Efecto citotóxico de los compuestos de inclusión de paladio (II) en la beta-ciclodextrina / Cytotoxic effect of palladium (II) inclusion compounds in beta-cyclodextrin

Resumen Introducción. Las tiosemicarbazonas y sus complejos de paladio (II) poseen actividad antineoplásica con pocos efectos secundarios, por lo cual se las considera como una nueva alternativa terapéutica. Sin embargo, existen diferencias en los rangos de la concentración inhibitoria media (CI50) asociada a la divergencia estructural y la solubilidad de los complejos, así como a la sensibilidad de los blancos celulares. La inclusión de fármacos en la beta-ciclodextrina con fines terapéuticos ha mejorado su solubilidad y estabilidad, pero los efectos de su combinación con los complejos de paladio (II) y las tiosemicarbazonas no se han comprobado aún. Objetivo. Estudiar el efecto citotóxico de los complejos de paladio en la beta-ciclodextrina. Materiales y métodos. La actividad citotóxica de los complejos de paladio en la beta-ciclodextrina se evaluó en la línea celular de cáncer de mama (MCF-7), empleando el método de la sulforodamina B. Resultados. Los ligandos MePhPzTSC y Ph2PzTSC, sus complejos de paladio (II) libres e incluidos en la beta-ciclodextrina y el cisplatino mostraron actividad citotóxica en la línea celular MCF-7; sin embargo, la citotoxicidad fue mayor con la inclusión en la beta-ciclodextrina ([Pd(MePhPzTSC)2]•ß-CD y [Pd(Ph2PzTSC)2]•ß-CD). La concentración inhibitoria media (CI50) para estos complejos se obtuvo en concentraciones de 0,14 y 0,49 μM, y con dosis hasta cinco veces inferiores comparadas con las concentraciones de los ligandos libres (1,4 y 2,9 μM), de los complejos de paladio (II) libres (0,57 y 1,24 μM) y del cisplatino (6,87 μM). Conclusiones. El uso de la beta-ciclodextrina mejoró significativamente la actividad citotóxica de las tiosemicarbazonas y sus complejos de paladio (II), lo cual probablemente está asociado al incremento de la solubilidad y biodisponibilidad del compuesto, estrategia que se puede sugerir para el diseño de futuros fármacos antineoplásicos.

Abstract Introduction: Thiosemicarbazones and palladium (II) complexes have antineoplastic activities with mild side effects, for which they are considered new alternative antineoplastic drugs. However, the IC50 ranges of these complexes vary due to differences in their structure and solubility and their sensitivities for various cellular targets. Beta-cyclodextrin is an additive used to improve the solubility and stability of various drugs for therapeutic use, but the combination of beta-cyclodextrin with palladium (II) complexes and thiosemicarbazones has not been tested yet. Objective: To study the cytotoxic effect of palladium (II) inclusion complexes in beta-cyclodextrin. Materials and methods: We tested the cytotoxic activity of palladium complexes combined with betacyclodextrin in the breast cancer cell line MCF-7 using a sulforhodamine B assay. Results: We tested the antiproliferative activity of palladium (II) complexes with and without the ligands MePhPzTSC and Ph2PzTSC and with and without beta-cyclodextrin in MCF-7 cells and compared them to that of cisplatin. All combinations showed antiproliferative activity; however, the activity was greater for the combinations that included beta-cyclodextrin: ([Pd (MePhPzTSC) 2] • ß-CD and [Pd (Ph2PzTSC) 2] • ß-CD), at concentrations of 0.14 and 0.49 μM, respectively. The IC50 for this complex was 5-fold lower than that of the ligand-free combinations (1.4 and 2.9 μM, respectively). The IC50 for free palladium (II) complex was 0.571.24 μM and that for cisplatin was 6.87 μM. Conclusions: Beta-cyclodextrin significantly enhanced the cytotoxic activities of palladium (II) complexes and thiosemicarbazones probably by improving their solubility and bioavailability. The addition of betacyclodextrin is a possible strategy for designing new anticancer drugs.

