共查询到20条相似文献,搜索用时 15 毫秒
1.
It was previously reported that the establishment of the L5178Y cell tumor-dormant state in DBA/2 mice is mediated principally by a peritoneal cytolytic T-cell response that reaches peak levels 4 days after L5178Y cell challenge, lyses more than 99% but less than 100% of peritoneal L5178Y cells, and gradually wanes to background levels by 40–70 days postchallenge (DPC). At this time the majority of mice are clinically normal, and contain a relatively small number of L5178Y cells in the peritoneal cavity. During the tumor-dormant state, mice that harbor more than 104 L5178Y cells contain peritoneal macrophage-mediated cytolytic activity. We report here that tumor-dormant mice that contain fewer than 104 peritoneal L5178Y cells also produce cytolytic activity in vitro, but that it is synergistic, in that the cytolytic activity of adherent (AD) peritoneal cells (PEC) and nonadherent (NAD) PEC cultured together is greater than the additive lysis produced by these cell populations when cultured separately. This synergistic cytolytic activity is: (1) effector cell density dependent, (2) dependent on the tumor-dormant status of the NAD and AD PEC donor mice, (3) protracted in its kinetics during a 48-hr in vitro assay, and (4) dependent on an interaction between NAD T cells and AD phagocytic macrophages. The consistent detection of this in vitro-assayed cytolytic activity in PEC of tumor-dormant mice which harbor small endogenous tumor burdens suggests that it reflects an in vivo cytotoxic effector mechanism involved in the long-term maintenance of the tumor-dormant state. 相似文献
2.
Helen L. Henry 《Biochemical and biophysical research communications》1977,74(2):768-774
The primary culture of kidney cells from vitamin D deficient chicks is described. After four days in culture the cells reach confluency and retain their ability to metabolize 25-hydroxyvitamin D3 to 1,25-dihydroxyvitamin D3. Addition of one unit of bovine parathyroid hormone to the culture medium for 48 hours prior to assay had no effect on the cells' ability to produce 1,25-dihydroxy vitamin D3, whereas after 24 hours in the presence of 5×10?8 1,25-dihydroxyvitamin D3 the cells produced not this metabolite, but 24,25-dihydroxyvitamin D3. This cell culture system will allow the investigation of the regulation of renal 25-hydroxyvitamin D3 metabolism under controlled conditions. 相似文献
3.
A steroid which stabilizes lysosomes and a pyrogenic steroid which labilizes lysosomes were compared with respect to their ability to modify lysosomal uptake and lysosomal enzyme levels . Cortisone acetate increased the uptake of acridine orange by rat liver lysosomes when the dye was administered by intrathoracic injection. The steroid increased and accelerated the uptake of acridine orange so that, in liver lysosomes from treated rats, the maximum uptake was double that of controls and was reached at 2h, whereas in controls the maximum uptake was at 4h after the injection of the dye. This large elevation of uptake is specific to the lysosomal fraction and is not seen in other subcellular fractions of rat liver. The specific activities of a lysosomal enzyme β-N-acetylglucosaminidase were increased in lysosomal fractions from cortisone acetate-treated rats. Etiocholanolone, a steroid which labilizes lysosome , similarly accelerated and increased acridine orange uptake by lysosomes but had little effect on lysosomal β-N-acetylglucosaminidase levels. Thus the ability of steroids to stabilize or labilize lysosomes does not correlate with their effect on lysosomal uptake of injected substances , or with their ability to induce increased specific activities of lysosomal enzymes. 相似文献
4.
M Lippman 《Life sciences》1976,18(2):143-152
Steroid hormones induce responses in target tissues by a mechanism involving the specific initial interaction of hormone with cytoplasmic receptor molecules. These receptors, usually localized in target tissues have high binding affinities and limited binding specificities for biologically active steroids. Examination of human leukemic lymphoblasts has revealed these receptors in some tumor samples. Their presence is well correlated with hormone responsiveness of the tumor . Similar studies on human breast cancer tumor homogenates has indicated that about of primary tumors contain estrogen receptor. The absence of receptor predicts a lack of response to hormone therapy almost invariably, while the presence of receptor increases but does not assure that the tumor will be hormone responsive. Recently tissue culture systems which mimic the hormone responses observed have been developed which should significantly aid in the clarification of the mechanisms whereby steroid hormones stimulate and inhibit growth in target tissues. 相似文献
5.
