Comparative Bilateral Measurements of Vastus Lateralis Muscle Oxygen Desaturation Kinetics during 30 S Sprint Cycling Exercise: Effects of Age and Performance.

The study assessed vastus lateralis oxygen desaturation kinetics (SmO2) in 32 male cyclists (16 Seniors, 16 Juniors) during a 30 s sprint, examining effects of age and performance. An incremental test was used to determine ventilatory thresholds (VT1, VT2) and maximal oxygen uptake (VO2kg), followed by a sprint test to evaluate anaerobic performance. Cyclists' performance phenotype was determined as the ratio of power at VT2 to 5 s peak sprint power. Juniors exhibited sprinter-like traits, excelling in all functional tests except for lactate levels post-sprint. SmO2 data showed no age-related or bilateral differences across participants. The combined mean response time (MRT) revealed stronger bilateral goodness of fit (R2 = 0.64) than individual time delay (TD) and time constant (τ). Higher VO2kg at VT2, peak power, and maximal uptake were linked to longer TD, while shorter TD correlated with higher lactate production and increased fatigue. Bilaterally averaged SmO2 kinetics distinguished between sprint and endurance athletes, indicating the potential to reflect the alactic anaerobic system's capacity and depletion. Age did not affect desaturation rates, but younger cyclists showed greater response amplitude, attributed to a higher initial baseline rather than maximal desaturation at the end of the exercise.

Bioenergetic impairment in Gulf War illness assessed via 31P-MRS.

Time for post-exercise phosphocreatine-recovery (PCr-R), deemed a robust index of mitochondrial function in vivo, was previously reported to be elevated (signifying impaired ATP production) in veterans with Gulf War illness (GWI). Here we sought to replicate the finding and assess the impact of contravening previous eligibility requirements. The replication sample comprised white males. Cases reported ≥ moderate muscle-weakness to match the organ assessed to an organ affected; controls lacked recent headache or multiple symptoms. The expansion sample added cases without muscle-weakness, controls with recent headache, females, nonwhites. PCr-R, following pedal-depression-exercise, was compared in veterans with GWI versus controls (sample N = 38). In the replication sample, PCr-R results closely matched the prior report: PCr-R veterans with GWI mean(SD) = 47.7(16.5); control mean(SD) = 30.3(9.2), p = 0.017. (Prior-study PCr-R veterans with GWI mean(SD) = 46.1(17.9), control mean(SD) = 29.0(8.7), p = 0.023. Combined replication + prior samples: p = 0.001.) No case-control difference was observed in the expansion sample. In cases, PCr-R related to muscle-weakness: PCr-R = 29.9(7.1), 38.2(8.9), 47.8(15.2) for muscle-weakness rated none/low, intermediate, and high respectively (p for trend = 0.02), validating desirability of matching tissue assessed to tissue affected. In controls, headache/multiple symptoms, sex, and ethnicity each mattered (affecting PCr-R significantly). This study affirms mitochondrial/bioenergetic impairment in veterans with GWI. The importance of careful case/control selection is underscored.

17ß-Estradiol Effects in Skeletal Muscle: A 31P MR Spectroscopic Imaging (MRSI) Study of Young Females during Early Follicular (EF) and Peri-Ovulation (PO) Phases.

The natural variation in estrogen secretion throughout the female menstrual cycle impacts various organs, including estrogen receptor (ER)-expressed skeletal muscle. Many women commonly experience increased fatigue or reduced energy levels in the days leading up to and during menstruation, when blood estrogen levels decline. Yet, it remains unclear whether endogenous 17ß-estradiol, a major estrogen component, directly affects the energy metabolism in skeletal muscle due to the intricate and fluctuating nature of female hormones. In this study, we employed 2D 31P FID-MRSI at 7T to investigate phosphoryl metabolites in the soleus muscle of a cohort of young females (average age: 28 ± 6 years, n = 7) during the early follicular (EF) and peri-ovulation (PO) phases, when their blood 17ß-estradiol levels differ significantly (EF: 28 ± 18 pg/mL vs. PO: 71 ± 30 pg/mL, p < 0.05), while the levels of other potentially interfering hormones remain relatively invariant. Our findings reveal a reduction in ATP-referenced phosphocreatine (PCr) levels in the EF phase compared to the PO phase for all participants (5.4 ± 4.3%). Furthermore, we observe a linear correlation between muscle PCr levels and blood 17ß-estradiol concentrations (r = 0.64, p = 0.014). Conversely, inorganic phosphate Pi and phospholipid metabolite GPC levels remain independent of 17ß-estradiol but display a high correlation between the EF and PO phases (p = 0.015 for Pi and p = 0.0008 for GPC). The robust association we have identified between ATP-referenced PCr and 17ß-estradiol suggests that 17ß-estradiol plays a modulatory role in the energy metabolism of skeletal muscle.

