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Biomedical subjects

B Kreft

Publications and source records attributed to B Kreft.

At least 109 records · Page 6Linked to original sources
PubMed1992

Adherence to and cytotoxicity of Escherichia coli for eucaryotic cell lines quantified by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide).

Adherence of Escherichia coli to human epithelial cells (HEp-2) was studied using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) which is cleaved by enzymes of eucaryotic or procaryotic cells to formazan. This method allows to quantify adherence of Escherichia coli to HEp-2 cells and offers the advantage of assaying a large number of eucaryotic cells without using specific antisera or radioactive material. Furthermore, toxic effects of isolated hemolysin cloned in Escherichia coli onto a renal tubular cell line (LLC-PK1) was investigated by this method, showing reduced cellular viability of tubular cells after an incubation period of 10 to 20 min. MTT is therefore considered to be useful to assay the adherence of Escherichia coli to eucaryotic cells and to quantify toxic effects in eucaryotic cells induced by bacterial virulence factors.

Bacterial Adhesion↗
PubMed1992

Is Escherichia coli invading tubuloepithelial cells?

The adhesion of Escherichia coli to host epithelium cells is the very first step of urinary tract infections followed by the internalization of the bacteria into these cells. These steps are influenced by several surface antigens or products of the pathogen, e.g. fimbriae or adhesins, K antigen, and hemolysin. The bacterial adherence and the internalization of several isogenic E. coli O18 strains differing in the expression of K5 antigen, hemolysin, and type of fimbriae were measured by using a permanent line of porcine tubuloepithelial cells (LLC-PK1). Strains with K5 antigen were reduced in their adherence and internalizability as compared to the K-negative strains. The expression of hemolysin by these strains lead to an increase of adherence and internalization. The internalization of bacteria is influenced mainly by their adherence to the epithelial cells. Thus, the engorgement of attached bacteria is rather a kind of endocytosis than an invasion of bacteria.

Animals↗
PubMed1992

Aggregation substance of Enterococcus faecalis mediates adhesion to cultured renal tubular cells.

The sex pheromone system of Enterococcus faecalis is a unique, highly efficient plasmid collection mechanism for this species. A crucial role in this system is played by an adhesin called aggregation substance which enables the cell-cell contact between donor and recipient strains. The existence of the amino acid motif Arg-Gly-Asp-Ser in the adhesin prompted us to look for a possible binding of E. faecalis cells expressing aggregation substance to eucaryotic cells. We were able to show that the adhesin mediated binding to cultured renal tubular cells (porcine cell line LLC-PK1) via light microscopic, electron microscopic, and enzyme-linked immunosorbent assay-based studies. Synthesis of the adhesin was induced by some component(s) of serum. These data are interpreted to mean that aggregation substance is an adhesin mediating not only cell-cell contact between different E. faecalis strains but also binding of E. faecalis to eucaryotic cells, and therefore it might contribute to virulence.

Amino Acid Sequence↗
PubMed1992

Identification and characterization of a surface-associated protein (Ssp) of Staphylococcus saprophyticus.

A 95-kDa protein was isolated from Staphylococcus saprophyticus 7108 grown on dialysis membranes placed on the surface of brain heart infusion agar. Strain CCM883 did not produce this protein. Ultrathin sections revealed the presence of very thin, tuftlike, 50- to 75-nm-long structures on the surface of strain 7108, whereas strain CCM883 was comparably smooth. The surface material could be removed by digestion with proteinase K, suggesting that the surface structures contain protein. High-resolution scanning electron microscopy showed a thick layer of surface material on strain 7108, whereas strain CCM883 appeared smooth. The 95-kDa protein was purified by Sephacryl S-300 chromatography, and an antiserum was raised in rabbits. This antiserum was used in immunogold labeling experiments, which showed that the protein is associated with the surface structures. Our experiments thus demonstrate the presence of a fibrillar protein on the surface of S. saprophyticus (Ssp for S. saprophyticus surface-associated protein).

Animals↗
PubMed1991

Adhesion of Staphylococcus saprophyticus to renal tubular epithelial cells is mediated by an N-acetyl-galactosamine-specific structure.

S. saprophyticus CCM883 and 9325 were found to adhere to the tubular cell line LLC-PK1. An ELISA technique was used to determine adherence of bacteria and inhibition of adherence by various carbohydrates. Only N-acetyl-galactosamine was found to significantly inhibit adhesion (p less than 0.001), which suggests that the surface component mediating adhesion recognizes structures on the target cell that contain this carbohydrate.

Acetylgalactosamine↗
PubMed1991

Experimental studies on the nephrotoxicity of amphotericin B in rats.

