Effects of Substrate Mechanics on Contractility of Cardiomyocytes Generated from Human Pluripotent Stem Cells

Human pluripotent stem cell (hPSC-) derived cardiomyocytes have potential applications in drug discovery, toxicity testing, developmental studies, and regenerative medicine. Before these cells can be reliably utilized, characterization of their functionality is required to establish their similarity to native cardiomyocytes. We tracked fluorescent beads embedded in 4.4–99.7 kPa polyacrylamide hydrogels beneath contracting neonatal rat cardiomyocytes and cardiomyocytes generated from hPSCs via growth-factor-induced directed differentiation to measure contractile output in response to changes in substrate mechanics. Contraction stress was determined using traction force microscopy, and morphology was characterized by immunocytochemistry for α-actinin and subsequent image analysis. We found that contraction stress of all types of cardiomyocytes increased with substrate stiffness. This effect was not linked to beating rate or morphology. We demonstrated that hPSC-derived cardiomyocyte contractility responded appropriately to isoprenaline and remained stable in culture over a period of 2 months. This study demonstrates that hPSC-derived cardiomyocytes have appropriate functional responses to substrate stiffness and to a pharmaceutical agent, which motivates their use in further applications such as drug evaluation and cardiac therapies

Trends in prevalence of hepatitis B virus infection among Albanian blood donors, 1999-2009

<p>Abstract</p> <p>Background</p> <p>Hepatitis B virus (HBV) was among the first virus known to be transmitted by blood and blood productions. The objective of this study is to determine the trend of hepatitis B virus in blood donors.</p> <p>Materials and methods</p> <p>In this study 79274 blood donors were retrospectively evaluated for HBsAg. The donors were selected using personal questionnaire, physical examination and testing blood before donation. Blood banks records are used as source of information. The blood donors samples were analyzed for the presence of hepatitis B surface antigen (HBsAg) by commercial available kits ELISA method, third generation (from Abbott laboratory, Germany). A sample was considered as HBsAg positive when found twice repeatedly reactive. Reactive samples were not confirmed with addition tests.</p> <p>Results</p> <p>In the evaluation data, we found out that from 79274 of the total healthy blood donors, 15983 were voluntary donors, 52876 were family replacement donors and 10424 commercial blood donors. The prevalence of HBsAg in blood donors was 7.9%. It was increased steadily from 5.9% in 1999 to 9.1% in 2006 and decreased in 7.9% in 2009. According to blood donors status the HBsAg prevalence was 10.5% in commercial blood donors, 8.1% in voluntary donors and 8.6% in family replacement donors. The prevalence of anti-HBc in blood donors was 59.1%.</p> <p>Conclusion</p> <p>The prevalence of HBsAg was lower in voluntary non remunerate blood donors than commercial donors and family replacement blood donors. In FDs the prevalence was higher than VDs but lower than CDs. So, it is important to encourage the voluntary blood donors to become regularly blood donors.</p

Anaerobic digestion and gasification of seaweed

The potential of algal biomass as a source of liquid and gaseous biofuels is a highly topical theme, with over 70 years of sometimes intensive research and considerable financial investment. A wide range of unit operations can be combined to produce algal biofuel, but as yet there is no successful commercial system producing such biofuel. This suggests that there are major technical and engineering difficulties to be resolved before economically viable algal biofuel production can be achieved. Both gasification and anaerobic digestion have been suggested as promising methods for exploiting bioenergy from biomass, and two major projects have been funded in the UK on the gasification and anaerobic digestion of seaweed, MacroBioCrude and SeaGas. This chapter discusses the use of gasification and anaerobic digestion of seaweed for the production of biofuel

Enhanced evaporation of the condensate droplets within the asymmetrical shock wave zone

The present work is concerned with investigation into coupled phenomena occurring in the supersonic section of the de Laval nozzle, characterized by the presence of shock the flow of condensing steam. The numerical simulations results were compared with the experiment carried out by Dykas et al. in 2013 on the half arc nozzles. The present work includes simulations results of oscillation frequency of the shock wave and conditions for the enhancement evaporation of condensate within the asymmetrical shock wave. Novelty of our approach lies on modeling both the moment of initiation of a phase transition, as well as the moment of its reverse progress – called here revaporization of the condensate phase

Diagnosis of hepatitis B infections and monitoring of treatment

Worldside viral hepatitis is still recognized as a mojor problem particularly in developing countries. During the past two decades there has been important progress in the field of viral hepatitis; the adapatation of molecular biology techniques to viral hepatitis has proven to be of great utility in the diagnosis of 'classical' hepatitis viruses, in monitoring during treatment, and also in learning more about the 'new' viruses. Here, the progress and pitfalls of serologic and molecular diagnosis techniques for viral hepatitis, unusual profiles and benefits of quantitative DNA/RNA tests will be discussed. (C) 2001 Elsevier Science B.V. All rights reserved

Varicella seroprevalence in a random sample of the Turkish population

Chicken pox highly contagious and common throughout the world, is an infectious disease caused by varicella zoster virus (VZV). This study was conducted to determine the seroprevalence of VZV in a population under age 30 and to identify the relationship of VZV seroprevalence and several characteristics of the study subjects in nine provinces of Turkey. The sampling method of 30 clusters recommended for field studies was used for selecting subjects of a pre-determined number in the rural and urban areas in each province. For this, a total of 60 groups, 30 clusters in the rural and 30 in the urban areas were determined. It was planned that a total of 4800 subjects, including 600 subjects from five big provinces (Istanbul, Ankara, Izmir, Adana, Diyarbakir) and 450 subjects from the remaining smaller provinces (Samsun, Erzurum, Trabzon, Edirne), be included in the study. ELISA method was used to examine the blood samples for VZV seropositivity. Positive VZV seroprevalence was detected in 77.8% of 4387 subjects under age 30 in nine provinces of Turkey. There was no difference in seroprevalence rate between rural and urban areas. Seroprevalence was found to be 79.0% in urban areas and 76.3% in rural areas. Seroprevalence increased with age. Seroprevalence was 20% at the age of 1 year, subsequently increased to 40% at the age of 4 years, 60% at the age 6 years, 80% at the age of 8 years, 85% at the age of 10 years, and then remained at 85-90% in subjects over the age of 10 years. In order to develop vaccination protocols and take appropriate preventive health care measures against diseases in different countries, it is very important to know the seroprevalence of any disease for an individual country. (C) 2002 Elsevier Science Ltd. All rights reserved

Hepatitis B and measles seroprevalence among Turkish children

This study was performed to determine hepatitis B and measles seroprevalence among the population under 30 years of age in Turkey. Blood samples of 2,683 subjects from eight provinces of Turkey-were studied. Measles IgG was determined.by hemagglutinin-inhibition method, and hepatitits B surface antigen (HBsAg), anti-hepatitis B surface antibody (anti-HBs) and anti-hepatitis B core antibodies (anti-HBc) were determined by ELISA method. Overall seropositivity for measles was found to be 59.6%. There was a significant difference in seropositivity among provinces. The seropositivity was found to increase with age. The overall seiopositivities for HBsAg, anti-HBs and anti-HBc were found to be 5.4%, 17% and 15:1%, respectively. The seroprevalences differed significantly among provinces. Although seroprevalence for anti-HBs and anti-HBc increased with age, HBsAg seropositivity did not change significantly after one year of age.. Seroprevalence was not affected by sex. It was concluded that every effort should be given to vaccinate infants as early as possible for hepatitis B and that the coverage of infancy measles vaccination should be increased with a second dose