Objective To explore the effect of frequency-modulated temporal interference electrical fields stimulation(TIs)on muscle strength and neuromuscular recruitment ability.Methods Sixteen healthy adult participants completed two testing sessions,with an interval of no less than 48 hours be-tween them.The only difference between them was the intervention of real TIs versus sham stimula-tion.The stimulation targeted the left primary motor cortex.During the test,the 3-second maximal vol-untary contraction(3 s MVC)of the first dorsal interosseous(FDI)muscle and the 20-second one(20 s MVC)in the right hand were recorded.Meanwhile,the surface electromyography(sEMG)sig-nals were recorded during the 20 s MVC and analyzed using sEMG decomposition techniques.Results A significant interaction effect was observed in peak muscle force during the 3 s MVC(P<0.05).Com-pared to baseline,real TIs significantly increased peak force,whereas the sham stimulation resulted in a decrease.Moreover,a significant interaction was also found in the peak EMG amplitude during the 20 s MVC(P<0.05),with peak EMG amplitude increasing after real TIs but decreasing after sham stimulation.Conclusion Frequency-modulated TIs effectively enhances peak muscle strength dur-ing the 3 s MVC and increases motor unit synchronization firing during the 20 s MVC.Therefore,TIs has potential for improving neuromuscular performance.

AIM:This study aimed to establish a model of functional impairment in INS-1 cells(rat insulino-ma cells)induced by prolonged exposure to a low level of interleukin-1β(IL-1β),and to investigate the underlying mech-anisms.METHODS:INS-1 cells were treated with different concentrations of IL-1β for 10 d.The cells were divided into control,0.05 μg/L IL-1β,0.1 μg/L IL-1β,and 0.2 μg/L IL-1β groups(n=3).Flow cytometry was employed to assess cell apoptosis,facilitating the identification of IL-1β concentrations that did not significantly induce apoptosis.Subse-quently,INS-1 cells were divided into control and IL-1β groups(n=3)and treated with 0.1 μg/L IL-1β for 10 days.The intracellular insulin content and glucose-stimulated insulin secretion level were detected by immunofluorescence and en-zyme-linked immunosorbent assay(ELISA).Differential proteins and associated signaling pathways were screened using 4D label-free proteomics technology.Moreover,fluorescent probes were used to detect glucose-stimulated calcium ion in-flux,and Western blot was conducted to verify the expression changes of relevant proteins in the nuclear factor kappa-B(NF-κB)signaling pathway and calcium signaling pathway.RESULTS:Treatment with 0.1 μg/L IL-1β for 10 days ex-hibited minimal impact on the survival of INS-1 cells but significantly reduced the intracellular insulin content and glucose-stimulated insulin secretion(P<0.01).Therefore,0.1 μg/L IL-1β was chosen for in vitro induction of functional impair-ment in INS-1 cells.Proteomic analysis showed no significant differences in the expression of apoptosis-related factors,such as caspase-3,B-cell lymphoma-2(Bcl-2),Bcl-2-associated X protein(Bax),and Bcl-2-associated death promoter(Bad),compared with the control(P>0.05).However,the expression of insulin,v-maf avian musculoaponeurotic fibro-sarcoma oncogene family protein A(Mafa),calcium/calmodulin-dependent protein kinase II(CaMKII),inositol 1,4,5-triphosphate receptor(IP3R),and NF-kappa-B inhibitor alpha(IκBα)was significantly reduced(P<0.01),while the protein expression levels of NF-κB and inducible nitric oxide synthase(iNOS)were significantly increased(P<0.05,P<0.01).Fluorescence probe results showed that,compared to the control,the calcium ion influx induced by glucose stimu-lation in the IL-1β group was significantly reduced(P<0.01).Western blot results demonstrated that the expression lev-els of IP3R,CaMKII,and IκBα in the IL-1β group were significantly reduced(P<0.05,P<0.01),while the expression levels of NF-κB and iNOS were significantly increased(P<0.01).CONCLUSION:A model of functional impairment in rat INS-1 cells induced by prolonged exposure to low levels of IL-1β has been successfully established,and it has been pre-liminarily confirmed that this impairment may be related to the activation of the NF-κB signaling pathway and dysfunction of the calcium signaling pathway.

