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ABSTRACT: We investigated the protective effects of sericin on corneal damage due to benzalkonium chloride (BAC) used as a preservative in commercially available timolol maleate eye drops using rat debrided corneal epithelium and a human cornea epithelial cell line (HCE-T). Corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera; eye drops were instilled into the rat eyes five times a day after corneal epithelial abrasion. The viability of HCE-T cells was calculated by TetraColor One; and Escherichia coli (ATCC 8739) were used to measure antimicrobial activity. The reducing effects on transcorneal penetration and intraocular pressure (IOP) of the eye drops were determined using rabbits. The corneal wound healing rate and rate constants (k) as well as cell viability were higher following treatment with 0.005% BAC solution containing 0.1% sericin than in the case of treatment with BAC solution alone; the antimicrobial activity was approximately the same for BAC solutions with and without sericin. In addition, the k for rat eyes instilled with commercially available timolol maleate eye drops containing 0.1% sericin was significantly higher than that of eyes instilled with timolol maleate eye drops without sericin, and the addition of sericin did not affect the corneal penetration or IOP reducing effect of commercially available timolol maleate eye drops. A preservative system comprising BAC and sericin may provide effective therapy for glaucoma patients requiring long-term anti-glaucoma agents.
Journal of oleo science 01/2013; 62(3):159-66. · 1.42 Impact Factor
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ABSTRACT: We previously found two mechanisms for the dysfunction in Ca(2+) regulation caused by excessive nitric oxide (NO) using the lenses of hereditary cataract model rats: the first is that NO causes a decrease in Adenosine-5'-triphosphate (ATP) level via cytochrome c oxidase (CCO), resulting in a decrease in ATPase function; the second is that NO causes enhanced lipid peroxidation, resulting in the oxidative inhibition of Ca(2+)-ATPase. In this study, we demonstrate the effect of excessive NO on lipid peroxidation and ATP production in human lens using a human lens epithelial cell line, SRA 01/04 (human lens epithelial (HLE) cells).
Excessive NO via inducible NO synthase (iNOS) was induced by stimulating cells with a combination of interferon-gamma (1000 IU IFN-γ) and lipopolysaccharide (100 ng/mL LPS). CCO activity was measured using a Mitochondrial Isolation kit and Cytochrome c Oxidase Assay kit, and ATP levels were determined using a Sigma ATP Bioluminescent Assay Kit and a luminometer AB-2200.
Cytochrome c oxidase activity and ATP levels were decreased in HLE cells stimulated with IFN-γ and LPS, and aminoguanidine (AG) and diethyldithiocarbamate (DDC) added 6 h before cell collection significantly attenuated these decreases in cells stimulated with the IFN-γ and LPS for 24-30 h. However, the lower CCO activity and ATP levels in HLE cells stimulated with the IFN-γ and LPS for 30 h were not changed by treatment with AG or DDC for 6-12 h, while the CCO activity and ATP levels in HLE cells treated with AG or DDC for 18 were recovered.
Excessive NO causes a decrease in CCO activity and ATP levels, and the recovery time for CCO activity is related to exposure time to NO in HLE cells.
Current eye research 05/2012; 37(10):889-97. · 1.51 Impact Factor
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ABSTRACT: To investigate the anti-inflammatory effects of the instillation of disulfirum (DSF) eyedrops that enhance solubility using 2-hydroxypropyl-β-cyclodextrin (HPβCD) and hydroxypropylmethylcellulose (HPMC) on endotoxin-induced uveitis (EIU) in rats and mechanisms related to ocular inflammation.
EIU was induced in male Lewis rats by subcutaneous injection of 200 μg lipopolysaccharide (LPS). DSF (0.125%, 0.25% and 0.5%) or commercially available 0.05% dexamethasone (Dexa) was topically applied to both eyes of rats 1 hour before, immediately after, and 1 and 2 hours after injection of LPS. The aqueous humor (AqH) was collected 24 hours after LPS injection, and the number of infiltrating cells, protein concentration, and levels of tumor necrosis factor-α (TNF-α), nitric oxide (NO) and prostaglandin E2 (PGE2) were determined. Immunohistochemical analysis of the iris ciliary body (ICB) cells was performed to determine the expression of activated nuclear factor κB (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2).
