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21.
Nitroso-aldicarb was tested for its ability to induce sister-chromatid exchanges (SCE) and cell-cycle delay in human peripheral blood lymphocytes in vitro. This derivative of aldicarb induced a dose-dependent increase in SCE values per cell. In addition, a slight decrease in the successive mitotic progression of cells in culture was observed. 相似文献
22.
Effects of social isolation and crowding upon adrenocortical reactivity and behavior in the rat 总被引:2,自引:0,他引:2
The effects of social isolation and crowding on adrenocortical function and upon behavioral responsiveness to electric shock have been studied in male and female rats. All female experimental groups showed higher corticosterone levels and heavier adrenals than their male counterparts. The major effect of housing condition concerned the corticosterone response to stress, while basal hormone concentration was not modified. Socially housed rats showed a more intense adrenocortical response and also a greater behavioral reactivity to electric shock than the isolates. 相似文献
23.
Enzyme levels of lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured in the cytosol of renal cortex samples from either normal and pathologic kidney tissue. The mean enzyme activity values, expressed in Units per gram of cytosolic protein decreased in the following order: normal cortex (LDH = 4,299 +/- 654; AST = 522 +/- 101; ALT = 197 +/- 44). chronic pyelonephritis (LDH = 2,360 +/- 876; AST = 297 +/- 117; ALT = 90 +/- 48), hydronephrosis (LDH = 2,208 +/- 1,264; AST = 279 +/- 165; ALT = 82 +/- 61), pyonephrosis (LDH = 1,410 +/- 596; AST = 158 +/- 69; ALT = 23.4 +/- 16.4) and renal tuberculosis (LDH = 1,149 +/- 481; AST = 93 +/- 34; ALT = 5.6 +/- 2.8). The decrease in the enzyme activities paralleled tissue damage and it was shown to affect cellular functionality in relation with energy and amino acid metabolism. 相似文献
24.
Summary By means of an experimental factorial design the role of several culture conditions is described and its values determined for the maximum yeast production in mixed cultures ofAspergillus oryzae andRhodotorula glutinis. 相似文献
25.
F Sánchez R González J Carretero M Rubio J M Riesco E Blanco J A Juanes R Vázquez 《Histology and histopathology》1992,7(4):719-724
Using the peroxidase-antiperoxidase immunocytochemical technique, a morphometric study of the magnocellular neurons of the Paraventricular nucleus of the rat hypothalamus, reactive to specific anti-vasopressin rabbit serum, was made. Following systemic and chronic administration of met-enkephalin the number of immunoreactive neurons was higher, especially in females. Additionally, in the females, it was possible to observe an increase in the immunoreactivity and the presence of well-stained fibres. These findings suggest, especially in females, a blockage in the release of vasopressin, facilitating its immunocytochemical visualization. 相似文献
26.
H. E. González 《Polar Biology》1992,12(1):81-91
Summary The abundance and depth distribution of zooplankton faeces in spring to early summer were investigated along meridional transects (47°W and 49°W) that extended from the Scotia Sea (57°S) across the Weddell-Scotia Confluence and into the Weddell Gyre (62°S). The sea ice edge retreated from 59°30S to 61°S during the study. Faeces were sampled with nets, Niskin bottles and sediment traps and subsequently analysed by light and electron (SEM) microscopy. Krill faecal strings and oval faecal pellets of unknown origin were by far the most important zooplankton faeces and highest concentrations were always found in the Confluence often close to the ice border. Krill faeces were usually more abundant in the uppermost layer (0–50m) where they contributed an average of 130 g dry weight m–3. There was an exponential decrease with depth, with a minimum of 0.6 g dry weight m–3 in the 500–1000 m stratum. Oval pellets were more evenly distributed in the upper 1000 m of the water column, with an average of 9 g dry weight m –3, although there was a small peak (20 g dry weight m–3) in the subsurface layer (50–150 m depth). Consecutive collections (day-night) of krill faeces using drifting sediment traps showed that only the larger strings sank from 50 to 150 m depth. Peritrophic membranes appeared to deteriorate during sinking. Diatoms (in particular Nitzschia and Thalassiosira spp.) contributed by far the bulk of material in krill and oval faeces. In samples collected near or under the pack ice, remains of crustaceans in both krill- and oval faeces were also found.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation 相似文献
27.
