Molecular basis of antagonism between K70E and K65R tenofovir-associated mutations in HIV-1 reverse transcriptase

The K70E mutation in HIV-1 reverse transcriptase was observed in 10% of virologic non-responders of the abacavir/lamivudine/tenofovir arm of ESS30009, alone, or in mixtures with K65R by population sequencing. Clonal analysis of six ESS30009 K70E isolates failed to identify double mutants carrying K65R+K70E. Site-directed K70E mutants had a replication capacity of 97+/-29%, but only 2.4+/-0.9% for K65R+K70E and 0.01% for K65R+K70E+M184V mutants. K65R+K70E phenotypic fold changes for abacavir, lamivudine and tenofovir were comparable to reported values for K65R alone. In molecular dynamic simulations, the epsilon-amino group of K65 was positioned 2.7+/-0.1A from the gamma-phosphate of the dTTP ligand and stabilized the triphosphate. In the R65 mutant, this distance increased to 4.2+/-0.4A and the interaction energy with the ligand was less favorable, but the K70 epsilon-amino group was repositioned closer to the gamma-phosphate and had a more favorable interaction energy. In the double mutant, E70 could not stabilize the gamma-phosphate, resulting in a more severe defect. The net effect of the atomic-level changes in the double mutant may be to destabilize the pyrophosphate leaving group of the ligand, more severely affecting the catalytic rate of the polymerization reaction than the R65 single mutation.

Bilirubin as an antioxidant in micelles and lipid bilayers: its contribution to the total antioxidant capacity of human blood plasma

The antioxidant capacities, antioxidant activities, k(inh), and stoichiometric factors, n, of water-soluble derivatives of bilirubin (BR), BR-human serum albumin (BR-HSA), and BR-ditaurate disodium conjugate (BRC) were determined in aqueous/lipid dispersions of sodium dodecyl sulfate (SDS) micelles/methyl linoleate and in bilayers of dilinoleoylphosphatidylcholine (DLPC) during initiation by water-soluble azo-bis-amidinopropane dihydrochloride (ABAP). The inhibition rate constants for BRC and BR-HSA were similar in micelles (k(inh) approximately 1.3 x 10(4) M(-1) s(-1)), where n approximately 2, whereas the k(inh) for BR-HSA dropped by (1/2) in bilayers. The dimethyl ester of bilirubin (BRDE) gave a k(inh) only one-tenth that of the vitamin E analog, pentamethylhydroxychroman (PMHC) in SDS micelles/methyl linoleate when initiated by lipid-soluble azo-bis-2,4-dimethylvaleronitrile (DMVN). Biliverdin hydrochloride (BVHCl) was NOT an effective peroxyl radical-trapping agent in the micellar phase during initiation by ABAP or DMVN containing methyl linoleate but it inhibited oxygen uptake in the aqueous phase. Both BRC and BR-HSA extended the total radical antioxidant parameter (TRAP) of human blood plasma and their contribution to TRAP was in the range of 5-10% of the natural TRAP of blood plasma, depending on the BR content determined in the blood plasma.

Promoting early detection in leprosy--a literature review to identify proven and potential interventions addressing patient-related delay

OBJECTIVES

The objective of the literature review was to identify proven and potential interventions to promote early diagnosis and start of treatment in leprosy, specifically, forms of intervention addressing needs at the local or primary level.

DESIGN

Using a structured search procedure, we identified recent leprosy-related publications describing proven interventions. To identify potential interventions the search was extended to publications assessing knowledge and attitudes towards leprosy and extended again to identify publications relating to patient-related delay in the context of other infectious diseases.

RESULTS

The review identified just 19 publications reporting leprosy-related interventions that included a form of evaluation of which only 10 directly addressed patient-related delay. These included health education interventions focussed on people directly affected by leprosy, their family members and other key individuals or groups within the local community. We identified no reports of interventions focussed specifically on the needs of women.

CONCLUSIONS

Our conclusion is that the evidence base available to inform the choice of small-scale interventions to promote early detection at the primary level is extremely limited. There is an urgent need to develop and extend the range of proven interventions, specifically those that address the needs of women, those that explore and develop the health promotion potential of people previously affected by,leprosy and those that exploit the potential of individuals with leadership roles within the community. This will require careful attention to planning, implementation, evaluation and reporting of interventions.

