Whole blood versus plasma measurements of glutamate and alanine across the human myocardium

Comparison of whole blood and plasma aorto-coronary sinus concentration differences of glutamate and alanine were made before, during and after coronary sinus pacing in seven patients with normal and six patients with stenotic coronary arteries. Mean differences between duplicate analyses were greater in whole blood than plasma both of glutamate (7.5 +/- 5.8 vs. 3.3 +/- 3.0 mumol/l, p less than 0.001) and of alanine (7.9 +/- 7.0 vs. 3.8 +/- 3.4 mumol/l, p less than 0.001). Concentrations of glutamate were 3.4 and of alanine 1.4 times higher in whole blood than in plasma. Blood cells were calculated to be responsible for about 20% of glutamate and alanine blood exchanges across the heart. Plasma and whole blood fluxes were closely positively correlated (glutamate:r = 0.81, alanine:r = 0.88) and had always the same direction. Differences in myocardial exchanges of amino acids between the patients with and without coronary artery disease, as well as rapid changes during pacing, could be demonstrated in plasma analyses but were not significantly reflected in whole blood glutamate determinations. This seemed to be due to the greater variations in whole blood analysis. In conclusion, differences in aorto-coronary sinus plasma concentrations reflected, although underestimated, whole blood fluxes. Because of considerable gains in precision of analysis, plasma should be preferred to whole blood for evaluations of glutamate and alanine exchanges across the human heart.     

Myocardial glutamate and alanine exchanges related to carbohydrate metabolism in patients with normal and stenotic coronary arteries

Summary. Myocardial exchanges of glutamate, alanine, glucose, lactate, free fatty acids (FFA) and oxygen in resting state were determined in nine subjects (controls) without and in 28 patients with coronary artery disease (CAD). Patients with CAD showed increased myocardial glutamate uptake (2·51±0·60 μmol/min) and alanine release (1·25±0·60μmol/min) compared to controls (glutamate uptake: 1·66±0·79 μmol/min; alanine release: 0·63±0·41 μmol/min). Myocardial glucose and lactate uptake was augmented in CAD patients, whereas FFA arterio-venous differences were decreased in patients with three-vessel-disease. The amount of glutamate taken up by the heart correlated positively to lactate uptake in all subjects (r= 0·84) and to external glucose utilization in patients with CAD (r= 0·72). Myocardial alanine release was positively related to glucose and lactate uptake in controls and in patients with only moderate CAD (one-vessel-disease). Glucose and FFA uptake correlated inversely in controls (r=0·84), but not in CAD patients. A tight relation between exchanges of glutamate/alanine and carbohydrate metabolism in human heart is demonstrated. The data suggest altered myocardial substrate exchange towards augmented carbohydrate utilization in CAD patients in resting state. The results agree with in vitro and animal studies suggesting extraction of glutamate from the circulation to be of importance for maintaining carbohydrate consumption in chronic ischaemic heart disease.     

Systemic and intracardiac vascular endothelial growth factor and angiopoietin‐1 and ‐2 levels in coronary artery disease: Effects of angioplasty

Background. Vascular growth factors are involved in the pathophysiology of human atherosclerotic vascular disease and plaque destabilization. We hypothesized that in stable patients with coronary artery disease (CAD), plasma levels of vascular endothelial growth factor (VEGF) and angiopoietins 1 and 2 (as indices of angiogenesis) would be no higher in coronary sinus blood when compared to the aortic root, coronary ostium, and peripheral femoral vein. Secondly, we hypothesized that percutaneous coronary intervention (PCI; angioplasty±stenting) would increase intracardiac levels of these indices, perhaps by destabilizing coronary plaques.

Methods. Patients undergoing elective diagnostic coronary angiography (n = 70; mean age 58.8±11.2 years) of which 37 proceeded to PCI were recruited. Blood samples were obtained from the aortic root, coronary ostium, coronary sinus, and femoral vein. Plasma VEGF, angiopoietin‐1 and angiopoietin‐2 levels were measured by immunoassays.