Creatine in Cognitive Performance: A Commentary.

Given the importance of cognition in everyday life, medicines that improve cognition safely and affordably are highly wanted. Creatine is an amino acid-derived substance that aids in the restoration of adenosine triphosphate (ATP), which provides energy to muscle and brain tissue. Although the relationship between creatine and cognitive performance is still debatable, here is a brief description of creatine's influence on cognition with probable implications for future research on this intriguing topic.

Uncovering the Therapeutic Potential of Phosphocreatine in Diabetic Retinopathy: Mitigating Mitochondrial Dysfunction and Apoptosis via JAK2/STAT3 Signaling Pathway.

Diabetic retinopathy (DR) stands as a prevalent complication of diabetes mellitus, causing damage to the delicate retinal capillaries and potentially leading to visual impairment. While the exact underlying cause of DR remains elusive, compelling research suggests that mitochondrial energy deficiency and the excessive generation of reactive oxygen species (ROS) play pivotal roles in its pathogenesis. Recognizing that controlling hyperglycemia alone fails to reverse the defects in retinal mitochondria induced by diabetes, current strategies seek to restore mitochondrial function as a means of safeguarding against DR. To address this pressing issue, a comprehensive study was undertaken to explore the potential of phosphocreatine (PCr) in bolstering mitochondrial bioenergetics and providing protection against DR via modulation of the JAK2/STAT3 signaling pathway. Employing rat mitochondria and RGC-5 cells, the investigation meticulously assessed the impact of PCr on ROS production, mitochondrial membrane potential, as well as the expression of crucial apoptotic and JAK2/STAT3 signaling pathway proteins, utilizing cutting-edge techniques such as high-resolution respirometry and western blotting. The remarkable outcomes revealed that PCr exerts a profound protective influence against DR by enhancing mitochondrial function and alleviating diabetes-associated symptoms and biochemical markers. Notably, PCr administration resulted in an upregulation of antiapoptotic proteins, concomitant with a downregulation of proapoptotic proteins and the JAK2/STAT3 signaling pathway. These significant findings firmly establish PCr as a potential therapeutic avenue for combating diabetic retinopathy. By augmenting mitochondrial function and exerting antiapoptotic effects via the JAK2/STAT3 signaling pathway, PCr demonstrates promising efficacy both in vivo and in vitro, particularly in counteracting the oxidative stress engendered by hyperglycemia. In summary, our study sheds light on the potential of PCr as an innovative therapeutic strategy for diabetic retinopathy. By bolstering mitochondrial function and exerting protective effects via the modulation of the JAK2/STAT3 signaling pathway, PCr holds immense promise in ameliorating the impact of DR in the face of oxidative stress induced by hyperglycemia.

Muscular stress is equal when resistance exercise with blood flow restriction is matched in total work volume: A cross-sectional, cross-over study.

AIM: We compared muscular metabolic stress during exercise performed at multiple intensities, from very low to moderate, with blood flow restriction (BFR) adjusted by the same work volume. METHODS: Twenty-five healthy young adults performed unilateral plantar flexion at 1 repetition/2 s in a magnetic resonance system. The BFR exercise protocols were as follows: (A) exercise with 10% of one repetition maximum (1-RM) for 360 s, (B) 15% 1-RM for 240 s, (C) 20% 1-RM for 180 s, (D) 30% 1-RM for 120 s, and (E) 40% 1-RM for 90 s. All protocols had the same total work volume (load × repetitions = 1800). A high-intensity protocol at 65% 1-RM without BFR (60 s) was also performed for comparison. We used 31 P-magnetic resonance spectroscopy to evaluate the muscular metabolic stress in the subjects' calf muscle, defined as decreases in phosphocreatine and intramuscular pH. RESULTS: The phosphocreatine depletion (A: 15.6 ± 0.7, B: 14.8 ± 0.8, C: 15.2 ± 0.6, D: 14.3 ± 0.6, E: 10.9 ± 0.5 mM; no significant difference [ns]) and the intramuscular pH decrease (A: 6.82 ± 0.02, B: 6.84 ± 0.01, C: 6.83 ± 0.02, D: 6.83 ± 0.02, E: 6.77 ± 0.02; ns) at the end of each exercise were similar and greater than those produced by the 65% 1-RM without BFR. CONCLUSION: If the total work volumes are equal, the metabolic stress in exercising muscle may reach similar levels at the end of exercise with BFR and could provide similar successful training effects.

