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Biomedical subjects

B C Chen

Publications and source records attributed to B C Chen.

44 records · Page 3Linked to original sources
PubMed1989

Epidemiological study on dental fluorosis and dental caries prevalence in communities with negligible, optimal, and above-optimal fluoride concentrations in drinking water supplies.

The prevalence of dental caries and dental fluorosis was assessed in 5,107 children (2,669 boys and 2,438 girls) aged 6 to 16 years who were lifelong residents of Shenkang Hsiang. The drinking water in the various villages in this area contains negligible, optimal, and above-optimal concentrations of natural fluoride. The prevalence of caries in the optimal fluoride areas was 10.7% lower than in the negligible fluoride area. In the above-optimal fluoride areas, even greater protection from caries was evident. Caries protection was compromised, however, in children with severe fluorosis. The effect may result from food, debris, or plaque being entrapped in the hypoplastic defects of severely fluorosed enamel. Data from children residing in the optimal and above-optimal fluoride areas show that older children are affected more by fluorosis than younger children, according to the Tooth Surface Index of Fluorosis. The relevant variables associated with secular changes in the prevalence of fluorosis are explored. Of the 14 communities studied, chyuarnshing, Dahturng, and Haaiweei, according to the Community Fluorosis Index, represent a medium fluorosis problem, while Dihngsing and Shehgun represent a slight public health fluorosis problem. The remaining communities have no public health fluorosis problem.

Adolescent↗
PubMed1988

An epidemiological study on farmer's lung among hay grinders in Dafeng County.

This article reports on an epidemiological survey of the presence of farmer's lung among 1054 farmers who grind moldy hay. The prevalence was 8.3-11.4%. The main pathogen was Thermoactinomyces vulgaris. The factors which influenced farmer's lung were the moldy state of the hay and the dust concentration. The epidemiological features of farmer's lung are analyzed and discussed and certain preventive measures are suggested.

Adult↗
PubMed1977

Reappraisal of the value of mode-A-echoencephalography.

The result of the first 425 cases studied in the Department of Neurology and Psychiatry, NTUH, by Mode A ultrasonic pulse techniques in the diagnosis of intracranial lesions is presented and compared with the findings in EEG, angiogram, air study and operation. The overall diagnostic accuracy in predicting midline echo shifting is 95.3%. The degree of echo shift is shown to be more closely related to the shift of venous angle than that of the anterior cerebral artery. The benefit of the combined use of echo and EEG is stressed. A method aiming at decreasing the operator bias is presented.

Adult↗
PubMedDate not supplied

Potentiation of lipopolysaccharide-induced IL-6 release by uridine triphosphate in macrophages: cross-interaction with cyclooxygenase-2-dependent prostaglandin E(2) production.

Our previous study has demonstrated the potentiation by uridine triphosphate (UTP) of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production in lipopolysaccharide (LPS)-stimulated murine J774 macrophages. In this study, we found that the amount of interleukin-6 (IL-6) release in response to LPS stimulation was greatly enhanced in the presence of UTP. This enhancement exhibited concentration dependence and occurred after 8 h of treatment with LPS. RT-PCR analysis indicated that the steady-state level of IL-6 mRNA induced by LPS was apparently increased upon co-addition of UTP. The potentiation by UTP was inhibited by the treatment with U73122 (a phosphatidylinositol-phospholipase C inhibitor), BAPTA/AM (an intracellular Ca(2+) chelator), KN-93 (a selective inhibitor of calmodulin-dependent protein kinase) or PDTC (a nuclear factor kappaB inhibitor). To understand the cross-regulation among NO, PGE(2) and IL-6, all of which are dramatically induced after LPS stimulation, the effects of L-NAME (a nitric oxide synthase inhibitor), indomethacin (a cyclooxygenase inhibitor), NS-398 (a cycloxygenase-2 inhibitor) and IL-6 antibody were tested. The results revealed the positive regulation between PGE(2) and IL-6 synthesis because NS-398 and indomethacin inhibited LPS plus UTP-induced IL-6 release, and IL-6 antibody attenuated LPS plus UTP-induced PGE(2) release. Taken together these results reinforce the role of UTP as a regulatory element in inflamed sites by demonstrating the capacity of this nucleotide to potentiate LPS-induced release of inflammatory mediators.

Animals↗
PubMedDate not supplied

Double-stranded cyclic oligonucleotides with non-nucleotide bridges.

A series of double-stranded, cyclic oligodeoxynucleotides with non-nucleotide bridges have been synthesized, and their physicochemical properties and susceptibility to enzymes have been investigated. These bridged duplexes are of potential interest for their binding properties to transcription factors and other DNA-binding proteins. Triethylene glycol has been employed as the bridge to alter the lipophilicity of the duplex and avoid the potential for enzymatic cleavage. The synthetic route involved the synthesis of a 3'-phosphorylated, nicked double-stranded precursor with the final internucleotide bond being formed chemically using a water soluble carbodiimide. These bridged duplexes have high thermal dissociation temperatures, and the Tm for a triethylene-bridged 20 base pair duplex was higher than that for the corresponding pentathymidylate-bridged duplex. EcoR I endonuclease cleaved a ligated, bridged duplex at a slower rate than the corresponding unmodified duplex, whereas the unligated, bridged duplex was cleaved more rapidly. Sufficient amounts of the bridged octamer and dodecamer were prepared for proton NMR spectroscopic studies, and 2D COSY and NOESY spectra were obtained. The results indicate that the ligated duplex has a B-form conformation.

Base Sequence↗