Comparing the Two- and Three-Parameter Logistic Models via Likelihood Ratio Tests: A Commonly Misunderstood Problem

Selection of an appropriate item response model is critical in the measurement of latent examinee ability. The one-, two-, and three-parameter logistic (1PL, 2PL, and 3PL) models are nested, and as such can be compared using likelihood ratio (LR) tests. The null hypothesis in the LR test for selection among the 2PL and 3PL models sets the guessing parameters to their lower bound of 0. This violates one of the assumptions of the LR test and renders the usual χ2 reference distribution inappropriate for the comparison. A review of the current literature revealed that this problem is not well understood in the educational measurement field. Ignoring this issue can lead to selection of an overly simplified model, with implications for the ability estimates. In this article, the use of the LR test for item response model selection is investigated, with the goal of providing practitioners with an appropriate method of selecting the most parsimonious model. The results of simulation studies indicate the nature of the problem, with inaccurate Type I error rates for cases where the inappropriate null distribution was used. An analysis of data from a statewide mathematics test showed differences pertinent to subsequent analyses.

Conservative management of preterm premature rupture of membranes beyond 32 weeks' gestation: is it worthwhile?

We aimed to investigate whether conservative management of preterm premature rupture of membranes (PPROM) at 32-34 weeks' gestation improves outcome. In this retrospective analysis of singleton pregnancies, the study group included patients with PPROM at 28-34 weeks' gestation and the control group included patients presented with spontaneous preterm delivery at 28-34 weeks' gestation. Both groups were subdivided according to gestational age - early (28-31 weeks' gestation) versus late (32-34 weeks' gestation). Adverse neonatal outcome included neonatal death, intraventricular haemorrhage grade 3/4, respiratory distress syndrome, periventricular leucomalacia and neonatal sepsis. The study and control groups included 94 and 86 women, respectively. The study group had a lower incidence of adverse neonatal outcome at the earlier weeks (28-31), compared with the control group at the same gestational age. In contrast, at 32-34 weeks' gestation no difference in the risk for adverse neonatal outcome was noticed. Additionally, within the study group, chorioamnionitis rate was significantly higher among those who delivered at 32-34 weeks' gestation (p < 0.01). No advantage for conservative management of PPROM was demonstrated beyond 31 weeks' gestation. Moreover, conservative management of PPROM at 32-34 weeks' gestation may expose both mother and neonate to infectious morbidity.

Cardiac troponin-I on diagnosis predicts early death and refractoriness in acquired thrombotic thrombocytopenic purpura. Experience of the French Thrombotic Microangiopathies Reference Center

BACKGROUND

Cardiac involvement is a major cause of mortality in patients with thrombotic thrombocytopenic purpura (TTP). However, diagnosis remains underestimated and delayed, owing to subclinical injuries. Cardiac troponin-I measurement (cTnI) on admission could improve the early diagnosis of cardiac involvement and have prognostic value.

OBJECTIVES

To assess the predictive value of cTnI in patients with TTP for death or refractoriness.

PATIENTS/METHODS

The study involved a prospective cohort of adult TTP patients with acquired severe ADAMTS-13 deficiency (< 10%) and included in the registry of the French Reference Center for Thrombotic Microangiopathies. Centralized cTnI measurements were performed on frozen serum on admission.

RESULTS

Between January 2003 and December 2011, 133 patients with TTP (mean age, 48 ± 17 years) had available cTnI measurements on admission. Thirty-two patients (24%) had clinical and/or electrocardiogram features. Nineteen (14.3%) had cardiac symptoms, mainly congestive heart failure and myocardial infarction. Electrocardiogram changes, mainly repolarization disorders, were present in 13 cases. An increased cTnI level (> 0.1 μg L(-1) ) was present in 78 patients (59%), of whom 46 (59%) had no clinical cardiac involvement. The main outcomes were death (25%) and refractoriness (17%). Age (P = 0.02) and cTnI level (P = 0.002) showed the greatest impact on survival. A cTnI level of > 0.25 μg L(-1) was the only independent factor in predicting death (odds ratio [OR] 2.87; 95% confidence interval [CI] 1.13-7.22; P = 0.024) and/or refractoriness (OR 3.03; 95% CI 1.27-7.3; P = 0.01).