Age-related changes in energy metabolism in peripheral mononuclear blood cells (PBMCs) and the brains of cognitively healthy seniors.

Mitochondrial dysfunction is a hallmark of cellular senescence and many age-related neurodegenerative diseases. We therefore investigated the relationship between mitochondrial function in peripheral blood cells and cerebral energy metabolites in young and older sex-matched, physically and mentally healthy volunteers. Cross-sectional observational study involving 65 young (26.0 ± 0.49 years) and 65 older (71.7 ± 0.71 years) women and men recruited. Cognitive health was evaluated using established psychometric methods (MMSE, CERAD). Blood samples were collected and analyzed, and fresh peripheral blood mononuclear cells (PBMCs) were isolated. Mitochondrial respiratory complex activity was measured using a Clarke electrode. Adenosine triphosphate (ATP) and citrate synthase activity (CS) were determined by bioluminescence and photometrically. N-aspartyl-aspartate (tNAA), ATP, creatine (Cr), and phosphocreatine (PCr) were quantified in brains using 1H- and 31P-magnetic resonance spectroscopic imaging (MRSI). Levels of insulin-like growth factor 1 (IGF-1) were determined using a radio-immune assay (RIA). Complex IV activity (CIV) (- 15%) and ATP levels (- 11%) were reduced in PBMCs isolated from older participants. Serum levels of IGF-1 were significantly reduced (- 34%) in older participants. Genes involved in mitochondrial activity, antioxidant mechanisms, and autophagy were unaffected by age. tNAA levels were reduced (- 5%), Cr (+ 11%), and PCr (+ 14%) levels were increased, and ATP levels were unchanged in the brains of older participants. Markers of energy metabolism in blood cells did not significantly correlate with energy metabolites in the brain. Age-related bioenergetic changes were detected in peripheral blood cells and the brains of healthy older people. However, mitochondrial function in peripheral blood cells does not reflect energy related metabolites in the brain. While ATP levels in PBMCs may be be a valid marker for age-related mitochondrial dysfunction in humans, cerebral ATP remained constant.

Simultaneous creatine and phosphocreatine mapping of skeletal muscle by CEST MRI at 3T.

PURPOSE: To confirm that CrCEST in muscle exhibits a slow-exchanging process, and to obtain high-resolution amide, creatine (Cr), and phosphocreatine (PCr) maps of skeletal muscle using a POlynomial and Lorentzian Line-shape Fitting (PLOF) CEST at 3T. METHODS: We used dynamic changes in PCr/CrCEST of mouse hindlimb before and after euthanasia to assign the Cr and PCr CEST peaks in the Z-spectrum at 3T and to obtain the optimum saturation parameters. Segmented 3D EPI was employed to obtain multi-slice amide, PCr, and Cr CEST maps of human skeletal muscle. Subsequently, the PCrCEST maps were calibrated using the PCr concentrations determined by 31 P MRS. RESULTS: A comparison of the Z-spectra in mouse hindlimb before and after euthanasia indicated that CrCEST is a slow-exchanging process in muscle (<150.7 s-1 ). This allowed us to simultaneously extract PCr/CrCEST signals at 3T using the PLOF method. We determined optimal B1 values ranging from 0.3 to 0.6 µT for CrCEST in muscle and 0.3-1.2 µT for PCrCEST. For the study on human calf muscle, we determined an optimum saturation time of 2 s for both PCr/CrCEST (B1 = 0.6 µT). The PCr/CrCEST using 3D EPI were found to be comparable to those obtained using turbo spin echo (TSE). (3D EPI/TSE PCr: (2.6 ± 0.3) %/(2.3 ± 0.1) %; Cr: (1.3 ± 0.1) %/(1.4 ± 0.07) %). CONCLUSIONS: Our study showed that in vivo CrCEST is a slow-exchanging process. Hence, amide, Cr, and PCr CEST in the skeletal muscle can be mapped simultaneously at 3T by PLOF CEST.

