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Biomedical subjects

J Bommer

Publications and source records attributed to J Bommer.

At least 55 records · Page 3Linked to original sources
PubMed1989

Lysine-specific cleavage of beta 2-microglobulin in amyloid deposits associated with hemodialysis.

Amyloid fibrils isolated from bone and carpal synovia of seven patients on long-term hemodialysis were further characterized biochemically. In addition, renal amyloid stones of three dialyzed patients were examined. All deposits and stones were of beta 2-microglobulin-origin (AB-amyloid) by immunohistochemical and immunochemical evaluation. Amyloid fibril extracts were dissolved in 80% formic acid and separated by high performance liquid chromatography in 60% formic acid and 20% 2-propanol. Three major retarded fractions with molecular weights of approximately 24, 12 and 7 to 10 kD were recovered. N-terminal amino acid sequence analysis documented beta 2-microglobulin (beta 2m) as the principal polypeptide in all investigated cases. In addition to proteins with intact N-termini, one fragment commencing with isoleucine in position 7 was found in osseous or synovial amyloid. In renal amyloid stones, one additional fragment was found beginning with serine in position 20. Generally, these data point to proteolytic cleavage carboxyterminal to a lysine residue and establish that not only intact beta 2m but also at least one beta 2m fragment is present in beta 2m-derived amyloid deposits of patients with long-term hemodialysis. The fragmentation pattern is consistent with the action of lysine-specific protease(s) and underscores a potentially important role of limited proteolysis in the pathogenesis of AB-amyloid deposits.

Adult↗
PubMed1988

Cuprammonium membranes stimulate interleukin 1 release and arachidonic acid metabolism in monocytes in the absence of complement.

Contact of blood with foreign surfaces, specifically dialysis membranes, causes cell activation which has widely been assumed to be mediated by complement (C). To explore the possibility of C-independent activation, we examined different cell types: PMN, human monocytes and the cell lines U937 or HL60, washed human platelets and rat glomerular epithelial cell (primary) cultures (GEC), under serum-free conditions and after addition of anti-C3 F(ab)2, respectively. The monitored biological effects were release of PGE2, TXB2 or interleukin 1 and generation of O2- radicals. To further explore the mechanisms involved, phospholipid metabolism was studied by measuring IP3 and DG (14C-arachidonic or oleic acid prelabeled U937 and HL60 cells); changes of cytosolic Ca++ (Quin2 technique) were also determined. The results show that in absence of C, brief (2 min) contact with cuprammonium (CU) stimulated: (a) PGE2 release in U937 and human monocytes or GEC; (b) TXB2 release in washed platelets; (c) slow interleukin 1 release by monocytes; and (d) generation of O2- radicals in PMN. Artifacts due to endotoxin were excluded by appropriate polymyxin control experiments and by comparison of effects with those of bacterial LPS. Potential synthesis of C3 by U937 was excluded by addition of anti-C3 F(ab)2. C-independent cell activation was accompanied by increase of DG, but not IP3 (suggesting involvement of protein C kinase dependent mechanisms) and by increased cytosolic Ca++. To further explore the initial signal involved, incubations were carried out with covalently modified CU members (DEAE cellulose) and in the presence of mM concentrations of monosaccharides. Cationic modification of CU membranes reduced C-independent cell activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acid↗
PubMed1988

HBV DNA and other hepatitis B virus markers in sera from long-term hemodialysis and kidney transplant patients.

Sera from 191 long-term hemodialysis patients and from 115 renal transplant patients were studied for the presence of HBsAg and other HBV markers. In 19.1% of the hemodialysis patients and 28.7% of the transplant patients, the sera were positive for HBeAg.HBV DNA in sera was detected by molecular hybridization. HBV DNA was present in the sera of 15 out of 16 hemodialysis patients positive for HBeAg, and in one hemodialysis patient positive for anti-HBe. All renal transplant patients positive for HBeAg were also positive for HBV DNA. Twelve transplant patients were positive for HBV DNA, but negative for both HBeAg and anti-HBe. Determination of HBV DNA was the most sensitive marker of infectivity in patients with end-stage renal disease, and in renal transplant patients.

Adult↗
PubMed1987

Diminished parathyroid 1,25(OH)2D3 receptors in experimental uremia.

In Sprague Dawley rats, six days after subtotal nephrectomy, serum 1,25(OH)2D3 concentration was diminished (59.8 +/- 17.5 pg/ml vs. 121 +/- 48; P less than 0.01). Despite low circulating 1,25(OH)2D3 levels, maximal specific binding capacity for 1,25(OH)2D3 in parathyroid glands was diminished (Nmax 87.5 fmol/mg protein and 3.52 fmol/mg DNA vs. 143 fmol/mg protein and 4.75 fmol/mg DNA, respectively). There was no change of KD, apparent molecular size (sucrose density gradient) and DNA binding affinity (DNA cellulose chromatography) pointing to intactness of the receptor. Since 1,25(OH)2D3 is a potent negative feedback signal for parathyroids, the data are potentially relevant for the genesis of secondary renal hyperparathyroidism.

Animals↗
PubMed1987

Ethylene oxide (ETO) as a major cause of anaphylactoid reactions in dialysis (a review).

Ethylene oxide (ETO), an alkylating compound of high chemical reactivity, is widely used for gas sterilization, but recently serious ETO side reactions have been recognized. With chronic ETO exposure, increased spontaneous abortion, sister chromatid exchange, and leukemia are observed. After medical use of ETO outside nephrology, contact dermatitis, cardiopulmonary shock (during cardiopulmonary surgery), allergic local reactions to ETO sterilized lenses, and anaphylactoid reactions to ETO sterilized catheters have been described. In numerous dialysis patients widespread hypersensitivity to ETO has been documented by skin prick test and ETO radioallergosorbent test (RAST). Furthermore an anaphylactoid "first-use reaction" was described in dialyzed patients, most of whom were using hollow-fiber dialyzers. After long discussions whether complement activation versus hypersensitivity is the cause of such acute anaphylactoid reactions, more recent studies using either ETO RAST or basophil degranulation tests implicate ETO hypersensitivity as their major cause. The high prevalence of sensitization to ETO and the frequency, unpredictability, and potential danger of anaphylactoid reactions to ETO lead to the conclusion that ETO sterilization of dialyzers should be discontinued, since alternative modalities of sterilization are currently available.

Anaphylaxis↗
PubMed1987

Effects of parathyroidectomy on blood pressure in spontaneously hypertensive rats.

The long-term effects of parathyroidectomy (PTX) on blood pressure, intravascular volume, pressor hormones, and on acute vascular effects of intravenous parathyroid hormone (PTH) were evaluated in spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WK) rats. PTX or sham operation (CO) were done at 4-5 weeks of age, and a high calcium diet was offered to PTX rats to study them at eucalcemic calcium levels. The cardiovascular effects of PTX, determined after 11-13 weeks, were qualitatively similar in SH and WK rats: mean arterial blood pressure (conscious unrestrained rats) was lower, intravascular volume was higher, total body sodium was slightly higher, and plasma angiotensin II or norepinephrine levels were not different from CO groups. The acute hypotensive and chronotrophic effect of intravenous PTH was unchanged in PTX groups. When parathyroid intact SH rats and PTX SH rats were both examined on an 1.6% Ca diet, blood pressure was significantly lower in PTX than in parathyroid-intact SH rats. The results are compatible with the hypothesis that PTH has a permissive action on blood pressure maintenance in eucalcemic SH and WK rats by mechanisms unrelated to volume status or circulating pressor hormone concentrations.

Animals↗