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K Neubauer

Publications and source records attributed to K Neubauer.

32 records · Page 2Linked to original sources
PubMed1995

Extracellular matrix proteins as early markers in diabetic nephropathy.

Basement membrane thickening and mesangial expansion characterize the renal involvement in diabetes mellitus and precede any symptoms of renal dysfunction, e.g., albuminuria and changes in glomerular filtration rate. Since the morphological changes can only be diagnosed by biopsy, this study was designed to investigate whether the urinary excretion of renal extracellular matrix proteins might reflect the morphological alterations. To specify the extent of renal involvement in diabetes, the patients, type I as well as type II diabetics, were classified according to their urinary albumin excretion: normal albumin excretion below 30 micrograms/min, microalbuminuria from 30 to 300 micrograms/min, and overt albuminuria above 200 micrograms/min. Laminin, collagen IV, and fibronectin, all intrinsic components of the renal extracellular matrix, were determined in serum and urine by radioimmunoassay or enzyme-linked-immunosorbent-assay, respectively. The results are given as median values (mean). Additionally, the urinary fragment pattern of fibronectin was analysed qualitatively by immunoblotting. Laminin concentrations in serum and in urine did not change in diabetics. Collagen IV decreased in serum of patients with increased albumin excretion (controls: mean = 255 micrograms/l, normoalbuminuric patients: mean = 56 micrograms/l, microalbuminuric patients: mean = 52 micrograms/l, and patients with overt albuminuria: mean = 70 micrograms/l; alpha < 0.01) and increased in urine (controls, normoalbuminuric and microalbuminuric patients: not detectable, patients with overt albuminuria: mean = 5 ng/12 h; apha < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Expression of von Willebrand factor in normal and diseased rat livers and in cultivated liver cells.

Von Willebrand factor (vWf) is an adhesive glycoprotein known to play an important role in hemostasis and in tissue injury. Because the latter process resembles hepatic fibrogenesis, we studied the tissue distribution of vWf in diseased livers. In normal rat liver vWf was strongly expressed in the vascular endothelium and as small spots or fiber-like structures in the hepatic parenchyma. During acute liver injury, pronounced staining was observed within the area of necrosis. In fibrotic livers vWf deposits were distributed predominantly at the scar-parenchyma interface but also within the septum and in sinusoidal lining cells. Testing different liver cell populations in vitro demonstrated that vWf gene expression was limited to endothelial cells (ECs) and, therefore, the latter cell population might represent the vWf-positive cells detected in vivo. The distribution of vWf within fibrotic septa suggests that vWf becomes a component of the extracellular matrix (ECM) in fibrotic livers.

Animals↗
PubMed1994

Entactin gene expression in normal and fibrotic rat liver and in rat liver cells.

BACKGROUND: Entactin, a constituent of basement membranes, is a sulfated glycoprotein with binding sites for laminin, collagen type IV, fibronectin, and cell surfaces. As it is known that excess matrix deposition and sinusoidal basement membrane formation is a central characteristic of liver fibrogenesis, we investigated whether the entactin gene is expressed in normal and in damaged rat liver and which cell types are able to express this gene. In addition, we were interested in the cellular origin and time course of laminin synthesis, a matrix protein closely associated with entactin. EXPERIMENTAL DESIGN: Entactin gene expression was analyzed in normal, acutely and chronically damaged rat livers (CCl4-model) by immunohistochemistry and in situ detection of specific transcripts. Rat fat-storing cells (FSC) (Ito), hepatocytes, Kupffer cells, liver endothelial cells, arterial smooth muscle cells (SMC), and skin fibroblasts (SF) were isolated according to standard techniques. Entactin gene expression in cultured cells was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of immunoprecipitates, Northern blot analysis, and immunocytochemistry. RESULTS: In normal liver, entactin was detected in the vessel walls as continuous deposits and in a spot-like fashion along the sinusoids. Entactin was detectable among the cells of the inflammatory infiltrates of acutely damaged liver and in connective tissue septa, in the walls of newly formed vessels and bile ducts of fibrotic liver. Laminin distribution in the vessels was similar, but it was additionally present in the space of Dissé of damaged liver. By in situ hybridization, few entactin-positive cells were found in normal liver sections. Strongly positive cells were scattered over the injured parenchyma of acutely and chronically damaged livers. Northern blot analysis of total RNA extracted from normal and damaged liver tissue showed a distinct increase of entactin specific transcripts during development of fibrosis. Hybridization of total RNA from cultured FSC, hepatocytes, Kupffer cells, endothelial cells, SMC, and SF revealed entactin specific mRNA in FSC, SMC, SF, and endothelial cells; laminin mRNA was found in FSC and SF. Synthesis and secretion of both proteins were found in FSC, SMC and SF. Entactin and laminin gene expression increased in parallel to FSC during time in culture. CONCLUSIONS: Among the main liver cells, FSC show the highest entactin gene expression and might therefore play the dominant role in the synthesis of this protein in normal and fibrotic liver. However, endothelial cells and liver myofibroblasts could also contribute to entactin production.

