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G Thiel

Publications and source records attributed to G Thiel.

At least 145 records · Page 8Linked to original sources
PubMed1992

Identification of a protein that binds to the SH3 region of Abl and is similar to Bcr and GAP-rho.

A Src homology 3 (SH3) region is a sequence of approximately 50 amino acids found in many nonreceptor tyrosine kinases and other proteins. Deletion of the SH3 region from the protein encoded by the c-abl proto-oncogene activates the protein's transforming capacity, thereby suggesting the participation of the SH3 region in the negative regulation of transformation. A complementary DNA was isolated that encoded a protein, 3BP-1, to which the SH3 region of Abl bound with high specificity and to which SH3 regions from other proteins bound differentially. The sequence of the 3BP-1 protein is similar to that of a COOH-terminal segment of Bcr and to guanosine triphosphatase-activating protein (GAP)-rho, which suggests that it might have GAP activity for Ras-related proteins. The 3BP-1 protein may therefore be a mediator of SH3 function in transformation inhibition and may link tyrosine kinases to Ras-related proteins.

3T3 Cells↗
PubMed1992

Synapsin IIa: expression in insect cells, purification, and characterization.

Synapsin IIa belongs to a family of neuron-specific phosphoproteins called synapsins, which are associated with synaptic vesicles in presynaptic nerve terminals. In order to examine the biochemical properties of synapsin IIa, and ultimately its physiological function, purified protein is required. Since attempts to purify significant quantities of synapsin IIa, an isoform of the synapsins, from mammalian brain have proven difficult, we undertook the production of recombinant synapsin IIa by utilizing the baculovirus expression system. Rat synapsin IIa cDNA was introduced into the baculovirus genome via homologous recombination, and the recombinant baculovirus was purified. Spodoptera frugiperda (Sf9) cells infected with this virus expressed synapsin IIa as 5% of the total cellular protein. The recombinant protein was extracted from the particulate fraction of the infected Sf9 cells with salt and a nonionic detergent and purified by immunoaffinity chromatography. The purified synapsin IIa was phosphorylated by the catalytic subunit of cAMP-dependent protein kinase to a stoichiometry of 0.8 mol of phosphate/mol of protein. Metabolic labeling with [32P]Pi demonstrated synapsin IIa phosphorylation in infected Sf9 cells. Using a homogenate of uninfected Sf9 cells, a cAMP-dependent protein kinase activity which can phosphorylate synapsin IIa was detected. Limited proteolysis of recombinant synapsin IIa phosphorylated in vitro and in vivo resulted in identical phosphopeptide maps. Further, synapsin IIa, like synapsin I, binds with high affinity in a saturable manner to synaptic vesicles purified from rat cortex.

Animals↗
PubMed1992

Dosage of OKT3 independent of body weight: a mistake?

Comparing OKT3 and antithymocyte globulin (ATG) in a prospective study, the dosage difference in regard to body weight (ATG: dependent on body weight/OKT3: independent) does not introduce any obvious source of mistake concerning clinical effectiveness or side effects. One explanation for the lack of influence of body weight may be the high effectiveness of 5 mg of OKT3, reaching a maximal effect even with lower plasma levels in heavier patients. We wonder, therefore, whether the OKT3 dosage could be lowered.

Animals↗
PubMed1992

Cyclosporin A has no impact on alterations of the lipid profile after renal transplantation.

The literature contains conflicting ideas regarding the role of cyclosporin A (CyA) in the induction of posttransplant dyslipidemia. The available studies contain small numbers of patients, especially on CyA monotherapy. We compared 65 patients on conventional azathioprine-prednisone therapy (AP) with 85 patients on CyA monotherapy, 19 on CyA-azathioprine therapy (CA), 20 on CyA-prednisone therapy (CP), and 52 on a triple therapy with CyA, azathioprine, and prednisone (CAP). From the results, it is concluded that patients on CyA monotherapy had lower serum cholesterol levels, with a lower high-density lipoprotein (HDL)-cholesterol level, probably due to the lower total cholesterol, compared with AP patients. From all groups, the CyA monotherapy group showed the most beneficial lipid profile. No additive negative influences of CyA when combined with other immunosuppressive drugs were noted. Thus, a correlation between derangements of the lipid profile and CyA therapy could not be confirmed. Further analysis of our data showed negative influences of antihypertensive treatment on lipid metabolism, particularly in the case of treatment with beta-blockers or diuretics. It cannot be excluded that studies showing a negative influence of CyA therapy on lipid homeostasis were biased by secondary factors like antihypertensive therapy, which was often not taken into account.