The topical administration with DSF suppressed, in a dose-dependent manner, the number of inflammatory cells, the protein concentration, and the levels of NO, TNF-α and PGE2 in the AqH and improved the histologic status of the ocular tissue. The anti-inflammatory potency of 0.5% DSF treatment was as strong as that of 0.05% Dexa. Topical DSF treatment also suppressed the activated NF-κB 3 hours after LPS injection, and iNOS and COX-2 expression in the ICB 24 hours after LPS injection.
The present results demonstrate that the topical instillation of DSF eyedrops suppresses the inflammation in EIU, suggesting a possible novel approach for the treatment of ocular inflammation.
Current eye research 02/2012; 37(2):124-31. · 1.51 Impact Factor
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ABSTRACT: Benzalkonium chloride (BAC) is known to cause corneal epithelial damage. In this study we investigated the effect of a BAC solution containing a thickening agent, which enhanced residence time in the eyes, on corneal wound healing using in vivo rat model debrided corneal epithelium. 0.5% or 1.0% methylcellulose (MC), carboxymethylcellulose (CMC) and hydroxypropyl-methylcellulose (HPMC) were used as the thickening agent. The levels of corneal wound healing of rat eyes injected with saline were alone approximately 45.0% at 12 h and 93.6% at 24 h after corneal epithelial abrasion, and healing was almost complete at 36 h. The healing rate in the rat eye treated just with MC, CMC and HPMC was higher than that in those injected with saline. In contrast to the treatment result using only this thickening agent, the healing rate in the eye treated with BAC was lower than that in those injected with saline: the corneal wounds in the BAC-treated eye showed approximately 20% healing at 12 h after abrasion. The injection of 0.02% BAC solution containing MC, CMC and HPMC more significantly delayed the healing than did the injection of 0.02% BAC alone. The results show that the in vivo evaluation method for corneal damage using rat debrided corneal epithelium reflects a toxic change depending upon residence time. These findings provide valuable safety and efficacy information for use in the design of eye drops.
YAKUGAKU ZASSHI 01/2012; 132(7):837-43. · 0.37 Impact Factor
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ABSTRACT: The dissolution test is a core performance test in pharmaceutical development and quality control of solid drug products. The conventional HPLC dissolution method (batch-sampling method) involves many steps including the filtration, collection and replenishment of sample solutions. We previously reported a dissolution test that involved microdialysis methods (microdialysis-HPLC method) and allowed many steps to be omitted. However, the recovery rate of theophylline by the microdialysis-HPLC method was lower, and the decrease in the flow rate through the dialysis probe caused variation between each tablet. In this study, we have attempted to improve the dissolution test by using a precise micro-controlled roller pump and microfiltering probe (microfiltering-HPLC method). Sustained release preparations of Theodur(®) (100 mg) were used, and the test solutions used were water, buffer at pH 1.2 and pH 6.8, and pH 6.8-buffer containing 0.1-1% polysorbate 80 or sodium lauryl sulfate. In all test solutions, the microfiltering-HPLC method was able to accomplish continuous sampling of sample solutions, and the recovery rate of theophylline was over 90%. The dissolution behavior by the microfiltering-HPLC method tends to reflect the pharmaceutical design in comparison with the batch-sampling method, and the standard deviations by the microfiltering-HPLC are lower than with the batch-sampling method. In addition, the microfiltering-HPLC method allows many steps to be omitted, such as the filtration, collection and replenishment of sample solutions. These findings provide significant information that can be used in the pharmaceutical development and quality assessment of solid drug products.
YAKUGAKU ZASSHI 01/2012; 132(11):1307-16. · 0.37 Impact Factor
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ABSTRACT: We attempted to develop anti-cataract eye drops using disulfiram (DSF) and low-substituted methylcellulose (MC), and evaluated their anti-cataract effect in terms of the lens opacification vs. age-profile curves using a one-exponential equation. The eye drops were prepared using 0.5% DSF and 2% MC (DSF eye drops), and ICR/f rats, a recessive-type hereditary cataractous strain, were used as the experimental model. Gelation of DSF eye drops containing MC was first observed at about 35°C, close to body temperature. In in vivo transcorneal penetration experiments using rabbit corneas, only diethyldithiocarbamate (DDC) was detected in the aqueous humor, while DSF was not detected. The DDC penetration level of DSF eye drops containing MC was approximately 1.3-fold higher than that of DSF eye drops. The opacification rate constant (k) of ICR/f rat instilled with DSF eye drops with or without MC was lower, and the initial time of opacification (τ) was longer than those of ICR/f rats instilled with saline. Furthermore, the k of ICR/f rats instilled with DSF eye drops with MC was lower than that of ICR/f rats instilled with DSF eye drops without MC. In conclusion, the analysis of kinetic parameters including k and τ using a one-exponential equation provided useful information for clarifying the anti-cataract effect of eye drops. ICR/f rats instilled with DSF eye drops using a low-substituted MC-based drug delivery system demonstrated a delay in cataract development, probably resulting from an increase in the retention of DSF eye drops on the cornea.
