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1.
Bernard-Weil E 《Acta biotheoretica》2000,48(3-4):243-257
A link between biological and human sciences may be established, under the condition that we should admit the existence of reciprocal influences between them. The model for the regulation of agonistic antagonistic couples (MRAAC) is built from the study of biological systems and gives rise to specific types of control. This model can be helpful in decision processes in some human sciences such as management, economical and political strategies. The reason for such an opportunity lies in the fact that MRAAC is a general and phenomenological model able to incorporate the whole of the agonistic antagonistic systems. This type of regulation might be related to the concept of the viability of a system (yet also valid for human science systems) and to a functional and structural pattern which is the basis for agonistic antagonistic networks. 相似文献
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Changes in cytosolic free Ca2+ concentration ([Ca2+]c) play a crucial role in the control of insulin secretion from the electrically excitable pancreatic β-cell. Secretion is controlled by the finely tuned balance between Ca2+ influx (mainly through voltage-dependent Ca2+ channels, but also through voltage-independent Ca2+ channels like store-operated channels) and efflux pathways. Changes in [Ca2+]c directly affect [Ca2+] in various organelles including the endoplasmic reticulum (ER), mitochondria, the Golgi apparatus, secretory granules and lysosomes, as imaged using recombinant targeted probes. Because most of these organelles have specific Ca2+ influx and efflux pathways, they mutually influence free [Ca2+] in the others. In this article, we review the mechanisms of control of [Ca2+] in various compartments and particularly the cytosol, the endoplasmic reticulum ([Ca2+]ER), acidic stores and mitochondrial matrix ([Ca2+]mito), focusing chiefly on the most important physiological stimulus of β-cells, glucose. We also briefly review some alterations of β-cell Ca2+ homeostasis in Type 2 diabetes. 相似文献
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Wakui S Motohashi M Muto T Takahashi H Hano H Jutabha P Anzai N Wempe MF Endou H 《Comparative medicine》2011,61(5):412-418
Epidemiologic studies indicate that the incidence of gastric cancer is higher in males than in females. Although the mechanisms mediating this difference are unclear, a role for estrogens has been proposed. We used Western blotting to evaluate the role of estrogen receptor (ER) subtypes ERα and ERβ and proliferating cell nuclear antigen (PCNA) in N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis in Wistar rats; ERα and ERβ mRNA levels also were analyzed by quantitative real-time RT-PCR analysis. The incidence of gastric cancer was significantly higher in male than female rats. In both sexes, ERα expression was similar in MNNG-treated cancerous and noncancerous tissues and normal gastric tissue. However, ERβ expression in MNNG-treated cancerous and noncancerous tissues was significantly lower in male rats and higher in female rats than that in normal gastric tissue; MNNG-induced cancerous tissue showed the highest ERβ expression. PCNA expression in MNNG-treated cancerous tissues was higher than that in noncancerous tissues, and was higher in male rats than female rats. Western blotting results were consistent with the mRNA changes determined by quantitative real-time RT-PCR. The present study provides evidence of a sex-associated difference in ERβ and PCNA expression in MNNG-induced gastric cancers in Wistar rats. 相似文献
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The aim of the study was to investigate theAmbrosia pollen concentrations inselected Polish cities and for Kraków torelate it to some meteorological factors.Sampling was carried out in Kraków in1982–1997 and in Rabka in 1992–1996 with theuse of the gravimetric method. In Zakopane,Kraków, Ostrowiec witokrzyski,Warszawa and Pozna in 1995–1996 both thegravimetric and volumetric methods (Burkardtrap) were employed. In Kraków themonitoring has been performed since 1994 usingthe volumetric method. The results show theragweed pollen presence in August and Septemberwith the tendency to appear more frequently inAugust in some years. In Kraków (1994–1999)Ambrosia pollen was found either in thelast two weeks of August or in the first twoweeks of September which seems to be a regularand repeatable pattern every two years.Seasonal fluctuations of Ambrosia pollenconcentration do not show a clear increasingtendency except at Warszawa and Ostrowiecwitokrzyski in 1996 and at Krakówin 1999. Percentage of Ambrosia pollen inannual sums of total pollen is very low anddoes not exceed 1% except at Ostrowiecwitokrzyski in 1996 (1.2%) and atKraków in 1999 (2%). For Kraków theanalysis of some meteorological factors (Tmax,Tmin, precipitation, wind direction) wasperformed. High temperature and lack of rain orlow precipitation correlate well with ragweedpollen concentrations. During the Ambrosia pollen seasons ESE, E, S, SE, WSW, SWwind directions prevailed which could suggest along-distance transport from Ukraine, the CzechRepublic, Slovakia and also from Hungary, one ofthe most ragweed-polluted countries. 相似文献
