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Biomedical subjects

R Tauber

Publications and source records attributed to R Tauber.

At least 91 records · Page 5Linked to original sources
PubMed1988

Demonstration of glycosylation variants of human fibrinogen, using the new technique of glycoprotein lectin immunosorbent assay (GLIA).

A new highly sensitive method, incorporation the ELISA technique (enzyme-linked immunosorbent assay), is described for the quantitation of the glycan residues of glycoproteins. With the aid of this "glycoprotein-lectin immunosorbent assay (GLIA)", it is possible to determine the nature of the glycan residues of a single protein in a glycoprotein mixture, without prior purification. The GLIA can be used for the accurate determination of the inhibitor constant for the interaction of any monosaccharide with any lectin. Using the described technique, glycosylation of human fibrinogen from plasma and amniotic fluid were compared. In fibrinogen from amniotic fluid a "fetal" glycosylation type could be demonstrated. In addition, evidence is presented for the first time that plasma fibrinogen possesses (GlcNAc beta 1----4Man beta) residues (bisecting GlcNAc) and O-glycosidically bound carbohydrate units. Preliminary results were published as abstract (E. Köttgen et al. (1988) Fresenius Z. Anal. Chem. 330, 448).

Enzyme-Linked Immunosorbent Assay↗
PubMed1988

Incorporation of non-acetylated hexosamines into plasma membrane glycoproteins of liver cells after galactosamine injection.

The following procedure for the detection of non-acetylated amino sugars in the plasma membrane was established: i) derivatization of free amino groups with dansyl-chloride, ii) hydrolysis with 3 M HCl (for 4 h at 105 degrees C) to liberate the dansylated carbohydrate moieties from the plasma membrane, iii) purification of the dansylated amino sugars by paper chromatography and subsequent analysis by thin-layer chromatography. Using this procedure, plasma membranes from rat liver were analysed after injection of D-[14C]galactosamine. For this purpose, rats were divided into three groups: the first received D-galactosamine.HCl at a dose of 2 mg/kg b.w., the second at a dose of 75 mg/kg b.w. and the third at a hepatitis-inducing dose of 260 mg/kg b.w.. In all three groups the majority of the protein-bound radioactivity in the plasma membrane was not dansylated, thus representing N-acetylated amino sugars. At a dose of 2 mg/kg, only 0.34% of the protein-bound radioactivity in the plasma membrane reacted with dansyl-chloride. At a dose of 70 mg/kg this value increased to 1.9%. At 260 mg/kg the value was 3.6%. These results indicate that the incorporation of non-acetylated amino sugar into the plasma membrane was dose-dependent and reached 90 pmol per mg plasma membrane protein during galactosamine injury. However, this incorporation of non-acetylated amino sugars into the plasma membrane did not represent a pathological mechanism responsible for the onset of the galactosamine-induced liver injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1988

[Results of interstitial radiotherapy using I-125 seeds in the treatment of prostatic cancer].

30 patients with localized adenocarcinoma of the prostate were treated with pelvic lymphadenectomy and I-125 interstitial implantation from 1980 to 1985 (21/30 T3-tumors and 14/30 with poor differentiation). The mean follow-up is 59.5 months (range 18 to 88 months). The crude, progression-free and local progression-free survival rates (Kaplan-Meier) for all patients are 68%, 61% and 71% respectively. But, the progression-free survival is 39% in patients with G3-tumors after five years and only 25% in patients with T3 G3-tumors after four years. The local progression rate was 33% in patients with T3-tumors. We did not observe any late intestinal side-effects, but 11/30 (37%) patients suffered from later urinary flow problems caused mainly by local tumor progression. Therefore, we regard interstitial implantation with I-125-seeds as an alternative treatment to radical prostatectomy in patients with T1, 2 G1, 2-tumors but as insufficient in patients with T3 G3-tumors.

Adenocarcinoma↗
PubMed1987

Role of membrane glycoproteins in mediating trophic responses.

During growth and differentiation the plasma membrane has a key role not only in the reception and transmission of extracellular signals such as hormones and growth factors, but also in communicating cellular response to the cellular microenvironment. Cellular response to trophic stimuli includes alterations of cell shape and cell surface antigenicity, of cell-cell recognition and cellular adhesion, of cell matrix binding and the adaptation of cell surface receptors. The plasma membrane is therefore regarded as a 'central agency' for the integration of a single cell into the complex system of a tissue or of an organism. The numerous functions of the plasma membrane are mainly mediated by membrane integrated glycoproteins or glycolipids both sharing the common feature of covalently bound oligosaccharide side chains. Specific alterations of oligosaccharide structure and metabolism associated with growth, differentiation and various pathologic conditions suggest a specific role for the oligosaccharide moieties in the regulation of cell surface functions (Table 1). This review intends to focus on the role of plasma membrane glycoproteins describing briefly principles of glycoprotein structure and function, and characteristics of their biosynthesis and degradation.

