Large foreign ownership and firm-level stock return volatility in emerging markets

Author name used in this publication: Steven X. Wei2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Patient-reported outcomes measures and patient preferences for minimally invasive glaucoma surgical devices.

BackgroundMany therapeutic options are available to glaucoma patients. One recent therapeutic option is minimally invasive glaucoma surgical (MIGS) devices. It is unclear how patients view different treatments and which patient-reported outcomes would be most relevant in patients with mild to moderate glaucoma. We developed a questionnaire for patients eligible for MIGS devices and a patient preference study to examine the value patients place on certain outcomes associated with glaucoma and its therapies.ObjectivesTo summarize the progress to date.MethodsQuestionnaire development: We drafted the questionnaire items based on input from one physician and four patient focus groups, and a review of the literature. We tested item clarity with six cognitive interviews. These items were further refined. Patient preference study: We identified important benefit and risk outcomes qualitatively using semi-structured, one-on-one interviews with patients who were eligible for MIGS devices. We then prioritized these outcomes quantitatively using best-worst scaling methods.ResultsQuestionnaire testing: Three concepts were deemed relevant for the questionnaire: functional limitations, symptoms, and psychosocial factors. We will evaluate the reliability and validity of the 52-item draft questionnaire in an upcoming field test. Patient preference study: We identified 13 outcomes that participants perceived as important. Outcomes with the largest relative importance weights were "adequate IOP control" and "drive a car during the day."ConclusionsPatients have the potential to steer clinical research towards outcomes that are important to them. Incorporating patients' perspectives into the MIGS device development and evaluation process may expedite innovation and availability of these devices

Brain Tumor Segmentation from Multi-Spectral MR Image Data Using Random Forest Classifier

The development of brain tumor segmentation techniques based on multi-spectral MR image data has relevant impact on the clinical practice via better diagnosis, radiotherapy planning and follow-up studies. This task is also very challenging due to the great variety of tumor appearances, the presence of several noise effects, and the differences in scanner sensitivity. This paper proposes an automatic procedure trained to distinguish gliomas from normal brain tissues in multi-spectral MRI data. The procedure is based on a random forest (RF) classifier, which uses 80 computed features beside the four observed ones, including morphological ones, gradients, and Gabor wavelet features. The intermediary segmentation outcome provided by the RF is fed to a twofold post-processing, which regularizes the shape of detected tumors and enhances the segmentation accuracy. The performance of the procedure was evaluated using the 274 records of the BraTS 2015 train data set. The achieved overall Dice scores between 85-86% represent highly accurate segmentation

Tetramethylpyrazine attenuates spinal cord ischemic injury due to aortic cross-clamping in rabbits

BACKGROUND: Lower limb paralysis occurs in 11% of patients after surgical procedure of thoracic or thoracoabdominal aneurysms and is an unpredictable and distressful complication. The aim of this study was to investigate the effects of tetramethylpyrazine (TMP), an intravenous drug made from traditional Chinese herbs, on the neurologic outcome and hisotpathology after transient spinal cord ischemia in rabbits. METHODS: Forty-five male New Zealand white rabbits were anesthetized with isoflurane and spinal cord ischemia was induced for 20 min by infrarenal aortic occlusion. Animals were randomly allocated to one of five groups (n = 8 each). Group C received no pharmacologic intervention. Group P received intravenous infusion of 30 mg·kg(-1) TMP within 30 min before aortic occlusion. Group T(1), Group T(2) and Group T(3) received intravenous infusion of 15, 30 and 60 mg·kg(-1) TMP respectively within 30 min after reperfusion. In the sham group (n = 5), the animals underwent the same procedures as the control group except infrarental aortic unocclusion. Neurologic status was scored by using the Tarlov criteria (in which 4 is normal and 0 is paraplegia) at 4 h, 8 h, 12 h, 24 h, and 48 h after reperfusion. All animals were sacrificed at 48 h after reperfusion and the spinal cords (L(5)) were removed immediately for histopathologic study. RESULTS: All animals in the control group became paraplegic. Neurologic status and histopathology (48 h) in the Groups P, T(2) and T(3) were significantly better than those in the control group (P < 0.05). There was a strong correlation between the final neurologic scores and the number of normal neurons in the anterior spinal cord (r = 0.776, P < 0.01). CONCLUSION: Tetramethylpyrazine significantly reduces neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion within a certain range of dose

