Biomedical subjects

R de Visser

Publications and source records attributed to R de Visser.

13 recordsLinked to original sources

PubMed2006

Smoking and erectile dysfunction: findings from a representative sample of Australian men.

OBJECTIVES: To examine whether there is an association between smoking and erectile dysfunction in a representative sample of Australian men. DESIGN: Secondary analysis of cross-sectional survey data from the Australian Study of Health and Relationships. PARTICIPANTS: 8367 Australian men aged 16-59 years. MAIN OUTCOME MEASURES: Erectile dysfunction was identified in men who reported having had trouble keeping an erection when they wanted to, a problem which persisted for at least one month over the previous year. Variables examined in multivariate logistic regression analyses included age, education, presence of cardiovascular disease and diabetes, and current alcohol and tobacco consumption. RESULTS: Almost one in 10 of the respondents (9.1%) reported erectile dysfunction that lasted for at least one month over the previous year. More than a quarter (27.2%) of respondents were current smokers, with 20.9% smoking < or = 20 cigarettes per day, and 6.3% smoking > 20 cigarettes per day. Compared with non-smokers, the adjusted odds ratios for erectile dysfunction were 1.24 (95% confidence interval (CI) 1.01 to 1.52, p = 0.04) for those smoking < or = 20 cigarettes per day and 1.39 (95% CI 1.05 to 1.83, p = 0.02) for those smoking > 20 cigarettes per day, after adjusting for other confounding factors. Older age, low level of education, and taking medications for cardiovascular disease were also independently and positively associated with erectile dysfunction. In contrast, moderate alcohol consumption (1-4 drinks per day) significantly reduced the likelihood of having erectile dysfunction. CONCLUSIONS: Erectile dysfunction is a significant health concern affecting around one in 10 Australian men aged 16-59 years. Current smoking is significantly associated with erectile dysfunction in Australian males. This association was strengthened as the number of cigarettes smoked increased. Health promotion programmes could use the link between smoking and erectile dysfunction to help reduce smoking levels among men.

Adolescent↗

PubMed2002

Use of alternative therapies by people living with HIV/AIDS in Australia.

Few studies of use of complementary and alternative medicine (CAM) among people living with HIV/AIDS (PLWHA) have been conducted since combination antiretroviral (ARV) drug therapy became widespread. In the context of changing ARV treatment options, it is important to consider the prevalence and correlates of use of CAM. In this study, a sample of 924 Australian PLWHA completed a self-administered survey that included questions on use of CAM. Half (55%) of the respondents reported using CAM. Most PLWHA did not choose CAM as an alternative to ARV drugs, but use CAM to complement ARV drugs. Use of CAM was not related to measures of progression of HIV/AIDS disease. In contrast, CAM use was related to characteristics of the ways respondents live with HIV/AIDS, and their attitudes toward treatment. The popularity of CAM among PLWHA highlights a need to ensure that PLWHA can make informed choices about CAM use.

Acquired Immunodeficiency Syndrome↗

PubMed2001

More cautious, more optimistic: Australian people living with HIV/AIDS, 1997-1999.

The aim of this study was to assess whether the lives of Australian people living with HIV/AIDS (PLWHA) have improved to the extent hoped for following the introduction of new antiretroviral (ARV) drugs for HIV. In 1997, 925 Australian PLWHA completed the first national survey of the social impacts of HIV/AIDS. In 1999, 924 Australian PLWHA were recruited for a repeat of the survey. Study participants completed an anonymous self-administered questionnaire. The data revealed that although new ARV drugs have improved the clinical profiles of many PLWHA, there have not been corresponding improvements in the physical well-being, levels of employment, or financial circumstances of many PLWHA. Nevertheless, PLWHA express favourable attitudes toward ARV drugs. Australian PLWHA have a complex relationship with their ARV medication that is likely to change over time as their HIV disease progresses and new treatments become available.

Adult↗

PubMed2001

Relationship between sexual partners influences rates and correlates of condom use.

A common finding in studies of heterosexual young adults is that condom use is more likely with casual partners than with regular partners. However, few studies have examined whether correlates of condom use differ with different partners. In this study, 103 heterosexual men and women completed a condom use diary for a period of up to 6 months. Condom use during sexual encounters with regular partners was mainly determined by established patterns of behavior. In contrast, condom use with casual partners was determined by the interaction between the sexual partners during the encounter, and was not influenced by the attitudes and beliefs of the individual. These differences have implications for interventions. They suggest that condom use with casual partners may be increased by furnishing young adults with skills and confidence for negotiating condom use. For young adults in regular relationships, we must ensure that routine patterns of condom use are appropriate for the levels of risk to which the partners are exposed.

Adolescent↗

PubMed2000

Alternative or complementary? Nonallopathic therapies for HIV/AIDS.

