KINETIC PROPERTIES AND EMG ACTIVITY OF NORMAL AND OVER-SPEED PEDALING IN TRACK SPRINT CYCLISTS: A CASE STUDY

Track sprint cycling requires unique skills. We investigate the pedaling kinetics and muscle coordination of a male track sprinter (170cm, 65kg, peak power 1513W) to see if they differ from that of a non-sprinter, and if the subject’s own technique vary from normal riding to an under-load maximal cadence sprint. Two trials were collected using 3D motion capture technology. EMG signals of 8 leg muscles were recorded. Joint torque and power of each trial were calculated using a subject specific musculoskeletal model, with realistic pedal forces as input to our dynamic simulation. Flexion torque appears at the knee during its extension, different from the non-sprinters. Joint torque and power appears similar for both trials, but 6 of the 8 muscles showed differences in EMG patterns. These findings could potentially benefit the evolvement of training methods

Role of pirenoxine in the effects of catalin on in vitro ultraviolet-induced lens protein turbidity and selenite-induced cataractogenesis in vivo

Purpose: In this study, we investigated the biochemical pharmacology of pirenoxine (PRX) and catalin under in vitro selenite/calcium- and ultraviolet (UV)-induced lens protein turbidity challenges. The systemic effects of catalin were determined using a selenite-induced cataractogenesis rat model. Methods: In vitro cataractogenesis assay systems (including UVB/C photo-oxidation of lens crystallins, calpain-induced proteolysis, and selenite/calcium-induced turbidity of lens crystallin solutions) were used to screen the activity of PRX and catalin eye drop solutions. Turbidity was identified as the optical density measured using spectroscopy at 405 nm. We also determined the in vivo effects of catalin on cataract severity in a selenite-induced cataract rat model. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE) was applied to analyze the integrity of crystallin samples. Results: PRX at 1,000 μM significantly delayed UVC-induced turbidity formation compared to controls after 4 h of UVC exposure (p<0.05), but not in groups incubated with PRX concentrations of <1,000 μM. Results were further confirmed by SDS–PAGE. The absolute γ-crystallin turbidity induced by 4 h of UVC exposure was ameliorated in the presence of catalin equivalent to 1~100 μM PRX in a concentration-dependent manner. Samples with catalin-formulated vehicle only (CataV) and those containing PRX equivalent to 100 μM had a similar protective effect after 4 h of UVC exposure compared to the controls (p<0.05). PRX at 0.03, 0.1, and 0.3 μM significantly delayed 10 mM selenite- and calcium-induced turbidity formation compared to controls on days 0~4 (p<0.05). Catalin (equivalent to 32, 80, and 100 μM PRX) had an initial protective effect against selenite-induced lens protein turbidity on day 1 (p<0.05). Subcutaneous pretreatment with catalin (5 mg/kg) also statistically decreased the mean cataract scores in selenite-induced cataract rats on post-induction day 3 compared to the controls (1.3±0.2 versus 2.4±0.4; p<0.05). However, catalin (equivalent to up to 100 μM PRX) did not inhibit calpain-induced proteolysis activated by calcium, and neither did 100 μM PRX. Conclusions: PRX at micromolar levels ameliorated selenite- and calcium-induced lens protein turbidity but required millimolar levels to protect against UVC irradiation. The observed inhibition of UVC-induced turbidity of lens crystallins by catalin at micromolar concentrations may have been a result of the catalin-formulated vehicle. Transient protection by catalin against selenite-induced turbidity of crystallin solutions in vitro was supported by the ameliorated cataract scores in the early stage of cataractogenesis in vivo by subcutaneously administered catalin. PRX could not inhibit calpain-induced proteolysis activated by calcium or catalin itself, and may be detrimental to crystallins under UVB exposure. Further studies on formulation modifications of catalin and recommended doses of PRX to optimize clinical efficacy by cataract type are warranted

Inner sense of rhythm: percussionist brain activity during rhythmic encoding and synchronization

