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排序方式: 共有695条查询结果,搜索用时 9 毫秒
51.
A rapid method to capture and screen for transcription factors by SELDI mass spectrometry. 总被引:12,自引:0,他引:12
52.
53.
Balagopal P Pandey M Chandramohan K Somanathan T Kumar A 《World journal of surgical oncology》2003,1(1):4
Background
Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain. 相似文献54.
Although calpain has been extensively studied, its physiological function is poorly understood. In contrast, its role in the pathophysiology of various diseases has been implicated, including that of experimental allergic encephalomyelitis (EAE), an animal model of the demyelinating disease multiple sclerosis (MS). In EAE, calpain degrades myelin proteins, including myelin basic protein (MBP), suggesting a role for calpain in the breakdown of myelin in this disease. Subsequent studies revealed increased calpain activity and expression in the glial and inflammatory cells concomitant with loss of axon and myelin proteins. This suggested a crucial role for calpain in demyelinating diseases. 相似文献
55.
Epizootiology of the parasitic dinoflagellate Hematodinium sp. in the American blue crab Callinectes sapidus 总被引:1,自引:0,他引:1
Hematodinium sp. is a parasitic dinoflagellate that infects and kills blue crabs Callinectes sapidus. Periodic outbreaks of dinoflagellate infections with subsequent high host mortalities prompted a study of the epizootiology and distribution of the crab pathogen. Hemolymph samples from over 13000 crabs were assessed for infections over 8 yr. Moderate to high prevalences were found at several locations along the Atlantic and Gulf coasts of the United States. In the coastal bays of Maryland and Virginia, prevalence followed a seasonal pattern, with a sharp peak in late autumn. Infections were significantly more prevalent in crabs measuring less than 30 mm carapace width; host sex did not influence prevalence. Prevalences were highest in crabs collected from salinities of 26 to 30%o; no infected crabs were found in salinities below 11%o. Intensity of infection did not vary among crab sizes, molt stages, or sexes. Naturally and experimentally infected crabs died over 35 and 55 d in captivity, with a mean time to death of approximately 13 and 42 d, respectively. Several other crustaceans, including gammaridean amphipods, xanthid (mud) crabs, and the green crab Carcinus maenus, were found with Hematodinium-like infections. Considering its widespread distribution and high pathogenicity, we suggest that Hematodinium sp. represents a significant threat to blue crab populations in high salinity estuaries along the Atlantic and Gulf coasts of the USA. 相似文献
56.
In the assessment of human origins, chimpanzees (Pan troglodytes, henceforth called Pan) represent the best hominoid outgroup for comparisons. Such an outgroup roots the "anatomically modern" human population cluster, or continuum. This study incorporates chimpanzees into a worldwide modern human database of quantified complete tooth variables (approximately 30 per tooth; e.g., root, pulp, enamel) in an attempt to develop a more accurate phylogeny of the hominoid continuum, with only intervening extinct hominids missing. Canonical discriminate analysis was performed mainly among Liberian common chimpanzees and global samples of humans. The first canonical variable explained 70% of the total variance and showed a tight cluster of humans, with chimpanzees as a distant outgroup. Within the human community, first non-San Bushman, sub-Saharan Africans and Andamanese, and then, close in, Australian aborigines were positioned towards Pan. Their relative orientation suggested an African human origin with the first branch within sub-Saharan Africa: sub-Saharan Africans and San Bushmen. Next, Andamanese Negritos, and then Australian aborigines, formed the early first surviving modern human lineage to leave Africa. Thin enamel and big teeth with relatively large roots characterized Pan nonmolar teeth. Humans showed a generalized sexual dimorphism for all teeth, with males having bigger teeth, bigger relative roots, and thinner enamel than females, while only Pan canines had significant and impressive sexual dimorphism. Interestingly, Pan molars were not larger than human molars. The data suggest that although hominids underwent two dental macroevolutionary events, the lineage leading to modern humans only experienced anterior tooth-size reduction. The suggested evolutionary significance of the observed total tooth variation is discussed. 相似文献
57.
Understanding Ras: 'it ain't over 'til it's over' 总被引:15,自引:0,他引:15
Since 1982, Ras has been the subject of intense research scrutiny, focused on determining the role of aberrant Ras function in human cancers and defining the mechanism by which Ras mediates its actions in normal and neoplastic cells. The long-term goal has been to develop antagonists of Ras as novel approaches for cancer treatment. Although impressive strides have been made in these endeavours, and our knowledge of Ras is quite extensive, it appears that we are at the beginning, rather than at the end, of fully understanding Ras function. This review highlights new issues that have further complicated our efforts to understand Ras. 相似文献
58.
Gene conversion among chemokine receptors 总被引:2,自引:0,他引:2
Shields DC 《Gene》2000,246(1-2):239-245
It has been proposed that proteins which are involved in host defence and susceptibility undergo accelerated evolution. Chemokine receptors have roles as pro-inflammatory agents acting in response to infection, and in addition are receptors for entry of viruses and other pathogens into cells. Consistent with this, their rate of evolution is higher than that for other members of the seven-transmembrane domain receptor family. The pattern of evolution of the chemokine receptors was examined in detail. Both chromosomal clusters of chemokine receptors (CC and CXC) showed evidence of a number of gene conversions. These are likely to have resulted in protein sequence changes, which could possibly alter function. 45% of a control group of clustered genes also showed evidence of conversion. Thus, the fixation of a gene conversion is not in itself sufficiently unusual in tandemly repeated genes and cannot be taken as strong evidence of a selection for a novel function. However, the degree of amino acid difference between the chemokine receptors CCR1 and CCR3 was greater than that for any of the control genes. Such changes could have functional implications for inter-species differences in chemokine receptor interactions with pathogens. 相似文献
59.
Goldman R Day BW Carver TA Mauthe RJ Turteltaub KW Shields PG 《Chemico-biological interactions》2000,126(3):171-183
Quantitation of carcinogen-DNA adducts provides an estimate of the biologically effective dose of a chemical carcinogen reaching the target tissue. In order to improve exposure-assessment and cancer risk estimates, we are developing an ultrasensitive procedure for the detection of carcinogen-DNA adducts. The method is based upon postlabeling of carcinogen-DNA adducts by acetylation with 14C-acetic anhydride combined with quantitation of 14C by accelerator mass spectrometry (AMS). For this purpose, adducts of benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (BPDE) with DNA and deoxyguanosine (dG) were synthesized. The most promutagenic adduct of BPDE, 7R,8S,9R-trihydroxy-10S-(N(2)-deoxyguanosyl)-7,8,9, 10-tetrahydrobenzo[a]pyrene (BPdG), was HPLC purified and structurally characterized. Postlabeling of the BPdG adduct with acetic anhydride yielded a major product with a greater than 60% yield. The postlabeled adduct was identified by liquid chromatography-mass spectrometry as pentakis(acetyl) BPdG (AcBPdG). Postlabeling of the BPdG adduct with 14C-acetic anhydride yielded a major product coeluting with an AcBPdG standard. Quantitation of the 14C-postlabeled adduct by AMS promises to allow detection of attomolar amounts of adducts. The method is now being optimized and validated for use in human samples. 相似文献
60.
Declan T. Bradley Thomas W. Bourke Derek J. Fairley Raymond Borrow Michael D. Shields Peter F. Zipfel Anne E. Hughes 《PloS one》2015,10(3)