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21.
In order to clarify the effect of recombinant human tumor necrosis factor (rHu-TNF) on the antitumor T cell immune response, we examined the effect of rHu-TNF on the generation of cytotoxic T cells (CTL) against syngeneic tumor cells. Spleen cells from X5563 plasmacytoma-transplanted mice were stimulated in vitro with mitomycin C-treated X5563 cells in the presence or absence of rHu-TNF. The generation of CTL was augmented in a dose-dependent manner by the addition of rHu-TNF. The augmenting effect of rHu-TNF was more marked when indomethacin was added to the culture. The augmenting effect was observed only when rHu-TNF was added at the early stage of the generation of CTL. The cell surface phenotype of CTL generated was L3T4- and Lyt2+. The augmentation was shown not only by the chromium-51 release assay but also by the Winn assay. As to the specificity, the augmentation of CTL generation was observed by the addition of rHu-TNF when responder-primed spleen cells were stimulated with the tumor cells in vitro. On the other hand, augmentation was not observed when responder spleen cells were not stimulated with the tumor cells in vitro, or when responder spleen cells were obtained from normal mice. The CTL generated was not cytotoxic against other tumor cells of the same haplotype. Thus, rHu-TNF augmented the generation of CTL against syngeneic tumor cells in an antigen-specific manner. The in vivo effect of rHu-TNF was examined by administering rHu-TNF into X5563-bearing mice. The spleen cells of rHu-TNF-injected mice generated a much higher CTL activity against X5563 cells in vitro than did the spleen cells of uninjected mice. From these results, a possibility can be considered that in some cases, rHu-TNF may exert its antitumor activity by stimulating the immune system.  相似文献   
22.
This study has investigated the effect of a long period of overeating on the glycemic control and pancreatic beta-cell function in neonatally streptozocin treated impaired glucose tolerant mice. Neonatally streptozocin (60 mg/kg) treated male ICR mice with 150-200 mg/dl of fed blood glucose levels were divided into two groups at 6 weeks of age. One group was maintained on a cafeteria diet (SZC) and the other on ordinary mouse chow (SZ) until 30 weeks of age. Normal male ICR mice were divided into a cafeteria diet group (CC) and an ordinary chow group (Cont). SZC and CC consumed 134-124% of the caloric intake in SZ and Cont throughout the study. Marked elevation of the fed blood glucose level was observed and the glucose tolerance was progressively impaired in SZC. On pancreas perfusion at 30 weeks of age, insulin secretion to 30 mM glucose in SZC was significantly decreased compared with that in SZ. That in CC was slightly decreased compared with that in Cont. The pancreatic insulin concentration in SZC was significantly less than that in SZ. We conclude that chronic hyperglycemia, induced by the long period of overeating, accelerated the selective loss of beta-cell sensitivity to glucose. Even in normal mice that did not have marked hyperglycemia, insulin secretion to glucose was suppressed, probably by chronic stimulation of the beta-cell due to the long period of dietary excess.  相似文献   
23.
Isolation of a cDNA encoding the human GM2 activator protein   总被引:3,自引:0,他引:3  
The GM2 activator protein is a glycolipid-binding protein required for the lysosomal degradation of ganglioside GM2. A human fibroblast cDNA library was screened with mixtures of oligonucleotide probes corresponding to four different areas of the amino acid sequence. A putative clone (821 bp) which gave positive signals to all four probe mixtures was purified and sequenced. The sequence was colinear with the sequence of 160 amino acids of the mature GM2 activator protein. Availability of the cDNA clone should facilitate investigation into function of the GM2 activator protein and also into genetic abnormalities underlying GM2 gangliosidosis AB variant.  相似文献   
24.
The settling flux of seston (dry weight, DW), chlorophyll a (Chl a), particulate organic carbon (POC), particulate organic nitrogen (PON), and particulate phosphorus (PP) was measured monthly in 1981–1983 at 10 different depths in Lake Chuzenji, Japan; an oligotrophic lake with a maximum depth of 163 m. The Ti concentration in entrapped matter was used to separate the sedimentation flux into allochthonous and autochthonous components. Inflow loads of dissolved nutrients (DN: 4.5, DP: 0.48 g m-2a-1) were almost sufficient to supply the autochthonous fluxes at 30 m (PON: 2.9, PP: 0.51 g m-2a-1 ), and this flux of POC (26.6 g m-2a -1) was about one-third of primary production (84 g C M-2a-1). Sedimentation of particulate matter was the main path of losing nutrients from lake water, explaining more than 80% removal of inflow loads (TN, TP). Decomposition rates during sedimentation which were calculated from the vertical difference in the autochthonous flux agreed very closely with the results obtained by laboratory experiments of a 100-day incubation (content ratios from field observations were: POC 0.67, PON 0.65, PP 0.85; and from laboratory experiments they were: POC 0.68, PON 0.70, PP 0.94). These decomposition rates and those near the sediment interface were used to explain dissolved oxygen depletion and nitrate increase in the hypolimnion during stratification. The average sinking velocities were 1.82m d-1 for seston and 1.16 m d-1 for Chl a at 30m, they were influenced by Chl a content of seston.  相似文献   
25.