The renal effects of amphotericin B alone and in combination with cyclosporin A, tobramycin, fosfomycin, D-glucaro-1,5-lactam and verapamil were studied in rats. The parameters for nephrotoxicity were urinary loss of tubular cells and malate dehydrogenase, as well as creatinine clearance. Repeated intraperitoneal injections of amphotericin B led to an increase of urinary tubular cell elimination and malate-dehydrogenase. After co-administration of amphotericin B and cyclosporin A, the urinary loss of tubular cells increased and creatinine clearance was reduced. A combination of amphotericin B and tobramycin reduced tubular cell elimination but the creatinine clearance improved. When verapamil was combined with amphotericin B, endogenous creatinine clearance increased, though the loss of tubular cells was elevated. Furthermore, fosfomycin reduced the loss of tubular cells and improved renal functional parameters in combination with amphotericin B. In addition, D-glucaro-1,5-lactam was found to reduce the urinary loss of tubular cells induced by amphotericin B.

Amphotericin B↗
PubMed1990

[Qualitative and quantitative NMR tomographic findings in focal nodular hyperplasia of the liver].

The qualitative and quantitative MRI findings in 16 patients with focal nodular hyperplasia (FNH) of the liver are described; nine of these were confirmed histologically. A central scar is typical of FNH and provides a reliable diagnosis. This finding was seen in half the cases. If the scar is not demonstrable, the following features suggest the diagnosis: smooth margins, homogeneous signal distribution, increased signal intensity in T2-weighted spin-echo images and reduced signal intensity in inversion-recovery sequences. The T1 and T2 relaxation times in FNH are increased by about 30% compared with normal liver tissue.

Adult↗
PubMed1990

Experimental studies on nephrotoxicity and pharmacokinetics of LY 146032 (daptomycin) in rats.

The nephrotoxicity and pharmacokinetics of LY 146032 (daptomycin) were studied in an experimental rat model. Nephrotoxicity was assessed by measuring urinary loss of tubular cells and malate dehydrogenase. LY 146032 (10-250 mg/kg daily iv) led to a dose-dependent and reversible increase of cell elimination. The tubulo-toxic threshold dose is stated to be 10 mg/kg daily. Nephrotoxicity induced by LY 146032 can be reduced by coadministration of fosfomycin or D-glucaro-1.5-lactam, and enhanced by combination with tobramycin. LY 146032 accumulated in renal tissue during repeated administration. Electron microscopy revealed histopathological changes in the kidneys. Therefore the nephrotoxic potential of LY 146032 should be taken into consideration in clinical trials.

Animals↗
PubMed1990

Genetically engineered S and F1C fimbriae differ in their contribution to adherence of Escherichia coli to cultured renal tubular cells.

Escherichia coli K-12 strains producing S-fimbrial adhesins, F1C fimbriae, and mutagenized fimbriae were tested in a binding assay with a renal tubular cell line. S-fimbrial adhesins and F1C fimbriae mediated binding to tubular cells. The SfaA, SfaG, and SfaS subunits of S fimbriae contributed to attachment. Site-specific mutations in the sfaS gene reduced binding. The inhibition profile of F1C fimbriae resembled that of S fimbriae.

Adhesins, Escherichia coli↗
PubMed1990

[Microbiological diagnosis of lower respiratory tract infections].

Successful microbiological diagnosis of lower respiratory tract infections demands a close cooperation between clinician and clinical microbiologist. Because of the broad spectrum of possible respiratory pathogens precise requests are necessary for adequate laboratory procedures. The high rate of potential pathogens requires quantitative microbiological and cytological data in order to differentiate between colonisation and infection. Pathophysiological reactions on microbial colonisation of the bronchial tree may contribute to acute exacerbations of a chronic bronchitis. The precise role of microbial nocuous agents, however, remains to be clarified.

Bronchi↗
PubMed1988

Effects of fosfomycin, mesna, and sodium thiosulfate on the toxicity and antitumor activity of cisplatin.

