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Biomedical subjects

M Brunner

Publications and source records attributed to M Brunner.

At least 19 recordsLinked to original sources
PubMed1992

Soluble N-ethylmaleimide-sensitive fusion attachment proteins (SNAPs) bind to a multi-SNAP receptor complex in Golgi membranes.

Soluble N-ethylmaleimide-sensitive fusion attachment proteins (SNAPs) are required for the binding of N-ethylmaleimide-sensitive fusion protein (NSF) to Golgi membranes and are, therefore, required for intra-Golgi transport. We report the existence of distinct alpha/beta-SNAP and gamma-SNAP-binding sites in Golgi membranes that appear to be part of the same receptor complex. Cross-linking studies with alpha-SNAP demonstrate that an integral membrane protein of between 30-40 kDa is the alpha-SNAP binding component of the multi-SNAP receptor complex. These data suggest that SNAPs function by independently binding to a multi-SNAP membrane-receptor complex, thereby activating them to serve as adaptors for the targeting of NSF.

Amino Acid Sequence↗
PubMed1992

Cellular changes in rat parathyroids provoked by progesterone and testosterone.

Male rats kept on a standard diet were treated either with progesterone or testosterone by a single intramuscular injection of preparations which are slowly absorbed and metabolized. The rats were anaesthetized 24 h after application of the hormones, perfused with glutaraldehyde, and the parathyroid glands prepared for electron microscopy. Morphometric analysis revealed that both progesterone and testosterone provoked (1) an increment in nuclear and cell volume and a concomitant increment in cell surface area, and (2) an increment in surface area of rough endoplasmic reticulum by 42% and 49%, and of the Golgi complex by 85% and 63%, respectively. Previously, we had found that oestradiol treatment led to a similar response in parathyroid cells. The conclusion is thus drawn that male and female sex hormones induce membrane synthesis resulting in an enhanced capacity for parathyroid hormone secretion since RER and Golgi complex are concerned with this secretion. It is considered probable that sex hormones have the ability fundamentally to modulate secretory activity in parathyroid cells.

Animals↗
PubMed1992

A multisubunit particle implicated in membrane fusion.

The N-ethylmaleimide sensitive fusion protein (NSF) is required for fusion of lipid bilayers at many locations within eukaryotic cells. Binding of NSF to Golgi membranes is known to require an integral membrane receptor and one or more members of a family of related soluble NSF attachment proteins (alpha-, beta-, and gamma-SNAPs). Here we demonstrate the direct interaction of NSF, SNAPs and an integral membrane component in a detergent solubilized system. We show that NSF only binds to SNAPs in the presence of the integral receptor, resulting in the formation of a multisubunit protein complex with a sedimentation coefficient of 20S. Particle assembly reveals striking differences between members of the SNAP protein family; gamma-SNAP associates with the complex via a binding site distinct from that used by alpha- and beta-SNAPs, which are themselves equivalent, alternative subunits of the particle. Once formed, the 20S particle is subsequently able to disassemble in a process coupled to the hydrolysis of ATP. We suggest how cycles of complex assembly and disassembly could help confer specificity to the generalized NSF-dependent fusion apparatus.

Adenosine Triphosphate↗
PubMed1992

[Atropine versus glycopyrrolate in eye surgery. A comparison of rhythm disorders and heart frequency using Holter-ECG].

