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1.
人体单臂间歇运动对发汗调定点的影响 总被引:2,自引:0,他引:2
本工作系在微小气候相对恒定条件下,对10名健康男青年每人进行四项实验。实验 Ⅰ 为测定双侧腿足浸入43℃水中,诱发左前臂屈侧显现定量汗点时的口腔温度(舌下)阈值,作为发汗调定点参考值(ToSSP);实验 Ⅱ 为 Ⅰ 附加右臂间歇轻负荷运动(77W)时测定 ToSSP,部分对象还记录了皮肤电反应;实验 Ⅲ、Ⅳ 为 Ⅰ、Ⅱ 均附加4.5m/s 气流(22—25℃)直吹头面部,再分别测定 ToSSP。实验 Ⅰ 与 Ⅱ 同体对照22人次,Ⅲ 与 Ⅳ 同体对照24人次。结果表明,实验 Ⅱ、Ⅳ 的 ToSSP 均值及其潜伏期均值分别较 Ⅰ、Ⅲ 者降低(P<0.01)或缩短(P<0.001);Ⅰ、Ⅱ间的 ToSSP 均值差、潜伏期均值差,分别与 Ⅲ、Ⅳ 之间者无显著差异(P>0.2);Ⅱ、Ⅳ 的ToSSP 均值各与其实验开始前的口温均值亦无明显差异(P>0.5)。此结果支持运动时体温调定点下降的论点,并提示在研究体温调定点活动时,以 ToSSP 为指标较用发汗速率为优越,因 ToSSP 不为许多干扰因素所影响。 相似文献
2.
Elevated epidermal growth factor receptor binding in plutonium-induced lung tumors from dogs 总被引:1,自引:0,他引:1
F C Leung L R Bohn G E Dagle 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1991,196(4):385-389
The objective of this study is to examine and characterize epidermal growth factor receptor (EGF-R) binding in inhaled plutonium-induced canine lung-tumor tissue and to compare it with that in normal canine lung tissue. Crude membrane preparations from normal and lung-tumor tissue from beagle dogs were examined in a radioreceptor assay, using 125I-labeled epidermal growth factor (EGF) as a ligand. Specific EGF receptor binding was determined in the presence of excess unlabeled EGF. We have examined EGF receptor binding in eight lung-tumor samples obtained from six dogs. Epidermal growth factor receptor binding was significantly greater in lung-tumor samples (31.38%) compared with that in normal lung tissue (3.76%). Scatchard plot analysis from the displacement assay revealed that there was no statistical difference in the binding affinity but significantly higher concentration of EGF-R sites in the lung-tumor tissue (619 fmol/mg) than in normal lung tissue (53 fmol/mg). The increase in EGF-R number in plutonium-induced dog lung tumors does not seem to correlate with increase in the initial lung burden exposure to plutonium. Our results demonstrate that there is a significant increase in EGF-R binding in inhaled plutonium-induced dog lung tumors. 相似文献
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Administration of oestradiol to ovariectomized baboons caused the epithelium of the cervix to differentiate into tall columnar cells that were ciliated or secretory. Administration of progesterone in the presence or absence of oestradiol altered the appearance of the lining epithelium, suggesting a decrease in secretory activity. Fluorographs of media from cultures of tissue from steroid-treated animals reflected changes in polypeptide biosynthesis which correlated with the morphological observations: 6 polypeptides (Mr 88,000-37,000; pI 5.5-6.0) were observed in all treatment groups and, except for relative changes in intensity, these polypeptides were electrophoretically similar to those synthesized by the endometrium. A new group of low molecular weight polypeptides (Mr 23,000-20,000, pI greater than 8.0-5.5) and a basic protein (Mr 160,000) were synthesized and released in the oestradiol-dominated animal. These polypeptides were distinct to the cervical mucosa since they were not observed in the endometrium or oviduct. Progesterone suppressed the synthesis of the low molecular weight acidic polypeptides (Mr 23,000-20,000; pI 6.1-5.5) but maintained the synthesis of the basic polypeptides (Mr 23,000-20,000; pI greater than 8). Treatment with progesterone +/- oestradiol did not appear to induce the synthesis of any new major polypeptides in the cervical epithelium. These results suggest that oestradiol induces the synthesis of a group of cervix-specific polypeptides and progesterone antagonizes the action of oestradiol in the baboon cervix. 相似文献
6.