Animals↗
PubMed1987

Half-lives of L-[35S]methionine and L-[3H]fucose of transferrin in the serum of rats.

The half-lives of 35S-labelled L-methionine and of 3H-labelled L-fucose of serum transferrin of rats were measured in pulse-chase experiments in vivo. Both L-[35S]methionine and L-[6-3H]fucose disappeared from transferrin with nearly the same half-lives of 33.8 h and 36.5 h, respectively. The data show that in this major serum glycoprotein peripheral carbohydrates and the protein moiety are degraded as a unit.

Animals↗
PubMed1987

[Role of glycoproteins in the pathogenesis of peptic ulcer].

Glycoproteins are major constituents of the two-component mucous barrier: glycoproteins of the mucin-type rich in carbohydrate groups form the viscoelastic mucous gel of the mucosa, oligosaccharides of glycoproteins and glycosphingolipids embedded into the plasma membrane form the glycocalyx of the epithelial cell surface. Both structures are thought to play major roles in protecting gastric mucosa against luminal acid and proteases. This assumption is supported by experimental evidence for mucus glycoproteins, however is largely hypothetical for cell surface glycoproteins. Reports that biosynthesis of mucus glycoproteins is decreased during gastric ulceration, while breakdown is enhanced indicate that disorders of glycoprotein biosynthesis and degradation may contribute to the pathogenesis of peptic ulcer disease. The molecular mechanisms responsible for the observed alterations, however, are unknown. Possible alterations of glycoprotein metabolism that may occur at different stages of biosynthesis and degradation are discussed.

Animals↗
PubMed1986

[Catecholamine behavior, adrenoreceptor density of intact cells and sensitivity to catecholamines in a patient with orthostatic hypotension].

We evaluated sympathetic nervous system function in a patient with primary orthostatic hypotension. Plasma catecholamine levels--except for dopamine levels--and urinary catecholamine excretion were decreased, alpha-adrenoreceptor responsiveness to noradrenaline and beta-adrenoreceptor responsiveness to isoproterenol were increased according to increased beta-2-adrenoreceptor density on intact polymorphonuclear leukocytes. Alpha-2-adrenoreceptor density on intact platelets and adrenaline-induced platelet aggregation in vitro, however, were unchanged. We evolved a therapeutic regimen with fludrocortisone, propranolol, and dihydroergotamine that allowed the patient to resume nearly a regular degree of mobility.

Aged↗
PubMed1986

Different oligosaccharide processing of the membrane-integrated and the secretory form of gp 80 in rat liver.

Rat liver synthesizes a glycoprotein with Mr of 80.000 (gp 80) which is partly inserted into the plasma membrane and partly secreted into the serum. The membrane-integrated and the secretory form of this glycoprotein have an identical peptide pattern, but different N-linked glycans. Whereas gp 80 from the serum is glycosylated with complex-type oligosaccharides, gp 80 from the plasma membrane has high mannose glycans. Phase separation with Triton X-114 showed that membrane-integrated gp 80 contains hydrophobic portions, whereas secretory gp 80 has hydrophilic properties. Intracellular transport and oligosaccharide processing of gp 80 were studied in vivo in the endoplasmic reticulum, the Golgi apparatus and plasma membranes of rat liver and in serum using pulse-chase labeling with L-[35S]methionine and immunoprecipitation. Peak labeling of gp 80 was reached in the endoplasmic reticulum 10 min after the pulse, in the Golgi apparatus 20 min later, and in the plasma membrane after 2 h; in the serum the specific radioactivity was steadily increasing during the experiment. Gp 80 of the endoplasmic reticulum was completely sensitive to endo-beta-N-glucosaminidase H (endo H), but simultaneously occurred in the Golgi apparatus in an endo H-sensitive and endo H-resistant form. The endo H-sensitive form was transported to the plasma membrane, the endo H-resistant species secreted into the serum. Conversion from the endo H-sensitive to the endo H-resistant form was completed within 10 min after transfer of gp 80 to the Golgi apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[Premedication with H1- and H2-receptor antagonists for intravenous urography using contrast media].

Intravenous urography using Telebrix was performed on 500 patients. Two hundred patients (group I) received no pre-medication; 300 patients (group II) were premedicated with H1 and H2 receptor antagonists. All patients were examined for signs of contrast reactions, blood pressure, pulse rate and plasma histamine levels. These were measured before and three minutes after the administration of the antihistamine substances and/or the contrast medium, and also at the end of the examination. Following the administration of H1 and H2 receptor antagonists, a slight, transient and insignificant rise in plasma histamine could be demonstrated. Both groups showed a significant rise in plasma histamine levels after the injection of the contrast medium. Although the pre-medicated group contained a higher percentage of high risk patients, there were significantly fewer patients with contrast reactions. Pre-medication with H1 and H2 receptor antagonists in high risk patients is therefore advisable.

Adult↗
PubMed1986

Effect of chloroquine on the degradation of L-fucose and the polypeptide moiety of plasma membrane glycoproteins.

