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E Bennett

Publications and source records attributed to E Bennett.

At least 19 recordsLinked to original sources
PubMed1997

MUC1 gene polymorphism and gastric cancer--an epidemiological study.

Gastric carcinoma is a major cause of cancer death worldwide and, like most human cancers, probably develops after environmental insults acting on normal individuals and/or individuals with increased genetic susceptibility. Mucins are attractive molecules to study the relationship between genetics and environment because they play an important role in the protection of gastric mucosa against environmental insults and exhibit a highly polymorphic genetic variation. We performed a case-control study using Southern blot analysis to evaluate the MUC1 gene polymorphism in a series of blood donors (n = 324) and in patients with gastric carcinoma (n = 159). We found that the distribution of MUC1 alleles is significantly different in the two populations and that small MUC1 alleles and small MUC1 genotypes are significantly more frequent in patients with gastric carcinoma than in controls. Individuals with small MUC1 genotypes are at increased risk for gastric carcinoma development.

ABO Blood-Group System↗
PubMed1997

Contribution of sialic acid to the voltage dependence of sodium channel gating. A possible electrostatic mechanism.

A potential role for sialic acid in the voltage-dependent gating of rat skeletal muscle sodium channels (rSkM1) was investigated using Chinese hamster ovary (CHO) cells stably transfected with rSkM1. Changes in the voltage dependence of channel gating were observed after enzymatic (neuraminidase) removal of sialic acid from cells expressing rSkM1 and through the expression of rSkM1 in a sialylation-deficient cell line (lec2). The steady-state half-activation voltages (Va) of channels under each condition of reduced sialylation were approximately 10 mV more depolarized than control channels. The voltage dependence of the time constants of channel activation and inactivation were also shifted in the same direction and by a similar magnitude. In addition, recombinant deletion of likely glycosylation sites from the rSkM1 sequence resulted in mutant channels that gated at voltages up to 10mV more positive than wild-type channels. Thus three independent means of reducing channel sialylation show very similar effects on the voltage dependence of channel gating. Finally, steady-state activation voltages for channels subjected to reduced sialylation conditions were much less sensitive to the effects of external calcium than those measured under control conditions, indicating that sialic acid directly contributes to the negative surface potential. These results are consistent with an electrostatic mechanism by which external, negatively charged sialic acid residues on rSkM1 alter the electric field sensed by channel gating elements.

Animals↗
PubMed1996

The molecular mechanism and potential dependence of the Na+/glucose cotransporter.

Activity of the Na+/glucose cotransporter endogenously expressed in LLC-PK1 cells was measured using whole cell recording techniques under three different sodium concentration conditions: 1) externally saturating, zero trans; 2) 40 mM external, zero trans; and 3) externally saturating, 50 mM trans. Activity of the transporter with increasing concentrations of sugar was measured for each set of conditions, from which the maximal current for saturating sugar, Im, was determined. The Im measured shows substantial potential dependence for each set of conditions. The absolute Im and the relative potential dependence of Im compared among the various solute conditions were used to identify which loci in the transport cycle are responsible for potential-dependent changes in function. The experimental data were compared with the predicted Im values calculated from an eight-state, sequential, reversible model of a transport reaction kinetic scheme. Predictions derived from assignment of rate limitation and/or potential dependence to each of the 16 transitions in the transport pathway were derived and compared with the measured data. Most putative models were dismissed because of lack of agreement with the measured data, indicating that several steps along the transport pathway are not rate limiting and/or not potential dependent. Only two models were found that can completely account for the measured data. In one case, translocation of the free carrier must be rate limiting, and both extracellular sodium-binding events as well as translocation of both free and fully loaded carrier forms must be potential-dependent transitions. In the second case, translocation of the free carrier and dissociation of the first sodium to be released intracellularly must be equivalently rate limiting. In this case only the two translocation events are required to be potential dependent. The two external sodium-binding events might still be potential dependent, but this is not required to fit the data. Previous reports suggest that the first model is correct; however, no direct experimental data compel us to dismiss the second option as a feasible model.

