Rate Of Matrix Formation Research Articles

PLGA and PDMS-based in situ forming implants loaded with rosuvastatin and copper-selenium nanoparticles: a promising dual-effect formulation with augmented antimicrobial and cytotoxic activity in breast cancer cells.

Breast cancer is among the most prevalent tumors worldwide. In this study, in-situ forming implants (ISFIs) containing rosuvastatin calcium were prepared using three types of poly (D, L-lactic-co-glycolic acid) (PLGA), namely, PLGA 50/50 with ester terminal and PLGA 75/25 with ester or acid terminal. Additionally, polydimethylsiloxane (PDMS) was added in concentrations of 0, 10, 20, and 30% w/v to accelerate matrix formation. The prepared ISFIs were characterized for their rheological behaviors, rate of matrix formation, and in-vitro drug release. All the prepared formulations revealed a Newtonian flow with a matrix formation rate between 0.017 and 0.059mm/min. Generally, increasing the concentration of PDMS increased the matrix formation rate. The prepared implants' release efficiency values ranged between 46.39 and 89.75%. The ISFI containing PLGA 50/50 with 30% PDMS was selected for further testing, as it has the highest matrix formation rate and a promising release efficiency value. Copper-selenium nanoparticles were prepared with two different particle sizes (560 and 383nm for CS1 and CS2, respectively) and loaded into the selected formulation to enhance its anticancer activity. The unloaded and loaded implants with rosuvastatin and copper-selenium nanoparticles were evaluated for their antibacterial activity, against Gram-positive and negative microorganisms, and anticancer efficacy, against MCF-7 and MDA-MB-231 cell lines. The results confirmed the potency of rosuvastatin calcium against cancer cells and the synergistic effect when loaded with smaller particle sizes of copper-selenium nanoparticles. This formulation holds a considerable potential for efficient breast cancer therapy.

Phase Inversion-Induced Rosin <i>In Situ</i> Forming Matrix Using Various Organic Biocompatible Solvents for Periodontitis Treatment

In situ forming matrix (ISM) is an injectable drug delivery system containing a drug-loaded polymeric solution. It was applied for local drug administration such as into a periodontal pocket for periodontitis treatment with an antimicrobial agent. ISM can transform with phase inversion into the solid-like matrix after contact an aqueous environment by solvent exchange mechanism. This study aims to develop ISM which various concentrations of rosin (R) as matrix former dissolved in organic biocompatible and biodegradable solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide and 2-pyrrolidone. Physicochemical characterization and matrix formation behavior owing to phase inversion of R ISM were evaluated including pH, density, viscosity, contact angles, surface tension, expelling force through a syringe, matrix formation behavior and morphological change. The density of all R ISM exhibited in the range of 1.03-1.11 g/cm3 and contact angles (9.04-44.13°) indicated a good wetting property. Higher R concentration decreased pH of ISM owing to increased amount of abietic and pimaric acid from R while the viscosity, contact angles and force for expelling a syringe were increased. The viscosity of R ISM in dimethyl sulfoxide was less than that in 2-pyrrolidone; thus, ISM using dimethyl sulfoxide as a solvent exhibited good injectability. ISM comprising R concentration > 30%w/w promoted a faster matrix growth in which the amount of occurred R matrix was enhanced with time and the rate of matrix formation was lower with time. Doxycycline Hyclate (Dx)-loaded 40%w/w ISM in dimethyl sulfoxide (Dx-DR) had pH of 3.70, density of 1.1084 ± 0.0005 g/ml, viscosity of 35.72 ± 0.00 cPs, contact angles of 26.87 ± 2.40°, surface tension of 37.11 ± 0.11 mN/m and expelling force of 23.98 ± 0.18 N. It showed the sustainable Dx release in simulated crevicular fluid and the efficient antimicrobial activity against Staphylococcus aureus and Porphyromonas gingivalis. Thus, this phase inversion induced R ISM using dimethyl sulfoxide as a solvent showed potential as an antimicrobial agent-loaded drug delivery system for periodontitis treatment.

