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Biomedical subjects

R T Hughes

Publications and source records attributed to R T Hughes.

13 recordsLinked to original sources
PubMed1992

Regulation of iron absorption in iron loaded subjects with end stage renal disease: effects of treatment with recombinant human erythropoietin and reduction of iron stores.

The effects on iron absorption of variation in erythroid activity, haemoglobin and iron stores were studied in six anaemic dialysis-dependent subjects in whom iron stores were increased from previous red cell transfusions. Gastrointestinal mucosal uptake and whole body retention of oral iron were measured at the beginning of the study, after starting treatment with recombinant erythropoietin (but before significant increase in haemoglobin), after partial correction of anaemia, after further reduction of iron stores by repeated phlebotomy, and when erythropoiesis decreased from the discontinuation of treatment with erythropoietin. Between successive measurements, valid comparisons were made in five subjects. Correction of anaemia decreased whole body retention of iron through decreased mucosal uptake (P = 0.032). Further reduction in iron stores through repeated phlebotomy whilst the increase in haemoglobin was maintained by treatment with erythropoietin, tended to increase whole body retention of iron through an increase in mucosal transfer (P = 0.010). With initial enhancement of erythropoiesis in anaemic iron-loaded subjects there was no change in any measured component of iron absorption. However, after correction of anaemia and reduction of iron stores, a decrease in erythropoiesis was associated with decreased whole body iron retention in all subjects through decreased mucosal transfer (P = 0.028). The data suggest that anaemia upregulates mucosal iron uptake, and that erythroid activity upregulates mucosal transfer but that this latter effect may be counter-balanced by iron overload which downregulates mucosal transfer.

Adult↗
PubMed1991

Stepwise correction of anaemia by subcutaneous administration of human recombinant erythropoietin in patients with chronic renal failure maintained by continuous ambulatory peritoneal dialysis.

Sixteen anaemic CAPD patients (Hb less than 9 g/dl) were treated with thrice-weekly subcutaneous recombinant erythropoietin, epoetin-alfa. The dose was adjusted to induce a stepwise increase in haemoglobin. Fourteen patients reached a first target haemoglobin of 11.0-11.5 g/dl and eight of these a second of 13.0-13.5 g/dl, but one could not be maintained at this level. Failure to reach or maintain the second target in nine subjects was accounted for by incomplete responses associated with infection in one, extreme shortening of red-cell survival in another, and was unexplained in one subject. These three received the maximum dose studied of 450 IU/kg per week. Six other subjects were withdrawn from the study for reasons unrelated to treatment with erythropoietin. The median dose required to maintain the haemoglobin at 11.0-11.5 g/dl was 75 IU/kg per week and at 13.0-13.5 g/dl was 150 IU/kg per week. Quality of life, assessed in 12 patients at haemoglobin 11.0-11.5 g/dl, showed significant improvement in energy, and at 13.0-13.5 g/dl improvements in sleep and emotional wellbeing became significant. Twelve subjects required either institution of, or an increase in, treatment for hypertension. The thrice-weekly subcutaneous doses of erythropoietin were well tolerated and were a convenient and effective treatment for anaemia in patients on CAPD.

Adult↗
PubMed1990

Subcutaneous administration of recombinant human erythropoietin to subjects on continuous ambulatory peritoneal dialysis: an erythrokinetic assessment.

Erythrokinetic studies were performed in subjects on continuous ambulatory peritoneal dialysis, during a trial examining the effectiveness of subcutaneous administration of recombinant human erythropoietin (r-HuEPO) in correcting the anaemia associated with end stage renal disease. 15 subjects (mean haemoglobin concentration 6.9 g/dl, SD 1.1) entered the study, and during treatment 9 were restudied at a haemoglobin concentration of 11-11.5 g/dl and six underwent a third study at haemoglobin 13-13.5 g/dl. By adjusting the dose of r-HuEPO, a stepwise increase in haemoglobin concentration was achieved, and this was accompanied by increases in total red cell volume and erythron transferrin uptake. Plasma volume decreased as red cell volume increased, leaving total blood volume essentially unchanged. Red cell survival, modestly reduced before treatment (mean 64, range 44-96 d, n = 6) tended to increase during treatment and when subjects were retested at a haemoglobin concentration of 13-13.5 g/dl (after 38-62 weeks treatment), the mean increase in red cell survival was 20 d (95% confidence interval 1-39 d). Thus subcutaneous r-HuEPO is effective in correcting the anaemia of end stage renal disease when administered thrice weekly to subjects on continuous ambulatory peritoneal dialysis. It produces an increase in haemoglobin concentration primarily by expanding the erythron, and may have a secondary effect, seen after several months of treatment, of increasing red cell survival.

Adult↗
PubMed1986

Improved local exhaust control by directed push-pull ventilation system.

Experiments using the directed push-pull ventilation technique were conducted on a general type of local exhaust ventilation installation. The exhaust (pull) system consisted of a square hood, while the push system consisted of one or two slot jets or two round jets. The two slot or round jets were located behind and beside a mannequin (the mannequin simulated the worker's position). The one slot jet was located between the smoke source and the mannequin. Under experimental conditions, the push-pull system reduced the amount of smoke in the mannequin's breathing zone even when the exhaust system volume flow rate necessary for capture of the smoke decreased approximately 50%. Generally, no difference between the slot and round jet control performance was found. The experiments showed that the directed push-pull ventilation system can be used effectively to reduce the contaminant emission into a workroom, if the jets are located so that the eddy currents induced by the worker or other obstructions are minimized or eliminated.

Humans↗
PubMed1986

Evaluation of building ventilation systems.

Over the past several years, NIOSH has responded to health hazard evaluation requests from workers in dozens of office environments. Typically, the employees have complained of headache, eye and upper respiratory tract irritation, dizziness, lethargy and the inability to concentrate. Most often "inadequate ventilation" has been blamed for these complaints. Of paramount importance in the evaluation and correction of these problems is an effective evaluation of the building's ventilation system. Heating, ventilating and air-conditioning conditions that can cause worker stresses include: migration of odors or chemical hazards between building areas; reentrainment of exhaust from building fume hoods or through heat wheels; buildup of microorganisms in the HVAC system components; and poor odor or environmental control due to insufficient "fresh" outdoor air or system heating or cooling malfunction. The purpose of this paper is to provide an overview of building ventilation systems, the ventilation problems associated with poorly designed or operating systems, and the methodology for effectively evaluating system performance.

Air Conditioning↗
PubMed1985

Development of push-pull ventilation.

Push-pull ventilation (air is blown across a contaminant generation area toward an exhaust hood) can have distinct advantages over exhaust ventilation alone. It can control contaminant emission into the workplace better than exhaust only, and much less conditioned air must be exhausted so there are energy savings. This paper presents suggested push and pull flow rates for open surface tank operations such as plating. About 98% of the contaminant generated can be captured by a push-pull system using the proper flow rates.

Ethanol↗