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Biomedical subjects

J Rudolph

Publications and source records attributed to J Rudolph.

At least 55 records · Page 3Linked to original sources
PubMed1995

Phosphorylation in halobacterial signal transduction.

Regulated phosphorylation of proteins has been shown to be a hallmark of signal transduction mechanisms in both Eubacteria and Eukarya. Here we demonstrate that phosphorylation and dephosphorylation are also the underlying mechanism of chemo- and phototactic signal transduction in Archaea, the third branch of the living world. Cloning and sequencing of the region upstream of the cheA gene, known to be required for chemo- and phototaxis in Halobacterium salinarium, has identified cheY and cheB analogs which appear to form part of an operon which also includes cheA and the following open reading frame of 585 nucleotides. The CheY and CheB proteins have 31.3 and 37.5% sequence identity compared with the known signal transduction proteins CheY and CheB from Escherichia coli, respectively. The biochemical activities of both CheA and CheY were investigated following their expression in E.coli, isolation and renaturation. Wild-type CheA could be phosphorylated in a time-dependent manner in the presence of [gamma-32P]ATP and Mg2+, whereas the mutant CheA(H44Q) remained unlabeled. Phosphorylated CheA was dephosphorylated rapidly by the addition of wild-type CheY. The mutant CheY(D53A) had no effect on phosphorylated CheA. The mechanism of chemo- and phototactic signal transduction in the Archaeon H.salinarium, therefore, is similar to the two-component signaling system known from chemotaxis in the eubacterium E.coli.

Amino Acid Sequence↗
PubMed1995

Investigation of the mechanism of phosphoribosylamine transfer from glutamine phosphoribosylpyrophosphate amidotransferase to glycinamide ribonucleotide synthetase.

Phosphoribosylamine (PRA) is a product of glutamine phosphoribosylpyrophosphate amidotransferase (PRPP-AT) and a substrate for glycinamide ribonucleotide synthetase (GAR-syn), the first two enzymes in the de novo purine biosynthetic pathway. PRA has a half-life of 5 s under physiological conditions, hydrolyzing to ribose 5-phosphate. The instability of this purine precursor brings to question how the efficiency of transfer from one active site to the next is ensured: Is PRA transferred by free diffusion, or is it transferred directly from one enzyme to the next through a process defined as substrate channeling? Kinetic investigations of reactions containing both enzymes monitoring the appearance of the intermediate PRA and/or the product GAR were performed and compared with the predicted kinetics assuming a free diffusion mechanism of transfer. A significant discrepancy exists between the free diffusion model and the experimental data when the ratios of the two enzymes are varied. To accommodate this discrepancy, a direct transfer mechanism is proposed that is facilitated by protein-protein interactions. Experiments to provide evidence for these stable protein-protein interactions including gel chromatography, fluorescence spectroscopy, chemical cross-linking, and affinity gel chromatography; however, have all been unsuccessful. These results suggest that the requisite channeling interaction between PRPP-AT and GAR-syn, which is indicated by the kinetic results, must be a transient one.

Amidophosphoribosyltransferase↗
PubMed1995

Chemotaxis and phototaxis require a CheA histidine kinase in the archaeon Halobacterium salinarium.

Histidine kinases are part of the two-component signal transduction system responsible for eubacterial responses to diverse environmental signals. They have recently been detected in eukaryotes but their existence in the kingdom Archaea remains uncertain. Here we report the sequence and function of a histidine kinase (CheAH.s.) from Halobacterium salinarium, the first such transmitter in Archaea. The protein CheAH.s. (668 residues) has significant sequence identity with the CheA proteins known from eubacterial signal transduction (e.g. 34% identity with CheA from Bacillus subtilis). Antibodies were raised against CheAH.s. as expressed in Escherichia coli and were used in Western blotting to demonstrate the expression of cheAH.s. in H. salinarium. As has been observed for other halophilic proteins, CheAH.s. has a deviant electrophoretic migration, with an apparent molecular weight of 103 kDa on SDS-PAGE compared with a calculated molecular weight of 72 kDa. Deletion of a part of the cheAH.s. gene leads to loss of both chemotactic and phototactic responses in H. salinarium as measured by swarm plate assays, motion analysis and tethering experiments. This indicates that CheAH.s. plays a crucial role in chemical and light signal integration, presumably interacting with at least two phototransducers and a number of chemoreceptors.

