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921.
Marden A. De Alvarenga Oscar Castro C. Astréa M. Giesbrecht Otto R. Gottlieb 《Phytochemistry》1977,16(11):1801-1804
Six bicyclo[3,2,1]octanoid neolignans, isolated from the benzene extract of Aniba simulans Allen (Lauraceae) trunk wood, are shown to derive from two basic structures: 1-allyl-8-hydroxy-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-7-methyl-3-oxobicyclo[3,2,1]octane, substituted by 4-hydroxy, 4-hydroxy-5-methoxy, 4-methoxy or 4,5-dimethoxy groups; and 1-allyl-8-hydroxy-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-7-methyl-4-oxobicyclo[3,2,1]oct-2-ene, substituted by 3-hydroxy or 3-hydroxy-5-methoxy groups. The structural proposals are based on spectral data, interconversions synthesis of a derivative from the known (2R,3S,3aS)-3a-allyl-5-methoxy-2-(3′-methoxy,4′,5′-methylenedioxyphenyl)-3-methyl-2,3,3a,6-tetrahydro-6-oxobenzofuran. 相似文献
922.
The relative frequencies of seed germination show positivelyskewed distributions along the time of isothermal incubation.Unimodal patterns prevailing between 19.3? and 31.4?C changeinto progressively polymodal distributions both below 19.3?and above 31.4?C. None of the distributions fit the adjustedgaussians, except at 8.0? and at 40.6?C. (Received September 29, 1977; ) 相似文献
923.
Tissue biopsies from (1) some chronic inflammatory diseases, (2) a necrotic tumoral process, (3) normal human lymphatic ganglia, and (4) two congenital diseases of the adrenal cortex were selected for study. A block from each biopsy was fixed in glutaraldehyde-paraformaldehyde; a second block was fixed in 10% formaldehyde. In all cases septate junctions between digestive vacuoles did occur in phagocytic cells and some adrenal cortex cells fixed in formaldehyde. These junctions were similar to those reported recently for malakoplakia phagocytes. Consistently, they were not found to attach organelles other than lysosomes derivatives. Both phagocytes and adrenal cortex cells in the material fixed in glutaraldehyde-paraformaldehyde did not display adhesive specializations between digestive vacuoles. This suggests that the septate junctions described herein are artifactuous structures induced by formaldehyde. There is, however, a certain degree of specificity of cells having the capability of developing these septate junctions. It is assumed that the coating material of digestive organelles in phogocytes and some other cells would be responsible for both cell specificity and organelle specificity of the formaldehyde-induced septate junctions. 相似文献
924.
I Martín de Miranda J C Macome L E Costa A C Taquini 《Acta physiologica latino americana》1977,27(2):65-71
The role of the gonads and their hormones on body weight was studied in rats of both sexes submitted to chronic hypoxia and their controls at sea level atmospheric pressure. Intact rats were exposed to either 4 700 or 6 000 m simulated altitude in a hypopressure chamber. Castrated rats and castrated rats daily injected with either 0.5 mg of testosterone or 20 microgram of estradiol or the vehicle, were exposed to the higher altitude. The rat weight was recorded for a period of at least eight weeks. All groups of hypoxic male animals increased their weight significantly less than the controls at sea level. Also in castrated females and in castrated injected with testosterone or the vehicle the same pattern of weight curves was observed. On the contrary, groups of intact females and castrated females injected with estradiol did not show significant differences between hypoxic and control animals. Only in a group of smaller intact females (50-80 g) the body weight increase was significantly diminished by exposure to either 4 700 or 6 000 m simulated altitude. 相似文献
925.
Résumé Les remainements intestinaux affectant la paroi intestinale sont quantifiés chez les larves d'un Amphibien Anoure,Alytes obstetricans, traitées par la thyroxine. La fraction correspondant à chaque zone composant la paroi est déterminée sur coupe. La répartition et la fréquence des noyaux marqués sont recherchées chez des larves ayant reçu de la thymidine tritiée.L'indice de marquage nucléaire de l'épithélium primaire tend vers zéro durant les 3 premiers jours du traitement. Ces résultats reflètent un ralentissement de la croissance du tissue, précédant sa dégénérescence et son élimination complète au 14ème jour d'immersion dans la solution hormonale.Dès de 3ème jour de traitement, un épithélium secondaire se développe à partir de cellules-souches basales. Son indice de marquqge croît, culmine au 9ème jour avec une valeur proche de 50%, puis s'abaisse. La prolifération cellulaire est plus modérée dans la zone extra-épithéliale, qui s'épaissit toutefois au cours de cette métamorphose provoquée.
