Gene/Protein Disease Symptom Drug Enzyme Compound
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Ortho- and parainfluenza viruses isolated from the cloacas of migrating feral ducks shot on the Mississippi flyway included three strains of influenza. A virus (Hav6 Nav1, Hav6 Nl, Hav7 Neq2) as well as Newcastle disease virus. One influenza virus, A/duck/Memphis/546/74, possessed Hav3 haemagglutinin, but the neuraminidase was not inhibited by any of the known influenza reference antisera. The neuraminidase on this virus was related to the neuraminidases on A/duck/GDR/72 (H2 N?), A/turkey/Ontario/7732/66 (Hav 5 N?), A/duck/Ukraine/1/60 (Hav3 N?) and A/turkey/Wisconsin/68. We therefore propose that the neuraminidase on this group of influenza viruses be designated Nav6. The A/duck/Memphis/546/74 influenza virus caused an ocular discharge in 1 of 5 ducks and was shed in faeces for 10 days; it was stable in faecal samples for up to 3 days at 20 degrees C. These results suggest that ecological studies on influenza in avian species should include attempts to isolate virus from faeces. Faecal-oral transmission is an attractive explanation for the spread of influenza virus from feral birds to other animals.
J Gen Virol 1976 Aug
PMID:Ortho- and paramyxoviruses from migrating feral ducks: characterization of a new group of influenza A viruses. 101 73

The effects of exogenous estradiol valerate on some uterine characteristics of the musk shrew were investigated. Treatment with the steroid for either 1 day or 7 days did not noticeably alter luminal epithelial cell height, endometrial gland epithelial cell height or diameter, or number of endometrial glands. The reciprocal values of cell density of circular muscle and deep endometrial layers and endometrium-to-myometrium ratio of the uterus increased significantly in response to 7 days of steroid administration. After 1 day of steroid treatment the numbers of mast cells in different layers of the uterus (i.e., meso-, myo-, and endometrium) were unchanged, but after 7 days there were significant increases in the number of mast cells in meso- and myometria. The number of eosinophils in all three layers of the uterus increased significantly in response to the treatment of estradiol for 1 day or for 7 days. The increase was greater in the 7-day group. Neither uterine DNA nor RNA contents changed following administration of the steroid for either group, although protein content was elevated significantly in the 7-day group. Estradiol administration thus evokes small but subtle changes in the uterus of the musk shrew.
Gen Comp Endocrinol 1992 Oct
PMID:Effects of estradiol valerate on the uterus of the musk shrew (Suncus murinus L.). 138 61

It has been suggested that sex differentiation in vertebrates is steroid hormone dependent, that estrogens play a critical role in ovarian differentiation, and that male sex differentiation will occur in the absence of estrogens. Using the model of the alligator in which sex can be manipulated by incubation conditions (eggs incubated at a constant temperature of 30 degrees produce 100% females, and at 33 degrees produce 100% males), a series of experiments using antiestrogens, antiandrogen, estradiol-17 beta, dihydrotestosterone (DHT), and aromatase inhibitors were performed. Test substances were injected into alligator eggs prior to gonadal sex differentiation and the eggs were incubated at male or female temperatures until just before expected date of hatching. Gonads were excised and the sex was verified histologically. Control embryos injected with vehicle produced the expected sex: females at 30 degrees and males at 33 degrees. Estradiol in eggs at 33 degrees (male temperature) produced 100% females and did not alter female development in eggs at 30 degrees. Antiandrogen, DHT, and a steroid antiestrogen had no discernible effect in either the 30 degrees or the 33 degrees eggs at the doses tested. The aromatase inhibitors aminoglutethimide and 4-hydroxyandrostenedione caused a moderate disruption of ovarian development and had no apparent effect on testicular development. The nonsteroidal aromatase inhibitor, Ciba Geigy 16949A, caused inhibition of ovarian development in all treated embryos. The Mullerian ducts did not appear to be affected by this treatment, or by any of the other treatments, and the gonads did not appear masculinized. We conclude that estrogen appears to be necessary for normal ovarian development, but that inhibition of estrogen synthesis alone is insufficient to cause masculinization. Likewise, exogenous androgens appear unable to masculinize embryonic gonads. The evidence suggests that testicular differentiation in amniote vertebrates is dependent on factors other than androgens or level of estrogens.
Gen Comp Endocrinol 1992 Apr
PMID:Disruption of ovarian development in alligator embryos treated with an aromatase inhibitor. 138 96

