Domoic acid biosynthesis in the red alga Chondria armata suggests a complex evolutionary history for toxin production.

Domoic acid (DA), the causative agent of amnesic shellfish poisoning, is produced by select organisms within two distantly related algal clades: planktonic diatoms and red macroalgae. The biosynthetic pathway to isodomoic acid A was recently solved in the harmful algal bloom-forming diatom Pseudonitzschia multiseries, establishing the genetic basis for the global production of this potent neurotoxin. Herein, we sequenced the 507-Mb genome of Chondria armata, the red macroalgal seaweed from which DA was first isolated in the 1950s, identifying several copies of the red algal DA (rad) biosynthetic gene cluster. The rad genes are organized similarly to the diatom DA biosynthesis cluster in terms of gene synteny, including a cytochrome P450 (CYP450) enzyme critical to DA production that is notably absent in red algae that produce the simpler kainoid neurochemical, kainic acid. The biochemical characterization of the N-prenyltransferase (RadA) and kainoid synthase (RadC) enzymes support a slightly altered DA biosynthetic model in C. armata via the congener isodomoic acid B, with RadC behaving more like the homologous diatom enzyme despite higher amino acid similarity to red algal kainic acid synthesis enzymes. A phylogenetic analysis of the rad genes suggests unique origins for the red macroalgal and diatom genes in their respective hosts, with native eukaryotic CYP450 neofunctionalization combining with the horizontal gene transfer of N-prenyltransferases and kainoid synthases to establish DA production within the algal lineages.

Synthesis and Identification of decarbamoyloxySaxitoxins in Toxic Microalgae and their Reactions with the Oxygenase, SxtT, Reveal Saxitoxin Biosynthesis.

Saxitoxin (STX, 1) is a representative compound of paralytic shellfish toxins (PSTs) that are produced by marine dinoflagellates and freshwater cyanobacteria. Although several pathways have been proposed for the biosynthesis of STX, the order of ring and side chain hydroxylation, and formation of the tricyclic skeleton have not been well established. In this study, 12,12-dideoxy-decarbamoyloxySTX (dd-doSTX, 2), the most reduced STX analogue having the tricyclic skeleton, and its analogues, 12ß-deoxy-doSTX (12ß-d-doSTX, 3), 12α-deoxy-doSTX (12α-d-doSTX, 4), and doSTX (5), were synthesized, and these compounds were screened in the toxic microalgae using high-resolution LCMSMS. dd-doSTX (2) and 12ß-d-doSTX (3) were identified in the PSTs-producing dinoflagellates (Alexandrium catenella, A. pacificum, and/or Gymnodinium catenatum) and in the cyanobacterium Dolichospermum circinale (TA04). doSTX (5), previously isolated from the dinoflagellate G. catenatum, was also identified in D. circinale (TA04). Furthermore, the conversion of 2 to 3, and 4 to 5, by SxtT with VanB, a reported Rieske oxygenase and its redox partner in STX biosynthesis, was confirmed. These results support that 2 is a possible biosynthetic precursor of STX, and that ring and side-chain hydroxylations proceed after cyclization.

Assay for okadaic acid O-acyl transferase using HPLC-FLD.

Dinophysistoxin 1 (DTX1, 1) and okadaic acid (OA, 2), produced by the dinoflagellates Dinophysis spp. and Prorocentrum spp., are primary diarrhetic shellfish toxins (DSTs), which may cause gastric illness in people consuming such as bivalves. Both compounds convert to dinophysistoxin 3 (DTX3, 3; generic name for 1 and 2 with fatty acids conjugated at 7-OH) in bivalves. The enzyme okadaic acid O-acyl transferase (OOAT) is a membrane protein found in the microsomes of the digestive glands of bivalves. In this study, we established an in vitro enzymatic conversion reaction using 4-nitro-2,1,3-benzoxadiazole (NBD)-OA (4), an OA derivative conjugated with (R)-(-)-4-nitro-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole (NBD-APy) on 1-CO2H, as a substrate. We detected the enzymatically produced 3, NBD-7-O-palmitoyl-OA (NBD-Pal-OA), using high-performance liquid chromatography-fluorescence detection. We believe that an OOAT assay using 4 will facilitate the fractionation and isolation of OOAT in the future.

