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Biomedical subjects

G Marks

Publications and source records attributed to G Marks.

At least 19 recordsLinked to original sources
PubMed2001

HIV-positive men's sexual practices in the context of self-disclosure of HIV status.

OBJECTIVE: To examine whether disclosure of HIV-positive status to sex partners at risk for HIV infection is associated with safer sex practices and to examine the prevalence and correlates of specific disclosure/sexual behavior patterns. METHODS: Cross-sectional assessment of 206 HIV-positive men (41% homosexual, 35% bisexual, 24% heterosexual) sampled randomly at an outpatient HIV clinic in Los Angeles, who reported that their most recent sex partner was HIV-negative or of unknown serostatus. Unsafe sex was defined as unprotected anal or vaginal intercourse with that partner. RESULTS: Twenty-five percent of the men engaged in unsafe sex, and 48% of the total sample withheld disclosure from the partner. The prevalence of safer sex was not significantly higher among disclosers than among nondisclosers (unadjusted odds ratio = 1.29; 95% confidence interval: 0.69-2.45), and disclosure was not significantly associated with safer sex in any of 25 demographic or partner subgroups examined in the study. In the full sample, 40% of the men disclosed and engaged in safer sex (informed protection), 35% withheld disclosure and engaged in safer sex (uninformed protection), 12% informed their partner and engaged in unsafe sexual behavior (informed exposure), and 13% withheld disclosure and engaged in unsafe sex (uninformed exposure). Risky behavior patterns were associated with using alcohol/drugs before sex, having an HIV-unknown partner, being less emotionally involved with one's partner, and testing seropositive in the previous 3 years. CONCLUSIONS: Interventions for seropositive men that focus primarily on increasing disclosure of serostatus to sex partners may not reduce the prevalence of unsafe sex. Interventions are needed to address the social and psychologic processes that give rise to risky behavior patterns in HIV-infected men. Improved substance abuse counseling also may be needed.

Adult↗
PubMed2001

Are negative affective states associated with HIV sexual risk behaviors? A meta-analytic review.

This meta-analytic review examined whether negative affective states (depressive symptomatology, anxiety, anger) are associated with sexual behaviors that place people at risk for contracting or transmitting HIV. The results from 34 study samples were included in the analysis. Contrary to popular belief, the findings as a whole provide little evidence that negative affect is associated with increased sexual risk behavior. The average weighted correlation for the overall association was .05. The effect size was nonsignificantly higher for anger (r = .10) than for depressive symptoms (r = .04) or anxiety (r = .03). The variability of effect sizes was not accounted for by type of sexual risk measure, subject population, or methodological aspects of the studies. Conceptual and methodological limitations of the literature are identified and directions for future research are discussed.

Adult↗
PubMed2001

The unreliability of the Kato-Katz technique limits its usefulness for evaluating S. mansoni infections.

The Kato-Katz technique, a (semi) quantitative stool examination technique, is generally recommended for diagnosis and evaluation of Schistosoma mansoni infection by schistosome experts. However, egg counts are subject to important variability. In order to quantify the reproducibility of egg counts using the Kato-Katz technique, field data of 1255 observations on 299 subjects infected with Schistosoma mansoni were analysed. Agreement between repeated observations was assessed both categorically (kappa statistic) and continuously (analysis of variance). The day-to-day variation of egg counts was much greater than the variation due to different observers or different slides. The quantitative reproducibility was low: the weighted kappa statistic was 0.39 between specimens of different days, 0.62 between slides of the same specimen and 0.81 between observers of the same slide. Therefore the classification of individual patients into groups based on egg counts, used as a measure of morbidity, must be interpreted with great care, especially in longitudinal studies. Usefulness of the Kato-Katz technique appears limited. Its reproducibility is low. It cannot be recommended as a routine test in a primary health care setting or in a hospital laboratory because safety and detection of other parasites are better assured by other techniques. It can be used in epidemiological studies and evaluation of schistosomiasis control programmes, but here too, other techniques might be preferred.

Humans↗
PubMed2001

Effects of housing relocation on immunocompetence and psychosocial functioning in older adults.

