Search PubMed⌕ Search

Biomedical subjects

M Schulze

Publications and source records attributed to M Schulze.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Minimally invasive osteosynthesis of fractures of the tibial head].

The role of closed reduction techniques in tibial plateau fractures was evaluated retrospectively in a group of 33 patients. The patients had mainly B fractures (AO classification) and were treated by the arthroscopic reduction technique (n = 10) or by reduction under fluoroscopic control (n = 23) and transcutaneous screw fixation. The 21 patients with an average follow-up of 34 months (minimum 1 year) were reviewed. Using clinical and radiological criteria, 19 results were considered excellent to good. One patient with a residual deformity was revised with a total knee and 1 patient with an anatomical result had arthritic pain in the knee operated on. Arthroscopic reduction had no advantages over reduction under fluoroscopic control in this study. The specific value of the technically demanding endoscopic procedure should be questioned, as percutaneous reduction under fluoroscopic control may achieve comparable results in the majority of these cases.

Adolescent↗
PubMed1995

L-fucose residues on cellulose-based dialysis membranes: quantification of membrane-associated L-fucose and analysis of specific lectin binding.

Contact of mononuclear human leukocytes with cellulose dialysis membranes may result in complement-independent cell activation, i.e. enhanced synthesis of cytokines, prostaglandins and an increase in beta 2-micro-globulin synthesis. Cellular contact activation is specifically inhibited by the monosaccharide L-fucose suggesting that dialysis membrane associated L-fucose residues are involved in leukocyte activation. In this study we have detected and quantitated L-fucose on commercially-available cellulose dialysis membranes using two approaches. A sensitive enzymatic fluorescence assay detected L-fucose after acid hydrolysis of flat sheet membranes. Values ranged from 79.3 +/- 3.6 to 90.2 +/- 5.0 pmol cm-2 for Hemophan or Cuprophan respectively. Enzymatic cleavage of terminal alpha-L-fucopyranoses with alpha-L-fucosidase yielded 7.7 +/- 3.3 pmol L-fucose per cm2 for Cuprophan. Enzymatic hydrolysis of the synthetic polymer membranes AN-69 and PC-PE did not yield detectable amounts of L-fucose. In a second approach, binding of the fucose specific lectins of Lotus tetragonolobus and Ulex europaeus (UEAI) demonstrated the presence of biologically accessible L-fucose on the surface of cellulose membranes. Specific binding was observed with Cuprophan, and up to 2.6 +/- 0.3 pmol L-fucose per cm2 was calculated to be present from Langmuir-type adsorption isotherms. The data presented are in line with the hypothesis that surface-associated L-fucose residues on cellulose dialysis membranes participate in leukocyte contact activation.

Acrylic Resins↗
PubMed1995

Association between degree of bone-erosion and synovial fluid-levels of tumor necrosis factor alpha in the knee-joints of patients with rheumatoid arthritis.

OBJECTIVE: To determine whether concentrations of cytokines and matrix-degrading enzymes in synovial fluid of patients with rheumatoid arthritis or osteoarthritis are associated with the degree of bone-destruction in the same joint. METHODS: Determination of Interleukin-1 alpha, IL-1 beta, IL-1-receptor-antagonist, IL-6, IL-8, tumor necrosis factor alpha (by ELISA), collagenase-activity and caseinase-activity (by substrate-assays) in the SF (knee) of patients with RA (n42) or OA (n35). The degree of bone-destruction was assessed radiographically. RESULTS: SF cytokine- and enzyme-levels were higher in patients with RA than in those with OA. In the RA group, SF-levels of TNF alpha were positively correlated with the degree of bone destruction of the respective joint. No correlation was found between radiographically assessed joint changes and SF-concentrations of other cytokines, enzyme activities, serum CRP, or duration of disease. In the OA-group, none of the examined parameters was associated with the degree of joint destruction. CONCLUSIONS: Our data may support the assumption of TNF alpha playing an important role in joint destruction in RA. Possible alternative conclusions are discussed.

Adult↗
PubMed1995

[Water permeability of breathing filters].

