Tailoring second-harmonic generation in birefringent poled fiber via Twist

We predict theoretically and demonstrate experimentally the ability to generate and control the strengths of various second-harmonic signals in birefringent poled fiber. This is done by simply twisting the fiber

Regulation of hypoxia-inducible factor-1α (HIF-1α) expression by interleukin-1β (IL-1β), insulin-like growth factors I (IGF-I) and II (IGF-II) in human osteoarthritic chondrocytes

Objective: Hypoxia-inducible factor 1 alpha regulates genes related to cellular survival under hypoxia. This factor is present in osteroarthritic chondrocytes, and cytokines, such as interleukin-1 beta, participate in the pathogenesis of osteoarthritis, thereby increasing the activities of proteolytic enzymes, such as matrix metalloproteinases, and accelerating cartilage destruction. We hypothesize that Hypoxia Inducible Factor-1 alpha (HIF-1α) can regulate cytokines (catabolic action) and/or growth factors (anabolic action) in osteoarthritis. The purpose of this study was to investigate the modulation of HIF-1α in human osteoarthritic chondrocytes by interleukin-1 beta (IL-1β) and insulin-like growth factors I (IGF-I) and II (IGF-II) and to determine the involvement of the phosphatidylinositol-3- kinase (PI-3K) pathway in this process. Methods: Human osteroarthritic chondrocytes were stimulated with IL-1β, IGF-I and IGF-II and LY294002, a specific inhibitor of PI-3K. Nuclear protein levels and gene expression were analyzed by western blot and quantitative reverse transcription-polymerase chain reaction analyses, respectively. Results: HIF-1α expression was upregulated by IL-1β at the protein level but not at the gene level. IGF-I treatment resulted in increases in both the protein and mRNA levels of HIF-1α, whereas IGF-II had no effect on its expression. However, all of these stimuli exploited the PI-3K pathway. Conclusion: IL-1β upregulated the levels of HIF-1α protein post-transcriptionally, whereas IGF-I increased HIF-1α at the transcript level. In contrast, IGF-II did not affect the protein or gene expression levels of HIF-1α. Furthermore, all of the tested stimuli exploited the PI-3K pathway to some degree. Based on these findings, we are able to suggest that Hypoxia inducible Factor-1 exhibits protective activity in chondrocytes during osteoarthritis. © 2012 CLINICS.6713540Martel-Pelletier, J., Pathophysiology of osteoarthritis (2004) Osteoarthritis Cartilage., 12 (SUPPL. A), pp. S31-S33. , doi: 10.1016/j.joca.2003.10.002Malemud, C.J., Cytokines as therapeutic targets for osteoarthritis (2004) BioDrugs., 18, pp. 23-35. , doi: 10.2165/00063030-200418010-00003van der Kraan, P.M., van den Berg, W.B., Anabolic and destructive mediators in osteoarthritis (2000) Curr Opin Clin Nutr Metab Care., 3, pp. 205-211. , doi: 10.1097/00075197-200005000-00007Semenza, G.L., Expression of hypoxia-inducible factor 1: Mechanisms and consequences (2000) Biochem Pharmacol., 59, pp. 47-53. , doi: 10.1016/S0006-2952(99)00292-0Semenza, G.L., Hypoxia-inducible factor 1: Control of oxygen homeostasis in health and disease (2001) Pediatr Res., 49, pp. 614-617. , doi: 10.1203/00006450-200105000-00002Bardos, J.I., Ashcroft, M., Negative and positive regulation of HIF-1: A complex network (2005) Biochim Biophys Acta., 1755, pp. 107-120Honorati, M.C., Cattini, L., Facchini, A., IL-17, IL-1beta and TNF-alpha stimulate VEGF production by dedifferentiated chondrocytes (2004) 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3915-3918Blumenfeld, I., Livne, E., The role of transforming growth factor (TGF)-beta, insulin-like growth factor (IGF)-1, and interleukin (IL)-1 in osteoarthritis and aging of joints (1999) Exp Gerontol., 34, pp. 821-829. , doi:10.1016/S0531-5565(99)00062-5Loeser, R.F., Shanker, G., Autocrine stimulation by insulin-like growth factor 1 and insulin-like growth factor 2 mediates chondrocyte survival in vitro (2000) Arthritis Rheum., 43, pp. 1552-1559. , doi: 10.1002/1529-0131(200007)43:7,1552::AID-ANR20.3.0.CO;2-WKellgren, J.H., Lawrence, J.S., Radiological assessment of osteoarthrosis (1957) Ann Rheum Dis., 16 (4), pp. 494-502Reginato, A.M., Iozzo, R.V., Jimenez, S.A., Formation of nodular structures resembling mature articular cartilage in long-term primary cultures of human fetal epiphyseal chondrocytes on a hydrogel substrate (1994) Arthritis Rheum., 37, pp. 1338-1349. , doi: 10.1002/art.1780370912Jaakkola, P., Mole, D.R., Tian, Y.M., Wilson, M.I., Gielbert, J., Gaskell, S.J., Targeting of HIF-alpha to the von Hippel-Lindau ubiquitylation complex by O2-regulated prolyl hydroxylation (2001) Science., 292, pp. 468-472. , doi: 10.1126/science.1059796Dignam, J.D., Lebovitz, R.M., Roeder, R.G., Accurate transcription initiation by RNA polymerase II in a soluble extract from isolated mammalian nuclei (1983) Nucleic Acids Res., 11, pp. 1475-1489. , doi: 10.1093/nar/11.5.1475Schipani, E., Ryan, H.E., Didrickson, S., Kobayashi, T., Knight, M., Johnson, R.S., Hypoxia in cartilage: HIF-1alpha is essential for chondrocyte growth arrest and survival (2001) Genes Dev., 15, pp. 2865-2876Pfander, D., Kobayashi, T., Knight, M.C., Zelzer, E., Chan, D.A., Olsen, B.R., Deletion of Vhlh in chondrocytes reduces cell proliferation and increases matrix deposition during growth plate development (2004) Development., 131, pp. 2497-2508. , doi: 10.1242/dev.01138Hellwig-Burgel, T., Rutkowski, K., Metzen, E., Fandrey, J., Jelkmann, W., Interleukin-1beta and tumor necrosis factor-alpha 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Broadband polarization-entanglement in a poled fiber

Broadband polarization-entanglement over 100 nm is demonstrated in a poled fiber phase-matched for type-II downconversion in the 1.5µm telecom-band. Two-photon interference and Hong-Ou-Mandel interference are used experimentally to confirm the broadband nature of the entanglement

High Power Single-Frequency Fibre Lasers: Design and Applications

We review the latest advances and developments in the area of single-frequency fibre lasers, their design and approaches for achieving power levels in excess of 100W. Future directions and applications of the technology will also be discussed

Single-longitudinal mode laser structure based on a very narrow filtering technique

A narrow filtering technique based on the spectral overlapping of two uniform FBGs and applied to obtain a Single Longitudinal Mode (SLM) laser is proposed and demonstrated in this work. The two FBGs are spectrally detuned to reduce their coincident reflection response narrowing the equivalent filter bandwidth. A proof-of-concept linear laser has been built and tested exhibiting SLM operation even with temperature and strain variations.The authors are grateful to the Spanish government project TEC2010-20224-C02, to the Spanish Ministry of Education and Culture, and to the grant AP2009-1403