CONCLUSIONS

A CTnI level of > 0.25 μg L(-1) at presentation in patients with TTP appears to be an independent factor associated with a three-fold increase in the risk of death or refractoriness. Therefore, cTnI level should be considered as a prognostic indicator in patients diagnosed with TTP.

The Current State of Vaccine Development for Ocular HSV-1 Infection

HSV-1 continues to be the leading cause of infectious corneal blindness. Clinical trials for vaccines against genital HSV infection have been ongoing for more than three decades. Despite this, no approved vaccine exists, and no formal clinical trials have evaluated the impact of HSV vaccines on eye health. We review here the current state of development for an efficacious HSV-1 vaccine and call for involvement of ophthalmologists and vision researchers.

The nitration pattern of energetic 3,6-diamino-1,2,4,5-tetrazine derivatives containing azole functional groups

A study of nitration patterns was conducted on 3,6-diamino-1,2,4,5-tetrazines derivatives, revealing the specificity of their nitration, as well as the stability of the formed nitramines towards hydrolysis.

The unexpected formation of [M - H]+ species during MALDI and dopant-free APPI MS analysis of novel antineoplastic curcumin analogues

Unusual ionization behavior was observed with novel antineoplastic curcumin analogues during the positive ion mode of matrix-assisted laser desorption ionization (MALDI) and dopant-free atmospheric pressure photoionization (APPI). The tested compounds produced an unusual significant peak designated as [M - H](+) ion along with the expected [M + H](+) species. In contrast, electrospray ionization, atmospheric pressure chemical ionization and the dopant-mediated APPI (dopant-APPI) showed only the expected [M + H](+) peak. The [M - H](+) ion was detected with all evaluated curcumin analogues including phosphoramidates, secondary amines, amides and mixed amines/amides. Our experiments revealed that photon energy triggers the ionization of the curcumin analogues even in the absence of any ionization enhancer such as matrix, solvent or dopant. The possible mechanisms for the formation of both [M - H](+) and [M + H](+) ions are discussed in this paper. In particular, three proposed mechanisms for the formation of [M - H](+) were evaluated. The first mechanism involves the loss of H2 from the protonated [M + H](+) species. The other two mechanisms include hydrogen transfer from the analyte radical cation or hydride abstraction from the neutral analyte molecule.

Relationship of bone mineralization density distribution (BMDD) in cortical and cancellous bone within the iliac crest of healthy premenopausal women

Bone mineralization density distribution (BMDD) is an important determinant of bone mechanical properties. The most available skeletal site for access to the BMDD is the iliac crest. Compared to cancellous bone much less information on BMDD is available for cortical bone. Hence, we analyzed complete transiliac crest bone biopsy samples from premenopausal women (n = 73) aged 25-48 years, clinically classified as healthy, by quantitative backscattered electron imaging for cortical (Ct.) and cancellous (Cn.) BMDD. The Ct.BMDD was characterized by the arithmetic mean of the BMDD of the cortical plates. We found correlations between Ct. and Cn. BMDD variables with correlation coefficients r between 0.42 and 0.73 (all p < 0.001). Additionally to this synchronous behavior of cortical and cancellous compartments, we found that the heterogeneity of mineralization densities (Ct.Ca(Width)), as well as the cortical porosity (Ct.Po) was larger for a lower average degree of mineralization (Ct.Ca(Mean)). Moreover, Ct.Po correlated negatively with the percentage of highly mineralized bone areas (Ct.Ca(High)) and positively with the percentage of lowly mineralized bone areas (Ct.Ca(Low)). In conclusion, the correlation of cortical with cancellous BMDD in the iliac crest of the study cohort suggests coordinated regulation of bone turnover between both bone compartments. Only in a few cases, there was a difference in the degree of mineralization of >1wt % between both cortices suggesting a possible modeling situation. This normative dataset of healthy premenopausal women will provide a reference standard by which disease- and treatment-specific effects can be assessed at the level of cortical bone BMDD.

