Biomedical subjects

Hiroyuki Yonekawa

Publications and source records attributed to Hiroyuki Yonekawa.

4 recordsLinked to original sources

PubMed2004

Three-dimensional microarray compared with PCR-single-strand conformation polymorphism analysis/DNA sequencing for mutation analysis of K-ras codons 12 and 13.

BACKGROUND: We developed a rapid, precise, and accurate microarray-based method that uses a three-dimensional platform for detection of mutations. METHODS: We used the PamChip microarray to detect mutations in codons 12 and 13 of K-ras in 15 cell lines and 81 gastric or colorectal cancer tissues. Fluorescein isothiocyanate-labeled PCR products were analyzed with the microarray. We confirmed the microarray results with PCR-single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. RESULTS: We could correctly identify wild-type, heterozygous, and homozygous mutant genotypes with the PamChip microarray in <3.5 h. The array data were consistent with those of PCR-SSCP analysis and DNA sequencing. All 15 cell lines and 80 of 81 clinical cancer specimens (98.8%; 95% confidence interval, 96.4-100%) were genotyped accurately with the microarray, a rate better than that of direct DNA sequencing (38.9%) or SSCP (93.8%). Only one clinical specimen was misdiagnosed as homozygous for the wild-type allele. Densitometric analysis of SSCP bands indicated that the content of the mutant allele in the specimen was approximately 16%. The PamChip microarray could detect mutant alleles representing more than 25% of the SSCP band proportions. Therefore, the limit for detection of mutant alleles by the PamChip microarray was estimated to be 16-25% of the total DNA. CONCLUSIONS: The PamChip microarray is a novel three-dimensional microarray system and can be used to analyze K-ras mutations quickly and accurately. The mutation detection rate was nearly 100% and was similar to that of PCR-SSCP together with sequencing analysis, but the microarray analysis was faster and easier.

Cell Line, Tumor↗

PubMed2003

[Prophylactic neck dissection for submandibular gland cancer].

The indication and preferred dissection field for prophylactic neck dissection for submandibular gland cancer are controversial and have not been standardized. We reviewed 27 patients who underwent a definitive operation for previously untreated submandibular gland cancer. The 27 patients consisted of 13 patients with adenoid cystic carcinoma, 6 patients with mucoepidermoid carcinoma, 6 patients with adenocarcinoma, and 2 patients with squamous cell carcinoma. The diagnostic accuracies of malignancy and histology with fine needle aspiration cytology were 86% and 56%, respectively. In sixteen out of 21 cases without neck lymph node metastasis, a prophylactic neck dissection was performed and pathological neck lymph node metastases were detected in five cases. On the other hand, in five cases that did not receive a prophylactic neck dissection, latent neck lymph node metastasis was observed in 2 cases. In both cases of neck lymph node metastasis, pathological positive lymph nodes were observed in only level 2 or level 3. The rates of occult neck lymph node metastasis according to the T stage were 0% in T1, 33.3% in T2, 57.1% in T3 and 100% in T4. The rates of occult neck lymph node metastasis according to the histopathology were 46.2% in adenoid cystic carcinoma, 50% in mucoepidermoid carcinoma, 50% in adenocarcinoma, and 50% in squamous cell carcinoma. In conclusion, we believe that supraomyohoid neck dissection is suitable for N0 cases of submandibular gland cancer because of four reasons: 1) rate of occult neck lymph node metastasis in submandibular gland cancer is high, 2) pathological neck lymph node metastasis in N0 cases and latent neck lymph node metastasis were observed in level 2 and level 3, 3) the prognosis of cases with neck lymph node metastasis was poor, and 4) same skin incision can be used not only for the primary resection but also for the neck dissection.

Adult↗

PubMed2003

[Basic studies on mutation analysis of K-ras codon 12 by use of three-dimensional microarray system].

A next-generation DNA microarray system, FD10 has been developed. It is based around the PamChip, a custom-made microarray, which consists of a solid three-dimensional structure that facilitated the incorporation of probe molecules. We applied this microarray system on a detection of K-ras mutation at codon 12 in some cancer cell lines. The PCR products amplified by use of FITC labeled primers were applied onto probe-absorbed microarray. After hybridization, the signal was imaged by CCD camera and analyzed by the exclusive software. We confirmed the microarray results by PCR-SSCP and sequencing analyses. Ten, two and three out of 15 cell lines were homozygous for wild type allele, heterozygous for wild and mutant allele, and homozygous for mutant alleles, respectively. Signals hybridized with antisense probes were stronger than those with sense probes, without PSN1 cell line. The system had a good reproducibility. Essentially, the microarray results were consistent with PCR-SSCP and sequencing results. In conclusion, the FD10 microarray system was easy to operate and short to get results. It might be useful for a focused array applicable for specific purposes. The K-ras mutation detection system worked well and will be applied to clinical specimens soon.

Codon↗

PubMed2002

[Squamous carcinoma of the posterior oropharyngeal wall].

We treated 9 patients with squamous cell carcinoma of the posterior oropharyngeal wall at the Cancer Institute Hospital, Tokyo. All were men averaging 64.1 years of age. One patient each was stage I, stage II or stage III, and 6 were stage IV. Cervical lymph node metastasis was seen in 6 at initial diagnosis. Retropharyngeal lymph nodes were involved in 4, while 5 had second primary cancer such as esophageal, gastric, head and neck cancer. Radical radiotherapy was done for 3 and surgery as initial treatment in 6. Five-year local control was 50% and 5-year disease-free survival was 22%. Total laryngectomy was done for 4 patients. Six died of oropharyngeal cancer and 1 of second primary cancer. Cancer of posterior pharyngeal wall is relatively rare and the prognosis is considered poorer than other types of oropharyngeal cancer for necessitating study to determine which modality may improve treatment results.

Aged↗