Search PubMed⌕ Search

Biomedical subjects

C Wolf

Publications and source records attributed to C Wolf.

At least 91 records · Page 5Linked to original sources
PubMed1999

PCR-RFLP analysis of mitochondrial DNA: a reliable method for species identification.

A method for identification of game species has been developed on the basis of the amplification of a specific part of the mitochondrial genome (tRNA(Glu)/cytochrome b) using the polymerase chain reaction (PCR). To distinguish between several game species, the obtained 464-bp-long PCR products were cut with different restriction endonucleases (RE) resulting in species-specific restriction fragment length polymorphism (RFLP). Even closely related deer species could be distinguished by application of one or two RE. Natural polymorphisms of the target sequence within one species were examined for red deer (Cervus elaphus), and base pair substitutions were identified affecting the RFLP pattern.

Animals↗
PubMed1999

Columnar lined oesophagus and intestinal metaplasia: current concepts.

Barrett's oesophagus is a condition where the distal oesophagus is lined with columnar epithelium. For the diagnosis intestinal metaplasia has to be found and a minimal length of 3 cm is required for the columnar-lined segment. It is well known that patients with the traditional Barrett's oesophagus have a higher risk of developing adenocarcinomas in the metaplastic segment. The clinical significance of shorter metaplastic segments and intestinal metaplasia at the gastro-oesophageal junction is much less certain. Different definitions are in use and the increasing number of studies dealing with these mucosal changes therefore may create confusion. In this article, the current knowledge concerning epidemiology, pathophysiology, clinical associations, diagnostic possibilities including endoscopy, pathology, measurement of differences in electrical potential, and treatment of columnar-lined oesophagus of any length and of intestinal metaplasia at the gastro-oesophageal junction is reviewed. Furthermore, the need for a consistent definition is emphasized.

Adenocarcinoma↗
PubMed1999

Oxidized derivatives of 7-dehydrocholesterol induce growth retardation in cultured rat embryos: a model for antenatal growth retardation in the Smith-Lemli-Opitz syndrome.

7-Dehydrocholesterol accumulates in fetuses affected by the Smith-Lemli-Opitz syndrome as a result of a deficit in the ultimate step of cholesterol synthesis catalyzed by Delta7 reductase. Rat embryos explanted at gestation day 10 and cultured for 48 h in the presence of the Delta7 reductase inhibitor AY 9944 were used as a model to discriminate between the beneficial effect of supplementation with cholesterol and the deleterious effect of supplementation with 7-dehydrocholesterol. Cholesterol supplementation in the form of mixed cholesterol/lecithin liposomes added to serum serving as the culture medium restores the growth of embryos which is markedly decreased in the presence of the inhibitor. 7-Dehydrocholesterol under identical conditions does not restore growth and impairs the beneficial effect of cholesterol added simultaneously. UV-photooxidation of 7-dehydrocholesterol-supplemented culture medium enhances its embryotoxicity, which suggests uptake by the embryo of toxic by-products formed from 7-dehydrocholesterol. By contrast photooxidation of cholesterol-supplemented culture medium does not induce embryotoxicity. alpha-Tocopherol reduces the toxicity of photooxidized 7-dehydrocholesterol supplementing the culture medium. We conclude that 7-dehydrocholesterol does not fulfill the cholesterol requirement of the developing embryos and exerts an additional embryotoxic effect probably via oxidized by-products. This could explain the antenatal growth retardation of SLOS by a blockage of the maternal compensatory cholesterol influx.

Animals↗
PubMed1999

[Physical arrangement of membrane lipids susceptible to being used in the process of cell sorting of proteins].

