The case of a network in the Berlin-Brandenburg optics cluster

Much research on regional business clusters refers to path dependence as a central feature in the evolution of cluster structures. In many cases, however, little is known about the agentic processes and mechanisms that underlie path dependence. In this article, we explore changes in a specific network in the optics cluster in the German region of Berlin-Brandenburg to show that development of clusters can be driven by elements of both emergence and planning. In particular, we argue that current actors actively and purposively draw upon rules and resources that were shaped not only in the long and discontinuous history of the cluster but also in the recent process of network development that involves careful planning and well-structured planning tools. Using central concepts from structuration theory, we show how agency is implicated in the coordination of the network and how agency turns coordination into a self-reinforcing mechanism. The findings suggest that purposive planning involves a fundamental ambivalence in the processes and outcomes of path dependence, at the level of both the cluster and its constituent networks

Network Integration in Regional Clusters and Firm Innovation – A Comparison of Measures

This paper assesses the effects of network involvement on firm-level innovation. Results from a structural network analysis of firms in a regional photonics cluster in Germany indicate that clique overlap is a much better predictor of firm-level innovation in clusters than a firm’s centrality, measured by the number of direct ties. The paper concludes with implications for network and cluster theory and for managing firms and networks in regional high-tech clusters

Authority and anomie in regional clusters

In this article we consider the nature and implications of barriers to collaborative process learning that may occur in regional clusters. Our approach is rooted in research in interorganizational collaboration and focuses on interview-based research in photonics clusters in: Scotland and the West Midlands in the United Kingdom; Berlin-Brandenburg in Germany; and Arizona in the United States of America. From this research we develop characterizations of the barriers to collaborative process learning in clusters at three levels of analysis—the macro, micro and meso levels. We also develop an integrated conceptualization of these barriers, which reveals a difficult tension between ‘authority’ and ‘anomie’. This tension has implications for the management of process learning, but also connects with recent debate about whether learning is most helpfully understood as an individual or collective process

Animal models for investigating chronic pancreatitis

Chronic pancreatitis is defined as a continuous or recurrent inflammatory disease of the pancreas characterized by progressive and irreversible morphological changes. It typically causes pain and permanent impairment of pancreatic function. In chronic pancreatitis areas of focal necrosis are followed by perilobular and intralobular fibrosis of the parenchyma, by stone formation in the pancreatic duct, calcifications in the parenchyma as well as the formation of pseudocysts. Late in the course of the disease a progressive loss of endocrine and exocrine function occurs. Despite advances in understanding the pathogenesis no causal treatment for chronic pancreatitis is presently available. Thus, there is a need for well characterized animal models for further investigations that allow translation to the human situation. This review summarizes existing experimental models and distinguishes them according to the type of pathological stimulus used for induction of pancreatitis. There is a special focus on pancreatic duct ligation, repetitive overstimulation with caerulein and chronic alcohol feeding. Secondly, attention is drawn to genetic models that have recently been generated and which mimic features of chronic pancreatitis in man. Each technique will be supplemented with data on the pathophysiological background of the model and their limitations will be discussed

Absence of the neutrophil serine protease cathepsin G decreases neutrophil granulocyte infiltration but does not change the severity of acute pancreatitis

Acute pancreatitis is characterized by an early intracellular protease activation and invasion of leukocytes into the pancreas. Cathepsins constitute a large group of lysosomal enzymes, that have been shown to modulate trypsinogen activation and neutrophil infiltration. Cathepsin G (CTSG) is a neutrophil serine protease of the chymotrypsin C family known to degrade extracellular matrix components and to have regulatory functions in inflammatory disorders. The aim of this study was to investigate the role of CTSG in pancreatitis. Isolated acinar cells were exposed to recombinant CTSG and supramaximal cholezystokinin stimulation. In CTSG(-/-) mice and corresponding controls acute experimental pancreatitis was induced by serial caerulein injections. Severity was assessed by histology, serum enzyme levels and zymogen activation. Neutrophil infiltration was quantified by chloro-acetate ersterase staining and myeloperoxidase measurement. CTSG was expessed in inflammatory cells but not in pancreatic acinar cells. CTSG had no effect on intra-acinar-cell trypsinogen activation. In CTSG(-/-) mice a transient decrease of neutrophil infiltration into the pancreas and lungs was found during acute pancreatitis while the disease severity remained largely unchanged. CTSG is involved in pancreatic neutrophil infiltration during pancreatitis, albeit to a lesser degree than the related neutrophil (PMN) elastase. Its absence therefore leaves pancreatitis severity essentially unaffected

