Multiple Comparison Methods Research Articles

Comments on Statistical Issues in September 2013

In this section, we explain the multiple comparison methods when there are more than two group means to be compared, which appeared in the article titled, Effect of alcohol consumption on risk of hyperhomocysteinemia based on alcohol-related facial flushing response, published in July 2013 by Kim et al.1)

Cost-Effectiveness of Infliximab for the Treatment of Acute Exacerbations of Ulcerative Colitis in the Netherlands.

IntroductionInfliximab is registered for the treatment of moderate-to-severe active ulcerative colitis (UC) adult patients who have had an inadequate response, or are intolerant, or have medical contraindications to therapy including corticosteroids and 5-aminosalicylates or thiopurines (6-mercaptopurine [6-MP] or azathioprine [AZA]). The authors estimate the costs and effects and evaluate the cost-effectiveness of infliximab at the licensed dose of 5 mg/kg versus cyclosporine or surgery for the treatment of adult Dutch patients hospitalized with acute exacerbations of UC, refractory to intravenous steroids.MethodAn existing decision analytical model was updated to simulate disease progression of hospitalized UC patients in the Netherlands, refractory to intravenous corticosteroids, and to estimate the costs and benefits associated with infliximab compared to cyclosporine and surgery over a 1-year time horizon. Colectomy rates were derived from infliximab and cyclosporine randomized trials and synthesized using multiple treatment comparison methods. The utility estimates associated with health states of ulcerative colitis patients were obtained from the literature. Resource use and drug use frequencies as well as unit costs were obtained from Dutch sources. The primary effectiveness measure used in the analysis was quality-adjusted life years (QALYs).ResultsFor a typical UC patient with body weight of 70 kg, the costs of treatment with infliximab, cyclosporine, and surgery over a 1-year treatment period were €17,062, €14,784, €13,979, respectively. The associated numbers of QALYs were 0.80, 0.70, and 0.58 for infliximab, cyclosporine, and surgery respectively. The incremental cost-effectiveness ratio for infliximab was €24,277 per QALY gained compared to cyclosporine, and €14,639 per QALY gained compared to surgery.ConclusionsInfliximab induction regimen appears to be a cost-effective treatment option in comparison to cyclosporine and surgery for hospitalized patients with acute exacerbations of UC, refractory to intravenous corticosteroids in the Netherlands.

Analyzing genotype-by-environment interaction using curvilinear regression

In the context of multi-environment trials, where a series of experiments is conducted across different environmental conditions, the analysis of the structure of genotype-by-environment interaction is an important topic. This paper presents a generalization of the joint regression analysis for the cases where the response (e.g. yield) is not linear across environments and can be written as a second (or higher) order polynomial or another non-linear function. After identifying the common form regression function for all genotypes, we propose a selection procedure based on the adaptation of two tests: (i) a test for parallelism of regression curves; and (ii) a test of coincidence for those regressions. When the hypothesis of parallelism is rejected, subgroups of genotypes where the responses are parallel (or coincident) should be identified. The use of the Scheffe multiple comparison method for regression coefficients in second-order polynomials allows to group the genotypes in two types of groups: one with upward-facing concavity (i.e. potential yield growth), and the other with downward-facing concavity (i.e. the yield approaches saturation). Theoretical results for genotype comparison and genotype selection are illustrated with an example of yield from a non-orthogonal series of experiments with winter rye (Secalecereale L.). We have deleted 10 % of that data at random to show that our meteorology is fully applicable to incomplete data sets, often observed in multi-environment trials.

Temporal occurrence of retinal detachments after cataract surgery

To characterize the temporal occurrence of retinal detachments (RD) after cataract surgery. In this retrospective, consecutive case series, we reviewed the charts of 798 pseudophakic patients with primary rhegmatogenous RD that underwent surgery between 1999 and 2009, at the Center of Ophthalmology, University of Cologne, Germany. Twenty-five percent of all pseudophakic RDs occurred within 1 year after cataract surgery, 50% within 3.2 years and 90% within 9.9 years. Risk was increased for at least 11 years. The time interval was significantly shorter in vitrectomized eyes (2.49 versus 4.31 years, p = 0.016). Women showed a statistical trend towards longer time intervals (4.72 versus 3.93 years, p = 0.052), whereas myopic patients and different age groups showed no significant difference. After cataract surgery, the risk for RD was highest in the beginning and decreased continuously over time. However, the risk was increased for at least 11 years. Therefore, most studies have underestimated the incidence of RD after cataract surgery.

