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Biomedical subjects

W Stauffacher

Publications and source records attributed to W Stauffacher.

7 recordsLinked to original sources
PubMed1992

Effect of acute acidosis and alkalosis on leucine kinetics in man.

The effects of acute pH changes on whole body leucine kinetics (1-13C-leucine infusion technique) were determined in normal subjects. Plasma insulin, glucagon, and growth hormone concentrations were kept constant by somatostatin and replacement infusions of the three hormones. When acidosis was produced by ingestion of NH4Cl (4 mmol kg-1 p.os; n = 8) arterialized pH decreased within 3 h from 7.39 +/- 0.01 to 7.31 +/- 0.01 (P less than 0.001) and leucine plasma appearance increased by 0.13 +/- 0.04 mumol kg-1 min-1 (P less than 0.02); in contrast, when alkalosis was produced by intravenous infusion of 4 mmol kg-1 NaHCO3 (n = 7, pH 7.47 +/- 0.01), leucine plasma appearance decreased by -0.09 +/- 0.04 mumol kg-1 min-1 (P less than 0.01 vs. acidosis). Whole body leucine flux also increased during acidosis compared to alkalosis (P less than 0.05), suggesting an increase in whole body protein breakdown during acidosis. Apparent leucine oxidation increased during acidosis compared to alkalosis (P = 0.05). Net forearm leucine exchange remained unaffected by acute pH changes. Plasma FFA concentrations decreased during acidosis by -107 +/- 67 mumol l-1 (P less than 0.05) and plasma glucose increased by 1.90 +/- 0.25 mmol l-1 (P less than 0.02); in contrast, alkalosis resulted in an increase in plasma FFA by 83 +/- 40 mumol l-1 (P less than 0.02; P less than 0.01 vs. acidosis), suggesting an increase in lipolysis; plasma glucose decreased compared to acidosis (P less than 0.01). The data demonstrate that acute metabolic acidosis and alkalosis, as they occur in clinical conditions, influence protein breakdown, and in the opposite direction, lipolysis.

Acidosis↗
PubMed1992

Effect of increasing doses of recombinant human insulin-like growth factor-I on glucose, lipid, and leucine metabolism in man.

The metabolic effects of recombinant human insulin-like growth factor-I (IGF-I) were assessed in five groups of normal male overnight-fasted volunteers receiving infusions of either 0, 5, 7.5, 15, or 30 micrograms/kg.h IGF-I during 8 h, resulting in total plasma IGF-I concentrations 127 +/- 7, 247 +/- 30, 389 +/- 39, 573 +/- 62, 620 +/- 105 ng/ml, respectively. Glucose consumption (euglycemic glucose clamp) increased dose dependently during IGF-I infusion (P < 0.001) up to 6.7 +/- 1.3 mg/kg. min in the 30 micrograms/kg.h group. Plasma triglyceride concentrations decreased with increasing doses of IGF-I (P < 0.03); the fall was 43% in the 30 micrograms/kg.h group. Plasma free fatty acid concentrations decreased during 7.5, 15, and 30 micrograms/kg.h IGF-I by 23%, 34%, and 48%, respectively. IGF-I lowered plasma beta-hydroxybutyrate concentrations in a dose-dependent manner (P < 0.025). Plasma concentrations of leucine and alpha-ketoisocaproate decreased dose dependently (P < 0.001 and P < 0.015). Whole body leucine flux (1-13C-leucine infusion technique) decreased with increasing doses of IGF-I by 41% during 30 micrograms/kg.h, indicating decreased whole body protein breakdown. Leucine oxidation into 13CO2 decreased with increasing doses of IGF-I (P < 0.045) by 57% in the 30 micrograms/kg.h group, suggesting inhibition of irreversible loss of leucine. Plasma C-peptide and insulin concentrations decreased dose dependently (P < 0.005 and P < 0.02), indicating diminished insulin secretion. Thus, acute elevation of plasma IGF-I concentrations in man results in metabolic effects which are qualitatively similar to those described previously of insulin.

Adult↗
PubMed1977

[Loss of insulin during the infusion of insulin in glucose and nutrient solutions].

