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Rie Igarashi

Publications and source records attributed to Rie Igarashi.

16 recordsLinked to original sources
PubMed2006

Transdermal delivery of CaCO3-nanoparticles containing insulin.

BACKGROUND: This study evaluates the pharmacokinetic and pharmacodynamic effects of a transdermally delivered insulin using novel CaCO(3)-nanoparticles in normal mice and those with diabetes. METHODS: CaCO3-nanoparticles encapsulating insulin (nanoinsulin) were transdermally applied to the back skin of normal ddY mice and dB/dB and kkAy mice with diabetes after fasting for 1 h. Serum insulin levels of ddY mice were analyzed by enzyme immunoassay, and blood glucose of normal mice and those with diabetes was monitored. RESULTS: Maximum serum insulin was 67.1 +/- 25.9 microIU/mL at 4 h with 200 microg of transdermal nanoinsulin in ddY mice, whereas that after subcutaneous injection of 3 microg of monomer insulin was 462 +/- 20.9 microIU/mL at 20 min. Transdermal nanoinsulin decreased glucose levels in a dose-dependent manner. A maximum decrease in blood glucose of 48.3 +/- 3.9% (ddY), 32.5 +/- 9.8% (dB/dB), and 26.2 +/- 7.6% (kkAy) after 6 h was observed with 200 microg of transdermal nanoinsulin, compared with 64.1+/-1.0% (ddY), 57.9 +/-3.4% (dB/dB), and 24.1 +/- 6.7% (kkAy) after 1 h with 3 microg of subcutaneous monomer insulin. Insulin bioavailability until 6 h with transdermal nanoinsulin in ddY mice was 0.9% based on serum insulin level and 2.0% on pharmacodynamic blood glucose-lowering effects. CONCLUSIONS: This CaCO(3)-nanoparticle system successfully delivered insulin transdermally, as evidenced by a significant sustained decrease in blood glucose in normal mice and those with diabetes. These results support the feasibility of developing transdermal nanoinsulin for human applications.

Administration, Cutaneous↗
PubMed2006

[Nanotechnology for therapy of type 2 diabetes].

All-trans Retinoic Acid (atRA), is known as a member of retinoid, and the atRA nano-particle with coated by CaCO3 (nanoegg -atRA), was recently developed as a new drug delivery system (DDS). This nanoparticles stimulated insulin secretion from islets in a glucose-dependent manner at streptozotocin (STZ)-induced diabetes. The stains on pancreas of Wistar rat at STZ induced diabetes, which was subcutaneous administered nanoegg -atRA 6 mg/head/week for 141 days, showed not only the expression of PDX-1 but also the presence of beta cell in islet of Langerhans. Furthermore, the increase of insulin concentration in plasma was also observed. Our data indicate that nanoegg -atRA might contribute to the regeneration of beta cells in vivo, and provide useful information for future therapy of diabetes mellitus.

Animals↗
PubMed2005

Genome sequencing and analysis of Aspergillus oryzae.

The genome of Aspergillus oryzae, a fungus important for the production of traditional fermented foods and beverages in Japan, has been sequenced. The ability to secrete large amounts of proteins and the development of a transformation system have facilitated the use of A. oryzae in modern biotechnology. Although both A. oryzae and Aspergillus flavus belong to the section Flavi of the subgenus Circumdati of Aspergillus, A. oryzae, unlike A. flavus, does not produce aflatoxin, and its long history of use in the food industry has proved its safety. Here we show that the 37-megabase (Mb) genome of A. oryzae contains 12,074 genes and is expanded by 7-9 Mb in comparison with the genomes of Aspergillus nidulans and Aspergillus fumigatus. Comparison of the three aspergilli species revealed the presence of syntenic blocks and A. oryzae-specific blocks (lacking synteny with A. nidulans and A. fumigatus) in a mosaic manner throughout the genome of A. oryzae. The blocks of A. oryzae-specific sequence are enriched for genes involved in metabolism, particularly those for the synthesis of secondary metabolites. Specific expansion of genes for secretory hydrolytic enzymes, amino acid metabolism and amino acid/sugar uptake transporters supports the idea that A. oryzae is an ideal microorganism for fermentation.

