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Biomedical subjects

Y Shigemasa

Publications and source records attributed to Y Shigemasa.

At least 19 recordsLinked to original sources
PubMed2002

[Strategy for preventing recurrence after video-assisted thoracoscopic surgery for spontaneous pneumothorax; efficacy of talc pleurodesis and absorbable mesh covering].

Video-assisted thoracoscopic surgery (VATS) has been widely used in the treatment of spontaneous pneumothorax. The unexpectedly high increase of the recurrence rate is the most important problem. We examined the interaction between recurrence, clinical features and patient's backgrounds. The main causes of recurrence were oversight of bullae and the emphysematous changes at the periphery of the site where an autosuture device was used. 90% of the recurrence occurred in the patients with type III small diffuse bullae. Introduction of the regional talc pleurodesis and covering stapled line with absorbable mesh were extremely useful to lower the recurrence rate after VATS for spontaneous pneumothorax.

Absorbable Implants↗
PubMed2001

Biological activities of carbohydrate-branched chitosan derivatives.

Two types of biological activities of the carbohydrate-branched chitosan derivatives were investigated. One is the specific interaction with lectins and bacterium. The other is activation of canine polymorphonuclear leukocyte (PMN) cells. The specific bindings of the L-fucose-branched chitosan derivative with Ulex europaeus agglutinin I (UEA-I) and the N-acetyl-D-glucosamine-branched chitosan derivative with Concanavalin A (Con A) were confirmed by a surface plasmon resonance technique. The specific aggregation of the fluorescence-labeled L-fucose-branched chitosan derivative with Pseudomonas aeruginosa was observed by fluorescent microscopic observation. The aggregation would be attributed to the specific binding between the L-fucose-branched chitosan derivative and PA-II receptor on the cell surface of P. aeruginosa. The influence of the chitosan derivatives on the active oxygen species generation from canine PMN cells was also investigated by the luminol-aided chemiluminescence method. The chemiluminescence responses depended on the degree of substitution and water solubility of the chitosan derivatives. The water-insoluble chitosan derivatives would stimulate the PMN cells by a phagocytosis mechanism, and the water-soluble ones would sensitize the PMN cells by a priming mechanism.

Animals↗
PubMed1999

Veterinary practice with chitin and chitosan.

Dramatic effects of chitin and chitosan on wound healing were demonstrated in field cases of many small animals (dogs and cats), food animals (338 cows) and 142 zoo animals. In comparison with conventional therapy with irrigation and antibiotic administration to wound, new treatment with chitin and chitosan permitted a substantial decrease in treatment frequency with minimum scar formation.

Animals↗
PubMed1998

Chitin and chitosan stimulate canine polymorphonuclear cells to release leukotriene B4 and prostaglandin E2.

The effects of chitin and chitosan on the release of arachidonic acid products were investigated in this study. Supernatants of canine polymorphonuclear cell (PMN) suspensions incubated with chitin and chitosan contained a leukotriene B4 (LTB4) concentration high enough to induce canine PMN migration in vitro. The supernatants also contained the same concentration of prostaglandin E2 (PGE2) as that normally found in the peripheral blood of dogs. Intraperitoneal administration of chitosan to dogs induced peritoneal exudative fluid (PEF), but chitin did not. The PEF contained numerous PMNs and macrophages. The supernatant of PEF contained both heat-stable and heat-labile chemotactic factors for canine PMNs. It also contained enough LTB4 to attract the canine PMNs in vitro.

Animals↗
PubMed1996

Evaluation of different absorbance ratios from infrared spectroscopy for analyzing the degree of deacetylation in chitin.

Various acetylated chitosan derivatives and mixtures of chitin and chitosan, covering the range of the degree of deacetylation (DDA) from 0-100% were analyzed by 1H-NMR spectroscopy and infrared spectroscopy. The use of the 1070 cm-1 or 1030 cm-1 absorption band as an internal standard in the determination of DDA from the absorbance of the amide I bands at 1655 cm-1 and 1630 cm-1 or the amide II band at 1560 cm-1 was studied. There is a good correlation between the results from IR spectroscopy and those from 1H-NMR spectroscopy.

Acetylation↗
PubMed1995

Partially deacetylated chitin and hyaluronan induce glycogenolysis in perfused rat liver.

