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.

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.

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.

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.

Effect of recovery time on [Formula: see text]-ON kinetics in humans at the onset of moderate-intensity cycling exercise

PURPOSE

τ of the primary phase of [Formula: see text] kinetics during square-wave, moderate-intensity exercise mirrors that of PCr splitting (τPCr). Pre-exercise [PCr] and the absolute variations of PCr (∆[PCr]) occurring during transient have been suggested to control τPCr and, in turn, to modulate [Formula: see text] kinetics. In addition, [Formula: see text] kinetics may be slower when exercise initiates from a raised metabolic level, i.e., from a less-favorable energetic state. We verified the hypothesis that: (i) pre-exercise [PCr], (ii) pre-exercise metabolic rate, or (iii) ∆[PCr] may affect the kinetics of muscular oxidative metabolism and, therefore, τ.

METHODS

To this aim, seven active males (23.0 yy ± 2.3; 1.76 m ± 0.06, [Formula: see text]: 3.32 L min^-1 ± 0.67) performed three repetitions of series consisting of six 6-min step exercise transitions of identical workload interspersed with different times of recovery: 30, 60, 90, 120, 300 s.

RESULTS

Mono-exponential fitting was applied to breath-by-breath [Formula: see text], so that τ was determined. τ decays as a first-order exponential function of the time of recovery (τ = 109.5 × e^(-t/14.0) + 18.9 r² = 0.32) and linearly decreased as a function of the estimated pre-exercise [PCr] (τ = - 1.07 [PCr] + 44.9, r² = 0.513, P < 0.01); it was unaffected by the estimated ∆[PCr].

CONCLUSIONS

Our results in vivo do not confirm the positive linear relationship between τ and pre-exercise [PCr] and ∆[PCr]. Instead, [Formula: see text] kinetics seems to be influenced by the pre-exercise metabolic rate and the altered intramuscular energetic state.

Contributions of energy pathways to ATP production and pH variations in postmortem muscles

The roles of energy pathways in postmortem muscles are still debated. In this study, the contributions of different pathways to ATP production and pH variations were analyzed by using a kinetic model based on data from beef longissimus lumborum. Phosphocreatine represents over 92% of the initial ATP production but, after 24 h, glycolysis, phosphocreatine, myokinase reaction, and aerobic respiration contribute, respectively, 89.44%, 5.26%, 4.44%, and 0.86% of the cumulative amount of ATP produced. ATP hydrolysis and glycolysis result in 0.52 and 0.6 units of pH decline, respectively, at 24 h with ATP hydrolysis accounting for most of the early decline. Phosphocreatine, myokinase reaction, and aerobic respiration lead to, respectively, 0.08, 0.07, and 0.004 units of pH increase after 24 h though phosphocreatine is depleted within the first 30 min. Furthermore, electrical stimulation affects pH primarily through ATP hydrolysis and glycolysis. The initial muscle oxygen saturation level and phosphocreatine content affect pH but the influences are small.

Protection of pancreatic β-cell by phosphocreatine through mitochondrial improvement via the regulation of dual AKT/IRS-1/GSK-3β and STAT3/Cyp-D signaling pathways

Diabetes mellitus (DM) is a metabolic syndrome, caused by insufficient insulin secretion or insulin resistance (IR). DM enhances oxidative stress and induces mitochondrial function in different kinds of cell types, including pancreatic β-cells. Our previous study has showed phosphocreatine (PCr) can advance the mitochondrial function through enhancing the oxidative phosphorylation and electron transport ability in mitochondria damaged by methylglyoxal (MG). Our aim was to explore the potential role of PCr as a molecule to protect mitochondria from diabetes-induced pancreatic β-cell injury with insulin secretion deficiency or IR through dual AKT/IRS-1/GSK-3β and STAT3/Cyclophilin D (Cyp-D) signaling pathways. MG-induced INS-1 cell viability, apoptosis, mitochondrial division and fusion, the morphology, and function of mitochondria were suppressed. Flow cytometry was used to detect the production of intracellular reactive oxygen species (ROS) and the changes of intracellular calcium, and the respiratory function was measured by oxygraph-2k. The expressions of AKT, IRS-1, GSK-3β, STAT3, and Cyp-D were detected using Western blot. The result showed that the oxidative stress-related kinases were significantly restored to the normal level after the pretreatment with PCr. Moreover, PCr pretreatment significantly inhibited cell apoptosis, decreased intracellular calcium, and ROS production, and inhibited mitochondrial division and fusion, and increased ATP synthesis damaged by MG in INS-1 cells. In addition, pretreatment with PCr suppressed Cytochrome C, p-STAT3, and Cyp-D expressions, while increased p-AKT, p-IRS-1, p-GSK-3β, caspase-3, and caspase-9 expressions. In conclusion, PCr has protective effect on INS-1 cells in vitro and in vivo, relying on AKT mediated STAT3/ Cyp-D pathway to inhibit oxidative stress and restore mitochondrial function, signifying that PCr might become an emerging candidate for the cure of diabetic pancreatic cancer β-cell damage.

The effects of phosphocreatine disodium salts plus blueberry extract supplementation on muscular strength, power, and endurance

BACKGROUND

Numerous studies have demonstrated the efficacy of creatine supplementation for improvements in exercise performance. Few studies, however, have examined the effects of phosphocreatine supplementation on exercise performance. Furthermore, while polyphenols have antioxidant and anti-inflammatory properties, little is known regarding the influence of polyphenol supplementation on muscular strength, power, and endurance. Thus, the purpose of the present study was to compare the effects of 28 days of supplementation with phosphocreatine disodium salts plus blueberry extract (PCDSB), creatine monohydrate (CM), and placebo on measures of muscular strength, power, and endurance.

METHODS

Thirty-three men were randomly assigned to consume either PCDSB, CM, or placebo for 28 days. Peak torque (PT), average power (AP), and percent decline for peak torque (PT%) and average power (AP%) were assessed from a fatigue test consisting of 50 maximal, unilateral, isokinetic leg extensions at 180°·s^- 1 before and after the 28 days of supplementation. Individual responses were assessed to examine the proportion of subjects that exceeded a minimal important difference (MID).

RESULTS

The results demonstrated significant (p < 0.05) improvements in PT for the PCDSB and CM groups from pre- (99.90 ± 22.47 N·m and 99.95 ± 22.50 N·m, respectively) to post-supplementation (119.22 ± 29.87 N·m and 111.97 ± 24.50 N·m, respectively), but no significant (p = 0.112) change for the placebo group. The PCDSB and CM groups also exhibited significant improvements in AP from pre- (140.18 ± 32.08 W and 143.42 ± 33.84 W, respectively) to post-supplementation (170.12 ± 42.68 W and 159.78 ± 31.20 W, respectively), but no significant (p = 0.279) change for the placebo group. A significantly (p < 0.05) greater proportion of subjects in the PCDSB group exceeded the MID for PT compared to the placebo group, but there were no significant (p > 0.05) differences in the proportion of subjects exceeding the MID between the CM and placebo groups or between the CM and PCDSB groups.

CONCLUSIONS

These findings indicated that for the group mean responses, 28 days of supplementation with both PCDSB and CM resulted in increases in PT and AP. The PCDSB, however, may have an advantage over CM when compared to the placebo group for the proportion of individuals that respond favorably to supplementation with meaningful increases in muscular strength.

