Search PubMed⌕ Search

Biomedical subjects

T Stephens

Publications and source records attributed to T Stephens.

At least 19 recordsLinked to original sources
PubMed2001

Tattooing and body piercing among adolescent detainees: relationship to alcohol and other drug use.

PURPOSE: The purpose of this preliminary study was to document self-reported tattooing and body piercing behavior among a sample of 860 adolescent detainees. Additionally, the study examined the relationship of alcohol and drug use to tattooing and body piercing--an often overlooked HIV risk behavior. METHODS: Adolescents (N = 860) participating in a substance use and HIV risk reduction intervention were surveyed upon entrance to a Youth Development Campus (YDC). RESULTS: Twenty-nine percent of the sample (N = 245) had at least one tattoo, and more than half (69%) had at least one body piercing. Fifteen percent had two or more tattoos, while 28% had three or more piercings. Although a small percentage of the youth reported knowingly sharing needles for tattoos or piercings (2% and 1.5%, respectively), 21% had tattoos that had been administered unprofessionally and 20% had unprofessionally administered piercings. Marijuana and alcohol were the highest reported substances used in this sample, 62% and 54%, respectively. Alcohol, marijuana, antidepressants, and sedatives were significant correlates of having tattoos. Alcohol was found to be a marginally significant (P = .052) correlate of body piercing. CONCLUSION: The popularity of tattooing and piercing and the risk involved with these activities make them an HIV risk behavior worthy of address. Risk reduction messages to youth should consistently address these behaviors and focus on them as they relate to substance use.

Adolescent↗
PubMed2001

Comprehensive tobacco control policies and the smoking behaviour of Canadian adults.

OBJECTIVE: To examine the associations of cigarette prices, restrictions on public smoking, and health education with the odds of adult smoking and amount smoked daily. DESIGN: Multi-level analysis of adult (age 25+) smoking patterns in Canada's National Population Health Survey, after adding administrative data on prices, bylaws, and health education according to the survey respondent's place of residence. SETTING/SUBJECTS: Population based sample of Canadians age 25+ in households (n = 14 355). OUTCOME MEASURES: Smoking status, amount consumed daily. ANALYSIS: Logistic regression for smoking status, multiple regression for amount smoked, with controls for age, education, marital status; separate analyses for men and women. RESULTS: Cigarette prices were positively associated with the odds of being a non-smoker and negatively with amount smoked, for adults of both sexes. Per capita health education expenditures were positively associated with the odds of being a non-smoker and negatively with amount smoked--for men but not women. The restrictiveness of municipal bylaws limiting public smoking was positively associated with the odds of being a non-smoker and negatively with amount smoked--for women but not men. These results are independent of age, education, and marital status. CONCLUSIONS: To be effective, tobacco control must comprise a mix of strategies as men and women respond differently to health education and restrictions on public smoking; taxation, reflected in higher cigarette prices, is the only one of these measures related to smoking for both sexes. This model permits calculations of the level of increase in each measure that is required to reduce the prevalence of smoking by a specified amount.

Adult↗
PubMed2001

Apolipoprotein E: possible therapeutic target for atherosclerosis.

Human apolipoprotein E (apoE) consists of a single polypeptide chain with 299 amino acids and is best known for its role in the transport of cholesterol and other lipids between peripheral tissues and the liver. However, more direct effects of apoE on the vascular wall may well contribute to arterial protection from atherosclerosis. This review will focus on: (a) the ability of apoE to direct cholesterol efflux mechanisms with the aid of apoA1 and the ATP binding cassette transporter 1 (ABC1); (b) the ability of apoE to prevent platelet aggregation by facilitating the production of endogenous nitric oxide (NO); (c) the ability of apoE to inhibit the proliferation of T-lymphocytes by internalization of the IL-2 receptor; and (d) the ability of apoE to inhibit proliferation of endothelial cells by out competing growth factors for interaction with cell surface heparan sulfate proteoglycans (HSPG's). The characterization of apoE and its many functions has provided insight into the ultimate potential of this protein as a possible therapeutic agent for the treatment of atherosclerosis. This review will examine key scientific advances, which focus on possible therapeutic strategies that encompass the use of apoE in the amelioration of atherosclerosis.

