EFFECTS OF ND:YAG LASER IRRADIATION AND FLUORIDE APPLICATION ON REMINERALIZATION OF THE ENAMEL (Nd:YAG 레이저 조사와 불화물 도포가 탈회법랑질의 재광화에 미치는 영향)
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- Journal of the korean academy of Pediatric Dentistry
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- v.31 no.3
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- pp.381-390
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- 2004
The purpose of this in vitro study was to investigate the effects of Nd:YAG laser irradiation and fluorides on acid drink demineralized enamel. The materials were 30 freshly extracted permanent premolars with intact smooth enamel surfaces. They were demineralized with Coca-cola at
Clostridium perfringens is both a ubiquitous environmental bacterium and a major cause of human gastrointestinal disease, and C. perfringens food poisoning ranks among the most common gastrointestinal diseases in developed countries. 120 isolates of C. perfringens were obtained from food-poisoning outbreaks in 2013~2014, Gyeonggi-do. Using PCR, all 120 isolates were identified as C. perfringens type A. Of the tested isolates, 49 isolates carried the cpe gene, 71 isolates carried the cpb2 gene. The outbreak cases of cpb2 and cpe /cpb2 genes were 7 and 7, whereas the outbreak cases of cpe-gene were 2. The epidemiological relationship between C. perfringens isolates has previously been investigated chiefly by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The genetics relatedness of the isolates raged from 53.5-100% and 75 district PFGE type were observed. The PFGE results revealed a wide genetic diversity among the 64 cpb2 carrying isolates (except 7 isolates), while 46 cpe-carrying isolates (except 3 isolates) showed a high genetic similarity. The MLST analysis revealed that 14 cpe isolates (cpe-chromosomal isolates) belong to a distinct cluster that is significantly distant from all the other cpb2 isolates (cpe-plasmid carrying and cpe-negative isolates). The isolates carrying a cpb2 appear to be rarely related, and are more variable than chromosomal cpe isolates. The results suggest that the cpe-positive outbreak isolates showed close genetic relation, whereas the cpb2-positive isolates revealed a wide genetic diversity.
Campylobacter jejuni is one of important food-borne pathogens causing human gastroenteritis. We isolated 42 strains of C. jejuni from diarrhea patients and 4 food-poisoning outbreaks in 2010, Gyeonggi-do. In this study, 42 strains were tested for genetic characteristics, the serotype distribution and antimicrobial resistant rate. The presence of hipO (100%), cdtB (100%), and mutated gyrA (95.2%) genes was detected in C. jejuni by polymerase chain reaction (PCR). Detection of mutated gyrA gene correlated with ciprofloxacin resistance. Forty isolates had mutated gyrA gene and were actually resistant to ciprofloxacin. Furthermore, comparing the gyrA DNA sequence data, ciprofloxacin-resistant isolates had a mutation of the DNA sequence from ACA (threonine) to ATA (isoleucine). But 41 strains (97.6%) of patient isolates were susceptible to erythromycin and azithromycin. A total of 35.7% among 42 C. jejuni isolates were identified into 4 different serotypes. The serotype distribution of C. jejuni strains were shown to be HS2(B), HS3(C), HS4(D), HS19(O). To investigate the genotypes of C. jejuni isolated in Gyeonggi province, repetitive sequence polymerase chain reaction (rep-PCR) analysis and SmaI-digested pulsed-filed gel electrophoresis (PFGE) profile analysis were performed. From the PFGE analysis of 42 C. jejuni strains, 12 clusters of PFGE profile were obtained. On the other hand, 11 clusters of rep-PCR profile were obtained from 42 strains of C. jejuni.