Azathioprine↗
PubMed1992

Early diagnosis of kidney transplant rejection and cyclosporin nephrotoxicity by urine cytology.

A total of 2000 urine samples from 53 kidney transplant recipients were studied to develop a routine method for the early diagnosis of rejection and cyclosporin (CSA) nephrotoxicity in urine. New-Sternheimer staining and an immunocytochemical technique were used together with classical Papanicolaou staining to differentiate cells in the urine. After cell count and differentiation of second morning urine samples with New-Sternheimer and Papanicolaou stains, immunocytochemistry was performed using antibodies against the following antigens: CD2, CD4, CD8, CD25, CD71 (transferrin receptor), HLA-DR and cytokeratin (Lu-5). Cell counts were obtained for the positively-reacting cells per millilitre of urine. By New-Sternheimer and Papanicolaou staining, CSA nephrotoxicity was characterized by the predominance of proximal tubular cells. During rejection episodes, increased numbers of mononuclear cells and renal epithelial cells were found. Immunocytochemical analysis showed a significant increase in CD2-, CD4-, CD8-, CD25-, CD71-, and HLA-DR-positive epithelial cells and in the ratio HLA-DR/cytokeratin-positive epithelial cells in rejection. CD25-positive cells had the highest sensitivity and specificity for the diagnosis of rejection. Our urine cytology technique proved to be a useful and non-invasive method for the early diagnosis of rejection and CSA nephrotoxicity.

Adolescent↗
PubMed1992

Glomerular hyperfiltration after unilateral nephrectomy in living kidney donors.

Glomerular hyperfiltration, which is expected to occur after uninephrectomy, could potentially damage the non-transplanted donor kidney in living donor transplantation. We therefore prospectively measured renal function (inulin and PAH clearance), albumin excretion and blood pressure in the donors of 30 consecutive living donor kidney transplants before uninephrectomy (n = 29) and 1 week (n = 27) and 1 year (n = 16) after. Hyperfiltration was defined as: (post-nephrectomy inulin clearance)/(0.5 x pre-nephrectomy inulin clearance); hyperperfusion was defined in an analogous way for PAH clearance. Hyperfiltration averaged 128 +/- 5% [SEM] and hyperperfusion 133 +/- 6% 1 week after uninephrectomy. Hyperfiltration was nearly unchanged (126 +/- 7%) 1 year after nephrectomy, whereas hyperperfusion had significantly decreased to 118 +/- 8% (P < 0.02). There was no significant change in blood pressure after nephrectomy, and no new cases of hypertension were observed during the 1-year follow-up. The degree of hyperfiltration did not correlate with donor age. Microalbuminuria > 30 mg/24 h was found in two donors 1 week after nephrectomy (one of which normalized at 1 year) and in one additional donor 1 year after nephrectomy. The degree of hyperfiltration did not correlate with albumin excretion rate. In conclusion, no adverse consequences of hyperfiltration were demonstrable during the 1-year observation period, but the prognostic role of occasional microalbuminuria should be further investigated.

Adult↗
PubMed1992

Membrane transport in stomatal guard cells: the importance of voltage control.

Potassium uptake and export in the resting conditions and in response to the phytohormone abscisic acid (ABA) were examined under voltage clamp in guard cells of Vicia faba L. In 0.1 mM external K+ (with 5 mM Ca2(+)-HEPES, pH 7.4) two distinct transport states could be identified based on the distribution of the free-running membrane voltage (VM) data in conjunction with the respective I-V and G-V relations. One state was dominated by passive diffusion (mean VM = -143 +/- 4 mV), the other (mean VM = -237 +/- 10 mV) exhibited an appreciable background of primary H+ transport activity. In the presence of pump activity the free-running membrane voltage was negative of the respective K+ equilibrium potential (EK+), in 3 and 10 mM external K+. In these cases VM was also negative of the activation voltage for the inward rectifying K+ current, thus creating a strong bias for passive K+ uptake through inward-rectifying K+ channels. In contrast, when pump activity was absent VM was situated positive of EK+ and cells revealed a bias for K+ efflux. Occasionally spontaneous voltage transitions were observed during which cells switched between the two states. Rapid depolarizations were induced in cells with significant pump activity upon adding 10 microM ABA to the medium. These depolarizations activated current through outward-rectifying K+ channels which was further amplified in ABA by a rise in the ensemble channel conductance. Current-voltage characteristics recorded before and during ABA treatments revealed concerted modulations in current passage through at least four distinct transport processes, results directly comparable to one previous study (Blatt, M.R., 1990, Planta 180:445) carried out with guard cells lacking detectable primary pump activity. Comparative analyses of guard cells in each case are consistent with depolarizations resulting from the activation of an inward-going, as yet unidentified current, rather than an ABA-induced fall in H(+)-ATPase output. Also observed in a number of cells was an inward-directed current which activated in ABA over a narrow range of voltages positive of -150 mV; this and additional features of the current suggest that it may reflect the ABA-dependent activation of an anion channel previously characterized in Vicia guard cell protoplasts, but rule out its function as the primary mechanism for initial depolarization.(ABSTRACT TRUNCATED AT 400 WORDS)

