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Biomedical subjects

J Noble

Publications and source records attributed to J Noble.

At least 55 records · Page 3Linked to original sources
PubMed1998

The introduction and use of Norplant implants in Indonesia.

In this study, patterns of Norplant use in Indonesia are reviewed to assess the implications of this experience for the introduction of new contraceptive methods. Data from the Norplant Use-Dynamics Study and the 1994 Indonesia Demographic and Health Survey are analyzed, and patterns of acceptance, continuation, and removal are described. Acceptance of Norplant has increased steadily since it was first introduced. The method is now used by more than 5 percent of all married women of reproductive age. Continuation rates among Norplant users are higher than among users of the IUD. One factor behind high continuation rates may be that a substantial proportion of acceptors were not told that removal before five years was possible. Results indicate that deficits occurred in the quality of service delivery and that a need exists for improved provider training, better supervision, and clearer and better-enforced guidelines regarding women's right to have Norplant removed on demand.

Adolescent↗
PubMed1997

Knowledge-based vision and simple visual machines.

The vast majority of work in machine vision emphasizes the representation of perceived objects and events: it is these internal representations that incorporate the 'knowledge' in knowledge-based vision or form the 'models' in model-based vision. In this paper, we discuss simple machine vision systems developed by artificial evolution rather than traditional engineering design techniques, and note that the task of identifying internal representations within such systems is made difficult by the lack of an operational definition of representation at the causal mechanistic level. Consequently, we question the nature and indeed the existence of representations posited to be used within natural vision systems (i.e. animals). We conclude that representations argued for on a priori grounds by external observers of a particular vision system may well be illusory, and are at best place-holders for yet-to-be-identified causal mechanistic interactions. That is, applying the knowledge-based vision approach in the understanding of evolved systems (machines or animals) may well lead to theories and models that are internally consistent, computationally plausible, and entirely wrong.

Animals↗
PubMed1997

Impact of adrenalectomy on 5-HT6 and 5-HT7 receptor gene expression in the rat hippocampus.

Both glucocorticoid excess and decreased serotonergic (5-HT) transmission may cause depression. The recently cloned 5-HT6 and 5-HT7 receptors have high affinity for antidepressants. Here, we show that pharmacological adrenalectomy increases 5-HT6 and 5-HT7 receptor mRNA expression in specific hippocampal subfields, effects partly reversed by corticosterone replacement. Increased 5-HT6 and 5-HT7 receptor expression may provide a basis, in part, for the therapeutic actions of adrenal steroid synthesis inhibitors in resistant depression.

Adrenalectomy↗
PubMed1997

Site-specific regulation of corticosteroid and serotonin receptor subtype gene expression in the rat hippocampus following 3,4-methylenedioxymethamphetamine: role of corticosterone and serotonin.

Abnormal interactions between serotonin (5-hydroxytryptamine) and glucocorticoids, notably in the hippocampus, may underpin neuroendocrine, affective and cognitive dysfunction in depression and ageing. Glucocorticoids act via intracellular glucocorticoid and mineralocorticoid receptors, whereas 5-hydroxytryptamine binds to a family of transmembrane sites; both cross- and auto-regulation have been proposed. To determine the roles of 5-hydroxytryptamine and corticosterone in the short-term control of hippocampal receptor gene expression, we used 3,4-methylenedioxymethamphetamine (20 mg/kg), which causes acute release of both 5-hydroxytryptamine and corticosterone. 3,4-methylenedioxymethamphetamine increased mineralocorticoid receptor messenger RNA expression throughout the hippocampus after 16 h. In rats with fixed glucocorticoid levels (adrenalectomy plus corticosterone pellets) this effect was lost in CA1-4, suggesting corticosterone-mediation, but maintained in the dentate gyrus, indicating 5-hydroxytryptamine involvement. In contrast, 3,4-methylenedioxymethamphetamine decreased glucocorticoid receptor messenger RNA expression in the dentate gyrus and CA1 within 4 h, but only in adrenal-intact rats, suggesting corticosterone control. 5-Hydroxytryptamine1A receptor messenger RNA expression was decreased in CA1 in both groups of rats, but increased in the dentate gyrus only in corticosterone-fixed rats, suggesting 5-hydroxytryptamine differentially regulates expression of this gene within hippocampal subfields. 5-hydroxytryptamine2C receptor messenger RNA was decreased in ventral CA1 only in adrenal-intact rats, suggesting a corticosterone effect, and decreased in the subiculum in both groups, indicating 5-hydroxytryptamine mediation. These results show the complexity and intricate subregional-specificity of 5-hydroxytryptamine and corticosterone interactions upon hippocampal corticosteroid and 5-hydroxytryptamine receptor gene expression. 3,4-Methylenedioxymethamphetamine-induced alterations in hippocampal receptor gene expression may play a role in the mood and behavioural changes associated with this drug of abuse.

