Proton Irradiations at Ultra-High Dose Rate vs. Conventional Dose Rate: Strong Impact on Hydrogen Peroxide Yield

During ultra-high dose rate (UHDR) external radiation therapy, healthy tissues appear to be spared while tumor control remains the same compared to conventional dose rate. However, the understanding of radiochemical and biological mechanisms involved are still to be discussed. This study shows how the hydrogen peroxide (H2O2) production, one of the reactive oxygen species (ROS), could be controlled by early heterogenous radiolysis processes in water during UHDR proton-beam irradiations. Pure water was irradiated in the plateau region (track-segment) with 68 MeV protons under conventional (0.2 Gy/s) and several UHDR conditions (40 Gy/s to 60 kGy/s) at the ARRONAX cyclotron. Production of H2O2 was then monitored using the Ghormley triiodide method. New values of GTS(H2O2) were added in conventional dose rate. A substantial decrease in H2O2 production was observed from 0.2 to 1.5 kGy/s with a more dramatic decrease below 100 Gy/s. At higher dose rate, up to 60 kGy/s, the H2O2 production stayed stable with a mean decrease of 38% ± 4%. This finding, associated to the decrease in the production of hydroxyl radical (•OH) already observed in other studies in similar conditions can be explained by the well-known spur theory in radiation chemistry. Thus, a two-step FLASH-RT mechanism can be envisioned: an early step at the microsecond scale mainly controlled by heterogenous radiolysis, and a second, slower, dominated by O2 depletion and biochemical processes. To validate this hypothesis, more measurements of radiolytic species will soon be performed, including radicals and associated lifetimes.

Design of Protein-Coated Carbon Nanotubes Loaded with Hydrophobic Drugs through Sacrificial Templating of Mesoporous Silica Shells

One key challenge in the fields of nanomedicine and tissue engineering is the design of theranostic nanoplatforms able to monitor their therapeutic effect by imaging. Among current developed nano-objects, carbon nanotubes (CNTs) were found suitable to combine imaging, photothermal therapy, and to be loaded with hydrophobic drugs. However, a main problem is their resulting low hydrophilicity. To face this problem, an innovative method is developed here, which consists in loading the surface of carbon nanotubes (CNTs) with drugs followed by a protein coating around them. The originality of this method relies on first covering CNTs with a sacrificial template mesoporous silica (MS) shell grafted with isobutyramide (IBAM) binders on which a protein nanofilm is strongly adhered through IBAM-mediated physical cross-linking. This concept is first demonstrated without drugs, and is further improved with the suitable loading of hydrophobic drugs, curcumin (CUR) and camptothecin (CPT), which are retained between the CNTs and human serum albumin (HSA) layer. Such novel nanocomposites with favorable photothermal properties are very promising for theranostic systems, drug delivery, and phototherapy applications.

Tolerability and efficacy of multidose epoetin beta (Reco-Pen) for subcutaneous administration in patients with anemia due to renal failure

AIMS

To assess the tolerability, safety and efficacy of the epoetin beta multidose cartridge formulation, self-administered subcutaneously via a pen device (Reco-Pen), in adult patients with renal anemia.

METHODS

Patients receiving maintenance epoetin therapy were switched to the subcutaneous (SC) multidose formulation of epoetin beta (NeoRecormon). The frequency of adverse events, local tolerability, and changes in blood pressure and laboratory variables were recorded. Hematologic parameters, transfusion requirements and epoetin beta dosage were also assessed.

RESULTS

A total of 406 patients were entered in the intention-to-treat analysis. Mean treatment duration was 82.3 days. Fifty patients (12.3%) withdrew from the study; 14 (3.4%) discontinued because of adverse events. Treatment was well tolerated, with adverse events considered probably related to treatment in only 5 cases, and 1 case of local intolerability. There were no clinically significant changes in blood pressure or laboratory variables, and no changes in hematologic parameters or transfusion requirements. Unexpectedly, the epoetin beta dose was reduced by almost one-third in patients previously maintained on SC epoetin.

CONCLUSION

SC administration of this multidose epoetin beta formulation with the Reco-Pen device was well tolerated and effective. It is possible that the improved capacity to individualize dose may have contributed to the considerable reduction in SC epoetin beta dosage requirement.

Identification and partial characterization of angiogenesis bioactivity in the lower respiratory tract after acute lung injury

Survival after acute lung injury (ALI) depends on prompt alveolar repair, a process frequently subverted by the development of granulation tissue within the alveolar airspace. Immunohistochemical examination of the intraalveolar granulation tissue confirmed that capillaries as well as myofibroblasts were the principal cellular constituents. We therefore hypothesized that angiogenesis factors would be present on the air-lung interface after ALI. To evaluate this hypothesis, bronchoalveolar lavage fluid from patients with ALI (n = 25) and patient controls (n = 8) was examined for angiogenesis bioactivity by its ability of induce endothelial cell migration. While lavage fluid from controls had no bioactivity, lavage fluid from 72% of patients with ALI promoted endothelial cell migration. Heparin affinity, ion exchange, and gel filtration chromatography resolved the bioactivity into at least two moieties. One appeared identical to the well characterized endothelial cell growth factor, basic fibroblast growth factor. The other was a 150-kD non-heparin binding protein that mediated endothelial cell migration and attachment in vitro, and the growth of new vessels in vivo. These data are consistent with the hypothesis that the growth of capillaries into the alveolar airspace results from angiogenesis factors present on the alveolar surface of the lung after ALI.

Hypoxia and endotoxin induce macrophage-mediated suppression of fibroblast proliferation

Cellular mechanisms and environmental factors contributing to wound failure following shock and wound contamination are unclear. The activation of macrophages by exposure to hypoxia (pO2 less than 20) and/or lipopolysaccharide (10 micrograms/ml) in vitro was investigated for its effect on macrophage regulation of fibroblast proliferation. The effect on fibroblast proliferation of conditioned medium from activated murine macrophages or co-culture with activated macrophages was tested by measuring 3T3 fibroblast incorporation of 3H-thymidine and culture DNA content. Unstimulated macrophages produced growth factors that increase fibroblast proliferation (proliferation index (PI) = 1.4 +/- 0.15, p less than 0.05 vs. control). Activation by hypoxia alone had little effect on macrophage regulation of fibroplasia (PI = 1.55 +/- 0.28, N.S. vs. unstimulated macrophages). LPS activated macrophages suppressed fibroplasia and the combination of hypoxia with LPS augmented the suppression (PI = 0.5 +/- 0.11, LPS alone, p less than 0.05 and 0.25 +/- 0.05, LPS + hypoxia, p less than 0.01). In addition, hypoxia + LPS treated co-cultures had reduced DNA contents, suggesting reduced cell numbers (12.5 +/- 2.6 micrograms vs. 8.2 +/- 2.0 micrograms). We screened several macrophage cytokines for their direct effect on 3T3 proliferation and found that mr-Tumor Necrosis Factor-alpha (150 units) also suppressed proliferation. Conditioned supernatants from LPS activated macrophages contained 12 +/- 2 units of mrTNF as measured by L929 cytolysis; however, this was significantly less than required to induce suppression of proliferation by direct addition. The regulatory role of the macrophage appears to be dependent on its level of activation. Activation by hypoxia and LPS altered macrophage regulation of fibroblast proliferation from stimulation to suppression.(ABSTRACT TRUNCATED AT 250 WORDS)