Animals↗
PubMed1996

Functional disorders of the small intestine.

Sensorimotor disturbances of the small bowel are implicated increasingly in the pathogenesis of the functional gastrointestinal disorders. In irritable bowel syndrome (IBS), alterations in both interdigestive and postprandial motility have been described, for example, the specific peristaltic contractions that are normally present in the ileum appear to occur more frequently and to be associated with abdominal pain in some patients. The latter finding is likely to be related to the selective mechanoreceptor hypersensitivity that has been demonstrated in the small bowel of IBS patients. The level of this afferent dysfunction has, however, not been established; some evidence suggests that personality traits, which predispose to a more severe and prolonged sympathetic response to stressors, may hasten the development of such sensorimotor disturbances.

Colonic Diseases, Functional↗
PubMed1995

Cultural factors in dialysis and renal transplantation among aborigines and Torres Strait Islanders in north Queensland.

Australian Aborigines experience end-stage renal disease at 10 times the national average. Although contributing physiological factors have been widely discussed, there has been little research into cultural factors affecting treatment and outcomes. This paper discusses folk and lay understandings of renal physiology and disease aetiology, and social and cultural factors in dialysis and transplantation, in a group of Aboriginal and Torres Strait Island renal transplant recipients. The implications for service delivery include the need for improved and clear information regarding renal disease and treatment and for culturally appropriate and acceptable support systems. Beliefs that continued alcohol consumption and poor nutrition were major reasons for kidney failure and separation from kin and country emerged as significant factors affecting treatment and leading to poor outcomes.

Cultural Characteristics↗
PubMed1995

Voltage- and frequency-dependent pentobarbital suppression of brain and muscle sodium channels expressed in a mammalian cell line.

The voltage- and frequency-dependent interactions of pentobarbital with voltage-gated sodium channels were examined in whole-cell patch-clamp recordings. Using rat brain IIA and rat muscle rSkM1 sodium channels expressed in stably transfected Chinese hamster ovary cell lines, it was found that pentobarbital reduced peak inward sodium currents with IC50 values of 1.2 mM (brain) and 1.0 mM (muscle). Analysis of steady state channel availability curves revealed two distinct effects of pentobarbital on both channel isoforms, i.e., a voltage-independent current reduction and an additional hyperpolarizing shift in the voltage dependence of channel availability. The latter effect leads to a voltage dependence of pentobarbital potency. Pentobarbital was also found to slow channel recovery after depolarization, yielding an additional use-dependent component of current suppression. Use-dependent block was enhanced by higher stimulation frequencies, longer pulse durations, and more depolarized holding and pulse potentials. All effects were identical for both channels. These findings can be explained in terms of the modulated receptor hypothesis and are consistent with a preferential interaction of pentobarbital with the inactivated channel state. As a consequence, actual pentobarbital potency would depend largely on experimental conditions or, in vivo, on the physiological parameters of a particular cell.

Animals↗
PubMed1995

Perception of facial attractiveness by patients, peers, and professionals.

Self-perception of facial attractiveness of 19 women (15 with Class II malocclusion and four with Class I malocculsion) was compared to the perceptions of the patient's peers, five orthodontists, and five oral surgeons. Each respondent ranked a set of four standardized facial photographs of each patient from most (1) to least (19) attractive. A surgical treatment plan was recommended for all of the Class II patients. However, only nine accepted surgery; six elected to undergo camouflaging orthodontics only. There was a statistically significant difference in the distribution of ranks given to the Class I, Class II camouflage-only, and Class II surgery groups by the panels. Overall, the Class I patients were judged most attractive. The Class II patients who elected to undergo orthodontics only were given mid-ranks, and the patients who elected surgery were ranked least attractive, although the distributions for overjet, point A-nasion-point B, and motivations for treatment were similar in the two groups. The distribution of self-ranks given by the patients were not significantly different among the three groups, although than the Class II patients perceived themselves as less attractive than the Class I patients.

