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Biomedical subjects

R S Chen

Publications and source records attributed to R S Chen.

At least 19 recordsLinked to original sources
PubMed1992

Gender differences in the learning status of diabetic children.

The learning status of 95 diabetic boys and girls and 97 matched controls was evaluated using the Wechsler Intelligence Scale for Children--Revised IQ factors and school histories. Of interest was whether diabetic boys would evidence more learning difficulties. Results indicated that diabetic boys had significantly lower Freedom From Distractibility scores compared with scores of diabetic girls and control Ss and lower Perceptual Organization scores compared with scores of control boys. Although group scores were still within the average range of functioning, a significantly high percentage of diabetic boys (40%) compared with diabetic girls (16%) had learning problems that warranted either special instructional services or grade retention. Diabetic children experienced more learning difficulties (24%) than controls (13%), supporting research findings that diabetes is associated with increased risk of learning problems.

Adolescent↗
PubMed1991

[In vitro effect of topical fluoride gels on the surface of composite resins].

This study was designed to compare the surface change in 6 brands of composite resins immersed in 4 topical fluoride gels of various pH. The result was evaluated by visual change in light reflectance and SEM. The findings were as follows: 1) five 4-minute immersions in acidic fluoride gels increased surface roughness and decreased the light reflectance of Prisma-Fil, Prisma APH, Brillant D and P-30, 2) Silux-Plus and Heliomolar were not affected by acidic fluoride gels, and 3) the surface texture of all resin samples was not changed when immersed in neutral fluoride gels. The findings suggested that a) neutral fluoride gels should be recommended for patients who have extensive composite restorations and require fluoride treatment, and b) when resin restoration is indicated, microfilled composite resin should be considered for patients who plan to use acidic fluoride gels.

Composite Resins↗
PubMed1990

[45Ca-uptake, mitochondrial protein bound Ca2+ and ultrastructural distribution of Ca2+ in some brain regions of mice during drug-induced analgesia].

After buprenorphine (Bup, 0.8 mg/kg ip) treatment 45Ca-uptake (cpm/mg fresh brain) in vivo by brain slices decreased from 589 +/- 12 and 486 +/- 12 to 522 +/- 14 and 408 +/- 10 and mitochondrial protein bound Tb3+ (Tb3+ relative fluorescent intensity) reduced from 41 +/- 5 and 32 +/- 2 to 30 +/- 3 and 22 +/- 2 in periaqueductal grey and hypothalamus, respectively. A large amount dense precipitate occurred in the myelin sheath and mitochondria in both regions. The 45Ca-uptake evoked by buprenorphine at 16 micrograms/40 microliter in vitro has the similar tendency with that in vivo. Treated by ruthenium red (20 micrograms/mouse ip or icv) before buprenorphine, the above-mentioned effects were all abolished. Similar results were obtained with morphine (Mor, 10 mg/kg ip) and verapamil (Ver, 8 micrograms/mouse icv) instead of buprenorphine and ruthenium red, respectively. These results suggest that Ca2+ transport across neuroplasmic membranes plays a mediator role in drug-induced analgesia.

Analgesics↗
PubMed1990

Prevalence of mottled enamel after 12 years of water fluoridation in Chung-hsing New Village.

The prevalence of mottled enamel (dental fluorosis) was investigated among children, aged 6 to 15 years, in Chung-hsing New Village and in Tsao-tun Village. The drinking water in Chung-hsing New Village has been fluoridated for 12 years at a level of 0.6 ppm, while the drinking water in Tsao-tun contains a negligible level of 0.08 ppm. The degree of mottled enamel was assessed by using Dean's Index and the Community Fluorosis Index (CFI), the latter being derived from Dean's Index for the purpose of comparison. In Dean's Index, 6 classes based on the severity of the mottling, are identified: normal, questionable, very mild, mild, moderate, and severe. The results showed that children in Chung-hsing had whiter teeth than those in Tsao-tun Village. In the fluoridated group, 5.8% of children fell into the "very mild" mottling category, as compared to 0.9% in Taso-tun, the control area. For the "mild" class, the rate was 1.9% for Chung-hsing New Village and 0.4% for Tsao-tun. With only one exception in Tsao-tun, none of the children in the two groups showed mottling in the "moderate" or "severe" classes. The Community Fluorosis Index (CFI) was 0.15 for the Chung-hsing group, indicating that the occurrence of mottled enamel is very low when compared with data from fluoridation programs in other countries. It is concluded that in Taiwan, a 0.6 ppm fluoride concentration in drinking water, which has previously been reported to be effective in prevention of dental caries, is associated with only negligible mottling of enamel. Even when mottling does occur, the degree is very mild and only small chalky spots can be seen on the teeth.

Adolescent↗
PubMed1989

Influence of water fluoridation on the eruption of permanent teeth in Chung-Hsing New Village, Taiwan.

