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Biomedical subjects

G A Müller

Publications and source records attributed to G A Müller.

At least 55 records · Page 3Linked to original sources
PubMed2000

Immunocytological determination of lymphocytes and monocytes/macrophages in urinary sediments of renal allograft recipients.

BACKGROUND: Urinary studies using Papanicolaou staining following kidney transplantation led to the conjecture that acute allograft rejection might be accompanied by an increased lymphocyturia. However, it is difficult to distinguish lymphoid cells from other urinary cells using conventional stains. METHODS: Staining of urinary lymphocytes using FITC-labelled antibodies is complicated by a high unspecific fluorescence that limits the evaluation. Therefore, we developed a method to stain urinary lymphocytes using enzyme-linked antibodies. The cells were cytocentrifuged onto microscope slides and were fixed. RESULTS: By means of a combined evaluation of Papanicolaou and immunocytochemical staining, CD3-positive pan T cells, CD4-positive T-helper cells, CD8-positive cytotoxic/suppressor cells, and CD14-positive monocytes/macrophages of urinary sediments were determined in 41 kidney graft recipients following renal transplantation. During periods of normal graft function, neither positive lymphocytes nor positive monocytes/macrophages were found in the urinary sediments. However, in the course of acute allograft rejection a significant increase in positive lymphocytes and positive monocytes/macrophages could be observed. Interestingly, in cases of acute allograft rejection the distribution of urinary lymphocytes and monocytes was comparable to the distribution of infiltrating immunocompetent cells in renal allograft biopsies. CONCLUSION: The present study demonstrates that immunocytochemical staining via enzyme-conjugated antibodies is a reliable method to visualize T lymphocytes and monocytes/macrophages in the urinary sediment, and that this technique may be of special diagnostic value in the diagnosis of acute allograft rejection.

Antigens, CD↗
PubMed2000

Increased expression of CD40 ligand (CD154) on CD4+ T cells as a marker of disease activity in rheumatoid arthritis.

OBJECTIVES: The interaction between the activation induced surface glycoprotein CD40L (ligand) (CD154) on CD4+ T cells and its receptor CD40, which is expressed on various cell types, plays a crucial part in numerous cell mediated and humoral immune reactions that may be of pathogenetic importance in rheumatoid arthritis (RA). To further evaluate the pathogenetic role of CD40L in RA, expression of CD40L and various other T cell activation antigens as well as costimulatory molecules was investigated on CD4+ T cells in RA by flow cytometry. METHODS: Two colour flow cytometry was used to determine the percentage of CD4+ T cells expressing CD40L, CD69, CD25, HLA-DR, CD39, CD27 and CD28 in peripheral blood (PB) of 62 RA patients in comparison to 20 healthy controls (HC). Disease activity was assessed by clinical, laboratory and radiological examination. Status of clinical remission of RA was evaluated according to the ACR preliminary criteria for complete clinical remission of RA. RESULTS: CD40L was expressed on > 10% of CD4+ T cells in 29% of RA patients thus defining a CD40L(high+) patient group. Disease activity as estimated by C reactive protein, rheumatoid factor and status of clinical remission of disease (p = 0.049) was higher in this subgroup than in the RA CD40L(low+) group. Expression of CD69, CD25, and HLA-DR was significantly increased in both RA patient groups in comparison with HC. However, the percentage of CD39+ CD4+ T cells was increased only in the RA CD40L(high+) subgroup (versus HC p = 0.019, versus RA CD40L(low+) p = 0.044). Furthermore, expression of CD40L and CD39 on CD4+ T cells correlated positively as estimated by Spearman rank correlation (p<0.001). The percentage of CD4+ T cells lacking the costimulatory molecules CD27 (p = 0.002) and CD28 (p = 0.026) was increased in RA CD40L(low+) patients in comparison with HC. CONCLUSIONS: These data suggest that increased expression of CD40L on CD4+ T cells in RA indicates prolonged and increased activation of CD4+ T lymphocytes and is associated with active disease and possibly an unfavourable prognosis. Whether this phenotypically defined RA CD40L(high+) subgroup will preferentially respond to an anti-CD40L antibody treatment remains to be elucidated.

Adult↗
PubMed1999

[Rapidly progressing renal insufficiency as the primary manifestation of systemic sarcoidosis].

