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1.
Glycopeptides from the surface of clones of hamster embryo cells were examined at various intervals after infection with polyoma virus. Two types of transformed cells were examined: (i) clones that showed delayed transformation or an initially low tumorigenicity, and (ii) clones that were rapidly transformed showing an initially high tumorigenicity. The glycopeptides were removed from the cell surface by trypsin and, after Pronase digestion, were examined by filtration through Sephadex G-50. With delayed transformation, a specific group of glycopeptides was increasingly evident over an 85-day period as the cells showed phenotypic properties of transformation and the ability to form tumors. In the other series, all but one clone of hamster embryo cells showed rapid transformation after infection with polyoma virus. This clone was less tumorigenic and showed little of the specific glycopeptides. In all cases of delayed or rapid transformation examined, the specific group of glycopeptides increased proportionately to the ability of the cells to form tumors. All of the cells derived from progressively growing tumors formed by injection of these transformed hamster cells into adult animals showed an abundance of this group of glycopeptides. These results suggest that specific surface membrane glycopeptides accompany viral transformation and tumorigenesis.  相似文献   

2.
利用47个根据已报道的QTL位点或者已被精细定位或克隆的与水稻产量性状基因紧密连锁的产量位点标记,对来自中国、印度和越南等国的58份水稻恢复系进行遗传多样性分析。结果表明:(1)在中国恢复系中,47个产量位点标记中有36个具有多态性,共检测到90个等位基因,每个标记检测到等位基因2~4个,平均为2.500个;有效等位基因共62.905个,平均每个标记1.747个;36个有效标记的Shannon信息指数平均值为0.632,变幅为0.271~1.266。(2)在来自国外的材料中,47个产量位点标记均具有多态性,共检测到131个等位基因,每个标记检测到的等位基因数为2~6个,平均2.787个;有效等位基因数共82.686个,平均1.759个;47个标记的Shannon信息指数平均值为0.649,变幅为0.109~1.110。(3)聚类分析显示,在遗传相似系数为0.73水平上,参试资源聚为三大类群,中国资源多聚在第Ⅰ类群下的第1、2、3亚群,越南资源多聚在第Ⅰ-4亚群,孟加拉资源多聚在第Ⅲ-3亚群。由此表明,中国资源遗传基础较为狭窄,而其他国家的恢复系具有较远的亲缘关系。  相似文献   

3.
Significant changes in monoamine levels and utilization were noted in certain brain regions of middle-aged Fisher 344 rats when compared with young adult controls. In the prefrontal cortex and septum, 3,4 dihydroxyphenylglycol (MHPG) and the MHPG/norepinephrine (NE) ratio were decreased. The septum also showed increases in dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) but there was a decrease in the DOPAC/DA ratio. The striatum showed an increase in the MPHG/NE ratio and an increase in DOPAC. The hippocampus and thalamus showed an increase in 5-hydroxyindoleacetic acid (5HIAA). This demonstrates that selected neurotransmitter systems in the brain are altered at an early stage of senescence. This could lead to ensuing neurological deficits.  相似文献   

4.
Forty normal-achieving and 33 learning disabled (LD) children were assigned randomly to either a negative ion or placebo test condition. On a dichotic listening task using consonant-vowel (CV) combinations, both groups showed an ioninduced increase in the normal right ear advantage (REA). However, the mechanisms for this effect were different for each group. The LDs showed the effect at the right ear/left hemisphere (enhancement). The normal achievers showed the effect at the left ear/right hemisphere (inhibition). The results are consistent with an activation-inhibition model of cerebral function and suggest a functional relationship between arousal, interhemispheric activation-inhibition, and learning disabilities. The LDs may have an interhemispheric dysfunction. Both groups showed superior right ear report and the normal achiever showed overall superiority. Normal achievers showed higher consonant intrusion scores, probably due to a greater cognitive capacity. Age was a significant covariate reflecting developmental capacity changes. Negative air ions are seen to be a tool with potential theoretical and remedial applications.  相似文献   