Along with an evaluation of the effects of 12 years' water fluoridation in the prevention of caries, the present study was conducted to explore the influence of water fluoridation on the eruption of permanent teeth. The survey was carried out in fluoridated Chung-Hsing New Village and the control town of Tsao-Tun from October to December, 1984. Dental examinations were performed on 3,459 children Chung-Hsing New Village and 4,610 in Tsao-Tun, at ages ranging from 3 to 15 years. The results showed that in general, the mean tooth eruption time of girls was earlier than that of boys, and that teeth in the lower jaw emerge sooner than their homologues in the upper jaw, except for premolars. In both fluoridated and control areas the order of tooth eruption was very similar except for the teeth of girls in the upper jaw. The eruption sequence was first premolar, canine then second premolar in the girls of Chung-Hsing New Village, while first premolar, second premolar then canine in those of Tsao-Tun. By comparing the eruption time of permanent teeth in the children of fluoridated and control areas, it was found that they were very alike in general, the only difference being observed in the premolars of the sexes. The premolars of the children in the fluoridated area emerged in the oral cavity 2.5 to 4.5 months later than did their counterparts in the control area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Survival of Yersinia enterocolitica in the environment.

When Yersinia enterocolitica was introduced into soils (or physiological saline), very little decrease in the population was observed throughout the test period. If the soil was allowed to air dry slowly, only 0.1% (2.8 x 10(3) colony forming units/g of soil) of the original population added still remained viable by day 10. On the other hand, the introduced organisms disappeared rapidly in river water but their longevities could be extended significantly if a eucaryote inhibitor was added to the river water or the river water was passed through a 0.8-micron membrane filter to remove eucaryotic predators. Furthermore, the rapid decrease of the Yersinia population coincided with an increase in numbers of protozoans. However, when Yersinia was added to filter-sterilized river water or when small numbers of the organism, below the threshold level believed necessary for active predation to occur, were added to the river water, no response in predators was observed; nevertheless, the population of Yersinia still showed a continued decline. When the organism was introduced into sephadex-treated river water or groundwater, its survival improved significantly compared with its survival in nontreated water samples. Low ambient temperature dramatically increased its ability to survive in the aquatic environment. It is concluded that, in addition to the temperature factor, the longevity of Y. enterocolitica in river water is chiefly regulated by predators and toxin producers.

Animals↗
PubMed1988

Factors affecting the survival of pathogenic bacteria in subtropical river water.

The present study was carried out to determine the factors causing the disappearance of introduced Salmonella enteritidis, Staphylococcus aureus, and Vibrio cholerae in natural river water. When large numbers of the above organisms (final level 10(7)-10(8) CFU per ml) were added to river water, the decline of their numbers coincided with increasing numbers of protozoa. Furthermore, their survival was improved dramatically if the river water was amended with a eucaryote inhibitor. After comparing the survivals of the test organisms in physiological saline, filtered river water, and in dialysis tubes immersed in river water, the results suggested that for Salmonella, predation was the most significant factor which caused the decline of its population in natural river water; starvation and toxic materials played lesser roles. Staphylococcus and Vibrio were also vulnerable to predation and toxic materials have molecular weights larger than 12,000. In the natural environment, these three factors together could cause rapid disappearance of the introduced microorganisms.

Animals↗
PubMed1987

Role of calcium in electron-acupuncture analgesia and the developments of analgesic tolerance to electro-acupuncture and morphine.

Role of brain Ca2+ in electro-acupuncture analgesia and the development of analgesic tolerance to electro-acupuncture and morphine were studied. At the same time, the inhibition by protein synthesis inhibitors of the development of analgesic tolerance to electro-acupuncture was observed. The results showed that like morphine tolerance, the brain Ca2+ and cAMP levels in mice were enhanced with the development of analgesic tolerance to electro-acupuncture. After treatment with protein synthesis inhibitors anisomycin, actinomycin or cycloheximide the development of analgesic tolerance to electro-acupuncture was inhibited, and concurrently, the brain Ca2+ and cAMP levels in the animals greatly reduced. From the changes of brain Ca2+ and cAMP levels, the analgesic effects by electro-acupuncture, morphine and lanthanides seem to be very similar and share a mutual ion basis and the mechanism of action. So does the development of analgesic tolerance to electro-acupuncture and morphine. These findings also suggest that the inhibition induced by the inhibitors of the analgesic tolerance to electro-acupuncture and morphine may be related to synthesis of new peptides or RNA in brain.

Acupuncture Therapy↗
PubMed1987

The effect of water and ions on the energy band structure of periodic alpha-helical polypeptides.

The solvent structure around several periodic polypeptides in the alpha-helical conformation has been determined by Monte-Carlo simulations. The calculations of the water clusters have been performed in the presence and absence of Na+ ions. The resulting hydration shell has been used to calculate the band structure of the polymers in the effective field of the water molecules and ions. The results show that the maximum change of the band widths and the band gaps is about 0.7 eV in the presence of the hydration shell. The band positions are shifted by up to 4.1 eV in the presence of water molecules and ions. The results have been compared with the band structure results of periodic polypeptides in the beta-pleated sheet conformation.

Ions↗
PubMed1987

Survival of pathogenic bacteria in environmental microcosms.

The survival times of Salmonella enteritidis, Pseudomonas aeruginosa, Staphylococcus aureus, and Vibrio cholerae in natural soil and river water samples were monitored by using various differential media. S. aureus and V. cholerae failed to survive in samples of soil, groundwater, and river water with various degrees of eutrophication. The population of the introduced S. enteritidis remained fairly constant in all three samples of soils tested. In water samples, numbers of S. enteritidis and P. aeruginosa showed an initial rapid decline followed by a much lower rate of decrease. The results indicated that some allochthonous microorganisms, because of their insensitivity to various biotic and abiotic stresses, might persist for a long time in the environment and become a serious threat to public health.

Pseudomonas aeruginosa↗