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Biomedical subjects

G Lowe

Publications and source records attributed to G Lowe.

At least 55 records · Page 3Linked to original sources
PubMed1998

Media messages and alcohol education: a school-based study.

The immediate effects of a media intervention on attitudes toward alcohol were investigated with 134 secondary school pupils (aged 13 to 17 years) who completed a drinking and smoking questionnaire and expressed strength of agreement or disagreement with 13 statements about alcohol, drinking and health. Pupils then read news cuttings from popular magazines. One group read a negative message about alcohol, another group a positive message. Other groups read both positive and negative messages, and a control group had no media intervention. Immediately afterwards, all pupils responded to the same 13 statements again. Those pupils who received only a negative message became significantly more negative in their attitudes towards alcohol. Those receiving only a positive message were significantly more positive afterwards. The control group and those receiving both positive and negative messages showed little change. These findings are discussed in terms of their implications for alcohol education programs at school.

Adolescent↗
PubMed1997

Hypocalcemic tetany and metabolic alkalosis in a dialysis patient: an unusual event.

The case is described of a 29-year-old man with renal failure and recurrent hyperparathyroidism who 3 weeks postparathyroidectomy developed hypocalcemic tetany because he was taking one-half the prescribed dose of calcitriol. He interpreted his symptoms as those of potassium intoxication and self-administered almost 1,500 mEq sodium bicarbonate. The increase in plasma sodium and osmolarity led to increased fluid intake, and at presentation he had an ionized calcium of 0.50 mmol/L, K 5.3 mmol/L, Na 148 mmol/L, total CO2 52.6 mmol/L, pO2 51.2 mm Hg, and pH of 7.61. He had gained 7 kg in weight. All abnormalities were corrected by dialysis, using initially a calcium-free dialyzate with extra calcium infused. The case illustrates the effect of alkalosis in reducing the amount of calcium that exists in ionized form, and it is suggested that complexing of calcium as calcium bicarbonate together with the pH change contributed to the decrease in ionized calcium. It is also an example of the hazards of treating patients who devise their own therapeutic regimens.

Adult↗
PubMed1997

Presence of t(8;21)(q22;q22) in myeloperoxidase-positive, myeloid surface antigen-negative acute myeloid leukemia.

Although acute myeloid leukemias (AMLs) cytochemically negative for myeloperoxidase are now well recognized, myeloid surface antigen-negative AMLs are rare. The morphologic, cytochemical, immunologic, and cytogenetic or molecular features of such cases are described in four adults aged 19 to 60 years. All had AML with maturation (FAB M2) and were myeloperoxidase positive. Immunologic studies showed all to be HLA-DR positive but negative for the CD13, CD14, and CD33 antigens. Two of four were CD34 antigen positive. Cytogenetic studies were performed in three patients, and all demonstrated t(8;21)(q22;q22). In studies using the reverse transcriptase polymerase chain reaction in two patients, including the patient in whom karytypic analysis was not performed, the AML1-ETO fusion product of t(8;21) was identified. These findings suggest an association between the lack of myeloid antigen expression in myeloperoxidase-positive AML and the presence of t(8;21). In addition, the results demonstrate the continued need for cytochemical studies in the evaluation of acute leukemias.

Adult↗
PubMed1997

Social drinking and laughter.

Pairs of observers monitored drinking and laughter in groups of social drinkers (N = 56). A significant correlation of .27 was found between units of alcohol consumed and laughter scores.

Adolescent↗
PubMed1997

Alcohol misuse prevention for young people: a systematic review reveals methodological concerns and lack of reliable evidence of effectiveness.

In a systematic review we assessed the methodological quality of evaluations of alcohol misuse prevention programmes for young people, and recorded evidence of effectiveness. Studies were identified through systematic searches of electronic databases; hand searches of all obtained papers, existing reviews and several journals; and mailshots to key organizations, conferences and individuals. Relevant papers were checked and cross-checked by members of the review team, and only those studies with an experimental or quasi-experimental design and positive attributes on a number of other quality criteria were included in the review. After pre-screening over 500 papers which reported prevention programmes, information was systematically abstracted from 155 papers. Only 33 studies merited inclusion in the review, and most of these had some methodological shortcomings. Twenty-one studies reported some significant short- and medium-term reductions in drinking behaviour. Of two studies which carried out longer-term evaluations, only one reported a significant longer-term effect, with small effect sizes. No factors clearly distinguished partially effective from ineffective or harmful prevention programmes. In conclusion, the lack of reliable evidence means that no one type of prevention programme can be recommended. In particular there is a need to carry out well-designed scientific evaluations of the effectiveness of current or new prevention efforts which target young people's alcohol misuse.

Adolescent↗
PubMed1996

An investigation of the binding of protein proteinase inhibitors to trypsin by electrospray ionization mass spectrometry.

