Electrostatically self-assembled gold nanorods with sulfated hyaluronic acid for targeted photothermal therapy for CD44-positive tumors.

Gold nanorods (GNR) produce heat upon irradiation with near-infrared light, enabling a tumor-targeted photothermal therapy. In this study, we prepared GNR coated with sulfated hyaluronic acid (sHA) with a binding affinity for CD44 via electrostatic interactions to deliver GNR to tumors efficiently and stably, and evaluated their usefulness for photothermal therapy. Cationic GNR modified with trimethylammonium groups electrostatically interacted with native HA or sHA with varying degrees of sulfation to form complexes. While GNR/HA was unstable in saline, GNR/sHA maintained the absorbance peak in the near-infrared region, particularly for GNR/sHA with higher degrees of sulfation. GNR/sHA exhibited an intense photothermal effect upon irradiation with near-infrared light. Furthermore, in vitro and in vivo studies revealed that GNR coated with sHA containing approximately 1.2 sulfated groups per HA unit could accumulate in CD44-positive tumors via an HA-specific pathway. These findings indicate the effectiveness of GNR/sHA as a tumor-targeted photothermal therapeutic agent.

Preparation and evaluation of 111In-labeled liposomes containing phosphatidylglycerol for detection of macrophages in atherosclerotic plaques.

Macrophage infiltration is a characteristic feature of atherosclerotic plaque progression. Since liposomes containing 1,2-distearoyl-sn-glycero-3-phosphoglycerol (DSPG) are efficiently phagocytosed by macrophages, we deduced that radiolabeled liposomes containing DSPG could potentially be used for nuclear imaging of vulnerable atherosclerotic plaques. Indium-111 (111In)-labeled liposomes containing different ratios of DSPG were developed with a high labeling efficiency. 111In-labeled liposomes with higher DSPG content showed higher uptake by macrophage-like RAW264 cells. A biodistribution study demonstrated rapid blood clearance and selective accumulation in the liver and spleen, especially in normal mice injected with 111In-labeled liposomes with higher DSPG content. Accumulation in atherosclerotic plaques was evaluated using 111In-labeled DSPG liposomes, which had the highest DSPG content among the studied liposomes. 111In-labeled DSPG liposomes accumulated in the plaques and the radioactive regions were mostly consistent with the distribution of macrophages. The target-to-non-target ratio of 111In-labeled DSPG liposomes was higher than that of 111In-labeled control liposomes without DSPG. These results suggest that 111In-labeled liposomes containing DSPG are useful for nuclear medical diagnosis of atherosclerotic plaques.

Chemical design of radioiodinated probes with a metabolizable linkage for target-selective imaging of systemic amyloidosis.

INTRODUCTION: Systemic amyloidosis is a rare disease caused by the deposition of amyloid fibrils in various organs. Amyloid-targeted radiopharmaceuticals have been developed and applied to diagnose systemic amyloidosis peripherally; however, high-contrast imaging has not been achieved because of the high background signals in normal organs. To overcome this problem, we designed an amyloid-targeted radioiodinated probe 1 with a metabolizable linkage (ester bond) to release of radiolabeled metabolites (m-iodohippuric acid) in normal organs that could be rapidly excreted in the urine. METHODS: Compound 1 was synthesized by conjugating 2-(4-(methylamino)phenyl)benzo[d]thiazol-6-ol, an amyloid-targeting compound, with m-iodohippuric acid. [125I]1 was synthesized via iododestannylation using a tributyltin precursor. Mouse models of amyloid A (AA) amyloidosis, a type of systemic amyloidosis, were prepared by administering amyloid-enhancing factor to mice and used for in vitro autoradiography using organ sections and in vivo evaluation. RESULTS: [125I]1 was obtained with a radiochemical yield of 59% and radiochemical purity of over 95%. An in vitro autoradiographic study demonstrated that [125I]1 specifically binds to amyloid in the splenic tissue. Upon administration to normal mice, [125I]1 was distributed to organs throughout the body, followed by the rapid excretion of radioactivity in the urine as m-[125I]iodohippuric acid. Furthermore, ex vivo autoradiography showed that [125I]1 bound to the amyloid formed around the follicles in the spleens of AA amyloidosis model mice. CONCLUSION: These results suggest that the interposition of a metabolizable linkage between an amyloid-targeting moiety and a radiolabeled hippuric acid would be useful in the design of radiopharmaceuticals for high-contrast imaging of systemic amyloidosis.

