Liquid chromatographic evaluation of purine production in the donor human heart during transplantation

Influence of Electronic Cigarettes on Antioxidant Capacity and Nucleotide Metabolites in Saliva

The balance between reactive oxygen species production and the activity of antioxidant systems present in saliva is an important element in maintaining oral environment homeostasis. E-cigarettes adversely affect the oral cavity and their cytotoxic effect is related to oxidative stress. The aim of this study was to assess the influence of using electronic cigarettes on antioxidant capacity of saliva. The study involved 110 subjects (35 e-cigarettes users, 33 traditional cigarettes smokers and 42 non-smokers). Laboratory analysis involved quantitation of uric acid, hypoxanthine, xanthine, TAOS (total antioxidant status) and TEAC (Trolox equivalent antioxidant capacity) in saliva. Lower values for TAOS and TEAC were observed among e-cigarettes users and traditional cigarettes smokers in comparison to non-smokers. Uric acid concentration tended to be higher among e-cigarettes users while no differences in hypoxanthine and xanthine saliva concentrations were observed. Electronic cigarettes usage affects antioxidant capacity of saliva to the same extent as traditional cigarettes, when comparing smokers to non-smokers. Further longitudinal studies on a larger study group are needed to assess the effect of changes in antioxidant status on oral health.

Change in Lactate, Ammonia, and Hypoxanthine Concentrations in a 1-Year Training Cycle in Highly Trained Athletes: Applying Biomarkers as Tools to Assess Training Status

Włodarczyk, M, Kusy, K, Słomińska, E, Krasiński, Z, and Zieliński, J. Change in lactate, ammonia, and hypoxanthine concentrations in a 1-year training cycle in highly trained athletes: applying biomarkers as tools to assess training status. J Strength Cond Res 34(2): 355-364, 2020-The aim was to determine changes in biomarker (LA, NH3, purine metabolites) blood concentration during graded exercise and recovery throughout an annual training cycle in highly trained athletes of different training profiles. The study included 12 sprinters (SP, 21-30 years), 11 triathletes (TR, 20-31 years), 12 futsal players (FU, 19-31 years), and 13 amateur runners (AM, 20-33 years). Purine metabolite (hypoxanthine, xanthine, uric acid), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes postexercise) in 4 phases of an annual training cycle. Purine metabolite concentration was determined from plasma, whereas LA and NH3 from whole blood. For LA during exercise and recovery, certain significant differences between training phases within groups were observed for FU, TR, and SP but not for AM. For NH3, the greatest differences between examination points were observed for SP and TR near maximal exercise and in the first few stages of recovery. For hypoxanthine (Hx), the largest amount of differences between examination points was observed for FU, TR, and FU throughout the entire exercise spectrum. Biomarker concentration dynamics change during an incremental exercise test and postexercise in an annual training cycle. Biomarker responses differ depending on training type and magnitude of training loads used in various phases of an annual training cycle. When assessing training status using an incremental exercise test throughout an annual training cycle, NH3 and Hx concentration changes are more sensitive compared with LA.

Changes in Blood Concentration of Adenosine Triphosphate Metabolism Biomarkers During Incremental Exercise in Highly Trained Athletes of Different Sport Specializations

