Country clustering in comparative political economy

"In the comparative political economy of rich democracies there is a long tradition of classifying countries into one of a small number of categories based on their economic institutions and policies. The most recent of these is the Varieties of Capitalism project, which posits two major clusters of nations: coordinated and liberal market economies. This classification has generated controversy. We leverage recent advances in mixture model-based clustering to see what the data say on the matter. We find that there is considerable uncertainty around the number of clusters and, barring a few cases, which country should be placed in which cluster. Moreover, when viewed over time, both the number of clusters and country membership change considerably. As a result, arguments about who has the 'right' typology are misplaced. We urge caution in using these country classifications in structuring qualitative inquiry and discourage their usage as indicator variables in quantitative analysis, especially in the context of time-series cross-section data. We argue that the real value of both Esping-Andersen's work and the Varieties of Capitalism project consists of their theoretical contributions and heuristic classification of ideal types." (author's abstract)"In der vergleichenden Politischen Ökonomie reicher Demokratien gibt es eine lange Tradition, Länder aufgrund ihrer unterschiedlichen wirtschaftlichen Institutionen und Policies zu typologisieren. Die jüngste dieser Typologien - das 'Varieties-of-Capitalism'-Konzept - erfasst zwei Gruppen von Ländern: koordinierte und liberale Marktwirtschaften. Da diese Klassifizierung einige Kontroversen hervorgerufen hat, nutzen die Autoren neueste Fortschritte im 'mixture model-based clustering', um zu prüfen, welche Erkenntnisse die Daten zu diesem Problem liefern. Die Ergebnisse weisen eine beträchtliche Unsicherheit hinsichtlich der Anzahl der Cluster und, mit wenigen Ausnahmen, der Zuordnung der Länder zu Clustern auf. Betrachtet man größere Zeiträume, variieren darüber hinaus die Anzahl der Cluster und Ländermitgliedschaften erheblich. Als Folge dieser Befunde halten die Autoren Argumentationen über die 'richtige' Typologisierung für unangebracht und raten davon ab, diese Länderklassifizierungen zur Strukturierung qualitativer Studien heranzuziehen oder als Indikatorvariablen in quantitativen Analysen zu nutzen. Dies gilt insbesondere im Kontext von gepoolten Zeitreihen- und Querschnittsdaten. Sie argumentieren, dass der substanzielle Wert sowohl der Forschung von Esping-Andersen als auch des 'Varieties-of-Capitalism'-Ansatzes in den Beiträgen zur Theorie und den heuristischen Klassifizierungen von Idealtypen besteht." (Autorenreferat

The Host Cell Sulfonation Pathway Contributes to Retroviral Infection at a Step Coincident with Provirus Establishment

The early steps of retrovirus replication leading up to provirus establishment are highly dependent on cellular processes and represent a time when the virus is particularly vulnerable to antivirals and host defense mechanisms. However, the roles played by cellular factors are only partially understood. To identify cellular processes that participate in these critical steps, we employed a high volume screening of insertionally mutagenized somatic cells using a murine leukemia virus (MLV) vector. This approach identified a role for 3′-phosphoadenosine 5′-phosphosulfate synthase 1 (PAPSS1), one of two enzymes that synthesize PAPS, the high energy sulfate donor used in all sulfonation reactions catalyzed by cellular sulfotransferases. The role of the cellular sulfonation pathway was confirmed using chemical inhibitors of PAPS synthases and cellular sulfotransferases. The requirement for sulfonation was mapped to a stage during or shortly after MLV provirus establishment and influenced subsequent gene expression from the viral long terminal repeat (LTR) promoter. Infection of cells by an HIV vector was also shown to be highly dependent on the cellular sulfonation pathway. These studies have uncovered a heretofore unknown regulatory step of retroviral replication, have defined a new biological function for sulfonation in nuclear gene expression, and provide a potentially valuable new target for HIV/AIDS therapy

Divergence of the single-copy DNA sequences of the Western Grebe (Aechmophorus occidentalis) and Clark’s Grebe (A. clarkii), as indicated by DNA-DNA hybridization

Single-copy nuclear DNA sequences of individuals of Aechmophorus occidentalis and A. ciarkii were compared by DNA-DNA hybridization. In each of three experimental sets the average thermal stability of homoduplex and within-species DNA-DNA hybrids did not differ, but the between-species DNA-DNA hybrids dissociated at an average temperature 0.57°C below the median melting temperature of homoduplex and within-species hybrids. The difference was highly significant in all three sets. The median DNA sequence distance between A. occidentalis and A. clarkii is comparable to such distances between other closely related congeneric species

