Air channels create a directional light signal to regulate hypocotyl phototropism.

In plants, light direction is perceived by the phototropin photoreceptors, which trigger directional growth responses known as phototropism. The formation of a phototropin activation gradient across a photosensitive organ initiates this response. However, the optical tissue properties that functionally contribute to phototropism remain unclear. In this work, we show that intercellular air channels limit light transmittance through various organs in several species. Air channels enhance light scattering in Arabidopsis hypocotyls, thereby steepening the light gradient. This is required for an efficient phototropic response in Arabidopsis and Brassica. We identified an embryonically expressed ABC transporter required for the presence of air channels in seedlings and a structure surrounding them. Our work provides insights into intercellular air space development or maintenance and identifies a mechanism of directional light sensing in plants.

Electronic Regulation of Nickel Single Atoms by Confined Nickel Nanoparticles for Energy-Efficient CO2 Electroreduction.

Modulating the electronic structure of atomically dispersed active sites is promising to boost catalytic activity but is challenging to achieve. Here we show a cooperative Ni single-atom-on-nanoparticle catalyst (NiSA/NP) prepared via direct solid-state pyrolysis, where Ni nanoparticles donate electrons to Ni(i)-N-C sites via a network of carbon nanotubes, achieving a high CO current density of 346 mA cm-2 at -0.5 V vs RHE in an alkaline flow cell. When coupled with a NiFe-based anode in a zero-gap membrane electrolyzer, the catalyst delivers an industrially relevant CO current density of 310 mA cm-2 at a low cell voltage of -2.3 V, corresponding to an overall energy efficiency of 57 %. The superior CO2 electroreduction performance is attributed to the enhanced adsorption of key intermediate COOH* on the electron-rich Ni single atoms, as well as a high density of active sites.

Van der Waals MoS2/VO2 heterostructure junction with tunable rectifier behavior and efficient photoresponse.

Junctions between n-type semiconductors of different electron affinity show rectification if the junction is abrupt enough. With the advent of 2D materials, we are able to realize thin van der Waals (vdW) heterostructures based on a large diversity of materials. In parallel, strongly correlated functional oxides have emerged, having the ability to show reversible insulator-to-metal (IMT) phase transition by collapsing their electronic bandgap under a certain external stimulus. Here, we report for the first time the electronic and optoelectronic characterization of ultra-thin n-n heterojunctions fabricated using deterministic assembly of multilayer molybdenum disulphide (MoS2) on a phase transition material, vanadium dioxide (VO2). The vdW MoS2/VO2 heterojunction combines the excellent blocking capability of an n-n junction with a high conductivity in on-state, and it can be turned into a Schottky rectifier at high applied voltage or at temperatures higher than 68 °C, exploiting the metal state of VO2. We report tunable diode-like current rectification with a good diode ideality factor of 1.75 and excellent conductance swing of 120 mV/dec. Finally, we demonstrate unique tunable photosensitivity and excellent junction photoresponse in the 500/650 nm wavelength range.

Photodynamic therapy in retinoblastoma: effects of verteporfin on retinoblastoma cell lines.

PURPOSE: In contrast to the excellent survival rates of the malignant childhood tumor retinoblastoma (RB), morbidity is high in patients with this disease because of the enucleation or loss of retinal areas caused by current bulb-saving therapies. The authors aimed to preclinically assess the effects of photochemotherapy using second-generation photochemotherapeutics as a prerequisite to develop a promising therapeutic alternative. This therapy implies intravenous application of a photosensitizer activated locally by light of the appropriate wavelength. Activation leads to the formation of free radicals, vascular occlusion, and death of affected cells in the area of irradiation. The photosensitizer verteporfin is approved for the therapy of neovascularizations, such as age-related maculopathy. METHODS: The uptake of verteporfin in RB cell lines was investigated. Established RB cell lines, an RB subline resistant to etoposide, and dissociated cells from a primary RB were incubated with verteporfin and irradiated with activating laser light. Proliferation was measured at different time points after application. RESULTS: All five RB cell lines investigated incorporated verteporfin, and nanomolar concentrations were sufficient for effective killing. At lower doses, surviving cells started to proliferate again after several days, but verteporfin 50 ng/mL and 100 J/cm(2) were sufficient for irreversible killing. High verteporfin concentrations caused cell death with little to no irradiation. Etoposide-resistant cells and primary tumor cells had a comparable susceptibility to photodynamic therapy (PDT) as established parental cell lines. CONCLUSIONS: PDT using verteporfin efficiently kills chemotherapy-resistant and nonresistant retinoblastoma cell lines and primary tumor cells in vitro, and it warrants further preclinical evaluation as a therapeutic option for the treatment of retinoblastoma.

