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R Schubert

Publications and source records attributed to R Schubert.

At least 91 records · Page 5Linked to original sources
PubMed1997

An ozone-responsive region of the grapevine resveratrol synthase promoter differs from the basal pathogen-responsive sequence.

Stilbene synthase (STS) is an enzyme involved in the biosynthesis of stilbenes, which are synthesized in various plants in response to pathogen attack, UV irradiation or exposure to ozone. We describe analysis of an ozone inducible STS transcript and its corresponding promoter (Vst1), combined with the beta-glucuronidase (GUS) reporter gene. A single ozone pulse (0.1 microliter/l, 10 h) resulted in 11-fold GUS expression. Histochemical localization of GUS activity revealed small spots distributed over the whole leaf. Cross-sections of leaf tissue showed that the Vst1 promoter was induced in palisade and spongy parenchyma cells and to a lesser extent in epidermal cells. Deletions at the 5' end showed that a partial promoter sequence between position -430 and -280 constituted the ozone-responsive region, whereas for effective pathogen-inducibility sequences from -280 to -140 have been shown to be necessary.

Acyltransferases↗
PubMed1997

Partial trisomy 6p from a de novo translocation (6;18) with variable mosaicism in different tissues.

Partial trisomy 6p is regarded as a distinct phenotype with short stature, failure to thrive, facial dysmorphisms with blepharophimosis, mental retardation and other malformations. An 18-month-old girl with typical features of partial trisomy 6p showed a de novo unbalanced translocation resulting in partial trisomy 6p21 to pter and partial monosomy 18p11 to pter. The translocation was observed in all fibroblasts analyzed, but only in 6% of the peripheral lymphocytes.

Abnormalities, Multiple↗
PubMed1997

Iloprost dilates rat small arteries: role of K(ATP)- and K(Ca)-channel activation by cAMP-dependent protein kinase.

The effect of the stable prostacyclin analog iloprost and its mechanism of action were investigated with the use of pressurized rat tail small arteries with a spontaneous myogenic tone. Iloprost concentration dependently dilated these vessels with a half-maximal effective dose of 5.0 +/- 0.5 x 10(-8) M. Application of 10(-7)-10(-6) M glibenclamide, a blocker of ATP-sensitive potassium (K(ATP)) channels, inhibited the iloprost-induced dilation. Glibenclamide did not affect the basal vessel diameter. The application of 5 x 10(-5)-10(-3) M tetraethylammonium (TEA) and 5 x 10(-9)-10(-7) M iberiotoxin, blockers of calcium-activated potassium (K(Ca)) channels, decreased vessel diameter in the presence of iloprost. Both TEA and iberiotoxin reduced the basal vessel diameter. Glibenclamide at 10(-6) M inhibited the dilation produced by 5 x 10(-5) M Sp-5,6-DCl-cBIMPS, an activator of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase. Iberiotoxin at 10(-7) M decreased vessel diameter in the presence of Sp-5,6-DCl-cBIMPS. H-89 and Rp-8-CPT-cAMPS, blockers of cAMP-dependent protein kinase A (PKA), inhibited the iloprost-induced dilation of these vessels. With use of the whole cell configuration of the patch-clamp technique, it was observed that 5 x 10(-7) M iloprost enhanced an outward current, determined largely by K(Ca) channels, 1.79 +/- 0.17-fold in freshly isolated smooth muscle cells from rat tail small artery. These data show that iloprost dilates rat tail small arteries with a spontaneous myogenic tone and suggest that K(ATP) as well as K(Ca) channels are involved in this effect, which is mediated, at least partly, by PKA.

Adenosine Triphosphate↗
PubMed1997

KCa-channel blockade prevents sustained pressure-induced depolarization in rat mesenteric small arteries.

In small blood vessels, elevation of transmural pressure induces myogenic constrictions and smooth muscle depolarization. The role of calcium-activated K+ channels (KCa channels) in these responses was examined in cannulated rat mesenteric small arteries. Inner and outer diameter were continuously monitored with a video technique. Smooth muscle membrane potential was recorded simultaneously using microelectrodes. To test for myogenic responsiveness, the transmural pressure was changed stepwise in the range between 10 and 120 mmHg. Pressure elevation induced moderate myogenic responses and significant depolarization, from -54.5 +/- 0.4 (SE) mV (n = 56) at 10 mmHg to -47.3 +/- 1.8 mV (n = 12) at 120 mmHg. Norepinephrine (NE, 0.67 and 10 microM) induced constriction and vasomotion, augmented myogenic responsiveness, and shifted the pressure-membrane potential relation to more depolarized values. Blockade of the Kca channels with charybdotoxin (ChTX) suppressed the responsiveness to pressure. In the absence of ChTX, with 0.67 microM NE, pressure elevation from 10 to 120 mmHg induced depolarization from -46.9 +/- 1.0 (n = 16) to -35.8 +/- 0.7 (n = 12) mV, whereas because of the myogenic response, the diameter increased only by 7%. In the presence of ChTX, with 0.3 microM NE, pressure changed the membrane potential from -41.0 +/- 1.1 (n = 12) to -37.8 +/- 0.7 mV (n = 4), which was not significant, and the diameter increased by 28%. These results demonstrate that blockade of KCa channels reduces responsiveness to pressure elevation. This suggests that pressure may induce depolarization and concomitant myogenic responsiveness by closure of KCa channels.