The relation between socioeconomic and demographic factors and tumour stage in women diagnosed with breast cancer in Denmark, 1983-1999

The authors investigated the association between socioeconomic position and stage of breast cancer at the time of diagnosis in a nationwide Danish study. All 28 765 women with a primary invasive breast cancer diagnosed between 1983 and 1999 were identified in a nationwide clinical database and information on socioeconomic variables was obtained from Statistics Denmark. The risk of being diagnosed with a high-risk breast cancer, that is size >20 mm, lymph-node positive, ductal histology/high histologic grade and hormone receptor negative, was analysed by multivariate logistic regression. The adjusted odds ratio (OR) for high-risk breast cancer was reduced with longer education with a 12% reduced risk (95% confidence interval (CI), 0.80,0.96) in women with higher education and increased with reduced disposable income (low income group: OR, 1.22; 95% CI, 1.10,1.34). There was an urban–rural gradient, with higher risk among rural women (OR 1.10; 95 % CI, 1.02, 1.18) and lower risk among women in the capital suburbs (OR, 0.85; 95% CI, 0.78, 0.93) and capital area (OR, 0.93; 95% CI, 0.84–1.02). These factors were significant only for postmenopausal women, although similar patterns were observed among the premenopausal women, suggesting a subgroup of aggressive premenopausal breast cancers less influenced by socioeconomic factors.

Access and equity to cancer care in the USA: a review and assessment

Cancer represents a serious threat to the health of women and men living in the USA. As the second leading cause of death, it claims about 500,000 lives annually. Health disparities occur when there are differences in the incidence, prevalence, mortality, and burden of disease among specific sub-populations within a specified region. For decades, disparities have been reported among Americans from racial/ethnic minority groups and those from low income groups. African Americans, the largest racial minority group in the USA, have the highest cancer incidence and mortality rates in the USA; it is about 10% higher in African Americans than in white people. Inequities in insurance status among Americans adversely affect their ability to obtain the entire range of cancer care. Those who are members of ethnic minorities and the working poor are especially apt to have poorer access to care and reduced quality of cancer care services as a result.

Predicting hypogonadism in men based upon age, presence of erectile dysfunction, and depression

Hypogonadism, a disorder associated with aging, can cause significant morbidity. As clinical manifestations of hypogonadism can be subtle, the challenge and the burden of diagnosis remain the responsibility of the clinician. Four different analytic methods were used to predict hypogonadism in men based upon age, the presence of erectile dysfunction (ED) and depression. 218 men were classified by age, serum testosterone level, the presence of ED and depression. Depression was determined by the Center for Epidemiologic Studies Depression Scale (CES-D). ED was assessed by the Sexual Health Inventory for Men (SHIM). Hypogonadism was defined as a serum testosterone level <300 ng/dl. An artificial neural network (ANN) was programmed and trained to predict hypogonadism based upon age, SHIM, and CES-D scores. Subject data was randomly partitioned into a training set of 148 (67.9%) and a test set of 70 (32.1%). The ANN processed the test set only after the training was complete. The discrete predicted binary output was set to (0) if testosterone level was <300 ng/dl or (1) if >300 ng/dl. The data was also analyzed by standard logistic regression (LR), linear and quadratic discriminant function analysis (LDFA and QDFA, respectively). Reverse regression (RR) analysis evaluated the statistical significance of each risk factor. The ANN can accurately predict hypogonadism in men based upon age, the presence of ED, and depression (receiver-operating characteristic=0.725). A four hidden node network was found to have the highest accuracy. RR revealed the depression index score to be most significant variable (P=0.0019), followed by SHIM score (P=0.00602), and then by age (P=0.015). Hypogonadism can be predicated by an ANN using the input factors of age, ED, and depression. This model can help clinicians assess the need for endocrinologic evaluation in men.

Survey of the provision of prophylactic dental care for horses in Great Britain and Ireland between 1999 and 2002

A survey of 854 horse owners, trainers and equestrian managers in 10 regions of Great Britain and Ireland showed that 83 per cent provided their horses with routine prophylactic dental care at fixed intervals, including 49 per cent at intervals of 12 months and 30 per cent at intervals of six months; a further 10 per cent provided it only when they felt it was required and 7 per cent did not provide it at all. Overall, 44 per cent of the owners had their horse's wolf teeth (first premolar) extracted routinely; when prophylactic dentistry was provided, it was carried out solely by equine dental technicians (EDTS) for 53 per cent of owners, solely by veterinarians for 35 per cent, by both EDTS or veterinarians for 10 per cent of owners and by other than veterinarians or EDTS for 1 per cent. There was confusion among some horse owners concerning the qualifications of the EDTS, because no recognised British qualification was available until towards the end of this survey in 2001. Several reasons were cited by owners for choosing between veterinarians and EDTS including their perceived qualifications, personal recommendations, costs, the availability of a wide range of dental equipment and sedation, and the time and effort devoted to the procedures.