ZASC1 knockout mice exhibit an early bone marrow-specific defect in murine leukemia virus replication

Abstract Background ZASC1 is a zinc finger-containing transcription factor that was previously shown to bind to specific DNA binding sites in the Moloney murine leukemia virus (Mo-MuLV) promoter and is required for efficient viral mRNA transcription (J. Virol. 84:7473-7483, 2010). Methods To determine whether this cellular factor influences Mo-MuLV replication and viral disease pathogenesis in vivo, we generated a ZASC1 knockout mouse model and completed both early infection and long term disease pathogenesis studies. Results Mice lacking ZASC1 were born at the expected Mendelian ratio and showed no obvious physical or behavioral defects. Analysis of bone marrow samples revealed a specific increase in a common myeloid progenitor cell population in ZASC1-deficient mice, a result that is of considerable interest because osteoclasts derived from the myeloid lineage are among the first bone marrow cells infected by Mo-MuLV (J. Virol. 73: 1617-1623, 1999). Indeed, Mo-MuLV infection of neonatal mice revealed that ZASC1 is required for efficient early virus replication in the bone marrow, but not in the thymus or spleen. However, the absence of ZASC1 did not influence the timing of subsequent tumor progression or the types of tumors resulting from virus infection. Conclusions These studies have revealed that ZASC1 is important for myeloid cell differentiation in the bone marrow compartment and that this cellular factor is required for efficient Mo-MuLV replication in this tissue at an early time point post-infection

Population screening for colorectal cancer means getting FIT:the past, present, and future of colorectal cancer screening using the fecal immunochemical test for hemoglobin (FIT)

Fecal immunochemical tests for hemoglobin (FIT) are changing the manner in which colorectal cancer (CRC) is screened. Although these tests are being performed worldwide, why is this test different from its predecessors? What evidence supports its adoption? How can this evidence best be used? This review addresses these questions and provides an understanding of FIT theory and practices to expedite international efforts to implement the use of FIT in CRC screening

Identification of prognostic phenotypes of esophageal adenocarcinoma in two independent cohorts.

BACKGROUND & AIMS: Most patients with esophageal adenocarcinoma (EAC) present de novo. Although this may be due to inadequate screening strategies, the precise reason for this observation is not clear.. We compared survival of patients with prevalent EAC with and without synchronous BE/intestinal metaplasia of the esophagus (IM) at the time of EAC diagnosis. METHODS: Clinical data were studied using Cox Proportional Hazards regression to evaluate the effect of synchronous BE/IM on EAC survival independent of age, sex, TNM stage and tumor location. Two cohorts from the Mayo Clinic and a U.K. multicenter prospective cohort were included. RESULTS: The Mayo cohort had 411 EAC patients with 49.3% with BE/IM demonstrating a survival benefit as compared to those without (hazard ratio (HR), 0.44; 95% CI: 0.34 - 0.57, P<0.001). In a multivariable analysis BE/IM was associated with better survival independent of age, sex, stage and tumor location and length (adjusted HR: 0.66, 95% CI: 0.5-0.88, P=0.005). The UK cohort contained 1417 patients, 45% with BE/IM demonstrating a survival benefit as compared with non-BE/IM patients (HR 0.59, 95% CI: 0.5-0.69, P<0.001) with continued significance in multivariable analysis that included age, sex, stage, and tumor location (adjusted HR 0.77, 95% CI: 0.64-0.93, P=0.006). CONCLUSION: Two types of esophageal adenocarcinoma can be characterized based on the presence or absence of Barrett's epithelium. These findings have implications for understanding the etiology of EAC and determining prognosis as well as for development of optimal clinical strategies to identify patients at risk

Fecal Tests: From Blood to Molecular Markers

Detection of molecular markers for colorectal neoplasia in feces has the potential to improve performance of simple noninvasive screening tests for colorectal cancer. Most research has explored the value of DNA-based, RNA-based, and protein-based markers. In all cases there has been a trend to move from a single marker to a panel of markers to improve sensitivity. Unfortunately, no type of molecular marker has proved specific for neoplasia. DNA tests have been improved by combining mutation detection with assessment of DNA integrity plus epigenetic markers of neoplasia. RNA-based approaches are just beginning to explore the full power of transcriptomics. So far, no protein-based fecal test has proved better than fecal immunochemical tests for hemoglobin. Finally, no marker or panel of markers has yet been developed to the point where it has been evaluated in large unbiased population studies to assess performance across all stages of neoplasia and in all practical environments