Synthesis and Properties of Vinylogous 6-(Cyclopentadienyl)pentafulvenes

The application of the principle of kinetic stabilization on vinylogous 6-(cyclopentadienyl)pentafulvenes 1 led to the synthesis of the di- and tetra-tert-butyl derivatives 7a – e and 8a - c. Their reactions with bases and acids form charged, heteroatom-free cyanine-type carbanionic 9a - e, 10a – e and carbocationic 11a – e, 12a – c species which were characterized with NMR and UV/Vis spectroscopy. Conclusions on the ion pair structures of the alkali metal salts 9a - e and 10a – c are drawn from the spectroscopic data. Additionally, in one case the behavior of the alkali metal salt 10b towards oxidants was studied by cyclic voltammetry and the structure of the corresponding hydrocarbon 8b was proved by X-ray structural analysis

A silent cry for leadership : organizing for leading (in) clusters

Leadership research so far has neglected clusters as a particular context for leadership, while research on networks and clusters has hardly studied leadership issues. This paper fills this dual gap in the abundant research on leadership on the one hand and on networks/clusters on the other by investigating leadership in photonics clusters from a structuration perspective. Apart from giving an insight into the variety and patterns of leadership practices observed, the paper addresses the dilemma that regional innovation systems such as clusters usually have a critical need of some kind of leadership, but that neither individual nor organizational actors wish to be led. This dilemma can only be ‘managed’ by organizing for leading (in) clusters in a certain way

Gastrointestinal Stromal Tumors: Clinical Symptoms, Location, Metastasis Formation, and Associated Malignancies in a Single Center Retrospective Study

Background and Aims: Gastrointestinal stromal tumors (GISTs) are rare malignancies but the most common mesenchymal tumors of the digestive tract. Recent advances in diagnostic imaging and an increasing incidence will confront us more frequently with stromal tumors. This single center study aimed to characterize GIST patients in terms of tumor location, clinical presentation, metastasis formation, as well as associated secondary malignancies. Methods: In a retrospective study, 104 patients with a histologically confirmed diagnosis of GIST, collected between 1993 and 2011, were characterized for several clinical features. Results: The most common GIST location was the stomach (67.6%) followed by the small intestine (16.2%). Gastrointestinal bleeding (55.8%) and abdominal pain (38.5%) were the most frequently reported symptoms whereas about one-third of patients remained clinically asymptomatic (31.6%); 14.4% of patients had either synchronous or metachronous metastases and there was a significant prevalence also in the low risk group. The proportion of secondary malignant associated neoplasms was 31% in our GIST cohort, among which gastrointestinal, genitourinary tumors, and breast cancer were the most prevalent. Conclusion: There was a considerable risk for metastasis formation and the development of secondary neoplasias that should encourage discussion about the appropriate surveillance strategy after surgery for GIST

Helicobacter pylori infection associates with fecal microbiota composition and diversity

Helicobacter (H.) pylori is the most important cause for peptic ulcer disease and a risk factor for gastric carcinoma. How colonization with H. pylori affects the intestinal microbiota composition in humans is unknown. We investigated the association of H. pylori infection with intestinal microbiota composition in the population-based cohort Study-of-Health-in-Pomerania (SHIP)-TREND. Anti-H. pylori serology and H. pylori stool antigen tests were used to determine the H. pylori infection status. The fecal microbiota composition of 212 H. pylori positive subjects and 212 matched negative control individuals was assessed using 16S rRNA gene sequencing. H. pylori infection was found to be significantly associated with fecal microbiota alterations and a general increase in fecal microbial diversity. In infected individuals, the H. pylori stool antigen load determined a larger portion of the microbial variation than age or sex. The highest H. pylori stool antigen loads were associated with a putatively harmful microbiota composition. This study demonstrates profound alterations in human fecal microbiota of H. pylori infected individuals. While the increased microbiota diversity associated with H. pylori infection as well as changes in abundance of specific genera could be considered to be beneficial, others may be associated with adverse health effects, reflecting the complex relationship between H. pylori and its human host