Serum glycerophosphate levels are increased in Japanese men with type 2 diabetes

OBJECTIVE

To identify metabolites showing changes in serum levels among Japanese male with diabetes.

METHODS

We performed metabolite profiling by coupling capillary electrophoresis with electrospray ionization time-of-flight mass spectrometry using fasting serum samples from Japanese male subjects with diabetes (n=17), impaired glucose tolerance (IGT; n=5) and normal glucose tolerance (NGT; n=14).

RESULTS

Other than the expected differences in characteristics related to abnormal glucose metabolism, the percent body fat was significantly different among subjects with diabetes, IGT and NGT (27.3±6.2, 22.2±4.5 and 19.2±6.0%, respectively, p=0.0022). Therefore, percent body fat was considered as a possible confounding factor in subsequent analyses. Of 560 metabolites detected using our platform, the levels of 74 metabolites were quantified in all of the serum samples. Significant differences between diabetes and NGT were observed for 24 metabolites. The top-ranked metabolite was glycerol-3-phophate (glycerophosphate), which was significantly higher in subjects with diabetes than in those with NGT, even after Bonferroni correction for multiple testing (11.7±3.6 vs. 6.4±1.9 µM, respectively; corrected p=0.0222). Stepwise multiple regression analyses revealed that serum glycerophosphate levels were significantly correlated with 2-h plasma glucose after a 75-g oral glucose tolerance test (r=0.553, p=0.0005), independently of other characteristics, including FPG and HbA1c.

CONCLUSION

Serum glycerophosphate levels were found to be elevated in Japanese men with diabetes, and correlated with 2-h PG, independent of FPG and HbA1c. Namely, serum glycerophosphate level at fasting condition can be a marker for predicting glucose intolerance. These results warrant further studies to evaluate the relevance of glycerophosphate in the pathophysiology of diabetes.

[Morphological and functional characteristics of lymphocytes of mothers of children with Down syndrome]

Nuclear chromatine of peripheral blood lymphocytes was studied in 13 women with children suffering from Down's syndrome using optic structural computer analysis. In 12 cases significant increase of nuclear roundness coefficient was determined. Deformation coefficient was determined for heterochromatine structures in 8 cases. Integral optic density of nuclear chromatine was significantly decreased in 12 women. This indicates the reduction of felgen-positive material due to deficiency of its compact fraction (in 11 cases). The activity of lymphocyte cytoplasmic lactate, alpha-glycerophosphate and succinate dehydrogenases (SDG) was studied morphocytochemically in 5 women who had children with the disease. High activity of mitochondrial SDG was determined in all cases which probably indicates disorders in lymphocyte energy state. This is one of the reasons for retention of risk pregnancy. Further research in this area may serve as a base for complete cytoanalysis in order to distinguish risk groups among women including primagravida for consequent determination of embryonal karyotype.

Influence of n-6 versus n-3 polyunsaturated fatty acids in diets low in saturated fatty acids on plasma lipoproteins and hemostatic factors

Modification of dietary fat composition may influence hemostatic variables, which are associated with increased risk of coronary heart disease (CHD). To address this question, we performed a controlled feeding study on 26 healthy male nonsmoking subjects with diets of differing fat composition. For the first 3 weeks, the subjects were given a diet calculated to supply 30% energy as total fat: 8% as monounsaturated, 4% as polyunsaturated, and 16% energy as saturated fatty acids, respectively (saturated diet). This was followed immediately by two diets taken in random order, each of 3-week duration and separated by an 8-week washout period on the subject's usual diet. Both diets were calculated to supply 30% of energy as fat: 14% monounsaturated, 6% as polyunsaturated, and 8% energy as saturated fatty acids. They both provided 5 g (approximately 1.7% energy) more of polyunsaturated fatty acids than the saturated fat diet; in one diet as long-chain n-3 fatty acids (n-3 diet) and in the other as linoleic acid (n-6 diet). Fasting plasma lipids, lipoproteins, and hemostatic factors were measured on the final 3 days of each dietary period. In a subset of 9 subjects the postprandial responses to a test meal were studied on the penultimate day of each period, each meal having the fat composition of its parent diet. On the n-3 diet compared with the n-6 diet, plasma triglyceride, HDL3 cholesterol, apoprotein AII, and fibrinogen concentrations were lower and HDL2 cholesterol concentration was higher (P = .0001, P = .003, P = .0001, P = .004, and P = .001, respectively). On both the n-3 and n-6 diets compared with the saturated diet, fasting plasma total and LDL cholesterol, apoprotein B, beta-thromboglobulin concentrations, and platelet counts were lower (P < .0001, P < .0001, P < .001, P < .01, and P < .05 respectively) and plasma Lp(a) and von Willebrand factor concentrations were higher (P = .02 and P < .01, respectively). Fasting factor VII coagulant activity (VIIc) was increased and apoprotein AI concentration reduced following the n-3 diet (P = .004 and P = .01, respectively) compared with the saturated diet. Plasma fibrinogen concentration was significantly greater following the n-6 diet than on the saturated diet (P = .02). Postprandially, plasma triglyceridemia was greater on the n-6 diet and lowest on the n-3 diet (P < .001) with the saturated diet being intermediate. Plasma VIIc was increased at 4 hours following the standardized test meals on the n-3 and n-6 diets (both P < .05) but not on the saturated diet. An increased intake of long chain n-3 fatty acids decreases fasting plasma triglyceride and apoprotein AII concentrations and increases HDL2 cholesterol concentrations and results in less postprandial lipemia but leads to an increase in VIIc. An increased intake of linoleic acid may raise plasma fibrinogen concentration. Decreasing the intake of saturated fatty acids reduces plasma LDL cholesterol and apoprotein B without affecting HDL cholesterol concentration independent of the type of polyunsaturated fatty acids in the diet. When advice is given to reduce saturated fat intake, it is important to ensure an appropriate ratio of n-3/n-6 fatty acids in the diet.

