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W Hübl

Publications and source records attributed to W Hübl.

27 records · Page 2Linked to original sources
PubMed1994

Enzymatic determination of sodium, potassium, and chloride in abnormal (hemolyzed, icteric, lipemic, paraproteinemic, or uremic) serum samples compared with indirect determination with ion-selective electrodes.

We evaluated the effect of hemolysis, icteric discoloration, lipemia, paraproteinemia, and uremia on enzymatic methods for determining sodium, potassium, and chloride, according to the National Committee for Clinical Laboratory Standards EP7-P proposals for testing interference from endogenous substances. The sodium, potassium, and chloride assays (reagent kits supplied by Boehringer Mannheim) were based on electrolyte-dependent beta-galactosidase, pyruvate kinase, and alpha-amylase, respectively. The results were compared with those obtained by indirect ion-selective electrodes (ISE), which in turn had been validated by flame photometry. We analyzed the samples with Hitachi 717, 737, and 911 chemistry analyzers and with an IL943 flame photometer. The enzymatic results were in good agreement with those by ISE, the interference-related differences generally being without clinical significance; however, none of the enzymatic methods could analyze grossly lipemic samples.

Bilirubin↗
PubMed1993

Intestinal permeability and the prediction of relapse in Crohn's disease.

To see whether intestinal permeability (IP) predicted relapse in Crohn's disease, we measured IP in 72 patients with quiescent Crohn's disease using the lactulose-mannitol test. The permeability index (lactulose/mannitol) was significantly higher in patients than in controls (0.046 [SEM 0.005] vs 0.018 [SEM 0.002], respectively). Patients were followed for 1 year after the test. 26 of the 37 patients with raised permeability, but only 6 of the 35 with normal permeability relapsed within 1 year after the test (p < 0.001). The sensitivity of the permeability test as a predictor for relapse was 81%. A significant correlation was found between the value of the permeability index and the probability of relapse (p < 0.01). These results show that increases in intestinal permeability precede clinical relapses in Crohn's disease and so are an indicator of subclinical disease. The measurement of intestinal permeability may lead to a better understanding of the pathogenesis of Crohn's disease.

Adult↗
PubMed1993

Investigation of the pathogenesis of massive hemolysis in a case of Clostridium perfringens septicemia.

Massive hemolysis is a rare, usually fatal complication of Clostridium perfringens septicemia. Of all toxins produced by the bacterium, phospholipase C (PLC) is believed to be the most likely cause of hemolysis. An influence of neuraminidase has often been suspected. In the present study, a case of C. perfringens septicemia with acute massive intravascular hemolysis is described. It led to death within 4 h of admission to the hospital. While the course of events was comparable to previously reported cases, we succeeded in gaining deeper insight into the pathogenesis by monitoring serum anti-T titer and quantifying serum PLC activity during the course of the disease. We excluded an effect of neuraminidase by a negative direct antiglobulin test, a negative anti-T lectin test, and a steady serum anti-T titer of 1 in 32. Serum PLC activity, on the other hand, showed a nearly fivefold increase (6.0 to 27.3 U/l), which is consistent with the hypothesized dominant role of this enzyme.

Aged↗
PubMed1992

Glycylglutamine: metabolism and effects on organ balances of amino acids in postabsorptive and starved subjects.

The present study was designed to investigate the metabolism of glycylglutamine and its effects on organ balances of amino acids during intravenous infusion of this dipeptide (100 mumol.h-1.kg-1) in postabsorptive and briefly starved (84-86 h) human subjects. Arterial concentrations of glycylglutamine were not significantly different in postabsorptive (265 +/- 18 microM) and starved (241 +/- 13 microM) subjects. Among the organs examined, kidney predominated in clearance of glycylglutamine from plasma. Moreover, renal clearance of glycylglutamine was reduced by starvation (87 +/- 7 vs. 52 +/- 5 mumol/min, P less than 0.01), whereas neither splanchnic nor muscle clearance was significantly affected. Infusion of glycylglutamine raised plasma concentrations of glycine and glutamine by increasing renal release of these amino acids. In postabsorptive subjects the infusion significantly increased splanchnic balances of glycine and glutamine with little or no effect on the muscle balances; the opposite was found in starved subjects. As far as other amino acids are concerned, the infusion decreased the muscle release of alanine and increased renal release of serine. We conclude that the amino acid residues of glycylglutamine are largely metabolized by the splanchnic organs in postabsorptive subjects and by peripheral organs in starved subjects. The latter results in selective inhibition of muscle release of amino acids.

Adult↗
PubMed1991

Utilization of tyrosine dipeptides and acetyltyrosine in normal and uremic humans.

