The effects of dark chocolate on cognitive performance during cognitively demanding tasks: A randomized, single-blinded, crossover, dose-comparison study

Dark chocolate, rich in polyphenols, increases cerebral blood flow and improves cognitive function. This study aimed to determine whether the consumption of chocolate with a high concentration of polyphenols helps to maintain cognitive performance during cognitively demanding tasks. In this randomized, single-blinded, crossover, dose-comparison study, 18 middle-aged adults consumed two types of chocolate (25 g each), one with a high concentration (635.0 mg) and the other with a low concentration (211.7 mg) of cacao polyphenols, and performed a cognitive task requiring response inhibition and selective attention over two time periods (15-30 min and 40-55 min after consumption, respectively). Autonomic nerve function and subjective feelings, such as fatigue and concentration, were measured before food intake and after the second task to assess the participant's state. The results showed that the average reaction time between the first and second sessions was not significantly different for either high- or low-concentration chocolate consumption. However, the percentage of correct responses was similar in the first (96.7 %) and second (96.8 %) sessions for high-concentration chocolate consumption and significantly lower for low-concentration chocolate consumption in the second (96.4 %) session than in the first session (97.3 %). Autonomic nerve function showed a significant increase in sympathetic nerve activity after the second task with high-concentration chocolate consumption, while subjective feelings showed an increase in mental fatigue for both chocolate types but a significant decrease in concentration only after the second task with low-concentration chocolate consumption. These findings suggest that dark chocolate consumption contributes to the maintenance of performance and concentration in continuous and demanding cognitive tasks.

Relationship between Body Mass Index and Sarcopenia with Oral Function Decline in Older Japanese Patients Who Regularly Attend a General Dental Clinic

BACKGROUND AND OBJECTIVE

This study examined the relationship between body mass index (BMI) and sarcopenia with oral function decline in older patients as well as whether a combination of underweight BMI and sarcopenia was associated with decreased oral function in individuals with conservative restorative and prosthetic treatment for masticatory disorders.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study included 290 older Japanese patients who regularly attended a general dental clinic. A detailed examination of oral function, sarcopenia, and BMI according to the Asian Working Group for Sarcopenia 2019 criteria was conducted for patients aged 65 years. This study used odds ratios as an epidemiological measure in the cross-sectional survey.

RESULTS

Multinomial logistic regression analysis showed that the number of remaining teeth and tongue pressure was associated with both ideal and overweight BMI in individuals with sarcopenia when compared to healthy individuals. The underweight BMI plus sarcopenia group was associated with tongue and lip motor function [ka] sound test, swallowing function, and the presence of oral hypofunction.

DISCUSSION

Our findings indicated that various aspects of oral function were impaired in community-dwelling older adult Japanese patients with sarcopenia and underweight BMI. Notably, among older adults with sarcopenia, both obese and thin patients exist, suggesting that distinct pathophysiological mechanisms influence oral function.

CONCLUSION

The above findings support the hypothesis that the coexistence of sarcopenia and underweight BMI is associated with poor oral function. Regular oral function assessments and weight measurements in general dental practice can aid the prompt identification of sarcopenia and reduced swallowing function and can facilitate early intervention. The presence of sarcopenia and impaired swallowing function should be considered in patients with underweight BMI, reduced [ka] sound, and low tongue pressure following a thorough oral function examination.

International consensus on clinical use of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

PURPOSE

Presynaptic dopaminergic positron emission tomography (PET) imaging serves as an essential tool in diagnosing and differentiating patients with suspected parkinsonism, including idiopathic Parkinson's disease (PD) and other neurodegenerative and non-neurodegenerative diseases. The PET tracers most commonly used at the present time mainly target dopamine transporters (DAT), aromatic amino acid decarboxylase (AADC), and vesicular monoamine type 2 (VMAT2). However, established standards for the imaging procedure and interpretation of presynaptic dopaminergic PET imaging are still lacking. The goal of this international consensus is to help nuclear medicine practitioners procedurally perform presynaptic dopaminergic PET imaging.

METHOD

A multidisciplinary task group formed by experts from various countries discussed and approved the consensus for presynaptic dopaminergic PET imaging in parkinsonism, focusing on standardized recommendations, procedures, interpretation, and reporting.

CONCLUSION

This international consensus and practice guideline will help to promote the standardized use of presynaptic dopaminergic PET imaging in parkinsonism. It will become an international standard for this purpose in clinical practice.

Impact of deep learning on radiologists and radiology residents in detecting breast cancer on CT: a cross-vendor test study

AIM

To investigate the effect of deep learning on the diagnostic performance of radiologists and radiology residents in detecting breast cancers on computed tomography (CT).

MATERIALS AND METHODS

In this retrospective study, patients undergoing contrast-enhanced chest CT between January 2010 and December 2020 using equipment from two vendors were included. Patients with confirmed breast cancer were categorised as the training (n=201) and validation (n=26) group and the testing group (n=30) using processed CT images from either vendor. The trained deep-learning model was applied to test group patients with (30 females; mean age = 59.2 ± 15.8 years) and without (19 males, 21 females; mean age = 64 ± 15.9 years) breast cancer. Image-based diagnostic performance of the deep-learning model was evaluated with the area under the receiver operating characteristic curve (AUC). Two radiologists and three radiology residents were asked to detect malignant lesions by recording a four-point diagnostic confidence score before and after referring to the result from the deep-learning model, and their diagnostic performance was evaluated using jackknife alternative free-response receiver operating characteristic analysis by calculating the figure of merit (FOM).

RESULTS

The AUCs of the trained deep-learning model on the validation and test data were 0.976 and 0.967, respectively. After referencing with the result of the deep learning model, the FOMs of readers significantly improved (reader 1/2/3/4/5: from 0.933/0.962/0.883/0.944/0.867 to 0.958/0.968/0.917/0.947/0.900; p=0.038).

CONCLUSION

Deep learning can help radiologists and radiology residents detect breast cancer on CT.

Cacao Polyphenol-Rich Dark Chocolate Intake Contributes to Efficient Brain Activity during Cognitive Tasks: A Randomized, Single-Blinded, Crossover, and Dose-Comparison fMRI Study

Cacao polyphenol-enriched dark chocolate may have beneficial effects on human health, such as facilitating maintaining good performance in long-lasting cognitive tasks. This study examined the effects of dark chocolate intake on improving brain function during cognitive tasks using functional magnetic resonance imaging (fMRI). In this randomized, single-blinded, crossover, and dose-comparison study, 26 healthy middle-aged participants ingested dark chocolate (25 g) either with a low concentration (LC) (211.7 mg) or a high concentration (HC) (635 mg) of cacao polyphenols. Thereafter, their brain activities were analyzed during continuous and effortful cognitive tasks relevant to executive functioning using fMRI in two consecutive 15 min sessions (25 and 50 min after ingestion). We observed significant interaction effects between chocolate consumption and brain activity measurement sessions in the left dorsolateral prefrontal cortex and left inferior parietal lobule. After HC chocolate ingestion, these areas showed lower brain activity in the second session than in the first session; however, these areas showed higher activity in the second session after LC chocolate ingestion. These results suggest that cacao polyphenol-enriched dark chocolate enhances the efficient use of cognitive resources by reducing the effort of brain activity.