Transverse redistribution of phospholipids during human platelet activation: evidence for a vectorial outflux specific to aminophospholipids

The redistribution kinetics of phospholipids during human platelet activation by calcium ionophore were investigated to determine the specificity of the observed phospholipid outflux [Bassé et al. (1993) Biochemistry 32, 2337]. (1) Two double-labeling experiments were performed with a combination of equal amounts of spin- and fluorescently-labeled phosphatidylserine and phosphatidylcholine. During A23187-induced activation, 50% of the internal phosphatidylserine analogs were rapidly (t1/2 < 1 min) reexposed on the platelet surface while no reciprocal influx of the external phosphatidylcholine analogs was observed. (2) Treatment with chlorpromazine allowed the internalization of 20% of external spin-labeled sphingomyelin or spin-labeled phosphatidylcholine, without either inducing platelet activation or interfering with aminophospholipid translocase activity or with A23187-induced activation (dense granule secretion and vesicle shedding). During A23187-induced activation, none of the previously internalized choline head phospholipids were exposed externally, while spin-labeled phosphatidylserine outward movements were similar irrespective of whether platelets were pretreated or not pretreated with chlorpromazine. Our results demonstrated that during strong platelet activation (1) the PL excess in the internal leaflet, due to the probe addition, is not responsible for their outflux; (2) the rapid aminophospholipid outflux is definitely a vectorial outflux not counterbalanced by a rapid reciprocal influx of choline head phospholipids (i.e., not scrambling); and (3) the vectorial outflux is specific for aminophospholipids since previously internalized sphingomyelin and phosphatidylcholine did not move outward. This suggests that the specific vectorial outflux of aminophospholipids could be catalyzed by a "reverse aminophospholipid translocase" activity.

Interconversion of D-fructose 1,6-bisphosphate and triose phosphates in human erythrocytes

Aldolase and triose phosphate isomerase both display strict specificity towards the enantiomers of [1-3H]glycerone 3-phosphate. The enantiomer generated from D-[1-3H]glyceraldehyde 3-phosphate produces 3HOH in the aldolase reaction, whilst the other enantiomer generated from D-[3-3H]fructose 1,6-bisphosphate is solely detritiated in the reaction catalyzed by triose phosphate isomerase. Advantage was taken of such a specificity to assess, in human erythrocytes exposed to either D-[3-3H]glucose or D-[3,4-3H]glucose, the extent of D-glyceraldehyde 3-phosphate sequential conversion to glycerone 3-phosphate and D-fructose 1,6-bisphosphate, relative to net glycolytic flux. At 37 degrees C and in the presence of 5.6 mM D-glucose, only 55% of the metabolites of D-[4-3H]glucose underwent detritiation in the reactions catalyzed by triose phosphate isomerase and aldolase. Such a percentage was further decreased at low temperature (8 degrees C) or lower concentrations of D-glucose (0.2 and 1.0 mM). However, when the erythrocytes were exposed to menadione, the increase in 3HOH production from either D-[3-3H]glucose or D-[3,4-3H]glucose indicated that the majority of the 3H atoms initially located on the C4 of D-glucose were recovered as 3HOH upon circulation through the pentose phosphate pathway. These findings suggest that, under physiological conditions, a large fraction of D-glyceraldehyde 3-phosphate generated from exogenous D-glucose may undergo enzyme-to-enzyme channelling in the glycolytic pathway.

[Phospholipid-glycerides, cross-resistance of erythrocytes, malonic dialdehyde level and alpha-tocopherol levels in the plasma and erythrocytes of rats with alloxan diabetes before and after combined antioxidant therapy]

Quantitative and qualitative alterations in content of phospholipids were studied in erythrocytes of rats with alloxan diabetes: rate of lipid peroxidation and content of L-tocopherol were estimated in blood plasma before and after the antioxidant therapy. Patterns of lipid metabolism were normalized after the course of treatment involving simultaneous administration of L-tocopherol and ascorbic acid within 10-15 days. The antioxidants used decreased the rate of lipid peroxidation in erythrocyte membranes and stimulated biosynthesis of phospholipids de novo. Role of antioxidants in phospholipid metabolism is discussed.