Beta-ray brachytherapy with 106Ru plaques for retinoblastoma.

PURPOSE: A retrospective analysis of 134 patients who received (106)Ru brachytherapy for retinoblastomas (175 tumors in 140 eyes). Treatment and follow-up were analyzed with special emphasis on tumor control organ, preservation, and late complications. RESULTS: Treated tumors had a mean height and diameter of 3.7+/-1.4 mm and 5.0+/-2.8 disk diameters, respectively. The radiation dose values were recalculated according to the calibration standard recently introduced by the National Institute of Standards and Technology. The recalculation revealed a mean applied dose of 419 Gy at the sclera (SD, 207 Gy) and 138 Gy (SD, 67 Gy) at the tumor apex. The 5-year tumor control rate was 94.4%. Tumor recurrence was more frequent in eyes with vitreous tumor cell seeding or fish-flesh regression. The estimated 5-year eye preservation rate was 86.5%. Previous treatment by brachytherapy or external beam radiotherapy, as well as a large tumor diameter, were significant factors for enucleation. The radiotherapy-induced complications after 5 years of follow-up were retinopathy (22%), optic neuropathy (21%), and cataract (17%). These complications were significantly more frequent after prior brachytherapy or external beam radiotherapy. CONCLUSION: Brachytherapy using (106)Ru plaques is a highly efficient therapy with excellent local tumor control and an acceptable incidence of side effects.

De novo intraocular retinoblastoma development after chemotherapy in patients with hereditary retinoblastoma.

OBJECTIVE: Identification of incidence and risk factors for recurrence of de novo retinoblastomas after chemotherapy treatment in patients with hereditary retinoblastoma. METHODS: A retrospective, case-control study of 32 patients (50 eyes) with sporadic or familial bilateral retinoblastomas was conducted. Patients received a systemic chemotherapy regimen applying three courses of a combination of three drugs (including vincristine, etoposide, carboplatin, or cyclophosphamide) followed by additional local therapy. The primary outcome analyzed was the development of retinoblastomas, probably arising as the cause of a new mutational event (de novo) after completion of chemotherapy treatment. RESULTS: Patients were treated with an average of 5.8 +/- 1.8 chemotherapy courses (4.6 +/- 2.4-year follow-up time). Development of de novo tumors occurred in 48% of the treated eyes. These tumors occurred during chemotherapy treatment or within 7 months of chemotherapy completion. No de novo tumors developed in patients older than 3.2 years. Children who developed de novo tumors were significantly younger at the time of diagnosis (6.7 +/- 6.3 months vs 14.4 +/- 11.4 months, P < 0.001), and had a significantly lower number of tumors per eye at treatment begin (2.6 +/- 2.3 tumors vs 4.3 +/- 6.4 tumors, P < 0.001). The difference of the total numbers of retinoblastomas that developed per eye between the patients that developed de novo retinoblastomas during or after chemotherapy and patients who did not was not statistically significant (4.9 +/- 2.7 and 4.3 +/- 6.4, respectively, P = 0.8). No eye was lost because of de novo retinoblastoma development, and 92% of the eyes were preserved. CONCLUSIONS: De novo retinoblastomas developed both during and after completion of chemotherapy treatment. Younger children were at a significantly higher risk for developing de novo intraocular retinoblastomas. Good tumor control and eye preservation rates were achieved with regular and frequent control examinations in addition to the immediate treatment of de novo retinoblastomas.

