Biomedical subjects

R A Coates

Publications and source records attributed to R A Coates.

At least 19 recordsLinked to original sources

PubMed1999

Renal effects of amlodipine in normotensive renal transplant recipients.

Renal effects of amlodipine in normotensive renal transplant recipients. The use of cyclosporin A (CsA) has improved the success of renal transplantation, but is associated with hypertension and significant renal toxicity. Previous reports suggest that calcium channel blockers may be useful in opposing the adverse effects of CsA. We have evaluated the effects of amlodipine (5 mg, once daily for 8 weeks) on renal function in 27 normotensive renal transplant recipients with stable renal function, in a double-blind, placebo-controlled, multicentre, cross over study. Amlodipine significantly reduced serum creatinine concentration relative to placebo (mean+/-SD: 168+/-65 vs 177+/-66 micromol/l; P=0.002) and there was a strong trend towards an increase in effective renal plasma flow on amlodipine relative to placebo (238+/-92 vs 217+/-87 ml/min; P=0.055). Glomerular filtration rate and lithium clearance were unaffected. Trough CsA blood concentration was unaffected. Amlodipine was well tolerated, with a low incidence of adverse events, and did not affect blood pressure or heart rate. In conclusion, amlodipine reduced serum creatinine in normotensive renal transplant recipients after only 8 weeks treatment, and was well tolerated in concomitant administration with CsA.

Adolescent↗

PubMed1993

Ongoing high-risk sexual behaviors in relation recreational drug use in sexual encounters. Analysis of 5 years of data from the Toronto Sexual Contact Study.

The current study investigated the association between the use of recreational drugs at the time of sexual activity and high-risk sexual behavior in a Toronto cohort of 249 homosexual and bisexual men over a 5-year period commencing in 1984 to 1985 and concluding in 1989 to 1990. The main analysis was based on a total of 2536 visits. Univariate and multivariate Liang-Zeger regression models were used to relate the log of the sexual activity score (SARS) to the independent variables over the 20 follow-up visits while controlling for intercorrelations between variables from the same respondent. We found that there was a significant decline, over time, in the sexual activities that pose a higher risk of infection with human immunodeficiency virus. Recreational drugs still appear to be playing an important role in the continuation of higher-risk sexual activities. The use of poppers in conjunction with sex is a strong predictor of high-risk activity, as is use of alcohol and marijuana in conjunction with sex. Also, simultaneously strongly associated with higher-risk score is the Centers for Disease Control classification II. More emphasis needs to be placed on educating the population about the potential risks of combining reactional drugs with sexual activity.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Recurrent themes of concern in groups for health care professionals.

This paper reports of recurrent themes of concern about AIDS expressed by health care professionals participating in small group sessions. Three dominant themes emerged: fear of contagion, homophobia, and attachment and loss. For each of these themes the possible meanings are explored. Fear of contagion was the dominant theme and is discussed as both a possible expression of displaced homophobia and a 'catastrophic' risk factor (extreme negative consequence). The need of health care professionals to see themselves as 'different' from the person with AIDS is also discussed. Professionals also discussed the emotional burden of caring for young patients often similar in age to themselves. It is suggested that hospital policy makers need to accept the reality of staff concerns and provide adequate forums for expression of concerns since without an opportunity for thoughtful discussion, health care professionals may espouse the 'correct' position and attitude, but believe and practise something else.

Attitude of Health Personnel↗

PubMed1992

Varied potential risks of HIV infection among prostitutes.

To date, most HIV prevention programs targeting North American prostitutes have focused on individual behaviour change, and in particular, the consistent use of condoms between prostitutes and their clients. The organizational and societal level issues which may influence high risk practices within the working and private spheres have received relatively little attention. In addition, most prevention efforts have been limited to targeting the sub-population of street prostitutes. We outline here three different types of prostitutes (street prostitutes, escorts, and prostitutes who work part time in the service sector, i.e. barmaids and erotic massage therapists) known to work in many North American centres. In doing so, we suggest that potential risks of infection vary according to the type of prostitution, and that prevention programs must recognize the diversity in potential risk practices. Differences in the organization of work and working conditions of varied types of prostitutes may, in particular, influence risk practices while working. Some of the individual, organizational and societal level issues which influence risk practices among different types of prostitutes are presented. Much of the research involving HIV and prostitutes has accessed prostitutes at sites where street prostitutes are over-represented. Other studies are based on potentially baised samples as they have recruited prostitutes from medical clinics. Methodologic problems that influence attempts to obtain a representative sample of the prostitute population are discussed.

