Long-term iodination of thyroglobulin by porcine thyroid cells cultured in porous-bottomed culture chambers: regulation by thyrotrophin

Thyroid cells cultured as monolayers on the porous bottom of culture chambers have been shown to express some specific functions of thyroid follicles. This system, which allows independent access to apical and basal media, is suitable for the long-term study of polarized processes, as the cells maintain their polarized organization. Iodination of thyroglobulin has been investigated under different culture conditions in the presence or absence of TSH. Apical thyroglobulin accumulation, apical iodide concentration and thyroglobulin iodination have been followed simultaneously. Iodide (0.5 mumol/l) was added to basal medium at various stages: only once for 4-day incubations and at each medium change or daily for longer experiments. TSH increased the amount of thyroglobulin secreted into the apical medium by five- to sixfold, whereas high basal iodide concentrations (greater than 5 mumol/l) inhibited thyroglobulin secretion by TSH-stimulated cells. TSH increased iodide uptake giving an iodide concentration ratio between apical and basal media of about 5. Thyroglobulin iodination was dependent upon TSH. Thyroglobulin was iodinated only in the apical compartment. Secretion and iodination of thyroglobulin were polarized phenomena, but the polarity of iodination was total whereas the polarity of secretion was only partial (10% basal secretion). This functional asymmetry was maintained for up to 29 days. The maximal incorporation of iodine into thyroglobulin obtained was never higher than 3.5 atoms/mol. Apical iodide concentrations from 1 to 15 mumol/l, depending on culture conditions, did not increase this value. These results suggest that cells cultured in this culture system are able to reproduce several steps of thyroidal iodide metabolism although there may be unknown factors which could interfere and reduce the efficiency of thyroglobulin iodination.     

Thyroid hormone synthesis in thyroglobulin secreted by porcine thyroid cells cultured on porous bottom chambers. Effect of iodide.

The long-term iodination of thyroglobulin secreted into the apical medium of thyroid cells cultured as monolayers on porous bottom chambers reached 5.87 +/- 1.66 atoms of iodine/mol thyroglobulin after 11 days incubation in the presence of TSH (0.1 mU/ml) and iodide (0.5 microM) in the basal medium. This iodinated thyroglobulin contained thyroid hormones (T3 + T4) which involved 22.7% of the thyroglobulin iodine content. The iodoamino acid content was, in residues per mole, 2.2 +/- 0.35 for monoiodotyrosine, 0.74 +/- 0.04 for diiodotyrosine, 0.23 +/- 0.04 for T4, and 0.098 +/- 0.02 for T3. Kinetic studies showed that a minimal level of iodination (2.05 +/- 0.26 atoms iodine/mol thyroglobulin) was necessary for hormonogenesis. A maximal level of iodination and hormonogenesis was obtained with 0.5 microM iodide added daily to the basal medium. In these conditions, hormonogenesis efficiency reached about 40% (a value close to this one observed in vivo). Above 0.5 microM iodide, both iodination and T4 synthesis were inhibited (28.3% and 73.9%, respectively, for 1 microM iodide). Our culture system makes it possible to demonstrate that this high iodide concentration in the basal medium did not increase apical iodide concentration above 10 microM but decreased apical thyroglobulin concentration. The inhibitory effect of iodide on hormonogenesis cannot be due to a competition with tyrosine residues of thyroglobulin for their binding to thyroperoxidase although it could be related, at least in part, to a decrease in protein synthesis.     