The binding of BPTI and SBTI with trypsin has been investigated by ESI MS, using the mutant K15V-BPTI and the chemically modified RcamBPTI as controls. Although high cone voltages (+80 V) produce sharp spectra of BPTI, RcamBPTI, SBTI and trypsin alone, the complexes of BPTI, RcamBPTI and SBTI with trypsin undergo partial dissociation due to collisional activation. At lower cone voltages (+40 V) these non-covalent complexes are stable. The charge distribution on the trypsin and the inhibitors produced by gas phase dissociation of the complexes are markedly different from those of the components alone, indicating that ESI MS provides a novel probe for exploring the ionic interactions at the contact surface of proteins. Moreover, by determining the cone voltage at which the gas phase dissociation of complexes occurs it may be possible to use ESI MS to compare the binding energies of closely related complexes.

Acetates↗
PubMed1996

Inhibition of human leukocyte and porcine pancreatic elastase by homologues of bovine pancreatic trypsin inhibitor.

The interactions of three BPTI homologues with human leukocyte elastase and porcine pancreatic elastase have been investigated. The principal mutation in determining the specificity of inhibition was the Lys15-Val mutation at the P1 position. An additional mutation at P3, i.e., BPTI (Lys15-Val, Pro13-Ile), increased the inhibition of HLE to a Ki = 2.5 x 10(-10) M, but decreased the inhibition of PPE, showing this to be a useful site for improving selectivity. Kinetic evidence suggests that the inhibition of HLE by BPTI homologues probably takes place by a two-step mechanism in which an isomerization step occurs after initial binding. 1H NMR spectroscopy of the BPTI (Lys15-Val) and BPTI (Lys15-Val, Pro13-Ile) mutants indicates that small conformational changes are associated with the mutations, but these are localized in the immediate vicinity of the mutation in the outer binding loop and in the inner loop connected to it through the Cys14-Cys38 disulfide bridge.

Amino Acid Sequence↗
PubMed1996

The structure of 4-way DNA junctions: specific binding of bis-intercalators with rigid linkers.

During replication and recombination, two DNA duplexes lie side by side. We have developed reagents that might be used to probe structure during these critical processes; they contain two intercalating groups connected by a rigid linker that forces those groups to point in opposite directions. If their stereochemistry proves appropriate, such structure-specific agents should intercalate specifically into adjacent duplexes in the Y- and X-shaped structures (i.e. 3- and 4-way junctions, now known as 3H and 4H junctions) found at replication and recombination sites. We prepared DNA structures in which four duplexes were arranged in all possible combinations around 2- and 4-way junctions and then probed the accessibility to DNase I of all their phosphodiester bonds. In the absence of any bis-intercalators, 7-9 nucleotides (nt) in each of the strands in 4-way junctions were protected from attack; protected regions were significantly offset to the 3' side of the junction in continuous strands, but only slightly offset, if at all, in exchanging strands. All the intercalators decreased accessibility throughout the structure, but none did so at specific points in the two adjacent arms of 4-way junctions. However, one bis-intercalator--but not its sister with a shorter linker--strikingly increased access to a particular CpT bond that lay 9 nt away from the centre of some 4-way junctions without reducing access to neighbouring bonds. Binding was both sequence and structure specific, and depended on complementary stereochemistry between bis-intercalator and junction.

Acridines↗
PubMed1996

4-Picoline-2,2':6',2"-terpyridine-platinum(II) - a potent intercalator of DNA.

4-Picoloine-2,2':6',2"-terpyridine-platinum(II) is shown in a ligation assay to unwind and so intercalate into DNA. Circular dichroism is used to determine an equilibrium binding constant of approximately 2 x 10(7) M(-1) for the most stable binding mode of 4-picoline-2,2':6',2"-terpyridine-platinum(II) to poly[d(A-T)2] with a site size of about 4 base pairs, and about 1 x 10(6) M(-1) for a second binding mode with a site size of about 2 base pairs. Fluorescence spectroscopy provides further evidence for the strong equilibrium binding constant of 4-picoline-2,2':6',2"-terpyridine-platinum(II) in that it displaces ethidium bromide bound to DNA. The double positive charge on 4-picoline-2,2':6',2"-terpyridine-platinum(II), together with the intercalative binding mode is probably responsible for the large binding constant.

Binding Sites↗
PubMed1996

Structure and properties of TentaGel resin beads: implications for combinatorial library chemistry.

In view of the widespread use of TentaGel resin beads for the synthesis of combinatorial libraries, the properties of TentaGel resin have been examined using a combination of confocal laser microscopy and NMR spectroscopy. Evidence is presented that trypsin, a 23.5-kDa enzyme, can penetrate to the core of 90-microns TentaGel beads, and that the matrix of such beads permits molecular motion at a similar rate to that in solution. The beads act as a separate gel phase rather than as a porous solid. These conclusions have important implications for the bioassay of on-bead combinatorial chemical libraries.

Deuterium↗
PubMed1996

Diffusion through narrow pores: movement of ions, water and nonelectrolytes through track-etched PETP membranes.