Non-energy mechanism of phosphocreatine on the protection of cell survival

If mitochondrial energy availability or oxidative metabolism is altered, patients will suffer from insufficient energy supply Phosphocreatine (PCr) not only acts as an energy carrier, but also acts as an antioxidant and defensive agent to maintain the integrity and stability of the membrane, to maintain ATP homeostasis through regulating mitochondrial respiration. Meanwhile, PCr can enhance calcium balance and reduce morphological pathological changes, ultimately, PCr helps to reduce apoptosis. On the other aspect, the activities of ATP synthase and MitCK play a crucial role in the maintenance of cellular energy metabolic function. It is interesting to note, PCr not only rises the activities of ATP synthase as well as MitCK, but also promotes these two enzymatic reactions. Additionally, PCr can also inhibit mitochondrial permeability transition in a concentration-dependent manner, prevent ROS and CytC from spilling into the cytoplasm, thereby inhibit the release of proapoptotic factors caspase-3 and caspase-9, and eventually, effectively prevent LPS-induced apoptosis of cells. Understandably, PCr prevents the apoptosis caused by abnormal mitochondrial energy metabolism and has a protective role in a non-energy manner. Moreover, recent studies have shown that PCr protects cell survival through PI3K/Akt/eNOS, MAPK pathway, and inhibition of Ang II-induced NF-κB activation. Furthermore, PCr antagonizes oxidative stress through the activation of PI3K/Akt/GSK3b intracellular pathway, PI3K/AKT-PGC1α signaling pathway, while through the promotion of SIRT3 expression to maintain normal cell metabolism. Interestingly, PCr results in delaying the time to enter pathological metabolism through the delayed activation of AMPK pathway, which is different from previous studies, now we propose the hypothesis that the "miRNA-JAK2/STAT3 -CypD pathway" may take part in protecting cells from apoptosis, PCr may be further be involved in the dynamic relationship between CypD and STAT3. Furthermore, we believe that PCr and CypD would be the central link to maintain cell survival and maintain cell stability and mitochondrial repair under the mitochondrial dysfunction caused by oxidative stress. This review provides the modern progress knowledge and views on the molecular mechanism and molecular targets of PCr in a non-energy way.

Phosphocreatine Promotes Osteoblastic Activities in H2O2-Induced MC3T3-E1 Cells by Regulating SIRT1/FOXO1/PGC-1α Signaling Pathway

BACKGROUND

Osteoporosis, characterized by bone loss, usually occurs with the increased bone resorption and decreased bone formation. H₂O₂-induced MC3T3-E1 cells are commonly used for the study of osteoblastic activities, which play a crucial role in bone formation.

OBJECTIVE

This study aimed to investigate the effects of Phosphocreatine (PCr) on the osteoblastic activities in H₂O₂-induced MC3T3-E1 cells and elaborate on the possible molecular mechanism.

METHODS

The Osteoprotegerin (OPG)/Receptor Activator of NF-κB Ligand (RANKL) ratio and osteogenic markers were detected to investigate the effects of PCr on osteoblastic activities, and the osteoblastic apoptosis was detected using Hochest staining. Moreover, oxidative stress, Adenosine Triphosphate (ATP) generation and the expression of Sirtuin 1 (SIRT1), Forkhead Box O 1 (FOXO1) and Peroxisome Proliferator-Activated Receptor Γ Coactivator-1α (PGC-1α) were also examined to uncover the possible molecular mechanism in H₂O₂-induced MC3T3-E1 cells.

RESULT

The results showed that PCr promoted the osteoblastic differentiation by increasing the expression levels of osteogenic markers of Alkaline Phosphatase (ALP) and Runt-related transcription factor 2 (Runx2), as well as increased the OPG/RANKL ratio and suppressed the osteoblastic apoptosis in H₂O₂-induced MC3T3-E1 cells. Moreover, treatment with PCr suppressed reactive oxygen species (ROS) over-generation and promoted the ATP production as well as increased the PGC-1α, FOXO1 and SIRT1 protein expression levels in H₂O₂-induced MC3T3-E1 cells.

CONCLUSION

PCr treatment could promote osteoblastic activities via suppressing oxidative stress and increasing the ATP generation in H₂O₂-induced MC3T3-E1 cells. In addition, the positive effects of PCr on osteoblasts might be regulated by SIRT1/FOXO1/ PGC-1α signaling pathway.

Creatine metabolism in the uterus: potential implications for reproductive biology

Creatine is an amino acid derivative synthesized from arginine, glycine and methionine. It serves as the substrate for the creatine kinase system, which is vital for maintaining ATP levels in tissues with high and fluctuating energy demand. There exists evidence that the creatine kinase system operates in both the endometrial and myometrial layers of the uterus. While use and regulation of this system in the uterus are not well understood, it is likely to be important given uterine tissues undergo phases of increased energy demand during certain stages of the female reproductive cycle, pregnancy, and parturition. This review discusses known adaptations of creatine metabolism in the uterus during the reproductive cycle (both estrous and menstrual), pregnancy and parturition, highlighting possible links to fertility and the existing knowledge gaps. Specifically, we discuss the adaptations and regulation of uterine creatine metabolite levels, cell creatine transport, de novo creatine synthesis, and creatine kinase expression in the various layers and cell types of the uterus. Finally, we discuss the effects of dietary creatine on uterine metabolism. In summary, there is growing evidence that creatine metabolism is up-regulated in uterine tissues during phases where energy demand is increased. While it remains unclear how important these adaptations are in the maintenance of healthy uterine function, furthering our understanding of uterine creatine metabolism may uncover strategies to combat poor embryo implantation and failure to conceive, as well as enhancing uterine contractile performance during labor.

Skeletal Muscle Mitochondrial Dysfunction Is Present in Patients with CKD before Initiation of Maintenance Hemodialysis

BACKGROUND AND OBJECTIVES

Patients with CKD suffer from frailty and sarcopenia, which is associated with higher morbidity and mortality. Skeletal muscle mitochondria are important for physical function and could be a target to prevent frailty and sarcopenia. In this study, we tested the hypothesis that mitochondrial dysfunction is associated with the severity of CKD. We also evaluated the interaction between mitochondrial function and coexisting comorbidities, such as impaired physical performance, intermuscular adipose tissue infiltration, inflammation, and oxidative stress.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Sixty-three participants were studied, including controls (n=21), patients with CKD not on maintenance hemodialysis (CKD 3-5; n=20), and patients on maintenance hemodialysis (n=22). We evaluated in vivo knee extensors mitochondrial function using ³¹P magnetic resonance spectroscopy to obtain the phosphocreatine recovery time constant, a measure of mitochondrial function. We measured physical performance using the 6-minute walk test, intermuscular adipose tissue infiltration with magnetic resonance imaging, and markers of inflammation and oxidative stress in plasma. In skeletal muscle biopsies from a select number of patients on maintenance hemodialysis, we also measured markers of mitochondrial dynamics (fusion and fission).

RESULTS

We found a prolonged phosphocreatine recovery constant in patients on maintenance hemodialysis (53.3 [43.4-70.1] seconds, median [interquartile range]) and patients with CKD not on maintenance hemodialysis (41.5 [35.4-49.1] seconds) compared with controls (38.9 [32.5-46.0] seconds; P=0.001 among groups). Mitochondrial dysfunction was associated with poor physical performance (r=0.62; P=0.001), greater intermuscular adipose tissue (r=0.44; P=0.001), and increased markers of inflammation and oxidative stress (r=0.60; P=0.001). We found mitochondrial fragmentation and increased content of dynamin-related protein 1, a marker of mitochondrial fission, in skeletal muscles from patients on maintenance hemodialysis (0.86 [0.48-1.35] arbitrary units (A.U.), median [interquartile range]) compared with controls (0.60 [0.24-0.75] A.U.).

CONCLUSIONS

Mitochondrial dysfunction is due to multifactorial etiologies and presents prior to the initiation of maintenance hemodialysis, including in patients with CKD stages 3-5.

A thermodynamic function of glycogen in brain and muscle

Brain and muscle glycogen are generally thought to function as local glucose reserves, for use during transient mismatches between glucose supply and demand. However, quantitative measures show that glucose supply is likely never rate-limiting for energy metabolism in either brain or muscle under physiological conditions. These tissues nevertheless do utilize glycogen during increased energy demand, despite the availability of free glucose, and despite the ATP cost of cycling glucose through glycogen polymer. This seemingly wasteful process can be explained by considering the effect of glycogenolysis on the amount of energy obtained from ATP (ΔG'_ATP). The amount of energy obtained from ATP is reduced by elevations in inorganic phosphate (Pi). Glycogen utilization sequesters Pi in the glycogen phosphorylase reaction and in downstream phosphorylated glycolytic intermediates, thereby buffering Pi elevations and maximizing energy yield at sites of rapid ATP consumption. This thermodynamic effect of glycogen may be particularly important in the narrow, spatially constrained astrocyte processes that ensheath neuronal synapses and in cells such as astrocytes and myocytes that release Pi from phosphocreatine during energy demand. The thermodynamic effect may also explain glycolytic super-compensation in brain when glycogen is not available, and aspects of exercise physiology in muscle glycogen phosphorylase deficiency (McArdle disease).

