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Biomedical subjects

David A Ross

Publications and source records attributed to David A Ross.

At least 19 recordsLinked to original sources
PubMed2006

'The man who believed he had AIDS was cured': AIDS and sexually-transmitted infection treatment-seeking behaviour in rural Mwanza, Tanzania.

Most people living with AIDS in sub-Saharan Africa have had neither a biomedical diagnosis nor antiretroviral medication, leading to the question of how individuals understand and treat AIDS. This study examined general illness, sexually-transmitted infection (STI) and AIDS treatment-seeking behaviour in rural Mwanza, Tanzania. From 1999-2002, participant observation was carried out in nine villages for a total of 158 person-weeks. Treatments were pluralistic and opportunistic, usually beginning with home remedies (western or traditional), followed by visits to traditional healers (THs) and/or health facilities (HFs). THs were sometimes preferred over HFs because of familiarity, trust, accessibility, expense, payment plans, and the perceived cause, nature and severity of the illness, e.g. only THs were believed to successfully treat bewitchment. Some people, particularly young girls, delayed or avoided seeking treatment for STIs for fear of stigma. Most STIs were attributed to natural causes, but AIDS was sometimes attributed to witchcraft. Locally available biomedical care of people with AIDS-like symptoms consisted of basic treatment of opportunistic infections. Most such individuals repeatedly visited THs and HFs, but many stopped attending HFs because they came to believe they could not be cured there. Some THs claimed to cure witchcraft-induced, AIDS-like illnesses. There is an urgent need for improved biomedical services, and TH interventions could be important in future HIV/AIDS education and care.

Acquired Immunodeficiency Syndrome↗
PubMed2006

From trial intervention to scale-up: costs of an adolescent sexual health program in Mwanza, Tanzania.

OBJECTIVE: To estimate annual costs of a multifaceted adolescent sexual health intervention in Mwanza, Tanzania, by input (capital and recurrent), component (in-school, community activities, youth-friendly health services, condom distribution), and phase (development, startup, trial implementation, scale-up). STUDY DESIGN: Financial and economic providers' costs and intervention outputs were collected to estimate annual total and unit costs (1999-2001). The incremental financial budget projects funding requirements for scale-up within an integrated model. RESULTS: The 3-year economic costs of trial implementation were US dollars 879,032, of which approximately 70% were for the school-based component. Costs of initial development and startup were relatively substantial ( approximately 21% of total costs); however, annual costs per school child dropped from US dollars 16 in 1999 to US dollars 10 in 2001. The incremental scale-up cost is approximately 1/5 of ward trial implementation running costs. CONCLUSIONS: Annual costs can reduce by almost 40% as project implementation matures. When scaled up, only an additional US dollars 1.54 is needed per pupil per year to continue the intervention.

Adolescent↗
PubMed2006

Farming with your hoe in a sack: condom attitudes, access, and use in rural Tanzania.

This study examines condom knowledge, attitudes, access, and practices in rural Mwanza, Tanzania. From 1999-2002, six researchers carried out participant observation in nine villagesfor a total of 158 person-weeks. Many villagers perceived condoms negatively for multiple reasons, for example, the method's association with infection or promiscuity, reduced male sexual pleasure, and cultural understandings of meaningful sex. Men controlled the terms of sexual encounters and reported that they would use condoms only with risky partners, but few perceived their partners as such. Use of condoms appeared to be very low, primarily as a result of limited demand, although barriers to access also existed. These qualitative findings contrast with inconsistent survey reports of relatively high condom use in the same population. Intervention efforts should address the tradeoff between possible short- and long-term consequences of condom use, particularly for men, for example, reduced pleasure versus reduced HIV risk. If possible, surveys should assess the validity of reported condom use through comparison with other data, including qualitative findings and distribution/sales records.

Adolescent↗
PubMed2006

A NAD(P)H:quinone oxidoreductase 1 polymorphism is a risk factor for human colon cancer.

