p53 gene mutations in non-small cell lung cancer from Thai patients.

Paraffin embedded tissues from twenty-two Thai patients with non-small cell lung cancer were studied for p53 gene mutations in exon 5 to 8 using polymerase chain reaction and single-stranded conformation polymorphism (PCR-SSCP) followed by thermal cycle sequencing. Results showed that point mutations in this region of p53 gene were present in 3 cases. One harboured the base change from GAC to AAC at codon 281, changing amino acid from aspartic acid to asparagine, whilst the other cases were transversion of AAA (lysine) to ACA (threonine) at codon 292. All subjects with p53 mutation had a past history of tobacco smoking.

K-ras oncogene and p53 gene mutations in cholangiocarcinoma from Thai patients.

Paraffin embedded tissues from twenty Thai patients with intrahepatic cholangiocarcinomas were studied for K-ras gene mutations at codon 12, 13 and 61 and for p53 gene mutations in exon 5 to 8 using polymerase chain reaction and thermal cycle sequencing. Results showed that point mutations at these regions in K-ras oncogene were not present in all the samples. One case harbored a p53 gene mutation in codon 282 in exon 8, CGG (arginine) to TGG (tryptophan), but the mutation was not found in other patient's tissues with similar histological features.

Cancer genes and cholangiocarcinoma.

Genes involved in cancer development include oncogenes and tumor suppressor genes. Ras oncogene and mutations in p53 tumor suppressor gene are commonly found in many types of cancer. In Thai patients with cholangiocarcinoma ras oncogenes occur less frequently than in other ethnic groups and furthermore, p53 mutations also occur with lower incidence when compared with Japanese subjects. It is unclear at this time the basis for these differences.

Mitochondrial cytochrome b gene in two developmental stages of human malarial parasite Plasmodium falciparum.

The cytochrome b gene of the mitochondrial ubiquinol-cytochrome c reductase (complex III of electron transport chain) was characterized in two developmental stages of human malarial parasite cultivated in vitro. The cytochrome b gene spanning the nucleotide position 4691 to 5930 in 6-kb mitochondrial DNA from gametocytic (sexual) and intraerythrocytic (asexual) stages of Plasmodium falciparum (a T9,94 mutant line) were in vitro amplified from total DNA using polymerase chain reaction (PCR). It was found that the parasites from both stages contained the PCR product approximately 1.2 kb in length that was localized in mitochondria. The nucleotide sequences of cytochrome b gene at Qi/quinone binding site from both stages were analyzed using thermal cycle sequencing and were found to be the same. The amount of this gene from both stages of the parasite were determined by using the quantitative PCR method. The results showed that the amount of the cytochrome b gene produced from the sexual stage was seven times higher than that obtained from the asexual stage. Our results would provide basic information on the regulation of cytochrome b and the 6-kb mitochondrial DNA during growth and development of the sexual and asexual stages of the malarial parasite in the mammalian host.