Nigeria’s Oilboom Period (1973-1983): Was Agriculture Really Neglected?

Over the years several authors have attributed the decline in Nigerian agricultural production to the neglect of the agricultural sector that resulted from the discovery of crude oil, what is known as the oilboom factor. This paper set out to find answer to the question: was agriculture really neglected as a result of the oilboom? The study took a historical perspective to trace the path of capital expenditure allocations to the agricultural sector in Nigeria. Secondary data on planned capital expenditure allocation to the agriculture sector before and during the oilboom period; and the budget estimates of capital expenditure allocations to the Agriculture, Water Resources, Health, Education and Defence sectors in Nigeria during the oil boom period 1977-1983 were sourced and used. Graphic descriptive statistics and the one-way analysis of variance technique were used to achieve the objectives of the study. The Tukey’s Multiple Comparison method w as employed to determine which mean(s) differ, in both cases, in the one-way analysis of variance tests conducted. The empirical findings of the study indicate significant increase in the quantity of capital expenditure allocation to the agriculture sector during the oilboom period; and that more capital expenditure was allocated to the agriculture sector than was allocated to either of Health, Education or Defence sectors in Nigeria during the oilboom period. Thus, it concluded that the decline in agricultural production in Nigeria was, statistically, not attributable to the neglect of the agricultural sector resulting from oil boom. The reason could be as a manifestation of Dutch Disease, Natural Resource Curse, Rent Seeking phenomenom, or something else.

P164 Evaluation of pro-inflammatory cytokines, and cell growth inhibition in primary human cells culture from oral tissue treated with uretandimethacrylate (UDMA)

Introduction Dental endodontic sealers are in intimate contact with tissues around the root apex for extended periods. New endodontic sealers have been developed in the past decade, but the biological responses to many new products are not well documented.After exposure to endodontic sealer based on Uretandimethacrylate (UDMA) in ex vivo expanded human dental pulp mesenchymal stem cells (DP-MSCs), human periodontal ligament mesenchymal stem cells (PDL-MSCs), human osteoblasts (HOSTs) and human gingival fibroblasts (HGF) were evaluated: morphological features and cells growth. Moreover, the secretion of pro-inflammatory cytokines as: interleukin-1 Beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), interleukin-12 (IL-12), tumor necrosis factor-Alpha (TNF-α) at 24 h of UDMA treatment was assessed. Methods DP-MSCs and PDL-MSCs were derived from the dental pulps and the periodontal ligament of 10 young donors. HGF was derived from gingival biopsy. HOSTs were derived from maxilla periosteum. After in vitro isolation, DP-MSCs, PDL-MSCs, HGF and HOSTs were treated with UDMA, and after 24, 48 and 72 h and 1 week of incubation, their morphological features were analysed by light and confocal microscopy. To evaluate the, cell growth an MTT assay was performed. The release of IL-1β, IL-6, IL-8, IL-10, IL-12, TNF-alpha was analysed by ELISA test. Differences in the cell growth and in the interleukin secretion were analysed for statistical significance with two-way anova tests and the Holm-Sidak method for multiple comparisons. Results The UDMA treatment induces a cells growth inhibition in all the different analysed cells line. At microscopic level the cells don’t showed morphological changes, in fact the fibroblastoid features with cytoplasmic processes was observable. An up-regulation of IL-6 IL-8 and TNF-α was present in DP-MSCs, PDL-MSCs, HOSTs and HGF at 24 h of treatment. On the contrary IL-12 was over-expressed only in the PDL-MSCs, while the IL-1β in the DP-MSCs. Conclusion This work shows endodontic sealers may alter the cell growth, and in treated samples to induce an up-regulation of soluble mediators of inflammation such as IL-6, IL-8 and TNF-α cytokines. The direct application of UDMA potentially induces an inflammation process that could be the starting point for toxic response and cell damage in DP-MSCs, PDL-MSCs, HGF and HOSTs.