BACKGROUND: The psychological and physical response to moderate life stressors among older adults has not been well characterized. This research examines effects of voluntary housing relocation on distress and immune function in healthy older adults as a model for studying the effects of moderate life stress. METHODS: Thirty older adults moving to congregate living facilities were assessed 1 month premove, 2 weeks postmove, and 3 months postmove. Twenty-eight nonmoving control subjects were assessed at similar time points. Subjects completed psychosocial questionnaires and had early morning blood draws in their homes. Blood samples were assayed for natural killer cell cytotoxicity (NKCC), interleukin-6 (IL-6), and IgG antibody titers to the Epstein Barr virus (EBV) viral capsid antigen. RESULTS: Movers demonstrated decreased vigor and elevated thought intrusion 1 month premove and 2 weeks postmove. By the 3-month follow-up, vigor increased, and intrusion decreased to levels commensurate with the controls. Averaged across all time points, movers showed lower NKCC than controls; however, post-hoc analyses indicate that by the 3-month follow-up time point, these differences were no longer significant. There were no differences between groups in IL-6 or in EBV antibody titers. Independent of the effects of group, higher levels of vigor were associated with greater NKCC at all assessments and with lower EBV titers at 2 weeks postmove. CONCLUSIONS: Findings suggest that in general, healthy older adults recover well psychologically from moderate. temporary life stressors such as moving. Whereas movers showed generally lower NKCC than controls, IL-6 and EBV antibody titers appeared not to be strongly affected by the stress of moving.

Adaptation, Psychological↗
PubMed2001

Use of V4R in patients who sustain blunt chest trauma.

OBJECTIVE: In blunt chest trauma, the right ventricle is more vulnerable than the left. The purpose of this study was to determine whether recording V4R in patients with blunt chest trauma would provide additional useful information to that already obtained from the standard 12-lead electrocardiogram (ECG). METHODS: Forty-five patients with blunt chest trauma and 40 unmatched control subjects without blunt chest trauma had standard 12-lead ECG and right precordial leads recorded. The ECGs were read blindly by three physicians. RESULTS: Patients with chest trauma were distinguishable from controls on the basis of the left-sided ECGs (odds ratio, 2.9; 95% confidence interval, 1.71-4.90). This was not the case using V4R (odds ratio, 1.23; 95% confidence interval, 0.59-2.0). CONCLUSION: Patients with a significant mechanism and physical findings of blunt chest trauma were more likely than controls to have an abnormal ECG. They were not more likely to have abnormalities in V4R. We recommend that a 12-lead ECG, but not V4R, be routinely obtained on these patients.

Adolescent↗
PubMed2001

Preferences about the characteristics of future HIV prevention products among men who have sex with men.

This study of men who have sex with men (MSM) examined preferences about the characteristics of a potential product for preventing sexual transmission of HIV, such as a rectal microbicide. MSM were recruited in West Hollywood, California. They self-administered a questionnaire and rated 48 product characteristics representing seven dimensions. Overall, the ratings were highest for effectiveness in preventing HIV and other sexually transmitted diseases, followed by characteristics reflecting the physical or secondary effects of the product and logistics of use. Physical attributes, convenience/accessibility, and psychological aspects had intermediate ratings; interpersonal dynamics had the lowest rating. Men with negative attitudes about using condoms to prevent HIV infection were more likely than their counterparts to prefer a product that does not reduce sexual sensation or pleasure, does not break the mood, and can be used after a sexual encounter ends. A similar pattern was observed when participants were stratified by whether or not they had engaged in unprotected anal intercourse in the past 12 months. The findings inform the development, testing, and marketing of a future HIV prevention product for MSM.

Adult↗
PubMed2001

The Circuit Party Men's Health Survey: findings and implications for gay and bisexual men.

