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Human retinal organoid transplantation can potentially restore vision in patients with degenerative retinal diseases. How the recipient retina regulates the maturation, fate specification, and migration of transplanted organoid cells is unknown. We transplanted human retinal organoid-derived cells into photoreceptor-deficient mice, conducted histology and single-cell RNA sequencing analyses, and observed two main classes of graft-derived cells. The first class consisted of retinal astrocytes and brain/spinal cord-like neural precursors, absent or rare in cultured organoids, that migrated into all recipient retinal layers and traveled long distances. The second class consisted of retinal progenitor-derived cells, including rods and cones, that remained in the subretinal space and matured more rapidly than photoreceptors in culture. These data suggest that the recipient subretinal space promotes the maturation of transplanted photoreceptors while inducing or expanding migratory cell populations that are not normally derived from retinal progenitors. These findings have important implications for cell-based treatment of retinal diseases.

OBJECTIVES: Cone photoreceptor transplantation is a potential treatment for macular diseases. The optimal conditions for cone transplantation are poorly understood, partly because of the scarcity of cones in donor mice. To facilitate allogeneic cone photoreceptor transplantation studies in mice, we aimed to create and characterize a donor mouse model containing a cone-rich retina with a cone-specific enhanced green fluorescent protein (EGFP) reporter. METHODS: We generated OPN1LW-EGFP/NRL(−/−) mice by crossing NRL(−/−) and OPN1LW-EGFP mice. We characterized the anatomical phenotype of OPN1LW-EGFP/NRL(−/−) mice using multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, immunohistology, and transmission electron microscopy. We evaluated retinal function using electroretinogram (ERG), including 465 and 525 nm chromatic stimuli. Retinal sheets and cell suspensions from OPN1LW-EGFP/NRL(−/−) mice were transplanted subretinally into immunodeficient Rd1 mice. RESULTS: OPN1LW-EGFP/NRL(−/−) retinas were enriched with OPN1LW-EGFP(+) and S-opsin(+) cone photoreceptors in a dorsal-ventral distribution gradient. Cone photoreceptors co-expressing OPNL1W-EGFP and S-opsin significantly increased in OPN1LW-EGFP/NRL(−/−) compared to OPN1LW-EGFP mice. Temporal dynamics of rosette formation in the OPN1LW-EGFP/NRL(−/−) were similar as the NRL(−/−) with peak formation at P15. Rosettes formed preferentially in the ventral retina. The outer retina in P35 OPN1LW-EGFP/NRL(−/−) was thinner than NRL(−/−) controls. The OPN1LW-EGFP/NRL(−/−) ERG response amplitudes to 465 nm stimulation were similar to, but to 535 nm stimulation were lower than, NRL(−/−) controls. Three months after transplantation, the suspension grafts showed greater macroscopic degradation than sheet grafts. Retinal sheet grafts from OPN1LW-EGFP/NRL(−/−) mice showed greater S-opsin+ cone survival than suspension grafts from the same strain. CONCLUSIONS: OPN1LW-EGFP/NRL(−/−) retinae were enriched with S-opsin(+) photoreceptors. Sustained expression of EGFP facilitated the longitudinal tracking of transplanted donor cells. Transplantation of cone-rich retinal grafts harvested prior to peak rosette formation survived and differentiated into cone photoreceptor subtypes. Photoreceptor sheet transplantation may promote greater macroscopic graft integrity and S-opsin(+) cone survival than cell suspension transplantation, although the mechanism underlying this observation is unclear at present. This novel cone-rich reporter mouse strain may be useful to study the influence of graft structure on cone survival.

The use of model systems that are capable of robust, spontaneous retina regeneration has allowed for the identification of genetic pathways and components that are required for retina regeneration. Complemented by mouse models in which retina regeneration can be induced after forced expression of key factors, altered chromatin accessibility, or inhibition of kinase/signaling cascades, a clearer picture of the key regulatory events that control retina regeneration is emerging. In all cases, Müller glia (MG) serve as an adult retinal stem cell that must be reprogrammed to allow for regeneration, with the end goal being to understand why regenerative pathways are blocked in mammals, but spontaneous in other vertebrates such as zebrafish. miRNAs have emerged as key gene regulatory molecules that control both development and regeneration in vertebrates. Here, we focus on a small subset of miRNAs that control MG reprogramming during retina regeneration and have the potential to serve as therapeutic targets for treatment of visual disorders and damage.

