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Biomedical subjects

F Pfeiffer

Publications and source records attributed to F Pfeiffer.

15 recordsLinked to original sources
PubMed1989

[Hemodynamic study of the development of tolerance in intravenous nitrate therapy].

UNLABELLED: To investigate possible tolerance development under an intravenous treatment with nitrates, 22 patients with coronary artery disease were randomly assigned to receive either 4 mg/h of ISDN (n = 12) or placebo (n = 10) and were given additional 10 mg of ISDN or placebo after 23 h. Pulmonary artery pressures (PAP), cardiac output, and heart rate were registered before, and 4 h, 22.5 h, and 24 h after the beginning of treatment. At baseline both groups were similar with regard to pulmonary artery diastolic pressure (PADP) at rest and at comparable work load. Each patient of the placebo group showed identical PAPs at work. ISDN led to a 42-59% decrease of PADP at rest and 29-37% decrease at comparable work load. After 22.5 h a statistically insignificant reduction of ISDN effect was observed which could be reversed by additional ISDN p.o. A detailed analysis of the ISDN group showed seven patients with a persistently lowered PADP, (table; see text) whereas five patients demonstrated a partial diminuation of the ISDN effect. No patient showed a complete tolerance. In the placebo group blood pressure did not show any change during the treatment period (143 +/- 21/84 +/- 10 mmHg vs 137 +/- 17/79 +/- 10 mmHg), whereas ISDN infusion resulted in a continuously lowered blood pressure (150 +/- 22/83 +/- 11 mmHg vs 125 +/- 15/72 +/- 9 mmHg (p less than 0.001). Cardiac output and heart rate were similar under ISDN and placebo treatment. CONCLUSION: Continuous infusion of 4 mg of ISDN/h over 24 h and an additional dose of 10 mg of ISDN after 23 h provided a significant reduction in PADP, blood pressure and rate pressure product over 24 h at rest and during exercise.

Administration, Oral↗
PubMed1989

[Sarcoma of the uterus. A clinical study apropos of 50 surgically treated cases at the Gustave Roussy Institute. Review of the literature].

From 1970 to 1987 fifty patients with uterine sarcoma who have been operated at the G. Roussy Institute (IGR) were studied. The histological material was reviewed according to the W.H.O. classification and the Hendrickson and Kempson's criteria. Staging was done on surgical and histological findings according to the pTNM classification of the UICC for endometrial carcinoma. There were 22 cases of heterologous malignant mixed müllerian tumor (MMT), 5 cases of homologous MMT, 20 cases of leiomyosarcoma (LS), 1 high grade stromal sarcoma, 1 low grade stromal sarcoma (stromal myosis (SM], 1 adenosarcoma. There were 22 cases of stage T1 T2, 23 cases of stage T3 T4 and 5 TX (first surgery outside IGR). Total hysterectomy with bilateral salpingo-oophorectomy was performed in 86% of the cases. Radiation therapy was performed in 26 cases mostly external pelvic irradiation associated with endobrachytherapy. "Cyvadic" combination chemotherapy was used in 16 cases associated with platinum in few cases. There were 2 postoperative deaths, 11 cases of progression and 37 cases of complete remission (CR). Of the 37 cases of CR, 10 patients are alive with NED 6 months to 10 years after diagnosis in 2 cases of MMT. 27 patients presented recurrence or metastasis. Of the 22 patients with pelvi-abdominal recurrence, 10 had debulking surgery (one total pelvic exenteration (PE), three posterior PE). Among them five are alive 14 to 78 months later (3 LS, 1 AS, 1 SM). Thirty percent of the patients developed lung metastasis. The overall five-year survival was 42 +/- 16% (28 patients) (Kaplan-Meier's method), similar to literature data.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

VecBase, a cloning vector sequence data base.

