Fecal carriage of carbapenem resistant Enterobacteriaceae among the intensive care unit patients

Background: The war against multidrug-resistant bacteria is challenging and of global concern. Hospitals are increasingly plagued by resistant gram negative pathogens. Bacteria of the family Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae are part of the normal human intestinal flora but are also often responsible for community- and healthcare-associated infections. These bacteria are prone to acquiring resistance genes.Methods: Rectal swabs/swabs from the peri-anal area of the patients who were admitted in the Intensive Care Unit (ICU) of the accident and emergency department of this teaching hospital. Swabs were collected first on day 1 of admission, then day 4, and thereafter weekly during the period of stay in the ICU. All the swabs were immediately inoculated into trypticase soy broth with one 10μg  meropenem disc and were incubated overnight at 35±2ºC, ambient air. Next day, the broth was vortexed, and then sub-cultured onto a MacConkey agar plate. On the third day, MacConkey agar plates were examined for lactose fermenting (pink-coloured) colonies. The representative isolated colonies were subjected to conventional antimicrobial susceptibility testing by the Kirby Bauer Disc diffusion method following the CLSI guidelines to know the susceptibility to carbapenem and other antimicrobial agents. Carbapenemase production was done by a Modified Hodge Test (MHT) and Imipenem-EDTA test.Results: Out of 89 patients, carbapenem resistant Klebsiella pneumoniae and E. coli isolates were recovered from 35 (39.3%) patients i.e. Klebsiella pneumoniae isolates from fifteen patients and carbapenem resistant E. coli isolates from twenty patients. Prevalence of carbapenemase producing isolates was found to be 1.42%.  Conclusions: Surveillance for CRE can definitely help reduce rates of healthcare associated infections.

Effect of 17% ethylenediaminetetraacetic acid irrigation on the dentin adhesion of Enterococcus faecalis / 华西口腔医学杂志

OBJECTIVE@#This work aims to uncover the promoting effect of 17% ethylenediaminetetraacetic acid (EDTA) irrigation on the dentin adhesion of Enterococcus faecalis (E. faecalis).@*METHODS@#Forty-eight half split samples and twelve dentin slices were randomly divided into three experimental groups and one control group. The experimental groups and the control group were soaked with EDTA in different time lengths and with normal saline, respectively. E. faecalis was inoculated, and its dentin adhesion was measured via scanning electron microscopy, confocal laser scanning microscopy (CLSM), colony forming unit counts, and histological Gram staining.@*RESULTS@#According to histological Gram staining, the depth showed no statistically significant differences between 1 min group and the control group, 1 min group and 3 min groups (P>0.05). E. faecalis intruded in the dentine tubules (measured by CLSM), and the thickness of the biofilm on the dentin surface and the colony numbers of experimental groups were greater than those of the control group (P<0.05). The differences between the three experimental groups were statistically signi-ficant (P<0.05).@*CONCLUSIONS@#EDTA (17%) irrigation can promote E. faecalis adhesion to dentin. This adhesion would in turn prolong EDTA treatment time.

Efficacy of sonic and ultrasonic irrigation devices in the removal of debris from canal irregularities in artificial root canals

Abstract Objective To evaluate the efficacy of different sonic and ultrasonic devices in the elimination of debris from canal irregularities in artificial root canals. Materials and Methods A resin model of a transparent radicular canal filled with dentin debris was used. Five groups were tested, namely: Group 1 - ultrasonic insert 15.02; Group 2 - ultrasonic insert 25/25 IRRI K; Group 3 - ultrasonic insert 25/25 IRRI S; Group 4 - sonic insert 20/28 Eddy on a vibrating sonic air-scaler handpiece; Group 5 - 20.02 K-file inserted on a Safety M4 handpiece. Two different irrigants (5% sodium hypochlorite and 17% EDTA) and 3 different times of activation (20, 40, and 60 seconds) were tested. Means and standard deviations were calculated and statistically analyzed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). Results No statistically significant differences were found between the two irrigants used. Group 4 removed more debris than the other groups (p<0.05). Groups 1, 2, and 3 removed more debris than group 5 (p<0.05). A statistically significant difference (p<0.05) was found for the time of activation in all groups and at all canal levels, except between 40 and 60 seconds in group 4 at coronal and middle third level (p>0.05). Conclusions No significant differences were found between 5% sodium hypochlorite and 17% EDTA. When the time of activation rises, the dentin debris removal increases in all groups. Both sonic and ultrasonic activation demonstrate high capacity for dentin debris removal.