Abscisic Acid↗
PubMed1992

Karyotypes in 90 human gliomas.

Cytogenetic studies were performed on 90 human gliomas including 26 astrocytomas, 12 oligodendrogliomas, three oligo-astrocytomas, seven ependymomas, eight pilocytic astrocytomas, and 33 malignant gliomas (anaplastic astrocytomas and glioblastomas). The most common abnormalities were trisomy 7 in 23 cases, monosomy 22 in 15 cases, losses of the Y chromosome in 19 of 50 male cases, and losses of the X chromosome in 10 of 39 female cases. There are evident differences between the particular subgroups of gliomas. Monosomy 10 and double minutes are typical for malignant gliomas. The 58 determined chromosomal breakpoints were located on 45 different sites. Chromosomes 1, 9, 6, 3, 10, and 17 were predominantly involved.

Adult↗
PubMed1992

Improving adherence to fluid restrictions in male hemodialysis patients: a comparison of cognitive and behavioral approaches.

A cognitive intervention and a behavioral intervention were compared to determine their relative effectiveness in reducing interdialytic weight gain (IWG) among eight adult male hemodialysis patients. The behavioral model consisted of positive reinforcement, shaping, and self-monitoring. The cognitive model consisted of a counseling intervention designed to modify health beliefs. Three small-sample experimental studies showed that both interventions produced immediate reductions in IWG. However, the behavioral intervention was superior to the cognitive intervention in producing maintenance of reduced weight gain. Combining the interventions resulted in no improvement over the behavioral intervention alone. Continuation of self-monitoring procedures produced maintenance of improvements up to 2 months posttreatment. Repeated-measures analysis of variance showed changes for only the "barriers" dimension of the health belief model (Hartman & Becker, 1978) (p < .001), and this occurred only following or concurrent with adherence behavior change. Suggestions for treatment and future research are offered.

Cognitive Behavioral Therapy↗
PubMed1992

Pressure dependent modulation of renin release in isolated perfused glomeruli.

The isolated perfused glomerulus technique was used to study pressure dependence of renin release in single, microdissected rabbit glomeruli with intact afferent arteriole and intact Bowman's capsule. Renin release from individual afferent-glomerular units was measured in 30 minute intervals while afferent arteriolar pressure was either decreased from 55 to 40 to 25 mm Hg or increased from 25 to 40 to 55 mm Hg. There was a clear, inverse relation of renin release and afferent pressure. Mean renin release rate was 3.2 times higher at 25 than at 55 mm Hg and 1.5 times higher at 40 than at 55 mm Hg. To evaluate the possible role of wall stretch in mediating this response, inner and outer afferent arteriolar diameters were measured by videomicroscopy. Outer afferent diameter remained constant between 25 and 55 mm Hg, whereas inner diameter exhibited a slight increase. Changes of afferent arteriolar wall stretch, however, did not correlate with changes of renin release. These data for the first time directly demonstrate the existence of a renin baroceptor at the level of the renal afferent arteriole. They furthermore suggest that this baroceptor is not a stretch receptor.

Animals↗
PubMed1992

The efficacy and tolerability of cyclosporine G in human kidney transplant recipients.