P024 LPS-P. gingivalis stimulate interleukin-6, −8 and CCL-20 release, and NF-kB translocation in human periodontal ligament mesenchymal stem cells

Introduction Periodontal diseases are clinically characterized by inflammation of the periodontal connective tissue that ultimately induces the destruction of periodontal tissue and the loss of alveolar bone. In chronic periodontitis, the anaerobic gram-negative bacterium Porphyromonas gingivalis (P. gingivalis) is implicated. The pathogenicity of P. gingivalis is exerted by a wide variety of factors, among which the lipopolysaccharides (LPSs). In this study, the expression of TLR-4, the cell growth, the cytokines release, and the nuclear factor-KB (NF-kB) transcription factor expression in response to LPS-P.Gingivalis (LPS-G) were examined in Human Periodontal Ligament Mesenchymal Stem Cells (PDL-MSCs). In this study, to understand the role and the response to LPS-G we examined cell growth, the IL-6, IL-8 and CCL-20 release and the NF-kB signaling pathway in periodontal stem cells. Methods PDL-MSCs were derived from the periodontal ligament of 10 young donors. After in vitro isolation, PDL-MSCs were incubated in the absence (controls) or presence of 5 μg/mL of LPS from P. gingivalis and after 12, 24, 48, and 7 h of incubation, their morphological features were analysed by light and confocal microscopy. PDL-MSCs were characterized by flow cytometry using against TRL-4 PE-conjugated monoclonal antibody.To evaluate the cell growth an MTT assay was performed. The release of IL-6, IL-8, and CCL-20 was analysed by ELISA test. Differences in the cell growth and in the interleukin secretion were analysed for statistical significance with two-way anova tests and the Holm-Sidak method for multiple comparisons. Results In basal conditions, human PDL-MSCs express high levels of TLR-4. In inflammatory conditions mimicked by LPS-Gchallenge, the MTT assay carried out at different treatment times evidenced the decrease of the cell growth. Moreover, the recognition of P. gingivalis components by TLR-4 culminated with the activation of secretion of inflammatory mediators such as: IL-6, IL-8 and CCL-20, and with the up-regulation of NF-kB, which was translocated into the nucleus. Our data intended to specify that TLR-4 expressed by PDL-MSCs is functional and plays a key role in inflammation. Conclusion The data obtained evidenced that the periodontal stem cells express a functional TLR-4 receptor, and the binding of LPS receptor activates the NF-kB signaling pathways. In fact, an increased level of expression and a nuclear translocation of the transcription factor is evident in treated cells. Moreover, a substantial increase of pro-inflammation cytokines IL-6 and IL-8 and CCL-20 chemokine production is visible after 24 h of stimulation with 5μg/ml LPS.In synthesis, our cells model seems to be a valuable tool for the evaluation of the response of stem cells to LPS-G, compounds that almost certainly are responsible for influencing the periodontal diseases. The distinct ability of the periodontal ligament cells to secrete IL-6, IL-8 and CCL-20 emphasizes that these cells may contribute to the release of cytokines in LPS-challenged periodontium and offer the opportunity to better comprehend the degenerative processes in periodontal diseases.

Progressive structure-based alignment of homologous proteins: Adopting sequence comparison strategies

Comparison of multiple protein structures has a broad range of applications in the analysis of protein structure, function and evolution. Multiple structure alignment tools (MSTAs) are necessary to obtain a simultaneous comparison of a family of related folds. In this study, we have developed a method for multiple structure comparison largely based on sequence alignment techniques. A widely used Structural Alphabet named Protein Blocks (PBs) was used to transform the information on 3D protein backbone conformation as a 1D sequence string. A progressive alignment strategy similar to CLUSTALW was adopted for multiple PB sequence alignment (mulPBA). Highly similar stretches identified by the pairwise alignments are given higher weights during the alignment. The residue equivalences from PB based alignments are used to obtain a three dimensional fit of the structures followed by an iterative refinement of the structural superposition. Systematic comparisons using benchmark datasets of MSTAs underlines that the alignment quality is better than MULTIPROT, MUSTANG and the alignments in HOMSTRAD, in more than 85% of the cases. Comparison with other rigid-body and flexible MSTAs also indicate that mulPBA alignments are superior to most of the rigid-body MSTAs and highly comparable to the flexible alignment methods.