OBJECTIVES: This study examined characteristics of gay and bisexual men who attend circuit parties, frequency of and motivations for attending parties, drug use and sexual behavior during circuit party weekends, and use of risk reduction materials available at parties. METHODS: A cross-sectional survey was conducted among 295 gay and bisexual men from the San Francisco Bay Area who had attended a circuit party in the previous year. RESULTS: One fourth of the men reported a drug "overuse" incident in the previous year. Nearly all respondents reported use of drugs during circuit party weekends, including ecstasy (75%), ketamine (58%), crystal methamphetamine (36%), gamma hydroxybutyrate or gamma butyrolactone (25%), and Viagra (12%). Two thirds of the men reported having sex (oral or anal), 49% reported having anal sex, and 28% reported having unprotected anal sex during the 3-day period. An association was found between use of drugs and sexual risk behavior. Prevention materials were observed at party events by some men; however, relatively few men used the materials. Common motivations for attending the parties were "to listen to music and dance" and "to be with friends." CONCLUSIONS: Intensive, targeted health promotion efforts are needed for gay and bisexual men who attend circuit parties.

Adult↗
PubMed2000

Is 'knowing people with HIV/AIDS' associated with safer sex in men who have sex with men?

OBJECTIVE: To examine the sexually protective role of knowing person(s) with HIV/AIDS (PWHA) by conducting a multidimensional analysis distinguishing the number of PWHA known (by disease status and relationship category) and aspects of the relationship with the closest PWHA (emotional closeness, length of time known, disease status, type of relationship). DESIGN: Cross-sectional study of white, Latino, and African-American men who have sex with men recruited at street locations in West Hollywood, California, in 1997. METHODS: The analyses conducted with linear regression models focused on men (n = 334) who reported that they were seronegative or of unknown serostatus and thus at risk for HIV infection. Unprotected sex was defined as percentage of anal intercourse partners in the past 12 months with whom unprotected anal intercourse (UAI) occurred at least once. RESULTS: The number of PWHA known was not associated with the percentage of UAI partners in multivariate or univariate analyses. Greater emotional closeness to a person who was HIV-positive without AIDS was associated with reduced UAI in multivariate models even after excluding participants whose close PWHA was a lover or sex partner. Younger men (18-25 years) knew fewer PWHA, reported less emotional closeness to a PWHA, and had a higher level of UAI than did older men. CONCLUSIONS: Emotional closeness to a seropositive person without AIDS may be a sexually protective factor. The results suggest the possibility that lower levels of emotional closeness to a PWHA may partially underlie the elevated sexual risk behavior of younger men who have sex with men.

Adolescent↗
PubMed2000

Preoperative chemoradiation in fixed distal rectal cancer: dose time factors for pathological complete response.

PURPOSE: Preoperative chemoradiation is being utilized extensively in the treatment of rectal cancer. However, a variety of dose time factors in both delivery of chemotherapy and irradiation remain to be established. This study was undertaken to examine the impact of dose time factors on pathological complete response (pCR) rates following preoperative chemoradiation for fixed rectal cancer. METHODS AND MATERIALS: Thirty-three patients with fixed rectal cancers were treated with combined 5-fluorouracil (5-FU) chemotherapy and pelvic radiation. Twenty-one patients received bolus 5-FU during the first 3-5 days of radiation and repeated on days 28-33 of their radiation treatment. Twelve patients were treated with continuous infusion (CI) 5-FU, 225 mg/m(2) for the duration of the pelvic radiation. Fifteen patients received a planned total radiation dose of 45 to 50 Gy and 18 patients received a dose of 55 to 60 Gy. Surgical resection was then carried out 6-8 weeks after completion of treatment. RESULTS: Diarrhea was the most frequent acute toxicity. Grade 3 diarrhea was observed in 6 patients requiring treatment interruption and was not related to the chemotherapy regimen. There was no Grade 4 or 5 toxicity. pCR was observed in 2 of 21 (10%) patients treated with bolus 5-FU as compared to 8 of 12 (67%) for patients treated with CI (p = 0.002). pCR were observed in 8 of 18 (44%) patients receiving radiation dose > or = 5500 cGy as compared to 2 of 15 (13%) patients treated to a dose < or = 5000 cGy (p = 0.05). In the high-dose radiation (> or = 5500 cGy) group, a significant difference in pCR rate was observed in patients treated with CI, 8 of 12 (67%) (p = 0.017) as compared with bolus 5-FU (0 of 6). There was no significant difference in operative morbidity or in wound healing between patients treated with bolus 5-FU or CI or within the groups treated with low or high doses of radiation. Three patients have developed local recurrence at 14 and 24 months, two in the low-dose group treated with bolus 5-FU and one patient in the CVI group. The overall 5-year survival for the whole group is 71%. CONCLUSION: Dose intensity of 5-FU and dose of radiation correlate significantly with the likelihood of achieving a pCR. Continuous infusion 5-FU (CI) and a preoperative radiation dose of 5500 cGy or higher can achieve pCR rates of approximately 50%, even in fixed cancers of the rectum.