Effectiveness of different endodontic irrigants against Enterococcus faecalis: an ex vivo study

Aim: To evaluate the effectiveness of different endodontic irrigants against Enterococcus faecalis (ATCC 29212). Methods: Seventy bovine mandibular incisors were prepared, inoculated with a bacterial strain for 60 days and divided into the following groups: positive control; negative control; 2.5% NaOCl; 17% EDTA; 0.2% chitosan; 2.5% NaOCl + 0.2% chitosan; and 2.5% NaOCl + 17% EDTA. The irrigation protocol was performed using an experimental peristaltic pump device, with the irrigating solutions circulating within the apparatus at a constant flow for 10 min. Paper-point samples were then collected from the root canals and immersed in 7 mL of brain heart infusion broth, followed by incubation at 37°C for 48 h. Bacterial growth was assessed by turbidity of the culture medium. Results: E. faecalis was present in all samples after the use of different irrigants. Conclusion: The different irrigants tested were not effective in completely eliminating dentin bacterial contamination with E. faecalis.

Root canal irrigants influence the hydrophobicity and adherence of Staphylococcus epidermidis to root canal dentin: an in vitro study

OBJECTIVES: To determine the effect of root canal irrigants on the hydrophobicity and adherence of Staphylococcus epidermidis (S. epidermidis) to root canal dentin in vitro. MATERIALS AND METHODS: Root dentin blocks (n = 60) were randomly divided into 4 groups based on the irrigation regimen: group 1, saline; group 2, 5.25% sodium hypochlorite (NaOCl); group 3, 5.25% NaOCl followed by 17% ethylenediaminetetraacetic acid (EDTA); group 4, same as group 3 followed by 2% chlorhexidine (CHX). The hydrophobicity of S. epidermidis to root dentin was calculated by cell surface hydrophobicity while the adherence was observed by fluorescence microscopy, and bacteria were quantified using ImageJ software (National Institutes of Health). Statistical analysis of the data was done using Kruskal-Wallis test and Mann-Whitney U test (p = 0.05). RESULTS: The hydrophobicity and adherence of S. epidermidis to dentin were significantly increased after irrigating with group 3 (NaOCl-EDTA) (p < 0.05), whereas in group 4 (NaOCl-EDTA-CHX) both hydrophobicity and adherence were significantly reduced (p < 0.05). CONCLUSIONS: The adherence of S. epidermidis to dentin was influenced differently by root canal irrigants. Final irrigation with CHX reduces the bacterial adherence and may impact biofilm formation.

Procedimentos de regeneração pulpar: avaliação longitudinal imune / Procedimentos de regeneração pulpar: avaliação imune / Pulpar regeneration procedures: Longitudinal imune assessment

