Plasma homocysteine as a risk factor for dementia and Alzheimer's disease

Atherogenic Effect of Homocysteine, a Biomarker of Inflammation and Its Treatment

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. Ischemic stroke and heart disease, coronary heart disease, and cardiovascular disease are events resulting from long-lasting and silent atherosclerosis. This paper deals with the synthesis of homocysteine (Hcy), causes of HHcy, mechanism of HHcy-induced atherosclerosis, and treatment of HHcy. Synthesis and metabolism of Hcy involves demethylation, transmethylation, and transsulfuration, and these processes require vitamin B 6 and vitamin B 12 folic acid (vitamin B 9 ). Causes of HHcy include deficiency of vitamins B 6 , B 9 , and B 12 , genetic defects, use of smokeless tobacco, cigarette smoking, alcohol consumption, diabetes, rheumatoid arthritis, low thyroid hormone, consumption of caffeine, folic acid antagonist, cholesterol-lowering drugs (niacin), folic acid antagonist (phenytoin), prolonged use of proton pump inhibitors, metformin, and hypertension. HHcy-induced atherosclerosis may be mediated through oxidative stress, decreased availability of nitric oxide (NO), increased expression of monocyte chemoattractant protein-1, smooth muscle cell proliferation, increased thrombogenicity, and induction of arterial connective tissue. HHcy increases the generation of atherogenic biomolecules such as nuclear factor-kappa B, proinflammatory cytokines (IL-1β, IL-6, and IL-8), cell adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selection), growth factors (IGF-1 and TGF-β), and monocyte colony-stimulating factor which lead to the development of atherosclerosis. NO which is protective against the development of atherosclerosis is reduced by HHcy. Therapy with folic acid, vitamin B 6 , and vitamin B 12 lowers the levels of Hcy, with folic acid being the most effective. Dietary sources of folic acid, vitamin B 6 , vitamin B 12 , omega-3 fatty acid, and green coffee extract reduce Hcy. Abstaining from drinking coffee and alcohol, and smoking also reduces blood levels of Hcy. In conclusion, HHcy induces atherosclerosis by generating atherogenic biomolecules, and treatment of atherosclerosis-induced diseases may be by reducing the levels of Hcy.

Biomarkers for cognitive impairment in alpha-synucleinopathies: an overview of systematic reviews and meta-analyses

Cognitive impairment (CI) is common in α-synucleinopathies, i.e., Parkinson's disease, Lewy bodies dementia, and multiple system atrophy. We summarize data from systematic reviews/meta-analyses on neuroimaging, neurophysiology, biofluid and genetic diagnostic/prognostic biomarkers of CI in α-synucleinopathies. Diagnostic biomarkers include atrophy/functional neuroimaging brain changes, abnormal cortical amyloid and tau deposition, and cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarkers, cortical rhythm slowing, reduced cortical cholinergic and glutamatergic and increased cortical GABAergic activity, delayed P300 latency, increased plasma homocysteine and cystatin C and decreased vitamin B12 and folate, increased CSF/serum albumin quotient, and serum neurofilament light chain. Prognostic biomarkers include brain regional atrophy, cortical rhythm slowing, CSF amyloid biomarkers, Val66Met polymorphism, and apolipoprotein-E ε2 and ε4 alleles. Some AD/amyloid/tau biomarkers may diagnose/predict CI in α-synucleinopathies, but single, validated diagnostic/prognostic biomarkers lack. Future studies should include large consortia, biobanks, multi-omics approach, artificial intelligence, and machine learning to better reflect the complexity of CI in α-synucleinopathies.

Plasma homocysteine and longitudinal change in cognitive function among urban adults

BACKGROUND

Cross-sectional and longitudinal studies have inconsistently linked cognitive performance and change over time to an elevated level of homocysteine (Hcy), with few conducted among urban adults.

METHODS

Longitudinal data [Visit 1 (2004-2009) and Visit 2 (2009-2013)] were analyzed from up to 1430 selected Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) participants. Baseline and follow-up blood Hcy was measured, while 11 cognitive function test scores were assessed at either of these two visits. Overall, sex- and race-stratified associations were evaluated using mixed-effects linear regression models, adjusting for key potential confounders. Interaction effects between Hcy and serum levels of folate and vitamin B-12 were also tested.

RESULTS

We found that greater LnHcyv1 was significantly associated with poorer baseline attention based on higher Loge (TRAILS A, in seconds) [β (SE): 0.101 (0.031), P = 0.001]. Heterogeneity was also found by sex and by race. Most notably, among men only, LnHcyv1 was associated with faster decline on the BVRT (# of errors), a measure of visuo-spatial memory (β (SE): 0.297(0.115), P = 0.010, reduced model); while among African American adults only, an elevated and increasing LnHcy over time was associated with faster rate of decline on Loge (TRAILS B, in seconds) [β (SE): +0.012 (0.005), p = 0.008], a measure of executive function. Interactions between Hcy, folate and vitamin B-12 blood exposures were also detected.

CONCLUSIONS

In summary, sex- and race-specific adverse association between elevated Hcy and cognitive performance over time were detected among middle-aged urban adults, in domains of attention, visuo-spatial memory and executive functioning.

Phototherapy Alters the Plasma Metabolite Profile in Infants Born Preterm with Hyperbilirubinemia

OBJECTIVE

To investigate the effects of gestational age (GA) and phototherapy on the plasma metabolite profile of preterm infants with neonatal hyperbilirubinemia (NHB).

STUDY DESIGN

From a cohort of prospectively enrolled infants born preterm (n = 92), plasma samples of very preterm (VPT; GA, 28 + 0 to 31 + 6 weeks, n = 27) and moderate/late preterm (M/LPT; GA, 32 + 0 to 35 + 6 weeks, n = 33) infants requiring phototherapy for NHB were collected prior to the initiation of phototherapy and 24 hours after starting phototherapy. An additional sample was collected 48 hours after starting phototherapy in a randomly selected subset (n = 30; VPT n = 15; M/LPT n = 15). Metabolite profiles were determined using ultraperformance liquid chromatography tandem mass spectroscopy. Two-way ANCOVA was used to identify metabolites that differed between GA groups and timepoints after adjusting for total serum bilirubin levels (false discovery rate q-value < 0.05). Top impacted pathways were identified using pathway over-representation analysis.

RESULTS

Phototherapy was initiated at lower total serum bilirubin (mean ± SD mg/dL) levels in VPT compared with M/LPT infants (7.3 ± 1.4 vs 9.9 ± 1.9, P < .01). We identified 664 metabolites that were significant for a phototherapy effect, 191 metabolites significant for GA, and 46 metabolites significant for GA × phototherapy interaction (false discovery rate q-value < 0.05). Longer duration phototherapy had a larger mean effect size (24 hours postphototherapy: d = 0.36; 48 hours postphototherapy: d = 0.43). Top pathways affected by phototherapy included membrane lipid metabolism, one-carbon metabolism, creatine biosynthesis, and oligodendrocyte differentiation.

CONCLUSION

Phototherapy alters the plasma metabolite profile more than GA in preterm infants with NHB, affecting pathways related to lipid and one-carbon metabolism, energy biosynthesis, and oligodendrocyte differentiation.

Over-expression of SiADCL1 in Arabidopsis modulates folate and amino acid metabolism to impact on flowering time

Foxtail millet is a C4 crop rich in folate (FA). This study explores the roles of the 4-amino-4-deoxychorismate lyase (ADCL) - a member of the transaminase IV group of enzymes - in FA metabolism and conferred phenotypes. Phylogenetic comparisons identified diversity in the transaminase IV/ADCL gene family in the foxtail millet genome which was associated with genomic duplications. Molecular docking studies suggested that SiADCL1 bound most strongly to aminodeoxychorismate (ADC) and most likely had the highest catalytic activities. SiADCL1 which was highly expressed in roots, peduncles and flag leaves. Over-expression of SiADCL1 in Arabidopsis significantly increased total FA content (1.14-1.84 fold) and this was linked to a delayed flowering time. Metabolomic and transcriptomic characterization of the derived over-expression lines, found that FA promotes the change of methylation-related genes, ethylene synthesis, amino acid metabolism and flowering-related genes. This study revealed a potential gene coexpression network linked with FA and targeted key genes that could be exploited in foxtail millet breeding programs.

Risk of Alzheimer's disease and genetically predicted levels of 1400 plasma metabolites: a Mendelian randomization study

Alzheimer's disease (AD) is a metabolic disorder. Discovering the metabolic products involved in the development of AD may help not only in the early detection and prevention of AD but also in understanding its pathogenesis and treatment. This study investigated the causal association between the latest large-scale plasma metabolites (1091 metabolites and 309 metabolite ratios) and AD. Through the application of Mendelian randomization analysis methods such as inverse-variance weighted (IVW), MR-Egger, and weighted median models, 66 metabolites and metabolite ratios were identified as potentially having a causal association with AD, with 13 showing significant causal associations. During the replication validation phase, six metabolites and metabolite ratios were confirmed for their roles in AD: N-lactoyl tyrosine, argininate, and the adenosine 5'-monophosphate to flavin adenine dinucleotide ratio were found to exhibit protective effects against AD. In contrast, ergothioneine, piperine, and 1,7-dimethyluric acid were identified as contributing to an increased risk of AD. Among them, argininate showed a significant effect against AD. Replication and sensitivity analyses confirmed the robustness of these findings. Metabolic pathway analysis linked "Vitamin B6 metabolism" to AD risk. No genetic correlations were found, but colocalization analysis indicated potential AD risk elevation through top SNPs in APOE and PSEN2 genes. This provides novel insights into AD's etiology from a metabolomic viewpoint, suggesting both protective and risk metabolites.