Adult↗
PubMed2000

Age-related risk for HIV infection in men who have sex with men: examination of behavioral, relationship, and serostatus variables.

The study examined behavioral, relationship, and serostatus variables that potentially contribute to HIV infection risk in three age groups of men who have sex with men (MSM). MSM recruited in West Hollywood, California self-administered a questionnaire measuring unprotected insertive anal intercourse (UIAI) and unprotected receptive anal intercourse (URAI) with primary and nonprimary partners. The following relationship/serostatus variables were also assessed: recency of HIV testing, knowledge of own HIV serostatus, perception of partner's serostatus, seroconcordance (self and partner seronegative), and self-reported monogamy status. The prevalence of UIAI and URAI was higher with primary than nonprimary partners. These sexual risk behaviors with primary partners were substantially more prevalent among men younger than 25 years of age than among men aged 25 to 30 or over age 30. UIAI and URAI with nonprimary partners were uncommon in each age group, and there were no significant age differences on the serostatus and relationship variables. The findings suggest that young MSM may be at elevated risk for contracting HIV by virtue of their sexual risk behavior with primary partners. Targeted interventions for MSM need to address sexual risk in the context of primary relationships.

AIDS Serodiagnosis↗
PubMed1999

Differences between asthma exacerbations and poor asthma control.

BACKGROUND: Increased variation in peak expiratory flow (PEF) is characteristic of poorly controlled asthma, and measurement of diurnal variability of PEF has been recommended for assessment of asthma severity, including during exacerbations. We aimed to test whether asthma exacerbations had the same PEF characteristics as poor asthma control. METHODS: Electronic PEF records from 43 patients with initially poorly controlled asthma were examined for all exacerbations that occurred after PEF reached a plateau with inhaled corticosteroid treatment. Diurnal variability of PEF was compared during exacerbations, run-in (poor asthma control), and the period of stable asthma before each exacerbation. FINDINGS: Diurnal variability was 21.3% during poor asthma control and improved to 5.3% (stable asthma) with inhaled corticosteroid treatment. 40 exacerbations occurred in 26 patients over 2-16 months; 38 (95%) of exacerbations were associated with symptoms of clinical respiratory infection. During exacerbations, consecutive PEF values fell linearly over several days then improved linearly. However, diurnal variability during exacerbations (7.7%) was not significantly higher than during stable asthma (5.4%, p=0.1). PEF data were consistent with impaired response to inhaled beta2-agonist during exacerbations but not during poorly controlled asthma. INTERPRETATION: Asthmatics remain vulnerable to exacerbations during clinical respiratory infections, even after asthma is brought under control. Calculation of diurnal variability may fail to detect important changes in lung function. PEF variation is strikingly different during exacerbations compared with poor asthma control, suggesting differences in beta2-adrenoceptor function between these conditions.

Adolescent↗
PubMed1999

Methods and effectiveness of environmental control.

In recent years the role of allergen exposure and atopy, and the interaction between them in the clinical expression of allergic disease, has been examined in a quantitative manner in epidemiologic studies. Such analyses suggest that avoidance of exposure to domestic allergens is a critical element in integrated strategies for both the prevention and the management of asthma. The promise of primary intervention in high-risk infants, as shown in the Isle of White study, has been confirmed in a recent study in Japan, and at least 4 similar trials are in progress. Applying these principles to the management of symptoms in patients with chronic asthma has proved more difficult, and it is likely that many earlier studies were poorly designed to test the hypothesis that allergen avoidance was clinically useful. Recent studies with patients moved to high altitudes during seasonal reductions in mite exposure and randomized controlled interventions in houses have all shown improvements in clinical manifestations of asthma. These recent trials have also demonstrated something that was less certain-that massive reductions in domestic allergen exposure can be achieved and that people will adopt the significant changes to their domestic environment and lifestyles if the risks and benefits are known. In the future, it seems likely that better study designs, as well as improvements in methods to monitor exposure and clinical outcomes, will provide further support for the role of allergen avoidance in the prevention and management of asthma.

