[Effect of thermal conductivity on apical sealing ability of 4 dental gutta-percha cones].

OBJECTIVE: To investigate the effect of thermal conductivity on the apical sealing ability of different dental gutta-percha cones during the warm vertical condensation obturation. METHODS: Four kinds of dental gutta-percha cones were used in this study: Bio-GP points (BP, B&L, Korea), large-tapered gutta-percha (DP, DENTSPLY, America), PROTAPER Universal gutta-percha points (DPP, DENTSPLY, America) and mtwo gutta-percha points (VP, VDW, Germany). Volume differences method was used to determine the main components and the thermal conductivity determinator was used to measure the thermal conductivity of these dental gutta-percha cones. Furthermore, 20 cones randomly selected from each kind of dental gutta-percha cones. And 10 cones of each dental gutta-percha cones, which were cut out the part of 4 mm in length from the apical end, were heated (200 °C) from the upper end without compression, and the temperature of the gutta perchacones surface was monitored in time by the infrared thermal imager during the whole heating process. In addition, the rest of the 10 cones of each dental gutta-percha cones were used to obturate the root canal in the transparent root canal resin model using warm vertical condensation technique. The cross-sectional surface was observed by stereomicroscope (× 40) at 1 mm and 3 mm from the working length and the gutta-percha obturation area proportion was measured and analyzed. The data were analyzed by one-way ANOVA. RESULTS: The proportion of inorganic fillers (80.90%±1.14 %) (P<0.05) and the thermal conductivity (2.247±0.002) of DP was significantly higher than BP (79.28%±3.88%, 1.179±0.003), DPP (68.46%±5.09%, 0.604±0.001), VP (78.86%±1.87%, 1.150±0.001) (P<0.05). During the thermal obturation without compression at the setting temperature (200 °C), DP could achieve 65 °C beyond 1 mm from the heating point, and BP, DPP and VP only reached 65 °C within 1 mm. After warm vertical condensation obturation, all the groups showed increased gutta-percha obturation area proportion. At the position of WL-3, DP (96.89%±0.03%) showed significantly higher proportion of gutta-percha obturation area than BP (95.47%±0.06%), DPP (95.21%±0.03%) and VP (95.15%±0.03%) (P<0.05). CONCLUSION: DP contains more inorganic fillers, possesses higher thermal conductivity, and leads a better apical sealing ability than BP,DPP and VP at the position of WL-3 during warm vertical condensation obturation.

A changes in hyoid bone position after orthodontic treatment of patients with mandibular deviation.

OBJECTIVES: The aim of this study was to observe the influence of orthodontic treatment on the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations. METHODS: A total of 60 patients with mandibular deviations, including 30 males and 30 females with a mean age of 15.4 years, were recruited. They were equally divided into average angle, high angle, and low angle groups, with a 1:1 gender ratio. Their hyoid position was measured before and after orthodontic treatment. The data were analysed using paired t-tests and analysis of variance (ANOVA). RESULTS: After treatment, the hyoid body in the high angle group presented significant forward and upward movements (p = 0.012 and p = 0.005). The hyoid body in the low angle group exhibited significant forward movement (p = 0.048) and a significant increase in the hyoid inclination (p = 0.00). In the average angle group, the hyoid body significantly moved downward (p = 0.031) and the thyrohyoid moved upward (p = 0.046). The ANOVA showed that orthodontic treatment significantly influenced the vertical position and inclination degree of the hyoid (F = 6.37, p = 0.003; F = 6.204, p = 0.004; and F = 3.393, p = 0.025). The average angle group displayed significant differences in these indices compared with the high angle and low angle groups. Orthodontic treatment significantly influenced the mandibular plane angle in the high angle group (p = 0.012). CONCLUSION: Orthodontic treatment influences the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations by varying degrees.

An indirect ELISA for serodiagnosis of cattle footrot caused by Fusobacterium necrophorum.