Conditional generation of free radicals by selective activation of alkoxyamines: towards more effective and less toxic targeting of brain tumors.

Brain tumors are an important cause of suffering and death. Glioblastoma are the most frequent primary tumors of the central nervous system in adults. They are associated with a very poor prognosis, since only 10% of GBM patients survive 5 years after diagnosis. Medulloblastoma are the most frequent brain malignancies in childhood; they affect the cerebellum in children under 10 years of age in 75% of cases. The current multimodal treatment comes at the expense of serious and often long-lasting side effects. Herein, we propose the synthesis of a library of novel alkoxyamines as anticancer drug candidates. The most efficient molecule, ALK4, was selected based on its ability to inhibit both survival and migration of GBM and MB cells in 2D cultures and in 3D tumor spheroids. A fluorescent derivative was used to show the early cytosolic accumulation of ALK4 in tumor cells. Spontaneous homolysis of ALK4 led to the release of alkyl radicals, which triggered the generation of reactive oxygen species, fragmentation of the mitochondrial network and ultimately apoptosis. To control its homolytic process, the selected alkoxyamine was bioconjugated to a peptide selectively recognized by matrix metalloproteases. This bioconjugate, named ALK4-MMPp, successfully inhibited survival, proliferation, and invasion of GBM and MB tumor micromasses. We further developed innovative brain and cerebellum organotypic models to monitor treatment response over time. It confirmed that ALK4-MMPp significantly impaired tumor progression, while no significant damage was observed on normal brain tissue. Lastly, we showed that ALK4-MMPp was well-tolerated in vivo by zebrafish embryos. This study provides a new strategy to control the activation of alkoxyamines, and revealed the bioconjugate ALK4-MMPp bioconjugate as a good anticancer drug candidate.

[Development of a Radioiodinated Probe for in Vivo Detection of Lipid Radicals and Evaluation Using Middle Cerebral Artery Occlusion Model].

Free radicals, such as hydroxyl radical, superoxide, and lipid-derived radical, have unpaired electrons, making them a highly reactive chemical species. They play important physiological roles, for example, in the removal of xenobiotic substances, such as bacteria and viruses, and in the production of chemical mediators, like prostaglandins and leukotrienes. However, excessive production of free radicals can cause structural defects in biomolecules like DNA and proteins, resulting in a loss of their normal functions. Hence, free radicals have been implicated in the onset and progression of various diseases such as cancer, atherosclerosis, and neurodegenerative diseases. However, there is very little clarity on the substantial amount, type, and location of free radicals in vivo, under pathological conditions. An investigation on the actual state of free radicals in vivo could lead to the diagnosis of pathological conditions and the elucidation of the mechanisms of their onset and progression; therefore, the development of in vivo radical detection methods is being widely pursued. Toward this end, nuclear medical imaging methods have recently attracted attention. In this study, we discuss the development of a nuclear medical imaging probe for the specific targeting of lipid radicals.

Enhanced Therapeutic Effect of Liposomal Doxorubicin via Bio-Orthogonal Chemical Reactions in Tumors.

