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Biomedical subjects

A Chiu

Publications and source records attributed to A Chiu.

67 records · Page 4Linked to original sources
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Determination of picogram levels of brain serotonin by a simplified liquid chromatographic electrochemical detection assay.

A simplified assay is described for measurement of picogram amounts of serotonin (5-HT) by high pressure liquid chromatography with electrochemical detection (LCEC). The procedure involves pre-purification of brain 5-HT by adsorption on Amberlite CG-50. Serotonin is subsequently resolved and detected by LCEC on Zipax SCX resin. The present method gives working sensitivities of at least 100 pg, tissue recoveries of 95% and very low interassay variability (coefficient of variation = 3%). Determination of rat brain area 5-HT by this LCEC method is described and compared to other high sensitivity methods.

Animals↗
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Synchronous appearance of germ cell tumor and papillary carcinoma of the thyroid.

Synchronous appearance of 2 different malignancies in one patient is a rare phenomenon. We describe our experience of 2 patients with synchronous malignancies of the testis and thyroid gland, and of a third patient who developed a thyroid neoplasm unrelated to recent treatment for a germ cell tumor. The medical records of 3 male patients treated for both a germ cell tumor and a thyroid cancer between 1989 and 1994 were reviewed. Two patients with nonseminomatous germ cell tumor received postoperative chemotherapy after orchiectomy and developed a papillary carcinoma of the thyroid during treatment. A third patient, who received radiation therapy for a clinical stage 1 seminoma, recurred with biopsy proven seminoma in the neck in association with a thyroid nodule 2 years later. All 3 patients had their thyroid cancer treated by surgical resection, and one received adjuvant radioactive iodine. Two of the patients are currently alive and disease-free. One patient died of pulmonary complications that stemmed from bleomycin toxicity. Synchronous appearance of germ cell tumor and papillary carcinoma of the thyroid has not been previously described. Genetic predisposition may play a role in the development of such simultaneous neoplasms.

Adult↗
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Reduction of chromium(VI) and its relationship to carcinogenesis.

Although Cr(VI)-containing compounds are well-documented carcinogens, their mechanism of action is still not well understood. Recent studies have suggested that reduction of Cr(VI) to its lower oxidation states and related free-radical reactions play an important role in carcinogenesis. This article summarizes recent studies on (1) the reduction of Cr(VI) by ascorbate, diol- and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (2) free-radical production with emphasis on hydroxy radical generation via Fenton or Haber-Weiss type reactions; and (3) free-radical-induced cellular damage, such as DNA strand breaks, hydroxylation of 2'-deoxyguanosine, and activation of nuclear transcription factor kappa B.

Animals↗