A rapid method for phosphocreatine-weighted imaging in muscle using double saturation power-chemical exchange saturation transfer.

Monitoring the variation in phosphocreatine (PCr) levels following exercise provides valuable insights into muscle function. Chemical exchange saturation transfer (CEST) has emerged as a sensitive method with which to measure PCr levels in muscle, surpassing conventional MR spectroscopy. However, existing approaches for quantifying PCr CEST signals rely on time-consuming fitting methods that require the acquisition of the entire or a section of the CEST Z-spectrum. Additionally, traditional fitting methods often necessitate clear CEST peaks, which may be challenging to obtain at low magnetic fields. This paper evaluated the application of a new model-free method using double saturation power (DSP), termed DSP-CEST, to estimate the PCr CEST signal in muscle. The DSP-CEST method requires the acquisition of only two or a few CEST signals at the PCr frequency offset with two different saturation powers, enabling rapid dynamic imaging. Additionally, the DSP-CEST approach inherently eliminates confounding signals, offering enhanced robustness compared with fitting methods. Furthermore, DSP-CEST does not demand clear CEST peaks, making it suitable for low-field applications. We evaluated the capability of DSP-CEST to enhance the specificity of PCr CEST imaging through simulations and experiments on muscle tissue phantoms at 4.7 T. Furthermore, we applied DSP-CEST to animal leg muscle both before and after euthanasia and observed successful reduction of confounding signals. The DSP-CEST signal still has contaminations from a residual magnetization transfer (MT) effect and an aromatic nuclear Overhauser enhancement effect, and thus only provides a PCr-weighted imaging. The residual MT effect can be reduced by a subtraction of DSP-CEST signals at 2.6 and 5 ppm. Results show that the residual MT-corrected DSP-CEST signal at 2.6 ppm has significant variation in postmortem tissues. By contrast, both the CEST signal at 2.6 ppm and a conventional Lorentzian difference analysis of CEST signal at 2.6 ppm demonstrate no significant variation in postmortem tissues.

Myocardial protection with phosphocreatine in high-risk cardiac surgery patients: a randomized trial.

BACKGROUND: This study was conducted to test the hypothesis that phosphocreatine (PCr), administered intravenously and as cardioplegia adjuvant in patients undergoing cardiac surgery with prolonged aortic cross clamping and cardiopulmonary bypass (CPB) time, would decrease troponin I concentration after surgery. METHODS: In this randomized, double-blind, placebo-controlled pilot study we included 120 patients undergoing double/triple valve repair/replacement under cardiopulmonary bypass in the cardiac surgery department of a tertiary hospital. The treatment group received: intravenous administration of 2 g of PCr after anesthesia induction; 2.5 g of PCr in every 1 L of cardioplegic solution (concentration = 10 mmol/L); intravenous administration of 2 g of PCr immediately after heart recovery following aorta declamping; 4 g of PCr at intensive care unit admission. The control group received an equivolume dose of normosaline. RESULTS: The primary endpoint was peak concentration of troponin I after surgery. Secondary endpoints included peak concentration of serum creatinine, need for, and dosage of inotropic support, number of defibrillations after aortic declamping, incidence of arrhythmias, duration of Intensive Care Unit (ICU) stay, length of hospitalization. There was no difference in peak troponin I concentration after surgery (PCr, 10,508 pg/ml [IQR 6,838-19,034]; placebo, 11,328 pg/ml [IQR 7.660-22.894]; p = 0.24). There were also no differences in median peak serum creatinine (PCr, 100 µmol/L [IQR 85.0-117.0]; placebo, 99.5 µmol/L [IQR 90.0-117.0]; p = 0.87), the number of patients on vasopressor/inotropic agents (PCr, 49 [88%]; placebo, 57 [91%]; p = 0.60), the inotropic score on postoperative day 1 (PCr, 4.0 (0-7); placebo, 4.0 (0-10); p = 0.47), mean SOFA score on postoperative day 1 (PCr, 5.25 ± 2.33; placebo, 5,45 ± 2,65; p = 0.83), need for defibrillation after declamping of aorta (PCr, 22 [39%]; placebo, 25 [40%]; p = 0.9),, duration of ICU stay and length of hospitalization as well as 30-day mortality (PCr, 0 (0%); placebo,1 (4.3%); p = 0.4). CONCLUSION: PCr administration to patients undergoing double/triple valve surgery under cardiopulmonary bypass is safe but is not associated with a decrease in troponin I concentration. Phosphocreatine had no beneficial effect on clinical outcomes after surgery. TRIAL REGISTRATION: The study is registered at ClinicalTrials.gov with the Identifier: NCT02757443. First posted (published): 02/05/2016.

