PubMed Health⌕ Search

Biomedical subjects

M Hirst

Publications and source records attributed to M Hirst.

At least 19 recordsLinked to original sources
PubMed2002

Transitions to informal care in Great Britain during the 1990s.

OBJECTIVES: To estimate annual changes and trends in the population of informal carers and to investigate transitions to caregiving by age, gender, locus of care, and level of involvement. DESIGN: Longitudinal analysis of data from the British household panel survey, 1991 to 1998, an annual prospective survey of a nationally representative sample of more than 5000 private households in England, Scotland, and Wales. SUBJECTS: Over 9000 adults over 16 years interviewed personally in successive waves of the survey, including around 1300 informal carers each year. RESULTS: One third of co-resident carers and 40% of extra-resident carers start caregiving each year and similar proportions cease to provide care. Five year period rates are at least 75% higher than the one year prevalence estimates. Almost everyone is involved in caregiving at one time or another and over half are likely to provide 20 hours or more care per week at some point in their lives. Recent trends indicate that more adults are becoming heavily involved in providing longer episodes of care. Although the onset of caregiving peaks in late middle and early older age, above average incidences span three decades or more of adult life. Age variations in the start of caring relationships are driven by the changing demands for care within and between generations over the life course. There is no firm evidence that carers increase their involvement in caring activities over the first three years of a caring episode. CONCLUSIONS: The population of carers is constantly changing as some people stop providing care and others take on a caring role or vary their level of involvement. Policy measures responsive to the diversity of caring roles, and geared around key transitions, are likely to be most effective in supporting carers through changing circumstances. Recognition and support for carers who are heavily involved in caring activities from the outset should be a priority.

Adolescent↗
PubMed2001

A two-hybrid system for transactivator bait proteins.

We describe a two-hybrid strategy for detection of interactions with transactivator proteins. This repressed transactivator (RTA) system employs the N-terminal repression domain of the yeast general repressor TUP1. TUP1-GAL80 fusion proteins, when coexpressed with GAL4, are shown to inhibit transcription of GAL4-dependent reporter genes. This effect requires the C-terminal 30 residues of GAL4, which are required for interaction with GAL80 in vitro. Furthermore, repression of GAL transcription by TUP1-GAL80 requires SRB10, demonstrating that the TUP1 repression domain, in the context of a two-hybrid interaction, functions by the same mechanism as endogenous TUP1. Using this strategy, we demonstrate interactions between the mammalian basic helix-loop-helix proteins MyoD and E12, and between c-Myc and Bin-1. We have also identified interacting clones from a TUP1-cDNA fusion expression library by using GAL4-VP16 as a bait fusion. These results demonstrate that RTA is generally applicable for identifying and characterizing interactions with transactivator proteins in vivo.

Animals↗
PubMed2001

Trends in informal care in Great Britain during the 1990s.

The population of adult carers in Great Britain declined during the 1990s while the proportion of those heavily involved in providing informal care increased. The intensification of care-giving was associated with an increasing number of caring relationships that typically make heavy demands on the carer: spouse care and caring for a child or parent. The provision of informal care by friends and neighbours diminished resulting in an overall decline in care-giving between households. However, parents were increasingly looked after in their own homes by non-resident daughters. More women than men withdrew from the less intensive care-giving between households while more men than women took on the role of a spouse carer. By the end of the decade, as many men as women provided informal care for a spouse or partner. If the trends identified here continue beyond the study period, increasing resources will be required to identify heavily involved carers, assess their needs, and support them in their caring activities. The findings are based on secondary analysis of the British Household Panel Survey covering the years 1991-1998. As well as charting trends in the prevalence of informal care, changes in the locus of care, the number of care recipients, their relationship to their carer and the amount of time devoted to caring activities are described and interpreted.

Adult↗
PubMed1999

GAL4 is regulated by the RNA polymerase II holoenzyme-associated cyclin-dependent protein kinase SRB10/CDK8.

Phosphorylation of the yeast transcription factor GAL4 at S699 is required for efficient galactose-inducible transcription. We demonstrate that this site is a substrate for the RNA polymerase holoenzyme-associated CDK SRB10. S699 phosphorylation requires SRB10 in vivo, and this site is phosphorylated by purified SRB10/ SRB11 CDK/cyclin in vitro. RNA Pol II holoenzymes purified from WT yeast phosphorylate GAL4 at sites observed in vivo whereas holoenzymes from srb10 yeast are incapable of phosphorylating GAL4 at S699. Mutations at GAL4 S699 and srb10 are epistatic for GAL induction, demonstrating that SRB10 regulates GAL4 activity through this phosphorylation in vivo. These results demonstrate a function for the SRB10/ CDK8 holoenzyme-associated CDK that involves regulation of transactivators by phosphorylation during transcriptional activation.