5.
Mutants of a cobalt-containing nitrile hydratase (NHase, EC 4.2.1.84) from Pseudonocardia thermophila JCM 3095 involved in substrate binding, catalysis and formation of the active center were constructed, and their characteristics and crystal structures were investigated. As expected from the structure of the substrate binding pocket, the wild-type enzyme showed significantly lower K(m) and K(i) values for aromatic substrates and inhibitors, respectively, than aliphatic ones. In the crystal structure of a complex with an inhibitor (n-butyric acid) the hydroxyl group of betaTyr68 formed hydrogen bonds with both n-butyric acid and alphaSer112, which is located in the active center. The betaY68F mutant showed an elevated K(m) value and a significantly decreased k(cat) value. The apoenzyme, which contains no detectable cobalt atom, was prepared from Escherichia coli cells grown in medium without cobalt ions. It showed no detectable activity. A disulfide bond between alphaCys108 and alphaCys113 was formed in the apoenzyme structure. In the highly conserved sequence motif in the cysteine cluster region, two positions are exclusively conserved in cobalt-containing or iron-containing nitrile hydratases. Two mutants (alphaT109S and alphaY114T) were constructed, each residue being replaced with an iron-containing one. The alphaT109S mutant showed similar characteristics to the wild-type enzyme. However, the alphaY114T mutant showed a very low cobalt content and catalytic activity compared with the wild-type enzyme, and oxidative modifications of alphaCys111 and alphaCys113 residues were not observed. The alphaTyr114 residue may be involved in the interaction with the nitrile hydratase activator protein of P. thermophila.  相似文献   

6.
Rabbits were fed for 10-12 weeks on a normal pellet diet or on the same diet containing 1% cholesterol and 6% peanut oil. The animals were killed and the aortas divided into three layers which were homogenized and extracted. The extracts and the insoluble residues were assayed for transglutaminase activity and tissue transglutaminase antigen. When compared with normal aortas, the inner and middle layers of aortas with atherosclerotic lesions from cholesterol-fed rabbits showed higher transglutaminase activities in the buffer-soluble fraction without a corresponding increase in antigen. The buffer extracts showed two peaks (I and II) of activity and antigen on DE 52 chromatography; peak I was also found, together with lipid, in Triton X-100 extracts of the buffer-insoluble residue. The Triton X-100 insoluble fraction showed higher concentrations of both activity and antigen in the inner and middle layers of atherosclerotic aortas than in normal aortas, but the activity per nanogram of antigen was lower than in the buffer-soluble fraction. The activity in this insoluble residue was largely extracted, together with an inhibitor, by an NaCl-sucrose-dithiothreitol-Triton X-100 solution. DE 52 chromatography of this extract showed a third peak of activity and antigen (peak III) and an inhibitor peak that was distinct from the activity peaks.  相似文献   

7.
Electron microscopic examination of ultrathin sections and freeze-etched and shadow cast preparations of a bovine prepuce isolate of Campylobacter fetus VC119 showed an S layer with subunits in an apparent linear arrangement. Surface radioiodination, enzyme digestion, low-pH extraction, and Western immunoblotting showed that the layer was composed mainly of one protein which is the predominant protein antigen of C. fetus. This protein was purified to homogeneity by gel filtration, ion-exchange chromatography, and high-performance liquid chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed an apparent molecular weight of 131,000 for this protein with a pI of 6.35, and no carbohydrate could be detected by a variety of techniques. Amino acid composition analysis showed that the protein contained approximately 1,304 residues per molecule, 41.2% of which were hydrophobic and approximately 22% of which were acidic. Cysteine and histidine were absent. Circular dichroism spectra showed that the prominent structure of the S layer protein was a beta-pleated sheet (36%) with aperiodic foldings (31%); a moderate amount of alpha-helix (28%) and a low amount of beta-turn (5%) were also present. The N-terminal amino acid sequence was determined for the first 18 residues. No sequence homology with other S layer proteins was found.  相似文献   

8.
Summary Liver epithelial cells from a young rat were cultured and passaged for a long period until they showed a malignant transformation (tumorigenicity in athymic mice), to know when an autocrine growth factor is produced in the course of a spontaneous malignant transformation of normal cells in vitro. The cells initially showed a cellular transformation and an increased growth rate, then produced an autocrine growth factor after Passage 55, and finally the cells after Passage 105 showed a malignant transformation (tumorigenicity in vivo). It is suggested that in addition to an autocrine growth factor, some other factors might be related to a malignant transformation (tumorigenicity in vivo).  相似文献   

9.
In this study, a 24 factorial experimental design was employed in order to evaluate the influence of the reaction conditions and preparation method on alginate–chitosan hydrogel properties. Alginate content, pH, chitosan molecular weight and the hydrogel preparation method were the independent variables and the reaction yield, particle size, swelling degree and point of zero surface charge were the dependent variables. The results showed that hydrogels were spherical with an average diameter of 5.0 ± 2.0 μm. Reaction yield varied according to the parameters, and chitosan molecular weight showed the greatest influence. Furthermore, the swelling degree and point of zero surface charge showed a linear dependence on the alginate content. In this regard, the study showed that hydrogels with a specific charge and swelling degree can be obtained by controlling the alginate content using the equation here provided to give an enhanced and site-specific controlled drug release.  相似文献   