Detection of immiscible lipid domains in biological membranes offers an alternative support to protein sorting. Liquid ordered domains ("rafts") comprising cholesterol and saturated sphingolipids incorporate saturated glycosyl-phosphatidylinositol (GPI)-anchored or acylated (palmitoyl- and myristoyl-) proteins or particular transmembrane protein sequences. These lipid domains can be isolated in the form of Detergent resistant membranes (DRM) from biological plasma membrane preparations. Caveolae appear to be a differentiated fraction of plasma membranes comprising such numerous cross-linked microdomains associated with caveolin in different cell types. While the biological relevance of such membrane domains is evidenced in vivo by co-patching of proteins sharing the identical affinity for sphingolipids and by the disruption of co-patching following cell cholesterol depletion, only a few physical studies confort the principle of membrane heterogeneity. Results are now presented where cholesterol addition in a tertiary lipid mixture forces outphase-separation, as a realistic model where the lipid segregation can promote protein sorting to the segregated Lo phase. A lipid mixture comprising phosphatidylserine, phosphatidylethanolamine and sphingomyelin of natural origin in the ratio (1/4/3: mole/mole) has been rendered neatly heterogeneous after the addition of cholesterol (27 mole%). Xray diffraction (Small angle Xray scattering) showed the splitting of two neatly resolved lamellar diffractions in the presence of cholesterol. Above 37 degrees C the heterogeneity was traceable by a broadened diffraction spot up to the complete get-to-liquid transition of sphingomyelin at temperatures > 40 degrees C where the spot became again symmetrical and narrow. The large temperature range where the immiscible lamellar phases are detected, the specific requirement for cholesterol association with sphingomyelin, the positive influence of calcium and the reversibility of domain formation support the occurrence for such domains at the inner side of the plasma membrane whereon lipids-bound proteins concentrate.

Animals↗
PubMed1998

Cholesterol relieves the inhibitory effect of sphingomyelin on type II secretory phospholipase A2.

Secretory type II phospholipase A2 (sPLA2) is inhibited by sphingomyelin (SPH); cholesterol either mixed with the model glycerophospholipid substrate or added to the assay medium as separated liposomes counteracts this inhibition efficiently. The inhibition of fatty acid release assayed by quantitative gas chromatography-MS is observed when SPH is added to erythrocyte membranes as the substrate instead of a readily hydrolysable phosphatidylethanolamine/phosphatidylserine model mixture. Hydrolysis of SPH by Staphylococcus aureus sphingomyelinase suppresses its inhibitory potency. The addition of cholesterol to SPH liposomes with a 1:1 stoichiometry relieves completely the inhibition of sPLA2 exerted by SPH. The mechanism of inhibition suggested by the binding assay is that sPLA2 binds with affinity to the SPH interface, after either phase segregation at the assay temperature or on the pure SPH liposomes added to the incubation medium. Cholesterol is shown to suppress the binding affinity of the enzyme for the SPH interface. A model for inhibition is suggested in which binding of the sphingosine moiety is competitive for sPLA2 (inhibition) or for cholesterol (release of the enzyme).

Animals↗
PubMed1998

Characterization of a 190-kilobase pair domain of human type I hair keratin genes.

Polymerase chain reaction-based screening of an arrayed human P1 artificial chromosome (PAC) library using primer pairs specific for the human type I hair keratins hHa3-II or hHa6, led to the isolation of two PAC clones, which covered 190 kilobase pairs (kbp) of genomic DNA and contained nine human type I hair keratin genes, one transcribed hair keratin pseudogene, as well as one orphan exon. The hair keratin genes are 4-7 kbp in size, exhibit intergenic distances of 5-8 kbp, and display the same direction of transcription. With one exception, all hair keratin genes are organized into 7 exons and 6 positionally conserved introns. On the basis of sequence homologies, the genes can be grouped into three subclusters of tandemly arranged genes. One subcluster harbors the highly related genes hHa1, hHa3-I, hHa3-II, and hHa4. A second subcluster of highly related genes comprises the novel genes hHa7 and hHa8, as well as pseudogene PsihHaA, while the structurally less related genes hHa6, hHa5, and hHa2 are constituents of the third subcluster. As shown by reverse transcription-polymerase chain reaction, all hair keratin genes, including the pseudogene, are expressed in the human hair follicle. The transcribed pseudogene PsihHaA contains a premature stop codon in exon 4 and exhibits aberrant pre-mRNA splicing. Evolutionary tree construction reveals an early divergence of hair keratin genes from cytokeratin genes, followed by the segregation of the genes into the three subclusters. We suspect that the 190-kbp domain contains the entire complement of human type I hair keratin genes.

