bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Health Care Utilization: United States versus Canada
Authors: Pylypchuk Yuriy , Sarpong Eric M.
Published: September 2012

Objective

To compare health care utilization between Canadian and U.S. residents.

Data Sources

Nationally representative 2007 surveys from the Medical Expenditure Panel Survey for the United States and the Canadian Community Health Survey for Canada.

Study Design

We use descriptive and multivariate methods to examine differences in health care utilization rates for visits to medical providers, nurses, chiropractors, specialists, dentists, and overnight hospital stays, usual source of care, Pap smear tests, and mammograms.

Principal Findings

The poor and less educated were more likely to utilize health care in Canada than in the United States. The differences were especially pronounced for having a usual source of care and for visits to providers, specialists, and dentists. Health care use for residents with high incomes and higher levels of education were not markedly different between the two countries and often higher for U.S residents. Foreign‐born residents were more likely to use health care in Canada than in the United States. The descriptive results were confirmed in multivariate regressions.

Conclusions

Given the magnitude of our results, the health insurance structure in Canada might have played an important role in improving access to care for subpopulations examined in this study.
Which States Enroll Their Medicaid‐ Eligible, Citizen Children with Immigrant Parents?
Authors: Seiber Eric E.
Published: September 2012

Objective

To identify which states achieve comparable enrollment rates for Medicaid‐eligible, citizen children with immigrant and nonimmigrant parents.

Data Source

A total of 810,345 Medicaid‐eligible, citizen children drawn from the 2008–2010 American Community Survey.

Study Design

This study estimates a state fixed‐effects probit model of uninsured status for Medicaid‐eligible, citizen children. State and immigrant family interaction variables test whether citizen children in immigrant families have a higher probability of remaining uninsured compared to children in nonimmigrant families. Simulations predict the uninsured rates for Medicaid eligible children in immigrant and nonimmigrant families and rank states by the differences between the two groups.

Principal Findings

While some states have insignificant and near zero differences in predicted uninsured rates, many states have enrollment disparities reaching 20 percent points between citizen children with immigrant and nonimmigrant parents.

Conclusions

Many states have large differences in enrollment rates between their Medicaid‐eligible, citizen children with immigrant and nonimmigrant parents. Addressing these enrollment disparities could improve the health status of citizen children in immigrant families and earn Children's Health Insurance Program Reauthorization Act bonus payments for many states.
Protective effect of nectandrin B, a potent AMPK activator on neointima formation: inhibition of Pin1 expression through AMPK activation
Authors: Ki Sung Hwan , Lee Jung‐Woon , Lim Sung Chul , Hien Tran Thi , Im Ji Hye , Oh Won Keun , Lee Moo Yeol , Ji Young Hyun , Kim Yoon Gyoon , Kang Keon Wook
Published: September 2012

Background and Purpose

Neointima is considered a critical event in the development of vascular occlusive disease. Nectandrin B from nutmeg functions as a potent AMP‐activated protein kinase (AMPK) activators. The present study addressed whether nectandrin B inhibits intimal hyperplasia in guide wire‐injured arteries and examined its molecular mechanism.

Experimental Approach

Neointima was induced by guide wire injury in mouse femoral arteries. Cell proliferation and mechanism studies were performed in rat vascular smooth muscle cells (VSMC) culture model.

Key Results

Nectandrin B increased AMPK activity in VSMC. Nectandrin B inhibited the cell proliferation induced by PDGF and DNA synthesis. Moreover, treatment of nectandrin B suppressed neointima formation in femoral artery after guide wire injury. We have recently shown that Pin1 plays a critical role in VSMC proliferation and neointima formation. Nectandrin B potently blocked PDGF‐induced Pin1 and cyclin D1 expression and nectandrin B‘s anti‐proliferation effect was diminished in Pin1 overexpressed VSMC. PDGF‐induced phosphorylation of ERK and Akt was marginally affected by nectandrin B. However, nectandrin B increased the levels of p53 and its downstream target p21 and, also reversibly decreased the expression of E2F1 and phosphorylated Rb in PDGF‐treated VSMC. AMPK inhibition by dominant mutant form of adenovirus rescued nectandrin B‐mediated down‐regulation of Pin1 and E2F1.

Conclusions and Implications

Nectandrin B inhibited VSMC proliferation and neointima formation via inhibition of E2F1‐dependent Pin1 gene transcription, which is mediated through the activation of an AMPK/p53‐triggered pathway.
Azaindole derivatives are inhibitors of microtubule dynamics, with anti‐cancer and anti‐angiogenic activities
Authors: Prudent Renaud , Vassal‐Stermann Émilie , Nguyen Chi‐Hung , Mollaret Marjorie , Viallet Jean , Desroches‐Castan Agnès , Martinez Anne , Barette Caroline , Pillet Catherine , Valdameri Glaucio , Soleilhac Emmanuelle , Di Pietro Attilio , Feige Jean‐Jacques , Billaud Marc , Florent Jean‐Claude , Lafanechère Laurence
Published: September 2012

Background and Purpose

Drugs targeting microtubules are commonly used for cancer treatment. However, the potency of microtubule inhibitors used clinically is limited by the emergence of resistance. We thus designed a strategy to find new cell‐permeable microtubule‐targeting agents.

Experimental Approach

Using a cell‐based assay designed to probe for microtubule polymerization status, we screened a chemical library and identified two azaindole derivatives, CM01 and CM02, as cell‐permeable microtubule‐depolymerizing agents. The mechanism of the anti‐tumour effects of these two compounds was further investigated both in vivo and in vitro.