Estrogenic activity of phenol red

It has recently been reported that phenol red, a pH indicator present in most tissue culture media, is a weak estrogen that can stimulate some estrogen-sensitive cells. However, the relative impact of phenol red on various cell lines is controversial. We examined the effect of phenol red on several estrogen-responsive cell systems that we use to study estrogen action. These included estrogenic stimulation of progesterone receptor and growth in human breast cancer-derived MCF-7 cells, stimulation of growth in human breast cancer-derived T47D cells, stimulation of prolactin synthesis in primary cultures of immature rat pituitary cells, and stimulation of progesterone receptor in primary cultures of immature rat uterine cells. Estrogenic responses in MCF-7 cells were the most sensitive to the presence of phenol red, while the other three cell cultures showed lesser effects of the indicator. In addition to intrinsic differences in cell responses, there were several other factors involved. These included differences in the estrogenic activity of phenol red-containing media and phenol red itself from different commercial suppliers, and differences in the concentration of free phenol red in final media due to binding of the indicator by serum. Higher concentrations of serum reduced the impact of phenol red on estrogenic responses in primary pituitary cells. Phenol red added to rat uterine cytosol competed with estradiol for binding to the estrogen receptor (relative binding affinity (RBA) approx. 0.001), and the acidic and basic forms of the indicator showed similar activity. Some commercial phenol red samples inhibited cell growth at levels of 100 mg/l; these effects were toxic rather than antiestrogenic, because growth inhibition could not be competitively reversed by an excess of estradiol. The amount of the indicator bound to serum in the final media, the source of the phenol red and the sensitivity of different cell types to the indicator ultimately determine its influence to the response of cells in tissue culture.     

Weak estrogenic activity of phenol red in the culture medium: its role in the study of the regulation of prolactin release in vitro

Phenol red, which is commonly used in culture media as a pH indicator, has recently been shown to possess estrogenic properties. In this study we investigated the effects of phenol red on prolactin release and synthesis by cultured female and male rat anterior pituitary cells and on the sensitivity of these cells of dopamine, TRH and somatostatin (SRIF). It was shown that phenol red stimulated rat prolactin release and cell content in a dose-dependent manner. The effects of 30 microM phenol red, which is the medium concentration in our regular culture medium, and a submaximally active concentration of 17 beta-estradiol (E2) were additive. Male rat pituitary cells were far more responsive to phenol red and also to E2 than female pituitary cells. The antiestrogen tamoxifen (100 nM) significantly inhibited the phenol red-stimulated prolactin release by male rat pituitary cells but caused a 2-fold increase of prolactin release in the absence of phenol red. 30 microM phenol red did not modulate the responsiveness of female and male rat lactotrophs to dopamine, TRH or SRIF. We propose from our results that the estrogenic effect of 30 microM phenol red is too weak in order to alter the responsiveness of rat lactotrophs to dopamine, TRH and SRIF but the presence of phenol red in culture media should be considered when the effects of estrogens and antiestrogens on rat prolactin release and synthesis in vitro are studied.     

Thyrotrophin regulation of apical and basal exocytosis of thyroglobulin by porcine thyroid monolayers

Exocytosis, the ultimate step in thyroglobulin secretion, has been studied in porcine thyroid cells cultured in monolayers on the permeable bottom of culture chambers. We have previously demonstrated, using this culture system, that apical secretion accounts for 85-95% of total secretion of newly synthesized thyroglobulin. When cells were cultured for several days with bovine TSH (25 microU/ml) in the basal medium, the rate of glycoprotein accumulation in the upper compartment was three times higher than that in the absence of TSH. In contrast, the rate of thyroglobulin released into the basal medium (5-15% of total secreted thyroglobulin) appeared unmodified by chronic TSH stimulation. To investigate the effect of acute TSH stimulation on thyroglobulin exocytosis in the apical and basal compartments, pulse-chase experiments were carried out with the same culture system. The release of radiolabelled thyroglobulin (1.5-h pulse) into the apical medium was increased threefold during the 2-h chase period under TSH stimulation. The radiolabelled thyroglobulin released into the basal medium was increased only 1.5- to 2-fold, and stimulation disappeared after 1 h. The effect of TSH was maximal when the chase medium contained 50 microU TSH/ml. However, cells cultured for several days in the presence of 25 microU TSH/ml before the pulse-chase experiment, appeared desensitized to acute TSH stimulation. Similar responses were observed when the chase medium contained 8-chloro-cyclic AMP or cholera toxin. This study provides another example of the pleiotropic effect of TSH, mediated by cyclic AMP, on the sequential steps of thyroglobulin gene expression in cultured thyroid cells in which the polar character of the epithelial cells is well preserved.     