Animals↗
PubMed2001

The economic burden of mental health problems in Canada.

This study provides a comprehensive estimate of the economic burden of mental health problems in Canada in 1998. In particular, it estimates the cost of non-medical services that have not been previously published and the value of short-term disability associated with mental health problems that were previously underestimated according to the definitions used here. The costs of consultations with psychologists and social workers not covered by public health insurance was $278 million, while the value of reduced productivity associated with depression and distress over the short term was $6 billion. Several data limitations suggest that these are underestimates. The estimated total burden of $14.4 billion places mental health problems among the costliest conditions in Canada.

Adult↗
PubMed2000

Commentary. monitoring tobacco use in canada: the need for a surveillance strategy.

Smoking behaviour has been monitored nationally through population surveys for 35 years in Canada, but these surveys have not been as consistent or rigorous as the magnitude of the smoking problem demands. Inconsistent methods and irregular survey intervals are just two of the characteristics that have made it difficult to know exactly how smoking is changing. Further, an absence of routine data on tobacco control policies (other than the price of cigarettes) has hampered understanding of the determinants of changing prevalence. The advent of two survey series--Canadian Tobacco Use Monitoring Survey (CTUMS) and Canadian Community Health Survey (CCHS) promises to change this situation for the better. We suggest that both are critical elements of a national smoking surveillance system and that, with a commitment to CTUMS in particular, Health Canada could set a new international standard for surveillance.

Canada↗
PubMed2000

School-based smoking prevention: economic costs versus benefits.

The objective of this study was to conduct a cost-benefit analysis to compare the costs of developing and delivering an effective school-based smoking prevention program with the savings to be expected from reducing the prevalence of smoking in the Canadian population over time. A smoking prevention program that meets published criteria for effectiveness, implemented nationally in Canada, would cost $67 per student (1996 dollars). Assuming such a program would reduce smoking by 6% initially and 4% indefinitely, lifetime savings on health care would be $3,400 per person and on productivity, almost $14,000. The benefit-cost ratio would be 15.4 and the net savings $619 million annually. Sensitivity analyses reveal that considerable economic benefits could accrue from an effective smoking prevention program under a wide range of conditions.

Adolescent↗
PubMed1999

Predictors of homelessness among participants in a substance abuse treatment program.

Risk factors for homelessness were examined prospectively among recent participants in a substance abuse treatment program. Low levels of support from friends, greater depression, and recent substance use were bivariately associated with homelessness two months following completion of the program. However, friend support was the only factor associated with homelessness after controlling for other significant bivariate predictors.

Adult↗
PubMed1999

Transsexual orientation in HIV risk behaviours in an adult male prison.

The present study examined the consequences of being a self-reported transsexual male and HIV risk behaviours in a state penal system. The specific research question was whether or not sexual orientation of inmates influences the level to which they evidence HIV risk behaviours. A total of 153 participants volunteered to participate in the study of which 31 described themselves as being transsexual. Based on risk ratios and using transsexual inmates (TIs) as the reference group, they were 13.7 times more likely to have a main sex partner while in prison [95% CI=5.28, 35.58]. Moreover, TIs were 5.8 times more likely than non-transsexual inmates (NTIs) to report having more than one sex partner while in prison [95% CI=2.18, 15.54]. It is obvious from these findings that TIs require more preventive support than their NTI confederates. In addition to TIs being protected from assault and battery by NTIs, they need social support and carefully developed preventive informational materials.

Adult↗
PubMed1999

Mental health of the Canadian population: a comprehensive analysis.

This study examines eight measures of mental health and looks for associations with nine potential demographic and psychosocial determinants. Data from the National Population Health Survey (NPHS), analyzed by logistic regression, reveal consistently strong, graded, independent associations of current stress, social support, life events, education and childhood traumas with both positive and negative indicators of mental health status. Sex differences exist for four of eight measures. For most indicators, mental health is relatively poor among youth and improves with age. Physical and mental health problems are associated. There is no independent relation between mental health and income adequacy or province of residence. Two measures used in several previous Canadian surveys are recommended for inclusion in the NPHS to better monitor population mental health.

