Effect of PEG400 Concentration in Receiving Solution on Drug Transdermal Test in Vitro / 中国实验方剂学杂志

Objective: To investigate the effect of varying concentrations of polyethylene glycol(PEG)400 in receiving solution on in vitro transdermal test of drugs. Method: 5-Fluorouracil(5-FU) was selected as a model drug,by preparing different concentrations of PEG400-phosphate buffer solution(PBS) as the receiving solution,the receiving chamber did not add drug,the excised rat skins were treated with various additives for 12 h,then replaced by PBS and added the saturated model drug into the donor compartment to determine the transdermal parameters of the drug.Meanwhile,scanning electron microscopy(SEM) was employed to monitor the effect of PEG400 with different concentration on the stratum corneum of rat skin. Result: The 10%,15% and 40% PEG400-PBS groups had no significant effect on in vitro transdermal absorption parameters of the 5-FU.The steady transdermal rate and cumulative penetration rate of the drug in 20% and 30% PEG400-PBS groups were significantly higher than that in the PBS group(PPConclusion: In the rat skin transdermal test,the concentration of PEG400 in receiving solution should be controlled below 20%.

Protective effects of citric acid-disodium hydrogen phosphate rinsing solution on ocular surface of mice with acute chemically induced corneal burns / 中华实验眼科杂志

Background Immediately ocular rinsing is a key step for the prevention of eye tissue damage after acute chemical bums.A good ophthalmic rinsing solution can neutralize chemical substance and improve the prognosis of patients.Objective This study attempted to evaluate the therapeutic effect of self-made citric aciddisodium hydrogen phosphate buffer and citric acid-disodium hydrogen phosphate-potassium chloride buffer on corneal chemical burns in mice.Methods Citric acid-disodium hydrogen phosphate buffer solution (solution 1) and citric acid-disodium hydrogen phosphate-potassium chloride buffer solution (solution2) with the pH 7.4 were prepared.One hundred and twenty clean male C57 mice aged 6-8 weeks were randomized to two groups,and filter papers containing 1 mol/L H2SO4 or 0.15 mol/L NaOH were attached to the central corneas of the right eyes to create the acid or alkali burning models.Then the eyes were immediately rinsed by 40 ml solution 1,tap water or solution 2 according to the grouping and the model eyes without rinsing served as the control group.The corneal opacity was examined by slit lamp microscope and scored in 3,7 and 14 days after modeling.The percentages of corneal fluorescein staining,corneal neovascularization and corneal ulcer were analyzed.The study protocol was approved by Experimental Animal Ethic Commission of Second Military Medical University.Results In the corneal acid burning models,the number of eye with corneal opacity scored 1 in the solution 1 group,tap water group and solution 2 group was significantly more than that in the non-rinsing group in 3,7 and 14 days after modeling (all at P＜0.01);In 3 days after modeling,the numbers of eye scored 1 were more in the solution 1 group than those in the tap water group and solution 2 group (x2 =11.000,P =0.001;x2 =4.000,P =0.046).There were no differences in the eye number of different corneal opacity scores in 14 days after acid burning (all at P＞0.05).In 3,7 and 14 days after corneal alkali burning,the number of eyes with corneal opacity scored 1-2 was significantly increased in the solution 1 group,tap water group and solution 2 group compared with non-rinsing group (all at P＜0.01).The percentage of corneal ulcer in the solution 1 group,tap water group and solution 2 group was 7％,27％ and 13％,respectively,which was significantly lower than 73％ in the non-rinsing group (P =0.000,0.027,0.003),and no significant differences were seen in various time points after corneal alkali burning (all at P＞O.05).Corneal neovascularization occurred in 50％ mice in non-rinsing group in 14 days after acid burning.However,no neovascularization was seen in the mice of the solution 1 group,tap water group and solution 2 group in both acid and alkali burning mice.Conclusions Citric aciddisodium hydrogen phosphate buffer (pH 7.4) appears to be an effective emergency rinsing solution for corneal chemical burns and the rinsing solution with or without potassium chloride is not obviously affected to the prognosis of corneal chemical burns in the mice.

