Systematically missing confounders in individual participant data meta-analysis of observational cohort studies

One difficulty in performing meta-analyses of observational cohort studies is that the availability of confounders may vary between cohorts, so that some cohorts provide fully adjusted analyses while others only provide partially adjusted analyses. Commonly, analyses of the association between an exposure and disease either are restricted to cohorts with full confounder information, or use all cohorts but do not fully adjust for confounding. We propose using a bivariate random-effects meta-analysis model to use information from all available cohorts while still adjusting for all the potential confounders. Our method uses both the fully adjusted and the partially adjusted estimated effects in the cohorts with full confounder information, together with an estimate of their within-cohort correlation. The method is applied to estimate the association between fibrinogen level and coronary heart disease incidence using data from 154 012 participants in 31 cohorts.† Copyright © 2009 John Wiley & Sons, Ltd.

Cardiovascular Health in the Developing World: Community Perceptions from Carriacou, Grenada

BACKGROUND: As developing countries shift to increasing prevalence of cardiovascular risk factors and diseases (CVD), prevention efforts, both primary and secondary, become a public health priority. Designing effective methods requires a clear understanding of local beliefs and practices regarding health risks and behaviors. METHODS: A mixed gender and age team deployed a Rapid Assessment Protocol (participant observation; interviews) over three days. Interviews from 25 residents of Carriacou, Grenada included leaders and community members representing a range of demographic characteristics (gender, age, employment). RESULTS: Residents expressed general uncertainty about their actual health. While acknowledging that certain conditions (e.g. diabetes, hypertension) were prevalent, heredity was viewed as being more strongly associated with CVD. Not being able to work or carry out one's daily activities often drove health care seeking behavior (evaluation, care or initiating lifestyle changes). Health improvement activities when practiced were fragmented, not an overall lifestyle change. Physical activity was implicitly valued but not universally practiced; it declined with age and increasing work and other commitments. CONCLUSIONS: While public health programs benefit from understanding community attitudes and beliefs, research to inform program development is often not undertaken or if undertaken not effectively utilized to make needed program modifications. Key to our conclusions was their perspective on health as illness oriented and reactive, strongly associated with heredity rather than preventive and associated with behavior change. A preventive focus informed by local practices is fundamental to designing effective and sustainable primary and secondary prevention programs and particularly useful in developing countries.

Modulation of meningeal nociceptors mechanosensitivity by peripheral proteinase-activated receptor-2: the role of mast cells

Inflammatory-related activation and sensitization of meningeal nociceptors is believed to play a key role in promoting the intracranial throbbing pain of migraine. We have shown recently that mast cell activation and various mast cell-derived inflammatory mediators can promote activation and sensitization of meningeal nociceptors. Mast cell tryptase has also been proposed to promote pain hypersensitivity by activating the proteinase-activated receptor 2 (PAR2) that is expressed on nociceptive neurons. In this study using in vivo single-unit recording in the trigeminal ganglion of anaesthetized rats, we found that local meningeal activation of PAR2 using the specific agonist SLIGRL-NH2 promoted sensitization of the threshold response while provoking desensitization of the suprathreshold responses. SLIGRL-NH2 also excited a subpopulation of meningeal nociceptors. Chronic mast cell depletion enhanced the sensitizing effects of PAR2 activation while curbing its desensitizing effects. Mast cell depletion did not change the PAR2-mediated excitatory effect. We propose that by enhancing the mechanical sensitivity of meningeal nociceptors local PAR2 activation could play a role in promoting the throbbing pain of migraine and that local mast cell degranulation may modulate such an effect.

Comparison of quality-adjusted survival in patients with advanced renal cell carcinoma receiving first-line treatment with temsirolimus (TEMSR) or interferon-α (IFN) or the combination of IFN+TEMSR

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Background: In a phase 3, randomized, 3-arm study of TEMSR or IFN or the combination of TEMSR + IFN in the first-line treatment of patients with advanced renal cell carcinoma (RCC) and poor-prognostic features, TEMSR improved overall survival (p=0.0069) and progression-free survival (p=0.0001) vs. IFN (Hudes et al. J Clin Oncol. 2006;24:LBA4). Quality-adjusted survival was a pre-defined endpoint and is reported. Methods: Quality-adjusted time without symptoms and toxicity (QTWiST) was estimated by partitioning overall survival into 3 distinct health states: time with serious toxicity, time with progression, and time without symptoms and toxicity (TWiST). Survival was value-weighted when patients completed quality of life questionnaires (EQ-5D) at weeks 12 and 32, when a grade 3 or 4 adverse event (AE) was reported, upon relapse or progression, or upon withdrawal from the study. Treatment group comparisons used restricted means analyses estimated from censored survival data. Restricted means were computed for duration of each health state by truncating data at median follow-up (17.9 months). Variance and covariance were estimated using bootstrap methods. Results: All 626 randomized patients in the study were included in computation of health state durations. EQ-5D questionnaires were obtained from 260/300 (87%) upon progression and 230/570 (40%) after a grade 3/4 AE. Patients receiving TEMSR alone had 38% greater TWiST than those receiving IFN alone (TEMSR=6.5 months vs. IFN=4.7 months, p=0.00048). There was no significant difference in TWiST between the combination arm and IFN alone (IFN+TEMSR=5.4 months vs. IFN=4.7 months, p=0.1288). Patients receiving TEMSR alone had 23% greater Q-TWiST than those receiving IFN alone (TEMSR=7.0 months vs. IFN=5.7 months; p=0.0015). There was no significant difference in Q-TWiST for the combination arm compared with IFN alone (IFN+TEMSR=6.1 months vs. IFN=5.7 months, p=0.3469). Conclusions: Patients with advanced RCC receiving TEMSR alone had significantly greater quality-adjusted survival than those receiving IFN alone.

