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排序方式: 共有192条查询结果,搜索用时 578 毫秒
81.
Biserka Kargacin Katherine S. Squibb Sofia Cosentino Anatoli Zhitkovich Max Costa 《Biological trace element research》1993,36(3):307-318
The purpose of this study was to evaluate species differences in tissue accumulation of chromium. Rats and mice were orally
exposed to Cr(VI) (potassium chromate) via drinking water (8 mg/d/kg body wt for 4 or 8 wk) or by ip injection (0.3 and 0.8
mg/d/kg, for 4 or 14 d). Chromium concentrations were measured by atomic absorption spectrophotometry, and tissues were compared
for exposure route and species differences. After oral exposure, irrespective of treatment duration, liver concentrations
of chromium were three to four times higher in mice than rats, whereas kidney concentrations were about 50% lower. However,
after ip injection, kidney and blood concentrations in rats were two- and four-fold, higher, respectively. Both rats and mice
showed high values of Cr concentration in the bone. After single ip injection of Na2
51CrO4; Cr concentrations were higher in the blood of rats than mice both after 24 and 72 h. Red blood cell concentrations of Cr
were also greater in rats than mice by approximately threefold, whereas white blood cell Cr concentrations were higher in
mice than rats. There was also a twofold greater binding of Cr/μmol of hemoglobin in rats compared to mice. These data indicate
that species differences exist for Cr metabolism and that they differ with respect to the route of exposure. These results
may be owing to species differences in the reduction of Cr and different binding of Cr to hemoglobin. 相似文献
82.
The previously unknown larvae of O. assimilis (Schneider, 1845) and O. lefebvrei (Rambur, 1842) are described, while that of O. flexuosus (Schneider, 1845) is redescribed, all from material from SW. Turkmenistan and Tajikistan. Their distributions extend from the eastern mediterranean to central-west Asia and are mapped. A differential diagnosis and key to the identification of the larvae of four central Asiatic species of the genus Onychogomphus is given. 相似文献
83.
M M Zhekova S A Anatoli? I P Ashmarin 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1976,(3):70-73
A study was made of conditions and dynamics of discharge of myeloperoxidase (MPO) from rabbit neutrophils in case of encounter with staphylococci. The discharge began not later than 9--12 minutes after the administration of Staph. aureus into the neutrophil suspension, i. e. as early as the stage of bacterial sorption, and reached the maximum by the 30th minute. The contact of neutrophils with individual bacteria was an adequate signal for the beginning of the discharge. The greatest discharge was with the ratio of 5 bacteria per one neutrophil. The discharge was retarded when this ratio reached 80: 1. A hypothesis on the "avalanche" switchingon of the system of MPO discharge: a single bacteria injection mu/ml a discharge from an individual neutrophil of MPO and cation proteins; the latter switch on discharge from several other neutrophils, without any participation of bacteria. Cation proteins intensified the MPO discharge in the concentration of the 10--20 switch on. Biolgical significance of the phenomenon of early discharge of antibacterial factors no directed to the provision of phagocytosis is discussed. 相似文献
84.
Zamora R Grishin A Wong C Boyle P Wang J Hackam D Upperman JS Tracey KJ Ford HR 《American journal of physiology. Gastrointestinal and liver physiology》2005,289(4):G643-G652
High-mobility group box 1 (HMGB1) is a late mediator of endotoxemia known to stimulate the production of proinflammatory cytokines that are putative mediators of intestinal inflammation associated with necrotizing enterocolitis (NEC). We hypothesized that HMGB1 is also involved in the pathogenesis of NEC. We examined the expression of HMGB1 and the effect of the novel drug semapimod on intestinal inflammation in an experimental model of NEC in neonatal rats. Newborn rats were subjected to hypoxia and fed a conventional formula by gavage (FFH) or were breast fed (BF). Rats were killed on day 4, and the distal ileum was harvested for morphological studies and Western blot analysis. FFH newborn rats but not BF controls developed intestinal inflammation similar to the histological changes observed in human NEC. We found that the expression of HMGB1 and its receptor for advanced glycation end products (RAGE) as well as that of other apoptosis/inflammation-related proteins (Bad, Bax, inducible nitric oxide synthase, and cyclooxygenase 2) was upregulated in the ileal mucosa of FFH newborn rats compared with BF animals. Administration of the drug semapimod inhibited the upregulation of those proteins and partially protected the animals against the FFH-induced intestinal injury. Elevated levels of HMGB1 were also found in ileal samples from infants undergoing intestinal resection for acute NEC. Our results implicate HMGB1 and RAGE as important mediators of enterocyte cell death and hypoxia-induced injury in NEC and support the hypothesis that inhibitors such as semapimod might play a therapeutic role in chronic intestinal inflammation characterized by this animal model. 相似文献
85.
