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W Schäfer

Publications and source records attributed to W Schäfer.

At least 19 recordsLinked to original sources
PubMed2006

A comprehensive view on organ-specific callose synthesis in wheat (Triticum aestivum L.): glucan synthase-like gene expression, callose synthase activity, callose quantification and deposition.

Callose ((1,3)-beta-glucan) is important during basic developmental processes of plants, but only little is known about the regulation of callose biosynthesis on molecular level. Growing evidence indicates that glucan synthase-like (GSL) genes in higher plants are involved in callose synthesis. We analyzed the expression of eight GSL genes (TaGSL) as well as callose synthase activity and total callose content in the stem, leaf blade and spike of wheat (Triticum aestivum L.). Organ-specific expression of six TaGSL genes and strong differences in expression levels were detected by quantitative real-time PCR. Differences were also determined in callose synthase (EC 2.4.1.34) activity and total amount of callose in the examined organs. Aniline blue staining in tissue sections localized callose depositions. These results allow a comprehensive reflection of callose regulation, considering gene expression, enzyme activity and enzyme product quantification as well as localization. Our data suggests that callose synthesis is highly regulated by a combination of GSL genes, which are involved either in general or in organ-specific developmental processes.

Gene Expression Regulation, Enzymologic↗
PubMed2005

Nonuniversality aspects of nonlinear k(perpendicular) factorization for hard dijets.

The origin of breaking of conventional linear k(perpendicular) factorization for hard processes in a nuclear environment is by now well established. The realization of the nonlinear nuclear k(perpendicular) factorization which emerges instead was found to change from one jet observable to another. Here we demonstrate how the pattern of nonlinear k(perpendicular) factorization, and especially the role of diffractive interactions, in the production of dijets off nuclei depends on the color properties of the underlying pQCD subprocess.

Journal Article↗
PubMed2005

Comparison of standard phenotypic assays with a PCR method to discriminate Candida albicans and C. dubliniensis.

In 1995, Candida dubliniensis was described as a new species in the genus Candida. Its close relationship to C. albicans has proved problematic in the identification of C. dubliniensis in clinical specimens. The objective of this study was to determine if reproducible differentiation between both species can be obtained by phenotypic assays. Therefore, 100 strains from 86 patients with the ability to produce chlamydospores were examined with different methods including API ID 32 C, colour development on CHROMagar, chlamydospore formation on Staib agar, growth at different temperatures and germ tube formation at 39 degrees C. Additionally, polymerase chain reaction (PCR) was used as gold standard. Six of the investigated strains were C. dubliniensis. The results suggest that there is still no single phenotypic method satisfactory to distinguish between C. albicans and C. dubliniensis.

Agar↗
PubMed2004

[Phantom sensations and peripheral induced neglect following implantation of total hip prosthesis].

OBJECTIVES: O. Sacks describes in his book "A leg to stand on" the inability to move his leg for along period after rupture of the tendon of m. quadriceps. He refers the history of similar cases, especially of a woman with a hip fracture. He discusses this as a result of disruption of proprioception (peripheral induced neglect). The aim of this investigation is to answer the question how frequently this symptom may be found in patients with hip fracture and/or arthrosis perioperativly after implantation of a total prosthesis. METHODS: we examined 106 patients aged 70.35 +/- 10.01 years (36-male 67.54 +/- 9.74 years and 69 female 71.9 +/- 9.9 years) who underwent an implantation of a hip prosthesis - antero-lateral access Watson-Jones - (right side n = 61, left n = 44) because of arthrosis (n = 81) or a hip fracture (n = 18) on postoperative day 1./2. and 10. - 14. Besides exact neurologic examination, we particularly asked for changed perception of the operated leg. RESULTS: by neurological examination we found only rarely signs of peripheral nerve lesion as a complication of implantation of hip prosthesis (1 femoral nerve lesion, 1 ischiadicus nerve lesion). 14 patients reported a changed perception at the first examination: 5 patients felt their operated leg shorter or longer, 4 patients described their leg changed in a strange manner (like a block of wood or lead), 2 patients felt their leg changed, but could not tell how. At follow-up examination there was no patient with a changed perception of the operated leg. CONCLUSIONS: at first examination only a small number of patients report a changed perception of the operated leg. Early mobilization of the operated leg may be the cause of quick normalization of perception. The peripherally induced neglect, described by O. Sacks, was possibly caused by decrease of cortical representation because of immobilization, but not by disrupted proprioception.

