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This study was undertaken to compare Intralipid® with a new fat emulsion containing gamma-linolenic acid and carnitine, named Pediatric Fat Emulsion 4501, in neonates with regard to lipid and carnitine metabolism over a short period of total parenteral nutrition. There were 10 neonates in each group and they tolerated the total parenteral nutrition well. In spite of the gamma-linolenic acid supplementation in the new emulsion, arachidonic acid decreased significantly in plasma lipid esters and adipose tissue in both groups after 5 d of treatment. Also, there was a decrease in plasma docosahexaenoic acid which was more pronounced in the treatment group. The relative percentage values of linoleic and linolenic acids in adipose tissue were increased, indicating that newborns have a rapid accretion of fatty acids. Plasma triglycerides were effectively cleared during the periods without fat infusion. In the group that received Pediatric Fat Emulsion 4501 the means of both free and total plasma carnitine concentrations increased significantly, whereas they tended to decrease in the Intralipid® group.

Laboratory and non-laboratory methods for assessing protein-energy nutritional status are reviewed. These are classified into methods for assessing adequacy of recent nutritional intake, methods for assessing whole body status, and tests which assist in the interpretation of these assessments. Each measurement is critically discussed in terms of the rationale for its use, the method of analysis, reference values, technical interference and limitations of methods, the effects of nutritional status and of other factors on the results, its overall usefulness in nutritional assessment, and its value relative to other methods. Non-laboratory tests such as dietary assessment, indirect calorimetry, functional tests and the many methods available for assessment of body composition, including anthropometry, bioelectrical impedance and isotope and imaging techniques, are compared with the clinical chemistry tests in common use, such as nitrogen balance, plasma protein measurements and urinary markers of muscle metabolism. This review provides comprehensive and practical advice on the use and limitations of these tests in the assessment of protein-energy nutritional status of a group, or of an individual patient.

The effect of dietary creatine and supplementation on skeletal muscle creatine accumulation and subsequent degradation and on urinary creatinine excretion was investigated in 31 male subjects who ingested creatine in different quantities over varying time periods. Muscle total creatine concentration increased by approximately 20% after 6 days of creatine supplementation at a rate of 20 g/day. This elevated concentration was maintained when supplementation was continued at a rate of 2 g/day for a further 30 days. In the absence of 2 g/day supplementation, total creatine concentration gradually declined, such that 30 days after the cessation of supplementation the concentration was no different from the presupplementation value. During this period, urinary creatinine excretion was correspondingly increased. A similar, but more gradual, 20% increase in muscle total creatine concentration was observed over a period of 28 days when supplementation was undertaken at a rate of 3 g/day. In conclusion, a rapid way to "creatine load" human skeletal muscle is to ingest 20 g of creatine for 6 days. This elevated tissue concentration can then be maintained by ingestion of 2 g/day thereafter. The ingestion of 3 g creatine/day is in the long term likely to be as effective at raising tissue levels as this higher dose.

In experimental animals the enhancement of hepatic fatty acid oxidation and ketogenic capacity is accompanied by a rise in the concentration of liver carnitine. Massive obesity is characterized by enhanced fatty acid turnover, insulin resistance, and often a fatty liver. Carnitine concentrations were determined in liver, abdominal muscle tissue, and blood in morbidly obese women. The liver and muscle carnitine concentrations were significantly higher in the obese subjects than in the lean control subjects. These findings suggest an increase of the whole-body carnitine pool. In the obese subjects there was also a significant positive correlation between liver and muscle carnitine concentrations. In the majority of the obese subjects fatty changes could be demonstrated in the liver. The plasma insulin concentration tended to be positively correlated with the degree of fat infiltration and negatively correlated with the liver carnitine content. It is concluded that the liver carnitine content is significantly increased in obese women, which agrees with the finding in experimental animals.

