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Biomedical subjects

S Shaldon

Publications and source records attributed to S Shaldon.

At least 109 records · Page 6Linked to original sources
PubMed1987

Beta 2-microglobulin kinetics during haemodialysis and haemofiltration.

Since the identification of beta 2-microglobulin as a major component of 'dialysis amyloid', concern about its removal by different dialysis methods has been raised. Haemodialysis with regenerated cellulose membranes increases serum beta 2-microglobulin by 10-15%. Serial measurements show a very early increase during cuprophan haemodialysis, the mechanism of which is as yet unknown. After cuprophan haemodialysis, serum values return to the initial pretreatment concentrations by the time of the next haemodialysis. In contrast to regenerated cellulose, dialysis with polycarbonate lowers serum beta 2-microglobulin by 8%, and dialysis with polysulphone by 53%. As opposed to cuprophan, after polysulphone haemodialysis the serum concentrations have not returned to the initial pretreatment levels within 48 h. Comparison of beta 2-microglobulin removal using the same polysulphone membrane for haemodialysis and haemofiltration shows that beta 2-microglobulin is more effectively removed by convection than by diffusion when both treatment modes are matched for blood flow and urea clearance. Therefore, in contrast to haemodialysis with regenerated cellulose membranes, where a transient, intradialytic release of beta 2-microglobulin is induced, significant removal is observed using higher permeable membranes. These findings may have implications for the generation of 'dialysis amyloid'.

Adult↗
PubMed1987

Plasma interleukin-1 activity in humans undergoing hemodialysis with regenerated cellulosic membranes.

Because of the similarity between the acute phase response and the post-hemodialysis syndrome, it has been proposed that human blood monocytes adhering to the hemodialysis membrane are exposed to several inducers of interleukin-1 (IL-1). These include endotoxin from the dialysate fluid and C5a activated on the surface of regenerated cellulosic hemodialysis membranes. In order to test this hypothesis, we measured IL-1 plasma activity by employing gel filtration to remove IL-1 inhibitors and subsequent augmentation of lectin-induced murine thymocyte proliferation in each fraction. To evaluate the acute response of end stage renal disease patients during a single hemodialysis with a regenerated cellulosic membrane, plasmas were tested before and after hemodialysis. Control plasmas were obtained from healthy individuals. Plasma IL-1 activity eluted at a molecular weight of predominantly 15 kD. This material was neutralized by anti-human-IL-1 which does not recognize IL-2. IL-1 activity was detected in the pre-dialysis plasma of 6 out of 7 patients and rose in 6 patients following a 5 hour hemodialysis. This increase was associated with a significant rise in body temperature. This study supports the hypothesis that hemodialysis with regenerated cellulose might augment IL-1 production in endstage renal disease patients maintained on longterm hemodialysis. It demonstrates for the first time that dialysis patients have detectable plasma levels of IL-1 compared to normal individuals.

Adult↗
PubMed1986

Future trends in biocompatibility aspects of hemodialysis and related therapies.

Biocompatibility is redefined as the quality of being mutually tolerant with life. In so far as this represents a quality which is as likely to be achieved as is the alchemist's dream of turning lead into gold, a compromise approach is recommended. It is suggested that all extracorporeal or body invasive procedures stimulate the inflammatory defense mechanism of the body by stimulating the monocyte to produce a family of polypeptides currently known collectively as Interleukin-1 (IL-1). So far two dissimilar gene products have been cloned and there are probably more. The IL-1 group of polypeptides possess hormonal functions which orchestrate nearly every instrument of the body's defense system. Inducers of IL-1 are present in dialysate and include bacterial pyrogen and acetate. In addition bacterial cell wall glycoprotein may be cleaved into muramyl dipeptides by the release of granulocyte lysozyme at the membrane interface. Muramyl dipeptides have been found in CAPD drain fluid and are more potent inducers of IL-1 than endotoxin. Membrane activation of the fifth component of complement with the release of C5a will also induce monocytes to produce IL-1. The consequences of repeated stimulation of the acute phase response are undesirable and may include muscle wasting, osteopenia and bone cysts (Shrinking man syndrome), fibrosis of scapulo-humeral joints and the carpal-tunnel syndrome. These latter lesions are often associated with deposition of amyloid fibrils related to beta 2 microglobulin. Efforts to reduce these complications are urgently required.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1983

[Hypoxemia in hemodialysis: hemodynamic mechanism? Hemodynamic and spirometric study using acetate and bicarbonate buffers].

The background of this study is the occurrence during acetate hemodialysis (HDA) of arterial hypoxemia associated with well described vasodilatator hemodynamic changes. Our aim was to evaluate the relationship between these 2 phenomena. Eleven patients (7 males, 4 females, mean age 54 years) were compared in a protocol of HDA and bicarbonate hemodialysis (HDB) as regards their cardiac output measured by the dye dilution method, blood gases and respiratory gas measurements made at the bedside. The results show significant hypoxemia with hypocapnia as soon as the 30th minute of HDA and no significant variation of cardiac index. No significant variation of respiratory response was noted. Arterial prostaglandin levels rose significantly higher during HDA (+ 302%) than HDB (+ 163%; 2 alpha less than 0,05). The absence of a correlation between arterial hypoxemia and hemodynamic changes in HDA compared to HDB suggests that the phenomena are not interdependent. The importance of increased thromboxane activation in HDA will require further investigation.

Acetates↗
PubMed1983

Hemodynamics in hemofiltration.

To study the established but not well understood phenomenon of improved intratreatment vascular stability during hemofiltration the same 10 stable hemodialysis patients were investigated during one hemodialysis and one hemofiltration treatment. Both treatments were matched in regard to linear fluid withdrawal (3 kg/240 minutes), small molecule removal rate (Curea 120 ml/min). Sodium (140 meq/l) and acetate (35 meq/l) concentration in dialysate and replacement fluid were identical. Outcome measures included mean arterial blood pressure, total peripheral vascular resistance by thermodilution, plasma noradrenaline concentration as index of sympathetic activity and sodium loss per treatment. Blood pressure was maintained during hemofiltration, while total peripheral vascular resistance and plasma noradrenaline concentrations increased. During hemodialysis mean arterial blood pressure fell significantly, total peripheral resistance and plasma noradrenaline concentrations remained unchanged. During both treatment modalities sodium loss was comparable. It is concluded, that the improved hemodynamic stability during hemofiltration is due to a maintained physiologic response to ultrafiltration, which is impaired during hemodialysis. Vascular stability during hemofiltration is not due to sodium retention relative to hemodialysis.

Adult↗