A serodiagnostic ELISA (rL-ELISA) using recombinant truncated leukotoxin protein PL2 (aa 311-644) of Fusobacterium necrophorum as antigen was developed for detection of antibodies against F. necrophorum from cattle footrot. In rL-ELISA, the recombinant diagnostic antigen showed no cross-reaction with antisera against bovine foot and mouth disease virus, bovine rhinotracheitis virus, bovine viral diarrhea virus, bovine rotavirus type A, bovine Escherichia coli, and bovine Salmonella. The rL-ELISA could confirm the existence of antibodies against F. necrophorum at day 7 after infection. Detection of the field samples indicated relative sensitivity of rL-ELISA to nL-ELISA using the purified native leukotoxin A as antigen was 96.43%, and relative specificity of rL-ELISA to nL-ELISA was 94.26%. These data demonstrated the rL-ELISA would have a potential use for early diagnosis of cattle footrot caused by F. necrophorum.

Encapsulation of phytosterols and phytosterol esters in liposomes made with soy phospholipids by high pressure homogenization.

Phytosterols and phytosterol esters were encapsulated within large unilamellar liposomes prepared with soy phospholipids using a microfluidizer. The average particle diameter of these liposomal vesicles increased with increasing amounts of encapsulated phytosterols, especially with increasing free sterol content. The phytosterol content, liposomal particle size, and phytosterol encapsulation efficiency started to plateau when liposomes were prepared with MOPS buffer dispersions that contained 50 mg ml-1 soy phospholipid and more than 4% phytosterol blend, suggesting the saturation of phytosterol encapsulation. We proposed an encapsulation mechanism of free sterols and phytosterol esters in liposomes, where free sterols were mainly encapsulated within the lumen of these liposomes as crystals, and sterol esters and some free sterols were incorporated within the phospholipid bilayer of the liposomal membrane. The results from this work could provide the pharmaceutical and nutraceutical industries a practical method to produce loaded liposomes using inexpensive phospholipid mixtures for the delivery of bioactive ingredients.

Cytotoxicity and altered c-myc gene expression by medical polyacrylamide hydrogel.

Medical Polyacrylamide Hydrogel (PAMG)has been used in plastic and aesthetic surgery for years. However, its safety is still in doubt in many countries. In the current research, first an approach, using high performance liquid chromatography (HPLC), to determine the amount of residual acrylamide monomer (AM) in the PAMG was presented. Then the cytotoxicity of PAMG was investigated using cell counting and methyl thiazolyl tetrazolium (MTT) assay. To explore the mechanism of this toxicity, normal human fibroblasts cultured in medium extracts were analyzed. Membrane changes and other related parameters were investigated using flow cytometry (FCM). Real time fluorescent polymerase chain reaction (real time PCR) was also introduced to determine the biological response of the fibroblasts. During this process, three representative genes (p53, beta-actin, and c-myc, which are tumor suppressor genes, housekeeping genes, and proto-oncogenes respectively) were selected for examination. Results indicated that a method based on HPLC is practical and simple for determining AM in PAMG. The detection limits can reach the desired ppb level, and so it can fully meet the requirements of the studies of PAMG. Polyacylamide Hydrogel inhibits the growth of human fibroblasts and may cause the apoptosis of human fibroblasts. Moreover, it can alter physical parameters such as the size and the granularity of these cells. Furthermore, these three genes have a relatively typical amplification plot and highly related, wide-range standard curves, and so this reaction system is definitely suitable for the semiquantification of these genes. PAMG induces the increase of the message ribonucleic acid (mRNA) expression of c-myc, while the p53 and beta-actin remain even. This change is not related to the concentration of AM in the gel and may be incited by other components in the extract of PMAG.

Advances in the application of food emulsifier α-gel phases: Saturated monoglycerides, polyglycerol fatty acid esters, and their derivatives.