Results. There were no significant differences in VEGF, angiopoietin‐1 and angiopoietin‐2 levels when aortic root, coronary ostium, coronary sinus, and femoral vein samples were compared (P = not significant (NS)). In patients undergoing PCI, peripheral angiopoietin‐2 levels were increased significantly post PCI (P = 0.01). There was also a difference in intracardiac gradient (that is, aortic root‐coronary sinus difference) in angiopoietin‐1 (P = 0.02) following PCI. No significant changes in VEGF with PCI were noted.

Conclusion. There were no differences in indices of angiogenesis when aortic root, coronary ostium, coronary sinus, and femoral vein levels of VEGF and angiopoietins are compared, suggesting that peripheral blood measurements of these indices are comparable to intracardiac levels. Although no immediate effects were observed in soluble VEGF levels, PCI affected intracardiac angiopoietin‐1 with a systemic release of angiopoietin‐2. Further investigations are necessary to determine the relative systemic and intracardiac effects of the angiopoietins in vascular remodelling post PCI.     

Pacing induced angina and plattelet reactivity

Platelet function was studied during pacing-induced angina pectoris in nine patients with coronary heart disease. Blood was sampled via catheters from the coronary sinus and the aorta at rest and during angina. The influence of the sampling procedures on the platelet function was evaluated in blood collected via catheters and via short venflons. The catheter induced pseudopode formation in the platelets. The aggregation response was similar, while platelet retention as measured with Hellem's method for native blood, was slightly lower in blood collected via catheters than via venflons.

At rest the maximal rate of primary, ADP-induced aggregation was lower in blood from the coronary sinus than from the aorta, as was the percentage of platelets retained in glass bead columns. The ability of platelets to produce prostaglandin metabolites, estimated from malondialdehyde formation after thrombin stimulation was also moderately, but significantly lower in coronary sinus blood.

During pacing-induced angina primary, ADP-induced aggregation and platelet retention values remained significantly lower in blood that had passed the coronary circulation than the aortic blood. There were no differences between aortic or coronary sinus samples collected at rest than during pacing. Unchanged platelet counts indicates that trapping of platelets did not occur. Thus, platelet reactivity was lower in coronary sinus than aortic blood at rest in patients with coronary heart disease, and a moderate pacing-induced angina did not influence this pattern.     

Myocardial Lipid and Carbohydrate Metabolism in Healthy, Fasting Men at Rest: Studies During Continuous Infusion of 3H-Palmitate

Abstract Myocardial metabolism of lipid and carbohydrate substrates was studied in 17 healthy men at rest by measuring the arterial-coronary sinus [(a—cs)] concentration differences. A continuous intravenous infusion of albumin-bound ³H-palmitate was given to provide a tracer for the plasma free fatty acids (FFA) and to produce endogenous labelling of plasma triglycerides (TG). A statistically significant positive (a—cs) difference in triglyceride (TG) concentration was detected in 10 of the 17 subjects and averaged 18±4 (SEM) μmol/1 plasma for the 17 subjects. This was 1.0% of the average arterial TG concentration. A significant positive (a—cs) difference in TG radioactivity was found in 12 of the 17 subjects but it was not possible to quantitate myocardial TG extraction from these radioisotope data. Myocardial extraction of FFA based on the radiopalmitate data was on average 39% greater than the extraction of FFA measured chemically. This was interpreted as indicating an efflux of unlabelled fatty acids into the coronary sinus, most probably from a glyceride pool within the myocardium. The finding that this efflux of fatty acids was not accompanied by free glycerol suggested either that the fatty acids were derived from partial hydrolysis of glycerides, or that glycerol was metabolised within the myocardium. Seven of the subjects had significant, positive (a—cs) differences in free glycerol concentration suggesting that the human heart is capable of metabolising glycerol. There were significant, negative linear correlations between arterial FFA concentration and myocardial extraction of glucose, lactate and pyruvate with significant efflux of pyruvate from the heart at higher FFA concentrations. These findings suggested that FFA can decrease glucose extraction by the human heart and that one possible mechanism for this may be the inhibition of pyruvate dehydrogenase. The average (±SEM) oxygen extraction ratios (OERs) for the substrates were: TG 16±4%; FFA 48±3%; glucose 20±3%; lactate 8±2%; pyruvate 1±0.3%. The total OER for these substrates averaged 97% suggesting that in the resting, fasting, state there is little change in the total energy content of endogenous myocardial substrate pools.     

