Biomedical subjects

S Klein

Publications and source records attributed to S Klein.

At least 289 records · Page 16Linked to original sources

PubMed1990

Role of triglyceride-fatty acid cycle in controlling fat metabolism in humans during and after exercise.

We have investigated the role of triglyceride-fatty acid cycling in amplifying control of the net flux of fatty acids in response to exercise and in recovery from exercise. Five normal volunteers were infused with [1-13C]palmitate and D-5-glycerol throughout rest, 4 h of treadmill exercise at 40% maximum O2 consumption, and 2 h of recovery. Total fat oxidation was quantified by indirect calorimetry. Lipolysis (rate of appearance of glycerol) increased from 2.1 +/- 0.3 to 6.0 +/- 1.2 mumol.kg-1.min-1 after 30 min of exercise and progressively increased thereafter to a value of 10.5 +/- 0.8 mumol.kg-1.min-1 after 4 h. Lipolysis decreased rapidly during the first 20 min of recovery, but it was still significantly elevated after 2 h of recovery. The rate of appearance of free fatty acids followed the same pattern of response. Seventy percent of released fatty acids were reesterified at rest, and this value decreased to 25% within the first 30 min of exercise. Reesterification remained less than 35% of lipolysis until the start of recovery, at which time the value rose to 90%. In exercise, more than one-half the increase in fat oxidation could be attributed to the reduction in the percent reesterification. Most of the change in percent reesterification during exercise and recovery was caused by changes in extracellular cycling of fatty acids released into plasma. We conclude that triglyceride-fatty acid cycling plays an important role in enabling a rapid response of fatty acid metabolism to major changes in energy metabolism.

Adult↗

PubMed1990

Bradykinin attenuates glucagon-induced leucine oxidation in humans.

Trauma and injury are associated with accelerated protein loss. Counterregulatory hormones are possible mediators of this response. In the present study, the effect of glucagon and glucagon plus bradykinin on leucine and urea kinetics was examined in nine normal volunteers during somatostatin infusion and basal insulin replacement. Bradykinin was given because of its prostaglandin-stimulating qualities and the potential anabolic action of prostaglandins. Physiological hyperglucagonemia elicited a small but significant reduction of total leucine flux and rate of urea synthesis. Simultaneously, leucine oxidation increased by 70%. The simultaneous infusion of bradykinin did not alter glucagon-related changes in urea or leucine kinetics. Bradykinin, however, significantly attenuated the stimulation of leucine oxidation by glucagon. These results suggest that glucagon and tissue factors are involved in controlling leucine metabolism in humans.

Adult↗

PubMed1990

Role of the glucose cycle in control of net glucose flux in exercising humans.

The hepatic glucose cycle involves the production of plasma glucose from glucose 6-phosphate and the simultaneous conversion of glucose back to glucose 6-phosphate. We have evaluated the role of the glucose cycle in the regulation of plasma glucose concentration during exercise at 70% of maximal O2 uptake and during recovery in five normal volunteers. Total glucose flux was measured by use of [2-2H]glucose (Ra2), net glucose flux through the glucose cycle was determined with [6,6-2H2]glucose (Ra6), and the rate of glucose cycling was determined by Ra2 - Ra6. Gas chromatography-mass spectrometry was used for analysis of isotopic enrichment. At rest, 33% of total glucose flux was recycled. In exercise, total flux increased 300%, but so did glucose cycling, which means that there was no change in the percentage of flux recycled. In recovery, both total flux and the rate of recycling returned rapidly to the resting value. We therefore conclude that whereas total glucose production can respond extremely quickly to large changes in energy requirements caused by exercise, thereby enabling maintenance of a constant blood glucose concentration, glucose cycling does not have an important role in amplifying the control of net hepatic glucose flux through the glucose cycle.

Adult↗

PubMed1990

Whole-body lipolysis and triglyceride-fatty acid cycling in cachectic patients with esophageal cancer.