HIV Infections↗

PubMed1992

Using serial observations to identify predictors of progression to AIDS in the Toronto Sexual Contact Study.

The Toronto Sexual Contact Study comprises a cohort of 249 male sexual contacts of men with HIV disease which has been followed every 3 months for almost 5 years. On enrollment 143 were seropositive and 16 seroconverted during the follow-up period. By 31 December 1989, 41 of the 159 seropositive cohort members had developed AIDS. Using Cox relative risk regression models, we investigated the association of a number of laboratory and clinical variables and progression to AIDS. Fixed covariate models examined laboratory variables from the enrollment visit of cohort members, with time calculated from this date. In models assessing time dependent covariates, time was calculated from the estimated date of HIV infection. In the univariate models of either fixed or time dependent covariates, many variables were significantly associated with risk of progression to AIDS (T4 cell count, T4/T8 ratio, blastogenic responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen, serum IgA, appearance of p24 antigen, and the development of oral hairy leukoplakia, thrush, or herpes zoster). Appearance of persistent generalized lymphadenopathy was not associated with increased risk of progression. In the multivariate model which evaluated fixed laboratory covariates, T4/T8 ratio, IgA level, and PHA response at enrollment were significantly associated with elevated risk.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS Serodiagnosis↗

PubMed1992

Fear of contagion and AIDS: nurses' perception of risk.

Nurses' fear of contagion when caring for persons with AIDS remains high despite increased levels of knowledge. This paper examines the multiple factors that contribute to nurses' perception of risk within the workplace. The authors suggests that constructs from theories such as decision making, psychoanalysis and cognitive psychology can provide insight into the assessment of risk. Findings from a recent survey of nurses are used to illustrate the complex nature of fear of contagion. Understanding this complexity may be an essential first step in order to provide opportunities for resolution of fears and modification of behaviors.

Acquired Immunodeficiency Syndrome↗

PubMed1992

A randomized trial of group interventions for hospital staff caring for persons with AIDS.

The purpose of this study was to develop an educational package for health care providers. Findings from a survey conducted by investigators were used to direct intervention content. All subjects received a 1 hour educational package. Since this type of intervention was not expected to be sufficient to modify attitudes and concerns, 75% of the subjects received an additional 1 hour group discussion intervention (n = 118). In a subgroup of those receiving group interventions, the discussion was preceded by the presence of a person with AIDS (PWA) (in person or on video) discussing his personal experience with the illness and health care workers. It was demonstrated that in order to modify change attitudes, concerns, and affective response, groups were necessary. Furthermore, fear of risk of contagion and homophobia required the presence of a PWA (in person or on video) in order for change to occur.

Acquired Immunodeficiency Syndrome↗

PubMed1992

The probability of progression to AIDS in a cohort of male sexual contacts of men with HIV disease.

In a cohort of 249 male sexual contacts of men with AIDS or an AIDS-related condition (ARC), 143 cohort members were seropositive on enrollment and 16 seroconverted during follow-up. A logistic Weibull mixture model was used to estimate the probability of progression to AIDS after HIV infection when infection was assumed to occur during the period of sexual contact with the primary case. Forty cohort members developed AIDS while under study. It appears that at least 50% of men with HIV disease will progress to AIDS and that the best estimate of this probability lies anywhere in the interval 70% to 100%.

Acquired Immunodeficiency Syndrome↗

PubMed1992

An efficacy trial of a mammalian cell-derived recombinant DNA hepatitis B vaccine in infants born to mothers positive for HBsAg, in Shanghai, China.

