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81.
Paula Klevjer-Anderson Gertrude Case Buehring 《In vitro cellular & developmental biology. Plant》1980,16(6):491-501
Summary The individual effects of seven hormones on the in vitro growth rate of different classifications of human mammary epithelium
were compared. Hormones used were: 17β-estradiol, estriol, progesterone, hydrocortisone, testosterone, prolactin, and growth
hormone. Cell cultures included three established breast cell lines and primary monolayer cultures established form breast
fluids and excised mammary tissue from 40 women and 4 men. Specimens comprised three classifications: normal, nonmalignant
atypical, and malignant. Growth was quantitated in situ and expressed as population doubling time. Principal findings were:
(a) estrogens, prolactin, and growth hormone stimulated growth of normal cells more frequently than growth of malignant cells,
whereas testosterone and hydrocortisone stimulated growth of malignant cells more frequently than growth of normal cells;
(b) cells cultured from nonmalignant atypias generally showed hormone response profiles intermediate between those of normal
and malignant cells; (c) progesterone stimulated the growth of cells from malignant specimens but not the growth of cells
from normal and nonmalignant atypical samples.
This research was supported by NIAID Research Training Grant 5-TO1-A1-00332-06. 相似文献
82.
The relative contributions of ventral blood island mesoderm and dorsal anterior mesoderm to differentiated lineages of hematopoietic cells was assessed by reciprocal grafting of cytogenetically labeled tissues between 67- and 72-hr-old frog embryos (Shumway stages 15–16). Diploid (2N) and triploid (3N) cell populations from hematopoietic organs were distinguished by Feulgen-DNA microdensitometric analysis. Ventral blood island mesoderm appears to contribute an embryonic erythrocyte population that progressively declines during larval development. Dorsal anterior mesoderm appears to contribute a population of precursor cells that gives rise to differentiated lineages of hematopoietic cells found in the thymus, pronephros, mesonephros, spleen, and blood. Histological examination of the developing dorsal anterior area indicates that extensive vascularization is a prominent characteristic of this region. The dorsal aortae and vasculature surrounding the pronephros may be sites where at least one population of hematopoietic cells matures and subsequently enters circulation. 相似文献
83.
Paula Branefors-Helander Björn Classon Lennart Kenne Bengt Lindberg 《Carbohydrate research》1979,76(1):197-202
The structure of the capsular antigen from Haemophilus influenza type c has been investigated, n.m.r. spectroscopy being the principal method used. It is concluded that the antigen is composed of repeating-units having the following structure: O-Acetyl groups are present in ~90% of the repeating-units. 相似文献
84.
85.
Paula M. Pitha Vitolis E. Vengris Fred H. Reynolds 《Journal of cellular biochemistry》1976,4(4):467-473
The mechanism of interferon action in human fibroblasts has been studied by use of both antisera to human fibroblast interferon and the antisera to the surface of human fibroblast cell. The anti-interferon serum completely neutralized the antiviral effect of human fibroblast interferon. Interferon antiserum prevented the intracellular antiviral state from developing when added to the medium of the cells in which interferon synthesis had already been induced by poly (I · C). This suggests that development of the antiviral state involves interferon interaction with the external part of the producing cell. Treatment with the serum directed against the surface of human fibroblast cells failed to inhibit the antiviral activity of human interferon in these cells. In addition, the effect of gangliosides on the antiviral activity of human interferon was studied and it was found that human interferon binds to gangliosides and that this interaction leads to inactivation of the antiviral effect of interferon. Pretreatment of human fibroblasts with gangliosides had no effect on the sensitivity of these cells to exogenous interferon. 相似文献
86.
Nonautotrophic thiobacilli were isolated from the acidic water of a coal mine. Based on their mixotrophic physiology, the isolates are regarded as strains of Thiobacillus perometabolis. 相似文献
87.
Induction of back mutations to prototrophy by methylene blue (MB)-sensitized photodynamic (PD) treatment has been studied in wild-type and repair-deficient strains of Salmonella typhimurium carrying either the base-pair substitution mutation hisG46 or the frameshift mutation hisD3052. We found that reversion of the hisG46 mutation was increased in a strain carrying a uvrB deletion and decreased in a strain carrying a recA-type mutation. Reversion of the hisD3052 (frameshift) mutation, on the other hand, was decreased in both uvrB deletion and recA-type strains. The former results are consistent with the hypothesis that the majority of MB-sensitized PD-induced base-pair substitution mutations arise by a mechanism similar to that currently believed to be involved in UV mutagenesis. The latter results suggest that PD-induced frameshift mutations may arise in some other way, and two possible mechanisms involving sequential action of the excision repair and recombinational repair pathways are considered. 相似文献
88.
89.
Effective coordination is key to many situations that affect the well-being of two or more humans. Social coordination can be studied in coordination games between individuals located on networks of contacts. We study the behavior of humans in the laboratory when they play the Stag Hunt game – a game that has a risky but socially efficient equilibrium and an inefficient but safe equilibrium. We contrast behavior on a cliquish network to behavior on a random network. The cliquish network is highly clustered and resembles more closely to actual social networks than the random network. In contrast to simulations, we find that human players dynamics do not converge to the efficient outcome more often in the cliquish network than in the random network. Subjects do not use pure myopic best-reply as an individual update rule. Numerical simulations agree with laboratory results once we implement the actual individual updating rule that human subjects use in our laboratory experiments. 相似文献
90.
Roberto A. Saenz Paula Medone Natalia di Clemente Anthony Tongen Jorge Rabinovich 《Physiological Entomology》2017,42(4):336-345
The molting process and body growth in Rhodnius prolixus (Hemiptera: Reduviidae) (Ståhl, 1859) are significantly influenced by the availability and quality of food. Based on the body weight of each stage, the present study provides estimates of a potential critical weight threshold required for molt initiation in R. prolixus. In addition, a new measure given by the area under the weight curve is proposed, which encapsulates both body weight and time. It is shown that this measure is consistent with the data, and allows the estimation of a pre‐refractory period (i.e. the time interval between the moment at which the critical weight threshold is reached and the moment when no further meals are accepted). The present analysis estimates the critical weight threshold as 1.6, 5.3, 12.9, 42.0 and 97.0 mg for stages 1–5, respectively, whereas the values of the area under the curve threshold as 5, 16, 31.2, 159.7 and 329.9 mg days for stages 1–5, respectively. The results of the present study confirm the existence of a weight‐dependent mechanism for the initiation of molting in R. prolixus. 相似文献