The effect of ethylene oxide sterilization on electrospun vascular grafts made from biodegradable polyesters.

The study describes the detailed examination of the effect of ethylene oxide sterilization on electrospun scaffolds constructed from biodegradable polyesters. Different fibrous layers fabricated from polycaprolactone (PCL) and a copolymer consisting of polylactide and polycaprolactone (PLCL) were investigated for the determination of their mechanical properties, degradation rates and interaction with fibroblasts. It was discovered that the sterilization procedure influenced the mechanical properties of the electrospun PLCL copolymer scaffold to the greatest extent. No effect of ethylene oxide sterilization on degradation behavior was observed. However, a delayed fibroblast proliferation rate was noticed with concern to the ethylene oxide sterilized samples compared to the ethanol sterilization of the materials.

Effective AC needleless and collectorless electrospinning for yarn production.

Nanofibrous materials are essential components for a wide range of applications, particularly in the fields of medicine and material engineering. These include protective materials, sensors, cosmetics, hygiene, filtration and energy storage. The most widely used and researched technology in these fields is electrospinning. This method for producing fibers yields highly promising results thanks to its versatility and simplicity. Electrospinning is employed in multiple forms, among which needle and needleless direct current (DC) variants are the most distinctive. The former is based on the generation of just one single jet from a nozzle; hence this fabrication process is not very productive. The latter uses the destabilization of free liquid surfaces by means of an electric field, which enhances the throughput since it produces numerous jets, emitted from the surfaces of rollers, spheres, strings and spirals. However, although some progress in total producibility has been achieved, the efficiency of the DC method still remains relatively low. A further drawback of DC electrospinning is that both variants need a collector, which makes it difficult to combine DC electrospinning easily with other technologies due to the presence of the high field strength within the entire spinning zone. This paper describes our experiments with AC electrospinning. We show that alternating current (AC) electrospinning based on a needleless spinning-electrode provides a highly productive smoke-like aerogel composed of nanofibers. This aerogel rises rapidly from the electrode like a thin plume of smoke, without any need for a collector. Our work shows that AC needleless electrospinning gains its efficiency and collector-less feature thanks to the creation of a perpetually charge-changing virtual counter-electrode composed of the nanofibers emitted. High-speed camera recordings demonstrate the formation mechanism of the nanofibrous plume, which is wafted by an electric wind. This wind's velocity field is experimentally investigated. One potential use of AC needleless electrospinning is demonstrated here by spinning it into a yarn.

Elastic three-dimensional poly (ε-caprolactone) nanofibre scaffold enhances migration, proliferation and osteogenic differentiation of mesenchymal stem cells.

OBJECTIVES: We prepared 3D poly (ε-caprolactone) (PCL) nanofibre scaffolds and tested their use for seeding, proliferation, differentiation and migration of mesenchymal stem cell (MSCs). MATERIALS AND METHODS: 3D nanofibres were prepared using a special collector for common electrospinning; simultaneously, a 2D PCL nanofibre layer was prepared using a classic plain collector. Both scaffolds were seeded with MSCs and biologically tested. MSC adhesion, migration, proliferation and osteogenic differentiation were investigated. RESULTS: The 3D PCL scaffold was characterized by having better biomechanical properties, namely greater elasticity and resistance against stress and strain, thus this scaffold will be able to find broad applications in tissue engineering. Clearly, while nanofibre layers of the 2D scaffold prevented MSCs from migrating through the conformation, cells infiltrated freely through the 3D scaffold. MSC adhesion to the 3D nanofibre PCL layer was also statistically more common than to the 2D scaffold (P < 0.05), and proliferation and viability of MSCs 2 or 3 weeks post-seeding, were also greater on the 3D scaffold. In addition, the 3D PCL scaffold was also characterized by displaying enhanced MSC osteogenic differentiation. CONCLUSIONS: We draw the conclusion that all positive effects observed using the 3D PCL nanofibre scaffold are related to the larger fibre surface area available to the cells. Thus, the proposed 3D structure of the nanofibre layer will find a wide array of applications in tissue engineering and regenerative medicine.

Antithrombotic treatment in patients with atrial fibrillation as a risk factor of stroke.

For over two decades, valuable insights have been accumulated from epidemiologic studies and randomized trials about the risks and prevention of atrial fibrillation. Atrial fibrillation (AF) substantially raises the risk of stroke, most likely through an atrio-embolic mechanism. Warfarin and other members of its class of oral anticoagulants targeted at an international normalized ratio (INR) of 2.5 can abrogate the risk of stroke attributable to AF effectively and fairly safely. High-quality management of anticoagulation can be achieved in usual clinical care. These insights have important implications for the care of individual patients and more generally for public health. Future research is needed to specify the risk of stroke and hemorrhage among patients with AF better, particularly among older individuals, to optimize use of antithrombotic agents, and to define the role of recently developed antithrombotic drugs and invasive nondrug approaches (Tab. 3, Ref. 20). Full Text (Free, PDF) www.bmj.sk.

