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G Müller

Publications and source records attributed to G Müller.

At least 397 records · Page 22Linked to original sources
PubMed1989

An amphitropic cAMP-binding protein in yeast mitochondria. 1. Synergistic control of the intramitochondrial location by calcium and phospholipid.

A cAMP-binding protein is found to be integrated into the inner mitochondrial membrane of the yeast Saccharomyces cerevisiae under normal conditions. It resists solubilization by high salt and chaotropic agents. The protein is, however, converted to a soluble form which then resides in the intermembrane space, when isolated mitochondria are incubated with low concentrations of calcium. Phospholipids or diacylglycerol (or analogues) dramatically increases the efficiency of receptor release from the inner membrane, whereas these compounds alone are ineffective. Also, cAMP does not effect or enhance liberation from the membrane of the cAMP-binding protein. Photoaffinity labeling with 8-N3-[32P]cAMP followed by mitochondrial subfractionation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis does not reveal differences in the apparent molecular weight between the membrane-bound and the soluble form of the cAMP receptor. The two forms differ, however, in their partitioning behavior in Triton X-114 as well as in their protease resistance, indicating that the release from the membrane is accompanied by a change in lipophilicity and conformation of the receptor protein. Evidence is presented that a change of the intramitochondrial location of the yeast cAMP-binding protein also occurs in vivo and leads to the activation of a mitochondrial cAMP-dependent protein kinase. The cAMP-binding protein is the first example of a mitochondrial protein with amphitropic character; i.e., it has the property to occur in two different locations, as a membrane-embedded and a soluble form.

Binding Sites↗
PubMed1989

An amphitropic cAMP-binding protein in yeast mitochondria. 2. Phospholipid nature of the membrane anchor.

We describe the first example of a mitochondrial protein with a covalently attached phosphatidylinositol moiety acting as a membrane anchor. The protein can be metabolically labeled with both stearic acid and inositol. The stearic acid label is removed by phospholipase D whereupon the protein with the retained inositol label is released from the membrane. This protein is a cAMP receptor of the yeast Saccharomyces cerevisiae and tightly associated with the inner mitochondrial membrane. However, it is converted into a soluble form during incubation of isolated mitochondria with Ca2+ and phospholipid (or lipid derivatives). This transition requires the action of a proteinaceous, N-ethylmaleimide-sensitive component of the intermembrane space and is accompanied by a decrease in the lipophilicity of the cAMP receptor. We propose that the component of the intermembrane space triggers the amphitropic behavior of the mitochondrial lipid-modified cAMP-binding protein through a phospholipase activity.

Animals↗
PubMed1989

An amphitropic cAMP-binding protein in yeast mitochondria. 3. Membrane release requires both Ca2(+)-dependent phosphorylation of the cAMP-binding protein and a phospholipid-activated mitochondrial phospholipase.

The amphitropic cAMP-binding protein in mitochondria of the yeast Saccharomyces cerevisiae is released from the inner membrane into the intermembrane space by the degradation of its lipid membrane anchor consisting of or containing phosphatidylinositol. The releasing reaction depends on the presence of an N-ethylmaleimide-sensitive protein (releasing factor) in the intermembrane space and is controlled by Ca2+ and phospholipid (or lipid derivatives). Here we demonstrate that these two effector molecules act on different activation steps within a complex releasing pathway involving both the cAMP receptor and the releasing factor: Ca2(+)-dependent phosphorylation of the receptor protein seems to be prerequisite for its subsequent lipolytic liberation from the inner membrane. In the presence of phospholipid (or lipid derivatives) the previously soluble releasing factor, which may be identical with a soluble diacylglycerol-binding protein in the mitochondrial intermembrane space, associates with the inner membrane. This change in the intramitochondrial location of the releasing factor, which thus exhibits amphitropic behavior itself, may be required for (direct or indirect) activation of the mitochondrial phospholipase which then releases the cAMP receptor from the inner membrane in a form liable to dissociation from the C subunit by cAMP.

Calcium↗
PubMed1989

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Journal Article↗
PubMed1989

Export of honeybee prepromelittin in Escherichia coli depends on the membrane potential but does not depend on proteins secA and secY.

Honeybee prepromelittin (70 amino acid residues), the precursor of an eukaryotic secretory protein, and a hybrid protein between prepromelittin and mouse dihydrofolate reductase (257 amino acid residues) were expressed in Escherichia coli and characterized with respect to their requirements for transport across the plasma membrane. Both precursor proteins are posttranslationally processed and exported into the periplasm, and they both depend on the membrane potential for this to occur. With respect to dependence on components of the export machinery, however, the two precursor proteins show striking differences: the small precursor protein prepromelittin does not require the function of proteins secA and secY; the large precursor protein prepromelittin-dihydrofolate reductase, on the other hand, depends on both components. The implications of these observations with respect to the mechanisms of protein export in E. coli and of protein import into the endoplasmic reticulum are discussed.

Animals↗
PubMed1989

Localization of Y chromosome sequences and X chromosomal replication studies in XX males.