To evaluate the role of lysosomes in the breakdown of the carbohydrate and the polypeptide moiety of plasma membrane glycoproteins, degradation of the plasma membrane glycoprotein gp120 was studied in the liver of rats treated with the lysosomotropic amine chloroquine. Half-lives of degradation of the terminal sugar L-fucose and of L-methionine of gp120 were measured in isolated plasma membranes after pulse-chase experiments in vivo. Chloroquine extended the plasma membrane half-life of the polypeptide moiety of gp120 from 51 h to 143 h. By contrast, L-fucose of gp120 in the plasma membrane was not affected by chloroquine, but decayed with the same short half-lives of 22 h and 23 h in both controls and chloroquine-treated rats. The data suggest that the protein portion of gp120 is degraded within the lysosomes. Conversely, the terminal sugar L-fucose is removed from the glycoprotein independent from proteolysis before segregation of the glycoprotein into the lysosomal compartment.

Animals↗
PubMed1985

Biopsy-coagulation forceps to simplify biopsy of the bladder.

Until now the forceps used for biopsy of the bladder has required a second procedure to coagulate the bleeding resulting from tissue removal. A new biopsy forceps is described, which makes it possible to perform the biopsy and coagulation simultaneously, thus, eliminating the inconvenience of having to change instruments during the operation. The shaft of the forceps through which the high frequency current flows is insulated completely so that the current exits only via the tips of the prongs. This design eliminates the danger of the specimen being subjected to thermal damage. The advantages offered by the new forceps are vision remains good, orientation is facilitated, loss of blood is minimal, operation time is reduced and the necessity of changing instruments is eliminated.

Biopsy↗
PubMed1985

[Therapeutic and ethical problems of nephrostomy in tumor-related hydronephrosis].

A total of 101 patients with hydronephrosis due to tumor obstruction underwent palliative nephrostomies. The average survival was 8.6 months; after 3 months, 32% of the patients were dead. The survival for patients with T3 tumors was 9.3 and for patients with T4 tumors, 6.0 months. The general postoperative health status did not improve in any of the cases. Retrospectively, 42% of the patients did not feel that the nephrostomy had done any good. In 17% of the cases, progressive development of tumor growth was predictable at the time of nephrostomy.

Adult↗
PubMed1985

[Seminal duct malformations: clinical picture, diagnosis and therapy].

Seminal duct abnormalities occur more often than generally assumed. In most cases, they remain undetected if diagnostic measures are not undertaken because of infertility or recurrent urinary tract infections. An IVP should be performed if aplasia of the vas is detected, since ipsilateral agenesis of the kidney may also be present. In spite of the improved techniques available today, reconstructive surgery on seminal duct abnormalities usually yields poor results.

Humans↗
PubMed1984

[Histamine in the urogenital tract].

Tissue histamine determination in the urogenital tract showed that there are significant differences concerning tissue histamine content between intraoperative and postmortem tissue samples. The difference appeared to be most significant in the case of renal pelvis samples, where the decrease was about 90% in the autopsie material compared to intraoperative tissues. In comparing tissue histamine content in special organs of different animal species we discovered considerable differences; e.g. in the ureter of the dog we measured 30 micrograms/g tissue - where as against the values in man amounted to only 6 micrograms/g tissue. The physiological meaning of the different tissue histamine levels is unknown.

Animals↗
PubMed1983

Intramolecular heterogeneity of degradation in plasma membrane glycoproteins: evidence for a general characteristic.

Five integral plasma membrane glycoproteins (60, 80, 120, 140, and 160 kilodaltons) were isolated to homogeneity from rat liver by a four-step procedure: (i) extraction of plasma membranes with lithium diiodosalicylate, (ii) solubilization of glycoproteins with Nonidet P-40, (iii) affinity chromatography on concanavalin A-Sepharose, and (iv) semipreparative NaDodSO4/polyacrylamide gel electrophoresis. The glycoproteins contained 48.5--51.5% hydrophobic amino acids. Carbohydrate moieties contained N-acetyl-D-glucosamine, D-mannose, D-galactose, L-fucose, and N-acetylneuraminic acid. N-Acetyl-D-galactosamine was not detectable. Half-lives of degradation of the carbohydrate and protein moieties of the five glycoproteins were measured by pulse-chase experiments in vivo. Protein moieties had half-lives ranging from 52 to 88 hr in the five glycoproteins, with a mean of 73 +/- 15 hr. Terminal sugars, L-fucose, and N-acetylneuraminic acid had significantly shorter half-lives, averaging 18 +/- 2 hr and 29 +/- 3 hr, respectively. The half-life of D-mannose varied between that of the terminal sugars and that of the protein moiety, depending on the type of the glycoprotein. The data show that the carbohydrate moieties are degraded faster than the protein portion of the glycoproteins. As this finding was obtained in each of the five glycoproteins, intramolecular heterogeneity of breakdown may be a general characteristic of plasma membrane glycoproteins in liver.

Amino Acids↗