Pyruvate dehydrogenase activity (PDHa) and acetyl group accumulation were examined in human skeletal muscle at rest and during exercise after different diets. Five males cycled at 75% of maximal O2 uptake (VO2 max) to exhaustion after consuming a low-carbohydrate diet (LCD) for 3 days and again 1-2 wk later for the same duration after consuming a high-carbohydrate diet (HCD) for 3 days. Resting PDHa was lower after a LCD (0.20 +/- 0.04 vs. 0.69 +/- 0.05 mmol.min-1.kg wet wt-1; P < 0.05) and coincided with a greater intramuscular acetyl-CoA-to-CoASH ratio, acetyl-CoA content, and acetylcarnitine content. PDHa increased during exercise in both conditions but at a lower rate in the LCD condition compared with the HCD condition (1.46 +/- 0.25 vs. 2.65 +/- 0.23 mmol.min-1.kg wet wt-1 at 16 min and 1.88 +/- 0.20 vs. 3.11 +/- 0.14 at the end of exercise; P < 0.05). During exercise muscle acetyl-CoA and acetylcarnitine content and the acetyl-CoA-to-CoASH ratio decreased in the LCD condition but increased in the HCD condition. Under resting conditions PDHa was influenced by the availability of fat or carbohydrate fuels acting through changes in the acetyl-CoA-to-CoASH ratio. However, during exercise the activation of PDHa occurred independent of changes in the acetyl-CoA-to-CoASH ratio, suggesting that other factors are more important.

The activity of pyruvate dehydrogenase complex (PDC) was studied in the human quadriceps femoris muscle during isometric contraction induced by intermittent electrical stimulation at 20 Hz. Muscle biopsy samples were obtained at rest and after 10, 20, and 46 contractions. The active form of PDC (PDCa) increased from a mean value of 26% of the total PDC at rest to mean values of 46, 78, and 80%, respectively. Muscle biopsy samples were also obtained at rest, after 46 contractions with limb blood flow intact or occluded, and after 2 min of oxidative recovery. In another experiment, muscle biopsy samples were obtained at rest, after 10 min of resting ischemia, and after 46 contractions with limb blood flow occluded. The transformation of PDC to PDCa was nearly complete, regardless of whether the blood flow was intact or occluded. However, the accumulation of acetyl groups observed during stimulation with intact blood flow was abolished when the blood flow was occluded. The absence of NADH oxidation during anoxia had no effect on the contraction-induced transformation of PDC to PDCa, but it inhibited the flux through the enzyme reaction.

We determined carnitine concentrations in blood and in liver and abdominal muscle biopsy specimens in 13 men and 16 women undergoing elective surgery (mostly gallbladder removal). The data suggest that the carnitine pools of plasma and erythrocytes are different. The erythrocytes show a higher acylcarnitine concentration than does plasma (P < 0.001). Several reference bases for values in tissues have been used--dry weight, noncollagen protein (NCP), and DNA--because these may be differently influenced by disease. In liver specimens, the quotient NCP (g)/DNA (g) was significantly higher in men, 54.4 +/- 6.3 (mean +/- SD), than in women, 47.7 +/- 7.0 (P < 0.01). Liver total carnitine content in relation to DNA was significantly higher in men than in women: 0.29 +/- 0.06 vs 0.22 +/- 0.08 mmol/g DNA (P < 0.01). Free carnitine content was significantly higher in men than in women independently of the reference base, e.g., 3.7 +/- 1.0 mumol/g NCP for men vs 2.9 +/- 1.0 for women (P < 0.05). No difference was found between the sexes in the abdominal muscle carnitine content, 20.6 +/- 6.7 mumol/g NCP for men vs 17.9 +/- 5.0 for women. Our study establishes control ranges, thereby providing an important basis for studies of patients with abnormal carnitine metabolism.

The changes in the muscle contents of CoASH and carnitine and their acetylated forms, lactate and the active form of pyruvate dehydrogenase complex were studied during incremental dynamic exercise. Eight subjects exercised for 3-4 minutes on a bicycle ergometer at work loads corresponding to 30, 60 and 90% of their VO2max. Muscle samples were obtained by percutaneous needle biopsy technique at rest, at the end of each work period and after 10 minutes of recovery. During the incremental exercise test there was a continuous increase in muscle lactate, from a basal value of 4.5 mmol kg-1 dry weight to 83 mmol kg-1 at the end of the final period. The active form of pyruvate dehydrogenase complex increased from 0.37 mmol acetyl-CoA formed per minute per kilogram wet weight at rest to 0.80 at 30% VO2max, 1.28 and 1.25 at 60 and 90% VO2max, respectively. Both acetyl-CoA and acetylcarnitine increased at the two highest work loads. The increase of acetyl-CoA was from 12.5 mumol kg-1 dry weight at rest to 27.3 after the highest work load and for acetylcarnitine from 6.0 mmol kg-1 dry weight to 15.2. The CoASH and free carnitine contents fell correspondingly. There was a close relationship between acetyl-CoA and acetylcarnitine accumulation in muscle during exercise, with a binding of approximately 500 mol acetyl groups to carnitine for each mole of acetyl-CoA accumulated. The results imply that the carnitine store in muscle functions as a buffer for excess formation of acetyl groups from pyruvate catalyzed by the pyruvate dehydrogenase complex.