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《Mutation Research Letters》1987,190(1):59-62
Cisplatinum [cis-diamminedichloroplatinum(II)] is one of the most active antitumour agents and its effect is mainly due to the formation of cisplatinum-DNA crosslinks. Formation of cisplatinum-DNA intrastrand crosslinks in nucleated white blood cells of patients was measured, both in (pretreatment) samples exposed in vitro and in cells collected immediately after in vivo exposure to cisplatinum. Large interpatient variations were found. The in vitro results showed a linear correlation with the in vivo data (cc=0.91). The in vitro measurements of crosslinks may allow prediction of response and avoidance of toxicity in individual patients. 相似文献
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Interindividual human variation in cisplatinum sensitivity, predictable in an in vitro assay? 总被引:2,自引:0,他引:2
Cisplatinum [cis-diamminedichloroplatinum(II)] is one of the most active antitumour agents and its effect is mainly due to the formation of cisplatinum-DNA crosslinks. Formation of cisplatinum-DNA intrastrand crosslinks in nucleated white blood cells of patients was measured, both in (pretreatment) samples exposed in vitro and in cells collected immediately after in vivo exposure to cisplatinum. Large interpatient variations were found. The in vitro results showed a linear correlation with the in vivo data (cc = 0.91). The in vitro measurements of crosslinks may allow prediction of response and avoidance of toxicity in individual patients. 相似文献
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We tested if variations (i.e., breadth) in morphology and habitat use vary predictably among six aquatic gastropod species that were collected across Indiana and Illinois, USA. We predicted that interspecific morphological variation would positively covary with variation in habitat use among species. We used geometric morphometrics (Procrustes technique and relative warp analysis) to quantify morphology and multivariate analyses (PCA) to quantify habitat. Increased morphological breadth did not vary predictably with increased habitat breadth. However, we found that life history traits correspond with patterns in morphological and habitat breadth for these six aquatic gastropods. Pulmonate gastropods (use lungs for respiration) that lack an operculum cover exhibited decreased morphological breadth compared to coenogastropods (use gills for respiration). This pattern may ultimately be a function of behavioral adaptations in freshwater gastropods. Gastropods that are capable of breathing air or using other behavioral modifications such as burrowing to escape predators may not require high morphological breadth. Conversely, selection may favor higher morphological breadth in gastropods with gills that also do not move out of the water column to escape predators. 相似文献
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Comfort P Haigh A Matthews MJ 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(3):772-776
Because previous research has shown a relationship between maximal squat strength and sprint performance, this study aimed to determine if changes in maximal squat strength were reflected in sprint performance. Nineteen professional rugby league players (height = 1.84 ± 0.06 m, body mass [BM] = 96.2 ± 11.11 kg, 1 repetition maximum [1RM] = 170.6 ± 21.4 kg, 1RM/BM = 1.78 ± 0.27) conducted 1RM squat and sprint tests (5, 10, and 20 m) before and immediately after 8 weeks of preseason strength (4-week Mesocycle) and power (4-week Mesocycle) training. Both absolute and relative squat strength values showed significant increases after the training period (pre: 170.6 ± 21.4 kg, post: 200.8 ± 19.0 kg, p < 0.001; 1RM/BM pre: 1.78 ± 0.27 kg·kg(-1), post: 2.05 ± 0.21 kg·kg(-1), p < 0.001; respectively), which was reflected in the significantly faster sprint performances over 5 m (pre: 1.05 ± 0.06 seconds, post: 0.97 ± 0.05 seconds, p < 0.001), 10 m (pre: 1.78 ± 0.07 seconds, post: 1.65 ± 0.08 seconds, p < 0.001), and 20 m (pre: 3.03 ± 0.09 seconds, post: 2.85 ± 0.11 seconds, p < 0.001) posttraining. Whether the improvements in sprint performance came as a direct consequence of increased strength or whether both are a function of the strength and power mesocycles incorporated into the players' preseason training is unclear. It is likely that the increased force production, noted via the increased squat performance, contributed to the improved sprint performances. To increase short sprint performance, athletes should, therefore, consider increasing maximal strength via the back squat. 相似文献
