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排序方式: 共有395条查询结果,搜索用时 31 毫秒
101.
Paul A. Crossey Keith Foster Frances M. Richards Maude E. Phipps Farida Latif Kalman Tory Michael H. Jones Elizabeth Bentley Ram Kumar Michael I. Lerman Bert Zbar Nabeel A. Affara Malcolm A. Ferguson-Smith Eamonn R. Maher 《Human genetics》1994,93(1):53-58
Von Hippel-Lindau (VHL) disease is a dominantly inherited familial cancer syndrome characterised by the development of retinal and central nervous system haemangioblastomas, renal cell carcinoma (RCC), phaeochromocytoma and pancreatic tumours. The VHL disease gene maps to chromosome 3p25-p26. To investigate the mechanism of tumourigenesis in VHL disease, we analysed 24 paired blood/tumour DNA samples from 20 VHL patients for allele loss on chromosome 3p and in the region of tumour suppressor genes on chromosomes 5, 11, 13, 17 and 22. Nine out of 24 tumours showed loss of heterozygosity (LOH) at at least one locus on chromosome 3p and in each case the LOH included the region to which the VHL gene has been mapped. Chromosome 3p allele loss was found in four tumour types (RCC, haemangioblastoma, phaeochromocytoma and pancreatic tumour) suggesting a common mechanism of tumourigenesis in all types of tumour in VHL disease. The smallest region of overlap was between D3S1038 and D3S18, a region that corresponds to the target region for the VHL gene from genetic linkage studies. The parental origin of the chromosome 3p25-p26 allele loss could be determined in seven tumours from seven familial cases; in each tumour, the allele lost had been inherited from the unaffected parent. Our results suggest that the VHL disease gene functions as a recessive tumour suppressor gene and that inactivation of both alleles of the VHL gene is the critical event in the pathogenesis of VHL neoplasms. Four VHL tumours showed LOH on other chromosomes (5q21, 13q, 17q) indicating that homozygous VHL gene mutations may be required but may not be sufficient for tumourigenesis in VHL disease. 相似文献
102.
103.
The possible relationship of the soluble, “cytosolic” estradiol receptor with complex membranous and cytoskeletal structures of the cell matrix has been studied using a model erythrocyte system. Extraction of erythrocyte ghosts with a nonionic detergent (Triton X-100) under conditions that yield a cytoskeletal matrix reveals the presence of a limited number (less than 100) of specific sites having high affinity (kd 10?9 M) for the estradiol-receptor complex. The interation between the estradiol receptor and the cytoskeleton is critically dependent on temperature and it is improved by 25 mM KCl or NaCl and by 2.5 mM MgCl2. The data suggest that the estradiol receptor, which has been generally considered to be freely “soluble” in the cytoplasm, may actually be physiologically associated in an integral manner with a complex cytoskeletal network in the cell cytoplasm. 相似文献
104.
The nucleotide sequence of recG, the distal spo operon gene in Escherichia coli K-12. 总被引:4,自引:0,他引:4
A gene is identified in the Escherichia coli K-12 spo operon as recG. Previously identified genes in the spo operon were spoS, alias rpoZ, encoding the omega (omega) subunit of RNA polymerase, as well as the spoT gene encoding the major cellular source of guanosine 3',5'-bispyrophosphate hydrolase activity. The gene order within the spo operon is: spoS (rpoZ), spoT, spoU, recG. A convergent gltS gene is present beyond the spo operon. Mutants bearing recG deletion-insertion alleles display mild sensitivities to both ultraviolet irradiation and to mitomycin C, which is expected to be due to a known recG insertion allele. Deletion-insertion mutations in upstream operon genes (spoT and spoU) show polar effects on these assays of recG function. The deduced 693-amino acid (aa) RecG sequence shows a weak, but significant, relatedness to aa sequence motifs previously reported for putative helicases involved in replication, recombination, and DNA repair. 相似文献
105.