CASE REPORT: We report the history of a 67-year-old patient who was admitted to hospital because of rapidly progressive renal insufficiency. The renal biopsy revealed granulomatous interstitial nephritis. The diagnosis of systemic sarcoidosis was confirmed by typical findings of bronchoalveolar lavage and of transbronchial, liver and bone marrow biopsy. Indications for sarcoidosis-related nephrocalcinosis/nephrolithiasis or glomerulonephritis were absent. Simultaneously a monoclonal gammopathy of unknown significance (MGUS) was diagnosed. While the patient having been uremic at the time of diagnosis, the administration of prednisolone effectively improved renal function. CONCLUSIONS: As a rare manifestation of sarcoidosis granulomatous interstitial nephritis can cause rapidly progressive renal insufficiency, which can effectively be treated by steroids, if distinct interstitial fibrosis is absent.

Acute Kidney Injury↗
PubMed1999

Expression cloning and characterization of a novel sodium-dicarboxylate cotransporter from winter flounder kidney.

A cDNA coding for a Na+-dicarboxylate cotransporter, fNaDC-3, from winter flounder (Pseudopleuronectes americanus) kidney was isolated by functional expression in Xenopus laevis oocytes. The fNaDC-3 cDNA is 2384 nucleotides long and encodes a protein of 601 amino acids with a calculated molecular mass of 66.4 kDa. Secondary structure analysis predicts at least eight membrane-spanning domains. Transport of succinate by fNaDC-3 was sodium-dependent, could be inhibited by lithium, and evoked an inward current. The apparent affinity constant (Km) of fNaDC-3 for succinate of 30 microM resembles that of Na+-dicarboxylate transport in the basolateral membrane of mammalian renal proximal tubules. The substrates specific for the basolateral transporter, 2,3-dimethylsuccinate and cis-aconitate, not only inhibited succinate uptake but also evoked inward currents, proving that they are transported by fNaDC-3. Succinate transport via fNaDC-3 decreased by lowering pH, as did citrate transport, although much more moderately. These characteristics suggest that fNaDC-3 is a new type of Na+-dicarboxylate transporter that most likely corresponds to the Na+-dicarboxylate cotransporter in the basolateral membrane of mammalian renal proximal tubules.

Amino Acid Sequence↗
PubMed1999

Relationship of antibodies to endotoxin core to mortality in medical patients with sepsis syndrome.

OBJECTIVES: To assess the prognostic value of determining anti-endotoxin core antibodies (EndoCab) immunoglobulin (Ig)G and IgM in medical patients with sepsis syndrome in order to identify patient subgroups that may profit from endotoxin-neutralizing therapy. The findings were correlated with clinical outcome, endotoxin levels and sepsis score. DESIGN: Cohort study with a follow-up period of 30 days. SETTING: Medical intensive care units (2) of a university hospital. PATIENTS AND METHODS: Twenty-nine patients who fulfilled the criteria of sepsis syndrome and did not present with septic shock or had not been treated with antibiotics for more than 3 days were included in the study. Twenty-one intensive care patients without infections served as controls for antibody concentrations. INTERVENTIONS: Blood samples were obtained from indwelling arterial catheters or direct venipuncture on admission and daily thereafter until transfer to a regular unit. Sepsis scores were determined daily. RESULTS: The mortality rate at 30 days was 44.8% (13 out of 29). Sepsis patients had significantly lower initial EndoCab IgM and IgG concentrations than controls. Initial EndoCab IgG concentrations were significantly lower in non-survivors of sepsis syndrome but not in survivors compared to controls (median concentrations 51.5 vs 110.1 vs 245.4 MU/ml). EndoCab IgM and IgG were lower in non-survivors compared to survivors, though that difference failed to reach significance (p = 0.11 in both cases). Depletion of initial EndoCab IgM concentrations (defined as a value below the 10th percentile of a control population) was present in 15 patients, 9 of whom died, and depletion of IgG in five patients, four of whom died. EndoCab IgM and IgG concentrations rose concordantly in survivors and non-survivors in the course of the disease. Endotoxin levels were significantly higher in non-survivors compared to controls but not in survivors. A sepsis score of 21 and higher was associated with 90.9% mortality (specificity 93.8%, sensitivity 76.9%). CONCLUSIONS: Decreased EndoCab IgG concentrations are associated with increased mortality in medical patients with sepsis syndrome. The measurement of initial anti-endotoxin antibodies may provide a useful tool to identify septic patients who profit potentially from endotoxin neutralizing therapy, however considerable overlap of antibody concentrations warrants additional parameters. The sepsis score is easy to determine and useful in the evaluation of medical patients with sepsis.

Adult↗
PubMed1999

A bumetanide-sensitive, apically localized Na+2Cl-K+ cotransport in the rat inner medullary collecting duct.

