Nonresponsiveness of the thyroid gland to goitrogen in the early neonatal period in the rat: light- and electron-microscopic observations.

The thyroid response of fetal and neonatal rats to propylthiouracil (PTU) as a goitrogen was studied with observation of the thyroid glands by light and electron microscopy. On day 19 of gestation and on days 1, 3, 5 and 8 after birth, fetal and neonatal rats were given a subcutaneous injection of PTU and were autopsied 2 days later. PTU induced conspicuous goiters in fetal rats but did not in neonatal rats aged up to day 5 after birth. Beyond that age, PTU again induced goiters. Histologically, the follicular cell height in goitrous thyroid glands was significantly increased. Ultrastructurally, follicular cells in goitrous thyroid glands often had colloid droplets and lysosomes. It seems that nonresponsiveness of the thyroid glands in early neonatal rats to goitrogen is due to a temporary decline of the pituitary activity of thyrotropin secretion. About 5 days or more after birth, the pituitary-thyroid system begins to operate again in response to goitrogen.     

Suppression of lymphocyte spontaneous proliferative response by proteolipid protein peptide in patients with HAM/TSP

To understand the immune mechanism suggested in HTLV-I-associated myelopathy (HAM/TSP), we investigated T cell response to proteolipid protein (PLP). Because of high autologous proliferative response (APR) of peripheral blood mononuclear cells (PBMC) in culture, the lymphocyte proliferation assay was not useful in this disease. Unexpectedly, however, APR was profoundly (70–98%) suppressed in 6 of 9 cases when PLP peptide 105-124 was added in the culture. PLP peptide 85-104 or 145-159 also suppressed APR in a few cases. Time course study showed that the peptide-mediated suppression became apparent after day 4 in culture. The results can be interpreted as that suppressor cells recognizing the PLP peptides were present in the PBMC of HAM/TSP patients and suppressed the APR as the consequence of antigen specific response. This may indicate that a T cell response to certain PLP determinants is involved in the pathomechanism of HAM/TSP at least in part. Molecular mimicry between PLP and HTLV-I mayaccount for the T cell sensitization to PLP in HAM/TSP.Special issue dedicated to Dr. Marjorie B. Lees.     

Further study on 1/f fluctuations observed in central single neurons during REM sleep

Recently, 1/f fluctuations have been discovered in the single-unit activity of mesencephalic reticular formation (MRF) neurons during REM sleep. In a previous paper, such behavior could satisfyingly be interpreted on the basis of the clustering Poisson process. The question of applicability of this model to other MRF neurons remained unanswered. The present paper reports on 1/f fluctuations in 12 MRF neurons all of which can satisfyingly be modeled by the clustering Poisson process.     

Effect of internally loaded iodide, thiocyanate, and perchlorate on sodium-dependent iodide uptake by phospholipid vesicles reconstituted with thyroid plasma membranes: iodide counterflow mediated by the iodide transport carrier

Na+-dependent I- transport and I- counterflow were studied using phospholipid vesicles (P-vesicles) made of porcine thyroid plasma membranes and soybean phospholipid by sonication. 1) I- uptake by P-vesicles incubated in the presence of external Na+ was higher than that by P-vesicles incubated in choline+ instead of Na+. The vesicles exhibited Na+-dependent I- uptake. When P-vesicles were internally loaded with I- prior to incubation in Na+, a further increase in Na+-dependent I- uptake was observed, although the concentration of internal I- was very much higher than that outside. In the absence of external Na+, I- uptake by P-vesicles preloaded with I- was comparable to baseline uptake. 2) Na+-dependent I- uptake by P-vesicles not loaded with I- and enhanced Na+-dependent I- uptake by P-vesicles preloaded with I- were both inhibited by either of SCN- and ClO4- added outside the vesicles. 3) When P-vesicles were loaded with SCN- instead of I- and incubated in Na+, I- uptake by these vesicles was also higher than baseline Na+-dependent I- uptake. However, a ClO4- load did not result in an increase in I- uptake. These results indicate that Na+-dependent I- transport including Na+-dependent I- counterflow is specifically mediated by the thyroid I- carrier. SCN- - I- counterflow in addition to I- - I- counterflow occurs dependently on Na+, but ClO4- - I- counterflow does not.     

Antithrombotic effect of topically applied 3-Oxa-Methano-prostaglandin I1 in the microcirculation and antiplatelet functions of its active form

The antithrombotic effect of topical application of the 3-oxamethano-prostaglandin (PG) I₁ analog, SM-10902 in the microcirculation and in vitro antiplatelet functions of its active form SM-10906 were estimated in comparison with PGI₂ and PGE₁. In rat platelets, SM-10906 evoked accumulation of intracellular cyclic adenosine 3′,5′-monophosphate, and exhibited antiaggregatory and disaggregatory activities, which were all enhanced by the phosphodiesterase inhibitor theophylline. Additionally, SM-10906 was shown to inhibit platelet adhesion to collagen in human platelet-rich plasma. PGI₂ and PGE₁ also showed in vitro antiplatelet effects in the order of PGI₂ > SM-10906 ≥ PGE₁. SM-10902 exhibited a dose-dependent antithrombotic effect in the guinea pig mesenteric arteriole by a topical application, and this activity might be exerted by the antiplatelet functions of SM-10906. Although SM-10906, PGI₂ and PGE₁ also showed the antithrombotic effects, SM-10902 was the most potent. In conclusion, the present studies indicate that an external topical preparation of SM-10902 may be useful for the therapy of peripheral circulatory insufficiency.     

Freemartinism among singleton bovine females born from multiple embryo transfer

Heterosexual chimerism among singleton females produced by multiple nonsexed embryo transfer (MNET singleton females) was investigated using chromosome typing and PCR (polymerase chain reaction)-amplification of male-specific DNA (msDNA). Of the 22 animals tested, 21 were classified as normal by both methods (i.e., showing no male cells among 100 metaphase spreads in chromosome typing and being msDNA negative in PCR). No morphological abnormalities of the genital organs were observed among 19 MNET single females. One MNET singleton female was, however, classified as a freemartin by PCR (male-specific DNA positive), but it was classified as normal cytogenetically. This individual probably had a low degree of heterosexual chimerism, and it seems that the chimerism derived from MNET was difficult to diagnose by chromosome typing, although it was detectable by PCR. The genital organs of this individual (15-mo-old Aberdeen Angus) were normal in form (both external and internal) and size. However, a very small structure, resembling seminiferous tubule, was found in the left ovary. It may be concluded that most MNET singleton females are expected to have normal reproductive function.