Predicting the BRAF mutation with pretreatment MRI radiomics features for melanoma brain metastases receiving Gamma Knife radiosurgery

AIM

To develop a model using radiomics features extracted from magnetic resonance imaging (MRI) images of Gamma Knife radiosurgery (GKRS) to predict the BRAF mutation in patients with melanoma brain metastases (MBM).

MATERIALS AND METHODS

Data of 220 tumours were classified into two groups. One was a group whose BRAF mutation was identified, and the other group whose BRAF mutation was not identified. We extracted 1,962 radiomics features from gadolinium contrast-enhanced T1-weighted MRI treatment-planning images. Synthetic Minority Over-sampling TEchnique (SMOTE) was performed to address the unbalanced data-related issues. A single-layer neural network (NN) was used to build predictive models with radiomics features. The sensitivity, specificity, accuracy, and the area under the curve (AUC) were evaluated to assess the model performance.

RESULTS

The prediction performance for the final evaluation without the SMOTE had an accuracy of 77.14%, a specificity of 82.44%, a sensitivity of 81.85%, and an AUC of 0.79. The application of SMOTE improved the prediction model to an accuracy of 83.1%, a specificity of 87.07%, a sensitivity of 78.82%, and an AUC of 0.82.

CONCLUSION

The current study showed the feasibility of generating a highly accurate NN model for the BRAF mutation prediction. The prediction performance improved with SMOTE. The model assists physicians to obtain more accurate expectations of the treatment outcome without a genetic test.

Regional neuroinflammation induced by peripheral infection contributes to fatigue-like symptoms: a [18F]DPA-714 positron emission tomography study in rats

Introduction

A series of symptoms, including fever, widespread pain, fatigue, and even ageusia, have frequently been reported in the context of various infections, such as COVID-19. Although the pathogenic mechanisms underlying an infection causing fever and pain have been well established, the mechanisms of fatigue induced by infection in specific brain regions remain unclear.

Methods

To elucidate whether and how the peripheral infection cause fatigue via regional neuroinflammation, we performed a brain-wide investigation of neuroinflammation in a peripheral pseudoinfection rat model using [18F]DPA-714 positron emission tomography (PET) imaging analysis, in which the polyriboinosinic: polyribocytidylic acid (poly I:C) was intraperitoneally injected.

Results

Transient fever lasting for several hours and subsequent suppression of spontaneous activity lasting a few days were induced by poly I:C treatment. Significant increase in plasma interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α were observed at 2 and 4 h following poly I:C treatment. PET imaging analysis revealed that the brain uptake of [18F]DPA-714 was significantly increased in several brain regions one day after poly I:C treatment, such as the dorsal raphe (DR), parvicellular part of red nucleus (RPC), A5 and A7 noradrenergic nucleus, compared with the control group. The accumulation of [18F]DPA-714 in the DR, RPC and A5 was positively correlated with subsequent fatigue-like behavior, and that in the A7 tended to positively correlate with fever.

Discussion

These findings suggest that peripheral infection may trigger regional neuroinflammation, which may cause specific symptoms such as fatigue. A similar mechanism might be involved in COVID-19.

Novel strategy of liver cancer treatment with modified antisense oligonucleotides targeting human vasohibin-2

Vasohihibin-2 (VASH2) is a homolog of vasohibin-1 (VASH1) and is overexpressed in various cancers. Vasohihibin-2 acts on both cancer cells and cancer microenvironmental cells. Previous analyses have shown that VASH2 promotes cancer progression and abrogation of VASH2 results in significant anticancer effects. We therefore propose VASH2 to be a practical molecular target for cancer treatment. Modifications of antisense oligonucleotide (ASO) such as bridged nucleic acids (BNA)-based modification increases the specificity and stability of ASO, and are now applied to the development of a number of oligonucleotide-based drugs. Here we designed human VASH2-ASOs, selected an optimal one, and developed 2',4'-BNA-based VASH2-ASO. When systemically administered, naked 2',4'-BNA-based VASH2-ASO accumulated in the liver and showed its gene-silencing activity. We then examined the effect of 2',4'-BNA-based VASH2-ASO in liver cancers. Intraperitoneal injection of naked 2',4'-BNA-based VASH2-ASO exerted a potent antitumor effect on orthotopically inoculated human hepatocellular carcinoma cells. The same manipulation also showed potent antitumor activity on the splenic inoculation of human colon cancer cells for liver metastasis. These results provide a novel strategy for the treatment of primary as well as metastatic liver cancers by using modified ASOs targeting VASH2.

Granular flow experiment using artificial gravity generator at International Space Station

Studying the gravity-dependent characteristics of regolith, fine-grained granular media covering extra-terrestrial bodies is essential for the reliable design and analysis of landers and rovers for space exploration. In this study, we propose an experimental approach to examine a granular flow under stable artificial gravity conditions for a long duration generated by a centrifuge at the International Space Station. We also perform a discrete element simulation of the granular flow in both artificial and natural gravity environments. The simulation results verify that the granular flows in artificial and natural gravity are consistent. Further, regression analysis of the experimental results reveals that the mass flow rate of granular flow quantitatively follows a well-known physics-based law with some deviations under low-gravity conditions, implying that the bulk density of the granular media decreases with gravity. This insight also indicates that the bulk density considered in simulation studies of space probes under low-gravity conditions needs to be tuned for their reliable design and analysis.

International Nuclear Medicine Consensus on the Clinical Use of Amyloid Positron Emission Tomography in Alzheimer's Disease

Alzheimer's disease (AD) is the main cause of dementia, with its diagnosis and management remaining challenging. Amyloid positron emission tomography (PET) has become increasingly important in medical practice for patients with AD. To integrate and update previous guidelines in the field, a task group of experts of several disciplines from multiple countries was assembled, and they revised and approved the content related to the application of amyloid PET in the medical settings of cognitively impaired individuals, focusing on clinical scenarios, patient preparation, administered activities, as well as image acquisition, processing, interpretation and reporting. In addition, expert opinions, practices, and protocols of prominent research institutions performing research on amyloid PET of dementia are integrated. With the increasing availability of amyloid PET imaging, a complete and standard pipeline for the entire examination process is essential for clinical practice. This international consensus and practice guideline will help to promote proper clinical use of amyloid PET imaging in patients with AD.

