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Biomedical subjects

W Haase

Publications and source records attributed to W Haase.

At least 73 records · Page 4Linked to original sources
PubMed1995

High level production and localization of bovine rod cGMP-gated cation channel subunit 1 in baculovirus-infected insect cells and Saccharomyces cerevisiae.

The cGMP-gated cation channel is responsible for the last step in the vertebrate phototransduction cascade which couples light activation of rhodopsin to a change in membrane permeability. Two different expression systems, baculovirus-infected Spodoptera frugiperda (Sf9) insect cells and Saccharomyces cerevisiae, were used for the overproduction of the cGMP-gated cation channel subunit 1 of bovine rod cells. Presence of recombinant channel protein was monitored by SDS-PAGE and Western-blot analysis. Through immunogold labeling, the heterologously expressed cation channel was found to be localized predominantly in the inner compartments of the infected insect cells and in the vacuole of recombinant yeast cells.

Animals↗
PubMed1995

Isolation and structural characterization of trimeric cyanobacterial photosystem I complex with the help of recombinant antibody fragments.

A monoclonal antibody was derived from mice immunized with the native trimeric, photosystem I (PSI) complex from the cyanobacterium Synechococcus PCC 7002 which reacts with a conformational epitope of the PSI complex. As seen by immunoelectron microscopy, the mAb bound to the stromal side of the thylakoid membranes. The DNA sequence encoding variable regions of the mAb was cloned into recombinant plasmids, sequenced and expressed in Escherichia coli. ELISA, Western blots and immunoelectron microscopy provided evidence that the expressed paired variable domain (Fv) fragments bind to the antigen in the same way as the parent mAb. A one-step purification was applied to purify the trimeric PSI complex using an affinity tag attached to the Fv fragment. Analysis by gel electrophoresis and N-terminal sequencing revealed the presence of the psaA, psaB, psaC, psaD, psaE, psaF and psaL gene products. The antenna size of the isolated PSI/Fv was 139 +/- 9 chlorophyll a/primary electron donor. Flash-induced absorption-change measurements showed that the complex exhibited electron transfer from the primary electron donor, P700, to the Fe-S center, FA/FB. The position of the bound Fv fragment on the trimeric PSI surface was determined by high-resolution electron microscopy and digital image processing.

Amino Acid Sequence↗
PubMed1995

Immunoelectron microscopy and epitope mapping with monoclonal antibodies suggest the existence of an additional N-terminal transmembrane helix in the cytochrome b subunit of bacterial ubiquinol:cytochrome-c oxidoreductases.

The topology of the ubiquinol:cytochrome-c oxidoreductase (cytochrome bc1 complex) from Paracoccus denitrificans was investigated by immunoelectron microscopy with sequence-specific murine monoclonal antibodies. Epitope mapping with synthetic peptides and enzymic proteolytic cleavage of the cytochrome bc1 complex were employed to localize precisely the respective antibody epitopes on the subunits of this membrane protein complex. Localization of defined epitopes on the cytochrome bc1 complex by immunoelectron microscopy clearly demonstrates that the N-terminus of the cytochrome b subunit is exposed to the periplasmic space. This finding is in agreement with a nine-transmembrane-helices topology model (I-IX) as predicted before for cytochrome b. However, due to other published evidence we favour the existence of an additional transmembrane helix (helix 0) complementing a more recently published eight-helices model (A-C,cd, D-H), at least for prokaryotes.

Amino Acid Sequence↗
PubMed1995

Characterization of the rat m3 muscarinic acetylcholine receptor produced in insect cells infected with recombinant baculovirus.

The m3 muscarinic acetylcholine receptor from rat heterologously produced in insect cells after infection with a recombinant baculovirus has an apparent molecular mass of approximately 75 kDa. Polyclonal antibodies raised against a carboxy-terminal nonapeptide that is unique to the m3 subtype can detect the receptors produced in the insect cells by Western blot and can also immunoprecipitate solubilized receptor. Immunofluorescence microscopy as well as electron microscopy revealed that the receptor was located intracellularly, visualized as a ring around the nucleus of the infected insect cells. Solubilization of the receptor was accomplished with digitonin which was added in increments (over 10 min) to a final concentration of 0.8% (mass/vol). The solubilized receptor is unstable when the ligand-binding site is not protected by a ligand. Here the low-affinity ligand propylbenzilylcholine (approximately 10 nM) has demonstrable protective ability during solubilization, but the usefulness of this ligand is limited by a very slow off rate. From the behaviour of the solubilized receptor during DEAE-Sephacel chromatography and lectin-affinity chromatography it can be deduced that the receptor produced in insect cells is heterogeneously glycosylated in the producing insect cells.