Phenol red in tissue culture media is a weak estrogen: implications concerning the study of estrogen-responsive cells in culture.

Although much attention has been paid to the removal of hormones from sera and to the development of serum-free media for studies on hormone-responsive cells in culture, little consideration has been given to the possibility that the media components themselves may have hormonal activity. We have found that phenol red, which bears a structural resemblance to some nonsteroidal estrogens and which is used ubiquitously as a pH indicator in tissue culture media, has significant estrogenic activity at the concentrations (15-45 microM) at which it is found in tissue culture media. Phenol red binds to the estrogen receptor of MCF-7 human breast cancer cells with an affinity 0.001% that of estradiol (Kd = 2 X 10(-5) M). It stimulates the proliferation of estrogen receptor-positive MCF-7 breast cancer cells in a dose-dependent manner but has no effect on the growth of estrogen receptor-negative MDA-MB-231 breast cancer cells. At the concentrations present in tissue culture media, phenol red causes partial estrogenic stimulation, increasing cell number to 200% and progesterone receptor content to 300% of that found for cells grown in phenol red-free media, thereby reducing the degree to which exogenous estrogen is able to stimulate responses. The antiestrogens tamoxifen and hydroxytamoxifen inhibit cell proliferation below the control level only when cells are grown in the presence of phenol red; in the absence of phenol red, the antiestrogens do not suppress growth. The estrogenic activity of phenol red should be considered in any studies that utilize estrogen-responsive cells in culture.     

Transcellular iodide transport and iodination on the apical plasma membrane by monolayer porcine thyroid cells cultured on collagen-coated filters

Isolated porcine thyroid follicular cells were cultured on a collagen-coated Millipore filter to form a monolayer. The monolayer could translocate 125I added in the medium beneath the filter (basal medium) into the medium above the monolayer (apical medium) and form an iodide concentration gradient of several-fold. Transcellular iodide pump activity was observed when the cells were cultured with TSH in the basal medium. In the absence of TSH, the translocation of iodide was very slow. The concentration of TSH required to activate the iodide pump was 0.1-0.3 mU/ml. Addition of ClO4- to the basal medium inhibited transcellular transport, whilst addition of ClO4- to the apical medium was much less effective. Constituents labelled with 125I in the apical medium were analysed. The amount of protein-bound 125I measured by acid precipitation was 3-8% of the total radioactivity. The residual radioactivity was found to be iodide ion by paper chromatography. Further analysis by sodium dodecylsulphate-polyacrylamide gel electrophoresis revealed that most of the 125I-labelled protein was at the position of bovine serum albumin which had been added to the culture medium. The monolayer culture of cells on collagen-coated filter would be a useful experimental system for analysing thyroid cell functions for which the cell polarity is essential.     

Accelerated exocytosis and H2O2 generation in isolated thyroid follicles enhance protein iodination

Open pig thyroid follicles in which the apical surface of the follicle cells is in direct contact with the incubation medium were used to study the effect of stimulated exocytosis and stimulated H2O2 generation on the iodination of protein in the incubation medium. In previous studies on this system of follicles we have shown (1) that the apical surface of the follicle cells is a major site of protein iodination and (2), that H2O2 is produced at the apical cell surface. In the present study we confirmed the previous finding that H2O2 generation is greatly stimulated by the Ca2+ ionophore A23187. We further found that TSH at a high concentration (greater than 10 mU/ml) and in the presence of Ca2+ stimulated H2O2 generation; TSH had no such effect on follicles incubated in Ca2+-free medium after pretreatment with EGTA. Forskolin did not stimulate H2O2 generation. Exocytosis of thyroglobulin was stimulated by TSH at a low concentration (0.1 mU/ml), and this stimulation was not dependent on Ca2+. Exocytosis was also stimulated by forskolin but not by A23187. Iodination of protein, including thyroglobulin, in the incubation medium was stimulated by A23187, TSH and forskolin. These observations suggest that stimulation of iodination in association with the apical surface of the follicle cells can be achieved separately by an increased rate of H2O2 generation and increased rate of exocytosis. Generation of H2O2 is Ca2+-dependent, whereas exocytosis is mediated by the adenylate cyclase-cAMP system; TSH at a high concentration can stimulate both these processes.     

