-proteins than in pharyngitis. Skin infections associated with edema and red streaking (characteristic).
3. Necrotizing fasciitis/myositis. Infection of deeper tissue advances despite antibiotics.
4. Scarlet fever. Caused by phage-associated erythrogenic toxin-producing strains. Toxins cause cardiac, renal, and other systemic failures. Rash is very red with a sand-papery feel and shedding of superficial skin.
5. Toxic Shock Syndrome. Parallels the toxic shock caused by TSST-carrying Staph. aureus.
6. Non-suppurative, post-infection diseases.
Rheumatic fever (myocarditis, cardiac valve disease, polyarthralgia, rashes. Occurs two weeks after a pharyngeal infection)
Glomerulonephritis (Occurs two weeks after pharyngeal or skin infections. Often due to immunologic reaction to M-protein type 12)
Post viral (post hepatitic) cirrhosis (15-20%)
Cause:- Viral hepatitis (mostly HBV or HCV)
Acute hepatitis → chronic hepatitis → cirrhosis.
Liver is shrunken. Fatty change is absent (except with HCV). Cirrhosis is mixed.
Hepatocytes-show degeneration, necrosis as other types of cirrhosis.
Fibrous septa -They are thick and immature (more cellular and vascular).
- Irregular margins (piece meal necrosis).
- Heavy lymphocytic infiltrate.
Prognosis:- - More rapid course than alcoholic cirrhosis.Hepatocellular carcinoma is more liable to occur
Avitaminoses - Vitamin deficiencies are more commonly secondary disorders associated with malabsorption conditions and chronic alcoholism.
A. Vitamin A - (retinoids, fat soluble compounds derived from ß-carotene) The best-known effect of deficiency is an inability to see in weak light (night blindness due to decreased rhodopsin).
-> The pathology is also characterized by skin lesions (rash on the extremities with punctate erythematous lesions). In malnourished children, vitamin A supplements reduce the incidence of infections such as measles, even in children without signs of preexisting deficiency.
B. Vitamin D - (1, 25 OH2 D3) Deficiency produces osteomalacia (called rickets in children). Many of the effects of osteomalacia overlap with the more common osteoporosis, but the two disordersare significantly different.
-> The specific alteration in osteomalacia and rickets is a failure of mineralization of the osteoid matrix resulting in decreased appositional bone growth.
C. Vitamin E - Very rare. Occurs as a secondary disorder in conditions associated with fat maladsorption such as cystic fibrosis, pancreatitis, and cholestasis (bile-flow obstruction).
-> Vitamin E deficiency causes a neurological disorder characterized by sensory loss, ataxia and retinitis pigmentosa due to free radical mediated neuronal damage.
D. Vitamin K - (phylloquinone) Present in most leafy plants and also synthesized by intestinal bacteria. Vitamin K is required for the production of specific clotting factors and a deficiency is characterized by impaired coagulation (elevated clotting times). Although this can occur in newborns that are given breast milk low in vitamin K, the deficiency is almost always secondarily associated with the use of certain anti-coagulants or disorders such as obstructive jaundice, celiac, or pancreatic disease.
E. Thiamine - (B1) The deficiency is known as beriberi. Thiamine deficiency is characterized by a peripheral neuropathy that affects sensation particularly in the legs (associated with demyelination of peripheral nerves), in more severe cases Korsakoff syndrome (neuropathy characterized by impaired ocular motility, ataxia, and mental confusion) and cardiomyopathy can occur.
F. Nicotinamide (niacin) - The deficiency is known as pellagra. Primary deficiencies are associated with diets that consist primarily of a single low quality protein source (i.e. corn). It results most commonly as a complication of alcoholism.
-> The pathology is characterized by hyperkeratosis and vesiculation of skin, atrophy of the tongue epithelium, and a neuropathy that can affect cortex and peripheral neurons.
- Initial symptoms include a smooth, red tongue, a sore mouth, and ulceration of the inside of the cheeks.
- The skin on the neck, chest, and back of the hands may become brown and scaly.
- Often there is nausea, vomiting, and diarrhea. There may also be insomnia, depression, confusion, and rapid changes of mood. Long-standing pellagra can result in dementia and death.
G. Vitamin B12 - (cobalamin) Because cobalamin is synthesized by intestinal bacteria and is widely available in many foods, deficiencies are almost always secondary disorders associated with gastric atrophy (and decreased uptake via intrinsic factor), microbial proliferation (AIDS), long-term antacids, chronic alcoholism, idiopathic (age-related).
In addition to anemia, the primary clinical symptoms include a sensory neuropathy (polyneuropathy), sclerosis of the spinal cord and atrophy of some mucous tissues.
H. Vitamin C - (ascorbic acid) The classic deficiency is known as scurvy. The essential pathology involves an inability to produce mature collagen and hence affects connective tissue.
This is characterized by an inability to synthesize osteoid and dentin (and results in decreased wound healing) and a loss of integrity of blood vessel walls.