Mannan interacts with mannose/N-acetylglucosamine (GlcNAc) receptors on the surface of both Kupffer cells and endothelial cells in the liver, and induces glycogenolysis through production of peptide-leukotriene (LT) in the perfused rat liver. In the present study, we examined whether positively and negatively charged GlcNAc-containing polysaccharides stimulate glycogenolysis in perfused rat liver. Infusion of the former, 67% deacetylated chitin (DAC), induced biphasic increases in glucose production and a steep decrease in oxygen consumption by the liver. ONO-1078, an LT D4 receptor antagonist, abolished the suppression of oxygen consumption and reduced the glucose production by DAC. Infusion of the latter, hyaluronan, stimulated glucose production with a concomitant increase in oxygen consumption. Ibuprofen, a cyclooxygenase inhibitor, reduced the glucose production by hyaluronan. Sequential infusions of mannan and DAC, but not hyaluronan, did not induce glycogenolytic responses when mannan was infused 20 min before the second stimulation. These results suggest that DAC, but not hyaluronan, stimulates mannose/GlcNAc receptors in the perfused rat liver, and that potent immunological activity induced by DAC may be mediated by activation of the receptors.

Acylation↗
PubMed1995

Polymeric N-acetyl-D-glucosamine (chitin) induces prostaglandin E2 in dogs.

The level of prostaglandin E2 (PGE2) in the exudate induced by subcutaneous implantation of a complex formed from non-woven fabric of polyester (NWF) and polymeric N-acetyl-D-glucosamine (chitin) (chitin/NWF) or by implantation of NWF in dogs was measured by radioimmunoassay. The amount of PGE2 in the exudate induced by chitin/NWF was about five times as high as that in the exudate induced by NWF (p < 0.05), while the level of PGE2 in the exudate was similar to that in serum.

Animals↗
PubMed1995

Effects of chitosan on experimental abscess with Staphylococcus aureus in dogs.

An abscess was developed experimentally by a subcutaneous inoculation of Stapylococcus (S.) aureus T-6 with a 4-cm silk suture in dogs. After draining the pus, the abscess was treated with a suspension of finely granulated chitosan (chitosan group), ampicillin (ampicillin group), or saline (control group) (Day 0). The chitosan group was further divided into 3 subgroups (0.01, 0.1, and 1.0 mg/subgroups). Similar treatment was repeated after 4 days (Day 4), followed by euthanasia on Day 8. The wound cavity contraction rate was calculated by measuring the wound cavity diameter by a sound on Days 0, 4 and 8. The wound cavity contraction rate was significantly higher in the ampicillin, 0.1 mg chitosan, and 1.0 mg chitosan groups than in the 0.01 mg chitosan and control groups on Days 4 and 8 (p < 0.05). In the 0.1 and 1.0 mg chitosan groups, the abscess healed completely in 6 out of 11 (55%), and 9 out of 10 cases (90%), respectively, by Day 8. In the ampicillin group, 4 out of 10 cases (40%) healed completely by Day 8. No healing occurred in the 0.01 mg chitosan and control groups. Histologically, the granulation tissue formed had abundant vascularization in the 0.1 and 1.0 mg chitosan groups on Day 8.

Abscess↗
PubMed1995

Evaluation of chitin and chitosan on open would healing in dogs.

Analysis on the accelerating effects of open wound healing by chitin and chitosan were carried out in dogs. Two, square, full-thickness wounds of skin (2 x 2 cm2) were created on the each dog's both sides of dorsal midline at 0, 14, 21, and 24 days. In one dog, one wound (left side) was treated with chitin (chitin group) and the other wound (right side) was not treated (control group). In another dog, one wound (left side) was treated with chitosan (chitosan group) and the other wound (right side) was not treated (control group). At 28 days after initial wounding, each wound site including surrounding tissue was taken for macroscopic and histological observations. Reepithelialization tended to be greater in chitin and chitosan groups than in the control group. However, when the scores of reepithelialization and granulation tissue were evaluated statistically, there was no significant differences in three groups during experimental period. Number of inflammatory cells was greater statistically in level in the control group than those in chitin and chitosan groups at 28 days after wounding. Many rete ridges were observed in the control group but very few in the another groups.

Animals↗
PubMed1994

Enzymatic degradation of chitins and partially deacetylated chitins.

The enzymatic (lysozyme, chitinase etc.) digestibility of chitins obtained from squid pen and shrimp shell, and of partially deacetylated chitins (DA-chitins) was investigated. The digestibility of various chitins by the chitinase from Bacillus sp. PI-7S was much higher than that by lysozyme, and beta-chitin was digested more smoothly than alpha-chitin. DA-chitin deacetylated under homogeneous conditions (DAC) was hydrolysed by lysozyme more rapidly than that deacetylated under heterogeneous conditions (DAC). DACs from shrimp shell and squid pen showed the same degree of digestibility by lysozyme in spite of a difference in the crystal structure of the original chitins. The crystal structure of chitin and the degree of N-acetyl group aggregation among DA-chitin molecules affect the enzymatic digestibility of chitin and DA-chitin, respectively.