Proceedings: In vitro thyroid hormone formation (author's transl)]

Iodination of a non halogenated goiter thyroglobulin and the resulting thyroxinogenesis was studied in vitro with purified thyroid peroxidase, H2O2 generating system and various concentrations of iodide. The rate of iodination was linear during the first minutes of incubation but thyroxine synthesis only began after a lag period whatever the iodide concentration in the incubation medium was. With high iodide concentrations a highly iodinated thyroglobulin (40-50 iodine atoms) containing no thyroxine was obtained after 3 minutes of incubation. If this highly iodinated goiter thyroglobulin was purified and reincubated with peroxidase and H2O2, thyroxine synthesis was again observed only after a lag period (2-3 min). In the absence of iodide the enzyme to elicit thyroxine synthesis. Depending of its concentration free diiodotyrosine exerts two opposite effects on the reaction catalyzed by thyroid peroxidase : at high concentration (10(-4) M) in inhibition of thyroglobulin iodination, and at low concentration (10(-7), 10(-8) M) a stimulating effect on thyroid hormones biosynthesis.     

Site of iodination in the rat thyroid gland deduced from electron microscopic autoradiographs.

The site of iodination of protein in the thyroid gland (whether intracellular or intraluminal) was ascertained by autoradiographic studies using iodide-125I. In tissue fixed within about 40 sec after intravenous injection of radioiodide the silver grains of autoradiographs were concentrated over the follicular lumen generally as a ring of grains close to the apical border of the follicular cells. The zone of grains was sharply limited toward the cells. No concentration of silver grains was detected associated with any intracellular organelle. The autoradiographic ring which had a minimum width of about 2 mum was continuous along the apical plasma membrane of the follicle cells but there was a drastic reduction in grain density along the plasma membrane of the distal portion of pseudopods. Tissue was fixed so soon after radioiodide injection that it appeared likely that a negligible fraction of radioiodoprotein, if formed in the cell, could have been transferred to the lumen. The observations strongly indicate that the iodination of thyroglobulin occurs in the follicle lumen, probably at the apical surface of the follicle cells. Since in the TSH-treated animals the distribution of the labeling along the apical plasma membrane agrees well with the reported histochemical distribution of thyroperoxidase in this membrane, it is further concluded that iodination may well be catalyzed by peroxidase in the apical plasma membrane.     

Iodination of thyroglobulin molecules depends on their diffusion velocity in follicular colloid

We have studied in vitro the effects of altered physicochemical properties of thyroglobulin molecules in solution and of the solution itself on iodination kinetics and hormone synthesis. Any change in hydrodynamic properties had a far greater effect in compartmentalized systems, obtained by coating the test tubes with peroxidase, than in conventional homogeneously mixed systems. Increasing thyroglobulin concentration in a range still far below that existing in vivo greatly retarded iodination and hormone synthesis. In contrast, a number of physiological and non-physiological changes of thyroglobulin structure, such as desialylation, preiodination, oxidation and denaturation, strikingly accelerated iodination. The highly variable physical-chemical state of thyroglobulin molecules appears to be a main determinant of protein diffusion within the colloid and, thereby, of iodination kinetics and rate of hormone synthesis. Moreover, alterations of the physicochemical state of thyroglobulin molecules may explain some hitherto ill-understood diffusion phenomena in live follicles.     