Approaches to Construction of the Medium-Sized Ring Structure in Zetekitoxin AB by Ring-Closing Metathesis.

Zetekitoxin AB (ZTX), a member of the saxitoxin (STX) family isolated from the Panamanian golden frog Atelopus zeteki, shows extremely potent NaV-inhibitory activity. Here, we investigate the synthesis of 12-membered ring structure with the C11 tertiary hydroxyl group in ZTX by means of the Mislow-Evans rearrangement reaction and subsequent ring-closing metathesis reaction. Although this approach did not provide access to the 12-membered macrocycle, we obtained a new STX analog with an 18-membered macrolactam structure as a synthetic mimic of ZTX.

Fluctuations in Cognitive Test Scores and Loss to Follow-Up in Community-Dwelling Older Adults: The IRIDE Cohort Study.

INTRODUCTION: We examined the relationship between previous fluctuations in Mini-Mental State Examination (MMSE) scores, future changes in MMSE scores, and attrition from follow-up surveys, which helps in a more comprehensive interpretation of repeatedly collected MMSE scores. METHODS: This 4-year longitudinal study included 2,073 community-dwelling older adults aged ≥65 years in Japan. The MMSE was administered at baseline (T0), 2 years (T1), and 4 years (T2) follow-up. We performed multinomial logistic regression analysis with the dependent variable, indicating the change in MMSE score from T1 to T2 (categorized as increase, no change [reference category], and decrease) and attrition at T2. The independent variables included the change in MMSE scores from T0 to T1 and MMSE scores at T0 and T1. RESULTS: The mean MMSE score was 29 across the three time points. A one-point decrease in MMSE score from T0 to T1 was associated with 79% (95% confidence interval: 1.62, 1.97) higher odds of an increase in MMSE score from T1 to T2 and 28% (1.17, 1.40) higher odds of attrition at T2. A one-point decrement in the MMSE score at T0 and T1 was also associated with an increase in the MMSE score from T1 to T2 and attrition at T2. CONCLUSION: Focusing on cognitive fluctuation for 2 years, rather than cognitive function at a point in time, would have no remarkable advantage when focusing on future cognitive function and attrition. Our results emphasize the need for further studies to identify factors that distinguish between those who continue to attend follow-up surveys and show improvements in cognitive test scores and those who drop out.

Characteristics of people seeking consultation after progressing to severe dementia: A mixed-method analysis.

OBJECTIVES: This explores the characteristics of patients with worsening dementia who did not receive a specialized medical examination or care. METHODS: This study utilized a mixed methods analysis. Of the 2712 people who received the Mini Mental State of Examination (MMSE) at the Community Consultation Center for Citizens with MCI and Dementia between December 2007 and December 2019, 1413 people who scored 23 points or less were included. Participants were categorized into mild, moderate, and severe groups, based on their MMSE scores. Participants' characteristics-gender, age, presence or absence of an escort, demographics, family type, and presence or absence of a family doctor-were compared between the groups. To further understand the severe group's characteristics, clinical psychologists recorded consultation forms were categorized. RESULTS: More than 80% of the patients in each group had a family doctor. Moreover, all the severe groups had escorts, and the role of family members and supporters was important for the consultation. In the severe group, 29 patients had never received specialized medical care. Their characteristics were coded "non-existence" (fewer people or opportunities to notice their needs), "connection failure" (a lack of access or connections to consultations), and "evaluation failure" (not recognized as a problem requiring consultation). CONCLUSIONS: It is necessary to improve primary physician education, disseminate knowledge, and raise awareness about dementia, besides building and strengthening networks to alleviate the isolation of dementia patients and their families. The psychological aspects of family members' denial regarding their family members with dementia must be addressed through intervention.

Combined Impacts of Physical Activity, Dietary Variety, and Social Interaction on Incident Functional Disability in Older Japanese Adults.