No significant financial relationships to disclose.

Subtypes of oligodendroglioma defined by 1p,19q deletions, differ in the proportion of apoptotic cells but not in replication-licensed non-proliferating cells

Oligodendrogliomas may be divided into those with deletion of chromosomes 1p and 19q (Del+), and those without (Del−). Del+ tumours show better survival and chemoresponsiveness but the reason for this difference is unknown. We have investigated whether these subgroups differ in (a) apoptotic index, (b) the proportion of cells licensed for DNA replication but not in-cycle, and (c) the relative length of G₁-phase. Fluorescence in situ hybridisation with probes to 1p and 19q was used to determine the deletion status of 54 oligodendrogliomas, including WHO grades II and III. The apoptotic index was determined using counts of apoptotic bodies. Replication-licensed non-proliferating cells were determined from the Mcm2 minus Ki67 labelling index, whilst the geminin to Ki67 ratio was used as a measure of the relative length of G₁. Del+ oligodendrogliomas showed a higher apoptotic index than Del− tumours (P = 0.037); this was not accounted for by differences in tumour grade or in proliferation. There were no differences in the Mcm2 − Ki67 index or in the geminin/Ki67 ratio between the subgroups, but grade III tumours showed a higher proportion of licensed non-proliferating cells than grade II tumours (P = 0.001). An increased susceptibility to apoptosis in oligodendrogliomas with 1p ± 19q deletion may be important in their improved clinical outcome compared to Del− tumours.

Development of a Scale for Evaluation of Tomato yellow leaf curl virus Resistance Level in Tomato Plants

ABSTRACT We have developed a scale of differential hosts that enables the determination and comparison of level of resistance to Tomato yellow leaf curl virus (TYLCV) expressed by resistant tomato lines or by individual plants in a segregating population. The scale is composed of seven different homozygous tomato genotypes that exhibit different levels of TYLCV resistance, ranging from fully susceptible to highly resistant. The differential hosts composing the scale were inoculated with TYLCV under greenhouse conditions. Four weeks after inoculation the plants were evaluated for disease symptom severity, and virus DNA titer was determined. The different genotypes were arranged in the scale according to symptom severity score. The different genotypes were then tested under different environmental conditions, inoculated at different ages, and tested in a field experiment assaying TYLCV-induced yield reduction. While the symptom severity score of each individual resistant genotype changed under different environmental conditions, the relative position on the scale did not alter, except for one genotype. Thus, to evaluate disease resistance of a given tomato genotype, the genotype in question should be inoculated alongside the differential hosts composing the scale, and within 4 weeks one can determine the relative level of resistance of the tested genotype.

The Yes-associated protein 1 stabilizes p73 by preventing Itch-mediated ubiquitination of p73

Upon DNA damage signaling, p73, a member of the p53 tumor suppressor family, accumulates to support transcription of downstream apoptotic genes. p73 interacts with Yes-associated protein 1 (Yap1) through its PPPY motif, and increases p73 transactivation of apoptotic genes. The ubiquitin E3 ligase Itch, like Yap1, interacts with p73. Given the fact that both Itch and Yap1 bind p73 via the PPPY motif, we hypothesized that Yap may also function to stabilize p73 by displacing Itch binding to p73. We show that the interaction of Yap1 and p73 was necessary for p73 stabilization. Yap1 competed with Itch for binding to p73, and prevented Itch-mediated ubiquitination of p73. Treatment of cells with cisplatin leads to an increase in p73 accumulation and induction of apoptosis, but both were dramatically reduced in the presence of Yap1 siRNA. Altogether, our findings attribute a central role to Yap1 in regulating p73 accumulation and function under DNA damage signaling.