Adolescent↗
PubMed1999

Risks associated with tattooing and body piercing.

The purpose of this article is to highlight the importance of including cosmetic body-piercing and tattooing in HIV prevention and education. Little information about risks associated with tattoos or having one's body pierced is evident in the health promotion and disease prevention literature, particularly among adolescents, ethnic groups, and incarcerated populations. It is incumbent that preventionists address behaviors such as tattooing and body piercing as possible vectors for HIV transmission in addition to typical concerns (homosexuality, i.v. drug use, condom use and safer sex practices). This article draws attention to the need for formation of regulatory policy issues related to body piercing and tattooing parlors. Currently, 26 percent of the states have regulatory authority over tattooing establishments, while only 4 states exercise such authority over body-piercing establishments. Implications for future research and policy initiatives are identified.

Adolescent↗
PubMed1998

A relevant dose of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone is extensively metabolized and rapidly absorbed in the canine tracheal mucosa.

Lung cancer is largely a site-of-entry disease caused by inhaled carcinogenic agents, especially tobacco smoke. Two major groups of procarcinogens, tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons, are putative agents, but their relative contributions are disputed. An important indicator of relative potency for these compounds is the dose to the target epithelial cells. Although we have reported the dose of polycyclic aromatic hydrocarbons to the canine tracheal epithelium [Gerde et al., Carcinogenesis (Lond.), 18: 1825-1832, 1997; Gerde et al., Carcinogenesis (Lond.), in press, 1998], the purpose of the current study was to characterize the absorption and metabolism of low levels of one tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in the canine trachea. One hundred ng of tritiated NNK were instilled in the distal trachea of the dog. Blood was repeatedly sampled from the azygous vein and both sides of the systemic circulation from 15 s to 30 min after instillation. Tissues were then removed and analyzed for the tritiated NNK and its metabolites. Autoradiography was used to determine the depth distribution of tritium in the tracheal mucosa. Most NNK appeared rapidly in the blood draining the airway mucosa, but there was also a slow clearance phase. During absorption, NNK was distributed within the entire depth of the mucosa to the tracheal cartilage; however, a portion was conspicuously bound to the mucin component of the mucous lining layer. Reversible binding to mucin may be largely responsible for the slow clearance phase. Despite the rapid absorption of most of the tritium, NNK was nonetheless extensively metabolized in the tracheal mucosa. Systemic metabolism was also rapid: within 18 min of instillation, the NNK parent compound had disappeared from the systemic circulation, and 45 min after instillation, no NNK was found in the trachea or any distal tissue. Although the rapid absorption and distribution of NNK and its metabolites ensured widespread and extensive distal binding in all tissues, first-pass metabolism and activation of NNK in the airway mucosa were sufficiently rapid to cause levels of binding at the site of absorption to be approximately 20-fold those of distal tissues. NNK may thus act as a site-of-entry carcinogen. This observation may be important in estimating the contribution of NNK to lung cancer relative to other carcinogens and for explaining increased incidences of oral cancers in users of snuff and chewing tobacco in which NNK is present in high concentrations.

Absorption↗
PubMed1998

Model for using hip-hop music for small group HIV/AIDS prevention counseling with African American adolescents and young adults.

Currently little attention has been directed, with the exception of peer education efforts, to constructively develop new and innovative ways to promote HIV/AIDS primary prevention among African American (AA) adolescents and young adults. With this in mind, the aim of this conceptual effort is to present a HIV/AIDS preventive counseling protocol developed for use with AA young adults that makes use of hip-hop music, a form of music popularized by young AAs. The author contend that an increased understanding of the relationships that many AA young adults have with hip-hop music may be used by disease prevention personnel to educate these populations about protective factors for HIV. Making use of hip-hop music is one strategy for integrating counseling in prevention and health maintenance. The overall implications of using hip-hop music in health promotion are unlimited. First, this method makes use of cultural relevant materials to address the educational and health needs of the target community. Second, it is grounded in an approach that serves to stimulate cooperative learning based on peer developed content. Moreover, the use of this medium can be applied to other health promotion activities such as violence/harm reduction and substance abuse prevention, upon reviews of songs for appropriate content. The authors contend that such an approach holds heuristic value in dealing with HIV/AIDS prevention among AA young adults. Additional testing of the intervention is warranted in the refinement of this innovative intervention.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Comparison of plasma and tissue levels of ZD1694 (Tomudex), a highly polyglutamatable quinazoline thymidylate synthase inhibitor, in preclinical models.