Amino Acid Sequence↗
PubMed1994

N5-carboxyaminoimidazole ribonucleotide: evidence for a new intermediate and two new enzymatic activities in the de novo purine biosynthetic pathway of Escherichia coli.

Conversion of aminoimidazole ribonucleotide (AIR) to 4-carboxyaminoimidazole ribonucleotide (CAIR) in Escherichia coli requires two proteins, PurE and PurK, previously thought to be subunits of a single enzyme, AIR carboxylase. Past studies revealing an ATP requirement for this reaction (Meyer et al., 1992), in conjunction with present studies, reveal that PurE and PurK possess independent catalytic activities. PurK is shown, by NMR spectroscopy, to catalyze the conversion of AIR in the presence of HCO3- and ATP to ADP, P(i), and the carbamate of AIR (designated N5-CAIR). PurE has been shown by NMR spectroscopy and kinetic analysis, to catalyze the reversible conversion of N5-CAIR and CAIR. N5-CAIR has a half-life of 0.9 min at pH 7.8 and 30 degrees C. Thus, two new enzymatic activities and a new intermediate have been discovered in the de novo purine biosynthetic pathway of E. coli.

Adenosine Diphosphate↗
PubMed1991

Work-site smoking policies in small businesses.

A growing number of workers in the United States are employed in small businesses. This study describes the experiences of small work sites in implementing policies restricting smoking. In the fall of 1987, we surveyed by telephone 216 work sites employing 120 or fewer persons. Compared with companies without policies, companies with policies were larger and reported having fewer smokers and more management support for smoking policies. Seventy-three percent of work sites without a smoking policy said they would be very likely to implement a policy if it were required by law; 42% of work sites with a policy reported offering smoking cessation assistance to their employees. Overall satisfaction and compliance with the smoking policy was high among work sites with a policy. The findings of this study have key implications for other small businesses considering implementing a smoking policy.

Employee Grievances↗
PubMed1990

Glycinamide ribonucleotide synthetase from Escherichia coli: cloning, overproduction, sequencing, isolation, and characterization.

The purD gene of Escherichia coli encoding the enzyme glycinamide ribonucleotide (GAR) synthetase, which catalyzes the conversion of phosphoribosylamine (PRA), glycine, and MgATP to glycinamide ribonucleotide, MgADP, and Pi, has been cloned and sequenced. The protein, as deduced by the structural gene sequence, contains 430 amino acids and has a calculated Mr of 45,945. Construction of an overproducing strain behind a lambda pL promoter allowed a 4-fold purification of the protein to homogeneity. N-Terminal sequence analysis and comparison of the sequence with those of other GAR synthetases confirm the amino acid sequence deduced from the gene sequence. Initial velocity studies and product and dead-end inhibition studies are most consistent with a sequential ordered mechanism of substrate binding and product release in which PRA binds first followed by MgATP and then glycine; Pi leaves first, followed by loss of MgADP and finally GAR. Incubation of [18O]glycine, ATP, and PRA results in quantitative transfer of the 18O to Pi. GAR synthetase is very specific for its substrate glycine.

Amino Acid Sequence↗
PubMed1990

Counselors' attitudes toward homosexuality: some tentative findings.

The attitudes of 52 counselors and trainees toward homosexuality showed respondents were less likely to accept homosexual persons in eroticized contexts, more likely in noneroticized contexts, with mixed acceptance for homosexuals in sensitive professional positions. Respondents generally accepted homosexuals' civil rights and saw homosexuality as nonpathological and unrelated to morality per se. Social distance theory may explain these results.

Adult↗
PubMed1989

[The effect of bronchologic studies on blood gases and hemodynamics in children].

During 78 bronchological examinations in children of all age groups out of 6 centers of children bronchology of the GDR PaO2, PaCO2 and pH were registered, in a part of them additionally pulse, systolic and diastolic blood pressure. Following to the intubation--under ventilation with 100% oxygen or a halothane-NO2-oxygen mixture--there was a marked rise of PaO2, which normalized after extubation quickly. After extubation a slight hypoxemia occurred for a short period, a quick rise of PaCO2 and a slight acidosis, too. Besides, the hearth rate, systolic and diastolic blood pressure elevated following to the intubation and diminished after extubation.

