Naruhiro Ishida

Abnormal protein profiles in tears with dry eye syndrome

PURPOSE To verify the hypothesis that protein concentrations, such as lactoferrin, epidermal growth factor (EGF), and aquaporin 5 (AQP5), in tears are abnormal in patients with dry eye. DESIGN Prospective case-control study. METHODS One hundred three dry eye patients were divided into three groups: dry eye not associated with the Sjögren syndrome (non-SS; n = 71), Sjögren syndrome (SS; n = 23), and Stevens-Johnson syndrome (SJS; n = 9). Sixteen normal control subjects were also checked. The concentrations of lactoerrin, EGF, and AQP5 were measured by enzyme-linked immunosorbent assay. RESULTS The concentration of lactoferrin was significantly decreased in tears of non-SS (P =.0001), SS (P =.00005), and SJS (P =.0006) patients compared with control subjects. The concentration of EGF was significantly decreased in non-SS (P =.0005), SS (P =.00002), and SJS (P =.0001) patients compared with control subjects. The concentration of AQP5 was significantly increased in tears of only SS patients (P =.01) compared with control subjects and increased in tears of only SS patients compared with non-SS patients (P =.007). CONCLUSIONS The decrease in both lactoferrin and EGF was found not only in SS patients but also in non-SS patients, indicating that tear components in dry eyes differ in their quantity and quality. Quantification of AQP5 increased only in SS patients, suggesting that AQP5 protein leaks into the tears when acinar cells of the lacrimal gland are damaged by lymphocytic infiltration.

Mos is degraded by the 26S proteasome in a ubiquitin-dependent fashion

Mos, the c‐mos proto‐oncogene product, is a key regulator of cell cycle progression. Recently, rapid turnover of Mos in an early stage of meiotic maturation of Xenopus oocytes was found to be mediated by the ubiquitin pathway, but the protease responsible for its breakdown was not identified. In the present study, we found that 35S‐labeled Mos synthesized in an in vitro transcription/translation system was degraded ATP‐ and time‐dependently by the 26S proteasome, but not by the 20S proteasome, in the presence of a ubiquitin‐ligation system. The 26S proteasome did not degrade a mutant Mos in which Ser3 was replaced by Asp3 that is metabolically stable in oocytes, indicating a similarity in the proteolytic events in vivo to those observed in vitro in the present work. This is the first demonstration that the proteasome catalyzes the ATP‐dependent degradation of a naturally occurring, short‐lived oncoprotein by the ubiquitin pathway. This finding suggests that the proteasome may regulate the intracellular stability of various oncoproteins.

Effects of prostaglandin F2α analogues on endothelin-1-induced impairment of rabbit ocular blood flow: Comparison among tafluprost, travoprost, and latanoprost

We investigated the effects of prostaglandin F(2α) (PGF(2α)) analogues on the endothelin-1 (ET-1)-induced impairment of optic nerve head (ONH) blood flow and on ET-1-induced contraction in isolated ciliary artery segments. In male rabbits, one of four PGF(2α) analogues [0.0015% tafluprost, 0.0015% 15-hydroxyl tafluprost (15-OH tafluprost), 0.005% latanoprost, or 0.004% travoprost] was topically administered at various pretreatment times before intravitreal ET-1 injection. ONH blood flow was estimated by the laser speckle method, which expresses blood velocity as a quantitative index, the squared blur rate (SBR). SBR was measured just before (baseline value) and at 30, 60, and 120 min after ET-1 injection. SBR was significantly decreased from 4.47 ± 0.20 to 3.50 ± 0.10 (78.6 ± 2.4% of baseline) at 120 min after intravitreal ET-1 injection (5 pmol/eye). The ET-1-induced decrease was almost completely prevented by tafluprost and significantly inhibited by the other three analogues. The inhibitory effect lasted longest with tafluprost, as indicated by the effective pretreatment times (tafluprost: 90, 120, or 240 min; 15-OH tafluprost: 90, but not 120 or 240 min; latanoprost and travoprost: 120, but not 240 min). In vitro, the effects of PGF(2α) analogues on ET-1-induced contractions in male rabbit ciliary arteries were evaluated using an isometric tension recording system. Tafluprost, latanoprost, travoprost, and 15-OH tafluprost concentration-dependently relaxed the 10 nM ET-1-induced ciliary artery contraction. Improvement of the ocular circulation may be superior with tafluprost than with the other PGF(2α) analogues. The underlying mechanism may involve relaxation of ocular resistance vessels.

