Photoelectric dye-based retinal prosthesis (OUReP) as a novel type of artificial retina

We have developed the world's first novel type of artificial retina, OUReP (Okayama University Retinal Prosthesis), in which a photoelectric dye that converts light energy into electric potential is covalently bonded to the surface of a polyethylene thin film as an insulator. The receptor that absorbs light and the output device that generates displacement current to stimulate nearby neurons are integrated in a sheet of thin film. It has become possible to measure the surface potential of the artificial retina OUReP using a Kelvin probe that measures the surface potential of semiconductors. When light is turned on and off to the artificial retina OUReP, the surface potential changes rapidly. As the light intensity is increased, the potential change on the surface of the artificial retina becomes larger. As for safety, the artificial retina OUReP was not toxic in all tests for biological evaluation of medical devices. As for efficacy, the artificial retina OUReP was implanted under the retina by vitreous surgery in monkey eyes which had chemically-induced macular degeneration with photoreceptor cell loss. Over the next 6 months, retinal detachment did not occur during the course, and the artificial retina was in contact with the retinal tissue. The amplitude of the visual evoked potential attenuated by macular degeneration recovered 1 month after implantation of the artificial retina, and the recovery of amplitude was maintained until 6 months after the implantation. By using multielectrode array-mounted dish recording system, it has been proved that action potential spikes are induced when the artificial retina is placed on degenerative retinal tissue of retinal dystrophic rats or mice and exposed to light, which is used as an index of the effectiveness of the artificial retina. We have established manufacturing and quality control of the device in a clean room facility, proved the safety and efficacy, and are preparing for first-in-human investigator-initiated clinical trials

Glass transition temperature of dried lens tissue pretreated with trehalose, maltose, or cyclic tetrasaccharide

[PURPOSE] Glass transition temperature is a main indicator for amorphous polymers and biological macromolecules as materials, and would be a key for understanding the role of trehalose in protecting proteins and cells against desiccation. In this study, we measured the glass transition temperature by differential scanning calorimetry of dried lens tissues as a model of a whole biological tissue to know the effect of pretreatment by trehalose and other sugars. [METHODS] Isolated porcine lenses were incubated with saline, 100 or 1000 mM concentration of trehalose, maltose, or cyclic tetrasaccharide dissolved in saline at room temperature for 150 minutes. The solutions were removed and all samples were dried at room temperature in a desiccator until no weight change. The dried tissues were ground into powder and placed in a measuring pan for differential scanning calorimetry. [RESULTS] The glass transition temperature of the dried lens tissues, as a mean and standard deviation, was 63.0 ± 6.4°C (n = 3) with saline pretreatment; 53.0 ± 0.8°C and 56.3 ± 2.7°C (n = 3), respectively, with 100 and 1000 mM trehalose pretreatment; 56.0 ± 1.6°C and 55.8 ± 1.1°C (n = 3), respectively, with 100 and 1000 mM maltose pretreatment; 60.0 ± 8.8°C and 59.2 ± 6.3°C (n = 3), respectively, with 100 and 1000 mM cyclic tetrasaccharide pretreatment. The glass transition temperature appeared lower, although not significantly, with trehalose and maltose pretreatments than with saline and cyclic tetrasaccharide pretreatments (P > 0.05, Kruskal-Wallis test). The glass transition temperature of the dried lens tissues with trehalose pretreatment appeared more noticeable on the thermogram, compared with other pretreatments. [CONCLUSIONS] The glass transition temperature was measured for the first time in the dried lens tissues as an example of a whole biological tissue and might provide a basis for tissue preservation in the dried condition

Behavior tests and immunohistochemical retinal response analyses in RCS rats with subretinal implantation of Okayama-University-type retinal prosthesis