VecBase, release 2, contains the sequences of 98 cloning vectors in 105 entries. Further additions are made continuously, and VecBase is intended to develop into a central repository for cloning vector sequences. However, as cloning vector sequences are commonly not determined by experiment, but are assembled from the sequences of the parent molecules according to the cloning strategy, they have to be used with extreme caution. To address this problem, VecBase contains an extensive documentation with special emphasis on crossreferences to "parent" sequences and indication of sequence discrepancies. Parent sequences are either themselves cloning vectors present in VecBase, or sequences from one of the major DNA sequence databases. VecBase contains both strands of pUC cloning vectors, because the published sequence displays the polylinker region in its reverse orientation. VecBase is distributed in the standardized format for sequence data exchange. An additional small database called VecSource contains ancillary sequences present in cloning vectors, e.g., polylinkers or promoters.

Bacteriophages↗
PubMed1985

Purification and characterization of the glycine receptor of pig spinal cord.

A large-scale purification procedure was developed to isolate the glycine receptor of pig spinal cord by affinity chromatography on aminostrychnine agarose. After an overall purification of about 10 000-fold, the glycine receptor preparations contained three major polypeptides of Mr 48 000, 58 000, and 93 000. Photoaffinity labeling with [3H]strychnine showed that the [3H]strychnine binding site is associated with the Mr 48 000 and, to a much lesser extent, the Mr 58 000 polypeptides. [3H]Strychnine binding to the purified receptor exhibited a dissociation constant KD of 13.8 nM and was inhibited by the agonists glycine, taurine, and beta-alanine. Gel filtration and sucrose gradient centrifugation gave a Stokes radius of 7.1 nm and an apparent sedimentation coefficient of 9.6 S. Peptide mapping of the [3H]strychnine-labeled Mr 48 000 polypeptides of purified pig and rat glycine receptor preparations showed that the strychnine binding region of this receptor subunit is highly conserved between these species. Also, three out of six monoclonal antibodies against the glycine receptor of rat spinal cord significantly cross-reacted with their corresponding polypeptides of the pig glycine receptor. These results show that the glycine receptor of pig spinal cord is very similar to the well-characterized rat receptor protein and can be purified in quantities sufficient for protein chemical analysis.

Animals↗
PubMed1985

Distribution of glycine receptors at central synapses: an immunoelectron microscopy study.

The distribution of receptors for a neurotransmitter was investigated cytochemically for the first time in the central nervous system, at synapses established on cells of the ventral horn of the rat cervical spinal cord. Three monoclonal antibodies (mAb's) raised against glycine receptors were used. Immunofluorescent staining already showed discontinuous labeling at the surface of neurons, and immunoenzymatic electron microscopy further revealed that the antigenic determinants were confined to the postsynaptic membrane and concentrated at the level of the synaptic complex. More specifically, one mAb directed against the receptive subunit of the oligomeric receptor recognized an epitope on the extracellular side of the plasma membrane, whereas two other mAb's bound to the cytoplasmic face. Epitopes for the last two mAb's were more accurately localized with protein A-colloidal gold, using an intermediate rabbit anti-mouse immunoglobulin serum. (a) In addition to the presence of gold particles in areas facing the presynaptic active zone (visualized with ethanolic phosphotungstic acid), the labeling extended beyond this zone for approximately 50-60 nm, which corresponds to the width of one presynaptic dense projection. (b) The distances between the mid membrane and the gold particles were different for the two mAb's (with means of 21.7 +/- 8.5 nm and 29.8 +/- 10.4 nm, respectively). The data suggest that one of the recognized epitopes is close to the plasma membrane, whereas the second protrudes into the cytoplasm. Our results indicate that the receptor is a transmembrane protein which has a restricted spatial distribution on the postsynaptic neuronal surface.

Animals↗
PubMed1984

Monoclonal antibodies and peptide mapping reveal structural similarities between the subunits of the glycine receptor of rat spinal cord.