To analyse the effects of L-carnitine supplemented TPN on lipid, energy and nitrogen metabolism, 16 severely injured patients were studied during the first 8 days after trauma. An L-carnitine solution (3g = 18.6mmol) was added to the fat emulsion and infused over 16h in a blind randomised fashion to half of the patients. Plasma triglyceride, free fatty acid and 3-OH-butyrate concentrations increased during the fat infusion, and fell to pre-infusion concentrations within 24h. There were no differences in plasma levels before, during or after infusion between the groups. ATP and phosphocreatine in muscle tissue were not influenced by carnitine supplementation. Glycogen, however, remained unchanged in the carnitine group and fell in the non-carnitine group. A cumulative N-balance measured from day 2 to day 8 was equally negative in both groups. Plasma carnitine levels were significantly higher in the supplemented group from day 3. The mean daily urinary carnitine excretion was increased 15-fold in the supplemented group. Muscle carnitine, however, remained unchanged in both groups and did not differ between them. The present results do not demonstrate any beneficial effects of parenterally administered L-carnitine on lipid, energy or nitrogen metabolism except for maintaining normal muscle glycogen levels in critically ill patients receiving TPN during the early phase after trauma.

The effect of L-carnitine (C) supplementation on body C balance, muscle C concentration, the leg exchange of C and some amino-acids was investigated in 8 patients with persistent post-operative infection. Before supplementation, total C concentration was 81 +/- 13 micromol/l plasma (SEM) and 15.4 +/- 1.5 micromol/g dry weight muscle, urinary excretion was 19 +/- 4 micromol/kg x 24 h and the arterial-femoral venous concentration difference over the leg (A-FV) of free C was -2.90 +/- 0.97 micromol/l, p0.05. Plasma-free C concentration correlated inversely with the A-FV of free C. The excretion of free C in urine was directly related to the plasma-free C concentration. A total C dose of 110 mg/kg during 4 days resulted in a 30% retention (range 12-48), a doubling of plasma C levels but no measurable alteration in either muscle C content or the arterial concentration and exchange of amino-acids over the leg. Plasma-free C concentration correlated inversely with the clearance of creatinine. In patients with persistent post-operative infection, muscle C concentration was normal and C was released from muscle as a consequence of muscle catabolism. The rate of C release was a major determinant of the plasma C concentration. At normal or low plasma C levels, the renal tubular reabsorption of C was a major determinant of body C balance. At elevated plasma concentrations of C, such as during C supplementation, the tubular capacity for reabsorption is exceeded and body carnitine balance is mainly dependent on the glomerular filtration.

L-Carnitine concentration was determined in vastus lateralis and abdominal rectus muscle tissue from 15 patients with diabetes mellitus and 66 controls. Nine of the diabetics were treated with diet and hypoglycemic drugs only and six with insulin. The carnitine concentration was determined enzymatically with labeled [I-14C] acetyl-coenzyme-A as a substrate and given per weight of non-collagen protein. The concentration in muscle tissue did not differ significantly between patients and controls. Patients with insulin-treated diabetes had the same concentration of carnitine in muscle tissue as those treated with hypoglycemic drugs. The drastic decreases in carnitine muscle concentration and in carnitine body pool seen in alloxan-diabetic rats are not observed in skeletal muscle of diabetic humans.