[QT interval dispersion in hypertensive diabetics and in patients with hypertension with chronic heart failure without diabetes]. / Disperzia QT intervalov u hypertonických diabetikov a u pacientov s hypertenziou bez diabetu s chronickým srdcovým zlyhaním.

AIM: Our aim was to: 1. compare QT dispersion from routine ECG in diabetic and no-diabetic patients with congestive heart failure, 2. describe associations between QT dispersion and circadian blood (BP) pressure variation in type 2 diabetic patients with congestive heart failure (CHF). PATIENTS AND METHODS: 122 patients admitted to hospital due to CHF in the period between years 2000-2001 have been divided into 2 groups: group 1:70 patients (m: 40, f: 30, mean age 64.7 +/- 9 years) with type II diabetes mellitus (DM), group 2:52 patients (m: 28, f:24, mean age 62.5 +/- 10.9 years) without DM. Diagnosis of CHF was made clinically and proved by ECG and ECHO (EF < 40%), DM was defined clinically or by using oral glucose tolerance test (75 g glucose, 2 h blood glucose > 11.1 mmol/l). The QT interval was measured from the beginning of the QRS complex to the end of the T wave from routine 12-lead ECG. QT intervals were corrected for heart rate using Bazett's formula. QT dispersion (QTd) and rate corrected QT dispersion (QTc) were defined as the difference between the maximum and minimum QT and QTc intervals, respectively. Ambulatory blood pressure (AMBP) was measured by an oscillometic technique. Diabetic patients with CHF were divided both according to below and above the median QTc dispersion (65 ms). STATISTICAL ANALYSIS: Chi-square and Student's t-test. Significant differences were assumed of p < 0.05. RESULTS: Both groups were matched by gender, age, duration and intensity of hypertension, the presence and intensity of obesity, hyperlipidemia (TC, TG, LDL-C, HDL-C) and smoking habits. Diabetic patients with CHF had significantly longer QTc interval (maximum and minimum), QT dispersion and QTc dispersion compared with non-diabetic patients with CHF. Diabetic patients with CHF with QTc dispersion > 65 ms had significantly higher night systolic (133 +/- 14 vs. 112 +/- 14) and diastolic (80 +/- 11 vs. 65 +/- 6) BP and significantly higher night/day ratio for both systolic (0.94 +/- 0.05 vs. 0.86 +/- 0.06) and diastolic (0.89 +/- 0.07 vs. 0.80 +/- 0.05) compared with diabetic patients with CHF with QTc dispersion < 65 ms. CONCLUSION: Diabetic patients with CHF are higher risk than non-diabetic. Our data describe both factors related to cardiovascular risk in diabetic patients with CHF-prolongation of the QT and QTc dispersion and reduced nocturnal blood pressure.

Is left ventricular hypertrophy a risk factor in hypertensive patients?

BACKGROUND: Left ventricular hypertrophy (LVH) is supposed to be a risk factor of cardiovascular (CV) complications in hypertensive patients. AIM: To compare clinical events in hypertensives with and without LVH. PATIENTS AND METHODS: 319 hypertensives with LVH (mean age 64.1+/-10.6 ys) and 177 hypertensives without LVH (mean age 62.5+/-11.3 ys). LVH defined by echo Penn convention as left ventricular mass index >134 g/m2 in men and >110 g/m2 in women. Clinical events--heart failure (EF<40 %), left ventricular diastolic dysfunction (echo-doppler: transmitral-flow where peak A>peak E), myocardial infarction (history, ECG, cardiac enzymes), chronic atrial fibrillation (more than 2 weeks duration), mitral regurgitation (echo) and renal involvement (creatininemia>120 micromol/l). The two groups of hypertensives were matched by demographic criteria, duration and intensity of hypertension, obesity, diabetes mellitus, lipid serum levels and smoking habits. RESULTS: There were statistically significant at least p<0.05 more CV events (heart failure, left ventricular diastolic dysfunction, myocardial infarction, chronic atrial fibrillation, and mitral regurgitation cases) and renal involvement in LVH-positive patients than in LVH-negative patients. CONCLUSION: LVH is a strong risk factor for clinical events in hypertensives, which necessitates their more intensive treatment, mainly with drugs producing also LVH regression. (Tab. 5, Ref. 48.)

