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Biomedical subjects

H Tang

Publications and source records attributed to H Tang.

At least 253 records · Page 14Linked to original sources
PubMed1993

The effects of a monoclonal antibody to interferon-gamma on experimental autoimmune thyroiditis (EAT): prevention of disease and decrease of EAT-specific T cells.

CBA/J mice immunized with thyroglobulin (Tg) develop an experimental autoimmune thyroiditis (EAT) with lymphocytic infiltration of the thyroid glands, autoantibodies to Tg and occurrence of EAT-specific T cells. When these mice were treated for 4 weeks after immunization with 1 mg/week of a monoclonal antibody (mAb) that neutralizes the activity of interferon-gamma (IFN) a beneficial effect on the onset of EAT was observed. Characteristic features of EAT were significantly reduced, including the lymphocytic infiltrations of the thyroid glands and the serum levels of autoantibodies to Tg. Moreover, in lymphoid organs, mAb to IFN-gamma significantly reduced the percentages of Tg-specific CD8+ cells, labeled by the anti-clonotypic mAb AG7. These Tg-specific T cells seem responsible for thyroid damages and disease development, since EAT was simultaneously abrogated. These results show that IFN-gamma plays an essential role in the pathophysiology of EAT and suggest the possibility to treat autoimmune thyroid diseases with mAb to IFN-gamma or drugs able to antagonize the production and/or the action of this cytokine.

Animals↗
PubMed1993

Differential induction of T cell cytokine mRNA in Epstein-Barr virus-transformed B cell clones: constitutive and inducible expression of interleukin-4 mRNA.

Clones of human B lymphocytes, obtained after immortalization with Epstein-Barr virus (EBV) of single CD19+ B cells and expansion in the absence of human T lymphocytes, produced mRNA for the T cell cytokines interleukin(IL)-2, IL-4, and interferon (IFN)-gamma. As detected by reverse transcriptase-polymerase chain reaction, IL-2 mRNA was expressed only after stimulation with the combination of phorbol 12-myristate 13-acetate (PMA) plus ionomycin. IL-4 mRNA was constitutively detectable in all (10/10) EBV-transformed B cell clones, and the mRNA for IFN-gamma was constitutively present in half of the clones. In contrast to IL-2 mRNA, the expression of IL-4 and IFN-gamma mRNA could be increased by PMA alone. Most of the clones produced IL-2 bioactivity and immunoreactive protein, but neither IL-4 nor IFN-gamma protein secretion was detected. The intriguing question raised by these results is whether IL-2 secretion could contribute to the immune control of EBV-infected B lymphocytes by cytolytic T cells, and whether normal B lymphocytes can potentially be induced to express certain cytokines including IL-4 in response to the appropriate activation signals.

B-Lymphocytes↗
PubMed1993

Immunization with thyroglobulin-specific cytotoxic T cell hybridoma induces anti-thyroglobulin antibodies: characteristics of monoclonal anti-thyroglobulin auto-antibody.

We have produced five monoclonal autoantibodies (mA-Abs) to thyroglobulin (Tg) and more precisely to one epitope located within the < 10-kDa pTg tryptic fragment suspension capable of inducing experimental autoimmune thyroiditis (EAT). They were selected from spleen cells from CBA/J mouse immunized with the syngeneic cytotoxic T cell hybridoma HTC2. HTC2 cells are specific for one Tg epitope located within the EAT inducer pTg tryptic fragments and are able to prevent EAT induction by pTg. The restricted specificity of the humoral response previously observed in vivo was further demonstrated and defined in vitro at the single cell level. Competitive studies for binding to pTg or to the < 10-kDa pTg tryptic fragments demonstrated that HTC2-induced anti-Tg mA-Abs recognized an epitope(s) located in the < 10-kDa pTg tryptic fragment (as did 3B8G9, one conventional anti-Tg mA-Ab we selected). We ruled out the possibility that HTC2-induced anti-Tg A-Abs belong to the group of the natural A-Abs due to the lack of recognition of actin, dsDNA, TNP-ovalbumin, tubulin, their isotypes (IgG1 or Ig2a), and their affinities (in the 10(-7) M order of magnitude). The results strengthen the hypothesis that T and B cells sharing the same specificity can express similar idiotopes on their respective receptors for antigen. They also demonstrate the existence of a regulatory idiotypic network that could explain the protection from EAT after injection of inactivated HTC2 cells or its anti-clonotypic mAb.