Fosfomycin and mesna were investigated in rats and mice concerning their detoxifying effects on cisplatin toxicity in comparison to sodium thiosulfate, a known protector against cisplatin nephrotoxicity. After separate i.p. injection of cisplatin and fosfomycin (500 mg/kg) or mesna (800 mg/kg) a slight increase in the 50% lethal dose of cisplatin was found in all animals. In mice sodium thiosulfate proved to be far more effective in preventing lethal toxicity and nephrotoxicity as measured by blood urea nitrogen increase. Fosfomycin and mesna were almost without influence on cisplatin treatment of L-1210 leukemia whereas their inhibition of the antitumor effect against S-180 ascites sarcoma (increase of in cisplatin dose to cure 50% of animals from 2.0 mg/kg to 3.5/4.7 mg/kg cisplatin) was similar to thiosulfate, which showed a strong inhibiting effect in the treatment of both tumors. In rats fosfomycin distinctively reduced the antitumor efficacy of cisplatin against Yoshida ascites sarcoma. Thus the concurrent injection of fosfomycin and mesna reduced both the toxicity and the antitumor activity of cisplatin. Therefore their simultaneous administration in addition to cisplatin via the same injection route should be avoided. Due to the weak detoxifying efficacy of fosfomycin and mesna they cannot be used instead of sodium thiosulfate for renal protection against cisplatin toxicity in local i.p. treatment modalities.

Animals↗
PubMed1987

Fosfomycin protects against tubulotoxicity induced by cis-diaminedichloroplatin and cyclosporin A in the rat.

The nephroprotective effect of fosfomycin against tubulotoxicity induced by cis-diaminedichloroplatin (DDP) and cyclosporin A (Cs) was studied in the rat. The parameter of nephrotoxicity was urinary tubular cell excretion. The experiments revealed that fosfomycin, given either concomitantly or in advance was able to reduce the nephrotoxic effect of DDP and Cs significantly. We conclude from these studies that fosfomycin is a broad-spectrum nephroprotective agent.

Animals↗
PubMed1987

[Experimental studies of the nephroprotective effect of fosfomycin].

We studied in an experimental rat model, if fosfomycin reduces the tubulotoxicity induced by tobramycin, teicoplanin, cisplatin or ciclosporine A and is thus a nephroprotective agent. 10 female wistar rats per dose and compound were used, measures of tubulotoxicity were urinary excretion rates of tubular cells and malate dehydrogenase on 5 successive days. Fosfomycin proved to be a potent nephroprotector against all 4 nephrotoxins. Its activity was not based on pharmacokinetic interactions but on a pharmacodynamic effect. Presumably, fosfomycin stabilises the membranes of lysosomes in tubular cells.

Acute Kidney Injury↗
PubMedDate not supplied

Enhancement efficacy of magnetic starch microshperes (MSM) in conventional spin-echo and turbo spin-echo sequences at 0.5 T and 1.5 T.

The efficacy of the superparamagnetic contrast agent magnetic starch microspheres (MSM) was evaluated in vitro by NMR relaxometry and in vivo by MR imaging using T2-weighted spin-echo (SE) and turbo spin-echo (TSE) sequences at 0.5 T and 1.5 T in 60 normal rats who received MSM in doses of 10-50 mu mol/kg. MR imaging was performed using T2-weighted SE and TSE sequences. The relaxation rates 1/T1 and 1/T2 for liver and spleen increased linearly with MSM concentrations up to 30 mu mol/kg body weight, and approached almost constant levels for higher doses. The slopes in the linear part of the 1/T2 diagram were 0.62 Hz +/- 0.03 for the liver and 0.51 Hz +/- 0.06 x kg/mu mol for the spleen. On all T2-weighted sequences at 0.5 T and 1.5 T, liver signal-to-noise ratio (SNR) decreased by a factor of 2-3 already at the lowest dose of 10 mu mol/kg. SNR values of TSE sequences exceeded values for SE sequences by 50-80%. The SNR decrease was not significantly different between SE and TSE sequences. Our results show that MSM is well suited as a T2 contrast agent at both magnetic field strengths when using conventional SE and fast TSE sequences.

Animals↗
PubMedDate not supplied

[Subacute sclerosing panencephalitis (SSPE) as differential diagnosis in severe personality changes and ataxia--case report and literature review].

An 8 year old girl presented with progressive change of personality and spastic ataxia since 4 weeks. A year before she had developed focal grand-mal-seizures; at this time laboratory and radiologic findings were normal. The EEG on admission demonstrated marked changes with partially focal, partially generalized hypersynchronic activity, but no SSPE-typical Radermecker-complexes. There were no cells in the cerebrospinal fluid (CSF), a slightly increased level of protein and a normal glucose. Isoelectric focusing showed predominantly measles-specific oligoclonal IgG bands in the CSF. In the magnetic resonance tomography multiple focal white matter lesions in the basal ganglia as well as in cortical and occipitoparietal regions could be seen. At the age of two the girl had suffered from measles, the child didn't receive any vaccination. The combination of history, CSF-, MRI-results and EEG lead to the diagnosis of subacute sclerosing panencephalitis (SSPE). After 3 months the clinical and radiological abnormalities had markedly increased. On the background of this history SSPE should be considered as differential diagnosis in patients with changes of personality.

Cerebrospinal Fluid Proteins↗