The rates at which ions (86Rb+, [3H]-choline, 36Cl), 3H2O and nonelectrolytes ([14C]-urea, [14C]-glycerol, and [14C]-sugars) equilibrate across track-etched polyethyleneterephthalate (PETP) membranes (isotopic diffusion) have been measured by a 'static' and a 'dynamic' technique under conditions where no net flow takes place; the two techniques give essentially the same results. All tracers diffuse faster the longer the membranes are etched, consistent with an increase in pore size. Water and neutral solutes diffuse at rates that are relatively independent of ionic strength, pH or the presence of divalent cations. Diffusion of cations is decreased by high ionic strength, by reducing pH or by addition of divalent cations; diffusion of chloride is increased by these procedures. Treatment of the membrane with diazomethane to reduce the negative fixed charge decreases diffusion of cations and increases that of anions; diffusion of water and neutral solutes is unaffected by methylation except in the membranes with the narrowest pores (i.e., those etched for the shortest time), in which case diffusion is reduced. We conclude (1) that the special features of flow near a charged surface apply to ions but not to water or nonelectrolytes and (2) that calculation of absolute rates of diffusion leads to values for the radii of pores through track-etched PETP membranes that are in remarkably good agreement with measured values.

Anions↗
PubMed1996

A mass spectrometric investigation of the reaction between 4,4'-vinylenedipyridine bis[2,2':6',2"-terpyridine platinum(II)] and the self-complementary oligonucleotide d(CpGpTpApCpG).

4,4'-Vinylenedipyridine bis[2,2':6',2"-terpyridine platinum(II)], a potential intermolecular bis-intercalator of DNA, reacts slowly at PtII, the linker being displaced by nucleobases. Crystallization of 4,4'-vinylenedipyridine bis[2,2':6',2"-terpyridine platinum(II)] in the presence of the self-complementary oligonucleotide d(CpGpTpApCpG) gave a product which was analyzed by electrospray ionization mass spectrometry. Molecular mass measurements demonstrated ligation of one terpyridine PtII, which was shown by liquid chromatography-mass spectrometry to reside exclusively on deoxyguanosine. The terpyridine PtII was shown by tandem mass spectrometry to be attached to the 3'-terminal deoxyguanosine, consistent with N-7 substitution.

2,2'-Dipyridyl↗
PubMed1996

The effect of oral vanadyl sulfate on body composition and performance in weight-training athletes.

The effects of oral vanadyl sulfate (VOSO4) (0.5 mg/kg/day) on anthropometry, body composition, and performance were investigated in a 12-week, double-blind, placebo-controlled trial involving weight-training volunteers. Performance was assessed in the treatment (VS) and placebo (P) groups using 1 and 10 repetitions maximum (RM) for the bench press and leg extension. Thirty-one subjects completed the trial, with 2 VS subjects withdrawing because of apparent side effects. There were no significant treatment effects for anthropometric parameters and body composition during the trial. Both groups had significant improvements in performance but the only significant effect of treatment was a Treatment x Time interaction in the 1 RM leg extension (p = .002), which could have arisen because the VS group had a lower performance at baseline in this test. It was concluded that oral vanadyl sulfate was ineffective in changing body composition in weight-training athletes, and any modest performance-enhancing effect requires further investigation.

Absorptiometry, Photon↗
PubMed1995

Olfactory transduction is intrinsically noisy.

The sources of noise that limit olfactory signal detection were investigated in dissociated rat olfactory receptor cells. Near-threshold odorant-evoked currents exhibited large random fluctuation. However, similar fluctuations were observed in the absence of applied odorants when currents were induced by elevating the intracellular cyclic AMP concentration. This suggests that the fluctuations reflect noise intrinsic to the transduction mechanism, rather than the quantal nature of an odorant stimulus. For many odorants, this intrinsic noise may preclude the reliable detection of single odorant molecules.

1-Methyl-3-isobutylxanthine↗
PubMed1995

Judgments of substance use and creativity in 'ordinary' people's everyday lifestyles.

To investigate the relationship between substance use and creativity, four pairs of raters independently assessed the reports of over 600 respondents from the Mass-Observation (M-O) Archive. The M-O directive addressed, their use of 'stimulants and relaxants.' Correlations between 'creativity' ratings and 'substance use' ratings were low but significantly positive (around .275). The observed links are discussed in relation to laboratory-based and other studies of substance use and creativity.

Adolescent↗
PubMed1995

Production of bovine-pancreatic-trypsin-inhibitor homologues in Escherichia coli and their characterization.

Biologically active bovine pancreatic trypsin inhibitor (BPTI) was produced in Escherichia coli using an OmpA leader-peptide fusion-protein system, and BPTI homologues were generated by cassette mutagenesis. Amino acids in the reactive loop of alpha 1-proteinase inhibitor (alpha 1-PI) were incorporated into the reactive loop of BPTI in a stepwise approach such that the contribution of individual amino acids could be assessed. The introduction of mutations into BPTI diminished the yield of heterologous protein relative to wild-type BPTI. However, for three BPTI homologues sufficient material was isolated to allow characterization of the proteins by electrospray MS and N-terminal peptide sequencing.

Amino Acids↗