Colon cancer is one of the most common cancers in North America and generally develops from colonic epithelial cells following initiation by carcinogens. We have shown that the phase II detoxifying enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1) contributes to the inhibition of carcinogen-induced colon cancer in rats at both the initiation and postinitiation stages. An inactivating polymorphism at base 609 of the NQO1 gene, (609)C (NQO1 *1) --> (609)T (NQO1 *2), occurs at high frequency in the human population. Thus, we carried out a case-control study to determine if this polymorphism is associated with an increased risk of developing colon cancer. A total of 298 patients with colon cancer and 349 healthy controls matched for age, gender, and ethnic origin were enrolled in the study. There was an increased incidence of the NQO1 *2/*2 genotype in patients with colon cancer, with a gender and age-adjusted odds ratio of 2.68 (95% confidence intervals, 1.14-6.28). However, the incidence of the NQO1 *1/*2 genotype was not increased in patients with colon cancer compared with controls. When the patient and control groups were stratified by tobacco and alcohol use, the incidences of the NQO1 *2/*2 genotype were increased in patients with colon cancer for tobacco and alcohol users and nonusers, suggesting that there is no interaction between the NQO1 base 609 polymorphism and tobacco or alcohol use. These results strongly suggest that NQO1 plays a significant role in preventing the development of colon cancer, and individuals with an NQO1 *2/*2 genotype are at an increased risk of developing this disease.

Adult↗
PubMed2006

The weight of evidence: a method for assessing the strength of evidence on the effectiveness of HIV prevention interventions among young people.

OBJECTIVES: To design a method for assessing the strength of evidence on the effectiveness of different interventions to prevent the spread of HIV that will be the basis for the reviews in this series. METHODS: The literature on the evaluation of public health interventions was reviewed, and a method was developed in consultation with colleagues involved in this series of reviews and others. FINDINGS: The method involves the following steps. First, define the key types of intervention that policy-makers need to choose between in the population setting under consideration. Second, define the strength of evidence that would be needed to justify widespread implementation of the intervention. Third, develop explicit inclusion and exclusion criteria for the studies under review. Fourth, critically review all eligible studies and their findings, by intervention type. Fifth, summarize the strength of the evidence on the effectiveness of each type of intervention. Sixth, compare the strength of the evidence provided by the studies against the threshold of evidence that would be needed to recommend widespread implementation. Seventh, from this comparison, derive evidence-based recommendations related to the implementation of each type of intervention in the setting or population group. CONCLUSIONS: The method proposed here provides a systematic, rigorous and transparent approach to reviewing evidence on the effectiveness of interventions of different types and in different population settings in order to generate recommendations for policy-makers.

Adolescent↗
PubMed2006

Review of the evidence for interventions to increase young people's use of health services in developing countries.

OBJECTIVE: This chapter reviews the evidence base for interventions that aim to increase young people's use of health services in developing countries. METHODS: We identified published and unpublished studies and reports from developing countries that provided information about interventions designed to increase young people's use of health services. The studies were classified into six different types based on whether they included some or all of the following characteristics: training for service providers and clinic staff; making efforts to improve the quality of the facilities; implementing community activities to generate demand and support for the services; and involving other sectors, notably schools and the media. The levels of evidence required to make decisions about policies and programmes were defined for each of these types. FINDINGS: Despite the lack of detailed descriptions of interventions in the studies and difficulties interpreting the data reported in the evaluations, the studies provided evidence of increased use of health services by young people for those types of interventions that included training for service providers, making improvements to clinic facilities and implementing activities in the community, with or without the involvement of other sectors. CONCLUSION: The evidence for the effectiveness of interventions to increase young people's use of health services was sufficient to recommend that interventions that include training for service providers, making improvements to clinics and using activities in the community should be widely implemented with careful monitoring of quality and coverage and that those that additionally involve other sectors should also be widely but cautiously implemented, provided they include a strong evaluation component. Operations research is also required to better understand the content of the interventions and their mechanisms of action.

Adolescent↗
PubMed2005

Functional analysis of Hes-1 in preadipocytes.

