Microbial Genetic Composition Tunes Host Longevity.

Homeostasis of the gut microbiota critically influences host health and aging. Developing genetically engineered probiotics holds great promise as a new therapeutic paradigm to promote healthy aging. Here, through screening 3,983 Escherichia coli mutants, we discovered that 29 bacterial genes, when deleted, increase longevity in the host Caenorhabditis elegans. A dozen of these bacterial mutants also protect the host from age-related progression of tumor growth and amyloid-beta accumulation. Mechanistically, we discovered that five bacterial mutants promote longevity through increased secretion of the polysaccharide colanic acid (CA), which regulates mitochondrial dynamics and unfolded protein response (UPRmt) in the host. Purified CA polymers are sufficient to promote longevity via ATFS-1, the host UPRmt-responsive transcription factor. Furthermore, the mitochondrial changes and longevity effects induced by CA are conserved across different species. Together, our results identified molecular targets for developing pro-longevity microbes and a bacterial metabolite acting on host mitochondria to promote longevity.

Neuronal regulation of longevity by staying cool.

Aging is fundamental to life and reflects functional declines in different tissues at the organismal level. As a systematic process, aging can be influenced by the interplay between genetic and environmental factors, and the nervous system plays a crucial role in this regulation. Environmental inputs can be sensed by the nervous system, which consequently triggers signaling outputs toward peripheral tissues to regulate gene expression systematically. Thus, understanding the underlying molecular mechanisms behind environmentally triggered neuron-periphery cross-talk is crucial for the promotion of an organism's health and longevity.

Low signaling efficiency from receptor to effector in olfactory transduction: A quantified ligand-triggered GPCR pathway.

G protein-coupled receptor (GPCR) signaling is ubiquitous. As an archetype of this signaling motif, rod phototransduction has provided many fundamental, quantitative details, including a dogma that one active GPCR molecule activates a substantial number of downstream G protein/enzyme effector complexes. However, rod phototransduction is light-activated, whereas GPCR pathways are predominantly ligand-activated. Here, we report a detailed study of the ligand-triggered GPCR pathway in mammalian olfactory transduction, finding that an odorant-receptor molecule when (one-time) complexed with its most effective odorants produces on average much less than one downstream effector. Further experiments gave a nominal success probability of tentatively ∼10-4 (more conservatively, ∼10-2 to ∼10-5). This picture is potentially more generally representative of GPCR signaling than is rod phototransduction, constituting a paradigm shift.

Defective cerebellar ryanodine receptor type 1 and endoplasmic reticulum calcium 'leak' in tremor pathophysiology.

Essential Tremor (ET) is a prevalent neurological disease characterized by an 8-10 Hz action tremor. Molecular mechanisms of ET remain poorly understood. Clinical data suggest the importance of the cerebellum in disease pathophysiology, and pathological studies indicate Purkinje Cells (PCs) incur damage. Our recent cerebellar cortex and PC-specific transcriptome studies identified alterations in calcium (Ca2+) signaling pathways that included ryanodine receptor type 1 (RyR1) in ET. RyR1 is an intracellular Ca2+ release channel located on the Endoplasmic Reticulum (ER), and in cerebellum is predominantly expressed in PCs. Under stress conditions, RyR1 undergoes several post-translational modifications (protein kinase A [PKA] phosphorylation, oxidation, nitrosylation), coupled with depletion of the channel-stabilizing binding partner calstabin1, which collectively characterize a "leaky channel" biochemical signature. In this study, we found markedly increased PKA phosphorylation at the RyR1-S2844 site, increased RyR1 oxidation and nitrosylation, and calstabin1 depletion from the RyR1 complex in postmortem ET cerebellum. Decreased calstabin1-RyR1-binding affinity correlated with loss of PCs and climbing fiber-PC synapses in ET. This 'leaky' RyR1 signature was not seen in control or Parkinson's disease cerebellum. Microsomes from postmortem cerebellum demonstrated excessive ER Ca2+ leak in ET vs. controls, attenuated by channel stabilization. We further studied the role of RyR1 in tremor using a mouse model harboring a RyR1 point mutation that mimics constitutive site-specific PKA phosphorylation (RyR1-S2844D). RyR1-S2844D homozygous mice develop a 10 Hz action tremor and robust abnormal oscillatory activity in cerebellar physiological recordings. Intra-cerebellar microinfusion of RyR1 agonist or antagonist, respectively, increased or decreased tremor amplitude in RyR1-S2844D mice, supporting a direct role of cerebellar RyR1 leakiness for tremor generation. Treating RyR1-S2844D mice with a novel RyR1 channel-stabilizing compound, Rycal, effectively dampened cerebellar oscillatory activity, suppressed tremor, and normalized cerebellar RyR1-calstabin1 binding. These data collectively support that stress-associated ER Ca2+ leak via RyR1 may contribute to tremor pathophysiology.