PurposeShort-term improvements in retinal anatomy are known to occur in preclinical models of photoreceptor transplantation. However, correlative changes over the long term are poorly understood. We aimed to develop a quantifiable imaging biomarker grading scheme, using non-invasive multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, to enable serial evaluation of photoreceptor transplantation over the long term.MethodsYellow-green fluorescent microspheres were transplanted into the vitreous cavity and/or subretinal space of C57/BL6J mice. Photoreceptor cell suspensions or sheets from rhodopsin-green fluorescent protein mice were transplanted subretinally, into either NOD.CB17-Prkdcscid/J or C3H/HeJ-Pde6brd1 mice. Multimodal cSLO imaging was performed serially for up to three months after transplantation. Imaging biomarkers were scored, and a grade was defined for each eye by integrating the scores. Image grades were correlated with immunohistochemistry (IHC) data.ResultsMultimodal imaging enabled the extraction of quantitative imaging biomarkers including graft size, GFP intensity, graft length, on-target graft placement, intra-graft lamination, hemorrhage, retinal atrophy, and peri-retinal proliferation. Migration of transplanted material was observed. Changes in biomarker scores and grades were detected in 13/16 and 7/16 eyes, respectively. A high correlation was found between image grades and IHC parameters.ConclusionsSerial evaluation of multiple imaging biomarkers, when integrated into a per-eye grading scheme, enabled comprehensive tracking of longitudinal changes in photoreceptor cell grafts over time. The application of systematic multimodal in vivo imaging could be useful in increasing the efficiency of preclinical retinal cell transplantation studies in rodents and other animal models.

Purpose Short-term improvements in retinal anatomy are known to occur in preclinical models of photoreceptor transplantation. However, correlative changes over the long term are poorly understood. We aimed to develop a quantifiable imaging biomarker grading scheme, using noninvasive multimodal confocal scanning laser ophthalmoscopy (cSLO) imaging, to enable serial evaluation of photoreceptor transplantation over the long term. Methods Photoreceptor cell suspensions or sheets from rhodopsin-green fluorescent protein mice were transplanted subretinally, into either NOD.CB17-Prkdcscid/J or C3H/HeJ-Pde6brd1 mice. Multimodal cSLO imaging was performed serially for up to three months after transplantation. Imaging biomarkers were scored, and a grade was defined for each eye by integrating the scores. Image grades were correlated with immunohistochemistry (IHC) data. Results Multimodal imaging enabled the extraction of quantitative imaging biomarkers including graft size, GFP intensity, graft length, on-target graft placement, intra-graft lamination, hemorrhage, retinal atrophy, and periretinal proliferation. Migration of transplanted material was observed. Changes in biomarker scores and grades were detected in 14/16 and 7/16 eyes, respectively. A high correlation was found between image grades and IHC parameters. Conclusions Serial evaluation of multiple imaging biomarkers, when integrated into a per-eye grading scheme, enabled comprehensive tracking of longitudinal changes in photoreceptor cell grafts over time. The application of systematic multimodal in vivo imaging could be useful in increasing the efficiency of preclinical retinal cell transplantation studies in rodents and other animal models. Translational relevance By allowing longitudinal evaluation of the same animal over time, and providing quantifiable biomarkers, non-invasive multimodal imaging improves the efficiency of retinal transplantation studies in animal models. Such assays will facilitate the development of cell therapy for retinal diseases.

Ionic polychloroprene rubber was prepared by reaction of poly-chloroprene rubber with acetyl sulfate at different times (2, 4, 6, 8, 12 and 15 h) and temperatures (25, 35 and 45°C). The product was characterized by IR and NMR spectroscopic methods. The modification increased with increasing reaction time and temperature. The modified rubber had lower intrinsic viscosity in chloroform and higher values of tensile strength, modulus and energy to break.