O tratamento endodôntico em dentes com desenvolvimento radicular incompleto está relacionado a algumas dificuldades e limitações. Entretanto, apesar das dificuldades técnicas, a alta susceptibilidade à fratura de dentes com rizogênese incompleta representa o fator chave para a busca de novas modalidades terapêuticas. Adicionalmente, as deficiências estéticas e funcionais apresentadas pelas terapias reabilitadoras após a perda de um elemento dentário permanente em um paciente jovem, também são fatores importantes e estimuladores. Assim, fica evidente a necessidade de pesquisas que disponibilizem novas opções terapêuticas conservadoras, com resultados previsíveis. O estudo objetivou investigar a resposta imunoinflamatória de dentes submetidos a diferentes protocolos descritos na literatura para se executar a terapia endodôntica regeneradora. Para isso, a expressão de moléculas inflamatórias e fatores de crescimento/diferenciação celular expressos nos tecidos pulpares foram analisados em diferentes intervalos de tempo, utilizando-se um modelo murino desenvolvido para a presente pesquisa. 54 Camundongos Balb/C tiveram as câmaras pulpares de seus molares superiores abertas e, subsequentemente submetidas à pulpectomia. Os animais foram então divididos em 3 grupos: grupo Sangramento (Blood) ­ preenchimento do espaço pulpar com coágulo sanguíneo; grupo EDTA + Sangramento (EDTA + Blood) ­ irrigação dos canais com solução de EDTA a 17% por 1 min, seguido do preenchimento do espaço pulpar com coágulo sanguíneo; grupo Vazio (Empty) ­ espaço pulpar deixado vazio. Cada grupo foi composto por 18 animais. De cada grupo, 6 animais foram sacrificados nos intervalos de 7, 14 e 21 dias após os experimentos. Utilizando-se a análise da reação em cadeia da polimerase em tempo real (Real Time PCR) avaliou-se a expressão gênica das citocinas IL-1, TNF-ß, IL-10 e dos fatores de crescimento/diferenciação NGF, IGF e VEGF, comparando-se tais achados inter e extra-grupos, nos diferentes períodos de avaliação. Os resultados demonstraram as maiores expressões dos mediadores pró-inflamatórios no grupo Empty, assim como uma maior expressão de mediadores anti-inflamatórios no grupo experimental preenchido com o coágulo sanguíneo. O grupo EDTA + Blood evidenciou a maior expressão gênica de fatores de crescimento/diferenciação, em todos os períodos analisados, quando comparado aos demais grupos. Pode-se concluir que a irrigação com solução de EDTA a 17%, previamente ao preenchimento dos sistemas de canais radiculares (SCR) com o scaffold (coágulo sanguíneo), estimulou a expressão aumentada de mediadores relacionados ao sucesso da terapia endodôntica regenerativa. Adicionalmente, o modelo animal desenvolvido para a pesquisa mostrou-se eficaz para se analisar longitudinalmente a modulação imune que se processa nos tecidos pulpoperirradiculares após a instituição da terapia.(AU)

Endodontic treatment in teeth with incomplete root development is related to some difficulties and limitations. However, despite the technical difficulties, the high susceptibility to fracture of teeth with incomplete rhizogenesis represents the key factor for the search for new therapeutic modalities. Additionally, the aesthetic and functional deficits presented by rehabilitation therapies after the loss of a permanent dental element in a young patient are also important and stimulating factors. Thus, it is evident the need for research that offers new conservative therapeutic options, with predictable results. Aimed to investigate the immunoinflammatory response of teeth submitted to different protocols described in the literature to perform the regenerative endodontic therapy. For this, the expression of inflammatory molecules and cell growth/differentiation factors expressed in pulpal tissues were analyzed at different time intervals using a murine model developed for the present study. 54 Balb/C mice had the pulp chambers of their upper molars opened and subsequently submitted to pulpectomy (one tooth per animal). The animals were then divided into 3 groups: Bleeding group - filling of the pulp space with blood clot; EDTA + Bleeding group (EDTA + Blood) - irrigation of the channels with 17% EDTA solution for 1 min, followed by filling of the pulp space with blood clot; Empty - pulp space left empty (negative control). Each group consisted of 18 animals. From each group, 6 animals were sacrificed at 7, 14 and 21 day intervals after the experiments. Using real-time polymerase chain reaction (RT-PCR), the cytokines IL-1, TNF-ß, IL-10 and the growth/differentiation factors NGF, IGF and VEGF, comparing such inter and extra group findings in the different evaluation periods. The results showed the highest expressions of the pro-inflammatory mediators in the Empty group, as well as a greater expression of anti-inflammatory mediators in the Experimental group filled with the blood clot. The EDTA + Blood group evidenced the greater gene expression of growth / differentiation factors, in all periods analyzed, when compared to the other groups. It can be concluded that irrigation with 17% EDTA solution, prior to filling the root canals system with the scaffold (blood clot), stimulated the increased expression of detrimental mediators for the success of regenerative endodontic therapy. Additionally, the animal model developed for the research proved to be effective in longitudinally analyzing the immune modulation that occurs in octopus-periradicular tissues after the institution of therapy.(AU)