Key Results

CM01 and CM02 induced G2/M cell cycle arrest and exerted potent cytostatic effects on several cancer cell lines including multidrug‐resistant (MDR) cell lines. In vitro experiments revealed that the azaindole derivatives inhibited tubulin polymerization and competed with colchicines for this effect, strongly indicating that tubulin is the cellular target of these azaindole derivatives. In vivo experiments, using a chicken chorioallantoic xenograft tumour assay, established that these compounds exert a potent anti‐tumour effect. Furthermore, an assay probing the growth of vessels out of endothelial cell spheroids showed that CM01 and CM02 exert anti‐angiogenic activities.

Conclusions and Implications

CM01 and CM02 are reversible microtubule‐depolymerizing agents that exert potent cytostatic effects on human cancer cells of diverse origins, including MDR cells. They were also shown to inhibit angiogenesis and tumour growth in chorioallantoic breast cancer xenografts. Hence, these azaindole derivatives are attractive candidates for further preclinical investigations.
Vitamin D levels and other factors related to bone mineral density during pregnancy
Authors: Shao Hongfang , Tao Minfang , Fan Yajing , Jing Jianling , Lu Jianping
Published: September 2012

Background

Multiple factors appear to affect bone mineral density (BMD) during pregnancy.

Aims

The aim of this study was to determine the relationships between BMD of the os calcaneus as measured by quantitative ultrasound (QUS) and levels of vitamin D3, parathyroid hormone (PTH), albumin (Alb), calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) in a group of Chinese women.

Methods

Multiple parameters, including density of the os calcaneus, were recorded for a group of 130 women in early (mean gestation, 16.09 ± 2.65 weeks) and late (mean gestation, 32.01 ± 3.45 weeks) stages of pregnancy; 139 nonpregnant women served as controls.

Results

Bone mineral density was lower in pregnant women than in controls at both early and late stages of pregnancy. Levels of Ca, P and ALP were significantly negatively correlated with BMD over the course of pregnancy. Levels of D3, PTH and Alb showed a falling trend from early to late pregnancy as with QUS BMD of the os calcaneus, but the correlations were not statistically significant.

Conclusions

Many factors are correlated with BMD. We suggest that levels of Ca and ALP should be included in the routine examination of pregnant women.
Dinoprostone vaginal pessary for induction of labour: Safety of use for up to 24 h
Authors: Tathem Kellie , Harris Lisa J. , O'Rourke Peter , Kimble Rebecca M.
Published: September 2012

Background

Cervidil® (dinoprostone) intravaginal pessaries are used for induction of labour and maintain serum prostaglandin levels for up to 24 h. The Therapeutic Goods Administration approves Cervidil® for 12‐h use. However, twenty‐four‐hour use of Cervidil® is supported in Europe, New Zealand, America and some Australian hospitals.

Aim

To assess the safety of Cervidil® use for up to 24 h for induction of labour in nulliparous women.

Methods

A retrospective cohort study of 269 consecutive women receiving Cervidil® at the Royal Brisbane and Women's Hospital (RBWH) between July 2007 and December 2008 was performed. The primary outcome measures were frequency of, and time to, uterine tachysystole with or without fetal heart rate (FHR) changes. Secondary outcome measures included frequency of maternal (intrapartum temperature, postpartum haemorrhage) and neonatal (low Apgars, resuscitation, nursery admission) morbidity. Morbidity outcomes of those who received Cervidil® for less than or equal to 12 h were compared with those who received Cervidil® for more than 12 h.

Results

Uterine tachysystole occurred in 9.3% of patients receiving Cervidil®, with a mean time to tachysystole of 10 h. The majority of cases (68%) occurred within 12 h of use. There was no increase in maternal or neonatal morbidity for those who received Cervidil® for longer than 12 h.

Conclusion

Twenty‐four‐hour use of Cervidil® is likely as safe as 12‐h use for induction of labour in nulliparous women.
Unexplored Diversity and Conservation Potential of Neotropical Hot Caves
Authors: Ladle Richard J. , Firmino João V. L. , Malhado Ana C. M. , Rodríguez‐Durán Armando
Published: September 2012

The term hot cave is used to describe some subterranean chambers in the Neotropics that are characterized by constantly high ambient temperatures generated by the body heat of high densities of certain bat species. Many of these species have limited geographic ranges, and some occur only in the hot‐cave environment. In addition to the bats, the stable microclimate and abundant bat guano provides refuge and food for a high diversity of invertebrates. Hot caves have so far been described in the Caribbean and in a few isolated locations from Mexico to Brazil, although there is some evidence that similar caves may be present throughout the tropics. The existing literature suggests these poorly known ecosystems, with their unique combination of geomorphology and bat‐generated microclimate, are particularly sensitive to disturbance and face multiple threats from urbanization, agricultural development, mining, and tourism.