Whole-body lipolytic rates and the rate of triglyceride-fatty acid cycling (reesterification of fatty acids released during lipolysis) were measured with stable isotopic tracers in the basal state and during beta-adrenergic blockade with propranolol infusion in five cachectic patients with squamous cell carcinoma of the esophagus, five cachectic cancer-free, nutritionally-matched control patients, and 10 healthy volunteers. Resting energy expenditure and plasma catecholamines were normal in all three groups. The basal rate of glycerol appearance in blood in the patients with cancer (2.96 +/- 0.45 mumol.kg-1.min-1) was similar to that in the nutritionally matched controls (3.07 +/- 0.28 mumol.kg-1.min-1), but 48% greater than in the normal-weight volunteers (2.00 +/- 0.16 mumol.kg-1.min-1) (P = 0.028). The antilipolytic effect of propranolol and the rate of triglyceride-fatty acid cycling in the patients with cancer were also similar in the cachectic control group and approximately 50% greater than in the normal-weight volunteers, but the differences were not statistically significant because of the variability in the data. We conclude that the increase in lipolysis and triglyceride-fatty acid cycling in "unstressed" cachectic patients with esophageal cancer is due to alterations in their nutritional status rather than the presence of tumor itself. Increased beta-adrenergic activity may be an important contributor to the stimulation of lipolysis.

Adult↗

PubMed1990

[Distribution pattern of chemical in surface waters as a reflexion of entry pattern--nonvolatile halogenated hydrocarbons].

The concentrations of some nonvolatile halogenated hydrocarbons in surface waters of an industrialized city and its surroundings are given. About 80% of the ballast isomers of hexachlorocyclohexane (alpha, beta and delta BHC) and of DDT and its metabolites are in the range of less than 5 micrograms l-1, whereas ca. 50% of lindane (gamma BHC) were found to be between 5 and 100 micrograms l-1. Starting form the remarks about the differential-diagnostic assessment of environmental concentrations conclusions as to the origin of hexachlorocyclohexane isomers are drawn with the help of their distribution pattern. A high part of the gamma isomer, compared with the ballast isomers means an application (e.g. against mosquitos). This fact may be supported if it coincides with the months typical for such an application. in contrast to this if you have high percentages of alpha, beta and delta hexachlorocyclohexane, it indicates a point source or diffuse inputs of technical BHC. If all four isomers are present on a comparable and very low level this may reflect a remobilization from the sediment.

DDT↗

PubMed1990

The "buried bumper syndrome": a complication of percutaneous endoscopic gastrostomy.

Percutaneous endoscopic gastrostomy is used for long-term nutritional support and can be performed with relatively few complications. We describe a patient in whom the internal bumper eroded into the stomach wall and was completely covered by gastric epithelium 11 months after gastrostomy tube placement. The gastrostomy tube itself was patent, and the end still protruded into the lumen of the stomach so that tube feeding was not impaired. Endoscopy, in combination with passage of Savary dilators over a guidewire, was safely used to remove the gastrostomy tube and buried bumper. We recommend this approach in patients with the "buried bumper" syndrome to prevent continued tube migration into the gastric and abdominal walls.

Aged↗

PubMed1990

Nutritional requirements in the elderly.

Nutritional management of elderly persons can be difficult because of illness, drug-nutrient interactions, socioeconomic factors, and lack of precise information regarding nutrient requirements. Dietary intake and requirements, nutritional assessment, and guidelines for nutritional management of the elderly population are reviewed.

Adult↗

PubMed1990

[Alternatives to steroid therapy in chronic uveitis].

In a search for alternative therapeutic methods other than corticosteroids and cytostatics, the effect of a dialyzable leukocyte extract (DLE), the antimetabolite 5-fluorouracil and the immunosuppressive agent cyclosporin A in corticosteroid-resistant idiopathic uveitis was studied. When DLE was administered to 26 patients who had uveitis forms with exogenous triggering (e.g., infection), as well as forms with an autoimmune background, there was a reduction in the number and duration of recurrences and a statistically proven prolongation of the inflammation-free intervals. This was particularly true in anterior and posterior uveitis and to a lesser extent in the intermediate form. No side effects were observed. 5-Fluorouracil, injected subconjunctivally, is indicated in intermediate uveitis with marked vitreous infiltration and beginning proliferation. Corneal erosion occurs relatively often. During treatment with cyclosporin A (low dose, 5 mg/kg of body weight per day), 14 of 17 patients (9 with intermediate uveitis, 6 with retinal vasculitis, 1 with sympathetic ophthalmia, 1 with panuveitis) showed improved results; in 2 cases the findings remained stationary and only 1 case had low-grade deterioration. If one takes into consideration the fact that in this patient any therapy would have failed, the results are convincing. This is particularly true of retinal vasculitis. There is no effect in cases of central hemorrhagic chorioretinopathy. So far, there have been no serious side effects.

Adrenal Cortex Hormones↗

PubMed1990

[Formation of organochlorine compounds in chlorination of water].

