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141.
M J Jarvis M A Russell C Feyerabend J R Eiser M Morgan P Gammage E M Gray 《BMJ (Clinical research ed.)》1985,291(6500):927-929
Saliva cotinine concentrations in 569 non-smoking schoolchildren were strongly related to the smoking habits of their parents. When neither parent smoked the mean concentration was 0.44 ng/ml, rising to 3.38 ng/ml when both parents were cigarette smokers. Mothers'' smoking had a stronger influence than did fathers'' (p less than 0.01). In addition, there was a small independent effect of number of siblings who smoked (p less than 0.01). The dose of nicotine received from fathers'' smoking was estimated as equivalent to the active smoking of 30 cigarettes a year, that from mothers'' smoking as equivalent to smoking 50 cigarettes a year, and that from both parents smoking as equivalent to smoking 80 cigarettes a year. This unsolicited burden may be prolonged throughout childhood and poses a definite risk to health. 相似文献
142.
143.
144.
Murine peritoneal macrophages (M phi), activated in vivo or in vitro, remarkably inhibited the uptake of thymidine by a lens epithelial cell line, while resident M phi, or M phi induced by thioglycollate, exhibited much lower or no cytostatic capacity. The target cells were partially protected from the cytostatic activity by the anti-inflammatory agents indomethacin, aspirin, and dexamethasone, but not by lipoxygenase inhibitors. The protective activity of indomethacin and aspirin, but not of dexamethasone, was completely counteracted by prostaglandin E2 (PGE2). Yet, PGE2 alone has no effect on the uptake of [3H]thymidine by lens epithelial cells. PGE1 resembled PGE2 in its effect on this system, whereas PGA2, PGB2, or PGF2 alpha had no detectable activity. The counteracting effect of PGE2 was mimicked by dibutyryl cAMP or by cholera toxin, an agent which increases cAMP levels. These findings suggest that PGEs are not direct cytostatic agents, but rather, are essential mediators for the development of the cytostasis. Activated M phi did not lyse cells of the original lens epithelial cell line, but caused substantial cytolysis of cells of a subline derived from it. In contrast to its aforementioned effect on the cytostasis, PGE2 inhibited the cytolytic activity of M phi. Thus, this study provides a first demonstration in a single system of the opposite effects of PGEs on M phi activity on target cells, i.e., mediating the cytostasis and inhibiting the cytolysis. 相似文献
145.
The effects of various salts of the Hofmeister and aliphatic acid salt series and hydrophobic reagents of the urea series on the subunit structure and the dissociation of Helix pomatia alpha-hemocyanin were investigated by employing light-scattering molecular weight methods. In moderate ranges of salt concentrations [0-1.0 M NaClO4, NaSCN, NaI, and guanidinium chloride (GdmCl) and 0-2.0 M NaBr], the dissociation reaction is essentially a two-step process characterized by the dissociation of whole hemocyanin molecules dissociating to half-molecules of decamers followed by the dissociation of the half-molecules to five dimeric fragments. The effectiveness of the salts and relative ineffectiveness of the ureas and GdmCl as dissociating agents in the first step of the dissociation reaction suggest that the stabilization of the contact areas between half-molecules in solution is largely a nonhydrophobic energy process involving polar and ionic interactions. Hydrophobic forces appear to be important, however, for stabilization of the half-molecules through side to side contacts of the five dimeric units that make up each half-molecule. The analysis of our dissociation data by use of equations derived in our previous studies [Herskovits, T. T., & Harrington, J.P. (1975) Biochemistry 14, 4964-4971] gave apparent estimates of amino acid groups of about 60-150 for each of the contact areas between the cylindrically shaped half-molecules and 30-60 for each of the dimers in the half-molecules themselves.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
146.