Allergens↗
PubMed1998

Preventive counseling of HIV-positive men and self-disclosure of serostatus to sex partners: new opportunities for prevention.

This study examined whether preventive counseling of HIV-positive men (N = 255) was associated with self-disclosure of serostatus to sex partners. Men who reported being counseled at posttest and at their current HIV clinic to disclose their serostatus to partners were more likely to have done so than men counseled only at posttest, only at the HIV clinic, or not counseled at either site. Disclosure increased with the number of times counseled at the HIV clinic. These patterns held for HIV-negative partners, but not for HIV-positive or HIV-unknown partners. Disclosure to HIV-negative partners was associated with safer sexual practices. The findings suggest that counseling interventions for HIV-positive men, when delivered by multiple sources, may provide an effective means of increasing disclosure to sexual partners.

Adult↗
PubMed1998

Is acculturation associated with sexual risk behaviours? An investigation of HIV-positive Latino men and women.

This cross-sectional study of 226 HIV-positive Latino men and women sampled and assessed at an outpatient HIV clinic in Los Angeles examined the associations among acculturation, use of a substance before sex, and unsafe sexual behaviour. As acculturation increased, men and women were increasingly likely to have engaged in unsafe sex in the most recent sexual encounter since testing seropositive. In men, the association was partially mediated by use of a substance (primarily alcohol) in the three hours before the sexual encounter; in women, the association was not mediated by drug use. The findings underscore the need for culturally sensitive, secondary prevention programmes for HIV-positive persons.

Acculturation↗
PubMed1998

Use of rectal cancer position as a prognostic indicator.

The hypothesis of this study was that the position of rectal cancer within the circumference of the rectum influences mortality. Tumor position was prospectively documented in 181 patients with rectal carcinoma by two examiners. The results were analyzed for correlation to survival using the Lifetest model and for multivariate correlation using the Cox regression model. An anterior tumor location was present in 43 patients and was found to have a significantly higher survival rate than other positions. Two-thirds of anterior tumors were of pathologically favorable Dukes' stages. Fifty-five patients had posterior tumors with decreased survival rates, two-thirds of which were of unfavorable stages. Circumferential position in 61 patients was most predictive of poorer outcome, with a relative risk of death being increased by 4.6 times (P = 0.014) and a 5-year survival rate of 68.8 per cent; 85 per cent of these tumors were of pathologically unfavorable stages. The 5-year survival rate for the whole group, which included 181 patients with all histopathological stages except those with distant metastases at presentation, was 78.5 per cent. This ranking of survival rates was found to be consistent in each category with the postoperatively determined Dukes' stage, which carried a prognostic significance of P = 0.0001. We conclude that tumor position is a significant indicator of prognosis available before surgery for rectal cancer.

Adenocarcinoma↗
PubMed1997

Functional decline in the elderly: evidence for direct and stress-buffering protective effects of social interactions and physical activity.

Advances in medical technology and improvements in health behavior have greatly increased the proportion of Americans who survive into old age. Consequently, identifying environmental and behavioral factors that enhance or protect the health and functional capacity of older adults is an important goal. This study investigated the extent to which social interactions and physical activity can protect older adults from the declines in functional ability that typically occur with age and the extent to which they buffer the negative effects of widowhood on physical functioning. Data were from the Longitudinal Study of Aging, a six-year follow-up of over 7,000 respondents in the 1984 National Health Interview Survey. Using individual growth curve models which examine the effects of predictor variables on change over time, this study investigated how physical activity, social interactions, and widowhood are related to the rate of change in functional health over a six-year period. Results suggested that physical activity and social interactions each exerted independent effects on functional decline. In addition, physical activity and social interactions buffered the effects of widowhood on functional decline, especially in men who died before the end of the study. Results suggest a need for health promotion programs to encourage both physical and social activities in the elderly.

Activities of Daily Living↗