BACKGROUND: This 3.6-year prospective study examined combined impacts of physical activity, dietary variety, and social interaction on incident disability and estimated population-attributable fraction for disability reduction in older adults. METHODS: Participants were 7,822 initially non-disabled residents (3,966 men and 3,856 women) aged 65-84 years of Ota City, Tokyo, Japan. Sufficiency of moderate-to-vigorous-intensity physical activity (MVPA) ≥150 min/week, dietary variety score (DVS) ≥3 (median), and social interaction (face-to-face and/or non-face-to-face) ≥1 time/week was assessed using self-administered questionnaires. Disability incidence was prospectively identified using the long-term care insurance system's nationally unified database. RESULTS: During a follow-up of 3.6 years, 1,046 (13.4%) individuals had disabilities. Independent multivariate-hazard ratios (HRs) and 95% confidence intervals (CIs) of MVPA, DVS, and social interaction sufficiency for incident disability were 0.68 (95% CI, 0.59-0.78), 0.87 (95% CI, 0.77-0.99), and 0.90 (95% CI, 0.79-1.03), respectively. Incident disability HRs gradually reduced with increased frequency of satisfying these behaviors (any one: HR 0.82; 95% CI, 0.65-1.03; any two: HR 0.65; 95% CI, 0.52-0.82; and all three behaviors: HR 0.54; 95% CI, 0.43-0.69), in an inverse dose-response manner (P < 0.001 for trend). Population-attributable fraction for disability reduction in satisfying any one, any two, and all three behaviors were 4.0% (95% CI, -0.2 to 7.9%), 9.6% (95% CI, 4.8-14.1%), and 16.0% (95% CI, 8.7-22.8%), respectively. CONCLUSION: Combining physical activity, dietary variety, and social interaction substantially enhances the impacts on preventing disability among older adults, with evidence of an inverse dose-response manner. Improving insufficient behavior elements through individual habits and preexisting social group activities may be effective in preventing disability in the community.

Inaccessibility, unresponsiveness, inconsistency, and invisibility of informal caregivers of older persons with cognitive impairment: community-based participatory research.

BACKGROUND: Studies on informal caregivers in Japan have been limited to family caregivers and largely conducted where family caregivers generally gather. Family caregivers who do not visit such places or non-family caregivers are generally overlooked, and data on these informal caregivers remains scant. Consequently, a framework is needed through which healthcare professionals can approach the informal caregivers of community-dwelling older persons. Therefore, this study approaches such informal caregivers and proposes a classification system for them from the starting point of older persons living in the community with cognitive impairment. METHODS: In 2016, we conducted an epidemiological survey of 7000 + community-dwelling older persons and identified 198 residents with Mini-mental state examination scores less than 23. A team of healthcare professionals contacted them regularly. By 2022, 92 people were still living in the community, and we systematically asked them about their informal caregivers. After approaching the caregivers and obtaining informed consent, we mailed separate questionnaires to older persons and informal caregivers. RESULTS: Among the caregivers, 59%, 34%, and 3% were the child, spouse, and sibling of the older person, while the remaining 4% were non-family caregivers. Except for two daughters-in-laws, all children were biological children of the older person. Male caregivers (46%) tended to have full-time jobs, whereas female caregivers (54%) tended to face financial difficulties. Only 3% of the caregivers had joined a family caregivers' association. Caregivers' reason for not joining such organizations was a lack of time and knowledge. A 3-tiered classification system was developed for these informal caregivers: (1) the household form, (2) accessibility, and (3) the reciprocal awareness of caregiving. Furthermore, family caregivers who lived with the older person or visited them more than once a week with reciprocal awareness of caring and being cared, or "traditional caregivers," accounted for 68% of the caregivers in this study. CONCLUSION: Core family caregivers can be easily approached at places where such caregivers generally gather. However, there also exists a group of informal caregivers who are sometimes inaccessible, unresponsive, and invisible to healthcare professionals. Moreover, their awareness of caregiving is sometimes inconsistent.

GO Revisited: Qualitative Analysis of the Motivating Factors to Start and Continue Playing GO.

PURPOSE: To explore the motivating factors for starting and continuing to play GO among older adults, as well as to examine the effect of GO activities in helping people to live well with, as well as to prevent, dementia. DESIGN: Qualitative descriptive research. METHODS: Semi-structured interviews were conducted. FINDINGS: The participants reportedly started playing GO for dementia prevention, and to cope with their anxieties about aging. They described feeling relaxed while playing GO. They also felt that playing GO fostered human relationships. CONCLUSIONS: GO is effective in assisting older adults to cope with aging issues, cultivate peace of mind and encourage interaction with peers. CLINICAL EVIDENCE: GO is effective in assisting older adults to cope with aging issues, cultivate peace of mind and encourage interaction with peers.