Włodarczyk, M, Kusy, K, Słomińska, E, Krasiński, Z, and Zieliński, J. Changes in blood concentration of adenosine triphosphate metabolism biomarkers during incremental exercise in highly trained athletes of different sport specializations. J Strength Cond Res 33(5): 1192-1200, 2019-We hypothesized that (a) high-level specialized sport training causes different adaptations that induce specific biomarker release dynamics during exercise and recovery and (b) skeletal muscle mass affects biomarker release. Eleven sprinters (21-30 years), 16 endurance runners (18-31 years), 12 futsal players (18-29 years), and 12 amateur runners as controls (22-33 years) were examined. Hypoxanthine (Hx), xanthine (X), uric acid (UA), ammonia (NH3), and lactate (LA) concentrations were determined at rest, during an incremental treadmill exercise test (every 3 minutes), and during recovery (5, 10, 15, 20, and 30 minutes after exercise). Hx, X, and UA concentration was determined from plasma, while LA and NH3 from whole blood, and muscle mass was assessed using dual X-ray absorptiometry method. At rest, during incremental exercise, and up to 30 minutes into the postexercise recovery period, sprinters had lowest Hx, X, and UA concentrations, and endurance athletes had lowest NH3 concentrations. For LA during exercise, the lowest concentrations were noted in endurance athletes, except when reaching maximum intensity, where the differences between groups were not significant. There were no significant correlations observed between skeletal muscle mass and biomarker concentration at maximal intensity and recovery in any group. In conclusion, the magnitude of exercise-induced biomarker concentration is only related to training adaptations through specific training profile but not to muscle mass. In addition, the results suggest that combined measuring of LA, NH3, and Hx concentration in blood is useful in indirectly reflecting key changes in exercise- and training-induced energy status. Further research should focus on studying how specific training sessions affect individual biomarker response in highly trained athletes.

Plasma Nucleotide Dynamics during Exercise and Recovery in Highly Trained Athletes and Recreationally Active Individuals

Circulating plasma ATP is able to regulate local skeletal muscle blood flow and 0₂ delivery causing considerable vasodilatation during exercise. We hypothesized that sport specialization and specific long-term training stimuli have an impact on venous plasma [ATP] and other nucleotides concentration. Four athletic groups consisting of sprinters (n=11; age range 21–30 yr), endurance-trained athletes (n=16; age range 18–31 yr), futsal players (n=14; age range 18–30 yr), and recreationally active individuals (n=12; age range 22–33 yr) were studied. Venous blood samples were collected at rest, during an incremental treadmill test, and during recovery. Baseline [ATP] was 759±80 nmol·l⁻¹ in competitive athletes and 680±73 nmol·l⁻¹ in controls and increased during exercise by ~61% in competitive athletes and by ~31% in recreationally active participants. We demonstrated a rapid increase in plasma [ATP] at exercise intensities of 83–87% of VO₂max in competitive athletes and 94% in controls. Concentrations reported after 30 minutes of recovery were distinct from those obtained preexercise in competitive athletes (P < 0.001) but not in controls (P = 0.61). We found a correlation between total-body skeletal muscle mass and resting and maximal plasma [ATP] in competitive athletes (r=0.81 and r=0.75, respectively). In conclusion, sport specialization is significantly related to plasma [ATP] at rest, during exercise, and during maximal effort. Intensified exercise-induced plasma [ATP] increases may contribute to more effective vessel dilatation during exercise in highly trained athletes than in recreational runners. The most rapid increase in ATP concentration was associated with the respiratory compensation point. No differences between groups of competitive athletes were observed during the recovery period suggesting a similar pattern of response after exercise. Total-body skeletal muscle mass is indirectly related to plasma [ATP] in highly trained athletes.

T. SMOLEŃSKI, ZOLADZ JA. Endothelial Glycocalyx Integrity Is Preserved in Young, Healthy Men During a Single Bout of Strenuous Physical Exercise

