The type 3 iodothyronine selenodeiodinase (D3) is an integral membrane protein that inactivates thyroid hormones. By using immunofluorescence cytochemistry confocal microscopy of live or fixed cells transiently expressing FLAG-tagged human D3 or monkey hepatocarcinoma cells expressing endogenous D3, we identified D3 in the plasma membrane. It co-localizes with Na,K-ATPase ␣, with the early endosomal marker EEA-1 and clathrin, but not with two endoplasmic reticulum resident proteins. Most of the D3 molecule is extracellular and can be biotinylated with a cell-impermeant probe. There is constant internalization of D3 that is blocked by sucrose or methyl-␤-cyclodextrin-containing medium. Exposing cells to a weak base such as primaquine increases the pool of internalized D3, suggesting that D3 is recycled between plasma membrane and early endosomes. Such recycling could account for the much longer half-life of D3 (12 h) than the thyroxine activating members of the selenodeiodinase family, type 1 (D1; 8 h) or type 2 (D2; 2 h) deiodinase. The extracellular location of D3 gives ready access to circulating thyroid hormones, explaining its capacity for rapid inactivation of circulating thyroxine and triiodothyronine in patients with hemangiomas and its blockade of the access of maternal thyroid hormones to the human fetus.Thyroid tissue is confined to and is present in all vertebrates. Its role is to synthesize and secrete polyiodinated thyronine molecules that modulate gene expression in virtually every vertebrate tissue through ligand-dependent transcription factors. Thyroxine (T 4 ) 1 is the primary product of thyroid secretion, a pro-hormone that must be activated by deiodination to 3,5,3Ј-triiodothyronine (T 3 ) by either type 1 or 2 iodothyronine deiodinases (D1 or D2) in order to initiate thyroid action. To balance the activation pathway, both T 4 and T 3 are irreversibly inactivated by monodeiodination of the tyrosyl ring of the iodothyronines, a reaction catalyzed by the type 3 iodothyronine deiodinase (D3). These three enzymes constitute a family of selenocysteine (Sec)-containing integral membrane oxidoreductases (1).Changes in the activity of D3 modulate both global and local tissue thyroid status. In the global sense, D3 expression is increased by T 3 and reduced in hypothyroidism or iodine deficiency, thus accelerating or retarding T 3 inactivation to maintain homeostasis (2-4) or to alter plasma T 3 concentrations such as occurs during tadpole metamorphosis or during fetal life (5-7). More complex are the alterations in D3 activity in specific tissues dictated by developmental programs that permit precisely timed changes in their differentiation. For example, during metamorphosis in Xenopus laevis tadpoles, the eyes must shift from a lateral to a more rostral and dorsal location to permit overlapping visual fields. Retinal cells follow this shift with an asymmetrical growth, a process that is thyroid hormone-dependent. To develop asymmetrically, however, a subset of dorsal cells must grow at a slower rate....

Northern blot analysis showed that the increases in cytokine-and NO secretion were due to an increase in cytokine mRNAs or NO synthase mRNA. Therefore, it is concluded that Agaricus blazei Murill components which activate macrophages result in the induction of cytokine-and NO secretion in vitro.

When macrophages were cultured with lactoferrin, cytokines such as tumor necrosis factor (TNF‐α), interleukin 8 (IL‐8) and nitric oxide (NO) were secreted. Secretion of TNF‐α peaked at 6 h of incubation in the presence of lactoferrin and then declined. About 80% of the maximum secretion of IL‐8 was observed at 6 h of incubation. The concentration of IL‐8 in the culture medium remained almost constant between 24‐72 h. In contrast, no siginificant effect on NO secretion was observed at 6 h, but a significant effect was observed at 24 h and secretion gradually increased between 24‐72 h. The effects of lactoferrin on the secretion of TNF‐α, IL‐8 and NO were dose‐dependent and lactoferrin had a significant effect on secretion at concentrations greater than 10 mg/ml. The use of reverse transcription‐polymerase chain reaction (RT‐PCR) showed that the results obtained were consistant with the cytokine secretion results. It is concluded that lactoferrin activates macrophages which result in the secretion of TNF‐α, IL‐8 and NO.

Anti-viral activities of Agaricus blazei Murill were investigated. The water extracts of the cultured mycelia and fruiting bodies were fractionated with different concentrations of ethanol. To several viruses which have cytopathic effects (CPE) on VERO cells, inhibition of these effects by the ethanol fractions was tested. Strong inhibition of CPE induced by western equine encephalitis (WEE) virus was observed in the mycelial fractions but not those of fruiting bodies.