Proton radiotherapy as an alternative to exenteration in the management of extended conjunctival melanoma.

BACKGROUND: Diffuse and multifocal patterns of conjunctival melanoma may not be treatable with standard eye-sparing methods. The purpose of this study was to evaluate the usefulness of proton beam radiation therapy as an alternative to exenteration. METHODS: Twenty patients with extended conjunctival melanoma were treated by proton beam irradiation. Most cases were T3 tumours which were not accessible to brachytherapy due to their extension, localisation with fornical or caruncular involvement. Only 2 patients had a tumour limited to the bulbar conjunctiva. Both were recurrent tumours with multiple lesions. Sixteen cases were recurrences after various pre-treatments. The area of the conjunctiva which was suspected to have microscopic disease was treated by 31 Gy in 6 fractions. The "high risk" areas with a clinically detectable tumour (primary target volume) were treated by an additional boost using a smaller beam size and applying 2 fractions up to 45 Gy. An individually shaped compensator was brought into the beam to modify the range of the protons so that the eye was irradiated only at a depth of 2 mm. RESULTS: The mean follow-up time was 38.1+/-26.6 months (median 34 months). Recurrent disease occurred in 6 cases (30%); 2 of them outside the irradiated volume, 3 within the target volume treated by 31 Gy, and just one in the primary target volume treated by 45 Gy. An exenteration followed only in two patients (10%). 6 patients (30%) suffered from metastatic disease and 4 (20%) of them have died by now. During follow up we found no statistically significant association between the occurrence of local recurrence after proton radiotherapy and the development of metastases. Best corrected visual acuity remained stable in 12 cases (60%); in 14 patients the best corrected visual acuity was 0.25 or better. A sicca-syndrome developed in 19/20 patients. However, only 10/20 patients used artificial tears more than 5x/d. A focal cataract developed in 7 patients (35%). There was eyelash loss in the area of irradiated eyelids. In 4 cases a limbal stem cell deficiency occurred with the consequence of corneal vascularisation. CONCLUSIONS: Proton radiotherapy may serve as an alternative to exenteration in case of T3 and diffuse T1 or T2 conjunctival melanomas.

Beta-ray brachytherapy of retinoblastoma: feasibility of a new small-sized ruthenium-106 plaque.

UNLABELLED: A non-comparative case observation study estimated the feasibility of brachytherapy for retinoblastoma with a newly designed ruthenium-106 plaque (label: CXS) with an 8-mm diameter of the irradiation zone. METHODS: The new CXS plaque was used between 2001 and 2003 for brachytherapy of 13 retinoblastomas. Indications were recurrences after preceding local treatment or endophytic retinoblastoma with an impending vitreous tumour cell seeding. The prescribed radiation dose at the apex was 88 Gy (NIST-calibrated dosimetry). RESULTS: The mean age at brachytherapy was 1.2 years (standard deviation, SD: 1.1 years), and the mean follow-up was 1.7 years (SD: 0.6 years). The treated tumours had a mean diameter of 2.3 mm (SD: 0.7 mm) and a mean height of 1.5 mm (SD: 0.6 mm) with a mean distance to the optic disc of 9.9 mm (SD: 2.2 mm). The mean duration of irradiation was 29.3 h (SD: 9.9 h) with a mean dose at the sclera of 213 Gy (SD: 80 Gy). Surgery was uneventful in all cases. Complete regression developed after 3.1 months (SD: 2.8 months) in all cases without a recurrence or a progression of the vitreous tumour cell seeding. The eyes developed no further side-effects besides a temporary circumscribed intra-ocular haemorrhage that emerged from the regressive tumour remnants. CONCLUSION: Brachytherapy with the CXS plaque seems to be a safe and reliable treatment option for small-sized retinoblastoma when laser or cryocoagulation failed to control the tumour growth or for small retinoblastoma with an incipient local tumour cell seeding on the tumour surface.