47 research outputs found
Frankincense oil derived from Boswellia carteri induces tumor cell specific cytotoxicity
<p>Abstract</p> <p>Background</p> <p>Originating from Africa, India, and the Middle East, frankincense oil has been important both socially and economically as an ingredient in incense and perfumes for thousands of years. Frankincense oil is prepared from aromatic hardened gum resins obtained by tapping <it>Boswellia </it>trees. One of the main components of frankincense oil is boswellic acid, a component known to have anti-neoplastic properties. The goal of this study was to evaluate frankincense oil for its anti-tumor activity and signaling pathways in bladder cancer cells.</p> <p>Methods</p> <p>Frankincense oil-induced cell viability was investigated in human bladder cancer J82 cells and immortalized normal bladder urothelial UROtsa cells. Temporal regulation of frankincense oil-activated gene expression in bladder cancer cells was identified by microarray and bioinformatics analysis.</p> <p>Results</p> <p>Within a range of concentration, frankincense oil suppressed cell viability in bladder transitional carcinoma J82 cells but not in UROtsa cells. Comprehensive gene expression analysis confirmed that frankincense oil activates genes that are responsible for cell cycle arrest, cell growth suppression, and apoptosis in J82 cells. However, frankincense oil-induced cell death in J82 cells did not result in DNA fragmentation, a hallmark of apoptosis.</p> <p>Conclusion</p> <p>Frankincense oil appears to distinguish cancerous from normal bladder cells and suppress cancer cell viability. Microarray and bioinformatics analysis proposed multiple pathways that can be activated by frankincense oil to induce bladder cancer cell death. Frankincense oil might represent an alternative intravesical agent for bladder cancer treatment.</p
The Role of Inflammatory Mediators in the Pathogenesis of Otitis Media and Sequelae
This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K+ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued
Two-component metal injection moulding of Ti-6Al-4V and stainless steel Bi-material parts
Two-component metal injection moulding (2C-MIM) allows producing functionallygraded metal parts of complex shape by co-sintering. Until now several studies have demonstratedthat different material properties can be combined. Another promising material combination istitanium and iron-based materials. It can combine the biocompatibility and low density of titaniumwith a ductile and cost efficient stainless steel. However, co-sintering these materials revealschallenges due to a significant mismatch in sintering shrinkage and limitations in sinteringtemperature for both materials. The recent study showed that Ti-6Al-4V can be joined to thestainless steel 316L by 2C-MIM provided that certain constraints are taken into account. Thequality of the interface before and after co-sintering is a crucial factor for intact parts afterprocessing. By applying sinterdilatometry the mismatch in shrinkage was compensated by usingadjusted powder characteristics and tailored feedstock compositions. A co-sintering cycle wasdefined with regard to the sintering characteristics of both materials. The developed two-componentspecimens revealed significant interdiffusion of alloying elements at the Ti-6Al-4V / 316L interfaceand a tensile strength of about 200 MPa after co-sintering
Standards for Metal Injection Moulding: Progress to-date and future challenges
Metal Injection Moulding can today be considered as a maturing manufacturing technology for small, complex shaped metal components. A broad spectrum of materials is available for MIM production and a number of steels, titanium and titanium alloys, nickel superalloys and an increasing number of special materials such as copper, cobalt-chromium or tungsten are qualified for MIM. The need for new materials is primarily driven by upcoming applications in the automotive, aerospace and medical sectors. In order to help designers, engineers, manufacturers and customers to choose one manufacturing process over another for these new applications, it is very helpful if a reliable basis for comparison is available. Standardisation is an essential process to provide such a database of typically attain able results. In an exclusive report for Powder Injection Moulding International, Fraunhofer IFAMs Marco Mulser and Prof Dr Frank Petzoldt review progress to-date, summarise existing standards for MIM technology and consider the challenges that lie ahead in order to support the growth of new markets and applications
Combining different or even contrasting material properties using two-component metal injection moulding
Two-component metal injection moulding (2C-MIM) allows manufacturing multi-material MIM components with tailored properties. It can generate completely new design opportunities with enhanced functionality options for MIM products. Additional assembling operations are not required. Process improvements and extended experience concerning the interactions of powders at sintered interfaces advanced the 2C-MIM technology to the threshold to be launched for industrial production. In this paper, recent investigations on the process development for bi-material parts with contrasting properties as ferritic/austenitic stainless steel (magnetic/non-magnetic), steel/titanium (toughness/biocompatibility) and steel/cobalt chromium (toughness/wear resistance) are shown. The results showed that bi-material combinations can be achieved if the utilized powders and feedstocks as well as the process parameters are adjusted. Requirements for powder selection and methods to balance the shrinkage mismatches during co-sintering were developed and evaluated concerning processability, microstructure and bonding strength at the interface
Tungsten-copper / stainless steel Bi-material parts by 2C-MIM
The paper reports on investigations for two component injection moulding (2C-MIM) of bi-material parts of W-Cu and the stainless steel 316L. The feasibility of joining these different materials by co-sintering was investigated. A significant mismatch in shrinkage of tungsten and 316L was observed by sinter dilatometry. It could be compensated by adjusting the powder particle size of the stainless steel. MIM parts of both materials were sinter joined followed by infiltration with Cu powder. The tungsten-copper / stainless steel interfaces were characterized by optical microscopy. The results show that it is possible to produce an interface of tungsten-copper and stainless steel by co-sintering and infiltration. The material combination in a functionally graded part would combine the high electrical and thermal conductivity of W-Cu with a ductile and rather cheap stainless steel substrate predestinated for electrical and thermal management applications