Choline-linked phosphoglycerides. A source of phosphatidic acid and diglycerides in stimulated neutrophils

Stimulation of human polymorphonuclear leukocytes (PMN) may result in the metabolism of phospholipids other than phosphoinositides to generate second-messenger intermediary metabolites. We investigated agonist-induced breakdown of 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine (1-O-alkyl-2-acyl-GPC), which constitutes almost half the diradyl-GPC fraction in human PMN (Mueller, H. W., O'Flaherty, J. T., Green, D. G., Samuel, M. P., and Wykle, R. L. (1984) J. Lipid Res. 25: 383-388), in cells prelabeled with 1-O-[3H] alkyl-2-acyl-GPC. We also utilized normal-phase high pressure liquid chromatography to quantitate the accumulation of diradylglycerols (1-O-alkyl-2-acylglycerols and diacylglycerols) in stimulated PMN. Phorbol-12-myristate-13-acetate (PMA), 1-oleoyl-2-acetyl-sn-glycerol-, calcium ionophore A23187-, and f-methionyl-leucyl-phenylalanine (fMLP) stimulation of PMN resulted in a time- and concentration-dependent hydrolysis of 1-O-[3H]alkyl-2-acyl-GPC and the formation of 1-O-[3H]alkyl-2-acyl-phosphatidic acid (PA) and 1-O-[3H]alkyl-2-acylglycerol. In all cases formation of 1-O-[3H]alkyl-2-acyl-PA preceded that of 1-O-[3H]alkyl-2-acylglycerol. The times between addition of stimulus and appearance of 1-O-[3H] alkyl-2-acylglycerol varied for PMA (40 s at 1.6 microM), A23187 (5 min at 5 microM), and fMLP (30 sec at 1 microM). Preincubation of cells with 1 microgram/ml pertussis toxin (PT) inhibited the breakdown of 1-O-[3H]alkyl-2-acyl-GPC in cells stimulated with 1 microM fMLP, indicating a role for a PT-sensitive G protein with this stimulus. Quantitation of diglycerides as diradylglycerobenzoates in PMN stimulated with PMA (10 min), A23187 (10 min), or fMLP demonstrated marked accumulation of both 1-O-alkyl-2-acylglycerols and diacylglycerols. The highest increases over controls were observed for fMLP (33-fold for 1-O-alkyl-2-acylglycerols and 17-fold for diacylglycerols). In stimulated PMN prelabeled with 1-O-[3H]hexadecyl-2-acyl-GPC and 1-O-alkyl-2-acyl-sn-glycero-3-[32P]phosphocholine, the ratio of 3H to 32P in 1-O-alkyl-2-acyl-PA compared to 1-O-alkyl-2-acyl-GPC suggested the involvement of a phospholipase D in the hydrolysis of 1-O-[3H]-alkyl-2-acyl-GPC. Thus, stimulation of human PMN results in the hydrolysis of 1-O-[3H]alkyl-2-acyl-GPC to yield 1-O-[3H] alkyl-2-acyl-PA and 1-O-[3H]alkyl-2-acylglycerol possibly initiated by activation of a phospholipase D.(ABSTRACT TRUNCATED AT 250 WORDS)

1-ether-linked phosphoglycerides. Major endogenous sources of arachidonate in the human neutrophil

This study has quantitated changes in the content of labeled and unlabeled arachidonate of neutrophil phosphoglyceride classes and subclasses during cell activation with ionophore A23187. The predominant pools of endogenous arachidonate in the resting neutrophil were found in ethanolamine (68%)-, choline (19%)-, and inositol (12.0%)-containing glycerolipids. Upon stimulation, endogenous arachidonate was lost from primarily ethanolamine (PE) greater than choline (PC) greater than inositol (PI)-linked phosphoglycerides. Released leukotriene B4 and 20-hydroxyleukotriene B4 accounted for 10-35% of the total arachidonate lost from all phosphoglyceride classes. In contrast to the mass loss, ionophore induced a decrease of labeled arachidonate from primarily PC and PI. In the resting neutrophil, 66% of the total arachidonate in PC was found in the 1-alkyl-linked fraction. Furthermore, loss of endogenous arachidonate from 1-alkyl-2-arachidonoyl sn-glycero-3-phosphocholine accounted for 62% of the decrease of arachidonate from choline-linked phosphoglycerides. In contrast, 60% of the release of labeled arachidonate from PC subclasses originated from 1-acyl molecular species. 1-Alk-1'-enyl-2-acyl-sn-glycero-3-PE contained 71% of the arachidonate in ethanolamine-linked phosphoglycerides and was the major PE subclass which was degraded during neutrophil activation with ionophore A23187. These findings demonstrate that human neutrophils contain large ether-linked stores of arachidonate and the capacity to mobilize these stores. In addition, this study points out major discrepancies between using mass or label to determine sources of arachidonate for eicosanoids.