Involvement of TSC genes and differential expression of other members of the mTOR signaling pathway in oral squamous cell carcinoma

<p>Abstract</p> <p>Background</p> <p>Despite extensive research, the five-year survival rate of oral squamous cell carcinoma (OSCC) patients has not improved. Effective treatment of OSCC requires the identification of molecular targets and signaling pathways to design appropriate therapeutic strategies. Several genes from the mTOR signaling pathway are known to be dysregulated in a wide spectrum of cancers. However, not much is known about the involvement of this pathway in tumorigenesis of OSCC. We therefore investigated the role of the tumor suppressor genes, <it>TSC1 </it>and <it>TSC2</it>, and other members of this pathway in tumorigenesis of OSCC.</p> <p>Methods</p> <p>Expression of genes at the RNA and protein levels was examined by semi-quantitative RT-PCR and western blot analyses, respectively. Loss of heterozygosity was studied using matched blood and tumor DNA samples and microsatellite markers from the <it>TSC1</it>, <it>TSC2 </it>and <it>PTEN </it>candidate regions. The effect of promoter methylation on TSC gene expression was studied by treating cells with methyltransferase inhibitor 5-azacytidine. Methylation status of the <it>TSC2 </it>promoter in tissue samples was examined by combined bisulfite restriction analysis (COBRA).</p> <p>Results</p> <p>The semi-quantitative RT-PCR analysis showed downregulation of <it>TSC1</it>, <it>TSC2</it>, <it>EIF4EBP1 </it>and <it>PTEN</it>, and upregulation of <it>PIK3C2A</it>, <it>AKT1</it>, <it>PDPK1</it>, <it>RHEB</it>, <it>FRAP1</it>, <it>RPS6KB1</it>, <it>EIF4E </it>and <it>RPS6 </it>in tumors. A similar observation was made for AKT1 and RPS6KB1 expression in tumors at the protein level. Investigation of the mechanism of downregulation of TSC genes identified LOH in 36.96% and 39.13% of the tumors at the TSC1 and TSC2 loci, respectively. No mutation was found in TSC genes. A low LOH rate of 13% was observed at the PTEN locus. Treatment of an OSCC cell line with the methyltransferase inhibitor 5-azacytidine showed a significant increase in the expression of TSC genes, suggesting methylation of their promoters. However, the 5-azacytidine treatment of non-OSCC HeLa cells showed a significant increase in the expression of the <it>TSC2 </it>gene only. In order to confirm the results in patient tumor samples, the methylation status of the <it>TSC2 </it>gene promoter was examined by COBRA. The results suggested promoter hypermethylation as an important mechanism for its downregulation. No correlation was found between the presence or absence of LOH at the TSC1 and TSC2 loci in 50 primary tumors to their clinicopathological variables such as age, sex, T classification, stage, grade, histology, tobacco habits and lymph node metastasis.</p> <p>Conclusion</p> <p>Our study suggests the involvement of TSC genes and other members of the mTOR signaling pathway in the pathogenesis of OSCC. LOH and promoter methylation are two important mechanisms for downregulation of TSC genes. We suggest that known inhibitors of this pathway could be evaluated for the treatment of OSCC.</p

Compensatory density feedback of Oncomelania hupensis populations in two different environmental settings in China