Diamond-like carbon (DLC) is a convenient term to indicate the compositions of the various forms of amorphous carbon (a-C), tetrahedral amorphous carbon (ta-C), hydrogenated amorphous carbon and tetrahedral amorphous carbon (a-C:H and ta-C:H). The a-C film with disordered graphitic ordering, such as soot, chars, glassy carbon, and evaporated a-C, is shown in the lower left hand corner. If the fraction of sp3 bonding reaches a high degree, such an a-C is denoted as tetrahedral amorphous carbon (ta-C), in order to distinguish it from sp2 a-C [2]. Two hydrocarbon polymers, that is, polyethylene (CH2)n and polyacetylene (CH)n, define the limits of the triangle in the right hand corner beyond which interconnecting C-C networks do not form, and only strait-chain molecules are formed. The DLC films, i.e. a-C, ta-C, a-C:H and ta-C:H, have some extreme properties similar to diamond, such as hardness, elastic modulus and chemical inertness. These films are great advantages for many applications. One of the most important applications of the carbon-based films is the coating for magnetic hard disk recording. The second successful application is wear protective and antireflective films for IR windows. The third application is wear protection of bearings and sliding friction parts. The fourth is precision gages for the automotive industry. Recently, exciting ongoing study [1] tries to deposit a carbon-based protective film on engine parts (e.g. engine cylinders and pistons) taking into account not only low friction and wear, but also self lubricating properties. Reduction of the oil consumption is expected. Currently, for an additional application field, the carbon-based films are extensively studied as excellent candidates for biocompatible films on biomedical implants. The carbon-based films consist of carbon, hydrogen and nitrogen, which are biologically harmless as well as the main elements of human body. Some in vitro and limited in vivo studies on the biological effects of carbon-based films have been studied [
The purpose of this study was to investigate the effects of Er : YAG laser on cutting efficacy and temperature changes of dentin. We used the dentin specimens of human premolars and molars which contain the physiologic saline and maintain the pulpal pressure in dentinal tubules. Each specimen was exposed to Er : YAG laser with non-contact handpiece type delivery system under different treatment condition of irradiation energy, pulse repetition rate, and exposure time. Two procedures were conducted by the presence of water flow during lasing. The specimens were grouped by thickness of dentin. We investigated the cavity pattern, volume, and temperature change of dentin specimen to determine the cutting efficacy and temperature rise of Er : YAG laser, and obtained following results. 1. Cutting volume of dentin was increased by increasing the irradiation energy, pulse repetition rate, and exposure time(P<0.05). 2. Margins of abulated cavities were sharp and clean and floors of cavities were conical in shape and showing smooth surfaces. Upper diameter of abulated cavities were increasing as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased. A few cracks were observed on abulated surfaces under treatment condition of laser parameter with 150mJ, 5Hz, and 5sec. 3. Temperature was increased as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased, and temperature rise was decreased as dentin thickness was increased(P<0.05). 4. Temperature rise was decreased under water flow compared with no water flow during laser exposure(P<0.05). From these results, we think that the method of using a Er:YAG laser would be effective and safe in cutting dentin for clinical application.
Background : Advanced chronic obstructive pulmonary disease is characterized by progressive pulmonary hypertension leading to right heart dysfunction, which plays a Important role in clinical evaluation but remains difficult and challenging to quantify. The noninvasive doppler echocardiographic value referred to as the Tei index has been suggested as a simple, reproducible and reliable parameter of the right ventricular function. The purpose of this was to assess the right ventricular function in patients with chronic obstructive pulmonary disease using the Tei index and to evaluate its relationship with the pulmonary functional status. Methods : The study population comprised of 26 patients with chronic obstructive pulmonary disease and 10 normal control subjects. The Tei index was obtained by dividing the sum of the isovolumetric contraction and the relaxation times by the ejection time using a pulsed-wave doppler. It was compared with the other available Doppler echocardiographic parameters of systolic or diastolic function and with the pulmonary function of the patients. Results : The Tei indices of the patients with COPD were significantly higher than those of normal subjects(
A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens Makino in Korea. Based on physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bacterial strain was identified as Pseudomonas aurantiaca. The bacteria also inhibited mycelial growth of several plant fungal pathogens such as Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani on PDA and 0.1 TSA media. The antifungal activity was found from the culture filtrate of this isolate and the active compound was quantitatively bound to XAD adsorption resin. The antibiotic compound was purified and identified as phenazine-l-carboxylic acid on the basis of combined spectral and chemical analyses data. This is the first report on the production of phenazine-l-carboxylic acid by Pseudomonas aurantiaca.
In this study, two cases of food poisoning caused by Salmonella that occurred in Gyeongsangnam-do in September 2021 are reported. One of the outbreaks occurred in a school and the other in a company. The molecular epidemiological characteristics of the isolated strains in the two outbreaks were analyzed. In the case of the school outbreak, 29 (4.9%) of 588 individuals experienced diarrhea and abdominal pain. As a result of a test of 36 individuals (patients, n=29; cook workers, n=7), Salmonella enterica serotype Enteritidis was detected in 17 (47.2%) patients, suggesting this serotype was the principal cause. Meanwhile, Salmonella spp. were not detected in 35 food and environmental samples. In the company outbreak, 87 (3.0%) of 2,900 individuals who had intaked from the same source experienced diarrhea, abdominal pain, and fever. In a test of 50 individuals (patients, n=40; cook workers, n=10), S. Enteritidis was detected in 28 patients (56.0%). Also, Vibrio cholerae (NAG) was detected in four patients with S. Enteritidis, and V. cholerae (NAG) only was detected in one patient. Salmonella spp. were not detected in 118 preserved foods, but S. Enteritidis was detected in one eaten food (toast) delivered in group by the company. Through PFGE genetic homology analysis of the isolated strains, all S. Enteritidis detected in patients and consumed foods were the same type. It seems that these S. Enteritidis isolates were the same type as detected in a previous school outbreak and in patients of group food poisoning in other regions, leading to an enhanced problem of food poisoning and epidemiology. Our analytic results can provide data for epidemiological management and food poisoning prevention based on molecular characteristics.
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70
The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70