This paper is a short version of a comprehensive literature study with the same title. During the chlorination of drinking, bathing and waste water a great number of halogenated compounds may be formed by the reaction of the disinfection agent with substances present in water. The haloforms which are often used as key compounds are only the tip of the iceberg. Reaction pathways and a selection of products are presented. The difficulty of assessing the health risk of a lifelong exposure to such compounds is pointed out. At present it doesn't however seem to be justified to abolish water chlorination because of hints to a possible weak carcinogenic action, because the arising bacterial risk would be irresponsible high.

Chlorine↗

PubMed1990

[Distribution pattern of chemicals in surface waters as a reflexion of entry pattern--description of the problems].

The distribution pattern of persistent substances made transparent chemically-analytically, in surface waters reflects--considering spatial-temporal limitations--an image of the input pattern. This permits in special cases repercussions on attributable (industrial enterprises, trade, plant production, pest control) or partly or completely anonymous (landfills, ancient deposits, contamination centres, traffic, atmospheric depositions) causative agents The classification of these information requires the knowledge of substance and substrate specifics, especially detailed information about production and/or application of the substances and so represents an interdisciplinary task. Assessing single substance analyses permits a comparison with limit values or literature data. The consideration of combinations of substances which belong together due to production, application and/or transformation may help to elucidate the input patterns. This differential-diagnostic method is presented by a first evaluation of analytical findings in surface waters of an industrialized town and its surroundings.

Hydrocarbons, Halogenated↗

PubMed1990

[Distribution pattern of chemicals in surface waters as a reflexion of entry pattern--volatile halogenated hydrocarbons].

The part gives some data about various light volatile halogenated hydrocarbons in surface waters of the industrialized city and its surroundings--the halogenated forms, chloroform and bromoform and the most used solvents trichloroethylene, tetrachloroethylene, tetrachloromethane and 1,1,2,2-tetrachloroethane. 80% of the concentrations of chloroform, tri- and tetrachloroethylene were in the range of less than 1 microgram l-1, 90% of bromoform, tetrachloromethane and 1,1,2,2-tetrachloroethane were found to amount less than 0.1 microgram l-1. With the help of the differential-diagnostic assessment method described in the first part we tried to evaluate the data for tetrachloromethane. The highest values were obtained for almost all sampling points in April--a possible cause may be the use of this solvent for cleaning and repairing procedures with sport boats (although tetrachloromethane has been prohibited for such uses for some years there may be some remainders which were used for these purposes).

Hydrocarbons, Brominated↗

PubMed1990

[Distribution pattern of chemicals in surface waters as a reflexion of entry pattern--heavy metals].

The concentrations of the heavy metals lead, cadmium and mercury were measured in surface water samples of an industrialized city and its surroundings. All but one value of Cd (particular) were less than 0.5 microgram l-1, 30% of the lead (particular) values were less than 0.5 microgram l-1, 70% 0.5 ... 10 micrograms l-1, 86% of the total mercury less than 0.1 and 14% 0.1 ... 0.5 microgram l-1. By applying the differential-diagnostic assessment method it could be found that the highest values were found in the vicinity of a metal-using factory. On a sampling point near such an enterprise the part of particularly bound lead was very low, that means a recent input, whereas on another sampling point with a high total lead level 95% were particularly bound which refers to a continuous input.

Cadmium↗

PubMed1989

The possible role of histamine-mediated cAMP formation as a link between H2-receptor stimulation and ultrastructural changes in guinea-pig oxyntic cells.

Guinea-pig oxyntic cell tubulin has been isolated and in vitro aggregation has been studied. The spontaneous assembly of isolated tubulin was significantly accelerated and increased by 1 mmol/l GTP. Histamine and forskolin increased tubulin polymerization only when detergent dispersed oxyntic cells or crude membranes were added. The forskolin response occurred very rapidly with an EC50 of approximately 30 mumol/l and did not require GTP. Histamine promoted tubulin aggregation with an EC50 of about 5 mumol/l only in the presence of GTP. Ranitidine completely inhibited the effects of histamine. From these data it is suggested that, in the oxyntic cell, histamine H2-receptor activated adenylate cyclase and the corresponding increase in cAMP play a role in eliciting characteristic ultrastructural changes by initiating formation of microtubules as a first step in the cascade of events leading to an increase in the secretory surface area.

Animals↗

PubMed1989

Caregiver burden and moral development.

This paper presents an expanded understanding of both burden and moral development, identifying the traits of burden as being essential components of moral development. Steps in the interpretation of burden are shown to result in caregiver decisions that may be life-giving, oppressive, or a combination of both. This new understanding of burden is then related to Folkman and Lazarus's (1985) theory of stress and coping.