The present work was carried out to study the in vitro effects of mammalian gonadotropin-releasing hormone (mGnRH) on Rana esculenta and Triturus carnifex testis production of prostaglandin F2 alpha (PGF2 alpha) and sex steroid hormones during the prereproduction, reproduction, and postreproduction periods. In R. esculenta, testicular PGF2 alpha release was lower during postreproduction, and mGnRH increased PGF2 alpha in prereproduction and reproduction. Androgens were higher during prereproduction, and mGnRH induced an androgens increase in prereproduction and reproduction. In T. carnifex testicular PGF2 alpha release was lower during reproduction, and mGnRH increased PGF2 alpha in prereproduction and reproduction. Androgens were higher in reproduction and lower in postreproduction, and mGnRH induced an androgens increase in reproduction. Estradiol-17 beta release was higher in postreproduction, and mGnRH induced an estradiol decrease in reproduction and an increase in postreproduction. These results seem to indicate the involvement of PGF2 alpha in the testicular reproductive activity, and a similar mGnRH mechanism of action, both in R. esculenta and in T. carnifex. In addition, taken together with previous studies, they seem to suggest that the relationship found between mGnRH and PGF2 alpha or sex steroids could be widespread in amphibians.
Gen Comp Endocrinol 1992 Aug
PMID:Mammalian GnRH involvement in prostaglandin F2 alpha and sex steroid hormones testicular release in two amphibian species: the anuran water frog, Rana esculenta, and the urodele crested newt, Triturus carnifex. 139 18

North Island brown kiwi (Apteryx australis mantelli) have a seasonal pattern of egg laying with a peak in mid to late winter. This study is the first description of changes in plasma steroid concentrations during the annual reproductive cycle of this species. Blood samples were collected at intervals over a 2 1/2-year period from a population of kiwi at Tangiteroria, Northland, New Zealand. Male kiwi had annual cycles of plasma levels of testosterone and estradiol. Mean testosterone levels were low (less than 0.18 ng/ml) during February to April, rose in May to a broad peak lasting 4 months (maximum levels 1.90 +/- 0.76 ng/ml), declined in September, and reached low levels in November to January. With respect to the breeding cycle, testosterone levels were low in the nonbreeding period, rose to high levels over 2 to 4 months before egg laying, then declined steadily toward the start of incubation. Plasma testosterone levels were very low in brooding males. Mean estradiol levels in males showed a pattern similar to testosterone levels, except that the rise to peak levels (1750 +/- 680 pg/ml) started in April. In female kiwi mean testosterone levels were low (less than 0.10 ng/ml) throughout the year. There was an annual cycle of mean estradiol levels in females which in timing and amplitude was similar to the male cycle. Estradiol levels in relation to stages of the breeding cycle in females were basal in the nonbreeding period, increased over a 3-month period before egg laying, declined in the 2 weeks before laying, and were low thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)
Gen Comp Endocrinol 1992 Sep
PMID:Plasma levels of sex steroids in the North Island brown kiwi (Apteryx australis mantelli) in relation to time of year and stages of breeding. 142 44

Estradiol 17-beta is known to induce hepatic synthesis and secretion of vitellogenin in all species studied and in Rana esculenta, previous experiments demonstrated the involvement of pituitary in these processes; indeed, in addition to estradiol 17-beta, homologous pituitary homogenate directly stimulated male and female liver to produce vitellogenin in tissue cultures. Therefore, the effect of ovine growth hormone (o-GH) and Rana catesbeiana growth hormone (f-GH) on hepatic vitellogenin synthesis was investigated. In the present in vitro experiments, both o-GH and f-GH positively stimulated vitellogenin synthesis, in female and male liver, in a dose-related fashion. No significant differences were found in VTG levels induced by o-GH and f-GH. The GH stimulatory effects, found during the different phases of the reproductive cycle, displayed different trends related to season and sex.
Gen Comp Endocrinol 1992 Dec
PMID:Hormonal control of in vitro vitellogenin synthesis in Rana esculenta liver: effects of mammalian and amphibian growth hormone. 149 May 86