By in situ hybridization, Y-specific DNA sequences were localized on Xp22.3-Xpter of one of the two X chromosomes in all of eleven XX males studied. In nine of the cases the presence of the Y-specific DNA did not affect random X inactivation in fibroblasts. Fibroblasts of the other two cases showed a preferential inactivation of the Y DNA-carrying X chromosome. In only one of these two exceptions blood lymphocytes could also be studied, and here, random inactivation of the Y DNA-carrying X chromosome occurred. Furthermore, the gene dosage of steroid sulfatase (STS) was examined by Southern blot analysis. In ten of the cases including the one showing random X-inactivation in lymphocytes but not in fibroblasts, a double dosage of the STS gene is present. The remaining case with non-random inactivation shows a single STS gene dosage. This case was reported previously to have STS enzyme activity in the male range. It is assumed that, as a consequence DNA sequences may result in the preferential inactivation of the Y DNA-carrying X chromosome.

Arylsulfatases↗
PubMed1989

The excretion of chlorophenylmercapturic acid, chlorophenols and a guanine adduct in the urine of chlorobenzene-treated rats after phenobarbital pretreatment.

Chlorobenzene (CB) was administered to male Wistar rats. Twenty-four-hour urine samples were collected over a period of 7 days. p-Chlorophenylmercapturic acid, chlorophenols and a guanine adduct were determined by chromatographic methods. The excretion pattern of p-chlorophenyl-mercapturic acid did not seem to be significantly affected by phenobarbital. To analyze for the chlorophenols and guanine adducts, diluted urine was subjected to cation exchange chromatography using UV-detection. Fractions were found containing chlorophenols and a compound showing chromatographic properties similar to those of the synthetic N7-phenylguanine. The results of the HPLC analyses suggested the presence of a guanine adduct excreted on days 1 and 2 and between days 4 and 6 post-administration. There were no compounds detected which were identical with p-, m- or o-isomers of N7-chlorophenylguanine. The excretion of p- and m-chlorophenols by phenobarbital-pretreated animals was twice as high as that in untreated rats. A 4-fold increase was detected for o-chlorophenol. It is assumed that it is mainly direct hydroxylation that can be induced by phenobarbital. Dehalogenated phenolic metabolites may be capable of covalent binding to DNA.

Acetylcysteine↗
PubMed1989

Determination of S-phenylmercapturic acid in the urine--an improvement in the biological monitoring of benzene exposure.

In an inhalation study rats were exposed to different doses of benzene, ranging from 1 to 500 p.p.m. The urine was sampled during the inhalation period of 8 h and for 24 h after exposure. S-Phenylmercapturic acid (S-PMA) in the urine was determined by amino acid analysis. Phenol was measured by gas chromatography/mass spectrometry. In both cases the correlation between benzene uptake and the excretion of the urinary metabolites was significant at the level of P = 0.01. The same significant correlation (P = 0.01) was demonstrable after i.p. administration of benzene at doses between 0.7 and 140.0 microliters/kg body weight. In the case of two collectives of workers who were exposed to air concentrations of up to 0.15 p.p.m. for 8 h and of up to 1.13 p.p.m. for 12 h respectively, the amount of S-PMA in the first urine samples after the shift was significantly higher than in samples collected at the beginning of the shift (P = 0.01). In the first collective the mean values and the standard deviations of the S-PMA concentrations in the samples at the beginning of the shift were 12.0 +/- 16.7 compared with 48.5 +/- 64.5 micrograms/g creatinine at shift end. In the second collective they were 25.1 +/- 25.1 compared with 70.9 +/- 109.2 micrograms/g creatinine. The level of significance of the difference between the concentration values of S-PMA at the beginning and end of the shift was P = 0.01. The phenol concentration did not differ significantly. These results suggest that S-PMA can be regarded as a useful indicator for monitoring individuals and collectives exposed to benzene at levels even less than 1 p.p.m.

Acetylcysteine↗
PubMed1989

Mammalian sex-chromosome evolution: a conserved homoeologous segment on the X and Y chromosomes in primates.

In a representative sample of primate species, including simians (Catarrhini and Platyrrhini) and prosimians (Lemuriformes and Lorisiformes), high-resolution, early replication banding revealed a homoeologous early replicating segment at the ends of both sex chromosomes. The DXYZ2 element, a repeated sequence specific for the human pseudoautosomal region, is conserved in the genomes of all primate species studies and is specifically localized in the distal early replicating segments of the X and Y chromosomes. Thus, cytogenetic and molecular evidence is presented of a highly conserved sex-chromosomal segment in primates. The pseudoautosomal behavior of this segment is discussed.

Animals↗
PubMed1989

Amoxicillin in the treatment of asymptomatic bacteriuria in pregnancy: a single dose of 3 g amoxicillin versus a 4-day course of 3 doses 750 mg amoxicillin.