Physiological Recordings of the Cerebellum in Movement Disorders.

The cerebellum plays an important role in movement disorders, specifically in symptoms of ataxia, tremor, and dystonia. Understanding the physiological signals of the cerebellum contributes to insights into the pathophysiology of these movement disorders and holds promise in advancing therapeutic development. Non-invasive techniques such as electroencephalogram and magnetoencephalogram can record neural signals with high temporal resolution at the millisecond level, which is uniquely suitable to interrogate cerebellar physiology. These techniques have recently been implemented to study cerebellar physiology in healthy subjects as well as individuals with movement disorders. In the present review, we focus on the current understanding of cerebellar physiology using these techniques to study movement disorders.

An Exergame-Integrated IoT-Based Ergometer System Delivers Personalized Training Programs for Older Adults and Enhances Physical Fitness: A Pilot Randomized Controlled Trial.

INTRODUCTION: Regular physical exercise is believed to counteract the adverse physiological consequences of aging. However, smart fitness equipment specifically designed for older adults is quite rare. Here we designed an exergame-integrated internet of things (IoT)-based ergometer system (EIoT-ergo) that delivers personalized exercise prescriptions for older adults. First, physical fitness was evaluated using the Senior Fitness Test (SFT) application. Then, radio frequency identification (RFID) triggered the EIoT-ergo to deliver the corresponding exercise session based on the individual level of physical fitness. The exercise intensity during each workout was measured to generate the next exercise session. Further, EIoT-ergo provides an exergame to help users control and maintain their optimal cadence while engaging in exercise. METHODS: This was a randomized controlled trial with 1:1 randomization. Participants were older adults, 50+ years of age (N = 35), who are active in their community. Participants in the EIoT-ergo group received a 12-week personalized exercise program delivered by EIoT-ergo for 30 min per session, with 2 sessions per week. Participants in the control group continued with their usual activities. A senior's fitness test and a health questionnaire were assessed at baseline and at a 13-week reassessment. The Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) was used to evaluate the satisfaction of EIoT-ergo. RESULTS: Compared with the control group, the EIoT-ergo group showed significant improvements in muscle strength (time-by-group interaction, sit-to-stand: ß = 5.013, p < 0.001), flexibility (back stretch: ß = 4.008, p = 0.005; and sit-and-reach: ß = 4.730, p = 0.04), and aerobic endurance (2-min step: ß = 9.262, p = 0.03). The body composition was also improved in the EIoT-ergo group (body mass index: ß = -0.737, p < 0.001; and skeletal muscle index: ß = 0.268, p = 0.03). Satisfaction with EIoT-ergo was shown in QUEST, with an average score of 4.4 ± 0.32 (5 for very satisfied). The percentage maximum heart rate in each session also indicated that EIoT-ergo can gradually build up the exercise intensity of users. CONCLUSIONS: EIoT-ergo was developed to provide personal identification, exergames, intelligent exercise prescriptions, and remote monitoring, as well as to significantly enhance the physical fitness of the elderly individuals under study.