Breathing filters or heat and moisture exchangers (HME), which are placed between a tracheal tube and the Y-piece, allow reuse of breathing tubes without changing between operations. During low-flow and minimal-flow anaesthesia, condensed water accumulates in the breathing circuit. An evaluation of the volume of condensed water is given (Fig. 1). It may be possible that water flows onto the filter surface, for example, when the breathing tubes are lifted. The water permeability of such breathing filters and HME was tested. For the experiments, a commercial breathing circuit and ventilator (Dräger Sulla 808 + Ventilog) and patient model (Fig. 2) were used; 12 breathing filters/HMEs of different manufacturers were tested. Only 3 filters were not permeable to the test volume of 20 ml water. The authors suggest the water volume be checked routinely and the breathing tubes be emptied if necessary.

Anesthesia, Inhalation↗
PubMed1995

Basic fibroblast growth factor augments podocyte injury and induces glomerulosclerosis in rats with experimental membranous nephropathy.

Podocyte injury is believed to contribute to glomerulosclerosis in membranous nephropathy. To identify the factors involved, we investigated the effects of basic fibroblast growth factor (bFGF), a cytokine produced by podocytes, on rats with membranous nephropathy (passive Heymann nephritis [PHN]). All rats received a daily i.v. bolus of 10 microg bFGF or vehicle from days 3-8 after PHN induction. In proteinuric PHN rats on day 8, bFGF injections further increased proteinuria. Podocytes of bFGF-injected PHN rats showed dramatic increases in mitoses, pseudocyst formation, foot process retraction, focal detachment from the glomerular basement membrane, and desmin expression. bFGF injections in PHN rats did not alter antibody or complement deposition or glomerular leukocyte influx. bFGF-injected PHN rats developed increased glomerulosclerosis when compared with control PHN rats. Also, bFGF induced proteinuria and podocyte damage in rats injected with 10% of the regular PHN-serum dose. None of these changes occurred in bFGF-injected normal rats, complement-depleted PHN rats or rats injected with 5% of the regular PHN serum dose. These divergent bFGF effects were explained in part by upregulated glomerular bFGF receptor expression, induced by PHN serum. Thus, bFGF can augment podocyte damage, resulting in increased glomerular protein permeability and accelerated glomerulosclerosis. This bFGF action is confined to previously injured podocytes. Release of bFGF from glomerular sources (including podocytes themselves) during injury may represent an important mechanism by which podocyte damage is enhanced or becomes self sustained.

Animals↗
PubMed1994

Insulin-like growth factor I accelerates recovery of articular cartilage proteoglycan synthesis in culture after inhibition by interleukin 1.

Interleukin 1 (IL-1) is a cytokine which induces cartilage proteoglycan (PG) depletion by inhibiting PG synthesis and increasing PG breakdown. Insulin-like growth factor I (IGF-I), in contrast, is known to promote matrix formation. We examined the effects of both mediators in a bovine tissue culture model. IL-1 dose-dependently inhibited PG formation of articular cartilage [half-maximal effect (EC50) at 4 ng/ml], while PG synthesis was increased by IGF-I (EC50 = 15 ng/ml). After inhibition of PG formation with IL-1 for 2 days and subsequent removal of free IL-1, addition of IGF-I dose-dependently accelerated restoration of the original rate of synthesis with a half-maximal effect at 20 ng/ml and a maximal effect at 50 ng/ml. The IGF-I concentration required to elicit a half-maximal effect on cartilage PG synthesis remained constant in the absence or presence of IL-1. We therefore conclude that inhibition of cartilage PG synthesis by IL-1 is not effected by damage to the IGF receptor. Synovial fluid (SF) of 40 patients with rheumatoid arthritis (RA) was found to contain 64 +/- 6 ng IGF-I/ml (mean +/- SEM). The reported effects of IGF-I in vitro therefore occurred at concentrations comparable to those present in joints in vivo. IL-1 beta was detectable (> 0.5 pg/ml) in 38 of 40 RA-SF samples (mean 28 +/- 6 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis, Rheumatoid↗
PubMed1994

Serum immunoglobulins in Heymann's experimental nephritis modulate binding of properdin and factor-H to sulpho-glycosphingolipids II3SO3(-)-Gg3Cer and III3SO3(-)-,II3SO3(-)-Gg3Cer.