Animals↗
PubMed1997

Applications and perspectives in anatomical 3-dimensional modelling of the visible human with VOXEL-MAN.

Up to now computerized interactive 3-dimensional (3D) atlases of human anatomy have been based on radiological data or artificial geometric models as spatial descriptions of morphological structures. Besides the obvious advantages of this data (e.g. already in digital format, geometrical correctness) the lack of high resolution anatomical slices of larger regions of the human body has prevented the use of more realistic anatomical data so far. Now, the Visible Human Project offers high quality anatomical slices of complete cadavers. Therefore, on the one hand, new opportunities for realistic virtual 3D models of anatomy are open. On the other hand, just the major advantages of the visible human data (e.g. realistic colors and textures, high resolution) result in new demands on the image processing and visualization techniques. This paper describes experience, solutions and results with a volume-based approach for building realistic anatomical 3D models.

Anatomy, Cross-Sectional↗
PubMed1997

Fulminating subacute sclerosing panencephalitis: case report and literature review.

We describe a young urban boy with atypically fulminant subacute sclerosing panencephalitis (SSPE). He had measles at 3 years of age despite receiving measles immunization in infancy. The literature describing acute SSPE is reviewed and summarized. This report reiterates the need to include SSPE as a diagnostic possibility in acute encephalopathic processes. The dismal prognosis of SSPE further emphasizes the need for measles vaccination and revaccination of all children who are initially immunized at an age of less than 15 months.

Acute Disease↗
PubMed1996

Cicutoxin from Cicuta virosa--a new and potent potassium channel blocker in T lymphocytes.

The effect of cicutoxin, the poisonous principle of the genus Cicuta, on K+ currents of activated T lymphocytes was investigated using the patch clamp technique. Cicutoxin produced a dose-dependent [5 x 10(-6) to 7 x 10(-5) mol/l] and completely reversible block of K+ currents with an EC50 of 1.8 x 10(-5) mol/l. A maximum block of 71% was achieved with cicutoxin at a concentration of 7 x 10(-5) mol/l. Since previous studies have shown that T lymphocyte proliferation is associated with K+ currents, the effect of cicutoxin on T lymphocyte proliferation was studied by means of 3H-thymidine uptake assays. At noncytotoxic concentrations [10(-7) to 5 x 10(-5) mol/l] cicutoxin reduced the 3H-thymidine incorporation dose-dependently. In conclusion, cicutoxin is a potent K+ current blocker which inhibits K+ channel-dependent proliferation of naive and memory T lymphocytes.

Alkynes↗
PubMed1996

Molecular-cytogenetic investigations of ten term placentae in cases of prenatally diagnosed mosaicism.

Discrepant chromosome findings in the placenta and fetus are detected by additional investigations commonly after chorionic villus sampling (CVS) and occasionally after amniotic fluid cell cultures. In this paper we present the results of molecular-cytogenetic investigations (fluorescence in situ hybridization, FISH) of ten term placentae after prenatally detected mosaicism. In three cases, mosaicism was found after first-trimester CVS and in seven cases, after second-trimester amniotic fluid culture. All three results after CVS represented confined placental mosaicism (CPM). Two of the seven mosaic findings after amniocentesis were not confirmed postnatally. In the remaining five cases, general mosaicism was found. The analyses of six defined areas of the term placentae showed that it is important to investigate the placenta at multiple sites. The frequency of a cell line varied by more than 50 per cent at different analysed sites. FISH on interphase nuclei proved to be a rapid and reliable method of investigating large numbers of biopsies and cells per biopsy.

Amniocentesis↗
PubMed1996

Noradrenaline-induced depolarization is smaller in isobaric compared to isometric preparations of rat mesenteric small arteries.