Comparison of homocysteine, vitamin B12 and folic acid between rural and urban ageing Indians and its association with mild cognitive impairment and cardiovascular risk factors: a cross-sectional analysis

The relationship between blood levels of homocysteine (HCY), vitamin B12, folic acid and cognitive impairment is inconclusive. Since HCY is an independent risk factor for cardiovascular diseases, understanding its association with Framingham risk score (FRS) may provide insight into the shared underlying mechanism between cardiovascular disease and cognitive impairment. Cross-sectional analyses utilized baseline data from two ongoing longitudinal studies: the Tata Longitudinal Study of Ageing (n = 923), an urban cohort, and Srinivaspura Ageing, NeuroSenescence and COGnition (n = 4239), a rural cohort. The study compared the HCY, vitamin B12 and folic acid levels across cohorts and normal versus mild cognitive impairment (MCI) participants. The association between HCY and cognitive status was established using regression models. Three models were analysed: model 1-unadjusted; model 2-adjusted for age, gender, smoking, alcohol consumption, diet, hypertension, cardiac illness, diabetes; and model 3-adjusted for variables in model 2 plus vitamin B12 and folic acid. Correlation was calculated between HCY and FRS. The urban cohort exhibited a significantly higher level of HCY [median (IQR) (17.70 (10.2) versus 14.70 (9.7); P < 0.001)], vitamin B12 (251 (231) versus 219 (138); P < 0.001) and folic acid (8.21 (8) versus 5.48 (4); P < 0.001) levels compared to rural cohort. HCY, vitamin B12 and folic acid levels did not differ significantly between normal and MCI participants in the urban cohort. In the rural cohort, among the age-gender matched MCI-normal, participants with normal cognition had higher levels of vitamin B12 (≥60 years) [227 (152) versus 217 (175); P = 0.03] and folic acid (<60 years) [5.91 (4) versus 5.40 (4); P = 0.04] compared to MCI. There was no association between HCY and cognitive status in both the cohorts, but there was a significant positive relationship between vitamin B12 deficiency and Clinical Dementia Rating-Sum of the Boxes (CDR-SOB), as well as folic acid deficiency and CDR-SOB in rural and urban cohorts, respectively, within a specific age group. A significant correlation was observed between FRS and HCY in the rural cohort (r = 0.17, P < 0.001), but not in the urban cohort. This study revealed significant differences in HCY, vitamin B12 and folic acid levels between the cohorts. In the rural cohort, participants with MCI had lower vitamin B12 and folic acid levels in a certain age group. Association between HCY and cognitive status was insignificant in both the cohorts. A small significant correlation between FRS and HCY was seen in the rural cohort.

Lactobacillus Eats Amyloid Plaque and Post-Biotically Attenuates Senescence Due to Repeat Expansion Disorder and Alzheimer's Disease

Patients with Alzheimer's disease and related dementia (ADRD) are faced with a formidable challenge of focal amyloid deposits and cerebral amyloid angiopathy (CAA). The treatment of amyloid deposits in ADRD by targeting only oxidative stress, inflammation and hyperlipidemia has not yielded significant positive clinical outcomes. The chronic high-fat diet (HFD), or gut dysbiosis, is one of the major contributors of ADRD in part by disrupted transport, epigenetic DNMT1 and the folate 1-carbon metabolism (FOCM) cycle, i.e., rhythmic methylation/de-methylation on DNA, an active part of epigenetic memory during genes turning off and on by the gene writer (DNMT1) and eraser (TET2/FTO) and the transsulfuration pathway by mitochondrial 3-mercaptopyruvate sulfur transferase (3MST)-producing H2S. The repeat CAG expansion and m6A disorder causes senescence and AD. We aim to target the paradigm-shift pathway of the gut-brain microbiome axis that selectively inhibits amyloid deposits and increases mitochondrial transsulfuration and H2S. We have observed an increase in DNMT1 and decreased FTO levels in the cortex of the brain of AD mice. Interestingly, we also observed that probiotic lactobacillus-producing post-biotic folate and lactone/ketone effectively prevented FOCM-associated gut dysbiosis and amyloid deposits. The s-adenosine-methionine (SAM) transporter (SLC25A) was increased by hyperhomocysteinemia (HHcy). Thus, we hypothesize that chronic gut dysbiosis induces SLC25A, the gene writer, and HHcy, and decreases the gene eraser, leading to a decrease in SLC7A and mitochondrial transsulfuration H2S production and bioenergetics. Lactobacillus engulfs lipids/cholesterol and a tri-directional post-biotic, folic acid (an antioxidant and inhibitor of beta amyloid deposits; reduces Hcy levels), and the lactate ketone body (fuel for mitochondria) producer increases SLC7A and H2S (an antioxidant, potent vasodilator and neurotransmitter gas) production and inhibits amyloid deposits. Therefore, it is important to discuss whether lactobacillus downregulates SLC25A and DNMT1 and upregulates TET2/FTO, inhibiting β-amyloid deposits by lowering homocysteine. It is also important to discuss whether lactobacillus upregulates SLC7A and inhibits β-amyloid deposits by increasing the mitochondrial transsulfuration of H2S production.

Dietary choline and betaine intake minimally impacts rate of annualized cognitive performance throughout the menopause transition: data from the Study of Women's Health Across the Nation

OBJECTIVE

Dietary choline is associated with lower risk of dementia in older adults, yet this association during mid-life remains unknown. Given that menopause reflects a nutrition-sensitive time point where prevention strategies may mitigate cognitive deficits, we examined the relationship of choline, betaine, and egg intakes (ie, dietary exposures) with cognitive performance in the Study of Women's Health Across the Nation (SWAN) cohort ( N = 1,006).

METHODS

SWAN is a longitudinal study of women across the menopause transition. Diet was assessed via modified Block food frequency questionnaire, and cognitive function was examined using the Symbol Digit Modalities Test, Digits Backward Test, and East Boston Memory Test (EBMT). Annualized rate of cognitive scores and quartiles of diet were computed using linear mixed models overall (all diet exposures) and by baseline menopausal status (choline, betaine only).

RESULTS

Among all women, higher choline ( P -for-trend = 0.006) and betaine ( P -for-trend = 0.005) intakes, independently and combined (ie, choline + betaine; P -for-trend = 0.001), were significantly associated with reduced rate of change on the EBMT-Delayed Recall (DR), but egg intake did not consistently impact cognitive function. By menopausal status, higher betaine, but not choline, was associated with a lower annualized rate of change in cognitive performance on the EBMT-DR (mean difference [95% confidence interval]; Q1: referent vs Q4: -0.071 [-0.17, 0.03]; P -for-trend = 0.006) for early perimenopausal women; nevertheless, choline and betaine were not associated with cognitive function among premenopausal women.

CONCLUSIONS

Higher dietary betaine intake among early perimenopausal women and higher dietary intakes of betaine and choline, independently and combined, among all women, were minimally associated with the trajectory of verbal episodic memory, yet no associations between diet and cognition were observed among premenopausal women. Future research should address the relationship between dietary intake and cognition during menopause in other research settings and cohorts.

Neuroprotective signaling by hydrogen sulfide and its dysregulation in Alzheimer's disease

The ancient messenger molecule hydrogen sulfide (H2S) modulates myriad signaling cascades and has been conserved across evolutionary boundaries. Although traditionally known as an environmental toxin, H2S is also synthesized endogenously to exert modulatory and homeostatic effects in a broad array of physiologic functions. Notably, H2S levels are tightly physiologically regulated, as both its excess and paucity can be toxic. Accumulating evidence has revealed pivotal roles for H2S in neuroprotection and normal cognitive function, and H2S homeostasis is dysregulated in neurodegenerative conditions. Here, we review the normal neuroprotective roles of H2S that go awry in Alzheimer's disease, the most common form of neurodegenerative disease.

A systematic review on the impact of nutrition and possible supplementation on the deficiency of vitamin complexes, iron, omega-3-fatty acids, and lycopene in relation to increased morbidity in women after menopause

A balanced and healthy diet during the menopausal transition and after menopause is crucial for women to reduce the risk for morbidities and chronic diseases due to deficiency of essential nutrients.

PURPOSE

The objective of this study was to conduct a systematic review of studies that analyzed the impact of vitamin and nutrient deficiencies in postmenopausal women in relation to increased morbidities and chronic conditions.

