Causal inference with confounders missing not at random

It is important to draw causal inference from observational studies, but this becomes challenging if the confounders have missing values. Generally, causal effects are not identifiable if the confounders are missing not at random. In this article we propose a novel framework for nonparametric identification of causal effects with confounders subject to an outcome-independent missingness, which means that the missing data mechanism is independent of the outcome, given the treatment and possibly missing confounders. We then propose a nonparametric two-stage least squares estimator and a parametric estimator for causal effects.

Correlations of SCN5A gene polymorphisms with onset of atrial fibrillation

OBJECTIVE

The aim of this study was to analyze the correlations of the sodium channel, voltage-gated, type V, alpha subunit (SCN5A) gene polymorphisms with the onset of atrial fibrillation (AF), and its clinical significance.

PATIENTS AND METHODS

The quantitative Real Time-Polymerase Chain Reaction (QRT-PCR) amplification and the TaqMan analysis were utilized to analyze the composition of SCN5A genotypes and alleles in the peripheral blood mononuclear cells of 48 normal controls and 115 AF patients. Meanwhile, the differences in single nucleotide polymorphisms (SNPs), 1673 A>G, and 3666+69 G>C, between the AF group and the control group were analyzed using the χ2-test. The high-risk factors influencing the AF attack were analyzed via logistic regression analysis, as well as univariate and multivariate analyses. In addition, the correlations of gene polymorphisms with high-risk factors (drinking and hypertension) for AF were verified by the χ2-test.

RESULTS

There were statistically significant differences in the incidence rate of hypertension, the times of smoking and drinking, and the frequencies of palpitation and syncope between the AF group and the control group (p<0.05). The composition of genotypes and alleles of 1673 A>G and 3666+69 G>C in the AF group was significantly different from that of the control group (p<0.05). According to the results of the logistic regression analysis, as well as the univariate and multivariate analyses, drinking, and hypertension were associated with the occurrence of AF (p<0.05). Furthermore, statistically significant differences were observed in the composition of the gene polymorphisms 1673 A>G and 3666+69 G>C between patients with and without histories of drinking and hypertension (p<0.05).

CONCLUSIONS

There are significant differences in SCN5A gene polymorphisms 1673 A>G and 3666+69 G>C between AF patients and normal controls. Moreover, drinking and hypertension can influence the changes in the gene polymorphisms.

[Analysis of the arthropathies on no-bleeding history joints in pre-school age severe hemophilia A children]

Objective: To detect the arthropathies on no bleeding history joints in pre-school hemophilia A children in order to provide evidence for further prevention and control of joint disease in children with hemophilia A. Methods: This study was a cross-sectional study based on China Hemophilia Individualized prophylaxis study (CHIPS). The basic data of outpatients with hemophilia in Beijing Children's Hospital and Chengdu Women's and Children's Central Hospital between August 2016 and June 2017 were collected and a three-month follow-up was conducted. The target joints (six joints of bilateral elbows, knees and ankles) of thirty-four children aged 1-7 years old with severe hemophilia A were examined by ultrasound, X-ray and joint function examination (4-7 years old, hemophilia joint health score (HJHS)). To find out whether there are arthropathies in patient's joints with no bleeding history and analyze the relevant factors by chi-square test, rank sum test and other statistical methods. Results: There were 32 analyzable cases with 112 no-bleeding history target joints, 42.9% (48/112) were elbow joints. Arthropathies were revealed in 34.8% (39/112) of them by joint structural and functional examination and 46.2% (18/39) were ankles (χ(2)=8.379, P=0.015) . Ultrasound showed abnormalities in 18.3% (20/109) joints, X-ray showed abnormalities in 3.8% (3/79) joints and HJHS showed abnormalities in 25.3% (20/79) joints. There was no correlation between ultrasound and HJHS (r=0.015, P=0.895), no correlation was found between X-ray and HJHS (r=-0.101, P=0.390) either, which suggested that joint structural and functional examination could not replace each other. The related risk factors of arthropathies in this group were >4.91 years old (OR=3.917, 95%CI:1.610-9.528) and combining with target joint (OR=3.530, 95%CI:1.316-9.465). Conclusions: Detecting the joint structure and function on no bleeding history joints in pre-school hemophilia A children could reveal the arthropathies and majority of them were ankle arthropathies. Joint structural and functional examinations could not replace each other. For patients more than 5 years old and those with target joints, the joints with no complaint of bleeding should be examined regularly to reveal the arthropathies in time.