Effect of cantilever length and alloy framework on the stress distribution in peri-implant area of cantilevered implant-supported fixed partial dentures

ABSTRACT Because many mechanical variables are present in the oral cavity, the proper load transfer between the prosthesis and the bone is important for treatment planning and for the longevity of the implant-supported fixed partial denture. Objectives To verify the stress generated on the peri-implant area of cantilevered implant-supported fixed partial dentures and the potential effects of such variable. Material and Methods A U-shaped polyurethane model simulating the mandibular bone containing two implants (Ø 3.75 mm) was used. Six groups were formed according to the alloy’s framework (CoCr or PdAg) and the point of load application (5 mm, 10 mm and 15 mm of cantilever arm). A 300 N load was applied in pre-determined reference points. The tension generated on the mesial, lingual, distal and buccal sides of the peri-implant regions was assessed using strain gauges. Results Two-way ANOVA and Tukey statistical tests were applied showing significant differences (p<0.05) between the groups. Pearson correlation test (p<0.05) was applied showing positive correlations between the increase of the cantilever arm and the deformation of the peri-implant area. Conclusions This report demonstrated the CoCr alloy shows larger compression values compared to the PdAg alloy for the same distances of cantilever. The point of load application influences the deformation on the peri-implant area, increasing in accordance with the increase of the lever arm.

Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework

Knowing how stresses are dissipated on the fixed implant-supported complex allows adequate treatment planning and better choice of the materials used for prosthesis fabrication. Objectives: The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods: Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results: The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion: The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant. .

Does the casting mode influence microstructure, fracture and properties of different metal ceramic alloys?

The aim of the present study was to evaluate the tensile strength, elongation, microhardness, microstructure and fracture pattern of various metal ceramic alloys cast under different casting conditions. Two Ni-Cr alloys, Co-Cr and Pd-Ag were used. The casting conditions were as follows: electromagnetic induction under argon atmosphere, vacuum, using blowtorch without atmosphere control. For each condition, 16 specimens, each measuring 25 mm long and 2.5 mm in diameter, were obtained. Ultimate tensile strength (UTS) and elongation (EL) tests were performed using a Kratos machine. Vickers Microhardness (VM), fracture mode and microstructure were analyzed by SEM. UTS, EL and VM data were statistically analyzed using ANOVA. For UTS, alloy composition had a direct influence on casting condition of alloys (Wiron 99 and Remanium CD), with higher values shown when cast with Flame/Air (p < 0.05). The factors 'alloy" and 'casting condition" influenced the EL and VM results, generally presenting opposite results, i.e., alloy with high elongation value had lower hardness (Wiron 99), and casting condition with the lowest EL values had the highest VM values (blowtorch). Both factors had significant influence on the properties evaluated, and prosthetic laboratories should select the appropriate casting method for each alloy composition to obtain the desired property.

In in-vitro evaluation of effect of different finish lines on marginal adaptation in metal-ceramic restorations under thermo-mechanical loading.

The aim of this study was to evaluate the marginal gap in terms of cement film thickness associated with shoulder, shoulder with 45° bevel, shoulder with 30° bevel and chamfer, under thermo-mechanical loading. Forty human mandibular molars were prepared and restored with ceramo-metal crowns. Teeth were thermo-mechanically loaded and vertically sectioned to evaluate the cement film thickness. Shoulder with 45° bevel provided the least marginal gap as compared with all the tested finish lines.

Development and Evaluation of the Quick Anaero-system-A New Disposable Anaerobic Culture System / 대한진단검사의학회지

BACKGROUND: We developed a new disposable anaerobic culture system, namely, the Quick anaero-system, for easy culturing of obligate anaerobes. METHODS: Our system consists of 3 components: 1) new disposable anaerobic gas pack, 2) disposable culture-envelope and sealer, and 3) reusable stainless plate rack with mesh containing 10 g of palladium catalyst pellets. To evaluate the efficiency of our system, we used 12 anaerobic bacteria. We prepared 2 sets of ten-fold serial dilutions of the 12 anaerobes, and inoculated these samples on Luria-Bertani (LB) broth and LB blood agar plate (LB-BAP) (BD Diagnostic Systems, USA). Each set was incubated in the Quick anaero-system (DAS Tech, Korea) and BBL GasPak jar with BD GasPak EZ Anaerobe Container System (BD Diagnostic Systems) at 35-37degrees C for 48 hr. The minimal inoculum size showing visible growth of 12 anaerobes when incubated in both the systems was compared. RESULTS: The minimal inoculum size showing visible growth for 2 out of the 12 anaerobes in the LB broth and 9 out of the 12 anaerobes on LB-BAP was lower for the Quick anaero-system than in the BD GasPak EZ Anaerobe Container System. The mean time (+/-SD) required to achieve absolute anaerobic conditions of the Quick anaero-system was 17 min and 56 sec (+/-3 min and 25 sec). CONCLUSIONS: The Quick anaero-system is a simple and effective method of culturing obligate anaerobes, and its performance is superior to that of the BD GasPak EZ Anaerobe Container System.

The electrochemical properties of four dental casting suprastructure alloys coupled with titanium implants

OBJECTIVES: As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions. MATERIAL AND METHODS: The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests. RESULTS: The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples. CONCLUSIONS: Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.