To better characterize loop diuretic-sensitive ion fluxes in the inner medullary collecting duct (IMCD) we examined them in IMCD cells grown as a primary culture on permeable supports. A polarization of the cells with their basolateral side to the support was confirmed morphologically by electron microscopy and functionally by flux studies with ouabain. Within 7 days cells developed a transepithelial resistance of 974+/-52 omega per cm2 and a low transepithelial potential difference (-0.7+/-0.8 mV). Measurements of intracellular ion content by electron probe microanalysis in IMCD depleted of intracellular ions by preincubation in a Na(+)-K(+)-Cl(-)-free medium revealed, compared to the control receiving solvent, significant reductions in intracellular Na+ content (-17.6% within 10 min) and intracellular Cl- content (-43.8% within 30 min) by the addition of bumetanide (10(-4) mol/l) to the apical but not basolateral incubation medium. In 22Na+ and 86Rb+ isotope uptake studies, fluxes from the apical side were significantly inhibited at bumetanide concentrations of 100 micromol/l by 0.27+/-0.10 and 0.21+/-0.04 nmol/cm2 in 10 min, respectively, whereas basolateral fluxes of 86Rb+ but not 22Na+ were significantly reduced by this substance. Removal of Cl- had a similar but not additional effect. mRNA encoding the apical isoform of the Na+2Cl(-)K+ cotransporter could be specifically amplified by reverse transcriptase polymerase chain reaction from the inner medulla and highly purified IMCD cells. Northern blot of mRNA isolated from the inner medulla with a riboprobe of the apical isoform revealed a transcript of approximately 4.9 kb. This probe localized under "low-stringency" conditions to the IMCD in in situ hybridization studies. These results suggest the presence of an apically localized isoform of bumetanide-sensitive Na+2Cl(-)K+ cotransport in at least a subfraction of IMCD cells. This transport may be involved in the ultimate adjustment of urinary electrolyte concentration by this final segment of the tubular system.

Animals↗
PubMed1999

Demonstration of a Na(+)-dicarboxylate cotransporter in bovine adrenocortical cells.

Our study found the uptake of [14C]succinate into bovine adrenocortical cells to be sodium-dependent, inhibited by lithium, and to have an apparent K(m) of 146 mumol/l. Succinate uptake was inhibited by glutarate, fumarate, alpha-ketoglutarate, and maleate but not by 2,3-dimethylsuccinate or cis-aconitate, specific inhibitors of the basolateral Na(+)-dicarboxylate transporter of renal proximal tubule cells. Succinate uptake was highest at pH 6.0 and decreased with increasing pH. Transport of succinate was not significantly inhibited by citrate at pH 7.4 whereas at pH 6.0 inhibition of succinate uptake by citrate was small but significant. The affinity of the adrenal dicarboxylate transporter towards succinate ranges in between the low affinity of the renal luminal dicarboxylate transporter and the high affinity of the respective basolateral transporter. The pH dependency of succinate uptake and the missing inhibition by citrate at pH 7.4 differ from both the luminal and from the basolateral dicarboxylate transporters in kidney, liver, intestine, and placenta. These functional characteristics provide evidence for the existence of a Na(+)-dicarboxylate cotransporter in adrenocortical cells which may supply cholesterol metabolism with reducing substrates.

Adrenal Cortex↗
PubMed1999

Review: the oxidant/antioxidant balance during regular low density lipoprotein apheresis.

Low density lipoprotein (LDL) apheresis is a safe procedure to treat severe hypercholesterolemia in patients with chronic heart disease (CHD). However, both hypercholesterolemia and extracorporeal treatment have been associated with oxidative stress. Even though LDL lowering has been proven to reduce CHD, the oxidative modification of LDL has been suggested to render these lipoproteins more atherogenic. It is therefore important to know whether LDL apheresis is safe with respect to oxidative stress including LDL oxidation. The contact of living cells such as leukocytes with artificial surfaces during extracorporeal treatment induces the liberation of various chemokines and cytokines as well as oxygen-derived radicals also known as respiratory burst. These effects justify the consideration of leukocyte activation resulting from extracorporeal treatment as an inflammatory reaction. In extracorporeal circuits such as those used for hemodialysis, the release of oxygen radicals has been shown and depends on the fiber material used in the dialyzer membranes. Reactive oxygen radicals can interact with different cell components such as carbohydrates, DNA, proteins, and lipids. Antioxidants in the form of low molecular weight molecules such as glutathione or radical scavenging enzymes such as superoxide dismutase offer protection against the damaging effects of prooxidants. The disturbed balance between prooxidants and antioxidants is considered as oxidative stress. Therefore, either an increase in oxygen radical formation or a decrease of antioxidants will lead to oxidative stress. During LDL apheresis, a decrease of low molecular weight antioxidants has been reported. In contrast, we have observed an increase in plasma glutathione concentrations but no severe reduction in the activity of antioxidant enzymes in plasma, red cells, or granulocytes, which may explain the lack of plasma lipid peroxidation shown during this kind of extracorporeal treatment. In addition, LDL isolated at the end of apheresis procedures are more resistant to oxidation. These findings suggest that LDL apheresis is safe with respect to radical mediated injury.

