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Biomedical subjects

D R Huang

Publications and source records attributed to D R Huang.

16 recordsLinked to original sources
PubMed2001

Absence of monocyte chemoattractant protein 1 in mice leads to decreased local macrophage recruitment and antigen-specific T helper cell type 1 immune response in experimental autoimmune encephalomyelitis.

Monocyte chemoattractant protein (MCP)-1 plays a critical role in innate immunity by directing the migration of monocytes into inflammatory sites. Recent data indicated a function for this chemokine in adaptive immunity as a regulator of T cell commitment to T helper cell type 2 (Th2) effector function. Studies in a Th1-dependent animal model, experimental autoimmune encephalomyelitis (EAE), showed that MCP-1 was highly expressed in the central nervous system (CNS) of affected rodents, and MCP-1 antibodies could block relapses of the disease. Mice deficient for the major MCP-1 receptor, CC chemokine receptor (CCR)2, did not develop EAE after active immunization but generated effector cells that could transfer the disease to naive wild-type recipients. We analyzed EAE in mice deficient for MCP-1 to define the relevant ligand for CCR2, which responds to murine MCP-1, MCP-2, MCP-3, and MCP-5. We found that C57BL/6 MCP-1-null mice were markedly resistant to EAE after active immunization, with drastically impaired recruitment of macrophages to the CNS, yet able to generate effector T cells that transferred severe disease to naive wild-type recipients. By contrast, adoptive transfer of primed T cells from wild-type mice into naive MCP-1-null recipients did not mediate clinical EAE. On the SJL background, disruption of the MCP-1 gene produced a milder EAE phenotype with diminished relapses that mimicked previous findings using anti-MCP-1 antibodies. There was no compensatory upregulation of MCP-2, MCP-3, or MCP-5 in MCP-1-null mice with EAE. These results indicated that MCP-1 is the major CCR2 ligand in mice with EAE, and provided an opportunity to define the role of MCP-1 in EAE. Compared with wild-type littermates, MCP-1-/- mice exhibited reduced expression of interferon gamma in draining lymph node and CNS and increased antigen-specific immunoglobulin G1 antibody production. Taken together, these data demonstrate that MCP-1 is crucial for Th1 immune responses in EAE induction and that macrophage recruitment to the inflamed CNS target organ is required for primed T cells to execute a Th1 effector program in EAE.

Amino Acid Sequence↗
PubMed2001

TNF-alpha mediates SDF-1 alpha-induced NF-kappa B activation and cytotoxic effects in primary astrocytes.

Stromal-derived cell factor-1 alpha (SDF-1 alpha; CXCL12) and its receptor, CXCR4, are constitutively expressed on neuroepithelial cells and are believed to be involved in both development and pathological processes, such as AIDS-associated neurologic disorders. Here, we demonstrate that SDF-1 alpha activates NF-kappa B, stimulates production of chemokines and cytokines, and induces cell death in primary astrocytes, effects that depend on ongoing secretion of TNF-alpha. SDF-1 alpha upregulated TNF-alpha mRNA and protein secretion, as well as TNF receptor 2 expression. TNF-alpha treatment mimicked SDF-1 alpha induction of NF-kappa B, IL-1 alpha/beta, and RANTES, as well as cell death; neutralizing antibodies against TNF-alpha opposed these responses. We also found that SDF-1 alpha activated Erk1 and Erk2 (Erk1/2) MAPK in a biphasic fashion. Early Erk1/2 activation was stimulated directly by SDF-1 alpha and late activation was mediated by TNF-alpha. PD98059 suppression of early Erk1/2 activation correlated with reduction of SDF-1 alpha-induced TNF-alpha expression. Late Erk1/2 activation was involved in TNF-alpha-stimulated NF-kappa B activation and cytokine induction. SDF-1 alpha was induced in reactive CXCR4-positive astrocytes near axotomized spinal cord motor neurons, consistent with autocrine SDF-1/CXCR4 signaling in these cells. We propose that these novel effects of SDF-1 alpha are relevant to the pathogenic and developmental roles of SDF-1 alpha in the CNS.

Animals↗
PubMed2000

Interleukin 6, tumour necrosis factor alpha, interleukin 1beta and interleukin 1 receptor antagonist promoter or coding gene polymorphisms in multiple myeloma.