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Laker RC Wlodek ME Wadley GD Gallo LA Meikle PJ McConell GK 《American journal of physiology. Endocrinology and metabolism》2012,302(10):E1221-E1230
We have previously shown that 4 wk of exercise training early in life normalizes the otherwise greatly reduced pancreatic β-cell mass in adult male rats born small. The aim of the current study was to determine whether a similar normalization in adulthood of reduced skeletal muscle mitochondrial biogenesis markers and alterations in skeletal muscle lipids of growth-restricted male rats occurs following early exercise training. Bilateral uterine vessel ligation performed on day 18 of gestation resulted in Restricted offspring born small (P < 0.05) compared with both sham-operated Controls and a sham-operated Reduced litter group. Offspring remained sedentary or underwent treadmill running from 5-9 (early exercise) or 20-24 (later exercise) wk of age. At 24 wk of age, Restricted and Reduced litter offspring had lower (P < 0.05) skeletal muscle peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) protein expression compared with Control offspring. Early exercise training had the expected effect of increasing skeletal muscle markers of mitochondrial biogenesis, but, at this early age (9 wk), there was no deficit in Restricted and Reduced litter skeletal muscle mitochondrial biogenesis. Unlike our previous observations in pancreatic β-cell mass, there was no "reprogramming" effect of early exercise on adult skeletal muscle such that PGC-1α was lower in adult Restricted and Reduced litter offspring irrespective of exercise training. Later exercise training increased mitochondrial biogenesis in all groups. In conclusion, although the response to exercise training remains intact, early exercise training in rats born small does not have a reprogramming effect to prevent deficits in skeletal muscle markers of mitochondrial biogenesis in adulthood. 相似文献
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Four hectares were inventoried for all trees with diameter at breast height (DBH) of 10cm or greater in a terra firme forest 200km Northeast of Manaus, Central Amazonia. The number of species varied from 137 to 168, the number of individuals from 639 to 713, total basal area from 32.8 to 40.2 and total biomass from 405 to 560 tons per hectare. The majority of trees, 90%, had a DBH between 10 and 30 cm. Leguminosae, Lauraceae, Sapotaceae, Chrysobalanaceae and Moraceae were the most rich families (number of species) in all sampled hectares. The most abundant families in all sampled hectares (number of trees) were Leguminosae, Burseraceae, Myristicaceae, Moraceae and Chrysobalanaceae. The most dominant families in all sampled hectares (basal area and biomass) were Leguminosae, Lecythidaceae, Chrysobalanaceae, Bombacaceae and Moraceae. Similarity indexes at family level varied from 67 to 86% between the four hectares sampled. Alexa grandiflora (Leguminosae) was the most abundant species in the hectares one and three, while Scleronema micranthum (Bombacaceae), and Oenocarpus bacaba (Palmae) were the most abundant species in hectares two and four. S. micranthum was the most dominant species (basal area) in hectares one and two, while Bertholletia excelsa (Lecythidaceae) and Goupia glabra (Celastraceae) were the most dominant species in hectares three and four. S. micranthum (Bombacaceae), Buchenavia sp. 2 (Combretaceae), B. excelsa (Lecythidaceae) Couepia obovata (Chrysobalanaceae) were the most dominant species (biomass) in hectares one to four, respectively. Similarity indexes at species level varied from 26 to 44% between the four sampled hectares. This inventory is compared with previous studies and it was found that, in our study area, there was a greater proportion of trees of 60cm diameter or more and consequently a considerably higher total basal area. It is concluded that there are still an inadequate number of inventories of Amazonian terra firme forests to elucidate the major floristic pattern a both regional and local levels. Since the area is a mosaic of distinct floristic communities it is essential to obtain further standardized inventory data in order to set adequate conservation policies for the region. 相似文献
14.
