Synthesis of cerium, zirconium, and copper doped zinc oxide nanoparticles as potential biomaterials for tissue engineering applications

A novel eco-friendly high throughput continuous hydrothermal flow system was used to synthesise phase pure ZnO and doped ZnO in order to explore their properties for tissue engineering applications. Cerium, zirconium, and copper were introduced as dopants during flow synthesis of ZnO nanoparticles, Zirconium doped ZnO were successfully synthesised, however secondary phases of CeO and CuO were detected in X-ray diffraction (XRD). The nanoparticles were characterised using X-ray diffraction, Brunauer-Emmett-Teller (BET), Dynamic Light scattering Measurements, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and RAMAN spectroscopy was used to evaluate physical, chemical, and structural properties. The change in BET surface area was also significant, the surface area increased from 11.35 (ZnO_2) to 26.18 (ZrZnO_5). However. In case of CeZnO_5 and CuZnO_5 was not significant 13.68 (CeZnO_5) and 12.16 (CuZnO_5) respectively. Cell metabolic activity analysis using osteoblast-like cells (MG63) and human embryonic derived mesenchymal stem cells (hES-MP) demonstrated that doped ZnO nanoparticles supported higher cell metabolic activity compared to cells grown in standard media with no nanoparticles added, or pure zinc oxide nanoparticles. The ZrZnO_5 demonstrated the highest cell metabolic activity and non-cytotoxicity over the duration of 28 days as compared to un doped or Ce or Cu incorporated nanoparticles. The current data suggests that Zirconium doping positively enhances the properties of ZnO nanoparticles by increasing the surface area and cell proliferation. Therefore, are potential additives within biomaterials or for tissue engineering applications.

Preparation, characterization and in vitro osteoblast growth of waste-derived biomaterials

Preparation, characterization and in vitro osteoblast growth of beer bagasse derived biomaterial.

Improvements in cheek volume in lipoatrophic individuals switching away from thymidine nucleoside reverse transcriptase inhibitors

BACKGROUND

Thymidine nucleoside reverse transcriptase inhibitors (NRTIs) are associated with subcutaneous fat loss. Facial changes cannot be assessed by dual-energy X-ray absorptiometry (DEXA) scans. There are limited objective data on the reversibility of facial lipoatrophy.

METHODS

We performed a facial volume substudy of a randomized thymidine NRTI replacement study carried out in HIV-infected subjects with moderate to severe lipoatrophy. Facial volume changes were assessed using validated 3D laser imaging. Changes in body composition were measured using DEXA scans. The association between changes in facial volume and body composition parameters at 48 weeks was measured using Spearman's rank correlation.

RESULTS

Forty-seven individuals (46 male), 11 receiving zidovudine and 36 receiving stavudine, switched to either tenofovir disoproxil fumarate (DF) (n=23) or abacavir (ABC) (n=24). Thirty-nine of these 47 patients (84.8%) reported facial lipoatrophy at baseline. The median volume increase in both cheeks from baseline was 1857.3 mm(3). These volume changes and increases in limb fat at 48 weeks were similar in the two groups and correlated significantly (Spearman's r=0.41, P=0.004).

CONCLUSIONS

Facial volume in lipoatrophic individuals was found to increase after thymidine NRTI replacement. We demonstrated a significant correlation between improvements in facial and limb fat parameters. Switching from thymidine NRTIs in patients with facial lipoatrophy could potentially reduce the need for cosmetic interventions.

Vascularized adipose tissue grafts from human mesenchymal stem cells with bioactive cues and microchannel conduits

Vascularization is critical to the survival of engineered tissues. This study combined biophysical and bioactive approaches to induce neovascularization in vivo. Further, we tested the effects of engineered vascularization on adipose tissue grafts. Hydrogel cylinders were fabricated from poly(ethylene glycol) diacrylate (PEG) in four configurations: PEG alone, PEG with basic fibroblast growth factor (bFGF), microchanneled PEG, or both bFGF-adsorbed and microchanneled PEG. In vivo implantation revealed no neovascularization in PEG, but substantial angiogenesis in bFGF-adsorbed and/or microchanneled PEG. The infiltrating host tissue consisted of erythrocyte-filled blood vessels lined by endothelial cells, and immunolocalized to vascular endothelial growth factor (VEGF). Human mesenchymal stem cells were differentiated into adipogenic cells, and encapsulated in PEG with both microchanneled and adsorbed bFGF. Upon in vivo implantation subcutaneously in immunodeficient mice, oil red O positive adipose tissue was present and interspersed with interstitial fibrous (IF) capsules. VEGF was immunolocalized in the IF capsules surrounding the engineered adipose tissue. These findings suggest that bioactive cues and/or microchannels promote the genesis of vascularized tissue phenotypes such as the tested adipose tissue grafts. Especially, engineered microchannels may provide a generic approach for modifying existing biomaterials by providing conduits for vascularization and/or diffusion.