[The expected role of Dementia Support Doctors in dealing with complex cases of older people with dementia].

AIM: The present studyinvestigated the roles expected of Dementia Support Doctors (DSDs) in dealing with complex cases. METHODS: The participants were attendees of the education programs organised by the Center for Promoting Dementia Support and the Medical Center for Dementia at the Tokyo Metropolitan Geriatric Hospital from April 2021 to March 2022. A self-administered postal questionnaire survey was conducted. The questionnaire included items on the basic attributes of the participants, their experiences with the issues associated with complex cases, and role expectations of consulting/collaboration partners when dealing with complex cases. RESULTS: The valid response rate was 49.3%. DSDs were expected by primary physicians, Community General Support Center staff and administrative staff to diagnose dementia and give advice on support strategies for complex cases. Primary physicians further expected them to initiate pharmacotherapy with anti-dementia drugs and address the pharmacotherapy needs for managing Behavioral and Psychological Symptoms of Dementia. It was also found that DSDs' experience with complex cases was comparable to that of the staff at the Medical Centers for Dementia. Of note, DSDs were mentioned less frequently as consulting/collaboration partners than Medical Centers for Dementia and primary physicians. CONCLUSIONS: The study showed that DSDs play an important role in dealing with complex cases. The roles of DSDs and ways to collaborate with them need to be communicated through interprofessional education.

Nontoxic Enantiomeric Reference Materials for Saxitoxins.

Saxitoxin (STX) is a potent neurotoxin that is biosynthesized by toxic dinoflagellates and accumulated in shellfish via the food chain. STX and its various analogues are now monitored in shellfish by the hygiene authorities in many countries with instrumental analytical methods, which require calibration with standards. Unfortunately, STX is registered as a chemical warfare agent in Schedule 1 of the Chemical Weapons Convention, and this has made it difficult to import calibration standards into some countries. We aimed to avoid violation of the Chemical Weapons Convention and facilitate analyses by preparing calibration standards based on unnatural nontoxic antipodal STXs (ent-STXs) with the same physicochemical properties as natural STXs. Our findings demonstrate that the nontoxic ent-STXs can be safely utilized as alternative reference materials of STXs in the routine monitoring program by the local authorities and consequently can lead to reduced usage of STX.

State-Dependent Inhibition of Voltage-Gated Sodium Channels in Neuroblastoma Neuro-2A Cells by Arachidonic Acid from Halichondria okadai.

Voltage-gated sodium channels (Nav) are closely associated with epilepsy, cardiac and skeletal muscle diseases, and neuropathic pain. Several toxic compounds have been isolated from the marine sponge Halichondria okadai; however, toxic substances that modulate Nav are yet to be identified. This study aimed to identify Nav inhibitors from two snake venoms and H. okadai using mouse neuroblastoma Neuro-2A cells (N2A), which primarily express the specific Nav subtype Nav1.7, using whole-cell patch-clamp recordings. We successfully isolated arachidonic acid (AA, 1) from the hexane extract of H. okadai, and then the fatty acid-mediated modulation of Nav in N2A was investigated in detail for the first time. Octanoic acid (2), palmitic acid (3), and oleic acid (4) showed no inhibitory activity at 100 µM, whereas AA (1), dihomo-γ-linolenic acid (DGLA, 5), and eicosapentaenoic acid (EPA, 6) showed IC50 values of 6.1 ± 2.0, 58 ± 19, and 25 ± 4.0 µM, respectively (N = 4, mean ± SEM). Structure and activity relationships were investigated for the first time using two ω-3 polyunsaturated fatty acids (PUFAs), EPA (6) and eicosatetraenoic acid (ETA, 7), and two ω-6 PUFAs, AA (1) and DGLA (5), to determine their effects on a resting state, activated state, and inactivated state. Steady-state analysis showed that the half inactivation potential was largely hyperpolarized by 10 µM AA (1), while 50 µM DGLA (5), 50 µM EPA (6), and 10 µM ETA (7) led to a slight change. The percentages of the resting state block were 24 ± 1, 22 ± 1, 34 ± 4, and 38 ± 9% in the presence of AA (1), DGLA (5), EPA (6), and ETA (7), respectively, with EPA (6) and ETA (7) exhibiting a greater inhibition than both AA (1) and DGLA (5), and their inhibitions did not increase in the following depolarization pulses. None of the compounds exhibited the use-dependent block. The half recovery times from the inactivated state for the control, AA (1), DGLA (5), EPA (6), and ETA (7) were 7.67 ± 0.33, 34.3 ± 1.10, 15.5 ± 1.10, 10.7 ± 0.31, and 3.59 ± 0.18 ms, respectively, with AA (1) exhibiting a distinctively large effect. Overall, distributed binding to the resting and the inactivated states of Nav would be significant for the inhibition of Nav, which presumably depends on the active structure of each PUFA.