Laboratory and non-laboratory methods for assessing protein-energy nutritional status are reviewed. These are classified into methods for assessing adequacy of recent nutritional intake, methods for assessing whole body status, and tests which assist in the interpretation of these assessments. Each measurement is critically discussed in terms of the rationale for its use, the method of analysis, reference values, technical interference and limitations of methods, the effects of nutritional status and of other factors on the results, its overall usefulness in nutritional assessment, and its value relative to other methods. Non-laboratory tests such as dietary assessment, indirect calorimetry, functional tests and the many methods available for assessment of body composition, including anthropometry, bioelectrical impedance and isotope and imaging techniques, are compared with the clinical chemistry tests in common use, such as nitrogen balance, plasma protein measurements and urinary markers of muscle metabolism. This review provides comprehensive and practical advice on the use and limitations of these tests in the assessment of protein-energy nutritional status of a group, or of an individual patient.

Protein energy malnutrition (PEM) is widespread throughout the world in both community and hospital settings. Assessment of PEM in an individual consists of good dietary and clinical assessment, followed by laboratory measurements. Recent changes in body weight and simple anthropometric measurements are also useful. Laboratory measurements have the advantage in that they are independent of body size, they can be made precisely, and allow monitoring of progress. However, laboratory measurements must be interpreted with caution, especially in seriously ill patients in the hospital.

We determined carnitine concentrations in blood and in liver and abdominal muscle biopsy specimens in 13 men and 16 women undergoing elective surgery (mostly gallbladder removal). The data suggest that the carnitine pools of plasma and erythrocytes are different. The erythrocytes show a higher acylcarnitine concentration than does plasma (P0.001). Several reference bases for values in tissues have been used--dry weight, noncollagen protein (NCP), and DNA--because these may be differently influenced by disease. In liver specimens, the quotient NCP (g)/DNA (g) was significantly higher in men, 54.4 +/- 6.3 (mean +/- SD), than in women, 47.7 +/- 7.0 (P0.01). Liver total carnitine content in relation to DNA was significantly higher in men than in women: 0.29 +/- 0.06 vs 0.22 +/- 0.08 mmol/g DNA (P0.01). Free carnitine content was significantly higher in men than in women independently of the reference base, e.g., 3.7 +/- 1.0 mumol/g NCP for men vs 2.9 +/- 1.0 for women (P0.05). No difference was found between the sexes in the abdominal muscle carnitine content, 20.6 +/- 6.7 mumol/g NCP for men vs 17.9 +/- 5.0 for women. Our study establishes control ranges, thereby providing an important basis for studies of patients with abnormal carnitine metabolism.

Seven subjects cycled to exhaustion [58 +/- 7 (SE) min] at approximately 75% of their maximal oxygen uptake (VO2max). Needle biopsy samples were taken from the quadriceps femoris muscle at rest, after 3, 10, and 40 min of exercise, at exhaustion, and after 10 min of recovery. After 3 min of exercise, a nearly complete transformation of the pyruvate dehydrogenase complex (PDC) into active form had occurred and was maintained throughout the exercise period. The total in vitro activated PDC was unchanged during exercise. The muscle concentration of acetyl-CoA increased from a resting value of 8.4 +/- 1.0 to 31.6 +/- 3.3 mumol/kg dry wt at exhaustion and that of acetylcarnitine from 2.9 +/- 0.7 to 15.6 +/- 1.6 mmol/kg dry wt. This was accompanied by corresponding decreases in reduced CoA (CoASH) from 45.3 +/- 3.1 to 25.9 +/- 3.1 mumol/kg dry wt and in free carnitine from 18.8 +/- 0.7 to 5.7 +/- 0.5 mmol/kg dry wt. Acetyl group accumulation, in the form of acetyl-CoA and acetylcarnitine, was maintained throughout exercise to exhaustion while the glycogen content decreased by 90%. This suggests that availability of acetyl groups was not limiting to exercise performance despite the nearly total depletion of the glycogen store. The increased acetyl-CoA-to-CoASH ratio during exercise caused inhibition of neither the PDC transformation nor the calculated catalytic activity of active PDC.