Awareness and use of advance directives in the spinal cord injured population

STUDY DESIGN

Research was conducted through the use of semi-structured patient interviews. Subjects were recruited through the Saskatchewan branch of the Canadian Paraplegic Association (CPA) and through the clinical practice of the primary investigator. A total of twenty-one patients were interviewed. A qualitative outcome analysis was performed on information collected.

OBJECTIVES

Advance directives (or living wills) serve to communicate the wishes of individuals in the event that they should no longer be capable of making those wishes known. This can include directives on issues such as resuscitation status and withdrawal or withholding of care. The goal of this study was to determine the present level of knowledge and interest of spinal cord injured (SCI) patients on the topic of advance directives, and to determine what specific issues they felt need to be addressed in such a document in this population.

SETTING

The study was performed in Saskatoon, Saskatchewan, Canada. Although design and analysis were done in a tertiary care centre, the interviews themselves were conducted in the homes of the participants.

RESULTS AND CONCLUSION

The results show that spinal cord injured patients have some knowledge of what is involved in the preparation of an advance directive and that they feel these documents are important. A relatively small percentage have completed their own written directives but a large percentage planned to do so after completing this survey. There is some disagreement about when after the injury the topic should first be discussed. Information about medical conditions which are more likely to arise following a SCI should be included in an SCI-specific document. A template for an SCI-specific living will (the SCIAD) is provided.

Mind and cancer: does psychosocial intervention improve survival and psychological well-being?

The aim of this review was to evaluate the scientific evidence for an effect of psychosocial intervention on survival from cancer and well-being and in particular on anxiety and depression. A literature search yielded 43 randomised studies of psychosocial intervention. Four of the eight studies in which survival was assessed showed a significant effect, and the effect on anxiety and depression was also inconsistent, indicating three possible explanations: (i) only some of the intervention strategies affect prognosis and/or well-being and in only certain patient groups; (ii) the effect was weak, so that inconsistent results were found in the generally small study populations; or (iii) the effect was diluted by the inclusion of unselected patient groups rather than being restricted to patients in need of psychosocial support. Thus, large-scale studies with sound methods are needed in which eligible patients are screened for distress. Meanwhile, the question of whether psychosocial intervention among cancer patients has a beneficial effect remains unresolved.

Mind and cancer. do psychological factors cause cancer?

We have reviewed the evidence for an association between major life events, depression and personality factors and the risk for cancer. We identified and included only those prospective or retrospective studies in which the psychological variable was collected independently of the outcome. The evidence failed to support the hypothesis that major life events are a risk factor for cancer. The evidence was inconsistent for both depression and personality factors. Chance, bias or confounding may explain this result, as many of the studies had methodological weaknesses. The generally weak associations found, the inconsistency of the results, the unresolved underlying biological mechanism and equivocal findings of dose-response relationships prevent a conclusion that psychological factors are established risk factors. However, certain intriguing findings warrant further studies, which must, however, be well conducted and large and include detailed information on confounders.

HbA(1c) levels are genetically determined even in type 1 diabetes: evidence from healthy and diabetic twins

HbA(1c), a measure of blood glucose regulation, reflects glucose levels in the preceding months. In diabetes, HbA(1c) levels predict the risk of microvascular complications. The aim of this study was to determine whether genetic factors could influence HbA(1c) levels in normal subjects and type 1 diabetic patients. We performed a classical twin study of HbA(1c) in healthy nondiabetic female twins and 42 monozygotic (MZ) and 47 dizygotic (DZ) pairs. Interclass correlations (r) were higher in MZ (r = 0.77) compared with DZ (r = 0.53) twin pairs, suggesting a substantial genetic effect; this was confirmed by quantitative genetic model fitting. Additive genetic effects (heritability) explained 62% (95% CI 47-75) of population variance in HbA(1c); the remainder was attributable to the influence of unique environment (23% [15-36]) and age (14% [5-28]). Multivariate modeling showed that genetic factors also have a substantial influence on fasting glucose levels (51%). However, HbA(1c) heritability could not be explained by genes in common with fasting glucose. In the patients with type 1 diabetes, HbA(1c) levels were correlated in 33 MZ twins concordant for diabetes (r = 0.68; P < 0.001) but also in 45 MZ twins discordant for the disease (r = 0.52; P < 0.001). These significant correlations for HbA(1c) in both concordant and discordant pairs indicate a diabetes-independent familial effect. Thus, HbA(1c) levels are largely genetically determined and independent of the genes influencing fasting glucose. Even in type 1 diabetes, familial (i.e., diabetes-independent) factors influence protein glycation, implying that familial factors may explain, in part, the risk for microvascular complications, as indicated by high HbA(1c) levels.