The iron fortification of food in Sweden, the highest in the world, was withdrawn 1st January 1995, because the effect upon target groups was considered to be uncertain. We wanted to study the effect of such a dietary experiment.Comparative cross over study.Out patient service and Blood Bank.Sixteen men aged 24-73 y on maintenance phlebotomy after treatment for iron overload. One was excluded because of inflammatory disease.Quantitative phlebotomy with serial measurements of Hb conc., % transferrin saturation and serum ferritin concentration.Iron absorption was measured by phlebotomy during two periods, with and without iron fortification. 1 g Hb = 3.4 mg Fe.Iron absorption was significantly reduced (P0.001) when iron fortification was withdrawn from a mean of 4.27 +/- 1.2 to 3.63 +/- 1.1 mg/d. The difference of 0.65 mg/d (95% c.i. 0.32-0.97) corresponds to the fraction of iron derived from fortification. Intervals between donations had to be extended from 59 +/- 15 to 69 +/- 17 d (P0.01) to avoid induction of iron deficiency anemia. The iron content of the fortified diet averaged 15.4 mg/d, of which the fortified fraction constituted 4.1 mg/d (27%). The relative bioavailability of carbonyl iron used as fortificant was 38%.The relative bioavailability of carbonyl iron used as fortificant was higher than previously reported. Target groups such as menstruating females will probably be affected by a higher prevalence of iron deficiency when food is no longer fortified. People with genetic hemochromatosis will accelerate into clinical disease at a slower rate.

Surface modification of Kapton polyimide film (325 nm thick) by means of chromic acid and perchloric acid at different times and temperatures has been carried out. The contact angle of water decreased from 82 to 55° and the surface energy increased accordingly from 26 to 45 mJ/m2 with times of etching by chromic acid up to 45 min at 33°C. Etching at higher temperatures increased the surface energy. Chromic acid was more effective than perchloric acid. IR and XPS studies indicated multiple bonding and generation of poler groups on the surface. The peak at 1778 cm-1 due to the imide group decreased on acid etching. The O/C ratio increased and the N/C ratio decreased. The peel strength of the joint polyimide film/copper film/epoxy adhesive/aluminium sheet increased about two-fold on modification of the polyimide (PI) film at 33°C for 45 min, although the changes were marginal for the PI film/silicone rubber/PI film joint. The peel strength is a function of the time and temperature of etching.

Analytical Chemistry Division, CSIR-National Metallurgical Laboratory, Jamshedpur-831 007, Jharkhand, India E-mail : konar@nmlindia.org A wet chemical method of total iron estimation in ilmenite sample has been reported. The method is fast, accurate, economic, analyst friendly and compares well with the existing methods. It does not require silica separation prior to iron estimation.

An amplification method has been described for the determination of chromium in low alloy steel samples. The well-known Leipert reaction has been coupled with a precipitate exchange reaction between lead iodate and chromium(III)–EDTA complex for amplification. Chromium is determined indirectly by determinig the liberated iodine and the detection of chromium is amplified twelvefold.

The contact angles and surface energies have been determined for silicone rubber functionalized with amide group and EPDM rubber modified with sulfonic acid and maleic anhydride. The functionalization of the polymers decreases the equilibrium contact angles of water and formamide with an increase in the surface energy. The changes in the surface properties are due to the changes in the concentration of the polar groups as measured by IR spectroscopy. The lap shear measurement on joints of silicone and EPDM rubber indicates an increased strength on modification. © 1996 John Wiley & Sons, Inc.

The influence of cations and anions of the adhesion promoters on the interface between brass-coated steel cord and natural rubber skim compounds has been studied by employing Auger electron spectroscopy and X-ray photoelectron spectroscopy at three different etching times. Cobalt stearate, cobalt boroacylate and nickel boroacylate have been used as organometallic adhesion promoters. The atomic concentrations of sulfur and carbon decreased, while those of copper and zinc increased significantly with etching times. Cobalt/nickel was only found at higher etching times. Cobalt boroacylate increased the atomic concentration of copper, zinc and sulfur with the formation of CuxS and ZnS on the top two layers more than the nickel boroacylate. The sulfidation reaction was, however, only partial in the presence of cobalt stearate, and ZnO was observed in the top layer. The atomic concentrations of copper and zinc were also much lower than those of the system containing cobalt boroacylate. A model, based on the results, is proposed to show the difference in activity of the cations and anions.

Surface energy of EPDM, silicone rubber, and their 50 : 50 (by weight) blend during aging was determined by contact angle measurement using water and formamide as the probe liquids. The surface energy increases initially with aging time. The results are explained on the basis of the polar component of the surface energy. Blending offers a good degree of protection toward aging of EPDM rubber. The generation of polar groups during aging is confirmed by IR and ESCA investigations. © 1995 John Wiley & Sons, Inc.

The surface energy and thermodynamic work of adhesion of polyethylene grafted with triallyl cyanurate in the presence of an electron beam have been determined. The surface energy increased with the grafting level and with the irradiation dose up to 10 Mrad. A similar trend was observed with the work of adhesion. The changes in these surface properties were correlated with the concentration of the polar groups as measured by IR (infrared) spectroscopy and ESCA (electron spectroscopy for chemical analysis) studies.