Cell Wall Structure in Cells Adapted to Growth on the Cellulose-Synthesis Inhibitor 2,6-Dichlorobenzonitrile : A Comparison between Two Dicotyledonous Plants and a Graminaceous Monocot 总被引:4,自引:2,他引:2 下载免费PDF全文
Our previous work (E. Shedletzky, M. Shmuel, D.P. Delmer, D.T.A. Lamport [1990] Plant Physiol 94:980-987) showed that suspension-cultured tomato cells adapted to growth on the cellulose synthesis inhibitor 2,6-dichlorobenzonitrile (DCB) have a markedly altered cell wall composition, most notably a markedly reduced level of the cellulose-xyloglucan network. This study compares the adaptation to DCB of two cell lines from dicots (tomato [Lycopersicon esculentum] and tobacco [Nicotiana tabacum]) and a Graminaceous monocot (barley [Hordeum bulbosum] endosperm). The difference in wall structures between the dicots and the monocot is reflected in the very different types of wall modifications induced by growth on DCB. The dicots, having reduced levels of cellulose and xyloglucan, possess walls the major integrity of which is provided by Ca2+-bridged pectates because protoplasts can be prepared from these cells simply by treatment with divalent cation chelator and a purified endopolygalacturonase. The tensile strength of these walls is considerably less than walls from nonadapted cells, but wall porosity is not altered. In contrast, walls from adapted barley cells contain very little pectic material and normal to elevated levels of noncellulosic polysaccharides compared with walls from nonadapted cells. Surprisingly, they have tensile strengths higher than their nonadapted counterpart, although cellulose levels are reduced by 70%. Evidence is presented that these walls obtain their additional strength by an altered pattern of cross-linking of polymers involving phenolic components. Such cross-linking may also explain the observation that the porosity of these walls is also considerably reduced. Cells of adapted lines of both the dicots and barley are resistant to plasmolysis, suggesting that they possess very strong connections between the wall and the plasma membrane. 相似文献
106.
Zoltn Fontnyi Rka Eszter Sziva va Pl Leila Hadjadj Anna Monori-Kiss Eszter Mria Horvth Rita Benk Attila Magyar Andrea Heinzlmann Zoltn Beny Gyrgy L. Ndasy Gabriella Masszi Szabolcs Vrbír 《Current issues in molecular biology》2021,43(1)
Background: Vitamin D deficiency (VDD) may be considered an independent cardiovascular (CV) risk factor, and it is well known that CV risk is higher in males. Our goal was to investigate the pharmacological reactivity and receptor expression of intramural coronary artery segments of male rats in cases of different vitamin D supply. Methods: Four-week-old male Wistar rats were divided into a control group (n = 11) with optimal vitamin D supply (300 IU/kgbw/day) and a VDD group (n = 11, <0.5 IU/kgbw/day). After 8 weeks of treatment, intramural coronary artery segments were microprepared, their pharmacological reactivity was examined by in vitro microangiometry, and their receptor expression was investigated by immunohistochemistry. Results: Thromboxane A2 (TXA2)-agonist induced reduced vasoconstriction, testosterone (T) and 17-β-estradiol (E2) relaxations were significantly decreased, a significant decrease in thromboxane receptor (TP) expression was shown, and the reduction in estrogen receptor-α (ERα) expression was on the border of significance in the VDD group. Conclusions: VD-deficient male coronary arteries showed deteriorated pharmacological reactivity to TXA2 and sexual steroids (E2, T). Insufficient vasoconstrictor capacity was accompanied by decreased TP receptor expression, and vasodilator impairments were mainly functional. The decrease in vasoconstrictor and vasodilator responses results in narrowed adaptational range of coronaries, causing inadequate coronary perfusion that might contribute to the increased CV risk in VDD. 相似文献
107.
