Expression of a novel carbonic anhydrase, CA XIII, in normal and neoplastic colorectal mucosa
BMC CANCER
Authors: Kummola, L; Hamalainen, JM; Kivela, J; Kivela, AJ; Saarnio, J; Karttunen, T; Parkkila, S
Abstract
Background: Carbonic anhydrase ( CA) isozymes may have an important role in cancer development. Some isozymes control pH homeostasis in tumors that appears to modulate the behaviour of cancer cells. CA XIII is the newest member of the CA gene family. It is a cytosolic isozyme which is expressed in a number of normal tissues. The present study was designed to investigate CA XIII expression in prospectively collected colorectal tumor samples. Methods: Both neoplastic and normal tissue specimens were obtained from the same patients. The analyses were performed using CA XIII-specific antibodies and an immunohistochemical staining method. For comparison, the tissue sections were immunostained for other cytosolic isozymes, CA I and II. Results: The results indicated that the expression of CA XIII is down-regulated in tumor cells compared to the normal tissue. The lowest signal was detected in carcinoma samples. This pattern of expression was quite parallel for CA I and II. Conclusion: The down-regulation of cytosolic CA I, II and XIII in colorectal cancer may result from reduced levels of a common transcription factor or loss of closely linked CA1, CA2 and CA13 alleles on chromosome 8. Their possible role as tumor suppressors should be further evaluated.
Enhanced Optical Properties of Bredigite-Structure Ca13.7Eu0.3Mg2[SiO4](8) Phosphor: Effective Eu Reduction by La Co-Doping
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
Authors: Kim, Seung Jun; Jang, Ho Seong; Unithrattil, Sanjith; Kim, Yoon Hwa; Im, Won Bin
Abstract
A green phosphor, La0.4Ca13.3Eu0.3Mg2Si8O31.6+N0.4- (LaCMSN:Eu2+), was prepared by a solid-state reaction and an efficient green emission was observed at 506 nm under near-ultraviolet (NUV) excitation. The structural and optical properties of LaCMSN:Eu2+ phosphors as well as their thermal quenching were investigated. The partial substitution of La3+ and N3- in Ca13.7Eu0.3Mg2Si8O32 led to a considerable enhancement in the peak emission intensity by as much as 194%. This demonstrates not only that the total number of Eu2+ activators increased, but also that the probability of a nonradiative transition between Eu2+ and Eu3+ could be reduced as the increase in concentration of the former is at the expense of the later. The white light-emitting diode (LED) was fabricated using phosphor with a NUV LED chip. The LED showed warm white light with an excellent color rendering index of 91. The LaCMSN:Eu2+ is thus a potential green-emitting phosphor for white LEDs.