A prospective, randomized, controlled comparative clinical trial was carried out with the aim of investigating the efficacy and tolerance of two different dosage regimens of amoxicillin in the treatment of asymptomatic bacteriuria during pregnancy. Patients in group A received a single dose of 3 g amoxicillin, which was compared to a 4-day course of 3 X 750 mg amoxicillin tablets taken every 8 h (group B). Significant bacteriuria (CFU greater than or equal to 10(5)/ml clean catch midstream urine and CFU greater than or equal to 10(4)/ml urine obtained by bladder catheterization) was diagnosed using the dip-slide method (Uricult). 91 pregnant women with a mean gestational age of 25 weeks (14-38) were randomly allocated to the two treatment groups. 53 patients were assigned to group A and 38 patients to group B. The treatment groups were comparable in terms of age and duration of pregnancy. Urine culture tests were performed 1 and 4 weeks after completion of therapy. The predominant species was Escherichia coli, which was isolated in 60-65% of the cases. Bacteriological cure rates at 1 and 4 weeks, respectively, were 77 and 74% in group A, and 62 and 62% in group B. These differences were statistically not significant. The incidence of side effects was 4% in group A and 13% in group B. The results obtained in the present study suggest that in the treatment of asymptomatic bacteriuria in pregnancy, a single dose of 3 g amoxicillin is as effective and acceptable as a 4-day course. In addition, the single-dose regimen offers the advantage of a reduction in total dose, lower costs and better patient compliance.

Adolescent↗
PubMed1989

[Biofeedback training and functional electrostimulation for improving incontinence in children with anal atresia].

Eleven children with anal incontinence following a pull-through operation for anorectal agenesis (4 low, 7 high anomalies) were treated with a conservative continence training program (optic/acoustic biofeedback, transcutaneous electrical stimulation, physical therapy, contraction exercises and sensibility training). All patients with one exception showed subjective and objective improvement of continence. Sphincter contraction increased by 80% in high and by 40% in low anomalies. For a short time electrostimulation provided an improvement of up to 20% in sphincter pressure. One additional success was improved coordination. Beside surgical therapy and other methods continence training is always indicated.

Adolescent↗
PubMed1989

[Endocapsular cataract surgery using the excimer laser at 308 nm].

We present our experience with in vitro endocapsular cataract surgery ("phakoablation") using the excimer laser at a wavelength of 308 nm. The ablation threshold for human lens nuclei (0.5 J/cm2) was found to be significantly lower compared to that for the capsule (1.5 J/cm2). A total energy of 215 J (mean value) is required for endocapsular ablation of human lens nuclei. For cataract surgery the laser pulses are coupled to a quartz fiber that is integrated into an irrigation/aspiration handpiece. Using the prototype we developed, endocapsular cataract surgery on autopsy eyes with opaque lenses could be performed within about 30 min without major damage to the capsule. Initial measurements of retinal UV exposure indicate that retinal damage might be expected only if the posterior lens capsule is ruptured. Thus endocapsular cataract surgery with the excimer laser seems to be feasible.

Cataract Extraction↗
PubMed1989

[In vitro studies of refractive corneal surgery using the excimer laser with quartz fiber].

With the application of different approved drugs, UV absorption of the cornea at 308 nm could be increased by more than three orders of magnitude, which provided effective shielding of intraocular structures against 308 nm excimer laser radiation. The width of the thermal damage zones at the edges of 308 nm excimer laser excisions was reduced to a few micrometers by our treatment. The ablation threshold was reduced by this treatment and the ablation rates were increased by a factor of three to five. In principle, these results offer the possibility of performing refractive corneal surgery with excimer lasers at 308 nm via quartz fibers.

Animals↗
PubMed1989

Lesions of the caudal pontine reticular nucleus reduce spontaneous behavioural activity of rats differently in dorsal and ventral parts of the nucleus.

Four groups of 8 adult male hooded rats of the Long-Evans strain were investigated before and after lesions of the dorsal or the ventral subdivisions of the caudal pontine reticular nucleus (RPC) in an open field test (OF) and in a neurological test program. After dorsal (d) RPC lesions all labyrinthine reflexes were extremely slowed, tactile and visual placing responses strongly reduced and the startle reflex abolished, whereas ventral (v) RPC lesions did not alter the neurological status. The dRPC rats showed strongly reduced drinking from water bottles, did not eat pellets in their home cages and lost 5% of their body weight per day. This could be prevented by a supply with a cornflake pap. The ventral RPC lesion revealed no influence on food and water intake. Ambulatory activity in the OF was strongly reduced by dorsal lesions but not by ventralones. The habituation quotient increased only after ventral RPC lesions. Both lesion types increased the duration of immobilization. Exploratory activity was also reduced after both lesion types, but significantly stronger after dorsal lesions. In a centrophobia test the dRPC rats were 6 times slower than before lesion, whereas vRPC rats remained unchanged compared with their preoperative values. The negativism-test revealed strong enhancement after dRPC lesions, but not so strong after vRPC lesions. The results indicate specialized subdivisions of the pontine reticular formation controlling differently spontaneous behaviour.

Animals↗