Quantitative analysis of intestinal changes and the evolution of DNA synthesis in thyroxine-treated larvae ofAlytes obstetricans. (Amphibia, Anura)
Summary Changes in the intestinal wall ofAlytes obstetricans (Amphibia, Anura) were quantified during thyroxine treatment. The relative proportion of each intestinal wall component was determined in tissue sections. Autoradiographic studies on intestine with3H-thymidine revealed the distribution and frequency of labeled nuclei.The labeling index in the primary epithelium falls to zero by 3 days. Thyroxine treatment induces a decrease in the growth rate of this tissue, just before its degeneration and complete elimination by 14 days.Three days after T4-treatment, a secondary epithelium develops from basal stem cells. Its labeling index rises to a maximum of about 50% by 9 days, and thereafter declines. Cell proliferation is less marked in the extraepithelial zone, which nevertheless thickens during this thyroxine-induced metamorphosis.相似文献
926.
Jan Jeník 《Folia Geobotanica》1977,12(2):208-208
927.
At routine post-mortem of a moose an inclusion-body-like configuration of the nuclei of the cells in the granule layer of the cerebellum was found. This was also observed to a lesser extent in glial cells of the cerebrum, epithelial cells of the collecting tubules of kidney and in the hepatocytes. 相似文献
928.
Bubeník J. Perlmann P. Indrová M. Šimová J. Jandlová T. Neuwirt J. 《Cancer immunology, immunotherapy : CII》1983,14(3):205-206
Summary Supernatants from Con A-stimulated rat spleen cell cultures containing T cell growth factor inhibited growth of a transplantable 3-methylcholanthrene-induced sarcoma in syngeneic mice. The tumour-inhibitory effects were dependent on the concentration of T cell growth factor and repeated injections of the supernatants. 相似文献
929.
Cyclopiazonic acid is a toxic metabolite of fungal origin that inhibits protein synthesis in intact HeLa cells and eukaryotic cell-free systems. It has been shown that cyclopiazonic acid blocks the GTP- and EF-1-dependent binding of (3H)Phe-tRNA to 80S ribosomes. Moreover the translocation of N-Ac-(3H)Phe-tRNA by 80S ribosomes that takes place in the presence of EF-2 and GTP is also halted by cyclopiazonic acid. It is concluded that this drug affects a ribosomal site involved in the alternative interaction of elongation factors EF-1 and EF-2. 相似文献
930.
In female rats aged 21 and 80 days, uninephroadrenalectomy with enucleation of the remaining adrenal was performed and 0.17 mol X l-1 saline offered as the only drinking fluid. The changes of plasma concentration of renin (PRC), and its substrate (RSC) and renal renin activity (RRA), considered as an indicator of the secretory activity of the regenerating adrenal were studied 5, 10, 20, 40 and 60 days after the adrenal enucleation to look for possible age differences related to the higher susceptibility of immature rats to the hypertensive influence of the regenerating adrenal. It has been found that: 1. In adrenal-enucleated rats the saline-induced decrease of RRA was delayed for a shorter time period in immature rats than in adult ones (5 vs. 10 days), during which blood pressure, saline consumption and RSC were lowered. The decrease of PRC was retarded in the older group only. 2. In rats with regenerating adrenals the PRC and RRA decrease was greater in animals subjected to enucleation of the remaining adrenal gland when immature, than in those operated when adult. At the end of the experiment this age difference disappeared. 3. The age difference in PRC and RRA suppression appeared during the period, when neither blood pressure nor saline consumption were higher in immature rats than in adult ones. 4. In rats with regenerating adrenals the renal mass was greater than in saline drinking controls. In the younger group, which in contrast to the adult one developed hypertension, this increase was greater and directly related to the blood pressure level from the 20th post-enucleation day onwards. It is being suggested that the changes of PRC, RRA and RSC observed up to the 10th post-enucleation day indicates relative adrenal insufficiency, the shorter duration of which in immature rats reflects their higher sensitivity to mineralocorticoids produced by the regenerating adrenal. This also manifests itself by greater PRC and RRA suppression in this age group. The haemodynamic results of the greater RRA suppression in the not yet fully developed kidneys of immature rats may facilitate the development of a "vicious circle" mechanism between blood pressure and hypertensive renal damage and thus contribute to the higher sensitivity to adrenal-regeneration hypertension. 相似文献