The hypothesis was tested that wall tension can influence the membrane potential response to noradrenaline (NA) using isometric and isobaric vessel preparations of rat mesenteric small arteries. The resting membrane potential was significantly less negative in the isobaric (-49.7+/-0.5 mV, S.E.M., n=12 vessels) compared to the isometric preparation (-56.1+/-0.7 mV, n=10), although there was no difference in wall tension. The depolarization induced by 10(-5) M NA was 2.6-fold smaller in the isobaric preparation, where wall tension decreased, compared to the isometric preparation, where wall tension increased. Since wall tension decreases under isobaric conditions, but increases under isometric conditions, the latter finding can be explained by assuming that part of the NA-induced membrane potential change is wall tension dependent.

Animals↗
PubMed1996

Analysis of pressurized resistance vessel diameter changes with a low cost digital image processing device.

A low cost digital image processing device (frame grabber) together with a program running under MS_WINDOWS for automatic on-line analysis of diameter changes of in vitro pressurized blood vessels with an inner diameter of 80-400 microns is presented. The frame grabber is designed to receive light microscopic images either from a video camera or from a VCR and to present the digitized image on the computer monitor. The special software allows to manipulate the image, e.g. filtering, calibrating, storing of vessel images, and detects the outer and inner border of the two vessel walls with a new, simple algorithm. The inner diameter and the vessel wall thickness are calculated and the diameter is presented in a diameter versus time diagram on the monitor screen. Further, these data are stored in an ASCII-file for later import into calculation and presentation programs like MS-EXCEL.

Algorithms↗
PubMed1996

Iloprost activates KCa channels of vascular smooth muscle cells: role of cAMP-dependent protein kinase.

The patch-clamp technique was used to investigate the effect of iloprost on activity of calcium-activated potassium (KCa) channels of freshly isolated rat tail artery smooth muscle cells. In the whole cell configuration, outward current, determined largely by KCa channels, was enhanced 1.73 +/- 0.11-fold by 5 x 10(-7) M iloprost, 1.80 +/- 0.12-fold by 10(-4) M 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole-3', 5'-cyclic monophosphothioate (Sp-5,6-DCl-cBIMPS), a specific activator of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA), and 2.78 +/- 0.95-fold by 10 U/ml of the catalytic subunit of PKA + 10(-4) M MgATP, whereas the heat-inactivated catalytic subunit of PKA + MgATP was without effect. Iloprost at 5 x 10(-7) M increased this current 1.70 +/- 0.27-fold after pretreatment of cells with 10(-6) M okadaic acid, a specific phosphatase inhibitor, but did not alter this current after pretreatment of cells with 2 x 10(-4) M Rp-8-(4-chlorophenylthio)-adenosine-3',5'-cyclic monophosphorothioate, a specific PKA inhibitor. In the cell-attached configuration, activity of KCa channels was enhanced 2.48 +/- 0.44-fold by 5 x 10(-7) M iloprost and 2.09 +/- 0.07-fold by 10(-4) M Sp-5,6-DCl-cBIMPS. Iloprost at 5 x 10(-7) M did not alter intracellular calcium concentration in these cells measured using indo 1. In the inside-out configuration, activity of KCa channels was increased 87.12 +/- 45.04-fold by 10 U/ml of the catalytic subunit of PKA together with 10(-4) M MgATP, whereas no effect was observed after application of the catalytic subunit of PKA together with its regulatory subunit and MgATP, MgATP, cAMP, or the catalytic subunit of PKA alone also did not change KCa channel activity. Thus these results show that iloprost is able to activate KCa channels of freshly isolated rat tail artery smooth muscle cells and suggest that this effect is mediated by a PKA-induced phosphorylation of the channel.

Animals↗
PubMed1996

External hydrocephalus in adults. Report of three cases.

The authors report three adult patients who developed a symptomatic extraaxial collection of cerebrospinal fluid (CSF) after an intracranial hemorrhage. The fluid shifted from the extraaxial into the ventricular space as the patients' symptoms progressed. The symptoms resolved after placement of a ventriculoperitoneal shunt. External hydrocephalus, which is frequently observed in children, had not yet been described in adults. It is important to differentiate chronic subdural collections from external hydrocephalus, because ventricular CSF shunting increases the former while it is the treatment for the latter. The authors believe that symptomatic extraaxial fluid collections developed in these three adults during the early phase of posthemorrhagic hydrocephalus because the ventricles presented great resistance to distention at the onset of hydrocephalus. Animal experiments have led to the same result.

Adult↗
PubMed1996

[Department social climate on mixed sex and segregated acute psychiatric units. Results of a survey].