Isolation and Biological Activity of 9-epiTetrodotoxin and Isolation of Tb-242B, Possible Biosynthetic Shunt Products of Tetrodotoxin from Pufferfish.

Tetrodotoxin (TTX, 1) is a potent voltage-gated sodium channel blocker detected in certain marine and terrestrial organisms. We report here a new TTX analogue, 9-epiTTX (2), and a TTX-related compound, Tb-242B (4), isolated from the pufferfish Takifugu flavipterus and Dichotomyctere ocellatus, respectively. NMR analysis suggested that 2 exists as a mixture of hemilactal and 10,8-lactone forms, whereas other reported TTX analogues are commonly present as an equilibrium mixture of hemilactal and 10,7-lactone forms. Compound 2 and TTX were confirmed not to convert to each other by incubation under neutral and acidic conditions at 37 °C for 24 h. Compound 4 was identified as the 9-epimer of Tb-242A (3), previously reported as a possible biosynthetic precursor of TTX. Compound 4 was partially converted to 3 by incubation in a neutral buffer at 37 °C for 7 days, whereas 3 was not converted to 4 under this condition. Compound 2 was detected in several TTX-containing marine animals and a newt. Mice injected with 600 ng of 2 by intraperitoneal injection did not show any adverse symptoms, suggesting that the C-9 configuration in TTX is critical for its biological activity. Based on the structures, 2 and 4 were predicted to be shunt products for TTX biosynthesis.

The Kesennuma Study in Miyagi, Japan: Study Design and Baseline Profiles of Participants.

BACKGROUND: To clarify the association between psychosocial problems and frailty in the areas affected by the Great East Japan Earthquake, and to develop strategies for preventive long-term care in the community, we launched the Kesennuma Study in 2019. This report describes the study design and the participants' profiles at baseline. METHODS: The prospective study comprised 9,754 people (4,548 men and 5,206 women) randomly selected from community-dwelling independent adults aged 65 to 84 who were living in Kesennuma City, Miyagi. The baseline survey was conducted in October 2019. It included information on general health, socio-economic status, frailty, lifestyle, psychological factors (eg, personality, depressive moods), and social factors (eg, social isolation, social capital). A follow-up questionnaire survey is planned. Mortality, incident disability, and long-term care insurance certifications will also be collected. RESULTS: A total of 8,150 questionnaires were returned (83.6% response rate), and 7,845 were included in the analysis (80.4%; mean age 73.6 [standard deviation, 5.5] years; 44.7% male). About 23.5% were considered frail. Regarding psychological and social functions, 42.7% had depressive moods, 29.1% were socially isolated, and only 37.0% participated in social activities at least once a month. However, 82.5% trusted their neighbors. CONCLUSION: While local ties were strong, low social activity and poor mental health were revealed as issues in the affected area. Focusing on the association between psychological and social factors and frailty, we aim to delay the need for long-term care for as long as possible, through exercise, nutrition, social participation, and improvement of mental health.

Mass spectrometry-guided discovery of new analogs of bicyclic phosphotriester salinipostin and evaluation of their monoacylglycerol lipase inhibitory activity.