METHODS

Observational studies were searched in the databases PubMed, UpToDate, and Google Scholar.

RESULTS

We searched 122 studies, of which 90 were included in our analysis. The meta-analysis of the data could not be performed because of the heterogeneity of the statistical methods in the included studies. In our study, we focused on the aspects of vitamin B6, vitamin B12, vitamin D, iron, omega-3-fatty acids, and lycopene, belonging to the family of carotenoids. Postmenopausal women with deficiencies of these nutrients are more vulnerable to comorbidities such as cardiovascular and cerebrovascular events, metabolic diseases, osteoporosis, obesity, cancer and neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, depression, cognitive decline, dementia, and stroke. We concluded that women after menopause tend to have a greater probability of suffering from deficiencies in various vitamins and nutrients, and consequently have an increased risk of developing morbidities and chronic diseases.

CONCLUSION

In conclusion, maintaining optimum serum levels of nutrients and vitamins, either through a balanced and healthy diet consuming fresh fruits, vegetables, and fats or by taking appropriate supplementation, is essential in maintaining optimal health-related quality of life and reducing the risk for women during the menopausal transition and after menopause. Nevertheless, more recent studies need to be assessed to formulate adequate recommendations to achieve positive clinical outcomes.

The Imbalance of Homocysteine, Vitamin B12 and Folic Acid in Parkinson Plus Syndromes: A Review beyond Parkinson Disease

While there is a link between homocysteine (Hcy), B12 and folic acid and neurodegeneration, especially in disorders like Parkinson's and Alzheimer's diseases, its role in Parkinson plus syndromes (PPS) has only been partially investigated. It appears that elevated Hcy, along with an imbalance of its essential vitamin cofactors, are both implicated in the development and progression of parkinsonian syndromes, which represent different disease pathologies, namely alpha-synucleinopathies and tauopathies. Attributing a potential pathogenetic role in hyperhomocysteinemia would be crucial in terms of improving the diagnostic and prognostic accuracy of these syndromes and also for providing a new target for possible therapeutic intervention. The scope of this review is to focus on vitamin imbalance in PPS, with a special emphasis on the role of Hcy, B12 and folic acid in the neurodegenerative process and their implication in the therapeutic approach of these disorders.

Electrochemical sensing of vitamin B6 (pyridoxine) by adapted carbon paste electrode

The recent investigation targets to use adapted carbon paste (CP) with copper nanoparticles (CuNs) operating in a phosphate buffer (PBS) medium with a pH range of 5.0-8.0, to synthesize a novel, susceptible, and simple electrochemical sensor for the detection of one of the most important drugs, vitamin B6. Copper (Cu) is one of the most three common essential trace elements found in the bodies of both humans and animals, along with iron and zinc for all crucial physiological and biochemical functions. Its properties, which are assessed using a variety of methods including scanning electron microscopy (SEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS), have also drawn a lot of attention recently. We considered the effects of pH, buffer, scan rate, interference, and calibration curve. The susceptible electrode's linear calibration curve encompassed concentration values between 8.88 and 1000.0 µM. The calculated limits of detection and quantification were 32.12 and 107.0 µM, respectively. Furthermore, this method was established in real human urine samples and drug validation which have been shown satisfactory results for vitamin B6 detection.

Research Progress of Fluorescent Probes for Detection of Glutathione (GSH): Fluorophore, Photophysical Properties, Biological Applications

Intracellular biothiols, including cysteine (Cys), glutathione (GSH), and homocysteine (Hcy), play a critical role in many physiological and pathological processes. Among them, GSH is the most abundant non-protein mercaptan (1-10 mM) in cells, and the change in GSH concentration level is closely related to the occurrence of many diseases, such as Parkinson's disease, Alzheimer's disease, and neurological diseases. Fluorescent probes have attracted much attention due to their advantages of high specificity, high sensitivity, high selectivity, low cost, and high quantum yield. Methods that use optical probes for selective detection of GSH in vitro and in vivo are in high demand. In this paper, we reviewed the most recent five years of research on fluorescence probes for the detection of GSH, including the specific detection of GSH, dual-channel identification of GSH and other substances, and the detection of GSH and other biothiols. According to the type of fluorophore, we classified GSH fluorescent probes into eight classes, including BODIPY, 1,8-Naphthalimide, coumarin, xanthene, rhodamine, cyanine, benzothiazoles, and others. In addition, we roundly discuss the synthesis, detection mechanism, photophysical properties, and biological applications of fluorescent probes. We hope that this review will inspire the exploration of new fluorescent probes for GSH and other related analyses.

Genetically Encoded Photocaged Proteinogenic and Non-Proteinogenic Amino Acids

Photocaged amino acids could be genetically encoded into proteins via genetic code expansion (GCE) and constitute unique tools for innovative protein engineering. There are a number of photocaged proteinogenic amino acids that allow strategic conversion of proteins into their photocaged variants, thus enabling spatiotemporal and non-invasive regulation of protein functions using light. Meanwhile, there are a hand of photocaged non-proteinogenic amino acids that address the challenges in directly encoding certain non-canonical amino acids (ncAAs) that structurally resemble proteinogenic ones or possess highly reactive functional groups. Herein, we would like to summarize the efforts in encoding photocaged proteinogenic and non-proteinogenic amino acids, hoping to draw more attention to this fruitful and exciting scientific campaign.

H3K4 Trimethylation Mediate Hyperhomocysteinemia Induced Neurodegeneration via Suppressing Histone Acetylation by ANP32A

Homocysteine (Hcy) is an independent and serious risk factor for dementia, including Alzheimer's disease (AD), but the precise mechanisms are still poorly understood. In the current study, we observed that the permissive histone mark trimethyl histone H3 lysine 4 (H3K4me3) and its methyltransferase KMT2B were significantly elevated in hyperhomocysteinemia (HHcy) rats, with impairment of synaptic plasticity and cognitive function. Further research found that histone methylation inhibited synapse-associated protein expression, by suppressing histone acetylation. Inhibiting H3K4me3 by downregulating KMT2B could effectively restore Hcy-inhibited H3K14ace in N2a cells. Moreover, chromatin immunoprecipitation revealed that Hcy-induced H3K4me3 resulted in ANP32A mRNA and protein overexpression in the hippocampus, which was regulated by increased transcription Factor c-fos and inhibited histone acetylation and synapse-associated protein expression, and downregulating ANP32A could reverse these changes in Hcy-treated N2a cells. Additionally, the knockdown of KMT2B restored histone acetylation and synapse-associated proteins in Hcy-treated primary hippocampal neurons. These data have revealed a novel crosstalk mechanism between KMT2B-H3K4me3-ANP32A-H3K14ace, shedding light on its role in Hcy-related neurogenerative disorders.

Synergistic effect of folate and MTHFR C677T on hippocampal subfields and perfusion in Alzheimer's disease

BACKGROUND

Low folate intake and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism have been suggested to increase the risk of Alzheimer's disease (AD). However, the synergistic effects and their impact on brain structure and perfusion remain unclear.

METHODS

This study explored the effects of dietary and genetic deficiencies in folate metabolism on the volume of the hippocampal subregions, cerebral perfusion, and cognitive decline in 71 cognitively unimpaired (CU) individuals and 102 patients with mild cognitive impairment (MCI) due to AD or AD. All participants underwent magnetic resonance imaging, laboratory examinations, and neuropsychological assessments. The hippocampal subfields were segmented using Freesurfer, and arterial spin labeling was used to measure the cerebral blood flow.

RESULTS

We found a significant group-by-MTHFR interaction effect on folate. Patients with AD and the 677 T allele showed hypoperfusion in the left precuneus compared to patients without this mutation, which mediated the relationship between low folate level and cognitive decline in patients carrying the 677 T allele. Moreover, a synergistic effect was observed for the combination of decreased folate concentrations and the presence of the MTHFR 677 T allele on the atrophy of specific hippocampal subregions in patients with AD.

CONCLUSIONS

In addition to offering insights into the neuronal mechanism underlying gene-dependent folate-induced cognitive impairment in AD, these findings may have clinical significance for the allocation of auxiliary folate supplementation therapy in patients with AD with low folate levels and carrying the MTHFR 677 T allele and may eventually promote the selection of early individualized AD drug therapy.

Shining New Light on Biological Systems: Luminescent Transition Metal Complexes for Bioimaging and Biosensing Applications

Luminescence imaging is a powerful and versatile technique for investigating cell physiology and pathology in living systems, making significant contributions to life science research and clinical diagnosis. In recent years, luminescent transition metal complexes have gained significant attention for diagnostic and therapeutic applications due to their unique photophysical and photochemical properties. In this Review, we provide a comprehensive overview of the recent development of luminescent transition metal complexes for bioimaging and biosensing applications, with a focus on transition metal centers with a d6, d8, and d10 electronic configuration. We elucidate the structure-property relationships of luminescent transition metal complexes, exploring how their structural characteristics can be manipulated to control their biological behavior such as cellular uptake, localization, biocompatibility, pharmacokinetics, and biodistribution. Furthermore, we introduce the various design strategies that leverage the interesting photophysical properties of luminescent transition metal complexes for a wide variety of biological applications, including autofluorescence-free imaging, multimodal imaging, organelle imaging, biological sensing, microenvironment monitoring, bioorthogonal labeling, bacterial imaging, and cell viability assessment. Finally, we provide insights into the challenges and perspectives of luminescent transition metal complexes for bioimaging and biosensing applications, as well as their use in disease diagnosis and treatment evaluation.