Cambios histomorfométricos en dentina al utilizar biomodificadores radiculares. Revisión sistemática / Histomorphometric changes in root dentine after using biomodifiers. A systematic review

Antecedentes: El éxito del tratamiento endodóntico depende de una óptima preparación biomecánica, la cual incluye la remoción del barro dentinario que se forma durante la instrumentación del conducto. Esta capa se adhiere a la superficie de la dentina, ocluye los túbulos dentinarios e impide la adhesión del material obturador. Debe ser removido por soluciones irrigadoras que causan cambios en la superficie dentinaria. Se han utilizado ácido etilendiaminotetracético (EDTA), ácido cítrico y tetraciclina como irrigantes. Objetivo: Identificar los cambios producidos en la dentina al aplicar EDTA, ácido cítrico y tetraciclina como agentes irrigadores, descritos en la literatura disponible. Métodos: En esta revisión sistemática se estudiaron los diferentes cambios histomorfométricos encontrados al utilizar biomodificadores radiculares sobre la estructura dentinaria, teniendo en cuenta el tiempo de aplicación y la concentración de las soluciones. La muestra consistió en 20 artículos seleccionados de 889 revisados, publicados entre 2009 y 2016. La medida global del resultado fue la diferencia estándar de la profundidad de desmineralización dentinaria, obtenida por los acondicionadores empleados. Resultados: De acuerdo con la literatura, la profundidad de desmineralización es directamente proporcional al tiempo de exposición y concentración de la solución después de su aplicación. Para otras variables, como el pH, no se contó con evidencia suficiente para hacer inferencias. Así, se sugiere que no existen las pruebas científicas suficientes para respaldar este tipo de estudio. Conclusiones: Los cambios que se presentan en la dentina al utilizar biomodificadores radiculares dependen del tiempo de aplicación y de su concentración.

Background: The success of endodontic therapy depends on an optimal biomechanical preparation, which includes removal of smear layer formed during root canal preparation. Smear layer adheres to the dentin surface and occludes the tubules, preventing the adhesion of the sealant material. It must be removed through irrigants that cause changes on the dentinal surface. Ethylenediaminetetraacetic acid (EDTA), citric acid, and tetracycline have been used as irrigants. Purpose: To identify changes in dentine after applying EDTA, citric acid, and tetracycline as irrigants, as described in available literature. Methods: In this systematic review, histomorphometric changes in dentin surface observed after using root biomodifiers, regarding application time and concentration of solution. The sample consisted of 20 articles selected from a population of 889 articles found and published between 2009 and 2016. The overall measure of results was the standard difference of dentinal demineralization depth, obtained for each solution. Results: According to the literature, the depth of demineralization is directly proportional to exposition time and concentration after application of the irrigant. Regarding other variables, such as pH, evidence was limited to draw conclusions. Thus, it is suggested there is not enough scientific evidence to support this type of study. Conclusions: Dentinal changes that occur after using root biomodifiers depend on the length of the application time and its concentration.

Analysis of clinical infection status of carbapenem-resistant Enterobacteriaceae / 国际检验医学杂志

