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S Hayes

Publications and source records attributed to S Hayes.

At least 73 records · Page 4Linked to original sources
PubMed1993

Multicolor FISH mapping with Alu-PCR-amplified YAC clone DNA determines the order of markers in the BRCA1 region on chromosome 17q12-q21.

A gene designated BRCA1, implicated in the susceptibility to early-onset familial breast cancer, has recently been localized to chromosome 17q12-q21. To date, the order of DNA markers mapped within this region has been based on genetic linkage analysis. We report the use of multicolor fluorescence in situ hybridization to establish a physically based map of five polymorphic DNA markers and 10 cloned genes spanning this region. Three cosmid clones and Alu-PCR-generated products derived from 12 yeast artificial chromosome clones representing each of these markers were used in two-color mapping experiments to determine an initial proximity of markers relative to each other on metaphase chromosomes. Interphase mapping was then employed to determine the order and orientation of closely spaced loci by direct visualization of fluorescent signals following hybridization of three probes, each detected in a different color. Statistical analysis of the combined data suggests that the order of markers in the BRCA1 region is cen-THRA1-TOP2-GAS-OF2-17HSD-248yg9-RNU 2-OF3-PPY/p131-EPB3-Mfd188- WNT3-HOX2-GP3A-tel. This map is consistent with that determined by radiation-reduced hybrid mapping and will facilitate positional cloning strategies in efforts to isolate and characterize the BRCA1 gene.

Breast Neoplasms↗
PubMed1993

Mapping of a major surface-exposed site in herpes simplex virus protein Vmw65 to a region of direct interaction in a transcription complex assembly.

The cellular factor Oct-1 is selectively recruited, together with at least one other cellular protein (CFF), into a multicomponent transcription complex whose assembly is directed by the herpes simplex virus regulatory protein Vmw65 (VP16). The acidic carboxy terminus of Vmw65 is not involved in assembly of the complex but is absolutely required for subsequent transcriptional activation. Elucidation of the mechanism of action of Vmw65 is important for an understanding not only of combinatorial control of gene expression by POU- and homeodomain proteins but also of the interaction(s) between activation domains of regulatory proteins and components of the basal transcriptional apparatus. We used a combination of limited proteolysis with a number of site-specific proteases and immunological detection to demonstrate the presence of two main surface-exposed regions in Vmw65. We mapped these sites to within a few amino acids at positions 365-370 408/409. The site at 408/409 is indicative of a flexible exposed linker region between the acidic carboxy-terminal activation domain (residues 430-480) and an N-terminal domain involved in complex formation with the two cellular factors. The site around residues 365-370 is precisely within a region that results from this and other laboratories have shown to be critical for complex formation. Furthermore, we show that this site is selectively protected from proteolysis after complex assembly. Finally, using a series of overlapping peptide encompassing this region, we show that the eight amino acids, R-E-H-A-Y-S-R-A, from positions 360 through 367 are sufficient to inhibit complex formation by intact Vmw65. We propose that these residues contain sufficient information to selectively bind one of the cellular partners involved in complex assembly and that these residues are located in a physical surface-exposed domain of the protein.

Amino Acid Sequence↗
PubMed1992

Working hours: an employer's duty.

Recent EC negotiations on the Working Time Directive have shown UK thinking to be at odds with the rest of Europe. Susan Hayes examines the implications for employee health.

Employment↗
PubMed1991

Mapping ethanol-induced deletions.

Chromosomal rearrangements, uniformly represented by very large deletions, were stimulated upon transiently exposing Escherichia coli cells with a defective lambda prophage to about 18% (v/v) ethanol. It was shown that the ethanol treatment induced deletion formation rather than enriching for ethanol-tolerant cells. The deletions in 435 mutants were mapped to 26 groups. Ethanol treatment changed the spectrum of deletions relative to those arising spontaneously, and stimulated the formation of deletions with endpoints in E. coli DNA flanking the lambda fragment. The promotion of deletion formation by ethanol involves the joining of distant, nonhomologous linear DNA segments, which can be considered an illegitimate recombination event; however, activity of the E. coli recA gene product was also required. Although spontaneous deletions arose in comparable cells defective for recA, the incidence of deletion formation in recA cells was not altered by ethanol. It is proposed that ethanol stimulates chromosomal rearrangements involving two oppositely oriented replication forks, since the localized deletions commonly removed or inactivated the chromosomal segment including the bidirectional lambda origin of replication. The results imply a novel mutagenic process induced by an agent that does not act directly on DNA.

