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Biomedical subjects

A Klein

Publications and source records attributed to A Klein.

At least 217 records · Page 12Linked to original sources
PubMed1994

Br/Rb ratio obtained by XRF analysis of kidneys of normal and tumor-bearing mice treated with cis-DDP.

The Br/Rb ratio in kidneys of normal and tumor-bearing mice was studied and a significant difference was found between the two groups. The mice were treated with cis-DDP with and without selenite, with selenite alone, and compared with controls. The animals were sacrificed 7d, 14d, and 21-28d after treatment. The kidneys were removed and subjected to Br and Rb determination by a novel X-ray fluorescence (XRF) method. The results are presented in terms of estimated net count rates under the BrK alpha and RbK alpha peaks. No significant differences were found in Br and Rb levels or in the Br/Rb ratio in kidneys of treated and untreated mice belonging to the same group-normals or lung carcinoma inoculated. However, there was a significant difference in the Br/Rb ratio between the two tested groups (normals and inoculated). Preliminary results on the Br/Rb ratio obtained from normal and malignant tissues of colorectal cancer (CRC) patients and from mice inoculated with melanoma, show the same trend as those from the group of mice with lung carcinoma. In all three groups tested the Br/Rb ratio was 2-4 times higher in normal than in malignant tissue.

Animals↗
PubMed1993

Influence of illumination on the electronic interaction between 77Se and nickel in active F420-non-reducing hydrogenase from Methanococcus voltae.

The selenium-containing F420-non-reducing hydrogenase from Methanococcus voltae was anaerobically purified. The enzyme as isolated showed an EPR spectrum with gx,y,z = 2.21, 2.15 and 2.01. Upon illumination this spectrum disappeared and a new signal with the lowest g value at 2.05 arose. EPR studies were carried out either with the enzyme containing natural selenium or enriched in the nuclear isotope 77Se. The hyperfine splitting caused by 77Se in the 'dark' signal is shown to be highly anisotropic. In contrast the splitting is nearly isotropic after illumination. A new model for the nickel site is proposed to explain these observations.

Anaerobiosis↗
PubMed1993

Over-expression of a functionally active human GM2-activator protein in Escherichia coli.

The cDNA of the human GM2-activator protein was cloned into the expression vector pHX17. The plasmid encodes a fusion protein with a hexahistidine tail and a Factor Xa cleavage site at its N-terminus. The recombinant protein was purified from cell homogenates under denaturing conditions by metal-ion affinity chromatography in a single step and then was refolded. The hexahistidine tail could be removed when desired by digestion with Factor Xa. In a functional assay, the GM2-activator thus generated from Escherichia coli and renatured, with or without the hexahistidine tail, was as active as the native GM2-activator protein that was purified from human tissue. When added to the culture medium, the recombinant carbohydrate-free GM2-activator, carrying the hexahistidine tail, could be taken up efficiently and restored the degradation of ganglioside GM2 to normal rates in mutant fibroblasts with the AB variant of GM2-gangliosidosis, which is characterized by a genetic defect in the GM2-activator protein. The prokaryotic expression system is useful for producing milligram quantities of a pure and functionally active GM2-activator.

Amino Acid Sequence↗
PubMed1993

A novel very small subunit of a selenium containing [NiFe] hydrogenase of Methanococcus voltae is postranslationally processed by cleavage at a defined position.

A coenzyme-F420 non-reducing [NiFe] hydrogenase was isolated from Methanococcus voltae. It consists of three subunits. They are the products of the previously identified genes vhuA, vhuG and vhuU. The vhuU gene product is of only 25 amino acids. This novel very small hydrogenase subunit contains selenocysteine within a conserved amino-acid sequence previously shown to be involved in Ni coordination. The subunit is shorter than the predicted primary gene product and is therefore apparently post-translationally processed.

Amino Acid Sequence↗
PubMed1993

Isolation and structural characterization of novel sialylated oligosaccharide-alditols from respiratory-mucus glycoproteins of a patient suffering from bronchiectasis.

The carbohydrate chains of the respiratory-mucus glycoproteins of a patient (blood group O) suffering from bronchiectasis due to Kartagener's syndrome, were released by alkaline borohydride treatment of a pronase digest. The structures of 82 neutral and low-molecular-mass sialylated oligosaccharides have been described previously [van Kuik A., de Waard P., Vliegenthart J. F. G., Klein A., Carnoy C., Lamblin G. Roussel P. (1991) Eur. J. Biochem. 198, 169-182]. In the present work, medium-size sialylated oligosaccharides were obtained after ion-exchange chromatography and were subsequently separated into 36 fractions utilizing gel filtration, HPLC on normal-phase alkylamine-bonded silica and reverse-phase HPLC. From these fractions, the following six sialylated hepta- and octa-saccharide-alditols have been characterized by employing 500-MHz 1H-NMR spectroscopy, in conjunction with fast-atom-bombardment mass spectroscopy and methylation analysis. [formula: see text]

Bronchiectasis↗
PubMed1993

Regulatory role of enteric kappa opioid receptors in human colonic motility.

