Biomedical subjects

X Fan

Publications and source records attributed to X Fan.

237 records · Page 14Linked to original sources

PubMedDate not supplied

Lack of gene amplification as a mechanism of CDK4 activation in human neuroblastoma.

Neuroblastoma is the most frequent solid tumor in childhood. We have analysed 48 neuroblastomas of different stages and degrees of cellular differentiation for CDK4 amplification by a fluorescent differential PCR assay. We explored the relative densitometric measure of a 119 bp fragment of the CDK4 gene versus an 82 bp fragment of the IFNG gene. We were not able to detect any case of CDK4 gene amplification in the neuroblastomas. In conclusion, CDK4 activation does not seem to be relevant to the development of neuroblastomas, at least through gene amplification.

Child↗

PubMedDate not supplied

Improvement of the methylation specific PCR technical conditions for the detection of p16 promoter hypermethylation in small amounts of tumor DNA.

Methylation specific PCR (MSP) is a technique that enables the detection of hypermethylation at a CpG island. The objective of this study is the introduction of small modifications to the MSP technique to make it more suitable for the study of promoter hypermethylation at tumor suppressor genes whenever there is a shortage of material available for study. This commonly happens in the case of using archival material from the Pathology departments. Tumor DNA was extracted from a collection of 40 fresh-frozen soft tissue sarcomas and 19 paraffin-embedded PNETs (primitive neuroectodermal tumors). The MSP technique was performed to detect hypermethylation at the p16 promoter. Also, blood genomic DNA was mixed with herry sperm genomic DNA as a carrier, in nine different combinations, in order to test for the best conditions that could produce MSP bands even when low amounts of genomic tumor DNA is available for study. We demonstrate the benefit of using herry sperm carrier DNA up to 10 microg together with small quantities of tumor DNA. This result will facilitate the incorporation of paraffin-embedded samples for study of promoter hypermethylation at tumor suppressor genes. Other technical conditions for the MSP technique are also studied.

Brain Neoplasms↗

PubMedDate not supplied

Identification of a renal proximal tubular epithelial antigen coexpressed on leukocytes.

Renal tubular epithelial cells (TEC) and leukocytes express distinct cell adhesion molecules and integrins in common. To identify additional proximal TEC molecules that are coexpressed on leukocytes, we have generated a panel of monoclonal antibodies (mAb) by immunization of rats with a mouse T cell line. One of these mAb (I-72) recognizes a 210-kD antigen on cultured TEC. The staining pattern in several cell lines allowed exclusion of known TEC surface molecules as being the antigens recognized by the I-72 mAb. Immunofluorescence staining of mouse kidney with the I-72 mAb demonstrated prominent expression on the apical but not the basolateral side of proximal tubules, predominantly in the S1 segment. I-72 was also expressed in the loop of Henle, the collecting duct, and on endothelial cells of intrarenal vessels. We have thus generated a mAb which identifies an unusual renal proximal tubular brush border molecule that is coexpressed on T cells. Molecular structure and the function of I-72 need to be defined in further studies.

Animals↗