Biological & Pharmaceutical Bulletin 01/2012; 35(2):239-45. · 1.66 Impact Factor
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ABSTRACT: Non-steroidal anti-inflammatory drugs (NSAIDs) comprise one of the most frequently used classes of medicines in the world; however, NSAIDs have significant side effects, such as gastroenteropathy, and rheumatoid arthritis patients taking NSAIDs are more susceptible to NSAID-induced gastric lesions as compared to patients with other diseases. In Asian countries, loxoprofen has been used clinically for many years as a standard NSAID. We demonstrate the preventive effect of the co-administration of water containing magnesium ion (magnesium water, 1-200 µg/kg) on the ulcerogenic response to loxoprofen in adjuvant-induced arthritis (AA) rats. Oral administration of loxoprofen (100 mg/kg) caused hemorrhagic lesions in the gastric mucosa of AA rats 14 d after adjuvant injection, and, following loxoprofen administration, the lesion score of AA rats was significantly higher than that of normal rats. The expression of inducible nitric oxide synthase (iNOS) mRNA and nitric oxide (NO) production in the gastric mucosa of AA rats were also increased by the administration of loxoprofen, and the increase in lesions and NO were prevented by the administration of aminoguanidine, an iNOS inhibitor. The co-administration of magnesium water decreased the ulcerogenic response to loxoprofen in AA rats. In addition, the co-administration of magnesium water attenuated the increase in iNOS mRNA expression and NO production in AA rats receiving loxoprofen. These results suggest that the oral co-administration of magnesium water to AA rats has a potent preventive effect on the ulcerogenic response to loxoprofen, probably by inhibiting the rise in iNOS and NO levels in the gastric mucosa.
Biological & Pharmaceutical Bulletin 01/2012; 35(12):2230-7. · 1.66 Impact Factor
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ABSTRACT: Mature interleukin 18 (IL-18) leads to the production of interferon-γ, nuclear factor kappa B, and inducible nitric oxide synthase, and we previously reported that the enhancement of IL-18 in lens of hereditary cataract model rats was involved in lens opacification. In this study, we investigated whether the expression of IL-18 relates to lens opacification in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus.
Male Long-Evans Tokushima Otsuka (LETO) and OLETF rats at 60 weeks of age were used in this study. Expression of IL-18 mRNA was measured by quantitative real-time RT-PCR method, and IL-18 and interferon-γ levels were determined using the ELISA method. The transparency of the lenses was monitored using an EAS-1000, and analyzed by image analysis software connected to the EAS-1000.
The plasma levels of glucose, triglycerides and cholesterol in the OLETF rats were significantly higher than in LETO rats as normal controls, and the development of diabetes mellitus was observed. The gene expression levels causing IL-18 activation (IL-18, IL-18 receptor, and caspase-1) are increased at 60 weeks of age, and the levels of IL-18 and interferon-γ in 60-week-old OLETF rat lenses were also higher than those in the 60-week-old LETO rat. Furthermore, the interferon-γ levels increased with increasing IL-18 levels in the lenses of OLETF rat, and a close relationship was observed between the levels of IL-18 and opacity.
The expression of IL-18 was increased in the lenses of OLETF rat. It is possible that activated IL-18 in the lenses of OLETF rat may be related to the lens epithelial cell apotosis and lens opacification.