Aged↗
PubMed2001

From coherently excited highly correlated states to incoherent relaxation processes in semiconductors.

Recent theories of highly excited semiconductors are based on two formalisms, referring to complementary experimental conditions, the real-time nonequilibrium Green's function techniques and the coherently controlled truncation of the many-particle problem. We present a novel many-particle theory containing both of these methods as limiting cases. As a first example of its application, we investigate four-particle correlations in a strong magnetic field including dephasing resulting from the growth of incoherent one-particle distribution functions. Our results are the first rigorous solution concerning formation and decay of four-particle correlations in semiconductors. They are in excellent agreement with experimental data.

Journal Article↗
PubMed2001

Cloning and expression analysis of NhL1, a gene encoding an extracellular lipase from the fungal pea pathogen Nectria haematococca MP VI (Fusarium solani f. sp. pisi) that is expressed in planta.

The filamentous fungus Nectria haematococca (anamorph Fusarium solani f. sp. pisi) resides in soil, and attacks pea seedlings in the area of the underground epicotyl and upper tap root, causing foot rot disease. We detected lipase activity during in vitro growth of N. haematococca. Subsequently, a lipase gene was cloned and functionally characterised by heterologous expression in Saccharomyces cerevisiae. The full-length cDNA of 1152 bp was cloned using a 3' RACE-PCR approach coupled with cDNA library screening. The genomic clone, comprising an ORF of 999 bp interrupted by two introns of 56 and 64 bp, was isolated from a newly constructed lambda phage library. Analysis of the deduced protein sequence revealed the presence of a typical signal peptide at the N-terminus, and of the three conserved amino acids forming the active site of lipases. The lipase of N. haematococca has a low degree of similarity to the lipases from Humicola lanuginosa (37.2%), Rhizomucor miehei (21.6%), Rhizopus delemar (23.1%), Rhizopus niveus (25.9%), and to mono- and diacylglycerol lipase from Penicillium camembertii (30.8%), and very high similarity (94.6%) to a lipase from Fusarium heterosporum. The lipase from N. haematococca shows maximal activity at 37 degrees C and pH 8.0. Based on Southern analysis, the lipase clone represents a single-copy gene in N. haematococca. Expression analysis was performed by RT-PCR. In vitro, the lipase gene shows a low basal expression, but is highly inducible by lipase substrates, and repressed by glucose. During plant infection, transcripts of this fungal lipase gene were detected 4, 8, and 10 days after infection.

Amino Acid Sequence↗
PubMed2001

Predicting natural attenuation of xylene in groundwater using a numerical model.

The aquifer beneath an abandoned refinery in the Lower Rhine area, Germany, was contaminated with a number of different mineral oil products. Groundwater sampling in the area around the former xylene plant revealed that a xylene plume had developed in the underlying groundwater, and moreover, that there is strong evidence for in situ microbial xylene degradation with oxygen, nitrate, sulfate and ferric iron as electron acceptors. In order to prevent further xylene spreading, three pumping wells extracting contaminated water were installed downgradient of the spill zone. The numerical reactive transport code Transport Biochemisty Chemistry (TBC) was applied to this situation to quantify the relation of microbial degradation to xylene removal by the pumping wells. It could be shown that the unamended in situ degradation was an appreciable xylene removal process that contributed to about one-third to the total xylene removal (degradation plus extraction). A further objective of the model application was to predict xylene spreading under regional flow conditions, i.e. without operation of the three pumping wells, to consider the possible effects of natural xylene attenuation. To accomplish this, the model calibrated for the situation with operating wells was transferred to the hydraulic situation of regional flow while retaining the parameters of the biochemical model. It turned out that the xylene plume that is expected to develop downgradient of the source area will be limited to an extension of not more than 1000 m. An interesting feature of the simulations results was that xylene degradation under iron-reducing conditions, which was of minor importance for the situation with operating pumping wells, becomes the dominant degradation mechanism under regional flow conditions. Moreover, iron reduction will be the key process in controlling plume evolution. The model application illustrates that multi-species reactive transport models are needed to adequately transfer reactive processes from one hydraulic situation to another, while single species models are not suited for this predictive task.

Forecasting↗
PubMed2001

The KEX2 gene of Candida glabrata is required for cell surface integrity.

