Biomedical subjects

Yoshiko Yamaguchi

Publications and source records attributed to Yoshiko Yamaguchi.

10 recordsLinked to original sources

PubMed2005

Specific molecule localization in microchannel laminar flow and its application for non-immobilized-probe analysis.

Microfluidic systems enable superior control of fluidics. We have developed a novel size-separation method utilizing secondary flow within a microchannel. Using confocal fluorescence microscopy and computer simulation, we confirmed that separation occurred as a result of specific molecular localization in the curving part of the microchannel. Maximum separation efficiency was achieved by optimizing microchannel design and flow rate for individual separation targets. In addition, more effective separation was achieved by use of plural microchannel curves. This method was used for sequence-selective DNA sensing. Double-stranded DNA formed by hybridization between target DNA and a complementary probe had different elution profiles from those of the single-stranded non-complementary sequence. Moreover, the response depends on the length of the DNA molecules. This method does not require immobilization of either probe or target DNA, because all reactions occurred in the solution phase. Such features may reduce experimental error and the difference between data from different operators.

Biosensing Techniques↗

PubMed2005

Efficient immobilization of enzymes on microchannel surface through His-tag and application for microreactor.

We developed a simple immobilisation method for His-tagged enzymes on a microchannel surface. It facilitates immobilisation of protein molecule on microchannel surface through Ni-complex, using crude or purified protein solutions. By this method, we could immobilize proteins on microcapillary constantly. This method might be useful for further development of microreactor with reversibly immobilized enzymes.

Animals↗

PubMed2004

Direct observation of long-strand DNA conformational changing in microchannel flow and microfluidic hybridization assay.

Conformational control of macromolecules is useful for efficient chemical and biochemical reactions. This article reports a direct observation method for macromolecules, such as long-strand DNA, in microchannel flow as well as a simple method for stretching DNA strands by microfluidics. Stretching and orientation of DNA molecules by control of flow within a microchannel was observed by optical microscopy. This DNA stretching is explained by coil-stretch transition of polymer molecules. This technique is useful for creating chemical reactions with macromolecules. It offers high selectivity and efficiency that are impossible to achieve in bulk solution. We also demonstrate that our microfluidic stretching method can accomplish efficient hybridization of long-strand DNA. This method will be useful for direct hybridization assay of long-strand DNA.

DNA↗

PubMed2004

Application of a microfluidic reaction system for CdSe nanocrystal preparation: their growth kinetics and photoluminescence analysis.

We used a microreactor for CdSe nanocrystal preparation and explored the effects of experimental conditions on the properties of the products. The particle growth kinetics and photoluminescence properties of the nanocrystals showed identical trends to previous reports, indicating the efficiency of the current method for analysis of rapid nanocrystal synthesis as well as industrial production of CdSe nanocrystals.

Journal Article↗

PubMed2004

Locally advanced and metastatic breast cancer with cartilaginous and/or osseous metaplasia showing excellent response to chemotherapy.

Breast cancer with cartilaginous and/or osseous metaplasia is considered a rare disease, but several cases have been reported recently. We report a case of breast cancer with cartilaginous and/or osseous metaplasia that was StageIV,(T4bN0M1b (PUL)), on the basis of the Japanese General Rules for Clinical and Pathological Recording of Breast Cancer, which responded well to chemotherapy. A 58-year-old women visited our hospital with a chief complaint of a palpable breast mass that had increased in size in March 2002. It was 20 x 15 x 14 cm and occupied the entire right breast. Chest computed tomography (CT) demonstrated multiple lung metastases. Histology of the biopsy specimens revealed a spindle-shaped cell carcinoma. It was ER(-), PgR(-), and HER2/neu Score 0. CAF was given to the patient as preoperative chemotherapy. Five cycles of treatment yielded improvement at the primary site and improvement of the metastatic lung lesions, which was judged as a partial response. Subsequently, one cycle of weekly paclitaxel 80 mg/m2 and oral administration of 5'-DFUR 800 mg/day were given. In November 2002, the patient underwent a right simple mastectomy with whole-layer skin grafting from the abdomen. The final pathological diagnosis was a rare type of breast cancer with cartilaginous and/or osseous metaplasia. Preoperative chemotherapy had caused necrosis in most of the tumor cells, and the efficacy was judged as Grade 2. From the third week postoperatively, weekly paclitaxel (80 mg/m2) was given. Six months after the operation, the multiple lung metastases were completely eliminated and new metastasis to liver or bone or local recurrence have not been observed.

