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Biomedical subjects

G Wolf

Publications and source records attributed to G Wolf.

At least 451 records · Page 25Linked to original sources
PubMed1991

The influence of glucose concentration on angiotensin II-induced hypertrophy of proximal tubular cells in culture.

Incubation of cultured murine proximal tubular cells in serum-free media containing 450 mg/dl of glucose resulted in cellular hypertrophy as defined by an increase in cell size, total protein content, and synthesis after 72 h. 10 nM angiotensin II further increased this hypertrophy, but failed to have any effect on cells grown in 100 mg/dl glucose. This enhancement by angiotensin II was blocked by treatment with 1 microM of the angiotensin-receptor antagonist DuP 753. Although cells incubated in either glucose media exhibited similar high-affinity angiotensin II-receptors, the receptor density was elevated only in cells grown in the presence of high glucose. Stimulation of cells in high glucose for 60 min with 10 nM angiotensin II also reduced significantly intracellular cAMP concentrations. This was not the case for proximal tubular cells cultured in normal glucose. Our results indicate that high glucose and angiotensin II have additive effects on the induction of hypertrophy in renal tubular cells.

Angiotensin II↗
PubMed1991

Synthesis and glycosylation of fibronectin in hepatocytes from vitamin A-deficient rats.

Recent work from our laboratory (Kim and Wolf, J Biol Chem 262:365-371, 1987) has shown increased uptake of labeled amino acids into fibronectin (FN), increased net synthesis of FN and increased levels of FN-mRNA in primary cultures of hepatocytes from vitamin A-deficient rats compared to controls. We now find, surprisingly, decreased uptake of labeled sugars into the oligosaccharide chains of FN from vitamin A-deficient hepatocytes. This decrease could be reversed by added retinoic acid at physiological concentration. At the same time, FN from deficient hepatocytes (-A.FN) was more susceptible to proteolytic degradation. Decreased uptake of the core sugar mannose into -A.FN was similar to that of glucosamine, yet the percent of label in sialic acid was the same as in + A.FN, suggesting a smaller number of oligosaccharide chains per molecule of -A.FN. Upon enzymatic removal of oligosaccharide and labeling with sodium borotritide, it was found that both -A.FN and +A.FN had biantennary oligosaccharide structures. Selective enzymatic removal of sialic acid showed that +A.FN had both sialic acids in an alpha 2----3 linkage, whereas -A.FN apparently had one alpha 2----3 and one alpha 2----6-linked sialic acid. The borotritide experiments allowed us to calculate that +A.FN appeared to have 5 oligosaccharide chains per FN monomer, whereas the -A.FN showed only 4 chains. These results would account for the decreased glycosylation and increased susceptibility to proteolysis of the -A.FN. We conclude that vitamin A controls both the rate of synthesis of the polypeptide chain of FN via its mRNA, as well as the rate of its glycosylation.

Acute-Phase Proteins↗
PubMed1991

Heme-dependent catalase activity of lactobacilli.

The heme-dependent catalase in Lactobacillus pentosus, L. sake, L. delbrueckii and Enterococcus faecalis was studied. The catalase was formed by cells grown aerobically in the presence of hematin or for lactobacilli when grown without added hematin, after incubation of buffered cells in the presence of hematin. The kinetics of the production of catalase revealed maximum activity for L. pentosus and E. faecalis at late stationary and late logarithmic growth phase, respectively. The physiological role of catalase was studied with L. sake. The presence of hematin allows higher growth yields, since it protects the cells against hydrogen peroxide formed endogenously up to concentrations of 4.6 mmol/l.

Culture Media↗
PubMed1991

Effects of MK-801, ketamine and alaptide on quinolinate models in the maturing hippocampus.

The ability of the N-methyl-D-aspartate receptor antagonists, MK-801, ketamine and alaptide [a newly synthesized cyclo(1-amino-1-cyclopentane-carbonyl-L-alanyl) with protective properties in models of hypoxia], to prevent neuronal degeneration caused by intracerebroventricular application of quinolinic acid was investigated. Neurodegenerative effects of quinolinate in the hippocampal formation were found to increase with the degree of maturity of glutamatergic target structures. A protective potency of the N-methyl-D-aspartate receptor antagonists was observed at all developmental stages studied (12- and 30-day-old and adult rats). MK-801 showed the highest efficacy, alaptide the lowest. These findings suggest a parallelism in maturity of glutamatergic transmission processes as one prerequisite of quinolinate vulnerability and postnatal increases of target fields of the protectives. Application of MK-801 or ketamine after quinolinate injection intensified their protective effects when compared to simultaneous or preadministration. This observation is interpreted as indicating that quinolinate is a prompter of a delayed neurodegenerative process rather than acting immediately as a toxicant.