Cerebellar Oscillations in Familial and Sporadic Essential Tremor.

Enhanced cerebellar oscillations have recently been identified in essential tremor (ET) patients as a key pathophysiological change. Since ET is considered a heterogeneous group of diseases, we investigated whether cerebellar oscillations differ in ET subtypes (familial vs. sporadic). This study aims to determine cerebellar physiology in familial and sporadic ET. Using surface electroencephalogram, we studied cerebellar physiology in 40 ET cases (n = 22 familial and n = 18 sporadic) and 20 age-matched controls. Both familial and sporadic ET cases had an increase in the intensity of cerebellar oscillations when compared to controls. Interestingly, cerebellar oscillations correlated with tremor severity in familial ET but not in sporadic ET. Our study demonstrated that ET cases have enhanced cerebellar oscillations, and the different relationships between cerebellar oscillations and tremor severity in familial and sporadic ET suggest diverse cerebellar pathophysiology.

Beyond Sarcopenia: older adults with type II diabetes mellitus tend to experience an elevated risk of poor dynamic balance-a case-control study.

BACKGROUND: People with type 2 diabetes mellitus (T2DM) tend to be vulnerable to geriatric syndromes such as sarcopenia and frailty. Reduced physical activity also accompanies sarcopenia and frailty, which is generally typical of patients with T2DM. However, a comprehensive assessment of physical fitness in patients with T2DM has seldom been carried out and verified. This study is thus an attempt to determine the associations among sarcopenia, frailty, and the SFT in diabetic patients and non-diabetic controls to provide a more comprehensive understanding of such associations in future evaluations of T2DM in older individuals. METHODS: Sarcopenia, frailty, and the senior fitness test (SFT) were compared between 78 older men with T2DM (66.5 ± 9.0 years) and 48 age-matched normoglycemic controls (65.8 ± 5.3 years) in this case-control study. The skeletal muscle index (SMI), grip strength, and 4-m walk test were employed to assess for sarcopenia. Frailty was evaluated using the Study of Osteoporotic Fractures index (SOF). The SFT comprises five components, including body composition, muscle strength, flexibility, balance, and aerobic endurance. RESULTS: The risk level of sarcopenia was significantly higher (p < 0.05) in the T2DM group as compared to the control group. No significant difference between-group differences were found in SMI and grip strength in the T2DM and control groups. However, the T2DM group showed a significant decrease in gait speed (p < 0.01) in comparison with the control group, as well as significant increases in frailty (p < 0.01) and depression (p < 0.05). With respect to the SFT, obvious elevation in BMI, significant declines in extremity muscle strength (elbow extensor, knee flexor, hip abductor, hip flexor, sit to stand), static/dynamic balance (single leg stand: p < 0.05; up-and-go: p < 0.01) and aerobic endurance (2-min step: p < 0.01; 6-min walk: p < 0.01) were found in the T2DM group. Furthermore, the SOF (OR = 2.638, 95% CI = 1.333-5.221), BMI (OR = 1.193, 95% CI = 1.041-1.368) and up-and-go (OR = 2.089, 95% CI = 1.400-3.117) were found to be positively and significantly associated with T2DM. CONCLUSIONS: The findings of this study indicated the importance of countering frailty and maintaining physical fitness, especially dynamic balance, during the early physical deterioration taking place in diabetic patients.

Methyl-Sensing Nuclear Receptor Liver Receptor Homolog-1 Regulates Mitochondrial Function in Mouse Hepatocytes.