Evaluation of the adaptation interface of one-piece implant-supported superstructures obtained in Ni-Cr-Ti and Pd-Ag alloys

Várias formulações de ligas alternativas têm sido propostas para a substituição das ligas áureas na Odontologia. Recentemente foi lançada uma liga à base de Ni-Cr-Ti. O propósito deste trabalho foi verificar a adaptação marginal de supra-estruturas de próteses implanto-suportadas obtidas em liga de Ni-Cr-Ti, comparada às obtidas em liga seminobre de Pd-Ag. Foram confeccionadas 8 supra-estruturas de cada liga, sobre 4 implantes na região anterior da mandíbula. As supra-estruturas foram posicionadas e o parafuso de fixação do implante #1 foi apertado com carga de 20Ncm num torquímetro, ficando os demais desparafusados (teste de Sheffield). A desadaptação (em mm) foi medida num medidor óptico tridimensional, nas faces vestibular e lingual de cada implante. Os dados foram submetidos à análise estatística pela análise de variância e teste complementar de Tukey em nível de 5 por cento. Na análise dos dados foram encontradas diferenças significantes para os fatores material, em nível de 5 por cento (p<0.05), com melhores resultados para estruturas em Ni-Cr-Ti, e implantes, em nível de 1 por cento (p<0.01). Não houve diferença significante para o fator posição e para as interações entre fatores (p>0.05). Com base na análise dos dados pode-se concluir que a liga de Ni-Cr-Ti possibilita a obtenção de supra-estruturas implanto-suportadas em monobloco com desadaptação menor se comparada à das obtidas em liga de Pd-Ag, tradicionalmente indicada para esta situação. Testes adicionais poderão atestas a superioridade da liga de Ni-Cr-Ti.

Spectrophotometric investigation of lincomycin and clindamycin-palladium [II] complexes and its application for their assay in capsules and ampoules

Palladium [II] chloride is proposed as a chromogenic reagent for the determination of lincomycin or clindamycin hydrochloride. The yellow complex is produced by the reaction of lincomycin or clindamycin HCl with Pd [II] in an aqueous solution of pH 4.7 or 5.5, respectively, and at ionic strength of 0.2 M KCl. The color has an absorption maximum at 380 nm with molar absorptivities of 1.86 x 103 and 1.68 x 103 1 mol-1 in concentration ranges of 10-140 and 20-170 mugml-1 for lincomycin and clindamycin, respectively. The precision, composition and conditional stability constant of the yellow complex have been established. The reagent has been successfully used for the spectrophotometric determination of these drugs alone and in pharmaceutical preparations

Microestructura y dureza de aleaciones odontológicas utilizadas en prótesis sobre implantes soldadas con láser / The microstructure and hardness of dental alloyds used in prosthetic applications welded by laser

Se evaluó la microestructura y la dureza de las aleaciones odontológicas utilizadas en prótesis sobre implanttes soldadas con laser. Los materiales utilizados fueron titanio comercialmente puro, una aleación de plata-paladio y una aleación de oro-paladio. Se verificó que en las soldaduras con laser la microestructura de las aleaciones presentaba tres regiones distintas: una hilera de soldadura, la zona afectada por el calor - (ZAC) y un metal base. El Ti (comercialmente puro) presentó una microestructura con una hilera de soldadura más refinada y de mayor dureza que un metal base y uno ZAC. Se observaron en las aleaciones AG-Pd y Au-Pd la aparición de una estructura dendrítica en la hilera de soldadura, siendo la dureza de éste menor que la del metal base y uno ZAC. Las microestructuras y la dureza fueron acordes con las altas velocidades de enfriamiento obtenidas durante la soldadura. En las tres aleaciones la ZAC fue pequeña comparado con otros procesos de soldadura, como uno convencional

Estudio in vitro de la adaptación marginal de dos aleaciones de plata-paladio / An in vitro study of the marginal accuracy of two silver-palladium alloys

En este estudio descriptivo comparativo se analizó la adaptación marginal de dos diferentes aleaciones de plata-paladio (J-7 y Jorcast), colocadas en 28 segundos premolares superiores. Se utilizaron restauraciones de coronas completas e incrustaciones inlay MOD, teniendo en cuenta si había alguna variación en los resultados, antes y después del pulido y manejando como grupo control oro tipo II (casting gold). Las muestras fueron cementadas en los dientes y acriladas para ser observadas al microscopio electrónico de barrido (SEM). Los resultados indican que las aleaciones de plata-paladio, antes y después del pulido, tanto en restauraciones de coronas completas como en incrustaciones MOD, presentan una adaptación marginal muy similar a las aleaciones de oro tipo III, convirtiéndose así en una alternativa confiable para su utilización en la práctica odontológica