Proinflammatory cytokines such as interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and IL-1beta are considered to be involved in the pathogenesis of multiple myeloma (MM). In the present study, we examined a G/C polymorphism at position -174 in the promoter region of IL-6, a biallelic polymorphism at position -308 in the promoter region of TNF-alpha, the TaqI restriction fragment length polymorphism in exon 5 of IL-1beta and a variable number of identical tandem repeat polymorphisms in intron 2 of IL-1 receptor antagonist (IL-1Ra) genes. The alleles of these loci are known to influence the level of production of the cytokines and the IL-1Ra. Seventy-three patients with MM, 27 with monoclonal gammopathy of undetermined significance (MGUS) and 129 healthy individuals were included. No difference was found between patients and healthy controls or between MM and MGUS patients in the distributions of genotypes and frequencies of alleles of the IL-6 (-174), TNF-alpha (-308), IL-1beta TaqI and IL-1Ra gene polymorphisms. No associations between the polymorphisms at the loci under study and clinical factors such as age, sex, clinical stage at onset and M-protein type were observed. Our results indicate that the cytokine (IL-6, TNF-alpha and IL-1beta) and IL-Ra gene polymorphisms do not confer susceptibility to the development of MM.

Adult↗
PubMed1999

Markers in the promoter region of interleukin-10 (IL-10) gene in myasthenia gravis: implications of diverse effects of IL-10 in the pathogenesis of the disease.

Interleukin-10 (IL-10) is an important pleiotropic cytokine with both anti-inflammatory and B lymphocyte stimulating functions. The expression of IL-10 is tightly controlled. A bi-allelic polymorphism and 2 CA repeat microsatellites located in the promoter region of IL-10 gene were analysed in Swedish myasthenia gravis (MG) patients and ethnically matched healthy individuals. The prevalence of a 'high secretor' phenotype of IL-10 (IL-10 1 G/G) was higher in IL-1beta TaqI polymorphism allele 2 positive healthy individuals ('high secretor' phenotype for IL-1beta) than in healthy individuals negative for this allele. No such balance was found in MG patients. In one of the microsatellites, IL10.R, allele 112 was associated with patients having normal thymic histology. No relation of IL10.R allele 112 to proinflammatory cytokine gene polymorphisms and serum IgG, IgM and autoantibodies against nicotinic acetylcholine receptor (nAchR-Ab) was found. In another microsatellite, IL10.G, allele 134 was associated with patients having higher level of nAchR-Ab in their circulation. Our results demonstrated novel genetic markers within IL-10 gene indicating different mechanisms for IL-10 involved in the disease.

Alleles↗
PubMed1999

Tumour necrosis factor-alpha polymorphism and secretion in myasthenia gravis.

The mechanism behind the association between MHC genes and myasthenia gravis (MG) is not fully understood. In the present study we studied the associations with polymorphisms at HLA-DR3, HLA-B8 and TNF-alpha genes in Swedish patients and healthy individuals. The TNF-alpha-308 allele 2 was associated with female patients having disease onset before the age 40 and with thymic hyperplasia. Analysis of strongest associations between MG and alleles close to TNF-alpha indicated that the association of TNF-alpha was possibly stronger than for HLA-DR3 and nearly the same as for HLA-B8. Peripheral blood mononuclear cells from patients positive for TNF-alpha -308 allele 2 had higher secretion of TNF-alpha when stimulated by anti-CD3 antibodies. Our results indicate that a subgroup of MG patients who have been previously shown to be associated with MHC genes may have a higher inducible TNF-alpha level in vivo, thus resulting the pathological changes in the thymus and the early onset of MG.

Adult↗
PubMed1999

The expression of insulin-like growth factor II, hepatitis B virus X antigen and p21 in experimental hepatocarcinogenesis in tree shrews.

