Ruthenium Pyrazole Complexes: A Family of Highly Active Metallodrugs for Photoactivated Chemotherapy.

Ruthenium complexes bearing bis pyrazole (pzH) ligands, cis-[Ru(bpy)2(R-pzH)2]2+ (bpy = 2,2'-bipyridine, R = -H, -Cl), were examined as photoactivated anticancer prodrugs. A dicationic pyrazole complex deprotonated to give monocationic pyrazole-pyrazolate complexes, cis-[Ru(bpy)2(R-pz-)(R-pzH)]+, in an aqueous solution with pKa values of 9.5 and 7.2 for R = H and R = Cl, respectively. Upon deprotonation, relative quantum yields of photosubstitution decreased while lipophilicity of the complexes increased according to the measurements of water-octanol coefficients. The ruthenium complex with 4-chloropyrazole ligands displayed high cytotoxicity upon light irradiation (IC50 = 0.060 ± 0.016 µM) toward lung cancer cells, which was 7 times higher than that in the dark (IC50 = 0.44 ± 0.07 µM). Additional experiments for the ruthenium R-pyrazole complexes indicated that (1) selective photodissociation of the 4-chloropyrazole ligand occurs from cis-[Ru(bpy)2(4-Clpz-)(4-ClpzH)]+, (2) photoinduced ligand dissociation is dominant rather than photoinduced generation of singlet oxygen (1O2), and (3) induction of cell death occurs via the intrinsic pathway of apoptosis.

Transition to a market economy and chronic psychosocial stress in northern Laos: An exploratory study of urinary free cortisol in rural residents.

OBJECTIVES: The indigenous population in northern Laos has experienced a transition from self-sufficiency to a market-oriented economy, which may have brought about unprecedented chronic psychosocial stress. This study examined the association between the transition to a market economy and urinary free cortisol (UFC) concentration as a stress biomarker among rural residents of three villages with different degrees of integration into the market economy. METHODS: An interview survey and urine sample collection were conducted in August 2018 and March 2019. We measured the UFC concentration in spot urine samples collected in the morning from participants aged 20-60 years (n = 168) using an enzyme-linked immunosorbent assay. Multiple linear regression analysis was performed to examine differences in UFC concentrations among villages by sex, with time of arrival for the survey, age, and body mass index included as covariates. RESULTS: The UFC concentration was higher in men living in the village with the highest degree of integration into the market economy than in those in the two villages with a lower dependence on cash, possibly linking increased stress levels with a change in employment type. This trend was not observed in women. CONCLUSION: Socioeconomic changes incidental to a transition to a market economy may increase the stress levels of men in northern Laos.

Intravenous Administration of Mesenchymal Stem Cell-Derived Exosome Alleviates Spinal Cord Injury by Regulating Neutrophil Extracellular Trap Formation through Exosomal miR-125a-3p.

Spinal cord injury (SCI) leads to devastating sequelae, demanding effective treatments. Recent advancements have unveiled the role of neutrophil extracellular traps (NETs) produced by infiltrated neutrophils in exacerbating secondary inflammation after SCI, making it a potential target for treatment intervention. Previous research has established that intravenous administration of stem cell-derived exosomes can mitigate injuries. While stem cell-derived exosomes have demonstrated the ability to modulate microglial reactions and enhance blood-brain barrier integrity, their impact on neutrophil deactivation, especially in the context of NETs, remains poorly understood. This study aims to investigate the effects of intravenous administration of MSC-derived exosomes, with a specific focus on NET formation, and to elucidate the associated molecular mechanisms. Exosomes were isolated from the cell supernatants of amnion-derived mesenchymal stem cells using the ultracentrifugation method. Spinal cord injuries were induced in Sprague-Dawley rats (9 weeks old) using a clip injury model, and 100 µg of exosomes in 1 mL of PBS or PBS alone were intravenously administered 24 h post-injury. Motor function was assessed serially for up to 28 days following the injury. On Day 3 and Day 28, spinal cord specimens were analyzed to evaluate the extent of injury and the formation of NETs. Flow cytometry was employed to examine the formation of circulating neutrophil NETs. Exogenous miRNA was electroporated into neutrophil to evaluate the effect of inflammatory NET formation. Finally, the biodistribution of exosomes was assessed using 64Cu-labeled exosomes in animal positron emission tomography (PET). Rats treated with exosomes exhibited a substantial improvement in motor function recovery and a reduction in injury size. Notably, there was a significant decrease in neutrophil infiltration and NET formation within the spinal cord, as well as a reduction in neutrophils forming NETs in the circulation. In vitro investigations indicated that exosomes accumulated in the vicinity of the nuclei of activated neutrophils, and neutrophils electroporated with the miR-125a-3p mimic exhibited a significantly diminished NET formation, while miR-125a-3p inhibitor reversed the effect. PET studies revealed that, although the majority of the transplanted exosomes were sequestered in the liver and spleen, a notably high quantity of exosomes was detected in the damaged spinal cord when compared to normal rats. MSC-derived exosomes play a pivotal role in alleviating spinal cord injury, in part through the deactivation of NET formation via miR-125a-3p.