Emulsifiers form complex structures in colloidal systems. One of these structures, the α-gel phase, has drawn much research interest. α-gel phases are formed by emulsifiers that are stable in the α-crystalline structure in the presence of water. The α-gel phase has shown superior functionality in a variety of applications because it has a water-rich lamellar structure. Even though studies on emulsifier α-gel phases emerged over half a century ago, there is still a knowledge gap on fundamental properties of α-gel phases formed by a variety of emulsifiers. This article summarizes recent studies on the physical and chemical properties of α-gel phases formed by several food emulsifiers, specifically saturated monoglycerides, polyglycerol monoester and diesters of fatty acid, and sodium stearoyl lactylate. Recent research has advanced the understanding of factors affecting the stability and foamability of the α-gel phases. Current and potential applications of α-gel phases in baked food products and in personal care products are also reviewed here.

Age estimation using a modified HPLC determination of ratio of aspartic acid in dentin.

Diastereomeric dipeptides were derived from the amino acid enantiomers in dentin by O-phthalaldehyde-N-acetyl-L-cysteine. The products were separated using high performance liquid chromatography (HPLC) and detected by fluorescence detector. A short analysis time (total analysis time was 15 min, including retention time, sample derivatization time and column regeneration time) was used. The sensitivity of detection was 1 pmol and high resolution (Rs = 1.5) was reached. We determined the D/L ratio of aspartic acid in dentin of 28 first premolars. The correlation value between the D/L ratio of aspartic acid and actual age was 0.9887; errors of +/- 1 year accounted for 46.4%, and no error exceeded 5 years.

Demineralized bone matrix as an alternative for mastoid obliteration and posterior canal wall reconstruction: results in an animal model.

HYPOTHESIS: This study was conducted to evaluate the use of Grafton human demineralized bone matrix as a graft material for mastoid cavity obliteration and canal wall reconstruction in an animal model. BACKGROUND: Canal wall down procedures in the treatment of cholesteatoma may result in a problematic mastoid cavity. Elimination of the mastoid cavity by obliteration or canal wall reconstruction can prevent or correct this problem. Many techniques and implant materials have been used for this application, yet no single material has proven to be ideal. METHODS: Athymic rats received tympanic bulla obliteration and lateral bulla wall reconstruction utilizing the Grafton Putty and Flex formulations, respectively. Wound healing was monitored twice a week. Auditory brainstem evoked responses were obtained 8 weeks after implantation. Nine weeks after implantation, the animals were killed, and histologic sections were prepared. A histologic bone formation score (range 0-4) was determined for each implant. RESULTS: Wound healing occurred without complication. Auditory brainstem response thresholds (average 23.5) fell within the normal range for all ears tested. The average histologic bone formation score for all implants was 3.7. The average scores for obliteration implants and wall reconstruction implants were 3.5 and 3.9, respectively. All wall reconstruction implants underwent partial or total collapse into the bulla. CONCLUSIONS: The high level of bone formation obtained by the use of Grafton implants in this study makes this material a promising resource for use in mastoid obliteration. The use of the material for canal wall reconstruction will likely require a sturdier preparation to prevent collapse into the mastoid cavity.

Incorporation of horseradish peroxidase in a Kieselguhr membrane and the application to a mediator-free hydrogen peroxide sensor.

Horseradish peroxidase was incorporated in a kieselguhr membrane. The electron-transfer process of the enzyme was examined by cyclic voltammetry. It was observed that the electron-transfer reactivity of horseradish peroxidase was greatly enhanced, and that direct electrochemistry was accordingly feasible. Using the merits of the direct electron-transfer reactivity of horseradish peroxidase and its specific enzymatic catalysis towards hydrogen peroxide, an unmediated hydrogen peroxide biosensor was constructed. The calibration plot of this hydrogen peroxide sensor was linear in the range of 2.0 x 10(-6) mol/L - 6.5 x 10(-4) mol/L. The relative standard deviation was 4.1% for 6 successive determinations at a concentration of 1.0 x 10(-4) mol/L. The detection limit was 1.0 x 10(-6) mol/L.

Prevalence and treatment of Pediculus capitis infestation among aboriginal school children in northern Taiwan.