We have developed a photoelectric dye-coupled polyethylene film as a prototype of retinal prosthesis, which we named Okayama University-type retinal prosthesis. The purposes of this study are to conduct behavior tests to assess vision in Royal College of Surgeons (RCS) rats that underwent subretinal implantation of the dye-coupled film and to reveal retinal response to the dye-coupled film by immunohistochemistry. Polyethylene films were made of polyethylene powder at refined purity, and photoelectric dyes were coupled to the film surface at higher density compared with the prototype. Either dye-coupled film or dye-uncoupled plain film used as a control was implanted subretinally from a scleral incision in both eyes of an RCS rat at 6 weeks of the age. Behavior tests 2, 4, 6, and 8 weeks after implantation were conducted by observing head turning or body turning in the direction consistent with clockwise or counterclockwise rotation of a black-and-white-striped drum around a transparent cage housed with the rat. After the behavior tests at 8 weeks, rats' eyes were enucleated to confirm subretinal implantation of the films and processed for immunohistochemistry. In the behavior tests, the number of head turnings consistent with the direction of the drum rotation was significantly larger in RCS rats with dye-coupled- compared with plain-film implantation [P < 0.05, repeated-measure analysis of variance (ANOVA), n = 7]. The number of apoptotic neurons was significantly smaller in eyes with dye-coupled- compared with plain-film implantation (P < 0.05, Mann-Whitney U test, n = 6). In conclusion, subretinal implantation of photoelectric dye-coupled films restored vision in RCS rats and prevented the remaining retinal neurons from apoptosis

Modelling the visual response to an OUReP retinal prosthesis with photoelectric dye coupled to polyethylene film

Objective. Retinal prostheses have been developed to restore vision in blind patients suffering from diseases like retinitis pigmentosa. Approach. A new type of retinal prosthesis called the Okayama University-type retinal prosthesis (OUReP) was developed by chemically coupling photoelectric dyes to a polyethylene film surface. The prosthesis works by passively generating an electric potential when stimulated by light. However, the neurophysiological mechanism of how OUReP stimulates the degenerated retina is unknown. Main results. Here, we explore how the OUReP affects retinal tissues using a finite element model to solve for the potential inside the tissue and an active Hodgkin-Huxley model based on rat vision to predict the corresponding retinal bipolar response. Significance. We show that the OUReP is likely capable of eliciting responses in retinal bipolar cells necessary to generate vision under most ambient conditions

Approach for combining physical properties and sensibility for pleasant beverage can-opening sound

The sound quality of consumer products has recently become an important feature, receiving much attention in the fields of engineering and manufacturing. The sound could add value to the product in the way that it meets the interests and preferences of consumers in a wide range of fields. The present study deals with the sound emitted from beverage cans when lifting the tab of the can end to open it before drinking. With a view toward finding the characteristics of sound that have a sense of ease and certainty for the consumer when opening a beverage can, we introduce the semantic differential method for the subjective assessment of sounds of various cans. We then perform waveform analyses in both time and frequency domains to determine the physical properties of the desirable sounds. Finally, we successfully correlate the texture factor with the duration of the tearing sound, which may be a new way to design cans with pleasant sounds. © 2015 Elsevier Ltd. All rights reserved

Step-by-Step Procedure to Test Photoelectric Dye-Coupled Polyethylene Film as Retinal Prosthesis to Induce Light-Evoked Spikes in Isolated Retinal Dystrophic Tissue of rd1 Mice

Purpose: Multielectrode array recording for electric activity in cardiac and neuronal cells has been developed as preclinical tests for drug screening. This study aims to establish an in vitro assay system, using the multielectrode array, to record light-evoked spikes in isolated degenerative retinal tissues of retinal dystrophic rd1 mouse, as a preclinical test to examine the efficacy of photoelectric dye-coupled thin film retinal prosthesis. Methods: Light-evoked spike response was tested for 1 min at first step in the isolated degenerative retinal tissue of retinal dystrophic rd1 mouse only on the multielectrode array, tested in the same retinal tissue overlain with a plain control film for light-off and light-on 10 min each at second step, and tested in the same tissue overlain with a dye-coupled film at third step. The retinal tissues which showed light-evoked response at first or second step were not used for evaluation at third step. Results: Residual light-evoked spikes were recorded at first or second step in 18 of 35 retinal tissues (51%) at 6 weeks of the age in rd1 mice, 16 of 44 tissues (36%) at 7 weeks, and 10 of 39 tissues (25%) at 8 weeks. At third step, light-evoked spikes were recorded with dye-coupled films in 8 of 17 retinal tissues (47%) at 6 weeks, 10 of 28 tissues (35%) at 7 weeks, and 8 of 29 tissues (27%) at 8 weeks. Conclusion: A step-by-step procedure with internal control was established to measure light-evoked spikes by the multielectrode array in the isolated degenerative retinal tissue to evaluate photoelectric dye-coupled thin films. This preclinical study would present one line of evidence for the efficacy of photoelectric dye-coupled thin film retinal prosthesis towards a first-in-human clinical trial

Photoelectric Dye, NK-5962, as a Potential Drug for Preventing Retinal Neurons from Apoptosis: Pharmacokinetic Studies Based on Review of the Evidence