Peripherally inserted central catheters can be an alternative to tunneled central venous catheters in chemotherapy for hematological and oncological pediatric patients.

PURPOSE: Tunneled central venous catheters (TCVs) are commonly used for pediatric chemotherapy. Recently, peripherally inserted central catheters (PICCs) have been used instead. Although PICC has the advantages of simpler insertion and fewer severe complications, there is little information on the efficacy of PICC compared to TCV in pediatric chemotherapy. METHODS: Patients, aged younger than 18 years, with primary malignancy who received chemotherapy with PICC or TCV at our institution from December 2007 to August 2022 were included in the study. We retrospectively compared PICC and TCV using medical records. RESULTS: Within the observation period, 133 catheters (73 PICCs and 60 TCVs) were inserted. The median indwelling time was 99 days for PICCs and 182 days for TCVs, with TCVs being significantly longer (p < 0.001). There were no significant differences in the incidence of complications, such as infections, thrombosis, obstruction, or mechanical accidents. Comparing patients treated with PICC (PICC group) versus those with TCV (TCV group), the time from diagnosis to insertion was significantly shorter in the PICC group (p < 0.001). In the PICC group, none of the patients required general anesthesia, and chemotherapy was completed with PICC only. CONCLUSION: PICC can be an alternative to TCV in pediatric chemotherapy.

Ultrasmall-Scale Brittle Fracture Initiated from a Dislocation in SrTiO3.

Crystal defects often lead to an intriguing variety of catastrophic failures of materials and determine the mechanical properties. Here we discover that a dislocation, which was believed to be a source of plasticity, leads to brittle fracture in SrTiO3. The fracture mechanism, i.e., bond breaking at the dislocation core triggers crack initiation and subsequent fracture, is elucidated from an atomic view by hybrid quantum and molecular simulations and in situ nanomechanical experiments. The fracture strength of the dislocation-included SrTiO3 was theoretically evaluated to be 8.8-10.7 GPa, which was eminently lower than that of the pristine one (21.7 GPa). The experimental results agree well with the simulated ones. Moreover, the fracture toughness of the ultrasmall crack initiating from the dislocation is quantitatively evaluated. This study reveals not only the role of dislocations in brittle fracture but also provides an in-depth understanding of the fracture mechanism of dislocations at the atomic scale.

Intermolecular correlations of liquid and glassy CS2 studied by synchrotron radiation x-ray diffraction.

How is the orientation of molecular liquids ordered on cooling? What are the basic structures of molecular glasses, e.g., close to the crystalline structure or some special structures such as icosahedral cluster? These are long-standing questions in liquid and glass physics. We have constructed a novel cryostat to prepare simple molecular glasses by vapor deposition and performed in situ synchrotron radiation x-ray diffraction experiments. The glassy state of a simple molecule CS2, which cannot be vitrified by normal liquid quenching, was successfully prepared with this instrument, and its diffraction data were collected in a wide Q-range of 0.16-25.7 Å-1 with a high-energy diffractometer at BL04B2, SPring-8. The diffraction data of liquid CS2 were also recorded in a wide temperature range of 160-300 K. These diffraction data were analyzed with molecular dynamics simulations and reverse Monte Carlo modelings to investigate orientational correlation. From the obtained 3D structure models, the orientational correlation between neighboring CS2 molecules was investigated quantitatively as a function of temperature. At room temperature, the parallel and T-shaped arrangements are preferred for the nearest neighbor correlation. On cooling, these arrangements are developed gradually, and its rate became prominent below the melting temperature (162 K). In the glassy state, the slipped-parallel arrangement is dominant as well as the T-shaped arrangement. Both arrangements appear in the CS2 crystal, indicating that the structure of glassy CS2 is close to that of crystalline CS2.