Significant amounts of cortisol (20 ng/g) and thyroid hormones thyroxine (T4, 20 ng/g) and triiodothyronine (T3, 10 ng/g), as well as estradiol (8 ng/g) and testosterone (4 ng/g), are present in fertilized eggs of chum salmon. Changes in the concentrations of these hormones in the developing embryo and larvae were monitored until after the emergence of the fry from the gravel bed. Cortisol concentrations in the developing embryo fell steadily from 20 ng/g at fertilization to 2.5 ng/g after 3 weeks, increased slightly to 10 ng/g by 1 week before hatching, and maintained this level during the early stages of yolk sac absorption. During the later stages of yolk sac absorption, cortisol concentrations increased markedly and remained at about 30 ng/g until emergence, when they declined to 10-15 ng/g. In contrast, both T4 and T3 levels were stable during early development, decreased gradually during yolk sac absorption, and increased slightly during emergence. Estradiol and testosterone profiles were similar to that of cortisol during early development. Testosterone levels remained low throughout emergence. Likewise, estradiol levels were low during yolk sac absorption but showed a transient increase at the time of emergence. These hormonal changes are discussed in the context of egg development and subsequent downstream migration.
Gen Comp Endocrinol 1992 Jan
PMID:Changes in whole body concentrations of cortisol, thyroid hormones, and sex steroids during early development of the chum salmon, Oncorhynchus keta. 156 18

Circulating levels of plasma estradiol, 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17 alpha,20 beta PROG), and thyroxine were measured during smoltification of coho salmon in two successive years (1984 and 1985). Two elevations of thyroxine occurred in both years, the first occurred in April followed by a second increase in May. Estradiol levels were dynamic with variable changes particularly in postsmolts when estradiol levels were either depressed in 1984 or high in 1985. However, elevations of estradiol preceded the second elevation of thyroxine in May in both years when the salmon were undergoing the later stages of smoltification. There were no consistent changes of plasma 17 alpha,20B PROG during this period. Although, in 1984, there were significant elevations and depressions of 17 alpha,20B PROG, and in 1985, there was a major unexplained depression of 17 alpha,20B PROG on April 24. There were no sexual differences noted for plasma steroid levels in the juvenile fish. These data suggest that there are seasonal changes of estradiol coinciding with other developmental changes during smoltification.
Gen Comp Endocrinol 1992 Feb
PMID:Changes in plasma thyroxine, estradiol-17 beta, and 17 alpha,20 beta-dihydroxy-4-pregnen-3-one during smoltification of coho salmon. 160 Dec 59

Steroid concentrations in plasma and follicular tissues (theca plus granulosa layers) were determined by radioimmunoassay in the aplacental viviparous ray, Torpedo marmorata, during various stages of the reproductive cycle. Steroids in the uterine fluid of pregnant animals and in preovulatory atretic follicles were also measured. In the follicular tissue of cyclic animals, levels of progesterone were always lower than those of estradiol-17 beta and androgens (testosterone plus 5 alpha-dihydrotestosterone). Estradiol-17 beta and androgen levels increased as the animals approached the ultimate maturational stage before ovulation. Androgens were not detectable in plasma, while estradiol-17 beta increased dramatically before ovulation. In pregnant animals, only small ovarian follicles (less than 5 mm in diameter) were observed, and these had hormone concentrations that were similar to those of the small follicles of cyclic animals. Progesterone was the only steroid detected in the uterine fluid of pregnant animals. In completely sclerotic atretic follicles of pregnant animals, steroids were not detected. Progesterone was the main hormone in atretic follicles undergoing yolk resorption. This suggests that the latter may contribute to the elevated plasma progesterone concentrations of pregnant animals.
Gen Comp Endocrinol 1992 Feb
PMID:Plasma and follicular tissue steroid levels in the elasmobranch fish, Torpedo marmorata. 160 Dec 64

Changes in serum concentrations of gonadotropins and gonadal steroids during the periovulatory period were monitored in green, Chelonia mydas, and loggerhead, Caretta caretta, sea turtles. Turtles were from natural populations that nest on a coral island on the Great Barrier Reef. After nesting, each turtle was transferred to a holding tank and held for a maximum of 8 days. A time series of blood samples was obtained from each of five sea turtles (three C. mydas and two C. caretta) starting immediately after nesting and then at approximately 12-hr intervals until the time of release. Prior to release back into the ocean, each turtle was examined by laparoscopy to verify that ovulation had occurred. Serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), progesterone (PRO), and testosterone (T) in both species exhibited significant changes during this period. Surges of FSH, LH, and PRO were evident within approximately 20 to 50 hr after each turtle had nested. The significant change in FSH concentration during the periovulatory period is the first such report for a reptile. Coincident with maximal concentrations of FSH, LH, and PRO was a decline in T concentrations in both species. Estradiol-17 beta concentrations were near or below assay sensitivity in the C. mydas, whereas those in the C. caretta were detectable but exhibited no significant changes. The dynamic changes in FSH, LH, PRO, and T concentrations are consistent with the hypothesis that these hormones facilitate specific physiological events during ovulation and egg production.
Gen Comp Endocrinol 1992 Jul
PMID:Serum gonadotropins and gonadal steroids associated with ovulation and egg production in sea turtles. 162 99


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