Caulerpa lentillifera improves ethanol-induced liver injury and modulates the gut microbiota in rats

Caulerpa lentillifera (CL), also called sea grape, is a type of edible green alga which was reported to have antioxidative and immunomodulatory potential. This study aimed to investigate the hepatoprotective effects of CL in a rat model of chronic ethanol exposure. Wistar rats were assigned to four groups and supplied with an isocaloric control liquid diet (group C), an ethanol liquid diet (group E), a control liquid diet supplemented with 5% CL (group CC), or an ethanol liquid diet supplemented with 5% CL (group EC) for a 12-week experimental period. Ethanol feeding induced steatosis, inflammation, and changes in the gut microbiota by the end of the study, whereas CL supplementation significantly improved liver injuries and decreased circulatory endotoxin levels. Moreover, we also found that CL reversed ethanol-induced elevation of hepatic toll-like receptor 4 (TLR4), MyD88 protein expression, the phosphorylated-nuclear factor (NF)-κB-to-NF-κB ratio, and proinflammatory cytokine concentrations. Additionally, CL also increased the abundance of Akkermansia and tight junction proteins and diminished the Firmicutes-to-Bacteroidetes ratio. Dietary CL inhibited the progression of alcoholic liver disease, and some of the possible mechanisms may be strengthening the intestinal barrier function, alleviating dysbiosis, and modulating the TLR4 pathway.

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at sqrt[s]=510 GeV in p[over →]+p[over →] Collisions

We present measurements of the cross section and double-helicity asymmetry A_{LL} of direct-photon production in p[over →]+p[over →] collisions at sqrt[s]=510  GeV. The measurements have been performed at midrapidity (|η|<0.25) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at sqrt[s]=510  GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range 0.02<x<0.08, with direct sensitivity to the sign of the gluon contribution.

In vitro evaluation of (S)-2-amino-3-[3-(2-18F-fluoroethoxy)-4-iodophenyl]-2-methylpropanoic acid (18F-FIMP) as a positron emission tomography probe for imaging amino acid transporters

BACKGROUND

(S)-2-amino-3-[3-(2-¹⁸F-fluoroethoxy)-4-iodophenyl]-2-methylpropanoic acid (¹⁸F-FIMP) as a promising PET probe for imaging the tumor-specific L-type amino acid transporter (LAT) 1. Our previous study revealed that ¹⁸F-FIMP had a higher affinity for LAT1 than for LAT2 abundantly expressed even in normal cells. ¹⁸F-FIMP showed high accumulation in LAT1-positive tumor tissues and low accumulation in inflamed lesions in tumor-bearing mice. However, the affinity of ¹⁸F-FIMP for other amino acid transporters was not determined yet. Here, we aimed to determine whether ¹⁸F-FIMP has affinity for other tumor-related amino acid transporters, such as sodium- and chloride-dependent neutral and basic amino acid transporter B(0 +) (ATB^0,+), alanine serine cysteine transporter 2 (ASCT2), and cystine/glutamate transporter (xCT).

PROCEDURES

Cells overexpressing LAT1, ATB^0,+, ASCT2, or xCT were established by the transfection of expression vectors for LAT1, ATB^0,+, ASCT2, or xCT. Protein expression levels were determined by western blot and immunofluorescent analyses. Transport function was evaluated by a cell-based uptake assay using ¹⁸F-FIMP and ¹⁴C-labeled amino acids as substrates.

RESULTS

Intense signals were observed only for expression vector-transfected cells on western blot and immunofluorescent analyses. These signals were strongly reduced by gene-specific small interfering ribonucleic acid treatment. The uptake values for each ¹⁴C-labeled substrate were significantly higher in the transfected cells than in the mock-transfected cells and were significantly inhibited by the corresponding specific inhibitors. The ¹⁸F-FIMP uptake values were significantly higher in the LAT1- and ATB^0,+-overexpressing cells than in the corresponding mock cells, but no such increase was seen in the ASCT2- or xCT-overexpressing cells. These ¹⁸F-FIMP uptake values were significantly decreased by the specific inhibitors for LAT1- and ATB^0,+.

CONCLUSIONS

We demonstrated that ¹⁸F-FIMP has affinity not only for LAT1, but also for ATB^0,+. Our results may be helpful for understanding the mechanisms of the whole-body distribution and tumor accumulation of ¹⁸F-FIMP.

Characteristic Evaluation of a 11C-Labeled Leucine Analog, l-α-[5-11C]methylleucine, as a Tracer for Brain Tumor Imaging by Positron Emission Tomography

Amino acid transporters are upregulated in many cancer cells, and system L amino acid transporters (LAT1-4), in particular, LAT1, which preferentially transports large, neutral, and branched side-chain amino acids, are considered a primary target for cancer positron emission tomography (PET) tracer development. Recently, we developed a ¹¹C-labeled leucine analog, l-α-[5-¹¹C]methylleucine ([5-¹¹C]MeLeu), via a continuous two-step reaction of Pd⁰-mediated ¹¹C-methylation and microfluidic hydrogenation. In this study, we evaluated the characteristics of [5-¹¹C]MeLeu and also compared the sensitivity to brain tumors and inflammation with l-[¹¹C]methionine ([¹¹C]Met) to determine its potential for brain tumor imaging. Competitive inhibition experiments, protein incorporation, and cytotoxicity experiments of [5-¹¹C]MeLeu were performed in vitro. Further, metabolic analyses of [5-¹¹C]MeLeu were performed using a thin-layer chromatogram. The accumulation of [5-¹¹C]MeLeu in tumor and inflamed regions of the brain was compared with [¹¹C]Met and ¹¹C-labeled (S)-ketoprofen methyl ester by PET imaging, respectively. Transporter assay with various inhibitors revealed that [5-¹¹C]MeLeu is mainly transported via system L amino acid transporters, especially LAT1, into A431 cells. The protein incorporation assay and metabolic assay in vivo demonstrated that [5-¹¹C]MeLeu was neither used for protein synthesis nor metabolized. These results indicate that MeLeu is very stable in vivo. Furthermore, the treatment of A431 cells with various concentrations of MeLeu did not change their viability, even at high concentrations (∼10 mM). In brain tumors, the tumor-to-normal ratio of [5-¹¹C]MeLeu was more elevated than that of [¹¹C]Met. However, the accumulation levels of [5-¹¹C]MeLeu were lower than those of [¹¹C]Met (the standardized uptake value (SUV) of [5-¹¹C]MeLeu and [¹¹C]Met was 0.48 ± 0.08 and 0.63 ± 0.06, respectively). In brain inflammation, no significant accumulation of [5-¹¹C]MeLeu was observed at the inflamed brain area. These data suggested that [5-¹¹C]MeLeu was identified as a stable and safe agent for PET tracers and could help detect brain tumors, which overexpress the LAT1 transporter.