In the present study, pediculosis was investigated among a total of 2,725 children from 35 primary schools in Hsiulin District of Hualien County, Jenai District of Nantou County, Wulai District of Taipei County, Chienshih District of Hsinchu County, Fushing District of Taoyuan County, and Nanao District of Ilan County. The overall infestation rate was 12.8%. The rates by districts were 19.7%, 17.3%, 16.7%, 15.1%, 7.9%, and 3.0%, respectively. The pediculicides including Nix (permethrin 1%) 56 gm/tube, Para aerosol (bioallethrin 0.66%) 90 gm/tube, and Perioderm (malathion 1%) cream shampoo 40 gm/tube were used to treat the head louse infestation in 83, 91, and 103 children; the cure rates were 97.3%, 94.1%, and 93.4%, respectively. No significant differences were found in these rates. The reactions were slight and transitory. A total of 636 lice was collected from the hair using fine-toothed combs before treatment and from the used towels after treatment of children in Wulai, Chienshih, Hsiulin, and Jenai Districts. Each child was found infested with a mean of 7.7 lice. The mean intensity of infestation was highest in Jenai (9.3) and Chienshih (8.7) came next. Wulai (3.7) and Hsiulin (3.6) had lower intensities.

[An experimental study on F-heparin surface modified IOLs implanted into the Rhesus monkeys' eyes].

OBJECTIVE: To evaluate the biocompatibility of F-heparin surface modified IOLs. METHODS: 13 monkeys were divided into 3 groups, and implanted with different surface modified and non-modified IOLs into their eyes. All of the eyes were examined by slitlamp microscope and Schiötz tonometer at postoperative 15, 30, 60, 90 and 180 days. Postoperatively, at different periods the aqueous was aspirated from the anterior chamber to calculate cells. RESULTS: F-heparin surface modified IOLs induced milder inflammatory reaction and less dense posterior capsula opacification (PCO) than non-modified IOLs. CONCLUSION: F-heparin surface modified IOL has a better biocompatibility.

[A new genus of oral bacteria in human].

A strain, No. 90-1, is isolated from the oral cavity of a patient with periodontophthy. This strain is a Gram-positive, non-endospore-forming, facultative anaerobe with spherical cells, 0.9-1.5 microns in diameter, occuring in pairs and seldom in short chains of four cells, and motile by one flagellum per cell. The optimum growing temperature is 35-37 degrees C; appreciable growth is not found below 10 degrees C, but growth at 53 degrees and tolerance to 60 degrees C for 30 min. This strain is microhalophilous and grows best, well and poorly in the medium containing 2%, 10%-15% and 25% NaCl respectively. Catalase and urease are positive and nitrate is reduced. Acid is produced from many carbohydrates, but no gas. Gelatin can be hydrolyzed, but starch, cellulose and dextrin do not. G + C content in DNA is 41.34 mol%(Tm). The strain(90-1) is considered to be a new species belonging to a new genus because its some characteristics are different from those of the known coccus genuera and designated as Stomatostreptococcus microhalophilus Ping, Zhou, Sun et Fan gen. nov. sp. nov. according to its source and microhalophilic trait.

[The research fields and advances of biomedical engineering].

The research fields and advances of biomedical engineering have been reviewed in four aspects, biomedical material, biomedical engineering appliance, tele-diagnostic system and biomedical recovery engineering with 14 references.

Synthesis, characterization and biocompatibility of poly(2-ethyl-2-oxazoline)-poly(D,L-lactide)-poly(2-ethyl-2-oxazoline) hydrogels.