Animals↗
PubMed1997

Erosive amyloidosis of the wrist and knee associated with oligoclonal bands.

We report on a patient who presented with an inflammatory arthropathy clinically, though without a raised erythrocyte sedimentation rate, and in whom investigation subsequently showed erosive amyloidosis with an oligoclonal band. There was no evidence of rheumatoid disease and she has not developed any haematological malignancy. The only other case reported in the literature had an elevated erythrocyte sedimentation rate and went on to develop a lymphoplasmacytoid lymphoma.

Amyloidosis↗
PubMed1997

Sexual negotiation in the AIDS era: negotiated safety revisited.

OBJECTIVE: To test the safety of the 'negotiated safety' strategy-the strategy of dispensing with condoms within HIV-seronegative concordant regular sexual relationships under certain conditions. METHOD: Data from recently recruited cohort of homosexually active men (Sydney Men and Sexual Health cohort, n = 1037) are used to revisit negotiated safety. The men were surveyed using a structured questionnaire and questions addressing their sexual relationships and practice their own and their regular partner's serostatus, agreements entered into by the men concerning sexual practice within and outside their regular relationship, and contextual and demographic variables. RESULTS: The findings indicate that a significant number of men used negotiated safety as an HIV prevention strategy. In the 6 months prior to interview, of the 181 men in seroconcordant HIV-negative regular relationships, 62% had engaged in unprotected anal intercourse within their relationship, and 91% (165 men) had not engaged in unprotected anal intercourse outside their relationship. Of these 165 men, 82% had negotiated agreements about sex outside their relationship. The safety of negotiation was dependent not only on seroconcordance but also on the presence of an agreement; 82% of the men who had not engaged in unprotected anal intercourse outside their regular relationship had entered into an agreement with their partner, whereas only 56% of those who had engaged in unprotected anal intercourse had an agreement. The safety of negotiation was also related to the nature of the safety agreement reached between the men and on the acceptability of condoms. Agreements between HIV-negative seroconcordant regular partners prohibiting anal intercourse with casual partners or any form of sex with a casual partner were typically complied with, and men who had such negotiated agreements were at low risk of HIV infection. CONCLUSIONS: The adoption of the strategy of negotiated safety among men in HIV-seronegative regular relationships may help such men sustain the safety of their sexual practice.

Adolescent↗
PubMed1997

Characterization of recombination in the HLA class II region.