Acute nicotine exposure blocks aromatase in the limbic brain of healthy women: A [11C]cetrozole PET study

BACKGROUND

Of interest to women's mental health, a wealth of studies suggests sex differences in nicotine addiction and treatment response, but their psychoneuroendocrine underpinnings remain largely unknown. A pathway involving sex steroids could indeed be involved in the behavioural effects of nicotine, as it was found to inhibit aromatase in vitro and in vivo in rodents and non-human primates, respectively. Aromatase regulates the synthesis of oestrogens and, of relevance to addiction, is highly expressed in the limbic brain.

METHODS

The present study sought to investigate in vivo aromatase availability in relation to exposure to nicotine in healthy women. Structural magnetic resonance imaging and two [¹¹C]cetrozole positron emission tomography (PET) scans were performed to assess the availability of aromatase before and after administration of nicotine. Gonadal hormones and cotinine levels were measured. Given the region-specific expression of aromatase, a ROI-based approach was employed to assess changes in [¹¹C]cetrozole non-displaceable binding potential.

RESULTS

The highest availability of aromatase was found in the right and left thalamus. Upon nicotine exposure, [¹¹C]cetrozole binding in the thalamus was acutely decreased bilaterally (Cohen's d = -0.99). In line, cotinine levels were negatively associated with aromatase availability in the thalamus, although as non-significant trend.

CONCLUSIONS

These findings indicate acute blocking of aromatase availability by nicotine in the thalamic area. This suggests a new putative mechanism mediating the effects of nicotine on human behaviour, particularly relevant to sex differences in nicotine addiction.

Two-Chain Mature Hepatocyte Growth Factor-Specific Positron Emission Tomography Imaging in Tumors Using 64Cu-Labeled HiP-8, a Nonstandard Macrocyclic Peptide Probe

Two-chain hepatocyte growth factor (tcHGF), the mature form of HGF, is associated with malignancy and anticancer drug resistance; therefore, its quantification is an important indicator for cancer diagnosis. In tumors, activated tcHGF hardly discharges into the systemic circulation, indicating that tcHGF is an excellent target for molecular imaging using positron emission tomography (PET). We recently discovered HGF-inhibitory peptide-8 (HiP-8) that binds specifically to human tcHGF with nanomolar affinity. The purpose of this study was to investigate the usefulness of HiP-8-based PET probes in human HGF knock-in humanized mice. ⁶⁴Cu-labeled HiP-8 molecules were synthesized using a cross-bridged cyclam chelator, CB-TE1K1P. Radio-high-performance liquid chromatography-based metabolic stability analyses showed that more than 90% of the probes existed in intact form in blood at least for 15 min. In PET studies, significantly selective visualization of hHGF-overexpressing tumors versus hHGF-negative tumors was observed in double-tumor-bearing mice. The accumulation of labeled HiP-8 into the hHGF-overexpressing tumors was significantly reduced by competitive inhibition. In addition, the radioactivity and distribution of phosphorylated MET/HGF receptor were colocalized in tissues. These results demonstrate that the ⁶⁴Cu-labeled HiP-8 probes are suitable for tcHGF imaging in vivo, and secretory proteins like tcHGF can be a target for PET imaging.

Comparison of [18F]FIMP, [11C]MET, and [18F]FDG PET for early-phase assessment of radiotherapy response

Several limitations of [¹⁸F]FDG have been reported, such as nonspecific uptake of inflammation foci. Moreover, [¹¹C]MET has been found to accumulate in normal and inflammatory tissues as well as tumors. To increase specificity to tumor tissues, PET probes with tumor-specific molecular targets have been actively developed. [¹⁸F]FIMP was found to be highly accumulated in LAT1-positive tumors but not in inflamed tissue. The aim of this study was to explore whether [¹⁸F]FIMP can be used for the early-phase evaluation of radiotherapy accompanied by inflammation, and compare its effectiveness with those of [¹¹C]MET and [¹⁸F]FDG. Tumor uptake of [¹⁸F]FIMP decreased at day 1 after irradiation, and remained low until day 14. Comparatively, that of [¹⁸F]FDG initially decreased at day 3 but was transiently elevated at day 7 and then decreased again at day 10. Decreased tumor uptake of [¹¹C]MET was observed at day 10. In line with the uptake of [¹⁸F]FIMP, the ratio of Ki-67 immuno-positive cells in tumor tissues significantly decreased at day 1, 7, and 10 as compared with that in the control. These findings suggest that [¹⁸F]FIMP may be a PET probe involved in the early detection and prediction of radiotherapy efficacy, although further clarification is needed.

Impact of tumoral structure and bacterial species on growth and biodistribution of live bacterial therapeutics in xenografted tumours

Live bacterial therapeutics is gaining attention, especially for cancer therapy, because anaerobic bacteria selectively grow inside the solid tumours. However, the effect of tumour structure and bacterial characteristics on the pharmacokinetics of tumours is unclear; therefore, we aimed to elucidate the effects of tumour structure and types of bacteria on tumoral bacterial growth. Using six mouse xenograft models, including stroma-rich tumours similar to clinical tumours, and two models of live bacterial therapeutics, Salmonella typhimurium VNP20009 and Escherichia coli DH5α, we investigated bacterial growth and distribution in tumours after intravenous administration. Rapid growth of E. coli was observed in HCT116 and other tumours with few collagens, blood vessels not covered by mural cells, and a cancer cell area proliferated disorderly, whereas tumours with contrasting features, such as BxPC-3, showed lower bacterial growth and a limited intratumor distribution. Alternatively, Salmonella typhimurium VNP20009, when successfully proliferated (the probability was approximately 50%), grew to 10⁸ colony forming units/g tissue even in BxPC-3 tumours, and its intratumor distribution was extensive. This study suggests that the development of new methods to modify tumour structure will be essential for the development of anti-tumour clinical therapies based on live bacterial therapeutics.