Diversidad No Explorada y Potencial de Conservación de Cuevas Neotropicales Calientes
The Habutengsu metapelites and metagreywackes in western Tianshan, China: metamorphic evolution and tectonic implications
Authors: LÜ Z. , BUCHER K. , ZHANG L. , DU J.
Published: September 2012

The HP‐UHP metamorphic belt of western Tianshan in northwestern China is a rarely preserved oceanic UHP terrane which consists predominantly of meta‐siliciclastic rocks, occasionally accompanied by lens‐shaped metabasites. The metapelites and metagreywackes from the Habutengsu Valley and adjacent area within this belt contain quartz, albite, garnet, white mica, chlorite and rutile/titanite, with or without minor amounts of barroisite, glaucophane, clinozoisite, allanite, graphite, carbonate and tourmaline. Included in coarse‐grained garnet, pseudomorphs of clinozoisite + paragonite after lawsonite are common, seldom also together with inclusions of chloritoid, jadeite and glaucophane. In the northern Habutengsu area, garnet is compositionally characterized by similar cores with consistently low‐Ca content. Similar garnet armouring coesite has been reported in UHP schists from the same area. Deduced P–T conditions during formation of these Ca‐poor garnet cores are 25–31 kbar and 430–510 °C, which are consistent with the computed stability of the observed assemblage Grt + Gln + Lws ± Jd ± Cld in the coesite stability field. Thus, the occurrences of the UHP metapelites and metagreywackes define an internally coherent UHP unit in the north of the Habutengsu area, the spatial extension of which is much larger than previously known. Compared with the northern ones, the southern metapelites and metagreywackes in the Habutengsu area consist of similar minerals and have similar bulk rock compositions but significantly different garnet chemistry, indicating an abrupt variation in P–T conditions during garnet growth. The derived conditions initiating the garnet growth for the southern rocks in a similar range (18–21 kbar and 450–500 °C) and thus constrain a coherent HP unit in the south of the Habutengsu area. The juxtaposition of two exhumed slices of contrasting metamorphic grades probably indicates the change of subduction dynamics of the palaeo‐Tianshan oceanic crust, the subduction polarity (from south to north) of which accounts for the spatial relationship between these two units.
Cutaneous Leukocytoclastic Vasculitis due to Salmonella enteritidis in a Child with Interleukin‐12 Receptor Beta‐1 Deficiency
Authors: Filiz Serkan , Kocacik Uygun Dilara F. , Verhard Els M. , van Dissel Jaap T. , Uygun Vedat , Bassorgun Cumhur , Bingol Aysen , Yegin Olcay , van de Vosse Esther
Published: September 2012

Abstract:  Defects in the interleukin 12 (IL‐12)/interferon gamma (IFN‐γ) pathway result in Mendelian susceptibility to mycobacterial disease (MSMD). IL‐12 receptor beta 1 (IL‐12Rβ1) deficiency, the most common form of MSMD, is associated with weakly virulent mycobacteria and salmonella. Infections in patients with this deficiency are extraintestinal, or septicemic, recurrent infections with nontyphoid salmonellae. Here we report a case of an IL‐12Rβ1 deficiency with cutaneous leukocytoclastic vasculitis due to Salmonella enteritidis.
Lack of Effect of Propranolol in the Treatment of Lymphangioma in Two Children
Authors: Maruani Annabel , Brown Shanna , Lorette Gerard , Pondaven‐Letourmy Soizick , Herbreteau Denis , Eisenbaum Allan
Published: September 2012

Abstract:  Vascular lesions such as hemangiomas and lymphangiomas can cause significant mortality and morbidity, as well as amblyopia when located in the orbit. Oral propranolol can regress infantile hemangioma during infancy and up to 23 months of age, but its effect on lymphangioma has not been demonstrated. We present two cases of lymphatic malformations treated with oral propranolol. Patient 1 is a 2‐year‐old boy with macrocystic bilateral cervical lymphangioma extending to the pharynx and larynx and microcystic lymphangioma of the tongue. The patient was started on propranolol 2 mg/kg/day starting at 17 months of age, and after 3 months only a very slight decrease in tongue volume was noted. Patient 2 is a 3.5‐year‐old boy with magnetic resonance imaging evidence of right facial complex lymphangioma with venous malformation. The patient was placed on oral propranolol 2 mg/kg/day. After 3 months of treatment, no change in the lesion was noted except for a transient decrease in the size of the conjunctival telangiectasia. Propranolol 2 mg/kg/day was not effective in treating lymphatic malformations in two children, both older than 17 months at the time of treatment.
Effect of Forced Transitions on the Most Functionally Impaired Nursing Home Residents
Authors: Thomas Kali S. , Dosa David , Hyer Kathryn , Brown Lisa M. , Swaminathan Shailender , Feng Zhanlian , Mor Vincent
Published: September 2012

Objectives

To examine the hospitalization rate and mortality associated with forced mass transfer of nursing home (NH) residents with the highest levels of functional impairment.

Design

Retrospective cohort study.

Setting

One hundred nineteen Texas and Louisiana NHs identified as being at risk for evacuation for Hurricane Gustav.

Participants

Six thousand four hundred sixty‐four long‐stay residents residing in at‐risk NHs for at least three consecutive months before landfall of Hurricane Gustav.

Measurements

Using Medicare claims and instrumental variable analysis, the mortality (death at 30 and 90 days) and hospitalization rates (at 30 and 90 days) of the most functionally impaired long‐stay residents who were evacuated for Hurricane Gustav were compared with those of the most functionally impaired residents who did not evacuate.

Results

The effect of evacuation was associated with 8% more hospitalizations by 30 and 90 days for the most functionally impaired residents. Evacuation was not significantly related to mortality.