Localization of iodine binding in the thyroid gland in vitro

Protein-bound radioiodine was localized by electron microscopic autoradiography in follicles and cells isolated from pig and rat thyroid tissue after incubation with 125I- for 1-10 min. Labeled proteins were analyzed by gel electrophoresis and immunoprecipitation. In closed follicles, with colloid-filled follicle lumina, the autoradiographic labeling was concentrated over the lumina and no labeling occurred over the cells. In open follicles, without colloid content, autoradiographic grains were invariably found along the apical cell surface and in some cells over intracellular lumina. Isolated cells with preserved polarity showed some labeling associated with remaining microvilli whereas isolated cells with lost polarity showed no grains at the cell surface. In isolated cells, particularly those with lost polarity, most grains were located over intracellular lumina (which were common in such cells) and some grains over vesicular elements associated with these lumina. About 80% of the labeled soluble proteins and 40% of the labeled proteins solubilized by sodium dodecyl sulfate were thyroglobulin. It is concluded that the site of iodination in follicles is the same in vitro as in vivo, viz. the apical surface of the follicle cells. When thyroid cells are removed from the follicle and lose their polarity, intracellular lumina become the major site of iodination. This shift in iodination sites is thought to be due to retention of Golgi-derived secretory vesicles in nonpolarized cells, leading to coalescence of vesicles with the formation of intracellular lumina and activation of membrane-bound enzymes catalyzing iodination.     

Effect of cryopreservation of thyroid parenchyma on iodoamino acid composition of thyroglobulin and its iodination

The content and distribution of iodoamino acids in thyroglobulin of the cryopreserved thyrotoxically-changed thyroid parenchyma were studied, as was thyroglobulin iodination. Thyroid tissue obtained during operations of patients with diffuse-toxic goiter was investigated. The thyroid parenchyma was cryopreserved according to the method developed at the Institute of Cryobiology and Cryomedicine Problems, Academy of Sciences of the Ukrainian SSR. The tissues were stored for 4-6 months. Thyroglobulin was isolated by gel filtration of the thyroid saline extract through a column packed with Sephadex G-200. Thyroglobulin was iodinated with KI + I2 water solution, pH 9.2, at 37 C for 30 min. The amount of iodine added was 100 moles of I2 per protein mole. Protein concentration was determined by the biuret reaction. Thyroglobulin iodoamino acid composition was determined by direct spectrophotometry. Absorption spectra were measured by an EPS-3T recording spectrophotometer ("Hitachi", Japan). The processes of freezing (-196 degrees C) and thawing of the thyroid parenchyma were shown to induce no changes in the thyroglobulin iodoamino acid composition. Cryopreservation of the thyroid parenchyma considerably affected iodine incorporation and formation of iodoamino acids in the thyroglobulin during its in vitro iodination. It may be supposed that cryopreservation of the thyroid tissue affects the thyroglobulin conformational status, that results in increased iodination of this iodoprotein.     

Effect of vasoactive intestinal peptide on monkey prolactin secretion and cyclic AMP in culture: interaction with estradiol and phenol red

To test the hypothesis that estrogenic compounds may decrease the sensitivity of primate lactotropes to adenylate cyclase-mediated secretagogues, the effect of VIP on prolactin secretion and cAMP levels in serum-free monkey pituitary monolayer cultures was examined in the presence and absence of estradiol (E) and phenol red. In two experimental designs, E treatment was initiated on either the day after dispersion (split plate design) or 10 days after serum-free culture (whole plate design). VIP challenges (5, 50 and 500 nM) were administered for 4 h on days 10 and 20 of culture. There was a significant decrease in the maximal percent stimulation of prolactin by VIP when cultures were treated with E or phenol red. The average percent increase in prolactin at 5, 50 and 500 nM VIP equalled 23, 83 and 156% in the absence of phenol red, but equalled 14, 43 and 112% when E was added to phenol red-free cultures. The percent stimulation by VIP in the presence of phenol red averaged 32, 62 and 97%, but addition of E with phenol red decreased the average stimulation to 26, 45 and 72%, respectively. Basal levels of cAMP were increased by E and phenol red. However, the maximal percent stimulation of cAMP by VIP was decreased in the presence of E and phenol red. In summary, E and phenol red act to decrease the maximal percent stimulation of prolactin secretion by VIP. This effect is reflected by a decrease in the maximal percent stimulation of intracellular cAMP.     