Protection of diabetes-induced kidney injury by phosphocreatine via the regulation of ERK/Nrf2/HO-1 signaling pathway

Diabetic nephropathy is the most common long-term complication of diabetes mellitus. The Methylglyoxal (MGO) production is mainly by metabolic pathways, such as lipolysis and glycolysis, its increases in the DM enhances oxidative stress and plays a crucial role in the diabetic nephrotic pathogenesis. Phosphocreatine (PCr) can improve lipopolysaccharide, ox-LDL-induced atherosclerosis, and alleviate vascular endothelial cell injury in diabetes. The aim of our present study is to examine the potential role of phosphocreatine (PCr) as a molecule protects against diabetes-induced Kidney Injury in-vitro and in-vivo through ERK/Nrf2/HO-1 signaling pathway. NRK-52E cells treatment with PCr obviously suppressed MGO-induced change of viability, apoptosis, coupled with decreased Bax/Bcl-2ratio, casapse-9 and caspase-3expressions. We determined the generation of reactive oxygen species (ROS) using membrane permeable fluorescent probe DCFH-DA as well as intracellular calcium by flow cytometry. ERK, Nrf2 and HO-1 expressions were determined by Western blot. PCr pretreatment significantly returned the oxidative stress enzymes to normal condition in-vitro and in-vivo. PCr pretreatment significantly reduced apoptosis, calcium and ROS production, induced by MGO, in NRK-52E cells. Moreover, pretreatment with PCr significantly inhibited cleaved caspase-3, cleaved caspase-9 and p-ERK expressions, while increased Nrf-2 and HO-1 expressions. Furthermore, PCr pretreatment significantly decreased p-ERK expression of MGO-induced injury in NRK-52E cells transfected with p-ERK cDNA. In conclusion, the renal protective effect of PCr in-vitro and in-vivo depends on suppressing apoptosis and ROS generation through ERK mediated Nrf-2/HO-1 pathway, suggesting that PCr may be a novel therapeutic candidate for the diabetic nephropathy treatment.

Lyn regulates creatine uptake in an imatinib-resistant CML cell line

BACKGROUND

Imatinib mesylate (imatinib) is the first-line treatment for newly diagnosed chronic myeloid leukemia (CML) due to its remarkable hematologic and cytogenetic responses. We previously demonstrated that the imatinib-resistant CML cells (Myl-R) contained elevated Lyn activity and intracellular creatine pools compared to imatinib-sensitive Myl cells.

METHODS

Stable isotope metabolic labeling, media creatine depletion, and Na⁺/K⁺-ATPase inhibitor experiments were performed to investigate the origin of creatine pools in Myl-R cells. Inhibition and shRNA knockdown were performed to investigate the specific role of Lyn in regulating the Na⁺/K⁺-ATPase and creatine uptake.

RESULTS

Inhibition of the Na⁺/K⁺-ATPase pump (ouabain, digitoxin), depletion of extracellular creatine or inhibition of Lyn kinase (ponatinib, dasatinib), demonstrated that enhanced creatine accumulation in Myl-R cells was dependent on uptake from the growth media. Creatine uptake was independent of the Na⁺/creatine symporter (SLC6A8) expression or de novo synthesis. Western blot analyses showed that phosphorylation of the Na⁺/K⁺-ATPase on Tyr 10 (Y10), a known regulatory phosphorylation site, correlated with Lyn activity. Overexpression of Lyn in HEK293 cells increased Y10 phosphorylation (pY10) of the Na⁺/K⁺-ATPase, whereas Lyn inhibition or shRNA knockdown reduced Na⁺/K⁺-ATPase pY10 and decreased creatine accumulation in Myl-R cells. Consistent with enhanced uptake in Myl-R cells, cyclocreatine (Ccr), a cytotoxic creatine analog, caused significant loss of viability in Myl-R compared to Myl cells.

CONCLUSIONS

These data suggest that Lyn can affect creatine uptake through Lyn-dependent phosphorylation and regulation of the Na⁺/K⁺-ATPase pump activity.

GENERAL SIGNIFICANCE

These studies identify kinase regulation of the Na⁺/K⁺-ATPase as pivotal in regulating creatine uptake and energy metabolism in cells.

Pharmacokinetics and hemorheology of phosphocreatine and creatine in rabbits: A directly comparative study between parent drug and active metabolite

This study is to investigate pharmacokinetics (PK) and hemorheology (HR) of exogenous phosphocreatine (PCr), a cardio-protective agent, and its active metabolite creatine (Cr), with particular focus on the PK and PD comparison between PCr and Cr. A specific ion-pair reversed-phase HPLC-UV assay was used to simultaneously measure PCr, Cr and ATP concentrations in plasma and red blood cells (RBC) samples of rabbits. PK and HR parameters were calculated based on concentration-time (C-T) curves and effect-time (E-T) curves, respectively, obtained after i.v. dosing. Meanwhile the apparent pharmacological activity ratio (R_app) and real pharmacological activity ratio (R_real) of Cr to PCr were calculated. The PCr disappeared from plasma rapidly and in a biphasic manner; plasma PCr was converted to Cr fast and largely with the elimination rate limited metabolite disposition in vivo (K_m < K). The i.v. administration of PCr led to a markedly elevated and long-lasting ATP level in RBC. After i.v. administration of preformed Cr, plasma Cr displayed similar elimination kinetics behaviors to that of Cr generated metabolically after i.v. PCr. The Cr could also raise ATP level in RBC, but to less extent than PCr. Approximately 43% of PCr-derived ATP came from Cr-derived ATP in RBC. PCr could significantly reduce whole blood viscosity and RBC osmotic fragility and Cr could do so, but weakly with estimated R_app of 0.53-0.68 and R_real of 0.38-0.48. PCr also inhibited platelet aggregation significantly, as opposed to Cr. The PCr-caused improvement of HR is related to the rise in ATP level in RBC. Cr is likely to partially mediate HR effect of PCr.

Control of invasive sea lampreys using the piscicides TFM and niclosamide: Toxicology, successes & future prospects

The invasion of the Laurentian Great Lakes of North America by sea lampreys (Petromyzon marinus) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10% of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys and in non-target animals, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, also likely works by uncoupling oxidative phosphorylation, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible "next-generation" strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.

Intravenous administration of adenosine triphosphate and phosphocreatine combined with fluoxetine in major depressive disorder: protocol for a randomized, double-blind, placebo-controlled pilot study

BACKGROUND

Major depressive disorder (MDD) is a common psychiatric disorder. With systematic antidepressant treatment, 50-75% of patients have a treatment response but require 4-6 weeks to have their symptoms alleviated. Therefore, researchers anticipate the development of novel fast-acting antidepressants. Previous studies have revealed that the decrease of bio-energetic metabolism may contribute to the occurrence of depression, while our team has found adenosine triphosphate (ATP) and phosphocreatine (PCr) to be fast-acting antidepressants in the depressed-animal model. ATP and PCr have already been widely prescribed clinically as energy supplements for cells. This will be the first clinical attempt of the intravenous administration of ATP and PCr combined with orally administered fluoxetine in MDD.

METHODS

This is a single-center, randomized, double-blind, placebo-controlled pilot study. A total of 42 patients will be divided randomly into three groups. Patients will receive an intravenous administration of ATP or PCr or saline twice daily combined with orally administered fluoxetine (20 mg/day) for the first 2 weeks and fluoxetine monotherapy for the following 4 weeks. Follow-up assessment will be completed at week 10. Feasibility outcomes will include percentages of patient eligibility, intention to use medication, willingness to participate, drug adherence, completion of the scheduled assessment, retention, drop-out, etc. Physical examination results, Side Effect Rating Scale, adverse events, results from blood tests, electroencephalogram, and electrocardiograph will be recorded for safety evaluation of the augmentation therapy. The trends of efficacy will be evaluated by the reduction rate of the Hamilton Depression Rating Scale, the mean change of the Clinical Global Impression Scale, and the Patients Health Questionaire-9 items.

