Biomedical subjects

A H Yang

Publications and source records attributed to A H Yang.

58 records · Page 4Linked to original sources

PubMedDate not supplied

Reiter's syndrome caused by Streptococcus viridans in a patient with HLA-B27 antigen.

A 26-year-old male patient with mitral valve prolapse and HLA-B27 antigen received endodontic treatment for dental caries. Two weeks later fever, dysuria, diarrhea, sterile inflammatory arthritis of lower limbs, enthesitis, dactylitis, conjunctivitis, and uveitis consecutively developed. Blood culture performed at the time of active arthritis yielded Streptococcus viridans. He did not have any history of psoriasis, acute infectious diarrhea, chronic inflammatory bowel diseases, or sexually transmitted diseases. Laboratory studies also excluded the possibility of infections by human immunodeficiency virus, hepatitis B or C virus, chlamydia, and streptococci from the upper airway. This report indicates that Streptococcus viridans can be the triggering microorganisms of Reiter's syndrome in some circumstances.

Adult↗

PubMedDate not supplied

Human peritoneal mesothelial cells produce nitric oxide: induction by cytokines.

OBJECTIVE: To investigate the induction of nitric oxide synthase type II (iNOS) in human peritoneal mesothelial cells (HPMC) using cytokines and bacterial lipopolysaccharide (LPS). DESIGN: Confluent monolayers of HPMC were exposed to cytokines [tumor necrosis factor alpha (TNFalpha), interleukin-1 beta (IL-1beta), interferon gamma (IFNgamma)] or LPS, individually or in various double and triple combinations, for 24-72 hours. Concentrations of nitrate and nitrite in the media were quantified using the Griess reaction and used as indirect indices of nitric oxide (NO) production. The expression of iNOS was assessed using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot. RESULTS: Neither single cytokines nor LPS was able to induce iNOS mRNA or NO production. Both double combinations of TNFalpha + IFNgamma and IL-1beta + IFNgamma were able to induce iNOS mRNA expression, but only TNFalpha + IFNgamma induced significant NO production. The triple combination of TNFalpha + IFNgamma + IL-1beta induced even more NO production than TNFalpha + IFNgamma. There was no constitutive NO synthase type III (eNOS) expression in HPMC. CONCLUSIONS: Certain combinations of cytokines could stimulate cultured HPMC to produce NO, and HPMC might be a source of intraperitoneal NO production during peritonitis.

Blotting, Western↗

PubMedDate not supplied

Absence of modulating effects of cytokines on antioxidant enzymes in peritoneal mesothelial cells.

OBJECTIVE: To investigate the modulation of superoxide dismutase, glutathione peroxidase, and catalase by cytokines and endotoxin in human peritoneal mesothelial cells. DESIGN: Cultured human peritoneal mesothelial cells were treated with various concentrations of interleukin-1 alpha, tumor necrosis factor-alpha (TNF-alpha), interleukin-6, interleukin-8, transforming growth factor-beta (TGF beta), and lipopolysaccharide. Cell morphology was observed and the activities of superoxide dismutase, catalase, and glutathione peroxidase were assayed. The antioxidant enzyme activities of human peritoneal mesothelial cells were also compared with those of human liver and kidney tissues. RESULTS: Interleukin-1 alpha, TNF alpha, TGF beta, and lipopolysacharide caused dose-dependent cytotoxicities in mesothelial cells. The activities of these three antioxidant enzymes did not change after treatment with cytokines and endotoxin. The total superoxide dismutase activity of confluent human peritoneal mesothelial cells was found to be greater than that of human liver and kidney tissues and was composed mostly of manganese superoxide dismutase activity. Furthermore, glutathione peroxidase and catalase activities of human peritoneal mesothelial cells were lower than those of human liver and kidney tissues. CONCLUSION: In human peritoneal mesothelial cells, lack of induction of antioxidant enzymes by inflammatory cytokines, as well as high superoxide dismutase activity accompanied by insufficient glutathione peroxidase and catalase activities may both contribute to the susceptibility of these cells to oxidative damage. Therefore, appropriate management to decrease oxidative injury to the peritoneum should be taken into consideration when treating long-term continuous ambulatory peritoneal dialysis patients.

Antioxidants↗

PubMedDate not supplied

Abnormal transcripts of FHIT gene in thyroid cancer.

Abnormalities of the FHIT gene were found in many carcinoma cell lines and human tumors as reported which suggest an etiological function in tumorigenesis. To investigate whether the FHIT gene is a target of thyroid tumor specific 3p alterations, we screened the FHIT gene for alteration in thyroid tumors and found that the tumors exhibited aberrant FHIT gene expression. The complete sequence of the FHIT gene in seven cases was determined and deletions between exon 2-9 in different regions were found. Goiter samples as control had normal FHIT transcripts while both normal and aberrant transcripts of FHIT were found not only in the tumor samples but also in the adjacent non-tumorous portion of the thyroid tumor. Our results support the hypothesis that FHIT gene alteration is involved in tumorigenetic development of human neoplasms in thyroid glands.

Acid Anhydride Hydrolases↗