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Biomedical subjects

J S Hwang

Publications and source records attributed to J S Hwang.

63 records · Page 4Linked to original sources
PubMed1990

[A review of larvivorous fish].

Recently, because of concern about the effects of insecticide on the environment, increased attention is being given to the use of biological agents for controlling the vectors of human disease. Biological control may encompass the use of predators, pathogens, parasites, pheromones, insect growth regulators, and other factors. Of these agents only fish and bacteria have so far been used operationally in mosquito control. Since 1988 fish have been employed for controlling Aedes larvae in water containers in Liuchiu, Pingtung. A review of larvivorous fish (mainly Gambusia affinis) and the present status of the use of fish in mosquito control in Mainland China are thus made for ready reference for the workers in mosquito control in Taiwan.

Animals↗
PubMed1990

[Preliminary study on the biological control of dengue vectors by fish in Liouchyou Prefecture, Pingtung County, Taiwan].

An investigation made in May 1989 with questionnaires to 2,480 families in Liouchyou Prefecture, Pingtung County, showed that there were about 6,533 water containers in the whole village, of which 49.83% were used to store water for drinking, and the remaining 50.17% were used for washing clothes and watering plants. 32.42% of the residents volunteered to rear fish in the family water containers to control the mosquito population. During the period from April to October 1989, there was a total approximately 17,600 Gambusia affinis, Poecilia reticulata, Tilapia mossambica, and Sarotherodon niloticus released into the household water containers in the Liouchyou areas to control dengue vectors--Aedes aegypti and Aedes albopictus. One month after the release, a comparison of the container index of Aedes larvae showed that among 530 containers with fish in them, the positive container index was 3.58; among the 3,219 containers without fish in them, it was 25.97. Furthermore, the positive container index without fish was as high as 97.32 in May 1989, and dropped to as low as 18.00 at the end of September 1989. This indicats that rearing fish to control household mosquitoes yielded significant results in the initial stage. Also, in some water containers Gambusia affinis and Porcilia reticulata lived longer than five months, and Gambusia affinis could eat 31.33 Aedes larvae/0.4078g fish per day on the average. It appears that the biological control of dengue vectors by fish in the Liouchyou areas would be advantageous.

Animals↗
PubMed1980

Analogues of chloramphenicol: circular dichroism spectra, inhibition of ribosomal peptidyltransferase, and possible mechanism of action.

Circular dichroism spectra of series of chloramphenicol derivatives la-r were measured in water at pH 7. Compounds 1a-o exhibit two positive Cotton effects at 310--340 and 240--260 nm, respectively, and a weaker negative Cotton effect at 280--300 nm. In analogues 1c, 11, and 1m there is only a minimum between the two positive Cotton effects. Derivatives 1p--r possess a strong negative Cotton effect at ca. 280 nm. Compounds 1a--r were examined as inhibitors of the puromycin reaction with Escherichia coli 70S ribosome-poly(U)-N-AcPhe-tRNA complex. Analogues 11, 1n, lo, and lq are potent competitive inhibitors of puromycin comparable to or better than chloramphenicol (1b). Compounds 1k and 1m are less active, whereas 1d--g and 1j are only moderately effective. The rest of the analogues have marginal or no activity. The results are compared with previous biological data and discussed in terms of a retro-inverso relationship of chloramphenicol (1b) to the aminoacyl moiety of puromycin (aminoacyl-tRNA) and to a hypothetical transition state of peptide bond formation.

Acyltransferases↗
PubMed1977

Chemical aminoacylation of transfer ribonucleic acid. The reaction of Escherichia coli tRNA with ethyl N-benzyloxycarbonylorthoglycinate.

The alpha-carbethoxypentadecyltrimethylammonium (Septonex) salt of tRNA (Ib) was condensed with ethyl N-benzyloxycarbonylorthoglycinate (II) in dimethylformamide in vacuo and in the presence of H3PO4 as catalyst. Pancreatic RNAase degradation and phenylalanine acceptor activity showed a 55--60% conversion to the 2',3'-cyclic orthoglycinate derivative of tRNA (IIIb). The orthoester grouping of IIIb was quantitatively hydrolyzed in 80% formic acid at 0 degrees C for 15 min to give 2'(3')-O-(N-benzyloxycarbonyl)glycyl tRNA (IVb). The latter was stripped at pH 8.8 to give tRNA whose behavior on DEAE cellulose column and gel electrophoresis was similar to that of starting tRNA. The phenylalanine acceptor activity amounted to almost 80% of the starting tRNA.

