"Click-to-Clear": A Strategy to Minimize Radioactivity from the Blood Pool Utilizing Staudinger Ligation.

The availability of several bioorthogonal reactions that can proceed selectively and efficiently under physiologically relevant conditions has garnered the interest of biochemists and organic chemists alike. Bioorthogonal cleavage reactions represent the latest innovation in click chemistry. Here, we employed the Staudinger ligation reaction to release radioactivity from immunoconjugates, improving target-to-background ratios. In this proof-of-concept study, model systems, including the anti-HER2 antibody trastuzumab, radioisotope I-131, and a newly synthesized bifunctional phosphine, were used. Staudinger ligation occurred when biocompatible N-glycosyl azides reacted with this radiolabeled immunoconjugate, leading to cleavage of the radioactive label from the molecule. We demonstrated this click cleavage in vitro and in vivo. Biodistribution studies in tumor models showed that radioactivity was eliminated from the bloodstream, thereby improving tumor-to-blood ratios. SPECT imaging revealed that tumors could be visualized with enhanced clarity. Our simple approach represents a novel application of bioorthogonal click chemistry in the development of antibody-based theranostics.

Phenolic acids and flavonoids from Salvia plebeia and HPLC-UV profiling of four Salvia species.

We isolated and purified phenolic acids and flavonoids from the ethanolic extract of Salvia plebeia using silica gel and a Sephadex LH-20 column chromatography. Spectroscopy revealed the isolated compounds were caffeic acid, rosmarinic acid, hispidulin, luteolin, jaceosidin, nepitrin, homoplantaginin, 6-hydroxyluteolin 7-O-glucoside, 6-methoxynaringenin 7-O-glucoside, naasanone, and cosmosiin. Quantitative analyses, using high-performance liquid chromatography coupled with UV (HPLC-UV), revealed that the major flavonoid from S. plebeia was 6-hydroxyluteolin 7-O-glucoside (100.63 mg/g) and the most abundant phenolic acid was rosmarinic acid (47.73 mg/g). Furthermore, among four other Salvia species, S. officinalis contained the highest overall phenolic acid and flavonoid level but these were still lower than S. plebeia. These results can help assess the potential of phenolic acids and flavonoids as potent sources of pharmacological ingredients from different Salvia species extracts.

Fish Collagen Peptide (NaticolⓇ) Protects the Skin from Dryness, Wrinkle Formation, and Melanogenesis Both In Vitro and In Vivo.

Consistent ultraviolet B (UVB) radiation exposure results in dry skin, wrinkles, and melanogenesis. In this study, we investigated whether fish collagen peptide (NaticolⓇ) could inhibit photoaging and oxidative stress in skin exposed to UVB using cell and animal models. We measured the skin hydration, histological observations, antioxidant activities, moisturizing-related factors, collagen synthesis-related factors, and melanogenesis-related factors in skin cells and animal skin using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blot assay. NaticolⓇ collagen improved skin moisturization via hyaluronic acid and ceramide synthesis-related factors in HaCaT cells and SHK-I hairless mice that were exposed to UVB. In addition, NaticolⓇ collagen inhibited wrinkle formation in Hs27 cells and SHK-I hairless mice exposed to UVB and restrained melanogenesis in 3-isobutyl-1-methylxanthine-induced B16F10 cells and UVB-irradiated SHK-I hairless mice. On the basis of these findings, we propose that ingestion of Naticol Ⓡ collagen might be valuable for preventing skin photoaging.

Diacerein, an inhibitor of IL-1ß downstream mediated apoptosis, improves radioimmunotherapy in a mouse model of Burkitt's lymphoma.