To determine the region of human tumor necrosis factor-alpha (TNF-alpha), essential for cytotoxic activity against mouse L-M cells, single amino-acid-substituted TNF-alpha mutant proteins (muteins) were produced in Escherichia coli by protein engineering techniques. An expression plasmid for TNF-alpha was mutagenized by passage through an E. coli mutD5 mutator strain and by oligonucleotide-directed mutagenesis. Approximately 100 single amino-acid-substituted TNF-alpha muteins were produced and assayed for cytotoxic activity. The cytotoxic activities of purified TNF-alpha muteins, e.g. TNF-31T, -32Y, -82D, -85H, -115L, -141Y, -144K and -146E, were less than 1% of that of parent TNF-alpha. These results indicate that the integrity of at least four distinct regions of the TNF-alpha molecule is required for full biological activity. These regions are designated as follows: region I, from position 30 to 32; region II, from position 82 to 89; region III, from position 115 to 117; region IV, from position 141 to 146. In addition, TNF-141Y could not completely compete with parent TNF-alpha for binding to the receptor. This demonstrates that region IV, and at least aspartic acid at position 141, must be involved in the TNF receptor binding site.  相似文献   
26.
27.
The effect of human C-reactive protein (CRP) on macrophage function was studied in an assay of superoxide anion (O2-) production. Peritoneal exudate macrophages (PEM) of guinea pigs exposed in vitro to various doses of CRP for 72 hr resulted in the development of O2- production dose-dependently, measured by increases in superoxide dismutase-inhibitable nitro blue tetrazolium reduction. The O2--producing activity of PEM cultured without CRP, used as a control, decreased markedly in proportion to incubation time. The O2- production by PEM exposed to CRP for 18 hr when control PEM were still high in O2- production, was decreased by larger doses of CRP, while PEM cultured without CRP for 72 hr, when O2- production by control PEM was very low, followed by incubation with CRP for another 18 hr, produced O2- CRP-dose-dependently as in the case of that observed after 72-hr incubation with CRP. These results indicate that CRP is capable of activating macrophages and acts on macrophage function as a modulator. CRP possesses migration inhibitory factor (MIF)-like activity (as reported in the preceding paper) and also macrophage-activating factor (MAF)-like activity, indicating that CRP may play a functional role at the site of inflammation and tissue damage by accumulating and activating macrophages.  相似文献   
28.
Polyclonal antibodies against Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) of rat brain were prepared by immunizing rabbits and then purified by antigen-affinity column. The antibodies which recognized both subunits of the enzyme with Mrs 49K and 60K were used for the study on the distribution of CaM kinase II in formalin-fixed, paraffin-embedded tissues. In the brain, a light-microscopic study demonstrated strong immunoreactivity in neuronal somata and dendrites and weak immunoreactivity in nuclei. The densely stained regions included cerebral cortex, hippocampal formation, striatum, substantia nigra, and cerebellar cortex. In substantia nigra, neurites were stained, but not neuronal somata. Electron microscopy revealed that the immunoreactive product was highly concentrated at the postsynaptic densities. In addition to neurons, weak immunoreactivity was also demonstrated in glial cells, such as astrocytes and ependymal cells of ventricles and epithelial cells of choroid plexus. In other tissues, strong immunoreactivity was observed in the islet of pancreas and moderate immunoreactivity in skeletal muscle and kidney tubules. Immunoreactivity was demonstrated in all of the tissues tested. The results suggest that CaM kinase II is widely distributed in the tissues.  相似文献   
29.
A Nakano  M Kondo  K Taniyama  S Tanaka 《Life sciences》1988,42(25):2657-2662
gamma-Aminobutyric acid (GABA) content was measured, and the release of GABA was studied in the synovial membrane of the rat knee joint. GABA content of the synovial membrane was 20.1 nmol/g tissue. Ten days after unilateral dissection of the sciatic nerve, femoral nerve or both nerves, the GABA contents of the ipsilateral membrane were 13.8, 14.6 and 7.8 nmol/g tissue, respectively. High K+ evoked the Ca2+-dependent release of [3H] GABA from the synovial membranes of intact rats preloaded with [3H] GABA, but did not evoke release from the membrane ipsilateral to the dissection of both sciatic and femoral nerves. Evoked release of [3H] GABA was obtained in the synovial membrane preloaded with [3H] GABA in the presence of beta-alanine, but not in the presence of 2,4-L-diaminobutyric acid. These results indicate that GABA is present in the neuronal elements of the synovial membrane of the rat knee joint.  相似文献   
30.
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