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Biomedical subjects

E Orr

Publications and source records attributed to E Orr.

At least 19 recordsLinked to original sources
PubMed1995

Actual and perceived parental social status: effects on adolescent self-concept.

This paper proposes a model in which parental social status (PSS) and perceived parental social status (PEPSS) affect adolescent self-concept in distinct ways: PSS affects school achievement and consequently self-concept in the academic domain, whereas PEPSS affects self-concept in the social domain. Two studies of Israeli high school students (N = 569), one on kibbutz and one on urban youth, were carried out. PSS was measured by father's education and occupation, and PEPSS by a new scale. Academic and social self-concepts were tapped by Marsh's SDQ II in the urban sample, and by a combination of the latter and Harter's SPPA in the kibbutz sample. The findings supported the model with one exception: in the urban setting, PSS was not related to academic self-concept. The findings rejected a model underlying the theory of Rosenberg and Pearlin, in which perceived parental social status mediates the effect of parental social status on adolescent self-concept.

Adolescent↗
PubMed1991

The identification and purification of a mammalian-like protein kinase C in the yeast Saccharomyces cerevisiae.

We have purified a yeast protein kinase that is phospholipid-dependent and activated by Diacylglycerol (DAG) in the presence of Ca2+ or by the tumour-promoting agent tetradecanoyl-phorbol acetate (TPA). The properties of this enzyme are similar to those of the mammalian protein kinase C (PKC). The enzyme was purified using chromatography on DEAE-cellulose followed by hydroxylapatite. The latter chromatography separated the activity to three distinguishable sub-species, analogous to the mammalian PKC isoenzymes. The fractions enriched in PKC activity contain proteins that specifically bind TPA, are specifically phosphorylated in the presence of DAG and recognized by anti-mammalian PKC antibodies.

Animals↗
PubMed1991

The yeast type II myosin heavy chain: analysis of its predicted polypeptide sequence.

We have completed the nucleotide sequence of the yeast MYO1 gene and deduced its amino acid sequence. The gene is 5553 bp long and contains no introns. Analysis of the sequence, as well as its comparison with other myosins, demonstrate that the yeast protein is a type II myosin heavy chain with characteristic head and tail regions. The latter domain contains six proline residues in two clusters of three, at approximately two thirds from the start of the gene.

Acanthamoeba↗
PubMed1990

The effect of novobiocin on yeast topoisomerase type II.

Low concentrations of novobiocin are toxic to permeable yeast cells, but do not inhibit type II topoisomerase activity. Furthermore, the enzyme does not bind specifically to novobiocin-Sepharose. These observations are in agreement with genetical analyses. Mutations at a single locus that confer novobiocin resistance and temperature sensitivity exhibit a similar phenotype to cells treated with novobiocin, but are not topoisomerase II mutants.

Chromatography, Affinity↗
PubMed1990

Sense of competence, time perspective, and state-anxiety of separated versus divorced mothers.

Separated and divorced mothers, with median separation times of four and 22 months, respectively, were compared on sense of competence, time perspective, and state-anxiety. Divorced mothers showed less defensiveness, in that their self-esteem ratings were more congruent with their self-efficacy and anxiety ratings. They also showed more positive time perspective, indicating greater optimism and suggesting a process of positive emotional transition.

Achievement↗
PubMed1990

The F1 ATP synthetase beta-subunit: a major yeast novobiocin binding protein.

Novobiocin affects DNA metabolism in both prokaryotes and eukaryotes, resulting in cell death. In prokaryotes, the drug is a specific inhibitor of DNA gyrase, a type II topoisomerase that can be purified on a novobiocin-Sepharose column. The yeast type II topoisomerase is neither the biochemical, nor the genetic target of the antibiotic. We have purified the major yeast novobiocin binding proteins and identified one of them as the beta-subunit of the yeast mitochondrial F1 ATP synthetase, a protein highly conserved throughout evolution. The inactivation of this protein might explain the toxic effects of novobiocin on higher eukaryotic cells.

Amino Acid Sequence↗
PubMed1990

Disease appraisals as a coping strategy with cancer threat.