Lymphoma has the characteristics of a solid tumor. Penetration of monoclonal antibodies is limited in solid tumors during radioimmunotherapy (RIT). Here, we first investigated the use of diacerein (DIA) as a combination drug to improve the penetration and therapeutic efficacy of 131I-rituximab (RTX) using the Burkitt's lymphoma mouse model. We selected DIA through computational drug repurposing and focused on rheumatoid arthritis (RA) drug interaction genes to minimize side effects. Then, the cytotoxicity of DIA was assessed in vitro using three different lymphoma cell lines. DIA-induced apoptosis was confirmed by Western blotting. After confirming apoptosis, we confirmed the enhanced uptake of 131I-RTX in Burkitt's lymphoma mouse model using SPECT/CT. Autoradiography of 131I-RTX confirmed the therapeutic effect of DIA. Finally, the tumor size and survival rate were assessed to measure the enhanced therapeutic efficacy when DIA was used. In addition, we assessed the dose-dependency of DIA in terms of the accumulation of 131I-RTX in tumor tissue, the tumor size, and the survival rate. The in vitro cytotoxicity was 10.9%. We showed that DIA induced apoptosis which was related to downstream IL-1ß signaling by Western blotting. We found increased Annexin V positive apoptosis after DIA administration. Immuno SPECT/CT images demonstrated a higher uptake of 131I-RTX in tumors in the DIA-administered group than that in the PBS-alone group. However, there were no statistical differences of dose-dependency between 20 mg/kg and 40 mg/kg of DIA. Tumor growth was significantly inhibited in the group treated with the combination of DIA plus 131I-RTX at 7 days after injection. Our suggested combination of DIA and 131I-RTX strategies could enhance the efficacy of 131I-RTX treatment.

Inhibition of HIF-1α by Atorvastatin During 131I-RTX Therapy in Burkitt's Lymphoma Model.

BACKGROUNDS: Radioimmunotherapy (RIT) serves as a targeted therapy for non-Hodgkin lymphomas (NHL). Although HIF(Hypoxia-inducible factors)-1α is an important biomarker during radiation therapy, its role in NHL is unclear. Atorvastatin (ATV) is used as a combination drug for chemotherapy. METHODS: We investigated whether ATV downregulated tumor radio-resistance and enhanced the anticancer effect of 131I-RTX (rituximab) in Raji xenograft mouse models. First, the increased uptake and enhanced therapeutic effect of 131I-RTX by ATV was confirmed using molecular imaging in Raji xenograft subcutaneous model and orthotropic model with SPECT and IVIS images. Second, we examined the profile of differentially expressed miRNAs using miRNA array. RESULTS: We found that miR-346 inhibited HIF-1α/VEGF (Vascular endothelial growth factor) during ATV combination therapy with 131I-RTX. The underlying mechanism of ATV involved induction of anti-angiogenesis and radiosensitivity by downregulating HIF-1α in Raji cells. CONCLUSION: Our findings suggested that combination therapy with ATV and 131I-RTX is a promising strategy for enhancing the potency of 131I-RTX therapy in poorly responding patients and those with radio-resistance.

Measurement of Tumor Pressure and Strategies of Imaging Tumor Pressure for Radioimmunotherapy.

Tumor interstitial pressure is a fundamental feature of cancer biology. Elevation in tumor pressure affects the efficacy of cancer treatment and results in the heterogenous intratumoral distribution of drugs and macromolecules. Monoclonal antibodies (mAb) play a prominent role in cancer therapy and molecular nuclear imaging. Therapy using mAb labeled with radionuclides-also known as radioimmunotherapy (RIT)-is an effective form of cancer treatment. RIT is clinically effective for the treatment of lymphoma and other blood cancers; however, its clinical use for solid tumor was limited because their high interstitial pressure prevents mAb from penetrating into the tumor. This pressure can be decreased using anti-cancer drugs or additional external therapy. In this paper, we reviewed the intratumoral pressure using direct tumor-pressure measurement strategies, such as the wick-in-needle and pressure catheter transducer method, and indirect tumor-pressure measurement strategies via magnetic resonance.

PET Evidence of the Effect of Donepezil on Cognitive Performance in an Animal Model of Chemobrain.