Impact of modernization on urinary concentrations of arsenic, cadmium, lead, and selenium in rural residents of Northern Laos.

OBJECTIVES: The impacts of modernization on toxic heavy metal exposure and essential trace element intake in indigenous populations of subsistence societies are unknown. We assessed urinary trace element concentrations in rural residents of Northern Laos and examined associations with levels of modernization. METHODS: A cross-sectional study was conducted comprising 380 residents of three villages in Northern Laos with different levels of modernization. We surveyed general characteristics and measured the weight and height of 341 participants. Arsenic, cadmium, lead, and selenium concentrations were measured in spot urine samples by inductively coupled plasma mass spectrometry. We examined associations between urinary trace element concentrations and variables related to modernization (village, roofing material, possessions index [total number of possessions], and body mass index [BMI]) using multilevel analyses with household as a random effect, after adjusting for sex, age, and smoking status. RESULTS: Urinary concentrations of arsenic and cadmium were high, while those of lead and selenium were low in comparison to previous reports of populations in non-contaminated regions or without excess/deficiency. We observed associations between urinary trace element concentrations and village-level modernization: lead and selenium concentrations were higher in more modernized villages and cadmium concentration was highest in the least modernized village. Urinary arsenic concentration was not predicted by the modernization level of a village, although we observed significant differences among villages. In addition, urinary selenium concentration was higher in participants inhabiting more modernized houses. CONCLUSION: Modernization of villages may impact toxic heavy metal exposure and selenium intake in rural residents of Northern Laos.

Fabrication of novel-shaped microneedles to overcome the disadvantages of solid microneedles for the transdermal delivery of insulin.

In this study, we fabricated two different microneedles (MNs) - semi-hollow and bird-bill - to overcome the limitations of solid and coated MNs, respectively. The two MN arrays were developed using a general injection molding process to obtain high-quality MNs with uniform shape. The semi-hollow and bird-bill MNs could penetrate the micropores of swine skin up to depths of 178.5 ± 27.6 µm and 232.1 ± 51.3 µm, respectively. When the semi-hollow MNs were used for the transdermal delivery of insulin in diabetic rats, it was observed that the blood glucose concentration (BGC) decreased remarkably within 30 min, and the desired effect of insulin was maintained for an additional 3 h after the removal of insulin from the skin surface. The bird-bill MN was able to load a coating gel at a maximum capacity of 3.20 ± 0.21 mg per MN array, and the BGC continued to decrease significantly after MN application for up to 2-6 h. In summary, we fabricated semi-hollow and bird-bill MN arrays using the injection molding method; these can be mass produced and are capable of effectively producing micro-holes in the stratum corneum. The two MN arrays could provide effective transdermal delivery of large-molecular-weight drugs such as insulin.

Association between nutrient intake and telomere length in Japanese female university students.

OBJECTIVE: Telomere length can be a biomarker of cumulative oxidative stress and inflammation indicating biological aging. Previous studies examined association of nutrient intake with telomere length targeting middle-aged and elderly individuals. This study examined whether dietary macro- and micronutrient intake was associated with telomere length in young females. METHODS: Seventy-four Japanese young females (median (interquartile range) age was 19 (19 - 20) years) participated. We estimated their intake of nutrients (energy, protein, fat, carbohydrate, essential elements, vitamins, fatty acids, and dietary fibre) using a semi-quantitative food frequency questionnaire and measured telomere length (T/S ratio, the ratio of telomere repeat copy number (T) to single-copy gene number (S)) of DNA extracted from blood by qPCR. The association between telomere length and tertiles of nutrient intake were analysed. RESULTS: The median (interquartile range) of telomere length was 0.70 (0.52 - 0.98). Vitamin A intake was positively associated with telomere length (tertile 1 vs. 2, coefficient [95% confidence interval] = 0.42 [0.12, 0.71]; tertile 1 vs. 3, coefficient [95% confidence interval] = 0.33 [0.04, 0.62]) after adjusting for covariates (age, BMI, passive smoking, and drinking). CONCLUSIONS: Our findings suggest that variation in vitamin A intake might influence telomere attrition in healthy individuals.