BACKGROUND AND AIMS: Liver receptor homolog-1 (LRH-1; NR5A2) is a nuclear receptor that regulates metabolic homeostasis in the liver. Previous studies identified phosphatidylcholines as potential endogenous agonist ligands for LRH-1. In the liver, distinct subsets of phosphatidylcholine species are generated by two different pathways: choline addition to phosphatidic acid through the Kennedy pathway and trimethylation of phosphatidylethanolamine through phosphatidylethanolamine N-methyl transferase (PEMT). APPROACH AND RESULTS: Here, we report that a PEMT-LRH-1 pathway specifically couples methyl metabolism and mitochondrial activities in hepatocytes. We show that the loss of Lrh-1 reduces mitochondrial number, basal respiration, beta-oxidation, and adenosine triphosphate production in hepatocytes and decreases expression of mitochondrial biogenesis and beta-oxidation genes. In contrast, activation of LRH-1 by its phosphatidylcholine agonists exerts opposite effects. While disruption of the Kennedy pathway does not affect the LRH-1-mediated regulation of mitochondrial activities, genetic or pharmaceutical inhibition of the PEMT pathway recapitulates the effects of Lrh-1 knockdown on mitochondria. Furthermore, we show that S-adenosyl methionine, a cofactor required for PEMT, is sufficient to induce Lrh-1 transactivation and consequently mitochondrial biogenesis. CONCLUSIONS: A PEMT-LRH-1 axis regulates mitochondrial biogenesis and beta-oxidation in hepatocytes.

The Efficacy and Safety of Transcranial Direct Current Stimulation for Cerebellar Ataxia: a Systematic Review and Meta-Analysis.

A promising new approach, transcranial direct current stimulation (tDCS) has recently been used as a therapeutic modality for cerebellar ataxia. However, the strength of the conclusions drawn from individual studies in the current literature may be constrained by the small sample size of each trial. Following a systematic literature retrieval of studies, meta-analyses were conducted by pooling the standardized mean differences (SMDs) using random-effects models to assess the efficacy of tDCS on cerebellar ataxia, measured by standard clinical rating scales. Domain-specific effects of tDCS on gait and hand function were further evaluated based on 8-m walk and 9-hole peg test performance times, respectively. To determine the safety of tDCS, the incidences of adverse effects were analyzed using risk differences. Out of 293 citations, 5 randomized controlled trials involving a total of 72 participants with cerebellar ataxia were included. Meta-analysis indicated a 26.1% (p = 0.003) improvement in ataxia immediately after tDCS with sustained efficacy over months (28.2% improvement after 3 months, p = 0.04) when compared with sham stimulation. tDCS seems to be domain-specific as the current analysis suggested a positive effect on gait (16.3% improvement, p = 0.04) and failed to reveal differences for hand function (p = 0.10) with respect to sham. The incidence of adverse events in tDCS and sham groups was similar. tDCS is an effective intervention for mitigating ataxia symptoms with lasting results that can be sustained for months. This treatment shows preferential effects on gait ataxia and is relatively safe.

Ca2+-activated Cl current predominates in threshold response of mouse olfactory receptor neurons.

In mammalian olfactory transduction, odorants activate a cAMP-mediated signaling pathway that leads to the opening of cyclic nucleotide-gated (CNG), nonselective cation channels and depolarization. The Ca2+ influx through open CNG channels triggers an inward current through Ca2+-activated Cl channels (ANO2), which is expected to produce signal amplification. However, a study on an Ano2-/- mouse line reported no elevation in the behavioral threshold of odorant detection compared with wild type (WT). Subsequent studies by others on the same Ano2-/- line, nonetheless, found subtle defects in olfactory behavior and some abnormal axonal projections from the olfactory receptor neurons (ORNs) to the olfactory bulb. As such, the question regarding signal amplification by the Cl current in WT mouse remains unsettled. Recently, with suction-pipette recording, we have successfully separated in frog ORNs the CNG and Cl currents during olfactory transduction and found the Cl current to predominate in the response down to the threshold of action-potential signaling to the brain. For better comparison with the mouse data by others, we have now carried out similar current-separation experiments on mouse ORNs. We found that the Cl current clearly also predominated in the mouse olfactory response at signaling threshold, accounting for ∼80% of the response. In the absence of the Cl current, we expect the threshold stimulus to increase by approximately sevenfold.