A novel thermoreversible hydrogel based on poly(2-ethyl-2-oxazoline)-derived amphiphilic triblock copolymer, poly(2-ethyl-2-oxazoline)-poly(D,L-lactide)-poly(2-ethyl-2-oxazoline) (PEOz-PLA-PEOz), was developed. The synthesis of PEOz-PLA-PEOz was carried out by coupling monohydroxylated PEOz-PLA diblocks with adipoyl chloride as coupling agent and dimethylamino pyridine as catalyst. The tube inverting and rheological tests showed that triblock copolymers had sol-gel-sol transition behavior with increasing temperature, and the gelation was found to be thermoreversible. The critical gelation concentration, the sol-gel transition temperature at a given concentration depended on the EOz/LA ratio and the molecular weight of PEOz. Scanning electron microscopy observation revealed that the resultant bulky gel exhibited an interconnected porous three-dimensional (3D) microstructure after freeze-drying. In addition, the hydrogels showed good cytocompatibility in vitro. MTT assays revealed that the human skin fibroblast cells encapsulated within the hydrogels were viable and proliferated inside the 3D scaffold. This newly described thermoreversible hydrogel demonstrated attractive properties to serve as cell matrix for a variety of tissue engineering applications or pharmaceutical delivery vehicles.

Changes in hyoid bone position after orthodontic treatment of patients with mandibular deviation / Cambios en la posición del hueso hioides después del tratamiento ortodóntico de pacientes con desviación mandibular

OBJECTIVES: The aim of this study was to observe the influence of orthodontic treatment on the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations. METHODS: A total of 60 patients with mandibular deviations, including 30 males and 30 females with a mean age of 15.4 years, were recruited. They were equally divided into average angle, high angle, and low angle groups, with a 1:1 gender ratio. Their hyoid position was measured before and after orthodontic treatment. The data were analysed using paired ttests and analysis of variance (ANOVA). RESULTS: After treatment, the hyoid body in the high angle group presented significant forward and upward movements (p = 0.012 and p = 0.005). The hyoid body in the low angle group exhibited significant forward movement (p = 0.048) and a significant increase in the hyoid inclination (p = 0.00). In the average angle group, the hyoid body significantly moved downward (p = 0.031) and the thyrohyoid moved upward (p = 0.046). The ANOVA showed that orthodontic treatment significantly influenced the vertical position and inclination degree of the hyoid (F = 6.37, p = 0.003; F = 6.204, p = 0.004; and F = 3.393, p = 0.025). The average angle group displayed significant differences in these indices compared with the high angle and low angle groups. Orthodontic treatment significantly influenced the mandibular plane angle in the high angle group (p = 0.012). CONCLUSION: Orthodontic treatment influences the hyoid position of patients with different vertical skeletal craniofacial patterns of mandibular deviations by varying degrees.

OBJETIVOS: El objetivo de este estudio fue observar la influencia del tratamiento ortodóntico en la posición hioidea de pacientes con diferentes patrones craneofaciales esqueléticos verticales de desviaciones mandibulares. MÉTODOS: Se reclutaron un total de 60 pacientes con desviaciones mandibulares, incluyendo 30 hombres y 30 mujeres con una edad media de 15.4 años. Los pacientes fueron divididos a partes iguales en grupos de ángulo promedio, ángulo alto, y ángulo bajo, con una proporción de género de 1:1. Su posición hioidea fue medida antes y después del tratamiento ortodóntico. Los datos se analizaron mediante pruebas t pareadas y análisis de varianza (ANOVA). RESULTADOS: Luego del tratamiento, el cuerpo del hioides en el grupo de ángulo alto presentó movimientos significativos hacia adelante y hacia arriba (p= 0.012 y p= 0.005). El cuerpo del hioides en el grupo de bajo ángulo exhibió avance significativo (p = 0.048) y un aumento significativo en la inclinación del hioides (p = 0.00). En el grupo de ángulo promedio, el cuerpo del hioides se movió significativamente hacia abajo (p = 0.031) y el tirohioideo se movió hacia arriba (p = 0.046). El Orthodontic Treatment of Patients with Mandibular Deviation análisis de ANOVA mostró que el tratamiento ortodóntico influye significativamente sobre el grado de inclinación y posición vertical del hioides (F = 6.37, p = 0. 003; F = 6.204, p = 0.004 y F = 3.393, p = 0. 025). El grupo de ángulo promedio mostró diferencias significativas en estos índices en comparación con los grupos de ángulo bajo y ángulo alto. El tratamiento ortodóntico influyó significativamente en el ángulo del plano de la mandíbula en el grupo de alto ángulo (p = 0.012). CONCLUSIÓN: El tratamiento ortodóntico influye en la posición hioidea de pacientes con diferentes patrones craneofaciales esqueléticos verticales de desviaciones mandibulares de diversos grados.