Cortical lobar volume reductions associated with homocysteine-related subcortical brain atrophy and poorer cognition in healthy aging

Homocysteine (Hcy) is a cardiovascular risk factor implicated in cognitive impairment and cerebrovascular disease but has also been associated with Alzheimer's disease. In 160 healthy older adults (mean age = 69.66 ± 9.95 years), we sought to investigate the association of cortical brain volume with white matter hyperintensity (WMH) burden and a previously identified Hcy-related multivariate network pattern showing reductions in subcortical gray matter (SGM) volumes of hippocampus and nucleus accumbens with relative preservation of basal ganglia. We additionally evaluated the potential role of these brain imaging markers as a series of mediators in a vascular brain pathway leading to age-related cognitive dysfunction in healthy aging. We found reductions in parietal lobar gray matter associated with the Hcy-SGM pattern, which was further associated with WMH burden. Mediation analyses revealed that slowed processing speed related to aging, but not executive functioning or memory, was mediated sequentially through increased WMH lesion volume, greater Hcy-SGM pattern expression, and then smaller parietal lobe volume. Together, these findings suggest that volume reductions in parietal gray matter associated with a pattern of Hcy-related SGM volume differences may be indicative of slowed processing speed in cognitive aging, potentially linking cardiovascular risk to an important aspect of cognitive dysfunction in healthy aging.

There Is No Direct Causal Relationship Between Coronary Artery Disease and Alzheimer Disease: A Bidirectional Mendelian Randomization Study

BACKGROUND

The association between poor cardiovascular health and cognitive decline as well as dementia progression has been inconsistent across studies. This study used Mendelian randomization (MR) to investigate the causal relationship between Alzheimer disease (AD), circulating levels of total-tau, and coronary artery disease (CAD).

METHODS AND RESULTS

This study used MR to investigate the causal relationship between AD or circulating levels of total-tau and CAD, including ischemic heart disease, myocardial infarction, coronary heart disease, coronary atherosclerosis, and heart failure. The primary analysis used the inverse-variance weighted method, with pleiotropy and heterogeneity assessed using MR-Egger regression and the Q statistic. The overall results of the MR analysis indicated that AD did not exhibit a causal effect on heart failure (odds ratio [OR], 0.969 [95% CI, 0.921-1.018]; P=0.209), myocardial infarction (OR, 0.972 [95% CI, 0.915-1.033]; P=0.359), ischemic heart disease (OR, 1.013 [95% CI, 0.949-1.082]; P=0.700), coronary heart disease (OR, 1.005 [95% CI, 0.937-1.078]; P=0.881), or coronary atherosclerosis (OR, 0.987 [95% CI, 0.926-1.052]; P=0.690). No significant causal effect of CAD was observed on AD in the reverse MR analysis. Additionally, our findings revealed that CAD did not influence circulating levels of total-tau, nor did circulating levels of total-tau increase the risk of CAD. Sensitivity analysis and assessment of horizontal pleiotropy suggested that these factors did not distort the causal estimates.

CONCLUSIONS

The findings of this study indicate the absence of a direct causal relationship between AD and CAD from a genetic perspective. Therefore, managing the 2 diseases should be more independent and targeted. Concurrently, investigating the mechanism underlying their comorbidity may not yield meaningful insights for advancing treatment strategies.

Investigation of interactions between biological thiols and gold nanoparticles by capillary electrophoresis with laser-induced fluorescence

Biological thiols spontaneously form a stable Au-S dative bond with gold nanoparticles (AuNP) that might be used for their selective extraction and enrichment in biological samples. In this work, interactions of selected biological thiols (glutathione, cysteine, homocysteine [Hcys], cysteamine [CA], and N-acetylcysteine) with AuNP stabilized by different capping agents (citrate, Tween 20, Brij 35, CTAB, SDS) were investigated by UV-Vis spectroscopy and capillary electrophoresis with laser-induced fluorescence. Spectrophotometric measurements showed aggregation of Hcys and CA with AuNP. In contrast, it was confirmed by CE-LIF that biological thiols were adsorbed to all types of AuNP. Citrate-capped AuNP were selected for AuNP-based extraction of biological thiols from exhaled breath condensate (EBC). Dithiothreitol was utilized for desorption of biological thiols from the AuNP surface, which was followed by derivatization with eosin-5-maleimide and CE-LIF analysis. AuNP-based extraction increased the sensitivity of CE-LIF analysis; however, further optimization of methodology is necessary for accurate quantification of biological thiols in EBC.

The Impact of the Dietary Intake of Vitamin B12, Folic Acid, and Vitamin D3 on Homocysteine Levels and the Health-Related Quality of Life of Levodopa-Treated Patients with Parkinson's Disease-A Pilot Study in Romania

BACKGROUND AND OBJECTIVES

Previous studies have shown that the levodopa treatment of Parkinson's disease (PD) elevates circulating homocysteine levels, which are associated with an increased risk of cardiovascular and neurological disorders, or thrombosis. The present trial aimed to examine whether the intake of vitamin B12, folic acid, and vitamin D3 supplements improved homocysteine level and quality of life (QoL).

MATERIALS AND METHODS

An interventional prospective trial was conducted in multiple centers across Romania. Participants with clinically established PD taking at least 300 mg/day of levodopa for more than 1 year received a daily tablet of a supplement containing 800 UI of vitamin D3, 1000 µg of folic acid, and 15 µg of vitamin B12. They were followed for 6 months and their serum homocysteine, vitamin B12, vitamin D, and QoL scores were measured at baseline and at 6 months of treatment. QoL was measured using a 15D questionnaire, which assesses mobility, vision, hearing, breathing, sleeping, eating, speech, excretion, usual activities, mental function, discomfort and symptoms, depression, distress, vitality, and sexual activity.

RESULTS

Twenty-four PD patients with a mean age of 71 ± 5.04 years (54.2% male and 45.8% female) finished the study. After the intervention, the mean score of speech, mental function, discomfort and symptoms, depression, and QoL significantly increased (p < 0.05 for all). Also, the serum homocysteine and vitamin D were significantly enhanced (p < 0.0001 and p = 0.025, respectively). Changes in vitamin B12 were not statistically significant at 6 months of treatment (p = 0.996). No gender differences were found among the changes that we have demonstrated for homocysteine, vitamin B12, vitamin D, and QoL levels (p < 0.05 for all).

CONCLUSIONS

The findings of this study showed that the dietary intake of vitamin B12, folic acid, and vitamin D3 remarkably decreased the dimensions of homocysteine and finally increased the total score of QoL in PD patients. We have successfully captured the potential benefits of the supplementation regimen over time and provided insights into the broader implications for managing PD with a focus on nutritional support.

Homocysteine Thiolactone Detoxifying Enzymes and Alzheimer's Disease

Elevated levels of homocysteine (Hcy) and related metabolites are associated with Alzheimer's disease (AD). Severe hyperhomocysteinemia causes neurological deficits and worsens behavioral and biochemical traits associated with AD. Although Hcy is precluded from entering the Genetic Code by proofreading mechanisms of aminoacyl-tRNA synthetases, and thus is a non-protein amino acid, it can be attached to proteins via an N-homocysteinylation reaction mediated by Hcy-thiolactone. Because N-homocysteinylation is detrimental to a protein's function and biological integrity, Hcy-thiolactone-detoxifying enzymes-PON1, BLMH, BPHL-have evolved. This narrative review provides an account of the biological function of these enzymes and of the consequences of their impairments, leading to the phenotype characteristic of AD. Overall, accumulating evidence discussed in this review supports a hypothesis that Hcy-thiolactone contributes to neurodegeneration associated with a dysregulated Hcy metabolism.

Elevated Blood Homocysteine Increases the Risk of Incident Motoric Cognitive Risk Syndrome: A Two-Cohort Study

BACKGROUND

Motoric Cognitive Risk (MCR) syndrome, a predementia syndrome characterized by cognitive complaints and slow gait, may have an underlying vascular etiology. Elevated blood levels of homocysteine, a known vascular risk factor, have been linked to physical and cognitive decline in older adults, though the relationship with MCR is unknown. We aimed to identify the association between homocysteine and MCR risk.

METHODS

We examined the association between baseline homocysteine levels and incident MCR using Cox proportional hazard models in 1826 community-dwelling older adults (55% women) from 2 cohorts (Einstein Aging Study [EAS] and Quebec Longitudinal Study on Nutrition and Successful Aging [NuAge]). We calculated hazard ratios (HR) with 95% confidence intervals (CI), for each cohort as well as stratified by sex and vascular disease/risk factors.