Conclusion

The most functionally impaired NH residents experience more hospitalizations but not mortality as a consequence of forced mass transfer. With the inevitability of NH evacuations for many different reasons, harm mitigation strategies focused on the most impaired residents are needed.
Does Feeding Tube Insertion and Its Timing Improve Survival?
Authors: Teno Joan M. , Gozalo Pedro L. , Mitchell Susan L. , Kuo Sylvia , Rhodes Ramona L. , Bynum Julie P. W. , Mor Vincent
Published: September 2012

Objectives

To examine survival with and without a percutaneous endoscopic gastrostomy (PEG) feeding tube using rigorous methods to account for selection bias and to examine whether the timing of feeding tube insertion affected survival.

Design

Prospective cohort study.

Setting

All U.S. nursing homes (NHs).

Participants

Thirty‐six thousand four hundred ninety‐two NH residents with advanced cognitive impairment from dementia and new problems eating studied between 1999 and 2007.

Measurements

Survival after development of the need for eating assistance and feeding tube insertion.

Results

Of the 36,492 NH residents (88.4% white, mean age 84.9, 87.4% with one feeding tube risk factor), 1,957 (5.4%) had a feeding tube inserted within 1 year of developing eating problems. After multivariate analysis correcting for selection bias with propensity score weights, no difference was found in survival between the two groups (adjusted hazard ratio (AHR) = 1.03, 95% confidence interval (CI) = 0.94–1.13). In residents who were tube‐fed, the timing of PEG tube insertion relative to the onset of eating problems was not associated with survival after feeding tube insertion (AHR = 1.01, 95% CI = 0.86–1.20, persons with a PEG tube inserted within 1 month of developing an eating problem versus later (4 months) insertion).

Conclusion

Neither insertion of PEG tubes nor timing of insertion affect survival.
Antibody levels correlate with detection of Trypanosoma cruzi DNA by sensitive polymerase chain reaction assays in seropositive blood donors and possible resolution of infection over time
Authors: Sabino Ester C. , Lee Tzong‐Hae , Montalvo Lani , Nguyen Megan L. , Leiby David A. , Carrick Danielle M. , Otani Marcia M. , Vinelli Elizabeth , Wright David , Stramer Susan L. , Busch Michael ,   NHLBI Retrovirus Epidemiology Donor Study‐II (REDS‐II) International Program
Published: September 2012

BACKGROUND: The clinical significance of anti‐Trypanosoma cruzi low‐level reactive samples is incompletely understood. Polymerase chain reaction (PCR)‐positive rates and antibody levels among seropositive blood donors in three countries are described.

STUDY DESIGN AND METHODS: Follow‐up samples were collected from T. cruzi–seropositive donors from 2008 through 2010 in the United States (n = 195) and Honduras (n = 58). Also 143 samples from Brazil in 1996 to 2002, originally positive by three serologic assays, were available and paired with contemporary follow‐up samples from these donors. All samples were retested with Ortho enzyme‐linked immunosorbent assay (ELISA). PCR assays were performed on coded sample panels by two laboratories (Blood Systems Research Institute [BSRI] and American Red Cross Holland Laboratory [ARC]) that amplified kinetoplast minicircle DNA sequences of T. cruzi.

RESULTS: PCR testing at BSRI yielded slightly higher overall sensitivity and specificity (33 and 98%) compared with those at the ARC (28 and 94%). Among seropositive donors, PCR‐positive rates varied by country (p < 0.0001) for the BSRI laboratory: Brazil (57%), Honduras (32%), and the United States (14%). ELISA signal‐to‐cutoff ratios (S/CO) were significantly higher for PCR‐positive compared to PCR‐negative donors (p < 0.05 for all comparisons). Additionally, PCR‐negative Brazilian donors exhibited greater frequencies of antibody decline over time versus PCR‐positive donors (p = 0.003).

CONCLUSION: For all three countries, persistent DNA positivity correlated with higher ELISA S/CO values, suggesting that high‐level seroreactivity reflects chronic parasitemia. Significant S/CO declines in 10% of the PCR‐negative Brazilian donors may indicate seroreversion after parasite clearance in the absence of treatment.
Prevalence and clinical significance of low‐avidity HPA‐1a antibodies in women exposed to HPA‐1a during pregnancy
Authors: Peterson Julie A. , Kanack Adam , Nayak Dhirendra , Bougie Daniel W. , McFarland Janice G. , Curtis Brian R. , Aster Richard H.
Published: September 2012

BACKGROUND: Recent studies suggest that HPA‐1a–specific, low‐avidity maternal antibodies not detectable by conventional methods can cause neonatal alloimmune thrombocytopenia (NAIT). We performed studies to further define the incidence and clinical significance of this type of antibody.

STUDY DESIGN AND METHODS: Surface plasmon resonance analysis was used to detect low‐avidity antibodies in HPA‐1a–negative, “antibody‐negative” mothers of suspected NAIT cases. The ability of antibodies detected to promote immune destruction of human platelets (PLTs) was examined in a newly developed NOD/SCID mouse model.

RESULTS: Among 3478 suspected cases of NAIT, 677 HPA‐1a–negative mothers were identified. HPA‐1a–specific antibodies were detected by conventional antibody testing in 616 cases (91%). Low‐avidity HPA‐1a–specific antibodies were identified in 18 of the remaining 61 cases (9%). Clinical follow‐up on 13 cases showed that eight were referred because of suspected NAIT and five because the mother's sister had previously had an infant with NAIT. Only six infants born to the 13 sensitized mothers had clinically significant thrombocytopenia at birth. Three of four low‐avidity antibodies tested in the mouse caused accelerated clearance of HPA‐1a/a but not HPA‐1b/b PLTs. Only 3 of 12 mothers with low‐avidity HPA‐1a antibodies were positive for HLA‐DRB3*0101.