Aspartic Acid Endopeptidases↗
PubMed2005

Lecithinized superoxide dismutase (PC-SOD) improved spinal cord injury-induced motor dysfunction through suppression of oxidative stress and enhancement of neurotrophic factor production.

PC-SOD (lecithinized superoxide dismutase) is a derivative of human Cu, Zn-SOD conjugated with 4 molecules of lecithin, yet having the enzyme activity of scavenging superoxide anion (O2-). Intravenous administration of PC-SOD promoted the recovery from spinal cord injury (SCI)-induced motor dysfunction in a dose-dependent manner in rat model, when evaluated by BBB (Basso Beattie Bresnahan) score. Even when given at 24 h after SCI, PC-SOD (1 mg/kg) significantly improved motor dysfunction. Distribution study demonstrated that PC-SOD gradually accumulated to the injured site. Enzyme-linked immunoassay revealed that PC-SOD prevented quantitative loss of neurons, astrocytes, and oligodendrocytes. PC-SOD inhibited SCI-induced oxidative stress, such as the decrease of free sulfhydryl residue, acetylcholine esterase activity, and the increase of lipid peroxidation. PC-SOD increased the production of neuroprotective factors. HIF-1alpha gene expression increased following SCI, and PC-SOD further increased it. In conclusion, PC-SOD gradually accumulated and retained at the damaged site to scavenge excessive O2-, and suppressed neuronal death through reducing oxidative stress, increasing neuroprotective factor production and HIF-1alpha gene expression.

Animals↗
PubMed2005

Effects of inducible nitric oxide synthase inhibitors on asthma depending on administration schedule.

The effectiveness of two inducible nitric oxide synthase (iNOS) inhibitors on allergic airway inflammation was investigated under different administration schedules. Rats sensitized to ovalbumin (OVA) were exposed to OVA for 3 consecutive days. Both iNOS inhibitors showed markedly different effects between two pretreatment schedules: pretreatment before each of three OVA exposures S1 and before the third exposure alone S2. S1 pretreatment resulted in higher pulmonary resistance than triple OVA alone. This potentiation was associated with increased eosinophil infiltration and malondialdehyde levels in the lungs, which were suppressed by superoxide dismutases (SODs) but not by methylprednisolone. However, the S2 administration of both iNOS inhibitors completely suppressed the airway response. Administration by schedule S1 completely suppressed plasma nitrite and nitrate levels, but that by S2 caused only a slight suppression. The triple OVA exposures resulted in the upregulation of iNOS in alveolar macrophages and arginase activity, Mn- and Cu/Zn-SOD expression, and nitrotyrosine and lipid peroxide deposition in the airway. However, inhibitors administered by schedule S1 suppressed this upregulation, but further potentiated nitrotyrosine, which in turn was inhibited by SOD. Although iNOS inhibitors may be beneficial for asthma, repeated administration may be detrimental because of extensive reduction of NO and downregulation of SOD.

Amidines↗
PubMed2005

Successful treatment of photo-damaged skin of nano-scale atRA particles using a novel transdermal delivery.

We show a novel drug delivery system (DDS) for improved all-trans retinoic acid (atRA) therapy for external treatments of photo-damaged skin. We prepared inorganic-coated atRA nanoparticles, in turn an egg-like structure in nano-scale (Nano-atRA), using boundary-organized reaction droplets. The interfacial properties of organic architectures, in atRA micelles, were used to template the nucleation of inorganic minerals. As a result, irritation and inflammation associated with atRA therapy were substantially reduced due to the complete encapsulation of the carboxylic function. Both irritative symptoms and physicochemical instability of the atRA micelle were improved. Since Nano-atRA which is prepared following to this new DDS system developmentally improved the permeability to the stratum corneum, the remarkable pharmacological effects were resulted in comparison with atRA as such as follows: (1) thicker epidermis than classical atRA treatment and (2) the overexpression of mRNA for heparin-binding epidermal growth factor (HB-EGF) as the provocation epidermal hyperplasia. Furthermore, we found a surprising boost in production of hyaluronan (HA) among the intercellular spaces of the basal and spinous cell layers in epidermis. Nano-atRA technology for atRA therapy could not only efficiently regulate keratinocyte cell proliferation and differentiation, but also markedly produce the additional benefit. Severely injured human skin by chronic ultraviolet irradiation will completely repair due to the accelerated turnover of skin tissue, which is induced by Nano-atRA.