Acetylation↗
PubMed1994

Migration of canine neutrophils to chitin and chitosan.

Suspension of chitin and chitosan particles (mean size of 1 micron) were found to attract canine neutrophils chemotactically as determined by a checkerboard assay through polycarbonate filter with 5 microns pore size in Blind well chamber. Suspension of chitin induced chemokinetic migrations of the neutrophils. These evidences might reflect accumulation of neutrophils to chitin- and chitosan-implanted regions in dogs.

Animals↗
PubMed1993

Polymeric N-acetyl-D-glucosamine (chitin) induces histionic activation in dogs.

Analyses on the effects of polymeric N-acetyl-D-glucosamine (chitin), which was obtained from squid pen, on histiogenic activation in dogs were carried out with subcutaneous implants (5 x 5 cm2) of polyester non-woven fabric (NWF) supplemented with chitin (chitin group) and NWF (control group). These materials were implanted at 4 sites, on the lumbodorsal and lumbosacral subcutaneous tissues on both sides of the midline in each dog under general anesthesia. The implants and their surrounding tissues were isolated on post-implantation days (PIDs) 2, 4, 8, and 18 under general anesthesia. In the chitin group, the implant was organized gradually and its organization was completed on PID 18, when obvious angiogenesis toward the NWF was observed. On the other hand, in the control group, obvious angiogenesis toward the NWF was not observed macroscopically. Numbers of mononuclear (MN) and polymorphonuclear (PMN) cells concentrated around the implants on PID 2 were larger in the chitin than control group. In the chitin group, formation of granulating tissue around the implant was indicated on PID 4, whereas such a phenomenon was not observed in the control group. From these results, chitin accelerates the migration of MN and PMN cells to the NWF site with rapid follow-up organization of the NWF accompanied by angiogenesis.

Animals↗
PubMed1993

Application of polymeric N-acetyl-D-glucosamine (chitin) to veterinary practice.

The sponge-, cotton-, and flake-type remedies made of chitin (chitin-sponge, chitin-cotton, and chitin-flake, respectively), and non-woven fabric of polyester (NWF) composited with chitin (chitin-NWF) were applied to various types of trauma, abscess, surgical tissue defect and herniorrhaphy in 147 clinical cases including 72 dogs, 38 cows, 33 cats, 2 rabbits, one monkey and one horse. Chitin-sponge was applied in 30 cases as filling agent of surgical tissue defect, and in 25 cases of trauma, 31 cases of abscess as wound dressing or tissue defect filling agent. In 77 out of 86 cases (89.5%), good healing developed. When chitin-sponge was buried in surgical tissue defects due to oncotomy in 20 cases, recurrence of the tumor developed in one case on one month post-operatively, but was not recognized for 3-24 months in 19 cases. Chitin-NWF was applied in 2 cases of trauma and 12 cases of abscess as wound dressing or tissue defect filling agent, 6 cases as filling agent of surgical tissue defect, and 12 cases of umbilical hernia as prosthesis of suture site of hernia ring. In 28 out of 32 cases (87.5%), good healing developed. Chitin-cotton was applied in 8 cases of trauma and 12 cases of abscess as wound dressing or tissue defect filling agent. In 18 out of 20 cases (90.0%), good healing developed. Chitin-flake was applied in 9 cases of trauma as wound dressing or tissue defect filling agent. In 8 out of 9 cases (88.9%), good healing developed. In all cases, no side effects were observed.

Abscess↗
PubMed1992

Behaviour of mouse macrophage cell line and mouse fibroblast on copolymers containing cellulose triacetate.

Copolymers containing cellulose triacetate were prepared under various conditions. A bacteriological plastic dish was coated with the copolymer (HCTA-MDI copolymer) composed of hydrolysed cellulose triacetate (HCTA) and diphenylmethane diisocyanate (MDI). The deacetylated copolymer (DA-copolymer) was prepared by the deacetylation of HCTA-MDI copolymer. The behaviour of animal cells such as a mouse macrophage cell line (A640-BB-2 cells) and a mouse fibroblast (3T6 cells) on prepared dishes was investigated morphologically. A640-BB-2 cells showed good adhesion and smooth spreading, and 3T6 cells also showed good adhesion and sufficient cell growth on the dish coated with HCTA-MDI copolymer. These results suggest that these copolymers are useful for biomedical materials.

Animals↗