Oral lesions are only a feature of the advanced form of the disease; early signs include fatigue, dermatitis, and purpura. There can be abnormalities in the growing bones of infants.
I. Vitamin B6 - (Pyridoxine) A deficiency can lead to peripheral neuropathy, most commonly associated with multivitamin B deficiencies in malnutrition and alcoholism.
V. Major Minerals - Sodium, potassium, chlorine, and magnesium are required for life but dietary deficiencies do not develop.
A. Iodine - Essential for the synthesis of thyroid hormones, and severe iodine deficiency is associated with hypothyroidism. The compensatory activity of the thyroid gland causes a characteristic enlargement called goiter.
B. Calcium - Required for bone mineralization, the RDA for adults is 800 mg/day. Clinical trials have shown that 1000-2000 mg/day can delay the bone loss observed in the elderly and decrease the risk of osteoporosis. See also section IV B.
VI. Trace Elements - At least 10 elements (examples: Co, Mn, Si) are required in minute amounts for normal development and metabolism.
A. Zinc - A deficiency can result from inadequate amounts given during total parenteral nutrition or as a secondary effect of acrodermatitis enteropathica (autosomal recessive trait characterized by alopecia, dermatitis, and diarrhea - the disease responds to administration of zinc).
B. Copper - Deficiencies are rare and primarily associated with malabsorption syndromes and total parenteral nutrition. Copper is required for normal hematopoiesis and bone growth. A deficiency resembles iron deficiency anemia and osteoporosis.
C. Fluoride - Levels in drinking water greater than 1 ppm cause mottling of teeth and in areas with chronic naturally induced fluorosis there is abnormal calcification of ligaments and tendons.
Auditory tube, which comes in contact
with epithelial line of first pharyngeal
cleft, where future external acoustic
meatus will form.
Distal portion will form tympanic
cavity (lining will become eardrum)
Proximal portion will become auditory tube
Forms buds that penetrate surrounding
mesenchyme, which together form the
Forms thymus and inferior parathyroid
Forms superior parathyroid glands
Forms utlimobranchial body
It is beta-receptor stimulant, which stimulates the heart and causes tachycardia.
It relaxes the smooth muscles particularly the bronchial and GIT. It is mainly used in bronchial asthma, in the treatment of shock and as a cardiac stimulant in heart block.
Is a potent β-adrenergic agonist.
Receptor sites in the bronchi and bronchioles are more sensitive to the drug than those in the heart and blood vessels.
increases the systolic and diastolic blood pressure. Amphetamine is a potent CNS stimulant and causes alertness, insomnia, increased concentration, euphoria or dysphoria and increased work capacity.
Amphetamines are drugs of abuse and can produce behavioural abnormalities and can precipitate psychosis.
It is used as a nasal decongestant and mydriatic agent and also in the treatment of paroxysmal supraventricular tachycardia.
UTERINE RELAXANTS (TOCOLYTICS)
Isoxsuprine has a potent inhibitory effect on vascular and uterine smooth muscle and has been used in the treatment of dysmenorrhoea, threatened abortion, premature labour and peripheral vascular diseases.
Applications-bridges and orthodontic appliances
Soldering -joining operation using filler metal that melts below 500° C
Brazing -joining operation using filler metal that melts above 500°C
Welding-melting and alloying of pieces to be joined
-Oxidative cleaning of area to be soldered
- Oxygen scavenging to prevent oxidation of alloy being soldered
16- 650 -- 650 fineness solder to be used with 16-karat alloys; fineness refers to the gold content
a. Gold solders-bridges
b. Silver solders-gold-substitute bridges and orthodontic alloys
Structure of gold solders
Composition-lower gold content than of alloys being soldered
Manipulation-solder must melt below melting temperature of alloy
1. Physical-similar to alloys being joined
2. Chemical-more prone to chemical and electrochemical corrosion
3. Mechanical-similar to alloy being joined
4. Biologic-similar to alloys being joined
PHARMACOLOGY OF LOCAL ANESTHETICS
1. Block axon conduction (nerve impulse) when applied locally in appropriate concentrations.
2. Local anesthetic action must be completely reversible; however, the duration of the anesthetic block should be of sufficient length to allow completion of the planned treatment.
3. Produce minimal local toxic effects such as nerve and muscle damage as well as minimal systemic toxic effects of organ systems such as the cardiovascular and central nervous system.
