Learning in Hybrid-Project Systems: The Effects of Project Performance on Repeated Collaboration

This study advances contingency theories of performance-outcome learning in hybrid-project systems, in which both project participants and superordinate organizations influence the formation of project ventures. We propose that performance-outcome learning depends on the perceived relevance of prior performance and on organizational control over project participants. We examine this framework using data on 239 U.S. movie projects from the years 1931-40. In keeping with our theory, higher project performance led to future collaborations with the same partners, contingent on prior collaborations, project similarity, and organizational control. Our findings imply distinct patterns of network evolution and unfolding adaptation of hybrid-project systems through slow-moving, local adjustments

Relationships between the <i>Osteocalcin</i> Gene Polymorphisms, Serum Osteocalcin Levels, and Hepatitis B Virus-Related Hepatocellular Carcinoma in a Chinese Population

<div><p>Background</p><p>Available evidence has demonstrated that osteocalcin may play a role in pathogenesis of cancer, and mutation of the <i>osteocalcin</i> gene may be involved in the cancer development. The aim of this study is to determine whether <i>osteocalcin</i> gene polymorphisms are associated with hepatitis B virus (HBV) related hepatocellular carcinoma (HCC) among Chinese population.</p><p>Methods</p><p>A total of 515 subjects were divided into four groups: 129 patients with chronic hepatitis B (CHB), 62 patients with HBV-related liver cirrhosis (LC), 154 patients with HBV-related HCC, and 170 healthy controls. The polymerase chain reaction-restriction fragment length polymorphism strategy was used to detect <i>osteocalcin</i> gene <i>rs1800247</i> and <i>rs1543297</i> polymorphisms.</p><p>Results</p><p>Compared with healthy controls, the <i>rs1800247</i> HH and Hh genotypes were associated with a significantly increased susceptibility to HCC (HH versus hh: OR = 6.828, 95% CI 2.620–17.795, <i>P</i> <0.001; Hh versus hh: OR = 6.306, 95% CI 3.480–11.423, <i>P</i> <0.001, respectively). Similarly, the subjects bearing the H allele of <i>rs1800247</i> had more than a 2.4-fold increased risk for development of HCC (OR = 2.484, 95% CI 1.747–3.532, <i>P</i> <0.001) compared with those bearing the h allele. In addition, we found significant decreased serum osteocalcin levels in HBV-related HCC patients (11.73±8.18 ng/mL) compared with healthy controls (15.3±6.06 ng/mL). Furthermore, the serum osteocalcin levels were significantly lower in HCC patients than healthy controls among the individuals with heterozygous Hh genotype (<i>P</i> = 0.003) and CT genotype (<i>P</i> <0.001). In contrast, there were no significant differences in the genotype and allele of <i>rs1543297</i> polymorphisms between the groups of patients and healthy controls.</p><p>Conclusions</p><p>These findings for the first time suggest that genetic variant in <i>osteocalcin</i> gene <i>rs1800247</i> polymorphisms may be a risk factor for HBV-related HCC. We also find an inverse association of serum osteocalcin levels with HCC.</p></div

Genotype and allele frequencies of two SNPs in the <i>osteocalcin</i> gene between HCC patients and healthy controls.

<p>* Adjusted for sex, age, smoking and drinking by logistic regression model</p><p>^a Dominant model: HH+Hh versus hh;</p><p>^b Recessive model: HH versus hh+Hh</p><p>^c Dominant model: TT+CT versus CC;</p><p>^d Recessive model: TT versus CC+CT</p><p>Genotype and allele frequencies of two SNPs in the <i>osteocalcin</i> gene between HCC patients and healthy controls.</p

PCR-RFLP assay for analyzing the <i>rs1800247</i> polymorphisms of the <i>osteocalcin</i> gene.

<p>Lanes M: DNA Marker; Lanes 1, 5, 6, 9, and 10 show Hh genotype; Lanes 2, 3, 4, 7, and 11 show hh genotype; lane 8 shows HH genotype.</p

Demographic characteristics of the study population.

<p><i>CHB</i> chronic hepatitis B, <i>HCC</i> hepatocellular carcinoma, <i>LC</i> liver cirrhosis, <i>SD</i> standard deviation, <i>IQR</i> interquartile range</p><p>Demographic characteristics of the study population.</p

Association of <i>osteocalcin</i> polymorphisms with serum osteocalcin levels (median ± IQR, ng/mL) in cases and healthy controls.

<p><i>CHB</i> chronic hepatitis B, <i>HCC</i> hepatocellular carcinoma,<i>LC</i> liver cirrhosis,<i>IQR</i> interquartile range, OC, osteocalcin, <i>N</i> group number</p><p>* Kruskal-Wallis test: comparing the difference of serum osteocalcin levels in the three genotypes among the same group subjects.</p><p>** Kruskal-Wallis test: comparing the difference of serum osteocalcin levels in the four group subjects among the individuals with the same genotype.</p><p>Association of <i>osteocalcin</i> polymorphisms with serum osteocalcin levels (median ± IQR, ng/mL) in cases and healthy controls.</p

PCR-RFLP assay for analyzing the <i>rs1543297</i> polymorphisms of the <i>osteocalcin</i> gene.

<p>Lanes M: DNA Marker; Lanes 1, 2 and 9 show CC genotype; lane 5, 6, and 10 shows CT genotype; Lanes 3, 4, 7 and 8 show TT genotype.</p

Myeloperoxidase Polymorphism, Menopausal Status, and Breast Cancer Risk: An Update Meta-Analysis

<div><p>Myeloperoxidase (MPO) is a metabolic/oxidative lysosomal enzyme secreted by reactive neutrophils at the sites of inflamed organs and tissues during phagocytosis. MPO has been either directly or indirectly linked to neoplasia, which is a well-established risk factor for many types of cancer. A large number of studies have reported the role of MPO G-463A polymorphism regarding breast-cancer risk. However, the published findings are inconsistent. Therefore, we conducted a meta-analysis to determine more precise estimations for the relationship. Eligible studies were identified by searching several electronic databases for relevant reports published before June 2012. According to the inclusion criteria and exclusion criteria, a total of five eligible studies were included in the pooled analyses. When the five eligible studies concerning MPO G-463A polymorphism were pooled into this meta-analysis, there was no evidence found for a significant association between MPO G-463A polymorphism and breast-cancer risk in any genetic model. We also categorized by ethnicity (Caucasian or Asian) for subgroup analysis; according to this subgroup analysis, we found no significant association between MPO G-463A polymorphism and breast-cancer risk in any genetic model. However, in the stratified analysis for the premenopausal group, women carrying the AA genotype were found to have a significantly reduced risk (OR = 0.56, 95% CI 0.34–0.94, p = 0.027). Under the recessive model, there was a significant association between MPO G-463A polymorphism and breast-cancer risk (OR = 0.57, 95% CI 0.34–0.93, p = 0.025). We conclude that MPO-G463A polymorphism might not be a good predictor of breast-cancer risk, though menopausal status modified women’s risk of developing breast cancer.</p></div

Flow chart of meta-analysis.

<p>Flow chart of meta-analysis.</p

Genetic polymorphism of MPO and breast cancer risk.

a<p><i>P</i> value for heterogeneity based on Q test.</p