Effects of Plasma Treatment on the Bioactivity of Alkali-Treated Ceria-Stabilised Zirconia/Alumina Nanocomposite (NANOZR).

Zirconia ceramics such as ceria-stabilized zirconia/alumina nanocomposites (nano-ZR) are applied as implant materials due to their excellent mechanical properties. However, surface treatment is required to obtain sufficient biocompatibility. In the present study, we explored the material surface functionalization and assessed the initial adhesion of rat bone marrow mesenchymal stem cells, their osteogenic differentiation, and production of hard tissue, on plasma-treated alkali-modified nano-ZR. Superhydrophilicity was observed on the plasma-treated surface of alkali-treated nano-ZR along with hydroxide formation and reduced surface carbon. A decreased contact angle was also observed as nano-ZR attained an appropriate wettability index. Treated samples showed higher in vitro bovine serum albumin (BSA) adsorption, initial adhesion of bone marrow and endothelial vascular cells, high alkaline phosphatase activity, and increased expression of bone differentiation-related factors. Furthermore, the in vivo performance of treated nano-ZR was evaluated by implantation in the femur of male Sprague-Dawley rats. The results showed that the amount of bone formed after the plasma treatment of alkali-modified nano-ZR was higher than that of untreated nano-ZR. Thus, induction of superhydrophilicity in nano-ZR via atmospheric pressure plasma treatment affects bone marrow and vascular cell adhesion and promotes bone formation without altering other surface properties.

Comparación in vitro de la difusión iónica de pastas de hidróxido de calcio usadas como medicación intraconducto con diferentes vehículos / In vitro comparison of ionic diffusion of calcium hidroxide pastes used as intracanal medication with different vehicles

La medicación intraconducto consiste en la colocación de un medicamento en el interior del conducto radicular. En la actualidad, la pasta de hidróxido de calcio es la más utilizada. Su mecanismo de acción se basa en la disociación de iones oxhidrilos y calcio, responsables de efectos antibacterianos y de reparación tisular. El objetivo de este trabajo fue comparar la difusión de iones calcio y oxhidrilos de la pasta de hidróxido de calcio en el tiempo, utilizando como vehículo agua tridestilada, polietilenglicol y gel de aloe vera. Se utilizaron 45 caninos, se realizó radiografías preoperatorias, aperturas, determinación de la longitud de trabajo para la preparación biomecánica de los conductos. Se rellenaron los especímenes con cada una de las pastas tomando radiografías postoperatorias. Se colocaron las muestras en un medio de análisis almacenándolas en estufa a 37ºC durante 3, 24, 72,168 y 336 horas. Se realizó por triplicado la determinación del pH con pH-metro Metrohm 692 y de la concentración de calcio total utilizando el método espectrofotométrico (reacción del calcio con cresolftaleína complexona a pH 11). Los datos se analizaron estadísticamente por medio de ANOVA aplicando el test de LSD (alfa= 0,05). El comportamiento difusional de las pastas alcalinas con vehículo agua tridestilada y polietilenglicol fue similar en las primeras etapas de experimentación y difirió en las etapas finales. La pasta alcalina con gel de aloe vera mostró un comportamiento de iones oxhidrilos diferente en las primeras etapas de experimentación, el comportamiento de iones calcio fue similar hasta las 168 horas

The intracanal medication consists in placing a medication inside the root canal. At present, the calcium hydroxide paste is most often used. Its mechanism of action is based on the dissociation of calcium ions and hydroxyls responsible for antibacterial effects and tissue repair. The aim of this study was to compare the diffusion of calcium ions and hydroxyls of calcium hydroxide paste in time, using triple distilled water as a vehicle, polietilienglicol and aloe vera gel. 45 canine teeth were used, was performed preoperative radiographs, openings, determining the working length to the biomechanical canal preparation. Specimens with each of the pastes were filled and postoperative radiographs were taken. The samples were placed in a medium of analysis were stored in an oven at 37 ° C for 3, 24, 72,168 and 336 hours. Was performed triplicate pH determination with Metrohm 692 pH meter and the total calcium concentration using the spectrophotometric method (reaction of calcium with cresolphthalein complexone to pH 11). The data were statistically analyzed by ANOVA using the LSD test ( = 0.05). The diffusional behavior of alkaline pasta with water tridistilled -polyethylene vehicle was similar in the initial stages of experiment and in the final stages different. The alkaline paste with aloe vera gel showed a different behavior of hydroxyls ions in the early stages of testing, the behavior of calcium ions was similar up the 168 h

Alkaline post-treatment of Cd(II)-glutathione coordination polymers: toward green synthesis of water-soluble and cytocompatible CdS quantum dots with tunable optical properties.