Low-density polyethylene (LDPE) has been functionalized in the bulk through dicumyl peroxide (DCP)-initiated grafting of dibutyl maleate (DBM) and vinyltrimethoxysilane (VTMO) in the temperature range from 140 to 200°C. The functionalized surfaces have been characterized through contact angle and contact-angle hysteresis measurements as well as through ESCA studies. The degree of grafting has been determined by infrared spectrophotometry. From the ESCA patterns of the modified polymers, the atomic ratios of oxygen to carbon and silicon to carbon have been calculated. Determination of an empirical relation between contact-angle hysteresis and the oxygen-carbon ratio of the functionalized polymer surfaces has been attempted. It is found that the higher the oxygen-carbon ratio, the lower the contact-angle value for polyethylene. Contact angle-hysteresis increases with increase of the degree of grafting. The total surface energy increases with grafting. The surface energy of the silane-grafted polyethylene (PEgS) is found to be the lower than that of dibutyl maleate-grafted polyethylene (PEgDBM). © 1993 John Wiley & Sons, Inc.

The synthesis of hydrotalcite-like compounds (HTlcs) containing Mg, Al and Ti using titanium-rich bauxite as one of the starting materials was described. The HT precursors and their calcined products were characterized by powder X-ray diffraction, TG-TDA, FT-IR and surface area measurements. Although the above characterization indicated the formation of hydrotalcite-like structure with good crystallinity, the presence of Ti 4? in the brucite layer was not confirmed. Calcination at 450 C gave rise mainly to poorly crystalline MgO and amorphous mixed oxides, which can be reconstructed to their original structure by exposure to an aqueous solution. The calcined sample containing titanium showed relatively high adsorption capacity for fluoride and Cr2O7 2� as compared to that without titanium.

Biosorption of Pb(II) on bael leaves (Aegle marmelos) was investigated for the removal of Pb(II) from aqueous solution using different doses of adsorbent, initial pH, and contact time. The maximum Pb loading capacity of the bael leaves was 104 mg g(-1) at 50 mg L(-1) initial Pb(II) concentration at pH 5.1. SEM and FT-IR studies indicated that the adsorption of Pb(II) occurs inside the wall of the hollow tubes present in the bael leaves and carboxylic acid, thioester and sulphonamide groups are involved in the process. The sorption process was best described by pseudo second order kinetics. Among Freundlich and Langmuir isotherms, the latter had a better fit with the experimental data. The activation energy E(a) confirmed that the nature of adsorption was physisorption. Bael leaves can selectively remove Pb(II) in the presence of other metal ions. This was demonstrated by removing Pb from the effluent of exhausted batteries.

LDPE blends of variable composition are prepared with several polymer additives, which include chromic acid-etched LDPE, polyhydroxyetherimide (PHEI), butylated silica and LDPE oxidized with phase-transferred permanganate. The strength of adhesion measured as the force required to peel off the laminated aluminium foil by 180 ° is found to be a function of time of etching, blend composition and the effective amount of polar groups on polymer-metal interface. LDPE-based additives, e.g. chromic acid oxidised LDPE and LDPE oxidised under phase transfer catalysis in benzene, promote practical adhesion by factors of 8 and 16, respectively. In the case of the silane additive there is virtually no enhancement of the peel load despite a large number of polar groups present in the blend. The results can be interpreted in terms of cohesive failure.

The fluoresence excitation and emission spectra of commercial LDPE and oxidized LDPEs using phase transferred permanganate as oxidant have been examined using solid state fluorescence spectra. The luminescent impurity species present in commercial polyethylene is found to be olefinic dione. LDPE has an emmission spectra at 330–345 nm and excitation spectra at 235 and 300–310 nm. The emission spectra of oxidized LDPEs contain two main peaks, one at 290–300 nm and the other at 330–345 nm. A comparison of the emission spectra of LDPE blends with the reference compounds, viz., stearic acid and stearone, with those of the oxidized LDPEs proves the presence of “saturated” keto groups (carbonyl in the main chain not conjugated with C = C) in oxidized LDPEs. This also enables us to find out quantitatively the amount of the keto groups present. The estimates thus obtained tally with the results of FT-IR measurements and follow the increasing order of the stability constant of the permanganate ionpair in benzene.