BACKGROUND: The most recent strategy for schistosomiasis control in the People's Republic of China aims to reduce the likelihood of environmental contamination of schistosome eggs. Despite considerable progress, it is believed that achievements would be further consolidated with additional intermediate host snail control measures. We provide an empirical framework for discerning the relative contribution of intrinsic effects (density feedback) from other extrinsic drivers of snail population dynamics. METHODS: We set up experiments in two study locations to collect reproduction data of Oncomelania hupensis, the intermediate host snail of Schistosoma japonicum. We applied a set of four population dynamic models that have been widely used to study phenomenological time-series data to examine the properties of demographic density feedback patterns from abundance data. We also contrasted the obtained results with the component feedback of density on survival rate to determine whether adult survival was the principal driver of the demographic feedback observed. RESULTS: Demographic density feedback models (Ricker- and Gompertz-logistic) accounted for <99% of Akaike's information criterion model weight, with the Gompertz ranking highest in all O. hupensis population groups. We found some evidence for stronger compensatory feedback in the O. hupensis population from Sichuan compared to a Jiangsu population. Survival rates revealed strong component feedback, but the log-linear relationships (i.e. Gompertz) had less support in the demographic feedback analysis. CONCLUSIONS: Our findings indicate that integrated schistosomiasis control measures must continue to reduce parasite abundance further because intermediate host snail populations tend to grow exponentially at low densities, especially O. hupensis populations in mountainous regions. We conclude that density feedback in adult survival is the principal component contribution to the demographic phenomenon observed in the population fitness (r)-abundance relationship

Effect of surface oxygen concentration on activation of methane over supported metal catalysts

Activation of methane over supported metal catalysts was investigated using MS-pulse technique on-line. Oxygen-free CH4 pulsing reactions were carried out over both Rh/SiO2 and Ru/SiO2 at 700 degreesC. Large amounts of CO and CO2 were observed at the first pulse of CH4 over oxidized Rh(O)/SiO2 catalyst. However, no CO2 formation was observed at the second pulse and thereafter. Similar to the response of Rh(O) /SiO2 catalyst, the intensity of CO and CO2 was strong at the first pulse over reduced Rh/SiO2 catalyst, and CO2 appeared also only at the first pulse over Rh/SiO2 catalyst. No CO2 was detected at the second pulse and thereafter. CH4 pulsing over Ru(O)/SiO2 catalyst also produced CO and CO2. CO and CO2 were detected from the first pulse I and their intensity was much stronger than that of CO and CO2 produced over Rh/SiO2 catalyst. However, unlike Rh/SiO2 catalyst, CO2 was formed at every pulse over Ru(O)/SiO2 catalyst. Pulsing CH4 over Ru/SiO2 catalyst also produced both CO and CO2 at every pulse. This difference between Rh and Ru catalysts may be due to the difference in the bond strength of Ru-O (528.4 kJ/mol) and Rh-O (405.1 kJ/mol) and in their relative oxygen affinities, Ru-0 can be more easily oxidized by O-2 than Rh-0 owing to the greater oxygen affinity of Ru. Surface oxygen should play an important role in the activation of methane and the product distribution

Exploring the journey to services

Firms are increasingly providing services to complement their product offerings. The vast majority of studies on the service journey, also known as servitization or service transition, examine the challenges and enablers of the process of change through cases studies. Investigations that provide an in-depth longitudinal analysis of the steps involved in the service journey are much rarer. Such a detailed understanding is required in order to appreciate fully how firms can leverage the enablers while overcoming the challenges of servitization. This study investigates what does a service journey look like? It analyzes in some detail the actual service journeys undertaken by three firms in the well-being, engineering and learning sectors. The paper offers four contributions. First, in the change literature, there are two dominant theories: The punctuated equilibrium model and the continuous change model. This study demonstrates that servitization follows a continuous change rather than a punctuated equilibrium. It shows that such continuous change is neither logical nor structured but much more emergent and intuitive in nature. Second, the study provides empirical evidence to support a contingency view of the dominance and sequencing of the different process models of change across the change journey. Third, this research shows the pace of service development and when the coexistence of basic, intermediate and complex services occurs. Finally, it contributes to the literature in the service field by presenting three actual service journeys and the associated seven stages of the service strategy model that organizations should consider when managing their service journeys