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1.
Morphological and histological study of castration-induced degeneration and androgen-induced regeneration in the mouse prostate 总被引:3,自引:0,他引:3
Degenerative and regenerative changes in the ductal architecture of the ventral and dorsolateral prostates (VP and DLP) of the adult mouse were investigated in microdissected specimens over a time-course of 14 days following castration and subsequently during 14 days of administration of testosterone propionate. After castration, about 35% of the ductal tips and branch-points were lost in distal regions (usually near the capsule) in both prostatic lobes. By contrast, in more proximal regions of the prostate (closer to the urethra), the ducts survived in an atrophic condition. The ductal morphology that had been lost in the distal regions completely regenerated after testosterone propionate was administered to the castrated males. In the VP, androgen replacement simply returned the gland to its former size with moderate ductal distension; in the DLP, excessive epithelial infoldings and ductal distension were elicited in the distal regions of the ducts after 14 days of treatment with testosterone propionate. These results suggest that androgenic responsiveness and dependency are different in distal versus proximal ducts. Distal ducts are exquisitely androgen-dependent and androgen-sensitive; in proximal regions, androgen-dependency is not as strict. 相似文献
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Studies have been conducted to determine whether the mutagens in fried beef ingested by human subjects are excreted in the urine. Urine samples were collected from individuals on liquid or regular diets before and after a fried beef meal. The mutagenic activity of the samples was tested in the Ames Salmonella/microsome assay system. The results showed that in individuals on liquid diets, most of the urinary mutagenic activity is recovered within 2-6 h after consuming a fried beef meal. In one individual tested, mutagenic activity was found in urine samples obtained 6-15 h after the fried beef meal. No mutagenic activity was detected in any of the urine samples obtained 15-24 h following the meal. In individuals on a regular diet, however, mutagenic activity was frequently observed in urine samples obtained 16-24 h following the fried beef meal, although the mutagenic activity was not as great as that in the preceding 16 h. It appears that the mutagenic agents generated by the frying of beef are ingested, absorbed, and excreted by the human body in biologically detectable quantities. These results suggest that subjects should abstain from fried beef at least one day prior to and during urine mutagenicity screening. 相似文献
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Applications of intrinsic fluorescence measurements in the study of Ca2+-transport ATPases are reviewed. Since the initial reports showing that the fluorescence emission was sensitive to Ca2+ binding, a substantial amount of work has focused on the use of both steady-state and time-resolved fluorescence spectroscopy to investigate structure-function relationships in sarcoplasmic reticulum and plasma membrane Ca2+-ATPases. These studies have revealed ligand-induced conformational changes, as well as provided information on protein-protein, protein-solvent and/or protein-lipid interactions in different functional states of these proteins. The main results of these studies, as well as possible future prospects are discussed. 相似文献
6.
Paula Tatiana Lopes Seixas Antonio Jacinto Demuner Luiz Claudio Almeida Barbosa Cristiane Isaac Cerceau Daiane Einhardt Blank Marcelo Henrique Dos Santos Elizeu de Sá Farias Marcelo Coutinho Picanço 《Journal of Applied Entomology》2023,147(2):116-125
Aedes aegypti L. (Diptera: Culicidae) is a vector for serious diseases in tropical regions. This pest is mainly controlled by commercial larvicides but the application of such products has led to environmental problems. Essential oils (EO) have been consistently reported as molecules with insecticidal activity and can be used to produce more environmentally friendly larvicides in the control of A. aegypti. In this study, the larvicidal effect of essential oils (EO) from the leaves of three Artemisia species was evaluated against A. aegypti. The oils were obtained from steam distillation and their chemical composition was determined by gas chromatography–mass spectrometry. The EO of Artemisia camphorata was the most active in the screening bioassay and presented LC50 and LC95 of 64.95 and 74.18 μg ml−1, respectively. In addition, we found that germacrene D-4-ol was the constituent responsible for the toxicity of this EO. Artemisia camphorata EO and its major constituent, germacrene D-4-ol, are promising for the development of natural larvicides against A. aegypti. 相似文献
7.