Acid-Base Equilibrium↗
PubMed1986

Problems connected with the analysis of halocarbons and hydrocarbons in the non-urban atmosphere.

The problems connected with the measurement of hydrocarbons outside urban areas are considerable: The atmospheric mixing ratios of most of the hydrocarbons are very low--from a few ppb down to some ppt; the mixture of hydrocarbons is extremely complex, ranging from light n-alkanes to alkyl benzenes and terpenes; for measurements in remote areas the logistic conditions often restrict the instrumentation which can be used for sample collection or in situ measurements (such as lack of electric power supply, weight restrictions etc.). Nevertheless, sensitive and sufficiently reliable measurements of hydrocarbons in the non-urban atmosphere are important. Hydrocarbons are important factors in the tropospheric photochemistry (e.g. ozone formation) and can be used as valuable tracers for man-made atmospheric pollutants etc. Other useful tracers for anthropogenic emission are halocarbons such as dichlormethane, tri- and tetrachloroethen etc. The impact of man-made hydrocarbons on the chemistry of the troposphere can only be understood if the extent of natural (biogenic) contributions is known. From measurements of a large variety of hydrocarbons and halocarbons it is often possible to obtain information about the sources of the most important atmospheric hydrocarbon species, even for trace gases with both significant anthropogenic and biogenic sources. In this presentation some of the problems and their solutions connected with such measurements of atmospheric hydrocarbons and halocarbons are presented and discussed. Some of the results obtained by several series of measurements are described, indicating that man-made as well as biogenic hydrocarbons can be important factors for the chemistry of the atmosphere.

Air Pollutants, Occupational↗
PubMed1984

Encephalo-angiomatosis in black children. A report of 2 cases.

Two cases of encephalo-angiomatosis are reported. The clinical presentation and certain neurological findings and investigations confirm the diagnosis of a disease which is relatively rare among Blacks. The case reports were considered valuable because of the rareness of the condition. Up to 1962 only 145 cases had been reported in the world literature. Encephalo-angiomatosis or Sturge-Weber syndrome is one of the disease groups known as phakomatoses, and an attempt is made to characterize each phakomatosis condition.

Adolescent↗
PubMed1981

Aggression in the service of the ego and the self.

With Jay, as with other patients in psychoanalysis, the pathological has shed light on the normal. First, during symbiosis, physical illness markedly disrupted his sense of well-being. He did not develop sufficient reserves of narcissism and instead built up a superabundance of hostile aggression. In the differentiation subphase of separation-individuation, his aggression could not be used constructively in the service of differentiation. In the practicing subphase, still immobilized, he was unable to effect even physical separation, let alone psychic separation. These subphase inadequacies, of course, influenced the character of his rapprochement subphase. With functioning already impaired by earlier subphase experience, continuing emotional pain and frustration affected his ability to negotiate the rapprochement subphase. Missing for Jay were the contributions that an adequate rapprochement subphase furnishes the organizing function of the ego. Not only did the rapprochement subphase fail to correct the inadequacies of the earlier subphases, the failures of rapprochement represented the last and final blow to the development of even a semblance of self- and object constancy, so that borderline pathology was the result. We can follow the progress made by the analysand by his own statements: Early: "I don't have a reserve of self-love to carry me through." Later, "I'm at a stage when I feel I can organize things without great anxiety. Plan things. Going ahead and slipping back sometimes too, but feeling confident." It has been the aim of this paper to show how the most malignant narcissistic rage has been converted into constructive aggression. Despite the greatest intrinsic and environmental odds, this patient, because of his good endowment, and aided by psychoanalysis, succeeded in gradually converting destructive aggression into constructive aggression by amalgamating it with more and more libido. Along with this, he also developed a sound secondary narcissism, so that his prognosis at eighteen years of age is optimistic.

Aggression↗
PubMed1981

[The problem of documentation in traumatology].

An exact documentation is a necessary demand of modern medicine. Different methods of the registration of information, for example the conventional sick-paper, the punch card and the electronic data processing documentation are opposed with their pros and cons. The own experiences of the surgical hospital of the Friedrich-Schiller-University with the documentation of injured patients is shown and explained. The text points to the importance of the electronic data processing registration and evaluation of the many facts of the injured patients concerning the therapeutic, epicritical, but also epidemic and legal questions.

Accidents↗