CONCLUSIONS: The findings confirm previous reports that low‐avidity HPA‐1a antibodies can cause NAIT but show that the presence of such an antibody does not predict that an infant will be affected. The low incidence of HLA‐DRB3*0101 in this cohort (p < 0.0001) suggests that women negative for DRB3*0101 may be predisposed to produce low‐avidity HPA‐1a antibodies.
Incremental Value of Perfusion over Wall‐Motion Abnormalities with the Use of Dobutamine–Atropine Stress Myocardial Contrast Echocardiography and Magnetic Resonance Imaging for Detecting Coronary Artery Disease
Authors: Falcão Sandra Nivea dos Reis Saraiva , Rochitte Carlos Eduardo , Junior Wilson Mathias , Quaglia Luiz , Lemos Pedro Alves , Sbano João César Nunes , Ramires José Antonio Franchini , Filho Roberto Kalil , Tsutsui Jeane Mike
Published: September 2012

Background

Recently, multimodality imaging has been demonstrated to improve the sensitivity of dobutamine stress for the diagnosis of coronary artery disease (CAD). Objective: We sought to determine the additional value of myocardial perfusion (MP) over wall‐motion (WM) analysis for detecting CAD, using real time myocardial contrast echocardiography (RTMCE) and cardiovascular magnetic resonance (CMR), in the same group of patients.

Methods

We studied 42 patients who underwent RTMCE and CMR during high‐dose dobutamine stress with early injection of atropine.

Results

No difference was observed in the diagnostic accuracy of RTMCE and CMR for detecting angiographically significant CAD when considering WM analysis alone (73% [95% CI, 65–81] and 78% [95% CI, 70–84], respectively; P = NS) or combined analysis of WM and MP (80% [95% CI, 73–97] and 83% [95% CI, 77–90], respectively; P = NS). Combined analysis of WM and MP had higher sensitivity than the analysis of WM alone by RTMCE (88% [95% CI, 75–100] vs. 72% [95% CI, 54–90]) and by CMR (92% [95% CI, 81–100] vs. 80% [95% CI, 64–96]) with no differences in specificity. The association of abnormal WM and MP abnormalities during high‐dose dobutamine–atropine stress had additional value for detecting CAD over the analysis of WM alone, both by RTMCE (χ2 = 16.16–24.13; P = 0.005) and CMR (χ2 = 12.73–27.41; P = 0.001).

Conclusion

RTMCE and CMR using the same dobutamine–atropine stress protocol had comparable diagnostic accuracies for the detection of angiographically significant CAD. MP imaging had additional value over WM analysis for the diagnosis of CAD, both at RTMCE and CMR.
Dynamic Migration of a Mobile Plaque from the Brachiocephalic Artery Detected by Ultrasonography
Authors: Watari Mari , Nakajima Makoto , Nishitomi‐Izumida Megumi , Inatomi Yuichiro , Yonehara Toshiro , Hirano Teruyuki
Published: September 2012

Mini‐Abstract

A 72‐year‐old woman with a history of radiation therapy on the right neck and thorax developed multiple brain embolism. Transthoracic ultrasonography demonstrated a mobile plaque attached to the beginning of the brachiocephalic artery. Over a week, we detected the plaque that had migrated to the beginning of the left external carotid artery without any neurological symptoms. Ultrasonography was very useful to observe the course of the mobile plaque.
Bayesian Inference for the Causal Effect of Mediation
Authors: Daniels Michael J. , Roy Jason A. , Kim Chanmin , Hogan Joseph W. , Perri Michael G.
Published: September 2012

Summary We propose a nonparametric Bayesian approach to estimate the natural direct and indirect effects through a mediator in the setting of a continuous mediator and a binary response. Several conditional independence assumptions are introduced (with corresponding sensitivity parameters) to make these effects identifiable from the observed data. We suggest strategies for eliciting sensitivity parameters and conduct simulations to assess violations to the assumptions. This approach is used to assess mediation in a recent weight management clinical trial.
A General Class of Semiparametric Transformation Frailty Models for Nonproportional Hazards Survival Data
Authors: Choi Sangbum , Huang Xuelin
Published: September 2012

Summary We propose a semiparametrically efficient estimation of a broad class of transformation regression models for nonproportional hazards data. Classical transformation models are to be viewed from a frailty model paradigm, and the proposed method provides a unified approach that is valid for both continuous and discrete frailty models. The proposed models are shown to be flexible enough to model long‐term follow‐up survival data when the treatment effect diminishes over time, a case for which the PH or proportional odds assumption is violated, or a situation in which a substantial proportion of patients remains cured after treatment. Estimation of the link parameter in frailty distribution, considered to be unknown and possibly dependent on a time‐independent covariates, is automatically included in the proposed methods. The observed information matrix is computed to evaluate the variances of all the parameter estimates. Our likelihood‐based approach provides a natural way to construct simple statistics for testing the PH and proportional odds assumptions for usual survival data or testing the short‐ and long‐term effects for survival data with a cure fraction. Simulation studies demonstrate that the proposed inference procedures perform well in realistic settings. Applications to two medical studies are provided.
Bayesian Latent Factor Regression for Functional and Longitudinal Data
Authors: Montagna Silvia , Tokdar Surya T. , Neelon Brian , Dunson David B.
Published: September 2012