The influence of pH and lactic acid concentration on the formation of artificial root caries in acid buffer solution / 대한치과보존학회지

The purpose of this study is to compare and to evaluate the effect of pH and lactic acid concentration on the progression of artificial root caries lesion using polarizing microscope, and to evaluate the morphological changes of hydroxyapatite crystals of the demineralized area and to investigate the process of demineralization using scanning electron microscope. Artificial root caries lesion was created by dividing specimens into 3 pH groups (pH 4.3, 5.0, 5.5), and each pH group was divided into 3 lactic acid concentration groups (25 mM, 50 mM, 100 mM). Each group was immersed in acid buffer solution for 5 days and examined. The results were as follows: 1. Under polarized microscope, the depth of lesion was more effected by the lactic acid concentration rather than the pH. 2. Under scanning electron microscope, dissolution of hydroxyapatite crystals were increased as the lactic acid concentration increased and the pH decreased. 3. Demineralized hydroxyapatite crystals showed peripheral dissolution and decreased size and number within cluster of hydroxyapatite crystals and widening of intercluster and intercrystal spaces as the pH decreased and the lactic acid concentration increased. 4. Under scanning electron microscope evaluation of the surface zone, clusters of hydroxyapatite crystals were dissolved, and dissolution and reattachment of crystals on the surface of collagen fibrils were observed as the lactic acid concentration increased. 5. Under scanning electron microscope, demineralization of dentin occurred not only independently but also with remineralization simultaneously. In conclusion, the study showed that pH and lactic acid concentration influenced the rate of progression of the lesion in artificial root caries. Demineralization process was progressed from the surface of the cluster of hydroxyapatite crystals and the morphology of hydroxyapatite crystals changed from round or elliptical shape into irregular shape as time elapsed.

The influence of the degree of saturation of acidulated buffer solutions in the root dentin demineralization / 대한치과보존학회지

The purpose of this study is to compare and to evaluate the effects of the degree of saturation on the progression of artificial root caries lesion. A total of 8 human premolars without any defects and cracks selected and the cementum were removed and the teeth were cleaned with ultrasonic device and pumice without fluoride. Each tooth was sectioned into 6 pieces and they were ground with #800 sandpaper until they had a thickness of 200microm. Specimens were applied with nail vanish except for the 2-3 mm window area after application of bonding agent. Under the constant pH, the specimens were divided into 6 groups (degree of saturation; 0.1415, 0.1503, 0.1597, 0.1676, 0.1771, 0.1977). Each group was immersed in acid buffer solution for 1, 2, 3, 5 days under controlled temperature (25degrees C) and imbibed in water and examined using the polarizing microscope. The results were as follows 1. Although the degree of saturation of demineralization solution decreased, the depth of penetration in the dentin was constant. 2. Erosion was observed on the surface of all the teeth in the group I, II. In the group III, IV, V, surfaces were not changed. The teeth in the group VI showed the more mineralized surface but not the shape of the dentinal tubules distinctively. 3. In all groups, the lesion progressed rapidly at the first day of the experiment, but increased gradually as time elapsed.

A Pseudoepidemic of Alcaligenes xylosoxidans Due to Contaminated Buffer Solution / 병원감염관리

Background: A clinician reported unusually high incidence of A. xylosoxidans isolation from aspirated tissues in outpatient clinic. Methods: A. xylosoxidans isolates from January 2002 to June 2002 were investigated. The infection control nurse reviewed medical records and observed the procedures of tissue aspiration and culture at the clinical microbiology laboratory. Specimens were obtained for investigational cultures from dye, aspiration gun, slide alcohol sponge, tray, sink. water of sink, buffer solution, microscope, computer, and telephone. Results: A. xyloxosidans was isolated from twenty-four patients during 6 months. None of 24 cases had any typical signs or symptoms of infections by A. xylosoxidans. Observation of tissue aspiration and culture procedure revealed that buffer solution was used for prevention of specimen drying after tissue aspiration. Culture of the buffer solution yielded a heavy growth of A. xylosoxidans from four out of ten specimens. A. xylosoxidans was not isolated from any other investigational specimens. Conclusions: This was supposed to represent pseudoepidemic. Contaminated buffer solution was documented as the cause of this pseudoepidemic. The usage of buffer solution was stopped. During the follow-up period of 2 months, no additional A. Xylosoxidans was cultured from aspirated tissues.