Animals↗
PubMed1999

Is ethanol an important antioxidant in alcoholic beverages associated with risk reduction of cataract and atherosclerosis?

It has been reported in the epidemiological literature that cataract, stroke, and atherosclerosis risk is reduced by 50% in people consuming one alcoholic drink per day. Peroxide has been implicated as a causative agent in cataractogenesis, and LDL oxidation appears to play a role in atherosclerosis. The antioxidant activity of alcohol was measured by: (i) use of a luminescent assay developed in our laboratory, confirmed as appropriate; (ii) electron spin resonance (ESR) spin-trapping; and (iii) copper-catalysed oxidation of LDL and VLDL from hamsters fed 6% ethanol in their drinking water. Ethanol reduced the luminescent counts/min from peroxide and superoxide. It significantly reduced the spin-trapped signal of hydroxyl radical, but not the superoxide signal. Other alcohols also showed large reductions in counts from hydrogen peroxide. Plasma from hamsters fed 6% ethanol had lower lipid peroxides and the oxidizability of LDL and VLDL was significantly reduced compared to controls. These data provide a possible explanation for the effect of beverages containing ethanol in the reduction of cataract and atherosclerosis risk observed in human population studies.

Alcohol Drinking↗
PubMed1998

Mapping a protein-binding site on straightened DNA by atomic force microscopy.

We have developed an Atomic Force Microscopy (AFM)-based method for mapping protein-binding sites on individual, long DNA molecules (> 5 kb) at nanometer resolution. The protein is clearly detected at the apex of the bent DNA molecules. Randomly coiled DNA molecules or protein:DNA complexes were extended by a motor-controlled moving meniscus on an atomically flat surface. The immobilized molecules were detected by AFM. The straightened DNA displayed a sharp bend at the site of bound protein with the two DNA segments linearly extending from the protein-binding site. Using GAL4, a yeast transcription factor, we demonstrate good agreement of the position of the observed binding site on straightened DNA templates to the predicted binding site. The technique is expected to have significant implications in elucidating DNA and protein interactions in general, and specifically, for the measurement of promoter occupancy with unlabeled regulatory proteins at the single-molecule level.

Aluminum Silicates↗
PubMed1998

N,N-Dimethylformamide modulates acid extrusion from murine hepatoma cells.

N,N-Dimethylformamide (DMF) affects cellular differentiation, causes hepatotoxicity and gastric irritation, and may be carcinogenic. Since these processes involve changes in cellular pH homeostasis, we investigated the effects of DMF on H+ extrusion and cytosolic pH (pHi) of mouse hepatoma cells (Hepa 1C1C7). Extracellular pH was monitored using a silicon-based sensor system (Cytosensor microphysiometer) and pHi was monitored by fluorescence spectrophotometry. Superfusion of cells with DMF (0.25 to 0.5 M) suppressed the extracellular acidification rate (ECAR) below baseline. Following washout of DMF there was a rapid, concentration-dependent, prolonged overshoot of ECAR above baseline rates. Removal of extracellular Na+ or superfusion with amiloride abolished the overshoot in acidification rate, indicating involvement of Na+/H+ exchange. The overshoot was dependent on extracellular glucose, suggesting that it arises from an increase in metabolic acid production. Fluorescence measurements showed that DMF did not change pHi. Furthermore, DMF did not alter the rate of pHi recovery of cells acid loaded using nigericin, indicating that DMF does not directly alter Na+/H+ exchange activity in these cells. In summary, these data suggest that suppression of acidification rate by DMF is likely due to decreased metabolic acid production. Washout of DMF is then accompanied by increased glucose metabolism and H+ efflux via Na+/H+ exchange. It is possible that alterations in H+ production and transport contribute to the hepatotoxicity of DMF and its effects on cellular differentiation.

Amiloride↗
PubMed1998

Naturally occurring human immunodeficiency virus type 1 long terminal repeats have a frequently observed duplication that binds RBF-2 and represses transcription.

