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T Benson

Publications and source records attributed to T Benson.

At least 19 recordsLinked to original sources
PubMed2007

Developing a socio-economic measure to monitor access to tuberculosis services in urban Lilongwe, Malawi.

OBJECTIVES: To develop locally appropriate measures of poverty for the National Tuberculosis Programme (NTP), Malawi, and to assess access to tuberculosis (TB) services by different socio-economic groups by establishing a socio-economic profile of current TB patients DESIGN: A quantitative proxy measure of poverty was developed through regression analysis of data from the 1998 national Malawi Integrated Household Survey. A qualitative assessment of poverty was conducted in poor and non-poor settlements in urban Lilongwe to identify key indicators of socio-economic status. Both quantitative and qualitative indicators were used to assess the socioeconomic status of 179 TB patients who participated in a cross-sectional survey. FINDINGS: The proxy measure of poverty and the qualitative indicators demonstrated similar ability to measure the poverty status of patients. The poverty head count among patients using the quantitative and qualitative indicators were 78% and 70%, respectively. Geographical analysis showed that 60% were from non-poor areas and only 15% (26/139) were from squatter settlements. CONCLUSION: This study established a strategy for monitoring access to TB services using a proxy measure of poverty and qualitative indicators. This is a vital first step in developing an evidence base for pro-poor equitable TB services.

Adult↗
PubMed2004

L-arginine transport in the human coronary and peripheral circulation.

BACKGROUND: Nitric oxide synthase (NOS) uses arginine for the production of nitric oxide (NO). High intracellular concentrations of arginine suggest that NOS activity should be independent of plasma arginine supply. However, under certain conditions, increased plasma arginine concentrations appear to be associated with increased NOS activity. The purpose of this study was to explore arginine transport within the human coronary and peripheral circulation METHODS AND RESULTS: Mass-labeled 15N2-arginine was infused to steady state before cardiac catheterization in 31 patients. After diagnostic angiography, a catheter was placed in the coronary sinus. The transcardiac concentration gradient (aorta-coronary sinus) of 15N2-arginine was used as a measure of arginine transport at baseline and during infusions of acetylcholine and N(G)-monomethyl-L-arginine (L-NMMA). No gradient was detected at rest. During the infusion of acetylcholine, a significant gradient was detected (2.5+/-1.2 micromol/L, P=0.01) corresponding to a fractional extraction of 11.7+/-7.5%. This is consistent with in vitro studies that suggest that stimulation of NOS induces arginine transport. During the infusion of L-NMMA, the concentration of 15N2-arginine increased in the coronary sinus, producing a gradient of -3.9+/-1.3 micromol/L (P=0.0002), corresponding to a fractional production of 20.5+/-5.0%. This is consistent with in vitro studies that suggest that L-NMMA induces the efflux of arginine from the cell to the extracellular space via transporter-mediated transstimulation. CONCLUSIONS: The use of steady-state 15N2-arginine to examine transorgan L-arginine gradients represents a novel tool for the study of L-arginine transport and the mechanisms of endothelial and NOS dysfunction.

Acetylcholine↗
PubMed2001

Why British GPs use computers and hospital doctors do not.

Almost all general medical practitioners (GPs) in the UK use computers, compared with less than one in ten of hospital doctors. This paper explains how this unexpected situation came about over a thirty-year period, identifying some of the successes and failures of British medical computing along the way. Twelve separate factors are considered. The major determinants have not been technical, but rather a strong tide of political backing for general practice and leadership from the profession at the highest level, which have combined to build an appropriate regulatory framework and financial incentives that have encouraged GPs to embrace computers. Hospital computing has some difficulties not met by GPs, but the main factor preventing progress has been the lack of any real incentive positive (carrot) or negative (stick), for hospital doctors to use computers.

Attitude to Computers↗
PubMed1994

Inhibition of L-type calcium-channel activity by thapsigargin and 2,5-t-butylhydroquinone, but not by cyclopiazonic acid.

Thapsigargin (TG), 2,5-t-butylhydroquinone (tBHQ) and cyclopiazonic acid (CPA) all inhibit the initial Ca(2+)-response to thyrotropin-releasing hormone (TRH) by depleting intracellular Ca2+ pools sensitive to inositol 1,4,5-trisphosphate (IP3). Treatment of GH3 pituitary cells for 30 min with 5 nM TG, 500 nM tBHQ or 50 nM CPA completely eliminated the TRH-induced spike in intracellular free Ca2+ ([Ca2+]i). Higher concentrations of TG and tBHQ, but not CPA, were also found to inhibit strongly the activity of L-type calcium channels, as measured by the increase in [Ca2+]i or 45Ca2+ influx stimulated by depolarization. TG and tBHQ blocked high-K(+)-stimulated 45Ca2+ uptake, with IC50 values of 10 and 1 microM respectively. Maximal inhibition of L-channel activity was achieved 15-30 min after drug addition. Inhibition by tBHQ was reversible, whereas inhibition by TG was not. TG and CPA did not affect spontaneous [Ca2+]i oscillations when tested at concentrations adequate to deplete the IP3-sensitive Ca2+ pool. However, 20 microM TG and 10 microM tBHQ blocked [Ca2+]i oscillations completely. The effect of drugs on calcium currents was measured directly by using the patch-clamp technique. When added to the external bath, 10 microM CPA caused a sustained increase in the calcium-channel current amplitude over 8 min, 10 microM tBHQ caused a progressive inhibition, and 10 microM TG caused an enhancement followed by a sustained block of the calcium current over 8 min. In summary, CPA depletes IP3-sensitive Ca2+ stores and does not inhibit voltage-operated calcium channels. At sufficiently low concentrations, TG depletes IP3-sensitive stores without inhibiting L-channel activity, but, for tBHQ, inhibition of calcium channels occurs at concentrations close to those needed to block agonist mobilization of intracellular Ca2+.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