28.
The human platelet integrin GPIIb/IIIa (228 kDa), a Ca-dependent heterodimer formed by the IIb subunit (GPIIb, 136 kDa) and the 3 subunit (GPIIIa, 92 kDa), serves as the fibrinogen receptor at the surface of activated platelets. The degree of dissociation of the GPIIb/IIIa heterodimer (s°20
*, 8.9 S) into its constituent glycoproteins (GPIIb, 5.8 S; and GPIIIa, 3.9 S) has been assessed by analytical ultracentrifugation in Triton X100 buffers, and its Ca2+- and temperature-dependence correlated with Ca2+-binding to GPIIb/IIIa and its temperature dependence. At 21°C half-maximal dissociation of GPIIb/IIIa occurs at 5.5 ± 2.5 × 10–8 M Ca2+, very close to the dissociation constant of the high affinity Ca-binding site of GPIIb/IIIa (Kd1 8 ± 3 × 10–8 M) (Rivas and González-Rodríguez, 1991) and much lower than the Kd of the 3.4 medium affinity Ca-binding sites (Kd2 4 ± 1.5 × 10–5 M), which seems to demonstrate that the stability of the heterodimer in solution at room temperature is regulated by the degree of saturation of the high-affinity Ca-binding site. At 4°C, the stability of the heterodimer is apparently Ca2+-independent, while at room and physiological temperatures (15–37°C) the degree of dissociation of the heterodimer is regulated by the degree of dissociation of the high- and medium-affinity Ca-binding sites, respectively. On increasing the Ca2+ concentration up to 1 × 10–4 M after dissociation in Triton X100 solutions, the reconstitution of the GPIIb/IIIa heterodimer depends on the time and temperature at which the dissociated heterodimer was maintained, being almost complete within the first 5–10 min at 37°C and within the first 1–2 h at 21°C. After this time, a time- and temperature-dependent irreversible autoassociation of GPIIb (covalent) and GPIIIa (non-covalent) occurs, which hinders both the isolation of permanently stable monoamers of GPIIb and GPIIIa and the reconstitution of the GPIIb/IIIa heterodimer in Triton X100 solutions.
Abbreviations: GPIIb, GPIIIa, and GPIIb/IIIa, glycoprotein IIb, IIIa, and the heterodimer formed by them, respectively; s°20
*, the sedimentation coefficient of the glycoprotein-detergent complexes determined at 20°C, after extrapolation to zero-glycoprotein concentration
Offprint requests to: J. González-Rodríguez 相似文献
29.
Helicobacter pylori in Barrett's esophagus. 总被引:2,自引:0,他引:2
J C Ferreres F Fernández A Rodríguez Vives I González-Rodilla I Ursúa R Ramos J F Val-Bernal 《Histology and histopathology》1991,6(3):403-408
Barrett's esophagus is an anatomicoclinical state in which, due to the prolonged action of gastroesophageal reflux, the squamous epithelium is replaced by columnar epithelium. Helicobacter pylori has been implicated in the pathogenesis of various gastrointestinal disorders and has occasionally been observed in Barrett's esophagus. The aim of this study is to determine the incidence of H. pylori in Barrett's esophagus and try to establish its role in the pathogenesis of this disorder. H. pylori was observed in 31 biopsies (44.3%) of the 70 studied, mainly when the epithelium is of the gastric atrophic-fundic type (p less than 0.01). Its presence shows no relation to the degree of inflammatory activity and does not seem, therefore, to play an important role in the pathogenesis of the lesion. 相似文献
30.
Chinese hamster cells (Don line) were treated in vivo with 5-BrdU and 33258-Hoechst fluorochrome for obtaining the partial inhibition of condensation that causes the R-banding pattern. Untreated chromosomes were stained by a standard G-banding method. Statistical measurements show significant differences in the band numbers between the two treatments. The Don cell line in the authors' laboratory presents some karyotypical differences from Don cell lines studied by other authors. 相似文献