Search PubMed⌕ Search

Biomedical subjects

J Bommer

Publications and source records attributed to J Bommer.

At least 73 records · Page 4Linked to original sources
PubMed1987

Determinants of plasma beta 2 microglobulin concentration: possible relation to membrane biocompatibility.

Beta 2 microglobulin (beta 2m) concentrations were measured by radioimmunoassay in the serum of haemodialysed patients. beta 2m was higher in males (n = 48) than in females (n = 26), i.e. 40.3 +/- 10.1 mg/l (SD) vs 31.2 +/- 8.0, P less than 0.01). beta 2m was not significantly higher in patients with bone cysts (37.7 +/- 11.4 mg/l vs 37.0 +/- 10.0), but median duration of dialysis was significantly (P less than 0.01) longer in patients with bone cysts (90 vs 57 months). beta 2m was lower in patients maintained on dialysis for less than 1 year and whose residual urine volume was greater than 0.1 litre per day. During one single session of dialysis, using cuprophane membranes, beta 2m increased acutely at 15 min and had risen by 32.4% at the end of the dialysis session, more than could be explained by haemoconcentration. In contrast, beta 2m acutely decreased by 38.7% during a single session using polysulphone membranes and the steady state predialysis values were lower by 37.1% after two weeks intermittent haemodialysis with polysulphone membranes. After re-exposure to cuprophane serum beta 2m increased to the original value. It is concluded that beta 2m concentrations on dialysis are a function of residual urinary volume, sex, and type of membrane used. Data are consistent with effective removal of beta 2m by membranes with high cut-off.

Biocompatible Materials↗
PubMed1987

Recombinant human erythropoietin therapy in haemodialysis patients--dose determination and clinical experience.

Recombinant human erythropoietin (R-Hu-EPO) was given to stable, long-term haemodialysis patients with haematocrit less than or equal to 25% who required no blood transfusions. Thirteen patients were initially given R-Hu-EPO at 24 U/kg i.v. at the end of each dialysis session, with a doubling of the dose every second week until a dose of 96 U/kg (n = 6) or 192 U/kg (n = 7) was reached after 8 weeks. In addition, three patients were given 24 U/kg for 2 weeks and subsequently 48 U/kg for 14 weeks. Median haematocrit increased from 19.4% (14.8-24.3) to 30.0% and 32.5% with 96 or 192 U/kg respectively. Starting 7 days after R-Hu-EPO a log dose-dependent increase in reticulocyte counts was noted. A consistent decrease in ferritin concentrations was observed despite oral supplementation of iron. A continuous rise in platelet counts was noted. Irrespective of blood-pressure status, predialysis blood pressure increased in six of nine patients who were not on antihypertensive medication; increased antihypertensive therapy was required in the others. A rise in bilirubin within the normal range was seen at the end of the study. No severe clinical side-effects occurred; specifically, there were no thrombotic episodes with the exception of clotting of two fistulae with known stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

No evidence for endotoxin transfer across high flux polysulfone membranes.

Recently, there has been some concern that high-flux membranes may expose dialysis patients to the risk of endotoxin transfer secondary to backfiltration within the dialyzer. To evaluate the safety of high-flux polysulfone dialyzers, we examined in an in vitro recirculation system whether lipopolysaccharides (LPS) and lipid A respectively penetrate from the dialysate to the blood compartment and vice versa using a F-60 hemofilter (Fresenius AG). For the detection of endotoxin, a sensitive, kinetic limulus amebocyte lysate (LAL) microtiter test was used. It can be concluded that LPS and lipid A do not pass from either side through the filter system used when saline was recirculated for more than 10 h on both sides of the membrane.

Blood↗
PubMed1986

[Problems of biocompatibility in hemodialysis treatment].

Although hemodialysis is one of the best examined, and clinically best established, methods of patient treatment with artificial organs, a number of biocompatibility problems remain. This review discusses the problem of water quality. Recently, much concern has been focused on potential longterm risks from patients exposure to subthreshold concentrations of endotoxin in dialysate. Further problems comprise inorganic and organic contaminants, some of which with potential carcinogenetic hazards. Complement activation by, and thrombogenicity of, dialysis membranes have not been eliminated. Presumably, the hazards of complement activation are less acute shortterm reactions (which according to more recent studies appear to be ETO-related anaphylactoid reactions) but rather potential longterm hazards, e.g. beta 2 m related amyloid. However, the issue is not settled since we have recently found cell activation by dialysis membranes even in the absence of complement. Apart from membranes, dialysis tubing presents hazards, e.g. leakage of plasticizers and release of oligomers or radicals. The recognition of ETO as a potent immunogen, inducing antibodies detectable in approximately 40% of the dialysis population, will require to replace ETO as a sterilisant for dialysis devices. This demand is even more urgent in view of the recognized carcinogenicity of this alkylating agent.

