Cocycle Properties of String Theories on Orbifolds

We study cocycle properties of vertex operators and present an operator representation of cocycle operators, which are attached to vertex operators to ensure the duality of amplitudes. It is shown that this analysis makes it possible to obtain the general class of consistent string theories on orbifolds.Comment: 40 pages (Talk given at Workshop on ``Recent Developments in String and Field theory", Kyoto, Japan on September 9-12, 1991.

The Diagnosis and Treatment of Early-Stage Colorectal Cancer

The introduction of colorectal endoscopic submucosal dissection (ESD) has expanded the applications for endoscopic treatment; as a result, lesions with low metastatic potential can be treated endoscopically regardless of the lesion size. The most attractive feature of ESD is the achievement of en bloc resection with a lower local recurrence rate in comparison to that of endoscopic piecemeal mucosal resection. However, in case of gastric cancers, ESD is not as widely applied to the treatment of colorectal neoplasms because of its technical difficulty, longer procedural time, and increased perforation risk. In the movement toward diversified endoscopic treatment strategies for superficial colorectal neoplasms, endoscopists who begin to perform ESD need to recognize the indications of ESD, as well as the technical issues and associated complications of this procedure

Dome-type carcinoma of the colon; a rare variant of adenocarcinoma resembling a submucosal tumor: a case report

<p>Abstract</p> <p>Background</p> <p>Dome-type carcinoma (DC) is a distinct variant of colorectal adenocarcinoma and less than 10 cases have been described in the literature. Most of the previously reported cases were early lesions and no endoscopic observations have been described so far. We herein report a case of a DC invading the subserosal layer, including endoscopic findings.</p> <p>Case presentation</p> <p>A highly elevated lesion in the transverse colon was diagnosed by colonoscopy in a 77-year-old man. The tumor appeared to be similar to a submucosal tumor (SMT), however, a demarcated area of reddish and irregular mucosa was observed at the top of the tumor. There were no erosions or ulcers. Laparoscopic-assisted right hemicolectomy was performed and pathological examination revealed a well-circumscribed tumor invading the subserosal layer. The tumor was a well-differentiated adenocarcinoma associated with a dense lymphocytic infiltration and showed expansive growth. The overlying mucosal layer showed high-grade dysplasia.</p> <p>Conclusion</p> <p>The present lesion was diagnosed as a DC of the colon invading the subserosal layer. Because the association of mucosal dysplasia is common in DCs, the detection of dysplastic epithelium would be important to discriminate DCs from SMTs.</p

Growth rates, relative growth and a potential aging method using vertebral centra in Silurus biwaensis(Siluriformes: Siluridae)

Relative growth and relationship between age and growth in Silurus biwaensis were examined on the basis of the body size data of the catfish collected from Lake Biwa and the reared catfish which were hatched from artificially inseminated eggs. Although it had been reported that the proportion of head length to body length increased with growth in S. biwaensis, such a relationship was not found for 218 catfish that were examined in this study. On the other hand, the proportion of head length to head width significantly decreased with SL in females. This result indicated that the narrow head shape peculiar to S. biwaensis becomes slightly squarer in bigger females. The three catfish reared from the hatching grew to 196-410mm SL for 2.7 years (73-152mm/yr). This growth rate was in contrast with that of a tagged adult male, which grew only 50mm from 460mm SL to 510mm SL in the lake for two years (25mm/yr). These results suggested that the growth of the adults might extremely slow down after the fast growth at the immature stage. This study also reported that the number of transparent zones in vertebral centra of S. biwaensis increased with growth. The vertebral centrum may possibly be utilized as an age indicator for this species and the other kinds of Silurid

桜島地域の地表大気中の鉛-210およびポロニウム-210

金沢大学低レベル放射能実験施設金沢大学自然計測応用研究センター自然計測研究部

In vivo regeneration of rat laryngeal cartilage with mesenchymal stem cells derived from human induced pluripotent stem cells via neural crest cells

The laryngotracheal cartilage is a cardinal framework for the maintenance of the airway for breathing, which occasionally requires reconstruction. Because hyaline cartilage has a poor intrinsic regenerative ability, various regenerative approaches have been attempted to regenerate laryngotracheal cartilage. The use of autologous mesenchymal stem cells (MSCs) for cartilage regeneration has been widely investigated. However, long-term culture may limit proliferative capacity. Human-induced pluripotent stem cell-derived MSCs (iMSCs) can circumvent this problem due to their unlimited proliferative capacity. This study aimed to investigate the efficacy of iMSCs in the regeneration of thyroid cartilage in immunodeficient rats. Herein, we induced iMSCs through neural crest cell intermediates. For the relevance to prospective future clinical application, induction was conducted under xeno-free/serum-free conditions. Then, clumps fabricated from an iMSC/extracellular matrix complex (C-iMSC) were transplanted into thyroid cartilage defects in immunodeficient rats. Histological examinations revealed cartilage-like regenerated tissue and human nuclear antigen (HNA)-positive surviving transplanted cells in the regenerated lesion. HNA-positive cells co-expressed SOX9, and type II collagen was identified around HNA-positive cells. These results indicated that the transplanted C-iMSCs promoted thyroid cartilage regeneration and some of the iMSCs differentiated into chondrogenic lineage cells. Induced MSCs may be a promising candidate cell therapy for human laryngotracheal reconstruction

Laryngeal Cartilage Regeneration of Nude Rats by Transplantation of Mesenchymal Stem Cells Derived from Human-Induced Pluripotent Stem Cells

Previous studies transplanted human-induced pluripotent stem cells (hiPSCs)-derived mesenchymal stem cells (iMSCs) into thyroid cartilage defect of X-liked severe combined immunodeficiency (X-SCID) rats and confirmed transplanted cell survival and cartilage regeneration. Thus, this study aimed to investigate the contribution of iMSC transplantation to thyroid cartilage regeneration of nude rats. iMSCs were induced from hiPSCs via a neural crest cell lineage. Then, clumps formed from an iMSC/extracellular matrix complex were transplanted into thyroid cartilage defects in nude rats. The larynx was removed and histological and immunohistochemical analyses were performed 4 or 8 weeks after the transplantation. Human nuclear antigen (HNA)-positive cells were observed in 11 of 12 (91.7%) rats, which indicated that transplanted iMSCs survived in thyroid cartilage defects in nude rats. HNA-positive cells co-expressed SOX9, and type II collagen was identified around HNA-positive cells in 8 of 12 rats (66.7%), which indicated cartilage-like regeneration. Cartilage-like regeneration in nude rats in this study was comparable to the previous report on X-SCID rats (HNA-positive cells were observed in all 14 rats and cartilage-like regeneration was observed in 10 of 14 rats). This result suggests that nude rats could be an alternative to X-SCID rats in thyroid cartilage regeneration experiments using iMSCs, and this nude rat cartilage transplantation model may develop cartilage regeneration research concerning fewer problems such as infection due to immunosuppression