The nephropathic effects of Heymann's experimental nephrites involve autoallergic serum antibodies directed against rat kidney membrane constituents. In assessing the action of glycolipids as possible autoallergens in these conditions, it was found that heterologous and autologous Heymann's nephritis sera antibodies recognize that rat kidney sulphatides, II3SO3(-)-Gg3Cer (Stri1), and III3SO3(-)-,II3SO3(-)-Gg3Cer (Stri2). Two antibody populations in Heymann's sera, each reacting with only one of the two sulphatides, could be observed. It was further shown that human factor-H and properdin, pivotal regulators of the alternative pathway of complement activation, both bound to Stri2 in vitro. This binding of factor-H and properdin was differentially affected by affinity-purified anti-Stri2 antibodies of Heymann's nephritis sera. Whereas the interaction between factor-H and Stri2 was inhibited by the antibody, that of properdin was enhanced.

Animals↗
PubMed1994

On the specificity of assays to detect circulating immunoglobulin A-fibronectin complexes: implications for the study of serologic phenomena in patients with immunoglobulin A nephropathy.

Immunoglobulin A (IgA)-fibronectin complexes have been proposed as specific serologic markers of IgA nephropathy. They have been detected by the use of ELISA composed of an immobilized antifibronectin antibody (or albumin as a negative control) and an enzyme-conjugated anti-IgA antibody (antifibronectin capture assay). By the use of this type of assay, plasma samples from 32 normal controls, 38 IgA nephropathy patients, and 81 patients with other types of glomerulonephritis were analyzed. Extinction values in IgA nephropathy patients were higher (P = 0.06) than in patients with other glomerulonephritis types and significantly higher than in normals. Markedly lower values were obtained when the plates were coated with albumin. However, when the antifibronectin antibody was replaced by normal IgG or F(ab')2 fragments, almost identical extinctions were measured. The use of different antifibronectin antibodies, IgG, ELISA plates, or blocking regimens did not modify these results. Extinction values could not be suppressed by the addition of exogenous fibronectin. Similar extinctions were observed when plasma samples were replaced by physiologic concentrations of fibronectin-free IgA. Extinction values measured in the plasma samples correlated significantly with IgA concentrations in plasma as analyzed by nephelometry. A collagen binding assay, a second type of assay used to measure IgA-fibronectin complexes, also allowed the detection of fibronectin-free IgA, and again, extinctions measured in plasma could not be suppressed by exogenous fibronectin. In conclusion, both antifibronectin capture ELISA and collagen binding assays do not specifically detect only IgA-fibronectin complexes, but also total plasma IgA, which is frequently, but nonspecifically, elevated in IgA nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Is the brush border membrane of the intestinal mucosa a generator of "chymosomes"?

1. The microvilli of enterocytes in calf intestine demonstrate high levels of vesiculation activity at the top and at the basal region. 2. The morphology of the vesicles associated with microvilli (100-500 nm diameter, unilamellar, few intramembraneous particles, high AP activity) is very similar to the morphology of vesicles found in the chyme. 3. Vesicles can be purified 6-10 fold from chyme of the calf intestine applying a Mg(++)-precipitation method, used for brush border membrane preparation. 4. Specific activities of alkaline phosphatase and disaccharidases were found to be much higher in chyme vesicles than in the mucosa. 5. Phospholipid content and phospholipid composition is in chyme vesicles different from brush border membrane vesicles. 6. The characterized chyme vesicles are referred to as chymosomes. We consider the mucosa as a large-scale generator of chymosomes, i.e. digestive enzymes bearing vesicles.

Alkaline Phosphatase↗
PubMed1994

Antibodies to glycolipids activate complement and promote proteinuria in passive Heymann nephritis.