Bacteriophage lambda↗
PubMed1990

Alcohol treatment of defective lambda lysogens is deletionogenic.

We ascertained that transient exposure to ethanol, above 18%, was deletionogenic to an Escherichia coli strain with a fragment (12.5 kb) of bacteriophage lambda integrated within the chromosome. The lambda attL B.P' through P fragment provided a forward selection for mutants, and a target for mutagenesis. The cells were killed by thermal derepression of transcription and replication of the lambda fragment when transferred from 30 degrees to 42 degrees C. Survivor mutants, capable of forming colonies at 42 degrees C, were selected from untreated starting cells. About half no longer supported marker rescue of the lambda fragment imm lambda (immunity) region, comprising the cI repressor, and the PL and PR promoters. Ethanol treatment of starting cells increased the occurrence of imm lambda-defective clones to near 100%. The mutations responsible for the imm lambda defect were found to be large deletions (12 kb or more of DNA). Ethanol treatment of the starting cells also produced a 5- to 18-fold increase in the occurrence of E. coli pgl mutations, which likely arose by the deletion mechanism generating the imm lambda defects, since pgl was closely linked to the integrated lambda fragment. A unifying hypothesis for these observations was that ethanol was deletionogenic. The inclusion or substitution of the int-kil segment of the lambda fragment produced no real change in the spontaneous occurrence of large imm lambda deletions from the untreated cells. Substitution of this segment suppressed the deletionogenic effect of ethanol, implying a prerequisite for sequence homology or gene function from this interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriophage lambda↗
PubMed1990

Stimulation of mutations suppressing the loss of replication control by small alcohols.

Transient exposure of lysogenic Escherichia coli cells to small alcohols stimulated the frequency of mutations suppressing the lethal loss of replication control from a prophage fragment of bacteriophage lambda. The stimulation in mutation frequency paralleled the effect of mutagenic agents, and in this sense the alcohols behaved as mutagens. 10-min treatments above distinct threshold concentrations at 23%, 18%, 10% and 4% (v/v) were required in order for methanol, ethanol, isopropanol and propanol to evoke mutagenic effects. The selected mutant cells were, in general, equally or more sensitive to ethanol than the starting cells. The mutagenicity of methanol and ethanol was detected only with E. coli strains with lambda fragments that included the site-specific and general recombination genes found within the phage int-kil gene interval; whereas, stimulation of the frequency of phenotypically identical mutations by nitrosoguanidine or ionizing radiation did not require that the lambda fragment encode these genes. Treatments of lysogenic cells with mutagenic concentrations of ethanol did not trigger prophage induction and were concluded not to induce a cellular SOS response nor to denature the prophage repressor, or to disrupt repressor-operator binding. The toxicity of ethanol was pH-dependent. Cellular sensitivity to ethanol toxicity was unaffected by the integrated lambda fragment(s) or by an intact lambda prophage; but, it was increased by deletions of the E. coli chromosome extending rightward from bio into uvrB, and rightward from chlA.

1-Propanol↗
PubMed1988

What are the 'best' measurements for monitoring patients during short-term second-line therapy?

Seventy-one patients with active rheumatoid arthritis were treated with one of five second-line agents and monitored for 24 weeks using seven clinical and seven laboratory measurements. Statistical tests were used to determine which measures changed fastest, which changed most and which most closely reflected changes in the others. The results consistently showed that articular index and summated change score were the 'best' clinical measures while ESR and plasma viscosity were the 'best' laboratory measures. Traditional measures such as grip strength and joint size fared badly and cannot be recommended. Clinical variables improved slightly more rapidly than laboratory measures, but the latter showed the greater change.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1987

The generic shoe: a prescription tool.

A multiple-use testing shoe capable of various orthotic modifications has been developed. Its use in predicting prescription performance and patient compliance is presented. Patient compliance is enhanced by understanding gained through the testing procedure.

Biomechanical Phenomena↗
PubMed1987

pK1' and bicarbonate concentration in plasma.

