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991.
We have studied the structure of nuclease-solubilized chromatin from Ehrlich ascites cells by flow linear dichroism (LD) using the anisotropic absorption of the DNA bases and of two intercalated dyes, ethidium bromide and methylene blue. It is confirmed that intercalation occurs preferentially in the linker part of the chromatin fiber, at binding ratios (dye/base) below 0.020. Using this information, we determined the orientation of the linker in relation to the average DNA organization in chromatin. The LD measurements indicate that the conformation of chromatin is considerably changed in the ionic strength interval 0.1-10 mM NaCl: with increasing salt concentration, the LD of the intrinsic DNA base absorption changes signs, from negative to positive, at approximately 2.5 mM NaCl. The LD of the intercalated dyes also changes signs, however, at a somewhat higher salt concentration. The results are analyzed in terms of possible allowed combinations of tilt angles of nucleosomes and pitch or tilt angles of linker DNA sections relative to the fiber axis, at different salt concentrations in the interval 0.1-10 mM NaCl. Two models for the salt-induced structural change of chromatin are discussed. 相似文献
992.
[6-3H]glucose was used for measurements of plasma glucose turnover in adult non-growing mice with sarcoma-induced malnutrition. Plasma glucose turnover was increased in freely-fed tumour-bearing mice but not in starved tumour-bearing mice. Elevated glucose turnover in freely-eating sarcoma-bearing mice was associated with an increased glucose pool, the latter not only being due to an expanded distribution volume of glucose. Plasma lactate was elevated in sarcoma-bearing mice independently of their food intake. The results show that elevated plasma glucose turnover in an anorectic tumour-bearing host is not due to insufficient adaptation to food depression. Increased glucose turnover in tumour-bearing mice was associated with an altered intermediary whole body metabolism of glucose which is not entirely accounted for by the state of malnutrition of the host. 相似文献
993.
Haptoglobin (Hp) groups were determined in 65 patients with dementia of Alzheimer type (DAT) and 74 with multi-infarct dementia (MID). The increased Hp1 gene frequency among patients with DAT described by other investigators could not be confirmed in this study. The patients showed no significant difference from the controls with respect to phenotype and gene frequencies, and there were no significant differences between early and late onset cases of DAT. 相似文献
994.
Haptoglobin groups and rheumatoid arthritis 总被引:2,自引:0,他引:2
Haptoglobin types were determined in 200 patients with rheumatoid arthritis (RA) subdivided according to sex and familial occurrence of polyarthritis. A highly significant excess of the Hp2 gene was found among patients with a family history of polyarthritis, more pronounced among males. The possible association between Hp2 and predisposition for increased immune reactivity is discussed. 相似文献
995.
Sutural morphogenesis was studied in calvariae of fetal and newborn 16- to 26-day postconception C57B1/6J mice. The squamoid pattern characteristic of most calvarial sutures appeared to be established during the phase of approach of the adjacent bone territories as they assumed different ecto/ifendocranial planes within the desmocranium. When this stratification failed, apoptosis, a form of cell death, was seen to occur upon physical contact of the leading osteogenic cells of each heterotopic bone territory. Apoptosis appeared as part of a secondary morphogenetic mechanism preventing physical contact and resultant fusion of adjacent mineralized zones, as well as enhancing appearance of the usual pattern of overlap of calvarial sutures. 相似文献
996.
The chemical composition of chromatin from the livers of 12-, 15- and 19-day-old embryos, of 1-day-old chicks and of adult chickens was analysed. The process of embryonic development is accompanied by an increase in non-histone chromatin proteins and chromatin RNA, as well as in the phosphorus content of chromatin phosphoproteins. The amount of these components decreases in the livers of 1-day-old chicks and adults. Two-dimensional polyacrylamide gel electrophoresis of acid-soluble chromatin proteins showed an increase in the amount of the H1 histone in 19-day-old embryos and adult chickens. Non-histone proteins of embryo liver chromatin showed a high content of the fraction of Mr of about 40 000; this was not the case for adult chickens. The non-histone protein fraction of Mr of about 120 000, characteristic of adult chicken liver proteins, was not found in the livers of 12- and 15-day-old embryos. Non-histone chromatin proteins isolated from the livers of animals of different age exhibited also quantitative differences. 相似文献
997.
Specific antibodies against the histone H2A from calf thymus were generated by injecting rabbits with complexes: histone H2A-RNA with a protein to RNA ratio of 3:1. In the microcomplement fixation assay the antibodies against the histone H2A from calf thymus immuno-reacted with the histone H2A from calf thymus but not with H2A from Physarum polycephalum. The histone H2A from calf thymus therefore appears to have an immunological determinant(s) which does not exist in H2A from Physarum polycephalum. 相似文献
998.
A prospective controlled investigation in 134 consecutive outpatients compared the cytologic adequacy of sputum samples obtained by spontaneous and provoked expectoration. Inhalation of nebulized 10% sodium chloride was used for provoked expectoration. A significantly higher number of adequate samples was produced after provocation, as judged by the presence of alveolar macrophages (X2 = 5.63; p less than 0.02). The improvement in sample adequacy was limited to the nonsmokers and ex-smokers in the study. This result, together with the relatively high cost of cytologic sputum examinations, indicates that provoked expectoration should at least be applied to the collection of sputum samples from nonsmokers and ex-smokers. 相似文献
999.
Degeneration of the knee joint and increase of anterior-posterior tibial displacement are resulting from total meniscectomy, especially in knees with anterior cruciate deficiency. Vascularisation of the meniscus was studied in 12 cadaver knees after latex injection of vessels. Vascularisation of the anterior and posterior horns was found to be much better than that of the body of meniscus. All vessels originated from the popliteal artery, but variably in importance, and formed the perimeniscal and subsynovial network. 11 peripheral meniscus tears (8 freshly injured, 3 ruptures older than 2 months) were repaired by refixation, followed by immobilisation for 6 weeks. Arthroscopy 3 months postoperatively showed complete healing of all tears. Clinical examinations--follow-up for 14 months--showed no signs of rerupture in any of the patients. 相似文献
1000.
Differential Adhesion and Infection of Nematodes by the Endoparasitic Fungus Meria coniospora (Deuteromycetes)
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The conidia of the endoparasitic fungus Meria coniospora (Deuteromycetes) had different patterns of adhesion to the cuticles of the several nematode species tested; adhesion in some species was only to the head and tail regions, on others over the entire cuticle, whereas on others there was a complete lack of adhesion. After adhesion, the fungus usually infected the nematode. However, adhesion to third-stage larvae of five animal parasitic nematodes, all of which carry the cast cuticle from the previous molt, did not result in infection. M. coniospora infected animal parasitic nematodes when this protective sheath was removed. Seven preparations of sialic acid (N-acetylneuraminic acid) gave three types of response in adhesion-infection of nematodes: (i) a significant reduction in conidial adhesions; (ii) no interference with adhesion, but a 10-day delay in infection; and (iii) a delay in infection by 2 to 3 days. The current results support previous findings indicating involvement of sialic acids localized on nematode cuticles in recognition of prey by M. coniospora. 相似文献