Influences of diet and postnatal age on the lipid composition of red blood cell membrane in newborn infants

The fatty acid and cholesterol contents of tissue membranes are determinants of their stability and functionality. This study was designed to evaluate the influences of diet and postnatal age on the polyunsaturated fatty acid (PUFA) composition of erythrocyte membrane phospholipid fractions and on the red blood cell membrane cholesterol and phosphorus contents in newborn infants during the 1st month of life. A group of infants was fed on human milk and another group on adapted milk formula. Blood samples were obtained at birth, from cord blood, and at 7 and 30 days of age. Long-chain w6 PUFA declined with advancing age in all membrane phosphoglycerides and sphingomyelin (SM) in those infants fed formula. w6 PUFA also decreased in phosphatidylcholine (PC) and phosphatidylserine (PS) in infants fed human milk and were maintained constant in phosphatidylethanolamine (PE) and SM. w3 PUFA were less affected by postnatal age. PE and SM showed significantly higher percentages of w6 and w3 long-chain PUFA in infants fed human milk than in those fed formula. Membrane cholesterol content increased in all infants from birth to 1 month of life but phosphorus levels were unaffected by diet and postnatal age. These results suggest that diets with a low content of long-chain PUFA, such as adapted cow's milk formulas, may induce changes in membrane functionality and that incorporation of PUFA to the diet in amounts similar to those found in human milk should be considered at least in early life.

Effect of dietary fatty acids on experimental manifestation of Salmonella-associated arthritis in rats. II. Effect of dietary fatty acids on experimental manifestation of Salmonella-associated arthritis in rats

Dietary supplementation with a marine lipid concentrate rich in n-3 fatty acids and pure ethyl ester of dihomo-gamma-linolenic acid (DHLA) resulted in inhibition of the chronic phase of inflammation in Salmonella-associated arthritis. The anti-inflammatory effect of DHLA was much stronger than that of two n-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid) present in marine oil. Fatty acid profiles in phosphoglyceride fractions of red blood cells showed incorporation of the respective supplemented fatty acids. Concentrations of 4 cyclooxygenase products in femoral vein plasma were smaller in the fatty acid supplemented rats. These studies suggest that DHLA and marine n-3 fatty acids may have useful anti-inflammatory effects in Salmonella-associated arthritis.

Formation of acetylcarnitine in muscle of horse during high intensity exercise

To study the changes in carnitine in muscle with spring exercise, two Thoroughbred horses performed two treadmill exercise tests. Biopsies of the middle gluteal were taken before, after exercise and after 12 min recovery. Resting mean muscle total carnitine content was 29.5 mmol.kg-1 dry muscle (d.m.). Approximately 88% was free carnitine, 7% acetylcarnitine and acylcarnitine was estimated at 5%. Exercise did not affect total carnitine, but resulted in a marked fall in free carnitine and almost equivalent rise in acetylcarnitine. The results are consistent with a role for carnitine in the regulation of the acetyl-CoA/CoA ratio during sprint exercise in the Thoroughbred horse by buffering excess production of acetyl units.

Metabolism of 3-phosphoglyceroyl phosphate in phosphoenolpyruvate-enriched human erythrocytes

The concentration of 3-phosphoglyceroyl phosphate in erythrocytes was increased by more than 100-fold when red cells were incubated with extracellular phosphoenolpyruvate at 37 degrees C. Since these elevated levels were maintained for 60 min, the metabolism of 3-phosphoglyceroyl phosphate and related compounds could be investigated in phosphoenolpyruvate-treated erythrocytes. 2,3-Bisphosphoglycerate synthesis was not affected by intracellular pH when the 3-phosphoglyceroyl phosphate level was constant but did vary with 3-phosphoglyceroyl phosphate concentration. On the other hand, the relationship between the rate of 2,3-bisphosphoglycerate synthesis and 3-phosphoglyceroyl phosphate concentration was not straightforward. At relatively low concentrations of 3-phosphoglyceroyl phosphate, the observed rate of 2,3-bisphosphoglycerate synthesis agreed with a rate calculated from a formula incorporating kinetic parameters of purified 2,3-bisphosphoglycerate synthase (Rose, Z.B. (1973) Arch. Biochem. Biophys. 158, 903-910). However, at high concentrations of 3-phosphoglyceroyl phosphate, the observed rate of 2,3-bisphosphoglycerate synthesis was lower than the calculated value. The concentration of glucose 1,6-bisphosphate did not increase even when 3-phosphoglyceroyl phosphate was elevated to 200 microM. Elevated levels of intracellular 2,3-bisphosphoglycerate did not inhibit glycolytic activity in these erythrocytes. These results suggest that incubation of erythrocytes with phosphoenolpyruvate is a useful technique to investigate the effect of metabolic perturbations at the intermediate stages of glycolysis.