Matrix Forming Behavior of Doxycycline Hyclate-Loaded Beta-Cyclodextrin <i>In Situ</i> Forming Matrix and Microparticle

In situ forming microparticle (ISM) is an injectable emulsion drug delivery system comprising drug loaded in polymeric solution as internal phase and oil combined with emulsifier as external phase. This emulsion transforms into microparticle after contact an aqueous environment by solvent exchange mechanism. This study developed ISM using internal phase comprising 5% w/w doxycycline hyclate (DH) loaded with various concentrations of beta-cyclodextrin (β-CD) using N-methyl-2-pyrrolidone (NMP) as a solvent and external phase containing olive oil combined with glyceryl monostearate (GMS). High concentrated β-CD solutions in NMP are used as the internal phase of ISM. Matrix forming behavior is evaluated for their particle size, transformation to microparticle, pH, rate of matrix formation, contact angle and surface tension. Each emulsion had similar pH values about 3.5-4.1 and transformed into microparticles (particle size about 60 μm) after contact with phosphate buffer pH 6.8. The particle sizes of each preparation decreased significantly after transformed into microparticles and the more microparticles were evident with time. The rate of matrix formation of ISM was apparent slower than its internal phase and was slower with time. Contact angle of ISM and its internal phase showed good wetting which the surface tension of 35% w/w β-CD ISM was 44.19 mN/m. The β-CD ISM exhibited as the potential delivery system for incorporation of active compounds.

Physicochemical properties of β-cyclodextrin solutions and precipitates prepared from injectable vehicles

β-Cyclodextrin (β-CyD) is cyclic oligosaccharide of a glucopyranose, containing a relatively hydrophobic central cavity and hydrophilic outer surface. However, the usefulness of β-CyD is limited owing to its low aqueous solubility whereas we found that its apparent high solubility was evident in some injectable solvents including 2-pyrrolidone (PYR), N-methyl pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). Therefore, in the present study, the physicochemical properties of the 30–60% w/w β-CyD in PYR, NMP and DMSO were investigated such as viscosity, water resistant, matrix formation rate and syringeability. The higher the concentration of β-CyD resulted in the increased viscosity and the higher force and energy of syringeability. β-CyD in PYR gave the highest viscosity which contributed to the lowest syringeability while β-CyD in DMSO exhibited the highest syringeability. The β-CyD in DMSO and NMP exhibited the higher rate of matrix formation. β-CyD in PYR showed the highest water resistant for phase separation while β-CyD in NMP gave the faster de-mixing rate compared to that from PYR. The difference in physicochemical properties of β-CyD dried ppts studied by scanning electron microscope (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) revealed that there was partial complexation of β-CyD with respective solvents. Both solution and precipitate characteristic properties will be useful for using β-CyD in further investigation as matrix material dissolved in the injectable vehicles as the in situ forming gel for periodontitis treatment.

Regeneration of dental pulp following pulpectomy by fractionated stem/progenitor cells from bone marrow and adipose tissue

Pulp stem/progenitor cells can induce complete pulp regeneration. However, due to the limited availability of pulp tissue with age, there is a need to examine other sources for fractions of side population (SP) cells. In the present investigation bone marrow and adipose tissues of the same individual were evaluated as alternate sources. Pulp CD31 − SP cells have higher migration activity and higher expression of angiogenic/neurotrophic factors than bone marrow and adipose CD31 − SP cells. Adipose tissue CD31 − SP cell transplantation yielded the same amount of regenerated tissue as pulp derived cells. However, bone marrow CD31 − SP cell transplantation yielded significantly less regenerated tissue in pulpectomized root canals in dogs. The rate of matrix formation was much higher in adipose CD31 − SP cell transplantation compared to pulp CD31 − SP cell transplantation on day 28. Microarray analysis demonstrated similar qualitative and quantitative patterns of mRNA expression characteristic of pulp in the regenerated tissues from all three cell sources. Expression of many angiogenic/neurotrophic factors in the transplanted cells demonstrated trophic effects. Our results demonstrate that bone marrow and adipose CD31 − SP cells might be suitable alternative cell sources for pulp regeneration.

Characterization of Dentin Formed in Transplanted Rat Molars by Electron Probe Microanalysis

The present study was designed to characterize dentin formed in transplanted rat molars by investigating calcium (Ca), phosphorus (P), and magnesium (Mg) concentrations using electron probe microanalysis (EPMA) as well as examining the rate of dentin matrix formation by vital staining. The unerupted immature lower right second molar in 2-week-old rats was transplanted into the upper right first molar socket. Rats were injected with oxytetracycline, calcein, and alizarin intraperitoneally at 1 day before and 1 and 2 weeks after transplantation, respectively, for vital staining. The maxillae and mandibles were fixed 3 weeks after transplantation, resected, and embedded in resin. Undemineralized sections were cut and examined by fluorescent microscopy and EPMA. The thickness of dentin formed in the first week after transplantation was significantly less than that of dentin formed in any other 1-week period in the transplanted tooth and was about one-fifth the thickness of dentin formed in control teeth. Formation of dentin recovered in the third week after transplantation. In the first week after transplantation, EPMA demonstrated a sharp increase in Mg concentration with a slight decrease in Ca concentration. Thereafter, no significant difference was identified among Ca, P, or Mg concentrations or the Ca/P ratio between transplanted and control teeth. These results suggest that disruption of the circulation and innervation by transplantation cause a temporary change in the matrix formation rate and elemental distribution of dentin, which is subsequently restored within 2 weeks after transplantation.

