instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: Nonviral vectors based on polyethylenimine (PEI) usually contain an excess of PEI that is not complexed to DNA. Since unbound PEI contributes to cellular and systemic toxicity, purification of polyplexes from unbound PEI is desirable.', 'Size exclusion chromatography (SEC) was used to purify PEI polyplexes of free PEI. Transfection properties of purified polyplexes and the effect of free PEI on gene delivery were studied in vitro and in vivo after systemic application into mice.', 'SEC did not change the size and zeta-potential of polyplexes. Independent of the amount of PEI used for complex formation, purified PEI polyplexes had the same final PEI nitrogen/DNA phosphate ratio of 2.5. Notably, purified PEI polyplexes demonstrated low cellular and systemic toxicity. High transfection efficiency was achieved with purified polyplexes at high DNA concentrations (8-15 microg/ml). At low DNA concentrations (2-4 microg/ml) gene transfer with purified particles was less efficient than with polyplexes containing free PEI both in vitro and in vivo. Mechanistic studies showed that free PEI partly blocked cellular association of DNA complexes but was essential for the following intracellular gene delivery. Adding free PEI to cells treated with purified particles with a delay of up to 4 h resulted in significantly enhanced transfection efficiency compared with non-purified particles or purified particles without free PEI.\Question: Does purification of polyethylenimine polyplexes highlight the role of free polycations in gene transfer?
answer:
This study presents an efficient method to remove free PEI from PEI polyplexes by SEC. Our results from transfection experiments demonstrate that free PEI substantially contributes to efficient gene expression but also mediates toxic effects in a dose-dependent manner. Purified polyplexes without free PEI have to be applied at increased concentrations to achieve high transfection levels, but exhibit a greatly improved toxicity profile.

question:
Context: Epidemiological prospective data on cardiovascular (CV) events in elderly subjects from Mediterranean populations are lacking. We aimed to investigate 15-year incidence of CV events and to evaluate the association with CV risk factors in an elderly Mediterranean population.', 'The population of a small Sicilian village were enrolled, visited and a blood sample was drawn at baseline. CV events were recorded in the 15 years of follow-up. From 1351 subjects (75% of the resident population); 315 were in the age range 65-85 years; 266 subjects free from CV disease were analysed. Seventy-seven CV events were recorded in 73 out of 266 subjects, with a 19.7% rate (in 10 years). Hypertension (HTN) (hazards ratio=2.1) and diabetes mellitus (DM) (hazards ratio=1.8) were independently associated with CV events. Subjects with both DM and HTN showed a lower survival free of CV events compared to those with DM or HTN.\Question: Are hypertension and diabetes mellitus associated with cardiovascular events in the elderly without cardiovascular disease . Results of a 15-year follow-up in a Mediterranean population?
answer:
In a 15-year follow-up of an elderly Mediterranean population free from CV disease, diabetes mellitus and hypertension were related to CV events. The control of risk factors in the elderly needs to be reinforced to achieve better results in terms of CV prevention.

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Context: Upregulated CD64 expression on neutrophils is the most useful marker for acute bacterial infections and systemic inflammation. However, it is unknown whether CD64 is involved in the pathogenesis of acute pancreatitis (AP). This study was designed to determine whether CD64 is implicated in severe acute pancreatitis (SAP), and thus, is a suitable marker for SAP.', 'SAP was induced in rats with an intraperitoneal injection of L-arginine. CD64 expression in the rat pancreas was determined by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry. Additionally, the CD64 mRNA expression in peripheral blood leukocytes from 21 patients with mild acute pancreatitis (MAP) and 10 patients with SAP was investigated at the time of admission and during remission by qRT-PCR.', 'CD64 mRNA and protein expression in the pancreas was significantly higher in rats with SAP, compared to the controls. The CD64 expression was higher in the patients with SAP than in the patients with MAP. During remission, CD64 mRNA decreased in both the MAP and SAP patients. The area under the curve of CD64 expression for the detection of SAP was superior to both the Ranson and the Acute Physiology and Chronic Health Evaluation II scores.\Question: Is cD64 expression increased in patients with severe acute pancreatitis : clinical significance?
answer:
The CD64 level was significantly increased in correlation with the disease severity in SAP and may act as a useful marker for predicting the development of SAP.