Approximately 38% of human immunodeficiency virus type 1 (HIV-1)-infected patients within the Vancouver Lymphadenopathy-AIDS Study have proviruses bearing partial 15- to 34-nucleotide duplications upstream of the NF-kappaB binding sites within the 5' long terminal repeat (LTR). This most frequent naturally occurring length polymorphism (MFNLP) of the HIV-1 5' LTR encompasses potential binding sites for several candidate transcription factors, including TCF-1alpha/hLEF, c-Ets, AP-4, and Ras-responsive binding factor 2 (RBF-2) (M. C. Estable et al., J. Virol. 70:4053-4062, 1996). RBF-2 and an apparently related factor, RBF-1, bind to at least four cis elements within the LTR which are required for full transcriptional responsiveness to protein-tyrosine kinases and v-Ras (B. Bell and I. Sadowski, Oncogene 13:2687-2697, 1996). Here we demonstrate that representative MFNLPs from two patients specifically bind RBF-2. In both cases, deletion of the MFNLP caused elevated LTR-directed transcription in cells expressing RBF-2 but not in cells with undetectable RBF-2. RBF-1, but not RBF-2, appears to contain the Ets transcription factor family member GABPalpha/GABPbeta1. Taken together with the fact that every MFNLP from a comparative study of over 500 LTR sequences from 42 patients contains a predicted binding site for RBF-2, our data suggest that the MFNLP is selected in vivo because it provides a duplicated RBF-2 cis element, which may limit transcription in monocytes and activated T cells.

DNA Replication↗
PubMed1998

Were practice nurses distributed equitably across England and Wales, 1988-1995?

OBJECTIVE: To examine whether variations in the number of whole-time equivalent (wte) practice nurses across family health services authorities (FHSAs) can be explained by population characteristics and the organisation of general practice. METHODS: Analysis of nine health and 16 social indicators for 98 FHSAs identified three factors underlying health care needs. These factors and seven practice characteristics were analysed by stepwise regression. A formula for allocating health care resources and a logistic growth model were used to estimate the 'expected' number of nurses. RESULTS: Past trends indicate an eventual (wte) practice nurse workforce of 12,500 (95% CI +/- 3500). Although geographical disparities have declined, there was a two-fold variation in nurse numbers across FHSAs. Around 2000 (wte) posts would be required to bring under-provided areas, mostly in northern England and metropolitan districts, up to the highest level of provision. There were more nurses in areas with higher proportions of elderly people but fewer where deprivation, morbidity and mortality levels were above average. The number of general practitioners was the most significant predictor of practice nurse provision (t = 5.0); population needs and practice characteristics explained 24% of the variation. CONCLUSIONS: The distribution of practice nurses scarcely corresponded with health care needs at the FHSA level. Despite a lack of evidence that nurses are a cost-effective addition to the primary health care team, their role and numbers will be driven by the extent to which they take on responsibilities performed by doctors. Achieving equity in practice nurse provision probably requires explicit consideration in a formula for allocating primary care funds, backed by audit of the services they provide.

Community Health Planning↗
PubMed1998

Enantioselective, mechanism-based inactivation of guinea pig hepatic cytochrome P450 by N-(alpha-methylbenzyl)-1-aminobenzotriazole.

N-Aralkylated derivatives of 1-aminobenzotriazole are well-established, mechanism-based inhibitors of cytochrome P450 (CYP or P450). In this study, the kinetics of inactivation of CYP2B-dependent 7-pentoxyresorufin O-depentylation (PROD) and CYP1A-dependent 7-ethoxyresorufin O-deethylation (EROD) activities by enantiomers of N-(alpha-methylbenzyl)-1-aminobenzotriazole (alphaMB) were compared. The racemic mixture (+/-)-alphaMB, as well as the enantiomers (-)-alphaMB and (+)-alphaMB, produced a time-, concentration-, and NADPH-dependent loss of PROD and EROD activity in hepatic microsomes from phenobarbital-treated guinea pigs. The rates of PROD inactivation by (-)-alphaMB were significantly faster than for (+)-alphaMB. Consistent with this, the derived maximal kinact was also significantly greater for (-)-alphaMB than for (+)-alphaMB (0.49 vs. 0.35 min-1). In contrast, the concentrations required for the half-maximal rate of inactivation (Ki) were equivalent for (-)-alphaMB and (+)-alphaMB, whereas the degree of competitive inhibition of PROD activity was greater for (+)-alphaMB. No significant differences were found among (-)-alphaMB, (+)-alphaMB, and (+/-)-alphaMB with respect to mechanism-based inactivation (kinact = 0.18, 0.16, and 0.17 min-1, respectively) or competitive inhibition of EROD activity. No differences were found for the maximal extent of PROD or EROD inhibition or the loss of spectral P450 after an extended 30-min incubation with the inhibitors. We conclude that mechanism-based inactivation of guinea pig CYP2B, but not CYP1A, isozymes by alphaMB occurs in a stereoselective manner, most likely as a result of a difference in the balance between metabolic activation and deactivation for the alphaMB enantiomers.