Candida glabrata has emerged as one of the most common causes of candidosis. In order to identify factors that are necessary for viability and pathogenicity of this fungal pathogen, we analysed the role of the KEX2 gene, which codes for a regulatory endoproteinase that is known to process certain virulence factors in Candida albicans. The KEX2 gene from C. glabrata was cloned and found to have 51% and 62% identity and high structural similarities to the homologous counterparts in C. albicans and Saccharomyces cerevisiae. KEX2 was expressed at all time points investigated during growth in complex medium. In order to investigate the role of this putative regulatory proteinase, Kex2-deficient mutants were produced. In addition to known kex2 phenotypes, such as pH and calcium hypersensitivity, the mutants grew in cellular aggregates and were found to be hypersensitive to several antifungal drugs that target the cell membrane, including azoles, amorolfine and amphotericin B. Ultrastructural investigation after exposure to low doses of itraconazole showed azole-specific alterations such as enlarged vacuoles and proliferation of the cytoplasmatic membrane in the kex2 mutants, but not in the control strains. In contrast, antifungals such as 5-flucytosine and hydroxypyridones inhibited growth of the kex2 mutants and the control strains to the same extent. In an in vitro model of oral candidosis, kex2 mutants showed reduced tissue damage in the presence of itraconazole compared with the control infections. These data suggest that Kex2 is involved in the processing of proteins that are essential for cell surface integrity of C. glabrata.

Amino Acid Sequence↗
PubMed2001

Can urodynamic assessment of outflow obstruction predict outcome from watchful waiting?--A four-year follow-up study.

OBJECTIVE: One of the most common "treatment" alternatives in suspected outflow obstruction due to bladder outlet obstruction (BOO) is watchful waiting (WW). The aim of this study was to see whether there were any differences in outcome between patients with slight, moderate or severe obstruction due to BOO as classified by transrectal ultrasound (TRUS) and urodynamics. MATERIAL AND METHODS: Thirty-seven men with lower urinary tract symptoms (LUTS) and suspected BOO were included. All of the patients were investigated by a routine investigation schedule, including TRUS and urodynamics with pressure-flow measurement (pQS) at baseline. Patients with cancer in the urinary tract, prostatitis, history of detrusor hyperreflexia (peripheral or central diseases or trauma to the nervous system affecting the bladder) and serious systemic diseases were excluded. Patients were examined at baseline, then checked again after 1 year and 4 years. Patients who did not want to continue with WW were listed as treatment failures. RESULTS: At baseline, 43.2% of the patients were urodynamically severely obstructed and 32.3% were moderately obstructed. Thirty-five per cent of the patients were found to have previously unknown detrusor hyperactivity/overactivity. The prevalence of detrusor hyperactivity/overactivity increased with BOO. After 1 year, IPSS had decreased at unchanged Qmax and postresidual volume. These findings persisted at 4 years. The failure rate increased in the more obstructed patients and was significantly higher with more severe obstruction. Complications were found in 13.5%, with no significant differences between patients with minor BOO [Detrusor Adjusted Mean PURR Factor (DAMPF) scale <42], moderate BOO (DAMPF 42-65) and severe BOO (DAMPF >65). CONCLUSIONS: In patients with severe BOO, the LUTS and failure rate increase over time. The percentage of patients with detrusor hyperactivity/overactivity was higher in the severely obstructed group. By including full urodynamics when investigating patients with BOO, it seems possible to predict the failure rate according to the patients' obstruction grade. This gives an opportunity to treat the patient with minimal invasion, and to give the individual patient a more precise prognosis if WW is preferred.

Adult↗
PubMed2001

PTK1, a mitogen-activated-protein kinase gene, is required for conidiation, appressorium formation, and pathogenicity of Pyrenophora teres on barley.

Mitogen-activated protein kinases (MAPKs) are a group of protein kinases that execute a wide variety of roles in cellular signal transduction pathways such as osmoregulation, cell wall biosynthesis, growth, and differentiation. A polymerase chain reaction (PCR) with degenerate primers based on conserved regions of known MAPKs was used to clone the MAPK gene PTK1 from the leaf pathogen Pyrenophora teres (anamorph Drechslera teres), the causal agent of net blotch of barley (Hordeum vulgare L.). The predicted amino acid sequence shows high homology with MAPKs from other phytopathogenic fungi. The gene is present in the genome as a single copy. PTK1 is expressed during in vitro growth on complete medium, under conidiation-inducing conditions and during infection of barley leaves, as shown by reverse transcription-PCR studies. In order to assess the role of PTK1 in the life cycle of P. teres, targeted gene disruption was conducted. Mutants carrying an interrupted copy of the gene were deficient in conidiation, did not form appressoria on glass surfaces or on barley leaves, lost their ability to infect barley leaves, and could not colonize host tissues following artificial wounding.