SummaryIn studies involving functional data, it is commonly of interest to model the impact of predictors on the distribution of the curves, allowing flexible effects on not only the mean curve but also the distribution about the mean. Characterizing the curve for each subject as a linear combination of a high‐dimensional set of potential basis functions, we place a sparse latent factor regression model on the basis coefficients. We induce basis selection by choosing a shrinkage prior that allows many of the loadings to be close to zero. The number of latent factors is treated as unknown through a highly‐efficient, adaptive‐blocked Gibbs sampler. Predictors are included on the latent variables level, while allowing different predictors to impact different latent factors. This model induces a framework for functional response regression in which the distribution of the curves is allowed to change flexibly with predictors. The performance is assessed through simulation studies and the methods are applied to data on blood pressure trajectories during pregnancy.
Estimating Diagnostic Accuracy of Raters Without a Gold Standard by Exploiting a Group of Experts
Authors: Zhang Bo , Chen Zhen , Albert Paul S.
Published: September 2012

SummaryIn diagnostic medicine, estimating the diagnostic accuracy of a group of raters or medical tests relative to the gold standard is often the primary goal. When a gold standard is absent, latent class models where the unknown gold standard test is treated as a latent variable are often used. However, these models have been criticized in the literature from both a conceptual and a robustness perspective. As an alternative, we propose an approach where we exploit an imperfect reference standard with unknown diagnostic accuracy and conduct sensitivity analysis by varying this accuracy over scientifically reasonable ranges. In this article, a latent class model with crossed random effects is proposed for estimating the diagnostic accuracy of regional obstetrics and gynaecological (OB/GYN) physicians in diagnosing endometriosis. To avoid the pitfalls of models without a gold standard, we exploit the diagnostic results of a group of OB/GYN physicians with an international reputation for the diagnosis of endometriosis. We construct an ordinal reference standard based on the discordance among these international experts and propose a mechanism for conducting sensitivity analysis relative to the unknown diagnostic accuracy among them. A Monte Carlo EM algorithm is proposed for parameter estimation and a BIC‐type model selection procedure is presented. Through simulations and data analysis we show that this new approach provides a useful alternative to traditional latent class modeling approaches used in this setting.
Estimating Open Population Site Occupancy from Presence–Absence Data Lacking the Robust Design
Authors: Dail D. , Madsen L.
Published: September 2012

Many animal monitoring studies seek to estimate the proportion of a study area occupied by a target population. The study area is divided into spatially distinct sites where the detected presence or absence of the population is recorded, and this is repeated in time for multiple seasons. However, when occupied sites are detected with probabilityp< 1, the lack of a detection does not imply lack of occupancy. MacKenzie et al. (2003,Ecology84, 2200–2207) developed a multiseason model for estimating seasonal site occupancy (ψt) while accounting for unknownp. Their model performs well when observations are collected according to the robust design, where multiple sampling occasions occur during each season; the repeated sampling aids in the estimationp. However, their model does not perform as well when the robust design is lacking. In this paper, we propose an alternative likelihood model that yields improved seasonal estimates ofpand Ψtin the absence of the robust design. We construct the marginal likelihood of the observed data by conditioning on, and summing out, the latent number of occupied sites during each season. A simulation study shows that in cases without the robust design, the proposed model estimatespwith less bias than the MacKenzie et al. model and hence improves the estimates of Ψt. We apply both models to a data set consisting of repeated presence–absence observations of American robins (Turdus migratorius) with yearly survey periods. The two models are compared to a third estimator available when the repeated counts (from the same study) are considered, with the proposed model yielding estimates of Ψtclosest to estimates from the point count model.
Testing for Homogeneity of Multivariate Dispersions Using Dissimilarity Measures
Authors: Gijbels Irène , Omelka Marek
Published: September 2012

Testing homogeneity of dispersions may be of its own scientific interest as well as an important auxiliary step verifying assumptions of a main analysis. The problem is that many biological and ecological data are highly skewed and zero‐inflated. Also the number of variables often exceeds the sample size. Thus data analysts often do not rely on parametric assumptions, but use a particular dissimilarity measure to calculate a matrix of pairwise differences. This matrix is then the basis for further statistical inference. Anderson (2006) proposed a distance‐based test of homogeneity of multivariate dispersions for a one‐way ANOVA design, for which a matrix of pairwise dissimilarities can be taken as an input. The key idea, like in Levene's test, is to replace each observation with its distance to an estimated group center. In this paper we suggest an alternative approach that is based on the means of within‐group distances and does not require group centre calculations to obtain the test statistic. We show that this approach can have theoretical as well as practical advantages. A permutation procedure that gives type I error close to the prescribed value even in small samples is described.
Corrected Confidence Bands for Functional Data Using Principal Components
Authors: Goldsmith J. , Greven S. , Crainiceanu C.
Published: September 2012