DISCUSSION

In our study, ATP and PCr will be given by intravenous infusion. Thus patients will be hospitalized for the initial 2 weeks for safety concern. Hospitalization will be an impact factor for the recruitment, participation, drop-out, efficacy, results, etc. The evaluation of our feasibility outcomes, study setting, safety of augmentation therapy and possible efficacy trends among groups, will facilitate a full-scale trial design and sample size calculation.

TRIAL REGISTRATION

NCT03138681 . Registered on 3 May 2017. First patient: 4 May 2017.

Targeting phosphocreatine metabolism in relapsing-remitting multiple sclerosis: evaluation with brain MRI, 1H and 31P MRS, and clinical and cognitive testing

BACKGROUND/OBJECTIVES

Fluoxetine and prucalopride might change phosphocreatine (PCr) levels via the cAMP-PKA pathway, an interesting target in the neurodegenerative mechanisms of MS.

METHODS

We conducted a two-center double-blind, placebo-controlled, randomized trial including 48 relapsing-remitting MS patients. Patients were randomized to receive placebo (n = 13), fluoxetine (n = 15), or prucalopride (n = 14) for 6 weeks. Proton (¹H) and phosphorus (³¹P) magnetic resonance spectroscopy (MRS) as well as volumetric and perfusion MR imaging were performed at weeks 0, 2, and 6. Clinical and cognitive testing were evaluated at weeks 0 and 6.

RESULTS

No significant changes were observed for both ³¹P and ¹H MRS indices. We found a significant effect on white matter volume and a trend towards an increase in grey matter and whole brain volume in the fluoxetine group at week 2; however, these effects were not sustained at week 6 for white matter and whole brain volume. Fluoxetine and prucalopride showed a positive effect on 9-HPT, depression, and fatigue scores.

CONCLUSION

Both fluoxetine and prucalopride had a symptomatic effect on upper limb function, fatigue, and depression, but this should be interpreted with caution. No effect of treatment was found on ³¹P and ¹H MRS parameters, suggesting that these molecules do not influence the PCr metabolism.

Neuroprotective effect of phosphocreatine on oxidative stress and mitochondrial dysfunction induced apoptosis in vitro and in vivo: Involvement of dual PI3K/Akt and Nrf2/HO-1 pathways

Methylglyoxal (MGO), an active metabolite of glucose, is observed in high levels in the tissues and blood of diabetic patients. Phosphocreatine (PCr), a high-energy phosphate compound, exhibits a range of pharmacological actions but little is well known of its neuroprotective action. The aim of the present study was to investigate the neuroprotective effects and the possible mechanisms of PCr. Diabetes is closely associated with neurodegenerative diseases, leading not only to the peripheral nervous system (PNS) and but also to central nervous system (CNS) damage. Therefore, we established two rat models of diabetes in vivo induced by MGO and streptozocin (STZ) respectively, while utilized differentiated PC-12 cells in vitro. Treatment of PC-12 cells with PCr markedly attenuated MGO-induced change of viability, apoptosis, accompanied by decreased levels of caspase-3, casapse-9 and Bcl-2/Bax protein ratio. Determination of cellular respiratory function was performed with intact PC-12 cells and homogenized hippocampal neuron tissue of rat. Reactive oxygen species (ROS) generation was assessed by membrane permeable fluorescent probe DCFH-DA. The expressions of Akt, Nrf2 and HO-1 were examined by Western blot. PCr pretreatment significantly reduced oxidative stress-induced high LDH, MDA level, and ROS production of PC-12 cells. PCr pretreatment also significantly decreased mitochondrial dysfunction in vitro and in vivo. In addition, PCr pretreatment increased the expression of p-Akt, Nrf2 and HO-1, and reduced the apoptosis. Moreover, the expression of Cleaved caspase3 was partially increased and the p-Akt, Nrf2 and HO-1 was partially reduced by a PI3K inhibitor (LY294002). While, compared with LY294002 groups, pre-treatment with PCr at the concentrations of 20 mM significantly reduced the expression of Cleaved caspase3 and increased the expression of p-Akt, Nrf2 and HO-1. Molecular docking assay showed that PCr possessed powerful affinity towards to Akt with lower binding energy. In conclusion, the neuroprotective effects of PCr in vitro and in vivo rely on normalizing mitochondrial function and reducing oxidative stress via Akt mediated Nrf2/HO-1 pathway, suggesting that PCr may be a novel therapeutic candidate for the treatment of diabetes-associated neurodegenerative diseases.

Effects of dietary-induced alterations in rat brain docosahexaenoic acid accrual on phospholipid metabolism and mitochondrial bioenergetics: An in vivo31P MRS study

Evidence from ³¹P magnetic resonance spectroscopy (³¹P MRS) studies suggest that different psychiatric disorders, which typically emerge during adolescence and young adulthood, are associated with abnormalities in mitochondrial bioenergetics and membrane phospholipid metabolism. These disorders are also associated with deficits in omega-3 polyunsaturated fatty acids (n-3 PUFA), including docosahexaenoic acid (DHA) which accumulates in mitochondrial and synaptic membranes. The present study investigated the effects of dietary-induced alterations in brain DHA accrual during adolescence on phospholipid metabolism and bioenergetics in the adult rat brain using ³¹P MRS. During the peri-adolescent period (P21-P90), male rats were fed a diet with no n-3 fatty acids (Deficient, DEF, n = 20), a diet fortified with preformed DHA (fish oil, FO, n = 20), or a control diet fortified with alpha-linolenic acid (18:3n-3, n = 20). On P90, ³¹P MRS was performed under isoflurane anesthetic using a 7 T Bruker Biospec system. Compared with controls, brain DHA levels were significantly lower in adult rats fed the DEF diet (-17%, p ≤ 0.0001) and significantly higher in rats fed the FO diet (+14%, p ≤ 0.0001). There were no significant group differences for indices of bioenergetics, including adenosine triphosphate and phosphocreatine levels, or indices of membrane phospholipid metabolism including phosphomonoesters and phosphodiesters. Therefore, the present ³¹P MRS data suggest that rat brain DHA levels are not a significant predictor of mitochondrial bioenergetics or membrane phospholipid metabolism.

The influence of high fat diets with different ketogenic ratios on the hippocampal accumulation of creatine - FTIR microspectroscopy study

The main purpose of this study was the determination and comparison of anomalies in creatine (Cr) accumulation occurring within CA3 and DG areas of hippocampal formation as a result of two high-fat, carbohydrate-restricted ketogenic diets (KD) with different ketogenic ratio (KR). To reach this goal, Fourier transformed infrared microspectroscopy with synchrotron radiation source (SRFTIR microspectroscopy) was applied for chemical mapping of creatine absorption bands, occurring around 1304, 1398 and 2800 cm^-1. The samples were taken from three groups of experimental animals: control group (N) fed with standard laboratory diet, KD1 and KD2 groups fed with high-fat diets with KR 5:1 and 9:1 respectively. Additionally, the possible influence on the phosphocreatine (PhCr, the high energetic form of creatine) content was evaluated by comparative analysis of chemical maps obtained for creatine and for compounds containing phosphate groups which manifest in the spectra at the wavenumbers of around 1240 and 1080 cm^-1. Our results showed that KD2 strongly modifies the frequency of Cr inclusions in both analyzed hippocampal areas. Statistical analysis, performed with Mann-Whitney U test revealed increased accumulation of Cr within CA3 and DG areas of KD2 fed rats compared to both normal rats and KD1 experimental group. Moreover, KD2 diet may modify the frequency of PhCr deposits as well as the PhCr to Cr ratio.

Adenosine Triphosphate Metabolism Measured by Phosphorus Magnetic Resonance Spectroscopy: A Potential Biomarker for Multiple Sclerosis Severity

BACKGROUND/AIMS

Phosphorus magnetic resonance spectroscopy (31P-MRS) has previously shown abnormal changes in energy metabolites in the brain of multiple sclerosis (MS) patients. However, the relationship between these energy metabolites - particularly adenosine triphosphate (ATP) - and the disease severity remains unclear. The objective of this study was to determine whether measuring ATP metabolites can help to predict disease severity in MS patients.