Amino Acid Sequence↗
PubMed2001

Evaluation for Madigan's prostatectomy in patients with benign prostatic hyperplasia.

AIM: To comparatively evaluate the efficacy and post-operative complications of the Madigan's prostatectomy (MPC) and suprapubic prostatectomy (SPPC). METHODS: A total of 43 patients with benign prostatic hyperplasia were divided into two groups: 21 underwent MPC and 22, SPPC. In all the patients, the international prostate symptom score (IPSS) and urinary pressure-flow studies were assessed before and 6 months after operation. The International Continence Society (ICS) nomogram, Abrams-Griffiths (AG) number and linear passive urethral resistance relation analysis (L-PURR) were used to diagnose and grade bladder outlet obstruction (BOO). The IPSS and the urodynamic parameters before and after operation, as well as the advantages and post-operative complications were recorded and compared. RESULTS: Patients of both the MPC and SPPC groups had a significant improvement in IPSS and urodynamic parameters. Obstruction was relieved in 81.0% of MPC and 86.4% of SPPC patients. MPC has the advantages of the absence of postoperative hematuria and post-catheter stricture, a shorter period of hospitalization, and lower incidence of retrograde ejaculation and erectile dysfunction. CONCLUSION: Both MPC and SPPC can effectively relieve BOO. MPC has certain advantages and a lower incidence of complications as compared with SPPC.

Aged↗
PubMed2001

Optimizing ventilation-perfusion lung scintigraphy: parting with planar imaging.

AIM: Of the study was to introduce and verify a ventilation-perfusion (V/Q) acquisition protocol that incorporates new developments in scintigraphy in order to allow for a more balanced comparison with other diagnostic procedures. METHODS: In 103 patients suspect of having pulmonary embolism, V/Q scans were acquired exclusively with SPECT technique. Ventilation was done with ultrafine aerosol. Planar images in eight directions were reconstructed through addition of three consecutive SPECT projections. Three referees examined the scans in regard to type, localization, and extent of V/Q defects. RESULTS: Using this protocol, significantly more defects, especially of subsegmental size, were detected (p < 0.01). Sensitivity, and diagnostic accuracy were also significantly improved (p < 0.01) to 0.96, and 0.99, respectively. Furthermore, kappa values were increased up to 0.82--a relevant enhancement in the ability to precisely localize V/Q defects. CONCLUSION: In conclusion this protocol provides high-resolution tomographic scans as well as high-quality planar images within a short acquisition time. Due to the significant increase in lesion detection, sensitivity, diagnostic accuracy, and anatomical localization of defects, it is a substantial improvement in the diagnosis of pulmonary embolism that will put V/Q scintigraphy on a par with other tomographic methods.

Adolescent↗
PubMed2001

[Characterization of therapy failures in radioiodine therapy of Graves' disease without simultaneous antithyroid agents].

UNLABELLED: Aim of this study was a characterization of radioiodine therapy (RIT) failures in Graves' disease without simultaneous carbimazole. METHOD: 226 patients with a confirmed diagnosis of Graves' disease received 686.8 +/- 376.4 MBq of iodine-131 orally for thyroid ablation. Target dose was 250 Gy. All patients were followed up for 6 months. Therapy failures were compared with successes regarding possible influencing variables initial thyroid volume, thyroid function, immune activity (TRAb), I-131 uptake, effective half-life, absorbed energy dose, age and gender. RESULTS: 212 of 226 patients (93.8%) were treated successfully, 14 (6.2%) showed a hyperthyroidism relapse within 6 months which required a second radioiodine therapy. A success rate of 92.5% (62/67) could also be achieved with 67 patients who were hyperthyroid at the time of RIT. Compared to the therapy successes, the 14 failures achieved significantly lower absorbed doses (223.8 +/- 76.6 Gy vs. 285.2 +/- 82.1 Gy, p < 0.005), but with no significant differences regarding age, thyroid volume, function or TRAb (all p > 0.2). Of the 14 failures, n = 8 reached an absorbed dose < 200 Gy and n = 1 a dose < 250 Gy, although 5 of the failures reached an absorbed dose of > 250 Gy. Stepwise logistic regression revealed only absorbed energy dose as a variable significantly influencing therapy success (p < 0.005), but no influence of initial thyroid volume, function, TRAb value, age (all p > 0.2) or gender (p = 0.13). Two-tailed Fisher's exact test showed no significant influence of gender on success rates (failures/successes: male 1/36, female 13/176, p = 0.48). CONCLUSIONS: Except for the absorbed energy dose, no other significant variable influencing the outcome of radioiodine therapy in Graves' disease without simultaneous carbimazole could be found. It should be noted, though, that 5 therapy failures (2.2%) reached an absorbed energy dose of > 250 Gy.

