The ecology of organizational demography: managerial tenure distributions and organizational competition

This paper argues that turnover processes in top managementteams create inter-organizational interdependencies. I arguethat managerial capabilities are shaped by their experiencesin a given competitive context; differences in managerial tenuretherefore lead to differences in managerial capabilities. Acomparison of the tenure distribution of a top management teamwith those of its competitors therefore captures the extentto which a firm relies on managerial capabilities similar tothose of its competitors. Overlap in managerial capabilitieswill lead to greater competition for resources, since managersshape a firm's pattern of resource utilization. I hypothesizethat organizational growth rates will decline to the extentthat competitors are crowded around a firm's location in thetenure distribution. Analyses of growth in viewership amongcommercial television stations support this claim.     

A novel approach to classify serum glycoproteins from patients infected by dengue using electrochemical impedance spectroscopy analysis

Electrochemical biosensor for serum glycoproteins (SG) from patients infected by dengue fever (DF) based on gold nanoparticles (AuNp) and polyvinyl butyral (PVB) adsorbed on gold electrodes has been investigated. Electrochemical impedance spectroscopy (EIS), in the frequency range from 100 mHz to 100 kHz, was performed on these electrodes, in phosphate buffer (PBS) solution containing 10 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆] (1:1) as a redox probe. The electrodes modified with AuNp–Con A–PVB–BSA–SG showed larger electron transfer resistances than those modified with AuNp–Con A–PVB–BSA. The impedance spectra showed an increase in the charge transfer resistance when Con A interacted with SG. Moreover, the charge transfer resistance obtained with DF was larger than that obtained with negative serum. The resulting biosensor is capable to recognize SG from patients infected by DF.     

Enhanced binding to DNA and topoisomerase I inhibition by an analog of the antitumor antibiotic rebeccamycin containing an amino sugar residue

Many antitumor agents contain a carbohydrate side chain appended to a DNA-intercalating chromophore. This is the case with anthracyclines such as daunomycin and also with indolocarbazoles including the antibiotic rebeccamycin and its tumor active analog, NB506. In each case, the glycoside residue plays a significant role in the interaction of the drug with the DNA double helix. In this study we show that the DNA-binding affinity and sequence selectivity of a rebeccamycin derivative can be enhanced by replacing the glucose residue with a 2'-aminoglucose moiety. The drug-DNA interactions were studied by thermal denaturation, fluorescence, and footprinting experiments. The thermodynamic parameters indicate that the newly introduced amino group on the glycoside residue significantly enhanced binding to DNA by increasing the contribution of the polyelectrolyte effect to the binding free energy, but does not appear to participate in any specific molecular contacts. The energetic contribution of the amino group of the rebeccamycin analog was found to be weaker than that of the sugar amino group of daunomycin, possibly because the indolocarbazole derivative is only partially charged at neutral pH. Topoisomerase I-mediated DNA cleavage studies reveal that the OH-->NH2 substitution does not affect the capacity of the drug to stabilize enzyme-DNA covalent complexes. Cytotoxicity studies with P388 leukemia cells sensitive or resistant to camptothecin suggest that topoisomerase I represents a privileged intracellular target for the studied compounds. The role of the sugar amino group is discussed. The study provides useful guidelines for the development of a new generation of indolocarbazole-based antitumor agents.     

Cardiac outcome in patients with subarachnoid hemorrhage and electrocardiographic abnormalities

OBJECTIVE: Approximately 25% of patients with subarachnoid hemorrhage (SAH) have electrocardiographic (ECG) abnormalities consistent with myocardial ischemia or myocardial infarction (MI), and their cardiac prognosis remains unclear. The objective of this study was to determine the cardiac and all-cause mortality rate of a series of patients with SAH with ECG changes consistent with ischemia or MI. METHODS: Using an existing database of patients with SAH and predetermined ECG criteria for ischemia or MI, a study group of patients with abnormal ECG results within 3 days of presentation and before aneurysm surgery was identified. Database patients without abnormal ECG results served as a control group. Cardiac mortality, defined as death resulting from arrhythmia, congestive heart failure, or cardiogenic shock, was assessed by chart review. RESULTS: Of 439 patients with SAH in the database, 58 met the criteria for the study group. Forty-one of these patients were treated neurosurgically. No deaths resulting from cardiac causes occurred, and 20 patients died as a result of noncardiac causes. In a multivariable analysis, age older than 65 years and Hunt and Hess grade of at least 3 were predictive of all-cause mortality. ECG abnormalities, however, were not a statistically significant predictor. CONCLUSION: In patients with SAH and ECG readings consistent with ischemia or MI, the risk of death resulting from cardiac causes is low, with or without aneurysm surgery. The ECG abnormalities are associated with more severe neurological injury but are not independently predictive of all-cause mortality.     

Viability and recovery of peripheral blood mononuclear cells cryopreserved for up to 12 years in a multicenter study

Polish physicians-philosophers tried to find a compromise between medicine as a science and medicine as a healing art. They stated that clinical practice should be transformed into science, bearing in mind that there would be no medicine without the existence of the sick. A perfect physician is a good and wise person and not exclusively a proficient expert. Polish physicians exercised a science that they called philosophy of medicine. It included logic, psychology, and medical ethics. The Polish school claimed that the history of medicine and philosophy of medicine are necessary for future doctors. The historical and philosophical approach makes it possible to recognize the subject of medicine (health, disease, and the sick) and its aim (treatment, restoration of health or just alleviation of suffering). The ethics teaches what values are pursued by medicine, what moral duties a doctor has, and what role model to follow to become a good physician. Placing the sick in the focus of medical interest, the Polish school taught future physicians to see in them suffering fellow men who should be embraced with care, compassion, and Christian charity. Such an approach to the ethical aspect of medical philosophy became incorporated into an education towards humane values, responsibility for ones' life and health in the spirit of the ethics of care.     

