摘要:

The thyroid hormone decarboxylation product, 3,5,3′-triiodothyronamine (T3AM), has been shown to inhibit the CAMP production stimulated by isoproterenol in turkey erythrocytes. This adrenergic receptor binding inhibition was not shown by the thyroid hormones nor by tyramine, but was observed for 3,5-diiodotyramine, 3,5-diiodothyronamine, and thyronamine. T3AM also inhibits prolactin secretion in cultured pituitary cells as well as domperidon binding in rat corpora striata membranes. T3AM has no thyromimetic activity at the nuclear level. The molecular structure of T3AM, determined as a borosalicylate salt by X-ray diffraction techniques, is the first report of a decarboxylated thyroid hormone analogue.

ISSN:0743-5800    

DOI:10.3109/07435808409035410

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

A human insulin degrading enzyme purified from IM-9 lymphocytes was tested for its ability to degrade insulin-like growth factor I (IGF-I) and insulin-like growth factor II (IGF-II). Degradation of these molecules was assessed by trichloroacetic acid precipitation, binding to specific receptors and chromatography on Sephadex G-50. All three techniques indicated that the enzyme readily degraded IGF-II and slightly degraded IGF-I. The IGF-II degrading activity chromatofocused with the insulin degrading activity and was absorbed by specific antibodies to the insulin degrading enzyme. These studies indicate, therefore, that a human insulin degrading enzyme can degrade IGF-II and, to a lesser extent, IGF-I.

ISSN:0743-5800    

DOI:10.3109/07435808409035411

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

The rhythms in pineal N-acetyltransferase (NAT) activity and melatonin levels were studied in the diurnally active Mexican ground squirrel and Eastern chipmunk. In the ground squirrel, both NAT activity and melatonin levels exhibited a marked nocturnal rise; these increases were not prevented by the exposure of these animals to a light irradiance of 200μW/cm2throughout the night. In the Eastern chipmunk, darkness at night was also associated with a marked rise in both the activity of the acetylating enzyme as well as the levels of melatonin. Again, these rhythms were not suppressed by the exposure of these animals to a light irradiance of 200μW/cm2for either 1 night or for 7 nights; exposure of chipmunks to light for 7 consecutive days did, however, reduce the rise in melatonin normally associated with darkness. The non-suppressibility of pineal NAT and melatonin by a 200μW/cm2light irradiance may relate either to the activity pattern of these animals, i.e., diurnal, or to their previous lighting history.

ISSN:0743-5800    

DOI:10.3109/07435808409035412

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

The LHKH agonist CD-Hi s(Bz1)6, Pro9-Nhetllhrh was estimated t o be 3.4, 4.4 and 9.2 times more potent than LHKH as a stimulat or of ovulation in Nembutal-anesthetized, androgen-steri 1 ized and diestrus rats, respectively; and 57 times more potent than LHRH as a stimulator o f uterine growth i n imnature mice. Higher doses o f agonist were required t o induce ovulation i n diestrus hamsters and mice than were needed i n diestrus rats. Rats and hamsters also exhibited different sensitivit i es to an antagonist of LHHH. The LHKH antagonist [N-AcΔ3-Pro1, D-pF-Phe2, D- Trp3s61LHRH was active but higher doses were required to inhibit ovulation in hamsters than were needed i n rats. I n addition, treatment a t 1500 hr on the day of proestrus in rats, in contrast t o treatment at 1000 hr in hamsters, caused the greatest inhibition of ovulation. It is clear from these data, that the estimated in vivo potencies of analogs of LHRH are greatly influenced by species and animal model, as well as route of administration and biopharmaceutic factors previously reported.

ISSN:0743-5800    

DOI:10.3109/07435808409035413

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

Ethanol as either 20% or 36% of total calories in a Lieber diet was administered to male rats. At these concentrations, ethanol consumption relative to body weight did not differ. Pair-fed controls were restricted to the amount of calories consumed by rats given ethanol. Under these conditions, a direct effect of ethanol on the hypothalamic-hypophyseal-thyroid axis could not be demonstrated. There were nodifferences between pair-fed control and ethanol treated rats in serum or pituitary TSH, TSH response to TfH, or T4ond T levels. On the other hand, in rats given ethanol as 36% of total calories serum T4levels occurred (25% and 30%), relative to the corresponding“20%”groups. The decreased T4in the“36%”groups was associated with a pronounced fallin caloric intake, decreased serum TSH, anddeclines in adenohypaphyseaf and body weights–all ofwhichwere of similar magnitude in experimental and control rats. Thus, inanition wasprobably the primary cause of reduced thyroid function in the“36%”groups. An interesting aspect of this change was the finding of no difference in serum T3levels between pair-fed control and ethanol treated rats in the 36% and 20% groups despite the reduced T4and caloric intake in 36% animals; the lack of decrease in T3concentration in 36% animals may reflect augmented peripheral conversion of T4to T3or reduced T3clearowe.