A 25 mg rectal dose of diclofenac for prevention of post-ERCP pancreatitis in elderly patients.

OBJECTIVES: A 50-100 mg rectal dose of diclofenac or indomethacin is recommended for prophylaxis of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP); however, limited data are available regarding the appropriate dose to prevent PEP in elderly patients. We aimed to evaluate the efficacy and safety of 25 mg diclofenac in preventing PEP in elderly patients. Material and methods: Overall, 276 patients with naive papilla, aged over 75 years, were included in the present study between April 2013 and March 2020. We retrospectively evaluated the risk of PEP in patients over 75 years, administered with or without 25 mg diclofenac 30 min before ERCP using inverse probability of treatment weighting (IPTW) analysis. Results: Patients were categorized into the diclofenac group (83 patients) or non-diclofenac group (193 patients). The incidence rate of PEP in the diclofenac group was significantly lower than that in the non-diclofenac group (4% vs. 14%, p = .01). Multivariate analysis revealed that 25 mg diclofenac was an independent protective factor against PEP in elderly patients aged over 75 years (odds ratio [OR] = 0.17; 95% confidence interval [CI] = 0.04-0.67; p = 0.01). This protective effect of diclofenac against PEP remained robust after IPTW analysis (OR = 0.11; 95% CI = 0.03-0.40; p = .001). No adverse events related to diclofenac were observed. Conclusion: Diclofenac (25 mg) was considered effective and safe for preventing PEP in elderly patients. Our results may provide a new strategy for preventing PEP in elderly patients.

Efficacy of early endoscopic intervention in pediatric pancreatic duct injury management.

BACKGROUND: The optimal management method for pediatric pancreatic trauma is controversial. Moreover, the efficacy of stent placement via endoscopic retrograde pancreatography (ERP) remains poorly documented. METHODS: The present, retrospective review of pediatric patients with pancreatic trauma was conducted from 2010 to 2020 at a single institution. RESULTS: Ten, male children with the median age of 9.5 years (range 4-14 years) with a grade I (n = 2), II (n = 4) or III (n = 4) pancreatic injury were identified. Of six of these patients in whom ERP was performed, four had a pancreatic duct injury (PDI). Pancreatic stent placement was performed in all the patients with ERP at a site proximal to the injury in four patients and across the injury in two patients. A pseudocyst or pancreatic fluid collection was detected in five patients, of these, two with a grade II injury were managed successfully with conservative therapy while three with PDI required surgery. In the four patients with PDI, only one in whom the stent was placed across the PDI was able to avoid surgery. CONCLUSION: Therapeutic ERP might be effective even if a patient has a PDI, therefore, early ERP should be considered as a treatment option.

Telomere length and urinary 8-hydroxy-2'-deoxyguanosine and essential trace element concentrations in female Japanese university students.

Telomere length is thought to be a biomarker of biological aging. This study examined whether telomere length was associated with urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of oxidative stress, and antioxidative trace elements in 73 female Japanese university students (age: 19.2 ± 0.7 years). We quantified 8-OHdG and selenium in urine by liquid chromatography-mass spectrometry and inductively coupled plasma-mass spectrometry, respectively. Telomere length and urinary concentrations of other essential trace elements (molybdenum, cobalt, and chromium) that were previously measured in the same study participants, were used in this study. We used multiple linear regression analysis to examine the associations of telomere length with urinary 8-OHdG and essential trace element concentrations (covariates: urinary cotinine concentration, age, BMI, and drinking status). The geometric means (geometric standard deviation) of 8-OHdG and selenium were 3.4 (1.5) and 31 (1.3) µg/g creatinine, respectively. Telomere length was not associated with urinary 8-OHdG concentration, but was negatively associated with urinary selenium concentration. In conclusion, telomere length was not associated with urinary 8-OHdG concentration in the young women in this study. Longitudinal studies should be conducted to clarify the association between telomere shortening rate and oxidative stress level.