NK-5962 is a key component of photoelectric dye-based retinal prosthesis (OUReP). In testing the safety and efficacy, NK-5962 was safe in all tests for the biological evaluation of medical devices (ISO 10993) and effective in preventing retinal cells from death even under dark conditions. The long-term implantation of the photoelectric dye-coupled polyethylene film in the subretinal space of hereditary retinal dystrophic (RCS) rats prevented neurons from apoptosis in the adjacent retinal tissue. The intravitreous injection of NK-5962 in the eyes of RCS rats, indeed, reduced the number of apoptotic cells in the retinal outer nuclear layer irrespective of light or dark conditions. In this study, we reviewed the in vitro and in vivo evidence of neuroprotective effect of NK-5962 and designed pharmacokinetic experiments. The in vitro IC50 of 1.7 μM, based on the protective effect on retinal cells in culture, could explain the in vivo EC50 of 3 μM that is calculated from concentrations of intravitreous injection to prevent retinal neurons from apoptosis. Pharmacokinetics of NK-5962 showed that intravenous administration, but not oral administration, led to the effective concentration in the eye of rats. NK-5962 would be a candidate drug for delaying the deterioration of retinal dystrophy, such as retinitis pigmentosa

Studies on Silage-Making XVII : The Influence of Level of Fertilization to Forage Crops on the Quality of Silage

イタリアンライグラスに対して,10アールあたり窒素量を6kg(少肥),12kg(中肥または標肥),18kg(多肥),24kg(過肥)の4水準に施肥した場合,生草の成分ならびにこれでサイレージをつくった場合,その発酵的品質にどのような影響を与えるかを知るため実験を行なった. その結果の要約はつぎのようである. 1)いずれの生育期においても,粗タンパク質の含量は,単位面積あたりの窒素施肥量の多くなるにつれて高くなった. 2)窒素施肥量が高くなるにつれて,水溶性炭水化物の含量は低くなった. 粗タンパク質と可溶性炭水化物含量間には,負の相関,r=-0.85が見出された. 出穂初期の試料の窒索含量と還元糖含量間にも有意な負の相関r=-0.98が見出された. 3)カロチン含量は,窒素施肥量を多くするにつれて高くなった. 4)サイレージの発酵的品質は,少肥区サイレージ70点,中肥区サイレージ58点,多肥区サイレージ23点で,窒素施肥量が多くなるにつれて,品質の低下することが認められた. 5)サイレージの有機物の消化率は,区間に大きな差はなかったが,粗タンパク質の消化率は,窒素施肥量が多くなるにつれて,高くなった. 6)サイレージのカロチン含量は,多肥区サイレージが高かったが,埋蔵間の保存率は窒素施肥量の高いものが低かった. 7)簡易し好試験の緒果は,品質のよいものほど,単位時間あたりの乾物摂取量が高かった. 8)サイレージ養分としての単位面積あたりの養分収量は,施肥量の高いものほど,DCP,TDNの収量が高かった

Vision evaluation by functional observational battery, operant behavior test, and light/dark box test in retinal dystrophic RCS rats versus normal rats

BACKGROUND: Vision plays a key role in some behavior tests for rats. Okayama University-type retinal prosthesis (OUReP) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to assess vision in retinal dystrophic (RCS) rats, in comparison with normal rats, by selected behavior tests. We also examined whether the tests could detect vision changes in RCS rats with dye-coupled film implantation. METHODS: Data sets were 5 normal rats, 4 untreated RCS rats, 7 RCS rats with dye-coupled films implanted at the age of 7 weeks after excluding unsuccessful implantation at autopsy. Behavior tests chosen were landing foot splay and visual forelimb-placing response in the menu of functional observational battery, operant-conditioning lever-press response and light/dark box test. RESULTS: Normal visual placing response was significantly less frequent in untreated RCS rats at the age of 9 and 11 weeks, compared with normal rats (P = 0.0027, chi-square test) while normal response was significantly more frequent at the age of 9 weeks in RCS rats with dye-coupled film implantation, compared with untreated RCS rats (P = 0.0221). In operant-conditioning lever-press test, the correct response rate was significantly lower in untreated RCS rats than in normal rats at the age of 9 weeks (P CONCLUSIONS: Behavior tests of functional observational battery, operant-conditioning lever-press response and light/dark box test discriminated vision between normal rats and RCS rats. The visual placing response and operant-conditioning lever-press test might have sensitivity to detect vision recovery in RCS rats with OUReP implantation