Animals↗
PubMed1993

Nursing diagnoses for psychiatric patients in China.

This report describes the development of a preliminary Chinese psychiatric classification system with nine categories and 211 separate diagnoses, and the corresponding diagnostic interview that enables psychiatric nurses in China to systematically assess the presence or absence of the various diagnoses. Using this interview with 30 representative inpatients, the authors identified 152 of the 211 (72%) diagnoses. On average, each patient was given 26 different nursing diagnoses. The interrater reliability of the four nurses who independently coded the diagnostic interview for these 30 patients was excellent: in over 77% of the identified diagnoses the generalized kappa was greater than 0.75. These findings show that further work on this classification of nursing diagnoses is warranted.

Adolescent↗
PubMed1993

Expression of coagulation factor IX (Christmas factor) in human hepatoma (HepG2) cell cultures after retroviral vector-mediated transfer.

PURPOSE: In this study, we compared production of recombinant human factor IX by HepG2 cells transduced with a cytomegalovirus (CMV) promoter-controlled factor IX vector to endogenous production of factor IX by non-transduced primary rat hepatocytes. METHODS AND RESULTS: Northern analysis showed 2.8 kb transcripts corresponding to the known size of factor IX mRNA in primary hepatocyte preparations and vector factor IX transcripts of the expected sizes in transduced HepG2 cell preparations. Factor IX produced by transduced HepG2 cells was completely inhibited by a monospecific antibody against human factor IX. Western analysis showed that recombinant factor IX migrated to the region of native plasma factor IX at 56 Kd. Production of biologically active factor IX by transduced HepG2 cells was 20-fold greater than that by nontransduced primary hepatocytes. CONCLUSION: These data indicate that transduced HepG2 cells transcribe, synthesize, and secrete authentic factor IX, and that these genetically engineered cells secrete significantly greater amounts of factor IX than do nontransduced primary hepatocytes. Studies are in progress to determine the effect of hepatocyte mitogens on production of factor IX in transduced HepG2 cells and primary hepatocytes.

Animals↗
PubMed1993

Biosynthesis and regulation of Le(x) and SA-Le(x) glycolipids in metastatic human colon carcinoma cells.

This report concerns the stepwise biosynthesis in vitro of Sialyl Lewis X, (SA-Le(x)), a carcinoembryonic antigen, in human colon carcinoma KM12 cells exhibiting different metastatic behaviors. The significance of SA-Le(x) has become even more apparent since the detection of its terminal epitope NeuAc(alpha 2-3)Gal beta 1-4(Fuc alpha 1-3)GlcNAc-, as the binding ligand of the selectin family member ELAM-1. The activity level of galactosyltransferase GalT-4 which catalyzes the formation of core nLcOse4Cer (Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-Cer) is very high in all the metastatic lines tested with highly metastatic lines (KM12-SM) exhibiting the highest activity. The same activity pattern for galactosyltransferase is also observed when tested with iLcOse5Cer (GlcNAc beta 1-3nLcOse4Cer), the precursor for polylactosamine glycolipid. Sialyltransferase SAT-3 which catalyzes the formation of LM1 (NeuAc alpha 2-3nLcOse4Cer), the precursor for SA-Le(x), is also present in all the metastatic cell lines although the activity levels are much lower compared to galactosyltransferase. The fucosyltransferase FucT-3, which catalyzes the formation of R'-Gal-Fuc(alpha 1-3)GlcNAc-R linkage, is active with both nonsialylated substrate, nLcOse4Cer, and sialylated substrate, LM1 (NeuAc alpha 2-3nLcOse4Cer) with the formation of either Le(x) (Gal beta 1-4(Fuc alpha 1-3)GlcNAc beta 1-3Gal beta 1-4Glc-Cer) or SA-Le(x) (NeuAc alpha 2-3nLcOse4Cer). However, the sialylated substrate LM1 is preferred to enzymatic activity since it exhibited lower Km (46 microM) than that of nLcOse4Cer (67 microM).(ABSTRACT TRUNCATED AT 250 WORDS)

Carbohydrate Conformation↗
PubMed1992

Characterization and sequencing of a 40-amino-acid peptide from human thyroglobulin inducing experimental autoimmune thyroiditis.