Animals↗
PubMed1991

Magnesium sulphate subcutaneously injected protects against kainate-induced convulsions and neurodegeneration: in vivo study on the rat hippocampus.

Kainate, an agonist of a unique subclass of glutamate receptors (kainate receptor), was injected intracerebroventricularly in rats to induce convulsive reactions and hippocampal damage in order to model glutamate-mediated brain injury. Rats treated with magnesium sulfate (subcutaneously injected, up to 600 mg/kg) were found to be protected from kainate neurotoxicity depending on the dose and time of application. Results were largely consistent with those obtained previously by using quinolinate as an excitotoxic N-methyl-D-aspartate-receptor agonist. Magnesium is discussed as being a natural and relatively safe therapeutic in cases of glutamate-induced (hypoxic, ischemic, traumatic, or convulsive) disorders of the brain.

Animals↗
PubMed1991

Computer-assisted image analysis of nucleolar organizer regions (NORs): a pilot study of astrocytomas and glioblastomas.

Computer-assisted image analysis was used to measure nucleolar organizer regions (NORs) of 22 astrocytomas and glioblastomas. Image analysis provides reproducible information about number and size of NORs together with further karyometric data, which can be compared and processed with other patient-related data. Our study exhibits a statistical relationship between number and size of NORs and malignancy of the measured gliomas.

Astrocytoma↗
PubMed1991

Expression of homeobox genes in a proximal tubular cell line derived from adult mice.

We have been studying the expression of several homeobox genes in cultures of proximal tubular epithelium (MCT cells) harvested from adult mus musculus. Hox genes 2.1, 2.3, and 3.3, in particular, are all expressed at low levels in resting MCT cells. The expression of Hox 2.1 and 3.3 were not influenced by mitogenic (epidermal growth factor: EGF, and platelet-derived growth factor: PDGF) nor by hypertrophogenic cytokines (angiotensin II: Ang II) in serum-free media. Transcripts for Hox 2.3, however, were elevated in MCT cells by Ang II. EGF, and serum treatment, as early as 30 minutes after their addition, whereas no change, or slight reductions were observed with transforming growth factor beta (TGF beta), PDGF, and gamma-interferon (gamma IFN). Hox 2.3 was also super-induced by serum, in the presence of cycloheximide, in cells rested previously in serum-free media, suggesting that new protein synthesis was not required for expressive augmentation. The induction of Hox 2.3, moreover, was not specific for tubular epithelium, since the gene could be activated in tubulointerstitial fibroblasts after treatment with EGF. These experiments collectively represent a first report regarding the characterization of transcripts encoding homeoboxes in adult cells derived from renal tissue. The putative DNA-binding properties of homeobox proteins in general, the prompt and rapid induction of Hox 2.3 by morphogenic cytokines in tubulointerstitial cells, and the observed effect of cycloheximide on this gene, all indicate that Hox 2.3 might have a role in the general activation of mature somatic cells, as an immediate early event. probably in the capacity of a nuclear trans-acting factor.

Animals↗
PubMed1991

Molecular mechanisms of tubulointerstitial hypertrophy and hyperplasia.

Adult kidneys, which are principally composed of tubulointerstitium, do not normally regenerate or expand their working pool of functional cells at a very high rate. Loss of kidney tissue, however, can lead to some compensatory renal enlargement. The catalytic forces initiating such exchanges have not been fully articulated by current experimental endeavors. Increasing evidence, nevertheless, does suggest that factors other than simple changes in renal hemodynamics may be involved in this process. Different cellular elements in the tubulointerstitial microenvironment probably modulate changes in tubular enlargement or size through a complex cytokine network. Autocrine and paracrine stimulation of enlargement by different local growth factors also seem to play a pivotal role. After binding to cellular receptors, these factors activate signal transduction pathways resulting in expression of immediate early genes, which by themselves can synchronize the expression of subsequent genes through the medium of transacting factors. The renal enlargement response can also be modified by endocrine hormones that can activate such genes directly and/or stimulate other adjunctive processes, like receptor expression for the regional binding of growth factors. Furthermore, renal enlargement is under negative feedback of inhibitory factors like TGF beta. It is possible, for example, that special genes exist which are only expressed to arrest enlargement. It has been further suggested that activation of the Na+/H+ antiporter is a common denominator in renal enlargement. Recent findings, however, indicate that the activation of this antiporter is not always necessary, and might rather be a parallel event rather than a key phenomena in tubular enlargement. G0/G1 transition of tubular cells seems to involve similar factors in tubular hypertrophy and hyperplasia. The factors which are responsible for the final determination of the enlargement pattern (hypertrophy vs. proliferation) are unknown. The separation between hypertrophy and hyperplasia, although suggested by striking differences in cellular regulation, may be somewhat artificial, since responses leading to tubular enlargement also exist in circumstances where hyperplasia and hypertrophy are combined events. Recently it has been proposed that growth factors stimulate gluconeogenesis in proximal tubular cells producing hyperplasia, whereas factors inhibiting gluconeogenesis might induce hypertrophy. Whether the common pathway message of this intriguing hypothesis is correct still requires further validation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

[Comparative study of introital sonography and the urethrocystogram in women before and after surgery for stress incontinence].