METHODS

31P-MRS at 3 tesla was performed in 9 relapsing remitting (RRMS), 9 secondary progressive MS patients (SPMS), and 10 age-matched healthy controls. ATP metabolites (expressed as %) in normally appearing white matter of the centrum semiovale were compared between patients and healthy controls. The relationship between Expanded Disability Status Scale (EDSS) and ATP metabolites was evaluated.

RESULTS

RRMS and SPMS patients had higher phosphocreatine (PCr) and lower phosphodiesters than healthy controls. In addition, RRMS patients had higher β-ATP% than SPMS patients. β-ATP% was negatively correlated with EDSS in all patients.

CONCLUSION

Our findings suggest a defective PCr metabolism in both patient groups, and a higher state of energy production in RRMS that might reflect a compensatory mechanism in face of the increased needs. The correlation of β-ATP with EDSS makes it a candidate biomarker for assessing MS disease severity.

Creatine biosynthesis and transport by the term human placenta

INTRODUCTION

Creatine is an amino acid derivative that is involved in preserving ATP homeostasis. Previous studies suggest an important role for the creatine kinase circuit for placental ATP turnover. Creatine is obtained from both the diet and endogenous synthesis, usually along the renal-hepatic axis. However, some tissues with a high-energy demand have an inherent capacity to synthesise creatine. In this study, we determined if the term human placenta has the enzymatic machinary to synthesise creatine.

METHODS

Eleven placentae were collected following elective term caesarean section. Samples from the 4 quadrants of each placenta were either fixed in formalin or frozen. qPCR was used to determine the mRNA expression of the creatine synthesising enzymes arginine:glycine amidinotransferase (AGAT) and guanidinoacetate methyltransferase (GAMT), and the creatine transporter (SLC6A8). Protein expression of AGAT and GAMT was quantified by Western blot, and observations of cell localisation of AGAT, GAMT and SLC6A8 made with immunohistochemistry. Synthesis of guanidinoacetate (GAA; creatine precursor) and creatine in placental homogenates was determined via GC-MS and HPLC, respectively.

RESULTS

AGAT, GAMT and SLC6A8 mRNA and protein were detected in the human placenta. AGAT staining was identified in stromal and endothelial cells of the fetal capillaries. GAMT and SLC6A8 staining was localised to the syncytiotrophoblast of the fetal villi. Ex vivo, tissue homogenates produce both GAA (4.6 nmol mg protein^-1h^-1) and creatine (52.8 nmol mg protein^-1h^-1).

DISCUSSION

The term human placenta has the capacity to synthesise creatine. These data present a new understanding of placental energy metabolism.

Phosphocreatine protects against LPS-induced human umbilical vein endothelial cell apoptosis by regulating mitochondrial oxidative phosphorylation

Phosphocreatine (PCr) is an exogenous energy substance, which provides phosphate groups for adenosine triphosphate (ATP) cycle and promotes energy metabolism in cells. However, it is still unclear whether PCr has influenced on mitochondrial energy metabolism as well as oxidative phosphorylation (OXPHO) in previous studies. Therefore, the aim of the present study was to investigate the regulation of PCr on lipopolsaccharide (LPS)-induced human umbilical vein endothelial cells (HUVECs) and mitochondrial OXPHO pathway. PCr protected HUVECs against LPS-induced apoptosis by suppressing the mitochondrial permeability transition, cytosolic release of cytochrome c (Cyt C), Ca(2+), reactive oxygen species and subsequent activation of caspases, and increasing Bcl2 expression, while suppressing Bax expression. More importantly, PCr significantly improved mitochondrial swelling and membrane potential, enhanced the activities of ATP synthase and mitochondrial creatine kinase (CKmt) in creatine shuttle, influenced on respiratory chain enzymes, respiratory control ratio, phosphorus/oxygen ratio and ATP production of OXPHO. Above PCr-mediated mitochondrial events were effectively more favorable to reduced form of flavin adenine dinucleotide (FADH2) pathway than reduced form of nicotinamide-adenine dinucleotid pathway in the mitochondrial respiratory chain. Our results revealed that PCr protects against LPS-induced HUVECs apoptosis, which probably related to stabilization of intracellular energy metabolism, especially for FADH2 pathway in mitochondrial respiratory chain, ATP synthase and CKmt. Our findings suggest that PCr may play a certain role in the treatment of atherosclerosis via protecting endothelial cell function.

Phosphocreatine protects endothelial cells from Methylglyoxal induced oxidative stress and apoptosis via the regulation of PI3K/Akt/eNOS and NF-κB pathway

Methylglyoxal (MGO), an active metabolite of glucose, can cause cellular injury which has an affinity for the progression of diabetes-associated atherosclerosis. Phosphocreatine (PCr) is a well-known high-energy phosphate compound. However, its protective effects and mechanism in the formation of a diabetes-associated atherosclerosis have not been clarified. In the present study, we investigated whether PCr could prevent MGO-induced apoptosis in human umbilical vascular endothelial cells (HUVECs) and explored the possible mechanisms. Cells were pre-treated with PCr and then stimulated with MGO. Cell morphology, cytotoxicity and apoptosis were assessed by light microscopy, MTT assay, and Annexin V-FITC respectively. Apoptotic-related proteins were evaluated by Western blotting. Reactive oxygen species (ROS) generation, intracellular calcium and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Our results showed that PCr dose-dependently prevented MGO associated HUVEC cytotoxicity and suppressed MGO activated ROS generation as well as apoptotic biochemical changes such as lactate dehydrogenase, malondialdehyde leakage, loss of MMP, decreased Bcl-2/Bax protein ratio, levels of caspase-3 and 9. In addition, the antiapoptotic effect of PCr enhanced p-Akt/Akt protein ratio, NO synthase (eNOS) activation, NO production and cGMP levels and also was partially suppressed by a PI3K inhibitor (LY294002). Furthermore, PCr also inhibited MGO-induced transcriptional activity of Nuclear factor kappa B (NFκB). In conclusion, our data described that PCr exerts an antiapoptotic effect in HUVECs exposed to oxidative stress by MGO through the mitochondrial pathway and the modulation of PI3K/Akt/eNOS and NF-κB signaling pathway. Thus, it might be a candidate therapeutic agent for diabetic-associated cardiovascular diseases.

Creatine kinase in ischemic and inflammatory disorders

The creatine/phosphocreatine pathway plays a conserved and central role in energy metabolism. Compartmentalization of specific creatine kinase enzymes permits buffering of local high energy phosphates in a thermodynamically favorable manner, enabling both rapid energy storage and energy transfer within the cell. Augmentation of this metabolic pathway by nutritional creatine supplementation has been shown to elicit beneficial effects in a number of diverse pathologies, particularly those that incur tissue ischemia, hypoxia or oxidative stress. In these settings, creatine and phosphocreatine prevent depletion of intracellular ATP and internal acidification, enhance post-ischemic recovery of protein synthesis and promote free radical scavenging and stabilization of cellular membranes. The creatine kinase energy system is itself further regulated by hypoxic signaling, highlighting the existence of endogenous mechanisms in mammals that can enhance creatine metabolism during oxygen deprivation to promote tissue resolution and homeostasis. Here, we review recent insights into the creatine kinase pathway, and provide rationale for dietary creatine supplementation in human ischemic and inflammatory pathologies.