Quantitative Assessment of Peripheral Oxidative Metabolism With a New Dynamic 1 H MRI Technique: A Pilot Study in People With and Without Diabetes Mellitus.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is linked to impaired mitochondrial function. Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) is a gadolinium-contrast-free 1 H method to assess mitochondrial function by measuring low-concentration metabolites. A CEST MRI-based technique may serve as a non-invasive proxy for assessing mitochondrial health. HYPOTHESIS: A 1 H CEST MRI technique may detect significant differences in in vivo skeletal muscle phosphocreatine (SMPCr) kinetics between healthy volunteers and T2DM patients undergoing standardized isometric exercise. STUDY TYPE: Cross-sectional study. SUBJECTS: Seven subjects without T2DM (T2DM-) and seven age, sex, and BMI-matched subjects with T2DM (T2DM+). FIELD STRENGTH/SEQUENCE: Single-shot rapid acquisition with refocusing echoes (RARE) and single-shot gradient-echo sequences, 3 T. ASSESSMENT: Subjects underwent a rest-exercise-recovery imaging protocol to dynamically acquire SMPCr maps in calf musculature. Medial gastrocnemius (MG) and soleus SMPCr concentrations were plotted over time, and SMPCr recovery time, τ $$ \tau $$ , was determined. Mitochondrial function index was calculated as the ratio of resting SMPCr to τ $$ \tau $$ . Participants underwent a second exercise protocol for imaging of skeletal muscle blood flow (SMBF), and its association with SMPCr was assessed. STATISTICAL TESTS: Unpaired t-tests and Pearson correlation coefficient. A P value <0.05 was considered statistically significant. RESULTS: SMPCr concentrations in MG and soleus displayed expected declines during exercise and returns to baseline during recovery. τ $$ \tau $$ was significantly longer in the T2DM+ cohort (MG 83.5 ± 25.8 vs. 54.0 ± 21.1, soleus 90.5 ± 18.9 vs. 51.2 ± 14.5). The mitochondrial function index in the soleus was significantly lower in the T2DM+ cohort (0.33 ± 0.08 vs. 0.66 ± 0.19). SMBF was moderately correlated with the SMPCr in T2DM-; this correlation was not significant in T2DM+ (r = -0.23, P = 0.269). CONCLUSION: The CEST MRI method is feasible for quantifying SMPCr in peripheral muscle tissue. T2DM+ individuals had significantly lower oxidative capacities than T2DM- individuals. In T2DM, skeletal muscle metabolism appeared to be decoupled from perfusion. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 1.

Protective effects of phosphocreatine on human vascular endothelial cells against hydrogen peroxide-induced apoptosis and in the hyperlipidemic rat model.