P S Coleman B Lavietes R Born A Weg 《Biochemical and biophysical research communications》1978,84(1):202-207
It is known that rat hepatoma mitochondria contain higher levels of endogenous cholesterol than do mitochondria from normal liver. In the experiments described here, normal liver mitochondria were enriched with cholesterol by a solid-state transfer process and some of their enzymic properties were compared with literature values reported for hepatoma mitochondria. Striking parallels were seen. The data indicate that normal mitochondria, enriched with cholesterol , may create an interesting model system for examining some metabolic characteristics of tumor mitochondria. 相似文献
6.
A particulate factor of rat liver is described which interconverts three forms of rat liver cytosolic tyrosine aminotransferase with no alteration of enzyme activity. The factor appears to be a heat- and pH-sensitive lysosomal protein. The interconversion process is stimulated by 2.5 mM MgCl2 and 2.5 mM ATP. Asparate aminotransferase multiple forms are also susceptible to interconversion by the lysosomal factor. The properties of the factor explain several anomalous effects of manipulation on the tyrosine aminotransferase forms which have been reported in the literature and implicate the form interconversion in the degradation of tyrosine aminotransferase. 相似文献
7.
As cyclic AMP has been associated with the inhibition of lymphocyte cytotoxicity, studies were performed to investigate adenyl cyclase activity in lymphocytes and macrophages of Toxoplasma-infected mice in which the efferent limb of the cell-mediated immune response had previously been found to be activated. In peritoneal or splenic lymphocytes from mice chronically infected with Toxoplasma in which growth of an isogeneic bladder tumor was found to be inhibited, adenyl cyclase activity was significantly less than in lymphocytes from uninfected control mice. Stimulation by prostaglandin E1 or NaF in vitro led to higher levels of adenyl cyclase activity in lymphocytes from unifected animals than in cells from Toxoplasma-infected animals. Similar observations were made with peritoneal macrophages from Toxoplasma-infected and uninfected mice. Lower levels of adenyl cyclase activity were also found in lymphocytes from tumor-bearing mice than in lymphocytes from nontumor-bearing controls. These data suggest that production of cyclic AMP by lymphocytes is inhibited with activation of certain cell-mediated immune functions. 相似文献
8.
CS7BL/6 mice were sensitized with an ip injection of allogeneic P-815 mastocytoma cells. Fifteen days later the spleen cells of the tumor allosensitized mice were cultured and tested for their responsiveness to mitogens and alloantigens, and for their ability to generate cytotoxic cells in vitro. The results indicate that 15 day tumor-sensitized spleen cells are hypo-responsive in mixed lymphocyte culture (MLC) with DBA/2 or AKR as stimulating spleen cells. The cells which are hypo-responsive in MLC can proliferate in response to mitogens and they also can generate cytotoxic cells in vitro. MLC reactivity recovers in about 2–3 months which is months after the mice have rejected their tumors. The mechanism of MLC hypo-responsiveness was investigated. The results suggest the presence of a suppressor cell which does not appear to be a macrophage or a B-cell. The suppressor cell can be separated from the cytotoxic cell and therefore appears to be a noncytotoxic T-cell. 相似文献
9.
Contractile responses to serotonin were examined in the longitudinal portal vein to determine whether such responses were mediated by the interaction of serotonin with 5HT1 receptors (those that preferentially bind [3H]serotonin) or 5HT2 receptors (those that preferentially bind [3H]spiperone). Using eight serotonin receptor antagonists (spiperone, metergoline, LY53857, ketanserin, trazodone, benzoctamine, 1-(1-naphthyl)piperazine, and 1-meta-methoxyphenylpiperazine), we found a significant correlation between the affinity for serotonin receptors in the rat portal vein and the ability to bind to 5HT2, but no 5HT1 receptors in rat frontal cortical membranes. Thus, the receptors mediating vascular contraction to serotonin in the rat portal vein were similar to those receptors defined in other vascular beds from the rat (aorta, jugular vein, and caudal artery). Furthermore, contraction resulting from the cumulative addition of serotonin in the rat portal vein was associated with desensitization (higher ED50 value) relative to contractions produced by the non-cumulative addition of serotonin. Affinities of serotonin receptor antagonists were also lower when determined by antagonism of cumulative serotonin concentration-response curves compared to affinities obtained by antagonism of non-cumulative concentration-response curves. Thus, 5HT2 receptor affinities of antagonists in the rat portal vein are best determined by the shift of non-cumulative responses to serotonin. 相似文献
10.