Objective To explore the effect of frequency-modulated temporal interference electrical fields stimulation(TIs)on muscle strength and neuromuscular recruitment ability.Methods Sixteen healthy adult participants completed two testing sessions,with an interval of no less than 48 hours be-tween them.The only difference between them was the intervention of real TIs versus sham stimula-tion.The stimulation targeted the left primary motor cortex.During the test,the 3-second maximal vol-untary contraction(3 s MVC)of the first dorsal interosseous(FDI)muscle and the 20-second one(20 s MVC)in the right hand were recorded.Meanwhile,the surface electromyography(sEMG)sig-nals were recorded during the 20 s MVC and analyzed using sEMG decomposition techniques.Results A significant interaction effect was observed in peak muscle force during the 3 s MVC(P<0.05).Com-pared to baseline,real TIs significantly increased peak force,whereas the sham stimulation resulted in a decrease.Moreover,a significant interaction was also found in the peak EMG amplitude during the 20 s MVC(P<0.05),with peak EMG amplitude increasing after real TIs but decreasing after sham stimulation.Conclusion Frequency-modulated TIs effectively enhances peak muscle strength dur-ing the 3 s MVC and increases motor unit synchronization firing during the 20 s MVC.Therefore,TIs has potential for improving neuromuscular performance.

AIM:This study aimed to establish a model of functional impairment in INS-1 cells(rat insulino-ma cells)induced by prolonged exposure to a low level of interleukin-1β(IL-1β),and to investigate the underlying mech-anisms.METHODS:INS-1 cells were treated with different concentrations of IL-1β for 10 d.The cells were divided into control,0.05 μg/L IL-1β,0.1 μg/L IL-1β,and 0.2 μg/L IL-1β groups(n=3).Flow cytometry was employed to assess cell apoptosis,facilitating the identification of IL-1β concentrations that did not significantly induce apoptosis.Subse-quently,INS-1 cells were divided into control and IL-1β groups(n=3)and treated with 0.1 μg/L IL-1β for 10 days.The intracellular insulin content and glucose-stimulated insulin secretion level were detected by immunofluorescence and en-zyme-linked immunosorbent assay(ELISA).Differential proteins and associated signaling pathways were screened using 4D label-free proteomics technology.Moreover,fluorescent probes were used to detect glucose-stimulated calcium ion in-flux,and Western blot was conducted to verify the expression changes of relevant proteins in the nuclear factor kappa-B(NF-κB)signaling pathway and calcium signaling pathway.RESULTS:Treatment with 0.1 μg/L IL-1β for 10 days ex-hibited minimal impact on the survival of INS-1 cells but significantly reduced the intracellular insulin content and glucose-stimulated insulin secretion(P<0.01).Therefore,0.1 μg/L IL-1β was chosen for in vitro induction of functional impair-ment in INS-1 cells.Proteomic analysis showed no significant differences in the expression of apoptosis-related factors,such as caspase-3,B-cell lymphoma-2(Bcl-2),Bcl-2-associated X protein(Bax),and Bcl-2-associated death promoter(Bad),compared with the control(P>0.05).However,the expression of insulin,v-maf avian musculoaponeurotic fibro-sarcoma oncogene family protein A(Mafa),calcium/calmodulin-dependent protein kinase II(CaMKII),inositol 1,4,5-triphosphate receptor(IP3R),and NF-kappa-B inhibitor alpha(IκBα)was significantly reduced(P<0.01),while the protein expression levels of NF-κB and inducible nitric oxide synthase(iNOS)were significantly increased(P<0.05,P<0.01).Fluorescence probe results showed that,compared to the control,the calcium ion influx induced by glucose stimu-lation in the IL-1β group was significantly reduced(P<0.01).Western blot results demonstrated that the expression lev-els of IP3R,CaMKII,and IκBα in the IL-1β group were significantly reduced(P<0.05,P<0.01),while the expression levels of NF-κB and iNOS were significantly increased(P<0.01).CONCLUSION:A model of functional impairment in rat INS-1 cells induced by prolonged exposure to low levels of IL-1β has been successfully established,and it has been pre-liminarily confirmed that this impairment may be related to the activation of the NF-κB signaling pathway and dysfunction of the calcium signaling pathway.