In the present study we aimed to evaluate whether oxidative stress and inflammation induced by strenuous exercise affect glycocalyx integrity and endothelial function. Twenty one young, untrained healthy men performed a maximal incremental cycling exercise – until exhaustion. Markers of glycocalyx shedding (syndecan-1, heparan sulfate and hyaluronic acid), endothelial status (nitric oxide and prostacyclin metabolites – nitrate, nitrite, 6-keto-prostaglandin F1α), oxidative stress (8-oxo-2’-deoxyguanosine) and antioxidant capacity (uric acid, non-enzymatic antioxidant capacity) as well as markers of inflammation (sVCAM-1 and sICAM-1) were analyzed in venous blood samples taken at rest and at the end of exercise. The applied strenuous exercise caused a 5-fold increase in plasma lactate and hypoxanthine concentrations (p<0.001), a fall in plasma uric acid concentration and non-enzymatic antioxidant capacity (p<10−4), accompanied by an increase (p=0.003) in sVCAM-1 concentration. Plasma 6-keto-prostaglandin F1α concentration increased (p=0.006) at exhaustion, while nitrate and nitrite concentrations were not affected. Surprisingly, no significant changes in serum syndecan-1 and heparan sulfate concentrations were observed. We have concluded, that a single bout of severe-intensity exercise is well accommodated by endothelium in young, healthy men as it neither results in evident glycocalyx disruption nor in the impairment of nitric oxide and prostacyclin production.

Effects of fatty acid treatments on the dexamethasone-induced intramuscular lipid accumulation in chickens

BACKGROUND

Glucocorticoid has an important effect on lipid metabolism in muscles, and the type of fatty acid likely affects mitochondrial utilization. Therefore, we hypothesize that the different fatty acid types treatment may affect the glucocorticoid induction of intramuscular lipid accumulation.

METHODOLOGY/PRINCIPAL FINDINGS

The effect of dexamethasone (DEX) on fatty acid metabolism and storage in skeletal muscle of broiler chickens (Gallus gallus domesticus) was investigated with and without fatty acid treatments. Male Arbor Acres chickens (31 d old) were treated with either palmitic acid (PA) or oleic acid (OA) for 7 days, followed by DEX administration for 3 days (35-37 d old). The DEX-induced lipid uptake and oxidation imbalance, which was estimated by increased fatty acid transport protein 1 (FATP1) expression and decreased carnitine palmitoyl transferase 1 activity, contributed to skeletal muscle lipid accumulation. More sensitive than glycolytic muscle, the oxidative muscle in DEX-treated chickens showed a decrease in the AMP to ATP ratio, a decrease in AMP-activated protein kinase (AMPK) alpha phosphorylation and its activity, as well as an increase in the phosphorylation of mammalian target of rapamycin (mTOR) and ribosomal p70S6 kinase, without Akt activation. DEX-stimulated lipid deposition was augmented by PA, but alleviated by OA, in response to pathways that were regulated differently, including AMPK, mTOR and FATP1.

CONCLUSIONS

DEX-induced intramuscular lipid accumulation was aggravated by SFA but alleviated by unsaturated fatty acid. The suppressed AMPK and augmented mTOR signaling pathways were involved in glucocortcoid-mediated enhanced intramuscular fat accumulation.

Metabolism of 4-pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR) in rodent tissues and in vivo

Our previous studies identified 4-pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR) phosphates in human erythrocytes. We demonstrated formation of these nucleotides by phosphorylation of 4PYR and potential toxicity due to disruption of erythrocyte energy balance. This study aimed to evaluate the ability of the other cell types to phosphorylate 4PYR to characterize function and toxicity of these compounds. Homogenates of rat heart, kidneys, and liver were used to study the rate of 4PYR phosphorylation in the presence of ATP. In another experiment, 4PYR was administered into mouse as repeated subcutaneous injections and into rats as intraperitoneal infusion. After 7 days, heart, liver, kidney, lungs, and skeletal muscle were collected, and the concentration of 4PYR nucleotides was evaluated. HPLC was used to measure 4PYR and 4PYR nucleotides in homogenate and specimens from in vivo experiments. 4PYR was rapidly phosphorylated by the liver homogenate (390 ± 27 nmol/min/g wet wt). Significant rates were reported in the heart and kidneys' homogenates: 34.3 ± 4.3 nmol/min/g and 33.2 ± 9.2 nmol/min/g, respectively. Phosphorylation of 4PYR was almost completely inhibited by adenosine kinase inhibitor 5'-iodotubercidin. Administration of 4PYR in vivo resulted in accumulation of 4PYR monophosphate in the liver, heart, skeletal muscle, and lung (20-220 nmol/g dry wt) except kidney (<1 nmol/g). In contrast to erythrocytes, no 4PYR triphosphate formation (<1 nmol/g) was observed in any of the organs studied. We conclude that not only the erythrocytes but also other cell types are capable of phosphorylating 4PYR to form 4PYR monophosphate. Potential toxicity or physiological role of 4PYR in peripheral organs could be considered, but mechanisms will be different from that in erythrocytes.

