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In male neotenic axolotls Ambystoma mexicanum plasma concentrations of thyroxine (T4) and testosterone were increased following intravenous injection of 10 micrograms luteinizing hormone-releasing hormone. A dose of 50 micrograms influenced only plasma T4 levels. This observation suggests for the first time that a hypothalamic hormone is capable of stimulating the thyroidal axis in the neotenic axolotl.

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Circulating levels of T3 and T4, as well as T3 and T4 content of the thyroid glands were measured by radioimmunoassay in the neotenic and metamorphosed axolotl Ambystoma mexicanum. In the two experiments which were performed plasma T4 concentrations were more elevated in metamorphosed axolotls, especially in the first experiment (2.12 +/- 0.40 ng/ml vs. 369 +/- 30 pg/ml). T3 plasma values which were only estimated in the second experiment were about five times higher in metamorphosed animals (63.2 +/- 7.4 pg/ml vs. 12.5 +/- 0.8 pg/ml). Also the thyroid hormone content of the glands was higher after metamorphosis. Nevertheless the neotenic gland still contained considerable amounts of T3 (14.7 +/- 1.8 ng and 48.3 +/- 4.8 ng/thyroid, respectively, in the first and second experiment) and T4 (530 +/- 61 ng; 2173 +/- 291 ng/thyroid). Because of the higher T3/T4 ratio found in the plasma compared to the thyroid gland, it was suggested that circulating T3 may be derived partly from peripheral T4 conversion, mainly after metamorphosis. An intravenous injection of 10 micrograms synthetic TRH was able to induce a very significant increase of the plasma T4 concentration (which was maintained during 24 hr) in the metamorphosed axolotls of the first experiment, however, not in those of the second experiment nor in the neotenic animals. Following an injection of 10 mU bovine TSH (first experiment) circulating levels of T4 were raised in both groups. The opposing TRH results could be related with the different control levels of T4 in the two experiments. However, the results indicate that TRH is capable of functioning as a possible thyrotropin-releasing factor in the metamorphosed axolotl.

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Basal and TSH-induced plasma concentrations of T4 have been measured by radioimmunoassay in the neotenic and metamorphosed male axolotl Ambystoma mexicanum both before and after an ovine prolactin pretreatment. All injections are made into the vena abdominalis. Basal levels of T4 are low in neotenes (85 +/- 19 pg/ml) and somewhat higher in metamorphosed Ambystoma (171 +/- 39 pg/ml), but are increased during metamorphosis (1094 +/- 138 pg/ml). Following injection of 5 mU bovine TSH circulating levels of T4 are raised about 4 times in neotenes, but more than 50 times in metamorphose animals. Three intravenous injections, each of 640 mU prolactin and given, respectively, 24 and 13 hr before and simultaneously with 5 mU TSH, do not inhibit the TSH-induced release in both experimental groups. In the metamorphosed Ambystoma again a more than 50-fold T4 increase is present, whereas in neotenes a 10-fold TSH-induced T4 release is seen, which is more pronounced than before the prolactin treatment. It is concluded that in A. mexicanum ovine prolactin does not block a TSH-induced T4 release and that any antagonistic action with thyroid hormones is not mediated through the thyroid gland.

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Circulating levels of T4 are measured by radioimmunoassay after intravenous injection of TRH, bovine (b) TSH, and pituitary extracts in the Mexican axolotl (Ambystoma mexicanum). Very low control levels of T4 are found (53 +/- 3 pg/ml (n = 27), but they are increased sevenfold following injection of 1/2 pars distalis extract or 1/2-1/10 IU b-TSH. Increased levels following these injections are found in plasma up to 48 hr after the injection. An in vitro assay also indicates that a 1/2 pars distalis of the axolotl is able to release T4 from the thyroid of R. ridibunda somewhat less effectively than a 1/50 pars distalis of the same size of R. ridibunda itself. TRH (50 and 100 micrograms) is unable to stimulate the release of T4 when injected intravenously into the axolotl. It is concluded that both the hypophysis and the thyroid gland of A. mexicanum may release optimal amounts of hormones necessary for metamorphosis following proper stimulation, but that TRH cannot function as a releasing hormone in this respect.

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The clinical course and morphological findings are reported of visceral paracoccidioidomycosis or South American blastomycosis with lung involvement in a 47-year-old male after specific antimycotic treatment for 11 years. The patient had been infected during a stay in São Paulo, Brazil, from 1950 to 1954. The diagnosis was established in 1959 after his return to St. Gall, Switzerland, in tissue from buccal mucosa and cervical lymph node biopsy and in fungus cultures. The patient was treated with Fungizone (amphotericin B) and with the sulfonamide Fanasil. He died in 1970 from acute right heart failure. Autopsy revealed multiple encapsulated mycotic foci in both lungs, together with healed foci and pulmonary fibrosis. Histological examination showed a large amount of Paracoccidioides brasiliensis in the mycotic foci, but cultural proof was no longer possible. In the buccal mucosa and lymph nodes, only fungus-free scars were observed. There are only a few effective antimycotic agents. With a thorough knowledge of their side effects and dosage modalities, it is possible to achieve highly satisfactory results.

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