This study was designed to examine the effects of stimulation and fat availability on the contents of acetyl coenzyme A (acetyl-CoA), free CoA (CoASH), acetylcarnitine, and free carnitine in the oxidative fiber types of rat skeletal muscle. Hindlimb muscles were perfused with no exogenous free fatty acids (FFA) or high FFA (0.93 +/- 0.03 mM) for 10 min at rest and during isometric, tetanic stimulation. Soleus (SOL) and red gastrocnemius (RG) muscles were sampled prior to perfusion and following rest perfusion and 1 and 5 min of stimulation. The SOL muscle contains predominantly slow oxidative (SO) fibers and the RG contains 56% fast oxidative-glycolytic (FOG) and 35% SO fibers. O2 uptake and tetanic tension production were similar in the fat-free and high FFA treatments. Rest perfusion with high FFA increased acetyl-CoA from 14.6 +/- 1.0 to 20.1 +/- 2.5 nmol/g dry muscle (dm) and acetylcarnitine from 0.12 +/- 0.01 to 0.78 +/- 0.18 mumol/g dm in the RG, while fat-free perfusion had no effect. The SOL results were similar as high FFA increased acetyl-CoA from 7.7 +/- 1.0 to 14.2 +/- 3.1 nmol/g dm and acetylcarnitine from 0.14 +/- 0.02 to 0.49 +/- 0.09 mumol/g dm. Stimulation increased acetyl-CoA and acetylcarnitine to values above rest in SOL and RG in both treatments and removed all fat-free and high-fat differences. The decreases in CoASH and free carnitine were reciprocal to the increases in acetyl-CoA and acetylcarnitine at all time points in both muscles such that total CoA and carnitine were constant.(ABSTRACT TRUNCATED AT 250 WORDS)

We examined the effects of a high-caffeine dose on endurance performance and muscle acetyl group metabolism during prolonged exercise. Eight subjects cycled to exhaustion at approximately 80% maximal oxygen uptake (VO2max) 1 h after ingestion of 9 mg/kg body wt dextrose (Pl) or caffeine (Caf). In the Pl trial, muscle biopsies were taken at rest (1 h postingestion) and at 15 min and exhaustion during exercise. The Caf trial followed the same protocol 1 wk later, with an additional biopsy at the time corresponding to Pl exhaustion. The subjects cycled significantly longer during the Caf trial (96.2 +/- 8.8 min) than in the Pl trial (75.8 +/- 4.8 min). Net glycogenolysis during the initial 15 min of cycling was reduced in the Caf vs. Pl trial (4.7 +/- 1.5 vs. 10.6 +/- 1.3 mmol.kg dry muscle-1.min-1; P less than 0.05). Muscle citrate concentration was increased at rest with Caf (0.59 +/- 0.07 vs. 0.37 +/- 0.05 mmol/kg dry muscle; P less than 0.05) but increased to similar values in both trials during cycling. Caf elevated the acetyl-CoA/CoA-SH ratio at rest (0.316 +/- 0.046 vs. 0.201 +/- 0.023; P less than 0.05) but had no effect on the increases in muscle acetyl-CoA and acetylcarnitine during exercise. The results indicate that Caf before exercise decreased muscle glycogenolysis by approximately 55% over the first 15 min of exercise at approximately 80% VO2max. This "spared glycogen" was available late in exercise and coincided with a prolonged time to exhaustion. Increased utilization of intramuscular triacylglycerol and/or extramuscular free fatty acids after caffeine ingestion may inhibit carbohydrate use at rest and early during exercise via elevations in muscle citrate and the acetyl-CoA/CoA-SH ratio. Muscle acetyl-CoA and acetylcarnitine were maintained above resting contents even at exhaustion when muscle glycogen was depleted.

A radioactive assay for the determination of pyruvate dehydrogenase complex activity in muscle tissue has been developed. The assay measures the rate of acetyl-CoA formation from pyruvate in a reaction mixture containing NAD+ and CoASH. The acetyl-CoA is determined as [14C]citrate after condensation with [14C]-oxaloacetate by citrate synthase. The method is specific and sensitive to the picomole range of acetyl-CoA formed. In eleven normal subjects, the active form of pyruvate dehydrogenase (PDCa) in resting human skeletal muscle samples obtained using the needle biopsy technique was 0.44 +/- 0.16 (SD) mumol acetyl-CoA.min-1.g-1 wet wt. Total pyruvate dehydrogenase complex (PDCt) activity was determined after activation by pretreating the muscle homogenate with Ca2+, Mg2+, dichloroacetate, glucose, and hexokinase. The mean value for PDCt was 1.69 +/- 0.32 mumol acetyl-CoA.min-1.g-1 wet wt, n = 11. The precision of the method was determined by analyzing 4-5 samples of the same muscle piece. The coefficient of variation for PDCa was 8% and for PDCt 5%.

