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Compensatory Effect (compensatory + effect)
Selected AbstractsAbsence of oligodendroglial glucosylceramide synthesis does not result in CNS myelin abnormalities or alter the dysmyelinating phenotype of CGT-deficient miceGLIA, Issue 4 2010Laleh Saadat Abstract To examine the function of glycosphingolipids (GSLs) in oligodendrocytes, the myelinating cells of the central nervous system (CNS), mice were generated that lack oligodendroglial expression of UDP-glucose ceramide glucosyltransferase (encoded by Ugcg). These mice (Ugcgflox/flox;Cnp/Cre) did not show any apparent clinical phenotype, their total brain and myelin extracts had normal GSL content, including ganglioside composition, and myelin abnormalities were not detected in their CNS. These data indicate that the elimination of gangliosides from oligodendrocytes is not detrimental to myelination. These mice were also used to asses the potential compensatory effect of hydroxyl fatty acid glucosylceramide (HFA-GlcCer) accumulation in UDP-galactose:ceramide galactosyltransferase (encoded by Cgt, also known as Ugt8a) deficient mice. At postnatal day 18, the phenotypic characteristics of the Ugcgflox/flox;Cnp/Cre;Cgt,/, mutants, including the degree of hypomyelination, were surprisingly similar to that of Cgt,/, mice, suggesting that the accumulation of HFA-GlcCer in Cgt,/, mice does not modify their phenotype. These studies demonstrate that abundant, structurally intact myelin can form in the absence of glycolipids, which normally represent over 20% of the dry weight of myelin. © 2009 Wiley-Liss, Inc. [source] Renal impairment in deoxycorticosterone acetate-salt hypertensive ratsNEPHROLOGY, Issue 4 2000Catherine Dallemagne Summary: This study has compared renal function in deoxycorticosterone (DOCA)-salt hypertensive Wistar rats (uninephrectomy followed by administration of DOCA 25 mg subcutaneously every fourth day and 1% NaCl in the drinking water) with various control rats using the isolated perfused kidney preparation. The systolic blood pressure of DOCA-salt hypertensive rats was 180 ± 10 mmHg (uninephrectomy controls: 136 ± 9 mmHg) while normalization of calcium intake (DOCA-Ca rats, 1% CaCl2 in water) attenuated this increase (systolic blood pressure, 146 ± 5 mmHg). Renal mass corrected for body weight increased by 25% after uninephrectomy, 55% in uninephrectomized rats given NaCl, 152% in DOCA-salt rats and 147% in DOCA-Ca rats. At a renal perfusion pressure of 135 mmHg, isolated perfused kidneys from DOCA-salt rats showed decreases of 48% in glomerular filtration rate and 69% in sodium excretion with an increase of 44% in renal vascular resistance compared with uninephrectomized rats. There were no significant differences in renal function between DOCA-salt and DOCA-Ca rats. Histological assessment of renal pathology showed proximal tubular hypertrophy and hyperplasia, marked focal distal tubular atrophy, interstitial fibrosis and glomerular hypercellularity in DOCA rats compared with UNX rats. Lesions were less obvious in UNX-salt or DOCA-Ca rats. The lack of direct correlation between alterations in function and pathology may be explained by the compensatory effect of remaining healthy or hypertrophied nephrons. Thus, the DOCA-salt model of hypertension in rats is associated with marked structural kidney damage and severely decreased kidney function. Marked attenuation of systemic hypertension by normalizing calcium intake in DOCA-salt rats did not prevent impairment of kidney function. [source] Calcium and Exercise Affect the Growing SkeletonNUTRITION REVIEWS, Issue 11 2005Jo M. Welch PhD Adequate dietary calcium and bone-stimulating exercise during growth are known to affect skeletal development, but the combined effects of dietary calcium and osteogenic exercise have received scant attention. Animal research has showed a compensatory effect of impact loading on calcium-deprived bones, while various human studies have suggested compensatory, additive, or possibly synergistic effects in certain skeletal locations. Current evidence suggests that the best strategy for strong bones by the end of childhood may be either high-impact exercise with a moderate or greater calcium intake or a combination of moderate-impact exercise and adequate calcium during growth. [source] Persistence of growth stunting in a Peruvian high altitude community, 1964,1999AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2010Ivan G. Pawson The growth of children living in Nuñoa, a Peruvian high-altitude community, was studied over a 35-year period using data collected in 1964 and 1999. There had been evidence of a secular trend in growth in the mid-1980s, but this was before a period of sociopolitical upheaval lasting until the late 1990s partly linked to the activities of the Shining Path group and the Peruvian government's response. Anthropometric data for 576 children examined in 1964,1966 were compared with data from 361 children examined in 1999. Data were converted to Z Scores using NCHS/WHO reference standards. Compared with the 1964 cohort, boys in 1999 had marginally greater height Z Scores, but among females, the