Values for pK1' were determined from pH measured at 37 degrees C with three blood-gas analyzers and from calculated pco2 values in 443 freshly separated plasmas, tonometered at 37 degrees C. Plasma was taken from healthy volunteers, seriously ill patients, and hyponatremic patients. pK1' values varied by considerably more than 0.06 in healthy volunteers as well as in very ill patients, and bicarbonate concentrations ([HCO3]p) calculated by blood-gas analyzers based on the pK1' value of 6.1 could be in error by some +/- 60%. pK1' was similarly determined for tonometered (37 degrees C) replicate dilutions of plasma samples. By adding weighed amounts of dry NaCl and NaHCO3 to the diluted samples we increased the Na+ concentration to approximately 150 mmol/L and bicarbonate concentrations to values ranging from approximately 2.5 to approximately 52.5 mmol/L. pK1' values decreased when [HCO3]p was increased in dilutions of plasma kept at constant ionic strength. At any given [HCO3]p, pK1' values were higher at high than at low values of pco2.

Bicarbonates↗
PubMed1986

Spontaneous lambda OR mutations suppress inhibition of bacteriophage growth by nonimmune exclusion phenotype of defective lambda prophage.

Survivor clones with defects in gene functions that participate in the replicative killing of thermally induced Escherichia coli constructs with integrated lambda N through P or cIII through P gene fragments were selected at a frequency of about 10(-6). Among the population of survivors, clones were identified that exhibited normal lambda immunity at 30 degrees C, as shown by their ability to prevent the plating of lambda wild type and to support the plating of a nearly identical heteroimmune bacteriophage lambda imm434. However, when placed at 42 degrees C to inactivate the cIts857 repressor, these survivor isolates excluded the plating of both lambda wild-type and lambda imm434 phages, a phenotype designated nonimmune exclusion (Nie). Spontaneous mutants of lambda wild type were isolated that overcame the Nie phenotype and would plaque at 42 degrees C on cell lawns of these isolates. The acquired lambda se mutations suppressed nonimmune exclusion, prevented lysogenization by interrupting repressor expression from PRM, and made the phage insensitive to replicative inhibition. The se mutations were genetically mapped and sequenced within the rightward lambda operator site.

Bacteriophage lambda↗
PubMed1985

Nephrotic syndrome with renal vein thrombosis: pathogenetic importance of a plasmin inhibitor (alpha 2-antiplasmin).

Tests of fibrinolysis were measured by fibrin plate methods in 44 patients with nephrotic syndrome, in 14 of whom renal vein thrombosis was demonstrated. In both groups the level of total fibrinolytic activity was normal, that of vascular plasminogen activator was decreased, and that of an inhibitor of plasminogen activation was elevated. The level of a plasmin inhibitor, measured by the fibrin plate method, was elevated in 13 of 14 patients with, but only in 12 of 30 without, renal vein thrombosis (p less than 0.005). The plasmin inhibitor was identical with alpha 2-antiplasmin. The data suggest that an increased level of alpha 2-antiplasmin may be a factor in determining susceptibility to the development and persistence of renal vein thrombosis in patients with nephrotic syndrome.

Fibrinolysis↗
PubMed1984

RK bacterial test for independently measuring chemical toxicity and mutagenicity: short-term forward selection assay.

A short-term bacterial assay system for determining the mutagenic potential of environmental substances was developed and validated. Genotoxic activity was demonstrated for selected substances from 10 categories of chemical agents. The RK test results were obtained with one Escherichia coli assay strain that was transiently exposed to, and then removed from the test substance prior to the selection step for mutant cells. The RK test employs a hitherto unused short-term assay technique for selecting forward mutations in the wild-type selector strain cells. The cells of the selector strain are killed upon shifting to 42 degrees C as a consequence of thermal derepression and subsequent expression of the replication genes from an integrated 10-kilobase fragment of phage lambda. Cells that acquire mutations in the responsible killing genes are detected by their colony-forming ability at 42 degrees C. A substance is determined to be genotoxic if it is capable of increasing the forward mutation frequency for appearance of these mutant cells. Toxicity of the agent is independently evaluated by examining its effect on the viability of the selector strain at 30 degrees C, when the viral replication genes remain repressed. The flexible assay protocol enables determination of the effect of pH on mutagenic activity, the requirement for metabolic activation, and assays of nearly insoluble or highly toxic substances.

Biotransformation↗