Highly unsaturated phospholipid molecular species of rat erythrocyte membranes: selective incorporation of arachidonic acid into phosphoglycerides containing polyunsaturation in both acyl chains

This study describes for the first time the complete molecular species composition and turnover of [3H]arachidonic acid in various glycerophospholipid classes of rat erythrocytes, a model system that has been extensively used to investigate numerous membrane phenomena. Quantitative analysis of the individual molecular species of the choline, ethanolamine, serine, and inositol glycerophospholipid classes was possible by preparing their diradylglycerobenzoate derivatives that can be quantitated by on-line uv detection in conjunction with high-performance liquid chromatography; turnover of the molecular species containing arachidonate was evaluated in erythrocytes labeled with [3H]arachidonic acid. A unique observation was the significant amounts of 22:6-20:4, 20:4-20:4, and 18:2-20:4 species observed in the diacyl fractions of phosphatidylethanolamine and phosphatidylserine. Moreover, the analysis of the specific radioactivities of individual phospholipid species from erythrocytes incubated with [3H]arachidonic acid demonstrated a selective incorporation of arachidonic acid into the most highly unsaturated molecular species in all of the phospholipid classes examined. Although the 22:6-20:4, 20:4-20:4, and 18:2-20:4 species represented only 4.5% of the total mass of the diacyl phosphoglycerides, these species accounted for a major portion (37%) of the arachidonic acid incorporated into the phospholipids. These results demonstrate the existence of unique populations of phospholipid molecules in rat erythrocytes with a high degree of unsaturation that exhibit a very rapid metabolic turnover rate.

Characterization of the arachidonate-containing molecular species of phosphoglycerides in the human neutrophil

Neutrophils were labeled with high specific activity, [3H]-arachidonate and separated into their arachidonate-containing phosphoglycerides using a slight modification of the normal phase and reverse phase HPLC described by Patton et al. The individual molecular species of PC, PE and PI containing arachidonate were characterized by fast atom bombardment/mass spectrometry techniques. Eight major arachidonate-containing molecular species of PC, six major arachidonate-containing molecular species of PE and two major arachidonate-containing molecular species of PI could be found. With the structures of the phosphoglycerides eluting from the reverse phase HPLC column known, general trends in the HPLC elution behavior of 1-0-alkyl, 1-alk-1-enyl and 1-acyl-2-arachidonoyl phosphoglycerides could be observed.

Remodeling of arachidonate-containing phosphoglycerides within the human neutrophil

Initial incorporation and subsequent remodeling of 16 phosphoglyceride molecular species containing arachidonate in the human neutrophil have been studied. Neutrophils were pulse-labeled with [3H]arachidonic acid (AA) for 5 min, then phospholipids were analyzed either at this time point or after a subsequent 120-min incubation. [3H]AA was found to be incorporated into phosphoglycerides phosphatidylinositol (PI) greater than phosphatidylcholine (PC) greater than phosphatidylethanolamine (PE) by 5 min. Incorporation of [3H]AA was not related to pool size, but reflected an increase in phosphoglyceride turnover. Following the 120-min incubation, only PE gained a significant amount of labeled arachidonate. Specific activity analysis revealed that PI contained the highest labeled/unlabeled ratio at both 5 min and 120 min. After the initial 5-min pulse, the majority of [3H]arachidonate was incorporated into 1-acyl-2-[3H]arachidonoyl-sn-glycero-3-PC, -PE, and -PI showing no preference for fatty acyl chains at the sn-1 position. However, [3H]AA was remodeled into 1-alkyl-acyl-and 1-alk-1-enyl-acyl-sn-glycero-3-PC and -PE molecular species in those neutrophils incubated for the additional 120 min. Specific activities of [3H]AA within all diacyl molecular species were initially higher relative to those alkyl-acyl and alk-1-enyl-acyl molecular species, but for PC and PE became more uniform as label shifted into ether and plasmalogen pools during the additional 120-min incubation. In contrast, the specific activity of 1-stearoyl-2-arachidonoyl-sn-glycero-3-PI remained constant throughout the 120-min incubation.

Effect of acetylglyceryl ether phosphocholine (platelet-activating factor) and thrombin on acylation of exogenous lysophosphoglycerides in rabbit platelets

Exogenous lysophosphoglycerides such as 1-O-acyl-2-(lyso)-sn-glycero-3-phosphocholine (lysoPC), 1-O-acyl-2-(lyso)-sn-glycero-3-phosphoethanolamine (lysoPE) and 1-O-alkyl-2-(lyso)-sn-glycero-3-phosphocholine (lysoGEPC) radiolabelled on the 1-O-aryl moiety were found to be acylated to the corresponding phosphoglycerides by rabbit platelets at different initial rates and to different extents. LysoPC and lysoGEPC were found to be the best precursors for specifically labelling the corresponding phosphoglyceride pool. Interestingly, synthetic 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC) and thrombin were able to increase the initial rate of acylation of all these lysophosphoglycerides up to 4-6-fold in a concentration-dependent manner. The finding that stimulation of the acylation rate of the various lysophosphoglycerides was relatively independent of the stimuli used supports the hypothesis that this activation could be a new phenomenon associated with the reversible shape change observed in platelets after stimulation with AGEPC or thrombin.