Functional principal components (FPC) analysis is widely used to decompose and express functional observations. Curve estimates implicitly condition on basis functions and other quantities derived from FPC decompositions; however these objects are unknown in practice. In this article, we propose a method for obtaining correct curve estimates by accounting for uncertainty in FPC decompositions. Additionally, pointwise and simultaneous confidence intervals that account for both model‐ and decomposition‐based variability are constructed. Standard mixed model representations of functional expansions are used to construct curve estimates and variances conditional on a specific decomposition. Iterated expectation and variance formulas combine model‐based conditional estimates across the distribution of decompositions. A bootstrap procedure is implemented to understand the uncertainty in principal component decomposition quantities. Our method compares favorably to competing approaches in simulation studies that include both densely and sparsely observed functions. We apply our method to sparse observations of CD4 cell counts and to dense white‐matter tract profiles. Code for the analyses and simulations is publicly available, and our method is implemented in the R package refund on CRAN.
Grain Size‐Dependent Properties of Dense Nanocrystalline Barium Titanate Ceramics
Authors: Curecheriu Lavinia , Balmus Sorin‐Bogdan , Buscaglia Maria Teresa , Buscaglia Vincenzo , Ianculescu Adelina , Mitoseriu Liliana
Published: September 2012

The grain size influence on the dielectric relaxation and nonlinear dielectric properties of BaTiO3 ceramics with grain size in the range of (92÷936) nm densified by Spark Plasma Sintering (SPS) from ultrafine powders were investigated. The progressive reduction of the Curie temperature and of the effective permittivity results from a combination of intrinsic size effects and low‐permittivity grain boundary layer. A model of dielectric cylindrical cavities was employed in order to calculate intrinsic effective permittivity values in GHz range. An interesting feature is the presence of a thermally activated Debye‐like relaxation in the ferroelectric state of ceramics with grain size above 300 nm, with activation energies of 0.45–0.49 eV, which seems to be related to the domain walls forced motion under the applied field. By diminishing grain size, a progressive reduction of the ferroelectric nonlinear character was obtained, reaching a macroscopic non‐switching character and a linear permittivity versus field dependence for the finest ceramics (grain size of 90–100 nm) until very high values of the applied field. The observed behavior supports the idea of frozen polarization induced by pinning centers as due to a large number of grain boundaries and charged defects in the fine structures.
Validity and reproducibility of an iodine‐specific food frequency questionnaire to estimate dietary iodine intake in older Australians
Authors: TAN Li‐Min , CHARLTON Karen E. , TAN Sze‐Yen , MA Gary , BATTERHAM Marijka
Published: September 2012

Aim: Iodine deficiency, which has adverse effects on health has re‐emerged in Australia. The present study aimed to develop and validate a novel iodine‐specific food frequency questionnaire for use in older Australians.

Methods: A 49‐item food frequency questionnaire that included iodine‐rich foods was constructed and administered in 84 men and women aged 60–95 years with normal cognitive function. Dietary iodine intake assessed by the food frequency questionnaire was validated against three repeated 24‐hour dietary recalls. Urinary spot iodine concentrations were selected as iodine intake biomarker. Agreement between the two dietary methods was determined using a Bland–Altman plot and intra‐class coefficients. Correlations between dietary and urinary iodine were assessed. Forty‐three participants repeated the questionnaire after 9 months for reproducibility.

Results: Mean iodine intake measured by the food frequency questionnaire and 24‐hour dietary recalls did not differ significantly (P= 0.870). The two methods were moderately correlated (r = 0.377;P< 0.05) and the Bland–Altman plots demonstrated an acceptable level of agreement (P= 0.870). Despite an association (r = 0.230;P< 0.05) between urinary iodine concentrations and 24‐hour dietary recalls, the food frequency questionnaire was not associated with urinary iodine concentration (r = 0.094;P= 0.40). The method of triads showed coefficients of 0.238 (urinary iodine), 0.953(food frequency questionnaire), 0.396 (24‐hour dietary recall) with the unknown true value.

Conclusion: A short food frequency questionnaire to assess habitual dietary iodine intake in older Australians has been shown to be valid at the group level with regard to categorising individuals according to their habitual iodine intake. Reproducibility of the food frequency questionnaire remains to be demonstrated.
Shortfall in the consumption of dairy foods in Australian children's diets: Addressing health implications and practical approaches
Authors: SPENCE Lisa A.
Published: September 2012

Aim:  This paper provides an overview of the consumption of dairy foods by Australian children and their contribution to nutrient intake, diet quality and optimal health. Practical approaches to meet the recommended intake of dairy foods are also presented.

Methods:  A computerised search was conducted of English language papers on PubMed. Additional papers were identified by searching references in relevant papers and book chapters.

Results:  A high proportion of Australian children do not meet the dietary requirements for calcium or the recommended intake of dairy foods. The consumption of dairy foods is critical for meeting calcium requirements while providing significant amounts of other nutrients. Studies demonstrate that dairy food consumption is important for growth, building peak bone mass and prevention of osteoporosis and bone fracture. While there is evidence that dairy food consumption may play a role in other diseases, that is, obesity and hypertension, there are limited studies in children. Various barriers may limit intake thus effective behavioural interventions need to be developed.

Conclusions:  Diets including recommended amounts of dairy foods can help maximize peak bone mass, minimize bone loss and promote overall health. Dieticians are integral in educating children and their parents and caregivers who are key in encouraging children to consume recommended amounts of dairy foods.
Label reading nutrient criteria: A survey of Australian nutrition professionals
Authors: PRATT Iain Stephen , MUHLMANN Loren , ERICKSON Hayley
Published: September 2012

Aim:  The aims of the present study were (i) to identify the format of resources that nutrition professionals use to educate consumers about reading nutrition information panels; (ii) to identify the most common nutrient criteria; and (iii) to assess the suitability of the nutrient criteria by assessing them against foods commonly eaten in Australia, from products in NUTTAB 2006.