Antibiotic protocol for prevention of endocarditis from dental procedures
Local or no anaesthesia
- Oral amoxicillin 3 g 1 hour before procedure
- if allergic to penicillin or have had more than a single dose in previous month: oral clindamycin 600 mg 1 hour beforeprocedure
- patients who have had endocarditis: amoxicillin and gentamycin, as under general anaesthesia
General anaesthesia: no special risk
- Amoxicillin 1 g intravenous at induction, then oral amoxicillin 500 mg 6 hours later
- oral amoxicillin 3 g 4 hours before induction then oral amoxicillin 3 g as soon as possible after procedure
- oral amoxicillin 3 g and oral probenecid 1 g 4 hours before procedure
General anaesthesia: special risk
- Patients with a prosthetic valve or who have had endocarditis are at special risk
- Amoxicillin 1 g and gentomycin 120 mg both intravenous at induction, then oral amoxicillin 500 mg 6 hours later
General anaesthesia: penicillin not suitable
- Patients who are allergic to penicillin or who have received more than a single dose of a penicillin in the previous month need different antibiotic cover
- Vancomycin 1 g intravenous over at least 100 minutes then intravenous gentamycin 120 mg at induction or 15 minutes before procedure
- teicoplanin 400 mg and gentamycin 120 mg both intravenous at induction or 15 minutes before procedure
- clindamycin 300 mg intravenous over at least 10 minutes at induction or 15 minutes before procedure then oral or
intravenous clindamycin 150 mg 6 hours later
1. Osteoma is a benign lesion of bone that in many cases represent a developmental abnormaly or reactive growth rather than true neoplasms. They are most common in the head, including the paranasal sinuses.
Microscopically, there is a mixture of woven and lamellar bone. They may cause local mechanical problems (e.g., obstruction of a sinus cavity) and cosmetic deformities.
2. Osteoid Osteoma and Osteoblastoma
are benign neoplasms with very similar histologic features. Both lesions typically arise during the 2nd & 3rd decades. They are well-circumscribed lesions, usually involving the cortex. The central area of the tumor, termed the nidus, is characteristically radiolucent. Osteoid osteomas arise most often in the proximal femur and tibia, and are by definition less than 2 cm, whereas osteoblastomas are larger. Localized pain is an almost universal complaint with osteoid osteomas, and is usually relieved by aspirin. Osteoblastomas arise most often in the vertebral column; they also cause pain, which is not responsive to aspirin. Malignant transformation is rare unless the lesion is treated with radiation.
• Both lesions are round-to-oval masses of hemorrhagic gritty tan tissue.
• A rim of sclerotic bone is present at the edge of both types of tumors.
• There are interlacing trabeculae of woven bone surrounded by osteoblasts.
• The intervening connective tissue is loose, vascular & contains variable numbers of giant cells.
This is “a bone-producing malignant mesenchymal tumor.” Excluding myeloma and lymphoma, osteosarcoma is the most common primary malignant tumor of bone (20%). The peak age of incidence is 10-25 years with 75% of the affected patients are younger than age 20 years; there is a second peak that occurrs in the elderly, usually secondary to other conditions, e.g. Paget disease, bone infarcts, and prior irradiation. Most tumors arise in the metaphysis of the long bones of the extremities, with 60% occurring about the knee, 15% around the hip, & 10% at the shoulder. The most common type of osteosarcoma is primary, solitary, intramedullary, and poorly differentiated, producing a predominantly bony matrix.
• The tumor is gritty, gray-white, often with foci of hemorrhage and cystic degeneration.
• It frequently destroys the surrounding cortex to extend into the soft tissue.
• There is extensive spread within the medullary canal, with replacement of the marrow. However, penetration
of the epiphyseal plate or the joint space is infrequent.
• Tumor cells are pleomorphic with large hyperchromatic nuclei; bizarre tumor giant cells are common, as are mitoses.
• The direct production of mineralized or unmineralized bone (osteoid) by malignant cells is essential for diagnosis of osteosarcoma. The neoplastic bone is typically fine, lace-like but can also be deposited in broad sheets.
• Cartilage can be present in varying amounts. When malignant cartilage is abundant, the tumor is called a chondroblastic osteosarcoma.
• Several genetic mutations are closely associated with the development of osteosarcoma. In particular, RB gene mutations that occur in both sporadic tumors, and in individuals with hereditary retinoblastomas. In the latter there are germ-line mutations in the RB gene (inherited).
• Spontaneous osteosarcomas also frequently exhibit mutations in genes that regulate the cell cycle including p53, cyclins, etc.
Osteosarcomas typically present as painful enlarging masses.
Radiographs usually show a large, destructive, mixed lytic and blastic mass with infiltrating margins. The tumor frequently breaks the cortex and lifts the periosteum. The latter results in a reactive periosteal bone formation; a triangular shadow on x-ray between the cortex and raised periosteum (Codman triangle) is characteristic but not specific of osteosarcomas.
Osteosarcomas typically spread hematogenously; 10% to 20% of patients have demonstrable pulmonary metastases at the time of diagnosis.
DNA (Deoxyribonucleic acid) - controls cell function via transcription and translation (in other words, by controlling protein synthesis in a cell)
Transcription - DNA is used to produce mRNA
Translation - mRNA then moves from the nucleus into the cytoplasm & is used to produce a protein . requires mRNA, tRNA (transfer RNA), amino acids, & a ribosome