IL-27 mediates complete regression of orthotopic primary and metastatic murine neuroblastoma tumors: role for CD8+ T cells 总被引:7,自引:0,他引:7
Salcedo R Stauffer JK Lincoln E Back TC Hixon JA Hahn C Shafer-Weaver K Malyguine A Kastelein R Wigginton JM 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(12):7170-7182
We have shown previously that IFN-gamma-inducing cytokines such as IL-12 can mediate potent antitumor effects against murine solid tumors. IL-27 is a newly described IL-12-related cytokine that potentiates various aspects of T and/or NK cell function. We hypothesized that IL-27 might also mediate potent antitumor activity in vivo. TBJ neuroblastoma cells engineered to overexpress IL-27 demonstrated markedly delayed growth compared with control mice, and complete durable tumor regression was observed in >90% of mice bearing either s.c. or orthotopic intra-adrenal tumors, and 40% of mice bearing induced metastatic disease. The majority of mice cured of their original TBJ-IL-27 tumors were resistant to tumor rechallenge. Furthermore, TBJ-IL-27 tumors were heavily infiltrated by CD8(+) T cells, and draining lymph node-derived lymphocytes from mice bearing s.c. TBJ-IL-27 tumors are primed to proliferate more readily when cultured ex vivo with anti-CD3/anti-CD28 compared with lymphocytes from mice bearing control tumors, and to secrete higher levels of IFN-gamma. In addition, marked enhancement of local IFN-gamma gene expression and potent up-regulation of cell surface MHC class I expression are noted within TBJ-IL-27 tumors compared with control tumors. Functionally, these alterations occur in conjunction with the generation of tumor-specific CTL reactivity in mice bearing TBJ-IL-27 tumors, and the induction of tumor regression via mechanisms that are critically dependent on CD8(+), but not CD4(+) T cells or NK cells. Collectively, these studies suggest that IL-27 could be used therapeutically to potentiate the host antitumor immune response in patients with malignancy. 相似文献
86.
87.
Structure,expression and chromosomal localisation of the metallothionein-like gene family of tomato 总被引:3,自引:0,他引:3
Giritch Anatoli Ganal Martin Stephan Udo W. Bäumlein Helmut 《Plant molecular biology》1998,37(4):701-714
Metallothioneins are small cysteine-rich proteins with strong binding capacity for heavy metals. In animals and fungi they are involved in cellular detoxification processes. Although genes for similar proteins exist in plants, less is known about the putative functions of their protein products. Here, we describe the characterisation of cDNAs specific for four genes (LEMT1, LEMT2, LEMT3 and LEMT4) encoding metallothionein-like proteins from tomato. Based on the characteristic cysteine pattern, the LEMT1, LEMT3 and LEMT4 gene products represent type 2 proteins. In contrast, the LEMT2 protein might establish a new structural pattern of metallothionein-like proteins not described before. Mapping experiments demonstrate that all four genes are localised at different genetic loci within the tomato genome. The members of the small gene family show a differential organ specific expression pattern. Expression of these genes is also influenced by heavy metals and by treatment with the thiol-oxidising drug diamide. We further describe the expression of the LEMT genes under different iron supply conditions both in tomato wild type as well as in the mutant chloronerva, which is defective in metal uptake regulation and exhibits a characteristic apparent iron deficiency syndrome. 相似文献
88.
During long-term potentiation (LTP) of excitatory synapses, Ca2+/calmodulin-dependent protein kinase II (CaMKII) is activated by Ca2+ influx through NMDA receptors that potentiate AMPA receptor currents by insertion of additional GluR1-containing receptors at the synapse and by increasing AMPA channel conductance, as well as by stimulating structural changes. CaMKII is also involved in the maintenance of LTP and contributes to maintenance of behavioral sensitization by cocaine or amphetamine. Recent studies show that transient expression of catalytically dead αCaMKII K42M mutant after exposure to amphetamine persistently reverses the behavioral effects of the addiction. A suggested interpretation is that this mutant acts as a dominant negative in the control of synaptic strength, but this interpretation has not been physiologically tested. Here we investigate the effect of αCaMKII K42M mutant expressed in single CA1 pyramidal neurons on basal excitatory neurotransmission in cultured rat hippocampal organotypic slices. The mutant caused nearly 50% reduction in the basal CA3–CA1 transmission, while overexpression of the wild-type αCaMKII had no effect. This result is consistent with the dominant negative hypothesis, but there are complexities. We found that the decrease in basal transmission did not occur when activity in the slices was suppressed after transfection by TTX or when NMDA receptors were blocked by APV. Thus, the dominant negative effect requires neural activity for its expression. 相似文献
89.
Igor A. Mikhailopulo Zygmunt Kazimierczuk Anatoli I. Zinchenko Vladimir N. Barai Valeria V. Romanova Ludmilla A. Eroshevskaya 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):477-480
Abstract Substrate activity of a broad spectrum of derivatives of benzimidazole in the reaction of enzymatic ribo- and 2-deoxyribosylation catalyzed by purine nucleoside phosphorylase of whole cells of E. coli BMT-1D/1A has been studied. Guanosine or 2′-deoxyguanosine were used as glycosyl donors. 相似文献
90.