The glutamyl binding site of trypanothione reductase from Crithidia fasciculata: enzyme kinetic properties of gamma-glutamyl-modified substrate analogues.

Trypanothione reductase, central to the redox defense systems of parasitic trypanosomes and leishmanias, is sufficiently different in its substrate-specificity from mammalian glutathione reductase to represent an attractive target for chemotherapeutic intervention. Previous studies of the physiological substrates trypanothione (N1,N8-bis(glutathionyl)spermidine) and N1-glutathionylspermidine disulphide established that the spermidine moiety of these substrates can be replaced by the 3-dimethyl-propylamide group (N1-glutathionyl-N3-dimethyl-propylamide). With this modification, the specificity for the gamma-glutamyl moiety of the substrate was examined. Kinetic analysis of a series of substrate analogues indicated that neither the alpha-carboxylate or alpha-amino functions of the L-gamma-glutamyl group is essential for recognition, since this group could be replaced by uncharged benzyloxycarbonyl or t-butyloxycarbonyl groups with relative catalytic efficiencies (kcat/Km) of 58 and 11%, respectively, of N1-glutathionyl-N3-dimethylpropylaminedisulphide. Other substitutions are less well tolerated (e.g., beta-L-aspartyl or aminobutyryl) or not at all (e.g., glutaryl). These findings are discussed in relation to the structural model of TR from Trypanosoma congolense. The successful structural replacements achieved have potential application for drug delivery.

Amino Acid Sequence↗
PubMed1993

Synthesis of substrate analogues for trypanothione reductase.

The synthesis and chemical characterisation of a range of substrate analogues for trypanothione reductase are described, with the spermidine portion of trypanothione replaced by the 3-dimethylaminopropylamide moiety. Using 1-hydroxybenzotriazole/N-hydroxysuccinimide coupling, products were obtained which had a range of replacements of the gamma-glutamyl groups of the enzyme substrate. The materials were characterised by FPLC, 1H/13C NMR spectroscopy and FAB mass spectroscopy.

Amino Acid Sequence↗
PubMed1993

Investigation of syntaxes for existing interchange formats to be used in healthcare.

This paper gives a summary of the work done by CEN TC 251 PT 004. The project team objective has been to investigate syntaxes of existing interchange formats (IFs) to be used in healthcare. A set of evaluation criteria have been developed based on functional requirements from two healthcare domains. 5 IFs; ASN.1, ASTM E1238, EDIFACT, Euclides and ODA have been evaluated. ASN.1 scores highest in the evaluation. However mapping from General Message Models (GMDs) to IF dependent message models (IFMDs) shows that all the IFs can be used. The project team recommends a strategy for development of GMDs, IFs and IFMDs.

Computer Communication Networks↗
PubMed1993

Development of standard healthcare EDI messages.

The development of standard healthcare messages requires a full understanding of user needs, an appropriate organisation structure for developing consensus and a suitable methodology. This paper presents the current state of development in the European Standardisation Organisation's Working Group on Healthcare Messages and Communications (CEN TC251 WG3).

Computer Communication Networks↗
PubMed1992

Heavy metal and selenium levels in young cattle egrets from nesting colonies in the northeastern United States, Puerto Rico, and Egypt.

Colonially-nesting species of herons and egrets breed mainly in coastal areas, along rivers or near other large bodies of water. Such areas are also preferred for human development, exposing nesting birds to various pollutants. From 1989-1991, the concentrations of heavy metals and selenium were studied in the feathers of fledgling cattle egrets Bubulcus ibis, a terrestrially-feeding insectivore, from New York and Delaware in the northeastern United States, from Puerto Rico, and from Egypt. There were geographic differences in the concentrations of lead, mercury, cadmium, manganese, selenium, and chromium in the feathers of these egrets. Lead levels were 41 times higher in the feathers of cattle egrets from Cairo compared to the other sites. This difference was attributed to the continuing use of leaded gasoline and the dense automobile traffic in Cairo. However, other differences remain unexplained. Similarly, levels of chromium and manganese were also higher in Cairo than at any other sites. Cadmium levels were similar at all places except for higher levels in eastern Puerto Rico. Mercury concentrations were twelve times higher in the feathers of cattle egrets at Aswan compared to Cairo. In Puerto Rico, we also compared levels in adult cattle egrets with young and found higher concentrations of mercury and manganese, but lower concentrations of selenium in the adults. Using feathers from young cattle egrets is a potentially sensitive tool for biomonitoring for metals, especially lead, since they reflect the local area surrounding the breeding colony.

Animals↗
PubMed1990

Dawn of a third era.

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Abstracting and Indexing↗