Block 44 Flashcards
Nursemaid elbow (radial head subluxation)
The most common elbow injury in children.
This occur most frequently from a sharp pull on the hand while the forarm is pronated and elbow is extended.
-the sudden increase causes the annular ligament to tear from its periosteal attachment at the radial neck.
-by age of 5 the annular ligament becomes thick and strong decreasing the likehood of displacement.
-affected children present with the injured arm held close to the body with the elbow extended and the forearm pronated.
Amyotrophic lateral sclerosis
Is the most common motor neuron disease.
Combined UMN and LMN lesions are characteristic, damage to motor neuron of the anterior horn and demylination of the corticospinal tracts (UMN lesion) are present.
-the result is denervation atrophy of the muscles.
-the disease manifest in middle aged people and has progressive course.
-Most patients die within 5 years of diagnosis.
-MCC of death is due respiratory complication.
-microscopic :
1. loss of neurons in the anterior horn(LMN)
2. Degeneration and atrophy of the lateral corticospinal tracts (UMN)
3. Loss of neurons in the motor nuclei of CN (V,IX,X,XII)
4. Denervation atrophy of the muscles.
Treatment: Riluzole, MOA.
Nitrites exposure effect on iron
- iron binds to heme normally in the reduced ferrous state (Fe2+)
- nitrites cause poisoning by inducing the conversion of this heme iron to the oxidized ferric state (Fe3+) state, leading to formation of methhemoglobin.
- methhemoglobin is unable to bind O2.
- the affinity of any reisdual ferrous iron in the hemoglobin tetramer is increased causing a leftward shift of the O2 dissociation curve.
- however, the partial pressure of oxygen in blood, which represents the amount of oxygen dissolved in the plasma is unchanged.
Protein structure in regard to alzehaimer disease
-a proteins primary structure is the sequence of amino acids linked be covalent peptide bonds.
-proteins may also assume a secondary structure such as alpha helix or beta sheet, due to subsequent hydrogen bonding.
-in pts with Alzheimer disease beta amyloid protein loses its alpha helical configuration and forms beta sheets, which are less soluble and therefore prone to aggregating. Aggregation of beta sheets are the primary component of senile plaques.
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Androgenic steroid abuse
- acne, testicular atrophy and erythrocytosis are highy suggestive.
- abuse of androgens, androgen precursors and agents that increase endogenous androgen production is most common in young adults who engage in competitive athletic activities or for cosmetic purposes.
- chronic androgen use may increase muscle mass but has multiple associated risks. Testosterone stimulate RBC production.
- androgens decrease gonadotropin secretion which results in testicular atrophy and decreased sperm production
Pus
Consists of thin protien rich fluid known is liquor puris and dead leukocytes, primarily neutophils.
- during infection, macrophages and surrounding endothelial cells release cytokines such as IL-8 that trigger neutophils to enter the site of infection via cheomtaxis.
- IL-8 also induce phagocytosis in neutrophils once they have arrived.
Ulnar nerve injury
Most commonly at the level of the elbow “funny bone” due to trauma or nerve compression, this injury present with loss of sensation in ulnar distribution.
- severe cases can result in weakness on wrist flexion/adduction, finger abduction/adduction and flexion of the fourth/fifth digits.
- weakness of the lumbricals in the 4th/5th digits may produce an ulnar claw deformity during extension of the fingers.
Complete collapse of lung
- it usually occurs following obstruction of a mainstem bronchus. As the air trapped in the lung gradually gets absorbed into the blood there is loss of lung volumes due to alveolar collapse which causes trachea deviation towards the affected side.
- the loss of radiolucent air, combined with shifting of organs into the hemithorax appears as a completely opacified hemithorax on chest X-ray.
Shifting of trachea on xray
Large pleural effusion or tension pneumothorax would cause shifting away from the affected lung, however mainstem bronchus obstruction (complete atelectasis) would cause shifting toward the affected side.
Mycetoma
Aspergilloma , its caused by colonization by aspergillus of preexisting cavity.
Nail neoplasm
Bluish neoplasm occuring underneath the nail bed may be either glomus tumor or subungual melanoma(both are rare)
- glomangioma is a tumor of the modifies smooth muscle cells of a glomus body. Glomus bodies are numerous small encapsulated neurovascular organs found in the dermis of the nail ned, pads of the fingers and toes and the ears.
- the role of the glomus body is to shunt blood away from the skin surface in cold temperatures in order to prevent heat loss, and to direct blood flow to the skin surface in hot envirnoments to facillitate the dissipation of heat.
Criteria to determine malignant potential of adnomatous polyps
- Degree of dysplasia
- Histologic pattern: villous adenomas are more likely to undergo malignant transformation that tubular adenomas.