Anatomical Findings in Patients Having Had a Chronically Indwelling Coronary Sinus Defibrillation Lead

The purpose of this report is to review the gross and histological cardiac anatomical findings in patients with chronically indwelling coronary sinus leads at the time of autopsy or cardiac transplantation. Transvenous cardioverter defibrillators offer effective protection against sudden death. The use of a coronary sinus electrode has been shown in some patients to decrease the defibrillation threshold. The anatomical consequences of chronically indwelling coronary sinus cardioversion /defibrillation electrodes in patients having transvenous implantable cardioverter defibrillators is unknown. The hearts of seven patients with chronically indwelling coronary sinus electrodes were evaluated following autopsy (n= 2) or cardiac transplantation (n= 5), The coronary sinus electrode in each case was a 6.5 French silicon lead with a 5-cm long defibrillation coil (Medtronic CS lead model 6933) that was positioned as distally as possible within the coronary sinus at the time of implantable cardioverter defibrillator surgery. The seven hearts examined were derived from patients whose age ranged between 49 and 69 (mean 56 ± 7 years). Six had coronary artery disease and one had idiopathic dilated cardiomyopathy. The time from implant to death or cardiac transplantation was 8 ± 6 months, range 1–18 months. In all seven patients, there was no evidence of any significant damage from the presence of the coronary sinus lead. The only finding in each case was the scattered presence of a thin white fibrous sheath over the lead that intermittently adhered to the coronary sinus endothelium and, in the two patients transplanted 1–3 months after implantable cardioverter defibrillator insertion, a mild inflammation reaction adjacent to the leads in the coronary sinus endothelium. There was no evidence of coronary sinus occlusion, adjacent coronary artery injury, coronary sinus perforation, coronary sinus burn, or myocardial injury adjacent to the lead. Cause of death was due to end-stage congestive heart failure and thrombotic stroke, respectively, in the two patients examined at autopsy. Coronary sinus defibrillation leads can be used safely without harmful anatomical effect.     

Muscle ammonia and amino acid metabolism during dynamic exercise in man

Summary. The effect of dynamic exercise on muscle and blood ammonia (NH₃) and amino acid contents has been investigated. Eight healthy men cycled at 50% and 97% of maximal oxygen uptake for 10 min and 5·2 min (to fatigue), respectively. Biopsies (quadriceps femoris muscle), arterial and femoral venous blood samples were obtained at rest and during exercise. Muscle NH₃ at rest and after submaximal exercise was (x?±SE) 0·5±0·1 mmol/kg dry muscle (d.m.) and increased to 4·1 ±0·5 mmol/kg d.m. at fatigue (P<0·001). The total adenine nucleotide (TAN) pool (TAN=ATP+ADP+AMP) did not change after submaximal exercise but decreased significantly at fatigue (P<0·01). The decrease in TAN was similar to the increase in NH₃. Muscle lactate was 3±1 mmol/kg d.m. at rest and increased to 104±5 mmol/kg d.m. at fatigue. Whole blood and plasma NH₃ did not change significantly during submaximal but both increased significantly during maximal exercise (P<0·001). During maximal exercise the leg released 7,120 μmol/min of lactate, whereas only 89 μmol/min of NH₃ were released. NH₃ accumulation in muscle could buffer only 3% of the hydrogen ions released from lactate, and NH₃ release could account for only 1% of the net hydrogen ion transport out of the cell. Muscle glutamine was constant throughout the study, whereas glutamate decreased and alanine increased during exercise (P<0·001). No significant changes in either arterial whole blood glutamine or glutamate were observed. Arterial plasma glutamine and glutamate concentrations, however, increased and decreased (P<0·001), respectively, during exercise. It is concluded that (1) muscle and blood NH₃ levels increase only during strenuous exercise and (2) NH₃ accumulation is of minor importance for regulating acid-base balance in body fluids during exercise.     