Methods:  An online 13‐question survey, asking about resources and nutrient criteria used, was distributed by email by the Dietitians Association of Australia. A total of 240 surveys were completed. The most common nutrient criteria were identified and tested against common foods in the NUTTAB 2006 database to make an assessment on suitability.

Results:  The most common resource format was diet sheet, and the most common criterion for each nutrient was: energy <600 kJ/snack food, total fat <10 g/100 g, saturated fat <3 g/100 g, sugar <10 g/100 g, fibre >3 g/serve and sodium <120 mg/100 g. One‐third of common foods in Australia met all four of the ‘per 100 g’ nutrient criteria.

Conclusions:  The majority of respondents had a set of nutrient criteria for educating consumers about reading and understanding nutrition information panels. The most common nutrient criteria allowed sufficient number of foods to choose from, suggesting that the four most common ‘per 100 g’ nutrient criteria are suitable for use with consumers.
Testing the boundaries of recommended carbohydrate intakes: Macronutrient exchanges, carbohydrate quality and nutritional adequacy
Authors: SHRAPNEL Bill
Published: September 2012

Aim:  The aim of this study was to explore the relationships between dietary carbohydrate, other macronutrients, carbohydrate quality and nutritional adequacy in the diets of free‐living Australian teenagers, and to consider the implications for total carbohydrate recommendations.

Methods:  Using the Children's Nutrition and Physical Activity Survey (2007) database, the nutrient intakes of boys and girls aged 14–16 years were assessed by quintile of carbohydrate intake.

Results:  Carbohydrate intake was inversely associated with intakes of saturated fat, polyunsaturated fat, long‐chain omega 3, monounsaturated fat and protein (for each association, P for trend <0.001). Carbohydrate intake was associated with increased intake of fibre in boys (P for trend <0.05) but not girls, the association being nonlinear. As carbohydrate intake increased, the densities of fibre, vitamin C, folate, thiamin and β‐carotene declined and the density of sugar increased, implying a decline in carbohydrate quality. Nutritional adequacy was generally compatible with a wide range of carbohydrate intakes.

Conclusions:  In combination, the exchanges of carbohydrate for polyunsaturated fat, long‐chain omega 3, monounsaturated fat and protein would be expected to increase coronary disease risk via several mechanisms. This implies that there may be a progressive increase in coronary risk as carbohydrate intakes increase across the Acceptable Macronutrient Distribution Range (AMDR), as the exchange of carbohydrate for saturated fat is now considered to be neutral for coronary risk. There is a case for lowering the upper and lower boundaries of the AMDR for carbohydrate intake as a strategy for chronic disease prevention. Lower boundaries would be unlikely to increase the risk for obesity or nutrient inadequacy.
Availability of Emergency Contraception in Rural and Urban Pharmacies in Kansas
Authors: Samson Fernand D. , Loren Rebecca , Downing Nicki , Schroeppel Sarah , Kelly Patricia J. , Ramaswamy Megha
Published: September 2012

Purpose: Determine availability of emergency contraception (EC) at rural and urban pharmacies in Kansas.

Methods: A sample of 201 Kansas pharmacies was selected using a random integer generator. We measured ability to dispense EC within 24 hours and whether it was in stock at the time of the survey call. We examined EC availability based on geographic differences and pharmacy type.

Findings: Of the sample, 186 pharmacists agreed to be interviewed. Of these, 19% (n = 36) were unable to provide EC within 24 hours. There were essentially no differences in availability of EC between rural (75% could dispense in 24 hours) and urban pharmacies (85% could dispense in 24 hours) (P= .105). Corporate pharmacies were more likely to be able to provide EC within 24 hours compared to independent pharmacies (OR = 3.79, CI 1.71‐8.43). Thirty‐one percent (n = 57) of pharmacists did not carry EC at the time of the survey call. With this sample, urban pharmacies were more than twice as likely to report carrying EC compared to rural pharmacies (OR = 2.47, CI 1.31‐4.68), and corporate pharmacies were also more likely to report carrying EC compared to independent pharmacies (OR = 7.77, CI 3.72‐16.21).

Conclusions: In a sample of Kansas pharmacies, there were no differences between rural and urban pharmacies in 24‐hour EC availability; however, there were differences in those who stocked EC at the time of the survey call. Corporate pharmacies were more likely to dispense EC within 24 hours and have it in stock compared to independent pharmacies, suggesting differences in availability of EC.
Rural‐Urban Differences in Consumer Governance at Community Health Centers
Authors: Wright Brad
Published: September 2012

Context: Community health centers (CHCs) are primary care clinics that serve mostly low‐income patients in rural and urban areas. They are required to be governed by a consumer majority. What little is known about the structure and function of these boards in practice suggests that CHC boards in rural areas may look and act differently from CHC boards in urban areas.

Purpose: To identify differences in the structure and function of consumer governance at CHCs in rural and urban areas.

Methods: Semistructured telephone interviews were conducted with 30 CHC board members from 14 different states. Questions focused on board members’ perceptions of board composition and the role of consumers on the board.

Findings: CHCs in rural areas are more likely to have representative boards, are better able to convey confidence in the organization, and are better able to assess community needs than CHCs in urban areas. However, CHCs in rural areas often have problems achieving objective decision‐making, and they may have fewer means for objectively evaluating quality of care due to the lack of patient board member anonymity.

Conclusions: Consumer governance is implemented differently in rural and urban communities, and the advantages and disadvantages in each setting are unique.