Twelve consecutive first cadaveric kidney transplant recipients received cyclosporine G (CsG)(initial dose 12 mg/kg per day) as basic immunosuppressive treatment along with prednisone (initial dose 0.5 mg/kg per day) for the first three months after transplantation. Thereafter CsG was replaced by Sandimmun (cyclosporine, CsA). Evaluation of the immunosuppressive efficacy and assessment of possible side effects of CsG was made and compared with the results in 38 historical control patients starting with the same dose of CsA as part of the same immunosuppressive dosage schedule. Statistically, there was no difference in patient survival at three (91% in CsG group versus 95% in CsA group) and twelve months (91% in CsG group versus 92% in CsA group), or in graft survival at three (75% in CsG group versus 89% in CsA group) and twelve months (75% in CsG group versus 84% in the CsA group). At equivalent oral doses of CsG and CsA significantly higher blood levels of CsG were observed (2P less than 0.05). Nephrotoxicity assessed by graft biopsy could be demonstrated to a similar extent in both groups, whereas hepatotoxicity was more pronounced during CsG treatment. Sequential measurements of bilirubin revealed a significant increase in all patients but median values were significantly higher in the CsG patients. A pronounced and concordant elevation of liver enzymes occurred during CsG treatment in three out of 12 patients. Liver biopsies performed in these patients revealed histological alterations consistent with toxic liver injury. Thus, in human kidney transplant recipients CsG and CsA appeared to be equally immunosuppressive and nephrotoxic but more hepatotoxic. On the basis of this limited experience we conclude that in human kidney transplant recipients CsG has no advantage over CsA.

Adult↗
PubMed1992

Renal graft rejection or cyclosporin toxicity? Early diagnosis by a combination of Papanicolaou and immunocytochemical staining of urinary cytology specimens.

A method is described for distinguishing between graft rejection and cyclosporin nephrotoxicity in renal allograft recipients by analyzing fresh morning urine samples. The technique combines classic Papanicolaou with immunocytochemical staining and was performed in urine specimens from a series of 42 patients. Early-stage cyclosporin toxicity was usually associated with increased numbers of proximal tubular cells only, whereas in rejection and late-stage toxicity there were increases in both tubular cells and in lymphocytes and monocytes (greater than 2000 cells/ml urine). Differentiation between these two clinical conditions was achieved by immunostaining, which revealed that increased numbers of CD25+ and CD8+ cells, as well as an increase in the HLA-DR/Lu5 ratio, were typical of rejection. CD25 positivity proved to be the best indicator of rejection, with a sensitivity and specificity of more than 90%. A cytodiagnostic algorithm is presented that is based on cell numbers and types, including immunophenotypes. The proposed method has the advantage of being noninvasive and appears to represent a reliable and rapid adjunct for the monitoring of graft function, especially in high-risk patients on cyclosporin immunosuppression.

Adolescent↗
PubMed1992

Risks and benefits of graft biopsy in renal transplantation under cyclosporin-A.

261 patients who received a kidney transplant under cyclosporin-A immunosuppression were reviewed in order evaluate the benefits and the risks of renal graft biopsies. 240 graft biopsies were performed in 124 of the 261 patients. The biopsy diagnoses were 103x rejection, 90x cyclosporin-A toxicity, 8x acute tubular necrosis, 8x glomerulonephritis, 9x different biopsy results, and 12 cases of normal renal tissue. In 214 cases the clinical course was well explained by the biopsy result. The histological results led to therapeutical changes in 199 cases. 221 of the 240 biopsies were performed without any complications. There was only one biopsy with irreversible and there were 19 biopsies with reversible complications.

Biopsy↗
PubMed1992

Studies on morphological outcome of cyclosporine-associated arteriolopathy after discontinuation of cyclosporine in renal allografts.

Cyclosporine (CSA)-associated arteriolopathy (CAA) is the second most frequent morphological diagnosis in renal allografts and its final outcome remains unclear. The present study was performed to clarify the morphological outcome of CAA by follow-up histological analysis after stopping CSA. Furthermore, the clinical management of patients showing CAA is discussed. Most of the patients came from our early experience with CSA between 1981-1983 when CSA doses and trough levels were high. Twenty recipients were divided into two groups according to the presence of CAA after stopping CSA: group A (n = 9) showed persistent CAA and group B (n = 11) showed no CAA. The majority of the patients, including five incomplete remission in group A, showed obvious improvement of CAA even if the arterioles were severely affected. Improvement of CAA was noted a few months after stopping CSA or after lower dose CSA therapy. There were no significant differences in CSA blood levels or duration of CSA therapy between the groups. The severity of preexistent CAA was significantly greater in group A. Only two patients who died from malignant tumor showed exacerbation of CAA. Eight patients died and eight grafts were lost, seven due to vascular rejection and one to hemolytic uremic syndrome-like CAA. Poor renal function was also noted in four cases with functioning graft owing to vascular rejection even though the improvement of CAA was evident. The complete regression of CAA and the remodelling of arterioles showing well preserved vascular patency were frequently found after stopping or reducing the dose of CSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Glomerular hyperfiltration following unilateral nephrectomy in healthy subjects].