In a prospective study of sonographic and radiographic methodologies we compared morphologic bladder data in 30 patients before and after stress incontinence surgery. 18 women were subject to colposuspension according to Burch due to recurrent stress incontinence, 12 women underwent anterior colporrhaphy. Visualisation of bladder, urethra and beta-angle was adequate with both methods. The good visualisation of the anatomical and functional situation of the vesico-urethral area is a major benefit of introital sonography.

Adult↗
PubMed1991

[Regeneration of the ciliary beat of human ciliated cells].

The influence of an isotonic, alkaline saline solution (diluted "Emser Sole" or brine from the spa of Bad Ems) on the ciliary beat of isolated cultured human ciliated cells of the upper respiratory tract was investigated. The ciliary beat was observed via an inverted phase contrast microscope (Zeiss Axiomat IDPC) and measured microphotometrically under physiological conditions and after the damaging influence of 1% propanal solution. Under physiological conditions the saline solution had a positive, although statistically not significant influence on the frequency of the ciliary beat. After damage of the cultivated cells by 1% propanal solution, the saline solution had a significant better influence on the regeneration of the cultured cells than a physiological sodium chloride solution. It is concluded that diluted brine from Bad Ems has a positive effect on the ciliary beat of the respiratory epithelium and accelerates its regeneration after damage by viral and bacterial infections, surgery or inhaled noxae.

Aldehydes↗
PubMed1991

Intracellular signaling of transcription and secretion of type IV collagen after angiotensin II-induced cellular hypertrophy in cultured proximal tubular cells.

Physiologic concentrations of angiotensin II (AII) can induce cellular hypertrophy in murine proximal tubular epithelium (MCT cells). This response is characterized by an increase in cell size, new protein synthesis, and by the secretion of new basement membrane type IV collagen in the absence of cellular proliferation. The present study was undertaken to evaluate the second messengers of these AII-induced cellular events with special reference to the increase in type IV collagen secretion. In initial experiments we observed that pretreatment of MCT cells with agents that increase concentrations of intracellular cAMP, like forskolin, dibutyryl cAMP, and isobutyl-methyl-xanthine abolish AII-induced amino acid incorporation, but have no effect on control cells or on their proliferation. In addition, 10(-8) M AII significantly decreased the concentration of intracellular cAMP. Phorbolesters were without significant effect on the hypertrophy or proliferation of AII-stimulated MCT cells or their rested controls. The transfection of MCT cells with reporter genes containing regulatory elements for type IV collagen revealed that the stimulatory effects of AII on collagen type IV depend, at least to some extent, on an increase in gene transcription. Agents increasing intracellular cAMP concentrations inhibited the AII-induced increase in transcription and secretion of collagen type IV, but had no effect on MCT cells grown in media without AII. Our findings provide evidence that AII-induced changes in tubular epithelium leading to the secretion of type IV collagen are mediated by a decrease in intracellular cAMP.

1-Methyl-3-isobutylxanthine↗
PubMed1991

The effect of diacylglycerols on fibronectin release and its reversal by retinoic acid in cell culture.

Previous work from our laboratory showed that tumor promoters such as phorbol ester (TPA) stimulated the release of fibronectin (FN) from the surface of several cell types in culture, and that this stimulation was counteracted by retinoic acid. Diacylglycerols (DAGs) are the endogenous ligands of the TPA receptor and can activate and translocate protein kinase C (PKC) in a manner similar to TPA. To show that the release of FN is related to activation of PKC, we tested the action of DAGs on FN release from human lung fibroblasts and its counteraction by retinoic acid. We found that DAGs stimulated the release of FN in a concentration- and time-dependent manner. The stimulation of the release of FN correlated with the translocation-activation of PKC by DAG. Retinoic acid reversed the action of DAG with respect to stimulation of FN release and inhibited this release even in the absence of DAG. These results suggest that the release of FN is in some way related to translocation-activation of PKC.

Cell Membrane↗
PubMed1991

The intracellular vitamin A-binding proteins: an overview of their functions.

