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31.
Laputková G Legin M Sabo J 《Acta medica (Hradec Králové) / Universitas Carolina, Facultas Medica Hradec Králové》2004,47(4):323-326
The influence of D-glucose on a lipid solid support system with the aid of impedance spectrocopy as a preliminary attempt for the biosensing of medical relevant molecules was studied. In spite of some shortcomings, s-BLM's proved to be an appropriate model for the study of lipid membrane-D-glucose interactions. The shortcomings were the roughness of the metal support, and the lack of homogeneity in the monolayer or multilayer lipid structures. 相似文献
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Calorie restriction (CR) extends the life span of various species through mechanisms that are as yet unclear. Recently, we have reported that mitochondrion-mediated apoptosis was enhanced in alphaMUPA transgenic mice that spontaneously eat less and live longer compared with their wild-type (WT) control mice. To understand the molecular mechanisms underlying the increased apoptosis, we compared alphaMUPA and WT mice for parameters associated with SOD2 (MnSOD), a mitochondrial antioxidant enzyme that converts superoxide radicals into H(2)O(2) and is also known to inhibit apoptosis. The SOD2-related parameters included the levels of SOD2 mRNA, immunoreactivity and enzymatic activity in the liver, lipid oxidation and aconitase activity in isolated liver mitochondria, and the sensitivity of the mice to paraquat, an agent that elicits oxidative stress. In addition, we compared the mice for the levels of SOD2 mRNA after treatment with bacterial lipopolysaccharides (LPS), and for the DNA binding activity of NFkappaB as a marker for the inflammatory state. We extended SOD2 determination to the colon, where we also examined the formation of pre-neoplastic aberrant crypt foci (ACF) following treatment with dimethylhydrazine (DMH), a colonic organotypic carcinogen. Overall, alphaMUPA mice showed reduced basal levels of SOD2 gene expression and activity concomitantly with reduced lipid oxidation, increased aconitase activity and enhanced paraquat sensitivity, while maintaining the capacity to produce high levels of SOD2 in response to the inflammatory stimulus. alphaMUPA mice also showed increased resistance to DMH-induced pre-neoplasia. Collectively, these data are consistent with a model, in which an optimal fine-tuning of SOD2 throughout a long-term regimen of reduced eating could contribute to longevity, at least in the alphaMUPA mice. 相似文献
34.
The role of IL-18 and IL-12 in the modulation of matrix metalloproteinases and their tissue inhibitors in monocytic cells 总被引:5,自引:0,他引:5
The matrix metalloproteinases (MMP) are enzymes crucial for the physiological patrol as well as pathological chemotaxis of immune cells to target tissues. The present study examined differential effects of pro-inflammatory [IL-18, IL-12 and tumor necrosis factor (TNF)-alpha] versus anti-inflammatory (IL-4) cytokines on the modulation of MMP and their endogenous tissue inhibitors (TIMP) expression in the U937 cell line. IL-18 and IL-12 separately and synergistically enhanced MMP-2, while TNF-alpha led to the elevation of MMP-9. All pro-inflammatory cytokines enhanced MT1-MMP expression and IL-4 suppressed TNF-alpha-induced MMP-9 expression. This study demonstrated that elevated IL-18 and IL-12, and related pro-inflammatory activity, may be associated with aberrant MMP activity, suggesting modulation of MMP expression using IL-12 and IL-18 antagonists as future therapeutic strategies to attenuate inflammatory and autoimmune disorders. 相似文献
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Daniel L. Van Dyke Anne Wiktor Catherine G. Paliner Dorothy A. Miller Michal Witt V. Ramesh Babu Maria J. Worsham Jacquelyn R. Roberson Lester Weiss 《American journal of medical genetics. Part A》1992,43(6):996-1005
Since some patients with Ullrich-Turner syndrome (UTS) have mental retardation, we reviewed our experience to look for a high-risk subgroup. Among 190 UTS and gonadal dysgenesis patients with X chromosome abnormalities, 12 had mental retardation. All of the six (100%) with a small ring X were educable (EMI) or trainable mentally impaired (TMI) with more severe delay than expected in UTS. Among the 184 with other X abnormalities, only 6 had similar delays (2 from postnatal catastrophes), for a frequency of 3.3% mental retardation among those without a small ring X; only 2.2% of these had unexplained mental retardation. Polymerase chain reaction studies showed no Y-derived material in the 2 patients who were evaluated, and in situ hybridization confirmed X origin of the ring in the 6 subjects who were evaluated. We describe the phenotype of the 6 individuals with a small ring X, and an additional 2 patients with a small ring X who were identified outside the survey. The subjects with a small ring X comprised a clinically distinct subgroup which had EMI/TMI and shorter stature than expected in UTS. Seizures and a head circumference <10th centile were observed in half of the patients with a small ring X, and strabismus, epicanthus, and single palmar creases were present in more than half. A “triangular” face in childhood, pigmentary dysplasia, sacral dimple, and heart defects were also common. Neck webbing appeared to be less frequent than in 45, X. We hypothesize that the high risk of mental retardation in this form of the UTS results from lack of lyonization of the ring X due to loss of the X inactivation center. Excluding those with a small ring X, mental retardation is not significantly increased in patients with UTS. © 1992 Wiley-Liss, Inc. 相似文献
39.