Studies of linkage disequilibrium across the HLA class II region have been useful in predicting where recombination is most likely to occur. The strong associations between genes within the 85-kb region from DQB1 to DRB1 are consistent with low frequency of recombination in this segment of DNA. Conversely, a lack of association between alleles of TAP1 and TAP2 (approximately 15 kb) has been observed, suggesting that recombination occurs here with relatively high frequency. Much of the HLA class II region has now been sequenced, providing the tools to undertake detailed analysis of recombination. Twenty-seven families containing one or two recombinant chromosomes within the 500-kb interval between the DPB1 and DRB1 genes were used to determine patterns of recombination across this region. SSCP analysis and microsatellite typing yielded identification of 127 novel polymorphic markers distributed throughout the class II region, allowing refinement of the site of crossover in 30 class II recombinant chromosomes. The three regions where recombination was observed most frequently are as follows: the 45-kb interval between HLA-DNA and RING3 (11 cases), the 50-kb interval between DQB3 and DQB1 (6 cases), and an 8.8-kb segment of the TAP2 gene (3 cases). Six of the 10 remaining recombinants await further characterization, pending identification of additional informative markers, while four recombinants were localized to other intervals (outliers). Analysis of association between markers flanking HLA-DNA to RING3 (45 kb), as well as TAP1 to TAP2 (15 kb), by use of independent CEPH haplotypes indicated little or no linkage disequilibrium, supporting the familial recombination data. A notable sequence motif located within a region associated with increased rates of recombination consisted of a (TGGA)12 tandem repeat within the TAP2 gene.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Gay youth and their precautionary sexual behaviors: the Sydney men and sexual health study.

Many commentators have positioned Western gay youth as a high-risk group for HIV infection and obscured important cultural, social, and contextual differences between populations. This study compares risk of HIV transmission factors among 216 young (under 25 years) and 822 older (25 years or over) homosexually active men, recruited through Sydney gay community and other sources. Bivariate and multivariate analyses of survey data that were collected by personal interviews consistently supported our hypothesis of no difference in HIV-related risk factors between young and older men. Although young men in this cohort were more likely to be of unknown serostatus, they were at least as knowledgeable, as attached to gay community, and as precautionary in their sexual behaviors with regular and casual male partners as their older counterparts. Safety campaigns targeting these young gay men should focus, for example, on their lower rates of HIV antibody testing and not be based on a false premise of hedonistic, uninformed, and disenfranchised youth.

AIDS Serodiagnosis↗
PubMed1996

Managing multiple risk factors: a call to action.

With the exception of obesity, risk factors for cardiovascular disease rarely occur as single conditions. Because these multiple factors often act synergistically, causing a geometric increase in overall cardiovascular risk, it is essential that their recognition and management be a goal of comprehensive preventive care. Physicians must make every effort to implement strategies to maximize risk reduction, including modification of an individual's lifestyle, appropriate pharmacologic treatment when indicated, involvement of the family, the community, and the media, patient education, and ready access to support and health services.

Cardiovascular Diseases↗
PubMed1996

Decreased NGFI-A gene expression in the hippocampus of cognitively impaired aged rats.

Hippocampal NGFI-A gene expression is increased following the induction of long-term potentiation, a form of activity-dependent synaptic plasticity that has been implicated in learning. In this study, we show a positive correlation between spatial learning and the constitutive expression of NGFI-A mRNA, selectively in CA1 pyramidal neurons. NGFI-A mRNA expression decreased with age in CA1, CA2 and neocortex. Long-term amitriptyline treatment, which improved spatial learning in young rats, had no significant effects on NGFI-A mRNA levels. Whether hippocampal NGFI-A plays a direct role in the mechanism of learning and memory remains to be determined.

Aging↗
PubMed1996

The fertility transition in Cuba and the Federal Republic of Korea: the impact of organised family planning.

South Korea and Cuba are dissimilar in religion, economy, culture and attitudes toward premarital sexual relations. In 1960, Korea instituted a national family planning programme to combat rapid population growth. Cuba explicitly rejected Malthusian policies, but made family planning universally available in 1974 in response to health needs. Both countries have undergone rapid fertility declines and today have less than replacement level fertility. Both countries have also used a similar mixture of methods, including a high prevalence of female sterilisation. Abortion has played a major role in the fertility decline of both countries, rising in the first half of the fertility transition and then falling, although remaining a significant variable in the second half. It is concluded that access to contraception, voluntary sterilisation, and safe abortion has a direct impact on fertility and has been associated with a rapid fall in family size in two very different countries.

Birth Rate↗