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1.
Regulation of G(1) cell-cycle progression by oncogenes and tumor suppressor genes. 总被引:13,自引:0,他引:13
Progression of resting quiescent G(0) cells into early G(1) and transition across the restriction point are highly regulated processes. Mutation of proto-oncogenes and tumor suppressor genes regulating these transitions are targeted during oncogenesis. Recent work has underscored the importance of the G(0) to early G(1) transition and metabolism to neoplastic cells. 相似文献
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Jerome S. Kaye Rachel McMaster-Kaye 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,696(1):44-51
Typical somatic cell type histones are lost from the nucleus during late spermiogenesis in the house cricket; they are replaced by unusual basic proteins specific to the spermatid. We wish to characterize these proteins because they appear to determine the unusual chromatin structures of the spermatid. Molecular weights of the unusual basic proteins were estimated by chromatographing them on Bio-Gel A 0.5 M agarose columns eluted with 6 M guanidine hydrochloride. Two proteins named TH1 and TH2 have molecular weights in the range spanned by the somatic histones. The molecular weight of TH1 is 17 500 and that of TH2 is 15 500. Three additional spermatid proteins were also analyzed by molecular weight determination. They are called here protamines A, B and C, and they have molecular weights in the range typical of protamines. That of A is 6200, of B is 5500 and of C is 3800. They span the range from the large protamines typical of mammalian sperm to the small protamines of salmonid fish. The molecular weights of the TH proteins were also examined by electrophoresis on SDS-polyacrylamide gels. Amino acid compositions determined for TH1 and TH2 show that both are basic proteins rich in arginine relative to lysine. Their compositions are histone-like, but they appear to be distinct histone types rather than variant forms of the somatic histones. 相似文献
4.
Dr. Timothy J. Barrett James H. Green Patricia M. Griffin Andrew T. Pavia Stephen M. Ostroff I. Kaye Wachsmuth 《Current microbiology》1991,23(4):189-195
Shiga-like toxin-producingEscherichia coli O157:H7 are important causes of bloody diarrhea and hemolytic uremic syndrome. To facilitate the epidemiologic study of these organisms, we developed enzyme-linked immunosorbent assays (ELISAs) for antibodies to Shiga-like toxin I (SLT I), Shiga-like toxin II (SLT II), andE. coli O157 lipopolysaccharide (LPS). We tested serum samples from 83 patients in two outbreaks ofE. coli O157:H7 diarrhea and from 66 well persons. Forty-three patients (52%) had at least one serum sample positive for anti-O157 LPS antibodies; among 26 culture-confirmed patients, 24 (92%) had at least one positive serum sample. Two (3%) of 66 control sera had positive anti-O157 LPS titers. ELISA results for SLT I and II were compared with those of HeLa cell cytotoxicity neutralization assays on both patient and control sera. Neutralization assays detected anti-SLT I antibodies in at least one serum sample from each of 17 (20%) patients and 7 (10.6%) controls, while 16 (19%) patients and 7 controls had positive titers by anti-SLT I ELISA. Although all serum samples, including control sera, showed nonspecific neutralization of SLT II, no antibody titers to SLT II were detected by either neutralization or ELISA. These results indicate that ELISAs for SLT I and SLT II antibodies are comparable to HeLa cell cytotoxicity neutralization assays. Both the ELISAs and neutralization assays are insensitive in detecting infected patients. However, the ELISA for antibodies toE. coli O157 LPS is both sensitive and specific, and may be more useful than assays for antitoxic antibodies in detecting persons withE. coli O157:H7 infection. 相似文献
5.
Genetic basis for altered pathogenesis of an immune-selected antigenic variant of reovirus type 3 (Dearing). 总被引:10,自引:8,他引:2 下载免费PDF全文
In this paper we provide a step by step comparison of the pathogenesis of murine infection caused by reovirus type 3 (Dearing) and an antigenic variant (K) selected by its resistance to neutralization with a monoclonal antibody (G5) directed against the T3 hemagglutinin. To show that specific changes in the biologic properties of variant K were due to mutation in the S1 double-stranded RNA segment (gene), which encodes the viral hemagglutinin, we generated a reassortant virus ("1 HA K") containing the variant K S1 gene and compared its properties to variant K and to a reassortant ("1 HA 3") containing the T3 (Dearing) S1 gene. These studies, in conjunction with our previous nucleotide sequence analysis of the S1 genes of variant K and T3 (Dearing) [R. Bassel-Duby, A. Jayasuriya, D. Chatterjee, N. Sonenberg, J. V. Maizel, Jr., and B. N. Fields, Nature (London) 315:421-423, 1985; R. Bassel-Duby, D. R. Spriggs, K. L. Tyler, and B. N. Fields, submitted for publication], indicate that a single amino acid change in the T3 hemagglutinin can alter viral growth and tropism within the central nervous system without affecting either its primary replication in the intestine or its pattern of spread to or within the central nervous system. 相似文献
6.