Maternal protective behavior of zebu type cattle (Bos indicus) and its association with temperament

The objective of the study was to evaluate the maternal protective behavior of zebu-type cattle (Bos indicus) and its association with temperament. A total of 40 cow-calf pairs raised under extensive conditions were randomly assigned to 1 of 4 groups (n = 10), which were evaluated at 30, 60, 90, and 120 d postpartum (dpp), respectively. Measures obtained were defense responses of cows protecting their calves assessed by categorizing the behavioral response of the dams during handling of their calves and chute exit score and facial hair whorl (HW) position as indirect measures associated with temperament. No association was found between protective behavior and exit score or HW measures (rs < 0.22 and 0.13, respectively; P > 0.05). At 30 dpp, 90% of the cows responded to the stimulus of calves being handled, 40% reacted exclusively to alien calves, and 50% responded to their own or alien calves. Sixty days later, the proportion of cows responding to alien calves decreased (P < 0.05) to 10%, and at 120 dpp, cows responding to any calf decreased (P < 0.05) to 20%, while the nonresponding cows increased (P < 0.05) to 60%. Similarly, as dpp increased, the intensity of the reaction of the cows to the manipulation of their calves declined. The intensity of the response was exacerbated (P < 0.05) when a human being was less than 1 m distance from the calf, also when the calf was its own or when the calf vocalized. Furthermore, independent of the sex of their own calf, cows reacted more to male than female calves (P < 0.05). It was concluded that zebu cows may display maternal protective behavior to their own or alien calves, which weakens about 120 dpp and is not influenced by individual temperament.

MutT Homolog 1 (MTH1) maintains multiple KRAS-driven pro-malignant pathways

Oncogenic RAS promotes production of reactive oxygen species (ROS), which mediate pro-malignant signaling but can also trigger DNA damage-induced tumor suppression. Thus RAS-driven tumor cells require redox-protective mechanisms to mitigate the damaging aspects of ROS. Here, we show that MutT Homolog 1 (MTH1), the mammalian 8-oxodGTPase that sanitizes oxidative damage in the nucleotide pool, is important for maintaining several KRAS-driven pro-malignant traits in a nonsmall cell lung carcinoma (NSCLC) model. MTH1 suppression in KRAS-mutant NSCLC cells impairs proliferation and xenograft tumor formation. Furthermore, MTH1 levels modulate KRAS-induced transformation of immortalized lung epithelial cells. MTH1 expression is upregulated by oncogenic KRAS and correlates positively with high KRAS levels in NSCLC human tumors. At a molecular level, in p53-competent KRAS-mutant cells, MTH1 loss provokes DNA damage and induction of oncogene-induced senescence. In p53-nonfunctional KRAS-mutant cells, MTH1 suppression does not produce DNA damage but reduces proliferation and leads to an adaptive decrease in KRAS expression levels. Thus, MTH1 not only enables evasion of oxidative DNA damage and its consequences, but can also function as a molecular rheostat for maintaining oncogene expression at optimal levels. Accordingly, our results indicate MTH1 is a novel and critical component of oncogenic KRAS-associated malignancy and its inhibition is likely to yield significant tumor-suppressive outcomes in KRAS-driven tumors.

Changes in weight and BMI following the diagnosis of type 1 diabetes in children and adolescents