Administration, Cutaneous↗
PubMed2005

Lecithinized brain-derived neurotrophic factor promotes the differentiation of embryonic stem cells in vitro and in vivo.

The addition of lecithin molecules to brain-derived neurotrophic factor (BDNF) has been reported to markedly enhance its pharmacological effect in vivo. In the current study, we show that lecithinized BDNF (PC-BDNF) has a higher affinity than BDNF for neural precursor cells. Although BDNF only slightly increased the expression of the genes for Mash-1, p35, 68 kDa neurofilament, and TrkB receptor, PC-BDNF caused a significant increase in their expression. PC-BDNF also increased the level of neurofilament protein and dramatically increased TrkB mRNA gene expression, which was followed by a sustained activation of the p42/p44 extracellular-regulated kinases. Finally, transplantation of PC-BDNF-treated cells was more effective than BDNF-treated cells at improving impaired motor function caused by spinal cord injury. These findings showed that PC-BDNF has a better potential than BDNF for promoting neural differentiation, partly due to a higher cellular affinity. Furthermore, PC-BDNF-treated cells could be useful for transplantation therapy for central nervous system injuries.

Animals↗
PubMed2005

Brain-derived neurotrophic factor bound with lecithin derivative showed a markedly enhanced pharmacological potency due to its potent cell membrane affinity followed by prolonged MAPK activation.

We synthesized lecithinized brain-derived neurotrophic factor (lecithinized-BDNF), in which an average of three molecules of a lecithin derivative were bound to recombinant human BDNF. We evaluated its pharmacological activity in C57BL/KsJ-db/db mice, and assessed its targetability and affinity for the nervous system. Subcutaneously administered lecithinized-BDNF markedly reduced the plasma glucose level, food intake, and body weight in C57BL/KsJ-db/db diabetic mice. Its potency was more than 20 times greater than that of unmodified BDNF. We then studied the mechanism for the markedly enhanced pharmacological activity. In vitro cell growth activity of lecithinized-BDNF using the MTT assay was lower than unmodified BDNF, probably due to steric hindrance of the lecithin moieties. While the plasma BDNF level after subcutaneous administration of lecithinized-BDNF was not higher compared with unmodified BDNF. However, higher amount of lecithinized-BDNF accumulated in the spinal cord was observed. Lastly, we found that in vitro binding capacity of lecithinized-BDNF for PC-pAB1 neural cells was much higher than unmodified BDNF. Moreover, lecithinized-BDNF bound to PC-pAB1 cells did not exchange with an excessive amount of unmodified BDNF or an excess of lecithinized-BDNF. PC-pAB1 cells treated with lecithinized-BDNF showed sustained mitogen-activated protein kinase (MAPK, ERK1/2) activation. These data would indicate that the high affinity of lecithinized-BDNF for the target cells, followed by prolonged MAPK activation, would play an important role in its potent pharmacological activity.

Animals↗
PubMed2005

Prostaglandin E2 production in ovarian cancer cell lines is regulated by cyclooxygenase-1, not cyclooxygenase-2.

The significance of cyclooxygenase-2 (COX-2) expression in ovarian cancer has been discussed. In this study, we found increased expression of COX-1 mRNA and protein in three out of 10 ovarian cancer cell lines. Prostaglandin E 2 (PGE2) production was elevated in these three cell lines, but not in other seven cell lines. COX-2 protein was not detected in any of the cell lines. Cytosolic prostaglandin E synthase (cPGES) mRNA and protein were detected in all 10 cell lines. Membrane-associated PGES-1 (mPGES-1) was detected in some of the ovarian cell lines, but its presence did not correspond with PGE2 production. In contrast, mPGES-2 mRNA and protein were detected in all 10 cell lines. A nonselective COX inhibitor (indometacin) and a selective COX-1 inhibitor (SC-560) strongly inhibited PGE2 production by the three cell lines, while selective COX-2 inhibitors (NS-398 and rofecoxib) did not inhibit PGE2 production. In addition, increased expression of COX-1, not COX-2 protein was observed in the mass of ovarian cancer tissues from 22 patients when compared with that in normal tissue. These findings suggest that COX-1 might be a major enzyme regulating PGE2 production in ovarian cancer cells.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Optimum formulation for sustained-release insulin.