Natural products containing the highly unusual phosphotriester ring are known to be potent serine hydrolase inhibitors. The long-chain bicyclic enol-phosphotriester salinipostins (SPTs) from the marine actinomycete Salinispora have been identified as selective antimalarial agents. A potential regulatory function has been suggested for phosphotriesters based on their structural relationship with actinomycete signaling molecules and the prevalence of spt-like biosynthetic gene clusters across actinomycetes. In this study, we established a mass spectrometry-guided screening method for phosphotriesters focusing on their characteristic fragment ions. Applying this screening method to the SPT producer Salinispora tropica CNB-440, new SPT analogs (4-6) were discovered and their structures were elucidated by spectroscopic analyses. Previously known and herein-identified SPT analogs inhibited the activity of human monoacylglycerol lipase (MAGL), a key serine hydrolase in the endocannabinoid system, in the nanomolar range. Our method could be applied to the screening of phosphotriesters, potential serine hydrolase inhibitors and signaling molecules.

First Identification of 12ß-Deoxygonyautoxin 5 (12α-Gonyautoxinol 5) in the Cyanobacterium Dolichospermum circinale (TA04) and 12ß-Deoxysaxitoxin (12α-Saxitoxinol) in D. circinale (TA04) and the Dinoflagellate Alexandrium pacificum (Group IV) (120518KureAC).

Saxitoxin and its analogues, paralytic shellfish toxins (PSTs), are potent and specific voltage-gated sodium channel blockers. These toxins are produced by some species of freshwater cyanobacteria and marine dinoflagellates. We previously identified several biosynthetic intermediates of PSTs, as well as new analogues, from such organisms and proposed the biosynthetic and metabolic pathways of PSTs. In this study, 12ß-deoxygonyautoxin 5 (12α-gonyautoxinol 5 = gonyautoxin 5-12(R)-ol) was identified in the freshwater cyanobacterium, Dolichospermum circinale (TA04), and 12ß-deoxysaxitoxin (12α-saxitoxinol = saxitoxin-12(R)-ol) was identified in the same cyanobacterium and in the marine dinoflagellate Alexandrium pacificum (Group IV) (120518KureAC) for the first time from natural sources. The authentic standards of these compounds and 12α-deoxygonyautoxin 5 (12ß-gonyautoxinol 5 = gonyautoxin 5-12(S)-ol) were prepared by chemical derivatization from the major PSTs, C1/C2, produced in D. circinale (TA04). These standards were used to identify the deoxy analogues by comparing the retention times and MS/MS spectra using high-resolution LC-MS/MS. Biosynthetic or metabolic pathways for these analogues have also been proposed based on their structures. The identification of these compounds supports the α-oriented stereoselective oxidation at C12 in the biosynthetic pathway towards PSTs.

Preparation of domoic acid analogues using a bioconversion system, and their toxicity in mice.

Domoic acid (1, DA), a member of the natural kainoid family, is a potent agonist of ionotropic glutamate receptors in the central nervous system. The chemical synthesis of DA and its derivatives requires considerable effort to establish a pyrrolidine ring containing three contiguous stereocenters. Recently, a biosynthetic cyclase for DA, DabC, was identified. This enzyme cyclizes the linear precursor of isodomoic acid A (IA) to IA, a bioactive DA analogue. In this study, we developed a bioconversion system to obtain DA analogues from linear substrates prepared by simple chemical synthesis using DabC expressed in Escherichia coli, in vivo. Three IA analogues with various substitutions at the C7'-geranyl terminus were prepared using this system: two minor natural analogues, 7'-methyl-IA (5) and 7'-hydroxy-IA (6), and one new unnatural analogue, 7'-amide-IA (7). In addition, the toxicity of these DA analogues in mice was examined by intracerebroventricular injection. Most of the mice injected with 5 (3 nmol) and 6 (3 nmol) did not show any adverse symptoms, whereas the mice injected with 7 (3 nmol) showed typical symptoms induced by DA (1, 0.7 nmol) and IA (2, 3 nmol). These results suggest that the 7'-carbonyl group in the side chain of IA (2) is crucial for its toxicity. The docking studies of DA, IA (2), 5, 6, and 7 to GluK1 supported these results.

Living on the edge of the community: factors associated with discontinuation of community living among people with cognitive impairment.

