PubMed Health⌕ Search

Biomedical subjects

J B Goldcamp

Publications and source records attributed to J B Goldcamp.

11 recordsLinked to original sources
PubMed1993

Evaluation of a relationship between polymer bulk hydroxyl and surface oxygen content and in vitro serum-material interaction.

To evaluate serum-material interaction for six types of minimodule and to assess the relationship between the interaction and chemical composition, notably bulk polymer hydroxyl (-OH) percent of polymer, or surface oxygen (SO) percent, polymeric membranes with varying -OH and SO percents were evaluated with normal human serum. The membrane materials (-OH percent and SO percent) evaluated included polypropylene (PP; 0% and 1.9%), polyvinyl alcohol (PVA; 23.7% and 27.3%), ethylene vinyl alcohol (EVAL 4A and D; 30.4% and 25.3%), Cuprophan (CP; 31.5% and 37.4%), and Hemophan (HP; 30.9% and 23.6%), respectively. Data from serum perfusions expressed as percent changes to sham perfusion showed that solute percent decreases were less than 10% in all materials except PVA (10-22%). PVA and CP had higher C3a, C4a, and C5a, and C3a concentration increases, and had larger suppressive effects for all three mitogen-induced mononuclear cell transformation functions (MNCTF) and concanavalin A-induced MNCTF, respectively. PVA had higher SO percent than EVAL and CP was higher than HP, despite PVA and CP having lower or comparable bulk -OH percent to EVAL or HP. The results obtained in the serum material interaction studies related more with the SO percent of the polymer rather than bulk -OH percent. The differences for C4a and PHA-induced MNCTF observed between the two EVAL membranes may be associated with significantly different pore size and therefore different surface structural properties. These results suggest that surface chemical (SO percent on the materials) and structural property analyses are important factors in biocompatibility parameter studies.

Biocompatible Materials↗
PubMed1992

Selective removal of cholesterol by plasmapheresis and the progression of atherosclerosis.

There is a strong correlation of plasma cholesterol levels with the risk of coronary heart diseases as shown by epidemiologic studies. This study was undertaken to evaluate the effect of plasma cholesterol lowering on the progression of atherosclerosis in the homozygous Watanabe heritable hyperlipidemic (WHHL) rabbit. The effect of cholesterol lowering, which was accomplished by thermofiltration (on-line plasma separation with plasma filtration at 39 degrees C) was evaluated by comparison between treated and untreated control groups. Thermofiltration reduced significantly the mean plasma level of total cholesterol (284 vs. 655 mg/dl, P = 0.0005) and the percent aortic area occupied by atherosclerotic plaque (15.0 vs. 44.2%, P = 0.0003). The total lipid and cholesterol contents in the aortas in the treated group were also significantly lower than those in the control group. Microscopically, thickness measurements of the lesions showed that the mean thickness of the fibrous cap and the ratio of the thickness of the intima to that of the media were smaller for the treated group than the control group. This study demonstrated the slowing or stopping of the progression of atherosclerosis by lowering the plasma total cholesterol level in WHHL rabbits.

Animals↗
PubMed1991

Immunomodulating effects of serum-material interactions.

The objective of this study is to evaluate an in vitro model to assess the effects of serum-material interactions on complement activation, macromolecular adsorption, and lymphocyte response. Minifilters of clinically available materials (PVA, EVAL-4A, and EVAL-D) used in extracorporeal therapies were evaluated. The test circuit consisted of a pump, sterile tubing, collection vessels, and the minifilter. A sham circuit similar to the test circuit was constructed, but without the filter. Serum flow rates and volumes processed were scaled down to those of clinical use. Post PVA serum showed the highest degree of complement activation, macromolecular solute adsorption, and lymphocyte suppressive response when incubated with Con-A, PHA, PWM, and Candida. Post EVAL-4A sera enhanced the response of lymphocytes to Con-A and PHA, while Post EVAL-D sera showed a slight suppression to these mitogens. Blood-material interactions have been shown to cause blood cellular changes. The in vitro model employed is simple to apply and does not require an animal or patient. The membrane modules used are a mini-type of clinically available extracorporeal filters, and there is a greater direct relevancy to clinical applications than there would be using specially formulated materials. This system would provide useful preclinical information in evaluating the effect of serum-material interactions.

Blood Physiological Phenomena↗
PubMed1991

Effects of single-dose infusion of pyridoxalated-hemoglobin-polyoxyethylene conjugate solution on canine renal function.

Pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP) is an acellular oxygen-carrying red blood cell substitute made from outdated human red blood cells. This study assessed the effect of PHP on renal function when PHP was infused with a clinically relevant dosage. A single dose of PHP that contains 8% wt/vol each of hemoglobin and maltose or an 8% maltose control solution was infused into the intact circulation of eight dogs (five dogs for PHP and three for the control; 20 ml/kg each, at the rate of 2.5 ml/h/kg for 8 h) in the awake state. Serial measurements of glomerular filtration rate (GFR) and renal plasma flow (RPF) were carried out before and after infusion for up to 2 weeks, along with determinations of urine volume flow rate, fractional excretion of sodium (FES), and free water clearance (CH2O). The results showed an elevation of plasma colloid osmotic pressure by an average of 4.4 mm Hg immediately postinfusion with PHP solution. An average 23% decrease in GFR, without notable changes in RPF immediately postinfusion, was observed in the PHP group; the value returned to the preinfusion level by 1 week postinfusion. Increases in parameters such as urine output, FES, and CH2O, which were more pronounced in the PHP group, were observed for 24 h after the infusion in both groups. Light microscopic examination of kidney specimens taken at 2 weeks postinfusion revealed a slight degree of vacuole formation in approximately 80% of the proximal tubules in the PHP group. The tubules were devoid of typical pathologic features of acute renal failure, and the vacuoles did not cause any observable changes in the assessed tubular functions.

Animals↗
PubMedDate not supplied

Evaluation of materials for use in extracorporeal circulation. In vitro serum-material interaction.

Polymeric membranes used in extracorporeal circulation procedures of varying hydroxyl (-OH) percent were evaluated with normal human serum to detect differences between chemical composition and serum-material interactions. The materials were evaluated as hollow fibers built into modules, including polypropylene (PP; 0%), polyvinyl alcohol (PVA; 23.7%), ethylene vinyl alcohol (EVAL; 29.7%), Cuprophan (CP; 31.5%), and Hemophan (HP; 30.9%). Data from serum perfusions expressed as percent changes to sham (circuit minus module) showed that solute % decreases were from 0% to 10% in all materials except for PVA (10-22%). Complement activation product % increases were higher with PVA (606-4309%) and CP (48-567%), and mononuclear cell transformation functions (MNCTFs) were more suppressed with PVA (100 to 98%) and CP (10-18%). Despite EVAL and HP having an -OH %, complement activation products were relatively low with EVAL (less than 212%), HP (less than 13%), and PP (less than 131%). MNCTFs were stimulatory with the co-polymer of vinyl alcohol and ethylene (EVAL), and very suppressed by serums from PVA contact. Ethylene vinyl alcohol and modified cellulose (HP) had reduced complement activation despite higher or comparable bulk -OH. Bulk -OH content alone cannot explain the differences observed.

Biocompatible Materials↗
PubMedDate not supplied

Effects of prostaglandin I2, superoxide dismutase, and catalase on ischemia-reperfusion injury in liver transplantation.

This study evaluated the effects of a prostaglandin I2 analogue (aPGI2), superoxide dismutase (SOD), and catalase (CAT) on hepatic injury after warm ischemia and reperfusion in terms of survival, mitochondrial function, serum enzymes, and histology. Hepatic ischemia was created in rats by clamping the hepatoduodenal ligament for 90 min with splenofemoral bypass. Reperfusion was induced by unclamping the vessels and disconnecting the splenofemoral bypass. Then aPGI2 (350 ng/kg/min) was infused for 60 min just before hepatic ischemia, and SOD and CAT (5,000 units/kg each) were administered immediately before the start of reperfusion. Serum enzyme and mitochondrial function assessments of livers were made just after ischemia, and after 2 hr of reperfusion. Survival rate was also assessed in a separate group of rats. Liver enzymes such as SGOT, SGPT, and LDH showed no correlation to liver viability. The administration of aPGI2 alone showed no effect on ischemically injured mitochondria; however, the free radical scavengers (SOD, CAT), in combination with aPGI2, showed significant improvement of mitochondrial function together with extension of survival. The ultrastructure of hepatocytes was better preserved in the treated groups. These agents improved the viability of ischemic-reperfused injured livers.

Alanine Transaminase↗
PubMedDate not supplied

Anticoagulant and membrane effects on humoral and cellular changes during plasmapheresis.

Heparin (H) and citrate (C) anticoagulation with cellulose acetate (CA) and polyvinyl chloride (PVC) membrane devices were evaluated on three myasthenia gravis patients. Changes of white blood cell (WBC) and platelet (PLT) counts, complement activation, granulocyte elastase, and interleukin-1 beta (IL-1 beta) were studied sequentially. Changes in WBC and PLT counts were more dependent on the membrane material and surface area. Changes of C3a and C5a were more related to the anticoagulant used, whereas changes of C4a were membrane-material dominant phenomenon. Systemic elastase levels did not show significant differences among the groups but module outlet values were elevated for Ca + H. IL-1 beta did not show changes in all schemes. CA + H was the most activating and PVC + C was the least activating combination. Both the membrane materials and anticoagulant must be considered in evaluating humoral and blood cellular changes in plasmapheresis.

Blood Cell Count↗