[Drug resistance mutations and its associated factors among 579 HIV/AIDS patients experiencing failure of antiretroviral therapy in Jiangsu Province, China]

Objective: To understand the incidence and related factors of HIV-1 drug resistance among HIV/AIDS patients experiencing treatment failure in Jiangsu province, China. Methods: The HIV/AIDS integrated prevention and control data information management system of China were used to collect the basic data of patients, blood specimens were collected from patients who had antiretroviral therapy (ART) failure with ≥12 months and older than 18 years in 2016 in Jiangsu, excluding cases with missing information, 713 cases were enrolled in this study. HIV-1 RNA was extracted, and then pol gene region was amplified and sequenced. The obtain sequences were submitted to Stanford University HIV Drug Resistance Database to interpret and analyse HIV-1 drug resistance and sub-types. Multivariate logistic regression model was used to explore the related factors of drug resistance. Results: A total of 579 subjects were amplified successfully, male accounted for 85.66% (496 cases), and the median age was 39 years old. The main route of infection was sexual transmission (553 cases, 95.51%). A total of 331 patients with drug resistance gene mutation were detected, drug resistance mutation rate was 57.18%. Compared with patients with baseline CD4(+)T cell count >500 cells/μl, patients with CD4(+)T cell count in 201-500 cells/mm(3) and ≤200 cells/μl had a higher incidence of genetic drug resistance, the odds ratio was 3.33 and 6.87, respectively. Compared with patients with treatment less than 24 months, patients treated for 25-48 months had a higher incidence of drug resistance, the odds ratio was 1.88. Compared with patients infected by CRF07_BC strains, patients infected by CRF01_AE strains were associated with higher incidence of drug resistance, the odds ratio was 2.22 and 3.32, respectively. Protease inhibitor (PI) resistance mutations, nucleoside reverse transcriptase inhibitor (NRTI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) were found in 3.80%, 33.16% and 53.37% of patients, respectively. 31.95% of patients harbored NRTI and NNRTI resistance mutations simultaneously. M184V/I and K103N/Q were the highest frequency of NRTI and NNRTI resistance mutation, the prevalence of M184V/I and K103N/Q were 28.15% and 22.28%, respectively. Conclusion: The status of HIV-1 drug resistance mutations are complex and diverse among patients experiencing failure of ART in Jiangsu. Patients with lower baseline CD4(+)T cell count, longer treatment time and HIV-1 CRF01_AE and B strains infection were associated with higher incidence of drug resistance mutation.

Sirt1 mediates improvement in cognitive defects induced by focal cerebral ischemia following hyperbaric oxygen preconditioning in rats

Hyperbaric oxygen preconditioning (HBO-PC) has been proposed as a safe and practical approach for neuroprotection in ischemic stroke. However, it is not known whether HPO-PC can improve cognitive deficits induced by cerebral ischemia, and the mechanistic basis for any beneficial effects remains unclear. We addressed this in the present study using rats subjected to middle cerebral artery occlusion (MCAO) as an ischemic stroke model following HBO-PC. Cognitive function and expression of phosphorylated neurofilament heavy polypeptide (pNF-H) and doublecortin (DCX) in the hippocampus were evaluated 14 days after reperfusion and after short interfering RNA-mediated knockdown of sirtuin1 (Sirt1). HBO-PC increased pNF-H and DCX expression and mitigated cognitive deficits in MCAO rats. However, these effects were abolished by Sirt1 knockdown. Our results suggest that HBO-PC can protect the brain from injury caused by ischemia-reperfusion and that Sirt1 is a potential molecular target for therapeutic approaches designed to minimize cognitive deficits caused by cerebral ischemia.

Ta2O5-TiO2 Composite Charge-trapping Dielectric for the Application of the Nonvolatile Memory

The charge-trapping memory devices with a structure Pt/Al₂O₃/(Ta₂O₅) _x (TiO₂) _1-x /Al₂O₃/p-Si (x = 0.9, 0.75, 0.5, 0.25) were fabricated by using rf-sputtering and atomic layer deposition techniques. A special band alignment between (Ta₂O₅) _x (TiO₂) _1-x and Si substrate was designed to enhance the memory performance by controlling the composition and dielectric constant of the charge-trapping layer and reducing the difference of the potentials at the bottom of the conduction band between (Ta₂O₅) _x (TiO₂) _1-x and Si substrate. The memory device with a composite charge storage layer (Ta₂O₅) _0.5 (TiO₂) _0.5 shows a density of trapped charges 3.84 × 10¹³/cm² at ± 12 V, a programming/erasing speed of 1 µs at ± 10 V, a 8% degradation of the memory window at ± 10 V after 10⁴ programming/erasing cycles and a 32% losing of trapped charges after ten years. The difference among the activation energies of the trapped electrons in (Ta₂O₅) _x (TiO₂) _1-x CTM devices indicates that the retention characteristics are dominated by the difference of energy level for the trap sites in each TTO CTM device.