Hans Bohn 《Molecular and cellular biochemistry》1978,20(2):67-75
Summary A review of the present knowledge of human fibrin-stabilizing factors (FSFs) is given. Thus far three human FSFs have been isolated and characterized, namely the FSFs from plasma, platelets and placentae.Placental and platelet FSF are identical; their molecules are composed of two identical polypeptide chains (subunits A) having a molecular weight of 80.000 daltons which are held together by non-covalent bonds. The subunit structure of these FSFs can be written A2.The molecules of plasma FSF (factor XIII) also contain 2 subunits A but in addition another component (subunit S, molecular weight 180.000 daltons) which are held together by non-covalent bonds, too. The subunit structure of plasma factor XIII can be written A2S.The physical and immunochemical properties as well as the amino acid and carbohydrate composition of the FSFs, respectively of the subunits A and S are reported.The biological active part in the FSFs resides in subunit A. The biological role of subunit S is unknown. Protein S occurs in normal plasma in a free state, too; it combines with placental or platelet FSF to form a complex A2S which is indistinguishable from plasma factor XIII. It has been suggested to designate protein S as FSF-binding globulin.The human FSFs are proenzymes which have to be activated by thrombin. The activation step is a limited proteolysis resulting in the release of a peptide (36 amino acid residues) from subunit A. The enzymes formed are transglutaminases; they crosslink the fibrin molecules by the formation of -glutamyl-s-lysine bonds, a process which is designated as fibrin-stabilization.The different methods which exist for assessment of the FSFs are reported. Deficiencies in FSFs which occur can be either hereditary or acquired. The possibilities of substituting FSFs in cases of deficiency and for accelerating wound healing after major surgeries are described. 相似文献
7.
The measurement of the intrinsic alkaline Bohr effect of various human haemoglobins by isoelectric focusing 下载免费PDF全文
We have used isoelectric focusing to measure the differences between the pI values of various normal and mutant human haemoglobins when completely deoxygenated and when fully liganded with CO. It was assumed that the ΔpI(deox.–ox.) values might correspond quantitatively to the intrinsic alkaline Bohr effect, as most of the anionic cofactors of the haemoglobin molecule are `stripped' off during the electrophoretic process. In haemoglobins known to exhibit a normal Bohr coefficient (ΔlogP50/ΔpH) in solutions, the ΔpI(deox.–ox.) values are lower the higher their respective pI(ox.) values. This indicates that for any particular haemoglobin the ΔpI(deox.–ox.) value accounts for the difference in surface charges at the pH of its pI value. This was confirmed by measuring, by the direct-titration technique, the difference in pH of deoxy and fully liganded haemoglobin A0 (α2β2) solutions in conditions approximating those of the isoelectric focusing, i.e. at 5°C and very low concentration of KCl. The variation of the ΔpH(deox.–ox.) curve as a function of pH (ox.) was similar to the isoelectric-focusing curve relating the variation of ΔpI(deox.–ox.) versus pI(ox.) in various haemoglobins with Bohr factor identical with that of haemoglobin A0. In haemoglobin A0 the ΔpI(deox.–ox.) value is 0.17 pH unit, which corresponds to a difference of 1.20 positive charges between the oxy and deoxy states of the tetrameric haemoglobin. This value compares favourably with the values of the intrinsic Bohr effect estimated in back-titration experiments. The ΔpI(deox.–ox.) values of mutant or chemically modified haemoglobins carrying an abnormality at the N- or C-terminus of the α-chains are decreased by 30% compared with the ΔpI value measured in haemoglobin A0. When the C-terminus of the β-chains is altered, as in Hb Nancy (α2βTyr-145→Asp2), we observed a 70% decrease in the ΔpI value compared with that measured in haemoglobin A0. These values are in close agreement with the estimated respective roles of the two major Bohr groups, Val-1α and His-146β, at the origin of the intrinsic alkaline Bohr effect [Kilmartin, Fogg, Luzzana & Rossi-Bernardi (1973) J. Biol. Chem. 248, 7039–7043; Perutz, Kilmartin, Nishikura, Fogg, Butler & Rollema (1980) J. Mol. Biol. 138, 649–670]. In other mutant haemoglobins it is demonstrated also that the ΔpI(deox.–ox.) value may be decreased or even suppressed when the substitution affects residues involved in the stability of the tetramer. These results support the interpretation proposed by Perutz, Kilmartin, Nishikura, Fogg, Butler & Rollema [(1980), J. Mol. Biol. 138, 649–670] for the mechanism of the alkaline Bohr effect, and also indicate that the transition between the two quaternary configurations is a prerequisite for the full expression of the alkaline Bohr effect. 相似文献
8.
S S Chen J W Bohn F T Liu D H Katz 《Journal of immunology (Baltimore, Md. : 1950)》1981,127(1):166-173
9.
B Bohn 《Experimental cell research》1976,103(1):39-46
With a specially equipped flow cytofluorometer it is possible to determine quickly and accurately binding constants and the maximum number of binding sites for ligands such as peptide hormones and lectins on surfaces of intact living cells, with incubation concentrations as low as 10?11 M. Since the measurement is confined to cell-bound material the cells can be kept in their physiological environment, including free ligand molecules, even at the very moment of the assay. Thus there is no additional risk of perturbing the integrity of the membrane or of interfering with ligand-receptor interactions by washing or similar procedures. It was found that damaged cells, inevitably present in any population, are able to grossly distort binding patterns. Suggestions are given how such cells may be excluded from the measurement. 相似文献
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