Adult↗
PubMed1994

Cloning and characterization of a cDNA encoding a novel fatty acid binding protein from rat brain.

We have adopted a polymerase chain reaction approach to identify and clone a cDNA that contains the complete coding sequence of a novel fatty acid binding protein (FABP) from a rat brain lambda gt10 library. Sequencing of the brain FABP (B-FABP) cDNA revealed an open reading frame coding for a protein with 132 amino acids and a predicted size of approximately 15,000 Da. This putative protein shares extensive sequence homology with other members of the FABP family. Northern blot analysis using the B-FABP cDNA as a probe established the presence of an abundant mRNA approximately 0.8 kb long in rat brain and in the MOCH-1 oligodendrocyte cell line. This transcript was also present in rat liver but not in other tissues examined. A developmental profile of this mRNA in rat brain demonstrated detectable expression in 15-day-old embryos with levels peaking in 1-day postnatal neonates and declining thereafter, reaching a low steady-state level at 3 weeks of age. In situ hybridization histochemistry revealed B-FABP mRNA in various brain regions, with the highest levels in fiber tracts. The B-FABP message was also detected at a lower level in several gray matter regions. The cloning approach used in this study would likely be useful in the identification and isolation of FABP-encoding genes from other tissues and species.

Amino Acid Sequence↗
PubMed1993

Screening mothers of young children for substance abuse.

Pediatricians have been urged to screen for parental substance abuse, but few screening instruments have been tested for mothers. We compared six screening questions for maternal alcohol and drug abuse with the Michigan Alcoholism Screening Test (MAST) and the Drug Abuse Screening Test (DAST). Questionnaires were completed by 507 mothers; most were Caucasian (78%) and married (75%). Eighteen percent were positive on the MAST, and 3% were positive on the DAST. The screening questions for drinking had a 90% sensitivity compared with the MAST; the questions about drug use had a sensitivity of 88% compared with the DAST. The MAST detected only 25% of mothers who reported physiologic tolerance to alcohol and 32% of those who reported binge drinking; the DAST failed to detect any mothers who reported using drugs in the previous 24 hours. The six screening questions about alcohol and drug use had good sensitivity, detected potential drinking problems and drug abuse missed by the MAST and DAST, and can be incorporated easily into a comprehensive psychosocial questionnaire.

Adult↗
PubMed1992

Na+ binding to the Na(+)-glucose cotransporter is potential dependent.

Activity of the Na(+)-glucose cotransporter in LLC-PK1 epithelial cells was assayed by measuring sugar-induced currents (IAMG) using whole cell recording techniques. IAMG was compared among cells by standardizing the measured currents to cell size using cell capacitance measurements. IAMG at a given membrane potential was measured as a function of alpha-methylglucoside (AMG) concentration and can be fit to Michaelis-Menten kinetics. IAMG at varying Na+ concentrations can be described by the Hill equation with a Hill coefficient of 1.6 at all tested potentials. At high external Na+ levels (155 mM), Na+ is at least 90% saturating at all tested potentials. Maximal currents at a given membrane potential (Im) are calculated from the Michaelis-Menten equation fit to data measuring IAMG vs. AMG concentration at a constant Na+ concentration. Im showed potential dependence under all conditions. Potential-dependent Na+ binding rate(s) cannot alone explain the observed potential dependence of Im under saturating Na+ conditions. Therefore, because Im is potential dependent, at least one step of the transport cycle other than external Na+ binding must be potential dependent. Im was also calculated from data taken at 40 mM external Na+. At all potentials studied, Im at 155 mM Na+ is greater than Im calculated at 40 mM Na+. This implies that the rate of external Na+ binding to the transporter at 40 mM also affects the maximal transport rate. Furthermore, Im at 40 mM external Na+ increases with hyperpolarization faster than Im at 155 mM Na+. Together, these facts indicate that the rate at which Na+ binds to the transporter is also potential dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Line↗
PubMed1991

Life stress and non-ulcer dyspepsia: a case-control study.