Instrumental variables as bias amplifiers with general outcome and confounding

Drawing causal inference with observational studies is the central pillar of many disciplines. One sufficient condition for identifying the causal effect is that the treatment-outcome relationship is unconfounded conditional on the observed covariates. It is often believed that the more covariates we condition on, the more plausible this unconfoundedness assumption is. This belief has had a huge impact on practical causal inference, suggesting that we should adjust for all pretreatment covariates. However, when there is unmeasured confounding between the treatment and outcome, estimators adjusting for some pretreatment covariate might have greater bias than estimators without adjusting for this covariate. This kind of covariate is called a bias amplifier, and includes instrumental variables that are independent of the confounder, and affect the outcome only through the treatment. Previously, theoretical results for this phenomenon have been established only for linear models. We fill in this gap in the literature by providing a general theory, showing that this phenomenon happens under a wide class of models satisfying certain monotonicity assumptions. We further show that when the treatment follows an additive or multiplicative model conditional on the instrumental variable and the confounder, these monotonicity assumptions can be interpreted as the signs of the arrows of the causal diagrams.

Measurement of the Neutrino Mixing Angle θ_{23} in NOvA

This Letter reports new results on muon neutrino disappearance from NOvA, using a 14 kton detector equivalent exposure of 6.05×10^{20} protons on target from the NuMI beam at the Fermi National Accelerator Laboratory. The measurement probes the muon-tau symmetry hypothesis that requires maximal θ_{23} mixing (θ_{23}=π/4). Assuming the normal mass hierarchy, we find Δm_{32}^{2}=(2.67±0.11)×10^{-3}  eV^{2} and sin^{2}θ_{23} at the two statistically degenerate values 0.404_{-0.022}^{+0.030} and 0.624_{-0.030}^{+0.022}, both at the 68% confidence level. Our data disfavor the maximal mixing scenario with 2.6σ significance.

A novel FOXM1 isoform, FOXM1D, promotes epithelial-mesenchymal transition and metastasis through ROCKs activation in colorectal cancer

Epithelial-mesenchymal transition (EMT) is a critical event in metastasis of colorectal cancer (CRC). Rho/ROCKs signaling has a pivotal role in orchestrating actin cytoskeleton, leading to EMT and cancer invasion. However, the underlying mechanisms for ROCKs activation are not fully understood. Here, we identified FOXM1D, a novel isoform of Forkhead box M1 (FOXM1) that has a pivotal role in ROCKs activation by directly interacting with coiled-coil region of ROCK2. FOXM1D overexpression significantly polymerizes actin assembly and impairs E-cadherin expression, resulting in EMT and metastasis in xenograft mouse model and knockdown of FOXM1D has the opposite effect. Moreover, a high FOXM1D level correlates closely with clinical CRC metastasis. FOXM1D-induced ROCKs activation could be abrogated by the ROCKs inhibitors Y-27632 and fasudil. These observations indicate that the FOXM1D-ROCK2 interaction is crucial for Rho/ROCKs signaling and provide novel insight into actin cytoskeleton regulation and therapeutic potential for CRC metastasis.

[Clinical results of transepithelial corneal collagen cross-linking in the treatment of keratoconus]

OBJECTIVE

To evaluate the effect of transepithelial corneal collagen cross-linking (CXL) in the treatment of keratoconus.

METHODS

Prospective study. Sixteen eyes of 16 patients with keratoconus underwent transepithelial CXL, and the fellow eyes were considered as the controls. The mean age was (22.4±6.5) years old. In the CXL group, topical anesthesia (0.1% tetracaine) was given for 15 minutes, and 0.5% riboflavin was applied until saturated in the anterior chamber. Then an ultraviolet A irradiance of 3 mW/cm(2) on the cornea was performed for 30 minutes. Postoperative corneal reepithelization time was recorded. Preoperative and postoperative examinations included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error, topography, corneal biomechanical parameters, thinnest corneal thickness, and endothelial cell density.

RESULTS

The mean corneal reepithelization time was 1.0(1.0 to 2.0) days. In the transepithelial CXL group, at the end of the 12-month follow-up, CDVA and refractive outcomes were significantly improved (P<0.05). Maximum K-value, anterior and posterior elevations were significantly decreased by (-2.23 ± 2.82)D (t=-3.153, P=0.007), (-4.69 ± 4.99) μm (t=-3.758, P=0.002), and (-13.94 ± 25.81) μm (t=-2.160, P=0.047), respectively. Corneal hysteresis, corneal resistance factor, thinnest corneal thickness, and endothelial cell density showed no significant difference (P>0.05). The differences in the changes of UDVA, CDVA, spherical equivalent refraction, and maximum K-value between the CXL and control groups were significant at 12 months (P<0.05).

CONCLUSION

Transepithelial CXL is effective in optimizing the irregular corneal surface of keratoconus, and might halt its progression. (Chin J Ophthalmol, 2016, 52: 525-530).

[Modified Chevron osteotomy combined distal soft tissue reconstruction to treat high-grade bunionette deformity]

OBJECTIVE

To explore the surgical method of using the modified chevron osteotomy combined distal soft tissue reconstruction to treat high-grade bunionette deformity.