CONTEXT: Many people with HIV/AIDS use alternative therapies. Do they choose alternative therapies instead of allopathic therapies? OBJECTIVE: To examine patterns of use of allopathic therapies and alternative therapies among people living with HIV/AIDS. DESIGN: Cross-sectional survey of convenience sample. SETTING: Nonclinical setting in Australia. PARTICIPANTS: 925 men and women living with HIV/AIDS in Australia. MAIN OUTCOME MEASURES: Correlates of choice of therapy included demographic variables, sources of information about treatment, and attitudes toward treatments and health management. RESULTS: 56% of people living with HIV/AIDS in Australia use alternative therapies. Attitudes toward both allopathic and alternative therapies were positive. The choice of allopathic and/or alternative therapies was related to disease progression. Choice of therapy was also related to attitudes toward allopathic and alternative therapies. Many users of alternative therapies believe that such therapies can alleviate the side effects of antiretroviral drugs. CONCLUSIONS: The results of this study suggest that rather than being used as an alternative to allopathic medicine, nonallopathic therapies are used by people living with HIV/AIDS as complementary therapies.

Adult↗

PubMed1999

Personal and social factors influencing age at first sexual intercourse.

Early initiation of sexual activity is a concern, in part because of increased risk of sexually transmitted diseases, including HIV, and unwanted pregnancies among young people. In this study, 241 high schoolers were administered a questionnaire to establish the relationships between age at first sexual intercourse and personal qualities (sexual style, attractiveness, physical maturity, restraint, autonomy expectations, and attitudes to gender roles), smoking and drug use, and aspects of the social context (social activities, media impact, peer norms). There were few effects of sex of respondent and none in which respondents' sex impacted on age of initiation. Overall (and among the male sample), perceptions of greater physical maturity, greater use of uncommon (mostly illicit) drugs, and expectations of earlier autonomy significantly differentiated between early and later initiators. This group of factors tends to confirm the view that early experience of sexual intercourse is correlated with problem behaviors and a press toward "adult" behaviors. For girls, this pattern was even clearer, with use of uncommon drugs being replaced as a significant contributor to early sexual experience by relative lack of restraint. We conclude that the desire to achieve the transition to adulthood at an earlier age than their peers constitutes a powerful incentive for young people to become sexually active.

Adolescent↗

PubMed1999

Poverty, disease progression and employment among people living with HIV/AIDS in Australia.

A national survey of 925 people living with HIV/AIDS (PLWHA) in Australia is used to examine the relationship between disease progression, employment status, poverty and economic hardship. While disease progression has some impact on economic hardship, employment status is found to be the strongest determinant of both poverty and economic hardship. The most commonly cited reasons for leaving work were psychosocial (71%), with declining health cited by half of respondents. It is therefore argued that psychosocial issues are at least as important as changes in health in causing unemployment and therefore poverty and economic hardship among PLWHA in Australia.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Australian and South African undergraduates' HIV-related knowledge, attitudes, and behaviors.

To understand safe sex behavior in two countries which have been differentially affected by the HIV/AIDS epidemic, the present study compared the AIDS-related knowledge, attitudes, and behaviors of 920 heterosexual undergraduate students in Australia and 228 heterosexual undergraduate students in South Africa. South African students were found to have significantly less knowledge about HIV/AIDS, and significantly less favorable attitudes toward safe sex behavior than their Australian counterparts. They were also more likely to report that they have avoided various groups of people for fear of contracting AIDS. Experience from Australia over the period 1986-1995 suggests that significant improvements in the AIDS-related knowledge, attitudes, and behaviors of South African undergraduates are achievable.

Acquired Immunodeficiency Syndrome↗

PubMed1991

[Tongue prosthesis].

Surgical treatment for tumors of the tongue and floor of the oral cavity often results in impaired swallowing and speech function. A method is described to improve oral functions after total glossectomy by constructing a removable tongue prosthesis in a multidisciplinary clinical practice.

Glossectomy↗

PubMed1990

Control of Seed Respiration and Growth in Vicia faba by Oxygen and Temperature: No Evidence for an Oxygen Diffusion Barrier.

The rate of dry matter accumulation by seeds of Vicia faba L. cv. Minica increases with temperature in the range of 16 to 26 degrees C. The duration of dry matter accumulation decreases with temperature, resulting in a decrease of final seed dry weight. In this study we test the hypothesis that a diffusion barrier for O(2), located in the seed coat, inhibits seed respiration and growth. The rate of O(2) uptake of intact seeds and of excised embryos and seed coats (separated seeds) was measured in air and buffer at 16, 20, and/or 26 degrees C at various O(2) concentrations and developmental stages. Oxygen uptake rates of intact seeds in buffer were only 9 to 15% of those in air. In buffer, the respiration rate of intact seeds decreased at a pO(2) below air saturation (21 kilopascals), whereas separated seeds showed a decline of O(2) uptake only below 80% of air saturation. In air, embryo excision had no effect on the sensitivity of seed respiration to pO(2), at both 20 and 26 degrees C. In air at 20 degrees C, separated and intact seeds showed similar rates of O(2) uptake. Oxygen uptake by intact seeds, both halfway and beyond the linear growth phase, showed a temperature coefficient Q(10) of 2.3 and was insensitive to pO(2) in the range of 80 to 100% of ambient. These results indicate that V. faba seed respiration in air is not limited by the diffusion of O(2) into the seed.