IntroductionThe main objective of this research is to explore the core cognitive mechanisms utilized by exceptionally skilled percussionists as they navigate complex rhythms. Our specific focus is on understanding the dynamic interactions among brain regions, respectively, related to externally directed cognition (EDC), internally directed cognition (IDC), and rhythm processing, defined as the neural correlates of rhythm processing (NCRP).MethodsThe research involved 26 participants each in the percussionist group (PG) and control group (CG), who underwent task-functional magnetic resonance imaging (fMRI) sessions focusing on rhythm encoding and synchronization. Comparative analyses were performed between the two groups under each of these conditions.ResultsRhythmic encoding showed decreased activity in EDC areas, specifically in the right calcarine cortex, left middle occipital gyrus, right fusiform gyrus, and left inferior parietal lobule, along with reduced NCRP activity in the left dorsal premotor, right sensorimotor cortex, and left superior parietal lobule. During rhythmic synchronization, there was increased activity in IDC areas, particularly in the default mode network, and in NCRP areas including the left inferior frontal gyrus and bilateral putamen. Conversely, EDC areas like the right dorsolateral prefrontal gyrus, right superior temporal gyrus, right middle occipital gyrus, and bilateral inferior parietal lobule showed decreased activity, as did NCRP areas including the bilateral dorsal premotor cortex, bilateral ventral insula, bilateral inferior frontal gyrus, and left superior parietal lobule.DiscussionPG’s rhythm encoding is characterized by reduced cognitive effort compared to CG, as evidenced by decreased activity in brain regions associated with EDC and the NCRP. Rhythmic synchronization reveals up-regulated IDC, down-regulated EDC involvement, and dynamic interplay among regions with the NCRP, suggesting that PG engages in both automatic and spontaneous processing simultaneously. These findings provide valuable insights into expert performance and present opportunities for improving music education

Epstein-Barr Virus BGLF4 Kinase Retards Cellular S-Phase Progression and Induces Chromosomal Abnormality

Epstein-Barr virus (EBV) induces an uncoordinated S-phase-like cellular environment coupled with multiple prophase-like events in cells replicating the virus. The EBV encoded Ser/Thr kinase BGLF4 has been shown to induce premature chromosome condensation through activation of condensin and topoisomerase II and reorganization of the nuclear lamina to facilitate the nuclear egress of nucleocapsids in a pathway mimicking Cdk1. However, the observation that RB is hyperphosphorylated in the presence of BGLF4 raised the possibility that BGLF4 may have a Cdk2-like activity to promote S-phase progression. Here, we investigated the regulatory effects of BGLF4 on cell cycle progression and found that S-phase progression and DNA synthesis were interrupted by BGLF4 in mammalian cells. Expression of BGLF4 did not compensate Cdk1 defects for DNA replication in S. cerevisiae. Using time-lapse microscopy, we found the fate of individual HeLa cells was determined by the expression level of BGLF4. In addition to slight cell growth retardation, BGLF4 elicits abnormal chromosomal structure and micronucleus formation in 293 and NCP-TW01 cells. In Saos-2 cells, BGLF4 induced the hyperphosphorylation of co-transfected RB, while E2F1 was not released from RB-E2F1 complexes. The E2F1 regulated activities of the cyclin D1 and ZBRK1 promoters were suppressed by BGLF4 in a dose dependent manner. Detection with phosphoamino acid specific antibodies revealed that, in addition to Ser780, phosphorylation of the DNA damage-responsive Ser612 on RB was enhanced by BGLF4. Taken together, our study indicates that BGLF4 may directly or indirectly induce a DNA damage signal that eventually interferes with host DNA synthesis and delays S-phase progression

Capsaicin in the Periaqueductal Gray Induces Analgesia Via Metabotropic Glutamate Receptor-Mediated Endocannabinoid Retrograde Disinhibition