Abstract 5562: Utility of circulating biomarkers as outcome predictors in metastatic colorectal cancer and recurrent glioblastoma multiforme patients treated with bevacizumab/sorafenib

Abstract Purpose: Surrogate biomarkers are lacking for predicting or monitoring response to anti-angiogenesis therapies. We investigated whether circulating biomarkers (CBMs) of angiogenesis (i.e., bFGF, SDF-1α, HGF, sKIT, Ang-2, and PlGF) correlated with treatment efficacy in a pooled analysis of metastatic colorectal cancer (mCRC) and recurrent glioblastoma multiforme (rGBM) patients (pts) treated with bevacizumab/sorafenib (BEV/SOR). Experimental procedures: Peripheral blood samples were obtained for CBM analyses from pts enrolled in the North Central Cancer Treatment Group (NCCTG) phase II studies N054C (mCRC, n=75, Grothey, ASCO 2010) and N0776 (rGBM, n=54, Galanis, ASCO 2010). Blood collection time points were: baseline (BL), cycle 1 day 3 (C1D3), prior to treatment cycles 2, 3, 5, 7, 9, 11, 13, and after the pt went off study. Plasma CBM levels were determined by commercially-available ELISAs (R&D Systems) and performed according to manufacturer's instructions. For each CBM, a linear regression model that adjusted for study was used to evaluate the correlation with either progression-free survival (PFS) success/failure or progression within 14 days of the last blood draw for the following measures: absolute BL levels, log2 BL levels; C1D3 log2-fold change (FC) from BL, prior to cycle 2 log2-FC from BL, last draw log2-FC from BL, and last draw log2-FC from prior draw. Results summary: There appears to be no significant difference in the PFS or overall survival (OS) between the pts on these two studies; therefore, we pooled the patients from both studies for a combined analyses. We found no difference in absolute or log2 levels for any of the CBMs during the course of BEV/SOR treatment. In these pooled analyses, we found increased absolute and increased log2 BL SDF-1α levels were significantly correlated with PFS success (p=0.023 and p=0.02, respectively). After correcting for multiple comparisons (method of Benjamini & Hochberg) the p-values <0.05 had a false-discovery-rate of 41.4%. None of the other CBM measures were significantly correlated with either PFS success/failure or progression within 14 days of the last blood draw (all p>0.10). Conclusions: This study provides preliminary evidence that SDF-1α may be a useful CBM for determining treatment efficacy in these pts treated with BEV/SOR. Further prospective validation of SDF-1α for predicting pt progression with this treatment combination in advanced disease (e.g., mCRC and rGBM) appears warranted. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5562. doi:1538-7445.AM2012-5562

Sequential Bonferroni Methods for Multiple Hypothesis Testing with Strong Control of Family-Wise Error Rates I and II

Sequential procedures are developed for simultaneous testing of multiple hypotheses in sequential experiments. Proposed stopping rules and decision rules achieve strong control of both family-wise error rates I and II. The optimal procedure is sought that minimizes the expected sample size under these constraints. Bonferroni methods for multiple comparisons are extended to sequential setting and are shown to attain an approximately 50% reduction in the expected sample size compared with the earlier approaches. Asymptotically optimal procedures are derived under Pitman alternative.

Three-dimensional analysis of the pharyngeal airway morphology in growing Japanese girls with and without cleft lip and palate

We evaluated the 3-dimensional craniofacial skeletal and pharyngeal airway morphology in growing patients with and without cleft lip and palate. Our juvenile subjects consisted of 34 girls (ages, 9-12 years); 15 had cleft lip and palate, and 19 did not. The adolescent subjects consisted of 32 girls (ages, 13-17 years); 14 had cleft lip and palate, and 18 did not. Each subject was examined with cone-beam computed tomography. The dimensions of the craniofacial skeleton and pharyngeal airway were measured. The Scheffé method of multiple comparisons was used to identify relationships among skeletal and pharyngeal variables. The pharyngeal airway and mandibular size variables did not differ significantly between the juvenile and adolescent cleft lip and palate groups. Significant differences were observed between each cleft lip and palate group and its corresponding control group. FHN-A, FHN-B, FH-NA, FH-NB, and Co-Me were significantly smaller in the cleft lip and palate groups than in the corresponding control groups. Anteroposterior and lateral widths, heights, and volumes of the superior oropharyngeal airway were significantly smaller in the adolescent cleft lip and palate group than in the adolescent controls. The mandible and the oropharyngeal airway were larger in the adolescent controls than in the juvenile controls without cleft lip and palate, but there were no significant differences between the adolescent and juvenile patients with cleft lip and palate.