Observational study of perioperative P tc co2 and S p o2 in non-ventilated patients receiving epidural infusion or patient-controlled analgesia using a single earlobe monitor (TOSCA) †

BACKGROUND

TOSCA, a non-invasive monitor with a single earlobe probe incorporating a Stow-Severinghaus electrode and optical sensor (Linde Medical Sensors AG, Basel, Switzerland), has previously been used with ventilated patients and in sleep laboratories. We recorded transcutaneous carbon dioxide pressures (Ptc(co(2)) and oxygen saturations (Sp(o(2)) in non-ventilated patients to investigate opioid-induced respiratory depression.

METHODS

This observational cohort study included 28 ASA I and II patients, monitored between 10 p.m. and 6 a.m., before and after elective major laparotomy. After operation, patients were kept on oxygen, 4 litre min(-1), and received either bupivacaine (0.1%) containing fentanyl (2 microg ml(-1) via epidural catheter (epidural analgesia group, EPI; n = 14) or morphine via patient-controlled analgesia infusion pump (PCA-morphine group, PCA; n = 14).

RESULTS

The preoperative median (lower/upper quartile) Ptc(co(2)) was similar in both groups at around 5.5 kPa, but significantly higher after operation in PCA with 6.9 kPa (5.6/7.3) (P = 0.02), accompanied by a longer hypercarbia time >6 kPa of 6.6 h (0.1/8.0) (P = 0.04), and lower respiratory rates of 13.9 breaths min(-1) (13.3/15.4) (P = 0.04). In EPI, the corresponding results were 5.8 kPa (5.5/6.0), 1.2 h (0.1/4.3), and 16.2 breaths min(-1) (14.8/16.7). The perioperative median Sp(o(2)) in both groups was comparable within the normal range, although generally higher when on supplemental oxygen (P = 0.26). The Sp(o(2)) time <94% was similar in both groups (P = 0.33) as were pain scores (P = 0.25).

CONCLUSIONS

Ptc(co(2)) recording in patients on PCA-morphine and supplemental oxygen revealed hypercapnia in the presence of normal respiratory rates and Sp(o(2)) values. This is recommended as an easy and sensitive monitor of respiratory depression and may have a role in the safe administration of opioid-analgesia.

Solution-mediated effect of bioactive glass in poly (lactic-co-glycolic acid)-bioactive glass composites on osteogenesis of marrow stromal cells

A previous study demonstrated that the incorporation of bioactive glass (BG) into poly (lactic-co-glycolic acid) (PLGA) can promote the osteoblastic differentiation of marrow stromal cells (MSCs) on PLGA by promoting the formation of a calcium-phosphate-rich layer on its surface. To further understand the mechanisms underlying the osteogenic effect of PLGA-BG composite scaffolds, whether solution-mediated factors derived from composite scaffolds/hybrids can promote osteogenesis of marrow stromal cells was tested. The dissolution product from PLGA-30%BG scaffold stimulated osteogenesis of MSCs, as was confirmed by increased mRNA expression of osteoblastic markers such as osteocalcin (OCN), alkaline phosphatase (ALP), and bone sialoprotein (BSP). The three-dimensional structure of the scaffolds may contribute to the production of cell-derived factors that promoted distant MSC differentiation. Thus PLGA-BG composites demonstrate significant potential as a bone-replacement material.

Osteogenic effects of bioactive glass on bone marrow stromal cells

Bioactive glass (BG) is an effective synthetic bone graft material. BG granules of narrow size range (300-355 mum) have the ability to form new bone tissue inside excavations produced by in vivo resorption. Previously, we demonstrated that BG stimulates the differentiation of cultured osteoblast precursors if the glass surface was biomimetically modified by the formation of bone-like apatite and adsorption of serum proteins. We now report that modified BG can also increase the rate at which multipotential rat bone marrow stromal cells (rMSC) will undergo osteogenesis. BG promoted rMSC osteogenesis both when cells were plated in contact with BG and when cells were not directly in contact with the BG. Alkaline phosphatase activity, a marker of bone cell differentiation, was used as an indicator for osteogenesis. Alkaline phosphatase activity of rMSCs exposed to osteoinducers such as ascorbate, dexamethasone, and BMP-2 was enhanced in the presence of BG. The stimulatory effect of BG was more pronounced in rMSC cultures with low basal alkaline phosphatase activity than in those with higher activity. The enhanced differentiation of rMSCs was associated with both a change in rMSC morphology and altered chemical composition of the cell culture media. rMSCs cultured on BG in the presence of BMP or dexamethasone exhibited a more rounded osteoblast-like appearance as compared with cells grown on tissue culture plastic. In the presence of BG, elevated levels of calcium and silicon in the culture medium were observed throughout the 7-day culture period, suggesting a continuous dissolution of surface-modified BG and resulting release of BG dissolution products. The data suggest that both surface- and solution-mediated events play a role in the osteogenic effect of BG.