Affinity Labels↗
PubMed1995

Use of antibody fragments (Fv) in immunocytochemistry.

We developed a novel antibody fragment (Fv) technique for localization and determination of the surface topology of membrane protein complexes by immunogold electron microscopy. Several hybridoma cell lines producing murine monoclonal antibodies (MAbs) raised against bacterial membrane proteins were established. The cDNAs coding for the variable domains of the MAbs were cloned and expressed in Escherichia coli. The engineered Fv fragments served as trifunctional adapter molecules. The Fv fragment binds to the epitope of the membrane protein. The Strep tag fused to the VH chain was used for one-step affinity purification of the Fv fragments. Immunological detection of the membrane protein-bound Fv fragments in electron microscopy was accomplished either via the Strep tag with colloidal gold-labeled streptavidin or via the c-myc tag, which was fused to the VL chain, in combination with the c-myc tag-specific antibody 9E10 and a colloidal gold-labeled secondary antibody. We examined four Fv fragments directed against the cytochrome c oxidase or the ubiquinol-cytochrome c oxidoreductase of Paracoccus denitrificans and bacteriorhodopsin of Halobacterium halobium to show that this method is generally applicable. In all cases the Fv fragments showed the same results as their corresponding parent antibodies in electron microscopic immunostaining and other applications.

Antibodies, Monoclonal↗
PubMed1995

A dose comparison study of didanosine in patients with very advanced HIV infection who are intolerant to or clinically deteriorate on zidovudine. German ddI Trial Group.

OBJECTIVE: Zidovudine (ZDV) is the only antiretroviral drug which has been shown to reduce mortality in patients with symptomatic HIV disease, but its use is restricted by intolerance in a significant proportion of patients. Additionally, the efficacy of ZDV therapy appears to decrease after prolonged treatment particularly in the advanced stage of HIV disease. Therefore, alternative antiretroviral regimens for patients are needed. In this study, didanosine (ddI; 2',3'-dideoxyinosine), another HIV reverse transcriptase inhibitor, was evaluated. DESIGN: A total of 426 patients with AIDS or AIDS-related complex (ARC) who were intolerant to or clinically progressing on ZDV therapy and who had CD4+ cell counts < or = 150 x 10(6)/l were randomized to receive either a high (750 mg for bodyweight > or = 60 kg or 500 mg for bodyweight < 60 kg) or a low (200 mg and 134 mg, respectively) dose of ddI daily. SETTING: The patients were recruited from 31 German and Austrian AIDS clinical primary-care centres. RESULTS: The study was stopped after the second interim analysis due to a statistically significant difference in the incidence of pancreatitis (nine versus 26; relative risk, 2.92; P = 0.003) and neuropathy (28 versus 43; relative risk, 1.55; P = 0.05) in favour of the low dose. There was no difference between the low and high dosage groups in survival rate at 6 (80 versus 80%) and 12 months (61 versus 65%), number of deaths [82 (43.6 per 100 patient-years) versus 84 (44.4 per 100 patient-years)], progression from ARC to AIDS or to AIDS or death, or average number of new/recurrent opportunistic infections (2.8 versus 3.0 per patient). CONCLUSIONS: This study cannot conclude on ddI efficacy but it shows that in patients with advanced HIV disease for whom no alternative antiretroviral therapy is available and ddI therapy is considered, daily doses < 750 mg should be administered.

AIDS-Related Complex↗
PubMed1994

Heterologous expression of the human D2S dopamine receptor in protease-deficient Saccharomyces cerevisiae strains.