The purpose of this paper was to study the mechanism of synergistic effect in hepatocarcinogenesis induced by hepatitis B virus (HBV) infection and aflatoxin B1 (AFB1) intake. Immunohistochemical staining was used in formalin-fixed, paraffin-embedded sections of cancer and liver tissues. The incidence of hepatocellular carcinomas (HCCs) was 52.9% in experimental tree shrews that received both HBV and AFB1. It was significantly higher than that of animals exposed to HBV (11.1%, Group B), or (AFB1) (15.8%, group C) alone. HCC was not found in the control animals (group D). The expressions of insulin-like growth factor II (IGF-II) were 82.4%, 22.2%, 26.3% and 0 in groups A, B, C and D, respectively. The significant differences of IGF-II were observed between groups A and B, C and D (P < 0.05). The expressions of p21 were 29.4%, 11.1%, 15.8% and 0 in group A, B, C and D, respectively. The positive rate of hepatitis B x antigen (HbxAg) was significantly higher in the group A than that in the group B (52.9% vs. 11.1%, P < 0.05). The parallel relations between the incidence of HCC and the overexpressions of these genes protein have been found in each group. On the other hand, the expressions of these genes in tumour-bearing tree shrews were significantly higher than that in nontumour-bearing animals. These findings suggest a synergistic effects of HBV and AFB1 in activation of these genes in tree shrews. Overexpressions of these genes may take an important role in the course of hepatocarcinogenesis in tree shrews.

Aflatoxin B1↗
PubMed1996

Human hepatitis B virus and hepatocellular carcinoma. I. Experimental infection of tree shrews with hepatitis B virus.

Tree shrews (Tupaia belangeri chinenesis) can be experimentally infected with human hepatitis B virus (HBV) by inoculation with human serum positive for HBV, the experimental infection rate being 55.21%. Successive infections have been passed through five generations among the tree shrews inoculated with HBV-positive sera from the infected animals, the average infection rate being 94.0%. The experimental infection of tree shrews with HBV may be prevented by immunization with hepatitis B vaccine, the protection rate being 88.89%. Standard serum containing HBV at 10(8) CID (chimpanzee infection dose)/ml, was diluted 10(-6), 10(-7), 10(-8), 10(-9), and 10(-10) and produced infection rates of 80.0%, 88.8%, 66.7%, 55.6% and 42.9% respectively. Thus the CID50 in tree shrews may reach a dilution of 10(-9), which shows that tree shrews are sensitive to HBV infection. These results successfully establish tree shrews as a reliable and useful animal model for research on HBV infection and its relation to hepatocarcinogenesis.

Animals↗
PubMed1996

Human hepatitis B virus and hepatocellular carcinoma. II. Experimental induction of hepatocellular carcinoma in tree shrews exposed to hepatitis B virus and aflatoxin B1.

On the basis of the successful establishment of an animal model in tree shrews experimentally infected with human hepatitis B virus (HBV), a study on the hepatocarcinogenic effects of HBV and/or aflatoxin B1 (AFB1) was conducted. The results showed that the incidence of hepatocellular carcinoma (HCC) was significantly higher in the animals both infected with HBV and exposed to AFB1 (52.94%) than in those solely infected with HBV (11.11%) or exposed to AFB1 (12.50%). No HCC of precancerous lesions were found in the controls that were neither HBV-infected nor AFB-1 exposed. Precancerous lesions, including liver cell dysplasia and enzyme-altered hyperplastic hepatocyte foci, were observed before the occurrence of HCC, and the frequency of their appearance correlated well with the incidence of HCC. HBV DNA and the protein it encodes were detected in the cancer cells and/or the surrounding hepatocytes. Integration of HBV DNA into the host liver genome was found during hepatocarcinogenesis among the animals infected by HBV. These results suggest that exposure to HBV and AFB1 may play a synergistic role in the development of HCC, and support the viewpoint of an aetiological relationship between HBV and HCC.

Aflatoxin B1↗
PubMed1994

Regulatory action of Astragalus saponins and buzhong yiqi compound on synthesis of nicotinic acetylcholine receptor antibody in vitro for myasthenia gravis.

With overall analysis of symptoms and signs of myasthenia gravis (MG) basing on "Pi (Spleen) Deficiency" [symbol: see text] theory and with years of our clinical experience in treating MG, we performed a pharmacological study of Astragalus saponins and Buzhong Yiqi Compound (Tonic granulae invigorating vital energy) in 14 peripheral blood mononuclear cell (PBMNC) cultures from 10 MG patients. PBMNG from two groups of patients given dexamethasone (Dxm) and cobalt 60 (60Co) treatment were used as controls. The results showed that water soluble Astragalus saponins significantly reduced the titer of nicotinic acetylcholine receptor antibodies (nAchR-Ab) in the cell culture supernatants, from 418.8-2328 to nil in 6 cases, and from 1143-1235 to 43-157 fmol/ml in 2 cases, and that Buzhong Yiqi compound also had inhibitory immunoregulatory action.

