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71.
The identification and regionalization of four pituitary parenchymal cell types, gonadotrophs, mammotrophs, somatotrophs and thyrotrophs, were studied in the baboon (Papio cynocephalus) hypophysis using immunocytochemistry. The gonadotrophs were homogeneously distributed throughout the entire pars distalis. Both mammotrophs and somatotrophs predominate at the superior and inferior poles of the organ. The medial and anteromedial regions are populated by mammotrophs and thyrotrophs, while the lateral and posterior portions of the pars distalis contain large numbers of somatotrophs. 相似文献
72.
Summary The properties of agglutination by plant lectins, along with chromosome patterns, were examined in a variety of mammalian
cell types. Untransformed adult and embryonic cells in culture, direct mouse spleen cell preparations, SV40-transformed 3T3
cells, and trypsinized 3T3 cells were all highly agglutinable with concanavalin A and with wheat germ agglutinin. In contrast,
untreated cells of the contact-inhibited 3T3 line were alone among the cells tested in their low agglutinability. Chromosome
analysis of the cultured cells showed that karyotypic variation from the diploid to an aneuploid state in mouse and rat embryo
cultures was not accompanied by a change in agglutinability. Adult rat lung, adult monkey kidney, and embryonic human lung
cells, which were all highly agglutinable, showed the normal diploid pattern. Thus, agglutination of cells by plant lectins
appears to be a cellular property often associated with non-neo-plastic cells.
This investigation was supported by Grants CA-12503 and ES-00260 from the National Institutes of Health, United States Public
Health Service. 相似文献
73.
STRUCTURAL DIFFERENTIATION OF STACKED AND UNSTACKED CHLOROPLAST MEMBRANES : Freeze-Etch Electron Microscopy of Wild-Type and Mutant Strains of Chlamydomonas 总被引:15,自引:10,他引:5 下载免费PDF全文
Wild-type chloroplast membranes from Chlamydomonas reinhardi exhibit four faces in freeze-etchreplicas: the complementary Bs and Cs faces are found where the membranes are stacked together; the complementary Bu and Cu faces are found in unstacked membranes. The Bs face carries a dense population of regularly spaced particles containing the large, 160 ± 10 A particles that appear to be unique to chloroplast membranes. Under certain growth conditions, membrane stacking does not occur in the ac-5 strain. When isolated, these membranes remain unstacked, exhibit only Bu and Cu faces, and retain the ability to carry out normal photosynthesis. Membrane stacking is also absent in the ac-31 strain, and, when isolated in a low-salt medium, these membranes remain unstacked and exhibit only Bu and Cu faces. When isolated in a high-salt medium, however, they stack normally, and Bs and Cs faces are produced by this in vitro stacking process. We conclude that certain particle distributions in the chloroplast membrane are created as a consequence of the stacking process, and that the ability of membranes to stack can be modified both by gene mutation and by the ionic environment in which the membranes are found. 相似文献
74.
Andrew G. Smith John D. Gilbert W. Arthur Harland Charles J. W. Brooks 《The Biochemical journal》1974,139(3):793-795
Cholest-5-ene-3beta,26-diol, isolated from human brain, was further characterized by oxidation to 3-oxocholest-4-en-26-ol and to 3-oxocholest-4-en-26-oic acid. Identification was achieved by comparison (by t.l.c., g.l.c. and g.l.c.-mass spectrometry) with corresponding reference compounds derived from kryptogenin. 相似文献
75.
Andrew Gemant 《Molecular biology reports》1974,1(7):423-427
Polyphenol oxidase (PPO) oxidizes, due to their tyrosine content, the proteins histone, casein and human serum albumin. These oxidations are inhibited by ascorbate which lowers the redox potential of the medium. Serum albumin in its native state is only moderately oxidized. If, however, prior to oxidation, the albumin is subjected to denaturation, involving unfolding of the chain, the attack by the enzyme is markedly increased. Such denaturation was effected by either the action of dodecyl sulfate or heating to 60°C. The implications of these findings to the problem of senescence are discussed. 相似文献
76.
77.
78.
Andrew M. Torres 《American journal of botany》1968,55(5):582-589
The karyotypes of the three diploid (n = 10) species of the subg. Diplothrix (Zinnia—Compositae) were compared to determine whether there were any demonstrable differences which could then be sought in their polyploid derivatives. Because many of the chromosomes in a set were too similar to distinguish confidently between them, a method of analysis was developed which measures the similarity of whole sets of chromosomes rather than individual ones. The method consists of measuring the distances between graph-plotted vertices representing arm lengths of chromosomes of real or paper hybrids and then comparing these distances by means of U tests with those similarly derived for the “parents.” This procedure obviates the need of attempting to identify morphologues (morphologically similar chromosomes) in a somatic diploid root-tip cell and to equate corresponding pairs of chromosomes from different cells of a single plant or from different species or hybrids. No demonstrable differences in the karyotypes of diploid cespitose zinnias were found. Analysis of previously published data by this method indicated that there has been a general non-objectivity and non-operationalism in the determination of homologous chromosomes, and a general but unwarranted assumption that morphologues are in reality genologues (genetically corresponding chromosomes). 相似文献
79.
Andrew More Desmond 《The Western journal of medicine》1962,96(5):315-320
In a series of 240 cases of perforated peptic ulcer prior to 1952 there was a total mortality of 17 per cent. This included cases treated conservatively as a planned procedure or because of other morbid conditions and undiagnosed cases, all ending in death.In cases treated by simple suture, mortality was 2.6 per cent for patients under 50 years of age and 17 per cent for those over 50, the rate rising very steeply with each decade over 50.From 1953 through 1959 selective gastric resection was carried out, the operation being done in all cases of perforated gastric ulcers, of chronic duodenal ulcers and of perforations associated with hemorrhage.During this period 303 perforated ulcers were treated, with a mortality of 15.5 per cent. Patients with associated morbid conditions and those admitted moribund and died, or died undiagnosed were again included.In this series also the mortality increased steeply from age 50 onward.Gastric resection was carried out in 148 cases of perforated peptic ulcer with a mortality of 6 per cent. In 105 cases under 60 years of age there were no deaths but in those over 60 the mortality rate was 21.8 per cent. Results in the patients who had resection, as determined after three years of observation, compared favorably with the results in patients who were treated by suture.The mortality of perforated ulcers in females was higher than in males.Emergency gastric resection has a definite place in the treatment of perforated peptic ulcer. 相似文献
80.