Adoptive transfer of both bone marrow and thymus cells is needed in lethally irradiated syngeneic mice to elicit CICC and CDCC responses against SRBC as assayed by the 51Cr-release cytotoxic test. The contribution of thymocytes to both CDCC and CICC was assessed by limiting dilution assays in BDF1 and CDF1 mice. Irradiated mice were reconstituted with a large number of bone marrow cells and graded limiting numbers of thymocytes, and were then immunized with SRBC. The limiting dilution plots conformed to the Poisson Model for both types of responses and both strains of mice. The numbers of thymocytes required for about 63% of the recipient spleens to be positive (i.e., the inoculum sizes containing one detectable antigen reactive unit) were similar for both CDCC and CICC ( thymocytes) in both strains. Chi-square tests, at the 0.01 level of significance, were incompatible with the hypothesis that CICC and CDCC are independent of each other. Limiting dilutions of bone marrow cells with larger numbers of thymus cells, using CDF1 mice, showed a non-Poisson curve for both CICC and CDCC. Chi-square values were compatible with the hypothesis of independent assortment of responses, as if the potential of the majority of precursors were restricted to either CICC or CDCC, but not to both. In contrast, BDF1 mice showed a Poisson curve for CDCC and a non-Poisson curve for CICC. Chi-square values were also compatible with independent assortment of responses. 相似文献
11.
The ability of various prostaglandins (PGs) to affect the anamnestic immune response of keyhole limpet hemocyanin (KLH)-primed rabbit popliteal lymph node cells was investigated. Of the four PGs studied (PGA1, PGE2 and PGF2α), PGE1 was found to have a stimulatory effect, whereas PGA1, PGE2 and PGF2α were ineffective in stimulating or inhibiting the anamnestic response. Under the conditions studied, a 3.5-fold increase in antibody production was obtained in PGE1-treated, KLH-stimulated cultures. Maximum enhancement was obtained when 0.2 μg of PGE1 were added at the time of culture initiation and were allowed to remain in contact with the lymph node cells for 24 hours. 相似文献
12.
E Ambellan 《Biochemical and biophysical research communications》1974,57(2):520-525
Glucocorticoid binding to certain cell particles of rat liver and thymus following treatments and consists in part of a very “tight binding” that resists hot and cold perchloric acid extractions. This binding is found in thymus nuclei and in liver cytoplasmic particles, but not in liver nuclei nor in thymus mitochondria or microsomes. The existence of “tight binding” coincides with the ability of the same particles to bind free corticoid directly in incubations . The difference in the cellular location of this binding suggests that different methods of glucocorticoid activation exist in the anabolic target tissue, liver, and the catabolic target tissue, rat thymus. 相似文献
13.
Microbial transformation experiments were conducted with the antitumor lactone withaferin-A. NRRL 1393 transformed withaferin-A () to 15β-hydroxywithaferin-A () and 12β-hydroxywithaferin-A (). The hydroxylated metabolites were isolated by solvent extraction and were purified by column and thin-layer chromatography. Structures of the hydroxylated metabolites were determined by protonand carbon-13 NMR, IR and mass spectral analyses, and by the preparation of acylated derivatives. Compounds and inhibited the growth and biochemical functions of grown P-388 lymphocytic leukemic cells. 相似文献
14.
A.W. Ford-Hutchinson A. Rackham R. Zamboni J. Rokach S. Roy 《Prostaglandins & other lipid mediators》1983,25(1):29-37
Synthetic leukotriene B4 (LTB4) and its ω-oxidation products, 20 OH-LT4 and 20 COOH-LTB4, were tested for their ability to induce the aggregation of rat neutrophils , to contract the guinea pig parenchymal strip and to cause vascular permeability changes in rabbit skin . 20 OH-LTB4 had 10, 100 and 20% of the activity of LTB4 in the neutrophil aggregation, parenchymal strip and vascular permeability assays respectively. 20 C00H-LTB4 was inactive and showed <1% of the activity of LTB4. These results show that while ω-oxidation is a route for biological inactivation of LTB4, 20 OH-LTB4 still retains significant biological activity. 相似文献
15.
