Search PubMed⌕ Search

Biomedical subjects

S A Falk

Publications and source records attributed to S A Falk.

33 records · Page 2Linked to original sources
PubMed1985

Graves' disease associated with histologic Hashimoto's thyroiditis.

The microscopic slides of 16 patients who underwent bilateral subtotal thyroidectomy for hyperthyroid Graves' disease were reviewed and classified into three groups: I, Hashimoto's thyroiditis; II, Graves' disease; and III, both Hashimoto's thyroiditis and Graves' disease. Three patients were classified as group I, 10 as group II, and three as group III. In 38% of the patients with clinical Graves' disease the histologic evidence of Hashimoto's thyroiditis could be found either alone or in combination with histologic evidence of Graves' disease (groups I and III). One patient in group I, four in group II, and three in group III had infiltrative ophthalmopathy (50% of total). Hyperthyroid Graves' disease, Graves' ophthalmopathy, and Hashimoto's thyroiditis can occur all together, in duads, or individually at a specific time in a patient's life.

Adult↗
PubMed1981

Glomerular dynamics and morphologic changes in the generalized Shwartzman reaction in postpartum rats.

The roles of glomerular functional and morphologic changes were examined in the acute renal failure associated with generalized Shwartzman reaction in postpartum Munich Wistar rats. The susceptibility of postpartum rats to acute deterioration in renal function after a 2-h endotoxin infusion was found to be greater than in virgin litter mates: glomerular filtration rate fell by 93% in the former vs. 24% in the latter group (P less than 0.001). In postpartum rats there were marked changes in platelet count and fibrinogen level (P less than 0.025) compatible with consumption coagulopathy. Renal blood flow and glomerular filtration rate fell from 5.5 +/- 0.9 and 0.74 +/- 0.12 to 2.0 +/- 0.7 and 0.12 +/- 0.01 ml/min, respectively (both P less than 0.001). Blood pressure did not change. Results of glomerular dynamics studies showed decreases in single nephron filtration rate from 28 +/- 7 to 6 +/- 4 nl/min and in glomerular plasma flow rate from 77 +/- 26 to 23 +/- 12 nl/min (both P less than 0.001). Afferent net ultrafiltration pressure fell from 20 +/- 3 to 5 +/- 4 mm Hg due to a fall in glomerular capillary hydraulic pressure from 47 +/- 1 to 29 +/- 5 mm Hg (P less than 0.001). There were four- and twofold increases in afferent and efferent arteriolar resistances, respectively. Less than 20% of glomeruli had evidence of fibrin deposition after 2 h of endotoxin infusion, a time when glomerular filtration rate was reduced by greater than 90%. [1-Sar, 5-Ile, 8-Gly] angiotensin II infusion before endotoxin significantly protected glomerular filtration rate, 62 vs. 7% of control in rats with no preinfusion (P less than 0.01) despite consumption coagulopathy and glomerular fibrin deposition similar to rats without pretreatment. These data suggest that the early deterioration in renal function in the generalized Shwartzman reaction in the postpartum rat is due to major changes in glomerular dynamics induced by neurohumoral agents and that glomerular fibrin deposition plays a lesser pathogenetic role at this time in this disorder. The study does not address the pathogenesis of renal failure in pregnancy nor peripartum renal failure in another species.

Animals↗
PubMed1977

Intrarenal dynamics in the pathogenesis and prevention of acute urate nephropathy.

Tubular fluid flow, urine osmolality, and pH were selectively altered to determine the relative protective roles of these factors in a rat model of acute urate nephrophathy. Various prehyper uricemic conditions were established in five groups of animals: (a) normopenic Wistar rats given no pretreatment (Group I); (b) Wistar rats given acetazolamide, 20 mg/kg, and isotonic NaHCO3 to produce urine alkalinization (Group II); (c) Wistar rats in which a moderate diuresis, similar to that observed in Group II but without urine alkalinization, was induced with furosemide, 2 mg/kg (Group III); (d) Wistar rats in which a high-flow solute diuresis was induced with furosemide, 15 mg/kg (Group IV); (e) Brattleboro rats, homozygous for pituitary diabetes insipidus, that had a spontaneous high-flow water diuresis (Group V). A comparable level of hyperuricemia (19.4+/-2.2 mg/100 ml) was achieved in all animals with intravenous urate infusion. Clearance and micropuncture studies were performed before and 1 h after induction of hyperuicemia. Group I rats had mean falls in renal plasma flow and glomerular filtration rate of 83 and 86%, respectively; nephron filtration rate decreased 66%, and tubular and microvascular pressures increased twofold. In Group II there were 45 and 47% declines in renal plasma flow and glomerular filtration rate, respectively, a 66% fall in nephron filtration rate, and a 30% increase in tubular and vascular pressures. Moderate amounts of urate were seen in the kidneys. Group III had changes in renal function identical to Group II suggesting that the moderate prehyperuricemic diuresis in the latter group and not urine alkalinization produced the partial protection observed. Groups IV and V were completely and comparably protected with renal function studies unchanged from controls. It is concluded that high tubular fluid flow, whether induced by a solute or water diuresis, is the primary mechanism of protection in acute urate nephropathy. At most, urine alkalinization plays a minor preventive role.

Animals↗
PubMed1976

A micropuncture study of the early phase of acute urate nephropathy.

The early pathophysiological changes in acute urate nephropathy were investigated in a rat model using micropuncture, clearance, and morphologic methods. Plasma urate was increased from 1.2 +/- 0.6 to 20.1 +/- 3.1 mg/100 ml (P less than 0.001). Urinary urate rose from 24.3 +/- 5.1 to 142.2 +/- 21.0 mg/100 ml (P less than 0.001). Renal plasma flow and glomerular filtration rate fell to 17 and 14% of control values, respectively, and urine flow rate decreased from 11.3 +/- 4.8 to 4.2 +/- 2.2 mul/min (all P less than 0.005) Superficial nephron filtration rate fell less than that of the whole kidney (70 vs. 86%). Both proximal and distal tubular pressures were increased from 10.6 to 26.1 mm Hg and from 7.2 to 24.7 mm Hg, respectively (P less than 0.005). Efferent arteriolar and peritubular capillary pressures were increased twofold. Vascular resistance beyond the peritubular capillaries increased from 4.8 X 10(9) to 21.6 X 10(9) dynes s/cm5. Extensive deposits of uric acid and urate were found in the tubular system and vasa recti from the corticomedullary junction to the tip of the papilla. It is concluded from these experiments that not only tubular obstruction in the collecting ducts, but also obstruction of the distal renal vasculature, are the primary early pathogenetic events in acute urate nephropathy.

Absorption↗
PubMedDate not supplied

Effect of mastoid cavity modification on middle ear sound transmission.

The modified radical mastoidectomy and intact canal wall mastoidectomy are the two most popular procedures used today for the treatment of chronic middle ear and mastoid disease. Their effects on the anatomy of the middle ear and mastoid cavity are quite different and it might also be expected that they would modify middle ear sound transmission in different ways. This paper describes experiments with human temporal bones and a middle ear computer analog model that attempt to define acoustic differences produced by cavity modifications in these two procedures. The temporal bone studies showed that blocking the aditus (as in modified radical mastoidectomy) produced improved sound transmission in the 1,500- to 4,000-Hz range and decreased transmission below 1,000 Hz when compared to the enlarged aditus and enlarged mastoid condition (as in intact canal wall mastoidectomy). Computer model showed better transmission at all frequencies with the intact canal wall mastoidectomy simulation.

Acoustic Stimulation↗