The effects of different kappa opioid agonists and antagonists on spontaneous mechanical activities and responses to electrical transmural nerve stimulation of both longitudinal and circular muscle strips from the human sigmoid colon were studied. A superfusion apparatus was used to record isometric contractions. Exogenously added kappa agonists did not modify spontaneous contractile activities on either type of strip. Nerve stimulation induced a triphasic response composed of a first contraction (C1) followed by a relaxation (C2) and an off-contraction (C3); this response was mediated by cholinergic excitatory nerves and non-adrenergic, non-cholinergic excitatory and inhibitory nerves. Dynorphin 1-13 and the synthetic kappa agonist trans-3,4-dichloro-N-methyl-N-(2- [1pyrolidinyl]-cyclohexyl) dramatically decreased the amplitude of the excitatory components C1 and C3. The effects of both kappa agonists were blocked in presence of the kappa antagonist Nor-Binaltorphimine. The delta antagonist ICI 174864 did not prevent the inhibition of the contractions C1 and C3 induced by dynorphin. Therefore, these data suggest that kappa receptors are involved in the neuroregulation of smooth muscle of human colon and mediate inhibition of cholinergic and non-cholinergic excitatory transmission within myenteric plexus.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1993

Modulation of pulmonary vascular resistance and edema formation by short-term infusion of a 10% fish oil emulsion.

BACKGROUND: The aim of this study was to investigate whether the pulmonary response to inflammatory stimulation, resulting in increased vascular resistance and permeability, could be attenuated by short-term infusion of triglycerides containing omega-3 fatty acids. With the concept of altering the composition of membrane phospholipids in such a manner that stimulation resulted in the release of less vasoconstrictive and permeability-enhancing metabolites of eicosapentaenoic acid instead of those of arachidonic acid (AA), the parenteral application of a lipid emulsion prepared from fish oil (Omegavenös) was tested in comparison with a soy oil preparation (Lipovenös). METHODS: Isolated lungs from anesthetized rabbits were ventilated and recirculatingly perfused (200 ml/min) with 200 ml cell-free buffer solution to which either 2 ml saline (controls, n = 6), 2 ml Lipovenös 10% (n = 6) or 2 ml Omegavenös 10% (n = 6) were added. To study the possible metabolic alterations in states of an enhanced AA turnover, lungs of each group were stimulated with smaller doses of A23187 (10(-8) M) during the 180-min lipid perfusion period, followed by a 10 times higher calcium ionophore A23187 (10(-7) M) challenge after washing out the lipids by exchange of perfusion fluid. Pulmonary artery pressure (PAP) and the lung weight gain indicating edema formation were monitored, and eicosanoids were analyzed in samples of the perfusate. RESULTS: Upon A23187 injection lung weight gain and PAP increase were significantly reduced (50%) in Omegavenös-perfused lungs in comparison with controls and Lipovenös treatment. The vascular reactions were accompanied by a shifting from LTC4 to LTC5 during and after Omegavenös perfusion. CONCLUSION: The data demonstrate that omega-3 fatty acids seem to be incorporated into the phospholipid pool of the pulmonary tissue, even after short-term infusion (3 h) resulting in an attenuated pressure reaction and edema formation due to an altered spectrum of metabolites in the case of inflammatory stimulation.

Acute-Phase Proteins↗
PubMed1993

Altered carbohydrate composition of salivary mucins from patients with cystic fibrosis and the adhesion of Pseudomonas aeruginosa.

We compared the chemical composition of salivary mucin glycopeptides from cystic fibrosis (CF) and from non-CF subjects and the adhesion of Pseudomonas aeruginosa to these different salivary glycopeptides. Three pools of CF saliva, four pools of non-CF saliva, one individual CF saliva, and one individual non-CF saliva were studied. The soluble fraction of the saliva was treated with pronase, and gel filtration was performed to obtain high and low molecular mass salivary mucin glycopeptides. The yield of total glycopeptides was significantly higher from CF than from non-CF saliva. Furthermore, the chemical composition revealed a significantly higher sialic acid content in CF than in non-CF mucin glycopeptides, and higher sulfate and fucose content in CF than in non-CF high molecular mass glycopeptides. We studied the adhesion of a nonmucoid strain of P. aeruginosa (1244), its nonpiliated isogenic derivative, and a mucoid strain (M35) to salivary mucin glycopeptides from patients with CF and from non-CF subjects. The three strains bound significantly more to the CF salivary glycopeptides than to the corresponding non-CF salivary glycopeptides. The nonpiliated isogenic mutant of P. aeruginosa 1244 also bound to CF salivary glycopeptides, suggesting that the adhesion of P. aeruginosa could involve nonpilus adhesions. Furthermore, neuraminidase treatment of CF glycopeptides decreased the adhesion of P. aeruginosa 1244. Altogether these results suggested that differences in mucins may in part explain the specificity of P. aeruginosa for CF.

Bacterial Adhesion↗
PubMed1993

[Risk factors of perioperative morbidity and mortality in colorectal cancer with special reference to tumor stage, site and age].

The perioperative risk was prospectively analyzed in 511 patients with colorectal cancer, out of which 5% had an emergency procedure. The morbidity rate was 23.6% without an association with tumour stage or localization. The incidence of nonsurgical complications rose with increasing age because of a rising number of concomitant illnesses (< 50: 5.7%, > 80: 28.1%). The morbidity was associated with an increasing blood loss during the operation (< 500 ml: 10.6%, > 2000 ml: 30.4%), but not with the type of treatment. The overall operative mortality rate was 2.3% with the same rate of surgical complications and complications of preexisting conditions. Morbidity and mortality following emergency procedure were 56%, respectively 20%, expressing mainly septical complications of colorectal cancer.

Adult↗