Animals↗
PubMed1997

Staying single in the 1990s: single-handed practitioners in the new National Health Service.

The U.K. health care system is organised around independent medical practitioners who work in community settings and act as gatekeepers for acute health interventions. Recent developments in U.K. health policy have revolutionised the environment within which all general medical practitioners (GPs) operate. The last five years in the U.K. have seen the most fundamental health service reforms since the inception of the National Health Service (NHS) in 1946: namely, the development of the internal market, an increasing emphasis on primary health care, and changes to the GP Contract in 1990. Single-handed GPs (practitioners not in partnership with other GPs) traditionally work in the most deprived areas with the greatest health and social problems. The current restructuring and the subsequent organisational and policy initiatives present particular problems for single-handed practitioners. How single-handed practitioners respond to the reforms raises particularly important debates that are significant both for themselves and for the populations they serve. Drawing upon a range of sources, this paper discusses three central issues that emerge. First, how do single-handed practices relate to the more managerial role envisaged for authorities responsible for supporting primary health care? Second, given the development of the internal market, how do single-handed practices fare in influencing local policy and priority setting? Third, to what extent can single-handed practitioners take advantage of the opportunities to hold their own budgets? Overall, in the context of recent U.K. health care reforms, what is the future for "staying single in the 1990s"?

Family Practice↗
PubMed1997

Clinical, cytogenetic, and molecular analysis of three families with FRAXE.

The probe StB12.3 has been used to screen the FMR-1 gene in 42 pedigrees with a distal Xq fragile site for expansion of the CCG repeat and aberrant methylation of the FRAXA locus. Four families did not have a FRAXA mutation and were investigated further. Fluorescent in situ hybridisation (FISH) and molecular analyses showed that three of these families had an expansion at FRAXE and one at FRAXE. Detailed psychiatric, psychological, and behavioural features of three families with FRAXE identified in the study are presented. All the males who expressed FRAXE had a large methylated CCG repeat at FRAXF. All males with the mutation had some degree of mental handicap. This study illustrates the need for the FRAXE phenotype to be defined further.

Adult↗
PubMed1996

The prevalence of pain in a disabled population.

An estimated 1.7 million disabled adults (95% CI +/- 74,000), living in private households in Great Britain, reported pain symptoms which severely affected their daily activities. That is, the pain they experienced is so severe, unrelieved and recurring as to limit or prevent their ability to perform ordinary, everyday, activities. They represent 30% of disabled adults suggesting that pain is a substantial cause of disability and a major public health problem. The prevalence of severely limiting pain increased with age declining beyond age 55 though younger disabled adults, and women generally, reported more severe pain symptoms. Pain was associated with disabilities which commonly have a physical origin and directly affect bodily movement, compounding the problems of daily living for this population. Three-quarters of those whose lives were limited by pain said the worst bouts of pain occurred at least once a week; half took analgesic medicine every day. More than nine out of ten disabled people suffering pain had recent contact with primary and community health or hospital services.

Activities of Daily Living↗
PubMed1996

Psychoactive constituents of the genus Sceletium N.E.Br. and other Mesembryanthemaceae: a review.