ZD1694 (Tomudex, raltitrexed) is a specific quinazoline antifolate thymidylate synthase inhibitor that relies on polyglutamation for high potency. Antibodies to ZD1694 have been used to establish a sensitive radioimmunoassay as an alternative to high-performance liquid chromatography (HPLC). The radioimmunoassay is reproducible, accurate and provides a means of determining low levels of ZD1694 in plasma (< 1 nM). By virtue of the high cross-reactivity of the antibodies with polyglutamated forms of ZD1694, it is also possible to measure the total concentration of drug in tissues. Results obtained in L1210 mouse leukaemia cells and in mouse tissues were similar to those previously determined using radiolabelled drug. Pharmacokinetic studies in mice have confirmed that the compound is rapidly eliminated from the plasma and that there is a prolonged terminal elimination phase. ZD1694 was measured in plasma (0.56 ng ml(-1); 1.2 pmol ml(-1)) up to 7 days after a single i.p. dose of 100 mg kg(-1) ZD1694. Liver, kidney and gut epithelium had a substantially higher level of ZD1694 immunoreactivity than plasma. For example, 24 h after a single i.p. dose at 1, 10 and 100 mg kg(-1), total drug levels in the liver were 480, 325 and 152 times higher than plasma levels respectively. In kidney and gut epithelium, total drug levels at these doses were approximately 55 and 34 times those of plasma. The high tissue to plasma ratios were maintained for at least 7 days after administration. Similarly, high tissue to plasma ratios (> 100) were found in dogs treated with a clinically relevant dose of ZD1694. These were maintained for 4 weeks in liver and kidney tissue (> 100). Total gastrointestinal concentrations of ZD1694 were approximately 10 times higher than plasma 3 days after administration, but levels were near to the limit of detection at 4 weeks. These results are consistent with extensive polyglutamation of ZD1694 within tissues in both mice and dog and provide further support for the infrequent schedule that has been used clinically. Although it has not been possible to measure individual polyglutamated forms of ZD1694, the radioimmunoassay provides a convenient means of assessing total drug levels in tissues and is currently the only method suitable for measuring the extent of drug retention in normal tissue and tumour biopsies obtained from patients treated with ZD1694.

Animals↗
PubMed1998

Dynamic positron emission tomography with F-18 fluorodeoxyglucose imaging in differentiation of benign from malignant lung/mediastinal lesions.

PURPOSE: This study was done to evaluate the diagnostic utility of dynamic positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) imaging in patients with suspected malignant pulmonary lesions. We wanted to test the hypothesis that the rate of FDG uptake (FDG influx constant values) would differentiate malignant from benign lung or mediastinal lesions. MATERIALS AND METHODS: We performed segmental dynamic PET imaging studies following administration of FDG in 19 patients with indeterminate pulmonary lesions based on chest radiograph and/or CT scans. Patlak analysis was done to compute Ki (FDG influx constant) values and compared with FDG standardized uptake values (SUVs) and histology. RESULTS: FDG Ki values (mean+/-SD) were significantly greater (p < 0.01) in all 12 malignant lesions (0.029+/-0.02) as compared with 7 benign lesions (0.0024+/-0.0011) with good correlation to the SUV values. Distinct time activity curve patterns were identified in malignant and benign lesions with continued uptake in malignant lesions. CONCLUSION: Dynamic PET-FDG imaging accurately differentiates malignant from benign pulmonary lesions. In certain cases with equivocal findings on visual analysis and SUV values, dynamic imaging may be further helpful in differentiating benign and malignant lesions.

Adenocarcinoma↗
PubMed1997

Phototoxic reactions caused by sodium fluorescein.