We conducted a randomized, double-blind clinical trial of an experimental mammalian cell-derived DNA hepatitis B vaccine (Betagen, Connaught Laboratories Ltd, Toronto, Canada) to determine its efficacy in infants born to mothers who were carriers of hepatitis B surface antigen (HBsAg). Four groups of 55 infants received injections as follows: (1) a licensed plasma-derived vaccine (Lanzhou, Lanzhou Institute for Biological Products, Lanzhou, People's Republic of China), 20 micrograms; (2) Betagen, 20 micrograms; (3) Betagen, 20 micrograms+hepatitis B immune globulin (HBIG); and (4) Betagen, 10 micrograms+HBIG. Vaccine injections were given at birth and at 1 and 6 months and HBIG was given at birth. The vaccines were compared to a historical placebo control group. The efficacy of Betagen alone was 82.6% compared to 51.0% for the Lanzhou. Efficacy of Betagen increased with the concomitant use of HBIG. No infants who were HBsAg negative at birth and/or were born to hepatitis B e antigen (HBeAg) negative mothers became carriers. The rate of HBsAg in infants receiving Betagen alone, and born to mothers who were HBeAg positive, decreased from 60% at birth to 20% by the ninth month, compared to 62.5% and 50% (respectively) for Lanzhou. The percentage of infants with protective levels of antiHBs was significantly higher for Betagen alone than for Lanzhou, but the geometric mean titre of antiHBs for responders was not significantly different. We have shown that Betagen alone is highly efficacious in preventing the development of hepatitis B in infants born to mothers who are carriers of HBsAg and is also highly effective in reducing the carriage of HBsAg in infants who are HBsAg positive at birth and/or born to HBeAg positive mothers.

Carrier State↗

PubMed1992

The Ontario HIV seroprevalence study of childbearing women: results from the first year of testing.

The Ontario HIV Seroprevalence Study of Childbearing Women is an unliked anonymous seroprevalence study designed according to the well-established ethical and legal guidelines for such studies. Commencing in November, 1989, randomly selected neonatal heelprick specimens were tested for the presence of HIV antibodies after all identifying information had been permanently and irrevocably unlinked from the specimens. During the first year of the study 94,119 (approximately 60% of all submitted specimens) were tested. Twenty-six specimens which were repeatedly reactive by EIA were confirmed as positive for an overall crude seroprevalence rate of 2.8 per 10,000 women having live births (95% CI: 1.8-4.1). Twenty-five of the 26 confirmed seropositive results came from babies born in hospitals in the Metropolitan Toronto, Ottawa-Carlton, or Hamilton-Peel-Halton regions.

Adult↗

PubMed1991

Changing trends of cirrhosis mortality in Ontario, Canada, 1911-1986.

Cirrhosis mortality death rates in Ontario for ages 20 and over declined from a high of 9.3 per 100,000 in 1911 to a low of 5.6 per 100,000 in 1919 (p less than 0.001) and after a 17-year period of relative stability, rose steadily to a high of 19.7 per 100,000 in 1975 (p less than 0.0001) and then declined to 13.3 per 100,000 in 1986 (p less than 0.001). Rates were consistently higher for men than for women and the male to female ratio of the rates increased from a low of 1.3 in 1933 to a high of 2.5 in 1986. The rate of increase in the rates for both men and women, and the rate of decline after the mid 1970s was most noted in the younger ages. Differences in trend could not be related to changes in disease classification, method of recording deaths, changes in diagnostic habits such as introduction of needle liver biopsy or to method of standardizing the rates. There was a positive and significant correlation between per capita alcohol consumption and rates of cirrhosis in Ontario from 1932 to 1975. However, while cirrhosis rates declined markedly from 1976 to 1986, alcohol consumption remained stable from 1976 to 1980 and declined only slightly from 1981 to 1986. A possible explanation for lack of correlation between alcohol consumption and the cirrhosis rates from 1976 to 1986 could be that the balance of force favoured recovery i.e. those people who already had cirrhosis who decreased (or stopped) their consumption of alcohol, did not die. Correlations with lagged alcohol consumption could not explain all the changes in the cirrhosis rates. Although cirrhosis rates consistently increased with increasing age from 35 to 85, our results showed that succeeding generations were developing cirrhosis at successively younger ages after the age of 35. Possible explanations for this cohort effect are increased survival from infectious diseases in infancy and childhood, increase in hepatitis B infection, excessive drinking habits being established at younger ages or a change in the pathogenesis of the disease.

Adult↗

PubMed1991

Comparison of saliva and blood for human immunodeficiency virus prevalence testing.