Our aim was to prepare an optimum formulation for a sustained-release preparation of insulin using biodegradable polymer composed of co-poly(D,L-lactic/glycolic) acids (PLGA)(L/G ratio: 50/50). Various kinds of PLGA microcapsules containing 3% insulin were administered subcutaneously (250 U/kg) as a single dose to rats with streptozotocin-induced diabetes, and plasma insulin levels were monitored. The following results were obtained. (1) Glycerin and water were suitable additives to prepare a reproducible injectable formulation. (2) Addition of zinc compounds was essential to diminish rapid insulin release and six-fold molar excess of ZnO to insulin was desirable. (3) The size of insulin particles showed the following order: human insulin > lyophilized human insulin > Zn-free human insulin. Zn-free insulin was similar to lyophilized insulin with respect to control of rapid release, so a smaller particle size was essential. (4) The size of the microcapsules also affected the release of insulin. With larger microcapsules (approximately 30 microm), there was gradual release and a significant second phase of insulin release, while smaller microcapsules did not allow sustained release. Some variation in microcapsule size contributed to more constant and sustained release. (5) Based on the insulin release profile in vivo, a suitable molecular weight for PLGA was around 6000. The biological activity of insulin extracted from the formulation was similar to that of normal insulin. These experiments allowed us to prepare a desirable sustained-release insulin formulation.

Animals↗
PubMed2003

Effects of prolonged delivery of brain-derived neurotrophic factor on the fate of neural stem cells transplanted into the developing rat retina.

One of the major roles of brain-derived neurotrophic factor (BDNF) is to promote the differentiation and support the survival of neurons in the central nervous system. The objective of the present study was to evaluate the effect of BDNF on the fate of adult rat hippocampus-derived neural stem cells (AHPCs) transplanted into the developing rat retina. Immunohistochemical analysis showed a significant increase in the ratio of grafted AHPCs stained for MAP2ab (P<0.05) and a marked decrease in the ratio of nestin-positive grafted cells in the slow-releasing BDNF group compared with the control group. The respective changes in the ratios of MAP5 and GFAP-positive grafted cells were comparable for the two groups. The results reported here suggest a potentially beneficial role for extended delivery of BDNF in the differentiation of grafted neural stem cells, which may lead to a novel modification of stem cell transplantation.

Animals↗
PubMed2003

Lecithin-bound superoxide dismutase in the treatment of noninfectious corneal ulcers.

PURPOSE: To evaluate the effects of a lipophilic analog of superoxide dismutase in the treatment of persistent epithelial defects of the cornea. DESIGN: Interventional case series. METHODS: Nineteen eyes of 19 patients with noninfectious corneal ulcers were enrolled. Patient profiles consisted of seven cases with Mooren-type peripheral ulcers, three cases with chemical or thermal burns, two cases with vernal keratoconjunctivitis, four cases with cicatricial keratoconjunctivitis, and three cases with sterile ulcers after corneal surgery. Patients consisted of 11 men and 8 women, with a mean age of 51.5 +/- 17.9 years (range, 14-77). Only patients who did not respond to conventional therapy were recruited for the study. Lecithinated superoxide dismutase was applied for 2 weeks, and sketches and/or fluorescein slit micrographs were recorded before and at the end of the study. The main outcome measure was decrease in ulcer size. RESULTS: As a group, the average ulcer size relative to the entire cornea decreased from 18.2 +/- 15.1% to 10.0 +/- 15.0% after 2 weeks (P <.05). A dramatic effect (>90% decrease in ulcer size) was observed in eight cases (100% in six cases), whereas no apparent change was found (<30% decrease in ulcer size) in five cases. The presence of polymorphonucleocytes within the ulcerated tissue was confirmed by brush cytology. CONCLUSION: Lecinthinated superoxide dismutase was effective in decreasing persistent epithelial defect size in a subset of patients with sterile corneal ulcers refractive to conventional therapy. A large-scale clinical investigation is merited.