The aim of this study was to study weight and body mass index (BMI) before, at, and after diagnosis of type 1 diabetes (T1D) and to identify factors associated with weight gain. Studied retrospectively were 209 children <18 years with T1D followed for 6 years. Data collected included clinical and laboratory data before diagnosis, at diagnosis, and during 6 years of follow-up. Anthropometric parameters of patients were compared along follow-up and with those of their parents and siblings. Mean BMI-standard deviation score (SDS) was below average at diagnosis (-0.66 ± 1.27), had increased to 0.37 ± 0.93 at 3 months, and decreased to a nadir at 6 months in females and 12 months in males; between 1 and 3 years, there was a slight increase and between 3 and 6 years a further increase only in the females. BMI-SDS at 6 years was significantly higher than pre-diabetes BMI-SDS (0.35 ± 0.83 vs. -0.04 ± 1.23, p < 0.001). Patients' BMI-SDS at 6 years was similar to that of their parents and siblings, was higher in the females (0.53 ± 0.74 vs. 0.27 ± 0.82, p = 0.02) and in those keeping diabetes a secret (0.66 ± 0.82 vs. 0.33 ± 0.78, p = 0.027), and was not associated with age or pubertal stage at diagnosis, ethnicity, or metabolic control. A longer duration of insulin pump therapy was associated with a lower BMI-SDS (r = -0.2375, p < 0.025). BMI-SDS increased during the 6 years following diagnosis of T1D in pediatric patients, especially in the females, but remained in the normal range and was similar to that of other family members.

Treatment retention among patients randomized to buprenorphine/naloxone compared to methadone in a multi-site trial

AIMS

To examine patient and medication characteristics associated with retention and continued illicit opioid use in methadone (MET) versus buprenorphine/naloxone (BUP) treatment for opioid dependence.

DESIGN, SETTINGS AND PARTICIPANTS

This secondary analysis included 1267 opioid-dependent individuals participating in nine opioid treatment programs between 2006 and 2009 and randomized to receive open-label BUP or MET for 24 weeks.

MEASUREMENTS

The analyses included measures of patient characteristics at baseline (demographics; use of alcohol, cigarettes and illicit drugs; self-rated mental and physical health), medication dose and urine drug screens during treatment, and treatment completion and days in treatment during the 24-week trial.

FINDINGS

The treatment completion rate was 74% for MET versus 46% for BUP (P < 0.01); the rate among MET participants increased to 80% when the maximum MET dose reached or exceeded 60 mg/day. With BUP, the completion rate increased linearly with higher doses, reaching 60% with doses of 30-32 mg/day. Of those remaining in treatment, positive opioid urine results were significantly lower [odds ratio (OR) = 0.63, 95% confidence interval (CI) = 0.52-0.76, P < 0.01] among BUP relative to MET participants during the first 9 weeks of treatment. Higher medication dose was related to lower opiate use, more so among BUP patients. A Cox proportional hazards model revealed factors associated with dropout: (i) BUP [versus MET, hazard ratio (HR) = 1.61, CI = 1.20-2.15], (ii) lower medication dose (<16 mg for BUP, <60 mg for MET; HR = 3.09, CI = 2.19-4.37), (iii) the interaction of dose and treatment condition (those with higher BUP dose were 1.04 times more likely to drop out than those with lower MET dose, and (iv) being younger, Hispanic and using heroin or other substances during treatment.

CONCLUSIONS

Provision of methadone appears to be associated with better retention in treatment for opioid dependence than buprenorphine, as does use of provision of higher doses of both medications. Provision of buprenorphine is associated with lower continued use of illicit opioids.

Aerobic exercise increases hippocampal volume and improves memory in multiple sclerosis: preliminary findings

Multiple sclerosis leads to prominent hippocampal atrophy, which is linked to memory deficits. Indeed, 50% of multiple sclerosis patients suffer memory impairment, with negative consequences for quality of life. There are currently no effective memory treatments for multiple sclerosis either pharmacological or behavioral. Aerobic exercise improves memory and promotes hippocampal neurogenesis in nonhuman animals. Here, we investigate the benefits of aerobic exercise in memory-impaired multiple sclerosis patients. Pilot data were collected from two ambulatory, memory-impaired multiple sclerosis participants randomized to non-aerobic (stretching) and aerobic (stationary cycling) conditions. The following baseline/follow-up measurements were taken: high-resolution MRI (neuroanatomical volumes), fMRI (functional connectivity), and memory assessment. Intervention was 30-minute sessions 3 times per week for 3 months. Aerobic exercise resulted in 16.5% increase in hippocampal volume and 53.7% increase in memory, as well as increased hippocampal resting-state functional connectivity. Improvements were specific, with no comparable changes in overall cerebral gray matter (+2.4%), non-hippocampal deep gray matter structures (thalamus, caudate: -4.0%), or in non-memory cognitive functioning (executive functions, processing speed, working memory: changes ranged from -11% to +4%). Non-aerobic exercise resulted in relatively no change in hippocampal volume (2.8%) or memory (0.0%), and no changes in hippocampal functional connectivity. This is the first evidence for aerobic exercise to increase hippocampal volume and connectivity and improve memory in multiple sclerosis. Aerobic exercise represents a cost-effective, widely available, natural, and self-administered treatment with no adverse side effects that may be the first effective memory treatment for multiple sclerosis patients.