Stimulation of creatine kinase BB activity by parathyroid hormone and by prostaglandin E2 in cultured bone cells. 总被引:2,自引:0,他引:2 下载免费PDF全文
Bone cells in culture responded to parathyroid hormone (PTH) and prostaglandin E2 (PGE2) by a 2-fold increase in creatine kinase (CK) activity. Combined treatment resulted in a higher response than with PTH alone. Calcitonin (CT) failed to stimulate CK activity, did not affect the response of CK to PTH, but inhibited slightly the increase in CK activity by PGE2. Bone-cell cultures grown in low [Ca2+] (0.125 mM), enriched in PTH-responsive osteoblast-like cells, responded to PTH, but not to PGE2 or CT, by increased CK activity. In both normal and low-[Ca2+] cultures, 8-bromo cyclic AMP did not affect CK activity, nor did it change the response of the cells to PTH, PGE2 or CT. The increase in CK activity was time- and dose-dependent and inhibited both by cycloheximide and by actinomycin D. The isoenzyme of CK stimulated was the CKBB form, the isoenzyme induced by other hormones. This appears to be the first report of the stimulation of CK activity by a polypeptide hormone or a prostaglandin. We suggest that stimulation of CKBB can serve as a marker for the action of a variety of hormones and growth promoters. 相似文献
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In Vitro Antimicrobial Activity and Human Pharmacology of Cephalexin, a New Orally Absorbed Cephalosporin C Antibiotic 总被引:3,自引:1,他引:2 下载免费PDF全文
Thomas S. Thornhill Matthew E. Levison Warren D. Johnson Donald Kaye 《Applied microbiology》1969,17(3):457-461
Concentrations of cephalexin (an orally absorbed derivative of cephalosporin C) in serum and urine were determined in normal volunteers and patients. The in vitro antibacterial activity was also studied. All strains of group A β-hemolytic streptococci and Diplococcus pneumoniae were inhibited by 3.1 μg/ml. Of the Staphylococcus aureus strains, 88% were inhibited by 6.3 μg/ml, and 12.5 μg/ml was inhibitory for all S. aureus, 80% of Escherichia coli, 72% of Klebsiella-Aerobacter, and 56% of Proteus mirabilis strains. About 90 to 96% of E. coli, Klebsiella Aerobacter, and P. mirabilis strains were inhibited by 25 μg of cephalexin per ml. Pseudomonas and indole-positive Proteus strains proved to be quite resistant to cephalexin. Cephalexin was well absorbed after oral administration. A peak serum concentration of cephalexin of at least 5 μg/ml was achieved in each volunteer with 250 and 500-mg doses. A mean peak serum concentration of 7.7 μg/ml was achieved with 250-mg doses; 12.3μg/ml was achieved with 500-mg doses of antibiotic. Food did not interfere with absorption. Probenecid enhanced both the peak serum concentration and the duration of antibiotic activity in the serum. Over 90% of the administered dose was excreted in the urine within 6 hr. The mean peak serum concentration of cephalexin after an oral dose of 500 mg was adequate to inhibit all group A streptococci, D. pneumoniae, and S. aureus, 85% of E. coli, and about 40 to 75% of Klebsiella-Aerobacter and P. mirabilis strains. Levels of cephalexin in urine were adequate to inhibit over 90% of E. coli, and P. mirabilis and 80 to 96% of Klebsiella-Aerobacter strains. 相似文献
10.
The Role of Calcium Ions in the Acceleration of Resting Muscle Glycolysis by Extracellular Potassium 下载免费PDF全文
The activation of the glycolysis of resting muscle by increased extracellular potassium is dependent upon the simultaneous presence of calcium, but not of sodium ions. This regulation of metabolism by a membrane characteristic seems to act upon an early link in the glycolytic enzyme chain. 相似文献