23 living related kidney transplant donors were prospectively studied to determine the degree of hyperfiltration which occurs after uninephrectomy and to monitor potential consequences of this procedure such as hypertension, microalbuminuria or renal functional impairment. Standard inulin and PAH clearance studies were performed immediately before (n = 23), one week after (n = 22) and one year after nephrectomy (n = 12). Hyperfiltration was defined as the ratio of (post-nephrectomy inulin clearance)/(0.5 x pre-nephrectomy inulin clearance), hyperperfusion was defined in an analogous way for PAH clearance. One week after uninephrectomy, hyperfiltration averaged 134 +/- 6% (SEM) and hyperperfusion was 138 +/- 6%. The degree of hyperfiltration did not correlate with donor age. One year after nephrectomy, hyperfiltration was nearly unchanged (130 +/- 7%) whereas hyperperfusion had significantly decreased to 119 +/- 8% (p less than 0.05). Blood pressure did not increase after nephrectomy and no new cases of hypertension were observed during follow-up. In contrast, there were two new cases of microalbuminuria at one week and one year after nephrectomy. Further follow-up of these kidney donors is warranted.

Adult↗
PubMed1991

Characterization of tissue-specific transcription by the human synapsin I gene promoter.

Synapsin Ia and synapsin Ib are abundant synaptic vesicle proteins that are derived by differential splicing from a single gene. To identify control elements directing the neuronal expression of synapsins Ia/b, we functionally analyzed the promoter region of the human synapsin I gene. A hybrid gene was constructed containing 2 kilobases of 5' flanking sequence from the synapsin I gene fused to the bacterial gene chloramphenicol acetyltransferase and transfected into 12 different neuronal and nonneuronal cell lines. In general, expression of the chimeric reporter gene showed excellent correlation with endogenous expression of synapsin I in different neuronal cell lines, whereas transcription was low in all nonneuronal cell lines examined. The addition of the simian virus 40 enhancer promoted non-tissue-specific expression. Deletion mutagenesis of the synapsin I promoter revealed the presence of positive and negative sequence elements. A basal (constitutive) promoter that directs reporter gene expression in neuronal and nonneuronal cell lines was mapped to the region -115 to +47. The promoter region from -422 to -22 contains positive elements that upon fusion with the herpes simplex virus thymidine kinase promoter potentiate its transcription in PC12 and neuroblastoma cells but not in Chinese hamster ovary cells.

Animals↗
PubMed1991

Coamplification of simple repetitive DNA fingerprint fragments and the EGFR gene in human gliomas.

DNA fingerprints were generated by the oligonucleotide probe (GTG)5 from surgically removed tissue and/or primary cell culture of 36 intracranial tumors (31 gliomas, 1 medulloblastoma, 4 metastatic carcinomas) and compared with the constitutional banding pattern obtained from the peripheral blood leukocytes of each patient. A multitude of somatic changes was detected and found to reflect the chromosome alterations identified by parallel karyotype analysis. Gain and/or loss of bands or significant band intensity shifts could be demonstrated in the fingerprints of more than 80% of the tumors investigated. This included a highly amplified fingerprint fragment in five independent gliomas (four of them had double minutes, dmin) which appeared not individual- but tumor-specific (2.4 kilobases, kb, after HaeIII digestion). Rehybridization with the oligonucleotide probes (GT)8 and (GATA)4, respectively, revealed additional amplified fingerprint fragments in the tumor DNA of these patients. While a (ca/gt)n fragment (2.6 kb. HaeIII) was also found to be amplified in all five cases, one band detected with (GATA)4 (1.4 kb, HaeIII) represented a unique feature for one of these tumors only. Amplification of the epidermal growth factor receptor (EGFR) gene via Southern blot hybridization was revealed only in those tumors showing the amplified DNA fingerprint fragments as well. Thus in many gliomas the amplification unit harbors two simple repetitive DNA fingerprint loci, (cac/gtg)n and (ca/gt)n, in addition to the EGFR gene.

Adolescent↗