Myocardial exchanges of glutamate, alanine and citrate in controls and patients with coronary artery disease

1. Myocardial exchanges of plasma alanine, glutamate, citrate, lactate, glucose and free fatty acids were determined in 17 patients with coronary artery disease and in seven control subjects during rest, atrial pacing and recovery. 2. Myocardial release of alanine was demonstrated in all subjects. The amount released was higher in patients with coronary artery disease than in controls. In the patients alanine release was related to severity of coronary artery stenosis. 3. All subjects showed myocardial uptake of glutamate, higher in patients than in controls at rest and during recovery. During atrial pacing myocardial glutamate extraction remained unchanged in controls but decreased in patients. 4. Citrate was released by the heart in all controls and patients. During recovery citrate output was higher in patients than in controls. 5. Myocardial alanine and citrate release during recovery were positively correlated. Both were positively related to myocardial uptake of glutamate during recovery and to the decrease in glutamate extraction during pacing. 6. The results indicate changed myocardial citrate and amino acid metabolism in coronary artery disease. Measurement of myocardial exchanges of glutamate, alanine and citrate in addition to lactate is suggested as a sensitive biochemical test in assessing myocardial ischaemia in man.     

Different venous angioplasty manoeuvres for successful implantation of CRT devices

Aims  Cardiac resynchronization therapy (CRT) has growing impact in the treatment of severe heart failure Stenosis of coronary veins, complex structure of coronary sinus and occlusions of subclavian veins can limit lead passage in the target vein. Methods and Results  Retrospective analysis of 705 implantation procedures of CRT devices from 1999 to July 2007 in a single centre to show the impact of venous angioplasty manoeuvres for successful placement of left ventricular lead. In 31 patients (3.5%) venous angioplasty was performed for LV-lead placement: 24 coronary veins (balloons 2.5–4.0mm), 4 subclavian veins, 3 valves in the coronary sinus and one Marshall vein were dilated. Ring like strictures of coronary veins made high inflation pressures (16 ± 4 atm) necessary. Success rate of LV lead placement were 99%. Complications were rare. Conclusions  Angioplasty of coronary or subclavian veins and valve structures of coronary sinus are a useful and safe tool for successful lead placement. The use of balloons of 3.0mm in size usually allows implantation of at least a unipolar lead.     