In this study, we demonstrate a facile and environmentally friendly method for the synthesis of glutathione (GSH)-capped water-soluble CdS quantum dots (QDs) with a high cytocompatibility and a tunable optical property based on alkaline post-treatment of Cd-GSH coordination polymers (CPs). Cd-GSH CPs are synthesized with the coordination reaction of Cd(2+) with GSH at different pH values, and the CdS QDs are then formed by adding NaOH to the aqueous dispersion of the Cd-GSH CPs to break the coordination interaction between Cd(2+) and GSH with the release of sulfur. The particle size and optical property of the as-formed CdS QDs are found to be easily tailored by simply adjusting the starting pH values of GSH solutions used for the formation of Cd-GSH CPs, in which the wavelengths of trap-state emission of the QDs red-shift with an increase in the sizes of the QDs that is caused by an increase in the starting pH values of GSH solutions. In addition, the use of GSH as the capping reagent eventually endows the as-formed CdS QDs with enhanced water solubility and good cytocompatibility, as demonstrated with HeLa cells. The method demonstrated here is advantageous in that the cadmium precursor and the sulfur source are nontoxic and easily available, and the size, optical properties, water solubility, and cytocompatibilty of the as-formed CdS QDs are simply achieved and experimentally regulated. This study offers a new and green synthetic route to water-soluble and cytocompatible CdS QDs with tunable optical properties.

Optimal choice of pH for toxicity and bioaccumulation studies of ionizing organic chemicals.

It is recognized that the pH of exposure solutions can influence the toxicity and bioaccumulation of ionizing compounds. The present study investigates whether it can be considered a general rule that an ionizable compound is more toxic and more bioaccumulative when in the neutral state. Three processes were identified to explain the behavior of ionizing compounds with changing pH: the change in lipophilicity when a neutral compound becomes ionized, electrical attraction, and the ion trap. The literature was screened for bioaccumulation and toxicity tests of ionizing organic compounds performed at multiple pH levels. Toxicity and bioconcentration factors (BCFs) were higher for acids at lower pH values, whereas the opposite was true for bases. The effect of pH was most pronounced when pH - pK(a) was in the range of -1 to 3 for acids, and -3 to 1 for bases. The factor by which toxicity and BCF changed with pH was correlated with the lipophilicity of the compound (log K(OW) of the neutral compound). For both acids and bases, the correlation was positive, but it was significant only for acids. Because experimental data in the literature were limited, results were supplemented with model simulations using a dynamic flux model based on the Fick-Nernst-Planck diffusion equation known as the cell model. The cell model predicts that bases with delocalized charges may in some cases show declining bioaccumulation with increasing pH. Little information is available for amphoteric and zwitterionic compounds; however, based on simulations with the cell model, it is expected that the highest toxicity and bioaccumulation of these compounds will be found where the compounds are most neutral, at the isoelectric point.

Mechanisms used to dispose of progressively increasing alkali load in rats.

Our objective was to describe the process of alkali disposal in rats. Balance studies were performed while incremental loads of alkali were given to rats fed a low-alkali diet or their usual alkaline ash diet. Control groups received equimolar NaCl or KCl. Virtually all of the alkali was eliminated within 24 h when the dose exceeded 750 micromol. The most sensitive response to alkali input was a decline in the excretion of NH(4)(+). The next level of response was to increase the excretion of unmeasured anions; this rise was quantitatively the most important process in eliminating alkali. The maximum excretion of citrate was approximately 70% of its filtered load. An even higher alkali load augmented the excretion of 2-oxoglutarate to >400% of its filtered load. Only with the largest alkali load did bicarbonaturia become quantitatively important. We conclude that renal mechanisms eliminate alkali while minimizing bicarbonaturia. This provides a way of limiting changes in urine pH without sacrificing acid-base balance, a process that might lessen the risk of kidney stone formation.