Amino Acid Sequence↗
PubMed1998

Generation of lyso-phospholipids from surfactant in acute lung injury is mediated by type-II phospholipase A2 and inhibited by a direct surfactant protein A-phospholipase A2 protein interaction.

Lyso-phospholipids exert a major injurious effect on lung cell membranes during Acute Respiratory Distress Syndrome (ARDS), but the mechanisms leading to their in vivo generation are still unknown. Intratracheal administration of LPS to guinea pigs induced the secretion of type II secretory phospholipase A2 (sPLA2-II) accompanied by a marked increase in fatty acid and lyso-phosphatidylcholine (lyso-PC) levels in the bronchoalveolar lavage fluid (BALF). Administration of LY311727, a specific sPLA2-II inhibitor, reduced by 60% the mass of free fatty acid and lyso-PC content in BALF. Gas chromatography/mass spectrometry analysis revealed that palmitic acid and palmitoyl-2-lyso-PC were the predominant lipid derivatives released in BALF. A similar pattern was observed after the intratracheal administration of recombinant guinea pig (r-GP) sPLA2-II and was accompanied by a 50-60% loss of surfactant phospholipid content, suggesting that surfactant is a major lung target of sPLA2-II. In confirmation, r-GP sPLA2-II was able to hydrolyze surfactant phospholipids in vitro. This hydrolysis was inhibited by surfactant protein A (SP-A) through a direct and selective protein-protein interaction between SP-A and sPLA2-II. Hence, our study reports an in vivo direct causal relationship between sPLA2-II and early surfactant degradation and a new process of regulation for sPLA2-II activity. Anti-sPLA2-II strategy may represent a novel therapeutic approach in lung injury, such as ARDS.

Acute Disease↗
PubMed1998

["Multiple chemical sensitivity syndrome"].

Multiple chemical sensitivity (MCS) has been described as an acquired multiple organ disease typically characterized by central nervous irritative and/or gastrointestinal symptoms. Advocates of this suspected syndrome attribute these disorders to overstressing of the organism caused by exposure to external noxae. Opponents of the theory of MCS attribute all the symptoms to classical conditioning or other psychopathological processes. In so far as controlled data exist, there is no indication of a toxic or immunological cause for this syndrome.

Conditioning, Classical↗
PubMed1998

Photometry and spectroscopy of the GRB 970508 optical counterpart

An optical transient within the error box of the gamma ray burst GRB 970508 was imaged 4 hours after the event. It displayed a strong ultraviolet excess, and reached maximum brightness 2 days later. The optical spectra did not show any emission lines, and no variations on time scales of minutes were observed for 1 hour during the decline phase. According to the fireball and afterglow models, the intensity should rise monotonically before the observed optical maximum, but the data indicate that another physical mechanism may be responsible for the constant phase seen during the first hours after the burst.

Journal Article↗
PubMed1998

[Nephrotic syndrome revealing malignant thymoma].

BACKGROUND: A well-established manifestation of neoplastic disease, nephrotic syndrome is infrequently associated with thymoma. Only 18 cases have been reported in the literature. CASE REPORTS: A 65-year-old man and a 60-year-old woman were seen for nephrotic syndrome. Minimal change renal disease was observed in the first patient whose nephrotic syndrome was steroid resistant. The second patient had membranous glomerulopathy and pure red cell aplasia. In both cases, nephrotic syndrome revealed thymoma. DISCUSSION: The histological lesions in 17 of the 18 biopsied cases reported in the literature were minimal change in 10, focal segmental glomerulonephritis in 4, proliferative glomerulonephritis in 2, and membranous glomerulopathy in only one. The outcome of the nephrotic syndrome was dependent on the success of the thymoma treatment. Some patients responded to steroid and immunosuppressive agents. Pure red cell aplasia is uncommon and prognosis is poor. It can be successfully treated with cyclosporin A as in our second case.

Adult↗
PubMed1998

Vascular remodeling and altered protein expression during growth of coronary collateral arteries.