Hydrotalcite-like compounds (layered double hydroxides, LDHs) containing varying amounts of Al(3+), Zr(4+), and Zn(2+) or Mg(2+) in the metal hydroxide layer have been synthesized and characterized by various physicochemical methods. The adsorption behavior of uncalcined (as-synthesized) and calcined LDHs have been investigated for Cr(2)O(7)(2-) and SeO(3)(2-). The mixed oxides, obtained on calcination at 450 degrees C, exhibit high adsorption capacities for Cr(2)O(7)(2-) (1.6-2.7 meq/g) and SeO(3)(2-) (1.1-1.5 meq/g), where adsorption occurs through rehydration. Substitution of Zr(4+) in the LDHs, for either M(2+) or Al(3+) ions, increases the adsorption capacity up to 20%, thus providing an alternative way to enhance the adsorption capacity of this type of material. The high adsorption capacity of these materials could be successfully used for removal of undesirable anions from water and also for synthesis of intercalated materials with tailored acidobasicity.

Department of Chemistry, Indian Institute of Technology, Kharagpur-721 302 Manuscript received 17 July 1995, revised 3 June 1996, accepted 19 June 1996 1 : 1 charge transfer adducts of CuII and NiII biguanides with I2 have been prepared. Thermal characteristics of metal biguanides, substituted metal biguanides and their charge transfer adducts have been studied. The general features of the thermoanalytical traces are almost same except in case of iodine adducts. The evolution of iodine from the iodine adduct at appreciably lower temperature than the usual iodine compounds confirms,he formation of charge transfer complexes of iodine with the metal biguanide.

The results of 92 consecutive renal retransplantations, performed during a 5-year period in recipients with HLA-antibodies, were retrospectively analysed. The actuarial 1-year graft survival (1-y GS) was 65% for all retransplantations, as compared with 63% for first grafts in sensitized recipients. For the second (n = 56), third (n = 24) and fourth-fifth (n = 12) grafts 1-y GS was 64%, 71% and 58%, respectively. Acute rejection was the major cause of graft loss (45%). Recipients with > 3 years GS of the preceding transplant had significantly better GS at retransplantation. Also, grafts with no HLA mismatches had significantly prolonged GS. One-y GS was 78% when PRA (panel reacting antibody) was less than 50%, and 60% when PRA was more than 50%. A benefit of repeated mismatches was demonstrated in the subgroup with PRA 50%, suggesting that, in some patients, an absence of antibody response against certain antigens might be used as a basis for future deliberate mismatching.

Low-density polyethylene (LDPE) has been oxidized using phase transferred permanganate as an oxidant. The resulting surface modifications have been characterized by different methods and the consequent adhesion promotion has been characterized in terms of contact angle and peel strength measurements. From contact angle measurements using water and formamide liquid drops, reversible work of adhesion, and thence γp s and γ-d s, the contributions of polar and dispersion components, respectively, have been calculated. The polar contributions increased in each oxidized LDPE relative to untreated LDPE and the surface energies also increased appreciably. The adhesion strengths between aluminium and untreated LDPE, as well as those between aluminium and oxidized LDPEs, have been examined by peel strength measurements. We found that the adhesion strength increased about 8-28 times in the case of oxidized LDPEs. Maximum strength was observed when benzyl triphenyl phosphonium permanganate was the oxidant. Both the p...

Low density polyethylene (LDPE) has been modified by oxidative degradation with phase transferred permanganate and both the treated and untreated materials have been examined by TGA and DSC. In TGA, LDPE shows three degradation steps whereas the modified LDPEs show only two, owing to elimination of short branches during oxidation. From DSC studies it is evident that all melting endotherms contain two peaks which can be explained as resulting from the two structure forms of LDPE. There is a small difference in melting peak temperature as well as in percentage crystallinity of LDPE and modified LDPEs but a greater difference is observed in degradation pattern. While LDPE has one degradation step, modified LDPEs follow multistep degradation.

Oxidative degradation of polyethylene has been carried out with phase transferred permanganate as oxidant. The degradation products have been characterised by infrared spectroscopy in an attempt to clucidate the probable degradation mechanism. The oxidised polyethylenes are found to possess carbonyl, ether, hydroperoxy and several types of olefinic groups. Using FT-IR spectra, the quantitative determination of the different functional groups has also been carried out. While the initiation and termination steps are common to all PTC oxidations of low density polyethylene, the propagation in the tetrabutyl ammonium bromide (TBAB)-catalysed process occurs through intramolecular hydrogen abstraction and chain scission.

The object of this study was to analyse the effect of leaf leachates of four species on the sprouting behavior of rhizomes, seedling growth and diosgenin content of Costus speciosus