The impact of renal failure on the elimination and hydrolysis of three sources of tyrosine for parenteral nutrition, the dipeptides alanyltyrosine (Ala-Tyr), glycyltyrosine (Gly-Tyr), and N-acetyltyrosine (NAc-Tyr) was investigated in eight patients on regular hemodialysis therapy (HD) and seven healthy controls (CON). In CON, whole body clearance (Ctot) of Ala-Tyr (3,169 +/- 198 ml/min) was higher than Gly-Tyr (1,781 +/- 184, P less than 0.001), and both exceeded NAc-Tyr (284 +/- 24, P less than 0.001). In HD, Ctot of Ala-Tyr was not different from CON, but Ctot of Gly-Tyr (858 +/- 73, P less than 0.001) and NAc-Tyr (129 +/- 30, P less than 0.02) was decreased. The rise in plasma levels of constituent amino acids was higher in Ala-Tyr vs. Gly-Tyr (P less than 0.01). In HD, the pattern was similar, although the increase in Tyr was less than in CON. Plasma Tyr did not increase with NAc-Tyr in either group. Urinary loss of peptides was neglible, but 60% of NAc-Tyr infused was excreted by CON. The half-life of peptides incubated in CON and HD plasma was unchanged for Ala-Tyr (12.3 +/- 0.9 vs. 14.6 +/- 1.9 min) and prolonged for Gly-Tyr in HD (101.7 +/- 4.9 vs. 131.3 +/- 12, P less than 0.05). Thus renal failure does not impair Ala-Tyr disposal and delays Gly-Tyr utilization. These differential effects on peptide assimilation underscore the importance of peptide structure on metabolism. Both peptides, but not NAc-Tyr, may serve as a nutritional substrate in renal failure patients.

Adult↗
PubMed1990

Splanchnic, renal, and muscle clearance of alanylglutamine in man and organ fluxes of alanine and glutamine when infused in free and peptide forms.

The present study was designed to investigate organ metabolism of intravenously (IV) infused (100 mumol.h-1.kg-1) alanylglutamine and its amino acid constituents in a group of healthy subjects. The dipeptide clearance (mumol/min) by kidney (51 +/- 3) was significantly (P less than .01) greater than the clearance by either splanchnic organs (19 +/- 6) or skeletal muscle (21 +/- 8). Infusion of alanylglutamine significantly (P less than .01) increased arterial plasma concentrations of free alanine (260 +/- 31 v 330 +/- 38 mumol/L) and free glutamine (620 +/- 66 v 764 +/- 65 mumol/L) when compared with the baseline period. Concurrently, splanchnic uptake of alanine and glutamine increased and muscle release of alanine ceased. However, muscle release of glutamine remained unaffected. Renal balances of alanine and glutamine changed from neutral to negative (net release) and from positive (net uptake) to neutral, respectively. Infusion of a corresponding mixture of alanine and glutamine had similar effects on arterial plasma concentrations and splanchnic and muscle balances of alanine and glutamine, but had no effect on renal balances of these amino acids. From these studies in man, we conclude that kidney predominates over other organs in clearance of alanylglutamine from plasma and that this may account for the different effect of infusion of alanine and glutamine in free and peptide forms on renal fluxes of these amino acids.

Adult↗
PubMed1989

Influence of molecular structure and plasma hydrolysis on the metabolism of glutamine-containing dipeptides in humans.

Glutamine-containing dipeptides may serve as a source of glutamine in parenteral nutrition solutions. To study the metabolism of glycyl-L-glutamine (gly-gln) and L-alanyl-L-glutamine (ala-gln) bolus injections of both dipeptides (0.1 mmol/kg within 40 seconds) were performed in five healthy male volunteers. Furthermore, plasma hydrolase activity against both peptides was tested by in vitro incubation. Both peptides were rapidly cleared from plasma after injection; however clearance was significantly greater for ala-gln than for gly-gln (1,595 +/- 124 v 507 +/- 14 mL/min). Arterial concentrations of constituent amino acids rose after peptide injection, indicating hydrolysis of the peptides. Glutamine concentration, for example, rose from 573 +/- 29 to a maximum of 718 +/- 34 mumol/L after gly-gln and from 570 +/- 15 to 900 +/- 53 mumol/L after ala-gln injection. Both peptides were hydrolyzed by plasma hydrolases during in vitro incubation. Hydrolysis was greater for ala-gln than for gly-gln. Half-lives of ala-gln and gly-gln were 46 +/- 3 and 553 +/- 160 minutes, respectively. For both peptides, plasma hydrolysis was too low to contribute significantly to in vivo clearance. Our results indicate that gly-gln and ala-gln are suitable sources for glutamine in parenteral nutrition solutions. Furthermore, plasma hydrolases do not play a significant role in peptide metabolism. Both peptides therefore appear to be primarily metabolized via extracellular hydrolysis, presumably by hydrolases on the cell membranes and consecutive uptake of the liberated amino acid residues.

Adult↗