The cellular mechanism of growth of coronary collateral vessels (adaptive arteriogenesis) is still poorly understood. To define a possible role of an altered expression pattern of cellular and matrix proteins in this process we implanted a constricting device around the left circumflex artery in 25 canine hearts and sacrificed the animals at the time of initiation (3 weeks), high activity (6 weeks) and discontinuation (8 weeks) of vessel growth. Methods were electron microscopy, labeling with Ki-67, the TUNEL method and immunofluorescence with confocal laser microscopy. As described earlier, the collateral vessels increased in wall thickness by the formation of a neointima without luminal narrowing. We report here for the first time that extensive vascular remodeling including migration, proliferation and apoptosis in all cell types takes place during the growth phase but not in more mature vessels. The most obvious difference with normal vessels is the reiteration of an embryonal expression pattern in smooth muscle cells of the neointima which includes a significant reduction of desmin and alpha-smooth muscle actin, calponin and vinculin. Fibronectin as a promoter of migration and adhesion was abundant, its antagonist tenascin and chondroitin sulfate showed patchy localization. A completely new finding in arteriogenesis is the involvement of mast cells releasing histamine and serotonin and probably cytokines. Vascular protein expression returned to almost normal at 8 weeks indicating cessation of remodeling. We conclude that in collateral vessel development an altered cellular and matrix protein expression is involved in a drastic case of positive vascular remodeling finally resulting in mature vessels 20-fold increased in size which are capable of maintaining the functional and structural integrity of the myocardium at risk.

Actins↗
PubMed1998

[Adjuvant whole body acupuncture in depression. A placebo-controlled study with standardized mianserin therapy].

In order to examine the efficacy of whole body acupuncture additionally applied to drug treatment in depression, a single-blind placebo-controlled study with 70 inpatients administered to three different treatment groups has been carried out. All patients were pharmacologically treated with the tetracyclic antidepressant mianserin. The verum group (n = 22) received acupuncture at specific points considered to be effective in the treatment of depression. The placebo group (n = 24) was treated with acupuncture at non-specific locations and the control group (n = 24) received only pharmacological treatment. Acupuncture was applied three times a week over a period of four weeks. Psychopathology was rated by judges blind to verum/placebo conditions twice a week over eight weeks with the CGI, GAS, BRMS and BfS rating scales. Additionally applied acupuncture improved the course of depression more than pharmacological treatment with mianserin did by itself. However, we could not detect any differences between placebo and verum acupuncture.

Acupuncture Therapy↗
PubMed1998

Erythropoietin in amniotic fluid as a marker of chronic fetal hypoxia.

OBJECTIVE: To determinate the erythropoietin concentration in amniotic fluid in normal pregnancies and pregnancies with suspected hypoxia. METHOD: The erythropoietin concentration of 164 samples of amniotic fluid was determined by ELISA. The samples were taken by amniotomy during birth, as well as amniocentesis conducted during prenatal care. RESULTS: A distribution of 1.07-7.29 U/l (10th-90th percentile) within the normal group (n = 106) was determined. Significantly elevated erythropoietin levels in amniotic fluid were determined in maternal hypertension (P = 0.039) and low birth-weight children (P = 0.0032). A correlation with the child's sex could be excluded. CONCLUSION: Elevated erythropoietin levels in amniotic fluid indicated chronic fetal hypoxia.

Adolescent↗
PubMed1998

Oral taurine supplementation modulates ethanol-conditioned stimulus preference.

The present study investigated the possible modulatory action of oral taurine supplementation on the rewarding and aversive properties of low and high ethanol doses in male Wistar rats. A vinegar odor stimulus was daily paired with either ethanol (0.3 or 2.0 g/kg) or saline. In addition, half of the rats were supplemented orally with taurine (0.5 g/kg/day). After eight conditioning sessions, all rats were tested for their vinegar stimulus preference or aversion. In nontaurine-treated rats, 2.0 g/kg ethanol conditioning induced a significant aversion for the vinegar stimulus, while there was no preference after 0.3 g/kg ethanol conditioning. However, in taurine-supplemented rats, the 2.0 g/kg ethanol-induced aversion for the stimulus was decreased significantly, while the rats administered the lower ethanol doses, 0.3 g/kg, in combination with taurine supplementation, demonstrated a significant stimulus preference. Such results suggest that taurine modulates some of the aversive or rewarding effects of ethanol.

