Variant thyroxine-binding globulin in serum of Australian aborigines: a comparison with familial TBG deficiency in Caucasians and American blacks

About 40% of clinically euthyroid Australian Aborigines have low concentrations of total thyroxine (TT4) and triiodothyronine (TT3) in serum. While the finding of normal concentrations of serum thyrotropin (TSH) in such individuals is compatible with their eumetabolic state, the reason for the finding of a low free T4 index (FT4I) has been unclear. A genetic variant of T4-binding globulin (TBG) with reduced affinity for T4 has been suggested but decrease in the absolute concentration of TBG has also been reported. In this study, we measured various parameters of thyroid function in 20 serum samples from euthyroid Australian Aborigines selected for their low TT4 levels. Results were compared to those obtained in serum samples from Caucasians and American Blacks with inherited partial TBG deficiency, 15 of which were matched to the Aborigines by their TBG and 20 by their TT4 concentrations. Results were also compared with those from another group of 20 samples from Caucasians and American Blacks with normal TBG concentration, matched to the Aborigines by their serum TT4 concentration. TBG in serum from these Australian Aborigines was immunologically identical to that in Caucasians and American Blacks in terms of parallelism of serially diluted samples in the TBG radioimmunoassay (RIA).(ABSTRACT TRUNCATED AT 250 WORDS)     

Interaction between elastin and tumor cell lines with different metastatic potential; in vitro and in vivo studies

Summary Interactions between the extracellular matrix macromolecules and tumor cells are critical in the process of metastasis formation. We show here that elastins (both mature insoluble elastin and a 75-kDa soluble peptide: -elastin) adhere rapidly to two cell lines with high metastatic capacities: a metastatic lung carcinoma cell line (3LL-HM) and a human amelanotic melanoma cell line (A-2058); by contrast the low-metastatic Lewis lung carcinoma cell line variant as well as a rhabdomyosarcoma cell line with a low metastatic potential bind to elastins to a much lower extent.³H-labelled -elastin was used in order to study elastin-3LL-HM interaction. It was found to be saturable (2 ng³H-labelled -elastin/10⁶ cells), with one class of high-affinity binding sites having K_d equal to 1.3 nM and 16000 sites/cell. The binding of -elastin to 3LL-HM cells at its receptor triggered several cell responses; (a) increase of intracellular Ca²⁺ concentration; (b) induction of 3LL-HM chemotaxis toward the -elastin gradient; (c) stimulation of the adherence of mature insoluble elastin. In contrast to non-transformed cells such as fibroblasts and smooth muscle cells, the adhesion kinetics of insoluble elastin to 3LL-HM did not exhibit a lag period; the rapid binding of insoluble elastin to the tumor cells was followed by its slow detachment from the cells, which lasted for 6 h. 3LL-HM cells but not human skin fibroblasts were shown to secrete elastinolytic activity inhibitable by metal-chelating agents.In vivo studies were performed in order to evaluate the influence of -elastin binding to 3LL-HM cells on their ability to form lung colonies in mice. It was shown that pretreatment of 10⁴ 3LL-HM cells with 10 M kelastin and the simultaneous i.v. injection into mice of 750 g -elastin together with the highly metastatic cells was able to reduce the number of lung colonies by more than 70% after 12 days.Abbreviations 3LL-HM, 3LL-LM highly metastatic and low-metastatic Lewis lung carcinoma cells     

Dual sites of inhibition by metyrapone of human adrenal steroidogenesis: correlation of in vivo and in vitro studies.

In a patient with pituitary ACTH-dependent adrenal hyperplasia (AH), the standard oral metyrapone test resulted in a decrease in "apparent 11beta-hydroxylase activity" (-48%) accompanied by an increase in "apparent cholesterol cleavage activity" (+318%). When incubated adrenal mitochondria from this patient were studied, metyrapone inhibited both 11beta-hydroxylation of labeled 11-deoxycorticosterone and cleavage of labeled cholesterol, although at 0.1 and 1.0 mM metyrapone concentrations, depression of cholesterol cleavage (23 and 54%, respectively) was less than that of 11beta-hydroxylation (62 and 84%, respectively). The inhibition of cholesterol cleavage by metyrapone (26 and 62%, at 0.1 and 1.0 mM concentrations, respectively) was also demonstrable in adrenal mitochondria from a patient with hypercorticism resulting from an ACTH-independent adrenal adenoman (AA). Metyrapone administration to AA resulted in a significant depression of both 11beta-hydroxylase (-62%) and cholesterol cleavage (-36%) "apparent activities"; when metyrapone and ACTH were given together to this patient, however, only 11beta-hydroxylase "apparent activity" diminished (-26%), while cholesterol cleavage "apparent activity" was greatly augmented (+231%), thereby simulating the results of the standard metyrapone test in AH. These data demonstrate that metyrapone inhibits both mitochondrial reactions involved in cortisol synthesis--initial cholesterol cleavage and final 11beta-hydroxylation; these effects probably result from interference by this agent with the interaction between substrate and related cytochrome P - 450. Since ACTH has a major stimulatory effect on cholesterol cleavage but not on 11beta-hydroxylation, the outcome of metyrapone administration is thus determined by whether a change in ACTH level ensues: while 11beta-hydroxylation is inhibited by metyrapone under any circumstances, total steroid output rises when a compensatory ACTH increase overcomes metyrapone inhibition of cholesterol conversion into pregnenolone and falls when metyrapone inhibition of this reaction is unopposed.     