Anticholinergics are indicated in ophthalmic surgery to inhibit oculocardiac reflexes (OCR). Although all anticholinergics exert an arrhythmic effect, comparative data on occurrence and severity of arrhythmias are not available. The aim of this investigation was to compare atropine (A) and glycopyrrolate (G) in adults undergoing ophthalmic surgery. One hundred patients (ASA class I and II, age range 20-60 yrs.) were given equipotent doses of either A (10 micrograms.kg-1) or G (5 micrograms.kg-1) in a randomized, double-blind fashion, before induction of anaesthesia. Continuous Holter monitoring was performed. The procedure was divided into the following phases: O (5 min before drug), I (5 min after drug), II (up to induction), III (induction until intubation), IV (intubation until operation), V (operation). Supraventricular, junctional, and ventricular arrhythmias were analyzed. Severe arrhythmia was judged to be greater than 5 events per min, or ventricular beats Lown classes III-V. The beat to beat analog signal was digitalized. The heart rate (HR) and the occurrence rate of OCR (greater than 20% decrease in heart rate, arrhythmias) was calculated by a computerized program. Analysed were: 1. the frequency of OCR, 2. the mean HR for each phase, 3. the frequency of all the various arrhythmias during the whole period, 4. as well as for each phase. The number of patients with severe arrhythmias 5. either for all the time or 6. for the individual phase were registered separately. There were no differences 1. in the frequency of OCR and 2. in mean HR during all phases between A and G.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Acoustic rhinometry: the bat principle of the nose].

All cross-sectional areas of the upper airway can be measured by an acoustic signal using the acoustic reflection technique, or acoustic rhinometry. The plane of the cross-sectional areas measured was determined in nasal models. The isotemporal layers were found to be nearly parallel to the nasal valve. The acoustically measured cross-sectional areas correlated with the cross-sectional areas of cuts from nasal models. After digitizing these cuts, a CAD software calculates cross-sectional areas in all orientations and at all distances. The difference between the measured and calculated cross-sectional areas is up to 3% in the nasal cavity and up to 17% in the nasopharynx. The hypothesis that the cross-sectional areas measured lie nearly parallel to the nasal valve was confirmed. The normal rhinometric curve shows the minimal cross-sectional area (I-notch) to lie at the nasal isthmus. The second narrowest segment of the nasal cavity lies at the head of the inferior concha and septal concha (C-notch). Characteristic examples of patients with turbinate hypertrophy, choanal atresia, enlarged adenoids, and septal deviations are presented. Acoustic rhinometric curves can only be interpreted in combination with the rhinoscopic findings because different pathological conditions can produce similar curves. Recording of reliable and reproducible data by acoustic rhinometry demands that the connection between the rhinometer and the nose does not distort the valve area. When we used two different nose pieces (1.2 and 1.5 cm outer diameter) the cross-sectional areas in the anterior third of the nose of only 28% of the patients was measured correctly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoids↗
PubMed1991

ADP-ribosylation factor is a subunit of the coat of Golgi-derived COP-coated vesicles: a novel role for a GTP-binding protein.

ADP-ribosylation factor (ARF) is an abundant and highly conserved low molecular weight GTP-binding protein that was originally identified as a key element required for the action of cholera toxin in mammalian cells, but whose physiological role is unknown. We report that ARF family proteins are highly concentrated in non-clathrin-coated transport vesicles and are coat proteins. About three copies of ARF are present on the outside of coated vesicles per alpha-COP (and thus per coatomer). ARF is highly enriched in coated vesicles as compared with parental Golgi cisternae, as shown both by biochemical and morphological methods, and ARF is removed from transport vesicles through uncoating during transport. Furthermore, ARF binds to Golgi cisternae in a GTP-dependent manner independently of coated vesicle budding. These observations strongly suggest a new role for GTP-binding proteins: ARF proteins may modulate vesicle budding and uncoating through controlled GTP hydrolysis.

ADP-Ribosylation Factors↗
PubMed1991

A new cuff electrode for reversible conduction blocking.

A cuff electrode of novel design (rigid body and lid) is presented. It contains a closed cavity surrounding the nerve, through which a cooled liquid (Ringer solution) can be circulated. Recording sites at both ends of the cavity permit monitoring of the conduction blocking, which occurs at different temperatures for different units. Reversible blocking with chemical agents is equally possible with this device.

Animals↗
PubMed1991

Effects of 10 known or suspected spindle poisons in the in vitro porcine brain tubulin assembly assay.