BACKGROUND: As Japanese society continues to age, the isolation of older people is increasing, and community living for people with cognitive impairment is becoming more difficult. However, the challenges faced by people with cognitive impairment living in the community have not been fully explored because of methodological difficulties. This study re-accessed people with cognitive impairment identified in a previous epidemiological survey to explore their current situation and the risk factors associated with all-cause discontinuation of community living. METHODS: Under a community-based participatory framework, we examined a high-risk approach for people with cognitive impairment and a community action approach in parallel, to build a dementia-friendly community. For the high-risk approach, we achieved stepwise access to 7614 older residents, which enabled us to select and visit the homes of 198 participants with a Mini-Mental State Examination score < 24 in 2016. In 2019, we re-accessed these individuals. For the community action approach, we built a community space in the study area to build partnerships with community residents and community workers and were able to re-access participants using multiple methods. RESULTS: We found that 126 (63.6%) participants had continued living in the same community, but 58 (29.3%) had discontinued community living. Of these, 18 (9.1%) had died, 18 (9.1%) were institutionalized, 9 (4.5%) were hospitalized, and 13 (6.6%) had moved out of the community. A multiple logistic regression analysis identified the following risk factors associated with discontinuation of community living: being certified under long-term care insurance, needing housing support, and needing rights protection. CONCLUSIONS: Three years after the baseline survey, 29.3% of people with cognitive impairment had discontinued community living. Despite having cognitive impairment or living alone, older people were able to continue living in the community if their needs for housing support and rights protection were met. Both social interventions and medical interventions are important to build age-friendly communities. TRIAL REGISTRATION: UMIN, UMIN000038189, Registered 3 October 2019, https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000043521.

Synthesis of C12-Keto Saxitoxin Derivatives with Unusual Inhibitory Activity Against Voltage-Gated Sodium Channels.

A novel series of C12-keto-type saxitoxin (STX) derivatives bearing an unusual nonhydrated form of the ketone at C12 has been synthesized, and their NaV -inhibitory activity has been evaluated in a cell-based assay as well as whole-cell patch-clamp recording. Among these compounds, 11-benzylidene STX (3 a) showed potent inhibitory activity against neuroblastoma Neuro 2A in both cell-based and electrophysiological analyses, with EC50 and IC50 values of 8.5 and 30.7 nm, respectively. Interestingly, the compound showed potent inhibitory activity against tetrodotoxin-resistant subtype of NaV 1.5, with an IC50 value of 94.1 nm. Derivatives 3 a-d and 3 f showed low recovery rates from NaV 1.2 subtype (ca 45-79 %) compared to natural dcSTX (2), strongly suggesting an irreversible mode of interaction. We propose an interaction model for the C12-keto derivatives with NaV in which the enone moiety in the STX derivatives 3 works as Michael acceptor for the carboxylate of Asp1717 .

Structures of N-Hydroxy-Type Tetrodotoxin Analogues and Bicyclic Guanidinium Compounds Found in Toxic Newts.

The biosynthesis of tetrodotoxin (TTX, 1), a potent neurotoxin widely distributed in marine and terrestrial metazoans, remains unresolved. A significant issue has been identifying intermediates and shunt products associated with the biosynthetic pathway of TTX. We investigated TTX biosynthesis by screening and identifying new TTX-related compounds from Cynops ensicauda popei and Taricha granulosa. Mass spectrometry (MS)-guided screening identified two new N-hydroxy TTX analogues in newts: 1-hydroxy-8-epiTTX (2) and 1-hydroxy-8-epi-5,11-dideoxyTTX (3, previously reported as 1-hydroxy-5,11-dideoxyTTX). We prepared a new analogue, 8-epi-5,11-dideoxyTTX (4), from 3 via N-OH reduction and confirmed the presence of 4 in T. granulosa using hydrophilic interaction liquid chromatography (HILIC)-LCMS. The presence of 8-epi-type TTX analogues in both Cynops and Taricha supports a branched biosynthetic pathway of terrestrial TTX, which produces 6- and 8-epimers. In addition, new bicyclic guanidinium compounds Tgr-238 (5) and Tgr-240 (6) were identified as putative shunt products of our proposed TTX biosynthesis pathway. A structural analysis of Cep-228A (7), another bicyclic compound, was performed using NMR. Based on the structures of 5-7 and their analogues, we propose a model of the shunt and metabolic pathways of the terrestrial TTX biosynthesis.