The cDNA for the human D2S dopamine receptor has been functionally expressed in the unicellular yeast Saccharomyces cerevisiae. The original D2S gene and an elongated D2S gene with an N-terminal fusion to the first 24 amino acids of the STE2 gene from S. cerevisiae were introduced into the episomal yeast expression vector YEp51 under the control of the GAL10 promoter. Expression studies performed in a wild-type strain and in two protease-deficient strains of S. cerevisiae revealed that the receptor was functionally expressed with respect to its ligand-binding properties. The KD values for the binding of the dopamine antagonist [3H]spiperone were calculated to be 1.6 nM for the D2S receptor alone and 1.9 nM for the STE2-D2S chimaera. Both membrane proteins could be further characterized by ligand-displacement studies using certain dopamine agonists and antagonists. D2S dopamine-receptor-specific polyclonal antibodies were used to monitor the heterologous expression of the receptor. Western-blot analysis of membranes prepared from transformed yeast cells producing either the receptor protein alone or the receptor fusion protein revealed apparent molecular masses of 40 kDa (D2S receptor alone) and 42 kDa (STE2/D2S receptor fusion protein). It could be shown that, in comparison to the expression in a wild-type S. cerevisiae strain, the amount of receptor degradation was drastically reduced in the protease-deficient strains. The localizations of the heterologously produced dopamine receptor and of the chimaera in the recombinant yeast were studied by immunogold electron microscopy and were found to be restricted mainly to the vacuole of the cells.

Base Sequence↗
PubMed1994

Ca2+ influx through stretch-activated cation channels activates maxi K+ channels in porcine endocardial endothelium.

The endocardial endothelium is an important modulator of myocardial function. The present study demonstrates the existence of a stretch-activated Ca(2+)-permeable cation channel and of a Ca(2+)-activated K+ channel in the endocardial endothelium of the porcine right atrium. The stretch-activated channel is permeable for K+, Na+, Ca2+, and Ba2+, with mean conductances of approximately 32 pS for the monovalent cations and approximately 13 pS for divalent cations. The Ca(2+)-activated K+ channel has a mean conductance of 192 pS in symmetrical KCl. solution. Channel activity is strongly dependent on membrane potential and the cytosolic Ca2+ concentration. Half-maximal activation occurs at a cytosolic Ca2+ concentration of approximately 5 microM. The influx of Ca2+ through the stretch-activated channel is sufficient to activate the Ca(2+)-activated K+ channel in cell-attached patches. Upon activation of the stretch-activated channel, the cytosolic Ca2+ concentration increases, at least locally, to values of approximately 0.5 microM, as deduced from the open probability of the Ca(2+)-dependent K+ channel that was activated simultaneously. The stretch-activated channels are capable of inducing an intracellular Ca2+ signal and may have a role as mechanosensors in the atrial endothelium, possibly activated by atrial overload.

Animals↗
PubMed1994

Glucosamine sulfate compared to ibuprofen in osteoarthritis of the knee.

Glucosamine sulfate is able to stimulate proteoglycan synthesis by chondrocytes and has mild anti-inflammatory properties. In clinical trials, glucosamine sulfate was more effective than placebo in controlling the symptoms of osteoarthritis (OA). In order to better characterize this therapeutic activity, we conducted a randomized, double-blind, parallel-group study of glucosamine sulfate 500 mg t.i.d. vs ibuprofen 400 mg t.i.d., orally for 4 weeks. The study included 200 hospitalized patients with active OA of the knee, symptoms for at least 3 months and a Lequesne's index of at least 7 points. Patients were evaluated weekly. Response was defined as a reduction in the Lequesne's index by at least 2 points if the enrollment value was higher than 12 points, or by at least 1 point if the enrollment value was 12 or less points, together with a positive overall assessment by the investigator. The improvement tended to be sooner under ibuprofen (48% responders vs 28% after the 1st treatment week; P = 0.06, Fisher's Exact test), but there was no difference from the 2nd week onward, with a success rate of 52% in the ibuprofen group and of 48% in the glucosamine group (P = 0.67) at the end of treatment. The average Lequesne's index at enrollment was around 16 points and decreased by over 6 points in both groups, again with the above described trend. On the other hand, 35% of patients on ibuprofen reported adverse events, mainly of gastrointestinal origin, vs 6% adverse events with glucosamine (P < 0.001, Fisher's Exact test). The number of adverse event related drop-outs was different between the two groups (7% vs 1%, respectively; P = 0.035). Glucosamine sulfate was therefore as effective as ibuprofen on symptoms of knee OA. These data confirm glucosamine sulfate as a safe symptomatic Slow Acting Drug for OA.

Administration, Oral↗
PubMed1994

Efficacy and tolerability of amitriptylinoxide in the treatment of chronic tension-type headache: a multi-centre controlled study.