[Heart failure in hypertensive patients with left ventricular hypertrophy]. / Srdcové zlyhanie u hypertonikov s hypertrofiou l'avej komory.

Left ventricular hypertrophy (LVH) is supposed to be a useful marker of cardiovascular complications during the course of hypertension. Authors compared the presence of heart failure, left ventricular diastolic dysfunction and chronic atrial fibrillation in hypertensive patients with and without left ventricular hypertrophy defined by echocardiography. Hospital records of 192 hypertensives treated in our medical department during years 1996-1999 were analysed. Left ventricular hypertrophy was defined by echocardiography (Penn convention) as left ventricular mass index > 134 g/m2 in men and > 110 g/m2 in women. Presence of LVH was found in 128 patients (mean age 65.9 years), absence of LVH in 64 patients (mean age 64.8 years). Both groups of hypertensives were matched by demographic parameters, by the presence of hyperlipidemia, by smoking habits. Hypertensive patients with left ventricular hypertrophy were more often treated by ACE inhibitors. There were statistically significant more patients with heart failure, left ventricular diastolic dysfunction and chronic atrial fibrillation in LVH-positive patients than in LVH-negative once. There was also statistically significant lower ejection fraction (50.3 +/- 11.4% vs 56.5 +/- 7.4%) in LVH-positive patients than in LVH-negative once. Left ventricular hypertrophy in patients with hypertension brings usually a complicated course of the disease with a high contribution to the development of chronic heart failure.

Relation of left ventricular hypertrophy to cardiovascular complications in diabetic hypertensives.

The presence of diabetes mellitus and other risk factors of atherosclerosis, such as obesity, smoking and hyperlipidemia, in hypertensive patients makes the prognosis worse. Authors compared the clinical findings in diabetic hypertensive patients with and without left ventricular hypertrophy, the presence of which was diagnosed and defined by echocardiography. The study is based on the analysis of hospital records of 115 hypertensive patients treated at our department during the period 1998-1999. Left ventricular hypertrophy (LVH) was defined by echocardiography as left ventricular mass index > 134 g/m2 in men and > 110 g/m2 in women. Left ventricular hypertrophy was found in 79 patients (mean age 64.6 ys) but not in 36 patients (mean age 63.3 ys). Both groups were matched as to age and sex, intensity and duration of hypertension and diabetes, obesity, smoking and hyperlipidemia. In LVH-positive patients, there was a statistically significant incidence of heart failure, mitral regurgitation and renal involvement and a more non-significant incidence of left ventricular diastolic dysfunction, myocardial infarction, chronic atrial fibrillation and stroke than in LVH-negative ones. Left ventricular hypertrophy usually complicates the course of hypertension. Authors recommend to investigate the presence of left ventricular hypertrophy in hypertensives as it carries a much more complicated course of the disease. (Tab. 5, Ref. 28.)

Mepacrine impairs neutrophil response after acute lung injury in rats. Effects on neutrophil migration.

Intraalveolar leukocytosis is integral in initiating and perpetuating airspace inflammatory reactions. We used intratracheal instillation of silica suspensions in adult male rats to cause neutrophil flux (32% increase over saline controls) without creating a protein leak, so simulating an early inflammatory response. We examined the in vivo effects of a known phospholipase A2 inhibitor (mepacrine) and the two mast cell active agents (cyproheptadine and reserpine) on lung lavage fluid chemotactic capability, alveolar macrophage (AM) production of chemotactic factor(s), and neutrophil diapedesis. Only mepacrine significantly depressed the leukocytosis (from 32% to 8% of total cells), with a similar diminution in AM chemotaxin production. Separate in vitro experiments using mepacrine-pretreated neutrophils and macrophages gave evidence that mepacrine: (1) diminishes neutrophil response to chemotaxin(s), (2) inhibits spontaneous, random neutrophil movement, and (3) diminishes macrophage-derived chemotactic factor production. These observations suggest that the earliest events in alveolar inflammatory reactions probably involve local production of chemotactic factors by AM, and that mepacrine's anti-inflammatory action results from inhibitory influences on both macrophage and neutrophil populations.

The neutrophil, friend or foe: pharmacologic manipulation.

We describe some features of neutrophil migration and their defense or injury mechanism in the lung. Employing an intratracheal silica instillation model in rats, we examined the effects on the silica-induced neutrophil migration of mepacrine, colchicine and reserpine on such migration in vivo and of mepacrine on phorbol-stimulated elastase release and superoxide anion generation by human neutrophils in vitro. Mepacrine sharply diminished neutrophil migration, O2 and elastase release. Colchicine produced variable effects on neutrophil migration which was unaffected by the mast cell agent reserpine. The implications for lung injury and therapy are discussed.