RESULTS

Median follow-up time was 2.2 years in EAS and 3.0 years in NuAge. Individuals with elevated baseline homocysteine levels (>14 µmol/L) had a significantly higher risk of incident MCR compared to those with normal levels in NuAge (HR 1.41, 95% CI: 1.01-1.97, p = .04), after adjusting for covariates. Our exploratory stratified analyses found that these associations were significant only in men with vascular disease/risk factors.

CONCLUSIONS

Higher blood homocysteine levels are associated with an increased risk of developing MCR in older adults, particularly in men with vascular disease or vascular risk factors.

Causal association between phenylalanine and Parkinson's disease: a two-sample bidirectional mendelian randomization study

Background

Research findings indicate a putative indirect or latent association between phenylalanine (Phe) and Parkinson's disease (PD). In this study, we aimed to analyze the causal relationship between Phe and PD by two sample Mendelian randomization (MR) analysis.

Methods

In this study, the PD-related dataset and Phe-related dataset were downloaded from Integrative Epidemiology U1nit (IEU) Open Genome-Wide Association Study (GWAS) database. Four algorithms (MR Egger, maximum likelihood, inverse variance weighting (IVW) and unweighted regression) were used to perform MR analysis. The sensitivity analysis (heterogeneity test, horizontal pleiotropy test and Leave-One-Out (LOO) analysis) was used to assess the reliability of MR analyses.

Results

In the forward MR analysis, Phe was a safety factor for PD (p-value < 0.05 and odds ratios (OR) < 1). The results of reverse MR analysis showed that there was no causal relationship between PD and Phe (p-value > 0.05). In addition, sensitivity analysis showed that MR analysis was reliable.

Conclusion

The results of this study revealed that Phe was a safety factor for PD, meaning that Phe reduced the risk of PD.

High plasma homocysteine levels predict the progression from mild cognitive impairment to dementia

High levels of blood homocysteine (HCy), a well-known cardiovascular risk factor and promoter of oxidative stress, have been associated with the incidence of cognitive impairment and dementia. Nonetheless, contrasting data are still present on its involvement in the progression from Mild Cognitive Impairment (MCI) to overt dementia. In this study we aimed to observe whether blood HCy level are associated with the evolution from MCI, divided into amnestic MCI (aMCI) and non-amnestic MCI (naMCI), to dementia. Blood HCy was measured in 311 MCI subjects (aMCI: 64%, naMCI: 36%) followed-up for a median of 33 months (range 10-155 months). At follow-up, 137 individuals converted to dementia (naMCI, n = 34; aMCI, n = 103). Based on HCy distribution, subjects in the highest tertile had a greater risk to convert to dementia compared to tertile I (Hazard Ratio (95% confidence interval): 2.25 (1.05-4.86); p = 0.04). aMCI subjects did not show increased risk to convert to dementia with increasing HCy concentration, but was significant in naMCI (p = 0.04). We observed a non-significant increase in the risk of progression to dementia from naMCI/low HCy (reference group, HCy cutoff value = 16 μmol/L) to naMCI/high HCy, but it was significant from aMCI/low HCy (HR: 2.73; 95%CI: 1.06-7.0; p:0.03), to aMCI/high HCy (HR: 3.24; 95%CI: 1.17-8.47; p:0.02). Our results suggest that HCy levels are associated with the progression from MCI to dementia. This association seems significant only for the naMCI group, indirectly supporting the notion that hyperhomocysteinemia damages the nervous system through its role as a vascular risk factor.

Unraveling the Hippocampal Molecular and Cellular Alterations behind Tramadol and Tapentadol Neurobehavioral Toxicity

Tramadol and tapentadol are chemically related opioids prescribed for the analgesia of moderate to severe pain. Although safer than classical opioids, they are associated with neurotoxicity and behavioral dysfunction, which arise as a concern, considering their central action and growing misuse and abuse. The hippocampal formation is known to participate in memory and learning processes and has been documented to contribute to opioid dependence. Accordingly, the present study assessed molecular and cellular alterations in the hippocampal formation of Wistar rats intraperitoneally administered with 50 mg/kg tramadol or tapentadol for eight alternate days. Alterations were found in serum hydrogen peroxide, cysteine, homocysteine, and dopamine concentrations upon exposure to one or both opioids, as well as in hippocampal 8-hydroxydeoxyguanosine and gene expression levels of a panel of neurotoxicity, neuroinflammation, and neuromodulation biomarkers, assessed through quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis of hippocampal formation sections showed increased glial fibrillary acidic protein (GFAP) and decreased cluster of differentiation 11b (CD11b) protein expression, suggesting opioid-induced astrogliosis and microgliosis. Collectively, the results emphasize the hippocampal neuromodulator effects of tramadol and tapentadol, with potential behavioral implications, underlining the need to prescribe and use both opioids cautiously.

Phosphorescent iridium (III) complex with covalent organic frameworks as scaffolds for highly selective and sensitive detection of homocysteine

Introduction: Developing a convenient and cost-effective platform for detecting homocysteine (Hcy) is of great interest as Hcy has been found to be a biomarker for Alzheimer's disease, gastric cancer, and other diseases. Methods: In this study, we synthesized five phosphorescent Ir(C∧N)2(N∧N)+ compounds (Irn, n = 1-5) with various substituents (-CHO or -CHO/-NH2), which were then doped into a covalent organic framework (COF) host via covalent bonding. Results and Discussion: The resulting optimal composites (denoted as Ir4/5@EBCOF) with -CHO/-NH2 substituents not only overcame the self-quenching issue of the bare Ir4/5 complexes but also showed rapid, highly selective, and sensitive detection of Hcy, with a limit of detection (LOD) of 0.23 μM and reaction time of 88 s. The sensing mechanism was revealed as the unique cyclization reaction between Ir(III) and Hcy that forms a six-membered ring. During the process, the color changes in the composites can be observed visually. It is expected that these phosphorescent Iridium (III) complexes with COFs will have the potential to serve as promising platforms for detecting thiols.

Nutrition for dementia prevention: a state of the art update for clinicians

BACKGROUND AND OBJECTIVES

Dementia prevalence continues to rise. It is therefore essential to provide feasible and effective recommendations to encourage healthy brain ageing and reduce dementia risk across the population. Appropriate nutrition represents a potential strategy to mitigate dementia risk and could be recommended by clinicians as part of mid-life health checks and other health initiatives to reduce dementia prevalence. The purpose of this review is to provide a clinician-focused update on the current state of the knowledge on nutrition and dementia prevention.

METHODS

Narrative review.

RESULTS

Strong evidence exists to support the consumption of healthy, plant-based dietary patterns (e.g. Mediterranean, MIND or Nordic diet) for maintaining cognitive function and reducing dementia risk in later life and is supported by dementia prevention guideline from leading public health bodies (e.g. World Health Organization). Emerging evidence suggests potential cognitive benefits of consuming specific nutrients/foods (e.g. n-3 fatty acids or fish, flavonols and B-vitamins) and multi-nutrient compounds (e.g. Fortasyn Connect). Challenges and opportunities for integrating nutritional/dietary interventions for dementia prevention into clinical practice are explored in this review.

CONCLUSIONS

Appropriate nutrition represents an important factor to help facilitate healthy cognitive ageing and allay dementia risk. The information provided in this article can help clinicians provide informed opinions on appropriate nutritional strategies as part of mid-life Health Checks and other risk reduction initiatives.

GWAS of Folate Metabolism With Gene-environment Interaction Analysis Revealed the Possible Role of Lifestyles in the Control of Blood Folate Metabolites in Japanese: The J-MICC Study

BACKGROUND

The present genome-wide association study (GWAS) aimed to reveal the genetic loci associated with folate metabolites, as well as to detect related gene-environment interactions in Japanese.

METHODS

We conducted the GWAS of plasma homocysteine (Hcy), folic acid (FA), and vitamin B12 (VB12) levels in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study participants who joined from 2005 to 2012, and also estimated gene-environment interactions. In the replication phase, we used data from the Yakumo Study conducted in 2009. In the discovery phase, data of 2,263 participants from four independent study sites of the J-MICC Study were analyzed. In the replication phase, data of 573 participants from the Yakumo Study were analyzed.

RESULTS

For Hcy, MTHFR locus on chr 1, NOX4 on chr 11, CHMP1A on chr 16, and DPEP1 on chr 16 reached genome-wide significance (P < 5 × 10-8). MTHFR also associated with FA, and FUT2 on chr 19 associated with VB12. We investigated gene-environment interactions in both studies and found significant interactions between MTHFR C677T and ever drinking, current drinking, and physical activity >33% on Hcy (β = 0.039, 0.038 and -0.054, P = 0.018, 0.021 and <0.001, respectively) and the interaction of MTHFR C677T with ever drinking on FA (β = 0.033, P = 0.048).

CONCLUSION

The present GWAS revealed the folate metabolism-associated genetic loci and gene-environment interactions with drinking and physical activity in Japanese, suggesting the possibility of future personalized cardiovascular disease prevention.

