Bone tissue engineering using polymer based scaffolds have been studied a lot in last decades. Considering the qualities of all the polymers desired to be used as scaffolds, Polycaprolactone (PCL) polyester apart from being biocompatible and biodegradable qualifies to an appreciable level due its easy availability, cost efficacy and suitability for modification. Its adjustable physio-chemical state, biological properties and mechanical strength renders it to withstand physical, chemical and mechanical, insults without significant loss of its properties. This review aims to critically analyse the efficacy of PCL as a biomaterial for bone scaffolds. 1.1. Polymers as biomaterial for scaffolds The characteristics of a biomaterial that must be scrutinized thoroughly before considering it for bone tissue engineering applications includes chemical composition, biological and structural characteristics, degradation behavior and fabrication process. Polymeric scaffolds are of considerable interest due to their distinctive features, such
SummaryOver 330,000 individuals in the United States depend on hemodialysis (HD), the majority as a result of endstage renal disease. Sustainable vascular access can be achieved through arteriovenous fistulas, arteriovenous grafts, or tunneled catheters. Tunneled dialysis catheters (TDCs) often remain in use for months or even years, long beyond their initial intended use as a bridging device. Research efforts are focused on identifying strategies to prevent/minimize the risk of the most common catheter-related complications: thrombotic occlusion and infection. Thrombotic occlusion of TDCs prevents adequate dialysis but can be managed successfully through thrombolytic agents to restore/improve blood flow in the majority of patients, allowing immediate HD delivery and prolonging usability of the TDC. Occasionally, catheter exchange with fibrin sheath disruption is needed to preserve the site. Surface-treated catheters could improve the morbidity and mortality associated with HD delivery via an indwelling catheter, but results from studies have been disappointing to date. We review the etiology of catheter-based access failure and the monitoring and interventional steps that should be taken to maintain the patency and safety of catheters for HD. Wherever possible we note the areas in which there is scant data where further randomized clinical trials are needed.
Effects of temperature on biological processes are complex. Diffusion is less affected than the diverse enzymatic reactions that have distinct individual temperature profiles. Hence thermal fluctuations pose a formidable challenge to ectothermic organisms in which body temperature is largely dictated by the ambient temperature. How cells in ectotherms cope with the myriad disruptive effects of temperature variation is poorly understood at the molecular level. Here we show that nucleocytoplasmic posttranslational modification of proteins with O-linked GlcNAc (O-GlcNAc) is closely correlated with ambient temperature during development of distantly related ectotherms ranging from the insect Drosophila melanogaster to the nematode Caenorhabditis elegans to the fish Danio rerio. Regulation seems to occur at the level of activity of the only two enzymes, O-GlcNAc transferase and O-GlcNAcase, that add and remove, respectively, this posttranslational modification in nucleus and cytoplasm. With genetic approaches in D. melanogaster and C. elegans, we demonstrate the importance of high levels of this posttranslational modification for successful development at elevated temperatures. Because many cytoplasmic and nuclear proteins in diverse pathways are O-GlcNAc targets, temperature-dependent regulation of this modification might contribute to an efficient coordinate adjustment of cellular processes in response to thermal change.O-GlcNAcylation | temperature acclimation A mbient temperature can fluctuate over various time scales and degrees in different ecological niches. Organisms cope with thermal fluctuations using alternative strategies. Endotherms like humans rely primarily on internally generated heat in combination with intricate regulation for maintenance of a relatively high and constant core body temperature. In contrast, the majority of organisms are ectotherms that produce far less heat. Their internal temperature is primarily dictated by the environment. Cells in some ectotherms are able to acclimate over a remarkable range of ambient temperatures even though temperature change has pervasive effects. All biological processes depend on temperature, but notably not in a uniform manner. Compensation of the myriad disruptive effects of temperature change at the cellular level necessitates extremely complex regulation. Our understanding of the responsible molecular mechanisms is still remarkably poor, even though ambient temperature is often the major ecological determinant of species range.Beyond advanced genetics, Drosophila melanogaster embryos provide additional advantages for studies at the cellular and molecular level, because behavioral responses to temperature change do not yet occur during the immotile early stages. Our characterization of temperature effects on early D. melanogaster development has revealed a unique temperature sensitivity of posttranslational modification of nucleocytoplasmic proteins with O-linked GlcNAc (O-GlcNAc). O-GlcNAc modification is known to occur on thousands of proteins involve...