冠心病患者血清Lp-PLA2与HCY检测及其与冠状动脉病变程度的相关性分析

目的 探讨血清脂蛋白相关磷脂酶A2(Lp-PLA2)和同型半胱氨酸(HCY)水平检测与冠心病(CHP)患者冠状动脉病变程度的关系。方法 选取2017年1月～2018年5月延安大学附属医院经冠状动脉造影确诊的冠心病患者266例为实验组,其中男性161例,平均年龄57.3±8.5岁,女性105例,平均年龄61.1±11.6岁,选取同期该院冠状动脉造影阴性的体检者180例为对照组,其中男性97例,平均年龄54.6±10.5岁,女性83例,平均年龄47.5±6.3岁,记录两组性别、年龄、糖尿病史、卒中病史、心肌梗死病史、吸烟史和饮酒史,使用贝克曼AU2700全自动生化分析仪测定两组HCY,Lp-PLA2,空腹血糖(FBG)、三酰甘油(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)和脂蛋白(a)[Lp(a)]水平,分析两组各项指标的差异。秩和检验比较Gensini积分组 [低积分组(Gensini积分<14分,n=128),中积分组(Gensini积分14～28分,n=83),高积分组(Gensini积分>28分,n=55)共3组] Lp(a),HCY水平之间的差异,秩和检验比较冠状动脉不同支数病变组 [1支病变组(n=87)、2支病变组(n=91)、3支及3支以上病变组(n=88)共3组] Lp(a),HCY水平之间的差异。采用Pearson法分析Gensini积分与Lp-PLA2,HCY水平之间的相关性及Lp-PLA2与HCY水平之间的相关性。结果 实验组与对照组吸烟史、饮酒史及HCY,Lp-PLA2,Lp(a)水平为:59.77% vs 38.9%,86.84% vs 76.67%,53.7±21.8 μmol/L vs 6.5±4.1 μmol/L,366.1±114.3 μg/L vs 115.4±48.4 μg/L,569±283 mg/L vs 107±75.8 mg/L,差异均有统计学意义(t或χ²=7.78～18.75,均P<0.05)。Gensini低积分组、中积分组、高积分组HCY和Lp-PLA2水平为:39.6±20.2 μmol/L,50.7±26.4 μmol /L,68.5±31.8 μmol/L和245.4±88.3 μg/L,326.1±104.3 μg/L,459.4±113.5 μg/L,差异均有统计学意义(Z=5.81,15.25,均P<0.05)。冠状动脉1支病变组、2支病变组、3支及3支以上病变组HCY和Lp-PLA2水平为:48.6±27.2 μmol/L,47.8±23 μmol /L,74.1±38.6 μmol/L和201.4±73.5 μg/L,344.1±134.2 μg/L,530.6±255.3 μg/L,差异均有统计学意义(Z=5.63,17.91,均P<0.05),随Gensini积分的增加和冠状动脉病变支数的增多,HCY和Lp-PLA2水平升高,差异有统计学意义(t=5.43～16.57,均P<0.05),相关性分析显示Gensini积分与Lp-PLA2,HCY水平呈正相关(r=0.454,0.991,均P<0.05)。Lp-PLA2与HCY水平呈正相关(r=0.336,P<0.05)。结论 冠心病患者Lp-PLA2,HCY水平与冠状动脉病变程度呈正相关。     

Haemodynamic and neurohumoral effects of cold pressor test in severe heart failure

Summary. The effect of a cold pressor test (CPT) on haemodynamics in relation to general and regional sympathetic activity and arginin vasopressin (AVP), was studied in eleven patients with severe congestive heart failure (CHF). Compared to an age-matched control group (C), resting arterial plasma noradrenaline (NA) (419 ±77 vs. 182 ±15 pg ml^-1), and adrenaline (A) (142 ±28 vs 54 ±10 pg ml^-1) were higher (P<0.05) in CHF. AVP showed no significant difference (14±4 vs. 9±4 pg ml^-1). During CPT systolic and diastolic blood pressure and systemic vascular resistance increased (P<0.01), as did NA (δ 114±39 pg ml^-1, P<0.01), A (δ 33 ± 10 pg ml, P<0.01) and heart rate (δ 10 beats min^-1, P<0.01). The myocardial v-a difference of NA decreased (P<0.05), but was unchanged across the renal vascular bed during CPT. The a-v difference of NA in the hepatic vascular bed, and fractional extraction of A in the coronary sinus, renal and hepatic vascular beds remained unchanged during CPT. AVP did not change significantly and no change in cardiac index or left ventricular filling pressure was observed during CPT. These data suggest that despite an increased activation of the sympathetic nervous system at rest, a further increase in blood pressure and catecholamines took place during CPT. Thus, the effect of a CPT which activates the central sympathetic system seems not to be altered in patients with severe CHF.     

Forearm metabolism during infusion of adrenaline: comparison of the dominant and non‐dominant arm

