Novel hydroxyapatite/chitosan bilayered scaffold for osteochondral tissue-engineering applications: Scaffold design and its performance when seeded with goat bone marrow stromal cells

Recent studies suggest that bone marrow stromal cells are a potential source of osteoblasts and chondrocytes and can be used to regenerate damaged tissues using a tissue-engineering (TE) approach. However, these strategies require the use of an appropriate scaffold architecture that can support the formation de novo of either bone and cartilage tissue, or both, as in the case of osteochondral defects. The later has been attracting a great deal of attention since it is considered a difficult goal to achieve. This work consisted on developing novel hydroxyapatite/chitosan (HA/CS) bilayered scaffold by combining a sintering and a freeze-drying technique, and aims to show the potential of such type of scaffolds for being used in TE of osteochondral defects. The developed HA/CS bilayered scaffolds were characterized by Fourier transform infra-red spectroscopy, X-ray diffraction analysis, micro-computed tomography, and scanning electron microscopy (SEM). Additionally, the mechanical properties of HA/CS bilayered scaffolds were assessed under compression. In vitro tests were also carried out, in order to study the water-uptake and weight loss profile of the HA/CS bilayered scaffolds. This was done by means of soaking the scaffolds into a phosphate buffered saline for 1 up to 30 days. The intrinsic cytotoxicity of the HA scaffolds and HA/CS bilayered scaffolds extract fluids was investigated by carrying out a cellular viability assay (MTS test) using Mouse fibroblastic-like cells. Results have shown that materials do not exert any cytotoxic effect. Complementarily, in vitro (phase I) cell culture studies were carried out to evaluate the capacity of HA and CS layers to separately, support the growth and differentiation of goat marrow stromal cells (GBMCs) into osteoblasts and chondrocytes, respectively. Cell adhesion and morphology were analysed by SEM while the cell viability and proliferation were assessed by MTS test and DNA quantification. The chondrogenic differentiation of GBMCs was evaluated measuring the glucosaminoglycans synthesis. Data showed that GBMCs were able to adhere, proliferate and osteogenic differentiation was evaluated by alkaline phosphatase activity and immunocytochemistry assays after 14 days in osteogenic medium and into chondrocytes after 21 days in culture with chondrogenic medium. The obtained results concerning the physicochemical and biological properties of the developed HA/CS bilayered scaffolds, show that these constructs exhibit great potential for their use in TE strategies leading to the formation of adequate tissue substitutes for the regeneration of osteochondral defects.     

Orchidectomy enhances the effects of phenylephrine in rat isolated portal vein

1. Orchidectomy results in long‐term testosterone deprivation similar to that observed in male clinical pathologies, such as hypogonadism and age‐related reductions in plasma testosterone concentrations. Although the vascular effects of these sorts of hormone deprivations are known in arteries, they have not been studied to the same extent in veins. 2. The aim of the present study was to determine the effect of orchidectomy, with or without subsequent testosterone replacement (started 23 days after orchidectomy; 10 mg/kg, i.m., testosterone propionate once every 5 days for 3 weeks), on responses of rat isolated portal veins and vena cavae to exogenous phenylephrine (PE). Isolated vessels were mounted in an organ bath and concentration–response curves constructed to PE (10^?10–10^?4 mol/L), endothelin (ET; 10^?10–10^?5 mol/L) and KCl (10^?2–1.2 × 10^?1 mol/L; as a control). 3. Orchidectomy had no effect on contractile responses of either the portal vein or vena cava to KCl. However, orchidectomy enhanced the maximum response (R_max) of the portal vein, but not the vena cava, to PE. Testosterone replacement had no effect on these responses. The effects of orchidectomy on the R_max to PE in portal veins were not altered by the nitric oxide synthase inhibitor N^G‐nitro‐l‐ arginine methyl ester (10^?4 mol/L) alone or combined with 10^?5 mol/L indomethacin (a non‐selective cyclo‐oxygenase inhibitor), but they were abolished following treatment of isolated vessels with the ET_A and ET_B receptor antagonists BQ‐123 and BQ‐788 (both at 10^?6 mol/L). Orchidectomy did not alter portal vein responses to the application of exogenous ET. 4. The results of the present study indicate that orchidectomy‐induced decreases in plasma testosterone can increase the venoconstrictor effects of PE on the portal vein and that this effect involves activation of both ET_A and ET_B receptors by locally produced ET.     

Dental caries status of Dai preschool children in Yunnan Province,China

Background

The Dai people, one of the ethnic minorities in China, have a population of 1,260,000. They have the same origin as one of the main ethnic groups of Laos and Thailand. Most of the Dai live in Yunnan province, which is located in the less-developed southwestern part of China. This study aimed to describe the oral health status of Dai preschool children in China and the factors that influence their oral health status.