[The ultrastructure changes of nerve fibers in pressure side of periodontal ligament during orthodontic tooth movement in rats].

OBJECTIVE: To observe the ultrastructure changes of nerve fibers in pressure side of periodontal ligament during orthodontic tooth movement (OTM) in rats. METHODS: The left maxillary of fifteen rats molar was moved mesially by an appliance for 2 days, 1 week, 2 weeks and 3 weeks. The ultrastructure changes of nerve fibers in pressure side of the periodontal ligament in rats were observed with electron microscope. RESULTS: The thick myelinated axon was degenerated after 2 days of OTM and not recovered after 3 weeks of OTM; the number of thin unmyelinated axons was increased after 2 days of OTM. It reached a maximum after 1 week of OTM and recovered after 3 weeks of OTM. Only part of thin unmyelinated was slightly degenerated. At the same time, some of the thin myelinated axons were slightly degenerated and partly demyelinated. CONCLUSION: The nerve fibers were involved in periodontal tissue remodelling.

[Identification of synthetic adhesives by simultaneous pyrolysis methylation gas chromatography].

At present, pyrolysis gas chromatography (Py-GC) is an effective analytical method for trace synthetic adhesives. Synthetic adhesives are usually composed of polar components. Thus, the polar pyrolysis products are normally difficult to measure by Py-GC due to their partial or complete adsorption in the pyrolysis zone, injection system or capillary column and the accuracy of results is seriously affected. Simultaneous pyrolysis methylation gas chromatography (Py-Me-GC) is a fast analytical method which was developed in recent years for polar compounds. The five synthetic adhesives have been identified by using Py-Me-GC in our study. Analytical conditions were: filament pyrolysis apparatus, flame ionization detector (FID), gas chromatograph, FFAP capillary column (30 m x 0.25 mm i.d.) and a quaternary ammonium salt as methylating agent. Major peaks of the products of pyrolysis were analysed qualitatively by GC/MS and comparisons were also made between the results by Py-Me-GC and those by Py-GC. The information gained from the components of substances by Py-Me-GC is more than that by Py-GC. The method is suitable for identifying synthetic adhesives of trace evidence in forensic science.

Custom bifurcated stent-graft for abdominal aortic aneurysms: initial experience.

PURPOSE: To describe a custom bifurcated stent-graft for possible treatment of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: Five male patients (mean age, 76 +/- 6 years), who had AAA (mean diameter, 4.7 +/- 0.4 cm) and who were considered to be at high risk for conventional surgery, were treated with a custom modular bifurcated stent-graft constructed with bifurcated 24-mm x 12-mm (upper body diameter x iliac limb diameter) Cooley Veri-Soft Woven polyester grafts and Gianturco-Rösch Z stents. The stent-graft body was delivered through 20-22-F sheaths, and the contralateral iliac limb was delivered through a 16-F sheath by means of surgical exposure of the common femoral arteries. A flared distal limb extender (12 mm to 14 mm) was created for one patient to accommodate a large common iliac artery. RESULTS: Stent-grafts were successfully deployed without complications in all five patients. There were no proximal or distal leaks. A lumbar-to-inferior mesenteric artery leak was seen in one patient at 24 hours. At 6-month follow-up, all devices were intact, with complete exclusion and shrinkage of the aneurysm in four of five patients. Aneurysm size remained stable in the one patient with a lumbar-to-inferior mesenteric artery leak. CONCLUSION: A custom, bifurcated stent-graft was utilized for endovascular treatment of AAA. Long-term follow-up is necessary for the device.