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N Tatsumoto

Publications and source records attributed to N Tatsumoto.

8 recordsLinked to original sources
PubMed2000

A simple preparation of half N-acetylated chitosan highly soluble in water and aqueous organic solvents.

A simple and improved method of preparing highly soluble chitosan (half N-acetylated chitosan) was developed using a series of chitosan samples of low molecular weights, and the solubility of the half N-acetylated chitosan in water and organic solvents was investigated in detail. To reduce the molecular weight, chitosan was treated with NaBO3 under the condition that chitosan was homogeneously dissolved in aqueous acetic acid. Weight-average molecular weights of the obtained chitosan samples were determined using a size-exclusion chromatography system equipped with a low-angle laser light-scattering photometer. Each chitosan sample was then N-acetylated with acetic anhydride under the condition that chitosan was homogeneously dissolved in aqueous acetic acid again. The water solubility of the half N-acetylated chitosan thus prepared increased with decreasing molecular weight. From 1H NMR spectroscopy, it was suggested that the sequence of N-acetylglucosamine and glucosamine residues was random. The solubility of the half N-acetylated chitosan of low molecular weight was rather high even in aqueous dimethylacetamide and dimethylsulfoxide.

Acetylation↗
PubMed2000

High telomerase activity is an independent prognostic indicator of poor outcome in colorectal cancer.

Telomerase activity and altered telomere length have been extensively studied in many kinds of malignant tumors for clinical diagnostic and/or prognostic utilities. In the present study, we investigated telomerase activity and telomere length in colorectal cancers and noncancerous colonic mucosa specimens in 100 patients between 1991 and 1996. To determine whether the level of telomerase activity or telomere length is a prognostic indicator of patient outcome, we followed these patients more than 3 years after surgery. Among 100 primary colorectal cancer specimens, 96 specimens had telomerase activity. Because noncancerous mucosa has some detectable telomerase activity, we divided the levels of telomerase activity into three categories: high (>50-fold more than that in noncancerous mucosa); moderate (10- to 50-fold); and low (<10-fold) levels. Among 100 cancer tissues, 28 showed moderate telomerase activity and 44 showed high telomerase activity. The frequency of tumors with moderate or high telomerase activity showed no significant relationship with any clinicopathological factors. The prognosis of the patients with high telomerase activity was significantly worse than that for patients with moderate and low telomerase activity (P < 0.01). Among the 87 patients with curative surgery, disease-free survival rate of those with high telomerase activity was also significantly poorer (P < 0.01). These results indicate that a high level of telomerase activity may be an independent prognosis-predicting factor in the patients with colorectal cancer.

Adult↗
PubMed1999

The effectiveness of perineal rectosigmoidectomy for the treatment of rectal prolapse in elderly and high-risk patients.

We report herein on the follow-up of ten consecutive patients who underwent perineal rectosigmoidectomy, and discuss the indications, surgical technique, and outcomes of this procedure. The median age of the patients was 79 years, with a range of 26 to 85 years, and eight patients had complicating medical conditions. Of five patients who underwent this procedure for a recurrent prolapse after another type of perineal procedure, four had previously undergone the Thiersch operation combined with the Gant-Miwa technique. The mean length of the excised rectum and sigmoid colon was 22.1 cm. Pain was minimal or absent in all patients and oral intake was commenced after 2 days. There were no mortalities, but anastomotic leakage occurred in one patient. The mean follow-up period was 3.5 years. Only one patient developed recurrent rectal prolapse 24 months after the operation. Of seven patients who underwent concomitant levatoroplasty for incontinence, five became fully continent within 3 weeks after the operation, while the remaining two improved after 2 months. We propose that perineal rectosigmoidectomy is indicated for patients who have suffered an early recurrence of prolapse after another transperineal repair; elderly or high-risk patients with incontinence; male patients; and patients with an incarcerated or gangrenous prolapsed rectal segment.

Adult↗
PubMed1997

Postoperative enteritis caused by methicillin-resistant Staphylococcus aureus.