Liposomes are highly biocompatible drug carriers in drug delivery systems (DDSs). Preferential accumulation of liposomes and acceleration of drug release at target tumor sites are essential for effective cancer therapy using liposomal formulations; however, conventional liposomes are unsuitable for on-demand drug release. We have previously reported that drug release can be accelerated via a bio-orthogonal inverse electron demand Diels-Alder (IEDDA) reaction between amphiphilic tetrazine (Tz)-containing liposomes and norbornene (NB) derivatives in vitro. In this study, we prepared HSTz-liposomes composed of hydrogenated soybean phosphatidylcholine (HSPC) and Tz compound (2-hexadecyl-N-(6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)octadecanamide) with particle sizes of 60-80 nm and ζ-potentials of -5 to 0 mV. Similar to our previous report, the addition of 5-norbornene-2-carboxylic acid (NBCOOH) to HSTz-liposomes accelerated drug release from the liposomes in vitro. In the biodistribution study using colon26 tumor-bearing mice, the radiolabeled HSTz-liposomes were accumulated and retained in the tumor at 6-48 h post-injection, whereas the radioactivity in the blood almost disappeared at 48 h. Therefore, the timing of the injection of NBCOOH was selected to be 48 h after the injection of the HSTz-liposome to avoid the IEDDA reaction in the bloodstream. We investigated the in vivo drug release by evaluating the intratumoral localization of doxorubicin (DOX) encapsulated in HSTz-liposomes labeled with fluorescent lipids. In the tumors treated with HSTz-liposomes and NBCOOH, DOX was more widely dispersed in the tumor compared with fluorescent lipid, suggesting that the release of encapsulated drugs (DOX) from HSTz-liposomes was enhanced in the tumor tissue via the bio-orthogonal IEDDA reaction. Furthermore, the combination of DOX-encapsulated HSTz-liposomes with NBCOOH significantly suppressed tumor growth compared to conventional DOX-encapsulated liposomes. In conclusion, the bio-orthogonal IEDDA reactions in the liposomal membrane enabled the acceleration of drug release from HSTz-liposomes in vivo, suggesting a promising strategy for effective cancer therapy.

Risk factors for intraocular pressure elevation during the early period post cataract surgery.

PURPOSE: To assess the risk factors for intraocular pressure (IOP) elevation during the early period post cataract surgery. STUDY DESIGN: Retrospective study. METHODS: This study involved 1587 eyes that underwent cataract surgery at the Baptist Eye Institute, Kyoto, Japan between April 2020 and May 2021. In all subjects, risk factors for early postoperative IOP elevation (i.e., an increase of IOP of 10 mmHg or more at 1-day postoperative compared with that at baseline, or a postoperative IOP of 28 mmHg or more) were analyzed by multivariate logistic regression analysis. RESULTS: Of the 1587 treated eyes in this study, 100 (6.3%) experienced early-postoperative IOP elevation. Of those 100 eyes, 78.0% were men, 27.0% had an axial length (AL) of ≥ 26.5 mm, 23.0% had a history of glaucoma treatment, 11.0% had poor mydriasis and 10.0% had intraoperative floppy iris syndrome (IFIS). Multivariate analysis findings revealed that male [odds ratio (OR) 4.36; 95% confidence interval (CI) 2.63-7.23; P < 0.001], AL of ≥ 26.5 mm (3.11; 1.83-5.30; P < 0.001), a history of glaucoma treatment (2.83; 1.63-4.91; P < 0.001), poorly mydriasis (2.63; 1.16-6.01; P = 0.02), IFIS (4.37; 1.78-10.74; P = 0.001) and baseline high IOP (1.09; 1.01-1.18; P = 0.03) were associated with increased IOP during the early period post cataract surgery. CONCLUSIONS: The findings in this study reveal that male sex, high myopia, a history of glaucoma treatment, poor mydriasis, IFIS and baseline high IOP are risk factors for IOP elevation during the early period post cataract surgery.

Development of a radioiodinated thioflavin-T-Congo-red hybrid probe for diagnosis of systemic amyloidosis.