Associations between urinary heavy metal concentrations and blood pressure in residents of Asian countries.

BACKGROUND: Previous studies have suggested that exposures to heavy metals (arsenic, cadmium, lead, and selenium) may be associated with differences in blood pressure. However, the findings of these studies have been inconsistent. This study was performed to examine the associations between urinary heavy metal concentrations and blood pressure among residents of four Asian countries (Bangladesh, Indonesia, Nepal, and Vietnam). METHODS: This cross-sectional study examined 1899 adults in four Asian countries. Urinary concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry. A questionnaire survey was administered regarding individual characteristics. Anthropometric measurements (height and weight) were performed. Systolic and diastolic blood pressures were measured after a short rest. Multiple linear regression models were applied to investigate associations between urinary heavy metal concentrations and blood pressure after adjustments for age, sex, and body mass index. RESULTS: The geometric means of the urinary concentrations of arsenic, cadmium, lead, and selenium were 84.6, 0.885, 2.09, and 16.5 µg/g creatinine, respectively. The urinary arsenic concentrations were slightly higher than those typically reported in non-polluted populations, while urinary cadmium, lead, and selenium concentrations were equivalent or slightly lower. The urinary lead concentrations were positively associated with both systolic and diastolic blood pressure, but urinary selenium concentrations were negatively associated with them. CONCLUSIONS: Variations in the urinary concentrations of lead and selenium were associated with blood pressure at low levels of exposure/intake.

Renal Handling of 99mTc-Labeled Antibody Fab Fragments with a Linkage Cleavable by Enzymes on Brush Border Membrane.

The high and persistent renal radioactivity levels after injection of radiolabeled low-molecular-weight polypeptides constitute a significant problem for their diagnostic and therapeutic applications, especially when they are labeled with metallic radionuclides. To improve the renal radioactivity levels of technetium-99m (99mTc)-labeled Fab fragments, a mercaptoacetyltriglycine (MAG3)-based new bifunctional chelating agent with a cleavable glycyl-phenylalanyl-lysine (GFK) linkage, MAG3-GFK-suc-TFP, was designed, synthesized, and evaluated. 99mTc-labeled Fab was obtained by reacting MAG3-GFK-Fab conjugate with 99mTc-glucarate. The GFK linkage remained stable in plasma but was cleaved by enzymes on the renal brush border membrane. The comparative biodistribution studies with indium-111 (111In)-labeled Fab using SCN-CHX-A″-DTPA showed that while both radiolabeled Fabs exhibited similar elimination rates from the blood, [99mTc]Tc-MAG3-GFK-Fab registered much lower renal radioactivity levels from 30 min post-injection onward due to the release and subsequent urinary excretion of [99mTc]Tc-MAG3-Gly. However, [99mTc]Tc-MAG3-GFK-Fab showed an increase in the intestinal radioactivity levels with the time that was not observed with 111In-labeled Fab. The analysis of the intestinal contents suggested the redistribution of [99mTc]Tc-MAG3-Gly to the intestine. The retrospective comparison of [99mTc]Tc-MAG3-GFK-Fab with the radiolabeled Fabs so far prepared under the identical concept suggested that some portion of [99mTc]Tc-MAG3-Gly was generated after the coated vesicle formation and they were excreted into the blood, and subsequently redistributed in the intestine via hepatobiliary excretion. In conclusion, MAG3-GFK-suc-TFP provided 99mTc-labeled Fabs that exhibit low renal radioactivity shortly after injection by the post-labeling procedure. The present study indicated that, contrary to our earlier proposal, the generation of the radiometabolites would proceed not only during the internalization process of the parental antibody fragments but also after coated vesicle formation. This study also showed that the intracellular behaviors of radiometabolites played crucial roles in the elimination rates and the routes of the radioactivity from the kidney.

Manipulating Pharmacokinetics of Purification-Free 99mTc-Labeled Bivalent Probes for In Vivo Imaging of Saturable Targets.