The aim of the present study was to test the hypotheses that minimizing cancer threat is a prevalent and useful coping strategy for breast cancer patients. Forty-nine primary breast cancer patients and a comparison group of 57 healthy women appraised cancer, heart disease and surgery. The hypotheses were confirmed. Breast cancer patients appraised cancer and the two other disease states significantly more optimistically than did healthy respondents. Breast cancer patients appraised the three diseases more optimistically at the beginning of the post-mastectomy year than at its end, and patients with worse prognoses appraised cancer in a more optimistic direction than patients with a more favorable one. More minimization was prospectively related to a better social adjustment.

Adaptation, Psychological↗
PubMed1988

Characterization of the gene for fructose-1,6-bisphosphatase from Saccharomyces cerevisiae and Schizosaccharomyces pombe. Sequence, protein homology, and expression during growth on glucose.

We have determined the nucleotide sequence of the gene for fructose-1,6-bisphosphatase from both Saccharomyces cerevisiae and Schizosaccharomyces pombe. The predicted protein sequence for fructose-1,6-bisphosphatase from S. cerevisiae contains 347 amino acids and has a molecular weight of 38,100; that from S. pombe, contains 346 amino acids and has a molecular weight of 38,380. Comparison of these amino acid sequences with each other and that of pig kidney fructose-1,6-bisphosphatase shows several regions of strong homology separated by regions of divergence. These homologous regions are likely candidates for functional domains. A gene cassette was constructed for fructose-1,6-bisphosphatase from S. cerevisiae and the gene cassette expressed from the regulated PHO5 and GAL1 promoters of yeast. Yeast cells expressing fructose-1,6-bisphosphatase, while growing on glucose, accumulated large amounts of enzyme intracellularly, suggesting that glucose-regulated proteolytic inactivation does not operate efficiently under these conditions. Growth on glucose was not inhibited by the expression of fructose 1,6-bisphosphatase.

Amino Acid Sequence↗
PubMed1988

Heat stress in the presence of low RNA polymerase activity increases chromosome copy number of Escherichia coli.

A temperature shift-up accompanied by a reduction in RNA polymerase activity in Escherichia coli causes an increased rate of initiation leading to a 1.7- to 2.2-fold increase in chromosome copy number. A temperature shift-up without a reduction in polymerase activity induces only a transient non-scheduled initiation of chromosome replication caused by heat shock with no detectable effect on chromosome copy number.

Chromosomes, Bacterial↗
PubMed1987

The yeast MYO1 gene encoding a myosin-like protein required for cell division.

A yeast gene MYO1 that contains regions of substantial sequence homology with the nematode muscle myosin gene (unc54) has been isolated and sequenced. Although the disruption of MYO1 is not lethal, it leads to aberrant nuclear migration and cytokinesis. The 200-kd myosin heavy chain-like protein, the product of MYO1, cross-reacts with anti-nematode myosin heavy chain IgG and is present in wild-type strains but not in strains carrying the disrupted gene. Instead, a truncated polypeptide with a molecular mass of 120 kd can be detected in some myo1 mutants.

Amino Acid Sequence↗
PubMed1986

Open communication as an effective stress management method for breast cancer patients.

The social and emotional adaptation of 51 breast cancer patients was assessed four times during the first year after mastectomy according to Weissman and Paykel's Social Adaptation Scale (SAS) and judges' ratings. Openness of communication was measured by eight indices during the first two interviews. It was predicted that they would correlate positively with successful adaptation as measured at the third and fourth interviews. Most patients were aware of their diagnosis, and their communication about their plight was found to be multifaceted. Successful copers sought information; less successful copers avoided it. However, where emotions and not facts were the issue, palliative measures such as avoidance of speaking about the threat and refusal to accept its further implications were connected with better adjustment. The findings indicate that palliation is a prerequisite to good instrumental adjustment when the emotional reactions are intense and countermeasures are limited. More research is needed for assessing communication with specific others and change over time.

Adaptation, Psychological↗
PubMed1986

Serum thiamin, pyridoxal, cobalamin and folate concentrations in young infants.

Blood samples were obtained from 509 apparently healthy infants between the age of 3 and 54 weeks attending for routine checks at infant health centres. Serum was assayed for thiamin, pyridoxal, cobalamin and folate. Three hundred and five infants were being breast fed and results from these were used to construct a reference range-thiamin 2-17 micrograms/l, pyridoxal 8-39 micrograms/l, cobalamin 120-800 ng/l and folate 7-47 micrograms/l (95 percentile ranges). One hundred and thirty-four infants were being fed a manufactured milk formulation and the serum concentrations of thiamin, pyridoxal and cobalamin were significantly higher than those found in breast fed infants. Thirteen infants were receiving pasteurized cow's milk. This milk was found to have more than 3 times the folate content of human breast milk yet these infants had a significantly reduced serum level of folate.