H. Wald Michal Dranitzki-Elhalel R. Backenroth Mordecai M. Popovtzer 《Pflügers Archiv : European journal of physiology》1998,436(2):289-294
Vitamin D counters the phosphaturic action of parathyroid hormone (PTH) in rats in vivo. The present study was undertaken
to examine this interaction using monolayers of Opossum kidney (OK) cells. 32P uptake, cAMP generation, PTH/PTHrP receptor mRNA expression and intracellular Ca2+ [Ca2+]i were measured in (1) control cells, (2) cells exposed to PTH, (3) cells pretreated with 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and (4) 1,25(OH)2D3-pretreated cells exposed to PTH. 32P uptakes were in (1) 5.00±0.20 (mean ±SE), in (2) 2.30±0.14 (P<0.001 versus group 1), in (3) 4.80±0.24 (P NS versus group 1) and in (4) 3.70±0.20 (P<0.001 versus group 2) nmol Pi/(mg·prot 10 mm). cAMP levels were in (1) 10±3, in (2) 210±8, in (3) 12±4, and in (4) 122±12 pmol cAMP/mg protein (P<0.001 versus group 2). PTH/PTHrP receptor mRNA expression was in relative units: (1) 100±0, (2) 99.5±6.2, (3) 68.7±2.6 (P<0.001 versus group 1), and (4) 34.8±3.3 (P<0.001 versus group 1). In groups 2 and 4 PTH induced equal transient increments in [Ca2+]i. These experiments demonstrate that the effect of vitamin D on phosphate transport is associated with a commensurate diminution
in PTH/PTHrP receptor gene expression and PTH-induced cAMP formation but not with Ca2+ transients. Vitamin D per se does not affect 32P uptake or cAMP generation while it slightly decreased PTH/PTHrP receptor gene expression. These observations demonstrate
that: (1) 1.25(OH)2D3 directly antagonizes the effects of PTH on 32P uptake in OK cells, (2) this effect is mediated via inhibition of PTH-induced activation of AC/cAMP system, (3) the diminution
in PTH-induced cAMP formation may stem at least in part from a decrease in the expression of PTH/PTHrP receptor mRNA.
Received: 2 December 1997 / Received after revision: 19 January 1998 / Accepted: 28 January 1998 相似文献
40.
Ultimate tensile strength of dentin: Evidence for a damage mechanics approach to dentin failure 总被引:2,自引:0,他引:2
Staninec M Marshall GW Hilton JF Pashley DH Gansky SA Marshall SJ Kinney JH 《Journal of biomedical materials research》2002,63(3):342-345
Dentin structure and properties are known to vary with orientation and location. The present study explored the variation in the ultimate tensile strength (UTS) of dentin with location in the tooth. Hourglass specimens were prepared from dentin located in the center, under cusps, and in the cervical regions of human molar teeth. These were tested in tension at various distances from the pulp. Median tensile strengths ranged from 44.4 MPa in the inner dentin near the pulp, to 97.8 MPa near the dentino-enamel junction (DEJ). This increase in the median UTS with distance from the pulp to the DEJ was statistically significant (P <.001). Of particular importance was the observation that the UTS measurements followed a Weibull probability distribution, with a Weibull modulus of about 4.5. The Weibull behavior of the UTS data strongly suggests that the large variances in fracture strength data result from a distribution of preexisting defects in the dentin. These findings justify a damage-mechanics approach to studies of dentin failure. 相似文献