ObjectiveTo investigate the effect of multi-target transcranial direct current stimulation (tDCS) and single-target tDCS on the performance of working memory-postural control dual-task in healthy adults, and to compare the regulatory effect of the two stimulation protocols. MethodsFrom November, 2020 to February, 2021, 19 healthy adults in Shanghai University of Sport were recruited and randomly accepted multi-target tDCS, single-target tDCS and sham stimulation with at least one week interval between any two stimulation protocols. The target areas of multi-target tDCS included left dorsal lateral prefrontal cortex (L-DLPFC) and bilateral primary motor cortex (M1), and single-tDCS only applied to L-DLPFC. Before and after stimulation, participants completed walking and standing balance tests under single task and dual-task conditions with the second task being a N-back task. The dual-task postural control performance, dual-task cost (DTC) and working memory performance were observed before and after stimulation. ResultsSignificant differences were observed among three stimulation protocols in the changes of stride variability (F = 3.792, P = 0.029), DTC of stride variability (F = 3.412, P = 0.040) and velocity of center of pressure (Vcop) (F = 3.815, P = 0.029). The stride variability (P = 0.047) and Vcop (P = 0.015) were significantly lower and the decrease in DTC of stride variability tended to be significant (P = 0.073) following multi-target tDCS, as compared to sham stimulation. Single-target tDCS significantly decreased the changes of stride variability (P = 0.011), DTC of stride variability (P = 0.014) and Vcop (P = 0.025), as compared to sham stimulation. Compared with single target tDCS, multi-target tDCS reduced the changes of the dual-task cost of the area of center of pressure (P = 0.035). Moreover, no significant difference was observed among the three stimulation protocols in the changes of each measure in the working memory test (P > 0.05). ConclusionBoth multi-target tDCS and single-target tDCS can improve the performance of working memory-postural control dual-task in healthy adults, and compared with single-target tDCS, multi-target tDCS has some advantages in regulating postural control.

Objective To explore the effect of transcranial direct current stimulation(tDCS)regulating the motor cortex on the performance of endurance exercise with incremental loading.Methods A randomized,double-blind,parallel control design was adopted.Forty healthy adults were randomly divided into real stimulation(lasting 20 min)or sham stimulation groups(30 s slow-rise and 30 s slow-fall stimulation provided within the 1st 1 min only).The multifocal tDCS was used,with seven small electrodes(3.14 cm2 round electrodes)placed in the primary,premotor,and supplementary motor areas to modulate motor cortex excitability.The injection current of a single electrode did not exceed 1.552 mA,and the total currents did not exceed 3.998 mA.Baseline tests on incrementally loading exercises were performed before and after the intervention,with an interval of 48 hours between the two tests.Two-way ANOVA was used to analyze the effects of this tDCS protocol on duration of cycling,power output,and revolution speed.Results All subjects completed the experiment without unexpected adverse effects.The overall accuracy rate of subjective guess was 37.5%.There was no significant difference in duration of cycling or power output between the two groups(P>0.05),and within-group statistics showed an increase in revolution speed after the real stimulation(P=0.012).Conclusions tDCS that targets and modulates the motor cortex can improve the revolution speed during cycling exercise with incremental loading in healthy adults,suggesting that this stimulation protocol may be a potential means of improving exercise efficiency in endurance sports.

Objective To explore the effect of transcranial direct current stimulation(tDCS)regulating the motor cortex on the performance of endurance exercise with incremental loading.Methods A randomized,double-blind,parallel control design was adopted.Forty healthy adults were randomly divided into real stimulation(lasting 20 min)or sham stimulation groups(30 s slow-rise and 30 s slow-fall stimulation provided within the 1st 1 min only).The multifocal tDCS was used,with seven small electrodes(3.14 cm2 round electrodes)placed in the primary,premotor,and supplementary motor areas to modulate motor cortex excitability.The injection current of a single electrode did not exceed 1.552 mA,and the total currents did not exceed 3.998 mA.Baseline tests on incrementally loading exercises were performed before and after the intervention,with an interval of 48 hours between the two tests.Two-way ANOVA was used to analyze the effects of this tDCS protocol on duration of cycling,power output,and revolution speed.Results All subjects completed the experiment without unexpected adverse effects.The overall accuracy rate of subjective guess was 37.5%.There was no significant difference in duration of cycling or power output between the two groups(P>0.05),and within-group statistics showed an increase in revolution speed after the real stimulation(P=0.012).Conclusions tDCS that targets and modulates the motor cortex can improve the revolution speed during cycling exercise with incremental loading in healthy adults,suggesting that this stimulation protocol may be a potential means of improving exercise efficiency in endurance sports.