BACKGROUND AND PURPOSE Capsaicin, an agonist of transient receptor potential vanilloid 1 TRPV1 channels, is pro- nociceptive in the periphery but is anti-nociceptive when administered into the ventrolateral periaqueductal gray vlPAG, a midbrain region for initiating descending pain inhibition. Here, we investigated how activation of TRPV1 channels in the vlPAG leads to anti-nociception. EXPERIMENTAL APPROACH We examined synaptic transmission and neuronal activity using whole-cell recordings in vlPAG slices in vitro and hot-plate nociceptive responses in rats after drug microinjection into the vlPAG in vivo. KEY RESULTS Capsaicin 1-10 mu M depressed evoked GABAergic inhibitory postsynaptic currents eIPSCs in vlPAG slices presynaptically, while increasing miniature excitatory PSC frequency. Capsaicin-induced eIPSC depression was antagonized by cannabinoid CB1 and metabotropic glutamate mGlu5 receptor antagonists, and prevented by inhibiting diacylglycerol lipase DAGL, which converts DAG into 2- arachidonoylglycerol 2-AG, an endocannabinoid. Capsaicin induced membrane depolarization in 2/3 neurons recorded but, overall, increased neuronal firings by increasing evoked postsynaptic potentials. Intra-vlPAG capsaicin reduced hot- plate responses in rats, effects blocked by CB1 and mGlu receptor antagonists. Effects of capsaicin were antagonized by SB 366791, a TRPV1 channel antagonist. CONCLUSIONS AND IMPLICATIONS Capsaicin activated TRPV1s on glutamatergic terminals to release glutamate which activated postsynaptic mGlu5 receptors, yielding 2-AG from DAG by DAGL hydrolysis. 2-AG induces retrograde inhibition disinhibition of GABA release via presynaptic CB1 receptors. This disinhibition in the vlPAG leads to anti-nociception by activating the descending pain inhibitory pathway. This is a novel TRPV1 channel-mediated anti-nociceptive mechanism in the brain and a new interaction between vanilloid and endocannabinoid systems

Cellular Mechanisms of Capsaicin-Induced Analgesia in Periaqueductal Gray -role of mGluR, endocannabinoids and GABA system