We tested the 10 known or suspected spindle poisons (colchicine, econazole nitrate, chloral hydrate, hydroquinone, diazepam, thiabendazole, cadmium chloride, thimerosal, pyrimethamine and vinblastine) of the coordinated EEC programme for induction of aneuploidy with the in vitro porcine brain tubulin assembly assay. The influence of the compounds on different parameters [lag-phase, polymerization velocity, endabsorption (steady-state level), reversibility, influence on disassembly at 4 degrees C] was evaluated. Colchicine [IC30 (30% inhibition concentration): 0.002 mM), vinblastine (IC30: 0.002 mM), thimerosal (IC30: 0.03 mM), thiabendazole (IC30: 0.5 mM) and chloral hydrate (IC30: 60 mM) led to an inhibition of tubulin assembly in vitro. No influence on the steady-state level was obtained with econazole nitrate (up to 0.1 mM), diazepam (up to 2.5 mM), cadmium chloride (up to 1 mM), pyrimethamine (up to 1 mM) and hydroquinone (up to 25 mM), the highest dose tested being limited either by precipitation or by reaching the maximal solubility of the compound in the solvent used. Diazepam enhanced the lag-phase and slightly reduced the polymerization velocity dose-dependently; however, all the treated test mixtures reached the same end absorption levels as the control. The influence on the disassembly process was studied at 4 degrees C. Microtubules treated with colchicine, econazole nitrate, diazepam, thiabendazole, cadmium chloride, thimerosal and pyrimethamine reached the same end absorption level after disassembly as the untreated control. Chloral hydrate reduced the disassembly rate but the end absorption of the control was not reached, the 30% reduction concentration being 0.25 mM. Hydroquinone at very high doses (greater than 10 mM) stimulated the disassembly process.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneuploidy↗
PubMed1990

An improved system for single unit isolation from multiunit nerve recordings by velocity analysis.

A system for recording and decomposition of complex extracellular spike trains by analog computing is presented. Unlike other systems, it is not necessary to establish templates for the analysis. Rather by adjustments of a single knob, the velocity band can be adjusted. The velocity measurement can be made to a precision of better than 1%, where the velocity jitter in individual spikes of a unit becomes apparent. Spike trains on the connective of a stick insect are analyzed which occur during an intersegmental reflex, the CLP reflex.

Action Potentials↗
PubMed1990

A precision multichannel cuff electrode optimized by simulation and experiment.

The parameters influencing single end and differential en passant extracellular recordings were investigated using two independent simulation methods. The results were compared with measurements from experimental electrodes. The effects of electrode size, electrode distance and leakage can thus be understood and the experiments agree with the simulation results. This led to the optimation of a novel en passant electrode producing very narrow signals with very high reliability. The electrode is used for multichannel recording in a velocity selective recording system.

Action Potentials↗
PubMed1989

Absence of BK virus sequences in transformed hamster cells transfected by human tumor DNA.

In an attempt to gain insight into the mechanism of oncogenic transformation by BK virus (BKV), a human papovavirus, we have probed for BKV sequences in transformed hamster cells in which oncogenic transformation had occurred as a result of transfection by human tumor DNA positive for BKV sequences. Even though the sources of the transfecting DNA contained BKV sequences, the transformed hamster cells which arose from the transfection for the most part did not retain BKV sequences. In only one barely detectable case was BKV-specific DNA found associated with chromosomal DNA, and in only a small minority of the transformed cells was BKV DNA detected in the Hirt supernatant, indicating an episomal configuration. Even in these few cases where BKV sequences were present in an episomal form, altered migration on gels of some BKV-positive bands (compared to bands derived from cloned viral DNA) suggested deletions and rearrangements of BKV DNA. We employed several different probe methodologies for these studies, including nick-translation, random primer and a non-isotopic biotinylated probe which gave a sensitivity that could detect better than 0.01 copy of viral genome per diploid cell. We conclude that transformation by transfection with human tumor DNA does not require persistence of the BKV viral genome, suggesting that either BKV virus was irrelevant to original oncogenesis, in analogy with models proposed by others for herpesvirus oncogenesis.