Step-up and step-down methods for testing multiple hypotheses in sequential experiments

Sequential methods are developed for testing multiple hypotheses, resulting in a statistical decision for each individual test and controlling the familywise error rate and the familywise power in the strong sense. Extending the ideas of step-up and step-down methods for multiple comparisons to sequential designs, the new techniques improve over the Bonferroni and closed testing methods proposed earlier by a substantial reduction of the expected sample size.

The effect of curcumin extract (Curcuma longa) on liver cell damage necrosis of mice after alcohol induction

Prasetyo Y, Suyatmi, Hanim D. 2012. The effect of turmeric extract (Curcuma longa) in preventing liver cell damage of mice by alcohol induction. Biofarmasi 10: 28-33. Turmeric extract (Curcuma longa) has an antioxidant activity to protect liver cell damage resulted by free radicals activity produced by alcohol metabolism. The objective of this research was to investigate the hepatoprotection activity of turmeric extract on liver cell damage induced by alcohol. This study was a laboratory experimental research with the post-test only controlled group design. The samples in this research were twenty-eight male mice (Mus musculus), Swiss Webster type, in age of 2-3 months old and ±20 g of body weight. The samples were divided into four groups, each group consisted of seven mice. Control group (K) was only given by aquadest 1 mL/20 g body weight of mice for 9 days in a row. The first treatment group (PI) was treated and given by alcohol with an increment form by 15%, 20%, 25% and 30% with a dose of 0.028 mL/20 g body weight of mice. The second treatment group (PII) was given like PI and given by turmeric extract in dose I by 0.14 mg/20 g body weight of mice for 9 days in a row. The third treatment group (PIII) was given like PI and given by turmeric extract in dose II by 0.28 mg/20 g body weight of mice. Finally on 9th day, mice were sacrificed with a vertebra cervical dislocation, then the liver was taken and stained with Hematoxylin-Eosin (HE). Histologic preparation was observed and scored based on the hepatocyte nuclear appearance (pyknosis, karyorrhexis and karyolysis). Each of them was given with score 1. Data were analyzed by One-Way ANOVA test (α=0.05) and before that, the data of control and P1 groups were analyzed by t-test independent. The analysis was continued by Post-Hoc Multiple Comparisons (LSD) test (α=0.05). The result of One-Way ANOVA showed that there was a significant difference among four groups. The result of Post-Hoc Multiple Comparisons (LSD) method showed that there was a significant difference between K-PI, K-PII, K-PIII, PI-PII, PII-PIII and PI-PIII (p<0.05). According to the results of this research, it was concluded that the turmeric extract was able to decrease the liver cell damage of mice, but the increase of turmeric extract dose, twice of first dose was not followed by the increase of protection effect to the liver cell damage of mice which induced by alcohol (p<0.05).

A SAS macro for testing differences among three or more independent groups using Kruskal-Wallis and Nemenyi tests

As a nonparametric method, the Kruskal-Wallis test is widely used to compare three or more independent groups when an ordinal or interval level of data is available, especially when the assumptions of analysis of variance (ANOVA) are not met. If the Kruskal-Wallis statistic is statistically significant, Nemenyi test is an alternative method for further pairwise multiple comparisons to locate the source of significance. Unfortunately, most popular statistical packages do not integrate the Nemenyi test, which is not easy to be calculated by hand. We described the theory and applications of the Kruskal-Wallis and Nemenyi tests, and presented a flexible SAS macro to implement the two tests. The SAS macro was demonstrated by two examples from our cohort study in occupational epidemiology. It provides a useful tool for SAS users to test the differences among three or more independent groups using a nonparametric method.