Using Behavioral Theories of Choice to Predict Drinking Outcomes Following a Brief Intervention.

Behavioral theories of choice predict that substance use is partly a function of the relative value of drugs in relation to other available reinforcers. This study evaluated this hypothesis in the context of predicting drinking outcomes following an alcohol abuse intervention. Participants (N=54, 69% female, 31% male) were college student heavy drinkers who completed a single-session motivational intervention. Students completed a baseline measure of substance-related and substance-free activity participation and enjoyment. Only women showed a significant reduction in drinking at the 6-month follow-up, and the ratio of substance-related to substance-free reinforcement accounted for unique variance in their drinking outcomes. Women who at baseline derived a smaller proportion of their total reinforcement from substance use showed lower levels of follow-up drinking, even after the authors controlled for baseline drinking level. Male and female participants who reduced their drinking showed increased proportional reinforcement from substance-free activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extracellular matrix regulates apoptosis in human neutrophils

BACKGROUND: During inflammation, polymorphonuclear neutrophils (PMNs) migrate into the affected tissue interacting with extracellular matrix (ECM) proteins. We tested the hypothesis that PMN-matrix interaction affects PMN apoptosis. METHODS: Apoptosis of human PMNs was detected by DNA-fragmentation assay and was quantitated by flow cytometry, ultraviolet and light microscopy. Cell adhesion was assessed by a toluidine blue assay, and cell spreading was detected by phase contrast microscopy. Protein tyrosine phosphorylation was studied using Western blotting and confocal microscopy. RESULTS: PMN apoptosis was not different in unstimulated cultures on either surface-adherent fibronectin or on PolyHema, a surface that prevents cell adherence. However, tumor necrosis factor-alpha (TNF alpha) treatment significantly increased apoptosis on fibronectin (37 +/- 4%) compared with PolyHema (20 +/- 3%). Tests on other matrix substances revealed that the percentage of apoptotic PMNs in the presence of TNF alpha was 8 +/- 1% on PolyHema, 26 +/- 4% on fibronectin, 17 +/- 2% on collagen I, 16 +/- 2% on collagen IV, and 16 +/- 3% on laminin (P < 0.05 for all matrices compared with PolyHema). Preincubation with genistein (50 microM) significantly inhibited TNF alpha-mediated apoptosis on fibronectin (39 +/- 4% to 21 +/- 4%) but not on PolyHema (21 +/- 4% to 16 +/- 4%). Genistein also reduced PMN spreading on fibronectin. In contrast, inhibitors of mitogen-activated protein kinase and protein kinase C showed no effect on PMN apoptosis. Fibronectin strongly increased tyrosine phosphorylation of three 102, 63, and 54 kDa proteins. Five newly tyrosine-phosphorylated 185, 85, 66, 56, and 42 kDa bands were also visible. Using confocal microscopy, highest tyrosine phosphorylation was localized to sites of cell-matrix interaction. CONCLUSIONS: ECM influences apoptosis in TNF alpha-activated, adherent, spreading PMNs. The process is regulated by tyrosine phosphorylation. Acceleration of apoptosis may shorten the PMN lifespan and thereby locally regulate inflammation.     

Polymorphic expression of the glutathione S-transferase P1 gene and its susceptibility to Barrett's esophagus and esophageal carcinoma

Factors determining individual susceptibility to esophageal cancer or premalignant Barrett's epithelium are still largely unclear. An imbalance between phase I drug metabolism [e.g., cytochrome P450 (CYP)] and phase II detoxification [e.g., glutathione S-transferase (GST)] may contribute to the development of these diseases. Polymorphic variants in the CYP1A1 gene were described leading to increased levels of bioactive compounds, whereas polymorphisms in GST genes often resulted in impaired detoxification. We studied the frequencies of polymorphic variants in CYP1A1, GSTP1, GSTT1, and GSTM1 genes in 98 patients with Barrett's epithelium and 34 patients with esophageal cancer. The results were compared with those obtained from 247 healthy blood donors. DNA was extracted, and PCR-RFLP methods were used to detect genetic polymorphisms. Chi2 analysis, Spearman rank correlation, and Wilcoxon rank sum tests were used for statistical evaluation. Polymorphisms in CYP1A1, GSTM1, and GSTT1 occurred at an equal frequency in patients and controls. Occurrence of the polymorphic GSTP1b variant in the GSTP1 gene resulted in a significantly lower GST enzyme activity (P < 0.05), and GSTP1b was found significantly more often in patients with Barrett's epithelium (70%; P < 0.001) and patients with esophageal adenocarcinoma (76%; P = 0.005), as compared to healthy blood donors (41%). In conclusion, presence of the GSTP1b allele leads to lower GST enzyme activity levels and, consequently, impaired detoxification. This most important esophageal GST isoform may, therefore, contribute to the development of Barrett's epithelium and adenocarcinoma.     

Technological autonomy and three definitions of technology

In this essay I argue that one way to comprehend popular discourse about new technologies is to explore the meanings of the term technology . I develop the need to interrogate the meaning of technology by contrasting studies of technological discourse with studies of scientific discourse. I delineate three meanings of technology assumed in popular and academic discourse: technology-as-instrumentality, technology-as-industrialization, and technology-as-novelty. Finally, I examine the deployment of these definitions by the Clinton administration as it promulgates and defends its policies regarding the Internet. I conclude by reflecting on the significance of popular equivocation on the meaning of technology for understanding the ideology of technology.