The glycine receptor of rat spinal cord is an oligomeric membrane glycoprotein of molecular mass 250,000 daltons that contains three polypeptides of 48,000, 58,000, and 93,000 daltons. Monoclonal antibodies (mAbs) were prepared against the affinity-purified glycine receptor protein by using 125I-labeled receptor preparations for the detection of positive hybrids. From nine monoclonal antibodies obtained, six recognized denatured receptor polypeptides blotted to nitrocellulose paper. Two of these antibodies bound to more than one glycine receptor polypeptide: mAb GlyR 4a stained the 48,000- and 58,000-dalton polypeptides, and mAb GlyR 7a stained the 48,000- and 93,000-dalton polypeptides. Common antigenic determinants thus are shared by the different subunits of the glycine receptor. Complementary results were obtained by peptide mapping of 125I-labeled glycine receptor polypeptides with various proteases. A set of peptide fragments of the same apparent molecular mass was produced from the different glycine receptor polypeptides by using V8 protease, chymotrypsin, and elastase. These data suggest that the subunits of the glycine receptor have significant homology within their primary structure and may have evolved from a common ancestor receptor polypeptide.

Amino Acid Sequence↗
PubMed1984

Monoclonal antibodies against the alpha-bungarotoxin-binding protein of chick optic lobe.

The nicotinic acetylcholine (ACh) receptor probe alpha-bungarotoxin (alpha-Butx) binds with high affinity to a membrane protein of the vertebrate central nervous system. To characterize further this putative neuronal ACh receptor, we have prepared monoclonal antibodies (mAbs) against the alpha-Butx-binding protein of chick optic lobe. Mice were immunized with affinity-purified protein preparations which were estimated to be 10 to 20% pure. Spleen cells from an immunized mouse were fused with the mouse myeloma cell line X63-Ag 8.653. From this fusion, 14 stable hybridoma lines were isolated which produce mAbs against the chick neuronal alpha-Butx-binding protein. Most of the antibodies inhibited alpha-Butx-binding to membrane fractions and/or detergent extracts of chick optic lobe. Some of the mAbs cross-reacted with the alpha-Butx-binding protein of the rat pheochromocytoma cell line PC12. However, none of the mAbs bound to a significant extent to the nicotinic ACh receptor of chick skeletal muscle or of Torpedo californica electric organ. All antibodies specifically isolated a polypeptide of Mr = 57,000 (+/- 2,000) from radiolabeled neuronal protein preparations. The present data show that these mAbs constitute useful tools for the further molecular and functional characterization of the neuronal alpha-Butx-binding protein.

Animals↗
PubMed1983

Photoaffinity-labelling of the glycine receptor of rat spinal cord.

The irreversible incorporation upon ultraviolet illumination of the glycine receptor antagonist, [3H]strychnine, into synaptic membrane fractions of rat spinal cord has been investigated. The specificity of this photoaffinity-labelling reaction for the glycine receptor was demonstrated by the following results: (a) the Kd value (9.7 nM) of the glycine-displaceable irreversible incorporation of [3H]strychnine was similar to the previously reported Kd of [3H]strychnine binding to the glycine receptor; (b) pre-illumination of the membranes with unlabelled strychnine led to a corresponding reduction in the number, but not the affinity, of reversible glycine-displaceable [3H]strychnine binding sites; (c) the ultraviolet light-induced incorporation into the membranes of [3H]strychnine was inhibited by different glycine receptor agonists; other neurotransmitter substances had little or no effect. Also, [3H]strychnine alone was shown to be stable upon illumination with ultraviolet light; this suggests that photocrosslinking of [3H]strychnine may require energy transfer from specific groups of its high-affinity receptor binding site. Upon sodium dodecyl sulphate/polyacrylamide gel electrophoresis a single labelled polypeptide with a relative molecular mass of 48000 was revealed from spinal cord membranes photoaffinity-labelled with [3H]strychnine. Spinal cord membranes photoaffinity-labelled with the gamma-aminobutyric acid receptor ligand [3H]flunitrazepam, however, gave a single polypeptide with a relative molecular mass of 5- 0000. Treatment of membranes, labelled with [3H]strychnine, by endoglycosidase H did not alter the relative molecular mass of the 48000-Mr labelled polypeptide. Trypsin treatment, on the other hand, successively produced major fragments of relative molecular masses of 42000 and 37000. Also, even after extensive treatment with trypsin or chymotrypsin, greater than or equal to 90% of the radioactivity incorporated into the labelled membranes remained membrane-associated. It is concluded that the strychnine binding site of the glycine receptor is located on a protease-inaccessible, i.e. probably hydrophobic domain of the 48000-Mr subunit.