Human skeletal muscle metabolism is often investigated by measurements of substrate fluxes across the forearm. To evaluate whether the two forearms give the same metabolic information, nine healthy subjects were studied in the fasted state and during infusion of adrenaline. Both arms were catheterized in a cubital vein in the retrograde direction. A femoral artery was catheterized for blood sampling, and a femoral vein for infusion of adrenaline. Forearm blood flow was measured by venous occlusion strain‐gauge plethysmography. Forearm subcutaneous adipose tissue blood flow was measured by the local ¹³³Xe washout method. Metabolic fluxes were calculated as the product of forearm blood flow and a‐v differences of metabolite concentrations. After baseline measurements, adrenaline was infused at a rate of 0·3 nmol kg^?1 min^?1. No difference in the metabolic information obtained in the fasting state could be demonstrated. During infusion of adrenaline, blood flow and lactate output increased significantly more in the non‐dominant arm (8·12 ± 1·24 versus 6·45 ± 1·19 ml 100 g^?1 min^?1) and (2·99 ± 0·60 versus 1·83 ± 0·43 μmol 100 g^?1 min^?1). Adrenaline induced a significant increase in oxygen uptake in the non‐dominant forearm (baseline period: 4·98 ± 0·72 μmol 100 g^?1 min^?1; adrenaline period: 6·63 ± 0·62 μmol 100 g^?1 min^?1) while there was no increase in the dominant forearm (baseline period: 5·69 ± 1·03 μmol 100 g^?1 min^?1; adrenaline period: 4·94 ± 0·84 μmol 100 g^?1 min^?1). It is concluded that the two forearms do not respond equally to adrenaline stimulation. Thus, when comparing results from different studies, it is necessary to know which arm was examined.     

Experimental studies on the influence of ouabain on ATP, calcium and magnesium in the failing human heart

Abstract. 1. ATP, Ca, Mg determinations from arterial and coronary-venous blood were carried out during routine cardiac catheterization. 2. 10 patients with chronic left heart failure and 10 patients with normal left ventricles were tested. An additional 10 patients with chronic left heart failure were tested only for ATP in arterial and coronary-venous blood. 3. The blood specimens were taken at rest and during physical exertion as well as before and after the administration of ouabain. 4. In coronary-venous blood of chronically failing human hearts ATP is increased during physical exertion (arterial = 0.756 μmol ATP/ml whole blood; coronary-venous = 0.796 μmol ATP/ml whole blood. p < 0.005). The results were reproduced in a second group of 10 patients with left heart failure (arterial = 0.654 μmol ATP/ml whole blood; coronary-venous = 0.693 μmol ATP/ml whole blood. p < 0.0005). 5. After the administration of ouabain this effect is no longer detectable in the same patients. 6. The chronically failing human myocardium absorbs essentially more Ca during physical exertion than the normal myocardium does (arterial = 107.4 μg/ml serum; coronary-vonous = 113.4 μ/ml serum. p < 0.0005). 7. In chronic heart failure there was no uptake of Ca after the administration of ouabain. 8. Differences in Mg uptake and release could not be determined in the failing human heart.     

急性冠脉综合征患者血清同型半胱氨酸和C-反应蛋白水平检测的临床意义

目的测定急性冠脉综合征(ACS)患者血清同型半胱氨酸(Hcy)和C-反应蛋白(CRP)水平,探讨血清Hcy、CRP水平与ACS严重程度的关系。方法将124例ACS患者分为不稳定性心绞痛(UA)组(66例)和急性心肌梗塞(AMI)组(58例),以57名健康体检者作为对照。测定各组血清Hcy、CRP水平,并进行统计学分析。结果血清Hcy水平UA组(16.08±5.17)μmol/L、AMI组(21.67±7.38)μmol/L,与对照组(10.11±4.15)μmol/L比较差异有统计学意义(P<0.05),UA组与AMI组比较,差异有统计学意义(P<0.05)。CRP水平UA组(29.65±15.87)mg/L、AMI组(58.14±21.17)mg/L,与对照组(8.06±4.86)mg/L比较差异有统计学意义(P<0.01),UA组与AMI组比较,差异有统计学意义(P<0.05)。结论 ACS患者血清Hcy、CRP水平显著高于正常人群,测定血清Hcy、CRP水平可能对ACS的预防和治疗监测具有重要临床意义。     

Hypoxanthine production by ischemic heart demonstrated by high pressure liquid chromatography of blood purine nucleosides and oxypurines

