Home About us Contact
|
Home About us Contact | ||
|
|
||
Enhanced Survival (enhanced + survival)
Selected AbstractsEnhanced survival of vascular smooth muscle cells accounts for heightened elastin deposition in arteries of neonatal spontaneously hypertensive ratsEXPERIMENTAL PHYSIOLOGY, Issue 4 2010Silvia M. Arribas Abnormal stiffening and narrowing of arteries are characteristic features of spontaneously hypertensive rats (SHR). In this strain, we have previously demonstrated an increased elastin content and abnormal organization of lamellae in conduit and resistance arteries from neonatal rats that preceded the impending inward remodelling, increased vascular stiffness and development of hypertension. The aim of this study was to assess the mechanism responsible for such excessive and aberrant elastin deposition in SHR vessels during perinatal development. We compared elastin, collagen and fibronectin production (inmunocytochemistry and quantitative assay of metabolically labelled insoluble elastin), DNA content as well as cell proliferation (proliferative cellular nuclear antigen, bromodeoxyuridine incorporation) and death rates (propidium iodide exclusion test, terminal transferase nick and labeling (TUNEL) assay) in cultures of vascular smooth muscle cells (VSMC) derived from neonatal SHR and Wistar,Kyoto (WKY) control rats. Cultures of VSMC derived from neonatal SHR exhibited hypertrophy, produced more elastin, collagen and fibronectin and contained more DNA than equally plated WKY counterparts. Further analysis revealed that the higher net DNA content in SHR-derived cultures was due to increased diploidy, but not to a heightened cell multiplication. The SHR-derived VSMC also exhibited lower rates of cell death and apoptosis, which were associated with increased levels of the anti-apoptotic protein, survivin. We therefore conclude that the peculiar heightened survival of matrix-producing VSMC in neonatal SHR is responsible for accumulation of hard-wearing elastin and other extracellular matrix elements in the growing arteries, thereby contributing to the subsequent development of systemic hypertension. [source] Bacteriological quality of skin-moisturizing creams and lotions distributed in a tropical developing countryJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2001I.N. Okeke Aims: To evaluate the bacteriological quality of skin moisturizing products in the South-west part of Nigeria and study factors predisposing their bacterial contamination under tropical conditions. Methods and Results: Viable counts for bacteria exceeded 103 cfu ml,1or cfu g,1 in 8 (16·3%) commercially available creams and lotions at time of purchase. Escherichia coli (8), Pseudomonas spp. (7), Staphylococcus spp. (9) and Bacillus spp. (6) were the most commonly recovered bacteria. Following use by volunteers, the proportion of E. coli and other Gram-negative organisms recovered increased. Organic matter, particularly in the absence of preservatives, enhanced survival and growth of bacteria in creams stored under ambient tropical conditions during challenge experiments. Conclusions: Contaminated products are relatively uncommon but some products present a potential health hazard because they are unable to suppress the growth of organisms of likely faecal origin during use. Significance and Impact of the Study: Quality assurance during manufacture, pack size, preservative evaluation, organic matter and water content were identified as factors to be considered during the development of creams and lotions for use in tropical developing countries. [source] ACID TOLERANCE OF ESCHERICHIA COLI FOLLOWING COLD SHOCK TREATMENTJOURNAL OF FOOD SAFETY, Issue 2 2003GREG BLANK ABSTRACT The effect of an initial cold shock treatment (2 h at 10C), following an abrupt downshift in temperature from 37 to 10C, on the subsequent growth and survival of Escherichia coli strains O157:H7 and MY20 (Biotype 1) in acidified Trypticase soy broth (TSB) and fruit juices (orange, apple) was investigated. Overall, no difference in growth at 37C was observed between each cold shocked and noncold shocked E. coli strain when cultured in TSB adjusted with either acetic acid (pH 6.0)or malic, citric and tartaric acid (each adjusted to: pH 4.5, 5.0, 5.5, 6.0). However, significant (P ± 0.05) differences in survival