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R P Thomas

Publications and source records attributed to R P Thomas.

At least 19 recordsLinked to original sources
PubMed2005

The implications of integrated assessment and modelling studies for the future remediation of chromite ore processing residue disposal sites.

Chromite ore processing residue (COPR) waste from a former chromium chemical works (1830-1968) is still contaminating groundwater in Glasgow, Scotland, with carcinogenic hexavalent chromium, Cr(VI). An integrated analytical, experimental and modelling approach has identified and accounted for mineral phases and processes responsible for the retention and release of Cr(VI) under prevailing field conditions. Both the nature of mineral phase retention and the buffered high pH of the sites, however, militate against direct remediative treatment of the source material, for example by the application of generic methods (e.g. FeSO4) that have been successfully employed elsewhere for the reduction of Cr(VI) to Cr(III) in other matrices. The interception and treatment of groundwater to remove Cr(VI) and the capping of sites to reduce human exposure to airborne Cr(VI)-contaminated dust may well be more realistic and effective, at least in the short to medium term.

Chromium↗
PubMed2002

Sexual activity and condom use among Eastern European adolescents--the Study of Hungarian Adolescent Risk Behaviours.

While rates of HIV and STD infection in Eastern Europe are increasing rapidly, little is known about sexual behaviour, including condom use, among Eastern European youths. The Study of Hungarian Adolescent Risk Behaviours was designed to assess the knowledge, attitudes, and behaviours of adolescents studying in secondary schools in Budapest, Hungary. Students (n =3486) in a random sample of public secondary schools completed a self-administered questionnaire, including measures of sexual activity and condom use. Thirty-eight percent of students reported ever having had vaginal intercourse. Condom use by those reporting having had sex in the past five weeks was classified as consistent/every time (40%); irregular (25.6%); and none (34.3%). Multivariate analysis revealed positive opinions about condoms, fear of AIDS, and initiation of condom use by both partners to predict more frequent condom use. Implications for targeted AIDS/STD education and prevention among adolescents are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Constitutional, biochemical and lifestyle correlates of fibrinogen and factor VII activity in Polish urban and rural populations.

BACKGROUND: Fibrinogen and factor VII activity are known to be related to atherosclerosis and coronary heart disease, but population differences in clotting factors and modifiable characteristics that influence their levels have not been widely explored. METHODS: This paper examines correlates of plasma fibrinogen concentration and factor VII activity in 2443 men and women aged 35-64 in random samples selected from the residents in two districts in urban Warsaw (618 men and 651 women) and from rural Tarnobrzeg Province (556 men and 618 women) screened in 1987-1988, and assesses which characteristics might explain urban-rural differences. Fibrinogen and factor VII activity were determined using coagulation methods. RESULTS: Fibrinogen was 12.9 mg/dl higher in men and 14.1 mg/dl higher in women in Tarnobrzeg compared to Warsaw. Factor VII activity was higher in Warsaw (9.2% in men and 15.3% in women). After adjustment for selected characteristics, fibrinogen was higher in smokers compared to non-smokers by 28 mg/dl in men and 22 mg/dl in women. In women, a 15 mg/dl increase in HDL-cholesterol was associated with a 10 mg/dl decrease in fibrinogen (P < 0.01). After adjustment for other variables, a higher factor VII activity in Warsaw remained significant (a difference of 9.4% in men and 14.8% in women). Lower fibrinogen in Warsaw remained significant only in women (15.4 mg/dl difference). CONCLUSIONS: The study confirmed that sex, age, BMI, smoking and blood lipids are related to clotting factors. However, with the exception of gender differences and smoking, associations between clotting factors and other variables were small and of questionable practical importance.

Adult↗
PubMed1996

Blood pressure and heart rate response during exercise in men and women in the USA and Russia lipid research clinics prevalence study.

Examination of blood pressure (BP) and heart rate (HR) measurements at rest and during exercise in samples of USA and Russian middle-aged men and women show significant differences between countries for both genders. Russian men had higher resting systolic blood pressure (SBP) than USA men but lower SBP at both stages of exercise. Russian women had significantly higher resting SBP than USA women at rest and also during exercise. Russian men and women had significantly lower HR at rest and during exercise than USA men and women. Differences between countries were also noted for mean body weight, height, lipid levels, percentages of smokers and several other variables, and it was postulated that differences in these factors might be responsible in part for differences in SBP and HR during exercise. After adjustment for these variables, differences in SBP during exercise between USA and Russian men remained, but differences between USA and Russian women disappeared. For both genders, differences in HR during exercise remained after adjustment. Mortality analyses in USA and Russian men indicated that stage 2 SBP response during exercise was generally not a significant mortality risk factor after adjustment for age, BMI, TC, smoking and resting SBP. In a similar model, stage 2 HR response during exercise was also a non-significant risk factor in mortality.

Adult↗
PubMed1993

Root canal morphology of maxillary permanent first molar teeth at various ages.