Impact of HIV type 1 drug resistance mutations and phenotypic resistance profile on virologic response to salvage therapy

This study examines the association between presence of drug resistance mutations and phenotypic resistance at baseline to virologic response to salvage therapy in a community setting. The study population consisted of 58 antiretroviral drug-experienced patients with HIV-1 infection who had recently switched therapy because of virologic failure. Drug resistance mutations in the reverse transcriptase- and protease-coding regions and phenotypic susceptibility to 13 antiretroviral drugs were assessed at baseline. Plasma HIV-1 RNA levels were assessed at baseline and at subsequent clinic visits. Results showed that three variables were significant in predicting virologic response: HIV-1 levels at baseline, number of protease mutations, and phenotypic sensitivity score for the regimen at baseline. For four drugs there was a significant association between the presence of specific drug resistance mutations and >10-fold phenotypic resistance to that drug. With phenotypic resistance defined as >4-fold resistance, the association between specific drug resistance mutations and phenotypic resistance was significant for seven drugs. Overall, these data show that phenotypic susceptibility and absence of drug resistance mutations, particularly protease mutations, are significant predictors of virologic response. For several drugs, specific combinations of drug resistance mutations are associated with decreased phenotypic susceptibility and might provide useful clinical guidelines in selecting therapeutic options.

You don't know me, but I know you: the illusion of asymmetric insight

People, it is hypothesized, show an asymmetry in assessing their own interpersonal and intrapersonal knowledge relative to that of their peers. Six studies suggested that people perceive their knowledge of their peers to surpass their peers' knowledge of them. Several of the studies explored sources of this perceived asymmetry, especially the conviction that while observable behaviors (e.g., interpersonal revelations or idiosyncratic word completions) are more revealing of others than self, private thoughts and feelings are more revealing of self than others. Study 2 also found that college roommates believe they know themselves better than their peers know themselves. Study 6 showed that group members display a similar bias-they believe their groups know and understand relevant out-groups better than vice versa. The relevance of such illusions of asymmetric insight for interpersonal interaction and our understanding of "naive realism" is discussed.

Thymidine analog and multinucleoside resistance mutations are associated with decreased phenotypic susceptibility to stavudine in HIV type 1 isolated from zidovudine-naive patients experiencing viremia on stavudine-containing regimens

Studies have demonstrated that HIV-1 isolated from subjects experiencing virologic failure on stavudine (d4T)-containing regimens often contains thymidine analog mutations (TAMs), consisting of reverse transcriptase (RT) mutations M41L, D67N, K70R, L210W, T215Y/F, and K219Q/E, previously associated only with zidovudine (ZDV) resistance. In clinical study NZT40012, HIV-1 was isolated from 86 ZDV-naive subjects experiencing viremia on d4T-based therapies (plasma HIV-1 RNA > or =1000 copies/ml) and analyzed to examine the association between RT mutations and phenotypic resistance to d4T. Resistance-associated mutations were analyzed from HIV-1 isolated from 85 subjects. Of these, 24 samples (28%) had TAMs, and 30 samples (35%) had either TAMs and/or the Q151M multinucleoside resistance (MNR) mutation. Phenotypic susceptibility to d4T was determined by two commercially available methods. Statistically significant increases (p < 0.001) in phenotypic fold resistance to d4T were observed in virus with at least one TAM or MNR mutation. However, the mean increases in phenotypic resistance were 4-fold for the Antivirogram assay and 3-fold for the Phenosense HIV assay, only slightly above the levels used to designate decreased susceptibility to d4T. Subjects can experience viremia on d4T-containing regimens with virus exhibiting only small increases in IC(50), suggesting that relatively small changes in viral susceptibility to d4T may influence drug efficacy.

Substitution of a commercially available, RNA extraction procedure in an HIV-1 genotyping system improves sensitivity and allows reduced sample volume

The use is described of a commercially available, silica-based extraction procedure for HIV-1 RNA that can be substituted for the extraction procedure supplied with a commercially available, PCR-based genotyping kit for HIV-1. The advantages of using this alternative, commercially available extraction procedure include the following: (1) reduced safety concerns, due to inactivation of virus in the initial step of the extraction procedure; (2) enhanced sensitivity, allowing the use of plasma with HIV-1 RNA levels of less than 2000 copies/ml; (3) improved yield, allowing a 60% reduction in plasma volume; and (4) convenience and improved reproducibility, with a single extraction providing RNA suitable for PCR-based sequencing and for quantitation of HIV-1 RNA levels.