Erythrocyte-dependent regulation of human skeletal muscle blood flow: role of varied oxyhemoglobin and exercise on nitrite, S-nitrosohemoglobin, and ATP

The erythrocyte is proposed to play a key role in the control of local tissue perfusion via three O(2)-dependent signaling mechanisms: 1) reduction of circulating nitrite to vasoactive NO, 2) S-nitrosohemoglobin (SNO-Hb)-dependent vasodilatation, and 3) release of the vasodilator and sympatholytic ATP; however, their relative roles in vivo remain unclear. Here we evaluated each mechanism to gain insight into their roles in the regulation of human skeletal muscle blood flow during hypoxia and hyperoxia at rest and during exercise. Arterial and femoral venous hemoglobin O(2) saturation (O(2)Hb), plasma and erythrocyte NO and ATP metabolites, and leg and systemic hemodynamics were measured in 10 healthy males exposed to graded hypoxia, normoxia, and graded hyperoxia both at rest and during submaximal one-legged knee-extensor exercise. At rest, leg blood flow and NO and ATP metabolites in plasma and erythrocytes remained unchanged despite large alterations in O(2)Hb. During exercise, however, leg and systemic perfusion and vascular conductance increased in direct proportion to decreases in arterial and venous O(2)Hb (r(2) = 0.86-0.98; P = 0.01), decreases in venous plasma nitrite (r(2) = 0.93; P < 0.01), increases in venous erythrocyte nitroso species (r(2) = 0.74; P < 0.05), and to a lesser extent increases in erythrocyte SNO (r(2) = 0.59; P = 0.07). No relationship was observed with plasma ATP (r(2) = 0.01; P = 0.99) or its degradation compounds. These in vivo data indicate that, during low-intensity exercise and hypoxic stress, but not hypoxic stress alone, plasma nitrite consumption and formation of erythrocyte nitroso species are associated with limb vasodilatation and increased blood flow in the human skeletal muscle vasculature.

Propionyl-L-carnitine improves hemodynamics and metabolic markers of cardiac perfusion during coronary surgery in diabetic patients

Diabetic hearts are particularly vulnerable to ischemia-reperfusion injury during cardiac surgery. Application of carnitine derivatives could be beneficial not only because of metabolic effects but also by protecting vasculature. This study aimed to evaluate hemodynamic changes associated with propionyl-L-carnitine and L-carnitine administration and its correlation with biochemical markers of cardiac vascular function.

METHODS

Sixty-eight diabetic patients undergoing cardiopulmonary bypass coronary operation were given intravenously 20 mg/kg b.w. L-carnitine (LC), 24 mg/kg b.w. propionyl-L-carnitine (PC), or placebo (Cont). Endothelin and nucleotide metabolites were determined intraoperatively in arterial and coronary sinus blood and heart biopsies.