Passive Heymann nephritis is an experimental rat model of human membranous nephropathy induced by injection of antisera against crude renal cortical fractions such as Fx1A or rat tubular microvilli. This results in the formation of subepithelial immune deposits, the activation of the C5b-9 membrane attack complex of complement, and severe proteinuria. While the formation of immune deposits is attributed to in situ immune complex formation with antibodies specific for the gp330-Heymann nephritis antigenic complex (HNAC), activation of complement and proteinuria appear to be caused by at least one additional antibody species present in anti-Fx1A sera. We have separated by affinity absorption polyspecific antisera against Fx1A and rat microvilli into one IgG fraction directed specifically against microvillar proteins (anti-Fx1A-prot) and another IgG fraction specific for glycolipids (ant-Fx1A-lip) of tubular microvilli. When injected into rats, the anti-Fx1A-prot fraction induced immune deposits but failed to activate complement or produce proteinuria, similar to results obtained with affinity-purified anti-gp330 IgG. When the antibodies of the anti-Fx1A-lip fraction were injected alone they did not bind to glomeruli. By contrast, when the IgGs specific for the Fx1A-prot fraction (or for gp330-HNAC) were combined with those directed against the Fx1A-lip glycolipid preparation, immune deposits were formed, in situ complement activation was observed, and also proteinuria was induced. It is concluded that within anti-Fx1A and anti-microvillar sera there are at least two IgG fractions of relevance for the development of PHN: one directed against the gp330-HNAC complex which is responsible for the development of immune deposits, and a second specific for glycolipid antigen(s) which activate(s) the complement cascade.

Animals↗
PubMed1993

Heterogeneity of glycosylphosphatidylinositol-anchored alkaline phosphatase of calf intestine.

A method is described for large-scale purification of glycosylphosphatidylinositol-anchored alkaline phosphatase from intestinal mucosa and chyme to homogeneity. Both enzyme preparations contain approximately 2 mol fatty acid/mol subunit and exhibit a very similar fatty acid composition with octadecanoate and hexadecanoate as prevalent components. No significant differences between native glycosylPtdIns-anchored and hydrophilic alkaline phosphatases from both sources were found regarding Km, Vmax, the type of inhibition and inhibition constants of the amino acids L-leucine, L-phenylalanine, and L-tryptophan. The purified enzymes of both sources yield diacylglycerol and phosphatidic acid, after treatment with phosphatidylinositol-specific phospholipase C (PtdIns-PLC) and glycosylphosphatidylinositol phospholipase D (PLD), respectively. Enzyme preparations of both sources appear as heterogeneous mixtures of five fractions separable by octyl-Sepharose chromatography. Fraction I corresponds to the anchorless enzyme, fractions II-V differ in their susceptibility to phospholipases. Fractions II and IV are completely split by PtdIns-PLC or PLD action, almost 50% of fraction III is split by PtdIns-PLC, while fraction V is resistant. The susceptibility of these two fractions toward the action of PLD is considerably higher. Fatty acid analysis yields molar ratios of fatty acids/alkaline phosphatase subunit of 1.78, 2.58, 2.24, and 3.37 for fractions II, III, IV, and V, respectively. Aggregates of glycosylPtdIns-anchored alkaline phosphatase of all fractions are seen in native PAGE in the presence of Triton X-100. By gel chromatography in the presence of Brij 35, fractions II-V form stable multiple aggregates of dimers and may bind different amounts of the detergent. These data, together with fatty acid analysis, can be interpreted by the following model. Fractions II and IV are tetramers and octamers with two molecules fatty acid/subunit. Fraction III is a tetramer, bearing one additional fatty acid molecule, localized on the dimer. Fraction V is an octamer, containing glycosylPtdIns-anchor molecules with three molecules fatty acids/anchor molecule. The additional fatty acid residue is possibly located on inositol and responsible for the reduced susceptibility to PtdIns-PLC. The similarity of all measured parameters of both enzymes suggests that the glycosylPtdIns-anchored alkaline phosphatase of the mucosa is released into the chyme without changing the anchor molecule constituents.

Alkaline Phosphatase↗
PubMed1993

The inferior epigastric artery for coronary bypass grafting. Functional assessment and clinical results.