The Association between Atherosclerotic Disease Risk Factors and Serum 25-Hydroxyvitamin D Concentration in Japanese Subjects

Recent studies have described that vitamin D deficiency/insufficiency is associated with hypertension, insulin resistance, and dyslipidemia, which are major components of metabolic syndrome causing atherosclerosis. Therefore, we investigated the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentration and atherosclerotic disease risk factors in healthy Japanese adults. In the present cross-sectional study, 1,177 subjects (348 males and 829 females) aged 20-72 y living in Japan (34.7-35.0ºN) were evaluated for vitamin D status by measuring serum 25(OH)D concentration. Atherosclerotic disease risk factors were defined as the presence of two or more of the following three risk factors: high blood pressure, dyslipidemia, and hyperglycemia. The percentages of vitamin D deficient and insufficient subjects were 33% and 46% in males and 59% and 32% in females, respectively. Subjects with atherosclerotic disease risk factors were significantly older and had higher BMI than those without it in both sexes. Male subjects with atherosclerotic disease risk factors had significantly lower physical activity and serum 25(OH)D concentration than those without it. In a logistic regression analysis adjusted for confounding factors, serum 25(OH)D concentration showed a significant inverse association with risk factors of atherosclerotic disease in males (OR=0.951, 95%CI: 0.906-0.998), but not in females. A covariance structure analysis also suggested that serum 25(OH)D level has a direct association with risk factors of atherosclerotic disease. In conclusion, we have demonstrated that low serum 25(OH)D level is a significant factor for increased atherosclerotic disease risk factors in males.

Dose-Response Relationships between Diet Quality and Mortality among Frail and Non-Frail Older Adults: A Population-Based Kyoto-Kameoka Prospective Cohort Study

OBJECTIVES

Although better diet quality is inversely associated with mortality risk, the association between diet quality and mortality remains unclear in frail and non-frail older adults. Thus, we aimed to examine this association in older Japanese adults.

DESIGN

A prospective cohort study.

SETTING AND PARTICIPANTS

We used the data of 8,051 Japanese older adults aged ≥65 years in the Kyoto-Kameoka study.

MESUREMENTS

Dietary intake was estimated using a validated food frequency questionnaire. Diet quality was evaluated by calculating the adherence scores to the Japanese Food Guide Spinning Top (range, 0 [worst] to 80 [best]), which were stratified into quartiles. Frailty status was assessed using the validated self-administered Kihon Checklist (KCL) and the Fried phenotype (FP) model. Survival data were collected between February 15, 2012 and November 30, 2016. Statistical analysis was performed using the multivariate Cox proportional hazard analysis and the spline model.

RESULTS

During the median 4.75-year follow-up (36,552 person-years), we recorded 661 deaths. After adjusting for confounders, compared with the bottom adherence score quartile, the top quartile was associated with lower hazard ratio (HR) of mortality in frailty (HR, 0.73; 95% confidence interval [CI], 0.54-1.00) and non-frailty, as defined by the KCL (HR, 0.72; 95% CI, 0.52-1.01). In the spline model, regardless of frailty status defined by the KCL and FP model, adherence score showed a strongly dose-dependent inverse association with mortality up to approximately 55 points; however, no significant differences were observed thereafter. This association was similar to the results obtained in individuals with physical, cognitive, and depression as domains of KCL in the spline model.

CONCLUSIONS

Our findings demonstrate an L-shaped association between diet quality and mortality in both frail and non-frail individuals. This study may provide important knowledge for improving poor diet quality in older individuals with frailty or domains of frailty.

Lasso peptide microcin J25 variant containing RGD motif as a PET probe for integrin a v ß 3 in tumor imaging

Microcin J25 (MccJ25), a lasso peptide, has a unique 3-D interlocked structure that provides high stability under acidic conditions, at high temperatures, and in the presence of proteases. In this study, we generated a positron emission tomography (PET) probe based on MccJ25 analog with an RGD motif and investigated their pharmacokinetics and utility for integrin α_vβ₃ imaging in tumors. The MccJ25 variant with an RGD motif in the loop region and a lysine substitution at the C-terminus (MccJ25(RGDF)GtoK) was produced in E. coli transfected with plasmid DNA containing the MccJ25 biosynthetic gene cluster (mcjABCD). [⁶⁴Cu]Cu-MccJ25(RGDF)GtoK was synthesized using the C-terminal lysine labeled with copper-64 (t_1/2 = 12.7 h) via a bifunctional chelator; it showed stability in 90% mouse plasma for 45 min. Using PET imaging for integrin α_vβ₃ positive U87MG tumor bearing mice, [⁶⁴Cu]Cu-MccJ25(RGDF)GtoK could clearly distinguish the tumor, and its accumulation was significantly higher than that of MccJ25(GIGT)GtoK without the binding motif for integrin α_vβ₃. Furthermore, MccJ25(RGDF)GtoK enabled visualization of only U87MG tumors but not MCF-7 tumors with low integrin α_vβ₃ expression in double tumor-bearing mice. In ex vivo biodistribution analysis, the integrin α_vβ₃ non-specific accumulation of [⁶⁴Cu]Cu-MccJ25(RGDF)GtoK was significantly lower in various tissues, except for the kidneys, as compared to the control probe ([⁶⁴Cu]Cu-cyclic RGD peptide). These results of the present study indicate that ⁶⁴Cu-labeling methods are appropriate for the synthesis of MccJ25-based PET probes, and [⁶⁴Cu]Cu-MccJ25 variants are useful tools for cancer molecular imaging.

N-Methylamide-structured SB366791 derivatives with high TRPV1 antagonistic activity: toward PET radiotracers to visualize TRPV1

Transient receptor potential cation channel subfamily V member 1 (TRPV1)-targeted compounds were synthesized by modifying the structure of SB366791, a pharmaceutically representative TRPV1 antagonist. To avoid amide-iminol tautomerization, structurally supported N-methylated amides (i.e., 3-alkoxy-substitued N-meythylamide derivatives of SB366791) were evaluated using a Ca2+ influx assay, in which cells expressed recombinant TRPV1 in the presence of 1.0 μM capsaicin. The antagonistic activities of N-(3-methoxyphenyl)-N-methyl-4-chlorocinnamamide (2) (RLC-TV1004) and N-{3-(3-fluoropropoxy)phenyl}-N-methyl-4-chlorocinnamamide (4) (RLC-TV1006) were found to be approximately three-fold higher (IC50: 1.3 μM and 1.1 μM, respectively) than that of SB366791 (IC50: 3.7 μM). These results will help reinvigorate the potential of SB366791 in medicinal chemistry applications. The 3-methoxy and 3-fluoroalkoxy substituents were used to obtain radioactive [11C]methoxy- or [18F]fluoroalkoxy-incorporated tracers for in vivo positron emission tomography (PET). Using the 11C- or 18F-labeled derivatives, explorative PET imaging trials were performed in rats.

Contribution of dental health in cardiovascular secondary prevention

Backgrounds

Previous studies have suggested that periodontitis is associated with cardiovascular disease (CVD), partly through exaggerated systematic inflammation through pathogens breaking into the bloodstream and their metabolic products. However, the clinical evidence in the cardiovascular secondary prevention is limited. In addition, there is a paucity of data about the contribution of comprehensively assessed dental health, including dental caries or teeth loss, to CVD incidence. Consequently, current ESC guideline for CVD prevention just briefly refers the contribution of dental health [1].

Objective

To investigate the associations between teeth loss, periodontitis, and dental caries and incident major adverse cardiovascular events (MACE) in patients with existing CVD.