The use by the Khoisan of South Africa of Sceletium plants in psychoactive preparations has often been alluded to in the literature. However, much of it is fragmentary and contradictory. The current review reassembles the historical data recorded over a 300-year period, describes techniques for the preparation and use of "kougoed' from plants of Sceletium and documents the subjective experiences of a number of contemporary users. Apart from chewing the dried product, after "fermentation', there are reports of uses as tinctures for sedation and analgesia, chewing the material directly and smoking the residue after chewing. The symbolic connections of Sceletium with eland antelopes, the "trance animals' par excellence of the San hunter-gatherers is noted. Observations by Paterson (1789) and reports of contemporary users indicate a synergism and potentiation with smoked Cannabis. There is no evidence to support the view that "kougoed' or Sceletium alkaloids are hallucinogenic. The alkaloid distribution in Sceletium and other members of the family Mesembryanthemaceae are considered. Chemical studies have indicated as many as nine alkaloids in Sceletium which fall into three distinct structural categories. Mesembrine, the alkaloid first isolated and named is not the dominant constituent of plants and is weakly narcotic. Evidence is assembled to suggest that traditional and contemporary methods of preparation serve to reduce levels of potentially harmful oxalates, which are found in Sceletium and other Mesembryanthemaceae. It is concluded that there is a need for further pharmacological studies on these alkaloids, based on their narcotic-anxiolytic properties, strong synergism with other psychomimetics, moderate toxicity and anti-cancer activity.

Alkaloids↗
PubMed1995

Two new cases of FMR1 deletion associated with mental impairment.

Screening of families clinically ascertained for the fragile X syndrome phenotype revealed two mentally impaired males who were cytogenetically negative for the fragile X chromosome. In both cases, screening for the FMR1 trinucleotide expansion mutation revealed a rearrangement within the FMR1 gene. In the first case, a 660-bp deletion is present in 40% of peripheral lymphocytes. PCR and sequence analysis revealed it to include the CpG island and the CGG trinucleotide repeat, thus removing the FMR1 promoter region and putative mRNA start site. In the second case, PCR analysis demonstrated that a deletion extended from a point proximal to FMR1 to 25 kb into the gene, removing all the region 5' to exon 11. The distal breakpoint was confirmed by Southern blot analysis and localized to a 600-bp region, and FMR1-mRNA analysis in a cell line established from this individual confirmed the lack of a transcript. These deletion patients provide further confirmatory evidence that loss of FMR1 gene expression is indeed responsible for mental retardation. Additionally, these cases highlight the need for the careful examination of the FMR1 gene, even in the absence of cytogenetic expression, particularly when several fragile X-like clinical features are present.

Adult↗
PubMed1994

Human GMP synthetase. Protein purification, cloning, and functional expression of cDNA.

GMP synthetase is a key enzyme in the de novo synthesis of guanine nucleotides. Human GMP synthetase has been purified to homogeneity, and a cDNA encoding the enzyme has been isolated from the T-lymphoblastoma cell line, A3.01. The open reading frame encodes a protein of 693 amino acids with a predicted molecular weight of 76,725. The cDNA complements a guaA mutant of Escherichia coli, which lacks a functional GMP synthetase and extracts from the transformed E. coli exhibit GMP synthetase activity, which is absent in the parental strain. RNA hybridization analysis shows that human GMP synthetase is encoded by a single 2.4-kilobase message. DNA hybridization analysis suggests that the human GMP synthetase is encoded by one gene. In several human cell lines, the level of mRNA expression is substantially higher in proliferating, transformed cells than in nontransformed cells. In two transformed cell lines, treatment with phorbol ester inhibits proliferation and results in a dramatic down-regulation in the levels of GMP synthetase mRNA and protein.

Amino Acid Sequence↗
PubMed1994

Deoxynivalenol (vomitoxin)-induced conditioned taste aversions in rats are mediated by the chemosensitive area postrema.

The present experiments used a conditioned aversion to a novel saccharin taste to assess the aversive effects of deoxynivalenol (vomitoxin) administration, and to examine the putative mediating role of the chemosensitive area postrema (AP). In experiment 1 adult male rats drank a novel 0.15% saccharin solution followed by injection of deoxynivalenol (n = 7; 0.125 mg/kg, IP) or vehicle (n = 7; propylene glycol, 0.5 ml/kg). In subsequent two-bottle preference tests the rats conditioned with deoxynivalenol displayed significantly (p < 0.01) lower absolute and relative saccharin intake levels in comparison to control rats which exhibited a strong preference for saccharin solution. In experiment 2 adult male rats received area postrema ablations (n = 6) or sham lesions (n = 6). On two conditioning days all rats drank a novel 0.15% saccharin solution followed by injections of deoxynivalenol (0.125 mg/kg, IP). In subsequent two-bottle preference tests the sham-lesioned rats displayed a significant (p < 0.01) aversion to the saccharin stimulus, relative to the area postrema-ablated rats which exhibited a preference for the saccharin solution. Thus, systemic administration of deoxynivalenol, following a novel taste, induced conditioned taste aversions which were mediated by the area postrema.

Animals↗