Hemodynamic effects of bPTH(1-34) and its analogue Nle8,18Tyr34bPTH(3-34) amide.

We examined the vascular effects of bovine PTH(1-34) and of an analogue, Nle8,18Tyr34bPTH(3-34) amide, which inhibits adenylate cyclase activation by bPTH(1-34) in a number of in vitro systems. In the conscious dog. bPTH(1-34) injection produced dose-dependent hypotension associated with increased heart rate and cardiac output. The (3-34) analogue had no hypotensive effect in doses up to 6.0 micrograms/kg (1.5 nM/kg). In vitro studies revealed that bPTH(1-34) relaxed pitressin-contracted helical strips from the rat caudal artery. The (3-34) analogue displayed a weak, but definite inhibitory effect against the vasorelaxant effects of bPTH(1-34) with a pA2 of 5.5. The results further characterize the previously established hypotensive and vasorelaxant actions of bPTH(1-34), and suggest that the (3-34) analogue, which inhibits adenylate cyclase generation by bPTH(1-34) in nonvascular tissues, antagonizes the vasorelaxant effects of bPTH(1-34) as well. The results provide suggestive evidence that the vasorelaxant effects of bPTH(1-34) may be mediated by adenylate cyclase.

A double-blind evaluation of sodium gradient hemodialysis.

In a double-blind, crossover trial, 7 chronic hemodialysis patients underwent three 4-week treatment periods. During one period, dialysate contained 135 mEq/l sodium. During another period, dialysate contained 143 mEq/l sodium. During the remaining period, we used "sodium gradient' dialysate, the sodium concentration of which was decreased from 160 to 133 mEq/l during each 4-hour dialysis session. Ultrafiltration was performed at a constant rate to achieve a predetermined post-dialysis weight. Interdialytic weight gain, thirst, blood pressure control, and incidence of side effects were monitored. There was a significant difference in interdialytic weight gain for the 3 treatments (p = 0.005). Interdialytic weight gain using 135 mEq/l sodium dialysate (2.2 +/- 0.9 kg, mean +/- SD) was significantly less than that using either 143 mEq/l sodium dialysate (2.6 +/- 0.8 kg) or sodium gradient dialysate (2.8 +/- 0.7 kg). Self-reported thirst tended to be less severe with 135 mEq/l sodium dialysate than with 143 mEq/l sodium dialysate or with sodium gradient dialysate, but changes in thirst were not statistically significant (p = 0.13). The incidence of intradialytic hypotensive episodes was comparable with the 3 levels of dialysate sodium. The results suggest that the described sodium gradient method does not prevent the increased interdialytic weight gain and thirst seen with other forms of high-sodium dialysis, and probably does not reduce the incidence of side effects.

Ultrafiltration hemodynamics in conscious, uremic dogs: effect of a decreasing plasma urea level.

The hemodynamic effects of a decreasing plasma urea level during hemodialysis were studied in acutely uremic, conscious dogs. Each dog was studied twice, during dialytic ultrafiltration against both a urea-free (U-) and a urea-supplemented (U+) dialysate. Plasma osmolality (-13 mosm/kg/H2O +/- 10 SD, p less than 0.01) and urea levels (-43 mg/dl +/- 20, p less than 0.01) decreased when using the (U-) dialysate, but were unchanged with the (U+) dialysate. At the end-point of volume depletion (MAP less than 80 mm Hg) total peripheral resistance index [U (+): 3,376 +/- 743 dyn . s X cm-5 X m2, U(-): 3,091 +/- 537, NS)] and blood volume [U(+): 62.7 +/- 7.4 ml/kg, U(-): 63.7 +/- 7.5, NS)] were comparable whether or not the plasma urea level had been allowed to decrease. The data suggest that an acutely decreasing plasma urea level during dialysis does not impair hemodynamic response to volume depletion in the model described.

Extreme hyperglycemia in dialysis patients.

In 12 diabetic patients who were being treated with maintenance hemodialysis or maintenance peritoneal dialysis, coma and other neurologic deficits did not occur in spite of extremely elevated serum glucose levels. The mean serum values of these patients were: glucose 1,174 +/- 248 (SD) mg/100 ml, sodium 125 +/- 5 mEq/l, calculated total osmolality 342 +/- 13 mOsm/kg water and calculated effective osmolality (without urea) 316 +/- 13 mOsm/kg water. It is suggested that the absence of osmotic diuresis and the lack of substantial osmotic ultrafiltration prevented the development of hypernatremia and marked hyperosmolality. The osmolar effect of glucose alone at these serum concentrations apparently was not sufficient to induce neurologic impairment.

[Intradural lumbar disk hernia. Contribution of 2 cases]. / Hernie discale lombaire intradurale. Apport de deux cas.

Two new cases of intradural herniated disks are added to those previously reported in the literature. It's frequency in our casuistry is of 0.27%, similar to that of other series. Predisponent factors and incidence at different levels are reviewed. Acute or subacute clinical on-set, level of lesion and an early surgical treatment seems to influence the evolution of these patients. Recent observations with C.T. with metrizamide and cytological study of L.C.R. with Cytospin suggest a more precise preoperative diagnosis than the myelography. The final diagnosis has been casual after intradural exploration when there were no correlation between the extradural exploration and the clinical and radiological picture. The pathological study of the intradural herniated disk don't differ from the usual extradural herniated disk.