The use of the internal thoracic artery (ITA) for coronary bypass grafting (CBG) has resulted in superior long-term function. Other autologous arteries have been investigated also, but the role of the inferior epigastric artery (IEA) for CBG has not yet been defined. From March 91 to August 92, IEA grafts were used in 50 male patients aged 30-68 years/mean 54.9) combined with 1 (n = 40) or 2 (n = 8) ITA grafts. Pedicled grafts were dissected (length: 8.5-16.5, 13.1 cm) but left in situ covered by sponges soaked with papaverine solution until going on bypass. There was no mechanical or pharmacological intraluminal manipulation. Distal free flow (in situ) was 41.8 ml/min (16-95 ml/min). A total of 146 grafts were constructed (2.9/patient), including free IEA-CBG performed to the LAD (n = 28) or its diagonal branches (n = 22). The operative mortality was 2.0%, there were no sternal wound complications but superficial abdominal infections in 5 patients. Recatheterization (1-6 months postoperatively) revealed an 82.6% patency rate (19/23) in IEA, compared to 100% in ITA, grafts. In vitro stimulation of arterial segments by endothelium- or muscular-dependent relaxation revealed a response (% of the maximum) of 92.4% in IEA and 74.6% in ITA to acethylcholine, while the response to nitroglycerin was 92.7% and 98.6%, respectively. Our clinical results would support the concept of combining IEA and ITA for arterial revascularization in CBG. Inferior epigastric artery grafts should provide adequate blood flow and good long-term patency due to preservation of their endothelial function.

Abdominal Muscles↗
PubMed1993

Gene expression of interleukin-1 beta during hemodialysis.

It is still controversial whether the hemodialysis (HD) procedure is an inflammatory process in vivo. Therefore, we studied the gene expression of interleukin-1 beta (IL-1 beta) as a marker of inflammation in peripheral blood mononuclear cells (PBMC) of patients during HD by Northern blotting and polymerase chain reaction. Compared to PBMC separated pre-HD (1.0 densitometric units), the amount of IL-1 beta mRNA was increased in PBMC leaving the dialyzer (12.2 +/- 2 densitometric units, P < 0.01), but was not increased in PBMC re-entering the dialyzer from the systemic circulation (0.6 +/- 0.1 densitometric units) in all 12 patients studied. The maximal amount of IL-1 beta mRNA in PBMC was seen at five minutes after start of HD. There was a significant correlation between the increase in IL-1 beta mRNA and the increase in activated complement C5a (r = 0.71, P < 0.01). HD using less complement-activating membranes (hemophan, polysulfone, polyamide or polyacrylonitrile) resulted in no detectable IL-1 beta mRNA. Furthermore, a monoclonal antibody against human C5a reduced the increase in IL-1 beta mRNA by 83% (P < 0.05), indicating that C5a plays a major role for induction of IL-1 beta mRNA during HD. This study demonstrates that during HD with regenerated cellulose, gene expression for IL-1 beta takes place in PBMC.

Base Sequence↗
PubMed1993

Short- and long-term effects of perinatal interleukin-1 beta-application in rats.

Nervous, endocrine and immune systems are regarded as a complex functional unit, interacting by their specific chemical messengers-neurotransmitters, systemic hormones and hormone-like mediators of immune cells (cytokines). Cytokines are known to affect several endocrine axes. Interleukin-1 beta (IL) was administered in rats intraperitoneally twice daily from day 17 to 21 of pregnancy. Some of the IL-treated mothers were rapidly decapitated 1.5 h after the last injection. The fetuses were delivered by cesarean section. Maternal plasma CRF, ACTH and corticosterone were found to be significantly elevated. Fetal adrenal and thymus weights were lower, and plasma corticosterone did not differ from controls. Fetal plasma testosterone was decreased in males, androstenedione was increased in females. Open-field testing revealed a higher total locomotor activity of IL offspring than of controls. IL offspring showed worse results in Skinner box learning than controls. Sexual behavior was only affected in males, showing a higher percentage of female-type lordosis behavior after castration and estrogen treatment compared to controls. At the age of 6 months responsiveness to 'novel-environment stress' of IL groups was significantly lower than that of controls in terms of plasma corticosterone. These results indicate that prenatal treatment with IL-1 beta results in long-lasting alterations in psychomotor development, behavior as well as in the neuroendocrine system.