INTRODUCTION: Systemic amyloidosis is a group of diseases characterized by the deposition of amyloid protein in multiple organs throughout the body and causing their dysfunction. As amyloid deposition is observed at an early phase and is highly specific to systemic amyloidosis, noninvasive detection of amyloid is considered useful for the early diagnosis of systemic amyloidosis. In this study, we designed and synthesized a novel radiolabeled amyloid imaging probe, sodium (E)-4-amino-3-((4-(6-iodobenzothiazol-2-yl)phenyl)diazenyl)naphthalene-1-sulfonate (1), which combines two amyloid-binding compounds, thioflavin-T and Congo-red, and evaluated its effectiveness in diagnosing amyloidosis. METHODS: A tributyltin precursor was synthesized through a 5-step reaction from 2-amino-6-bromobenzothiazole, and [125I]1 was synthesized by an iododestannylation reaction with a tributyltin precursor. Mouse models of amyloid A (AA) amyloidosis, a type of systemic amyloidosis, were prepared by intraperitoneal injection of amyloid-enhancing factor into mice. An in vitro autoradiographic study was performed using spleen sections from normal mice and AA amyloidosis mice. Furthermore, [125I]1 was intravenously injected into mice, and its distribution was evaluated. Finally, an ex vivo autoradiographic study was performed using AA amyloidosis mice. RESULTS: [125I]1 was obtained with a radiochemical yield of 66% and a radiochemical purity of over 95%. In vitro autoradiography revealed specific binding of [125I]1 to thioflavin-S-stained regions in the spleen. Normal mice showed relatively rapid clearance of [125I]1 from the organs, whereas radioactivity was retained in the spleen, where amyloid deposition was observed in model mice. Furthermore, ex vivo autoradiography showed a heterogeneous distribution of [125I]1, which was co-localized with thioflavin-S-stained regions in the spleen of model mice. CONCLUSION: These results indicate the potential of radioiodinated 1 as a nuclear imaging probe for diagnosing AA amyloidosis.

Redox Monitoring in Nuclear Medical Imaging.

Significance: The imbalance in redox homeostasis is known as oxidative stress, which is relevant to many diseases such as cancer, arteriosclerosis, and neurodegenerative disorders. Overproduction of reactive oxygen species (ROS) is one of the factors that trigger the redox state imbalance in vivo. The ROS have high reactivity and impair biomolecules, whereas antioxidants and antioxidant enzymes, such as ascorbate and glutathione, reduce the overproduction of ROS to rectify the redox imbalance. Owing to this, redox monitoring tools have been developed to understand the redox fluctuations in oxidative stress-related diseases. Recent Advances: In an attempt to monitor redox substances, including ROS and radical species, versatile modalities have been developed, such as electron spin resonance, chemiluminescence, and fluorescence. In particular, many fluorescent probes have been developed that are selective for ROS. This has significantly contributed to understanding the relevance of ROS in disease onset and progression. Critical Issues: To date, the dynamics of ROS and radical fluctuation in in vivo redox states remain unclear, and there are a few methods for the in vivo detection of redox fluctuations. Future Directions: In this review, we summarize the development of radiolabeled probes for monitoring redox-relevant species by nuclear medical imaging that is applicable in vivo. In the future, translational research is likely to be advanced through the development of highly sensitive and in vivo applicable detection methods, such as nuclear medical imaging, to clarify the underlying dynamics of ROS, radicals, and redox substances in many diseases. Antioxid. Redox Signal. 36, 797-810.

Enhanced Delivery of Thermoresponsive Polymer-Based Medicine into Tumors by Using Heat Produced from Gold Nanorods Irradiated with Near-Infrared Light.

The aim of this study was to establish a drug delivery system (DDS) for marked therapy of tumors using a thermoresponsive polymer, polyoxazoline (POZ). The effectiveness of the following was investigated: (i) the delivery of gold nanorods (GNRs) to tumor tissues, (ii) heat production of GNR upon irradiation with near-infrared (NIR) light, and (iii) high accumulation of an intravenously injected radiolabeled POZ as a drug carrier in tumors by sensing heat produced by GNRs. When the GNR solution was irradiated with NIR light (808 nm), the solution temperature was increased both in a GNR-concentration-dependent manner and in a light-dose-dependent manner. POZ, with a lower critical solution temperature of 38 °C, was aggregated depending on the heat produced by the GNR irradiated by NIR light. When it was intratumorally pre-injected into colon26-tumor-bearing mice, followed by NIR light irradiation (GNR+/Light+ group), the tumor surface temperature increased to approximately 42 °C within 5 min. Fifteen minutes after irradiation with NIR light, indium-111 (111In)-labeled POZ was intravenously injected into tumor-bearing mice, and the radioactivity distribution was evaluated. The accumulation of POZ in the tumor was significantly (approximately 4-fold) higher than that in the control groups (GNR+/without NIR light irradiation (Light-), without injection of GNR (GNR-)/Light+, and GNR-/Light- groups). Furthermore, an in vivo confocal fluorescence microscopy study, using fluorescence-labeled POZ, revealed that uptake of POZ by the tumor could be attributed to the heat produced by GNR. In conclusion, we successfully established a novel DDS in which POZ could be efficiently delivered into tumors by using the heat produced by GNR irradiated with NIR light.