Several genera of N2-fixing bacteria establish symbiotic associations with plants. Among these, the genus Rhizobium has the most significant contribution, in terms of yield, in many important crop plants. The establishment of the Rhizobium-legume symbiosis is a very complex process involving many genes which need to be co-ordinately regulated. In the first instance, plant signal molecules, known to be flavonoids, trigger the expression of host-specific genes in the bacterial partner through the action of the regulatory NodD protein. In response to these signals, Rhizobium bacteria synthesize lipo-oligosaccharide molecules which in turn cause cell differentiation and nodule development. Once the nodule has formed, Rhizobium cells differentiate into bacteroids and another set of genes is activated. These genes, designated nif and fix, are responsible for N2 fixation. In this system, several regulatory proteins are involved in a complex manner, the most important being NifA and a two component (FixK and FixL) regulatory system. Our knowledge about the establishment of these symbioses has advanced recently, although there are many questions yet to be solved. 相似文献
8.
An increase in nitric oxide produced by rat peritoneal neutrophils is not involved in cell apoptosis
Fierro IM Barja-Fidalgo C Canedo RM Cunha FQ Ferreira SH 《Mediators of inflammation》1995,4(3):222-228
Polymorphonuclear neutrophils (PMN) obtained from carrageenin-stimulated peritoneal cavities of rats, but not blood PMN, spontaneously produced nitric oxide (NO) when incubated in vitro. Incubation of the cells with the NO synthase inhibitors, L-imino-ethyl-L-ornithine (L-NIO) or N(G)-monomethyl-L-arginine (L-NMMA), inhibited NO production. This inhibition could be reversed by L-arginine. Incubation of PMN with lipopolysaccharide (LPS) failed to enhance NO production. Pretreatment of the rats with dexamethasone (DEXA) prior to carrageenin injection or incubation of PMN with the glucocorticoid in vitro partially inhibited the spontaneous release of NO. On the other hand, when PMN obtained from DEXA pretreated rats were incubated in vitro with DEXA, NO synthase activity and hence NO generation were almost abolished. A similar inhibition was also observed following the addition of L-NIO or cycloheximide to cultures of carrageenin-elicited PMN. The NO production by PMN did not appear to be related to cell viability or apoptosis. Indeed, neither the blockade of NO generation by L-NIO nor the incubation of the neutrophils with a NO donor, S-nitroso-acetylpenicillamine (SNAP) modified the pattern of LDH release or DNA fragmentation. In summary, it appears that PMN migration triggers a continuous NO synthesis, and that NO produced by these cells is not related to their apoptosis. 相似文献
9.
Tatiana Kozhina Lubomira Stateva Pencho Venkov 《Molecular & general genetics : MGG》1979,170(3):351-354
Summary The genetic analysis of VY1160 sorbitol dependent, osmotic sensitive yeast mutant led to the identification of three different nuclear recessive mutations. Two of them, designated sorb- and ts1 are closely linked to one another. The mutation sorb- determines the lysis, while the mutation tsl increases the ability for lysis of the sorbitol dependent cells. The third mutation ts2 segregates independently from the other two and confers the sensitivity of VY1160 mutant cells towards rifampicin. 相似文献
10.
Phage M-1 produced clear plaques with a halo in the lawn of Rhizobium japonicum D211. A one step growth curve of phage M-1 showed a latent period of 3 h, burst size of 55 and rise period of 2 h. The inactivation of phage M-1 was found to be dependent upon the concentraion of d-glucosomanine. The neutralization kinetics of phage M-1 by antiphage serum gave a K value (velocity constant) of 83.1 min–1. Transduction of str and kan was studied in the presence of antiphage serum and d-glucosamine. Cotransduction of different antibiotic resistance markers suggested that the system can be further explored for high resolution mapping in R. japonicum.Abbreviations YM
yeast mannitol medium
- PFU
plaque forming unit
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moi
multiplicity of infection
- EOP
efficiency of plating 相似文献