- Size: risk of malignancy increase with size, especially >4 cm.
UV rays damage to DNA
-primarily through formation of abnormal covaelnt bonds between adjacent thymine or cytosine reisdues (pyrimidine dimers).
The presence of pyrimidine dimers interferes with base recognition during transcription and replication, and DNA mutations can results.
Pyrimidine dimers are removed by nucleotide excision repair (endonuclease complex)
Opiates in spine mechanism
In spine, opiates bind to mu receptors on the primary afferent neuron resulting in closure of voltage gated calcium channels, reduced calcium influx and decreased excitatory neurotransmitter release from presynaptic terminal.
-opiates also bind to postsynaptic membrane, which opens K+ channels and leads to membrane hyperpolarization due to potassium efflux.
Opioid intoxication
- Depressed mental status,
- decreased respiratory rate
- miosis
- bradycardia
- hypotension (due to histamine release)
- decreased bowel sounds also common
Pregnancy induced venous thromboembolic disease treatment
- LMWH currently provides the best balance between mother and child benefits.
- they dont cross the placenta and short elimination time
Esophageal varices is due flow to
Left gastric vein (coronary vein)
Methimazole and propylthiouracil mechanism
Thionamide drugs used for treating hyperthyroidism. They inhibit thyroid peroxidase, the enzyme responsible for both iodine organification and coupling of iodotyrosines.
In propionic academia which amino acids cant be converted to energy
Valine, isoleucine methionine and threonine
-treatment involve starting a low protein diet containing minimal amounts of valine, isoleucine, methionine and threonine.
Esophageal dysmotility in CREST syndrome
Its the result of atrophy and fibrous replacment of the muscularis in the lower esophagus.
-the esophageal body and the lower esophageal sphincter become atonic and dilated resulting in symptoms of GERD. This increase the risk of barrets esophagus and stricture formation
Suprapubic cystostomy
The trocar and cannula pierces the aponeurosis of the abdominal wall muscles, along with the laters of the superficial fascia, transversalis fascia, and extreaperitoneal fat.
However the peritoneum is not entered, reducing the risk of peritonitis and hemoperitoneum.
Aging of skin contributing agents and pathophysiology
- multiple envirnomental factors ,especially exposure to UV light contribute to aging of the skin.
- UV type B contribute to sunburn and increased risk of malignancy
- UV type A contribute to photoaging, it produces reactive oxygen species which activates multiple inflammatory cell surface receptors and nuclear transcription factors. This leads to decreased collagen fibril production, along with upregulation of matrix metalloproteinases that subsequently degrade type I and III collagen and elastin.
Kaposi sarcoma
The most common tumor in HIV patients, KS presents as multiple blue-biolet or brownish dermal plaques that first appear on the feet and legs before spreading proximally.
- KS lesions can also develop on the mucosal membranes of the face and genitals. In pts with late stage disease the lesions spread to the lungs and GI tract.
- histologic examination of skin afflicted with kaposi’s sarcoma shows spindle and endothelial cell proliferation, RBC extravasation and inflammation.
PR interval and ß-blockers
- the longer the PR interval, the longer it takes for an electrical stimulus to travel from SA node to ventricles via AV node, bundle of his and fascicular branches.
- drugs that slow AV nodal conduction such as beta blockers will prolong PR interval.
- beta blockers dont have any specific effects on QRS or QT interval (except sotalol - class III properties )
Amyloid from multiple meyloma
AL amyloid forms due to accumulation of monoclonal immunoglobulin light chains. Its seen as an eosinophilic extracelluar deposts on H&E stain and shows apple-green birefringence with congo red stain when viewed under polarized light.
- AL amyloidosis contributes to the development of renal failure.
- its also deposited in the heart, tongue, CNS
Biopsy of cervical intraepithelial neoplasia
- High grade CIN: means that the atypical cells have invaded beyond the lower 1/3 of cervical epithelium, it have high rate of carcinoma progression. (However it doesnt reach the basment mebrane, which usually signifies cancer development).
- Low grade CIN: cell doesnt invade past lower 1/3 of cervical epithelium.
Huntington clinically
- chorea
- dementia
- behavioral abnormalities such as aggressiveness, apathy or depression.
- Systolic murmur that accentuates with standing from supine position.
- Medication that should be avoided in that case
hypertrophic cardiomyopathy.
- medication that should be avoided in HCM patients:
1. Vasodilators (eg, dihydropyridine Ca+ channel blockers, nitroglycerine, and ACEI) —> decrease systemic vascular resistance leading to decrease afterload and lower LV volumes.
2. Diuretics —> decrease LV venous filling and also result in greater outflow obstruction.