Age Factors↗
PubMed1985

Effect of DNA gyrase inactivation on RNA synthesis in Escherichia coli.

The average chain growth rates of rRNA and of total RNA were not affected by a thermal inactivation of DNA gyrase in a temperature-sensitive gyrB mutant of Escherichia coli. The fact that total RNA synthesis decreased under these conditions suggests that transcription is primarily affected at the step of chain initiation. The fraction of rRNA in total pulse-labeled RNA was not altered by inactivation of the enzyme, indicating that the latter is not required to actively maintain a high rate of synthesis of this RNA species.

Escherichia coli↗
PubMed1984

DNA binding and antigenic specifications of DNA gyrase.

Complexes of DNA gyrase and minichromosomal DNA containing the origin of replication of Escherichia coli (oriC) can be formed without metabolic energy and visualised by electron microscopy. The A subunit, part of the A2B2-DNA gyrase complex is the binding protein. Various binding sites are scattered around the minichromosomal DNA including oriC. The minimal origin contains the only prominent and reproducible binding site. Binding to this site is suppressed by oxolinic acid and the ATP analogue beta-y-imido ATP. If gyrase isolated from the gram-positive bacterium Bacillus subtilis is used no binding to oriC is seen. This observation is consistent with antigenic differences between the A subunits of the two microorganisms. The binding to oriC might reflect a requirement for DNA gyrase during the initiation of DNA replication.

Antigen-Antibody Complex↗
PubMed1984

Gene expression in a temperature-sensitive gyrB mutant of Escherichia coli.

The effect of gyrase inactivation on gene expression was studied by examining the activities of different promoters in a temperature-sensitive gyrB mutant of Escherichia coli. The relative activities of promoters affected by cAMP-binding protein (CAP), e.g., the lac promoter, are not reduced by gyrase inactivation but can, on the contrary, be enhanced. This stimulation depends on the promoter location or its structure. The tnaA promoter is activated when located near the origin of replication, suggesting a differential effect of gyrase inactivation on various chromosomal domains. Only silent or mutant promoters such as the non-functional wild-type bgl or the lacIq can be activated. No differential effect of gyrase inactivation on the lambda pL and the trp promoters carried by the phage can be detected.

Bacterial Proteins↗
PubMed1983

Mutagenic repair in Escherichia coli. VIII. Effect of gyrB mutations on ultraviolet light mutagenesis.

Introduction into Escherichia coli WP2 bacteria of a mutation in the gyrB locus previously shown to reduce the degree of chromosomal superhelicity caused a small decrease in the frequency of UV-induced mutations to streptomycin resistance (but not significantly) and to tryptophan independence (mostly ochre suppressors) in excision repair-proficient bacteria. It did not influence the 'broth effect' or the rate or extent of 'mutation frequency decline' of suppressor mutations. In an excision-deficient (uvrA 155) background the yield of UV-induced streptomycin-resistant mutations was lower in gyrB bacteria at all doses; the yield of tryptophan-independent mutations was slightly lower at low doses and slightly higher at high doses. In both excision-proficient and -deficient bacteria the yield of UV-induced mutations to rifampicin resistance was apparently lower in gyrB mutants but this could be due at least in part to a hypersensitivity of some Rifr gyrB bacteria to UV. The number of spontaneous tryptophan-independent mutations was lower in gyrB bacteria but this was almost certainly due to their poorer viability on tryptophan-limiting plates and not to a lower spontaneous mutation rate. In a temperature-sensitive presumed gyrase-deficient strain a small decrease in mutant yield at low doses was observed following incubation at restrictive temperature before UV. This was ascribed to an enhancement of excision repair. Our failure to find any significant effect of gyrB mutations does not support the hypothesis that hairpin formation (which should be dependent on a high degree of superhelicity) is involved in determining the 'broth effect', 'mutation frequency decline' or the probability that a mutation will occur spontaneously. Dramatic effects of superhelicity on UV mutagenesis also seem to be unlikely.

DNA Repair↗