Amitriptyline is the medication of first choice in the treatment of chronic tension-type headache. In 197 patients with chronic tension-type headache (87M and 110F with a mean age of 38 +/- 13 (18-68)) efficacy and tolerability of 60-90 mg amitriptylinoxide (AO) were compared with 50-75 mg amitriptyline (AM) and placebo (PL) in a double-blind, parallel-group trial consisting of a four weeks' baseline phase and 12 weeks of treatment. The primary study endpoint was a reduction of at least 50% of the product of headache duration and frequency and a reduction of at least 50% in headache intensity. Statistics used were Fisher's exact test and analysis of variance. No significant difference emerged between AO, AM and PL with respect to the primary study endpoint. Treatment response occurred in 30.3% of the AO, 22.4% of the AM and 21.9% of the PL group. A reduction in headache duration and frequency of at least 50% was found in 39.4% on AO, in 25.4% on AM and in 26.6% on PL (PAO-PL = .1384, PAM-PL = 1.000, PAO-AM = .0973). A reduction in headache intensity of at least 50% was found in 31.8% on AO, in 26.9% on AM and in 26.6% on PL (PAO-PL = .5657, PAM-PL = 1.000, PAO-AM = .5715). Trend analysis with respect to a significant reduction of headache intensity (p < 0.05) and the product of headache duration and frequency revealed a superior effect of AO.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Zopiclone improves sleep quality and daytime well-being in insomniac patients: comparison with triazolam, flunitrazepam and placebo.

In a randomized, double-blind, parallel group study in private practice, zopiclone given for 28 days was compared with flunitrazepam, triazolam and placebo in its effect on quality of sleep and daytime well-being in 1507 patients suffering from insomnia. For quantitative assessment, patients were defined as responders according to either a shortening of sleep latency by at least 15 min, or prolongation of total sleep time by at least 20%, or reduction of the number of nocturnal awakenings to three or less and a fresh feeling in the morning, as well as lack of impairment in daytime well-being as a result of tiredness or anxiety. The responder rate tended to be higher with zopiclone (37.4%) than with flunitrazepam (30%) and triazolam (32.2%) and was significantly greater (p = 0.0017) than with placebo (26.8%). Daytime well-being was particularly responsive to zopiclone and most responsive in severe insomniacs. With the exception of those to triazolam, rates of response were most pronounced in patients with insomnia of a short duration (< or = 1 year) than in those with insomnia of a longer duration (> or = 1 year). Following discontinuation of treatment, all groups showed a moderate reduction in therapeutic effect, but no rebound insomnia occurred.

Azabicyclo Compounds↗
PubMed1994

[Refraction in childhood as a risk factor for the development of amblyopia and/or strabismus. Recording a round table discussion at the 89th Congress of the German Society of Ophthalmology 25 September 1991 in Leipzig].

The members of the panel refer to the recent literature. As has been shown by several groups of authors (Atkinson et al., Abrahamsson et al., Ingram et al.) hypermetropia of 3 diopters or more as well as astigmatism of 1 or more dpt at the age of 12 months, especially oblique astigmatism, increase the rate of amblyopia/strabism until the age of 4 years. The risk rises too, if the refractive error deteriorates. The authors conclude that the prescription of glasses in non-squinters should be based on these new findings.

Amblyopia↗
PubMed1994

[Pseudo-esotropia caused by nasal dislocation of the macula in patients with high infantile myopia].

Pseudostrabismus due to dislocation of the macula is a well-known clinical entity mostly reported in the outward, upward and downward directions. This heterotopia is thought to be caused by changes in the growth rate in different areas of the retina or mechanically by retinal traction due to abortive ROP, vascular abnormalities, chorioiditis or other peripheral retinal disorders. In this paper we demonstrate four cases of macular dislocation in the direction of the optic disc associated with high myopia in infants and toddlers without signs of other retinal abnormalities. These children had myopia had myopia ranging from -17 to -20 D and esotropia superimposed by pseudostrabismus. In all four cases, strabismus surgery was performed. Postoperatively, these children showed signs of some binocular interaction. This case report may indicate that in children with strabismus associated with high myopia macular dislocation should be considered as a further characteristic affecting diagnosis and therapy.

Child↗
PubMed1993

Cloning of a membrane-associated protein which modifies activity and properties of the Na(+)-D-glucose cotransporter.