Current eye research 06/2011; 36(6):497-506. · 1.51 Impact Factor
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ABSTRACT: Dissolution testing is a core performance test in pharmaceutical development and quality control. The conventional HPLC dissolution method (batch-sampling method) has many steps such as the filtration, collection and replenishment of sample solutions. We previously reported the dissolution test by using microdialysis methods (microdialysis-HPLC method) that can omit many steps. In this study, we investigated whether the microdialysis-HPLC method can be applied to quality assessment for sustained release preparations by a dissolution test. Calcium-channel blockers nifedipine tablets (20 mg) were used, and the test solution used was 0.2 M hydrogen phosphate-citric acid buffer (pH 6.8) with or without 1% sodium lauryl sulfate. In both test solutions, the microdialysis-HPLC method is able to accomplish continuous sampling of sample solutions, and the dissolution behaviors of original nifedipine tablets by the microdialysis-HPLC method were similar to that of the batch-sampling method. In contrast, the dissolution behaviors by the microdialysis-HPLC method were different between original nifedipine tablets and generic products, and the dissolution behaviors in the microdialysis-HPLC method tend to reflect the pharmaceutical design in comparison with the batch-sampling method. In addition, standard deviation in the microdialysis-HPLC method was lower than that of the batch-sampling method. We found that the recovery rate of nifedipine by the microdialysis-HPLC method was increased with the decrease in flow rate through dialysis probe. These findings provide significant information that can be used in pharmaceutical development and quality assessment for original and generic pharmaceutical products, which are sustained release preparations.
YAKUGAKU ZASSHI 04/2011; 131(4):621-8. · 0.37 Impact Factor
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ABSTRACT: Our previous studies have demonstrated that lipid peroxidation in the lenses of hereditary cataract model rats (Ihara cataract rat (ICR)/f rats) caused a dysfunction in Ca(2+) regulation. In the present study, we investigated the effect of in vitro hydrogen peroxide (H(2)O(2)) stimulation on lipid peroxide (LPO) and the activities of sarco-/endoplasmic reticulum and plasma membrane Ca(2+)-ATPase (SERCA and PMCA) in the ICR/f rat lenses. An increase in LPO level and decreases in the SERCA and PMCA activities were observed with increasing H(2)O(2) concentration, and pretreatment with diethyldithiocarbamate, a potent radical scavenger, attenuated these changes in normal and ICR/f rat lenses. The glutathione levels, glutathione peroxidase and glutathione reductase activities are significantly lower in ICR/f rat lenses than in normal rat lenses. Furthermore, we presented as two kinetic parameters such as DP (defense point) and K(s) (reactive constant) analyzed from above various biological responses vs. H(2)O(2) concentration-profile curves using a one-exponential equation. The DPs for LPO, SERCA and PMCA in ICR/f rat lenses is lower than in normal rat lenses. In contrast to the results in DP, the K(s) for LPO, SERCA and PMCA in ICR/f rat lenses is higher than in normal rat lenses. In addition, the closed relationship of was observed between DP and K(s) for LPO, SERCA and PMCA. These results show that the resistance to H(2)O(2) in the ICR/f rat lenses is lower than that of normal rats. The DP and K(s) values can provide an useful information for resistances to various stimuli in cells and tissues.
Biological & Pharmaceutical Bulletin 01/2011; 34(7):1005-10. · 1.66 Impact Factor
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ABSTRACT: The combination of anti-glaucoma eye drops is frequently used in clinical treatment, and it is known that the combination can cause corneal damage. Recently, an anti-glaucoma combination eye drops is developed, and the treatment by the combination eye drops is expected to enhance quality of life. However, effects of the combination eye drops on corneal epithelial cell damage have not been clarified. In this study, we investigated the corneal epithelial cell damage of commercially available anti-glaucoma combination eye drops, such as Xalacom® (latanoprost/timolol maleate combination eye drops), Duotrav® (travoprost/timolol maleate combination eye drops) and Cosopt® (dorzolamide hydrochloride/timolol maleate combination eye drops) using the human corneal epithelial cell (HCE-T). The cytotoxicity in Xalacom® was higher than that in Xalatan® (eye drops containing latanoprost) and Timoptol® (eye drops containing timolol maleate), and the benzalkonium chloride (BAC) and timolol maleate were related to cytotoxicity in Xalacom®. The cytotoxicity in Duotrav® and Cosopt® was lower than that in Timoptol®. The Duotrav® is preserved with a non-BAC system (POLYQUAD, polidronium chloride). Therefore, it was suggested that the POLYQUAD related to the low cytotoxicity in Duotrav®. On the other hand, the D-mannitol reduced the cytotoxicity by BAC in this study. This result suggested that the cytotoxicity in Cosopt® was reduced by D-mannitol. The Duotrav® and Cosopt® may be less damaging to the ocular surface of glaucoma patients receiving long-term eye drop therapy in compared with the combination of anti-glaucoma eye drops.
