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J Whelan

Publications and source records attributed to J Whelan.

At least 145 records · Page 8Linked to original sources
PubMed1989

Insulin gene enhancer activity is inhibited by adenovirus 5 E1a gene products.

Selective transcription of the insulin gene in pancreatic beta cells is regulated by its enhancer, located within the 5'-flanking region of the insulin gene. Transcription from the enhancer is controlled by both positive- and negative-acting cellular transcription factors. It was previously shown that both the 243- and 289-amino-acid adenovirus type 5 E1a proteins can repress insulin gene transcription in vivo. To localize the insulin DNA sequences involved in this response, we examined the effects of a number of mutations within the 5'-flanking region of the rat insulin II gene on E1a-mediated repression of insulin gene transcription. We have found that E1a proteins inhibit enhancer-stimulated transcription of the insulin gene. The enhancer appears to contain at least two genetically separable and independent E1a target sequence elements. Interestingly, these same regions of the insulin enhancer have been shown to be negatively regulated by cellular transcription factors. These results suggest that E1a-like cellular factors may function in the pancreatic beta-cell-specific expression of the insulin gene.

Adenoviridae↗
PubMed1989

Pancreatic beta-cell-type-specific expression of the rat insulin II gene is controlled by positive and negative cellular transcriptional elements.

The insulin gene is expressed almost exclusively in pancreatic beta-cells. The DNA sequences that control cell-specific expression are located upstream of the transcription initiation site. To identify the cis-acting transcriptional control regions within the rat insulin II gene that are responsible for this tissue-specific expression pattern, we constructed a series of 5'-flanking deletion mutants and analyzed their expression in vivo in transfected insulin-producing and -nonproducing cell lines. Pancreatic beta-cell-specific expression was shown to be controlled by enhancer sequences lying between nucleotides -342 and -91 relative to the transcription start site. The rat insulin II enhancer appears to be a chimera, composed of a number of distinct cis-acting DNA elements. Both positive and negative transcriptional regulatory elements appear to be responsible for this cell-type-specific expression. We have shown that expression from one element within the enhancer, which is found between nucleotides -100 and -91, is regulated by both positive- and negative-acting cellular transcription factors. Expression from chimeras containing only the enhancer element sequences from -100 to -91 were active only in insulin-producing cells, indicating that the positive-acting factor(s) required for this activity may be active only in beta-cells. In contrast to the enhancer region, the rat insulin II gene promoter did not appear to require cell-specific transcription factors. Promoter mutants with 5'-flanking sequences extending to nucleotides -90 and -73 were constitutively active in both insulin-producing and -nonproducing cells. These results suggest that rat insulin II gene transcription in pancreatic beta-cells is imparted by a combination of both negative- and positive-acting cellular factors interacting with the gene enhancer.

Animals↗
PubMed1988

Isolation and characterization of 5-lipoxygenase from tulip bulbs.

An unique membrane bound lipoxygenase was isolated and purified from purple star tulip bulbs with a specific activity of 5.2 mu moles O2 consumed.min-1.mg-1 protein. The purified tulip enzyme exhibits regiospecificity for O2 insertion at C-5 of the arachidonic acid molecule. Identification of the reaction product was confirmed as 5-hydroperoxyeicosatetraenoic acid by analytical criteria which included: cochromatography with the authentic compound, as well as mass spectral and 1H-NMR analysis. Thus, the enzyme from tulip bulbs appears to be different from the cytosolic lipoxygenase from potato tubers, which exhibits non-regiospecificity in terms of O2 incorporation. However, the purified tulip lipoxygenase showed a strong immunological crossreactivity with antiserum raised against the purified potato lipoxygenase, indicating close immunological relationship with the other plant lipoxygenases.

Arachidonate 5-Lipoxygenase↗
PubMed1988

Characteristics of RP4 tellurite-resistance transposon Tn521.

A restriction map of the tellurite-resistance (Ter) transposon Tn521 (parent plasmid RP4Ter) was prepared. Five sites from RP4Ter, including the EcoRI origin, were found in pIN25::Tn521. Tn521 was inserted into a transferable 27.5 kb vector (pCU109) to make three different insertion mutants, in which the size of Tn521 was measured accurately at 4.5 kb. Unlike the Ter of IncHI2 plasmids, that of Tn521 in RP4Ter was non-inducible. Ter was expressed in five widely differing bacterial species to which RP4Ter was transferred from Escherichia coli. Electron micrographs of bacteria expressing the Ter of RP4Ter, H complex plasmids, and chromosomal mutants, all revealed similar tellurium metal crystallites when the bacteria were grown in potassium tellurite medium. No other Ter determinants were found amongst 54 plasmids representing most incompatibility groups (excluding the H complex).

DNA Transposable Elements↗
PubMed1988

Ward sisters' management styles and their effects on nurses' perceptions of quality of care.