Hispanic Spinocerebellar Ataxia Type 35 (SCA35) with a Novel Frameshift Mutation.

Genetic mutations in transglutaminase 6 (TGM6) are recently identified to be associated with spinocerebellar ataxia type 35 (SCA35). We report a Hispanic SCA35 patient, who was confirmed to have a heterozygous, single-nucleotide deletion in TGM6, causing a frameshift mutation with a premature stop codon. An immune-mediated ataxia previously found to be associated with autoantibody reactivity to TG6 may share a similar pathomechanism to SCA35, suggesting a converging role for TG6 in cerebellar function.

Effects of the Surface Texture and Weight of a Pinch Apparatus on the Reliability and Validity of a Hand Sensorimotor Control Assessment.

OBJECTIVES: To investigate the reliability and validity of a modified pinch apparatus devised with 3 surface textures and 2 different weights for clinical application. DESIGN: Case-controlled study. SETTING: A university hospital. PARTICIPANTS: The participants (N=32) included carpal tunnel syndrome (CTS) patients (n=16) with 20 sensory neuropathy hands, and an equal number of age-sex matched volunteers without CTS, as well as young volunteers without CTS (n=16 with 20 hands) used to analyze both the testing validity and reliability of the modified device. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The Semmes-Weinstein monofilament (SWM) and two-point discrimination (2PD) tests were conducted, and the force ratio between the FPpeak (peak pinch force during lifting phase) and FLmax (maximum load force at maximum upward acceleration onset) detected from a pinch-holding-up activity (PHUA) under various testing conditions was obtained. RESULTS: The range of the intraclass correlation coefficient of this pinch device was 0.369-0.952. The CTS patients exhibited poorer force modulation ability according to the inertial change in a dynamic lifting task when compared to the controls under all testing conditions (P<.001). The area under the receiver operating characteristic force ratio curve was 0.841, revealing high accuracy of the test for diagnosing CTS neuropathic hands under the testing condition in which the 125-g coarse texture device was used. In addition, the weight factor was shown to have significant effects on the sensitivity and accuracy of the PHUA assessment. CONCLUSIONS: This study showed that the PHUA test via the modified pinch apparatus is a sensitive tool that can be used in clinical practice for detecting neuropathic CTS hands. In addition, changing the weight of the pinch device has a significant effect on the sensitivity and accuracy of the PHUA assessment.

Cyclic-nucleotide-gated cation current and Ca2+-activated Cl current elicited by odorant in vertebrate olfactory receptor neurons.

Olfactory transduction in vertebrate olfactory receptor neurons (ORNs) involves primarily a cAMP-signaling cascade that leads to the opening of cyclic-nucleotide-gated (CNG), nonselective cation channels. The consequent Ca2+ influx triggers adaptation but also signal amplification, the latter by opening a Ca2+-activated Cl channel (ANO2) to elicit, unusually, an inward Cl current. Hence the olfactory response has inward CNG and Cl components that are in rapid succession and not easily separable. We report here success in quantitatively separating these two currents with respect to amplitude and time course over a broad range of odorant strengths. Importantly, we found that the Cl current is the predominant component throughout the olfactory dose-response relation, down to the threshold of signaling to the brain. This observation is very surprising given a recent report by others that the olfactory-signal amplification effected by the Ca2+-activated Cl current does not influence the behavioral olfactory threshold in mice.

Live-cell imaging of alkyne-tagged small biomolecules by stimulated Raman scattering.

Sensitive and specific visualization of small biomolecules in living systems is highly challenging. We report stimulated Raman-scattering imaging of alkyne tags as a general strategy for studying a broad spectrum of small biomolecules in live cells and animals. We demonstrate this technique by tracking alkyne-bearing drugs in mouse tissues and visualizing de novo synthesis of DNA, RNA, proteins, phospholipids and triglycerides through metabolic incorporation of alkyne-tagged small precursors.