Transient receptor potential vanilloid type 1 (TRPV1) channel 在周邊和中樞神經系統的疼痛調節上皆扮演重要的角色。在動物疼痛模式的實驗中觀測到，將Capsaicin 打入大鼠中腦環導水管灰質背側區 (vlPAG)會產生止痛效果。本實驗利用細胞膜箝制記錄的電生理方法觀測Capsaicin對於環導水管灰質背側區的神經突觸可塑性的影響，以解釋Capsaicin在中樞產生止痛的機轉。本實驗結果發現，在中腦環導水管灰質背側區的腦薄片給予Capsaicin 1~10μM會抑制此區的evoked GABAergic inhibitory postsynaptic currents (IPSCs)。此抑制現象可以被SB 366791 (TRPV1的拮抗劑)防止 (前處理)或反轉 (後處理)，可推知此抑制現像是經由活化TRPV1 channels而來。當我們在70ms的間隔下，快速給予成對的兩個刺激，Capsaicin可以增加雙刺激的促進效果 (Paired-pulse facilitation)，這個現象暗示了其作用效果主要位於突觸前。由於在2002年有報導指出Capsaicin在環導水管灰質背側區引起的止痛反應可以被group Ⅰ metabotropic glutamate receptors (mGluRs) 所抑制。因此我們接著探討mGluRs在這裡和Capsaicin的交互作用。Capsaicin對於IPSCs的抑制現象可以被mGluR5 的拮抗劑 MPEP (2-methyl-6- (phenylethynyl) pyridine hydrochloride)反轉，而mGluR1拮抗劑CPCCOEt (7-(hydroxyimino) cyclopropa[b]chromen -1a-carboxylate ethyl ester)無法產生反轉。由此可知mGluR5是Capsaicin下游產生作用的主要調控者。在miniature EPSCs的實驗中，Capsaicin增加其頻率，但不影響其大小。此結果進一步說明了上述mGluR5的活化應是由Capsaicin釋放的glutamate引發的。在許多腦區，活化group I mGluRs 皆會抑制GABAergic transmission。這個現象目前已被廣泛接受是由Gqprotein-phospholipase C (PLC)-diacylglyceral (DAG)-DAG lipase的訊息傳遞路徑產生endocannabinoids。 Endocannabinoids接著逆行活化突觸前的Cannabinoid receptors subtype 1 (CB1)，而造成IPSCs的抑制現象。我們觀察到Capsaicin所抑制的IPSCs在AM251 (CB1拮抗劑)的作用下可以被反轉。上述的實驗結果顯示Capsaicin在中腦環導水管灰質背側區活化位於glutamatergic terminals的TRPV1 channels，促進glutamate釋放，進而活化mGluR5和其下游的Gqprotein- PLC- DAG-DAG lipase 傳導路徑，促進endocannabinoids的生成 ;再透過endocannabinoids逆行活化突觸前的CB1 cannabinoid receptors來抑制此區的GABAergic transmission。在evoked postsynaptic potentials (PSPs)的實驗中，Capsaicin在類似生理情況的條件下促進了中腦環導水管灰質背側區神經細胞的整體興奮性，亦即活化了這個下行性的疼痛抑制路徑 (descending pain inhibitory pathway)。本實驗結果提出一個嶄新的細胞內機轉來解釋Capsaicin在中樞神經系統所產生的止痛作用。The transient receptor potential vanilloid type 1 (TRPV1) channel plays a role in pain modulation not only at the periphery, but also in the brain. It is a nonselective cation channel and can be activated by an irritant plant product, capsaicin, as well as the endovanilloid, anadamide (AEA). It was reported that capsaicin elicit antinociceptive response in vivo by activating the TRPV1 channels in the ventrolateral periaqueductal gray (vlPAG), a key midbrain region for initiating the descending pain inhibitory pathway. We, therefore, investigated how capsaicin, through activating TRPV1 channels, affects synaptic transmission in the vlPAG to produce its antinociception using visualized whole-cell patch clamp recording technique in brain slices containing the vlPAG. Capsaicin (1-10 μM) concentration-dependently depressed evoked GABAergic inhibitory postsynaptic currents (IPSCs) in vlPAG slices. This effect was competitively reversed and prevented by SB 366791, a selective TRPV1 antagonist. Capsaicin-induced depression of IPSCs was accompanied with an increase of the paired-pulse facilitation ratio, suggesting a presynaptic site of action. Capsaicin has been reported to facilitate neurotransmitter release via activating presynaptic TRPV1 channels and its central antinociceptive effect was blocked by the antagonists of group I metabotropic glutamate receptor (mGluR). We, therefore, examined if mGluRs were involved in the effect of capsaicin (3μM). Indeed, capsaicin-induced IPSC depression was reversed by 2-methyl-6- (phenylethynyl) pyridine hydrochloride (MPEP, 10 μM), a selective mGluR5 antagonist, but not by 7-(hydroxyimino) cyclopropa[b]chromen-1a- carboxylate ethyl ester (CPCCOEt, 10μM) a mGluR1 antagonist,. This suggests capsaicin has to facilitate glutamate release in order to activate mGluRs. This suggestion was supported by the finding that capsaicin dramatically increased the frequency, but not amplitude, of miniature excitatory postsynaptic currents (mEPSCs). t has been demonstrated that activation of group I mGluRs, through the Gq-protein-phospholipase C (PLC)-diacylglyceral (DAG)-DAG lipase pathway, leads to synthesis of endocannabinoids which retrogradely inhibited GABAergic transmission in many brain regions, including the vlPAG. We, therefore, examine if endocannabinoids were involved in the action of capsaicin. We did find capsaicin-induced IPSC depression was reversed by AM251, a CB1 cannabinoid receptor antagonist. Furthermore, capsaicin produced an overall excitatory effect on the neuronal activity of vlPAG neurons when evoked postsynaptic potentials were recorded in the current clamp mode. This suggests that capsaicin can increase vlPAG neuronal excitability in physiological condition through this mechanism.t is concluded that capsaicin activates the TRPV1 channels at glutamatergic terminals to facilitate the release of glutamate which subsequently activates postsynaptic mGluR5. Activation of mGluR5 leads to synthesis of endocannabinoids, which retrogradely activates the CB1 receptors at nearby GABAergic terminals to inhibit GABAergic transmission in the vlPAG. The eventual effect gives rise to activation of descending pain inhibitory pathway, producing antinociception. This study reveals a novel cellular mechanism for the central antinociceptive action of capsaicin. To the best of our knowledge, this is the first study disclose the interplay between vanilloids and endocannabinoids, two pain-regulating players, in a pain-regulating brain locus.口試委員會審定書…………………………………………………… i謝…………………………………………………………………… ii文摘要 (Abstract in Chinese) ……………………………… iv文摘要 (Abstract in English) ………………………………vi.Introduction……………………………………………………1.Materials and Methods……………………………………… 10.Results………………………………………………………13.Discussion……………………………………………………18.Tables…………………………………………………………25.Figures………………………………………………………29.Reference……………………………………………………4

