Hybrid polycaprolactone/polyethylene oxide scaffolds with tunable fiber surface morphology, improved hydrophilicity and biodegradability for bone tissue engineering applications

In the present study, we attempt to modify Polycaprolactone (PCL) by blending it with a water soluble polymer Polyethyleneoxide (PEO) having two different molecular weights (Mv ~1,00,000 and 6,00,000) using electrospinning technique. The effect of PEO molecular weight and blend ratio on fiber morphology, porosity, surface wettability, static and dynamic mechanical properties of PCL was investigated. In vitro degradation studies in phosphate buffer saline (PBS) at 37 °C demonstrated formation of pores on fiber surface especially in blend scaffolds with 50:50 ratios. In vitro studies using human osteoblast sarcoma (hOS) cell lines on blend scaffolds showed improved cellular response with good cell adhesion, viability and proliferation. The study revealed that incorporation of PEO on PCL scaffolds complemented the properties of PCL and facilitated fabrication of scaffolds with improved hydrophilicity, mechanical property and tunable degradation profile with better cell viability which makes it an ideal candidate for bone tissue engineering applications.

Biomimetic approaches with smart interfaces for bone regeneration

A 'smart tissue interface' is a host tissue-biomaterial interface capable of triggering favourable biochemical events inspired by stimuli responsive mechanisms. In other words, biomaterial surface is instrumental in dictating the interface functionality. This review aims to investigate the fundamental and favourable requirements of a 'smart tissue interface' that can positively influence the degree of healing and promote bone tissue regeneration. A biomaterial surface when interacts synergistically with the dynamic extracellular matrix, the healing process become accelerated through development of a smart interface. The interface functionality relies equally on bound functional groups and conjugated molecules belonging to the biomaterial and the biological milieu it interacts with. The essential conditions for such a special biomimetic environment are discussed. We highlight the impending prospects of smart interfaces and trying to relate the design approaches as well as critical factors that determine species-specific functionality with special reference to bone tissue regeneration.

Incidence of Onchocerca gibsoni in subcutaneous nodules of cross bred Jersey cows: case report

Onchocerca gibsoni subcutaneous nodules in four cross bred Jersey cows aged 5-6 years brought for post mortem with calcified and caseated skin nodules in the lateral flank region is reported. Examination and dissection of these nodules revealed that they were "worm nests" of Onchocerca sp. of filarid nematodes. The worm nests were carefully dissected and filarid worms were extracted out. Multiple numbers of worms were recovered from each nodule ranging from 15 to 20. Female worms were found inside the worm nests and were found to be filled with microfilariae. The nodules weighed 2-3 g. Based on the morphological features the worms were identified as O. gibsoni.

Occurrence of Knemidokoptes mutans and Laminosioptes cysticola in backyard poultry in India

Birds reared in backyard poultry farming system are more prone to parasitic infestation resulting in economic losses to rural community. The present study reports occurrence of Knemidokoptes mutans and Laminosioptes cysticola mites in a male Aseel bird. Clinical signs observed in the affected bird include hyperkeratosis with whitish film layer on shank and hock region of legs. Focal areas of sloughing of skin with oozing of blood were also observed on the back and on the legs. Examination of skin scrapings from the affected sites revealed different developmental stages of Knemidokoptes mutans and Laminosioptes cysticola mites. This paper reports occurrence of L. cysticola for the first time from India. The bird was treated with ivermectin injection through intramuscular route.

Ganga hospital open injury score in management of open injuries

INTRODUCTION

Open injuries of the limbs offer challenges in management as there are still many grey zones in decision making regarding salvage, timing and type of reconstruction. As a result, there is still an unacceptable rate of secondary amputations which lead to tremendous waste of resources and psychological devastation of the patient and his family. Gustilo Anderson's classification was a major milestone in grading the severity of injury but however suffers from the disadvantages of imprecise definition, a poor interobserver correlation, inability to address the issue of salvage and inclusion of a wide spectrum of injuries in Type IIIb category. Numerous scores such as Mangled Extremity Severity Score, the Predictive Salvage Index, the Limb Salvage Index, Hannover Fracture Scale-97 etc have been proposed but all have the disadvantage of retrospective evaluation, inadequate sample sizes and poor sensitivity and specificity to amputation, especially in IIIb injuries.