Methods

Patients with known CVD who were admitted to the Department of Cardiology between May 2012 and August 2015 were prospectively, consecutively enrolled. Patients underwent comprehensive dental examinations, including counts of lost teeth, dental caries, and periodontal measurements of clinical attachment loss (CAL), periodontal probing pocket depth (PPD), and bleeding on probing (BOP) by trained periodontists during the hospital stay. We assessed the associations between these dental measures and MACE, defined as a composite of cardiac death, acute myocardial infarction, stroke, and hospital re-admission for worsened congestive heart failure, using multivariate COX proportional hazard models and restricted mean survival time (RMST) analyses. P-values were adjusted by Bonferroni methods.

Results

Among 888 patients included for the present analyses, the mean age was 63.9 (SD: 13.1) years and there were 242 (27.3%) women. During a median follow-up of 4.6 (IQR: 1.4, 6.7) years, incident MACE was confirmed in 142 patients. In multivariate COX proportional hazard models, one more tooth loss was associated with 3 (95% CI: 1, 5) % higher hazard of MACE (adjusted p=0.020). Kaplan-Meier curves showing survival from MACE according to the quartiles of teeth loss were described in Figure 1. Compared with patients with 0 to ≤4 lost teeth, periods free from MACE (95% CI) by 5-years of follow-up were on average shorter by 0.17 (−0.04, 0.37) years, 0.26 (0.04, 0.49) years, and 0.59 (0.34, 0.85) years in patients with 5 to ≤7, 8 to ≤13, and &gt;13 lost teeth, respectively. The RMST differences with varied cutoff years were shown in Figure 2. There were no significant associations between the number of dental caries, CAL, PPD, and BOP and MACE incidence.

Conclusion

In hospitalized patients due to existing cardiovascular diseases, total number of lost teeth was associated with incident MACE. Given that teeth loss is an ultimate consequence of periodontitis or dental caries, the present findings imply that efforts to prevent losing teeth by maintaining dental health would be effective measures for cardiovascular secondary prevention.

Funding Acknowledgement

Type of funding sources: None.

Prevalence and Associated Risk Factors of Urinary Schistosomiasis among Primary School Pupils in the Jidawa and Zobiya Communities of Jigawa State, Nigeria

Background

Urogenital schistosomiasis (UgS) is a parasitic disease caused by Schistosoma haematobium and can lead to chronic ill-health. Nigeria is endemic for schistosomiasis, but epidemiology of UgS has not been studied in most states. This study was conceived with the aim to contribute towards an accurate national picture of UgS in Nigeria. The prevalence of UgS and the associated risk factors were for the first time investigated among primary school pupils in Jidawa and Zobiya communities of the Dutse Local Government Area (LGAs) of Jigawa State, Nigeria.

Method

Focus group discussions with teachers and parents were conducted. After obtaining written consent from parents, questionnaires were administered to pupils to obtain socio-demographic data and information on water contact activities. Urine samples (279) were collected and processed by the urine filtration technique to evaluate haematuria and the presence of S. haematobium eggs.

Results

Prevalences of 65.7% (90/137) and 69.0% (98/142) were recorded in the Jidawa and Zobiya communities, respectively. In both communities, there was a significant association between gender and UgS: 63.3% of the infected pupils were males as compared to 36.7% females (χ2 = 5.42, p = 0.020). Grade 5 students had a significantly higher prevalence (χ2 = 17.919, p = 0.001) (80.0%) compared to those in grades 2, 3, 4, and 6 (63.8%, 66.7%, 61.5%, and 64.6%, respectively). Water contact activities showed that pupils involved in fishing, irrigation, and swimming were at greater risk of becoming infected in Jidawa and Zobiya, with odds ratios (risk factors) of 5.4 (0.994-28.862) and 4.1 (1.709-9.862), respectively (p = 0.05).

Conclusion

Both the Jidawa and Zobiya communities of the Dutse LGAs of Jigawa State are hyperendemic for UgS. In collaboration with the State Ministry of Health, mass administration of praziquantel was carried out in the Jidawa and Zobiya communities after this study.

Lysophosphatidic acid receptor type-1 mediates brain activation in micro-Positron Emission Tomography analysis in a fibromyalgia-like mouse model

The intermittent cold stress-induced generalized pain response mimics the pathophysiological and pharmacotherapeutic features reported for fibromyalgia patients, including the presence of chronic generalized pain and female dominance. In addition, the intermittent cold stress-induced generalized pain is abolished in lysophosphatidic acid receptor type-1 knockout mice, as reported in many cases of neuropathic pain models. This study aimed to identify the brain loci involved in the intermittent cold stress generalized pain response and test their dependence on the lysophosphatidic acid receptor type-1. Positron emission tomography analyses using 2-deoxy-2-[¹⁸ F]fluoro-D-glucose in the presence of a pain stimulus showed that intermittent cold stress causes a significant increase in uptake in the ipsilateral regions, including the salience networking-related anterior cingulate cortex and insular cortex and the cognition-related hippocampus. A significant decrease was observed in the default mode network-related posterior cingulate cortex. Almost these intermittent cold stress-induced changes were abolished in lysophosphatidic acid receptor type-1 knockout mice. There results suggest that the intermittent cold stress-induced generalized pain response is mediated by the lysophosphatidic acid receptor type-1 in specific brain loci related to salience networking and cognition, which may lead to further developments in the treatment of fibromyalgia.

International consensus on the use of tau PET imaging agent 18F-flortaucipir in Alzheimer's disease

Purpose

Positron emission tomography (PET) with the first and only tau targeting radiotracer of ¹⁸F-flortaucipir approved by FDA has been increasingly used in depicting tau pathology deposition and distribution in patients with cognitive impairment. The goal of this international consensus is to help nuclear medicine practitioners procedurally perform ¹⁸F-flortaucipir PET imaging.

Method

A multidisciplinary task group formed by experts from various countries discussed and approved the consensus for ¹⁸F-flortaucipir PET imaging in Alzheimer’s disease (AD), focusing on clinical scenarios, patient preparation, and administered activities, as well as image acquisition, processing, interpretation, and reporting.

Conclusion

This international consensus and practice guideline will help to promote the standardized use of ¹⁸F-flortaucipir PET in patients with AD. It will become an international standard for this purpose in clinical practice.