Total and free carnitine and acylcarnitine concentrations were analyzed in whole blood and plasma in 12 children with a mean age of 68.4 +/- 42.9 months who had received carnitine-free total parenteral nutrition (TPN) for an average of 4 years. The purpose of the study was to see if the children had become carnitine deficient and, if so, whether this correlated with poor lipid clearance. Compared to controls, the TPN-dependent children had significantly decreased concentrations of total and free carnitine in blood (26.6 +/- 9.4 (SD) mumols/L vs. 43.3 +/- 9.1 mumols/L, p less than 0.001, and 17.1 +/- 7.7 mumols/L vs. 35.2 +/- 8.1 mumols/L, p less than 0.001, respectively). Similar results were found in plasma (total carnitine of 19.0 +/- 8.0 mumols/L vs. 41.9 +/- 5.2 mumols/L, p less than 0.001, and free carnitine of 15.7 +/- 7.3 mumols/L vs. 36.1 +/- 5.2 mumols/L, p less than 0.001, respectively). The acylcarnitine concentration in plasma was decreased in the TPN children (3.3 +/- 1.5 mumols/L vs. 5.8 +/- 3.0 mumols/L, p less than 0.01) compared to controls. Despite the low carnitine concentrations, serum triglyceride levels and serum free fatty acid levels were within the normal range. There was no correlation between carnitine concentrations in plasma and serum triglyceride and free fatty acid levels. Our data show that children receiving carnitine-free TPN for many years developed markedly decreased concentrations of carnitine in blood and plasma. However, no adverse effects of the low carnitine levels were found on triglyceride and free fatty acid metabolism under stable conditions.

The effects of carnitine supplementation on fat and glucose metabolism and carnitine balance were studied in 12 preterm neonates receiving full or partial parenteral nutrition (PN) for 5 to 21 days. The gestational age ranged from 27 to 32 weeks and the birth weight from 790 to 2090 g. The neonates were assigned at random to receive either L-carnitine 10 mg/kg (n = 6) or saline (n = 6). In the carnitine group, increased concentrations in plasma of total and free carnitine were observed. Less than 50% of the given dose was recovered in urine. In the placebo group no changes in the total plasma carnitine concentration were seen. In all neonates plasma triglycerides, free fatty acids, glycerol, alanine, 3-hydroxybutyrate (BOB), glucose and lactate were measured at predetermined intervals. The only significant difference between the groups was higher BOB-concentrations in the carnitine group 2 days after the start of parenteral nutrition. Elevated BOB concentrations are an indicator of improved fatty acid oxidation in the carnitine group. In this study, only a temporary effect of the carnitine supplementation was found.

Treadmill exercise of 2-min duration and increasing intensity resulted in increased formation of acetyl-CoA and acetylcarnitine in working muscle of Thoroughbred horses. At high work intensities a plateau was reached for both acetyl-CoA (approximately 50 mumols/kg dry muscle) and acetylcarnitine (approximately 20 mmol/kg dry muscle). Postexercise concentrations were significantly (P less than 0.001) correlated; [acetylcarnitine] = 349.[acetyl-CoA] + 2.4. The results indicate that approximately 350 mumols acetylcarnitine were accumulated for every 1 mumol acetyl-CoA. Under the conditions of exercise used it is probable that most of the acetyl-CoA formed is generated through the intramitochondrial decarboxylation of pyruvate. The acetyl groups of acetyl-CoA are apparently redistributed throughout the whole cell through formation of acetylcarnitine, which readily transverses the mitochondrial membrane. Despite the redistribution, however, the close correlation between acetylcarnitine and acetyl-CoA would indicate that equilibrium was maintained and that neither acetylcarnitine transferase nor carnitine/acetylcarnitine translocase were rate limiting. There is some question as to whether the changes observed relate directly to exercise itself or to the state in muscle 10 s or more after exercise.