Controversial results of previous investigations prompted us to reassess the adsorptive loss of insulin to infusion bottles and tubings. An experimental array was chosen which was in strict accordance with the infusion technique used for the high-caloric parenteral nutrition of severely ill patients. The insulin concentrations were determined by a radioimmunoassay method. As in pure glucose solutions of various concentrations a loss of insulin amounting to about 30% was determined in high-caloric solutions containing aminoacids. The protective effect of human serum albumin, gelatine (Physiogel), and Rheomakrodex, all three of which diminish the insulin loss by about 50%, could be confirmed. The varying results obtained by different investigators may be attributable mainly to technical factors such as different surface properties of the infusion material, differences of the experimental array and analytical methods. Accordingly, variable losses of insulin may also occur in clinical practice. For daily routine an exact knowledge of these losses is irrelevant, since the insulin dosage is adjusted to the blood sugar level. However, if the insulin requirement is used as an index of the metabolic condition of the patient, precise determination of the actual loss is mandatory.

Absorption↗
PubMed1975

[Mode of action and indication for appetite depressants in the treatment of obesity].

After a brief introductory discussion of methods generally used in the treatment of overweight (dieting; fasting; behavioral therapy; physical activity), the pharmacology of anorexigenic drugs and the considerations governing their clinical use and indications are discussed. All currently available anorexigens exert their action through nor-adrenergic stimulation at receptor sites located in the hypothalamus (amphetamine and ephedrine derivatives) or in the limbic system (Mazindol). In view of the CNS-stimulatory effect of these agents, drug addiction must be considered a potential hazard of their prolonged use. Since any drug treatment of obesity interferes with the patient's motivation to subject himself to the prolonged and possibly life-long changes in his eating habits and exertional behavior which are mandatory for the achievement of long-term therapeutic success, the use of drugs is rarely indicated in the treatment of obesity and should remain the exception. In view of their additional potential to induce drug addiction, this is particularly true of appetite suppressants.

Amphetamine↗
PubMed1975

An apparent abnormaltiy of the B-cell microtubular system in spiny mice (Acomys cahirinus).

The pancreatic B-cell contains microtubules, which are thought to participate in the process of insulin release. In order to disclose a possible abnormaltiy of this B-cell microtubular system in animals with islet dysfunction, isolated islets from normal rats and mice, as well as from diabetic mutant mice (DBM mice) and from spiny mice (Acomys cahirinus) were incubated in the presence of vincristine, which causes the precipitation of the microtubular protein into paracrystalline deposits. Ultrastructural examination of the islets indicated that the volume-density of vincristine-induced deposits was markedly reduced in B-cells of spiny mice, when compared to that found in normal rats and mice and DBM mice. Exposure of the islets from spiny mice to a high glucose concentration, concomittantly to vincristine, caused a further reduction in vincristine-induced crystals content of the B-cell. It is speculated that an impairment of the B-cell microtubular system may account for the deficiency of insulin release found in spiny mice.

Animals↗
PubMedDate not supplied

Protein metabolism assessed by 1-13C leucine infusions in patients undergoing bone marrow transplantation.

Patients receiving cytoreductive therapy and bone marrow transplantation (BMT) are known to develop marked protein catabolism. To assess the contribution of whole body protein breakdown, amino acid oxidation and incorporation into proteins, plasma leucine kinetics (1-13C-leucine infusion technique) were determined in six patients five times within 14 days before and after cytoreductive therapy (Cyclophosphamide and total body irradiation) and marrow transplantation. Nitrogen balance became negative (-0.20 +/- 0.04 g/Kg/24 hr) after cyclophosphamide (p less than 0.01) and was -0.25 +/- 0.05 g/Kg/24 hr 7 days after BMT in spite of total parenteral nutrition. Plasma leucine concentration increased after BMT by 67% (p less than 0.0015). Leucine plasma appearance was 1.20 +/- 0.15 mumol/kg/min before treatment, it increased slightly and transiently after cyclophosphamide, and increased again from day 5 to day 7 after BMT (p less than 0.01), suggesting increased protein break-down. Leucine oxidation increased from 0.27 +/- 0.07 before therapy to 0.97 +/- 0.16 mumol/kg/min (p less than 0.02) after cyclophosphamide and BMT. Nonoxidative leucine disappearance rate decreased slightly from 0.92 +/- 0.08 to 0.75 +/- 0.16 mumol/kg/min after BMT (ns). Leucine metabolic clearance rate decreased from 11.8 +/- 1.65 before therapy to 6.9 +/- 0.70 ml/kg/min (p less than 0.02) after cytoreductive therapy. After BMT it increased again to 9.9 +/- 1.5 ml/kg/min (p less than 0.02). The results demonstrate that patients undergoing cytoreductive therapy and bone marrow transplantation develop negative nitrogen balance due to increased protein breakdown associated with increased leucine oxidation and increased metabolic clearance rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