Fibronectin plays a major role in hypoxia-induced lenvatinib resistance in hepatocellular carcinoma PLC/PRF/5 cells

Resistance to lenvatinib mesylate (LEN), a systemic chemotherapy that can be administered orally, has been a major issue for treatment of hepatocellular carcinoma (HCC). Although HCC is the tumor that most exhibits intratumoral hypoxia, which has been shown to be involved in the development of treatment resistance, there are no reports of LEN resistance in HCC treatment under hypoxia. The purpose of our study was to elucidate the mechanism of treatment resistance to LEN under hypoxia using HCC cell lines. We confirmed LEN resistance under hypoxic conditions in HCC cell lines. There was a significant increase in the IC₅₀ value of PLC/PRF/5 cells from 13.0±0.8 μM in normoxia to 21.3±1.1 μM in hypoxia, but in HepG2 cells, the increase was not significant. To elucidate the LEN resistance mechanism of PLC/PRF/5 cells under hypoxia, we performed microarray analysis and extracted genes that are thought to be related to this mechanism. Furthermore, in-silico analysis confirmed significant changes in the extracellular matrix, and among them, FN1 encoding fibronectin was determined as the hub of the gene cluster. The expression of fibronectin in PLC/PRF/5 cells examined with immunofluorescence staining was significantly elevated in and outside of cells under hypoxia, and tended to decrease when cells were exposed to LEN under normoxia. Furthermore, the fibronectin concentration in the culture solution of PLC/PRF/5 cells examined by ELISA was 2.3 times higher under hypoxia than under normoxia under LEN(-) conditions, and 1.6 times higher under hypoxia than under normoxia under LEN(+) conditions. It is assumed that in PLC/PRF/5 cells, fibronectin is probably suppressed as an indirect effect of LEN under normoxia, but transcription factors such as HIF-1α are induced under hypoxia, thus enhancing the production of fibronectin and attenuating the effect of LEN, resulting in drug resistance. This behavior of fibronectin with LEN exposure under hypoxia is probably specific to PLC/PRF/5 cells. Further studies should verify the combined effective inhibition of fibronectin and the MAPK pathway as a promising therapeutic strategy to enhance the value of LEN in HCC treatment.

Increase in rear-end collision risk by acute stress-induced fatigue in on-road truck driving

Increasing road crashes related to occupational drivers’ deteriorating health has become a social problem. To prevent road crashes, warnings and predictions of increased crash risk based on drivers’ conditions are important. However, in on-road driving, the relationship between drivers’ physiological condition and crash risk remains unclear due to difficulties in the simultaneous measurement of both. This study aimed to elucidate the relationship between drivers’ physiological condition assessed by autonomic nerve function (ANF) and an indicator of rear-end collision risk in on-road driving. Data from 20 male truck drivers (mean ± SD, 49.0±8.2 years; range, 35–63 years) were analyzed. Over a period of approximately three months, drivers’ working behavior data, such as automotive sensor data, and their ANF data were collected during their working shift. Using the gradient boosting decision tree method, a rear-end collision risk index was developed based on the working behavior data, which enabled continuous risk quantification. Using the developed risk index and drivers’ ANF data, effects of their physiological condition on risk were analyzed employing a logistic quantile regression method, which provides wider information on the effects of the explanatory variables, after hierarchical model selection. Our results revealed that in on-road driving, activation of sympathetic nerve activity and inhibition of parasympathetic nerve activity increased each quantile of the rear-end collision risk index. The findings suggest that acute stress-induced drivers’ fatigue increases rear-end collision risk. Hence, in on-road driving, drivers’ physiological condition monitoring and ANF-based stress warning and relief system can contribute to promoting the prevention of rear-end truck collisions.

Amelioration of fatigue in chronic dialysis patients with dialysis solution employing electrolyzed water containing molecular hydrogen (H2) and its association with autonomic function balance

Background

Enhanced oxidative stress is involved with fatigue in hemodialysis (HD) patients. Molecular hydrogen (H2) could improve the redox status. Thus, the study examines whether HD solution rendered by electrolyzed water containing H2 (E-HD) could impact the fatigue and autonomic balance of patients.

Methods

This single-arm, prospective observational study examined 95 patients on chronic HD (54 males; mean age and HD duration; 71.4 years and 10.6 years). Fatigue status on HD and HD-free days was compared between control HD (CHD) and 8 weeks after commencement of E-HD, using a visual analog scale (VAS) and an original scale. Autonomic balance was analyzed with the degree of activities of the sympathetic and parasympathetic nervous system via frequency analysis of a continuous beat interval.

Results

Patients were classified into three groups according to the presence of subjective fatigue during the period of CHD: Group A (40.0%), fatigue only on HD days; Group B (11.6%), presence of fatigue on both HD and HD-free days; and Group C (48.4%), freedom from fatigue. During the 8-week observation period of E-HD, VAS scores were significantly decreased on HD days in Group A, while Group B showed no significant changes in VAS on HD days, but significant decreases on HD-free days. No consistent changes were found in Group C. Significant increases in percentages of patients who reported absence of fatigue were seen in Group A on HD days and in Group B on HD-free days in week 8. Regarding changes in autonomic balance parameters after E-HD commencement, a positive correlation was identified between changes in VAS and autonomic balance in Group A.

Conclusion

E-HD may ameliorate fatigue in patients with subjective symptoms on HD and HD-free days. The influence of autonomic balance by E-HD and its impact on fatigue needs to be elucidated.

Prevention of retained fetal membranes and improvement in subsequent fertility with oxytocin administration in cows with assisted calving

In dairy cows, the efficacy of oxytocin treatment for preventing retained fetal membranes (RFM) is controversial. The physiological condition of cows associated with the calving process may affect the action of oxytocin. This study aimed to elucidate the difference in the efficacy of exogenous oxytocin treatment immediately after calving among cows that received various obstetric interventions. The calving ease was recorded using a score of 1-5, and assisted birth was defined as a score of 2 or more. Cows that required calving assistance (assisted, n = 28) due to delayed calving progression had a prolonged time from calving to expulsion of the fetal membrane (P < 0.01), and impaired reproductive performance compared to cows that did not receive calving assistance (unassisted, n = 78). The effect of oxytocin treatment was determined using cows that did not expel their fetal membrane within 3 h after calving. Cows were randomly divided into the control (unassisted, n = 41; assisted, n = 22) or oxytocin group (unassisted, n = 33; assisted, n = 10). Oxytocin (50 IU) was administered intramuscularly to the cows in the oxytocin group between 3 and 6 h after calving, while no treatment was administered in the control group. In cows with assisted birth, oxytocin administration accelerated placental expulsion (P < 0.05) and improved several reproductive parameters, such as the number of services until conception (P < 0.05) and the calving to conception intervals (P < 0.05) compared to the control group. On the other hand, oxytocin administration slightly accelerated placental expulsion (P < 0.05), but failed to improve fertility in cows with unassisted birth. The results indicate that the action of oxytocin varies depending on the calving situation of the cows. Oxytocin administration during the early postpartum period could prevent RFM and improve the decline in reproductive performance associated with calving assistance.