Sixty-two patients with persistent NUD symptoms were compared with healthy persons of comparable age, sex and social status on a variety of life stress, personality, mood state and coping measures. Highly threatening chronic difficulties were significantly more evident in the NUD group than controls (98 and 2% respectively), as were acute life events which remained highly threatening one week after their onset. Other psychological variables significantly related to NUD were high levels of anxiety and depressive symptoms, personality traits indicating neurotic or anxious tendencies, a tendency to use less mature stress-coping mechanisms and to have less high-quality emotional support. Multivariate analysis revealed the presence of highly threatening stressors to be by far the most important predictor of NUD status. The implications of these findings in relation to the significance of stress and other psychological variables in the aetiology and treatment of NUD are discussed.

Adaptation, Psychological↗
PubMed1991

Sodium-dependent succinate transport by isolated chick intestinal cells.

Isolated chick intestinal epithelial cells take up succinate by a Na(+)-coupled transport system similar in some characteristics to those described for renal epithelium. The transport system exhibits a hyperbolic dependence on succinate concentration but a sigmoidal dependence on Na+ concentration. Best nonlinear fit of the Na+ dependence data to the Hill equation indicates a Michaelis constant for half-maximal transport rate (Km) for Na+ of approximately 20 mM, a maximal transport rate (Vmax) of 1.1 nmol succinate.min-1.mg protein-1, and a Hill coefficient of 2.5. Nearly equivalent fit was obtained with trial Hill coefficients down to 2.0. The data for succinate dependence indicated a Km of 25 microM and Vmax of 1.05 nmol.min-1.mg protein-1. The kinetic parameters indicate a higher affinity, lower capacity system than for succinate transport in the renal brush-border system. Thiocyanate-induced diffusion potentials cause no change in Na(+)-dependent succinate influx despite pronounced effects on the influx of tetraphenylphosphonium and on Na(+)-dependent alpha-methylglucoside (AMG) and alanine uptake. Several other dicarboxylic and tricarboxylic metabolic intermediates (but not the dicarboxylic amino acids) compete with succinate for uptake via the transport system. The data are consistent with the likelihood that these cells have a succinate transport system with a 2Na+:1succinate stoichiometry per transport cycle. The system catalyzes no net charge transfer and is therefore different from the potential-responsive succinate transporter described for renal tissue.

Alanine↗
PubMed1990

Whole cell recording of sugar-induced currents in LLC-PK1 cells.

Gigaohm-seal whole cell recording techniques were used to monitor function of the Na(+)-coupled sugar transport system in LLC-PK1 cells. The currents coupled to sugar transport were identified as those that are induced by the presence of 10 mM alpha-methylglucoside (AMG) in either the extracellular or intracellular compartment and were inhibited by addition of 320-800 microM phlorizin to the extracellular bathing medium. The sugar-induced currents are small, 15-20 pA, but of the expected magnitude as determined from the known kinetic parameters for Na(+)-coupled sugar transport in LLC-PK1 cells. The phlorizin-sensitive currents are Na+ dependent and can be studied under conditions in which the net Na+ and sugar flux (and consequently the Na+ electrical current) is in either the inward or outward direction. The reversal potential of the sugar-induced currents measured under conditions with high Na+ and AMG concentrations inside the cell is close to values predicted from thermodynamic principles, assuming a coupling stoichiometry of 2 Na+: 1 sugar for the transport system. The reversal potential of the sugar-induced currents with high extracellular Na+ and AMG is not equal to the predicted value, but it is of the polarity expected for inward-imposed solute gradients. Reasons for the observed discrepancy between observed and calculated values are discussed.

Animals↗
PubMed1987

A prospective study of BCG given to young children in Agra, India--a region of high contact with environmental mycobacteria.