Biocompatible Materials↗
PubMed1986

Amyloid kidney stones of uremic patients consist of beta 2-microglobulin fragments.

Urinary stones with amyloid structure, obtained from uremic patients, were analyzed according to molecular weight, amino acid sequence, and antigenic content. A major protein of approximately 7 kD, designated AB protein, was isolated by size exclusion using HPLC in 60% formic acid. AB protein reacted in immunodiffusion only with an antiserum to beta 2-microglobulin, with beta 2m spurring over AB protein. N-terminal amino acid sequence analysis defined two fragments homologous to beta 2m. One fragment commenced with Ile at position 7 and the other with Ser at position 20, with a cleavage point subsequent to a lysyl residue in both. It is concluded that beta 2m is a precursor of urinary amyloid stones and intratubular concretions of patients with preterminal and terminal renal failure; limited proteolysis is involved in AB amyloid generation.

Amino Acid Sequence↗
PubMed1986

Immunogenicity of recombinant hepatitis B vaccine in dialysis patients.

Eighty-eight dialysis patients were vaccinated with recombinant hepatitis B vaccine prepared in yeast. Fourty-nine patients were immunized 3 times (months 0, 1, 6) intragluteally with 40 micrograms hepatitis B surface antigen (HBsAg) per dose. Only 32 of them (65.3%) showed anti-HBs concentrations above 10 IU/l with a geometric mean titer (GMT) of 180.7 IU/l after 3 vaccinations, whereas all of the 16 healthy controls, vaccinated 3 times with a 10-micrograms dose of the same vaccine batch, had specific antibodies higher than 10 IU/l (GMT 897.4 IU/l). Responses of patients were slightly higher than those of dialysis patients vaccinated in an earlier study with plasma-derived vaccine according to the same schedule. Results in 20 patients immunized 6 times intragluteally with 40 micrograms HBsAg/dose in monthly intervals were not better (at month 7, 65% showed anti-HBs concentrations greater than 10 IU/l; GMT = 126.6 IU/l), and 19 patients receiving 6 times 20 micrograms HBsAg monthly showed significantly lower responses (anti-HBs greater than 10 IU/l in 42% of vaccinees, GMT = 89.5 IU/l). The vaccine was tolerated well; side-effects were slight, and no serious adverse reactions were observed. In conclusion, recombinant hepatitis B vaccine is comparable to plasma-derived vaccine also in the case of dialysis patients; a 6-dose schedule does not seem to have much advantage compared to the conventional 3-dose regimen.

Adult↗
PubMed1986

Dialysis membranes and coagulation system.

Artificial membranes used for hemodialysis differ from endogenous membranes, i.e. endothelial cells, by their variable thrombogenicity. The key step in activation of the coagulation system by dialysis membranes is thrombocyte activation which is preceded by formation of a protein layer of critical thickness. Crucial questions concerning the quality of this protein membrane as a determinant of thrombocyte activation are not well understood. Activation of the contact phase of the intrinsic plasmatic coagulation system by dialysis membranes is well documented. Local action of thrombin in the membrane microenvironment is documented by release of fibrinopeptide A and deposition of fibrin on the membrane. Apart from thrombin, other mechanisms, e.g. PMN elastase, plasma-independent activation of blood cells, facilitatory action of erythrocytes etc., may play a contributory role. With respect to the polycarbonate membrane, some authors find less platelet extraction and unchanged platelet release reaction. In our own studies, polycarbonate membranes were not superior to cuprophane membranes with respect to thrombogenicity.

Animals↗
PubMed1986

Different in vitro generation of C3d by cuprammonium and polycarbonate capillary hemodialyzers.