Adrenal Glands↗
PubMed1993

Glomerulonephritis associated with inflammatory demyelinating polyradiculoneuropathy: a case report and review of the literature.

A patient developed relapsing inflammatory demyelinating polyradiculoneuropathy associated with nephrotic syndrome. Renal biopsy showed focal-segmental glomerulosclerosis. The review of the literature disclosed that glomerulonephritis with and without nephrotic syndrome seems to be not uncommon in inflammatory demyelinating polyradiculoneuropathy, such as Guillain-Barré syndrome. membranous glomerulonephritis is the most frequent histologic diagnosis while minimal change nephropathy, 'acute glomerulonephritis' and postinfectious type glomerulonephritis are not often present. This is the first case of inflammatory demyelinating polyradiculoneuropathy associated with nephrotic syndrome due to focal-segmental glomerulosclerosis. Larger prospective studies are necessary and may contribute to the understanding of the pathogenesis of both, glomerulonephritis and inflammatory demyelinating polyradiculoneuropathy.

Adult↗
PubMed1993

Plasma levels of bactericidal/permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) during hemodialysis.

Several proteins modify the biological response to lipopolysaccharide (LPS). Both bactericidal/permeability-increasing factor (BPI), a protein stored in neutrophils, and the acute phase protein LPS-binding protein (LBP) bind to LPS; however, BPI inhibits while LBP enhances binding of LPS to leukocytes and subsequent induction of cytokines. We investigated plasma levels of BPI, LBP, elastase and C5a before, during and after hemodialysis (HD). Six patients were dialysed with Cuprophane (Cup) and polysulfone (PS) low-flux dialyzers on two consecutive HD sessions. There was a significant, 10.9 +/- 2.8-fold increase in BPI after 4-hour HD compared to predialysis and a 4.4 +/- 1.6-fold increase in elastase after 4-hour HD using Cup. Plasma levels of BPI and elastase decreased rapidly after the dialysis session. HD with PS resulted in a smaller, but still significant rise in BPI (3.7 +/- 1.6-fold at 4 hours) and elastase (1.69 +/- 0.2-fold at 4 hours). Levels for BPI and elastase were similar in the arterial and venous blood lines of the dialyzer. Plasma levels of LBP did not change during or after the HD session. These data indicate that BPI, but not LBP is released during HD with Cup and to a lesser extent with PS. Activation of neutrophils and release of BPI during HD may influence the biological response to bacterial products possibly introduced during HD.

Acute-Phase Proteins↗
PubMed1993

Glomerular C3c localization indicates ongoing immune deposit formation and complement activation in experimental glomerulonephritis.

In antibody-mediated glomerular disease, deposits of C3 (C3b) are common and are degraded by factor I to C3c and C3d. However, the kinetics of C3b degradation in glomerulonephritis have not been defined. To do this, we studied three models of complement-dependent glomerulonephritis with established C3 deposits (passive Heymann nephritis, cationized immunoglobulin G membranous nephropathy, and concanavalin A-anticoncanavalin A glomerulonephritis). C3b deposition was halted by administration of cobra venom factor, and the disappearance of C3c and C3d from glomeruli was measured with specific antibodies and quantitative fluorescence densitometry. Results showed that C3c deposits were reduced by over 85% within 24 hours in all three models. C3c clearance was unaffected by site or mechanism of deposit formation. C3d deposits persisted despite lack of ongoing complement activation. In passive Heymann nephritis when disease activity was monitored by urinary C5b-9 excretion, C3c was cleared in parallel with return of urine C5b-9 excretion to normal values. We conclude that glomerular deposits of C3c are cleared within 24 hours of cessation of complement activation. Positive staining for C3 utilizing antibody specific for the C3c portion documents recent complement activation usually reflecting new immune deposit formation.

Animals↗