The aim of this study was to determine if a ward sister's management style influenced the quality of care received by patients on the ward. The management styles of sisters on 16 oncology wards at the Royal Marsden Hospital were assessed by structured interviews with staff members from each ward. Management styles were classified as high, medium or low on three dimensions, namely socio-emotional orientation, task orientation and pattern of decision making. The quality of patient care was determined by asking all grades of clinical nursing staff to complete a questionnaire. A score for each nurse's perception of the quality of care given on her ward was thus obtained. Correlation of management style and nurse's perception of quality of care indicated that the management style prevalent on a ward influenced the quality of care carried out there. Other factors that influence both management style and quality of care were identified. Suggestions for improving the quality of care given on a ward are thus identified.

Humans↗
PubMed1986

pIN32: a cointegrate plasmid with IncHI2 and IncFII components.

An Enterobacter cloacae strain isolated from the faeces of a child with diarrhoea in Indonesia contained a transferable 216 MDa plasmid, pIN32, exhibiting IncHI2 phenotypic characters, including temperature sensitivity of transfer and the expression of H serotype pili at a repressed level. A derivative plasmid (pIN32-1), which had lost the IncHI2 phenotype, and contained only 60 MDa of the original replicon, was obtained after mating at 37 degrees C. It was IncFII, showed regions of homology with plasmid R100, determined IncFII serotype conjugative pili constitutively and was transfer-derepressed. After overnight growth at 37 degrees C in non-selective medium, pIN32 gave rise to another derivative, pIN32-2 (size 184.3 MDa), which retained the IncHI2 phenotype and several other pIN32 characters.

Child↗
PubMed1985

Conjugation systems of IncT plasmids.

Four IncT plasmids were compared for various characters, in particular pilus synthesis and function at different temperatures. The prototype Rts1 differed in some respects from the others (R402, R394, pIN25). At 37 degrees C, the supposedly temperature-sensitive conjugation systems of the plasmids could still function efficiently on a surface, but not in a liquid. Long conjugative pili were synthesized at 30 degrees C, but only short ones (approx. 200 nm) were produced at 37 degrees C. The long pili converted two surface-obligatory conjugation systems to surface + liquid ones at 30 degrees C.

Conjugation, Genetic↗
PubMed1982

The medical and anaesthetic management of acromegalic patients undergoing maxillo-facial surgery.

Three acromegalic patients are described in whom successful surgical correction of the prognathism was performed. No immediate post-operative upper respiratory tract obstruction nor cardiac dysrrhythmias occurred as have been reported in previously recorded cases. It is suggested that particular attention be paid to the recognition and prevention of these complications. In addition we believe that initial treatment should be directed to the achievement of as near normal growth hormone levels as possible for at least a year before maxillo-facial surgery so that there may be maximal soft tissue regression and reduction of airway hazards and cardiac embarrassment.

Acromegaly↗
PubMedDate not supplied

Detection of single-base mutations in a mixed population of cells: a comparison of SSCP and direct sequencing.

Single-base-pair changes in several genes have been shown to be important in carcinogenesis. We have compared the sensitivity of two commonly used techniques for detection of single-base-pair changes. Defined populations of cells were prepared by mixing wild-type Chinese hamster ovary cells with cells carrying a known mutation in the CTP synthetase gene. RNA was extracted and analyzed for the mutation by single-strand conformational polymorphism and direct sequence analysis of polymerase chain reaction products. We found that both techniques were able to detect the mutation when it was present in 25% of the cells, but that direct sequencing was slightly more sensitive and able to detect the mutation when it was present in only 20% of the population.

Animals↗
PubMedDate not supplied

Validating facemask use for gas exchange analysis in patients with congestive heart failure.

PURPOSE: Functional limitation, often associated with congestive heart failure (CHF), is most accurately assessed with measurement of peak VO2 (VO2peak) during exercise testing. VO2peak strongly predicts survival in CHF patients and is used to triage patients for cardiac transplantation. However, the traditional mouthpiece/noseclip equipment used for gas exchange analysis is often cumbersome and uncomfortable. Several alternative facemask designs tested previously in healthy cohorts were inferior to the mouthpiece for measuring VO2peak. In this study, a series of facemasks designed specifically for VO2peak testing (Hans-Rudolph) was employed. Although previously validated in healthy young adults, this apparatus has not been validated in patients with severe CHF. METHODS: The Hans-Rudolph facemasks were compared with the mouthpiece apparatus in 30 patients with severe CHF. Each subject completed a cardiopulmonary exercise test with each device. Twelve subjects were randomized to evaluate a possible training effect. To enhance recruitment, 18 additional subjects were recruited after they had completed a test with the mouthpiece. RESULTS: There was no evidence of a training effect and no differences in gas exchange measurements were found between the two devices. The weight-adjusted VO2peak measurements were 17.1 +/- 5.3 ml O2/kg/min for the mouthpiece group and 17.3 +/- 5.6 ml O2/kg/min for the mask group (P = 0.54). CONCLUSIONS: The facemask was shown to be equivalent to the mouthpiece for measuring VO2peak in CHF patients. Concerns of hypoventilation and decreased VO2peak associated with previous facemask designs were not substantiated. Since successful exercise testing depends on maximal exertion, providing a choice of equipment may facilitate cooperation without sacrificing accuracy.

Adult↗