An expression library from porcine kidney cortex was screened with a monoclonal antibody (R4A6) which stimulates high-affinity phlorizin binding in kidney and intestine but does not react with the membrane protein (SGLT1) which mediates Na(+)-coupled transport of D-glucose (Hediger, M.A., Coady, M.J., Ikeda, T.S., and Wright, E.M. (1987) Nature 330, 379-381). A cDNA (RS1) was obtained which codes for a hydrophilic M(r) 66,832 polypeptide and contains a predicted hydrophobic alpha-helix at the COOH terminus. After expression in Xenopus oocytes RS1 protein was found associated with the plasma membrane. RS1-homologous mRNAs were detected in renal outer cortex and outer medulla, small intestine, liver, and LLCPK1 cells, but not in skeletal muscle, heart muscle, Madin-Darby canine kidney (MDCK) cells, renal inner medulla, and Xenopus oocytes. After nondenaturing gel electrophoresis of renal brush-border membranes comigration of RS1- and SGLT1-homologous proteins as a high molecular weight complex was demonstrated. RS1 altered the expression of Na(+)-glucose cotransport by SGLT1 in Xenopus oocytes. There was no effect on the expression of the nonhomologous transporters for Na(+)-gamma-aminobutyric acid cotransport and for Na(+)-independent glucose transport. However, RS1 also changed the expression of the SGLT1-homologous Na(+)-myo-inositol cotransporter from MDCK cells. The Vmax of methyl-alpha-D-glucopyranoside (AMG) transport expressed after injection of a small amount of SGLT1-cRNA was increased 40-fold when a stoichiometric amount of RS1-cRNA was coinjected. In addition the voltage and glucose dependence of expressed AMG uptake and the concentration dependence of transport inhibition by phlorizin were changed when stoichiometric amounts of RS1-cRNA were coinjected with SGLT1-cRNA. Thus with SGLT1 one apparent transport site (K0.5 about 100 microM) and one apparent phlorizin inhibition site (Ki about 5 microM) was observed whereas with SGLT1 plus RS1 two apparent transport sites (K0.5(1) about 20 microM, K0.5(2) about 1 mM) and two apparent phlorizin inhibition sites (Ki(1) about 0.3 microM, Ki(2) about 30 microM) were found as has been described in brush-border membrane vesicles of kidney and intestine (see e.g. Koepsell, H., Fritzsch, G., Korn, K., and Madrala, A. (1990) J. Membr. Biol. 114, 113-132). The data suggest that the Na(+)-D-glucose cotransporter and possibly also other SGLT1-type Na(+)-cotransporters contain RS1-type regulatory subunits.

Amino Acid Sequence↗
PubMed1993

Stable expression of gp80 (TRPM-2, clusterin), a secretory protein implicated in programmed cell death, in transfected BHK-21 cells.

The gp80 (TRPM-2, clusterin) cDNA cloned into an eucaryotic expression vector, was transfected into BHK-21 cells and stably transformed cell clones were obtained. Analysis of the gp80 glycoprotein complex produced in these cells demonstrated that the complex was glycosylated, proteolytically processed and secreted in a way similar to the gp80 glycoprotein complex expressed from the endogenous gene in MDCK cells. The analysis of the viability of the cells, the morphology and the state of the DNA in the transfected cells was unchanged when compared with the untransformed cells, demonstrating that the expression of the protein failed to elicit any signs of apoptosis in this system.

Animals↗
PubMed1993

Renal and central vasopressin receptors: immunocytochemical localization.

Employing an anti-vasopressin monoclonal antibody for immunization, anti-idiotypic monoclonal antibodies were obtained which induced plasminogen activator production in the renal epithelial cell line LLC-PK1. The anti-idiotypic antibodies were employed to visualize vasopressin receptors on LLC-PK1 and A7r5 smooth muscle cells by immunofluorescence. All results indicated specificity of the anti-idiotypes for both V1 and V2 vasopressin receptor subtypes. These antibodies were used for immunohistochemical localization of vasopressin receptors in rat and bovine kidney preparations. In accordance with earlier physiological and biochemical observations, vasopressin receptors were detected predominantly in collecting ducts in cortex and medulla. On the cellular level, a differential staining pattern was observed. On rat brain tissue sections, dense staining was observed within various circumventricular organs. The staining pattern corresponded to that obtained in autoradiographic studies with labeled AVP(4-9) fragment peptide and differed from the distribution of binding sites for labeled vasopressin or V1 antagonists.

Animals↗