Electrostatically self-assembled gold nanorods with chondroitin sulfate for targeted photothermal therapy for melanoma.

BACKGROUND: The application of gold nanorods (GNRs) in photothermal therapy is a promising avenue for cancer treatment. The aim of this study was to develop a GNR-based targeted photothermal therapy for melanoma. METHODS: We utilized the electrostatic interaction between cationic GNRs and an anionic polymer chondroitin sulfate A (CSA), which has an affinity for binding to melanoma cells, to construct an anionic binary GNR-CSA complex (GNR-CS) at an optimal theoretical charge ratio of the trimethylammonium groups of GNR: carboxyl and sulfate groups of CSA = 1:2.5. The cytotoxicity to normal cells and erythrocyte agglutination activity of GNR-CS were evaluated. After the cellular uptake of GNR-CS by melanoma cells (B16-F10) was investigated, the photothermal performance of GNR-CS against B16-F10 cells was evaluated in vitro. RESULTS: The particle size and zeta potential of GNR-CS were approximately 35 nm and -20 mV, respectively. GNR-CS showed little cytotoxicity to normal cells and low erythrocyte agglutination activity, indicating good biocompatibility. Compared with negatively-charged GNR, GNR-CS was highly taken up by B16-F10 cells even if it was negatively charged. Cellular uptake was significantly suppressed upon treatment with excess CSA, suggesting the involvement of a CSA-specific uptake pathway. Furthermore, irradiation of the GNR-CS solution with near-infrared (NIR) light increased its temperature in light-intensity and GNR-concentration dependent manners. GNR-CS exhibited significant and GNR-dose dependent cytotoxicity in melanoma cells in combination with NIR light irradiation. CONCLUSION: GNRs coated with CSA have the potential as a medicine in targeted photothermal therapy for melanoma.

A Radiolabeled Self-assembled Nanoparticle Probe for Diagnosis of Lung-Metastatic Melanoma.

Melanoma is a highly malignant skin cancer that frequently metastasizes to the lung, bone, and brain at an early phase. Therefore, noninvasive detection of metastasized melanoma could be beneficial to determine suitable therapeutic strategies. We previously reported a biocompatible ternary anionic complex composed of plasmid DNA (pDNA), polyethyleneimine (PEI), and γ-polyglutamic acid (γ-PGA) based on an electrostatic interaction, which was highly taken up by melanoma cells (B16-F10), even if it was negatively charged. Here, we developed a radiolabeled γ-PGA complex by using indium-111 (111In)-labeled polyamidoamine dendrimer (4th generation; G4) instead of pDNA and iodine-125 (125I)-labeled PEI instead of native PEI, and evaluated its effectiveness as a melanoma-targeted imaging probe. This ternary complex was synthesized at a theoretical charge ratio; carboxyl groups of 111In-diethylenetriaminepentaacetic acid (DTPA)-G4 : amino groups of 125I-PEI : carboxyl groups of γ-PGA was 1 : 8 : 16, and the size and zeta potential were approximately 29 nm and -33 mV, respectively. This complex was taken up by B16-F10 cells with time. Furthermore, a biodistribution study, using normal mice, demonstrated its accumulation in the liver, spleen, and lung, where macrophage cells are abundant. Almost the same level of radioactivity derived from both 111In and 125I was observed in these organs at an early phase after probe injection. Compared with the normal mice, significantly higher lung-to-blood ratios of radioactivity were observed in the B16-F10-lung metastatic cancer model. In conclusion, the radiolabeled γ-PGA complex would hold potentialities for nuclear medical imaging of lung metastatic melanoma.