Metodología aplicada al desarrollo de aleaciones dentales / Methodology applied to the development of dental alloys

Se presenta una metodología de desarrollo de aleaciones dentales y se aplica en plata-paladio con bajo contenido en metales nobles. El trabajo contempla obtención de aleaciones y evaluación de propiedades metalúrgicas y clínicas. Los resultados obtenidos con el grupo de aleaciones Ag-Pd muestran que el comportamiento "in vitro" permite predecir, con suficiente certeza, un comportamiento aceptable en boca. Esta predicción adquiere mayor validez al incorporar a la evaluación clínica aleaciones desarrolladas en trabajos anteriores, instaladas hace 4 o más años. Para una muestra global de 53 restauraciones, un 96 por ciento entrega resultados satisfactorios y sólo un 4 por ciento aparece como no aceptable. Se concluye que el trabajo desarrollado ofrece una aceptable metodología de prueba de toda nueva aleación propuesta como material dental restaurador

Comportamiento "in vitro" de aleaciones plata-paladio / In vitro behavior of silver-palladium alloys

En la búsqueda de aleaciones dentales económicamente alternativas están siempre presentes las aleaciones base plata-paladio, por sus características y versatilidad de uso. En este trabajo se estudia el comportamiento "in vitro" de siete aleaciones Ag-Pd, representantes de la gran familia Ag-Pd-Au-Cu-otros, se obtienen subgrupos eliminando el oro o el cobre de la composición general. Se usa como referencia un producto Ag-Pd comercial, siendo el costo de las aleaciones un factor determinante para definir su composición. Las muestras se obtienen mediante técnicas tradicionales de fusión, simulando la obtención de colados dentales. Se determinan propiedades mecánicas y químicas de las aleaciones investigadas. Se concluye que la composición no tiene una influencia tan importante en la dureza de las aleaciones experimentales ya que, en general, tienden a clasificar alrededor del tipo III de la ADA. Por otro lado, su aptitud al tratamiento térmico permitiría cubrir los rangos de menor y mayor dureza. Sin embargo, elevados contenidos de plata hacen que predominen las propiedades de este elemento, obteniéndose aleaciones más blandas. La composición tiene una influencia más importante sobre las propiedades químicas; la plata, como elemento base de la aleación, es determinante sobre estas propiedades, principalmente, cuando está presente en cantidades de 80 por ciento o más. Los peores comportamientos, frente a la corrosión y pigmentación, los exhibieron las aleaciones con mayores contenidos de plata. Las aleaciones con un contenido más elevado de metales nobles, mostraron las mejores propiedades químicas. Sin embargo, aleaciones de composición y costos intermedios mostraron comportamientos aceptables, respondiendo así a los objetivos de la investigación

Extraction-spectrophotometric determination of prazosin hydrochloride with palladium [II]

The described spectrophotometric determination of prazosin hydrochloride [PZH] involves the extraction of the PZH-Pb [II] complex from an acetate buffer solution pH 6.0 into a chloroform layer. The absorbance of the extracted solution is measured at 420 nm. The molar absorptivity of the complex is 2.1 x 103 l mol-1 cm-1 at 420 nm. The effects of pH [4-10], Pb [II] chloride concentration and shaking time were studied. The ratio of prazosin molecules to palladium ions in the colored complex was found to be 1: 1. Finally, a procedure for the determination of PZH in pure form or in pharmaceutical preparations is recommended. The method is selective, sensitive and accurate

Thermal and spectroscopic characterization of Pd [II] and Pt [IV] thiobarbiturate complexes

Pd [II] and Pt [IV] thiobarbiturate complexes [Ligaud: 2-thiobarbituric acid; Abbreviation, HTBA] were synthesized as solid phases. Chemical and thermogravimetric analyses, together with IR and electronic absorption spectra of the ligand and the two complexes were carried out. IR vibrational bands support M-S and M-N bondings in the Pd [II] and Pt [IV] ions are tetra-and hexa-coordinated, as deduced from their electronic absorption bands characteristic of square planar and octahedral configurations, respectively. Results of thermogravimetric analysis were in agreement with the general molecular formulae: Pd [TBA]2 and Pt [TBA]4 [HTBA]2 proposed by chemical analysis. The TG and DTG curves of both the Pd [II] complex and the Pt [IV] complex showed three thermal dissociation steps ending with a final step at>790 and >772 omicron, respectively. The thermal stability of the studied compounds was found to have the order: Pt [TBA]4 [HTBA]2> HTBA>pd [TBA]2