Objective To extract key parameters from a series of biomechanical parameters of rowing technique, so as to provide useful information for coach training. Methods Based on rowing performance of 16 rowers in national team, the factor analysis was used to extract reducing dimension of biomechanical parameters of rowing technique of 80 oxygen utilisation 2 （UT2） training pieces. Results The biomechanical parameters of rowing techniques were classified as technical characteristic factors (angle of 70% peak force, work portion of per 25% stroke length, drive start time, finish slip, position of peak force and angle of peak force), power factor (rower power, average of boat power, port swivel power and stroke swivel power), stroke length factor (catch angle and finish angle) and oar’s motion factor (recovery time, stroke rate and distance of per stroke). Conclusions Monitoring and analyzing these biomechanical factors would contribute coaches and scientific researchers to accurately judge the technical characteristics and shortcomings of rowers.

OBJECTIVE: To investigate the inhibitory effect of ketogenic diet (KD) on growth of neuroblastoma in mice. METHODS: BALB/c-nu mouse models bearing neuroblastoma xenografts were established by subcutaneous injection of human neuroblastoma cell line (SH-SY5Y). When the tumor volume reached 250 mm3, the mice were randomized into SD group with standard diet and PBS treatment, KD group with ketogenic diet and PBS treatment, and CP+KD group with ketogenic diet and cyclophosphamide (60 mg·kg·day) treatment, =8. The tumor volume, body weight, blood glucose, ketone body (β-Hydroxybutyrate) levels, and hepatic steatosis in the mice were assessed. The expressions of caspase-3 and caspase-8 were detected by Western blotting, and Ki67 expresison was detected using immunohistochemistry (IHC). Transmission electron microscopy (TEM) was employed for the autophagosomes, and the autophagic protein Beclin1, LC3A/B and P62 were detected by IHC and Western blotting. RESULTS: On day 28 post tumor cell injection, the mice in KD and CP+KD groups could prolong the overall survival rates than that in SD group ( < 0.001). On day 22 post the injection, the tumor volume in KD group was smaller than that in SD group ( < 0.05); on 16, 19, and 22 day post the injection, the tumor volume in CP+KD group was smaller than that in SD group ( < 0.01). The mice in SD group showed greater body weight on day 19 and higher blood glucose level on day 13 post the injection than those in the other two groups ( < 0.05). Blood ketone level and hepatic steatosis score were higher and glucose ketone index (GKI) was lower in KD and CP+KD groups than those in SD group (all < 0.05). The expressions of Ki67 and apoptotic proteins were detected in the tumor tissues of all groups. TEM revealed more autophagosomes in the tumor tissues of KD group than that of SD group. P62 expression was lowered ( < 0.01) and Beclin1 and LC3A/B expressions were up-regulated in the tumor tissues of KD group ( < 0.05), which is consisitent with IHC. CONCLUSIONS KD has a strong anti-tumor effect in the xenograft mouse model possibly by regulating cell autophagy.
3-Hydroxybutyric Acid ; Animals ; Blood Glucose ; Cell Line, Tumor ; Diet, Ketogenic ; Humans ; Mice ; Mice, Inbred BALB C ; Neuroblastoma

TLR2 activity plays an important role in the pathogenesis of autoimmune diseases, tumor carcinogenesis and cardio-cerebrovascular diseases. To establish a TLR2 receptor-based cell screening model, NF-kappaB promoter-driven luciferase reporter plasmids were transfected into human embryonic kidney cells (HEK293) stably expressing human TLR2 and co-receptors CD14, TLR1 and TLR6. Single clones were then isolated and characterized. Using this screening system, a human TLR2-binding peptide C8 was obtained from the Ph.D.-7 Phage Display Peptide Library through biopanning and rapid analysis of selective interactive ligands (BRASIL). The binding characteristic of C8 with human TLR2 was evaluated by ELISA, flow cytometry and immunofluorescence. The NF-kappaB luciferase activity assay showed that C8 could activate the TLR2/TLR1 signaling pathway and induce the production of cytokines TNF-alpha and IL-6. In conclusion, the TLR2 receptor-based cell screening system is successfully established and a new TLR2-binding peptide is identified by using this system.