Breast Neoplasms↗

PubMed2003

Continuous synthesis of CdSe-ZnS composite nanoparticles in a microfluidic reactor.

ZnS-coated CdSe composite particles have been continuously synthesized in a microfluidic reactor. By using this system, CdSe particles and a ZnS coating can be produced in sequence, and the particle size and layer thickness can be directly adjusted by the residence time. It demonstrated that the continuous synthesis in the microreactor was a simple and efficient way to prepare composite particles with different structures and determine the optimized experimental conditions.

Journal Article↗

PubMed2003

Sequence-selective DNA detection using multiple laminar streams: a novel microfluidic analysis method.

On-site detection methods for DNA have been demanded in the pathophysiology field. Such analysis requires a simple and accurate method, rather than high-throughput. This report describes a novel microfluidic analysis method and its application for simple sequence-selective DNA detection. The method uses a microchannel device with a serpentine structure. Sequence-specific binding of probe DNA can be detected at one side of the microchannel. This method is capable of sequence-specific detection of DNA with high accuracy. Single base mutations can also be analyzed. Combination of laminar stream and laminar secondary flow in the microchannel enable specific detection of probe-bound DNA.

Base Sequence↗

PubMed2003

A case of breast cancer metastasizing to cervix after resection of pancreatic metastasis.

A case of breast cancer that metastasized to the cervix 10 years and 8 months after mastectomy is reported. The patient had undergone pancreaticoduodenectomy due to solitary metastasis to the head of the pancreas 4 years previously. The cervical metastasis was associated with abnormal genital bleeding. After pancreaticoduodenectomy the serum levels of CEA, CA15-3 and NCC-ST-439, which are markers of breast cancer, were within normal limits, but the serum level of CA15-3 had increased month by month. The patient had abnormal genital bleeding and presented to the department of gynecology at our hospital. The tumor was in the cervix, bled easily and 2.5x2.0 cm in size on ultrasonography. It was thought to be carcinoma of the cervix, but biopsy revealed the tumor to be an adenocarcinoma pathologically and CA15-3 was immunohistochemically demonstrated in the resected specimen, similar to lobular carcinoma of the breast. Abdominal CT scan revealed involvement of the ovaries and uterus, prompting hysterectomy with bilateral oophorectomy. After discharge, she received chemoendocrine therapy. However, she subsequently died due to peritoneal carcinomatosis.

Adenocarcinoma↗

PubMed2002

Preparation of CdSe nanocrystals in a micro-flow-reactor.

A micro-reactor was utilized for continuous and controlled CdSe nanocrystal preparation. Effects of reaction conditions on optical properties of the nanocrystals were investigated; in this current system, rapid and exact temperature control of the micro-reactor was beneficial for controlling particle diameter and reproducible preparation of particles; additional effort was made towards narrower particle-size distributions.

Journal Article↗

PubMed2002

Periodontal status of rural inhabitants in Prek Russey, Cambodia.

There is a paucity of information pertaining to oral disease patterns including periodontal disease in Cambodia, which is just emerging from a 20-year ruin. A house-to-house survey was conducted to assess the periodontal status of 1948 subjects aged 15-74 years in a rural commune in Cambodia using Community Periodontal Index (CPI) and measuring Attachment Loss (LA). The periodontal status of Cambodians increased with age as indicated by both CPI and LA. Calculus was the most common finding among Cambodians pointing to overall poor oral hygiene levels. Notwithstanding the poor oral hygiene, however, the severe periodontitis as denoted by > or = 6mm periodontal pockets was rare even in the elderly while edentulousness was not frequently observed until 65 years. Preventive programmes targeting periodontal disease in Cambodia should focus on oral health education and simple oral hygiene instructions while the ubiquitous calculus could be dealt with oral prophylaxis.

Adolescent↗