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Increased Viability (increased + viability)

Distribution by Scientific Domains

Medical Sciences	50%
Life Sciences	50%

Selected Abstracts

Collagenase-Assisted Fat Dissociation for Autologous Fat Transfer

DERMATOLOGIC SURGERY, Issue 10 2008
DAVID K. MOSCATELLO PHD
BACKGROUND The quality of fat for autologous transfer procedures has been a major focus of research in the past few years. The primary goal of these efforts is to improve the viability and longevity of the graft in human subjects. One possible factor in the permanence of theses transplants is the size of the adipose tissue grafts. OBJECTIVE This study evaluated the effects of collagenase digestion on the viability of human adipose tissue. MATERIALS AND METHODS Samples of fat were obtained from subjects undergoing tumescent liposuction. The tissue was digested in a variety of concentrations of collagenase using optimized methods of processing. The digested fat was also subjected to mock injections through small bore needles. RESULTS Eight subjects completed the study. The viability of the fat using the optimized methods of collagenase digestion was consistently higher than 79%. During the mock injection trials, the viability of fat was improved from approximately 17% to 84% by collagenase digestion. CONCLUSIONS Our results show increased viability of human adipose tissue when digested by collagenase. These techniques can be applied to human autologous lipoaugmentation procedures in an effort to improve longevity of the transplanted tissue. [source]

Response to alkaline stress by root canal bacteria in biofilms

INTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2007
L. E. Chávez de Paz
Abstract Aim, To determine whether bacteria isolated from infected root canals survive alkaline shifts better in biofilms than in planktonic cultures. Methodology, Clinical isolates of Enterococcus faecalis, Lactobacillus paracasei, Olsenella uli, Streptococcus anginosus, S. gordonii, S. oralis and Fusobacterium nucleatum in biofilm and planktonic cultures were stressed at pH 10.5 for 4 h, and cell viability determined using the fluorescent staining LIVE/DEAD BacLight bacterial viability kit. In addition, proteins released into extracellular culture fluids were identified by Western blotting. Results,Enterococcus faecalis, L. paracasei, O. uli and S. gordonii survived in high numbers in both planktonic cultures and in biofilms after alkaline challenge. S. anginosus, S. oralis and F. nucleatum showed increased viability in biofilms compared with planktonic cultures. Alkaline exposure caused all planktonic cultures to aggregate into clusters and resulted in a greater extrusion of cellular proteins compared with cells in biofilms. Increased levels of DnaK, HPr and fructose-1,6-bisphosphate aldolase were observed in culture fluids, especially amongst streptococci. Conclusions, In general, bacteria isolated from infected roots canals resisted alkaline stress better in biofilms than in planktonic cultures, however, planktonic cells appeared to use aggregation and the extracellular transport of specific proteins as survival mechanisms. [source]

Can maternally transmitted endosymbionts facilitate the evolution of haplodiploidy?

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2006
J. ENGELSTÄDTER
Abstract Whilst many invertebrate taxa are haplodiploid, the factors underlying the evolution of haplodiploidy remain unresolved. We investigate theoretically whether haplodiploidy might evolve as an outcome of the co-evolution between maternally inherited endosymbionts and their hosts. First, we substantially extend a recently developed model that involves maternally inherited endosymbionts that kill male offspring by eliminating the paternal genome. We also put forward a new hypothesis and develop a model that involves bacteria that induce cytoplasmic incompatibility (CI). Based on these models, we explore the co-evolutionary events that might occur between hosts and symbionts. We find that both with male-killers and CI-inducing endosymbionts, the hosts are likely to develop increased viability of haploid males, which can be considered a preadaptation to haplodiploidy. In addition, populations with haploidizing male-killers can in some cases evolve directly towards a genetic system of paternal genome elimination, a special form of haplodiploidy. These results are combined with consideration of mechanism and ecology to appraise the likelihood of male-killers and CI inducing bacteria being involved in the evolution of haplodiploidy. [source]

Production of succinic acid at low pH by a recombinant strain of the aerobic yeast Yarrowia lipolytica

BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2010
Tigran V. Yuzbashev
Abstract Biotechnological production of weak organic acids such as succinic acid is most economically advantageous when carried out at low pH. Among naturally occurring microorganisms, several bacterial strains are known to produce considerable amounts of succinic acid under anaerobic conditions but they are inefficient in performing the low-pH fermentation due to their physiological properties. We have proposed therefore a new strategy for construction of an aerobic eukaryotic producer on the basis of the yeast Yarrowia lipolytica with a deletion in the gene coding one of succinate dehydrogenase subunits. Firstly, an original in vitro mutagenesis-based approach was proposed to construct strains with Ts mutations in the Y. lipolytica SDH1 gene. These mutants were used to optimize the composition of the media for selection of transformants with the deletion in the Y. lipolytica SDH2 gene. Surprisingly, the defects of each succinate dehydrogenase subunit prevented the growth on glucose but the mutant strains grew on glycerol and produced succinate in the presence of the buffering agent CaCO3. Subsequent selection of the strain with deleted SDH2 gene for increased viability allowed us to obtain a strain capable of accumulating succinate at the level of more than 45,g,L,1 in shaking flasks with buffering and more than 17,g,L,1 without buffering. The possible effect of the mutations on the utilization of different substrates and perspectives of constructing an industrial producer is discussed. Biotechnol. Bioeng. 2010;107:673,682. © 2010 Wiley Periodicals, Inc. [source]