Methods

An oral health survey was performed between 2011 and 2012 to select Dai five-year-old children using multi-stage stratified sampling in Yunnan. Their dental caries experience was measured using the “dmft” index, and severe caries was assessed using the “pa” index, which is modified from the “pufa” index. Oral hygiene status was assessed using the visual plaque index (VPI). A questionnaire to study the children’s socio-demographic background and oral health-related behaviours was completed by the children’s parents.

Results

A total of 833 children were examined. Their caries prevalence was 89% and 49% of the children had carious tooth with pulp involvement. The mean (SD) dmft score was 7.0 (5.3). Higher dmft scores were found among children who were girls, were currently bottle-fed, took daily sweet snacks, had higher VPI scores, and had visited a dentist within the last year.

Conclusions

The caries prevalence and experience of the five-year-old Dai children in Yunnan, China was high, and almost half had severe caries. The caries experience was associated with gender, snack habits, dental visit habits, and oral hygiene status.

     

Location and geometric description of carpal bones in CT images

The carpal regions of ten cadaver extremities were imaged by CT. The images were combined into a 3-dimensional model of the carpus using a technique based on a dynamic programming algorithm to find an optimal estimate of the location of the bone boundaries in the CT images. The resulting set of surface points on each bone was used to compute volumes and principal and antipodal axes for the bones. A spatial coordinate system was established based on the positions of the centroids of three bones in the distal carpal row. The angular orientations of all carpal bones were determined with respect to this system. The principal axes for the same bone among ten wrist specimens proved to be more widely dispersed than the antipodal axes for the same bones. The antipodal axes also correspond more closely to an intuitive notion of the “longest axis” of the bones. We conclude that the antipodal axis is a more reliable and useful measure of bone orientation than the principal axis.     

Atypical causes of hand pain

The history and physical examination allow early identification of the cause of hand pain in most patients. In some cases, however, the etiology of the pain is not obvious and a diagnostic problem arises. The less common causes of hand pain include atypical mycobacterial infection, occult fractures, bone fragments, incomplete carpal coalitions, carpal ligament injuries and several uncommon forms of tendinitis.     

Iotrol versus metrizamide in lumbar myelography: a double-blind study

In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.     

Effect of vitamin E on tamoxifen-treated breast cancer cells

BACKGROUND: Induction of apoptosis by tamoxifen has been postulated to involve oxidative stress. Tamoxifen (TAM) may act on estrogen receptors (ER) located in the plasma membrane. Our hypothesis that supplemental antioxidant vitamin E (alpha-tocopherol) acts at the plasma membrane to alter the effectiveness of tamoxifen was tested in ER-positive breast cancer cell lines, MCF-7 and T47D. METHODS: Cells were treated in vitro with 20-muM TAM alone and in combination with 10-muM alpha-tocopherol (AT). Estrogen growth signals were quantified by immunohistochemical staining for the mitogen-activated protein kinase p-ERK. Rapid changes in intracellular calcium were detected in TAM-treated MCF-7 and T-47D cells by fluorescence microscopy of cells loaded with the calcium-sensitive dye Fluo 4AM. Apoptosis was assayed by flow cytometry. RESULTS: Proliferating cells in normal medium exhibited strong p-ERK staining. Addition of TAM abolished p-ERK staining and caused cell rounding and death. The addition of AT led to the restoration of cell proliferation and p-ERK expression even in the presence of high-dose TAM. Intracellular calcium rapidly increased in MCF-7 and T47D cells upon exposure to TAM, followed by an increase in caspase activation and eventual apoptosis. The increase in intracellular calcium was abolished by the addition of 10muM AT to TAM, and pan-caspase staining decreased at 5 hours from 72% to 41%. CONCLUSIONS: These studies suggest that supplemental vitamin E decreases the inhibitory effect of TAM on the proliferation of ER+ breast cancer cells and eliminates the rapid rise in intracellular calcium that leads to apoptosis stimulated by TAM. The use of vitamin E acetate supplements may be inadvisable for women taking tamoxifen.     

Distributed controller design and performance optimization for discrete‐time linear systems

This article addresses the problem of distributed controller design for linear discrete‐time systems. The problem is posed using the classical framework of state feedback gain optimization over an infinite‐horizon quadratic cost, with an additional sparsity constraint on the gain matrix to model the distributed nature of the controller. An equivalent formulation is derived that consists in the optimization of the steady‐state solution of a matrix difference equation, and two algorithms for distributed gain computation are proposed based on it. The first method consists in a step‐by‐step optimization of said difference matrix equation, and allows for fast computation of stabilizing state feedback gains. The second algorithm optimizes the same matrix equation over a finite time window to approximate asymptotic behavior and thus minimize the infinite‐horizon quadratic cost. To assess the performance of the proposed solutions, simulation results are presented for the problem of distributed control of a quadruple‐tank process, as well as a version of that problem scaled up to 40 interconnected tanks.