Taurocholate transport by hepatic and intestinal bile acid transporters is independent of FIC1 overexpression in Madin-Darby canine kidney cells

BACKGROUND: Mutations in the human familial intrahepatic cholestasis gene, FIC1, result in progressive familial intrahepatic cholestasis type 1 in children and benign recurrent intrahepatic cholestasis. The present study was performed to determine whether FIC1 transports bile acids and/or influences the activity of apical bile acid transporters. METHODS: The apical secretion assay utilized transfected Madin-Darby canine kidney (MDCK) cells, which stably express the bile acid uptake protein, Na+/taurocholate co-transporting polypeptide (NTCP). These cells were then transiently transfected with FIC1 and/or the bile salt export pump (BSEP) and were grown on Transwell filters to form a polarized monolayer. [(3)H]Taurocholate was added to the basal medium and the taurocholate secretion was measured in the apical medium. A second assay, apical uptake assays, utilized polarized MDCK-II cells, which were transiently transfected with FIC1, FIC1 mutants and/or the apical sodium-dependent bile acid transporter (ASBT). [(3)H]Taurocholate was added to the apical media and intracellular uptake of taurocholate was measured. RESULTS: Apical secretion assays: FIC1 expression in MDCK/NTCP cells had no effect on taurocholate secretion compared to controls. In contrast, apical secretion of taurocholate in BSEP-transfected cells was approximately twofold higher than in non-transfected MDCK/NTCP cells (P < 0.01). The BSEP-mediated secretion was unaffected by co-transfection with FIC1. Apical uptake assays: taurocholate uptake in ASBT expressing cells was 6.5-fold higher than in controls and was unaffected by co-transfection of cells with FIC1 or FIC1 mutants. CONCLUSIONS: These results indicate that FIC1 does not transport taurocholate and, when overexpressed in MDCK cells, had no effect on the function of BSEP or ABST.     

Iodide handling by the thyroid epithelial cell.

Iodination of thyroglobulin, the key event in the synthesis of thyroid hormone, is an extracellular process that takes place inside the thyroid follicles at the apical membrane surface that faces the follicular lumen. The supply of iodide involves two steps of TSH-regulated transport, basolateral uptake and apical efflux, that imprint the polarized phenotype of the thyroid cell. Iodide uptake is generated by the sodium/iodide symporter present in the basolateral plasma membrane. A candidate for the apical iodide-permeating mechanism is pendrin, a chloride/iodide transporting protein recently identified in the apical membrane. In physiological conditions, transepithelial iodide transport occurs without intracellular iodination, despite the presence of large amounts of thyroglobulin and thyroperoxidase inside the cells. The reason is that hydrogen peroxide, serving as electron acceptor in iodide-protein binding and normally produced at the apical cell surface, is rapidly degraded by cytosolic glutathione peroxidase once it enters the cells. Iodinated thyroglobulin in the lumen stores not only thyroid hormone but iodine incorporated in iodotyrosine residues as well. After endocytic uptake and degradation of thyroglobulin, intracellular deiodination provides a mechanism for recycling of iodide to participate in the synthesis of new thyroid hormone at the apical cell surface.     

急性肺损伤血栓素A2受体、受体mRNA的变化及拮抗剂酚红对它们的影响

目的研究急性肺损伤（ＡＬＩ）肺组织特异性膜受体（ＴＸＡ２Ｒ）的变化及受体拮抗剂酚红对它们的影响，从分子水平阐明血栓素Ａ２（ＴＸＡ２）在ＡＬＩ中的作用机制。方法采用大鼠油酸肺损伤模型，分析伤后６小时肺组织ＴＸＡ２Ｒ、ＴＸＡ２ＲｍＲＮＡ表达的变化以及酚红（５０ｍｇ／ｋｇ、５ｍｇ／ｋｇ）对它们的影响。结果油酸肺损伤后肺组织ＴＸＡ２Ｒ结合容量明显“降低”，其ｍＲＮＡ的转录显著升高。酚红的应用使ＴＸＡ２Ｒ结合容量明显“降低”，并能抑制油酸肺损伤ＴＸＡ２ＲｍＲＮＡ转录的增高。酚红能显著降低肺体指数（ＬＢＩ）、肺含水率（ＲＬＷ），改善动脉血氧分压（ＰａＯ２），减轻肺组织损伤程度。结论ＴＸＡ２在ＡＬＩ的病理过程中具有重要作用。体内试验证明酚红能有效地调节ＴＸＡ２Ｒ及其ｍＲＮＡ的表达并对ＡＬＩ的发生有防护作用     