The accumulation of 99mTc-labeled probes targeting saturable systems of the body is hindered by the presence of a large excess of unlabeled ligands needed to ensure high radiochemical yields in a short reaction time. To address the issue, we recently reported a novel concept of a metal-coordination-mediated synthesis of a bivalent 99mTc-labeled probe from a monovalent ligand using d-penicillamine (Pen) as a chelating molecule and c(RGDfK) as a model targeting device. The Pen-conjugated c(RGDfK) via a hexanoate linkage (Pen-Hx-c(RGDfK)) provided a bivalent [99mTc]Tc-[(Pen-Hx-c(RGDfK))2 that possessed much higher integrin αvß3 binding affinity than Pen-Hx-c(RGDfK) and visualized a murine tumor without purification. However, high radioactivity levels were observed in the abdominal regions, which necessitated improved pharmacokinetics of the probes for practical applications. In this study, a pharmacokinetic (PK) modifier was introduced to manipulate the pharmacokinetics of the 99mTc-Pen2-based bivalent probe. The Hx linkage in Pen-Hx-c(RGDfK) was replaced with acetyl-d-serine-d-serine-glycine (Ac-ssG) or hexanoyl-d-serine-d-serine-d-serine (Hx-sss) to prepare Pen-Ac-ssG-c(RGDfK) or Pen-Hx-sss-c(RGDfK). Pen-Ac-ssG-c(RGDfK) impaired the complexation ability of Pen-Hx-c(RGDfK), and a monovalent 99mTc-labeled compound was generated at low ligand concentration. However, Pen-Hx-sss-c(RGDfK) provided the objective bivalent 99mTc-labeled probe in high radiochemical yields at a concentration similar to that of Pen-Hx-c(RGDfK). [99mTc]Tc-[Pen-Hx-sss-c(RGDfK)]2 also possessed stability and integrin αvß3 binding affinity similar to those of [99mTc]Tc-[Pen-Hx-c(RGDfK)]2. As a result, [99mTc]Tc-[Pen-Hx-sss-c(RGDfK)]2 exhibited tumor and abdominal radioactivity levels similar to and significantly lower than those of [99mTc]Tc-[Pen-Hx-c(RGDfK)]2. These findings indicate the incorporation of a tripeptide PK modifier to Pen-Hx-c(RGDfK) preserved the complexation ability and improved the pharmacokinetics of the resulting 99mTc-labeled bivalent probe without impairing the targeting ability. Thus, the [Pen-Hx-(PK modifier)-(targeting device)] would constitute a basic formulation for preparing the 99mTc-Pen2-based bivalent probes for imaging saturable targets of the body.

Tunable Direct Band Gap of ß-CuGaO2 and ß-LiGaO2 Solid Solutions in the Full Visible Range.

We synthesized solid solutions of ß-CuGaO2 and ß-LiGaO2 (i.e., ß-(Cu1- xLi x)GaO2) by partial ion exchange of Cu+ in ß-CuGaO2 with Li+ from LiCl in the composition range of 0 ≤ x ≤ 0.89. The energy band gap of ß-CuGaO2 (1.47 eV) increased linearly up to 3.0 eV with increasing Li content, covering the full visible range. The crystal structures of the solid solutions were analyzed using the Rietveld method. The structural distortions of the solid solutions with respect to the ideal binary wurtzite-type structure were relatively small because of the similar ionic radii of Li+, Cu+, and Ga3+. Based on a recently proposed hypothesis relating structural distortion to the nature of the band gap (i.e., direct or indirect), it is expected that the solid solution has a direct band gap. We anticipate that this solid solution system will contribute to the realization of oxide-based optoelectronic devices.

Chiral Supramolecular Nanoarchitectures from Macroscopic Mechanical Rotations: Effects on Enantioselective Aggregation Behavior of Phthalocyanines.

Fluid dynamics, resulting from the macroscopic mechanical rotation of either a rotary evaporator or a magnetic stirrer, has been shown to selectively induce one of two enantiomers (mirror-image structures) in certain nanoscale supramolecules. As an alternative to giving a chiral twist to synthesized supramolecules or polymers, it is a challenge to reproducibly prepare chiral species by only using macroscopic mechanical rotations. Demonstrated here is a highly reproducible method for rotary-evaporation-induced enantioselective H-aggregation of achiral phthalocyanines. Chiral induction mechanisms are proposed by using the chiroptical-sign-based absolute structures. These results will provide insight to the origin of the homochirality of life, and serves as a pioneering study in a novel scientific field in terms of admixing nanoscale molecular chemistry and macroscopic fluid dynamics.