YAKUGAKU ZASSHI 01/2011; 131(6):985-91. · 0.37 Impact Factor
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ABSTRACT: To investigate potency of oral disulfiram (DSF) compared with that of dexamethasone (Dexa), on endotoxin-induced uveitis (EIU) in rats. The oral administration with 750 mg/kg DSF suppressed the number of inflammatory cells, protein concentration, and levels of tumor necrosis factor (TNF)-α, Nitric oxide (NO) and prostaglandin (PG) E2 in the aqueous humor and improved the histiologic status of the ocular tissue at 24 hr after lipopolysaccharide (LPS) injection. The anti-inflammatory potency of DSF oral administration was as strong as that observed with 0.5 mg/kg Dexa in the present study. The results suggest that DSF might pave the way for a novel therapeutic agent for the management of uveitis.
Journal of Veterinary Medical Science 12/2010; 73(4):517-20. · 0.85 Impact Factor
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Kazutaka Kanai,
Naoyuki Itoh,
Kazuki Yoshioka,
Tomohiro Yonezawa,
Hiromi Ikadai,
Yasutomo Hori,
Yoshimasa Ito, Noriaki Nagai,
Seishirou Chikazawa,
Fumio Hoshi,
Seiichi Higuchi
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ABSTRACT: Disulfiram (DSF) exhibits a wide variety of biological activities, including an anti-inflammatory action, on which we focused our attention. The aim of the present study was to investigate the effect of oral DSF on endotoxin-induced uveitis (EIU) in rats.
We investigated its effect upon cellular infiltration and protein leakage, as well as on the concentration of tumor necrosis factor-α (TNF-α), nitric oxide (NO), and prostaglandin E2 (PGE2) in the anterior chamber. Some eyes were enucleated for histologic examination and immunohistochemical analysis. EIU was induced in male Lewis rats by a footpad injection of lipopolysaccharide (LPS). One hour before the LPS injection, either 250, 500, or 750 mg/kg DSF was administered orally. Twenty-four hours later, the aqueous humor was collected from both eyes, and the number of infiltrating cells and protein concentration in the aqueous humor were determined. Levels of TNF-α, NO, and PGE2 were determined by enzyme-linked immunosorbent assay. Immunohistochemical analysis in the iris ciliary body (ICB) cells was performed to determine the expression of activated nuclear factor kappa B (NF-κB), inducible-nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2).
The oral administration with DSF suppressed, in a dose-dependent manner, the number of inflammatory cells, the protein concentration, and the levels of TNF-α, NO, and PGE2 in the aqueous humor and improved the histiologic status of the ocular tissue. The expression of activated NF-κB-positive cells in the ICB was significantly inhibited by oral administrated with DSF 3 hr after the LPS injection. The LPS-induced increased expressions of iNOS and COX-2 proteins in the ICB were also inhibited by oral DSF 24 hr after LPS injection.
The present results indicate that oral DSF suppresses the inflammation in EIU by inhibiting the NF-κB-dependent pathway and the subsequent production of pro-inflammatory mediators.
Current eye research 10/2010; 35(10):892-9. · 1.51 Impact Factor
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ABSTRACT: We have studied the effect of disulfiram (DSF) solution containing 2-hydroxypropyl-beta-cyclodextrin and hydroxypropylmethylcellulose (DSF eye drops) on intraocular pressure (IOP) in experimentally induced ocular hypertension in rabbits. In both in vitro and in vivo transcorneal penetration experiments using rabbit corneas, only diethyldithiocarbamate (DDC) was detected in the aqueous humor, while DSF was not detected. The amount of DDC penetration for 0.25% DSF eye drops was about 4-fold that for 0.1% DSF eye drops in in vivo transcorneal penetration experiments. The elevation in IOP was induced by the rapid infusion of 5% glucose solution (15 ml/kg of body weight) through the marginal ear vein, and IOP was measured with an electronic tonometer. The induced elevation in IOP was reduced by the instillation of 0.1-0.5% DSF eye drops, and the IOP-reducing effect increased with the increase in DSF concentration in the drops. Nitric oxide (NO) levels increased in the aqueous humor following the infusion of the 5% glucose solution, and this increase was also suppressed by the instillation of DSF eye drops. In conclusion, the present study demonstrates that the instillation of DSF eye drops has an IOP-reducing effect in rabbits with experimentally induced ocular hypertension, probably caused by the suppression of NO production.