Evidence for specific binding of uncapacitated boar spermatozoa to porcine zonae pellucidae in vitro
Washed ejaculated boar sperm and sperm from the cauda epididymis bind to the zona pellucida of fixed porcine eggs in large numbers. Sperm incubated in the presence of dextran sulfate (8 K daltons or 500 K daltons) or fucoidan and then washed no longer bind to eggs. Other acid carbohydrates (heparin, chondroitin sulfates, inositol hexasulfate, carboxymethylcellulose) fail to block sperm-egg binding even when added directly to sperm-egg suspensions. Seminal plasma and the seminal vesicle secretion contain basic proteins which bind tightly to sperm and bind reversibly to eggs preventing sperm from binding to eggs. When dextran sulfate or fucoidan are mixed with the vesicular secretion, from which seminal plasma basic proteins originate (Hunt et al., '83), the secretion loses the capacity to prevent sperm from binding to eggs; this suggests that seminal vesicle proteins can bind to the same site on zonae as do sperm and thus seminal plasma may modify sperm-egg interactions. Corpus and cauda epididymal sperm also bind in large numbers to the zona pellucida of isolated eggs but high concentrations of caput sperm, which exhibit high motility in the presence of caffeine, bind only in few numbers. Thus a component that enhances sperm-zona binding is apparently formed on the plasma membranes of uncapacitated sperm during passage through the epididymis. This finding, and an earlier observation that antibodies raised against uncapacitated sperm plasma membranes block sperm-egg binding in vivo (Peterson et al., '83) suggest that this component may be involved in sperm zona interaction in vivo. 相似文献
147.
Sequence of Guinea Pig Myelin Basic Protein 总被引:5,自引:5,他引:0
Gladys E. Deibler Russell E. Martenson Henry C. Krutzsch† Marian W. Kies 《Journal of neurochemistry》1984,43(1):100-105
This paper proposes a tentative amino acid sequence of guinea pig myelin basic protein obtained by comparison of peptide fragments of the guinea pig and bovine proteins. Analyses of the tryptic peptides confirmed the known sequence differences in the NH2-terminal half of the molecule and showed that in the COOH-terminal half of the guinea pig protein Ser131 was missing, Ala136 - His137 was deleted, Leu140 was replaced by Phe, and an extra Ala was inserted somewhere within sequence 142-151 (tryptic peptide T23 ). Sequence determination of guinea pig tryptic peptides corresponding to residues 130-134 ( T20 ), 135-138 ( T21 ), and 142-151 ( T23 ) of the bovine protein confirmed the above sequence changes and placed the extra Ala between Gly142 and His143 . The sequence of the region corresponding to bovine residues 130-143 is thus Ala-Asp-Tyr-Lys-Ser-Lys-Gly-Phe-Lys-Gly-Ala-His. No species differences were observed in the amino acid compositions of the remaining tryptic peptides obtained from the COOH-terminal half of the molecule. Based upon these results, the guinea pig basic protein contains 167 amino acid residues and has a molecular weight of 18,256. 相似文献
148.