Coordination-Mediated Synthesis of 67Ga-Labeled Purification-Free Trivalent Probes for in Vivo Imaging of Saturable Systems.

A large excess of unlabeled ligands over gallium-67 (67Ga) provides 67Ga-labeled probes with high radiochemical yields in a short reaction time. However, the unlabeled ligands hinder target accumulation of radiolabeled probes by competing for target molecules. To circumvent the problem, we investigated the way to prepare 67Ga-labeled multivalent probes from monovalent ligands. The reaction of a bi- or tridentate ligand with [67Ga]Ga-citrate resulted in 67Ga-labeled probes of insufficient stability. However, the reaction of [67Ga]Ga-citrate with a mixture of RGD-conjugated salicylaldehyde and triamine provided a 67Ga-labeled trivalent probe with stability sufficient for in vivo applications. Since the free Schiff base ligand decomposed rapidly upon injection, the 67Ga-labeled trivalent probe visualized the murine tumor without postlabeling purification, which was not achieved with a 67Ga-labeled trivalent probe from a trivalent ligand. These findings indicate the availability of Schiff base ligands to prepare 67Ga-labeled trivalent probes by a simple radiolabeling procedure.

Coordination-Mediated Synthesis of Purification-Free Bivalent 99mTc-Labeled Probes for in Vivo Imaging of Saturable System.

In the synthesis of technetium-99m (99mTc) labeled target-specific ligands, the presence of a large excess of unlabeled ligands over 99mTc in the injectate hinders target accumulation of 99mTc-labeled ligands by competing for target molecules. To circumvent the problem, we recently developed a concept of the metal coordination-mediated multivalency, and proved the concept with a 99mTc-labeled trivalent compound [99mTc(CO)3(CN-RGD)3]+. In this study, D-penicillamine (Pen) was selected as a chelating molecule and a cyclic RGDfK peptide was conjugated to Pen via a hexanoic linkage (Pen-Ahx-c(RGDfK)). 99mTc complexation reaction, and the stability, integrin αvß3 binding affinity, and biodistribution of the 99mTc-labeled probe were investigated to evaluate the applicability of the concept to bivalent probes. 99mTc-[Pen-Ahx-c(RGDfK)]2 was obtained over 95% radiochemical yields under low Pen-Ahx-c(RGDfK) concentration (50 µM). 99mTc-[Pen-Ahx-c(RGDfK)]2 showed approximately 10-times higher integrin αvß3 binding affinity than the monovalent compounds, Pen-Ahx-c(RGDfK) and c(RGDyV). In biodistribution studies, the tumor accumulation of 99mTc-[Pen-Ahx-c(RGDfK)]2 was decreased to 77% and 43% of HPLC-purified (Pen-Ahx-c(RGDfK)-free) 99mTc-[Pen-Ahx-c(RGDfK)]2 by the presence of 5 nmol of unlabeled Pen-Ahx-c(RGDfK) and Re-[Pen-Ahx-c(RGDfK)]2, respectively. 99mTc-[Pen-Ahx-c(RGDfK)]2 provided tumor image without removing unlabeled ligand, while a 99mTc-labeled monovalent probe prepared from a monovalent ligand could not. These findings indicate the availability of the design concept to prepare 99mTc-labeled bivalent probes with a variety of 99mTc core and other metallic radionuclides of clinical relevance.

Uveitis induced by programmed cell death protein 1 inhibitor therapy with nivolumab in metastatic melanoma patient.

Nivolumab, a new immune checkpoint inhibitor, binds to programmed cell death-protein 1 receptors on T cell, blockades binding of its ligands, and augments the immunologic reaction against tumor cells. Augmented immune response, however, may lead to immune-related adverse events. Herein we describe a rare case of bilateral anterior uveitis induced by nivolumab treatment for metastatic melanoma. A 54-year-old woman presented with mild conjunctival redness and blurred vision two months after initiating nivolumab treatment. Ophthalmological examination revealed bilateral non-granulomatous anterior uveitis. The flare values in the anterior chamber were monitored as an objective inflammatory index during nivolumab therapy and clinical time course was reported in this paper.