Notch signaling blocks differentiation of 3T3-L1 preadipocytes, and this can be mimicked by constitutive expression of the Notch target gene Hes-1. Although considered initially to function only as a repressor, recent evidence indicates that Hes-1 can also activate transcription. We show here that the domains of Hes-1 needed to block adipogenesis coincide with those necessary for transcriptional repression. HRT1, another basic-helix-loop-helix protein and potential Hes-1 partner, was also induced by Notch in 3T3-L1 cells but did not block adipogenesis, suggesting that Hes-1 functions primarily as a homodimer or possibly as a heterodimer with an unknown partner. Purification of Hes-1 identified the Groucho/transducin-like enhancer of split family of corepressors as the only significant Hes-1 interacting proteins in vivo. An evaluation of global gene expression in preadipocytes identified approximately 200 Hes-1-responsive genes comprising roughly equal numbers of up-regulated and down-regulated genes. However, promoter analyses indicated that the down-regulated genes were significantly more likely to contain Hes-1 binding sites, indicating that Hes-1 is more likely to repress transcription of its direct targets. We conclude that Notch most likely blocks adipogenesis through the induction of Hes-1 homodimers, which repress transcription of key target genes.

Adipocytes↗
PubMed2005

Contradictory sexual norms and expectations for young people in rural Northern Tanzania.

There has been a long-running debate as to whether sexual cultures in sub-Saharan Africa are permissive or characterised by restrictive rules, rituals and self-restraint. This paper, based on participant observation data, outlines the main features of sexual culture in rural northern Tanzania and highlights both permissive and restrictive norms and expectations for young people. It also illustrates how sexual beliefs are socially constructed and subject to social change. Sexual activity is constrained by clear norms of school pupil abstinence, female sexual respectability and taboos around the discussion of sex. However, these norms are incompatible with several widely held expectations: that sexual activity is inevitable unless prevented, sex is a female resource to be exploited, restrictions on sexual activity are relaxed at festivals, and masculine esteem is boosted through sexual experience. Differential commitment to these norms and expectations reflects conflicts between generations and genders. Young people appear to manage the contradictions in these norms by concealing their sexual relationships. This almost certainly contributes to their short duration and the high levels of partner change, since relationships are not reinforced through social recognition and there is little scope to develop intimacy through non-sexual contacts.

Adolescent↗
PubMed2005

Absolute pitch: music and beyond.

"Perfect pitch," known in the scientific literature as "absolute pitch" (AP), is a rare phenomenon that has fascinated musicians and scientists alike for over a century. There has been a great deal of conflict in the literature between advocates of the two main theories on the etiology of AP: some believe that AP is learned early in life through intensive musical training, whereas others believe AP to be largely innate. Both theories are alike, however, in considering AP to be exclusively a musical phenomenon. We propose a paradigm shift by presenting here a new model of AP, one that is predicated on two principles: (1) that AP may be relatively independent of musical experience; and (2) that there are different types of AP, each of which can be ascribed to discrete neurobiological mechanisms. We also review data from a diverse series of experiments that were designed to test explicitly both the predictions of our model and a series of historical myths about AP. In each case, the data strongly support our model. We conclude with a general discussion on the nature of AP, the relevance of these findings for other areas of research, and future directions of study.

Acoustic Stimulation↗
PubMed2005

The MEMA kwa Vijana project: design of a community randomised trial of an innovative adolescent sexual health intervention in rural Tanzania.

BACKGROUND: Effective interventions to reduce the incidence of HIV, other sexually transmitted infections (STIs) and unwanted pregnancy among adolescents in sub-Saharan Africa are urgently needed. This paper describes the rationale and design of a randomised trial of the impact of an innovative sexual health intervention among adolescents in rural Mwanza Region, Tanzania. METHODS: The MEMA kwa Vijana intervention comprises a teacher-led, peer-assisted sexual health education programme for students in the last 3 years of primary school, training and supervision of health workers in the provision of youth-friendly health services, peer condom promotion and distribution, and wider community activities. Detailed process evaluation was conducted and the impact of the intervention was evaluated through a community-randomised trial in which a cohort of 9645 adolescents was followed up for 3 years. Both process and impact evaluation used multiple assessment methods. Impact measures included incidence and prevalence of HIV and other STIs, pregnancy rates, knowledge and reported attitudes and sexual behaviour, as well as qualitative assessments. RESULTS: Results of the baseline survey of the cohort have been presented previously. The outcome of the trial will be reported separately. CONCLUSIONS: Behaviour change interventions among adolescents have been widely advocated, but there have been few rigorously designed trials of their effectiveness, particularly in developing countries, and measurement of sexual behaviour is particularly problematic in this age group. The MEMA kwa Vijana trial was undertaken to address these problems and to collect rigorous evidence on the effectiveness of an innovative intervention, designed to be implemented on a very large scale.