Topical glucocorticoids inhibit activation by allergen in the upper respiratory tract

We have studied the effect of a topically administered glucocorticoid, fluticasone propionate (FP), on infiltration and activation of eosinophils in the nasal mucosa after provocation with allergen. Forty-four patients with seasonal allergic rhinitis entered a double-blind, crossover study in which they underwent treatment with either FP (200 micrograms once daily) or identical placebo for 2 weeks. Patients then underwent nasal-allergen provocation followed by nasal lavage and biopsy at one of several time points between 0 and 8 hours. Patients subsequently received the alternate treatment for 2 weeks before repeat allergen provocation, nasal lavage, and biopsy, as before. Biopsy specimens of nasal mucosa obtained during the immediate allergic response demonstrated an influx of eosinophils (stained by monoclonal antibody EG1) of similar magnitude during both FP and placebo treatment. Significantly, fewer eosinophils in these biopsy specimens were activated (stained by monoclonal antibody EG2) after treatment with FP compared with that after placebo treatment (median values, 8.8 and 36.6 cells per square millimeter, respectively; p less than 0.02). The concentration of eosinophil cationic protein in nasal lavage fluid was significantly elevated above baseline from 2 to 8 hours after allergen, and this increase was abolished by treatment with FP. These results suggest that topical glucocorticoids inhibit allergen-induced activation of eosinophils in allergic rhinitis.

Necrobacillosis--an unusual cause of cervical abscess

Necrobacillosis is a rare infection which may be fatal if inadequately treated. We present a case demonstrating the classical clinical picture upon which correct diagnosis depends. The need for a high index of suspicion is highlighted and appropriate management is discussed.

Antibiotic/steroid ear drop preparations: a cost-effective approach to their use

Otorrhoea is a common otological complaint reflecting infection in the outer and/or middle ear. Guidelines as to which antibiotic/steroid ear drop preparation to use in a treatment regime are few and no studies comparing the different types of preparation are available. This paper reviews the antibiotic/steroid ear drop preparations used by consultant surgeons and general practitioners and presents a two fold rationale for deciding which preparation to use, based on microbial sensitivity and cost.

Fine needle aspiration cytology in dermatology: a clinicopathological appraisal

The possible clinical value of fine needle aspiration cytology (FNAC) has been assessed prospectively in 60 patients presenting with cutaneous lesions. The cytological diagnosis in each case has been compared with the clinical diagnosis and biopsy result. The principal potential use appears to be the rapid confirmation of the clinical diagnosis of basal cell carcinoma to allow immediate referral for radiotherapy or plastic surgery. FNAC could also prove useful when the clinical diagnosis of malignant melanoma is in doubt and primary diagnostic excision is difficult or disfiguring. Accurate distinction could usually be made between benign and malignant lymphoproliferative conditions, but further classification was difficult. Metastatic malignancy could be diagnosed with ease and other characteristic cytological appearances were seen with naevocellular naevi, pyogenic granuloma and pilar cysts. However, there were limitations in achieving an accurate diagnosis in approximately half the cases, and consequently, FNAC cannot be regarded in general as a substitute for histological diagnosis.

Fractures of the floor of the anterior cranial fossa. The selection of patients for dural repair

A series of 87 patients operated on because of subfrontal fractures is reported. In 73 of these a fistulous lesion (connecting the brain with the nose or the accessory air sinuses) was displayed and was repaired. Almost always a bifrontal exploration has been made, because the lesions were bifrontal in 43 per cent of cases. The mean follow-up period was 4 years; to date no instances of postoperative meningitis or rhinorrhoea have occurred. Our experience suggests that cerebrospinal rhinorrhoea accompanying fractures of the facial bones (without fractures of the skull vault) can safely be treated conservatively. Damaged brain adheres to the lips of the torn dura and permanently prevents natural healing, thereby creating a continuing threat to life. Consequently it is recommended that all frontal fractures lying below the hairline and all comminuted anterior temporal fractures should be referred for expert neurosurgical/neuroradiological assessment. This is because 42 per cent of the patients requiring operative repair were selected after tomographic studies of the anterior fossa; they had not presented with the classic criteria of cerebrospinal rhinorrhoea, intracranial air, or meningitis.