Animals↗
PubMed1988

Two new ELISAs using monoclonal H-Y antibody.

Biotin-conjugated monoclonal H-Y antibody was used to detect soluble H-Y antigen, directly, in two novel enzyme-based systems: a sandwich or 'capture' ELISA and an inhibition ELISA. In each case, soluble H-Y was readily detected in samples known to contain the antigen, provided that positive and negative samples were compared on an equivalent protein basis. By adding increasing concentrations of inhibitor (antigen) we define the useful range of the assays to be between 0.6 and 20.0 micrograms of added protein. Both sandwich and inhibition ELISAs gave similar results with antigens tested. The methods can accordingly be applied as direct diagnostics in the study of sex determination and in the assignment of gender.

Animals↗
PubMed1988

A modular analog neuron-model for research and teaching.

An analog electronic neuron for modeling neuronal networks and for teaching purposes is presented. The circuitry represents a new approach, since ionic channels are all modeled by fast relay switches in combination with resistors. Thus, the synapse design includes nonlinear PSP superposition and reversal potentials. The spike is modeled with Na+ and K+ currents. Detailed circuit diagrams and examples of performance are given. Besides its use in network research, the model has been successfully used over 3 years of teaching practice.

Action Potentials↗
PubMed1988

Purification and analysis of a sex-specific antibody.

Analysis of the male-specific H-Y antigen is difficult, in part, because of the tendency of "male-specific" antisera to bind cell surface components found in male and in female cells. Some insight as to the nature of that difficulty is provided by biochemical evaluation of H-Y antibody. In this study, purification of a monoclonal H-Y antibody with ammonium sulfate or Protein-A Sepharose, revealed the possibility of microheterogeneity. Despite evidence of multiple subtypes, Protein-A elution profiles suggested that the male-specific activity of the antibody resided in an IgG2a moiety. This was borne out by decreased activity after absorption of the IgG2a subtype with male cells, and by reaction of the monoclonal antibody with mouse subtype-specific antisera in an ELISA. Combined analysis using biological (absorption), biochemical (EF and PAGE) and immunological (ELISA) methods could find applicability in other complex systems.

Animals↗
PubMed1987

Promoter recognition and promoter strength in the Escherichia coli system.

The strength of Escherichia coli promoters in vivo as well as the rates of association between RNA polymerase and promoter sequences differ by more than an order of magnitude. Since efficient promoter recognition and rapid binding of the enzyme might be a prerequisite for exceptional promoter strength we have determined the forward rate constants kon (as well as koff) for nine promoters including PL, PA1, and PN25 from phages lambda, T7, and T5, respectively as well as Pbla and PlacUV5 from E. coli. The second order forward rate constants span a 30-fold range from 1 X 10(7) M-1 s-1 for Pbla and PL up to 2.9 X 10(8) M-1 S-1 for PN25. Little correlation between 'promoter recognition' as defined by the rate of complex formation of a promoter sequence with RNA polymerase and its strength in vivo as defined by the rate of RNA synthesis has been found. This adds to the evidence that the complex functional pathway encoded in a promoter sequence can be limited at various levels and that promoter strength in vivo is the result of an optimization process involving more than just one functional parameter.

Bacteriophage lambda↗
PubMed1987

Reaction of monoclonal H-Y antibody in the ELISA.

Monoclonal H-Y antibody of demonstrated specificity was reacted with soluble H-Y antigen in a newly-developed enzyme-linked immunosorbent assay (ELISA). Typing of cell lines was accomplished by qualitative and quantitative absorption. In one case, the antibody was subdivided into equal portions, each of which was absorbed with 1, 3, 6 or 12 X 10(6) cells from male or female; after absorption, the cells were discarded and the antibody was titrated for residual activity in the ELISA. With increasing cell numbers, optical density scores for male-absorbed antibody approached baseline levels. Although male-female differences were pronounced and highly significant, there was also a fall in reactivity after absorption with female cells.

Animals↗