Proteomic Analysis of Various Rat Ocular Tissues after Ischemia-Reperfusion Injury and Possible Relevance to Acute Glaucoma.

Glaucoma is a group of eye diseases that can cause vision loss and optical nerve damage. To investigate the protein expression alterations in various intraocular tissues (i.e., the cornea, conjunctiva, uvea, retina, and sclera) during ischemia-reperfusion (IR) injury, this study performed a proteomic analysis to qualitatively investigate such alterations resulting from acute glaucoma. The IR injury model combined with the proteomic analysis approach of two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to monitor the protein expression alterations in two groups of specimens (an IR injury group and a control group). The analysis results revealed 221 unique differentially expressed proteins of a total of 1481 proteins in the cornea between the two groups. In addition, 97 of 1206 conjunctival proteins, 90 of 1354 uveal proteins, 61 of 1180 scleral proteins, and 37 of 1204 retinal proteins were differentially expressed. These findings imply that different ocular tissues have different tolerances against IR injury. To sum up, this study utilized the acute glaucoma model combined with 2D-DIGE and MALDI-TOF MS to investigate the IR injury affected protein expression on various ocular tissues, and based on the ratio of protein expression alterations, the alterations in the ocular tissues were in the following order: the cornea, conjunctiva, uvea, sclera, and retina.

Single-pulsed electromagnetic field therapy increases osteogenic differentiation through Wnt signaling pathway and sclerostin downregulation.

Pulsed electromagnetic field (PEMF) therapy has been used for more than three decades to treat bone diseases. The main complaint about using PEMF is that it is time-consuming. Previously, we showed single-pulsed electromagnetic field (SPEMF) applied for 3 min daily increased osteogenic differentiation of mesenchymal stem cells and accelerated bone growth in a long bone defect model. In the current study, we investigated the mechanism of SPEMF to increase osteogenic differentiation in osteoblastic cells. We found that both short-term (SS) and long-term (SL) SPEMF treatment increased mineralization, while alkaline phosphatase (ALP) activity increased during the first 5 days of SPEMF treatment. SS treatment increased gene expression of Wnt1, Wnt3a, Wnt10b, Fzd9, ALP, and Bmp2. Also, SPEMF inhibited sclerostin after 5 days of treatment, and that inhibition was more significant with SL treatment. SL SPEMF increased expression of parathyroid hormone-related protein (PTHrP) but decreased expression of Sost gene, which encodes sclerostin. Together, the early osteogenic effect of SPEMF utilizes the canonical Wnt signaling pathway while the inhibitory effect of long-term SPEMF on sclerostin may be attributable to PTHrP upregulation. This study enhances our understanding of cellular mechanisms to support the previous finding and may provide new insight for clinical applications.

Distinctive CD56dim NK subset profiles and increased NKG2D expression in blood NK cells of Parkinson's disease patients.

Mounting data suggest an important role for the immune system in Parkinson's disease (PD). Previous evidence of increased natural killer (NK) cell populations in PD suggests a potential role of NK cells in the pathogenesis of the disease. Previous studies have analyzed NK cell populations using aggregation by variable expression of CD56 and CD16. It remains unknown what differences may exist between NK cell subpopulations when stratified using more nuanced classification. Here, we profile NK cell subpopulations and elucidate the expressions of activating, NKG2D, inhibitory, NKG2A, and homing, CX3CR1, receptors on NK cell subpopulations in PD and healthy controls (HC). We analyzed cryopreserved PMBC samples using a 10-color flow cytometry panel to evaluate NK cell subpopulations in 31 individuals with sporadic PD and 27 HC participants. Here we identified significant differences in the CD56dim NK subset that changes with disease severity in PD. Furthermore, the expressions of NKG2D in all three NK cell subsets were significantly elevated in PD patients compared to HC. Notably, NKG2A expression in the CD56bright NK subset increased in PD patients with longer disease duration but there were no changes in CX3CR1. In summary, our data suggests that changes in NK cells may be influenced by the clinical severity and duration of PD.