Erythrocyte pyruvate kinase deficiency: characterization of a new variant (PK "Aarau")

A new PK variant with moderate hemolytic anemia is described. The enzymes of the nonanemic parents show sigmoidal reaction kinetics, with normal kinetic parameters, but differ with respect to nucleotide specificity, thermostability, and the concentrations of the glycolytic intermediates in the erythrocytes. The most characteristic features of the patient's (daughter) enzyme are a 30% activity, hyperbolic reaction kinetics and only two bands in the SDS-gel electrophoresis instead of three bands observed with the parental enzymes. Moreover, the pH-optimum is shifted to the acidic range, the affinity for PEP and ADP is decreased, ATP inhibition is negligible and FDP-activation is roughly ten times smaller than with controls. The concentrations of 2,3-DPG, 2-PG and PEP in the erythrocyte are increased, but ATP decreased. As there is no consanguinity in the parents and their enzymes are different this PK mutant can be considered to be compound-heterozygous for two different mutant PK alleles.

Erythrocyte membrane glycerophospholipid organization is normal in multiple sclerosis

The phospholipid composition of erythrocyte membranes from patients with multiple sclerosis (MS) was found to be normal, in agreement with previous reports. The transbilayer asymmetry of the glycerophospholipids in MS red cells was probed using bee venom phospholipase A2 and was also found not to be significantly different from normal. Abnormal membrane glycerophospholipid organisation is therefore not involved in the increased red cell size, osmotic fragility, and electrophoretic mobility associated with MS.

The alkylacyl and alkenylacyl glycerophospholipids of human platelets

The phospholipids of human platelets were isolated and analysed for their constituent 1-0-alkyl- and 1-0-(1'-alkenyl)glycerol species. The serine and inositol phospholipids contained only small amounts (0.5-1.6%) of both alkylacyl and alkenylacyl species; the ethanolamine phospholipids contained little alkylacyl (1.7%) but much more alkenylacyl (45.3%) species, while the choline phospholipids contained 4.5% and 1.4% of these compounds, respectively. Because choline phospholipids amount to 41% of the total phospholipids of human platelets, it appears that they could provide a sufficient supply of alkylacyl glycerophosphocholine for the generation of the alkylacetyl analog (platelet activating factor) by a deacylation-acetylation pathway.

The influence of different types of omega 3 polyunsaturated fatty acids on blood lipids and platelet function in healthy volunteers

1. Five healthy subjects took a daily supplement of 20 ml of linseed oil for 2 weeks. After a break of at least 6 weeks, the same subjects took a similar amount of MaxEPA (a fish oil fraction) for 2 weeks. The linseed oil supplement provided 9.38 g of linolenic acid (18:3 ω3) and the MaxEPA supplement provided 3.03 g of eicosapentaenoic acid (20:5 ω3) and 2.93 g of docosahexaenoic acid (22:6 ω3). The effects of the supplements on plasma lipid concentrations and on the fatty acid composition of platelet phosphoglycerides were studied.

2. In a second experiment, five male subjects took 5, 10 and 20 g of MaxEPA/day in random order for 3 week periods; each experimental period was separated by a break of at least 6 weeks. These doses of MaxEPA provided 0.83, 1.67 and 3.33 g of 20:5 ω3 and 0.80, 1.61 and 3.22 g 22:6 ω3 respectively. The effects of these supplements on plasma lipid concentrations, the fatty acid composition of platelet phosphoglycerides, template bleeding time and platelet aggregation induced by collagen and the prostaglandin analogue compound U46619 were studied.

3. In the platelet lipids, the proportion of 20:5 ω3 was increased by the 20 ml linseed oil supplement but the increase was small compared with the increase brought about by even 5 g of MaxEPA/day. The proportion of arachidonic acid (20:4 ω3) was substantially decreased by the MaxEPA supplement but not by the linseed oil supplement. The ratio of 20:4 ω6/20:5 ω3 fell from 32:1 in the control periods to 11:1 with 5 g, 7:1 with 10 g and 5:1 with 20 g of MaxEPA/day. The MaxEPA supplement also led to increases in the proportions of 22:5 ω3 and 22:6 ω3 and decreases in those of 20:3 ω6 and 22:4 ω6.

4. Bleeding times tended to be prolonged with the MaxEPA supplement but did not follow any dose-dependent trend. Platelet aggregation induced by both collagen and compound U46619 was not inhibited in vitro.