A considerable number of patients with breast cancer complain of cognitive impairment after chemotherapy. In this study, we showed that donepezil enhanced memory function and increased brain glucose metabolism in a rat model of cognitive impairment after chemotherapy using behavioral analysis and positron emission tomography (PET). We found that chemotherapy affected spatial learning ability, reference memory, and working memory and that donepezil improved these cognitive impairments. According to PET analysis, chemotherapy reduced glucose metabolism in the medial prefrontal cortex and hippocampus, and donepezil increased glucose metabolism in the bilateral frontal lobe, parietal lobe, and hippocampus. Reduced glucose metabolism was more prominent after treatment with doxorubicin than cyclophosphamide. Our results demonstrated the neural mechanisms for cognitive impairment after chemotherapy and show that cognition was improved after donepezil intervention using both behavioral and imaging methods. Our results suggested that donepezil can be employed clinically for the treatment of cognitive deficits after chemotherapy.

Comparison of Imaging Characteristics of (124)I PET for Determination of Optimal Energy Window on the Siemens Inveon PET.

Purpose. (124)I has a half-life of 4.2 days, which makes it suitable for imaging over several days over its uptake and washout phases. However, it has a low positron branching ratio (23%), because of prompt gamma coincidence due to high-energy γ-photons (602 to 1,691 keV), which are emitted in cascade with positrons. Methods. In this study, we investigated the optimal PET energy window for (124)I PET based on image characteristics of reconstructed PET. Image characteristics such as nonuniformities, recovery coefficients (RCs), and the spillover ratios (SORs) of (124)I were measured as described in NEMA NU 4-2008 standards. Results. The maximum and minimum prompt gamma coincidence fraction (PGF) were 33% and 2% in 350~800 and 400~590 keV, respectively. The difference between best and worst uniformity in the various energy windows was less than 1%. The lowest SORs of (124)I were obtained at 350~750 keV in nonradioactive water compartment. Conclusion. Optimal energy window should be determined based on image characteristics. Our developed correction method would be useful for the correction of high-energy prompt gamma photon in (124)I PET. In terms of the image quality of (124)I PET, our findings indicate that an energy window of 350~750 keV would be optimal.

Neuroprotective effects of bee venom phospholipase A2 in the 3xTg AD mouse model of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a severe neuroinflammatory disease. CD4(+)Foxp3(+) regulatory T cells (Tregs) modulate various inflammatory diseases via suppressing Th cell activation. There are increasing evidences that Tregs have beneficial roles in neurodegenerative diseases. Previously, we found the population of Treg cells was significantly increased by bee venom phospholipase A2 (bvPLA2) treatment in vivo and in vitro. METHODS: To examine the effects of bvPLA2 on AD, bvPLA2 was administered to 3xTg-AD mice, mouse model of Alzheimer's disease. The levels of amyloid beta (Aß) deposits in the hippocampus, glucose metabolism in the brain, microglia activation, and CD4(+) T cell infiltration were analyzed to evaluate the neuroprotective effect of bvPLA2. RESULTS: bvPLA2 treatment significantly enhanced the cognitive function of the 3xTg-AD mice and increased glucose metabolism, as assessed with 18F-2 fluoro-2-deoxy-D-glucose ([F-18] FDG) positron emission tomography (PET). The levels of Aß deposits in the hippocampus were dramatically decreased by bvPLA2 treatment. This neuroprotective effect of bvPLA2 was associated with microglial deactivation and reduction in CD4(+) T cell infiltration. Interestingly, the neuroprotective effects of bvPLA2 were abolished in Treg-depleted mice. CONCLUSIONS: The present studies strongly suggest that the increase of Treg population by bvPLA2 treatment might inhibit progression of AD in the 3xTg AD mice.

Standardized Herbal Formula PM012 Decreases Cognitive Impairment and Promotes Neurogenesis in the 3xTg AD Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a severe neurodegenerative disease for which there is currently no effective treatment. This study investigated whether treatment with the herbal formula PM012 would improve the cognitive function and the pathological features of AD in 3xTg-AD mice. The cognitive function of 3xTg-AD mice was assessed using the Morris water maze test and positron-emission tomography (PET) with 18 F-2 fluoro-2-deoxy-D-glucose ([F-18] FDG) neuroimaging. The levels of the amyloid beta (Aß) deposits in the hippocampus were evaluated by immunohistochemistry. Neurogenesis was assessed by quantitative labeling with the DNA marker bromodeoxyuridine (BrdU) and the newborn neuron marker doublecortin (DCX). PM012 treatment significantly ameliorated memory deficit in AD mice, as shown by shortened escape latencies and increased time spent in the target zone during probe tests. In addition, PM012 significantly decreased Aß deposits, up-regulated the expression of brain-derived neurotrophic factor (BDNF), increased neurogenesis, and improved brain glucose metabolism in the 3xTg-AD mice. These results suggest that PM012 could be a promising treatment for AD.