A radioiodinated nitroxide probe with improved stability against bioreduction for in vivo detection of lipid radicals.

It is well known that lipid carbon radicals (lipid radicals) are the origin of lipid peroxidation and are involved in various diseases such as cancer. Therefore, the in vivo detection of lipid radicals would be expected to lead to early diagnosis of these diseases. However, there are no methods for measuring lipid radicals in vivo. Nitroxides are known to be highly reactive with lipid radicals, but they tend to be reduced in vivo. Focusing on the excellent detection sensitivity of nuclear medical imaging, we have developed a radioiodinated nitroxide derivative with resistance to bioreduction for the in vivo detection of lipid radicals. The desired compound was obtained successfully and was highly stable against bioreduction while maintaining high reactivity toward lipid radicals. The I-125 labeling was efficacious with radiochemical yields of 84-87% and radiochemical purities of >99%. A cellular uptake assay showed that the radioiodinated compound was significantly taken up by cells under lipid radical-producing conditions compared to that in the absence of lipid radical production. A biodistribution study indicated that the radioiodinated compound accumulated more in organs where lipid peroxidation was promoted than the methoxyamine derivative, which lost reactivity to lipid radicals. These results indicated that the developed probe became trapped in cells or organs by reacting with lipid radicals. Thus, the radioiodinated nitroxide is a candidate probe for in vivo detection of lipid radicals.

Radiation-induced redox alteration in the mouse brain.

Time courses of the redox status in the brains of mice after X-ray or carbon-ion beam irradiation were observed by magnetic resonance redox imaging (MRRI). The relationship between radiation-induced oxidative stress on the cerebral nervous system and the redox status in the brain was discussed. The mice were irradiated by 8-Gy X-ray or carbon-ion beam (C-beam) on their head under anesthesia. C-beam irradiation was performed at HIMAC (Heavy-Ion Medical Accelerator in Chiba, NIRS/QST, Chiba, Japan). MRRI measurements using a blood-brain-barrier-permeable nitroxyl contrast agent, MCP or TEMPOL, were performed using 7-T scanner at several different times, i.e., 5-10 h, 1, 2, 4, and 8 day(s) after irradiation. Decay rates of the nitroxyl-enhanced T1-weighted MR signals in the brains were estimated from MRRI data sets, and variation in the decay rates after irradiation was assessed. The variation in decay rates of MCP and TEMPOL after X-ray or C-beam irradiation was similar, but different variation patterns were observed between X-ray and C-beam. The apparent decay rate of both MCP and TEMPOL decreased due to the temporal reduction of blood flow in the brain several hours after X-ray and/or C-beam irradiation. After decreasing, the apparent decay rates of nitroxyl radicals in the brain gradually increased during the following days after X-ray irradiation or rapidly increased 1 day after C-beam irradiation. The sequential increase in nitroxyl decay rates may have been due to the oxidative atmosphere in the tissue due to ROS generation. X-ray and C-beam irradiation resulted in different redox responses, which may have been due to time-varying oxidative stress/injury, in the mouse brain. The C-beam irradiation effects were more acute and larger than those of X-ray irradiation.

Multiple Linear Regression Analysis of the Impact of Corneal Epithelial Thickness on Refractive Error Post Corneal Refractive Surgery.

PURPOSE: To evaluate the influence of corneal epithelial thickness (CET) on the deviation from the targeted refraction (refractive error [RE]) post corneal refractive surgery. DESIGN: Retrospective, single-center, cross-sectional study. METHODS: This study involved 211 eyes of 211 patients who previously underwent laser-assisted in situ keratomileusis (LASIK) or epipolis LASIK for the correction of myopia and myopic astigmatism from August 2000 to May 2014 at the Baptist Eye Institute, Kyoto, Japan, and who subsequently underwent examination of CET via optical coherence tomography imaging of 17 zones (central: n = 1 zone, paracentral: n = 8 zones, and midperipheral: n = 8 zones) within a 6.0-mm-diameter area of the central cornea from April 2014 to February 2015. The relationship between CET and RE was evaluated using Spearman coefficient in 5 parameters: CET in the (1) central, (2) paracentral, and (3) midperipheral zones, and the difference between the (4) central and paracentral zones and the (5) central and midperipheral zones. The influence of CET on RE was evaluated in the CET parameter that showed a significant correlation with RE using multiple liner regression analysis. RESULTS: The correlation coefficient with RE was (1) -0.238 (P < .01), (2) -0.172 (P < .05), (3) -0.002 (P = .98), (4) -0.186 (P < .01), and (5) -0.266 (P < .01), respectively. Multiple liner regression analysis revealed that the difference of mean CET between the central and midperipheral zones had a significant influence on RE (ß coefficient = -0.028, P < .01). CONCLUSIONS: The difference between CET at the central and midperipheral zones may play a role in the final RE post corneal refractive surgery.