5. Plasma triglyceride concentrations were lowered by the MaxEPA supplement but not by the linseed oil supplement. Plasma triglyceride concentrations were substantially lowered by 10 g and 20 g of MaxEPA/day. Total plasma cholesterol concentrations were slightly lowered and HDL cholesterol concentrations were slightly increased by 20 g of MaxEPA/day. No other significant differences were noted.

Lysophosphoglycerides in ischemic myocardium effluents and potentiation of their arrhythmogenic effects

Lysophosphoglycerides accumulate in ischemic myocardium. To determine whether lysophosphatidylcholine (LPC) concentrations increase in extracellular fluid and may be arrhythmogenic, the anterior descending coronary artery of the open-chest cat (n = 12) was perfused with a Krebs-albumin solution after 10 min of ischemia and the effluent assayed for LPC. A twofold increase in LPC (0.097 +/- 0.02 to 0.170 +/- 0.03 mM) was observed. Microelectrode intracellular recordings from from normal feline endocardium at pH 7.4 in vitro revealed little change in action potentials when superfused with feline plasma despite augmented LPC to twice normal levels (0.74 mM). However, at pH 6.7, marked changes were elicited by LPC-enriched plasma including diminished resting membrane potential (-96 +/- 1 to -35 +/- 7 mV), amplitude (102 +/- 3 to 36 +/- 8 mV), maximum rate of rise (Vmax) of phase 0 (178 +/- 24 to 26 +/- 11 V/s), and conduction velocity with fractionation of the action potential. Acidified control plasma decreased only Vmax (from 161 to 57 V/s). Thus LPC increases twofold in effluents from cat myocardium in vivo after 10 min of ischemia and, coupled with ischemia-induced acidosis, is sufficient to induce marked electrophysiological derangements in vitro.

Effect on blood lipids and haemostasis of a supplement of cod-liver oil, rich in eicosapentaenoic and docosahexaenoic acids, in healthy young men

1. Twelve healthy male subjects took a daily supplement of 20 ml of cod-liver oil for 6 weeks. This provided 1.8 g of eicosapentaenoic acid (20:5 omega 3) and 2.2 g of docosahexaenoic acid (22:6 omega 3). The effects of the supplement on blood lipids, haemostatic variables, bleeding time and plasma vitamin A and carotene were studied. In seven subjects platelet aggregation induced by adenosine 5'-pyrophosphate (ADP) was also studied. 2. The proportions of 20: 5 omega 3 and 22: 6 omega 3 in platelet and erythrocyte phosphoglycerides were substantially increased by the supplement mainly at the expense of omega 6 polyunsaturated fatty acids. 3. Mean plasma triglyceride concentrations were reduced and those of high-density-lipoprotein (HDL) cholesterol were increased by the supplement. 4. The mean bleeding time was significantly prolonged after 3 weeks of taking the supplement, but had returned to the presupplementation value 5 weeks after withdrawal of the supplement. 5. The maximum estimated response to platelet aggregation induced by ADP was increased by the supplement. 6. The mean levels of antithrombin III (immunological) and blood pressure were lower at the end of the period of supplementation and remained so 5 weeks after withdrawal of the supplement. No significant changes in other variables were noted.

[Enzymatic determination of serum glycerophosphatides, using phospholipase C (author's transl)]

A simple method is described for the determination of serum glycerophosphatides, with the exception of lyso-phosphatide. Two determinations are necessary. The usual "triglyceride" determination is performed on native serum, and a further determination is performed after incubation of the serum with phospholipase C. Glycerophosphatides are hydrolysed to diglycerides and phosphorylcholine by phospholipase C. The resulting diglycerides are determined in addition to the mono-, di-, triglycerides and free glycerol of the native serum. The difference between the two glyceride determinations corresponds to the concentration of glycerophosphatides. Involvement of glycerophosphatides in blood coagulation and their increased levels in certain liver illnesses are two reasons for the importance of the present method. Compared with the usual method of measuring phospholipid phosphorus, the present method involves considerably less work, and, as a fully enzymatic method, it has a higher specificity.

[Content of nicotinamide coenzymes, metabolites and the NAD-dependent dehydrogenase activity in the blood in arteriosclerosis]

Study of the key mechanisms, metabolism regulators, showed that in the blood of patients with atherosclerosis the NAD/NAD . N ratio decreases by 59.8% and the NAD+ concentration by 44%, while the NAD . N content increases by 56.7%. In the nicotinamide adenine dinucleotide system there is a general tendency tomards accumulation:the concentration of NADP+ grows by 218.6% and that of NADP . N by 12.9%. A marked increase in the content of incompletely oxidized products is determined: lactic acid by 37.4%, alpha-glycerophosphate by 49.8%, dihydroxyacetone phosphate by 155%, oxaloacetate by 131% in the presence of lactate dehydrogenase and malate dehydrogenase activation. The detected changes are evidence of tissue energy debt in atherosclerosis, they reflect the character of metabolic acidosis formation and point to the presence of conditions for intensified liposynthesis.