were observed between cold shocked and noncold shocked populations in TSB acidified with acetic acid (pH 5.0) or citric, malic and tartaric acid (pH 4.0). For strain MY20, survivor levels for cold shocked cells in TSB acidified with acetic acid citric, malic and tartaric acid at 8C were significantly (P ± 0.05) higher than in noncold shocked populations. Also, at 37C survival levels for cold shocked cells were significantly (P ± 0.05) higher than noncold shocked cells in TSB acidified with either malic or tartaric acid (pH 4.0). For the O157:H7 strain, survivor levels were higher (P ± 0.05) for cold shocked cells when maintained in TSB at 37C regardless of acid type. At 8C, cold shock treatment only increased (P ± 0.05) the survival of the O157:H7 strain in TSB adjusted with acetic acid (pH 6.0). Acid cross protection induced by cold shocking, as evidenced by enhanced survival, was not apparent for either E. coil strain in apple (pH 3.5) or orange juice (pH 3.8) maintained at 8C. [source] Evidence for target-specific outgrowth from subpopulations of grafted human dopamine neuronsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 5 2001Ingrid Strömberg Abstract Clinical and experimental grafting in Parkinson's disease has shown the need for enhanced survival of dopamine neurons to obtain improved functional recovery. In addition, it has been suggested that a limited number of surviving dopamine neurons project to the dopamine-denervated host striatum. The aim of this study was to investigate if subpopulations of ventral mesencephalic dopamine neurons project to their normal targets, i.e., dorsal vs. ventral striatum. Following implantation of human ventral mesencepahlic tissue into the lateral ventricle of dopamine-depleted rats, human-derived dopamine reinnervation was achieved both in dorsal and ventral striatum. Treatment with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) resulted in a degeneration of tyrosine hydroxylase (TH)-immunoreactive nerve fibers in dorsal striatum but not in ventral areas in some animals, while MPTP was without effect in other animals. TH-immunoreactive neurons were small and appeared shrunken in animals carrying grafts affected by the MPTP treatment. In conclusion, grafted dopamine neurons projected nerve fibers into areas that they normally innervate. Thus, when searching for factors that may enhance survival of grafted dopamine neurons it is important to study which subpopulation(s) of ventral mesencephalic dopamine neurons is affected, such that a proper reinnervation may be achieved. Microsc. Res. Tech. 54:287,297, 2001. © 2001 Wiley-Liss, Inc. [source] CtsR controls class III heat shock gene expression in the human pathogen Listeria monocytogenesMOLECULAR MICROBIOLOGY, Issue 4 2000Shamila Nair Stress proteins play an important role in virulence, yet little is known about the regulation of stress response in pathogens. In the facultative intracellular pathogen Listeria monocytogenes, the Clp ATPases, including ClpC, ClpP and ClpE, are required for stress survival and intracellular growth. The first gene of the clpC operon of L. monocytogenes encodes a homologue of the Bacillus subtilis CtsR repressor of stress response genes. An L. monocytogenes ctsR -deleted mutant displayed enhanced survival under stress conditions (growth in the presence of 2% NaCl or at 42°C), but its level of virulence in the mouse was not affected. The virulence of a wild-type strain constitutively expressing CtsR is significantly attenuated, presumably because of repression of the stress response. Regulation of the L. monocytogenes clpC, clpP and clpE genes was investigated using transcriptional fusions in B. subtilis as a host. The L. monocytogenes ctsR gene was placed under the control of an inducible promoter, and regulation by CtsR and heat shock was demonstrated in vivo in B. subtilis. The purified CtsR protein of L. monocytogenes binds specifically to the clpC, clpP and clpE regulatory regions, and the extent of the CtsR binding sites was defined by DNase I footprinting. Our results demonstrate that this human pathogen possesses a CtsR regulon controlling class III heat shock genes, strikingly similar to that of the saprophyte B. subtilis. This is the first description of a stress response regulatory gene in a pathogen. [source] | ||||||||||