Separase cleaves a subunit of the cohesin complex and thereby promotes sister chromatid separation during mitotic and meiotic divisions. Drosophila separase associates with regulatory subunits encoded by the pimples and three rows genes. Three rows and Pimples, the Drosophila securin, are required for sister chromatid separation during mitosis. Budding yeast separase provides other functions in addition to cohesin subunit cleavage, which are required for spindle organization and temporal regulation during exit from mitosis. Therefore, using time-lapse imaging in live embryos, we have carefully analyzed progression through mitosis in pimples and three rows mutants. We demonstrate that despite the total failure of sister chromatid separation, exit from mitosis, including a complete cytokinesis, proceeds with only a minor temporal delay in the epidermal cells of these mutants. Interestingly, however, pronounced defects in the epithelial organization develop in the following interphase, indicating that the separase complex is not only important for genetic stability but also and perhaps indirectly for epithelial integrity.
The present study extended the universal applicability of children fear survey schedule -dental subscale, while at the same time it was able to highlight different facets of problem in different environments.
Trauma accounts for the principal etiologic factor of mortality in the first 40 years of life. According to the World Health Organization (WHO), almost 1 million people die and approximately 15 to 20 million are injured annually in road traffic accidents (RTAs). 1 In India, the world's second most populated country, the trauma "epidemic" claims lakhs of lives every year. 2 We are experiencing an increasing trend in injuries, particularly due to road traffic accident (RTA), at an alarming annual rate of 3%. 3 Studies have found that maxillofacial injuries occur in approximately 5 to 33% of patients experiencing severe trauma. 4 Indians with injuries are reported to be six times more at risk of death as compared with their counterparts from developed countries. 5 Therefore, maxillofacial injury management requires adequate patient documentation, injury surveillance, and re-creation of data that adequately describe the whole spectrum of injuries. 6 This would enable health planners and providers to specifically address the burden of maxillofacial injuries, and thus develop suitable preventive programs aimed at lowering the incidence of these through more efficient planning for resource allocation and delivering adequate care. 7-9 The etiology of facial trauma also affects the Keywords ► maxillofacial injury ► road traffic accident ► trauma AbstractThis study aimed to obtain dependable epidemiologic data of the variation in cause and characteristics of maxillofacial fractures by identifying, describing, and quantifying trauma. This retrospective study was conducted in the state of Uttar Pradesh, India, over 1 year, based on a systematic computer-assisted database search from March 2015 to March 2016 for maxillofacial fractures. The demographics, etiology, geographic distribution, date of injury, site and number of fractures, and type of intervention were recorded for each. The study population consisted of 1,000 patients with 1,543 fractures. The male:female ratio was 8:1. A peak incidence of fractures was seen in the third decade (mean age: 30.3) with maximum patients younger than 40 years (80.8%). The incidence of fractures was highest in spring (42.9%). Road traffic accidents were the most common cause of trauma (64.4%) and mainly involved two wheelers (60.2%). Single-site fractures were most common. Mostly zygomatic (45.1%) and mandibular fractures (44.4%) were encountered, accounting for approximately 90% of all fractures. The main site of mandibular fractures was the body (34.4%); 46.2% of fractures underwent open reduction and internal fixation (ORIF) while 53.8% were treated by closed methods. The study provides important data to contrive future plans for injury prevention. The trend of most traffic-related injuries continues with the increasing traffic on roads. Zygomatic complex and mandibular fractures remain the most frequent. The major populations at risk are young men and those driving two wheelers. The use of helmets could achieve a large reduction in maxillofacial fractures. Awareness for preventive ...
Polyhydroxyalkanoates (PHA) are prokaryotic macromolecules accumulated within the cytoplasm as granules. Due to their suitable mechanical properties, biocompatibility, degradation time, ability to be blended, surface modified, and form copolymers, it is widely used in medical devices and as scaffolds in bone tissue engineering. This review describes in brief the production and extraction sources, physico-chemical characteristic, mechanical properties, degradation rate and applications of various PHAs and its copolymers with special emphasis to its role as scaffolds in bone tissue engineering.
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