Chemical Phenomena↗
PubMedDate not supplied

Ifosfamide-induced encephalopathy with or without using methylene blue.

Ifosfamide is one of the most widely used alkylating chemotherapeutic agents. Before mesna was introduced, its dose-limiting toxicity was hemorrhagic cystitis, but at present, neurotoxicity is one of its most worrisome side effects. A total of 10%-15% of patients treated with ifosfamide develop an encephalopathy. The exact pathophysiologic mechanisms responsible for the development of ifosfamide-induced encephalopathy (IIE) are not known. However, accumulation of chloracetaldehyde, toxic metabolite of ifosfamide, in the central nervous system is theorized to be the cause of the neurotoxicity. No standard treatment has been available for IIE. Recently, many reports suggested that methylene blue (MB) may be an effective treatment of this lethal complication. We report two cases of IIE and their treatment outcomes. The first patient recovered completely with MB. The other patient showed slow and incomplete improvement without using MB. We suggest that MB can be used as an initial treatment for the encephalopathy related to ifosfamide infusion. Thus, we present these two cases with brief review of related literature.

Adult↗
PubMedDate not supplied

Protective effects of (-)-epigallocatechin-3-gallate on UVA- and UVB-induced skin damage.

It has been known that green tea and its components possess significant chemopreventive effects against chemical carcinogens and photo-caused skin tumor formation. In this study, the protective effects of (-)-epigallocatechin-3-gallate (EGCG), a major green tea catechin, on the ultraviolet (UV)-induced skin damage (photoaging) were studied in guinea pigs, hairless mice and human dermal fibroblast cultures. The lipid peroxidation was significantly reduced in the EGCG-treated group. The amount of lipid peroxides produced in the control and EGCG treated group were 838 +/- 144 and 286 +/- 57 nmol/mg at 18 h after UV irradiation, respectively. UVB-induced erythema was also significantly reduced in the EGCG treated group. The erythema relative index of the control and the EGCG treated group were 311 +/- 45 and 191 +/- 49 at 16 h after UV irradiation, respectively. EGCG treatment reduced UVA-induced skin damage (roughness and sagginess) and protected from the decrease of dermal collagen in hairless mouse skin. EGCG treatment blocked the UV-induced increase of collagen secretion and collagenase mRNA level in fibroblast culture. The nuclear transcription factors NF-kappaB and AP-1 binding activities were also inhibited by EGCG treatment.

Animals↗
PubMedDate not supplied

The comparative molecular study between Bombycidae and Saturniidae based on mtDNA RFLP and cytochrome oxidase I gene sequences: implication for molecular evolution.

The phylogenetic relationships between Bombyx mori and Bombyx mandarina species of Bombycidae, and Antheraea yamamai and Antheraea pernyi species of Saturniidae were investigated based on mtDNA RFLP and cytochrome oxidase I gene. The sizes of the mtDNA of all the species were estimated at approximately 16 kbp +/- 500 bp by total length of all the restricted fragments and no variation in size was recognized. Of the fourteen different restriction endonucleases used, BamHI, HindIII, PstI, EcoRI and XbaI showed RFLP. Among these, only HindIII showed RFLP between B. mori and B. mandarina. A comparative analysis of sequences was also conducted with the mitochondrial cytochrome oxidase I genes of each species. The results indicated that B. mori shared a 97%, 85% and 87% sequence identity with B. mandarina, A. yamamai and A. pernyi, respectively. B. mandarina shared a 87% and 88% sequence identity with A. yamamai and A. pernyi, respectively. A. yamamai shared 92% sequence identity with A. pernyi. The results of the phylogenetic analysis exhibited monophyly and confidence limits of more than 99% in all trees for both Bombycidae and Saturniidae.

Animals↗