DXA vs QCT: in vitro and in vivo studies

The aim of this study was to evaluate the discrepancy between bone mineral density (BMD) results when using dual X-ray absorptiometry and quantitative computed tomography both in vitro and in vivo. Using these two techniques, we found that the T-score densitometric index values were discrepant in the BMD qualitative evaluation, which can affect the diagnosis of osteopenia or osteoporosis, thus we propose its modification.     

Differential effects of leptin on ovarian metalloproteinases and their tissue inhibitors between in vivo and in vitro studies

In this study, we investigated the effect of leptin on the ovarian metalloproteinase system in the rat during the ovulatory process. Ovulation was induced in immature rats primed with gonadotropins. In both in vitro and in vivo experiments, we measured i) the protein expression of the ovarian metalloproteinases (matrix metalloproteinases, MMPs) and their tissue inhibitors (TIMPs) by western blot; ii) the gelatinase activity of the ovarian MMPs by zymography; and iii) the inhibitory action of TIMPs by reverse zymography. Using cultures of ovarian explants, leptin increased the activity but not the protein expression of MMP-2 and MMP-9 in both culture medium and ovarian tissue, and the protein expression of TIMPs, without a higher inhibitory action of the gelatinase activity. These results suggest either that the increase in TIMP proteins was not sufficient or that the inhibitory actions of TIMPs were impaired to suppress the MMP activity when the ovaries were directly exposed to leptin. To study the in vivo effect, rats received an acute treatment with high doses of leptin to inhibit ovulation. This treatment increased the expression of both the latent and the active forms of MMP-2 but did not result in a greater activity of MMP-2. In addition, the inhibitory action of TIMP-2 was also increased by this treatment. These results suggest that the administration of high doses of leptin could be regulating the follicle wall degradation, at least in part, by increasing the action of the ovarian TIMP-2 as a result of an extraovarian mechanism or signaling pathway.     

Mechanisms of platelet release: in vivo studies and in vitro modeling

Abstract

Mechanisms related to platelet release in the context of the bone marrow niche are not completely known. In this review we discuss what has been discovered about four critical aspects of this process: 1) the bone marrow niche organization, 2) the role of the extracellular matrix components, 3) the mechanisms by which megakaryocytes release platelets and 4) the novel approaches to mimic the bone marrow environment and produce platelets ex vivo.     

Hepatoprotective evaluation of Anogeissus latifolia： In vitro and in vivo studies

AIM： To evaluate the hepatoprotective activity of a hydroalcoholic extract of the bark of Anogeissus latifolia; in vitro in primary rat hepatocyte monolayer culture and in vivo in the liver of Wistar rats intoxicated by carbon tetrachloride （CCl4）. METHODS： In the in vitro study, a primary hepatocyte monolayer culture was treated with CCh and extract of Anogeissus latifolia. Hepatoprotective activity was demonstrated in the CCh damaged primary monolayer culture. In the in vivo study, the hepatoprotective activity of a hydroalcoholic extract ofAnogeissus latifolia was analyzed in liver injured CCh-treated rats. Biochemical parameters including serum transaminases [aspartate aminotransferase （AST） and alanine aminotransferase （ALT）] and alkaline phosphatase （ALP） in serum wereanalyzed. The biochemical findings were supplemented with histopathological examination of rat liver sections. RESULTS： In vitro： primary hepatocyte monolayer cultures were treated with CCh and extract of Anogeissus latifolia. A protective activity could be demonstrated in the CCh damaged primary monolayer cultUre. In vivo： Hydroalcoholic extract of Anogeissus latifolia （300 mg/kg） was found to have protective activity in rats with CCh-induced liver damage as judged from serum marker enzyme activity. CONCLUSION： The above findings lead to the conclusion that the hydroalcoholic extract of Anogeissus latifol/a is hepatoprotective. Hence, we suggest that the inclusion of this plant in the management of liver disorders is justified.