Objective To investigate the clinical distribution of carbapenem-resistant Enterobacteriaceae(CRE)strains separated in this hospital and the situation of its production of carbapenem enzyme.Methods The production of carbapenem enzyme by CRE strains was confirmed by using modified Hodge test,the situation of the production of metallo-beta-lactamases by CRE strains was screened by using imipenem-EDTA double-disk synergy test,and the clinical distribution of CRE strains was retrospectively ana-lysed.Results 37 strains of CRE isolated in this laboratory were screened by using instrument method and verified by using disk diffusion (K-B)method.It showed an increasing trend from 2012 to 2014 in the amount of CRE strains.In terms of bacterial spe-cies,K.pneumonia(1 6 strains)was the main kind of carbopenems-resistant strains,followed by E.coli(6 strains),Ser.marcescens(6 strains)and E.cloacae(4 strains).CRE strains were mainly isolated from geriatric ward and intensive care unit(ICU).Sputum,u-rine and blood specimen were key sources of CRE strains.Modified Hodge test confirmed that 36 strains of CRE were the strains that can produce carbapenemase,including 4 strains of K.pneumonia,3 strains of E.cloacae,and 1 strain of E.asburiae,and strains producing metallo-beta-lactamases were confirmed by using imipenem-EDTA double-disk synergy test.Conclusion Elderly patients with underlying diseases are susceptible population of CRE hospital infection and are primary preventive targets.The principal mechanism of carbapenem-resistant CRE strains in this hospital is the production of carbapenemase and production of metallo-β-lac-tamases in a small number of strains.

Determination of Caffeic Acid Based on ZnO Nanoparticles Enhanced Luminol-EDTA Chemiluminescence / 分析化学

In the presence of ZnO nanoparticles ( ZnO NPs ) and EDTA, luminol could produce strong chemiluminescence ( CL) without any oxidant. Therefore, a new CL system was established based on luminol-EDTA-ZnO NPs. As caffeic acid could strongly inhibit the CL, a flow injection CL method for the determination of caffeic acid was proposed. Under the optimized conditions, the relative CL intensity was linear over the logarithm of concentration of caffeic acid ranging from 1 . 0í10-7 mol/L to 1 . 0í10-5 mol/L with the detection limit of 1. 8í10-8 mol/L (3σ). The relative standard deviation (RSD) for the determination of 4 . 0í10-7 mol/L caffeic acid was 3 . 5% ( n=11 ) . The new method was successfully applied to determine the caffeic acid content in the tablets with the recoveries in the range of 97%-101%.

Proposal of an Appropriate Decalcification Method of Bone Marrow Biopsy Specimens in the Era of Expanding Genetic Molecular Study

BACKGROUND: The conventional method for decalcification of bone specimens uses hydrochloric acid (HCl) and is notorious for damaging cellular RNA, DNA, and proteins, thus complicating molecular and immunohistochemical analyses. A method that can effectively decalcify while preserving genetic material is necessary. METHODS: Pairs of bilateral bone marrow biopsies sampled from 53 patients were decalcified according to protocols of two comparison groups: EDTA versus HCl and RDO GOLD (RDO) versus HCl. Pairs of right and left bone marrow biopsy samples harvested from 28 cases were allocated into the EDTA versus HCl comparison group, and 25 cases to the RDO versus HCl comparison group. The decalcification protocols were compared with regards to histomorphology, immunohistochemistry, and molecular analysis. For molecular analysis, we randomly selected 5 cases from the EDTA versus HCl and RDO versus HCl groups. RESULTS: The decalcification time for appropriate histomorphologic analysis was the longest in the EDTA method and the shortest in the RDO method. EDTA was superior to RDO or HCl in DNA yield and integrity, assessed via DNA extraction, polymerase chain reaction, and silver in situ hybridization using DNA probes. The EDTA method maintained intact nuclear protein staining on immunohistochemistry, while the HCl method produced poor quality images. Staining after the RDO method had equivocal results. RNA in situ hybridization using kappa and lambda RNA probes measured RNA integrity; the EDTA and RDO method had the best quality, followed by HCl. CONCLUSIONS: The EDTA protocol would be the best in preserving genetic material. RDO may be an acceptable alternative when rapid decalcification is necessary.

Smear layer removal efficacy of different irrigating solutions: A comparative scanning electron microscope evaluation.