We previously demonstrated that: a) a cytotoxic T cell hybridoma (HTC2) was able to induce lysis of syngeneic macrophages pulsed with either porcine thyroglobulin (pTg) or the tryptic fragments (TF) from pTg less than 10 kDa (M(r)) and that b) these low M(r) pTg TF included pathogenic epitopes because their injection into CBA/J mice induces thyroid lymphocytic infiltration typical of experimental autoimmune thyroiditis. Therefore the biochemical analysis of the TF preparation from pTg less than 10 kDa M(r) was undertaken and the characterized peptides were tested for their ability to be recognized or not by HTC2 cells. The sequencing of the selected peptides showed a 70% sequence homology with a portion of human thyroglobulin (hTg). The lack of a published sequence of pTg led us to synthesize a 40-amino acid peptide (F40D) similar to that portion of hTg. This F40D peptide was able to generate lymphocytic infiltrations in CBA/J mice thyroid glands, as was the native pTg molecule. Although the lymphocytic infiltrations were similar in the pTg or F40D-immunized mice, auto-antibodies to pTg or to hTg were only detectable in mice immunized with pTg. In contrast, autoantibodies levels to F40D peptide were significantly increased in serum from mice in which EAT had been induced by the F40D peptide. This highly hydrophobic peptide shows a M(r) of 4,492 kDa; it is located at the end of the second-third of the thyroglobulin molecule and up to now represents a unique sequence from the hTg molecule inducing experimental autoimmune thyroiditis.

Amino Acid Sequence↗
PubMed1992

Changes in lipid content and composition during the development of N-nitrosodiethylamine induced hepatocarcinoma.

Alterations in lipid content and composition in the N-nitrosodiethylamine-induced hepatocarcinoma were investigated. Rats were administered with N-nitrosodiethylamine in the drinking water for 12 weeks followed by normal tap water for another 6 weeks. The cholesterol content in the liver was increased shortly after the administration of N-nitrosodiethylamine and remained elevated after the removal of the nitrosoamine from the water. The phosphatidylethanolamine level was elevated during N-nitrosodiethylamine administration with a concomitant reduction in phosphatidylcholine level. Lysophosphatidylcholine and sphingomyelin levels were increased during the last four weeks of the study. The level of phosphatidylinositol was substantially reduced after eight weeks of N-nitrosodiethylamine treatment, and remained low during the post-treatment period. We postulate that changes in lysophosphatidylcholine and sphingomyelin may be a compensatory mechanism for maintaining the asymmetrical distribution of choline-containing lipids in the outer leaflet of the membrane. The elevated level of cholesterol may be a useful indicator for the early detection of N-nitrosodiethylamine-induced hepatocarcinoma.

Animals↗
PubMed1992

Relationships between speech recognition threshold, average hearing level, and speech importance noise detection threshold.

The aim of this study was to determine (a) if the speech importance noise detection threshold (SINDT) could be used as an accurate estimator of speech recognition threshold (SRT), and (b) whether the SINDT correlates well with various measures of the pure-tone threshold average (PTA). Pure-tone threshold, SRT, and SINDT tests were administered to 94 adults with various degrees of hearing loss. The results demonstrated that SRT can be accurately predicted from SINDT and that these two are highly correlated (r = 0.97). Since a SINDT measurement takes less time than SRT determination, the SINDT test may be recommended as an alternative for SRT in some applications.

Adolescent↗
PubMed1992

High-frequency threshold measurements using insert earphones.

Several recent studies have reported large intersubject variability of high-frequency thresholds measured with circumaural earphones. In the present study, high-frequency thresholds of 10 subjects were measured with circumaural (Sennheiser HD-250) and insert (Etymotic ER-1) earphones at 10, 12, 14, and 16 kHz. Overall results show significantly smaller variability of the threshold data obtained with insert earphones than with circumaural earphones. The above data indicate that insert earphones may be more suitable for high-frequency testing than circumaural earphones.

Acoustic Stimulation↗