Animals↗
PubMed1993

Localization and mRNA steady-state level of cellular fibronectin in rat liver undergoing a CCl4-induced acute damage or fibrosis.

In an attempt to investigate cellular fibronectin synthesis and deposition during acute liver damage and fibrogenesis, we used the presence of the additional type III-related ED-A domain of cellular fibronectin as a characteristic for distinguishing it from the plasma form. Using site-specific antibodies, we localized cellular fibronectin deposition in the necrotic pericentral areas of acutely damaged liver tissue after a single CCl4-gavage, whereas in control liver only trace amounts of cellular fibronectin were detectable along the sinusoids. Upon several CCl4-administrations leading to liver fibrosis, cellular fibronectin deposits were accumulated in the fibrotic septa. Northern blot hybridization using a cDNA representing part of the ED-A domain revealed that in liver tissue, in response to an acute intoxication, cellular fibronectin synthesis was initiated within the first 48 h after CCl4-gavage. By in situ hybridisation transcripts for cellular fibronectin were identified in the necrotic areas of acutely damaged tissue restricted to single, pericentrally located cells, whereas no cellular fibronectin mRNA was detectable in control liver. During fibrogenesis cellular fibronectin transcripts were shown to be synthesized in the immediate vicinity of septa. We conclude that upon acute or chronic intoxication, cellular fibronectin is a member of the accumulating biomatrix and is produced locally by mesenchymal liver cells.

Animals↗
PubMed1993

Genetic characterization of six parasitic protozoa: parity between random-primer DNA typing and multilocus enzyme electrophoresis.

We have assayed genetic polymorphisms in several species of parasitic protozoa by means of random amplified polymorphic DNA (RAPD). One goal was to ascertain the suitability of RAPD markers for investigating genetic and evolutionary problems, particularly in organisms, such as the parasitic protozoa, unsuitable for traditional methods of genetic analysis. Another goal was to test certain hypotheses concerning Trypanosoma cruzi, and other protozoa, that have been established by multilocus enzyme electrophoresis. The RAPD results corroborate the hypothesis that the population structure of T. cruzi is clonal and yield a phylogeny of the clonal lineages in agreement with the one obtained by enzyme electrophoresis. This parity between the two sets of results confirms that RAPD markers are reliable genetic markers. The RAPD markers are also suitable for reconstructing species phylogenies and as diagnostic characters of species and subspecific lineages. The number of DNA polymorphisms that can be detected by the RAPD method seems virtually unlimited, since the number of primers can be increased effectively at will. The RAPD method is well suited for investigating genetic and evolutionary questions in certain organisms, because it is cost effective and demands no previous genetic knowledge about the organism.

Animals↗
PubMed1992

The gene of hepatocyte growth factor is expressed in fat-storing cells of rat liver and is downregulated during cell growth and by transforming growth factor-beta.

Hepatocyte growth factor (HGF) has been detected in non-parenchymal cells but not in hepatocytes. We performed Northern blot analysis of total RNA extracted from rat hepatocytes, Kupffer cells, endothelial cells and fat-storing (Ito-) cells. Total RNA was extracted from fat-storing cells at different times after isolation and from cells treated with different amounts of transforming growth factor beta. The RNA was hybridized with HGF, fibronectin-, and alpha-actin-specific cDNA probes, consecutively. We found an abundant amount of HGF mRNA in freshly isolated fat-storing cells, but not in other liver cells. The amount of the HGF transcripts decreases significantly in FSC during the time of culture, while fibronectin gene expression increases and alpha-actin gene expression as well. TGF-beta dramatically inhibits HGF gene expression, but causes an enhanced fibronectin mRNA level. Northern blot hybridisation of total RNA from CCl4-chronically damaged liver with HGF cDNA shows a significant increase of HGF mRNA during development of liver fibrosis. We suggest that in damaged liver either non-parenchymal cells, others than FSC, became able to express the HGF in vivo, or other mediators overcome the inhibitory effect of TGF-beta.

Actins↗
PubMed1992

Rat hepatocytes in primary culture synthesize and secrete cellular fibronectin.