The intracellular retinoid-binding proteins bind retinol, retinaldehyde, and retinoic acid for purposes of protection against decomposition, solubilize them in aqueous medium, render them nontoxic, and transport them within cells to their site of action. These binding proteins also function by presenting the retinoids to the appropriate enzymes for metabolism. The cytosolic retinol and retinoic acid-binding proteins--CRBP, CRABP, CRBP (II)--function in transport and metabolism of retinoids within parenchymal, intestinal, reproductive, and fetal cells and across blood-organ barriers. A different group of retinoid-binding proteins, more related to serum retinol-binding protein, functions in epididymis and uterus. Retinaldehyde-binding protein aids in the oxidation-reduction reaction of 11-cis-retinol-11-cis-retinaldehyde in the retina, where the interphotoreceptor retinol-binding protein transports retinol between pigment epithelium and photoreceptors. Finally, a group of retinoic acid-binding proteins termed "receptors" functions in the nucleus by attaching to promoter regions of a number of specific genes to stimulate their transcription and thus affect growth, development, and differentiation.

Animals↗
PubMed1991

[Frequency distribution, microscopic image analysis and grading of mammary carcinoma].

The frequency of diagnoses of breast diseases in 1685 patients was examined on the basis of biopsy material at the Institute of Pathology of Charité Hospital in Berlin, during 1984-1987, with particular consideration of histological types of mammary carcinomas. Breast cancer was detected in 562 patients of whom 429 had undergone operations according to standardized recommendations by the Charité Department of Surgery. Histological tumor classification, postoperative staging and, in cases of invasive ductal carcinoma, also histological grading were part of the pathologico-anatomic investigation. Reproducibility of grading was 72.7% for intra-observer examination and 63.3% for evaluation by different pathologists. A group of 20 premenopausal patients with tumors staged as pT1, pN0 was selected for morphometric studies and objectivation of tumor grading. HE-stained paraffin sections were made for conventional grading according to Bloom and Richardson (1957), whereas Feulgen reaction in 4 microns thick sections was used for quantitative examination by means of a microscopic image analysis system (Robotron A6471 with AMBA/R software). The measuring program used was based mainly on evaluation of karyometric features. Measurements were concentrated on analysis of the chromatin structure of tumor cell nuclei. Correlations with histological grading were found to exist for 16 features out of 28 parameters selected for statistical analysis. Some new parameters of the texture of tumor cells nuclei were demonstrated to be strongly correlated with the degree of tumor differentiation. The prognostic significance of nuclear texture features has to be proved by further studies in which clinical data of the course of the tumor disease must be included.

Adult↗
PubMed1991

Outcome predictors in selection of balloon angioplasty or surgery for peripheral arterial occlusive disease. Veterans Administration Cooperative Study No. 199.

In a selected group of men, surgical bypass and percutaneous balloon angioplasty (PTA) are equally effective therapy for ileo-femoropopliteal occlusive disease, provided immediate PTA failures are disregarded. Can we predict those patients likely to experience immediate PTA failure? Do any preintervention factors exist that favor PTA or surgical bypass for the remaining patients? Logistic regression analysis determined variables predictive of failure for the 19 immediate PTA failures and for the 17 patients with PTA and the 24 patients with surgical bypass who failed after initial intervention but before the end of 2 years. Two hundred sixty-three patients were enrolled. The analysis evaluated patient characteristics (age, weight, smoking status, diabetic status, and sickness impact profile score) as well as lesion site, percent lesion stenosis, runoff status, hemodynamic parameters, and indications. Two independent predictors of immediate PTA failure were diastolic hypertension (p = 0.032) and percent stenosis of study site (p = 0.035). The probability equation defined by the logistic regression analysis delineates patients at high risk for immediate PTA failure. Interestingly, no factor uniquely predicted delayed PTA or surgical failure. These data suggest that selected patients with diastolic hypertension and a severely stenotic or occluded artery are poor candidates for PTA. Either PTA or surgical bypass is effective therapy for the remaining patients.

Angioplasty, Balloon↗
PubMed1990

[Perioperative subjective emotional state].

The aim of adequate preoperative medication is to minimize the patient's anxiety level. Preoperative anxiety can be consciously and specifically orientated or it can be masked. This double-blind study was performed to evaluate the effects of an anxiolytic drug in comparison with a placebo perioperatively and to assess the post-operative course of the important factors anxiety, depression and asthenia. The Mannheim inventory for subjective state and STAI (State-Trait-Anxiety-Inventory) were offered. The study was undertaken in 60 female patients, who were operated for suspected carcinoma of the breast. We conclude that in such a specific group of patients extensive preoperative psychological preparation must be backed up by the administration of an anxiolytic drug.

Adaptation, Psychological↗