Peroxidase activity and thyroglobulin iodination activity of thyroid peroxidase in non-functioning thyroid tumours

Both lesion (L) and adjacent normal (N) thyroid tissue from 48 patients with non-functioning adenomas and adenomatous goitres were assayed for peroxidase activity by the 'mini' assay method employing guaiacol or iodide as the second substrate. A considerable proportion of thyroids (46% of adenomas and 22% of adenomatous goitres) demonstrated no iodide oxidation activity in L although they had guaiacol oxidation activity, and these were grouped as subgroups A. The rest of these non-functioning tumours, termed subgroups B, had both guaiacol and iodide oxidation activity which was higher (3.0-4.6 times in guaiacol assay and 7.3-14.1 times in iodide assay) in L than in N. These data indicate that the non-functioning in subgroups A may be due to a lack of iodide oxidation activity and that some other defects such as an iodide transport defect may be involved in subgroups B. Furthermore, a precise and rapid assay method for thyroglobulin iodination activity of thyroid peroxidase was developed, with modifications of previous methods. On the basis of this method, we found that there is a good correlation (r = 0.94) between iodide oxidation assay and thyroglobulin iodination assay, leading to the conclusion that thyroglobulin iodination assay can be replaced by iodide oxidation assay.     

急性肺损伤血栓素A2受体,受体mRNA的变化及拮抗剂酚红对它？…

目的 研究急性肺损伤（ＡＬＩ）肺组织特异性膜受体（ＴＸＡ２Ｒ）的变化及受体拮抗剂酚红对它们的影响，从分子水平阐明血栓素Ａ２（ＴＸＡ２）在ＡＬＩ中的作用机制。方法 采用大鼠油酸肺损伤模型，分析后６小时肺组织ＴＸＡ２Ｒ、ＴＸＡ２ＲｍＲＮＡ表达的变化以及酚红（５０ｍｇ／ｋｇ、５ｍｇ／ｋｇ）对它们的影响。结果 油酸肺损伤后肺组织ＴＸＡ２Ｒ结合容量明显“降低”，其ｍＲＮＡ的转录显升高。酚红的应用使ＴＸＡ２     

Phenol Congo red staining enhances the diagnostic value of abdominal fat aspiration biopsy in reactive AA amyloidosis secondary to rheumatoid arthritis

OBJECTIVE: Systemic reactive AA amyloidosis is an intractable complication in patients with a long history of rheumatoid arthritis (RA). To help to more easily and reliably detect the presence of this form of amyloidosis in patients with RA and start intensive treatment as early as possible, we examined the sensitivity and usefulness of abdominal fat aspiration biopsy with phenol Congo red staining in the diagnosis of AA amyloidosis. PATIENTS AND METHODS: Ten patients were diagnosed with systemic reactive AA amyloidosis secondary to RA (all women; mean age, 70.2 +/- 6.4 years; mean disease duration of RA, 20.3 +/- 11.2 years) based on histopathological examinations of biopsied specimens mainly from the gastroduodenal mucosa. Abdominal fat aspiration biopsy was performed in these patients, and the specimens were treated with both classical alkaline and phenol Congo red staining. RESULTS: Phenol Congo red staining revealed amyloid deposits in all 10 patients, while conventional alkaline Congo red staining showed a positive result in 7 patients. In the patients with a positive result with alkaline Congo red staining, reactivity of one grade or two higher was demonstrated by the phenol Congo red method. CONCLUSION: Phenol Congo red staining is superior to the classical alkaline Congo red staining with respect to the detection of AA-amyloid deposits in biopsied abdominal fat tissue specimens. In addition to easy access and procedural safety, abdominal fat aspiration biopsy might contribute reliably to the diagnosis of systemic reactive AA amyloidosis secondary to RA when phenol Congo red staining is employed.