Chemical modifications of imidazole-containing alkoxyamines increase C-ON bond homolysis rate: Effects on their cytotoxic properties in glioblastoma cells.

Previously, we described alkoxyamines bearing a pyridine ring as new pro-drugs with low molecular weights and theranostic activity. Upon chemical stimulus, alkoxyamines undergo homolysis and release free radicals, which can, reportedly, enhance magnetic resonance imaging and trigger cancer cell death. In the present study, we describe the synthesis and the anti-cancer activity of sixteen novel alkoxyamines that contain an imidazole ring. Activation of the homolysis was conducted by protonation and/or methylation. These new molecules displayed cytotoxic activities towards human glioblastoma cell lines, including the U251-MG cells that are highly resistant to the conventional chemotherapeutic agent Temozolomide. We further showed that the biological activities of the alkoxyamines were not only related to their half-life times of homolysis. We lastly identified the alkoxyamine (RS/SR)-4a, with both a high antitumour activity and favourable logD7.4 and pKa values, which make it a robust candidate for blood-brain barrier penetrating therapeutics against brain neoplasia.

Lipophilic triphenylphosphonium derivatives enhance radiation-induced cell killing via inhibition of mitochondrial energy metabolism in tumor cells.

It has recently been reported that radiation enhances mitochondrial energy metabolism in various tumor cell lines. To examine how this radiation-induced alteration in mitochondrial function influences tumor cell viability, various lipophilic triphenylphosphonium (TPP+) cation derivatives and related compounds such as 4-hydroxy-2,2,6,6-tetramethyl-1-oxy-piperidin (Tempol) with TPP+ (named "Mito-") were designed to inhibit the mitochondrial electron transport chain. Mito-(CH2)10-Tempol (M10T) and its derivatives, Mito-(CH2)5-Tempol (M5T), Mito-(CH2)10-Tempol-Methyl (M10T-Me), Mito-C10H21 (M10), and C10H21-Tempol (10T), were prepared. In HeLa human cervical adenocarcinoma cells and A549 human lung carcinoma cells, the fractional uptake of the compound into mitochondria was highest among the TTP+ analogs conjugated with Tempol (M10T, M5T, and 10T). M10T, M10T-Me, and M10 exhibited strong cytotoxicity and enhanced X-irradiation-induced reproductive cell death, while 10T and M5T did not. Furthermore, M10T, M10T-Me, and M10 decreased basal mitochondrial membrane potential and intracellular ATP. M10T treatment inhibited X-ray-induced increases in ATP production. These results indicate that the TPP cation and a long hydrocarbon linker are essential for radiosensitization of tumor cells. The reduction in intracellular ATP by lipophilic TPP+ is partly responsible for the observed radiosensitization.

Fluorescence probes to detect lipid-derived radicals.

Lipids and their metabolites are easily oxidized in chain reactions initiated by lipid radicals, forming lipid peroxidation products that include the electrophiles 4-hydroxynonenal and malondialdehyde. These markers can bind cellular macromolecules, causing inflammation, apoptosis and other damage. Methods to detect and neutralize the initiating radicals would provide insights into disease mechanisms and new therapeutic approaches. We describe the first high-sensitivity, specific fluorescence probe for lipid radicals, 2,2,6-trimethyl-4-(4-nitrobenzo[1,2,5]oxadiazol-7-ylamino)-6-pentylpiperidine-1-oxyl (NBD-Pen). NBD-Pen directly detected lipid radicals in living cells by turn-on fluorescence. In a rat model of hepatic carcinoma induced by diethylnitrosamine (DEN), NBD-Pen detected lipid radical generation within 1 h of DEN administration. The lipid radical scavenging moiety of NBD-Pen decreased inflammation, apoptosis and oxidative stress markers at 24 h after DEN, and liver tumor development at 12 weeks. Thus, we have developed a novel fluorescence probe that provides imaging information about lipid radical generation and potential therapeutic benefits in vivo.