The root canal anatomy and pulp chamber morphology of 216 maxillary permanent first molar teeth of known age was examined using a radiographic technique after infusion of the root canal system with a radiopaque sodium iothalomate gel. This technique proved to be a rapid and effective method for the examination of root canal morphology and is recommended when root canal anatomy needs to be examined before further investigations are carried out. Over 95% of palatal and disto-buccal roots contained a single root canal. The mesio-buccal root was more complex. All types of configurations were seen. Only 26% of mesio-buccal roots showed a single canal. The pulp canal in all roots appeared to narrow at an early age. In the mesio-buccal root, a definite two-directional calcification pattern was apparent in most teeth by the age of 10. The rate of progress of root formation was very variable. There was no apparent relationship between the type of canal system in the mesio-buccal root and the type of canal orifice present. The transverse cross-sectional shape of the pulp chamber was trapezoidal in 81% of teeth.

Adolescent↗
PubMed1992

Poland-US collaborative study on cardiovascular epidemiology: classification agreement between US National Cholesterol Education Program and European Atherosclerosis Society hyperlipidemia guidelines in selected Polish and US populations.

Data from two epidemiological studies are used to measure the degree to which two well-known guidelines agree in measuring hyperlipidemia in population samples in the US and Poland. The epidemiological studies are the US Lipid Research Clinics Program Prevalence Study and the Pol-MONICA project in Poland and the guidelines are those adopted by the US National Cholesterol Program (USNCEP) and by the European Atherosclerosis Society (EAS). EAS guidelines were analyzed in two ways: Method 1 used triglycerides and total cholesterol only in classifying persons as hyperlipidemics or non-hyperlipidemics; Method 2 used triglycerides, total cholesterol and nine additional risk factors in the classification process. USNCEP guidelines used total cholesterol, low density lipoprotein cholesterol and the same additional nine risk factors used in EAS Method 2 in classifying hyperlipidemics. Classification differences between the two sets of guidelines were high when EAS Method 1 guidelines were compared with USNCEP guidelines. However, EAS Method 2 which included risk factors, compared favorably with USNCEP guidelines in all three populations under study.

Adult↗
PubMed1991

Vanillin, a potential agent for the treatment of sickle cell anemia.

Vanillin, a food additive, has been evaluated as a potential agent to treat sickle cell anemia. Earlier studies indicated that vanillin had moderate antisickling activity when compared with other aldehydes. We have determined by high performance liquid chromatography that vanillin reacts covalently with sickle hemoglobin (HbS) both in solution and in intact red blood cells. Hemoscan oxygen equilibrium curves show a dose-dependent left shift, particularly at low oxygen tensions. Rheologic evaluation (pO2 scan Ektacytometry) of vanillin-reacted HbS erythrocytes shows a dose-dependent inhibition of deoxygenation-induced cell sickling. Ektacytometry also suggests that vanillin may have a direct inhibitory effect on HbS polymer formation. Vanillin has no adverse effects on cell ion or water content. X-ray crystallographic studies with deoxyhemoglobin (HbA)-vanillin demonstrate that vanillin binds near His 103 alpha, Cys 104 alpha, and Gln 131 beta in the central water cavity. A secondary binding site is located between His 116 beta and His 117 beta. His 116 beta has been implicated as a polymer contact residue. Oxygen equilibrium, ektacytometry, and x-ray studies indicate that vanillin may be acting to decrease HbS polymerization by a dual mechanism of action; allosteric modulation to a high-affinity HbS molecule and by stereospecific inhibition of T state HbS polymerization. Because vanillin is a food additive on the GRAS (generally regarded as safe) list, and because it has little or no adverse effects at high dosages in animals, vanillin is a candidate for further evaluation as an agent for the treatment of sickle cell disease.

Anemia, Sickle Cell↗
PubMed1989

Poland and US collaborative study on cardiovascular epidemiology. I. Introduction and baseline findings.

The Poland-US Agreement for Health Cooperation has as its goal the sharing of scientific information in cardiovascular disease epidemiology between the two countries. Patterns of cardiovascular disease and identification of risk factors were investigated through two large epidemiologic studies, the Pol-Monica Study in Poland and the US Lipid Research Clinics Program Prevalence Study in the United States. These two studies are described with regard to methodological issues, comparability of data collection procedures, and demographic and behavioral characteristics of the two populations involved. Mean blood pressure, lipids, and body mass indices of participants in these studies are also compared.

Adult↗
PubMed1989

Poland and US collaborative study on cardiovascular epidemiology. III. Correlates of systolic and diastolic blood pressure in men and women aged 35-64 years from selected Polish rural, Polish urban, and US samples.

Three diverse samples of men and women aged 35-64 years living in urban Poland, rural Poland, and the United States are described and subsequently analyzed using systolic blood pressure and diastolic blood pressure separately as dependent variables in multiple regression. Several demographic, behavioral, and biologic factors are included in the models as independent variables. Heart rate, Quetelet index, high density lipoprotein cholesterol, and the natural logarithm of triglycerides were statistically significant in accounting for variation in systolic pressure in men in all three samples, whereas only heart rate and Quetelet index were significant in women in all samples. In the analysis of diastolic pressure, Quetelet index, heart rate, and ethanol consumption were statistically significant in men in all three samples, while only Quetelet index and heart rate were significant in women in all samples.

Adult↗