Serum folate and risk of disabling dementia: a community-based nested case-control study

PURPOSE

The aim of this study was to examine associations between serum folate levels and risk of disabling dementia that required care under the national insurance (disabling dementia).

METHODS

We performed a nested case-control study in a community-based cohort, the Circulatory Risk in Communities Study, involving 13,934 Japanese individuals aged 40-84 years at the baseline period of 1984-2005. Serum folate was measured in 578 cases of incident disabling dementia, and in 1,156 controls whose age (±1 years), sex, area of residence, and baseline year were matched with the cases. The diagnosis of disabling dementia was performed by attending physicians under the National Long-Term Care Insurance System in Japan. Conditional odds ratios of disabling dementia according to quintiles of serum folate were calculated using conditional logistic regression models.

RESULTS

After a 20.8-year follow-up, serum folate was inversely associated with risk of disabling dementia. The respective multivariable odds ratios (95% CIs) were 0.71 (0.51-0.99), 0.76 (0.54-1.06), 0.70 (0.49-1.00), and 0.62 (0.43-0.90) for persons with the second, third, fourth, and highest quintiles of serum folate as compared with the lowest quintile (P for trend = 0.03). A similar association was observed for dementia with or without stroke.

CONCLUSION

In this nested case-control study with a long follow-up, low serum folate levels were associated with an increased risk of disabling dementia among Japanese individuals.

Homocysteine-induced sustained GluN2A NMDA receptor stimulation leads to mitochondrial ROS generation and neurotoxicity

Homocysteine, a sulfur-containing amino acid derived from methionine metabolism, is a known agonist of N-methyl-D-aspartate receptor (NMDAR) and is involved in neurotoxicity. Our previous findings showed that neuronal exposure to elevated homocysteine levels leads to sustained low-level increase in intracellular Ca2+, which is dependent on GluN2A subunit-containing NMDAR (GluN2A-NMDAR) stimulation. These studies further showed a role of ERK MAPK in homocysteine-GluN2A-NMDAR-mediated neuronal death. However, the intracellular mechanisms associated with such sustained GluN2A-NMDAR stimulation and subsequent Ca2+ influx have remained unexplored. Using live-cell imaging with Fluo3-AM and biochemical approaches, we show that homocysteine-GluN2A NMDAR-induced initial Ca2+ influx triggers sequential phosphorylation and subsequent activation of the proline rich tyrosine kinase 2 (Pyk2) and Src family kinases, which in turn phosphorylates GluN2A-Tyr1325 residue of GluN2A-NMDARs to maintain channel activity. The continuity of this cycle of events leads to sustained Ca2+ influx through GluN2A-NMDAR. Our findings also show that lack of activation of the regulatory tyrosine phosphatase STEP, which can limit Pyk2 and Src family kinase activity further contributes to the maintenance of this cycle. Additional studies using live-cell imaging of neurons expressing a redox-sensitive GFP targeted to the mitochondrial matrix show that treatment with homocysteine leads to a progressive increase in mitochondrial reactive oxygen species generation, which is dependent on GluN2A-NMDAR-mediated sustained ERK MAPK activation. This later finding demonstrates a novel role of GluN2A-NMDAR in homocysteine-induced mitochondrial ROS generation and highlights the role of ERK MAPK as the intermediary signaling pathway between GluN2A-NMDAR stimulation and mitochondrial reactive oxygen species generation.

Nonlinear Relationship Between Homocysteine and Mild Cognitive Impairment in Early Parkinson's Disease: A Cross-Sectional Study

Background

Cognitive impairment, a prevalent non-motor symptom in advanced Parkinson's disease (PD), has been associated with hyperhomocysteinemia, an important risk factor for PD progression and cognitive decline in PD. However, evidence regarding the association between homocysteine (Hcy) and cognitive function during early PD remains insufficient. Therefore, this study aims to examine the correlation between Hcy levels and cognitive function in the early stage of PD.

Methods

The study included 218 individuals in the early stages of PD who were consecutively admitted to the Suining Central Hospital Neurology Department. All the individuals completed the Parkinson's Disease Cognitive Rating Scale (PD-CDR). The Unified Parkinson's Disease Rating Scale part III (UPDRS-III) was employed for measuring the severity of motor symptoms, while the Hoehn-Yahr scale was used to measure the clinical symptom stage. Fasting venous blood samples were also drawn to measure the Hcy concentration, red blood cell folate, and vitamin B12.

Results

In this cross-sectional study, 47 (21.5%) patients with PD showed cognitive dysfunction. The serum Hcy levels were significantly higher in the cognitive impairment PD (PDCI) group compared with the cognitive normal PD group (P<0.001). The Generalized Additive Model (GAM) analysis revealed a nonlinear relationship between Hcy and the risk of PDCI. Multiple logistic regression analyses demonstrated a positive relationship between elevated Hcy and the risk of PDCI in the fully adjusted model ([OR]:3.1, 95% CI, 1.1-8.5, P=0.028). Segmented linear regression analysis showed that when Hcy levels were above 17.7 umol/l, the risk of PDCI increased by 1.6 times for every 1 unit elevated in Hcy (95% CI:1.1-2.2, P=0.008).

Conclusion

This study revealed a nonlinear positive correlation between the risk of PDCI and elevated serum Hcy levels in early PD patients, suggesting hyperhomocysteinemia as one of the treatable factors for cognitive impairment in the early stages of PD.

Choline Metabolites Reverse Differentially the Habituation Deficit and Elevated Memory of Tau Null Drosophila

Impaired neuronal plasticity and cognitive decline are cardinal features of Alzheimer's disease and related Tauopathies. Aberrantly modified Tau protein and neurotransmitter imbalance, predominantly involving acetylcholine, have been linked to these symptoms. In Drosophila, we have shown that dTau loss specifically enhances associative long-term olfactory memory, impairs foot shock habituation, and deregulates proteins involved in the regulation of neurotransmitter levels, particularly acetylcholine. Interestingly, upon choline treatment, the habituation and memory performance of mutants are restored to that of control flies. Based on these surprising results, we decided to use our well-established genetic model to understand how habituation deficits and memory performance correlate with different aspects of choline physiology as an essential component of the neurotransmitter acetylcholine, the lipid phosphatidylcholine, and the osmoregulator betaine. The results revealed that the two observed phenotypes are reversed by different choline metabolites, implying that they are governed by different underlying mechanisms. This work can contribute to a broader knowledge about the physiologic function of Tau, which may be translated into understanding the mechanisms of Tauopathies.

Highly-ordered assembled organic fluorescent materials for high-resolution bio-sensing: a review

Organic fluorescent materials (OFMs) play a crucial role in the development of biosensors, enabling the extraction of biochemical information within cells and organisms, extending to the human body. Concurrently, OFM biosensors contribute significantly to the progress of modern medical and biological research. However, the practical applications of OFM biosensors face challenges, including issues related to low resolution, dispersivity, and stability. To overcome these challenges, scientists have introduced interactive elements to enhance the order of OFMs. Highly-ordered assembled OFMs represent a novel material type applied to biosensors. In comparison to conventional fluorescent materials, highly-ordered assembled OFMs typically exhibit robust anti-diffusion properties, high imaging contrast, and excellent stability. This approach has emerged as a promising method for effectively tracking bio-signals, particularly in the non-invasive monitoring of chronic diseases. This review introduces several highly-ordered assembled OFMs used in biosensors and also discusses various interactions that are responsible for their assembly, such as hydrogen bonding, π-π interaction, dipole-dipole interaction, and ion electrostatic interaction. Furthermore, it delves into the various applications of these biosensors while addressing the drawbacks that currently limit their commercial application. This review aims to provide a theoretical foundation for designing high-performance, highly-ordered assembled OFM biosensors suitable for practical applications. Additionally, it sheds light on the evolving trends in OFM biosensors and their application fields, offering valuable insights into the future of this dynamic research area.

Fruit and Vegetable Intake and Risk of Disabling Dementia: Japan Public Health Center Disabling Dementia Study

BACKGROUND

Fruits and vegetables contain abundant amounts of antioxidant vitamins such as vitamin C, α-carotene, and β-carotene. Few prospective observational studies have investigated the effects of fruit and vegetable intake on the risk of dementia, and the results are inconsistent.

OBJECTIVES

Our aim was to examine associations between fruit and vegetable intake and the risk of disabling dementia.

METHODS

We conducted a follow-up survey within the Japan Public Health Center-based Prospective Study involving 42,643 individuals aged 50-79 y at baseline (2000-2003). Dietary fruit and vegetable intakes and related antioxidant vitamin intakes (i.e., α-carotene, β-carotene, and vitamin C) were determined using a food frequency questionnaire. The diagnosis of disabling dementia was made based on the daily living disability status related to dementia under the Japanese long-term care insurance program from 2006 to 2016. Hazard ratios and 95% confidence intervals for disabling dementia were estimated using area-stratified Cox proportional hazard models adjusted for potential confounding factors.