Nasal and conjunctival screening prior to refractive surgery: an observational and cross-sectional study.

OBJECTIVES: To investigate bacterial flora of clinically healthy conjunctiva and nasal cavity among patients prior to refractive surgery, as well as the characteristics of patients with methicillin-resistant Staphylococcus aureus (MRSA) colonisation. DESIGN: Observational and cross-sectional study. SETTING: A single-centre study in Japan. PARTICIPANTS: 120 consecutive patients pre-refractive surgery. PRIMARY AND SECONDARY OUTCOME MEASURES METHODS: Samples were obtained from the right conjunctival sac and the nasal cavity of 120 consecutive patients prior to refractive surgery and were then measured for the levels of the minimum inhibitory concentration (MIC) of antibiotics. Patients were interviewed regarding their occupation, family living situation and any personal history of atopic dermatitis, asthma, smoking or contact lens wear. RESULTS: Propionibacterium acnes (P. acnes) (32.5%) and Staphylococcus epidermidis (4.2%) were detected from the conjunctival sac. S. epidermidis was the most commonly isolated (68.3%) in the nasal cavity. Of the 30 patients (25.0%) with colonisation by S. aureus, 2 patients, both of whom were healthcare workers with atopic dermatitis, were found to be positive for MRSA in the nasal cavity. A history of contact lens wear, asthma or smoking, as well as patient gender and age, was not associated with MRSA colonisation. CONCLUSIONS: There were only 2 patients who were colonised with MRSA, both of whom were healthcare workers with atopic dermatitis. P. acnes was predominantly found in the conjunctival sac. Further study is needed to investigate the involvement between nasal and conjunctival flora, and risk factors for infectious complications.

A novel DPP-4 inhibitor teneligliptin scavenges hydroxyl radicals: In vitro study evaluated by electron spin resonance spectroscopy and in vivo study using DPP-4 deficient rats.

AIMS: Recently various dipeptidyl peptidase-4 (DPP-4) inhibitors have emerged because of their high effectiveness and safety. In spite of their common effect of DPP-4 inhibition, the chemical structures are diverse. Here we show that the structure of teneligliptin, a novel DPP-4 inhibitor, has a scavenging activity on hydroxyl radical (·OH). METHODS: ·OH and superoxide (O2(-)) were detected by electron spin resonance (ESR) spectroscopy. ·OH and O2(-) were generated in vitro by the Fenton reaction and a hypoxanthine-xanthine oxidase system, respectively. The level of free radicals was estimated from the ESR signal intensity. The product via teneligliptin and ·OH reaction was identified by thin layer chromatography and mass spectrometry analysis. In vivo effect was also evaluated using DPP-4 deficient rats with streptozotocin-induced diabetes. RESULTS: ESR spectroscopy analysis showed that teneligliptin did not scavenge O2(-), but scavenged ·OH in a dose dependent manner. Its activity was greater than that of glutathione. The reaction product appeared to have an oxygen-atom added structure to that of teneligliptin, which was identical to the most abundant metabolite of teneligliptin in human plasma. Furthermore, using DPP-4 deficient rat, teneligliptin did not affect plasma glucose levels or body weight, but normalized increased levels of 8-hydroxy-2'-deoxyguanosine in urine, kidney and aorta of diabetic rats, supporting that teneligliptin may have a ·OH scavenging activity in vivo independently of DPP-4 inhibition. CONCLUSIONS: Teneligliptin is not only effective as DPP-4 inhibitor, but may also be beneficial as ·OH scavenger, which may be useful in the prevention of diabetic complications.