Phosphocreatine (PCr) has been shown to have a cardio-protective effect during cardiopulmonary resuscitation (CPR). However, little is known about its impact on atherosclerosis. In this study, we first evaluated the pharmacological effects of PCr on antioxidative defenses and mitochondrial protection against hydrogen peroxide (H2O2) induced human umbilical vascular endothelial cells (HUVECs) damage. Then we investigated the hypolipidemic and antioxidative effects of PCr on hyperlipidemic rat model. Via in vitro studies, H2O2 significantly reduced cell viability and increased apoptosis rate of HUVECs, while pretreatment with PCr abolished its apoptotic effect. PCr could reduce the generation of ROS induced by H2O2. Moreover, PCr could increase the activity of SOD and the content of NO, as well as decrease the activity of LDH and the content of MDA. PCr could also antagonize H2O2-induced up-regulation of Bax, cleaved-caspase3, cleaved-caspase9, and H2O2-induced down-regulation of Bcl-2 and p-Akt/Akt ratio. In addition, PCr reduced U937 cells' adhesion to H2O2-stimulated HUVECs. Via in vivo study, PCr could decrease MDA, TC, TG and LDL-C levels in hyperlipidemic rats. Finally, different-concentration PCr could increase the leaching of TC, HDL, and TG from fresh human atherosclerotic plaques. In conclusion, PCr could suppress H2O2-induced apoptosis in HUVECs and reduce hyperlipidemia through inhibiting ROS generation and modulating dysfunctional mitochondrial system, which might be an effective new therapeutic strategy to further prevent atherosclerosis.

Aspects of human uterine creatine metabolism during the menstrual cycle and at term pregnancy†.

Creatine metabolism likely contributes to energy homeostasis in the human uterus, but whether this organ synthesizes creatine and whether creatine metabolism is adjusted throughout the menstrual cycle and with pregnancy are largely unknown. This study determined endometrial protein expression of creatine-synthesizing enzymes arginine:glycine amidinotransferase (AGAT) and guanidinoacetate methyltransferase (GAMT), creatine kinase (CKBB), and the creatine transporter (SLC6A8) throughout the menstrual cycle in fertile and primary infertile women. It also characterized creatine metabolism at term pregnancy, measuring aspects of creatine metabolism in myometrial and decidual tissue. In endometrial samples, AGAT, GAMT, SLC6A8, and CKBB were expressed in glandular and luminal epithelial cells. Except for SLC6A8, the other proteins were also located in stromal cells. Irrespective of fertility, AGAT, GAMT, and SLC6A8 high-intensity immunohistochemical staining was greatest in the early secretory phase of the menstrual cycle. During the proliferative phase, staining for SLC6A8 protein was greater (P = 0.01) in the primary infertile compared with the fertile group. Both layers of the term pregnant uterus contained creatine, phosphocreatine, guanidinoacetic acid, arginine, glycine, and methionine; detectable gene and protein expression of AGAT, GAMT, CKBB, and ubiquitous mitochondrial CK (uMt-CK); and gene expression of SLC6A8. The proteins AGAT, GAMT, CKBB, and SLC6A8 were uniformly distributed in the myometrium and localized to the decidual glands. In conclusion, endometrial tissue has the capacity to produce creatine and its capacity is highest around the time of fertilization and implantation. Both layers of the term pregnant uterus also contained all the enzymatic machinery and substrates of creatine metabolism.

Phosphocreatine addition to extender enhances the quality and antioxidant capacity of cryopreserved boar sperm.

Boar sperm are less resistant to drastic changes in the external environment during cryopreservation, mainly because their plasma membranes are rich in unsaturated fatty acids but lack cholesterol and are thus susceptible to lipid peroxidation caused by the attack of reactive oxygen species. This study evaluated the effect of adding phosphocreatine to cryopreservation extenders on boar sperm quality and antioxidant capacity. Different concentrations (0, 5.0, 7.5, 10.0 and 12.5 mmol/L) of phosphocreatine were added to the cryopreservation extender. After thawing, sperm were analysed for morphological parameters, kinetic parameters, acrosome integrity, membrane integrity, mitochondrial activity, DNA integrity and antioxidant enzyme activity. The results showed that 10.0 mmol/L phosphocreatine samples enhanced the boar sperm motility, viability, average path velocity, straight-line velocity, curvilinear velocity and beat cross frequency after cryopreservation and reduced the malformation rate compared to the control group (p < .05). The acrosome integrity, membrane integrity, mitochondrial activity and DNA integrity of boar sperm were higher than those of the control group after adding 10.0 mmol/L phosphocreatine to the cryopreservation extender (p < .05). Extenders containing 10.0 mmol/L phosphocreatine maintained high total antioxidant capacity; elevated the activities of catalase, glutathione peroxidase and superoxide dismutase; reduced malondialdehyde and H2 O2 content (p < .05). Therefore, adding phosphocreatine to the extender is potentially beneficial for boar sperm cryopreservation at an optimal 10.0 mmol/L concentration.