G S Haas E Halperin D Doseretz R Linggood P S Russell R Colvin L Barrett A B Cosimi 《Journal of immunology (Baltimore, Md. : 1950)》1984,132(2):1026-1030
To better understand the immunologic effects of lymphoid irradiation (LI), blood levels of T cell subsets were sequentially monitored in 15 patients before, during, and after irradiation treatment for Hodgkin's disease. Blood levels of all lymphocytes, T cells, and T cell subsets (defined by OKT4 and OKT8) fell dramatically and in similar proportions during early therapy, reaching levels less than 20 to 25% of control by the completion of mantle irradiation, and continuing at very depressed levels through the completion of therapy. Blood levels of OKT8-reactive (OKT8+) cells returned to pretreatment levels (402 +/- 38/mm3 vs 360 +/- 32/mm3 pretreatment) between 6 to 8 mo after LI, whereas blood levels of OKT4-reactive (OKT4+) cells returned to only 42% of previous values (242 +/- 22/mm3 vs 584 +/- 34/mm3 pretreatment) over the same period. The pre-LI ratio of OKT4+ to OKT8+ cells was 1.85 +/- 0.24 and fell to 0.65 +/- 0.05 between 6 to 8 mo after LI. During the recovery period, discrepancies of 208 +/- 32 cells/mm3 (3 to 5 months post LI) and 198 +/- 32 cells/mm3 (6 to 8 mo post LI) developed between the blood levels of OKT3+ cells and the sum of OKT4+ and OKT8+ cells. This suggests the emergence of OKT4+/OKT3-, OKT8+/OKT3-, and/or OKT4+/OKT8+ cells. In five patients, the sum of OKT4+ and OKT8+ cells was compared with the number of cells simultaneously co-stained by OKT4 and OKT8. It appeared that a significant proportion of the cells were OKT4+/OKT3- and OKT8+/OKT3- lymphocytes. We concluded that LI is similarly cytotoxic to peripheral blood T cell subpopulations. The reversed ratio after LI is a result of a slower repopulation of the peripheral blood by OKT4+ cells relative to OKT8+ cells. T cells after LI show a high degree of antigenic immaturity. It is postulated that the bone marrow that lies outside the fields of treatment and contains predominantly immature OKT8+/OKT3- cells is a major source of T cells repopulating the peripheral blood after LI. 相似文献
149.
Organization of the ribosomal ribonucleic acid genes in various wild-type strains and wild-collected strains of Neurospora 总被引:6,自引:0,他引:6
Peter J. Russell Sheryl Wagner Karin D. Rodland Rhonda L. Feinbaum Jennifer P. Russell Marion S. Bret-Harte Stephen J. Free Robert L. Metzenberg 《Molecular & general genetics : MGG》1984,196(2):275-282
Summary The organization of the ribosomal DNA (rDNA) repcat unit in the standard wild-type strain of Neurospora crassa, 74-OR23-1A, and in 30 other wild-type strains and wild-collected strains of N. crassa, N. tetrasperma, N. sitophila, N. intermedia, and N. discreta isolated from nature, was investigated by restriction enzyme digestion of genomic DNA, and probing of the Southern-blotted DNA fragments with specific cloned pieces of the rDNA unit from 74-OR23-1A. The size of the rDNA unit in 74-OR23-1A was shown to be 9.20 kilobase pairs (kb) from blotting data, and the average for all strains was 9.11+0.21 kb; standard error=0.038; coefficient of variation (C.V.)=2.34%. These data indicate that the rDNA repeat unit size has been highly conserved among the Neurospora strains investigated. However, while all strains have a conserved HindIII site near the 5 end of the 25 S rDNA coding sequence, a polymorphism in the number and/or position of HindIII sites in the nontranscribed spacer region was found between strains. The 74-OR23-1A strain has two HindIII sites in the spacer, while others have from 0 to at least 3. This restriction site polymorphism is strain-specific and not species-specific. It was confirmed for some strains by restriction analysis of clones containing most of the rDNA repeat unit. The current restriction map of the 74-OR23-1A rDNA repeat unit is presented. 相似文献
150.
The sperm head of the plains mouse, Pseudomys australis, has three curved hooks projecting from its anterior margin. The two ventral hooks have previously been shown to consist largely of an extension of the subacrosomal material. To characterize further the structure and composition of the ventral hooks, we have examined their formation during spermiogenesis using transmission electron microscopy, silver staining, and actin localization with NBD-phallacidin. The ventral hooks develop as an extension of the perinuclear space and postacrosomal dense lamina on the anteroventral margin of the sperm head. Bundles of 6-nm-thick filaments appear in the core of each hook; these are probably actin filaments based on staining of the hooks with NBD-phallacidin. Just prior to spermiation, electron-dense material condenses in the core of the ventral hooks and concurrently in the perinuclear space in the remainder of the sperm head. The two ventral hooks thus appear to consist of a core of perinuclear material and actin filaments, which is enclosed by a continuation of the postacrosomal dense lamina. 相似文献