METHODS

The Ganga Hospital Open Injury Score (GHOIS) was proposed in 2004 and is designed to specifically address the outcome in IIIb injuries of the tibia without vascular deficit. It evaluates the severity of injury to the three components of the limb--the skin, the bone and the musculotendinous structures separately on a grade from 0 to 5. Seven comorbid factors which influence the treatment and the outcome are included in the score with two marks each. The application of the total score and the individual tissue scores in management of IIIB injuries is discussed.

RESULTS

The total score was shown to predict salvage when the value was 14 or less; amputation when the score was 17 and more. A grey zone of 15 and 16 is provided where the decision making had to be made on a case to case basis. The additional value of GHOIS was its ability to guide the timing and type of reconstruction. A skin score of more than 3 always required a flap and hence it indicated the need for an orthoplastic approach from the index procedure. Bone score of 4 and 5 will require complex reconstruction procedures like bone transport, extensive bone grafting or free fibular graft. Regarding the timing of reconstruction, injuries with a score of 9 or less indicated a low violence trauma and were amenable for early soft tissue reconstruction whereas injuries with a score of 10 or more indicated high violence injuries where a staged reconstruction policy must be followed.

CONCLUSIONS

Ganga Hospital Open Injury Score was found to be highly useful in decision making regarding salvage in IIIB injuries. The individual tissue scores were also useful to provide guidance regarding the timing and type of bone and soft tissue reconstruction.

CD40 signaling drives B lymphocytes into an intermediate memory-like state, poised between naïve and plasma cells

Immunological memory comprising of antigen-specific B and T cells contributes to the acquisition of long-term resistance to pathogens. Interactions between CD40 on B cells and CD40L on T cells are responsible for several aspects of acquired immune responses including generation of memory B cells. In order to gain insights into events leading to memory B cell formation, we analyzed the genome-wide expression profile of murine naive B cells stimulated in the presence of anti-CD40. We have identified over 8,000 genes whose expression is altered minimally 1.5-fold at least at one time point over a 3-day time course. The array analysis indicates that changes in expression level of maximum number of these genes occur within 24 h of anti-CD40 treatment. In parallel, we have studied the events following CD40 ligation by examining the expression of known regulators of naive B cell to plasma cell transition, including Pax5 and BLIMP1. The expression profile of these regulatory genes indicates firstly, that CD40 signaling activates naïve B cells to a phenotype that is intermediate between the naive and plasma cell stages of the B cell differentiation. Secondly, the major known regulator of plasma cell differentiation, BLIMP1, gets irreversibly downregulated upon anti-CD40 treatment. Additionally, our data reveal that CD40 signaling mediated BLIMP1 downregulation occurs by non-Pax5/non-Bcl6 dependent mechanisms, indicating novel mechanisms at work that add to the complexity of understanding of B cell master regulatory molecules like BLIMP1 and Pax5.

Nanohydroxyapatite incorporated electrospun polycaprolactone/polycaprolactone-polyethyleneglycol-polycaprolactone blend scaffold for bone tissue engineering applications

The present work is a comparative evaluation of physical and biological properties of electrospun biodegradable fibrous scaffolds based on polycaprolactone (PCL) and its blend with polycaprolactone-polyethyleneglycol-polycaprolactone (CEC) with and without nanohydroxyapatite (nHAP) particles. The fiber morphology, porosity, surface wettability, and mechanical properties of electrospun PCL were distinctly influenced by the presence of both copolymer CEC and nHAP. The degradation in hydrolytic media affected both morphological and mechanical properties of the scaffolds and the tensile strength decreased by 58% for PCL, 83% for PCL/CEC, 36% for PCL/nHAP and 75% for PCL/CEC/nHAP in 90 days of PBS ageing. MTT assay using mouse fibroblast L929 cells proved all the scaffolds to be non-cytotoxic. An overall enhanced performance was shown by PCL/CEC/nHAP scaffold in cell viability (LPH) and proliferation (Picogreen). Simultaneously, ELF assay of ALP activity (bone marker) confirmed the presence of osteogenic-induced Rabbit adipose-derived mesenchymal stem cells (ADMSCs) on all the scaffolds. In comparison, the results reveal the potential of the cytocompatible PCL/CEC/nHAP scaffold for the fabrication of living bony constructs for tissue engineering applications.