Advanced phosphocreatine-grafted chitosan hydrogel promote wound healing by macrophage modulation.

Background: The repair of wounds usually caused by trauma or other chronic diseases remained challenging in clinics due to the potential risk of inflammation and inadequate tissue regenerative properties. Among them, the behaviour of immune cells, such as macrophages, is critical in tissue repair. Materials and methods: In this study, a water-soluble phosphocreatine-grafted methacryloyl chitosan (CSMP) was synthesized with a one-step lyophilization method, followed by the fabrication of CSMP hydrogel with a photocrosslinked method. The microstructure, water absorption and mechanical properties for the hydrogels were investigated. Then, the macrophages were co-cultured with hydrogels and the pro-inflammatory factors and polarization markers for these macrophages were detected through real-time quantitative polymerase chain reaction (RT-qPCR), Western blot (WB), and flow cytometry methods. Finally, the CSMP hydrogel was implanted in a wound defect area in mice to test its ability to promote wound healing. Results: The lyophilized CSMP hydrogel had a porous structure with pores ranging in size from 200 to 400 µm, which was larger than the CSM hydrogel's. The lyophilized CSMP hydrogel possessed a higher water absorption rate compared with the CSM hydrogel. The compressive stress and modulus of these hydrogels were increased in the initial 7 days immersion and then gradually decreased during the in vitro immersion in PBS solution up to 21 days; the CSMP hydrogel showed a higher value in these parameters versus the CSM hydrogel. The CSMP hydrogel inhibited the expression of inflammatory factors such as interleukin-1ß (IL-1ß), IL-6, IL-12, and tumor necrosis factor-α (TNF-α) in an in vitro study cocultured with pro-inflammatory factors in pre-treated bone marrow-derived macrophages (BMM). The mRNA sequencing results showed that the CSMP hydrogel might inhibit the macrophages' M1 type polarization through the NF-κB signaling pathway. Furthermore, when compared to the control group, the CSMP hydrogel promoted more skin area repair in the mouse wound defect area, and inflammatory factors such as IL-1ß, IL-6, and TNF-α were lower in the repaired tissue for the CSMP group. Conclusion: This phosphate-grafted chitosan hydrogel showed great promise for wound healing through regulating the macrophage's phenotype via the NF-κB signaling pathway.

Energy System Contributions during Olympic Combat Sports: A Narrative Review.

This narrative review focuses on the studies that estimate the energy systems' contributions during match simulations of striking (boxing, karate, and taekwondo), grappling (judo), and weapon-based (fencing) Olympic combat sports. The purpose is to provide insights into the metabolism of these athletes. In striking Olympic combat sports, the oxidative contribution varied from 62% (in karate and taekwondo) to 86% (in boxing), the ATP-PCr system contribution varied from 10% (in boxing) to 31% (in taekwondo), and the glycolytic contribution was between 3% (in the third round of taekwondo) and 21% (in karate). In grappling combat sports, only judo was studied, and for a 4 min match, the oxidative contribution was 79%, followed by 14% ATP-PCr system contribution and 7% contribution from the glycolytic system. In fencing, the only weapon-based Olympic combat sport, the oxidative contribution varied from 81% (in the first bout) to 90% (in the second bout), followed by 9% (bout 2) to 12% (bout 1) contribution from the ATP-PCr system, and 0.6% to 7% contribution from the glycolytic system during 3 × 3 min bouts of épée match simulation. Hence, Olympic combat sports are primarily powered by the oxidative system, but the key scoring actions are likely fueled by anaerobic pathways.

Preclinical evaluation of triiodothyronine nanoparticles as a novel therapeutic intervention for resuscitation from cardiac arrest.