Ocular Hypotensive Effects of Anti-Glaucoma Agents in Mice

PURPOSE To evaluate the ocular hypotensive effects induced by topical application of anti-glaucoma agents in mice. METHODS Representative drugs (latanoprost and tafluprost [for prostanoid FP receptor agonists], timolol [for beta-adrenoceptor antagonists], dipivefrin [for alphabeta-adrenoceptor agonists], dorzolamide [for carbonic anhydrase inhibitors], pilocarpine [for muscarinic receptor agonists], bunazosin [for alpha(1)-adrenoceptor antagonists], or brimonidine [for alpha(2)-adrenoceptor agonists]) were used as anti-glaucoma agents; each one being topically applied once in a given male ddY mouse. Intraocular pressure (IOP) was measured using the microneedle method under general anesthesia. IOP was measured before, and at 1, 2, 3, and 4 h after administration of each drug. The contralateral eyes were untreated. At the each time point, the induced IOP reduction was evaluated by calculating the difference in IOP between the treated and untreated eyes in one and the same mouse. RESULTS All of the evaluated anti-glaucoma agents reduced IOP in mice. The 2 prostanoid FP receptor agonists, the beta-adrenoceptor antagonist, and the alphabeta-adrenoceptor agonist began significantly to reduce IOP 2 h after their administration, and mostly induced a long-lasting IOP reduction. The alpha(1)-adrenoceptor antagonist, the alpha(2)-adrenoceptor agonist, the muscarinic receptor agonist, and the carbonic anhydrase inhibitor began reducing the IOP within 1 h after their administration, but their effects waned fairly quickly (the IOP reductions being lost by 3 h after their administration). Concomitant administration of timolol and tafluprost or of dorzolamide and tafluprost induced a significantly greater IOP reduction than that induced by either of the individual components. CONCLUSIONS In this study, all the anti-glaucoma agents tested had apparent ocular hypotensive effects in mice. Our data suggest that the mouse may be a useful animal for the evaluation of the pharmacological effects of agents with various anti-glaucoma mechanisms, and for the evaluation of the enhanced ocular hypotensive effects that may be induced by the concomitant use of 2 anti-glaucoma agents.

Effects of Repeated Administrations of Tafluprost, Latanoprost, and Travoprost on Optic Nerve Head Blood Flow in Conscious Normal Rabbits

PURPOSE The aim of this study was to evaluate and compare the effects of repeated administrations of three prostaglandin F(2alpha) analogs (tafluprost, latanoprost, and travoprost) on optic nerve head (ONH) blood flow in normal rabbits. METHODS Male Dutch rabbits were housed under a 12-h light-dark cycle for use in this study. A quantitative index of blood flow, the squared blur rate (SBR), was determined using laser speckle flowgraphy. Saline, 0.0015% tafluprost, 0.005% latanoprost, or 0.004% travoprost (each 50 microL) was topically administered into the left eye once daily for 28 days. ONH blood flow was measured before the start at the course of treatment (baseline), and on day 14 and/or day 28 [measurements being made at 0, 30, and/or 60 min after drugs application on day 14 and/or day 28]. Heart rate was also measured at these time points. RESULTS Tafluprost, latanoprost, and travoprost each increased the ONH blood flow at all measurement points on day 14 and/or day 28. The 0 min SBR value on day 14 was greater than the baseline SBR value by 8.7% + or - 4.4% for tafluprost and by 5.8% + or - 1.7% for latanoprost. The 0 min SBR value on day 28 was greater than the baseline SBR value by 11.9% + or - 3.9% for tafluprost, by 7.2% + or - 4.3% for latanoprost, and by 6.7% + or - 3.5% for travoprost. The increasing state of the ONH blood flow continued within 60 min after a topical administration of tafluprost, latanoprost, or travoprost. Tafluprost, latanoprost, and travoprost did not change heart rate (vs. the baseline value) at any measurement points. CONCLUSIONS Repeated topical administration of any of the three prostaglandin F(2alpha) analogs increased ONH blood flow in rabbits, without changing heart rate. The increase in ONH blood flow induced by tafluprost was greater than that induced by latanoprost (P = 0.086) or travoprost (P = 0.037) at 60 min on day 28.

The protective effects of SA3443, a novel cyclic disulfide, on chronic liver injuries in rats

The effects of (4R)-hexahydro-7,7-dimethyl-6-oxo-1,2,5-dithiazocine-4- carboxylic acid (SA3443), a novel cyclic disulfide compound, on the development of chronic liver injury were studied in rats, using two types of models, carbon tetrachloride (CCl4)-induced chronic liver injury and heterologous serum (swine serum)-induced liver fibrosis. SA3443 (30-100 mg/kg, p.o.) significantly suppressed increases in serum transaminase and alkaline phosphatase activity induced by CCl4-treatment for 10 weeks. This compound also inhibited increases in hepatic lipids and hydroxyproline content in CCl4-treated rats. In the histopathological studies, treatment with SA3443 resulted in a decrease in the degree of hepatic necrosis, fibrosis and steatosis. On the other hand, 8-weeks treatment with swine serum revealed hepatic fibrosis without appearance of necrosis or fatty accumulation. In this model, SA3443 (30 mg/kg, p.o.) reduced the hepatic hydroxyproline level, and diminished the formation of connective tissue in the liver. These findings indicate that SA3443 protects the liver against chronic liver injuries induced by CCl4 and heterogeneous serum.