RESULTS

Cardiac index at 6 and 12 h after cardiopulmonary bypass was significantly higher in PC (3.30 +/- 0.12 and 3.47 +/- 0.15 L/min/m2) as compared to Cont (2.92 +/- 0.13 and 2.91 +/- 0.16 L/min/m2; P = 0.04 and P = 0.01, respectively). Mean pulmonary artery pressure was lower in PC at 6 (20.8 +/- 0.91 mmHg) and 12 h (20.7 +/- 0.81 mmHg) in comparison to Cont (23.5 +/- 0.75 and 23.4 +/- 0.75 mmHg; P = 0.03 and P = 0.02, respectively). Trans-cardiac endothelin difference on reperfusion was higher in Cont (0.33 +/- 0.26 pmol/L) than in LC (-0.61 +/- 0.24 pmol/L, P = 0.012) and tended to be higher than in PC (-0.29 +/- 0.17 pmol/L, P = 0.056). Trans-cardiac hypoxanthine difference after 10 min reperfusion was significantly higher in Cont (6.22 +/- 1.08 micromol/L) in comparison to LC (3.17 +/- 0.66 micromol/L, P = 0.025) and PC (2.36 +/- 0.73 micromol/L, P = 0.006). Myocardial hypoxanthine concentration was lowest in PC.

CONCLUSIONS

Significant improvement of hemodynamics following propionyl-L-carnitine administration in diabetic patients undergoing on-bypass coronary surgery was accompanied by reduced trans-cardiac endothelin difference and rapid hypoxanthine washout during reperfusion suggesting improvement of metabolism or vascular function.

β-Amyloid Fragment 25–35 Causes Mitochondrial Dysfunction in Primary Cortical Neurons

Beta-amyloid deposition and compromised energy metabolism both occur in vulnerable brain regions in Alzheimer's disease. It is not known whether beta-amyloid is the cause of impairment of energy metabolism, nor whether impaired energy metabolism is specific to neurons. Our results, using primary neuronal cultures, show that 24-h incubation with A beta(25-35) caused a generalized decrease in the specific activity of mitochondrial enzymes per milligram of cellular protein, induced mitochondrial swelling, and decreased total mitochondrial number. Incubation with A beta(25-35) decreased ATP concentration to 58% of control in neurons and 71% of control in astrocytes. Levels of reduced glutathione were also lowered by A beta(25-35) in both neurons (from 5.1 to 2.9 nmol/mg protein) and astrocytes (from 25.2 to 14.9 nmol/mg protein). We conclude that 24-h treatment with extracellular A beta(25-35) causes mitochondrial dysfunction in both astrocytes and neurons, the latter being more seriously affected. In astrocytes mitochondrial impairment was confined to complex I inhibition, whereas in neurons a generalized loss of mitochondria was seen.

Adenine incorporation in human and rat endothelium

Adenine (ADE) reutilisation is an important pathway of adenylate pool regeneration. Data on the rate of this process in different types of cells, its regulation and the importance of species differences is limited. In this study we evaluated adenine incorporation rate and the effect of metabolic factors on this process in human and rat endothelium and compared it to adenine phosphoribosyltransferase (APRT) activity. Microvascular endothelial cells from human (HE) and rat (RE) hearts and a transformed human microvascular endothelial cell line (HMEC-1) were investigated. The rate of adenine incorporation into the adenine nucleotide pool under control conditions was 3.1+/-0.3, 82.8+/-11.1 and 115.1+/-11.2 pmol/min per mg protein for HE, RE and HMEC-1, respectively. In the presence of 2.5 mM ribose or elevated inorganic phosphate concentration in the medium (4.8 mM), few changes were observed in all types of cells. In the presence of both ribose and high inorganic phosphate, the rate of adenine incorporation for RE and HMEC-1 was not significantly different from control, while in HE the rate of adenine incorporation into adenine nucleotides was increased by 75%. Activities of APRT in RE and HMEC-1 were 237.7+/-23.2 and 262.0+/-30.6 pmol/min per mg protein respectively while the activity in HE was markedly lower 48.7+/-3.0 pmol/min per mg protein. In conclusion, nucleotide synthesis from adenine seems to be a slow process in human cardiac microvascular endothelium but it is fast and efficient in rat heart microvascular endothelial cells. Low APRT activity in normal human endothelial cells seems to be the most likely mechanism for this. However, adenine incorporation rate and APRT activity could be greatly enhanced in human endothelium, as demonstrated in transformed cells.