ISSN:0743-5800    

DOI:10.3109/07435808409035414

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

A method is described for the preparatlon of hlgh yields of viable, dissociated cells from porcine theca Interna and corpus lutem and from human and bovine endometrium. The tissues were dissociated by incubation at 37°C in a mixture of 0.5% collagenase, 0.1% hyaluronidase and 0.1% pronase I n balanced saltsolution containing 1% chicken serum. This procedure conslstently provided high yields of structurally and metabolically intact dispersed cells after a digestion period of 60 min. The procedure is superior to methods previously reported in the literature.

ISSN:0743-5800    

DOI:10.3109/07435808409035415

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

The acute gonadotropin and estradiol responses following single subcutaneous injections of 10, 50, 100 and 200μg of {(imBzl)D66-His6, Pro -NEt}-GnRH were compared to those after 100μg of [D-Trp6, Pro - NEt]-GnRH. The gonadotropin responses after 50-100μg of the D-His analog of GnRH were equivalent to those following 100μg of the D-Trp analog. The ovarian E2response, a reflection of the total cumulative secretion of gonadotropins, was similar at 100μg of each analog. The estradiol response paralleled the increasing gonadotropin response accompanying the graded doses of the D-His analog, indicating the lack of a direct inhibitory action of this GnRH agonist on the ovary. Assessment of both gonadotropin and estradiol responses appears to be satisfactory for assessing relative potency among GnRH agonistic analogs.

ISSN:0743-5800    

DOI:10.3109/07435808409035416

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

Gel filtration and high performance gel filtration showed the zinc of prostatic cytosol to be associated with a low molecular weight ligand. Absence of degradation of this ligand by proteolytic enzymes but its disappearance after action of the citrate lyase system led to the identification of the ligand with citrate. Involvement of zinc-citrate in prostatic zinc homeostasia is discussed.

ISSN:0743-5800    

DOI:10.3109/07435808409035417

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

Slices of human hyperplastic prostates were superfused with±6 5Zn±Cl2in the absence or in the presence of testosterone or 5α-dihydrotestosterone or 5α-androstane-3α, 17β-diol. Uptake of±6 5Zn±Cl2was not significantly changed by steroid androgens but the binding of±6 5Zn±to the citrate of prostatic cytosol was generally significantly decreased by the tested steroids. The 5α-reduced androgens were more efficient than testosterone in decreasing bound zinc levels and increasing free zinc concentrations. Implications of these findings on the metabolism and differentiation of prostatic cells are discussed.

ISSN:0743-5800    

DOI:10.3109/07435808409035418

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor

摘要:

The equilibrium association constant, KA, and the number of receptor binding sites, Bmax, that characterize the estrogen receptor present in rat thymus were determined using five different methods of data analysis on binding data obtained using a dextran-coated-charcoal assay. The methods of data analysis consisted of fitting the binding data directly to the hyperbolic binding function, fitting the data to the Lineweaver-Burk, Scatchard, and Woolf transforms of the hyperbolic function, and the direct linear plot method of Eisenthal–Cornish-Bowden. The Woolf and Eisenthal–Cornish-Bowden methods gave identical results indicating that added estradiol caused a decrease in KA(competitive inhibition) and a marked decrease in Bmax(noncompetitive inhibition). The Scatchard analyses gave only a very qualitativeindication of this trend, while the Lineweaver-Burk analyses gave no indication of any such systematic trend. The results from the computationally more difficult fits to the hyperbolic binding equation were in agreement with the Woolf and Eisenthal–Cornish-Bowden results. Thus, the cytosolic thymus estrogenreceptor from the rat shows both competitiveand noncompetitive inhibition in the presence of endogenous or exogenous estradiol.

ISSN:0743-5800    

DOI:10.3109/07435808409035419

出版商:Taylor&Francis    

年代:1984

数据来源: Taylor