International consensus on the use of [18F]-FDG PET/CT in pediatric patients affected by epilepsy

PURPOSE

Positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose ([¹⁸F]-FDG) has been increasingly applied in precise localization of epileptogenic focus in epilepsy patients, including pediatric patients. The aim of this international consensus is to provide the guideline and specific considerations for [¹⁸F]-FDG PET in pediatric patients affected by epilepsy.

METHODS

An international, multidisciplinary task group is formed, and the guideline for brain [¹⁸F]-FDG PET/CT in pediatric epilepsy patients has been discussed and approved, which include but not limited to the clinical indications, patient preparation, radiopharmaceuticals and administered activities, image acquisition, image processing, image interpretation, documentation and reporting, etc. CONCLUSION: This is the first international consensus and practice guideline for brain [¹⁸F]-FDG PET/CT in pediatric epilepsy patients. It will be an international standard for this purpose in clinical practice.

Synthesis of L-[5-11 C]Leucine and L-α-[5-11 C]Methylleucine via Pd0 -mediated 11 C-Methylation and Microfluidic Hydrogenation: Potentiality of Leucine PET Probes for Tumor Imaging

The efficient synthesis of L-[5-¹¹ C]leucine and L-α-[5-¹¹ C]methylleucine has been investigated using a continuous two-step sequence of rapid reactions consisting of Pd⁰ -mediated ¹¹ C-methylation and microfluidic hydrogenation. The synthesis of L-[5-¹¹ C]leucine and L-α-[5-¹¹ C]methylleucine was accomplished within 40 min with a decay-corrected radiochemical yield of 15-38 % based on [¹¹ C]CH₃ I, radiochemical purity of 95-99 %, and chemical purity of 95-99 %. The Pd impurities in the injectable solution measured using inductively coupled plasma mass spectrometry met the international criteria for human use. Positron emission tomography scanning after an intravenous injection of L-[5-¹¹ C]leucine or L-α-[5-¹¹ C]methyl leucine in A431 tumor-bearing mice was performed. As a result, L-α-[5-¹¹ C]methylleucine was found to be a potentially useful probe for visualizing the tumor. Tissue distribution analysis showed that the accumulation value of L-α-[5-¹¹ C]methylleucine in tumor tissue was high [12±3% injected dose/g tissue (%ID/g)].

Disrupting tumor onset and growth via selective cell tagging (SeCT) therapy

This study presents the early framework of selective cell tagging (SeCT) therapy, which is the concept of preferentially labeling specific cells in vivo with chemical moieties that can elicit a therapeutic response. Using glycosylated artificial metalloenzyme (GArM)-based protein labeling, this study reports two separate functional strategies. In one approach, early tumor onset can be suppressed by tagging cancer cells in living mice with an integrin-blocking cyclic-Arg-Gly-Asp (cRGD) moiety, thereby disrupting cell adhesion onto the extracellular matrix. In another approach, tumor growth in mice can be reduced by tagging with a cytotoxic doxorubicin moiety. Subsequent cell death occurs following internalization and drug release. Overall, experiments have shown that mouse populations receiving the mixture of SeCT labeling reagents exhibited a significant delay/reduction in tumor onset and growth compared with controls. Highlighting its adaptability, this work represents a foundational step for further development of SeCT therapy and its potential therapeutic applications.

PET imaging of 11C-labeled thiamine tetrahydrofurfuryl disulfide, vitamin B1 derivative: First-in-human study

Vitamine B₁ thiamine is an essential component for glucose metabolism and energy production. The disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), is more absorbent compared to readily-available water-soluble thiamine salts since it does not require the rate-limiting transport system required for thiamine absorption. However, the detailed pharmacokinetics of thiamine and TTFD under normal and pathological conditions were not clarified yet. Recently, ¹¹C-labeled thiamine and TTFD were synthesized by our group, and their pharmacokinetics were investigated by PET imaging in normal rats. In this study, to clarify the whole body pharmacokinetics of [¹¹C]TTFD in human healthy volunteers, we performed first-in-human PET imaging study with [¹¹C]TTFD, along with radiation dosimetry of [¹¹C]TTFD in humans.

METHODS

Synthesis of [¹¹C]TTFD was improved for clinical study. Dynamic whole-body PET images were acquired on three young male normal subjects after intravenous injection of [¹¹C]TTFD. VOIs were defined for source organs on the PET images to measure time-course of [¹¹C]TTFD uptake as percentage injected dose and the number of disintegrations for each organ. Radiation dosimetry was calculated with OLINDA/EXM.

RESULTS

We succeeded in developing the improved synthetic method of [¹¹C]TTFD for the first-in-human PET study. In the whole body imaging, uptake of [¹¹C]TTFD by various tissues was almost plateaued at 10 min after intravenous injection, afterward gradually increased for the brain and urinary bladder (urine). %Injected dose was high in the liver, kidney, urinary bladder, heart, spine, brain, spleen, pancreas, stomach, and salivary glands, in this order. %Injected dose per gram of tissue was high also in the pituitary. By dosimetry, the effective radiation dose of [¹¹C]TTFD calculated was 5.5 μSv/MBq (range 5.2-5.7).

CONCLUSION

Novel synthetic method enabled clinical PET study with [¹¹C]TTFD, which is a safe PET tracer with a dosimetry profile comparable to other common ¹¹C-PET tracers. Pharmacokinetics of TTFD in the pharmacological dose and at different nutritional states could be further investigated by future quantitative PET studies. Noninvasive in vivo PET imaging for pathophysiology of thiamine-related function may provide diagnostic evidence of novel information about vitamin B₁ deficiency in human tissues.

PET imaging of neural activity, β-amyloid, and tau in normal brain aging

Normal brain aging is commonly associated with neural activity alteration, β-amyloid (Aβ) deposition, and tau aggregation, driving a progressive cognitive decline in normal elderly individuals. Positron emission tomography (PET) with radiotracers targeting these age-related changes has been increasingly employed to clarify the sequence of their occurrence and the evolution of clinically cognitive deficits. Herein, we reviewed recent literature on PET-based imaging of normal human brain aging in terms of neural activity, Aβ, and tau. Neural hypoactivity reflected by decreased glucose utilization with PET imaging has been predominately reported in the frontal, cingulate, and temporal lobes of the normal aging brain. Aβ PET imaging uncovers the pathophysiological association of Aβ deposition with cognitive aging, as well as the potential mechanisms. Tau-associated cognitive changes in normal aging are likely independent of but facilitated by Aβ as indicated by tau and Aβ PET imaging. Future longitudinal studies using multi-radiotracer PET imaging combined with other neuroimaging modalities, such as magnetic resonance imaging (MRI) morphometry, functional MRI, and magnetoencephalography, are essential to elucidate the neuropathological underpinnings and interactions in normal brain aging.