Adult↗
PubMed2000

The N-terminal fragment of human parathyroid hormone receptor 1 constitutes a hormone binding domain and reveals a distinct disulfide pattern.

The N-terminal extracellular parts of human G-protein coupled receptor class B, for example, receptors for secretin, glucagon, or parathyroid hormone, are involved in ligand binding. To obtain structural and functional information on the N-terminal receptor fragment of human parathyroid hormone receptor 1 (PTHR1), the truncated receptor was expressed in the cytosol of Escherichia coli in the form of inclusion bodies. Oxidative refolding of inclusion body material resulted in stable, soluble, monomeric protein. Ligand binding was proved by surface plasmon resonance spectroscopy and isothermal titration calorimetry. Refolded receptor fragment was able to bind parathyroid hormone with an apparent dissociation constant of 3-5 microM. Far-UV circular dichroism spectra showed that the refolded polypeptide contained approximately 25% alpha-helical and 23% beta-sheet secondary structures. Analysis of the disulfide bond pattern of the refolded receptor fragment revealed disulfide bonds between Cys170 and Cys131, Cys148 and Cys108, and Cys117 and Cys48. These results demonstrate that the extracellular N-terminal domain of the parathyroid hormone receptor (PTHR1) possesses a well-defined, stable conformation, which shows a significant ligand binding activity.

Amino Acid Sequence↗
PubMed2000

Cloning and targeted disruption of two polygalacturonase genes in Penicillium olsonii.

The filamentous fungus Penicillium olsonii secretes several polygalacturonases (PGs) with molecular masses of about 47 kDa. These enzymes consist of several basic and acidic isoforms, with dominant activities at pI 4.5 and pI 7.9. Two polygalacturonase genes, pg1 and pg2, have been cloned. The corresponding enzymes, PG1 and PG2, consist of 370 and 380 amino acids, respectively, and show significant similarities to endo-polygalacturonases from other filamentous fungi. Targeted disruption of pg1 resulted in the elimination of all basic PG isoforms. In contrast, disruption of pg2 reduced, but did not eliminate the acidic PG activities. The PGs of P. olsonii must therefore be encoded by a gene family of at least three genes. Induction studies with various carbon sources revealed that the acidic and basic isoforms are differentially regulated. Pectin is the best inducer of the acidic PG isoforms. The basic isoforms, however, are best induced by monosaccharides like glucose, alpha-L-rhamnose and alpha-L-arabinose.

Cloning, Molecular↗
PubMed2000

Secreted lipases of Candida albicans: cloning, characterisation and expression analysis of a new gene family with at least ten members.

Extracellular lipolytic activity enabled the human pathogen Candida albicans to grow on lipids as the sole source of carbon. Nine new members of a lipase gene family (LIP2-LIP10) with high similarities to the recently cloned lipase gene LIP1 were cloned and characterised. The ORFs of all ten lipase genes are between 1281 and 1416 bp long and encode highly similar proteins with up to 80% identical amino acid sequences. Each deduced lipase sequence has conserved lipase motifs, four conserved cysteine residues, conserved putative N-glycosylation sites and similar hydrophobicity profiles. All LIP genes, except LIP7, also encode an N-terminal signal sequence. LIP3-LIP6 were expressed in all media and at all time points of growth tested as shown by Northern blot and RT-PCR analyses. LIP1, LIP3, LIP4, LIP5, LIP6 and LIP8 were expressed in medium with Tween 40 as a sole source of carbon. However, the same genes were also expressed in media without lipids. Two other genes, LIP2 and LIP9, were only expressed in media lacking lipids. Transcripts of most lipase genes were detected during the yeast-to-hyphal transition. Furthermore, LIP5, LIP6, LIP8 and LIP9 were found to be expressed during experimental infection of mice. These data indicate lipid-independent, highly flexible in vitro and in vivo expression of a large number of LIP genes, possibly reflecting broad lipolytic activity, which may contribute to the persistence and virulence of C. albicans in human tissue.

Amino Acid Sequence↗