4-(2-Hydroxyphenyl)-3,5-dithiaheptanedioic acid

In the crystal of the title compound, C₁₁H₁₂O₅S₂, mol­ecules are linked by O—H⋯O hydrogen bonds and C—H⋯O inter­actions, forming a three-dimensional network.

Electrospun biodegradable calcium containing poly(ester-urethane)urea: synthesis, fabrication, in vitro degradation, and biocompatibility evaluation

In this work an in vitro degradable poly(ester-urethane)urea (PEUU) was synthesized using polycaprolactone diol, hexamethylene diisocyanate, and calcium salt of p-aminobenzoic acid. The synthesized polymer was characterized by (1) H-NMR and FTIR spectroscopy and viscosity studies. Scaffolds having random micro fibrous structures were fabricated from PEUU by electrospinning process. The thermal properties of the scaffold were evaluated by thermogravimetric analysis and dynamic mechanical analysis. The mechanical property evaluation showed that the scaffold possess sufficiently high tensile strength of 16 MPa. The in vitro degradation studies of the electrospun scaffold were carried out in phosphate buffer saline for 6 months. The average mass loss of the scaffold after 6 months of hydrolytic degradation was 25%. FTIR spectroscopy study confirmed the degradation of the PEUU from decrease in intensity of 1400 cm(-1) peak corresponding to ionic carboxylate group. Presence of amine group and calcium ions in the degradation medium further confirmed the degradation of the hard segment in the hydrolytic medium. The mechanical property evaluation of the scaffold indicated a gradual decrease in tensile strength and modulus whereas percentage elongation of the scaffold increases with time of in vitro degradation. The morphological evaluation of the scaffold after degradation by SEM shows evidence of broken fibers and pores in the scaffold. Preliminary in vitro cytotoxicity test demonstrated that both the material and the degradation products were noncytotoxic in nature and the material showed good proliferation to L-929 cells.

Structural characterization, mechanical properties, and in vitro cytocompatibility evaluation of fibrous polycarbonate urethane membranes for biomedical applications

This paper reports the electrospinning of a series of oxidatively stable polycarbonate urethanes (PCU) [carbothane (ECT), bionate (EBN), and chronoflex (ECF)] using N,N-dimethyl formamide and tetrahydrofuran as the mixed solvent. The nonwoven membranes were characterized for their structure, performance, and compatibility with cells. Scanning electron microscope was utilized to study the structural morphology and fiber diameter. Microcomputed tomography (micro-CT) was used to characterize the 3D architecture, pore size distribution, and percentage porosity. All the membranes displayed a porous architecture with average fiber diameter in the range of 1.5-2 μm. Static mechanical tests on the membranes revealed that the tensile strength was greater than 7 MPa and the dynamic mechanical tests showed that the average storage modulus (E(i) ) is 2 MPa at 37°C. PCU membranes were subjected to accelerated in vitro degradation for 90 days in 20% hydrogen peroxide/0.1M cobalt chloride solution. Mechanical characterization of the membranes postdegradation confirmed a 64% reduction in tensile strength for EBN at the end of 90 days where as ECF and ECT did not show any significant mechanical property deterioration in the oxidative medium. Cytotoxicity of the membranes was evaluated using L929 fibroblast cells and the results indicated that all the PCU membranes were cytocompatible and showed good adherence to L929 cells. Accordingly, these results highlight the potential of these fibrous PCU membranes for biomedical applications but further in vivo correlation studies are required for better understanding of the biodegradation and biological efficacy.