Biological & Pharmaceutical Bulletin 01/2010; 33(9):1574-8. · 1.66 Impact Factor
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ABSTRACT: To evaluate the pharmacological properties of cilostazol (CLZ), we examined its intraocular pressure (IOP) -lowering effect. CLZ is an inhibitor of Type III phosphodiesterase that increases intracellular cyclic AMP levels by restraining platelet aggregation, and has a potential protective effect against atherosclerosis. We attempted to apply it for use as an anti-glaucoma agent; however, the application of CLZ in the ophthalmic field is limited due to its poor water solubility. We attempted to enhance CLZ solubility using 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD). The solubility of CLZ increased with increasing HPbetaCD concentrations, and 0.05% CLZ was dissolved in 10% HPbetaCD. Moreover, fine particle suspension of 0.5% CLZ in 5% HPbetaCD (soluble CLZ: ca. 0.027%) were prepared using a Microfluidizer, an impact-type emulsifying comminution device. In an in vitro transcorneal penetration experiment through the rabbit cornea, the CLZ penetration rate was dependent on the CLZ content of the solutions and suspensions. When a 0.05% CLZ ophthalmic solution was instilled into a rabbit eye, the absorption rate constant for CLZ into an aqueous humor was 0.0059+/-0.001 min(-1), and the elimination rate constant was 0.048+/-0.024 min(-1). Also CLZ ophthalmic solutions and fine particle suspension were examined to for their ability to reduce enhanced intraocular pressure (IOP) of rabbits in a darkroom. The instillation of 0.05% CLZ ophthalmic solutions and 0.5% CLZ fine particle suspensions into rabbit eyes reduced the enhanced IOP. These results demonstrate that the instillation of CLZ ophthalmic solutions and fine particle suspensions may represent an effective anti-glaucoma formulation.
Journal of oleo science 01/2010; 59(8):423-30. · 1.42 Impact Factor
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ABSTRACT: We compared the corneal toxicity of two commercially available anti-glaucoma ophthalmic solutions, travoprost eye drops with sofzia consist of boric acid (H(3)BO(3)) and zinc chloride (ZnCl(2)) and latanoprost eye drops with benzalkonium chloride (BAC), using rat debrided corneal epithelium. Rat corneal epithelium was removed with a BD Micro-Sharp, and the wounded corneas were dyed with a 1% fluorescein solution. The corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera. Eye drops were instilled into the rat eyes five times a day after corneal epithelial abrasion. The corneal wound of a rat eye instilled with saline showed 50.9% and 83.4% healing 12 and 24 h after corneal epithelial abrasion, respectively. The healing rate of the corneal wound of a rat eye instilled with travoprost eye drops with sofzia was similar to that of the eye instilled with saline, and this rate was higher than in an eye instilled with latanoprost eye drops with BAC. The rates of corneal wound healing were also lower in eyes instilled with BAC and H3BO3 eye drops than in eyes instilled with saline. In contrast to the results with BAC and H(3)BO(3), the instillation of ZnCl(2) enhanced corneal wound healing in comparison with the instillation of saline The present study demonstrates that the classic preservative system using BAC may be more toxic to rat corneal epithelium than the new preservative system using H(3)BO(3)/ZnCl(2). Travoprost eye drops with sofzia may provide effective therapy for glaucoma patients using long-term ophthalmic agents.
Journal of oleo science 01/2010; 59(3):135-41. · 1.42 Impact Factor
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ABSTRACT: Diabetic keratopathy is a well-known ocular complication secondary to type 2 diabetes mellitus. In this study, we performed a kinetic analysis of corneal wound healing in Long-Evans rats (normal rat) and Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus. Corneal wound healing in 7-week-old normal rats was mostly complete 24 h after corneal epithelial abrasion, and the process of corneal wound healing took place according to an equation with a first-order rate constant. The rate of corneal wound healing in normal rats decreased with aging. The process of corneal wound healing in 38- and 60-week-old normal and OLETF rats occurred in two phases with rate constants for the first and second phases represented as alpha and beta, respectively. The alpha and beta values in 38- and 60-week-old OLETF rats were lower than those in normal rats of the corresponding age. Furthermore, a close relationship was observed between the corneal wound healing rate constant and plasma glucose levels in OLETF rats. The present studies suggest the sequence of events that occur following damage to the corneal surface in OLETF rats as a model animal for a human type 2 diabetes mellitus.