Abstract OT3-2-02: PreOperative window of endocrine therapy provides information to increase compliance: POWER PIINC: A feasibility study

Background: The addition of systemic therapy to the surgical treatment of breast cancer has improved survival of patients. A mainstay of systemic therapy in the setting of hormone receptor positive breast cancer is endocrine therapy. Despite the known advantages, the compliance with short and long term systemic endocrine therapy is less than ideal. Several studies report significant rates of non-compliance with endocrine therapy, either in patients never starting the medication or not completing the recommended multi-year course. It is estimated that as many as 10% of patients per year discontinue their therapy. We wondered why women would forgo such an important part of their treatment and how we might intervene to improve compliance. Using information gleaned from POWER PIINC, we hope to design a behavioral intervention study to see if the patient knowing her tumor's preoperative response to endocrine therapy will improve long term compliance. In order to do such a study we would need to define the minimal length of preoperative endocrine therapy needed to detect measurable changes in the tumor.

After 14 days of endocrine therapy, significant decreases in Ki67 can be seen in most hormone sensitive breast cancers. In fact two current studies are using this information (POETIC and ADAPT trials). Both of these trials are being conducted outside of the U.S. where operative therapy does not typically occur within a week or two of seeing the surgeon. POWER PIINC is a feasibility study to determine if we can detect changes in Ki67 with only 7 days of therapy. The results of POWER PIINC will inform the behavioral intervention trial.

Trial Design: This is a prospective, single-arm feasibility study. Participants take tamoxifen for 7 days prior to surgery. Ki67 is measured pre (core biopsy) and post (surgical specimen) tamoxifen.

Eligibility critieria: Non-pregnant women age 18 or older with a hormone positive (&gt;1% ER or PR) clinical Stage 1 or 2 breast cancer who are candidates for surgical therapy of their breast cancer. No concurrent CYP2D6 inhibitors or other contraindications to tamoxifen.

Specific Aims:

Primary Objective:

Demonstrate a significant reduction in Ki67 expression in tumors with 7 days of pre-surgical tamoxifen.

Secondary Objectives:

- Evaluate symptom patterns from baseline through 18 months of follow-up (presence, severity, and bother)

-Evaluate 18-month endocrine therapy adherence

-Evaluate change in attitude regarding endocrine therapy

-Evaluate correlation between changes in Ki67 expression and symptom scores

-Evaluate additional changes in proliferative markers (subset of PAM 50)

Statistical Methods: A one-sample t-test will be applied to the log-ratio of Ki67 at resection to pre therapy. If this ratio is not normally distributed we will use a non-parametric Wilcoxon test. Secondary objectives will be analyzed using a variety of appropriate statistical tests.

Accrual: Target accrual is 52 patients over 18 months. We opened this study in August of 2012. To date (9 months) we have accrued 23 patients.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-2-02.