Adolescent↗
PubMed2005

Role of NQO1 polymorphisms as risk factors for squamous cell carcinoma of the head and neck.

A case: control study was carried out to determine if inactivating polymorphisms of the NQO1 gene at bases 609 and 465 are associated with altered risk of developing squamous cell carcinoma of the head and neck (SCCHN). Genotyping was carried out by PCR RFLP analysis on whole blood samples. The frequency of the inactive 609T and active 609C forms, and the inactive 465T and active 465C forms, of NQO1 were compared in patient and control groups by a logistic regression analysis and odds ratios (ORs) were calculated. Participants were stratified by tobacco and alcohol use, and genotype distributions in these sub-groups were compared. There were no significant differences in genotype distribution between SCCHN patients and the control population for the base 609 or 465 polymorphisms. There were also no significant differences in genotype distributions between patient and control groups for tobacco and/or alcohol users and non-users. Genotype distributions were similar for SCCHN patients at all disease sites with the exception of the nasopharynx where there was a higher incidence of the 609C:609T and 609T:609T genotypes. These results suggest that individuals having either 609T or 465T alleles generally do not have an altered risk of developing SCCHN.

Adult↗
PubMed2005

A typology of groups at risk of HIV/STI in a gold mining town in north-western Tanzania.

Mining communities with migrant populations are high-risk locations for human immunodeficiency virus (HIV)/sexually transmitted infection transmission in Sub-Saharan Africa. Interventions presupposing certain groups to be at high risk, such as those working exclusively as commercial sex workers, may divert attention from other high-risk groups. Qualitative research was conducted in a small town adjacent to a large-scale commercial gold mine in north-western Tanzania. Objectives were to identify populations at high risk of HIV and suggest suitable behavioural interventions by gaining an understanding of sexual behaviour patterns in the town. Rapid assessment procedures were employed comprising participant observation, informal questioning and in-depth interviews. Epidemiological categories of "core", "bridging" and "general" populations may not be adequate to the understanding of risk. Many types of women were found to receive payment for sex, distinguished by permanency of residence, age, relationship status, accommodation and income-earning activity. Paying for sex and having multiple partners was common among most men. The town was a high-risk environment as a result of the economic opportunities available there (in contrast to the poverty of surrounding areas), which were often accessed by offering sex in exchange for money or gifts. In this environment, the potential for spread of HIV infection between sub-populations was high and identification of distinct high- and low-risk groups not possible. However, the methodology enabled the identification of different social circumstances of risk, such as residential arrangements, employment status and venues for recreation, associated with different types of people. Targeted interventions may be oriented to specific circumstances in order to address risk practices in a culturally appropriate manner. It is useful to think of risk environments rather than attributing risk to types of people, and to target interventions to these environments. The methodology also enabled an approach to interventions sensitive to different circumstances associated with risk within the town while identifying structural factors affecting risk at the level of the town as a whole.

Age Factors↗
PubMed2004

Consequences of Notch-mediated induction of Jagged1.

Notch signaling is initiated upon contact of cells expressing Notch receptors with those expressing ligands. While examining the dynamic response of NIH 3T3 cells to cells expressing the Notch ligand Jagged1, we found that Notch signaling resulted in increased levels of the ligand Jagged1. Induction of Jagged1 was delayed relative to the generation of active Notch and dependent on the transcription factor p63. The induced Jagged1 had no apparent autocrine effects on Notch signaling but could promote signaling in naïve cells. These results describe a mechanism through which Notch signaling can be relayed from cell to cell.

Animals↗
PubMed2004

Key elements for successful integrated health information systems: lessons from the States.