Testing saliva for the detection of human immunodeficiency virus (HIV) antibodies has many potential advantages for epidemiologic surveillance. A commercial ELISA kit and a standardized in-house immunoblot (IB) system were slightly modified to enhance antibody detection in saliva. Frozen saliva specimens from Toronto Sexual Contact Study participants (including sequential saliva specimens collected during seroconversion) were tested as were fresh saliva samples collected from a population of street-based intravenous drug users (IVDUs). HIV antibody results on saliva were compared with HIV serostatus determined by ELISA and IB on serum or dried blood spots. The overall sensitivity was 98.3% (117/119) for the kit and 99.2% (118/119) for IB; the specificity was 100% (429/429). In the IVDU population, compliance in the voluntary submission of specimens increased from 69% agreeing to provide blood samples to 89% agreeing to provide blood, saliva, or both. Saliva specimens can be easily collected under difficult field conditions with minimal training and provide a valuable alternative to testing blood for HIV-seroprevalence studies.

Cohort Studies↗

PubMed1991

Comparison of three HIV antigen detection kits in sequential sera from a cohort of homosexual men.

HIV antigen detection kits are available from a number of commercial sources. Abbott, Coulter, and Du Pont antigen kits were used to test 661 sera collected sequentially from 65 members of the Toronto Sexual Contact Study (TSCS). The sera had been collected at 3-month intervals over 4 years from nine persistently HIV-seronegative men, 14 seroconverters, and 42 seroprevalent participants. Antigen was not detected in any seronegative men. Two of 14 seroconverters were antigen positive in the specimen immediately preceding seroconversion (by all kits). Antigen was detected in 22 of 56 seropositive participants; of these, 16 of 22 demonstrated the emergence of antigen during observation. Discrepancies were noted in the time of detection of antigen (ranging from 3 months to more than 3 years) in nine participants. Although overall concordance among all kits for all specimens appears high (95.4%), when the bias introduced by testing multiple specimens from the same patient is removed, the lower bound of concordance among all three kits is estimated to be 80%. Similarly, after correction, the upper and lower bound of estimates of sensitivity are Abbott 96, 92%; Coulter 88, 63%; and Du Pont 88, 58%. There are significant differences in the performance characteristics of these commercial products for the detection of HIV antigen in serum.

AIDS-Related Complex↗

PubMed1990

Underreporting of AIDS cases in Canada: a record linkage study.

To estimate the rate of underreporting of AIDS (acquired immune deficiency syndrome) to the Federal Centre for AIDS (FCA), in 1988 the initials, date of birth and place of residence of 66 patients with AIDS known to the Toronto Sexual Contact Study (TSCS), 65 patients with AIDS known to the Vancouver Lymphadenopathy-AIDS Study (VLAS) and other participants in both studies who did not have AIDS were sent to the Bureau of Epidemiology and Surveillance, FCA. The FCA conducted a manual record linkage to link these data to the national registry of reported cases. The rate of underreporting was 12% (8/65) for the VLAS and 18% (12/66) for the TSCS. The specific diagnosis was not related to the rate of underreporting. For the TSCS the rate of underreporting had increased from 0% in 1983-84 to 44% in 1987-88 (p = 0.001). Differences in the observed rates of underreporting between the two studies are likely the result of differences in the reporting responsibilities of physicians involved in the studies.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Cofactors of progression to acquired immunodeficiency syndrome in a cohort of male sexual contacts of men with human immunodeficiency virus disease.

In a cohort of 249 male sexual contacts of men with acquired immunodeficiency syndrome (AIDS) or an AIDS-related condition in Toronto, Ontario, Canada, 143 cohort members were seropositive on enrollment and 16 seroconverted between initial recruitment in July 1984 to July 1985 and December 1988. Data on age, smoking and drinking status, recreational drug use, and history of sexually transmitted diseases and other diseases were obtained from interviews at induction and during follow-up on the cohort members every 3 months. Cox relative risk regression models, in which time was calculated from estimated date of human immunodeficiency virus (HIV) infection for seroprevalent cohort members and from 90 days prior to the first positive test for seroconverters, examined the potential effect of use of a variety of recreational drugs and the occurrence of selected infections on the risk of development of AIDS. Thirty-five cohort members developed AIDS while under study. No significant association with risk of progression to AIDS was noted for use of various recreational drugs (singly or in combination), history of specific infections, age at enrollment, or smoking and drinking status at enrollment. Only estimated duration of HIV infection appeared to be associated with increasing risk of development of AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1990

A randomized double-blind clinical trial of a mammalian cell-derived recombinant DNA hepatitis B vaccine compared with a plasma-derived vaccine.

