The product of the hypB gene, which is required for the maturation of the three [NiFe]hydrogenases of Escherichia coli, is a member of the GTPase family and exhibits a low intrinsic GTPase activity. It was studied whether or not GTP hydrolysis by HypB is coupled to nickel insertion into hydrogenases and to maturation of hydrogenases. Mutations were introduced into the hypB gene at sites expected to code for amino acids involved in guanine-nucleotide binding.
View Article and Find Full Text PDFThe FHLA protein is the transcriptional regulator of the genes of the formate regulon from Escherichia coli. The protein shares homology with the sigma 54-dependent regulators of the NTRC family in the central and C-terminal domains but differs in possessing an extended N terminus lacking the aspartate residue which is the site of phosphorylation. Purified FHLA displays intrinsic ATPase activity which is stimulated weakly by formate and DNA.
View Article and Find Full Text PDFA mutant of Methanosarcina barkeri (Fusaro) is able to grow on pyruvate as the sole carbon and energy source. During growth, pyruvate is converted to CH4 and CO2, and about 1.5 mol of ATP per mol of CH4 is formed (A.
View Article and Find Full Text PDFWe tested the hypothesis that the fludrocortisone in doses sufficient to elevate blood pressure (BP) in normal subjects would increase platelet cytosolic calcium. Eight normal volunteers were given 0.8 mg fludrocortisone daily for 7 days (short protocol).
View Article and Find Full Text PDFPurpose: To evaluate a fast three-dimensional (3D) sequence that permits the acquisition of 16 T2-weighted images within a 29-second breath hold for magnetic resonance (MR) imaging of the liver.
Materials And Methods: Eighty-seven patients with focal liver lesions were examined at 1.5 T by using a 3D reversed fast imaging with steady-state precession (PSIF) sequence at flip angles of 15 degrees, 30 degrees, and 70 degrees and a T2-weighted spin-echo (SE) sequence.
The large subunits of nickel-containing hydrogenases are synthesised in a precursor form which, after nickel incorporation, is processed by proteolytic cleavage at the C-terminal end. The protease involved in processing of HycE, the large subunit of hydrogenase 3 from Escherichia coli, was purified by three chromatographic steps to apparent homogeneity. Its gene was identified by using a hybridisation probe generated by PCR with oligonucleotide primers the sequence of which was derived from the N-terminal and internal amino acid sequences.
View Article and Find Full Text PDFNephrol Dial Transplant
August 1995
The data concerning the value of duplex sonography in diagnosing parenchymatous renal allograft dysfunction are controversial. Most early studies did not take into consideration the many factors influencing resistance parameters. We therefore performed a prospective, biopsy-controlled study with exclusion of all known sources of error regarding resistance parameters.
View Article and Find Full Text PDFReticulocyte quantification in peripheral blood samples is a commonly used diagnostic indicator of erythropoietic activity. A methodology based on flow cytometry additionally separates reticulocytes into 3 groups by fluorescence staining of the residual RNA. This identifies cells as 'high (HFR), medium (MFR) and low (LFR) fluorescence intensity' reticulocytes.
View Article and Find Full Text PDFSchweiz Med Wochenschr
November 1994
For early diagnosis of cytomegalovirus (CMV) infection after renal transplantation, 18 patients were monitored within the first 3 months. Blood leukocytes were assayed weekly for the presence of the CMV matrix protein p65 (antigenemia assay) and CMV DNA by the polymerase chain reaction (PCR). In 12 out of 18 patients, 70 (37.
View Article and Find Full Text PDFIn clinical practice p-creatinine is used to estimate changes of GFR. Generally, it is believed that recovery of p-creatinine within 10% of initial baseline allows exclusion of relevant nephrotoxic changes. We evaluated whether recovery of GFR after discontinuation of CyA therapy can be adequately predicted by measuring p-creatinine alone.
View Article and Find Full Text PDFTransplant Proc
October 1994
To evaluate long-term benefits and risks of CyA therapy in renal transplantation, we analyzed the 10-year experience with all 59 patients who had received a first cadaveric renal graft until August 1983 and were immunosuppressed with CyA. We compared their actual graft survival with that of all 213 patients who had received a first cadaveric graft from 1967 until August 1983, but were immunosuppressed initially with azathioprine and prednisone (AzaP). For comparison of p-creatinine, proteinuria, blood pressure, lipids, uric acid and skin malignancies we evaluated the patients staying unchanged on initial therapy for 10 years (CyA = 12, AzaP = 53).
