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Biomedical subjects

H W Lane

Publications and source records attributed to H W Lane.

60 records · Page 4Linked to original sources
PubMedDate not supplied

Selenium status of seven chronic intravenous hyperalimentation patients.

Selenium status was determined on seven patients receiving long-term intravenous hyperalimentation (IVH) and they were followed monthly for 4 to 17 months. Analysis of the IVH solutions for selenium revealed no detectable amounts. The selenium indices measures were (1) erythrocyte selenium levels, (2) erythrocyte glutathione peroxidase activities (GSH-Px), and (3) plasma selenium levels. In general, the IVH population had significantly lower values (p less than 0.001) for these selenium indices than a healthy population (n = 275). The plasma selenium levels decreased to below the normal range within one to two months after initiation of IVH. The below normal ranges varied by patient: three patients by three months, one patient by nine months, and three patients had low and normal values throughout the study. No consistent correlation of individual patient's erythrocyte GSH-Px activities and erythrocyte selenium levels existed, but a positive correlation (r = 0.51, p less than 0.01) occurred between plasma selenium levels and erythrocyte GSH-Px activities. Thus, erythrocyte GSH-Px activities decrease parallel to decreases in plasma selenium levels but not with changes in erythrocyte selenium levels. These data suggest that some of these IVH patients may be at risk for selenium deficiency and that selenium supplementation of IVH solutions may be required. Furthermore, these data suggest that the measurement of erythrocyte GSH-Px activity or selenium levels in some IVH patients may not be related to available body selenium.

Adult↗
PubMedDate not supplied

Selenium depletion in burn patients.

Victims of major burns may be at risk for selenium (Se) depletion because increased postinjury nutrient needs are often met by total parental nutrition and tube feedings which contain little Se. This study compared Se status of 17 burn patients and 191 healthy control subjects. Se intake of burn patients was lower than the intake of control subjects when total parenteral nutrition or tube feedings were used as primary nutrient sources but was comparable to the control intake when burn patients consumed oral diets. Serial determinations each 10 days during recovery showed that burn patients had lower plasma Se, erythrocyte Se, and erythrocyte glutathione peroxidase levels, and lower 24-hr urine Se excretion. These results provide biochemical evidence of Se depletion despite exogenous Se intake within the range recommended for healthy adults. Further studies are indicated to determine if Se depletion in burn patients can be prevented by Se supplementation of total parenteral nutrition and tube feeding solutions.

Adult↗
PubMedDate not supplied

The effect of selenium supplementation on selenium status of patients receiving chronic total parenteral nutrition.

Patients receiving long-term total parenteral nutrition (TPN) are at risk for selenium deficiency. The purpose of this study was to determine the effect of parenteral selenium as selenious acid on the selenium status of seven long-term TPN patients. Patients received a dosage of zero, 80, or 160 micrograms Se/day for 1 month each. The measures of selenium status used were selenium levels in plasma and glutathione-peroxidase activities in erythrocytes and platelets. Urinary selenium excretion was measured. Control subjects were selected to match the sex, age, and weight of the patients. With increasing levels of parenteral selenium, there was increasing plasma selenium concentration as well as erythrocyte and platelet glutathione-peroxidase activity. There was no statistical difference between the patients during the time they received the 160 micrograms parenteral selenium treatment and the control subjects for platelet glutathione-peroxidase activity. At the 160 micrograms Se/day level, patient plasma selenium concentrations increased from 28% to 58% of the control levels. Four patients were studied after they returned to the 80 micrograms parenteral selenium/day from the 160-micrograms Se/day treatment. With decreasing parenteral selenium, three patients had decreasing platelet glutathione-peroxidase activity, while plasma selenium concentration decreased in two patients. These data suggest that some patients receiving long-term parenteral nutrition should receive parenteral selenium.

Adult↗
PubMedDate not supplied

Oral branched-chain amino acids decrease whole-body proteolysis.

BACKGROUND: This study reports the effects of ingesting branched-chain amino acids (leucine, valine, and isoleucine) on protein metabolism in four men. METHODS: To calculate leg protein synthesis and breakdown, we used a new model that utilized the infusion of L-[ring-13C6]phenylalanine and the sampling of the leg arterial-venous difference and muscle biopsies. In addition, protein-bound enrichments provided for the direct calculation of muscle fractional synthetic rate. Four control subjects ingested an equivalent amount of essential amino acids (threonine, methionine, and histidine) to discern the effects of branched-chain amino acid nitrogen vs the effects of essential amino acid nitrogen. Each drink also included 50 g of carbohydrate. RESULTS: Consumption of the branched-chain and the essential amino acid solutions produced significant threefold and fourfold elevations in their respective arterial concentrations. Protein synthesis and breakdown were unaffected by branched-chain amino acids, but they increased by 43% (p < .05) and 36% (p < .03), respectively, in the group consuming the essential amino acids. However, net leg balance of phenylalanine was unchanged by either drink. Direct measurement of protein synthesis by tracer incorporation into muscle protein (fractional synthetic rate) revealed no changes within or between drinks. Whole-body phenylalanine flux was significantly suppressed by each solution but to a greater extent by the branched-chain amino acids (15% and 20%, respectively) (p < .001). CONCLUSIONS: These results suggest that branched-chain amino acid ingestion suppresses whole-body proteolysis in tissues other than skeletal muscle in normal men.

Adult↗
PubMedDate not supplied

Proposed mechanisms for selenium-inhibition of mammary tumorigenesis (review).

Both the reduced and oxidized forms of selenium are available at various rates through a common selenium pool for incorporation into selenoproteins, of which glutathione peroxidase is the best studied. Dietary selenium as selenite and selenomethionine decreased the incidence of rodent mammary tumorigenesis. The postulated mechanisms of this inhibition includes alterations in the level of GSHPX, membrane peroxidation, glutathione, immune functions, induction of specific selenoproteins, alterations of carcinogen metabolism, and the effect of various chemical forms of selenium. After many studies the mechanism of action of selenium in the inhibition of mammary tumorigenesis is still unknown, although studies of the role of selenoproteins appears the most promising.

Animals↗