The Effect of Processing Parameters on the Growth Rate and Microstructure of Al2O3/Metal Matrix Composites

ABSTRACTCeramic matrix composites can be formed by the directed oxidation of a doped molten aluminum alloy into an inert reinforcement or filler. The resultant ceramic matrix consists of interconnected Al2O3 and partially interconnected metal. The growth kinetics of this Al2O3 /metal ceramic matrix can be altered by numerous parameters. The effect of the growth atmosphere composition and temperature on the composite growth rate is dependent on the alloy dopant utilized. The ceramic matrix formation rate is also dependent on the alloy composition. Likewise, alloy composition has a profound effect on the mechanical properties and microstructure of the composites produced.

Total and non-dialyzable urinary hydroxyproline in acromegalics and control subjects.

Abstract. The urinary excretion of total and non-dialyzable hydroxyproline (HYP) containing peptides has been studied in 25 patients with active acromegaly and 44 control subjects — all kept on a collagen free diet. Acromegalics had a greater excretion of both total and non-dialyzable HYP than controls, indicating an increased turn-over of collagen/bone matrix. The amounts of total and non-dialyzable HYP excreted in acromegalics were significantly correlated to mean fasting growth hormone levels. Both acromegalics and controls exhibited a significant coupling between the excretion of total and non-dialyzable HYP. Female control subjects demonstrated an age-dependent decrease in the excretion of both total and non-dialyzable HYP, whereas no such age-dependence could be observed in males. Age seemed to have a greater effect on the non-dialyzable fraction than on the total HYP excretion. These results may imply that collagen/bone matrix turn-over declines with age and that bone formation declines at a more rapid rate than resorption. In acromegalics the ratio of non-dialyzable to dialyzable HYP was not significantly different from control values, indicating that although turn-over is increased the actual matrix formation rate is normal in acromegaly. No correlation was found between serum or urinary parameters of calcium/phosphate metabolism or the urinary excretion of 3',5'-cyclic adenosine monophosphate and total or non-dialyzable HYP in acromegalics or controls.

Formation, mineralization, and resorption of bone in hypophosphatemic rats.

Quantitative morphologic methods were used to measure the effects of feeding a low phosphorus diet to intact and thyroparathyroidectomized rats on several processes of bone mineralization and turnover. In severely hypophosphatemic animals, the matrix formation rate was decreased, the osteoid maturation rate was decreased, which indicated a delay in the onset of mineralization, the initial rate of mineralization was decreased, and the endosteal osteoclastic bone resorption rate was increased. In moderately hypophosphatemic animals, there was a substantial increase in bone resorption but no change in formation or in mineralization. The increase in endosteal bone resorption was due to an increase in the linear rate of bone resorption and particularly to an increase in the length of the endosteal resorbing surface. The magnitude of the increase in bone resorption was similar in thyroparathyroidectomized and intact rats indicating that neither parathyroid hormone nor calcitonin is involved in this change. This, together with the finding that there was a strong negative correlation (r = -0.99) between the per cent endosteal resorbing surface and the serum phosphorus, supports the view that the increased resorption was due to hypophosphatemia. This inverse relationship between endosteal resorbing surface and serum phosphorus appeared to hold for values of serum phosphorus above normal. The resorptive response to hypophosphatemia, as previously shown for the resorptive response to excess endogenous parathyroid hormone, was partially inhibited by vitamin D deficiency. Increased resorption occurred at levels of serum phosphorus where no changes were observed in bone formation, mineralization, or growth, suggesting that this resorptive response functions as a homeostatic mechanism to maintain serum and intracellular phosphorus concentrations.

Formation, mineralization, and resorption of bone in vitamin D-deficient rats.

Quantitative histologic methods have been devised to measure several processes dealing with formation and mineralization of matrix and bone resorption. In vitamin D-deficient rats, the total osteoblastic matrix formation rate was 20% less and the total osteoclastic bone resorption rate was 80% more than in pair-fed control rats. These changes were found to be primarily because of changes in the rates of matrix formation and of bone resorption per unit area of forming or resorbing surfaces rather than to changes in the areas of these surfaces. The rate of maturation of osteoid and the rate of initial mineralization both were reduced to half of normal in the vitamin D-deficient rats. These variables related to matrix formation and mineralization were significantly correlated with the concentration of calcium but not with the concentration of phosphate in serum. The occurrence of hypocalcemia is interpreted as the consequence, both of reduced calcium absorption and of inadequate resorptive response of bone cells to homeostatic stimuli, such that, although bone resorption was greater than normal, it did not adequately compensate for the reduced intestinal absorption.