336 research outputs found
An operationalization of Stevenson’s conceptualization of entrepreneurship as opportunity-based firm behavior
No full textThis is the author-version of article published as: Brown, Terrence and Davidsson, Per and Wiklund, Johan (2001) An operationalization of Stevenson’s conceptualization of entrepreneurship as opportunity-based firm behavior. Strategi
Apolipoproteins A-I and B: biosynthesis, role in the development of atherosclerosis and targets for intervention against cardiovascular disease
No full textSven-Olof Olofsson, Olov Wiklund, Jan BorénSahlgrenska Center for Cardiovascular and Metabolic Research, the Wallenberg Laboratory University of GöteborgAbstract: Apolipoprotein (apo) AI and apoB are the major apolipoproteins of high-density lipoprotein (HDL) and low-density lipoprotein (LDL), respectively. ApoB assembles the precursor of LDL, very-low-density lipoprotein (VLDL), in the liver. The assembly starts with the formation of a primordial particle, which is converted to VLDL2. The VLDL2 particle is then transferred to the Golgi apparatus and can either be secreted or converted to triglyceriderich VLDL1. We have reviewed this assembly process, the process involved in the storage of triglycerides in cytosolic lipid droplets, and the relationship between these two processes. We also briefly discuss the formation of HDL. ApoB mediates the interaction between LDL and the arterial wall. Two regions in apoB are involved in this binding. This interaction and its role in the development of atherosclerosis are reviewed. ApoB can be used to measure the number of LDL or VLDL particles present in plasma, as there is one molecule of apoB on each particle. By contrast, the amount of cholesterol and other lipids on each particle varies under different conditions. We address the possibility of using apoAI and apoB levels to estimate the risk of development of cardiovascular diseases and to monitor intervention to treat these diseases.Keywords: Apolipoprotein AI, atherosclerosis, cardiovascular diseas
Conceptual and Empirical Challenges in the Study of Firm Growth
No full textWhen the first author reviewed the literature on small firm growth in the mid 1980’s for his disserta-tion work, he noted that surprisingly few studies had focused on that specific problem (Davidsson 1989a; 1989b). Today, this is no longer true. In recent years ever more comprehensive lists of studies have been compiled and reviewed. Storey (1994) compiled results from more than 25 studies. Delmar (1997) scrutinized the operationalizations of growth in 55 studies. The second author of the present manuscript recently reviewed and classified close to 70 studies for his dissertation work (Wiklund, 1998), while Ardishvili, Cardozo, Harmon & Vadakath (1998) included in their classification a full 105 published and unpublished studies focusing on new and/or small firm growth. \ud
However, rather than presenting a set of solid generalizations on the causes and effects of growth, these reviewers all tend to come up with relatively critical accounts. These criticisms concern both theoretical and methodological shortcomings. (Storey, 1994, p. 5; 125, Cooper, 1995, p. 120; Delmar (1997, pp. 205; 212; Wiklund, 1998, pp. 6-7; 19; Ardishvili et al, 1998, p. 1) \ud
In addition to the above evaluations of research specifically on growth, we also have the observation that longitudinal designs are generally lacking in entrepreneurship research (Cooper 1995, p. 112; Wik-lund 1998, p. 7). In the latest ‘State-of-the-Art’ volume, several authors mentioned the lack of longitu-dinal studies in entrepreneurship research as a major impediment (Aldrich & Baker, 1997, p. 389; Sex-ton, 1997, p. 407) \ud
As a result of the shortcomings pointed out by the critics, it is still true today that knowledge about what facilitates and hinders growth is still scattered and limited. The same is true for insights into the process of firm growth. Apparently, the large number of empirical studies has not given a very high yield of generalizable knowledge. This suggests that researchers who set out to contribute meaningfully to this line of empirical research have a number of challenges to deal with. On the basis of the criticism summarized above we would suggest that some of the more important challenges are the following:\ud
• to develop a satisfactory basic research design\ud
• to apply a well-founded conceptualization of growth, which in turn requires a well thought-out con-ceptualization of ‘the firm’\ud
• to adequately match this conceptualization with the purpose of the study, the theories used, and the operationalization of growth.\ud
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In the remainder of this chapter we will elaborate our views on these challenges. In the next section we will argue that growth studies need to be longitudinal, and why this is so. We will then turn to the conceptualization of the firm and the unit of analysis in growth studies, which turns out to be a really difficult problem. After that we discuss theoretical perspectives and how these match with different conceptualizations of the firm. Finally, we turn to operationalization issues, i.e. the choice of growth indicators, specific ways to model growth trajectories, and the distinction between organic and acquired growth. Throughout, we also discuss how these issues relate to different purposes, i.e. whose knowl-edge interests the study aims to satisfy
[New agents against atherosclerosis tested. Alarming findings, ACAT inhibitors seem to have proatherogenic effects]
No full textElderly benefit from lower LDL-cholesterol
No full textIn two recent publications LDL-cholesterol and cardiovascular risk in the elderly was studied. A study from Copenhagen shows that LDL-cholesterol is similar as a risk-factor for myocardial infarction in all age-groups. Due to the higher incidence of myocardial infarction with age, the number of events associated with an increased LDL is higher among the elderly. The effect of LDL reduction in the elderly was studied in a meta-analysis including statin studies as well as studies with ezetimibe and PCSK9 inhibitors. The relative risk reduction associated with a reduction of 1 mmol/l of LDL-cholesterol was 26%, similar for patients above or below 75 years of age. These studies emphasize that reduction of LDL should be considered also in the elderly without many comorbidities
Statin treatment, reduced T-cell content of atherosclerotic plaques and cancer - Response by authors
No full textLika huvudbudskap i riktlinjer för lipider för hjärt-kärlprevention. Europeiska och amerikanska rekommendationer utgår från riskstratifiering. Equal key messages in guidelines for lipids for cardiovascular prevention. European and American recommendations are based on risk stratification
No full textEuropeiska och amerikanska riktlinjer för lipidbehandling i kardiovaskulär prevention fokuserar på aktiv behandling med statiner stratifierad efter absolut risk för kardiovaskulär sjukdom. Risken värderas med riskalgoritmer. Behandlingsintensitet för olika riskgrupper är väsentligen kongruenta mellan de olika riktlinjerna. De amerikanska riktlinjerna rekommenderar intensiv statinbehandling vid hög eller mycket hög risk, medan de europeiska definierar målvärden för LDL, med lägre målvärden för patienter med mycket hög eller hög risk. Bägge riktlinjerna rekommenderar aktiv uppföljning och monitorering av LDL-reduktion under behandling
[Determination of apolipoproteins: An important tool for prevention and treatment of cardiovascular diseases]
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