PURPOSE: To report three cases of phototoxic reactions to intravenous fluorescein for retinal angiography and to describe provocative testing in a volunteer. METHODS: Three patients with phototoxic reactions were interviewed, and one volunteer underwent a controlled challenge test by applying a potent sunscreen and exposing skin areas to direct sunlight before and after fluorescein administration. RESULTS: All patients experienced marked cutaneous erythema, edema, and pain to sun-exposed areas within 1 hour of exposure. The reaction faded during a variable period of time, and one case resulted in mild epidermal desquamation and prolonged discomfort. We noted minimal skin changes in the volunteer who was exposed to the sun before fluorescein administration; however, marked blanching erythema and pain were noted after fluorescein administration and sunlight. CONCLUSIONS: Consistent with its in vitro properties as a photodynamic dye, fluorescein may rarely act as a phototoxic agent in humans at doses employed for fluorescein angiography.

Adult↗
PubMed1997

Leptin and thermogenesis in humans.

We examined changes in serum leptin concentrations and thermogenesis in 12 healthy men (39 +/- 2 years, BMI 22.8 +/- 0.3 kg m-2) during a 4 h euglycaemic hyperinsulinaemia performed on a control day and after a day of competitive marathon runs. As compared with the control day, after the marathon, baseline FFA concentration (543 +/- 0.73 vs. 955 +/- 96 mumol L-1, P < 0.05), lipid oxidation rate (0.8 +/- 0.1 vs. 1.2 +/- 0.1 mg kg-1 min-1, P < 0.01) and energy expenditure (5.2 +/- 0.1 vs. 5.5 +/- 0.1 kJ min-1, P < 0.01) were elevated. Baseline serum leptin concentrations were similar on the control and postexercise days and increased during insulin infusion by 35-45% on both days (P < or = 0.01). Baseline serum leptin concentration correlated directly with serum insulin (r = 0.65, P < 0.05) and cortisol (r = 0.64, P < 0.05), and inversely with serum growth hormone concentration (r = -0.66, P < 0.05). In the postexercise study, the rise in energy expenditure during insulin clamp correlated with serum leptin concentration as determined before (r = 0.61, P < 0.05) or at the end of insulin infusion (r = 0.55, P < 0.05). Thus, in healthy individuals with normal body weight: (1) hyperinsulinaemia increases serum leptin concentrations; (2) a rise in energy expenditure correlates with serum leptin concentration. These data suggest that leptin is involved in the regulation of energy expenditure in humans.

Adult↗
PubMed1997

Serum leptin concentration and fuel homeostasis in healthy man.

We studied the interrelationship between the obese gene product serum leptin, insulin and counter-regulatory hormone concentrations and glycogen synthesis in 26 healthy men. A 4-h euglycaemic insulin clamp with muscle biopsies was performed after a resting control day in 26 subjects, and in 14 of them also after heavy, glycogen-depleting (32%, P < 0.01) exercise. Serum leptin concentrations were at baseline 34% (0.67 +/- 0.18 vs. 1.03 +/- 0.13 ng L-1, P < 0.05) lower after the exercise, and rose during hyperinsulinaemia by 56% (to 1.38 +/- 0.19 ng L-1, P < 0.001) and 34% (to 1.05 +/- 0.20 ng L-1, P < 0.01) after the post-exercise and control studies respectively. Basal serum leptin concentration correlated positively with body mass index (r = 0.42, P < 0.05), serum cortisol concentration (r = 0.70, P < 0.001) and the rise in muscle glycogen content during the clamp (r = 0.43, P < 0.05) and inversely with serum growth hormone concentration (r = -0.43, P < 0.05). There was a positive correlation between serum leptin after hyperinsulinaemia and serum insulin concentration during the hyperinsulinaemia (r = 0.42, P < 0.05). After exercise, basal serum leptin level correlated with serum triglyceride concentration (r = 0.82, P < 0.001) and after hyperinsulinaemi serum leptin correlated positively with muscle glycogen content (r = 0.56, P < 0.05). It was concluded that serum leptin concentrations correlate directly with serum insulin, cortisol and triglyceride and inversely with growth hormone concentrations. They are decreased by glycogen-depleting exercise and increase during hyperinsulinaemic clamp. These data suggest that leptin is associated with factors regulating fuel homeostasis and its hormonal control in man.

Adult↗