Cardiac protection with phosphocreatine: a meta-analysis

Phosphocreatine (PCr) plays an important role in the energy metabolism of the heart and a decrease in its intracellular concentration results in alteration of myocardium energetics and work. We conducted a meta-analysis of all randomized and matched trials that compared PCr with placebo or standard treatment in patients with coronary artery disease or chronic heart failure or in those undergoing cardiac surgery. We systematically searched PubMed/Medline, Embase, Cochrane Central Register of Controlled Trials and Google Scholar up to 1 November 2015, for pertinent trials. The primary outcome was all-cause mortality. Secondary outcomes included inotrope use, ejection fraction (EF), peak creatinine kinase-myocardial band (CK-MB) release and the incidence of major arrhythmias, as well as spontaneous recovery of the heart performance in the subgroup of patients undergoing cardiac surgery with cardiopulmonary bypass. We pooled odds ratio (OR) and mean difference (MD) using fixed- and random effects models. We identified 41 controlled trials, of them 32 were randomized. Patients receiving PCr had lower all-cause mortality when compared with the control group [61/1731 (3.5%) vs 177/1667 (10.6%); OR: 0.71, 95% CI: 0.51-0.99; P = 0.04; I(2) = 0%; with 3400 patients and 22 trials included]. Phosphocreatine administration was associated with higher LVEF (MD: 3.82, 95% CI: 1.18-6.46; P = 0.005; I(2) = 98%), lower peak CK-MB release (MD: -6.08, 95% CI: -8.01, -4.15; P < 0.001; I(2) = 97%), lower rate of major arrhythmias (OR: 0.42; 95% CI: 0.27-0.66; P < 0.001; I(2) = 0%), lower incidence of inotropic support (OR: 0.39, 95% CI: 0.25-0.61; P < 0.001; I(2) = 56%) and a higher level of spontaneous recovery of the heart performance after cardiopulmonary bypass (OR: 3.49, 95% CI: 2.28-5.35; P < 0.001; I(2) = 49%) when compared with the control group. In a mixed population of patients with coronary artery disease, chronic heart failure or in those undergoing cardiac surgery, PCr may reduce all-cause short-term mortality. In addition, PCr administration was associated with improved cardiac outcomes. Owing to the pharmacological plausibility of this effect and to the concordance of the beneficial effects of PCr on several secondary but important outcomes and survival, there is urgent need for a large multicentre randomized trial to confirm these findings.

Creatine ingestion augments dietary carbohydrate mediated muscle glycogen supercompensation during the initial 24 h of recovery following prolonged exhaustive exercise in humans

Muscle glycogen availability can limit endurance exercise performance. We previously demonstrated 5 days of creatine (Cr) and carbohydrate (CHO) ingestion augmented post-exercise muscle glycogen storage compared to CHO feeding alone in healthy volunteers. Here, we aimed to characterise the time-course of this Cr-induced response under more stringent and controlled experimental conditions and identify potential mechanisms underpinning this phenomenon. Fourteen healthy, male volunteers cycled to exhaustion at 70 % VO_2peak. Muscle biopsies were obtained at rest immediately post-exercise and after 1, 3 and 6 days of recovery, during which Cr or placebo supplements (20 g day⁻¹) were ingested along with a prescribed high CHO diet (37.5 kcal kg body mass⁻¹ day⁻¹, >80 % calories CHO). Oral-glucose tolerance tests (oral-GTT) were performed pre-exercise and after 1, 3 and 6 days of Cr and placebo supplementation. Exercise depleted muscle glycogen content to the same extent in both treatment groups. Creatine supplementation increased muscle total-Cr, free-Cr and phosphocreatine (PCr) content above placebo following 1, 3 and 6 days of supplementation (all P < 0.05). Creatine supplementation also increased muscle glycogen content noticeably above placebo after 1 day of supplementation (P < 0.05), which was sustained thereafter. This study confirmed dietary Cr augments post-exercise muscle glycogen super-compensation, and demonstrates this occurred during the initial 24 h of post-exercise recovery (when muscle total-Cr had increased by <10 %). This marked response ensued without apparent treatment differences in muscle insulin sensitivity (oral-GTT, muscle GLUT4 mRNA), osmotic stress (muscle c-fos and HSP72 mRNA) or muscle cell volume (muscle water content) responses, such that another mechanism must be causative.

Creatine target engagement with brain bioenergetics: a dose-ranging phosphorus-31 magnetic resonance spectroscopy study of adolescent females with SSRI-resistant depression

Major depressive disorder (MDD) often begins during adolescence and is projected to become the leading cause of global disease burden by the year 2030. Yet, approximately 40 % of depressed adolescents fail to respond to standard antidepressant treatment with a selective serotonin reuptake inhibitor (SSRI). Converging evidence suggests that depression is related to brain mitochondrial dysfunction. Our previous studies of MDD in adult and adolescent females suggest that augmentation of SSRI pharmacotherapy with creatine monohydrate (CM) may improve MDD outcomes. Neuroimaging with phosphorus-31 magnetic resonance spectroscopy (³¹P-MRS) can measure the high-energy phosphorus metabolites in vivo that reflect mitochondrial function. These include phosphocreatine (PCr), a substrate for the creatine kinase reaction that produces adenosine triphosphate. As part of the National Institute of Mental Health’s experimental medicine initiative, we conducted a placebo-controlled dose-ranging study of adjunctive CM for adolescent females with SSRI-resistant MDD. Participants were randomized to receive placebo or CM 2, 4 or 10 g daily for 8 weeks. Pre- and post-treatment ³¹P-MRS scans were used to measure frontal lobe PCr, to assess CM’s target engagement with cerebral energy metabolism. Mean frontal lobe PCr increased by 4.6, 4.1 and 9.1 % in the 2, 4 and 10 g groups, respectively; in the placebo group, PCr fell by 0.7 %. There was no group difference in adverse events, weight gain or serum creatinine. Regression analysis of PCr and depression scores across the entire sample showed that frontal lobe PCr was inversely correlated with depression scores (p = 0.02). These results suggest that CM achieves target engagement with brain bioenergetics and that the target is correlated with a clinical signal. Further study of CM as a treatment for adolescent females with SSRI-resistant MDD is warranted.

Phosphorus magnetic resonance spectroscopy studies in schizophrenia

Phosphorus magnetic resonance spectroscopy ((31)P MRS) allows in vivo quantification of phosphorus metabolites that are considered to be related to membrane turnover and energy metabolism. In schizophrenia (SZ), (31)P MRS studies found several abnormalities in different brain regions suggesting that alterations in these pathways may be contributing to the pathophysiology. In this paper, we systematically reviewed the (31)P MRS studies in SZ published to date by taking patient characteristics, medication status and brain regions into account. Publications written in English were searched on http://www.ncbi.nlm.nih.gov/pubmed/, by using the keywords 'phosphomonoester', 'phosphodiester', 'ATP', 'phosphocreatine', 'phosphocholine', 'phosphoethanolamine','glycerophosphocholine', 'glycerophosphoethanolamine', 'pH', 'schizophrenia', and 'MRS'. Studies that measured (31)P metabolites in SZ patients were included. This search identified 52 studies. Reduced PME and elevated PDE reported in earlier studies were not replicated in several subsequent studies. One relatively consistent pattern was a decrease in PDE in chronic patients in the subcortical structures. There were no consistent patterns for the comparison of energy related phosphorus metabolites between patients and controls. Also, no consistent pattern emerged in studies seeking relationship between (31)P metabolites and antipsychotic use and other clinical variables. Despite emerging patterns, methodological heterogeneities and shortcomings in this literature likely obscure consistent patterns among studies. We conclude with recommendations to improve study designs and (31)P MRS methods in future studies. We also stress the significance of probing into the dynamic changes in energy metabolism, as this approach reveals abnormalities that are not visible to steady-state measurements.

Intramuscular phosphagen status and the relationship to muscle performance across the age spectrum

PURPOSE

To examine age-related differences in intramuscular concentrations of adenosine triphosphate (ATP), free creatine (FCr), phosphocreatine (PCr) and total creatine (TCr) and if these differences were related to muscle performance.

METHODS

Forty-two healthy, non-sedentary, males between 20 and 76 years provided muscle samples to determine [ATP], [FCr], [PCr], and [TCr]. Maximal strength and endurance were assessed and correlated with intramuscular variables.

RESULTS

Intramuscular [ATP] decreased by 13.5% (p = 0.013) in the older cohort (18.0 ± 0.6 mmol/kg dry wt) vs. the young cohort (20.8 ± 0.9 mmol/kg dry wt) and was significantly correlated to age (r = -0.38, p = 0.008). No other differences were observed between age groups for intramuscular [PCr], [FCr], [TCr], or [PCr]:[TCr] (p > 0.05). The older cohort consumed significantly less (p < 0.05) dietary protein when compared to the young cohort. Bivariate correlations were found for intramuscular [ATP] and lower body 1RM (r = 0.24, p = 0.066), leg press volume and free creatine (r = 0.325, p = 0.036) and leg press repetitions and free creatine (r = 0.373, p = 0.015). Partial correlations controlling for age eliminated the relationship between [ATP] and 1RM while intramuscular free creatine and leg press repetitions remained significant (p < 0.05) and leg press volume approached significance (p = 0.095).