The segregation of sexes in an acute psychiatric unit was followed up by means of a research survey. Patients and staff members were questioned about the ward climate before and after changing the admission procedure. The male patients merely noticed a decreased influence of sexual problems on the ward atmosphere. The female patients evaluated the new ward for women as an improvement. In particular, assistance and clarity of conditions were more positively assessed. The staff members of the previous open ward noticed a significant increase in annoyance and aggression after closing the ward and segregation of the sexes. In general, segregation of the sexes did not result in deterioration of the ward atmosphere.

Adaptation, Psychological↗
PubMed1995

Concentration-dependent binding of the chiral beta-blocker oxprenolol to isoelectric or negatively charged unilamellar vesicles.

Large unilamellar vesicles (LUVs) of different lipid compositions were used to study the type of binding of the beta-blocking cationic agent oxprenolol to the lipid matrix of biological membranes at a physiologic pH value of 7.4. When isoelectric membranes of pure egg lecithin or egg lecithin/cholesterol (7:3 mol/mol) were used, a linear relationship between membrane-bound and free oxprenolol indicated a constant molar partition coefficient of 54 or 44 between the liposomal and the aqueous phase over a wide concentration range of the drug up to 25 mM. This pointed to deep insertion of the drug molecules into the hydrophobic membrane interior. Drug binding to membranes of negatively charged phosphatidylserine from bovine brain was cooperative with a Hill coefficient h of 3.4 at concentrations below 0.5 mM and a molar ratio Re of bound drug per lipid of 1:10. Above drug concentrations of 2.5 mM and Re = 1:5, a constant molar partition coefficient of 33 could be estimated. R-oxprenolol or S-oxprenolol, as well as the racemic drug, showed no differences in membrane binding, even with egg lecithin LUVs containing 20 mol% of the negatively charged (2S, 4R)-N-(hexadecanoyl)-4-hydroxyproline, which has a pronounced chiral headgroup. Our results suggest that enantioselective interactions of the chiral oxprenolol with the chiral lipids of biological membranes can be excluded. Furthermore, surface adsorption of the drug is probable only on the negatively charged cytosolic side of biological plasma membranes, whereas on the isoelectric exterior the cationic drug is inserted deeply into the membrane.

Animals↗
PubMed1995

The lack of immunogenicity of iotrolan.

RATIONALE AND OBJECTIVES: To test whether it would be possible to raise antibodies against iotrolan in rabbits and, if possible, to develop a radioimmunoassay for iotrolan. METHODS: A "half-molecular" analogue of iotrolan was synthesized, which contained a carboxylic group. This moiety was coupled via a link to bovine serum albumin. The resultant hapten was suspended in Freund's complete adjuvant and used to immunize rabbits by two subcutaneous and two intramuscular injections followed by monthly booster injections. After bleeding of the animals, the antibodies formed were tested. RESULTS: The rabbits successfully developed antibodies against the hapten. These antibodies were tested for cross-reactivity with iotrolan, the iotrolan half-molecule, and the hapten. Minimal cross-reactivity (below 0.5%) was found for iotrolan and the half-molecule. Only the hapten was found to bind to the antibody. CONCLUSIONS: In the current test setting using a half-molecular analogue, it could be shown that iotrolan is probably not immunogenic. The formation of an antibody against the half-molecule coupled to bovine serum albumin can be explained only by immunogenicity of that part of the molecule, which constitutes the bridge or link to the albumin. This part of the hapten, however, is not representative of iotrolan itself.

Animals↗
PubMed1995

[New kinds of 3-dimensional atlases of the anatomy and function of the human body].

It is a drawback of classical multimedia programs for the visualization of spatial knowledge, that they are based on a limited number of predefined views. This paper describes a model that combines pictorial and symbolic knowledge about spatial structures in a way that allows arbitrary views of the scene and the interrogation of the model in the context of the actual view. The style of the pictorial presentation only depends on the objective and the phantasy of the user. The functionality of the approach is demonstrated with the example of the human head. It is furthermore shown that the model potentially allows the simulation or generation of all classical visual teaching aids for anatomy.

Anatomy, Artistic↗
PubMed1994

Tissue-specific expression of an oat 12S seed globulin gene in developing tobacco seeds: differential mRNA and protein accumulation.

We studied the expression of the oat globulin gene asglo5 in developing transgenic tobacco seeds. The asglo5 gene promoter directed transcription in the endosperm as well as in the provascular tissue, the presumptive root tip and the shoot apical meristem of the embryo as revealed by GUS reporter gene constructs and in situ hybridization. However, immunological tissue printing detected the oat protein exclusively in the tobacco endosperm, suggesting that extensive post-transcriptional regulatory processes influence the expression of the monocot transgene in the dicot host.

Allergens↗