Early cardiovascular adaptation to simulated zero gravity.
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Biomedical subjects
Publications and source records attributed to P Vergne-Marini.
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Rubella antibody titers were determined pretransplant and then serially posttransplantation in 52 consecutive patients whose renal allografts survived at least three months. Group A patients (18) had antibody titers greater than or equal to 1:128 in the posttransplant period. Group B (24) had intermediate antibody titers that never rose higher than 1:64. Group C (10) consistently had antibody titers less than 1:8. Group A did not differ from groups B and C with respect to age, race, sex, type of transplant, underlying renal disease, or maximum complement fixation antibody titers posttransplant to cytomegalovirus or herpes simplex virus, type 1. Group A did differ from groups B and C in its frequency of hepatitis, chronic liver disease, episodes of late rejection (greater than or equal to 21 days after transplant), transplant nephrectomy required for rejection, infections whose defense involves intact cell-mediated immunity, and the number of late rejection episodes per patient. Mechanisms underlying these associations are not known but apparently are not related to HLA phenotype.
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The drainage and instillation of poorly absorbable corticosteroids has recently been suggested as an laternative to the present modes of therapy for uremic pericarditis. One patient who underwent such a therapeutic approach subsequently had a left internal mammary artery to right internal mammary vein arteriovenous fistula develop. To our knowledge, this is the first report of the development of arteriovenous fistula after either pericardiocentesis or intrapericardial instillation of steroids.
A serum bank maintained for renal transplant recipients allowed for a longitudinal study of antibody responses before and after herpes zoster. Renal transplant recipients without herpes zoster served as controls. Antibody responses to varicella-zoster virus, herpes simplex virus type 1, and cytomegalovirus were measured. The serological responses following herpes zoster were prompt and sustained (in the majority of cases), transient, or not present at all. Zoster without an eruption occurred (apparent only on retrospective chart review) and furnished an explanation for unexplained unilateral pain syndromes in these patients. Asymptomatic rises in titer of antibody to varicella-zoster virus not explained by rises in antibody to herpes simplex virus occurred in both groups. This latter finding points to an unstable relation between virus and host and supports and hypothesis of Hope-Simpson that subclinical release of virus with resulting antigenic stimulation may maintain immunity to varicella-zoster virus. Patients with herpes zoster and controls did not differ in several humoral immune parameters that might have explained the occurrence of herpes zoster. There was no evidence that herpes zoster precipitated renal graft rejection.
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Calcium absorption in 30-cm segments of small intestine was measured by constant perfusion of test solutions containing different concentrations of calcium gluconate. In both the jejunum and ileum, calcium absorption rates increased progressively as luminal calcium concentration was increased stepwise between 1 and 20 mM. Although calcium transport was not saturable within these limits, unidirectional flux ratios of calcium (47Ca) suggest that calcium absorption is active in both the jejunum and ileum. Calcium absorption in patients with chronic renal disease was markedly depressed in both regions of the small intestine. This was due to decreased flux out of the lumen; flux in the reverse direction was normal. Flux ratios in the renal disease patients showed no evidence for active calcium transport. Treatment of these patients for 1 wk within 2 mug/day of 1alpha-hydroxycholecalciferol [1alpha-(OH)-D3] restored net calcium absorption and unidirectional calcium flux out of the lumen to normal values in the jejunum; in the ileum, 1alpha-(OH)-D3 increased calcium absorption 60-83% of normal at the various luminal calcium concentrations. 1alpha(OH)-D3 had no effect on unidirectional calcium flux into the lumen or on xylose and electrolyte absorption in either area of the small intestine.
Magnesium absorption was studied in the normal human jejunum and ileum by in vivo intestinal perfusion, using test solutions containing from 0 to 20 mM Mg (as MgCl2). As luminal Mg concentration was increased, the rate of absorption in the jejunum rose progressively with a tendency towards saturation at the higher concentrations. The kinetics and rates of Mg absorption in the ileum were comparable to those in the jejunum, with the exception that at higher luminal concentrations the ileal absorptive process was fully saturated. Using test solutions containing various combinations of Ca and Mg, we found that Ca had little or no influence on Mg absorption, even through Mg depressed Ca absorption to a modest extent. Patients with end-stage renal disease, who had a reduced rate of Ca absorption (presumably due to deficiency of 1,25-dihydroxycholecalciferol) were found to have a severe depression of Mg absorption. On the other hand, patients with absorptive hypercalciuria and nephrolithiasis, who had an increased rate of Ca absorption, were found to absorb Mg normally. These results suggest that Mg absorption in the human is mediated by a transport process different from that which facilitates Ca absorption, and that normal Mg absorption may be dependent on vitamin D. Our results do not establish whether or not the normal intestine can absorb Mg against an electrochemical gradient.
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