CONCLUSION

These results expand upon previous observations indicative of age-related reductions in intramuscular [ATP] and dietary protein intake. The lack of change in other intramuscular PCr system markers are suggestive of dysfunctions at the mitochondrial level while the impact of neuromuscular changes, lean mass cross-sectional area and differences in physical activity are also important.

Creatine as a booster for human brain function. How might it work?

Creatine, a naturally occurring nitrogenous organic acid found in animal tissues, has been found to play key roles in the brain including buffering energy supply, improving mitochondrial efficiency, directly acting as an anti-oxidant and acting as a neuroprotectant. Much of the evidence for these roles has been established in vitro or in pre-clinical studies. Here, we examine the roles of creatine and explore the current status of translation of this research into use in humans and the clinic. Some further possibilities for use of creatine in humans are also discussed.

Localized semi-LASER dynamic (31)P magnetic resonance spectroscopy of the soleus during and following exercise at 7 T

OBJECTIVES

This study demonstrates the applicability of semi-LASER localized dynamic (31)P MRS to deeper lying areas of the exercising human soleus muscle (SOL). The effect of accurate localization and high temporal resolution on data specificity is investigated.

MATERIALS AND METHODS

To achieve high signal-to-noise ratio (SNR) at a temporal resolution of 6 s, a custom-built human calf coil array was used at 7T. The kinetics of phosphocreatine (PCr) and intracellular pH were quantified separately in SOL and gastrocnemius medialis (GM) muscle of nine volunteers, during rest, plantar flexion exercise, and recovery.

RESULTS

The average SNR of PCr at rest was [Formula: see text] in SOL ([Formula: see text] in GM). End exercise PCr depletion in SOL ([Formula: see text] %) was far lower than in GM ([Formula: see text] %). The pH in SOL increased rapidly and, in contrast to GM, remained elevated until the end of exercise.

CONCLUSION

(31)P MRS in single-shots every 6 s localized in the deeper-lying SOL enabled quantification of PCr recovery times at low depletions and of fast pH changes, like the initial rise. Both high temporal resolution and accurate spatial localization improve specificity of Pi and, thus, pH quantification by avoiding multiple, and potentially indistinguishable sources for changing the Pi peak shape.

Protective effects of phosphocreatine administered post-treatment combined with ischemic post-conditioning on rat hearts with myocardial ischemia/reperfusion injury

Background

The aim of the study was to investigate the effects of phosphocreatine (PCr) post-treatment combined with ischemic post-conditioning on myocardial ischemia/reperfusion (I/R) injury in a rat model.

Methods

Forty Sprague-Dawley rats that had undergone 30 minutes ischemia and 120 minutes reperfusion were randomly divided into four groups (n = 10 in each group): the I/R group, the ischemia post-conditioning (IPost) group, the PCr group, and the IPost + PCr group. The activities of serum creatine kinase (CK), myeloperoxidase (MPO), and lactate dehydrogenase (LDH) were measured after 120 minutes of reperfusion. At the end of the experiment, serum levels of nuclear factor (NF)-κB and tumor necrosis factor (TNF)-α were detected, myocardial infarct size (IS) was measured by triphenyltetrazolium chloride staining, and myocardial expression of Bcl-2 and phosphorylated Akt (p-Akt) was determined by western blot.

Results

The IPost, PCr, and PCr + IPost groups had significantly lower IS than the I/R group (P < 0.05). The reductions in CK, LDH, and MPO release were consistent with the decrease in the myocardial IS (P < 0.05). Serum concentrations of TNF-α and NF-κB in the IPost, PCr, and PCr + IPost groups were significantly lower than those in the I/R group (P < 0.05). The levels of p-Akt and Bcl-2 in the IPost, PCr, and PCr + IPost groups were greater than those in the I/R group (P < 0.05). CK, LDH, MPO, NF-κB, TNF-α, p-Akt, Bcl-2 and IS were further enhanced in the IPost + PCr group (P < 0.05).

Conclusions

Post-treatment with PCr enhanced the protective effect of IPost on rat myocardium affected by I/R injury, possibly by inhibiting the inflammatory response and activating the phosphatidylinositol 3-kinase (PI-3K)/Akt/Bcl-2 signaling pathway.

Effect of exogenous phosphocreatine on cardiomycytic apoptosis and expression of Bcl-2 and Bax after cardiopulmonary resuscitation in rats

BACKGROUND

Ischemia-reperfusion injury in the myocardium after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) is an important pathologic basis of post-cardiac arrest of syndrome (PCAS), and apoptosis is one of the major mechanisms in myocardial ischemia-reperfusion injury. To lessen myocardial ischemia-reperfusion injury after cardiac arrest and CPR, it is important to reduce energy consumption and to increase energy supply in the myocardium. This study aimed to observe changes of cell apoptosis and expression of Bcl-2 and Bax protein on the myocardium after CPR in rats, and the protective effects of different doses of exogenous phosphocreatine (creatine phosphate, CP) on them.

METHODS

A total of 32 male adult Sprague-Dawley rats were randomly divided into 4 groups: control group (group A), CPR group (group B), low-dose CP group (group C, CP 0.5 g/kg at beginning of CPR and 1.0 g/kg at 2 hours after CPR) and high-dose CP group (group D, CP 1.0 g/kg at beginning of CPR and 2.0 g/kg at 2 hours after CPR). Cardiac arrest was induced by asphyxiation and CPR started at 7 minutes after asphyxiation in groups B, C and D. Myocardium samples were taken at 24 hours after CPR. Cardiomycytic apoptosis was detected by the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method. The expression of Bcl-2 and Bax protein was measured by immunohistochemistry.

RESULTS

Cardiomyocytic apoptosis index (AI) and expression of Bcl-2 and Bax protein increased more significantly in groups B, C and D than in group A (P<0.01), but Bcl-2/Bax ratio significantly decreased (P<0.01). Cardiomyocytic AI and expression of Bcl-2 and Bax protein decreased more significantly in groups C and D than in group B (P<0.01), but Bcl-2/Bax ratio increased more significantly (P<0.01). Cardiomyocytic AI and expression of Bcl-2 and Bax protein decreased more significantly in group D than in group C (P<0.05), but Bcl-2/Bax ratio increased more significantly (P<0.05).

CONCLUSION

Exogenous phosphocreatine, especially at a large dose, could inhibit cardiomyocytic apoptosis and alleviate myocardial injury after CPR in rats.

Pharmacokinetics of phosphocreatine and its active metabolite creatine in the mouse plasma and myocardium

BACKGROUND

The pharmacokinetic (PK) studies of phosphocreatine (PCr) and its active metabolite creatine (Cr) are considerably lacking. This study is to comparatively investigate the PK profiles of PCr and Cr in mice plasma and myocardium as well as the ATP level.

METHODS

After iv administration of equimolar PCr and preformed Cr to healthy and Pit-induced myocardial ischemic mice, plasma and myocardium samples were analyzed for exogenous PCr, Cr and related ATP concentrations using a specific ion-pair reversed-phase HPLC-UV assay.

RESULTS

The plasma C-T data of iv PCr and Cr were well fitted to two-compartment model. Following iv PCr, Cr appeared in plasma as early as 1.0 min postdose with a longer t1/2 than PCr and had a fm of 72%. The mice dosed iv PCr preceded 5 min by ip Pit 30 U/kg showed longer t1/2β PCr and t1/2 Cr in plasma and elevated Cmax, Cr and Cmax, ATP in myocardium compared with mice dosed iv PCr alone, and it was estimated that about 40% ATP produced by iv PCr was from Cr.

CONCLUSION

The PCr in plasma is converted to Cr rapidly and mostly, and shows an elimination rate limited (ERL) metabolite disposition. Iv PCr caused a significantly elevated and long-lasing myocardial ATP and Cr levels. The Pit-induced myocardial ischemia brings slower elimination of PCr and Cr and higher peak concentrations of Cr and ATP in myocardium. The metabolite Cr at least partially mediates PCr-caused rise in myocardial ATP level and also possibly the cardio-protective effects of PCr.