Adolescent↗
PubMed2003

Porcine enamel matrix derivative enhances the formation of reparative dentine and dentine bridges during wound healing of amputated rat molars.

We examined the biological effects of porcine enamel matrix derivative (EMD; Emdogain) on the formation of reparative dentine and dentine bridges in rat molars after pulp amputation. The pulp chambers of upper molars of Wistar rats were perforated and the amputated pulp surfaces were directly capped with either EMD or its carrier propylene glycol alginate (PGA) as control. The cavities were then restored with glass-ionomer cement. On post-amputation days 4-30, the dissected maxillae were examined by light and electron microscopy. In PGA-capped pulp, reparative dentine had been formed over the dentine walls under the prepared cavity on day 7 post-amputation and its thickness extended until day 30. On day 30, as well as reparative dentine formation, diffuse calcification had occurred beneath the amputated wound surfaces. Dentine bridge formation under the amputated coronal pulp surface was observed in 18.2% of amputated pulp on day 30. In EMD-capped pulp, reparative dentine had already been formed by odontoblast-like cells over the dentine walls, already on day 4 post-amputation, and its thickness extended until day 30. The Ca and P weight % and Ca/P ratio of reparative dentine matrix were similar to those of pre-existing dentine matrix, and these values were not different between PGA and EMD-capped pulp. Dentine bridge formation was observed in 27.3% of EMD-capped pulp on day 30. Our results suggest that EMD enhances the formation of both reparative dentine and dentine bridges during wound healing of amputated rat molar pulp.

Amputation, Surgical↗
PubMed2002

A novel sustained-release formulation of insulin with dramatic reduction in initial rapid release.

To ensure a strictly controlled release of insulin, a preparation method for insulin-loaded microcapsules was designed. Microcapsules were prepared with an injectable, biodegradable polymer composed of co-poly(D,L-lactic/glycolic) acids (PLGA) (mean molecular weight 6600, LA/GA ratio 50:50). Morphological examination using scanning electron microphotography demonstrated spherical particles with a main diameter of 15-30 microm. When 3% insulin-loaded PLGA microcapsules were administered subcutaneously as a single dose (250 U/kg) to streptozotocin-induced hyperglycemic rats, plasma insulin levels increased and were sustained at levels showing hypoglycemic effects. When glycerin, ethanol, or distilled water was used throughout the preparation procedure, the resultant microcapsules dramatically reduced the initial burst. The formulation in which glycerin was added to an oil phase containing PLGA, insulin, and ZnO increased plasma insulin levels to 86.7, 108.4, and 84.9 microU/ml at 1, 2, and 6 h, respectively. The levels remained at 36.2-140.7 microU/ml from day 1 to day 9. The AUC(0-24 h)/AUC(0-336 h) ratio was calculated to be 9.7%. The formulation prepared without additives gave such a rapid insulin release that animals receiving it became transiently hypoglycemic.

Animals↗
PubMed2002

A novel insulin formulation can keep providing steady levels of insulin for much longer periods in-vivo.

We have recently succeeded in preparing insulin-loaded microcapsules that release the insulin in a strictly controlled manner with little initial rapid release in-vitro or in-vivo. We show here the superiority of the best formulation prepared with co-poly(D,L-lactic/glycolic) acids (PLGA) (mean MW 5800, L/G ratio 50:50) with a main diameter of 15 approximately 30 microm in-vivo. When 3.2 % insulin-loaded PLGA microcapsules were subcutaneously given as a single dose to streptozotocin-induced hyperglycaemic rats (250 U kg(-1)), plasma insulin levels gradually increased and constant levels (30.3-94.1 microU mL(-1)) were sustained. Rats receiving the formulation once a week showed not only steady plasma insulin levels, but also gained weight at a similar speed to normal rats. Meanwhile, daily treatment with Humulin U (25 U kg(-1)) caused a transient high insulin level (2723.9 microU mL(-1) at 1 h) in plasma, but the body weight of the rats was little changed. A pharmacological study in female Cynomolgus monkeys also revealed that the microcapsular formulation provided a flat release of insulin for longer periods and showed no immunogenic activity. In the near future, therefore, this insulin formulation could become very beneficial as a provider of basal insulin levels for insulin-dependent diabetic patients.

Animals↗