RESULTS

A total of 4994 cases of disabling dementia were recorded. We observed an inverse association between total fruit and vegetable intake and the risk of dementia among males and females: the multivariate hazard ratios (95% confidence intervals) for the highest compared with lowest quartiles of intake were 0.87 (0.76, 0.99) (P- trend = 0.05) among males and 0.85 (0.76, 0.94) (P- trend = 0.006) among females. Among antioxidant vitamins, vitamin C intake was inversely associated with the risk of dementia among males and females: the multivariate hazard ratios (95% confidence intervals) for the highest compared with lowest quartiles of intake were 0.71 (0.61, 0.84) (P- trend < 0.0001) among males, and 0.76 (0.67, 0.86) (P- trend < 0.0001) among females.

CONCLUSIONS

Fruit and vegetable intake and dietary intake of vitamin C may contribute to reducing the risk of disabling dementia among males and females.

Lysine ε-aminolysis and incorporation of sulfhydryl groups into human brain tau 4R/1N and 306VQIVYK311 enhances the formation of beta structures and toxicity

In the present study, we investigated the effects of N-homocysteine thiolactone (tHcy) modification on expressed and purified tau protein and the synthesized VQIVYK target peptide. The modified constructs were subjected to comprehensive validation using various methodologies, including mass spectrometry. Subsequently, in vivo, in vitro, and in silico characterizations were performed under both reducing and non-reducing conditions, as well as in the presence and absence of heparin as a cofactor. Our results unequivocally confirmed that under reducing conditions and in the presence of heparin, the modified constructs exhibited a greater propensity for aggregation. This enhanced aggregative behavior can be attributed to the disruption of lysine positive charges and the subsequent influence of hydrophobic and p-stacking intermolecular forces. Notably, the modified oligomeric species induced apoptosis in the SH-SY5Y cell line, and this effect was further exacerbated with longer incubation times and higher concentrations of the modifier. These observations suggest a potential mechanism involving reactive oxygen species (ROS). To gain a deeper understanding of the molecular mechanisms underlying the neurotoxic effects, further investigations are warranted. Elucidating these mechanisms will contribute to the development of more effective strategies to counteract aggregation and mitigate neurodegeneration.

Vascular dementia: From pathobiology to emerging perspectives

Vascular dementia (VaD) is the second most common type of dementia. VaD is synonymous with ageing, and its symptoms place a significant burden on the health and wellbeing of older people. Despite the identification of a substantial number of risk factors for VaD, the pathological mechanisms underpinning this disease remain to be fully elucidated. Consequently, a biogerontological imperative exists to highlight the modifiable lifestyle factors which can mitigate against the risk of developing VaD. This review will critically examine some of the factors which have been revealed to modulate VaD risk. The survey commences by providing an overview of the putative mechanisms which are associated with the pathobiology of VaD. Next, the factors which influence the risk of developing VaD are examined. Finally, emerging treatment avenues including epigenetics, the gut microbiome, and pro-longevity pharmaceuticals are discussed. By drawing this key evidence together, it is our hope that it can be used to inform future experimental investigations in this field.

Association between Helicobacter pylori infection and incident risk of dementia: The AMI cohort

BACKGROUND

Chronic infectious diseases are increasingly being considered as potential contributors to dementia risk. Among those infections, Helicobacter pylori, the main cause of chronic gastritis worldwide, has been suggested. As the prevalence of H. pylori infection has decreased, the main objective of this work was to reconsider the association between H. pylori infection and the risk of incident dementia, including Alzheimer's disease.

METHODS

Prospective cohort of 689 older (≥65 years) agricultural workers from Southwest France. Descriptive and comparative analyses were performed according to H. pylori status determined by serology at baseline. The risk of incident dementia according to H. pylori status over a 7-year follow-up was explored by survival analyses: Kaplan-Meier curve and Cox proportional hazards models.

RESULTS

Two-hundred (29.0%) participants were H. pylori-positive at baseline. Compared to H. pylori-negative participants, they showed worse cognitive performances at baseline. Eighty-five incident dementia cases were diagnosed during the follow-up period. After adjustment for age, sex, education, apolipoprotein ε4, and several cardiovascular risk factors, H. pylori remained associated with an increased risk of dementia (HR 1.70, 95% CI, 1.05-2.74). The risk was stronger for Alzheimer's disease (HR 2.85, 95% CI, 1.58-5.12).

CONCLUSIONS

Despite an observed decrease in H. pylori infection prevalence, this study provides evidence for the association between H. pylori infection and dementia. These results should encourage further research on the mechanisms underlying the contribution of infectious diseases to pathological brain aging, especially the influence of gut inflammation on the brain.

Personalized, Precision Medicine to Cure Alzheimer's Dementia: Approach #1

The goal of the treatment for Alzheimer's dementia (AD) is the cure of dementia. A literature review revealed 18 major elements causing AD and 29 separate medications that address them. For any individual with AD, one is unlikely to discern which major causal elements produced dementia. Thus, for personalized, precision medicine, all causal elements must be treated so that each individual patient will have her or his causal elements addressed. Twenty-nine drugs cannot concomitantly be administered, so triple combinations of drugs taken from that list are suggested, and each triple combination can be administered sequentially, in any order. Ten combinations given over 13 weeks require 2.5 years, or if given over 26 weeks, they require 5.0 years. Such sequential treatment addresses all 18 elements and should cure dementia. In addition, any comorbid risk factors for AD whose first presence or worsening was within ±1 year of when AD first appeared should receive appropriate, standard treatment together with the sequential combinations. The article outlines a randomized clinical trial that is necessary to assess the safety and efficacy of the proposed treatments; it includes a triple-drug Rx for equipoise. Clinical trials should have durations of both 2.5 and 5.0 years unless the data safety monitoring board (DSMB) determines earlier success or futility since it is uncertain whether three or six months of treatment will be curative in humans, although studies in animals suggest that the briefer duration of treatment might be effective and restore defective neural tracts.

Diet-induced hyperhomocysteinemia causes sex-dependent deficiencies in offspring musculature and brain function

Hyperhomocysteinemia (HHcy), characterized by elevated homocysteine (Hcy) levels, is a known risk factor for cardiovascular, renal, and neurological diseases, as well as pregnancy complications. Our study aimed to investigate whether HHcy induced by a high-methionine (high-Met) diet exacerbates cognitive and behavioral deficits in offspring and leads to other breeding problems. Dietary HHcy was induced four weeks before mating and continued throughout gestation and post-delivery. A battery of behavioral tests was conducted on offspring between postnatal days (PNDs) 5 and 30 to assess motor function/activity and cognition. The results were correlated with brain morphometric measurements and quantitative analysis of mammalian target of rapamycin (mTOR)/autophagy markers. The high-Met diet significantly increased parental and offspring urinary tHcy levels and influenced offspring behavior in a sex-dependent manner. Female offspring exhibited impaired cognition, potentially related to morphometric changes observed exclusively in HHcy females. Male HHcy pups demonstrated muscle weakness, evidenced by slower surface righting, reduced hind limb suspension (HLS) hanging time, weaker grip strength, and decreased activity in the beaker test. Western blot analyses indicated the downregulation of autophagy and the upregulation of mTOR activity in HHcy cortexes. HHcy also led to breeding impairments, including reduced breeding rate, in-utero fetal death, lower pups' body weight, and increased mortality, likely attributed to placental dysfunction associated with HHcy. In conclusion, a high-Met diet impairs memory and cognition in female juveniles and weakens muscle strength in male pups. These effects may stem from abnormal placental function affecting early neurogenesis, the dysregulation of autophagy-related pathways in the cortex, or epigenetic mechanisms of gene regulation triggered by HHcy during embryonic development.

A Enhanced Fluorescent Probe for Simultaneous Detection and Discrimination of Hydrogen Bisulfite Anions and Glutathione

Bisulfite (HSO3-) and biological thiols molecules, such as glutathione (GSH), cysteine (Cys), and homocysteine (Hcy), play important roles in organisms. Developing a fluorescent probe that can simultaneously detect and distinguish HSO3- and biological thiols is of great significance. In this study, ethyl(2E,4Z)-5-chloro-2-cyano-5-(7-(diethylamino)-2-oxo-2 H-chromen-3-yl)penta-2,4-dienoate (CCO) as a novel enhanced fluorescence probe was synthesized by integrating coumarin derivatives and ethyl cyanoacetate, which can simultaneous detection and discrimination of hydrogen bisulfite anions and glutathione. The sensing mechanism was elucidated through spectral analysis and some control experiments. In weakly alkaline environments, the probe not only has good selectivity for HSO3- and GSH, but also has a lower detection limits of 0.0179 µM and 0.2034 µM. The probe exhibited fuorescent turn-on for distinguishing with 296 and 28 fold the fluorescent intensity increase at 486 and 505 nm, respectively, through diferent excitation wavelengths. This provides a new method for simultaneous detection and discrimination of HSO3- and biological thiol cell levels and further applications.