Fibronectins, involved in cell-matrix interactions and cell attachment, are glycoproteins which show a remarkable heterogeneity, due to alternative splicing. The type III-related domains, ED-A and ED-B, are present in cellular fibronectin in a variety of ratios whereas they are absent in circulating plasma fibronectin. Fibronectin synthesis by hepatocytes which are accepted as suppliers of plasma fibronectin was studied in primary cultures during a 6-day culture period. Using site-specific antibodies we demonstrate that rat hepatocytes are also able to synthesize and secrete fibronectin bearing the ED-A domain from Day 3 on after inoculation. By immunocytological characterization of the hepatocyte monolayer with antibodies directed against desmin, laminin, collagen IV, alpha-SM-actin, or ED-1 or factor VIII-related antigen, contaminating mesenchymal hepatic cell-types as a source for cellular fibronectin production could be ruled out. Dexamethasone treatment caused enhanced fibronectin synthesis and cellular fibronectin was already detectable at Day 1 after plating. Elevation of cellular fibronectin synthesis after prolonged culture-terms and by dexamethasone could also be demonstrated on mRNA steady-state level, using ED-A cDNA as a probe in hybridization analysis. Dot blot hybridisation proved a prominent response of cellular fibronectin mRNA level to dexamethasone at Day 1 when dexamethasone treatment resulted in an increased contribution of ED-A-positive fibronectin transcripts to total fibronectin mRNA level.

Animals↗
PubMed1992

Synthesis of cellular fibronectin by rat liver fat-storing (Ito) cells: regulation by cytokines.

Fibronectins are multifunctional extracellular matrix glycoproteins that seem to play a pacemaker role in liver fibrogenesis. The expression of cellular fibronectin by rat liver fat-storing cells in primary culture and their modulation by cytokines was studied. Cellular fibronectin was localized in the cytoplasm and on the surface of cultured fat-storing cells as well as in extracellular matrix fibrils by indirect immunofluorescence. Immunoprecipitation of endogenously labeled fibronectin using type specific antibodies showed the synthesis and secretion of cellular fibronectin by fat-storing cells in vitro. ED1 positive sequences specific for cellular fibronectin and absent in plasma fibronectin were detected within the total RNA of fat-storing cells. Cellular fibronectin synthesis was severalfold enhanced in "activated" vs. "resting" fat-storing cells. Treatment of fat-storing cells with transforming growth factor beta 1 resulted in a dose dependent increase of fibronectin synthesis. In contrast, interferon gamma inhibited the synthesis of fibronectin. The stimulation of fibronectin synthesis by transforming growth factor beta 1 and the inhibition by interferon gamma might be of importance for pathophysiology and therapy of liver fibrogenesis.

Animals↗
PubMed1992

Epidural spinal electrical stimulation for severe angina: a study of its effects on symptoms, exercise tolerance and degree of ischaemia.

The effectiveness of epidural spinal electrical stimulation has been studied in 14 patients with severe intractable angina unresponsive to standard therapies including bypass grafting. After implantation of the neurostimulator units the patients were assessed by a symptom questionnaire, treadmill exercise testing and right atrial pacing. There was a significant improvement of symptoms and GTN consumption fell markedly. With the neurostimulator on, exercise duration increased from a mean (CI) of 414 (153) to 478 (149) s, and total ST segment depression was less both at maximum exercise (7.1 (4.5) vs 5.6 (4.2) mm) and at 90% of the maximum control heart rate (3.5 (3.7) vs 2.6 (4.3) mm), with similar rate-pressure product at maximum exercise. With right atrial pacing the maximum heart rate reached before onset of angina was increased (143 (14) to 150 (7) b.min-1) and total ST segment depression was less at all heart rates. Benefit has persisted in some patients for over 2 years without any apparent adverse sequelae. Epidural spinal electrical stimulation is, therefore, an alternative therapy for some patients with intractable angina which has not responded to standard therapies.

Angina Pectoris↗
PubMed1992

Dementia and driving.

Many European countries test cars, but not their drivers, as they age. There is evidence to suggest that human factors are more important than vehicular factors as causes of motor crashes. The elderly also are involved in more accidents per distance travelled than middle-aged drivers. As the UK relies on self-certification of health by drivers over the age of 70 years, we examined the driving practices of patients with dementia attending a Memory Clinic. Nearly one-fifth of 329 patients with documented dementia continued to drive after the onset of dementia, and impaired driving ability was noted in two-thirds of these. Their families experienced great difficulty in persuading patients to stop driving, and had to invoke outside help in many cases. Neuropsychological tests did not help to identify those who drove badly while activity of daily living scores were related to driving ability. These findings suggest that many patients with dementia drive in an unsafe fashion after the onset of the illness. The present system of self-certification of health by the elderly for driver-licensing purposes needs to be reassessed.

Accidents, Traffic↗
PubMed1985

Treatment of neonatal hyperbilirubinaemia with flumecinolone, a new enzyme inducing drug.

The effect of flumecinolone, a new drug with enzyme inductor properties, on non-haemolytic hyperbilirubinaemia of term and premature newborns has been investigated. Prophylactic treatment with the drug prevented the development of severe hyperbilirubinaemia. Alone or in combination with phototherapy, flumecinolone inhibited the steep rise of serum bilirubin in premature infants. A similar effect has been shown in term babies with haematomas. The new drug is void of all side-effects of phenobarbital.

Benzhydryl Compounds↗