Journal Article↗

PubMed1988

Ethylene Production by Attached Leaves or Intact Shoots of Tobacco Cultivars Differing in Their Speed of Yellowing during Curing.

Using an open air flow system, differences in the yellowing rate of leaves during curing were assessed in relation to ethylene production by shoots of intact seedlings or attached mature leaves of 60 day old tobacco (Nicotiana tabacum L.) plants. The rate of ethylene evolution from the leaves of the fast yellowing cultivars was significantly higher than in the slow yellowing ones. The same differences were obtained with shoots of intact seedlings. The findings suggest that it is possible to use ethylene production by seedlings as a selection criterion in screening for genotypic differences in the rate of yellowing. The ability of carbon dioxide (1%) to enhance ethylene production by attached leaves was significant in a slow, but not in a fast yellowing cultivar. However, similar amounts of ethylene were produced on administration of 1-aminocyclopropane-1-carboxylic acid to a slow and a fast yellowing cultivar. Exposure of attached leaves to exogenous ethylene (0.1 microliter per liter) accelerated the loss of chlorophyll and protein. This treatment was effective only for slightly yellow leaves and not for fully expanded green ones. The significance and possible use of ethylene in the flue-curing process are discussed.

Journal Article↗

PubMed1986

Alternative Path Mediated ATP Synthesis in Roots of Pisum sativum upon Nitrogen Supply.

Changes in the efficiency of root respiration were examined on intact plants of Pisum sativum L. cv Rondo after addition of nitrate or ammonium to the culture solutions. Nitrate was absorbed immediately after addition and elicited a respiratory rise (O(2)-uptake as well as CO(2)-production) to 160% at most. This occurred both in roots of plants fixing N(2) and in those of non-nodulated plants pregrown for 1 or 2 weeks on a nitrogen-free culture solution. In older plants, used after 2 weeks of N-free growth, the full capacity of the cytochrome path was engaged in root respiration. This was demonstrated by the absence of an effect of the uncoupler carbonylcyanide m-chlorophenylhydrazone in the presence of 25 millimolar salicylhydroxamate, an inhibitor of the alternative path. In these plants more than 90% of the nitrate-induced stimulation of root respiration was salicylhydroxamate-sensitive. In young plants, used after 1 week of N-free growth, the cytochrome path was not saturated. Its activity increased instantaneously at the expense of alternative path activity, which initially dropped to zero and subsequently increased to 160% of the control 7 hours after nitrate supply. The rate of photosynthesis rose to 120% of the control, but not before 1 hour after nitrate supply, suggesting that the stimulation of root respiration was not due to a higher rate of photosynthesis. Experiments with plants grown with a split-root system showed that respiration rate and alternative path activity only increased in the root halves exposed to nitrogen. Ammonium was equally effective as nitrate in stimulating root respiration. These results lead to the conclusion that alternative-path mediated root respiration contributes to synthesis of ATP during at least the first 24 hours following nitrogen supply.

Journal Article↗

PubMed1984

Inhibition and stimulation of root respiration in pisum and plantago by hydroxamate : its consequences for the assessment of alternative path activity.

The contribution of the alternative pathway in root respiration of Pisum sativum L. cv Rondo, Plantago lanceolata L., and Plantago major L. ssp major was determined by titration with salicylhydroxamate (SHAM) in the absence and presence of cyanide. SHAM completely inhibited the cyanide-resistant component of root respiration at 5 to 10 millimolar with an apparent K(i) of 600 micromolar. In contrast, SHAM enhanced pea root respiration by 30% at most, at concentrations below 15 millimolar. An unknown oxidase appeared to be responsible for this stimulation. Its maximum activity in the presence of low SHAM concentrations (1-5 millimolar) was 40% of control respiration rate in pea roots, since 25 millimolar SHAM resulted in 10% inhibition. In plantain roots, the maximum activity was found to be 15%. This hydroxamate-activated oxidase was distinct from the cytochrome path by its resistance to antimycin. The results of titrations with cyanide and antimycin indicated that high SHAM concentrations (up to 25 millimolar) block the hydroxamate-activated oxidase, but do not affect the cytochrome path and, therefore, are a reliable tool for estimating the activity of the alternative path in vivo. A considerable fraction of root respiration was mediated by the alternative path in plantain (45%) and pea (15%), in the latter because of the saturation of the cytochrome path.

Journal Article↗