Administration, Oral↗
PubMed1998

Combined histamine H1/H2 receptor antagonists: part II. Pharmacological hybrids with pheniramine- and tiotidine-like substructures.

Hybrid molecules combining the crucial structural features of both pheniramine-type histamine H1 receptor antagonists and guanidinothiazole-type H2 receptor antagonists have been synthesized and tested for in vitro pharmacological activity at the isolated ileum and the spontaneously beating right atrium of the guinea-pig. In the title compounds the basic side chain nitrogen of the H1 antagonist and the so-called 'polar group' (cyanoguanidine, urea, or nitroethenediamine) of the H2 antagonist moiety have been linked by a polymethylene spacer. The new substances displayed high affinities to both histamine receptor subtypes and a dual type of antagonism (surmountable/insurmountable) characterized by a shift of the concentration response curves to the right accompanied by a depression of the maximal response to the agonist if the antagonist concentration was >/=100 nM. Highest combined histamine antagonist activities were found in the nitroethenediamine series with pKB values ranging from 8.16 to 9.04 in the ileum (H1) and 7.0-8.08 in the atrium (H2)

Animals↗
PubMed1998

Results of two European interlaboratory studies for the determination of beta-agonists in various matrices.

Two Beta-Agonist Interlaboratory Studies, 5/96 and 11/97, were designed and evaluated according to the International Harmonised Protocol for the Proficiency Testing of (Chemical) Analytical Laboratories (ISO/REMCO N 280) jointly elaborated by ISO, IUPAC and AOAC. In the sense of proficiency testing, interlaboratory studies are part of external quality assurance systems. The Beta-Agonist Interlaboratory Studies 5/96 and 11/97 were intended to offer laboratories in the EU Member States an opportunity to check objectively their routine methods for the detection of beta-agonists and to demonstrate the reliability of their analytical results; 48 and 44 laboratories, respectively, all involved in official residue control, participated in the studies. Irrespective of the large number of satisfactory results achieved at higher concentration levels according to the z-score evaluation, the number of false negative results is still unsatisfactory. The results of both Beta-Agonist Interlaboratory Studies confirmed that comparability of analytical results is not yet ensured within the European residue control system.

Adrenergic beta-Agonists↗
PubMed1997

Modulation of human type II secretory phospholipase A2 by sphingomyelin and annexin VI.

Conjectural results have been reported on the capacity of inflammatory secreted phospholipase A2 (sPLA2) to hydrolyse mammalian membrane phospholipids. Development of an assay based on the release of non-esterified fatty acids by the enzyme acting on the organized phospholipid mixture constituting the membrane matrix has led to the identification of two prominent effectors, sphingomyelin (SPH) and annexin. Recombinant human type II sPLA2 hydrolyses red-cell membrane phospholipids with a marked preference for the inner leaflet. This preference is apparently related to the high content of SPH in the outer leaflet, which inhibits sPLA2. This inhibition by SPH is specific for sPLA2. Cholesterol counteracts the inhibition of sPLA2 by SPH, suggesting that the SPH-to-cholesterol ratio accounts in vivo for the variable susceptibility of cell membranes to sPLA2. Different effects were observed of the presence of the non-hydrolysable D-alpha-dipalmitoyl phosphatidylcholine (D-DPPC), which renders the membranes rigid but does not inhibit sPLA2. Annexin VI was shown, along with other annexins, to inhibit sPLA2 activity by sequestering the phospholipid substrate. The present study has provided the first evidence that annexin VI, in concentrations that inhibit hydrolysis of purified phospholipid substrates, stimulated the hydrolysis of membrane phospholipids by sPLA2. The activation requires the presence of membrane proteins. The effect is specific for type II sPLA2 and is not reproducible with type I PLA2. The activation by annexin VI of sPLA2 acting on red cell membranes results in the preferential release of polyunsaturated fatty acids. It suggests that type II sPLA2, in conjunction with annexin VI, might be involved in the final step of endocytosis and/or exocytosis providing the free polyunsaturated fatty acids acting synergistically to cause membrane fusion.

Annexin A6↗