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Biomedical subjects

G Meier

Publications and source records attributed to G Meier.

At least 55 records · Page 3Linked to original sources
PubMed1988

Rebound of aldosterone but not of corticosterone after suppression of adrenal function by triamcinolone acetonide in rats.

1. The effects of microcrystalline 'depot' triamcinolone acetonide on renal excretion and blood levels of aldosterone, 18-hydroxycorticosterone and corticosterone were studied in rats over a 13 day period. The renal excretion of all of these steroids was found to be suppressed on day 1 after triamcinolone acetonide administration. Corticosterone excretion remained suppressed for 6 days, whereas aldosterone and 18-hydroxycorticosterone excretion normalized within 3 days. 2. While corticosterone excretion was returning to control values, the excretion of aldosterone rose to values above the pretreatment levels (the rebound phenomenon). 18-Hydroxycorticosterone excretion paralleled that of aldosterone, but the rebound was of less statistical significance. 3. The findings in urine were confirmed by plasma steroid determinations. A suppression of plasma aldosterone, 18-hydroxycorticosterone and corticosterone was observed in the first 24 h after triamcinolone acetonide injection. On day 4 only corticosterone showed lowered levels. An aldosterone rebound could be seen at 18.00 hours, the circadian maximum in rats. 4. These findings suggest that in addition to the effects on glucocorticoids, mineralocorticoids have to be taken into account in the restoration of the adrenal function after corticoid therapy. The aldosterone rebound observed during this sensitive period may be important in preventing disturbances of electrolyte and water homoeostasis.

Adrenal Glands↗
PubMed1984

Klinokinesis in polymorphonuclear leucocytes.

Klinokinesis has previously been demonstrated in bacteria and amoeba but not in metazoan cells. We report here evidence for klinokinesis in leucocytes. Changes in the rate of human and rabbit polymorphonuclear leucocyte (PMN) displacement elicited by uniform concentrations of the chemotactic peptide formyl-Met-Leu-Phe (fMLP) were associated with alterations of the klinolocomotion index (KI), the mean angle of turns greater than or equal to 90 degrees and the frequency of changes in direction greater than or equal to 90 degrees. Orthokinesis and klinokinesis had synergistic effects and both elements of chemokinesis may have a substantial influence on PMN velocity. The relationship between speed and changes in the direction of locomotion has been analyzed and the putative role of klinokinesis in chemotactic responses is discussed.

Animals↗
PubMed1981

Lack of greater seroconversion of rhesus monkeys after subcutaneous inoculation of dengue type 2 live-virus vaccine combined with infection-enhancing antibodies.

Four groups of six nonimmune male rhesus monkeys were inoculated subcutaneously with formulations of dengue type 2 vaccine virus DEN-2/S-1. Group A received 1.9 x 10(4) plaque-forming units of vaccine in normal human serum albumin diluent. Group B received the same dose combined with a dengue type 2-immune human serum diluted 1:1,600, beyond its neutralization endpoint of 1:300, but having an immune enhancement titer of 250,000. Groups C and D received 10-fold dilutions of these respective formulations. No migration-inhibitory factor was found when peripheral blood mononuclear leukocytes obtained on day 68 post-immunization from monkeys of all experimental groups were tested. No viremia was detected in any of the monkeys when sera taken on postvaccination days 1 through 12 were inoculated into adult Toxorhynchites amboinensis mosquitoes and LLC-MK2 cells. By day 89, four of the six monkeys had seroconverted by the neutralization test in each of groups A, B, and C, and three of five monkeys in group D (one monkey died from cardiac collapse after anesthesia) had seroconverted. Immune enhancement of dengue virus infection is known to occur in humans and monkeys circulating heterologous flavivirus antibodies. In this study, there was no enhancing effect when antibody was mixed with dengue type 2 vaccine virus and injected subcutaneously.

Animals↗
PubMed1976

Myocardial interaction between the ventricles.

The myocardial interaction between the ventricles was studied using isolated, flow-perfused, paced rabbit hearts beating isovolumically. In general, increasing left ventricular (LV) volume increased right ventricular (RV) diastolic and developed pressures. In particular, with a peak RV volume (RVV), increasing LV volume (LVV) from zero to two-thirds of its peak volume increase RV diastolic pressure by 1.7 mmHg (N=10, P less than 0.001) and RV developed pressure by 1.5 mmHg (N=10,P less than 0.001). For the LV, small RVV caused LV diastolic and developed pressure to increase, while large RVV increased LV diastolic pressure but decreased LV developed pressure. With a LVV held at two-third of peak volume, increasing RVV from zero to its peak volume caused LV diastolic pressure to increase by 2.5 mmHg (N=10,P less than 0.001) and LV developed pressure to decrease by 2.0 mmHg (N=10, P less than 0.001). The position of the interventricular septum correlated with LV diastolic pressure and RV diastolic and developed pressure changes (P less than 0.01). The results demonstrate that the diastolic and developed pressure-volume relationships of either ventricle can be acutely altered by varying the volume of the other ventricle.

Animals↗