High doses of caffeine reduce in vivo osteogenic activity in prepubertal rats.

Caffeine adversely affects endochondral ossification during fetal skeletal growth, and results in increased incidence of delayed and abnormal fetal skeletal development. Chronic caffeine intake also decreases growth hormone secretion. Thus, it is conceivable that caffeine may disrupt bone growth during the peripubertal period. This study aimed to investigate the impact of high-caffeine consumption on bone growth throughout puberty. A total of 51 male rats (21 days old) were divided randomly into three groups: a control group and two groups fed caffeine via gavage with 120 and 180 mg kg(-1)  day(-1) for 4 weeks. After death, the final length and weight of leg bones were measured, and the tibia processed for histomorphometric analysis. Caffeine caused a significant decrease in body mass gain. This was accompanied with proportional decreases in lean body mass and body fat. In addition, bone mass and osteogenic activity in vivo were assessed using dual-energy X-ray absorptiometry and (18) F-NaF positron emission tomography. The results showed significant decreases of bone mass and in vivo osteogenic activity in the caffeine-fed groups. Rats fed with caffeine showed a significantly shorter and lighter tibia and femur and the vertebral column compared with controls. In addition, caffeine does not increase the width of the growth plates (GPs), it slows the rate at which the GP closes due to a slower rate of growth. These results demonstrated that caffeine altered osteogenic activity, leading to delayed peripubertal longitudinal bone growth and maturation. Given that osteogenic cells undergo dynamic changes in metabolic activity and that the pubertal growth spurt is mainly stimulated by growth hormone/insulin-like growth factor-1 and sex steroids during pubertal development, caffeine could suppress ossification by interfering with both physiological changes in hormonal secretion and osteogenic activity during this critical period. Further study will be needed to investigate the cellular/molecular mechanism by which caffeine affects osteogenesis using in vitro experimental models.

Validation of a postinjection transmission method for actual rat brain PET.

PURPOSE: Postinjection transmission positron emission tomography (PET) may be useful for shortening the total scan time. In this study, the effect of post-transmission scanning was assessed using PET on a phantom (NU4) and actual rat brain. METHODS: Transmission was performed using (57)Co for 15 min. After a 15-min pre-transmission scan, emission PET was performed in list mode for 1 h, followed by an additional 15-min post-transmission scan. To compare the pre-transmission and post-transmission results, we measured nonuniformity, the recovery coefficient, and the spillover ratio (SOR) using NU4 and rat phantoms. The authors also assessed cerebral glucose metabolism using (18)F-fluorodeoxyglucose (FDG) PET and the binding potential for (18)F-fluorinated N-3-fluoropropyl-2-ß-carboxymethoxy-3-ß-(4-iodophenyl)nortropane (FP-CIT) in rat brain for differences between pre-transmission and post-transmission scanning. RESULTS: Nonuniformity and the SORs for air and water were comparable on the pre-transmission and post-transmission scans. With FDG-PET, after attenuation and scatter corrections no differences were observed in the brain regions on the pre-transmission and post-transmission scans. With FP-CIT-PET, the binding potentials were also not significantly different. CONCLUSIONS: In the present study, we validated a post-transmission method for PET of the rat brain. Post-transmission PET was reliable, and the results were comparable to those of pre-transmission PET. Post-transmission PET eliminates the early tracer uptake time in the PET imaging, making it possible to determine uptake in the conscious subject, which may provide more realistic, "normal" metabolic measurements. Thus, post-transmission PET may be a useful option for increasing the number of subjects who can be evaluated.