Osteoblast viability on hydroxyapatite with well-adjusted submicron and micron surface roughness as monitored by the proliferation reagent WST-1

The impact of the cell surface roughness on titanium alloys used for biomedical implants has been extensively studied, whereas the dependency of human osteoblast viability on hydroxyapatite (HA) submicron and micron surface roughness has hitherto not yet been investigated in detail. Therefore, we investigate in this study the effect of HA substrates with different well-adjusted surface roughness on human osteoblast proliferation using the standard colorimetric reagent WST-1. By grinding, we obtained HA surfaces with six levels of well-defined surface roughness ranging from Sa = 3.36 µm down to 0.13 µm, resulting in hydrophilic contact angles from 11° to 27°. Energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray fluorescence measurements confirmed that neither grinding paper residues nor changes of the crystal structure were introduced to the HA substrates by the grinding process. By applying this simple surface treatment, we were able to isolate other effects from surface chemistry, crystal structure, and relative density. The changes of the osteoblast proliferation (WST-1 assay) on these different roughened HA surfaces after 7 days were found to be insignificant (p > 0.05), evaluated by one-way analysis of variance and Tuckey's Multiple Comparison Method. The results of this study show that all roughened HA surfaces, regardless of the microtopography, are biocompatible and allow osteoblast attachment, proliferation, and collagen type I production. The comparison with surface roughness used for standard Ti-based implants yielded that for HA no finishing process is necessary to ensure a sound human osteoblast cell proliferation in vitro.

Graphical Procedures for Multiple Comparisons Under General Dependence

It has been more than half a century since Tukey first introduced graphical displays that relate non-overlap of confidence intervals to statistically significant differences between parameter estimates. In this paper, we show how Tukey’s graphical overlap procedure can be modified to accommodate general forms of dependence within and across samples. We also develop a procedure that can be used to more effectively resolve rankings within the tails of the distributions of parameter values, thereby generalizing existing methods for multiple comparisons with the best. We show that these new procedures retain the simplicity of Tukey’s original procedure while maintaining asymptotic control of the familywise error rate under very general conditions. Simple examples are used throughout to illustrate the procedures.

The Pore of the Voltage-Gated Proton Channel

In classical tetrameric voltage-gated ion channels four voltage-sensing domains (VSDs), one from each subunit, control one ion permeation pathway formed by four pore domains. The human Hv1 proton channel has a different architecture, containinga VSD, but lacking a pore domain. Since its location is not known, we searched for the Hv permeation pathway. We find that mutation of the S4 segment's third arginine R211 (R3) compromises proton selectivity, enabling conduction of a metal cation and even of the large organic cation guanidinium, reminiscent of Shaker's omega pore. In the open state, R3 appears to interact with an aspartate (D112) that is situated in the middle of S1 and is unique to Hv channels. The double mutation of both residues further compromises cation selectivity. We propose that membrane depolarization reversibly positions R3 next to D112 inthe transmembrane VSD to form the ion selectivity filter in the channel's open conformation.

Overexpression of interleukin‐6 and ‐8, cell growth inhibition and morphological changes in 2‐hydroxyethyl methacrylate‐treated human dental pulp mesenchymal stem cells

To evaluate morphological features, cell growth and interleukin-6 (IL-6) and interleukin-8 (IL-8) secretion in expanded ex vivo human dental pulp mesenchymal stem cells (DP-MSCs) after exposure to 2-hydroxyethyl methacrylate (HEMA). Dental pulp mesenchymal stem cells were derived from the dental pulps of 10 young donors. After in vitro isolation, DP-MSCs were treated with 3 and 5 mmol L(-1) HEMA, and after 24, 48 and 72 h of incubation, their morphological features, cell growth, IL-6 and IL-8 secretion were analysed. Differences in the cell growth and in the interleukin secretion were analysed for statistical significance with two-way anova tests and the Holm-Sidak method for multiple comparisons. Dental pulp mesenchymal stem cells revealed a decrease in cell growth with both treatments (P < 0.05), more evident at 5 mmol L(-1) . Microscopic analysis displayed extensive cytotoxic effects in treated cells, which lost their fibroblastoid features and became retracted, even roundish, with a large number of granules. An up-regulation of IL-6 and IL-8 in treated cells cytokines was evident (P < 0.05). 2-Hydroxyethyl methacrylate exhibited cytotoxicity, inhibited cell growth and induced morphological changes in cultured DP-MSCs. Moreover, in treated samples, an up-regulation of soluble mediators of inflammation such as IL-6 and IL-8 cytokines was found. The direct application of HEMA potentially induces an inflammation process that could be the starting point for toxic response and cell damage in DP-MSCs.