Affinity Labels↗
PubMed1982

Purification by affinity chromatography of the glycine receptor of rat spinal cord.

The glycine receptor of rat spinal cord was solubilized with the nonionic detergent Triton X-100 and subsequently purified by affinity chromatography on aminostrychnine-agarose and wheat germ agglutinin-Sepharose. An overall purification of 1950-fold was achieved. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and mercaptoethanol revealed three glycine receptor-associated polypeptides of Mr = 48,000, 58,000, and 93,000. [3H]Strychnine was incorporated irreversibly into the Mr = 48,000 polypeptide upon UV-illumination. The dissociation constant (KD) of [3H]strychnine binding to the purified glycine receptor was 9.3 +/- 0.6 nM. The glycine receptor agonists glycine, beta-alanine, and taurine inhibited the binding of [3H]strychnine to the purified receptor. Gel filtration and sedimentation in sucrose/H2O and sucrose/D2O gradients gave a Stokes radius of 7.7 nm, a partial specific volume of 0.780 +/- 0.005 ml/g and a sedimentation coefficient s20,w of 8.2 +/- 0.2 S for the purified glycine receptor. From these data, a molecular weight of 246,000 +/- 6,000 was calculated for the glycine receptor protein.

Affinity Labels↗
PubMed1982

Avermectin B1a inhibits the binding of strychnine to the glycine receptor of rat spinal cord.

The anthelmintic drug, avermectin B1a, has been reported to interfere with gamma-aminobutyric acid-mediated chloride conductance. Also, enhancement of diazepam binding to mammalian brain membranes by avermectin B1a has led to the suggestion that avermectin B1a interacts with the 'benzodiazepine receptor-gamma-aminobutyric acid receptor-chloride ionophore' complex. Here we report an interaction of avermectin B1a with the glycine receptor. The binding of the glycine receptor antagonist, strychnine, to both membranes and solubilized receptor from rat spinal cord, was inhibited by avermectin B1a with Ki values of 1.3 microM and 3.6 microM, and Hill coefficients of 0.46 and 0.62, respectively.

Animals↗
PubMed1981

Solubilization of the glycine receptor from rat spinal cord.

Glycine receptors, as detected by glycine-displaceable [3H]strychnine binding, were solubilized from a membrane fraction of rat spinal cord by the non-ionic detergent Triton X-100. The solubilized material retained its high affinity for [3H]strychnine and exhibited the typical pharmacological properties of the membrane-bound glycine receptor. On sucrose density gradients, the solubilized receptor had a sedimentation coefficient of 8.3 +/- 0.4 S. Gel exclusion chromatography on Sepharose 6 B in the presence of phosphatidylcholine gave a Stokes radius of 7.3 +/- 0.3 nm.

Animals↗
PubMed1977

[Methodology of myocardial scintigraphy with thallium 201: limits of pathological findings].

Thallium 201 is a useful agent for demonstrating ischemic myocardia. It is injected during maximum stress, the stress situation is then continued for a further 2 min and a series of scans are carried out 5-25 min after injection. The series is repeated 3-5 h after injection, thereby obtaining pictures of myocardial resting and stress perfusion. Repitition of the study without stress reveals no further data. In follow-up examinations under the same stress situation the perfusion defects remain the same. 27 normal subjects were evaluated and the limits between normal and pathologic scans established.

Coronary Disease↗