A multiple skin test survey of school children (aged 5-15 years) living in Agra, India showed very high levels of sensitisation to numerous species of mycobacteria and little difference in tuberculin positivity between those with and without BCG scars. A total of 136 children aged 3 months to 8 years, living in Agra, were skin tested with Tuberculin and Leprosin A and examined for scars of previous BCG vaccination. Of those who had not previously received BCG and who had responses to Tuberculin of zero or less than 5 mm induration, 109 were offered BCG vaccination: 107 accepted and as many of them as possible were followed up with repeat skin testing 1 and 2 years later. The results are discussed in relation to the background of environmental sensitisation. A comparison is made with the data obtained from other places, particularly the Lebanon, where there is little sensitisation from the environment. Although the high level of Tuberculin conversion achieved after BCG suggested that the vaccine might have an important protective effect, the large size of Tuberculin responses in comparison with those obtained in the UK was worrying. Evidence was obtained suggesting that sensitisation to mycobacteria may occur in very young children which is not detected by the Tuberculin test, but which influences responses to BCG vaccination.

BCG Vaccine↗
PubMed1987

Testing of chemicals, safety evaluation and regulation at European Community level.

Regulations regarding safety of chemicals are covered by the following main programmes: health and safety at work, internal market and technical harmonization, environmental and consumer protection. The elaboration of draft Community legislation by the Commission for transmission to Council and the European Parliament requires an evaluation of the scientific data together with a determination of the technical possibilities and economic impact. Studies, scientific committees, national experts and tripartite advisory committees are used. For new chemicals premarketing testing is required for labelling. The testing scheme is described. From the legislative point of view chemical safety is considered essentially in terms of six broad categories: air and water pollution and handling of toxic wastes, classification and labelling of dangerous chemicals and preparations, limitations of use of dangerous substances and preparations, occupational health and safety measures, prevention of major industrial chemical accidents, public health measures related to dangerous chemicals. The classification and labelling of carcinogens and the regulation of the various facets of the use of lead will illustrate these regulatory procedures.

Accident Prevention↗
PubMed1985

Subspecies- and species-specific antigens of Leishmania mexicana characterized by monoclonal antibodies.

Monoclonal antibodies have been produced that are specific for the reference stocks of Leishmania mexicana species and subspecies L. mexicana mexicana(L11, M379), L. mexicana amazonensis (WR303, H6, LV72), and L. mexicana pifanoi (L20). The specificities of these antibodies were confirmed by analyses employing an indirect radioimmune binding assay and 107 stocks of New World Leishmania. The molecules associated with these species- and subspecies-specific determinants have been characterized by Western blot analysis and consist of mainly low m.w. (11,000 to 50,000) membrane-associated components.

Animals↗
PubMed1984

Production and characterization of species-specific monoclonal antibodies against Leishmania donovani for immunodiagnosis.

Sixteen species-specific monoclonal antibodies were produced against membranes of Leishmania donovani. These antibodies only reacted with determinants present on L. donovani. No cross-reactions were found with any other species of Leishmania or with membranes of Trypanosoma cruzi. An extensive analysis of the binding specificities of selected antibodies was carried out by using whole promastigote homogenates as antigen. Monoclonal antibodies D-1, D-2, D-3, and D-4 correctly identified all 44 L. donovani stocks from a cross-panel of 84 New and Old World Leishmania stocks. Antibodies D-1 and D-2 were also useful for species classification by immunofluorescence. No cross-reactions were observed with any other Leishmania species examined. Based on either Western blot and/or radioimmunoprecipitation analyses, five distinct groups of molecules associated with L. donovani-specific antigenic determinants were identified. These molecules range in m.w. from 18 to 84 kilodaltons. The antigenic molecules recognized by antibodies D-2, D-10, and D-13 are also recognized by antibodies present in sera from patients with visceral leishmaniasis (kala-azar). Kala-azar sera obtained from cases in both the Old and New World specifically compete with these monoclonal antibodies for the appropriate antigenic determinants in Western blot analysis. These monoclonal antibodies and/or the purified protein antigens may be useful in the development of a serologic assay for the clinical diagnosis of visceral leishmaniasis caused by L. donovani and in epidemiologic studies of leishmaniasis.

Animals↗