Antioxidants↗
PubMed1999

Demonstration of a probenecid-inhibitable anion exchanger involved in the release of cortisol and cAMP and in the uptake of p-aminohippurate in bovine adrenocortical cells.

Recently we provided evidence for the involvement of a probenecid-inhibitable anion exchanger in cortisol release from primary cultures of bovine adrenocortical cells. In the present study, we further characterized this exchange transporter. Adrenocorticotropic hormone stimulated 3H-p-aminohippurate (3H-PAH) uptake into as well as cortisol release from the cells about two- and tenfold, respectively. Probenecid inhibited both 3H-PAH uptake and cortisol release by about 55 and 63%. Preincubation of the cells with 1 mM PAH trans-stimulated 3H-PAH uptake by 30%, whereas cortisol release was inhibited by 30%. 3H-PAH uptake was cis-inhibited by 1 mM glutarate or by 1 mM cortisol in the medium, while cortisol release was trans-stimulated by glutarate. PAH in the incubation medium showed saturable cis-inhibition of 3H-PAH uptake. The release of cyclic adenosine monophosphate, a substrate of the renal PAH exchanger, was also inhibited by probenecid and trans-stimulated by glutarate. In summary, the trans-stimulation and cis-inhibition experiments support the concept of an anion exchanger involved in cortisol and cyclic adenosine monophosphate release from and PAH uptake into adrenocortical cells.

Adrenal Cortex↗
PubMed1999

Interstitial pathomechanisms underlying progressive tubulointerstitial damage.

Progressive renal disease poses an increasing problem for the medical community. Though the causes of end-stage renal failure are multiple, the histologic pictures of chronic renal disease are remarkably similar being characterized by interstitial infiltration, fibrosis, tubular atrophy and dilatation. This similarity points to a final common pathway. In addition, renal disease often progresses despite elimination or amelioration of the inciting stimulus. This review deals with the pathomechanisms of progressive renal failure proposing a three-step model of fibrogenesis with an induction phase, a phase of inflammatory, and, lastly, a phase of postinflammatory matrix synthesis. The central role of the tubular epithelial cell as a mediator of interstitial inflammation and its participation in matrix synthesis will be discussed particularly. Finally, a brief overview is listed on new therapeutic approaches to limit the progressive nature of fibrogenesis.

Animals↗
PubMed1999

Abnormal growth and clonal proliferation of fibroblasts in an animal model of unilateral ureteral obstruction.

The time course for the development of renal interstitial fibrosis (RIF) in rats between days 5 and 25 after unilateral ureteral obstruction (UUO) was studied. In kidneys with UUO under histological examination, an interstitial fibrosis was observed after more than 10 days with progression up to day 25. On day 5, collagen peptidase activity in homogenates of UUO kidneys was about 50% higher than in controls but gradually declined afterwards until reaching the level obtained from contralateral kidneys (CL) on day 25. 10 days after UUO, renal hydroxyproline content was elevated about twofold as compared to CL and sham-operated rats, and increased considerably by day 25 of UUO. In primary cultures of cells obtained from UUO kidneys, fibroblast proliferation increased regardless of the extent of fibrosis. This could be a result of an early inflammatory process. Renal fibroblasts from rats are heterogenous when studied in vitro. When fibroblasts of passage 1 obtained from kidneys 25 days after UUO were plated at low density, the number of mitotic type I clones was elevated 5.5-fold as compared with cultures from CL kidneys. The majority of type I clones in UUO cultures from fibrotic kidneys developed in an unusual fashion with formation of three-dimensional structures. The changes detectable under the unfavorable conditions of clonal culture suggest phenotypical differentiation of a small fraction of fibroblasts from kidneys with RIF. These cells are able to overgrow cell monolayers forming circular growing colonies. Obviously, one needs to distinguish between intensive proliferation as a consequence of acute inflammation, and the changes in phenotype of a small fraction of renal fibroblasts which are resistant to normal physiologic regulative mechanisms in cell culture. The latter may contribute to matrix disorders and RIF.

Animals↗