Effects of bunazosin hydrochloride on ciliary muscle constriction and matrix metalloproteinase activities.

Purpose:To clarify the mechanism by which bunazosin hydrochloride (BZ), a selective &agr;1-adrenoceptor antagonist, increases uveoscleral outflow. Methods:The effects of BZ on matrix metalloproteinase (MMP) activities in cultured monkey ciliary muscle cells, and on phenylephrine hydrochloride-induced constriction in bovine ciliary muscles, were examined. Also, the possible additive ocular hypotensive effects of BZ and latanoprost (LP) were evaluated in ocular normotensive monkeys. Results:Although BZ at 10−7 to 10−5 M did not increase MMP-2, -3, and -9 activities in the culture medium of ciliary muscle cells, BZ at 10−7 to 10−5 M inhibited phenylephrine hydrochloride-induced constriction in ciliary muscles. The maximal reduction in intraocular pressure of concomitant administration of BZ and LP was greater than that of BZ alone and tended to be greater than that of LP alone. Conclusion: These findings, in normotensive monkeys, indicate that the mechanism whereby BZ increases uveoscleral outflow is independent of an effect on MMPs and is partly due to relaxation of the ciliary muscle. This effect is different from that of LP, which might help to explain the finding that topical concomitant administration of BZ and LP increased AUC(0–6h) value (IOP reduction) to 201% and 145% of BZ and LP given alone, respectively.

Ocular hypotensive effect of tafluprost in latanoprost low-responder cynomolgus monkeys.

PurposeTo determine the proportion of latanoprost low-responders among cynomolgus monkeys, and to evaluate the switching efficacy from latanoprost to tafluprost in latanoprost low-responder monkeys. MethodsThirty-nine ocular normotensive monkeys were used in this study. Latanoprost low-responders were detected using a 2-step evaluation procedure. In the first step, the response to single administration of latanoprost was investigated in all monkeys. In the second step, the response to 7-day administration of latanoprost was evaluated in screened monkeys. We defined latanoprost low-responders as any monkey that showed intraocular pressure (IOP) reduction of 1 mm Hg or less during the 7-day treatment. Switching efficacy from latanoprost to tafluprost was then evaluated in a 3-phase switching study. Latanoprost was topically administered for about 1 week in phases 1 and 3, with tafluprost being topically administered for about 1 week in phase 2. ResultsEleven monkeys were “latanoprost low-responders.” The maximal IOP reduction exhibited by these low-responders in the second step of the evaluation was 0.5±0.2 mm Hg (mean±SEM) during saline treatment and 0.8±0.2 mm Hg during latanoprost treatment. In the 3-phase switching study, the maximal IOP reductions were: 0.4±0.2 mm Hg in phase 1 (latanoprost), 2.4±0.3 mm Hg in phase 2 (tafluprost), and 0.5±0.2 mm Hg in phase 3 (latanoprost). ConclusionsLatanoprost low-responders exist among cynomolgus monkeys. Switching from latanoprost to tafluprost reduced IOP, and tafluprosts IOP-lowering effect disappeared after switching back to latanoprost in the latanoprost low-responder monkeys. These results suggested that tafluprost might be effective for latanoprost nonresponder patients.

OCT evaluation of neuroprotective effects of tafluprost on retinal injury after intravitreal injection of endothelin-1 in the rat eye.

PURPOSE To determine whether optical coherence tomography (OCT) is a useful technique to monitor retinal damage and to evaluate the neuroprotective effect of topical tafluprost in a rat model of intravitreal endothelin-1 (ET-1) injection. METHODS A single intravitreal injection of ET-1 (0.2-200 pmol/eye) was performed in one eye. Optical coherence tomography imaging was performed until 2 weeks after ET-1 injection. Subsequently, an intravitreal injection of ET-1 (20 pmol/eye) was performed in one eye of each rat, which was followed by topical instillation of tafluprost or saline once daily for 4 weeks. Optical coherence tomography imaging was performed until 4 weeks after ET-1 injection. After the last OCT session, retinal ganglion cells (RGCs) were retrogradely labeled with Fluorogold. RESULTS Endothelin-1 at doses of 20 to 200 pmol/eye caused a significant decrease in inner retinal thickness, whereas ET-1 at doses of 0.2 to 5 pmol/eye did not. The inner retinal thickness at 2 weeks postinjection was strongly correlated with Fluorogold-labeled RGC counts in the central retina (r = 0.92, P < 0.001). The inner retina of eyes treated with tafluprost was significantly thicker than eyes treated with saline at 1 and 2 weeks (P = 0.038 and P = 0.045, respectively). Fluorogold-labeled RGC counts in the central retina of eyes treated with tafluprost were significantly greater than in eyes treated with saline (P = 0.03). CONCLUSIONS Optical coherence tomography is useful for monitoring inner retinal damage in a rat model of intravitreal ET-1 injection. Daily topical administration of tafluprost may be protective against ET-1-induced retinal injury in the rat.