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Selected Abstracts

Mitochondrial function and apoptotic susceptibility in aging skeletal muscle

AGING CELL, Issue 1 2008
Béatrice Chabi
Summary During aging, skeletal muscle undergoes sarcopenia, a condition characterized by a loss of muscle cell mass and alterations in contractile function. The origin of these decrements is unknown, but evidence suggests that they can be partly attributed to mitochondrial dysfunction. To characterize the nature of this dysfunction, we investigated skeletal muscle contractile properties, subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondrial biogenesis and function, as well as apoptotic susceptibility in young (6 months old) and senescent (36 months old) Fischer 344 Brown Norway rats. Muscle mass and maximal force production were significantly lower in the 36-month group, which is indicative of a sarcopenic phenotype. Furthermore, contractile activity in situ revealed greater fatigability in the 36-month compared to the 6-month animals. This decrement could be partially accounted for by a 30% lower mitochondrial content in fast-twitch muscle from 36-month animals, as well as lower protein levels of the transcriptional coactivator peroxisome proliferator-activated receptor , coactivator-1,. Enzyme activities and glutamate-induced oxygen consumption rates in isolated SS and IMF mitochondria were similar between age groups. However, mitochondrial reactive oxygen species (ROS) production during state 3 respiration was ~1.7-fold greater in mitochondria isolated from 36-month compared to 6-month animals, and was accompanied by a 1.8-fold increase in the DNA repair enzyme 8-oxoguanine glycosylase 1 in fast-twitch muscle. Basal rates of release of cytochrome c and endonuclease G in SS mitochondria were 3.5- to 7-fold higher from senescent animals. These data suggest that the age-related sarcopenia and muscle fatigability are associated with enhanced ROS production, increased mitochondrial apoptotic susceptibility and reduced transcriptional drive for mitochondrial biogenesis. [source]

Effects of the fattening period on the fatty acid composition of fat deposits and free amino acid and inosinic acid contents of the longissimus muscle in carcasses of Japanese Black steers

ABSTRACT The effects of the fattening period on carcass characteristics, fatty acid composition of fat deposits, and muscle free amino acid (FAA) and inosinic acid (IMP) contents were evaluated in Japanese Black steers. Ten castrated, 10-month-old calves derived from the same sire were divided into five to be slaughtered at the age of 30 months after a 20-month fattening period (20-month group) and five to be slaughtered at the age of 34 months after a 24-month fattening period (24-month group). Concerning the fatty acid composition of subcutaneous fat, the percentage of palmitoleic acid was higher (P < 0.05) in the 24- than in the 20-month group, but no difference was noted in any other fatty acids. For intermuscular fat, no difference was observed in any fatty acids. The percentages of oleic acid and total monounsaturated fatty acid of intramuscular and perinephric fat were higher (P < 0.05) in the 24- than in the 20-month group. Of the FAAs in the longissimus thoracis muscle, the threonine and tyrosine contents were lower (P < 0.05) in the 24- than in the 20-month group. The IMP content was higher (P < 0.05) in the 24- than in the 20-month group, suggesting an effect of prolongation of the fattening period. [source]

Hepatitis A seroprevalence and its relationship with environmental factors in children of different age groups in Kahramanmaras, Eastern Mediterranean region of Turkey

D. Kaya
Summary., Hepatitis A infections are influenced by environmental and socioeconomic factors. Epidemiologic studies regarding hepatitis A virus (HAV) infection in Turkey have not previously examined these factors. We investigated HAV seroprevalence and its association with sociodemographic factors among children of various ages in the Eastern Mediterranean region of Turkey. The study included 1142 children (603 male and 539 female) between ages of 6 months and 18 years. Seropositivity in the whole group was 57.2%. HAV prevalence rates according to age groups were as follows: 35.5% in 6,23 months group, 19.2% in 2,5 years group, 74.3% in 6,10 years group, 83.0% in 11,14 years group, 92.8% in 15,18 years group. Risk factors that influenced seropositivity were; dense population, over-crowded families, excessive number of siblings, low socioeconomic status and low education of the mother. As HAV seroprevalence in children older than 6 years of age is high, we recommend hepatitis A vaccination in this region after the first year of life. [source]

2143: Corneal keratocyte population after laser subepithelial keratectomy (LASEK) with mitomycin C (MMC): 3 months vs 15 months comparison

Purpose To study corneal keratocyte population after LASEK with mitomycin C (MMC) 15 months vs 3 months after surgery Methods Sixty eyes were included in this study, all of them treated with LASEK with intraoperative 0.02% MMC, divided into 2 groups. 32 eyes had LASEK performed 3 months before, versus 28 in the 15 months post-op group. Keratocyte density was examined by using confocal microscopy in the anterior, mid and posterior stroma in both groups, and the mean density was compared with a control group of healthy eyes Results Keratocyte density in the anterior stroma was 16993,75+ 8001,7 cells/mm3 and 18529,1 + 2917,7 cells/mm3(p=0,3) in the 3 months and in the 15 months groups respectively, in the mid stroma it was 30783,3+ 9300 cells/mm3 in the 3 months and 20754,7 + 3615,3 cells/mm3 in the 15 months groups (p= 0,0001) and 30286,75+ 8321 cells/mm3and 19994+ 3085,9 cells/mm3 (p= 0,0001) in the posterior stroma in the 3 months and in the 15 months groups respectively. The comparison between the average densities through the whole cornea showed statistically significant difference between the 3 months vs 15 months group and 3 months vs normals, but it was not statistically significant different between 15 months vs normals Conclusion The changes in the corneal keratocyte population after LASEK + MMC seen in the early post-op, seem to change towards the normal values 15 months after the procedure. [source]