trend was reversed. Stunting prevalence had decreased from 1964 levels, but still approached 60% in both sexes, among the highest rates recorded for a modern world population. The prevalence of low weight for height was less than expected, possibly because of the compensatory effect of enlarged chest diameter. This anatomical feature may represent the effect of chronic hypoxic stress, causing growth of the chest cavity at the expense of growth in height. In view of modest improvements during the late 1980s in this population, we believe that the relatively poor growth status of children a decade later may result from food disruption associated with later political instability. Compared with children in a nearby community, which benefits from the socioeconomic infrastructure associated with a large copper mine, Nuñoa children continue to fare relatively poorly. Am. J. Hum. Biol. 2010. © 2009 Wiley-Liss, Inc. [source] Assessing in vivo Fertilizing Capacity of Liquid-Preserved Boar Semen According to the ,Hanover Gilt Model'REPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2003F Ardón Contents The goal of this study was to determine the ability of the Hanover gilt model to assess in vivo fertilizing capacity of preserved sperm and to consider whether any modifications to this model were needed. This model evaluates the fertilizing capacity of semen based on the fertilization rate, the rate of normal embryos and the accessory sperm count of 3,5-day embryos. Its distinguishing characteristics are the use of one-time insemination of sperm in reduced numbers, of spontaneously ovulating gilts and of ovulation detection through ultrasound examination of ovaries. Reduced sperm numbers allow for an accurate evaluation of the fertilizing potential of different semen treatments, thereby avoiding the compensatory effect of doses calibrated to maximize fertility. The model's usefulness was assessed in a trial run designed to compare the fertilizing capacity of liquid boar semen diluted into two different extenders. The diluent, the boar and the backflow, had no significant effect on any of the parameters studied. Gilts inseminated less than 24 h before ovulation had a significantly higher (p < 0.01) fertilization rate and accessory sperm cell count (p < 0.05) than those inseminated more than 24 h before ovulation. Very good/good embryos from homogeneous litters (only very good/good embryos were present) had a significantly higher (p < 0.01) accessory sperm count than those from heterogeneous litters (at least one embryo was of a different quality and/or oocytes were present). Both very good/good and degenerated/retarded embryos from heterogeneous litters had low accessory sperm numbers. This suggests that accessory sperm count is significantly related to the quality of the litter, but not to the quality of the embryo within gilts. It can be concluded that the Hanover gilt model is sensitive enough to show fertility differences (in this study, those associated with in vivo ageing of semen), while using relatively few gilts and little time. [source] Internal Kinematics of the Tongue Following Volume ReductionTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2008Volodymyr Shcherbatyy Abstract This study was undertaken to determine the functional consequences following tongue volume reduction on tongue internal kinematics during mastication and neuromuscular stimulation in a pig model. Six ultrasonic-crystals were implanted into the tongue body in a wedge-shaped configuration which allows recording distance changes in the bilateral length (LENG) and posterior thickness (THICK), as well as anterior (AW), posterior dorsal (PDW), and ventral (PVW) widths in 12 Yucatan-minipigs. Six animals received a uniform mid-sagittal tongue volume reduction surgery (reduction), and the other six had identical incisions without tissue removal (sham). The initial-distances among each crystal-pairs were recorded before, and immediately after surgery to calculate the dimensional losses. Referring to the initial-distance there were 3,66% and 1,4% tongue dimensional losses by the reduction and sham surgeries, respectively. The largest deformation in sham animals during mastication was in AW, significantly larger than LENG, PDW, PVW, and THICK (P < 0.01,0.001). In reduction animals, however, these deformational changes significantly diminished and enhanced in the anterior and posterior tongue, respectively (P < 0.05,0.001). In both groups, neuromuscular stimulation produced deformational ranges that were 2,4 times smaller than those occurred during chewing. Furthermore, reduction animals showed significantly decreased ranges of deformation in PVW, LENG, and THICK (P < 0.05,0.01). These results indicate that tongue volume reduction alters the tongue internal kinematics, and the dimensional losses in the anterior tongue caused by volume reduction can be compensated by increased deformations in the posterior tongue during mastication. This compensatory effect, however, diminishes during stimulation of the hypoglossal nerve and individual tongue muscles. Anat Rec, 291:886-893, 2008. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||