10.
For prevention of nosocomial infection, 25 infants including high risk patients received an emergency injection of live varicella vaccine. Three patients developed a rash within 5 days after vaccination, but their symptoms were mild. The other 22 showed no clinical symptoms and gave an immune response. Twenty-two patients receiving immunosuppressive therapy were vaccinated and 20 of them showed a positive response in the varicella skin test. Of 14 vaccinated patients with malignancies, 2 giving a positive skin test, later showed clinical varicella, but their symptoms were not severe. One case with ALL was immunized safely under very poor conditions during the first induction therapy. No complications were observed in any patients.  相似文献   

11.
A novel opioid ligand possessing a stable and cyclic imine 16 and its derivatives with an azabicyclo[2.2.2]octane skeleton were synthesized. The imine 16 showed higher affinity for the μ receptor than compound 21 with an oxabicyclo[2.2.2]octane skeleton. Azabicyclo[2.2.2]octane derivative 18d with a cyclopropylmethyl group on the 8-nitrogen showed the highest affinity for the μ receptor among the synthesized derivatives.  相似文献   

12.
The incidence of haemonchosis in sheep and goats in Sierra Leone showed a seasonal variation with a high peak in the dry season (October to January) and a low one from March to May. Mean relative densities were significantly higher in young hosts and showed two peaks, a high one from August to December and a low one from April to June while the mean relative densities of old hosts were low and exhibited an irregular seasonal pattern with no defined peaks. The peak seasons in young hosts coincided approximately with the dry and rainy seasons. Male hosts showed an overall higher but not a significant mean relative density than females but for most of the months mean relative densities of infection of female hosts were not significantly higher than those of males. The roles of climatic conditions and arrested development (hypobiosis) and self-cure and host age immunity on Haemonchus contortus worm burdens are discussed.  相似文献   

13.
The soft-electron beam (low-energy electrons) and gamma-radiation sensitivities of phosphine-resistant (PHR) and -susceptible (PHS) strains of adults lesser grain borer Rhyzopertha dominica (F.) were studied, with particular reference to DNA damage assessed using single-cell electrophoresis (comet assay). Results showed that mortality in adult R. dominica varied significantly between both PHR and PHS strains. Adults of the PHR strain were found to be more tolerant toward soft-electron and gamma radiation than adults of the PHS strain. Studies on the longevity of strains showed that mean survival time and dose rate were highly correlated with both strains and treatments. Results also showed that adults of the PHR strain lived longer than adults of PHS strain for both treatments. Radiation sensitivity indices, however, decreased as radiation dose increased in both strains. Analysis of DNA damage, after 40- and 160-Gy gamma radiation, was carried out using cells obtained from both strains. Gamma-irradiated adults of both strains showed typical DNA fragmentation, compared with cells from nonirradiated adults, which showed more intact DNA. Investigations using the comet assay showed that tail length, moment, olive-tail moment, percentage of tail DNA, and percentage of DNA damage were all greater in the PHS strain compared with the PHR strain and the control insects. Results also showed that DNA damage remained at a constant level for up to 24 h after irradiation. The results have been discussed in relation to the observed strain differences in radiation sensitivity and resistance to phosphine.  相似文献   

14.
Two series of azanaphthoquinone annelated pyrrolo oximes have been synthesized. The antiproliferative activities of 10 compounds were evaluated on at least four different cell lines. One series of pyrrolo derivatives showed high cytotoxic activity. The effects on cell cycle and caspase activity were investigated. Compounds 9a and 9b showed an accumulation of cells in G2/M phase. Substantial and dose-dependent caspase activity was found after treatment of cells with 9a and 9b. This indicates an apoptosis inducing property of these compounds.  相似文献   

15.
A new phosmidosine analog 10, in which the proline and 8-oxoadenosine moieties were linked by an N-acyl sulfamate linkage, was successfully synthesized by the sulfamoylation of an 8-oxoadenosine derivative 5 followed by coupling with an L-proline derivative 8. An L-alanine-substituted derivative 13 and its derivative 14 without the alanyl residue were also synthesized. The morphological reversion activity of these synthetic compounds in v-src(ts) NRK cells and their antitumor activity in L1210 and KB cells were studied. As the result, neither L-proline- nor L-alanine-substituted phosmidosine analogs 10 and 13 showed any antitumor activity. Contrary to these results, the derivative 14 lacking the amino acid residue showed potent antitumor activities against cancer cells.  相似文献   

16.
Laforga JB 《Acta cytologica》1999,43(2):263-267
BACKGROUND: Giant cell carcinoma (GCC) of the lung is an unusual tumor characterized by an aggressive outcome. CASE: A peripheral lung tumor was observed in an elderly male. At presentation the clinical symptoms were cough, thoracic pain and hemoptysis. Chest roentgenography showed a left pleural effusion and neutrophilia in the blood. Bronchoscopic examination showed a peripheral tumor mass that could not be biopsied. Bronchoalveolar lavage was negative. The patient underwent a cerebrovascular accident and died. The autopsy showed a peripheral giant cell tumor of the left lung that involved regional and mediastinal lymph nodes. Touch imprints showed tridimensional clusters of pleomorphic and large cells, some of which were multinucleated, containing leukocytes in their cytoplasm. CONCLUSION: This case illustrates the typical cytohistologic features of GCT of the lung, which should be considered in the differential diagnosis of any peripheral lung tumor composed of large cells. Clinical correlation is helpful in reaching the correct diagnosis.  相似文献   