An isocratic high pressure liquid Chromatographic system was developed for the estimation of purine nucleosides and oxypurines in blood. Use was made of a reversed-phase column. Nucleotides derived from erythrocytes affected the separation; these compounds were removed with Al₂O₃. The recovery of the whole clean-up procedure exceeded 75%, and the lower detection limit of the assay for blood metabolites was 0.1 μmol/l. In 6 healthy volunteers, non-resting, the following blood concentrations (mean values ± S.D. in μmol/l) were observed: adenosine (< 0.1), inosine (0.2 ± 0.1), hypoxanthine (2.2 ± 1.3) and xanthine (0.2 ±0.1). In plasma and serum the total amount of these compounds was 1.9 and 5.4 times higher, respectively, presumably due to nucleotide breakdown during blood processing. The myocardial arterial-venous differences of blood purine nucleosides, oxypurines and lactate were subsequently measured in blood samples from 13 patients with angiographically documented ischemic heart disease, undergoing an atrial pacing stress test. No significant release of adenosine, inosine and xanthine by the heart was detectable in this study. The myocardial arterial-venous difference of lactate changed from 0.01 ± 0.03 mmol/1 (mean ± SEM) at rest, to ?0.10 ± 0.04 mmol/1 during pacing (p < 0.002). Relatively larger changes were observed for hypoxanthine: pacing increased the arterial-venous difference from ?0.01 ± 0.05 to ?0.51 ± 0.17 μmol/1 (p <0.02). We conclude that the high pressure liquid chromatographic assay of blood hypoxanthine is a useful tool in the diagnosis of ischemic heart disease.     

A kinetic determination of ammonia in plasma

A simple and rapid method is described for the determination of ammonia in plasma without deproteinization, using the enzyme glutamate dehydrogenase and NADPH as coenzyme. ADP is used to stabilize glutamate dehydrogenase.The measuring principle is a kinetic one, determining the reaction rate on the “Enzyrator”. The whole determination takes only 7 min, including the preincubation time.The plasma sample is only 100 μl, which makes it possible to determine the ammonia values in capillary blood. Comparing the values of venous and capillary blood, we found that capillary values are 2–3 times higher than those in venous blood.The normal range for venous plasma NHs was 6.5–35.0 μmol/l. The mean value of non-fasting persons was 22.0 μmol/l.     

Reduction of anti-A and anti-B isoagglutinin titers of group O whole blood units employing an ABO antibody immune adsorption column

BackgroundMassive hemorrhage is a leading cause of death from trauma. There is growing interest in group O whole blood transfusions to mitigate coagulopathy and hemorrhagic shock. Insufficient availability of low-titer group O whole blood is a barrier to routine use. We tested the efficacy of the Glycosorb® ABO immunoadsorption column to reduce anti-A/B titers in group O whole blood.MethodsSix group O whole blood units were collected from healthy volunteers, and centrifuged to separate platelet poor plasma. Platelet-poor plasma was filtered through a Glycosorb® ABO antibody immunoabsorption column, then reconstituted to prepare post-filtration whole blood. Anti-A/B titers, CBC, free hemoglobin, and thromboelastography (TEG) assays were performed on pre-and post-filtration whole blood.ResultsMean( ± SEM) anti-A (224 ± 65 pre vs 13 ± 4 post) and anti-B (138 ± 38 pre vs 11 ± 4 post) titers were significantly reduced (p = 0.004) in post-filtration whole blood. No significant changes were detected in CBC, free hemoglobin, and TEG parameters on day 0. Free hemoglobin increased throughout storage (48 mg/dl ± 24 Day 0 vs 73 ± 35 Day 7 vs 96 ± 44 Day 14; p = 0.14).ConclusionsThe Glycosorb® ABO column can significantly reduce anti-A/B isoagglutinin titers of group O whole blood units. Glycosorb® ABO could be employed to provide whole blood with lower risk of hemolysis and other consequences of infusing ABO incompatible plasma. Preparation of group O whole blood with substantially reduced anti-A/B would also increase the supply of low-titer group O whole blood for transfusion.     