BACKGROUND: Given emerging evidence of rapid non-genomic cytoprotective effects of triiodothyronine (T3), we evaluated the resuscitative efficacy of two nanoparticle formulations of T3 (T3np) designed to prolong cell membrane receptor-mediated signaling. METHODS: Swine (n = 40) were randomized to intravenous vehicle (empty np), EPI (0.015 mg/kg), T3np (0.125 mg/kg), or T3np loaded with phosphocreatine (T3np + PCr; 0.125 mg/kg) during CPR following 7-min cardiac arrest (n = 10/group). Hemodynamics and biomarkers of heart (cardiac troponin I; cTnI) and brain (neuron-specific enolase; NSE) injury were assessed for up to 4-hours post-ROSC, at which time the heart and brain were collected for post-mortem analysis. RESULTS: Compared with vehicle (4/10), the rate of ROSC was higher in swine receiving T3np (10/10; p < 0.01), T3np + PCr (8/10; p = 0.08) or EPI (10/10; p < 0.01) during CPR. Although time to ROSC and survival duration were comparable between groups, EPI was associated with a ∼2-fold higher post-ROSC concentration of cTnI vs T3np and T3np + PCr and the early post-ROSC rise in NSE and neuronal injury were attenuated in T3np-treated vs EPI-treated animals. Analysis of hippocampal ultrastructure revealed deterioration of mitochondrial integrity, reduced active zone length, and increased axonal vacuolization in EPI-treated animals vs controls. However, the frequency of these abnormalities was diminished in animals resuscitated with T3np. CONCLUSIONS: T3np achieved a ROSC rate and post-ROSC survival that was superior to vehicle and comparable to EPI. The attenuation of selected biomarkers of cardiac and neurologic injury at individual early post-ROSC timepoints in T3np-treated vs EPI-treated animals suggests that T3np administration during CPR may lead to more favorable outcomes in cardiac arrest.

Chemical exchange saturation transfer imaging of creatine, phosphocreatine, and protein arginine residue in tissues.

Chemical exchange saturation transfer (CEST) MRI has become a promising technique to assay target proteins and metabolites through their exchangeable protons, noninvasively. The ubiquity of creatine (Cr) and phosphocreatine (PCr) due to their pivotal roles in energy homeostasis through the creatine phosphate pathway has made them prime targets for CEST in the diagnosis and monitoring of disease pathologies, particularly in tissues heavily dependent on the maintenance of rich energy reserves. Guanidinium CEST from protein arginine residues (i.e. arginine CEST) can also provide information about the protein profile in tissue. However, numerous obfuscating factors stand as obstacles to the specificity of arginine, Cr, and PCr imaging through CEST, such as semisolid magnetization transfer, fast chemical exchanges such as primary amines, and the effects of nuclear Overhauser enhancement from aromatic and amide protons. In this review, the specific exchange properties of protein arginine residues, Cr, and PCr, along with their validation, are discussed, including the considerations necessary to target and tune their signal effects through CEST imaging. Additionally, strategies that have been employed to enhance the specificity of these exchanges in CEST imaging are described, along with how they have opened up possible applications of protein arginine residues, Cr and PCr CEST imaging in the study and diagnosis of pathology. A clear understanding of the capabilities and caveats of using CEST to image these vital metabolites and mitigation strategies is crucial to expanding the possibilities of this promising technology.

Fam96b recruits brain-type creatine kinase to fuel mitotic spindle formation.

Mitosis is a complicated and ordered process with high energy demands and metabolite fluxes. Cytosolic creatine kinase (CK), an enzyme involved in ATP homeostasis, has been shown to be essential to chromosome movement during mitotic anaphase in sea urchin. However, it remains elusive for the molecular mechanism underlying the recruitment of cytosolic CK by the mitotic apparatus. In this study, Fam96b/MIP18, a component of the MMXD complex with a function in Fe/S cluster supply, was identified as a brain-type CK (CKB)-binding protein. The binding of Fam96b with CKB was independent of the presence of CKB substrates and did not interfere with CKB activity. Fam96b was prone to oligomerize via the formation of intermolecular disulfide bonds, while the binding of enzymatically active CKB could modulate Fam96b oligomerization. Oligomerized Fam96b recruited CKB and the MMXD complex to associate with the mitotic spindle. Depletion of Fam96b or CKB by siRNA in the HeLa cells led to mitotic defects, which further resulted in retarded cell proliferation, increased cell death and aberrant cell cycle progression. Rescue experiments indicated that both Fam96b oligomerization and CKB activity were essential to the proper formation of mitotic spindle. These findings suggest that Fam96b may act as a scaffold protein to coordinate the supply and homeostasis of ATP and Fe/S clusters during mitosis.