Insulin resistance, oxidative stress, hypertension, and leukocyte telomere length in men from the Framingham Heart Study

Insulin resistance and oxidative stress are associated with accelerated telomere attrition in leukocytes. Both are also implicated in the biology of aging and in aging-related disorders, including hypertension. We explored the relations of leukocyte telomere length, expressed by terminal restriction fragment (TRF) length, with insulin resistance, oxidative stress and hypertension. We measured leukocyte TRF length in 327 Caucasian men with a mean age of 62.2 years (range 40-89 years) from the Offspring cohort of the Framingham Heart Study. TRF length was inversely correlated with age (r = -0.41, P < 0.0001) and age-adjusted TRF length was inversely correlated with the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) (r =-0.16, P = 0.007) and urinary 8-epi-PGF(2alpha) (r = -0.16, P = 0.005) - an index of systemic oxidative stress. Compared with their normotensive peers, hypertensive subjects exhibited shorter age-adjusted TRF length (hypertensives = 5.93 +/- 0.042 kb, normotensives = 6.07 +/- 0.040 kb, P = 0.025). Collectively, these observations suggest that hypertension, increased insulin resistance and oxidative stress are associated with shorter leukocyte telomere length and that shorter leukocyte telomere length in hypertensives is largely due to insulin resistance.

Predicting gene promoter methylation in lung tumors through examination of sputum and serum

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Background: Personalized medicine may be a key approach in improving survival for advanced lung cancer. Success for this approach is seen with the response of cancer patients with an activating mutation within the epidermal growth factor receptor to the growth fact inhibitor, gefitinib. Genes involved in all types of normal cell function are targeted for inactivation by promoter hypermethylation during lung cancer development. This makes gene-specific promoter hypermethylation an attractive target for novel treatment strategies. One obstacle to targeted therapy is accessibility of tissue from peripheral tumors for methylation analysis. The purpose of this study was to determine the predictive power of sputum and serum to detect NSCLC through analysis for methylation of genes in these fluids. Methods: Tissue, serum, and sputum were obtained from 72 stage III NSCLC patients participating in a Phase III trial of Carboplatin, Paclitaxel and Radiotherapy, With or Without Thalidomide (ECOG 3598). Methylation specific PCR assessed methylation of the p16, MGMT, DAPK, RASSF1A, PAX5-α, PAX5-β, H-cadherin, and GATA5 genes. Results: At least one gene was methylated in 89% of tumors. Prevalence for methylation ranged from 15–47% and did not differ between gender. Methylation of ≥ 3 genes was seen in ∼50% of tumors. The agreement between sputum or serum in classifying methylation status of any gene in the tumor ranged from 54– 69%. The reduced sensitivity was presumably due in part to absence of tumor DNA in the biological fluids of methylation positive tumors. Logistic regression models revealed 3.1 (CI, 1.2, 8.2) and 4.2 (1.1, 16.1) increased odds for methylation of the p16 and MGMT gene, respectively in tumors if the serum or sputum was positive for methylation. The effect of tumor histology for predicting methylation using sputum and serum is being examined. Conclusion: These studies demonstrate for genes such as p16 and MGMT the possibility of interrogating biological fluids to predict for methylation in the primary tumor. (Supported by CA-89551).

No significant financial relationships to disclose.

Cross-sectional relations of serum aldosterone and urine sodium excretion to urinary albumin excretion in a community-based sample

Experimental models suggest that increased aldosterone and sodium intake are associated with renovascular damage and resultant proteinuria. We hypothesized that serum aldosterone and urinary sodium would be associated with urinary albumin excretion, an indicator of kidney damage. We evaluated 2700 participants (53% women, mean age 58 years) from the Framingham Offspring Study who attended a routine examination between 1995 and 1998, who were free of heart failure and renal failure, and underwent testing for serum aldosterone, spot urinary sodium, and urinary albumin excretion (urine albumin/creatinine ratio, UACR), the latter two indexed to urinary creatinine. Stepwise multivariable linear regression was used to evaluate the relations between UACR with urinary sodium index and serum aldosterone. In multivariable regression, log urinary sodium index was associated positively with log-UACR (P<0.0001). UACR levels in the fourth and fifth quintiles of urinary sodium index were 24% (95% confidence interval (CI) 3-49%), and twofold higher (95% CI 72-150%), respectively, relative to the lowest quintile (P-value for trend across quintiles <0.001). In multivariable models, log-transformed aldosterone was not related to log-UACR. The top quintile of serum aldosterone levels was associated with a 21% higher (95% 1-44%) UACR levels relative to the lowest quintile. Urinary albumin excretion was strongly and positively associated in a continuous fashion with urinary sodium excretion, whereas a weaker nonlinear positive relation with serum aldosterone was noted. Our cross-sectional observations raise the possibility that dietary salt intake may be associated with early renovascular damage.

Atypical presentation of aortic dissection secondary to a gunshot wound

We present a case of aortic dissection secondary to a gunshot wound. The traumatic aortic dissection in this patient occurred secondary to the cavitary forces produced by the bullet passing through the patient's chest. This is a rare phenomenon that could easily be missed if attention is placed only on the more obvious injuries.