Adolescent↗
PubMed1993

The crystal and molecular structure of trichosanthin at 2.6 A resolution.

The crystallographic refinement of trichosanthin has been performed at 2.6 A resolution. The crystal and molecular structure of trichosanthin is described in detail in this paper. On summarizing the regularity of the amino acid sequences of eight kinds of ribosome inactivating proteins and combining with the crystal and molecular structure of trichosanthin, fifteen most conservative amino acid residues are analyzed. It is found that four most conservative polar amino acid residues Gln156, Glu160, Arg163 and Glu189 gather on the molecular surface on the boundary of the large and small domains, thus forming the active center of the protein molecule.

Amino Acid Sequence↗
PubMed1990

Choledochoscopy in management of retained biliary stones and recurrent lesions.

Postoperative choledochofiberscopy was performed in 188 patients with retained biliary stones and recurrent lesions. The following entrances to the biliary tract for choledochoscopy were used: the T-tube tract (129 patients), an afferent jejunal limb of a choledochojejunostomy (43), the jejunostomy tube tract of an efferent limb (12), an U-tube tract (2), and a ductal fistula after segmental liver resection (2). 380 choledochoscopic sessions were carried out, 2 sessions on the average for each patient. The overall success rate of stone removal was 90.5%. No mortality was related to this procedure. Eleven patients developed fever and chills after manipulations but all responded to antibiotics. Two patients had perforation of the T-tube tract during the removal of stones and were reoperated on for abdominal drainage. They recovered eventually. Stone extraction with a flexible choledochoscope is a proven procedure. For residual intrahepatic stones, however, a satisfactory entrance into the biliary tree should be provided for subsequent stone removals. We believe that the jejunostomy tube tract of an efferent limb of an afferent jejunal limb of a choledochojejunostomy is a useful entrance for choledochoscopy because it is permanent in meeting therapeutic demands.

Adolescent↗
PubMed1988

[Carcinoma of the extrahepatic bile duct].

The diagnosis and treatment of 18 patients with carcinoma of the extrahepatic bile duct are reported. All patients were worked up by USG, PTC or ERC before operation. Tumor was resected in 3 patients, palliative internal or external drainage of the biliary tract was performed in 10, 1 was explored and 4 received PTCD treatment. One of the patients with the tumor resected has survived for 2 years. Mean survival time after the operation was 5.6 months for patients treated by drainage. The authors believe that PTC and ERC play the most important role in diagnosing carcinoma of the biliary tract. As this tumor has a low resection rate, internal or external drainage of the biliary tract should be done for patients with unresectable lesions. PTCD is still one of the effective palliative therapies for inoperable lesions.

Adult↗
PubMed1983

The effects of thyroid hormone on in vitro phosphorylation, acetylation, and ADP ribosylation of rat liver nuclear proteins.

The effect of thyroid hormone on acetylation, phosphorylation and ADP ribosylation of rat liver nucleoproteins was studied by incubating intact nuclei with labeled precursors. Acetylation, which occurred in histones and low molecular weight proteins (less than 30,000), was depressed in nuclei from thyroidectomized animals. The administration of L-3,5,3'-triiodothyronine (T3) increased acetate incorporation to 50% over control levels. Incorporation of labeled phosphate from ATP into most proteins was decreased in nuclei from thyroidectomized animals and increased by the administration of T3. The greatest increase produced by T3 (to 140% of control values) was seen in proteins of molecular weight greater than 68,000. Nuclei from thyroidectomized animals incorporated less ADP ribose in most proteins. Both high molecular weight proteins (greater than 68,000) and low molecular weight proteins (less than 30,000) showed a further decrease in ADP ribose incorporation in nuclei from thyroidectomized rats given T3. However, a few proteins of the middle molecular weight class showed increased ADP ribose incorporation subsequent to the injection of T3. It is suggested that a generalized increase in protein synthetic rates previously noted to be caused by T3 is accompanied by increased acetylation and phosphorylation of histones and other proteins. These changes could accelerate transcription of already active genes.

Acetylation↗