Effect of methotrexate on blood purine and pyrimidine levels in patients with rheumatoid arthritis

OBJECTIVE

The mechanism of anti-inflammatory effects of methotrexate (MTX) at low dose may relate to a decrease in availability of the purine precursor or it may depend on accumulation of 5-aminoimidazole-4-carboxamide (AICAR) and the anti-inflammatory nucleoside adenosine. The aim of this study was to evaluate the possible mechanism of action by analysis of changes in blood concentrations of purine and pyrimidine metabolites during MTX treatment.

METHODS

Venous blood samples were collected from rheumatoid arthritis patients before and at different times for up to 7 days after the start of MTX treatment. Whole blood concentrations of adenosine, uridine, hypoxanthine, uric acid and erythrocyte nucleotides were measured by HPLC.

RESULTS

The initial blood adenosine concentration was 0.073 +/- 0.013 microM and no differences were observed during MTX treatment. However, a decrease in uric acid concentration was observed from 205.5+/-13.5 to 160. 9+/-13.5 microM (P<0.05) within 24 h after MTX administration. The hypoxanthine concentration decreased in parallel with uric acid, while the uridine concentration decreased 48 h after MTX administration. No accumulation of AICAR-triphosphate (ZTP) was observed in the erythrocytes.

CONCLUSIONS

MTX decreases circulating purine and pyrimidine concentrations, and their availability for DNA and RNA synthesis, which may affect immune cell proliferation and protein (cytokine) expression. The absence of adenosine concentration changes and lack of ZTP formation is evidence against an AICAR/adenosine mechanism, although localized adenosine concentration changes cannot be excluded.

Influence of heat stress on myocardial metabolism and functional recovery after cardioplegic arrest: a 31P N.M.R study

OBJECTIVE

Heat stress and induction of heat shock proteins confer protection against myocardial ischemia-reperfusion injury; however the precise mechanisms of this effect remain unknown. We investigated the influence of heat stress on metabolic and functional recovery after cardioplegic arrest, in a protocol mimicking clinical donor heart preservation.

METHODS

Langendorff perfused rat hearts in control group (C, n = 6) and heat stressed (24 h prior to experiment) group (HS, n = 6) were subjected to 4 h of ischemia at 4 degrees C following cardioplegic arrest (St. Thomas' No. 1). 31P nuclear magnetic resonance spectroscopy was used to follow changes in ATP, phosphocreatine and inorganic phosphate concentrations during the pre-ischemic, ischemic and reperfusion periods. Myocardial adenine nucleotide levels in hearts at the end of experiments and purine catabolite release in coronary effluent during reperfusion, were evaluated using high performance liquid chromatography. Mechanical function in the pre-ischemic and reperfusion periods was evaluated using an intraventricular balloon. Western immunoblotting was used to quantitate HSP70 expression.

RESULTS

Although baseline concentrations of ATP and phosphocreatine were similar in C and HS groups, the rate of high-energy phosphate depletion was attenuated during the early phase of ischemia in HS groups. On reperfusion, recovery of ATP was 10-20% greater in HS versus C groups; phosphocreatine levels also recovered better in the HS group, transiently reaching levels 40% higher in HS versus C groups. The concentrations of adenine nucleotides in hearts were significantly higher in the HS versus C groups. These changes were associated with an attenuation of total purine catabolite release in the coronary effluent in HS versus C groups. A significant improvement in relative recovery of developed pressure was shown in HS versus C groups in the post-ischemic periods.

CONCLUSIONS

Heat stress causes beneficial changes in high-energy phosphate metabolism in the rat heart subjected to cardioplegic arrest and ischemia. Improved mechanical recovery in HS versus C groups was associated with a decreased rate of high-energy phosphate depletion and increased recovery of ATP and phosphocreatine levels during reperfusion. Changes in energy metabolism may play a role in the mechanism of cardioprotection by heat stress during prolonged hypothermic cardiac arrest. rights reserved.