The Arabidopsis thiamin-deficient mutant pale green1 lacks thiamin monophosphate phosphatase of the vitamin B1 biosynthesis pathway

Thiamin diphosphate (TPP, vitamin B-1) is an essential coenzyme present in all organisms. Animals obtain TPP from their diets, but plants synthesize TPPde novo. We isolated and characterized an Arabidopsis pale green1 (pale1) mutant that contained higher concentrations of thiamin monophosphate (TMP) and less thiamin and TPP than the wild type. Supplementation with thiamin, but not the thiazole and pyrimidine precursors, rescued the mutant phenotype, indicating that the pale1 mutant is a thiamin-deficient mutant. Map-based cloning and whole-genome sequencing revealed that the pale1 mutant has a mutation in At5g32470 encoding a TMP phosphatase of the TPP biosynthesis pathway. We further confirmed that the mutation of At5g32470 is responsible for the mutant phenotypes by complementing the pale1 mutant with constructs overexpressing full-length At5g32470. Most plant TPP biosynthetic enzymes are located in the chloroplasts and cytosol, but At5g32470-GFP localized to the mitochondrion of the root, hypocotyl, mesophyll and guard cells of the 35S:At5g32470-GFP complemented plants. The subcellular localization of a functional TMP phosphatase suggests that the complete vitamin B1 biosynthesis pathway may involve the chloroplasts, mitochondria and cytosol in plants. Analysis of PALE1 promoter-uidA activity revealed that PALE1 is mainly expressed in vascular tissues of Arabidopsis seedlings. Quantitative RT-PCR analysis of TPP biosynthesis genes and genes encoding the TPP-dependent enzymes pyruvate dehydrogenase, -ketoglutarate dehydrogenase and transketolase revealed that the transcript levels of these genes were upregulated in the pale1 mutant. These results suggest that endogenous levels of TPP may affect the expression of genes involved in TPP biosynthesis and TPP-dependent enzymes

Effects of pH on electrocatalytic activity of functionalized carbon nanotubes

[[abstract]]In this study, we modified carbon nanotubes (CNTs) by grafting with poly(ethylene glycol) (PEG) using the “grafting to” method. The PEG-grafted CNT (CNT-g-PEG) was cast on indium tin oxide (ITO) electrode to investigate the electrocatalytic activity of CNT to the redox reactions of the Fe(CN)6 3−/4−as a probe using cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of CNT was correlated with CNT dispersion in the cast film on ITO as a function of pH of aqueous solution from which the film was cast. The CNT dispersions in aqueous solutions of different pH and in the cast films were examined by visual observation and zeta potential, scanning electron microscopy and transmission electron microscopy, respectively. At a pH in the range of 3–11 at which ITO electrode was modified, two functionalized CNT (fCNT and CNT-g-PEG) were both found to electrocatalyze the redox reactions of the Fe(CN)6 3−/4−probe and the PEG grafts in CNT-g-PEG could help CNT adhere to the electrode to obtain durable modified electrode. The more uniform CNT dispersions in aqueous solutions and in the cast films appeared to have greater electrocatalytic acitivity