Aims: Comparative evaluation of cleaning efficacy of smear layer removal by different irrigating solutions such as 2.5% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA) with 2.5% NaOCl, 10% citric acid with 2.5% NaOCl and 1% tetracycline Hydrochloride (HCl) with 2.5% NaOCl for smear layer removal in the apical third of root canal. Settings and Design: In vitro material science study. Materials and Methods: Seventy-five single rooted permanent maxillary central incisor teeth were subjected to standardized root canal instrumentation (crown down technique). The teeth were randomly divided into five groups with 15 teeth in each groups: (1) Normal saline (n = 15) (2) 2.5% NaOCl (n = 15) (3) 17% EDTA + 2.5% NaOCl (n = 15) (4) 10% citric acid + 2.5% NaOCl (n = 15) (5) 1.0% tetracycline HCL + 2.5% NaOCl (n = 15). After final irrigation, the teeth were prepared for scanning electron microscope analysis to evaluate the cleaning of apical third of radicular dentine to determine the presence or absence of smear layer. Statistical Analysis Used: The results were analyzed by nonparametric statistical analysis techniques. Kruskal-Wallis test, Mann-Whitney test and Chi-square tests were carried out. Results: There was no significant statistical difference in the efficacy of smear layer removal when 2.5% NaOCl was compared with 17% EDTA with 2.5% NaOCl, 10% citric acid with 2.5% NaOCl and 1% tetracycline HCl with 2.5% NaOCl in apical third of root canals. Conclusions: The present study suggests that irrigating agents, citric acid and tetracycline HCl can be used as an alternative to EDTA for the removal of smear layer in endodontics.

Blood clot stabilization on root dentin conditioned by the combination of tetracycline and EDTA

AIM: To assess the combined use of tetracycline (TTC) and ethylenediaminetetraacetic acid (EDTA) on clot formation, considering that EDTA may neutralize TTC acidity. METHODS: Planed human tooth roots were treated with saline solution, EDTA, TTC and their combination (EDTA followed by TTC and TTC before EDTA). Fresh human blood was applied on the conditioned surfaces to check clot adhesion and stabilization. A previously calibrated (kappa = 0.93) and blinded examiner scored scanning electron micrographs of the samples. Statistical analyses were performed using one-way ANOVA and Tukey's test. RESULTS: Application of TTC before EDTA presented the best results with the highest number of cells adhered to the root surface (p=0.046). Use of EDTA alone and EDTA before TTC disturbed clot stabilization when compared to control group (p<0.01). CONCLUSIONS: The use of TTC before EDTA seems to be able to keep blood cells viable to establish an organized clot and could be used by clinicians together with the conventional mechanical root scaling and planing...

Replication priority of hepatitis C virus genotype 2a in a Chinese cohort

HCV genotypes have been documented in clinical practice. The aim of this study was to determine the replication priority of different HCV genotypes in a Chinese HCV positive cohort. Serum samples from 491 apparently healthy Chinese blood donors testing positive for HCV antibodies and naive to antiviral drug therapy were tested. Genotyping analysis showed that genotypes 1b and 2a were predominant and accounted for 77.6% of the HCV infections. Among the genotype groups, individuals infected with genotype 2a had an HCV RNA viral load (10(8) copies/mL) about 200-fold (lg, 2.3) greater than those infected with other genotypes (10(4)-10(5) copies/mL) indicating a replication priority of genotype 2a. However, there was no correlation between HCV genotype and antibody response suggesting that the amplification advantage of genotype 2a results from a favorable interaction with the host cellular environment. In conclusion, HCV genotypes 1b and 2a are the predominant genotypes in China and genotype 2a possesses a significant replication priority compared with the other genotypes. This suggests the existence of host cellular factors that may act as drug-targets for entirely clearing HCV infection in the future.

A comparative evaluation of smear layer removal using two rotary instrument systems with ethylenediaminetetraacetic acid in different states: A SEM study.