[Blood-eye barrier in the acute period of experimental severe alkaline burn of the eye by injection of deoxyglucose into the central vein]. / Gematooftal'micheskii bar'er v ostrom periode éksperimental'nogo tiazhelogo shchelochnogo ozhoga glaz pri vvedenii radioaktivnoi dezoksigliukozy v tsentral'nuiu venu.

The permeability of the blood-eye barrier for 14C-labeled deoxyglucose injected intravenously was studied on a model of severe experimental eye burn in 12 rabbits (24 eyes). The barrier permeability was evaluated by the content of radioactive material in the burnt eye humor in comparison with intact eye. Analysis of radiometric data showed a significant difference in the content of 14C in damaged and intact eyes. The permeability of the blood-eye barrier was increased in the damaged eye, this permeability depending on the concentration of the agent in the blood.

Evaluation of using dog as an animal model to study the fraction of oral dose absorbed of 43 drugs in humans.

PURPOSE: To conduct a retrospective evaluation of using dog as an animal model to study the fraction of oral dose absorbed (F) of 43 drugs in humans and to briefly discuss potential factors that might have contributed to the observed differences in absorption. METHODS: Mean human and dog absorption data obtained under fasted state of 43 drugs with markedly different physicochemical and pharmacological properties and with mean F values ranging from 0.015 to 1.0 were obtained from the literature. Correlation of F values between humans and dogs was studied. Based on the same references, additional F data for humans and rats were also obtained for 18 drugs. RESULTS: Among the 43 drugs studied, 22 drugs were virtually completely absorbed in both dogs and humans. However, the overall correlation was relatively poor (r2 = 0.5123) as compared to the earlier rat vs. human study on 64 drugs (r2 = 0.975). Several drugs showed much better absorption in dogs than in humans. Marked differences in the nonliner absorption profiles between the two species were found for some drugs. Also, some drugs had much longer Tmax values and prolonged absorption in humans than in dogs that might be theoretically predicted. Data on 18 drugs further support great similarity in F between humans and rats reported earlier from our laboratory. CONCLUSIONS: Although dog has been commonly employed as an animal model for studying oral absorption in drug discovery and development, the present study suggests that one may need to exercise caution in the interpretation of data obtained. Exact reasons for the observed interspecies differences in oral absorption remain to be explored.

Urinary citrate, bone resorption and intestinal alkali absorption in stone formers with fasting hypercalciuria.

Reduced citrate in urine and increased fasting excretion of calcium are abnormalities frequently reported in stone forming (SF) patients. Increased dietary acid (or reduced alkali) introduction or absorption may be a potential cause of both these pathological findings. To test this hypothesis, we studied 64 SF patients (32 with fasting hypercalciuria (FH) and 32 without FH (NFH)). After a basal evaluation for nephrolithiasis, while on a 500 mg calcium diet, they were evaluated for: (1) daily intestinal alkali absorption (IAA), by urinary electrolyte excretion; (2) basal concentrations of PTH, calcitonin (CT) and 1,25(OH)2-VitD; (3) oral calcium load for evaluation of changes in calcium and hydroxyproline urinary excretions; (4) intestinal calcium absorption (18 patients), with double curve analysis (stable Sr as tracer); and (5) changes in citrate excretion after an alkali load (50 mEq of a mixture of calcium gluconate, lactate and carbonate) in 10 patients. The results demonstrated: (1) FH stone formers had reduced citrate excretion and lower mean IAA levels than NFH stone formers; (2) FH stone formers also had higher bone resorption levels with lower PTH and higher CT levels; (3) IAA levels were related to both citrate excretion and bone turnover indices; and (4) the increases in citrate excretion after oral alkali load were strictly related to basal IAA values (index of alkali absorption and/or generation after oral load), demonstrating that a different absorptive capacity of alkali rather than a different dietary content may underlie these metabolic abnormalities.