Studies in normal pregnancy. III. Fatty acid composition of serum phosphoglycerides and cholesterol esters

Metabolic and hormonal influences on liver lipid synthesis are reflected in the relative fatty acid composition of serum lecithin. Thus, a successive decrease in essential fatty acids (EFA), i.e. n-6 fatty acids, during pregnancy would indicate an incipient EFA deficiency at the time of delivery. Furthermore, reciprocal changes in linoleic and arachidonic acids during the 1st trimester with an increase in arachidonic acid would suggest an enhancement of the Greenbeg Pathway (Pathway II) in lecithin synthesis presumably caused by estrogen influence. During the 2nd and 3rd trimester, reciprocal changes in lecithin content of palmitic and stearic acids are similar to changes appearing under cholestasis. It is furthermore suggested that variations in the utilization of linoleic acid in cholesterol esters (expressed as cholesterol ester 18:2/lecithin 18:2) might reflect changes in plasma cholesterol esterification by the enzyme lecithin-cholesterol-acyl-transferase (LCAT). Then, in late pregnancy, in relation to a subclinical cholestatic liver engagement, LCAT activity would increase as judged from this ratio as well as the increased linoleic acid in cholesterol esters.

A path analysis of the causal relationships between red cell glycolytic intermediates, ADP and ATP in sickle cell anemia

The statistical relationships among the glycolytic intermediates (GI)) of the Embden-Meyerhof pathway, adenine nucleotides (ANs) and various hematological measures were estimated for 34 sickle cell anemia patients. Heterogeneity in linear and quadratic regressions of hemoglobin and hematocrit, both singly and jointly, on the GI and AN variables implied 1) that any single formula to standardize optical density measures of the GIs and ANs on a per gram hemoglobin or per liter cell water basis would not uniformly remove hemoglobin and hematocrit effects: 2) that ignoring significant hematological effects could bias the estimates of correlation among GIs and ANs; and 3) that hemoglobin and hematocrit measures do not reflect the same source of variability. The correlations among the GIs and ANs, after adjustment for hematological variability, were analyzed by path analysis to determine which of five proposed path models for cause and effect relationships were compatible with the data. AMP had a greater influence on ADP (coefficient of determination (CD) = 23%) than all the GIs together, while G6P and ADP influenced ATP variability the most (CD = 33% and 12%). The contributions of unknown factors to ADP and ATP variability were large for all models (CD = 56--77%) possibly due to stress of sickle cell disease. The path model with AMP and the four GIs (G6P, F6P, FDP, DHAP) influencing ADP variation, and the same GIs and ADP influencing ATP was the model most compatible with the data.

Treatment of oral estramustine phosphate (Estracyt) in prostatic carcinoma: influences on lipid and carbohydrate metabolism

Estramustine phosphate (Estracyt), a combination of estradiol and nitrogen mustard given to males with prostatic carcinoma, had the same effect on serum lipids, lipoproteins, and serum phosphoglyceride fatty acid composition as ethynyl estradiol (Etivex). The characteristic effects on serum lipids caused by both drugs, i.e., a reduction in serum cholesterol and an increase in serum phospholipids, were apparently expressions for reduced low density lipoproteins and increased alpha-lipoproteins. Serum lecithin fatty acid composition revealed during the administration of both drugs a characteristic increase in palmitic acid (16:0) and a decrease in stearic acid (18:0), interpreted as evidence for a cholestatic, although subclinical, liver involvement. Similar changes have earlier been revealed in women given ethynyl estradiol; however, the increase in serum triglycerides and very low density lipoprotein cholesterol in young women was not duplicated in aged males with prostatic carcinoma. Furthermore, in aged males, the administration of these estrogens did not change carbohydrate metabolism but did produce an increase in adipose tissue lipoprotein lipase.

[Adaptive metabolic disorders in erythrocytes during shock]

In patients with shock the metabolic activity of the red blood cells was studied following separation according to cell-age by density layer centrifugation using Stractan II-Urografin solutions. Metabolic acidosis in patients with cardiogenic shock (n = 8) and with postoperative shock (n = 7) induced a pronounced fall in 2,3-diphosphoglycerate (2,3-DPG) levels and in adenosine triphosphate (ATP), in contrast to a raised lactate-pyruvate ratio. 2,3-DPG values were higher than normal in patients with hypoglycemic shock (n = 12), whereas further measured substrate levels were markedly decreased. The levels of these compounds of the red blood cells revealed a significant difference in the hemolysates derived from cells separated according to cell-age. The shock syndrome was also observed in patients suffering from severe congestive heart failure (n = 10) who received dopamine (300 mug/min) for its known action in improving hemodynamics and renal function. Following drug administration for 150 min a clinical improvement was associated with a change of extent and pattern of the red blood cell metabolic disorder.