Aim: The aim of the study was to evaluate the ability of 17% ethylenediaminetetraacetic acid (EDTA) solution and 19% EDTA gel to remove debris, and smear layer produced during root canal preparation with two NiTi files systems, Mtwo and Protaper. Materials and Methods: Twenty freshly extracted human anterior teeth with single root canal were collected. The crowns were sectioned at the cemento-enamel junction, and working length was measured. These samples were randomly divided into four groups of five samples each. In each group, 2ml of 3 % sodium hypochlorite solution was used with first instrument. The groupings were as follows. Group 1: 2 ml of 17% EDTA solution and 2 ml of 3% NaOCl were used alternatively each time a new file was employed. This group was prepared with Mtwo rotary files. Group 2: The samples in this group was prepared with Mtwo rotary files. EDTA gel (19%) was used and the samples were irrigated with 2 ml of 3% NaOCl. NaOCl and EDTA gel were used alternatively. Group 3: Five samples were prepared with Protaper file. Irrigation regime was the same as in Group 1. Group 4: Five samples were prepared with Protaper files and irrigation regime was the same as in Group 2. SEM study was done and the collected data were submitted for statistical analysis. Results: There was no statistically significant difference with the varied instruments used (Mtwo and Protaper files), and 17% EDTA solution and 19% EDTA gel. Conclusion: Both the NITI instruments produced a similar dentin surface on root canal wall when used with EDTA gel and EDTA solution.

A Comparative Study on the Enhancement Efficacy of Specific and Non-specific Iron Chelators for Protoporphyrin IX Production and Photosensitization in HaCat Cells / 华中科技大学学报（医学）（英德文版）

The iron chelators can be utilized in target cells to improve 5-aminolaevulinic acid (ALA)-based photodynamic therapy (PDT). The purpose of this study is to compare the effect of two kinds of iron chelators,desferrioxamine (DFO) and ethylenediaminetetraacetic acid (EDTA) on the enhancement of ALA-PDT. HaCat cells were cultured in medium containing 2.0 mmol/L of ALA and 0.5 mmol/L of DFO or EDTA. After 3-h incubation in the dark,the concentration of cellular protoporphyrin IX (PpIX) was detected by high performance liquid chromatography (HPLC),and the fluorescence of PpIX was observed at 630 nm emission under confocal laser scanning microscope.For PDT,HaCat cells were irradiated using 632.8 nm laser,and the fractions of apoptotic and necrotic cells were flow cytometricaUy assayed. Related differences in morphology and ultrastructure of HaCat cells were observed using optical microscope or transmission electron microscope. Compared to incubation with ALA alone,the addition of DFO or EDTA increased the concentration of cellular PpIX and the fluorescent density of PpIX,and also increased cell death ratio after PDT. PDT using ALA plus DFO produced the highest cellular PpIX level,greatest cell death ratio and most severe structural damage to the cells. It was concluded that both DFO and EDTA could enhance ALA-based PpIX production and PDT. Compared to the non-specific iron chelator of EDTA,the specific chelator,DFO,showed more potential for the enhancement.

Response of the periapical tissue of dogs' teeth to the action of citric acid and EDTA

The purpose of this study was to analyze the inflammatory response of dog's periapical tissues to 17 percent trisodium EDTA salt (pH 8.0) and 1 percent citric acid (pH 2.0). Saline was used as a control. Six adult dogs were used as the biological model of the study. The experimental units comprised 56 roots of mandibular molars (first and second) and premolars (first, second and third). After coronal opening, pulpectomy and root canal instrumentation were performed using the above-mentioned irrigating solutions. After 24 and 48 hours, the animals were euthanized and the teeth and their supporting tissues were removed and histologically processed. The sections were stained with hematoxylin and eosin and analyzed histopathologically with a light microscope at x100 magnification. The histological analysis focused on the occurrence of acute inflammatory response. The presence of swelling, vasodilatation and inflammatory cells were evaluated and the degree of inflammation was determined for each case. Data were analyzed by Fisher's exact test using the SPSS software with a confidence interval of 95 percent (p<0.05). 17 percent EDTA and 1 percent citric acid caused inflammatory responses in dog's periapical tissues with no significant differences to each other or to saline (control) at either the 24-hour (p=0.482) or 48-hour (p=0.377) periods. It may be concluded that the inflammatory response was of mild intensity for the tested substances.