β-adrenergic modulation of in vivo long-term potentiation in area CA1 and its role in spatial learning in rats 总被引:1,自引:0,他引:1
The hippocampus plays a key role in declarative learning and memory [1]. Hippocampal long-term potentiation (LTP) is a type of synaptic plasticity that has been widely studied as a syn-aptic mechanism underlying learning and memory[27]. It has been reported that in vitro LTP in area CA1 is subjected to b-adrenergic modulation. For example, the theta-pulse stimulation (510 Hz), a neutral frequency not modifying synaptic strength, can elicit a robust LTP in area CA1 in slice when the b-adr… 相似文献
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Background
The value of genotyping to predict variant phenotypes in patients with phenylalanine hydroxylase (Pah) deficiency is a matter of debate. However, there exists no comprehensive population relationship study focused on the Han Chinese.Methods
We analyzed genotype–phenotype correlation for 186 different genotypes in 338 unrelated Chinese patients harboring 109 different Pah mutations. Two systems were used in this process. The first was a phenotype prediction system based on arbitrary values (AV) attributed to each mutation. The second was a pair-wise correlation analysis. The observed phenotype for AV analysis was the corresponding metabolic phenotype stratified according to the pretreatment phenylalanine (Phe) value.Results
We found that the observed phenotype matched the predicted phenotype in 54.41% of 272 patients for whom AV information was available; the highest degree of concordance (61.83%) was found in patients with null/null genotypes, whereas the lowest “concordance rate” (32.69%) was observed for patients with expected mild-PKU phenotype. There are repeated inconsistencies for such mutations as R241C, R243Q, R261Q, V388M, V399V, R408Q, A434D and EX6-96A>G which are associated with variable phenotypes in patients with identical genotype. Significant correlations were disclosed between pretreatment Phe values and predicted residual activity (r = − 0.45643, P < 0.0001) or AV sum (r = − 0.59523, P < 0.0001).Conclusion
Our study supports the notion that the Pah mutation genotype is the main determinant of metabolic phenotype in most patients in a particular population, and provided novel insights into the values that underpin the subsequent treatment and the prognosis of PKU in Chinese. 相似文献16.
Detection of chemical compounds in food sources is based on the activation of 7 transmembrane gustatory receptors (GRs) in mammals and in insects such as Drosophila, although the receptors are not conserved between the classes. Different combinations of Drosophila GRs are involved in the detection of sugars, but the activated signaling cascades are largely unknown. Because 7 transmembrane receptors usually couple to G-proteins, we tried to unravel the intracellular signaling cascade in taste neurons by screening heterotrimeric G-protein mutant flies for gustatory deficits. We found the subunit Goα to be involved in feeding behavior and cell excitability by different transgenic and pharmacological approaches. Goα is involved in the detection of sucrose, glucose, and fructose, but not with trehalose and maltose. Our studies reveal that Goα plays an important role in the perception of some sweet tastants. Because the perception of other sweet stimuli was not affected by mutations in Goα, we also found strong indication for the existence of multiple signaling pathways in the insect gustatory system. 相似文献
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Roles of β-catenin in somitogenesis in rat embryos 总被引:2,自引:0,他引:2
Matsuda M 《In vitro cellular & developmental biology. Animal》2000,36(9):593-599
Summary We studied the roles of β-catenin in somitogenesis using immunostaining and antisense experiments in rat embryos. High levels
of β-catenin appeared transiently in the developing rat somites. Initially, β-catenin accumulation was observed in the core
cells of presomitic cell aggregates and then in the lumen of epithelial vesicles. Subsequently, it was confined to the dermomyotomes
and their lumen and then the myotomes. High levels of cyclin D1 were observed in the core cells, in the lumen of epithelial
vesicles, in myotomes, and in mesenchymal sclerotomes. When embryos were cultured in medium supplemented with β-catenin antisense
oligodeoxynucleotide (ODN), the accumulation of β-catenin, but not of cyclin D1, in the nascent somites and dermomyotomes
was suppressed, while the number of somites was the same as that observed in control embryos. The number of myosin-positive
somites and the amount of myosin per somite in embryos treated with the antisense ODN were lower than those in controls. These
results suggested that β-catenin promotes development of myotomal cells during somitogenesis. The function of β-catenin in
the development of myotomes may not be correlated to cyclin D1. 相似文献
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Alvaro AR Rosmaninho-Salgado J Santiago AR Martins J Aveleira C Santos PF Pereira T Gouveia D Carvalho AL Grouzmann E Ambrósio AF Cavadas C 《Neurochemistry international》2007,50(5):757-763
NPY is present in the retina of different species but its role is not elucidated yet. In this work, using different rat retina in vitro models (whole retina, retinal cells in culture, microglial cell cultures, rat Müller cell line and retina endothelial cell line), we demonstrated that NPY staining is present in the retina in different cell types: neurons, macroglial, microglial and endothelial cells. Retinal cells in culture express NPY Y(1), Y(2), Y(4) and Y(5) receptors. Retina endothelial cells express all NPY receptors except NPY Y(5) receptor. Moreover, NPY is released from retinal cells in culture upon depolarization. In this study we showed for the first time that NPY is present in rat retina microglial cells and also in rat Müller cells. These in vitro models may open new perspectives to study the physiology and the potential pathophysiological role of NPY in the retina. 相似文献