Eight hundred volunteers from heath care and emergency fields participated in a randomized double-blind clinical trial of a new experimental mammalian cell-derived recombinant DNA hepatitis B vaccine (Betagen) compared with a licensed plasma-derived vaccine (Heptavax-B). Vaccine injections (20 micrograms) were administered intramuscularly at 0, 1, and 6 months, and sera were tested at 0, 1, 2, 3, 6, 7, and 12 months for hepatitis B surface antigen, antibody to hepatitis B surface antigen, and antibody to hepatitis B core antigen. Data from 745 vaccinees (93.1%), analyzed at the 7th month of follow-up, showed no significant difference in the seroconversion rates for Betagen (94.4%) vs Heptavax-B (97.3%), but the geometric mean titer of antibody was significantly higher for Heptavax-B (11 833 mIU/L) than for Betagen (4628 mIU/mL). The antibody response of Betagen was significantly and independently related to age and sex, while that of Heptavax-B was related to age only. Reported side effects from both vaccines were minor and mild, with approximately one fourth of all vaccinees reporting at least one side effect. Vaccinees, who had a protective level of antibody at the 7th month, were tested for antibodies at the 12th month. Of those in the Betagen-vaccinated group and those in the Heptavax-B-vaccinated group, 99.0% and 100%, respectively, were still protected. There was a proportionately larger decline in the geometric mean titers of antibody to hepatitis B surface antigen for Heptavax-B than for Betagen.

Adult↗

PubMed1989

Mortality and hospital morbidity from cirrhosis of the liver in relation to per capita consumption of absolute alcohol, education and native status, Ontario; 1978 to 1982.

Correlation and regression analyses have been carried out to test the hypothesis that areas experiencing high per capita consumption of absolute alcohol will also experience correspondingly higher annual rates of cirrhosis, in Ontario from 1978 to 1982. Adjustment was made for the influence of socio-demographic variables upon hospital morbidity and mortality rates. Areas experiencing higher per capita consumption of absolute alcohol were found to have higher hospital morbidity. The relationship between hospital morbidity and general mortality from cirrhosis, and per capita consumption of absolute alcohol appears to be growing weaker; no relationship could be demonstrated, however, between cirrhosis mortality and hospital morbidity and proportionate native population and education status.

Adult↗

PubMed1989

Kaposi's sarcoma and AIDS: a variable spectrum.

A cohort of 61 patients with Kaposi's sarcoma (KS) and AIDS was seen in the Oncology Unit of the Toronto General Hospital between 1982 and 1986. In an attempt to identify prognostic variables, laboratory and clinical parameters were examined using Kaplan-Meier estimates and the Cox Regression Model. All patients were male, median age 36 years (range 23-52). In 49 patients KS was diagnosed before any AIDS-associated opportunistic infection (OI). Three patients had concurrent KS and OI, and nine patients developed KS one or more months after an OI. Only 11 patients had stage I or II disease, 34 stage III, and 15 stage IV. Only 18 patients (30%) were asymptomatic. Twenty-six percent had fever, night sweats, or weight loss, 11% had minor opportunistic infections, and 33% had both symptom complexes. The median overall survival was 10.5 months. The survival of patients who received chemotherapy for their KS was not significantly different from the survival of non-treated patients (p = 0.7). Although significant differences in survival could not be seen between stages, patients with both systemic symptoms and minor opportunistic infections had significantly shorter survival (p = 0.03). Survival from the onset of KS was significantly shorter for patients who had experienced a previous OI, but their overall survival from the date of diagnosis of AIDS was not significantly different from those patients presenting with KS alone. When analyzed separately the laboratory parameters of hemoglobin (p less than 0.0001), absolute lymphocyte count (p = 0.03), platelet count (p = 0.04), and T4 level (p = 0.05) demonstrated a significant relationship with survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