METHODS

From June 2013 to June 2015, the modified chevron osteotomy combined distal soft tissue reconstruction was used for surgical treatment of high-grade bunionette deformity in the Department of Hand and Foot Microsurgery in Xuzhou Central Hospital.Twenty-six patients with 28 feet high-grade bunionette deformity were hospitalized for treatment, with 3 male (3 feet) and 23 female (25 feet) cases, aged 22-73 (mean 47.1) years old.The average fourth-fifth intermetatarsal angle, lateral deviation of the fifth metatarsal angle and metatarsophalangeal-fifth angle were measured on the pre-and post- operative anterior to posterior weight-beating X rays of treated feet.The American Orthopaedic Foot and Ankle Society (AOFAS) Lesser Toe Metatarsophalangeal-Interphalangeal Scale was used to evaluate the post-operative outcomes.

RESULTS

All of 26 patients were followed, with a mean 15.7 months (range 8-25 months). Primarily healing of the wound was achieved in all cases.No postoperative infection and nonunion on the osteotomy site was found during the follow-up time.The fracture healing time was 6-15 (mean 12.2) weeks.All the patients had satisfactory appearance and sensory function without callosum and metastatic metatarsalgia at the final follow-up.The post-operative fourth-fifth intermetatarsal angle, lateral deviation of the fifth metatarsal angle and metatarsophalangeal-fifth angle were significantly lesser than the pre-operative at the 6th week after operation, respectively [(5.5±1.7)°, (2.1±0.8)°, (5.7±2.6)°vs (16.4±4.2)°, (6.0±2.2)°, (10.5±7.4)°; all P<0.01]. The post-operative AOFAS score was significantly greater than the pre-operative [(87.1±6.7) vs (62.3±9.8) points, P<0.001].

CONCLUSION

The modified chevron osteotomy combined distal soft tissue reconstruction is a safe and easy treatment option for the high-grade bunionette deformity and provides patient satisfaction results.

Population genetic structure of critically endangered salamander (Hynobius amjiensis) in China: recommendations for conservation

Amji's salamander (Hynobius amjiensis) is a critically endangered species (IUCN Red List), which is endemic to mainland China. In the present study, five haplotypes were genotyped for the mtDNA cyt b gene in 45 specimens from three populations. Relatively low levels of haplotype diversity (h = 0.524) and nucleotide diversity (π = 0.00532) were detected. Analyses of the phylogenic structure of H. amjiensis showed no evidence of major geographic partitions or substantial barriers to historical gene flow throughout the species' range. Two major phylogenetic haplotype groups were revealed, and were estimated to have diverged about 1.262 million years ago. Mismatch distribution analysis, neutrality tests, and Bayesian skyline plots revealed no evidence of dramatic changes in the effective population size. According to the SAMOVA and STRUCTURE analyses, H. amjiensis should be regarded as two different management units.

First Measurement of Electron Neutrino Appearance in NOvA

We report results from the first search for ν_{μ}→ν_{e} transitions by the NOvA experiment. In an exposure equivalent to 2.74×10^{20} protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99±0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07±0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π<δ_{CP}<0.5π in the inverted mass hierarchy at the 90% C.L.

Prognostic value of clinical and immunological markers in acute phase of SFTS virus infection

SFTS virus (SFTSV) is a novel bunyavirus that causes severe fever with thrombocytopenia syndrome (SFTS), an emerging infectious disease that occurred in China in recent years, with an average case fatality rate of 10-12%. Intervention in the early clinical stage is the most effective measure to reduce the mortality rate of disease. To elucidate the natural course of and immune mechanisms associated with the pathogenesis of SFTSV, 59 laboratory-confirmed SFTS patients in the acute phase, who were hospitalized between October 2010 and September 2011, were enrolled in this study, and the patients sera were dynamically collected and tested for SFTSV viral RNA load, 34 cytokines or chemokines and other related laboratory parameters. All clinical diagnostic factors in the acute phase of SFTS were evaluated and assessed. The study showed that the severity of the disease in 11 (18.6%) patients was associated with abdominal pain (p 0.007; OR = 21.95; 95% CI, 2.32-208.11) and gingival bleeding (p 0.001; OR=122.11; 95% CI, 6.41-2328). The IP-10, TNF-α, IL-6, IL-10, granzyme B and HSP70 levels were higher over the 7-8 days in severe cases, accompanied by altered AST, CK and LDH levels. HSP70 (p 0.012; OR=8.29; 95% CI, 1.58-43.40) was independently correlated with the severity of the early acute phase of SFTSV infection. The severity of SFTS can be predicted based on the presence of symptoms such as abdominal pain and gingival bleeding and on the level of HSP70 in the acute phase of the disease.