The objective of this study was to compare the ability of porcine blastocysts to attach to various cellular and non-cellular substrates . One hundred twenty-two hatched blastocysts were collected from 17 handmated gilts and sows at slaughter. Blastocysts were randomly assigned to one of four treatments: Minimal Essential Medium (MEM) supplemented with 10% (v/v) heat treated fetal calf serum (HTFCS), monolayers of bovine uterine fibroblasts in MEM + 10% HTFCS (Buf), monolayers of bovine testicular fibroblasts in MEM + 10% HTFCS (Btes), and MEM + 10% HTFCS exposed to uterine fibroblasts for 24 hr to condition the medium (cMEM). Embryos were cultured individually in 24 well Linbro culture plates at 37 C in a humidified gas atmosphere of 5% CO2 in air. Embryos were observed at 24 hr intervals by phase contrast microscopy (100X) and measured with an ocular micrometer. Blastocyst attachment was greater (P < .01) in Buf () compared to MEM (), cMEM (), and Btes (). Embryo diameter was greater (P < .05) 24 hr prior to attachment in Buf compared to the other treatments. In addition, trophoblast monolayers continued to proliferate for 20 days when cocultured with uterine fibroblasts. These observations suggest that uterine fibroblasts provide a superior substratum for blastocyst attachment and the maintenance of swine trophoblast cells . 相似文献
16.
C I Hong A Nechaev C R West 《Biochemical and biophysical research communications》1979,88(4):1223-1229
Superior antitumor activity of 1-β-D-arabinofuranosylcytosine (ara-C) conjugates of prednisolone and prednisone against L1210 leukemic mice, based on ara-C content, has encouraged us to synthesize 5′-(cortisone-21-phosphoryl)-1-β-D-arabinofuranosylcytosine (I) and 5′-(cortisone-21-phosphoryl)-1-β-d-arabinofuranosylcytosine (II) by condensation of N4,2′,3′-triacetyl-1-β-d-arabinofuranosylcytosine 5′-monophosphate with cortisol and cortisone in the presence of N,N′-dicyclohexylcarbodiimide at room temperature followed by removing the acetyl groups in 2 N methanolic ammonia in 20% yield. The conjugates I and II inhibited the growth of L1210 by 50% (ED50) at 0.25 μM and 0.07 μM, respectively, while ara-C showed ED50 0.1 μM. However, the conjugates I and II exhibited 287% and 238% of at 50 mg/kg/day × 5 doses against L1210 leukemic mice, respectively, while ara-C at 25 mg and 50 mg/kg/day × 5 gave the respective 127% and 110% of . 相似文献
17.
Phenoxybenzamine was antinociceptive in the mouse tail electrical stimulation assay (ED50, 36.8 mg/kg) with a peak effect at hours after subcutaneous injection. Naloxone antagonized this antinociception action of phenoxybenzamine in a dose-related manner. Dose-ratio analysis of naloxone's antagonism of phenoxybenzamine antinociception gave a pA2 value of 6.15, similar to that found for the benzomorphinan mixed agonist-antagonists. This is in agreement with the sodium response ratio found for phenoxybenzamine, 4.3, in assays of phenoxybenzamine inhibition of 3H-naloxone binding to mouse brain homogenate (5). These findings suggest that phenoxybenzamine binds to the opiate receptor both as well as in a manner similar to the mixed agonist-antagonists. 相似文献
18.
19.
S E Steinberg C Campbell R S Hillman 《Biochemical and biophysical research communications》1981,98(4):983-989
The effect of N2O-induced vitamin B12 deficiency on folate metabolism was studied in an animal model previously developed for studies of the folate enterohepatic cycle, and in rats with localized, subcutaneous tumor nodules. While N2O inhibited liver folate polyglutamate formation, it did not affect the absorption of (3H)PteGlu1 from the gut, its reduction, methylation, and transport to the liver, or the subsequent secretion of CH3H4(3H)PteGlu1 into bile—the folate enterohepatic cyle. In addition, N2O did not impair folate polyglutamate formation in the fibrosarcoma tumor nodule suggesting that tumor tissue can either demethylate CH3H4PteGlu1 by an alternate pathway or can utilize it as a substrate for polyglutamate formation without demethylation. 相似文献
20.
Carnitine synthesis in rat tissue slices 总被引:2,自引:0,他引:2
The ability of rat liver, kidney, muscle, heart and testis tissue to carry out the synthesis of carnitine via ε-N-trimethyllysine and γ-butyrobetaine was studied. All tissues formed γ-butyrobetaine from trimethyllysine, but liver and testis also formed carnitine in about 7% and 1% yield respectively. Liver slices formed trimethyllysine from lysine in about 6% yield. These studies thus establish that liver has all the enzymes of the carnitine biosynthetic pathway. This tissue appears to be the primary site of carnitine synthesis in the rat as implied from whole animal studies in this and other laboratories. 相似文献