Cellulosic membranes have been shown to activate C3 via the alternative pathway. Generation of the stable product C3d was compared in polycarbonate (PC) and cuprammonium (CU) hollow-fiber minidialyzers with identical geometry, using an in vitro recirculation system with platelet-poor plasma (recirculation rate 20 ml/min; 1,600 fibers; 0.115 m2; 40 ml system priming volume; recirculation time 120 min). After extensive washing, residual protein was removed by reverse transmembrane pressure (1.5 bar) from the air-filled dialysate compartment. Such protein fraction, functionally defined as 'secondary membrane', was similar in quantity for PC and CU fibers. Plasma proteins were present in the membrane without selective adsorption (flat-bed polyacrylamide gel electrophoresis and rocket immunoelectrophoresis using monospecific antibodies). C3d, measured by immunoelectrophoresis, increased with time in the fluid phase compartment of both dialysers, but C3d generation was consistently and significantly (p less than 0.05) less in PC than in CU dialysers. The observation documents an activation of C3 with PC, in contrast to previous reports of no activation. However, C3 activation with PC was less intense than with CU.

Adsorption↗
PubMed1985

Treatment of hypertension in dialysis patients.

Hypertension is common in hemodialyzed patients and constitutes an important cardiovascular risk factor. Fluid retention, inappropriate stimulation of the renin-angiotensin system, sympathetic overactivity and changes of vessel wall structure have been shown to be important factors in its pathogenesis. It has been claimed that hemofiltration permits a better control of hypertension in the interdialytic interval, although the evidence is not perfectly convincing; blood pressure tends to be lower with continuous ambulatory peritoneal dialysis. While fluid withdrawal and - within certain limits - adjustment of dialysate sodium concentration constitutes a primary line of therapy, antihypertensive medication is necessary in approximately 20% of patients. Specific problems with dialysis patients are cumulation of drugs (some cardioselective beta-blockers, alpha-methyldopa, captopril), altered dose-response relationship (diuretics) and particularly interaction with cardiovascular stability during fluid withdrawal.

Adolescent↗
PubMed1985

Response of alkaline phosphatase to zinc repletion in hypozincemic hemodialysis patients.

The response of serum alkaline phosphatase (AP), a zinc-dependent metalloenzyme, to zinc administration via the dialysate (400 micrograms/l) was examined in 14 hypozincemic (less than 30th percentile of dialysis patients) hemodialysis patients and in 14 placebo-treated matched dialysis control patients. Plasma zinc and serum AP were measured three times: prior to, once weekly during (5 weeks), and 2 weeks after addition of zinc to the dialysate. The serum zinc levels remained stable in placebo-treated controls (initial 87.7 +/- 12.5; final 78.6 +/- 8.3 micrograms/dl) and increased in zinc-treated patients (initial 76.4 +/- 8.3; 5th week 96.9 +/- 13.3; 2 weeks after zinc withdrawal 82.3 +/- 12.2 micrograms/dl). There was a slight increase of AP with time in placebo controls (initial 90.2 +/- 26.5; 5th week 100 +/- 29 U/l) and a more pronounced increase in zinc-treated patients (initial 90.8 +/- 19.9; 5th week 113 +/- 20.9 U/l). The difference between the two groups was marginally significant (p less than 0.05; analysis of variance). It is concluded that zinc repletion via dialysate with documented increase of serum zinc levels in initially hypozincemic dialysis patients causes a reversible increase of serum AP. The result is compatible with some tissue zinc deficiency in hypozincemic dialysis patients.

Adult↗
PubMed1985

Evidence for macrophage activation in dialysis patients exposed to silicone filing.

Spleen cell suspensions of 2 dialysis patients with hepatosplenomegaly and pancytopenia were studied in vitro. Spleen cells of a cadaver kidney donor were studied as control. In spleen macrophages of the patients, silicone particles could be demonstrated with TEM and electron microprobe analysis. Under basal conditions and after stimulation with zymosan and concanavalin A, release of PGE2, TXB2 and 6-keto-PGF1 alpha from patient cells was higher than control cells. This anecdotal observation parallels previous animal studies and suggests that loading of human macrophages with foreign material particles activates arachidonic acid metabolism.

Adult↗
PubMed1985

Acquired multicystic transformation of kidneys.

Acquired multicystic renal transformation of diseased kidneys is a problem known since the early 19th century which has recently regained interest. Such cysts were known before dialysis was established, are seen prior to hemodialysis and in patients on peritoneal dialysis, and can therefore not be a consequence of hemodialysis. It is concluded that an increased incidence of renal cell carcinoma in such kidneys is not established, although, theoretically, several mechanisms might promote carcinogenesis in end-stage kidneys.

Adenoma↗