View Article and Find Full Text PDFReticulocyte quantification in peripheral blood samples is a commonly used diagnostic indicator of erythropoietic activity. A methodology based on flow cytometry additionally separates reticulocytes into three groups by fluorescence staining of the residual RNA. This identifies cells as high (HFR), medium (MFR) and low (LFR) fluorescence intensity reticulocytes.
View Article and Find Full Text PDFPurified FHLA, the transcriptional activator of the formate regulon from Escherichia coli, is able to efficiently stimulate transcription from the sigma 54-dependent promoters of the fdhF, hyp, and hyc transcriptional units. Expression was dependent on the presence of sigma 54, of the upstream activatory sequence (UAS), and of formate. Hypophosphite, a formate analogue, could substitute for formate in vitro suggesting that formate per se was active in regulation.
View Article and Find Full Text PDFFHLA is the transcriptional activator for the expression of the genes coding for components of the formate hydrogenlyase system of Escherichia coli. The cloned fhlA gene was overexpressed under selected growth conditions, and a purification protocol for the FHLA protein was developed. Purified FHLA in the native state is a homotetramer.
View Article and Find Full Text PDFAlthough the tRNA species directing selenocysteine insertion in prokaryotes differ greatly in their primary structure from that of their eukaryotic homologues they share very similar three-dimensional structures. To analyse whether this conservation of the overall shape of the molecules reflects a conservation of their functional interactions it was tested whether the selenocysteine inserting tRNA species from Homo sapiens supports selenoprotein synthesis in E. coli.
View Article and Find Full Text PDFUsing a stepwise logistic regression analysis, we investigated clinical data, allergologic findings, spirometric data, and the cellular and humoral immune system in order to gain new insights into the role these parameters play in bronchial hyperresponsiveness to methacholine in children and to create a model for the prediction thereof. Bronchial hyperresponsiveness, which was found in 124 of 462 children (26.8%), was observed to have been influenced by an increased level of eosinophils, the positivity of the skin prick test for any of the allergens tested, a decreased baseline forced expiratory volume in 1 second (FEV1) (percent predicted), a decreased maximum expiratory flow at 50% expiration as a percent of forced vital capacity, and a decreased level of kappa-chain-assembled immunoglobulins.
View Article and Find Full Text PDFA system was devised which allows the efficient substitution of cysteine residues in a protein by selenocysteine. It involves overexpression of the respective gene with the aid of the T7 promotor/polymerase system in a cysteine auxotrophic strain. The induction of the T7 polymerase formation was performed in cysteine-supplemented medium followed by wash-out of the cysteine and production of the desired gene product in the presence of selenocysteine.
View Article and Find Full Text PDFPurification of the large subunit, HYCE, of Escherichia coli hydrogenase 3 revealed that it is a nickel-containing polypeptide, which is subject to C-terminal proteolytic processing. This processing reaction could be performed in vitro with partially purified components, yielding a low-molecular mass C-terminal peptide which was resolved in a Tricine/SDS/polyacrylamide gel. N-terminal sequencing of this peptide revealed that proteolytic cleavage occurred at the C-terminal side of the arginine residue at position 537, which corresponds to the histidine residue in the highly conserved motif, DPCXXCXXH, of other (NiFe) hydrogenases thought to be involved in active site nickel coordination.
View Article and Find Full Text PDFThe genes (selC) coding for the selenocysteine-inserting tRNA species (tRNA(Sec)) from Clostridium thermoaceticum and Desulfomicrobium baculatum were cloned and sequenced. Although they differ in numerous positions from the sequence of the Escherichia coli selC gene, they were able to complement the selC lesion of an E. coli mutant and to promote selenoprotein formation in the heterologous host.
View Article and Find Full Text PDFIn Escherichia coli the unusual amino acid selenocysteine is incorporated cotranslationally at an in-frame UGA codon. Incorporation of selenocysteine relies, in part, on the interaction between a specialized elongation factor, the SELB protein, and a cis-acting element within the mRNA. Boundary and toeprint experiments illustrate that the SELB-GTP-Sec-tRNA(Sec) ternary complex binds to the selenoprotein encoding mRNAs fdhF and fdnG, serving to increase the concentration of SELB and Sec-tRNA(Sec) on these mRNAs in vivo.
View Article and Find Full Text PDFThe neuropeptides thyrotropin-releasing hormone (TRH) and corticotropin-releasing hormone (CRH) have been found to be potent stimulators of the autonomic nervous system in both experimental animals and humans. We studied the effects of different doses of CRH and TRH given intracerebroventricularly in the urethane-anesthetized rat and a single dose of CRH in the chloral hydrate-anesthetized rat to elucidate the effects of these peptides in the unconscious state. All TRH doses studied enhanced blood pressure and noradrenaline and adrenaline secretion.
View Article and Find Full Text PDF