Improved retrieval of PM2.5 from satellite data products using non-linear methods

Satellite observations may improve the areal coverage of particulate matter (PM) air quality data that nowadays is based on surface measurements. Three statistical methods for retrieving daily PM2.5 concentrations from satellite products (MODIS-AOD, OMI-AAI) over the San Joaquin Valley (CA) are compared--Linear Regression (LR), Generalized Additive Models (GAM), and Multivariate Adaptive Regression Splines (MARS). Simple LRs show poor correlations in the western USA (R(2) ~/= 0.2). Both GAM and MARS were found to perform better than the simple LRs, with a slight advantage to the MARS over the GAM (R(2) = 0.71 and R(2) = 0.61, respectively). Since MARS is also characterized by a better computational efficiency than GAM, it can be used for improving PM2.5 retrievals from satellite aerosol products. Reliable PM2.5 retrievals can fill in missing surface measurements in areas with sparse ground monitoring coverage and be used for evaluating air quality models and as exposure metrics in epidemiological studies.

Odontostomatological aspects in patients with Goldenhar syndrome: a series of 9 patients

The authors observed and followed nine patients with Goldenhar syndrome to identify the variability and severity malformations mainly affecting the orofacial district, but also other systems. Considering the severity of the lesions and the affected organs and tissues, the authors report preventive and therapeutic approaches, which present considerable difficulties in timing and quality of interventions.

Breakage and Buckling of Fibrous Reinforcements During Fabrication of Thermoplastic Matrix Composites

The paper addresses the buckling of fibrous reinforcements which occurs due to motion of the amorphous matrix material during solidification. The motion of the matrix material is caused by a variation in cooling rate in different portions of a composite while the sample is cooling. In the course of this study, samples were prepared with a fiber reinforcement sandwiched between premolded sheets of polycarbonate. Samples were either processed in a two-cavity, “dogbone” shape mold or in a rectangular, single-cavity mold matched die compression mold. In order to visualize the motion of the molten matrix material, strands of polycarbonate blended with carbon black were mounted into the matrix. The buckling behavior demonstrated sensitivity, to the amount of reinforcement observed with single and multiple filaments of carbon and Kevlar and bundles of carbon fiber tows. This paper provides scaling considerations indicating the sensitivity of the observed effects to processing conditions and concludes with a discussion of the implications for load carrying capabilities of composites.

Material and Numerical Aspects of Mathematical Modeling of Blow Molding**

The work describes an approach to simulation of a blow molding process. The development originated from the need to reduce the amount of experimentation through a screening of processing conditions and preform configurations. The simulation uses a standard finite element software capable of handling large deformations and an interaction with rigid surfaces, which are encountered in blow molding. The developed constitutive equation for a general purpose polystyrene in the rubbery state was incorporated into the model. Temperature and rate dependencies, typical for plastic materials, are accounted for in this model. The application of the developed model for analysis of the preform's deformations is illustrated here on a number of examples.

Buprenorphine/Naloxone and methadone effects on laboratory indices of liver health: a randomized trial

BACKGROUND

Buprenorphine/naloxone (BUP) and methadone (MET) are efficacious treatments for opioid dependence, although concerns about a link between BUP and drug-induced hepatitis have been raised. This study compares the effects of BUP and MET on liver health in opioid-dependent participants.

METHODS

This was a randomized controlled trial of 1269 opioid-dependent participants seeking treatment at 8 federally licensed opioid treatment programs and followed for up to 32 weeks between May 2006 and August 2010; 731 participants met "evaluable" criteria defined as completing 24 weeks of medication and providing at least 4 blood samples for transaminase testing. Participants were randomly assigned to receive BUP or MET for 24 weeks. Shift table analysis determined how many evaluable participants moved between categories of low and elevated transaminase levels. Predictors of moving from low to high transaminase levels were identified.

RESULTS

Changes in transaminase levels did not differ by medication condition. Baseline infection with hepatitis C or B was the only significant predictor of moving from low to elevated transaminase levels; 9 BUP and 15 MET participants showed extreme liver test elevations and were more likely than those without extreme elevations to have seroconverted to both hepatitis B and C during the study, or to use illicit drugs during the first 8 weeks of treatment. MET participants were retained longer in treatment than BUP participants.

CONCLUSIONS

This study demonstrated no evidence of liver damage during the initial 6 months of treatment in either condition. Physicians can prescribe either medication without major concern for liver injury.