17.
以云南高黎贡山百花岭不同海拔梯度(1500~3100 m)的短肋羽藓(Thuidium kanedae)为材料,通过测定其叶绿素含量和实际光合量子产量,研究其光合特性随海拔梯度变化的规律。结果表明,短肋羽藓的实际光合量子产量Y(Ⅱ)与叶绿素总量、叶绿素a、叶绿素b含量及叶绿素a/b比值之间都呈负相关关系。随着海拔升高,其叶绿素总含量、叶绿素a及叶绿素b含量都呈先升高而后下降的“单峰”分布模式,但随着海拔进一步升高,叶绿素总含量及叶绿素a含量变化不明显,而叶绿素b含量呈现明显上升趋势。叶绿素a/b比值随着海拔升高先呈现“单峰”分布模式,然后随着海拔继续升高呈现缓慢下降的趋势。实际光合量子产量Y(Ⅱ)整体表现出随海拔升高而增加的趋势,并在高海拔处出现急剧上升的趋势。本研究为揭示苔藓植物在不同海拔梯度下适应生态环境的生理机制提供参考。  相似文献   

18.
During 1983 a severe episode of respiratory infection occurred in a marmoset colony at these laboratories. Of 91 marmosets, 69 showed clinical signs of disease, one died and nine were so ill that euthanasia was necessary. Eight were examined post mortem and all showed consolidation of the lungs. Laboratory studies were carried out in an attempt to establish the cause of the outbreak and an interstitial pneumonia was found in seven animals which were examined histologically. Direct electron microscopy of nasal swabs and lung samples revealed the presence of a high titre of a paramyxovirus, and subsequent immunofluorescence studies established that the particular paramyxovirus involved was parainfluenza virus type I. Subsequent studies showed that surviving affected animals had seroconverted to parainfluenza I virus while animals that had not been implicated in the outbreak had not.  相似文献   

19.
Vibrio mimicus strains W-26768 (stool isolate) and N-1301 (environmental isolate) and Vibrio fluvialis strains AA-18239 (stool isolate) and M-940 (environmental isolate) were studied for virulence properties and lipopolysaccharide composition. All four strains were hydrophobic, produced cytotoxin, adhered to HeLa cells and showed mannose-sensitive agglutination of guinea pig erythrocyte. The strains were negative for enterotoxin production and were mostly susceptible to the common antibiotics. The environmental and clinical isolates of both species were antigenically unrelated to each other. Lipopolysaccharide antigen analysis showed that O-antigen polysaccharides of two strains of V. fluvialis and two strains of V. mimicus differed with respect to the sugar components. Only LPS from V. mimicus W-26768 showed the presence of an unusual sugar, 3,6-dideoxy-3-acetamido-hexose. The sugar compositions of these V. fluvialis and V. mimicus strains differed from those of previously reported Japanese isolates. These differences probably reflect differences in the serogroup of strains.  相似文献   

20.
Hepatocytes were isolated by EDTA perfusion of livers from lean (Fa/-) and obese (fa/fa) Zucker rats. Triacylglycerol (TG) and sn-glycerol 3-phosphate were increased in fa/fa hepatocytes, but free fatty acids, cholesterol and phospholipid concentrations were similar in both groups. In spite of an identical fatty acid uptake rate, glycerolipid synthesis was higher in obese compared to lean rat hepatocytes, and this difference remained for at least 2-3 days of culture. Triacylglycerol mass secretion was 2-fold higher in obese than in lean rat hepatocytes. This was confirmed by the higher incorporation of labeled glycerol and oleic acid into the medium TG fraction floating at density 1.006 g/ml. Density gradient ultracentrifugation of [14C]oleate-labeled lipoproteins showed that fa/fa hepatocytes secreted more TG-rich lipoproteins, and that 87% of the label was in the VLDL fraction compared with 67% in the medium of Fa/- hepatocytes. Decreased utilisation of leucine for protein synthesis in obese rat compared to lean rat hepatocytes was associated with enhanced leucine oxidation to CO2. [35S]Methionine incorporation showed an identical cell protein synthesis rate. Autoradiography after PAGE separation of secreted apolipoproteins (apoBh, Bl, apoA-VI, apoE, apoA-I, apoC) showed an identical pattern in both cell types.  相似文献   

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