The effects of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) on fuel stores and ion balance in a non-target fish, the rainbow trout (Oncorhynchus mykiss)

The pesticide 3-trifluoromethyl-4-nitrophenol (TFM) is used to control sea lamprey (Petromyzon marinus) populations in the Great Lakes through its application to nursery streams containing larval sea lampreys. TFM uncouples oxidative phosphorylation, impairing mitochondrial ATP production in sea lampreys and rainbow trout (Oncorhynchus mykiss). However, little else is known about its sub-lethal effects on non-target aquatic species. The present study tested the hypotheses that TFM exposure in hard water leads to (i) marked depletion of energy stores in metabolically active tissues (brain, muscle, kidney, liver) and (ii) disruption of active ion transport across the gill, adversely affecting electrolyte homeostasis in trout. Exposure of trout to 11.0mgl(-1) TFM (12-h LC50) led to increases in muscle TFM and TFM-glucuronide concentrations, peaking at 9h and 12h, respectively. Muscle and brain glycogen was reduced by 50%, while kidney and muscle lactate increased with TFM exposure. Kidney ATP and phosphocreatine decreased by 50% and 70%, respectively. TFM exposure caused no changes in whole body ion (Na(+), Cl(-), Ca(2+), K(+)) concentrations, gill Na(+)/K(+) ATPase activity, or unidirectional Na(+) movements across the gills. We conclude that TFM causes a mismatch between ATP supply and demand in trout, leading to increased reliance on glycolysis, but it does not have physiologically relevant effects on ion balance in hard water.

Experimental and theoretical investigation of [Al(PCr)(H2O)] complex in aqueous solution

Phosphocreatine is a phosphorylated creatine molecule synthesized in the liver and transported to muscle cells where it is used for the temporary storage of energy. In Alzheimer's disease, the capture of glucose by cells is impaired, which negatively affects the Krebs cycle, leading to problems with the generation of phosphocreatine. Furthermore, the creatine-phosphocreatine system, regulated by creatine kinase, is affected in the brains of Alzheimer's disease patients. Aluminum ions are associated with Alzheimer's disease. Al(III) decreases cell viability and increases the fluidity of the plasma membrane, profoundly altering cell morphology. In this study, one of the complexes formed by Al(III) and phosphocreatine in aqueous solution was investigated by potentiometry, (31)P and (27)Al NMR, Raman spectroscopy and density functional theory (DFT) calculations. The log KAlPCr value was 11.37±0.03. Phosphocreatine should act as a tridentate ligand in this complex. The (27)Al NMR peak at 48.92ppm indicated a tetrahedral molecule. The fourth position in the arrangement was occupied by a coordinated water molecule. Raman spectroscopy, (31)P NMR and DFT calculations (DFT:B3LYP/6-311++G(**)) indicated that the donor atoms are oxygen in the phosphate group, the nitrogen of the guanidine group and the oxygen of the carboxylate group. Mulliken charges, NBO charges, frontier molecular orbitals, electrostatic potential contour surfaces and mapped electrostatic potential were also examined.

Dependence of residual dipolar couplings on foot angle in (1)H MR spectra from skeletal muscle

Foot dorsi and plantar flexion affects the pennation angle of skeletal muscle fibers and changes the fiber direction with respect to the main magnetic field, thereby affecting MR spectrum of the muscle. In order to analyze the effect that foot flexion has on the MR spectrum, tibialis anterior (TA) and soleus muscles were studied in humans and rats. Localized MRS was performed at different foot angles in clinical and pre-clinical settings using a 3T MRI/MRS GE Excite HD and 7T Bruker Clinscan scanner, respectively. In this study we show the effect of foot angle variation on total Creatine (tCr) resonance of (1)H spectrum at 3.03 and 3.93ppm for TA and soleus muscles. In addition to this, we observe a 4-line splitting pattern for methylene resonance of tCr in the rat TA spectrum for a specific foot angle. This observation is attributed to the individual splitting of creatine and phosphocreatine of the tCr signal. Novel hydrogel application is demonstrated and used to support our in vivo observations and for the first time splitting of individual resonances of Cr and PCr has been shown in an in vitro set-up.

Pyruvate-fortified resuscitation stabilizes cardiac electrical activity and energy metabolism during hypovolemia

AIM: To test the hypothesis that fluid resuscitation with Ringer’s solution enriched with pyruvate (PR), a physiological antioxidant and energy substrate, affords protection of myocardial metabolism and electrophysiological performance superior to lactated Ringer’s (LR) during hypovolemia and hindlimb ischemia-reperfusion.

METHODS: Male domestic goats (25-30 kg) were exsanguinated to a mean arterial pressure of 48 ± 1 mmHg. Right hindlimb ischemia was imposed for 90 min by applying a tourniquet and femoral crossclamp. LR or PR, infused iv, delivered 0.05 mmol/kg per minute L-lactate or pyruvate, respectively, from 30 min hindlimb ischemia until 30 min post-ischemia. Time controls (TC) underwent neither hemorrhage, hindlimb ischemia nor resuscitation. Goats were sacrificed and left ventricular myocardium biopsied at 90 min fluid resuscitation (n = 6 per group) or 3.5 h later (n = 9 LR, 10 PR, 8 TC).

RESULTS: Myocardial 8-isoprostane content, phosphocreatine phosphorylation potential, creatine kinase activity, and heart rate-adjusted QT interval (QTc) variability were evaluated at 90 min resuscitation and 3.5 h post-resuscitation. PR sharply lowered pro-arrhythmic QTc variability vs LR (P < 0.05); this effect persisted 3.5 h post-resuscitation. PR lowered myocardial 8-isoprostane content, a product of oxidative stress, by 39 and 37% during and 3.5 h after resuscitation, respectively, vs LR. Creatine kinase activity fell 42% post-LR vs TC (P < 0.05), but was stable post-PR (P < 0.02 vs post-LR). PR doubled phosphocreatine phosphorylation potential, a measure of ATP free energy state, vs TC and LR (P < 0.05); this energetic enhancement persisted 3.5 h post-resuscitation.

CONCLUSION: By augmenting myocardial energy state and protecting creatine kinase activity, pyruvate-enriched resuscitation stabilized cardiac electrical function during central hypovolemia and hindlimb ischemia-reperfusion.

Creatine supplementation and swim performance: a brief review

Nutritional supplements are popular among athletes participating in a wide variety of sports. Creatine is one of the most commonly used dietary supplements, as it has been shown to be beneficial in improving performance during repeated bouts of high-intensity anaerobic activity. This review examines the specific effects of creatine supplementation on swimming performance, and considers the effects of creatine supplementation on various measures of power development in this population. Research performed on the effect of creatine supplementation on swimming performance indicates that whilst creatine supplementation is ineffective in improving performance during a single sprint swim, dietary creatine supplementation may benefit repeated interval swim set performance. Considering the relationship between sprint swimming performance and measurements of power, the effect of creatine supplementation on power development in swimmers has also been examined. When measured on a swim bench ergometer, power development does show some improvement following a creatine supplementation regime. How this improvement in power output transfers to performance in the pool is uncertain. Although some evidence exists to suggest a gender effect on the performance improvements seen in swimmers following creatine supplementation, the majority of research indicates that male and female swimmers respond equally to supplementation. A major limitation to previous research is the lack of consideration given to the possible stroke dependant effect of creatine supplementation on swimming performance. The majority of the research conducted to date has involved examination of the freestyle swimming stroke only. The potential for performance improvements in the breaststroke and butterfly swimming strokes is discussed, with regards to the biomechanical differences and differences in efficiency between these strokes and freestyle. Key PointsCreatine supplementation does not improve single sprint swimming performance.Creatine supplementation does improve repeated interval swim set performance.Creatine supplementation does improve power development in swimmers when measured on a swim bench ergometer.As a result of the high energy demands of the butterfly and breaststroke competitive swimming styles, potentially, the benefits associated with creatine supplementation and swimming performance could be greater when swimming butterfly or breaststroke, compared to the commonly examined freestyle swimming stroke.