Influence of prone positioning on the measurement of transpulmonary thermodilution-derived variables in critically ill patients

Patients with respiratory failure undergoing prone positioning (PP) are often monitored by the transpulmonary thermodilution (TPTD) technique. However, it remains unclear whether the measurement of TPTD-derived variables is influenced by PP. We investigated the effects of 135° PP on the accuracy of TPTD-derived variables and their changes over an 8-10 h period of time. We studied 16 mechanically ventilated patients who underwent PP for acute respiratory distress syndrome or acute lung injury and received hemodynamic monitoring by the TPTD technique. Measurements of extravascular lung water index (EVLWI), global end-diastolic volume index (GEDVI), ejection fraction corrected GEDVI (cGEDVI), pulmonary vascular permeability index (PVPI) and hemodynamic variables were obtained 10 min before and after positioning and repositioning. One-way analysis of variance and Friedman's test with Student-Newman-Keuls method for all pairwise multiple comparisons were used for statistical analysis. EVLWI increased after proning (12.7 ± 4.7 vs. 14.8 ± 7.8 ml/kg) and remained elevated until end of prone positioning (15.1 ± 7.2 vs. 12.8 ± 4.9 ml/kg) with P < 0.05 for difference between respective time points. After proning, GEDVI remained unchanged (571 ± 153 vs. 593 ± 152 ml/m²). At the end of prone positioning GEDVI was 610 ± 55 ml/m² and decreased after returning to supine to 553 ± 14 ml/m². Proning increased cGEDVI from 525 ± 136 to 570 ± 11 ml/m² and repositioning decreased cGEDVI from 558 ± 116 to 496 ± 121 ml/m². No significant changes in PVPI were observed during the study period. EVLWI and GEDVI measurements are possibly influenced by prone positioning. In spite of statistical significance, the differences in EVLWI and GEDVI are low and presumably of no clinical relevance.

Smoking and COX-2 Functional Polymorphisms Interact to Increase the Risk of Gastric Cardia Adenocarcinoma in Chinese Population

BackgroundOver-expression and increased activity of cyclooxygenase (COX)-2 induced by smoking has been implicated in the development of cancer. This study aimed to explore the interaction between smoking and functional polymorphisms of COX-2 in modulation of gastric cardia adenocarcinoma (GCA) risk.Methods and FindingsThree COX-2 polymorphisms, including –1195G>A (rs689466), –765G>C (rs20417), and 587Gly>Arg (rs3218625), were genotyped in 357 GCA patients and 985 controls. In the multivariate logistic regression analysis, we found that the –1195AA, –765GC, and 587Arg/Arg genotypes were associated with increased risk of GCA (OR = 1.50, 95% CI = 1.05–2.13; OR = 2.06, 95% CI = 1.29–3.29 and OR = 1.67, 95% CI = 1.04–2.66, respectively). Haplotype association analysis showed that compared with G−1195-G−765- GGly587Arg, the A−1195-C−765-AGly587Arg conferred an increased risk of GCA (OR = 2.49, 95% CI = 1.54–4.01). Moreover, significant multiplicative interactions were observed between smoking and these three polymorphisms of –1195G>A, –765G>C, and 587Gly>Arg, even after correction by false discovery rate (FDR) method for multiple comparisons (FDR-P interaction = 0.006, 5.239×10−4 and 0.017, respectively). Similarly, haplotypes incorporating these three polymorphisms also showed significant interaction with smoking in the development of GCA (P for multiplicative interaction = 2.65×10−6).ConclusionThese findings indicated that the functional polymorphisms of COX-2, in interaction with smoking, may play a substantial role in the development of GCA.