The Genetic Services Branch, Maternal and Child Health Bureau of the Health Services and Resources Administration has provided funding to state health departments to integrate their newborn dried blood-spot screening programs with other early child health information systems since 1999. In 2001, All Kids Count conducted site visits to these grantees to identify and describe best practices in planning, developing, and implementing their integration projects. The site visits were organized around 9 key elements considered critical to the success of an information systems integration project: leadership, project governance, project management, stakeholder involvement, organizational and technical strategy, technical support and coordination, financial support and management, policy support and evaluation. Best practices for each of the key elements and 5 lessons learned were documented in Integration of Newborn Screening and Genetic Service Systems with Other Maternal & Child Health Systems: A Sourcebook for Planning and Development. The lessons learned are overarching conclusions that agencies should consider when planning and implementing integrated information systems. This article briefly describes the key elements, their best practices as implemented by states, and the lessons learned.

Child↗
PubMed2004

The near-term future for child health information systems.

The developmental process in children offers an opportunity to influence their health and well-being as adults. The information infrastructure of the future needs to support the multiple partners responsible for providing elements of the health protection and health care of children. In this partnership, public health plays simultaneously a supportive role and a leadership role. Five tasks need to guide near-term information systems thinking with respect to establishing a basis for building electronic linkages among various child health programs. First, the nation's vital records system must be reengineered to ensure that this key information asset can be integrated into other child health information systems. Second, through an appropriate governance structure, the key stakeholders in child health should endorse standards and requirements that define a longitudinal health record for children. Third, public health agencies should develop a thorough business case/value proposition that drives mutually developed and mutually endorsed requirements for the integration of presently fragmented systems. Fourth, public health should take the lead in ensuring that parents have convenient access to information that can support the coordination of their child's care and development. And fifth, provider groups and public health agencies should join research networks to study how information supports positive changes to children's health.

Child↗
PubMed2004

Asking semi-literate adolescents about sexual behaviour: the validity of assisted self-completion questionnaire (ASCQ) data in rural Tanzania.

OBJECTIVES: To develop and test a sexual behaviour survey method for semi-literate populations, combining the privacy of a self-completion questionnaire (SCQ) with the clarity of a face-to-face questionnaire (FFQ). METHODS: In 1998, 6079 Tanzanian primary school students (mean age 15.1 years) were surveyed using an innovative assisted self-completion questionnaire (ASCQ). The format of the questionnaire was simple, all responses were closed, and conceptually complex questions such as those involving ranking or multiple answers were avoided. The ASCQ was administered to groups of 20 by a research assistant who read questions and answers aloud in two languages so pupils could tick or write responses independently. A total of 4958 of respondents from the 1998 ASCQ Cohort also participated in a 1998 FFQ interview and, in 2000, 4424 again completed an ASCQ. RESULTS: In the 1998 ASCQ survey, 55.0% of males and 21.1% of females reported they had had vaginal intercourse, of whom 71.5% and 66.0%, respectively reported their first sexual relationship lasted for a week or less, and 49.5% and 59.6%, respectively reported they had had sex in the last 4 weeks. After adjustment for age, reported sex was associated with alcohol use in both males (OR = 1.57) and females (OR = 1.69), earning money for males (OR = 1.32) and not living with a mother for females (OR = 0.77). The vast majority of respondents did not appear to have difficulty completing the ASCQ, but 7.4% of 1998 respondents and 2.9% of 2000 respondents selected all first or all last answers in a section for which this was inconsistent. This bias was associated with female, less educated and more geographically remote respondents. Of those respondents who reported sex in the 1998 ASCQ survey, 32.1% reported fewer total partners in the 2000 ASCQ survey, 25.2% reported having had sex fewer times than originally reported, and 61.9% of those who reported having used a condom in 1998 reported never having used one in 2000. While the proportions reporting sex were very similar in the 1998 ASCQ and FFQ surveys, 37.9% of males and 59.2% of females reporting sex only did so on one of the two questionnaires. Higher proportions of respondents reported sensitive information in the ASCQ than the FFQ, although in some cases this may have related to answer order bias. CONCLUSION: The results suggest that an ASCQ may be useful in assessing sexual behaviour in African adolescents, particularly for older, male and/or educated respondents. However, triangulation with data from other surveys raises questions about the validity of self-reported sexual behaviour in general.

Adolescent↗