We examined the clinical features of 14 men (mean age 72 years) with postoperative enteritis caused by methicillin-resistant Staphylococcus aureus (MRSA). The patients had all undergone surgery for the treatment of digestive diseases and had received antibiotic prophylaxis consisting of an extended-spectrum cephem. Diarrhea appeared a mean of 3.3 days postoperatively and lasted for 5 days on average. In severe cases organ insufficiency was involved. Coagulate-positive staphylococci were the predominant organisms isolated from watery diarrhea. In 13 of 14 patients, coagulase type II isolates producing enterotoxins A, C and toxic shock syndrome toxin-1 (TSST-1) with enterotoxin A, C, and 1st genes were isolated. These strains were sensitive to vancomycin and arbekacin; however, they were highly resistant to many other antibiotics. We also investigated the effects of a glucocorticoid hormone and gamma globulin on production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-2 (IL-2) obtained from healthy volunteers. TNF-alpha and IL-2 production was enhanced by TSST-1 and the supernatant of Iscove-modified dulbecco medium, in which coagulase type II isolates producing enterotoxins A, C and TSST-1 with enterotoxin A, C were cultured for 24 h. Both glucocorticoid hormone and gamma globulin suppressed TNF-alpha and IL-2 production, thus suggesting that these drugs may be effective in treating postoperative MRSA enteritis.

Aged↗
PubMed1997

The effect of ultrasonic waves on the oxidation current of chlorpromazine in the 38 and 96 kHz-ultrasonic vibrating electrode voltammetry.

In the case of 38 and 96 kHz ultrasonic vibrating electrode (USVE) voltammetry of chlorpromazine, the oxidation current increased considerably with ultrasonic power (amplitude). Movement of the first oxidation product, crimson coloured cation radical, and the streaming of liquid in the neighbourhood of the USVE, were visually observed in order to understand the mechanism of the promotive effects of ultrasound on the oxidation reaction. The reaction profile of the oxidation of chlorpromazine in 38 kHz seems to be somewhat different from that in 96 kHz. However, the mechanical agitation of solution in the area nearest the electrode surface, which is essentially the same fundamental mechanism, takes place in both the cases of 38 and 96 kHz. Both micro- and macro-streamings due to the vibration of a small bubble on the electrode surface with a frequency lower than that of the ultrasonic wave were formed in 38 kHz. These streamings seemed to contribute to the agitation and the exchange of the solution near the electrode surface. However, at the same ultrasonic amplitude, the oxidation current at 96 kHz was much greater than that at 38 kHz. Such a promoting effect of ultrasound on the electrode reaction was considered to be due to the increase of the moving speed or to the acceleration of the particle in the solution.

Antipsychotic Agents↗
PubMed1995

Telomerase activity in gastric cancer.

Although many genetic alterations have been reported in gastric cancer, it is not known whether all gastric tumors are capable of indefinite proliferative potential, e.g., immortality. The expression of telomerase and stabilization of telomeres are concomitant with the attainment of immortality in tumor cells; thus, the measurement of telomerase activity in clinically obtained tumor samples may provide important information useful both as a diagnostic marker to detect immortal cancer cells in clinical materials and as a prognostic indicator of patient outcome. Telomerase activity was analyzed in 66 primary gastric cancers with the use of a PCR-based assay. The majority of tumors (85%) displayed telomerase activity, but telomerase was undetectable in 10 tumors (15%), 8 of which were early stage tumors. Most of the tumors with telomerase activity were large and of advanced stages, including metastases. Survival rate of patients of tumors with detectable telomerase activity was significantly shorter than that of those without telomerase activity. Alterations of telomere length (reduced/elongated terminal restriction fragments) were detected in 14 of 66 (21%) gastric cancers, and all 14 had telomerase activity. Cellular DNA contents revealed that all 22 aneuploid tumors had detectable telomerase activity. The present results indicate that telomerase activation may be required as a critical step in the multigenetic process of tumorigenesis, and that telomerase is frequently but not always activated as a late event in gastric cancer progression.

Base Sequence↗
PubMedDate not supplied

Microencapsulation of pancreatic islets. A technique and its application to culture and transplantation.

Hamster pancreatic islets were encapsulated by a biocompatible membrane composed of the molecular sequence of alginate-polylysine-alginate. The encapsulated islets released insulin into the culture medium in response to secretagogues in short-term incubation. In long-term culture, the encapsulated islets maintained their insulin-releasing capacity for 28 days at a level similar to that of the unencapsulated islets. No overgrowth of fibroblastic cells was observed inside the capsule even after 70 days of culture. Further, the encapsulated hamster islets were xenotransplanted to streptozotocin-induced diabetic rats intraperitoneally. Some of the encapsulated islets, which were recovered from a recipient 27 days after transplantation, were found to be viable, although prolonged normalization of fasting plasma glucose levels of the recipients could not been achieved. On the contrary, the unencapsulated islets were replaced by massive connective tissue elements and insulin-positive B cells were hardly detected within the grafts 22 days after transplantation. The results of this study seem to confirm the potential of the application of the encapsulating technique to primary culture of parenchymal cells and to transplantation of pancreatic islets.

Alginates↗