Glutathione and γ-glutamylcysteine in whole blood,plasma and erythrocytes

A method for the simultaneous determination of glutathione and γ-glutamyl-cysteine in capillary blood samples is described.The whole blood levels of glutathione and γ-glutamylcysteine are 1.09 ± 0.20 mmol/l and 25 ± 8 μmol/l (M ± S.D.), respectively. The plasma concentration is approximately 4 μmol/l for both compounds. It is important to treat the blood samples with a reducing agent before protein precipitation to release glutathione and γ-glutamylcysteine from disulfide linkages since, otherwise, 30–40% of the glutathione and 80% of the γ-glutamylcysteine is lost with the protein precipitate. Whole blood is preferable to washed erythrocytes for the analysis since the washing procedure involves losses of, especially, γ-glutamyl-cysteine.     

Serum ferritin,iron status and plasma ascorbic acid in 40- to 49-year-old males in the Faroe Islands

Iron status (haemoglobin, S-ferritin, S-iron, S-transferrin, and transferrin saturation) was evaluated in an epidemiological survey comprising a representative sample of 118 (4%) of the 40- to 49-year-old Faroese male population. All had normal haemoglobin, (mean ±SD 153±9 g/1; 9.5±0.6 mmol/1). Median S-ferritin was 151 ng/1, 5-95 percentile 46-588 u.g/1, observed range 33-1166 Hg/1. None had depleted iron stores (S-ferritin ≥20 ng/1), 2.5% had ‘small’ iron stores (S-ferritin 21-40 ng/1), 80.5% had ‘normal’ iron stores (S-ferritin 41-300 ng/1) and 17% had ‘increased’ iron stores (S-ferritin ≥300 ug/1). Transferrin saturation values were ≥16% in all males; high values ≥50% were found in 9.3%, and the combination of high transferrin saturation and S-ferritin ≥300 μ/l was found in 3.4% of the males. Median P-ascorbic acid was 26 μmol/1, 5-95 percentile 7-67 μmol/1; significantly higher in subjects taking vitamin supplements (n=35, median 50 μmol/1) than in those not taking supplements (n=81, median 23 μmol/1) (p<0.0001). There was no correlation between P-ascorbic acid and iron status markers. The results indicate a high frequency of ample iron reserves in the Faroese male population.     

Plasma nitrate as an index of nitric oxide formation in man: analyses of kinetics and confounding factors

SUMMARY. Nitric oxide (NO) is metabolized to nitrate in humans. Accordingly, plasma nitrate has been proposed as an index of the in vivo formation of NO. Such an application requires knowledge about the possible influence of nitrate from sources other than endogenous NO formation, as well as of the kinetics of nitrate in plasma. In the present study, plasma nitrate increased from 32 ± 4 to 205 ± 27 μmol/1 (mean ± SE) following intake of nitrate-rich food. It dropped during the intake of nitrate-restricted diet and stabilized at a level of 29 ± 1 μmol/1. The urinary excretion of nitrate during nitrate restriction was 840 ± 146 μmol/24 h. Plasma nitrate was not affected following the intake of a gastrointestinal antibiotic drug for a period of four days. Smoking three cigarettes in succession did not affect the plasma nitrate levels significantly. The oral intake of potassium nitrate (500 mg ± 4950 μmol) elevated plasma nitrate from 29 ± 3 to 313 ± 12 μmol/1 within 60 min. The subsequent drop in plasma nitrate, with a t_1/2 of 451 ± 42 min, was probably a reflection of the redistribution of nitrate within the body fluids and the renal excretion of nitrate. The plasma clearance of nitrate was 30 ± 2 ml/min/1.73 m² BSA. The distribution volume for nitrate was 28 ± 1% of the bodyweight (BW). We conclude that plasma nitrate can be used as an index of the endogenous formation of NO, provided that the oral intake of nitrate is restricted for at least 48 h. Due to the large distribution volume and the low clearance of the ion wide-spread, marked, and chronic changes in NO formation are required to significantly affect the levels of nitrate in samples of mixed blood.