Adaptation, Psychological↗

PubMed1989

Host Restriction and Transduction in Rhizobium meliloti.

A host restriction difference exists between Rhizobium meliloti Rm41 and SU47 exists as indicated by the reduce plating efficiency of transducing phage PhiM12h1. Restriction can be attenuated by incubating cells at 42 degrees C for 3 h; this procedure overcomes a block to transduction from SU47 to Rm41.

Journal Article↗

PubMed1989

Effect of short- and long-term beta-adrenergic blockade on lipolysis during fasting in humans.

Stable isotope tracers and indirect calorimetry were used to evaluate the importance of beta-adrenergic stimulation of lipolysis and triglyceride-fatty acid cycling during fasting in healthy human volunteers. Each subject was studied after 12 and 84 h of fasting both with and without propranolol infusion (protocol 1) and when oral propranolol treatment was given throughout fasting (protocol 2). In protocol 1, the rates of appearance of glycerol and palmitic acid increased from 3.04 +/- 0.19 and 1.78 +/- 0.17 mumol.kg lean body mass-1.min-1, respectively, after 12 h of fasting to 5.28 +/- 0.31 and 3.47 +/- 0.15 mumol.kg lean body mass-1.min-1, respectively, after 84 h of fasting (P less than 0.005). The rate of triglyceride-fatty acid cycling increased from 97 +/- 8 to 169 +/- 5 mumol/min (P less than 0.005). Intravenous propranolol infusion decreased the rate of lipolysis after both 12 and 84 h of fasting, but the magnitude of the antilipolytic effect was much greater after 84 h (P less than 0.005). In protocol 2, the rate of lipolysis and triglyceride-fatty acid cycling was still increased by fasting despite beta-adrenergic blockade with oral propranolol. This study demonstrates that beta-adrenergic stimulation contributes to the mobilization of fat during fasting. However, other mechanism(s) can increase lipolysis and triglyceride-fatty acid cycling when beta-adrenergic receptors are continuously blocked.

Adult↗

PubMed1989

Effect of dichloroacetate on lactate concentration in exercising humans.

The precise mechanism responsible for the increase in plasma lactate concentration during exercise in humans is not known. We have used dichloroacetate to test the hypothesis that a limitation in pyruvate dehydrogenase activity is responsible for the rise in plasma lactate. Dichloroacetate stimulates the activity of pyruvate dehydrogenase, which is normally the regulatory enzyme in the oxidation of glucose when tissue oxygenation is adequate. Six subjects were studied twice according to a randomized, crossover protocol, involving one test with saline infusion and another with dichloroacetate infusion. Exercise load on a bicycle ergometer was increased progressively until exhaustion. Blood samples were drawn each minute throughout exercise and periodically throughout 120 min of recovery. Dichloroacetate significantly lowered the lactate concentration during exercise performed at less than 80% of the average maximal O2 consumption. The peak concentration of lactate at exhaustion was not affected by dichloroacetate treatment, but dichloroacetate did lower lactate concentration throughout recovery. These results suggest that a limitation in pyruvate dehydrogenase activity contributes to the increase in plasma lactate during submaximal exercise and recovery.

Acetates↗

PubMed1989

Patency and durability of small diameter silicone rubber vascular prostheses.

This study evaluated the long-term patency and durability of 6 mm internal diameter (ID), 18-30 micron pore size replamineform silicone rubber vascular prostheses as canine aortic interposition and arteriovenous (A-V) grafts. Six prostheses (6 mm ID x 8 cm length) were evaluated as aortic grafts for 24 to 30 months, and 10 prostheses (6 mm ID x 8-10 cm length) were studied as A-V grafts from 2 weeks to 10 months. Three of the A-V prostheses were punctured for sham dialysis once or twice/week with two 16 gauge needles (total of approximately 50 needle punctures). The porous wall of the silicone rubber prostheses was incorporated with capillaries and fibrohistiocytic cellular elements from 2 weeks of implantation. This cellular incorporation remained constant up to 2 1/2 years. Needle puncture of the arteriovenous grafts over a 3 to 5 month period produced no complications such as thrombosis, perigraft hematoma formation or bleeding through the puncture site. The silicone rubber sealed the holes with no evidence of tearing. Explanted prostheses had no evidence of enlargement or false aneurysm formation. This study supports our hypothesis that Replamineform silicone rubber prostheses are hemocompatable and demonstrate long-term durability for dialysis access. Clinical evaluation of this graft is planned in the near future.

Animals↗