The plant-specific cyclin-dependent kinase CDKB1;1 and transcription factor E2Fa-DPa control the balance of mitotically dividing and endoreduplicating cells in Arabidopsis 下载免费PDF全文
Boudolf V Vlieghe K Beemster GT Magyar Z Torres Acosta JA Maes S Van Der Schueren E Inzé D De Veylder L 《The Plant cell》2004,16(10):2683-2692
108.
Magyar A Wölfling J Kubas M Cuesta Seijo JA Sevvana M Herbst-Irmer R Forgó P Schneider G 《Steroids》2004,69(5):301-312
Steroidal aryliminium salts were prepared from D-seco-pregnene aldehyde 2b, and their BF3.OEt2-catalyzed reactions were studied. The nature of the substituent R1 in the anilines 3-6 essentially influenced the chemoselectivity. Using unsubstituted 3, 4-methoxy- (4) or 4-bromoaniline (5), different tetrahydroquinoline derivatives 7a-13a via intramolecular hetero Diels-Alder reaction were formed. In the case of 4-nitroaniline (6) the N-arylamino-D-homopregnane (14a) were also obtained. We assume, that an intramolecular Prins reaction led to this type of fluoro-D-homosteroid. The main products represent a new class of tetrahydroquinolino-androstenes. 相似文献
109.
Altered nitric oxide production in mouse brain after administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridin or methamphetamine 总被引:3,自引:0,他引:3
Several studies have demonstrated the involvement of reactive nitrogen and oxygen species (RNOS) in the neurotoxic effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydro-pyridin (MPTP) and methamphetamine (METH), so the contribution of altered nitric oxide synthase (NOS) enzyme function can be suspected. In this study, about 50% increase in nitric oxide (NO) production in the mouse striatum was found between 4 and 12 h after a single MPTP injection, allowing an increased peroxynitrite (ONOO−) formation in the target brain region. However, METH injection induced a rapid decrease of NO formation both in mouse striatum and hippocampus, reaching its minimum level at 2 h, and restored to the control value after 6 h in the striatum and 12 h in the hippocampus. The uncoupled function of NOS with increased superoxide (O2−) production after METH injection is suggested. 相似文献
110.
McWhinney C Wenham D Kanwal S Kalman V Hansen C Robishaw JD 《The Journal of biological chemistry》2000,275(3):2087-2097
Activation of alpha(1)-adrenergic receptors influences both the contractile activity and the growth potential of cardiac myocytes. However, the signaling pathways linking activation of specific alpha(1)-adrenergic receptor (AR) subtypes to these physiological responses remain controversial. In the present study, a molecular approach was used to identify conclusively the signaling pathways activated in response to the individual alpha(1A)- and alpha(1B)-AR subtypes in cardiac myocytes. For this purpose, a mutant alpha(1a)-AR subtype (alpha(1a)-S(290/293)-AR) was constructed based on analogy to the previously described constitutively active mutant alpha(1b)-AR subtype (alpha(1b)-S(288-294)-AR). The mutant alpha(1a)-S(290/293)-AR subtype displayed constitutive activity based on four criteria. To introduce the constitutively active alpha(1)-AR subtypes into cardiac myocytes, recombinant Sindbis viruses encoding either the alpha(1a)-S(290/293)-AR or alpha(1b)-S(288-294)-AR subtype were used to infect the whole cell population with >90% efficiency, thereby allowing the biochemical activities of the various signaling pathways to be measured. When expressed at comparable levels, the alpha(1a)-S(290/293)-AR subtype exhibited a significantly elevated basal level as well as agonist-stimulated level of inositol phosphate accumulation, coincident with activation of atrial natriuretic factor-luciferase gene expression. By contrast, the alpha(1b)-S(288-294)-AR subtype displayed a markedly increased serum response element-luciferase gene expression but no activation of atrial natriuretic factor-luciferase gene expression. Taken together, this study provides the first molecular evidence for coupling of the alpha(1a)-AR and the alpha(1b)-AR subtypes to different signaling pathways in cardiac myocytes. 相似文献