Journal of oleo science 01/2010; 59(8):441-9. · 1.42 Impact Factor
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ABSTRACT: Dissolution testing is a core performance test in pharmaceutical development and quality control. Generally, the HPLC method uses the analysis of dissolution testing. In this study, we attempted to improve the dissolution test by using microdialysis methods. We also investigated the comparison of the conventional HPLC dissolution method (batch-sampling method) and the improved dissolution test (microdialysis method). Histamine H(2)-receptor antagonist cimetidine tablets (200 mg), which are used clinically and of which there are also some generic examples, were selected for this comparison, and the dissolution behavior of the tablets by the two methods were found to be similar. On the other hand, standard deviation in the microdialysis method was lower than that of the batch-sampling method. In addition, the microdialysis method can omit many steps such as the filtration, collection and replenishment of sample solutions, and is also able to accomplish continuous sampling of sample solutions. These findings provide significant information that can be used in the pharmaceutical development and quality control of original and generic products.
Yakugaku zasshi journal of the Pharmaceutical Society of Japan 12/2009; 129(12):1515-21. · 0.39 Impact Factor
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ABSTRACT: The protein sericin is the main constituent of silk. We investigated the effects of sericin on corneal wound healing in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model for human type 2 diabetes. Corneal wounds were prepared by removal of the corneal epithelium, and documented using a TRC-50X equipped with a digital camera. Sericin solutions were instilled into the eyes of rats five times a day following corneal abrasion. Plasma glucose and triglycerides were determined using an Accutrend GCT. Cholesterol and insulin were measured using a Cholesterol E-Test Kit and ELISA Insulin Kit, respectively. The plasma levels of glucose, triglycerides, cholesterol and insulin in 38-week-old OLETF rats were significantly higher than in Long-Evans Tokushima Otsuka (LETO) rats used as normal controls, and the rate of corneal wound healing in OLETF rats was slower than in LETO rats. The corneal wounds of rats instilled with saline showed almost complete healing by 72 h after corneal epithelial abrasion. On the other hand, the corneal healing rate of OLETF rats instilled with 10% sericin solution was significantly higher than that of LETO rats instilled with saline, and the wounds showed almost complete healing at 48 h after abrasion. The corneal healing rate increased with increasing sericin concentration. The present study demonstrates that the corneal wound healing rate in OLETF rat is slower than in LETO rats, and the instillation of sericin solution has a potent effect in promoting wound healing and wound-size reduction in LETO and OLETF rats.
Biological & Pharmaceutical Bulletin 10/2009; 32(9):1594-9. · 1.66 Impact Factor
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ABSTRACT: The protein sericin is the main constituent of silk. We demonstrate the effects of sericin on corneal wound healing in rat debrided corneal epithelium. We also determined the effects of sericin on cell adhesion and proliferation in a human cornea epithelial cell line (HCE-T). Epithelium was removed from the corneas of rats with a BD Micro-Sharp, and wounded corneas were dyed with a 1% fluorescein solution. The corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera. The corneal wound of rats instilled with saline was approximately 10% healing at 12 h, and approximately 65% healing at 24 h after corneal epithelial abrasion. The corneal wounds of rats instilled with saline showed almost complete healing by 36 h after corneal epithelial abrasion. On the other hand, the corneal healing rate of rats instilled with sericin solution was higher than that of rats instilled with saline, and the corneal healing rate constant increased with increasing sericin concentration. In addition, the adhesion and proliferation of HCE-T cells treated with 0.01-0.5% sericin solutions were enhanced, reaching a maximum at treatments with 0.2 and 0.1% sericin solutions, respectively. The present study demonstrates that the instillation of sericin solution has a potent effect in promoting wound healing and wound-size reduction in rats, probably caused by increasing cell movement and proliferation.
Biological & Pharmaceutical Bulletin 06/2009; 32(5):933-6. · 1.66 Impact Factor