Diet Pattern Analysis in Alzheimer's Disease Implicates Gender Differences in Folate-B12-Homocysteine Axis on Cognitive Outcomes

BACKGROUND & AIMS

Low plasma B12 and folate levels or hyperhomocysteinemia are related to cognitive impairment. This study explores the relationships among diet pattern, blood folate-B12-homocysteine levels, and cognition measurement in Alzheimer's disease (AD) while exploring whether a gender effect may exist.

METHODS

This cross-sectional study enrolled 592 AD patients (246 males, 346 females) and the demographic data, blood biochemical profiles, Mini-Mental State Examination (MMSE), and a Food Frequency Questionnaire (FFQ) for quantitative assessment of dietary frequency were collected. Structural Equation Modeling (SEM) was employed to explore the associations among dietary patterns, blood profiles, and cognition. A least absolute shrinkage and selection operator regression model, stratified by gender, was constructed to analyze the weighting of possible confounders.

RESULTS

Higher MMSE scores were related to higher frequencies of coffee/tea and higher educational levels, body mass index, and younger age. The SEM model revealed a direct influence of dietary frequencies (skimmed milk, thin pork, coffee/tea) and blood profiles (homocysteine, B12, and folate) on cognitive outcomes. At the same time, the influence of dietary pattern on cognition was not mediated by folate-B12-homocysteine levels. In males, a direct influence on the MMSE is attributed to B12, while in females, homocysteine is considered a more critical factor.

CONCLUSIONS

Dietary patterns and blood profiles are both associated with cognitive domains in AD, and there are gender differences in the associations of dietary patterns and the levels of B12 and homocysteine. To enhance the quality of dietary care and nutritional status for individuals with dementia, our study results still require future validations with multi-center and longitudinal studies.

Elevated homocysteine levels may moderate and mediate the association between HIV and cognitive impairment among middle-aged and older adults in an underserved population in Baltimore, Maryland

Background: In the antiretroviral therapy (ART) era, HIV-associated neurocognitive disorders (HAND) remain a considerable challenge for people with HIV, yet not all such disorders can be attributed to HIV alone. This study aimed to: (1) identify factors influencing neurocognitive impairment (NCI) utilizing the NIH Toolbox Cognition Battery (NIHTB-CB) as per the revised research criteria for HAND; (2) ascertain the moderating role of high homocysteine levels in the association between NCI and HIV; and (3) assess the mediating effect of elevated homocysteine levels on this association.Methods: We analyzed data from 788 adults (≥45 years) participating in a study on HIV-related comorbidities in underserved Baltimore communities, using NIHTB-CB to gauge neurocognitive performance. Special attention was given to results from the Dimensional Change Card Sort (DCCS) test within the executive function domain during causal mediation analysis.Results: Overall, HIV was not associated with NCI presence. However, HIV was associated with NCI among individuals with homocysteine >14 μmol/L. Furthermore, HIV was both directly and indirectly associated with NCI in DCCS test scores. Notably, the mediating role of elevated homocysteine in DCCS scores was only observable among individuals who had never used cocaine or had used it for ≤ 10 years, suggesting that extended cocaine use may have a substantial influence on cognitive performance.Conclusions: The findings from this study suggest elevated homocysteine levels may moderate and mediate the association between HIV and neurocognitive impairment.

MOF-polymer composites with well-distributed gold nanoparticles for visual monitoring of homocysteine

The distribution of gold nanoparticles (AuNPs) on the surface of a metal-organic framework (MOF) plays a crucial role in the catalytic performance of MOF-AuNP composites. This study describes how the physical adsorption (PH@AuNPs-on-U) and chemical modification of AuNPs on the surface of UiO-66-NH2 (U) affect the composites' catalytic efficiency. After 2-vinyl-4,4-dimethyl-2-oxazolin-5-one (VD) linked to poly(N-2-hydroxypropyl methacrylamide) (PH) with U (UVD-PH), UVD-PH@AuNPs composites were constructed with PH as the capping and reducing reagent. The composites exhibited higher peroxidase (POD)-like activity than PH@AuNPs-on-U for oxidising 3,3'5,5'-tetramethylbenzidine (TMB) with H2O2. The approach demonstrated that the proposed composite-based nanozymes could significantly enhance their catalytic activity and had a highly uniform distribution of PH@AuNPs on the surface of UVD. An assay with the nanozymes for visual detection of homocysteine (Hcy) was developed, displaying a good linear relationship (R2 = 0.998) ranging from 3.34 μM to 30.0 μM and a detection of limit of 0.3 μM. Additionally, the UVD-PH@AuNPs-TMB-H2O2 system successfully monitored serum Hcy after intraperitoneal injection in rats. This study paves a new way for developing MOF-AuNPs with highly uniform surface distribution of polymer@AuNPs to boost its catalytic activity and to detect drugs in real bio-samples.

Deficiencies in one-carbon metabolism led to increased neurological disease risk and worse outcome: homocysteine is a marker of disease state

Elevated plasma homocysteine levels have been identified as a significant, independent risk factor for the development of cognitive decline including Alzheimer's disease. While several studies have explored the link between homocysteine and disease risk, the associations have not been entirely clear. Elevated levels of homocysteine serve as a disease marker and understanding the underlying cause of these increased levels (e.g., dietary or genetic deficiency in one-carbon metabolism, 1C) will provide valuable insights into neurological disease risk and outcomes. Previous cell culture experiments investigating the mechanisms involved used ultra-high levels of homocysteine that are not observed in human patients. These studies have demonstrated the negative impacts of ultra-high levels of homocysteine can have on for example proliferation of neuroprogenitor cells in the adult hippocampus, as well as triggering neuronal apoptosis through a series of events, including DNA damage, PARP activation, NAD depletion, mitochondrial dysfunction, and oxidative stress. The aim of this mini-review article will summarize the literature on deficiencies in 1C and how they contribute to disease risk and outcomes and that homocysteine is a marker of disease.

Nutrition, Exercise, and Cognitive Rehabilitation for Dementia Prevention

Dementia is one of the most significant global challenges in medical and social care in the 21st century. It affects not only the patients themselves, but also their families, caregivers, and society in general, causing physical, psychological, and socioeconomic effects. As of 2020, there are approximately 6 million people in Japan aged 65 or older with dementia, and this number is expected to increase to around 7 million by 2025, meaning that one out of every five elderly people will have dementia. To prevent the onset and progression of dementia, it is crucial to have a proper understanding of its risks and adopt a healthy lifestyle. Leading an active life from an early stage can also aid in delaying or preventing the onset of dementia. Livingston has identified 12 risks that can lead to dementia, including physical inactivity, smoking, excessive alcohol consumption, air pollution, head injury, social isolation, poor educational history, obesity, hypertension, diabetes, depression, and hearing loss. Modifying one's lifestyle and leading an active life can be crucial in reducing these risks. The Mediterranean diet is gaining attention as a good practice for dementia prevention due to its diversity, richness in omega-3 fatty acids and vitamins. Exercise has been shown to prevent dementia on biological, behavioral, and socio-psychological levels. Repetitive transcranial magnetic stimulation is a non-invasive brain stimulation method that can alter brain plasticity and is being studied for clinical applications as a non-drug therapy for preventing dementia progression.

Simple and Cost-Effective Quantum Dot Chemodosimeter for Visual Detection of Biothiols in Human Blood Serum

An emission "turn-off" chemodosimeter for the naked-eye detection of biothiols using silica-overcoated cadmium selenide quantum dots is developed. Hole scavenging by the thiol group of cysteine, homocysteine, or glutathione on interaction with quantum dots resulted in an instant and permanent emission quenching under physiologically relevant conditions. Also, the emission suppression is so specific that thiols and substituted thiols (methionine and cystine) can easily be distinguished. A pilot experiment for the visual detection of serum thiols in human blood was also conducted. Densitometry analysis proved the potential of this system as a new methodology in clinical chemistry and research laboratories for routine blood and urine analyses using a simple procedure. This method enables one to visually distinguish biothiols and oxidized biothiols, whose ratio plays a crucial role in maintaining "redox thiol status" in the blood.

New Rhodamine-based sensor for high-sensitivity fluorescence tracking of Cys and simultaneously colorimetric detection of H2S

Sulfhydryl-containing compounds including cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H2S) are involved in many physiological processes. The development of single-molecule optical sensor for the distinguish detection of these bio-thiols is a critical and challenging effort. In this work, we designed a one-step synthesis of the Rhodamine-based sensor FR for specific fluorescent response of Cys and simultaneously colorimetric detection of H2S, in which the aldehyde and fluorine groups act as response sites. Sensor FR displays significant fluorescence enhancement at 565 nm toward Cys with high selectivity and low detection limits (49 nM) due to the low background fluorescent signal of the spirocyclic closed-state in Rhodamine structure. Meantime, after treatment of H2S, the color of the sensor changes significantly from colorless to blue-purple, which can be used as a visual colorimetric method to detect H2S. These response mechanisms were systematically characterized by 1H NMR and Mass spectrometry. Finally, sensor FR could be used to monitor exogenous and endogenous of intracellular Cys changes.