Carnitine is necessary for the transport of long-chain fatty acids across the mitochondrial membrane. Thirteen severely injured patients on total parenteral nutrition were studied during days 2-8 post injury. Initially plasma and skeletal muscle carnitine values were within the range earlier found for normal subjects, whereas the urinary carnitine excretion was markedly increased. On day 4 there was a simultaneous decrease in the carnitine concentration in plasma (alpha < 0.01) and urine (alpha < 0.05) as well as in skeletal muscle tissue (alpha < 0.05 using only the values that could be paired i.e. from eight subjects), whereas no difference was found between day 2 and 8. One explanation of this pattern might be that a redistribution of carnitine occurs to other organs not measured, for example the liver. In skeletal muscle tissue, statistically significant positive correlations were found between the carnitine level and ATP (alpha < 0.01) and phosphocreatine (alpha < 0.02) as well as between carnitine and glycogen (alpha < 0.05).

The metabolic and morphologic adaptation to physical training in skeletal muscle tissue of eleven middle-aged, physically untrained men was studied. Muscle biopsies were taken from the vastus lateralis before, after 8 weeks and after 6 months of physical training for analysis of metabolic and morphologic variables. Glucose tolerance test indicated increased insulin sensitivity after 6 months of physical training. The activities of glycogen phosphorylase, hexokinase and glucose-6-P-dehydrogenase were increased but other enzymes involved in glycogen turnover and glycolysis were unchanged after 6 months of physical training. The activities of citrate synthase and cytochrome-c-oxidase, representing the oxidative capacity were significantly increased already after 8 weeks of physical training. The incorporation rate of palmitate-carbon into CO2 and triglycerides increased, and the incorporation rate of leucine-carbon into CO2 decreased with 6 months of physical training. The fiber diameter of both Type 1- and Type 2-fibers increased, while the mitochondrial volume increased predominantly in Type 2-fibers. Significant correlations were found between metabolic, physiologic and morphologic variables before and after physical training. The results indicate an increased oxidative capacity, mainly located to Type 2-fibers, and an increased utilization of fatty acids in response to this type of physical training.

A group of women with excessive menstrual blood loss (menorrhagia) without any known local or general underlying disease was studied and compared to a group of women with normal menstrual blood loss. Blood coagulation, platelet function and fibrinolysis as well as a variety of plasma proteins were analyzed on six occasions during one menstrual cycle. Women with menorrhagia were found to have a slightly higher concentration of fibrinogen--fibrin degradation products, a higher factor V and VIII activity, higher antithrombin III, alpha 1-antitrypsin concentrations and higher antifibrinolytic activity than the normal women. The concentration of albumin, beta IE-globulin, orosomucoid, ceruloplasmin and IgG were lower in women with memorrhagia than in normals. The capillary fragility did not differ significantly between the groups. The observed differences in clotting factors between the groups could not have caused the differences in blood losses.Blood coagulation factors, platelet function, fibrinolysis, and levels of plasma proteins were determined on 6 occasions during a single menstrual cycle in a group of women suffering from menorrhagia and in normally menstruating controls. Patients with menorrhagia had a slightly higher concentration of fibrinogen-fibrin degradation products, elevated factor 5 and 7 activity, increased antithrombin 3 and alpha(1)-antitrypsin concentrations, and higher antifibrinolytic activity than the control group. Subjects with menorrhagia also had lower concentrations of albumin, beta(IE)-globulin, orosomucoid, ceruloplasmin and IgG compared with controls. There was no marked difference in capillary fragility between the 2 groups. The differences in blood losses between the groups is not attributable to differences in clotting factors.

When studying the correlation between the change of a variable during treatment and the value before treatment, random errors (errors of measurement as well as intra-individual biological variation) may yield seriously biased results. In the present work a method to adjust for this bias is presented. The method was applied to data from blood coagulation factor and plasma protein analyses in chronic alcoholics before and after one week of abstinence. It was found that many of the significant correlations were lost when the data were adjusted.

Urinary excretion of carnitine was studied in 14 patients with burns. Both free and total carnitine were monitored during an 8-day period following the burn and in some of the patients during a longer period of time. The mean value of total urinary carnitine was increased six-fold on day 2 compared with controls. The mean values decreased during the 8-day period post burn although they were still significantly higher on the eighth day compared to the mean value of controls. Increased carnitine excretion was also observed after the first post-traumatic week. A significant relationship was found between the percentage burned surface area and the individual mean value of carnitine excretion during the 8-day period. The percentage of free carnitine in urine was higher in the patients than in the normal subjects. A significant negative correlation was found for the regression of the ratio of acyl carnitine to free carnitine and total carnitine in urine both in the patients and in the controls.

The pharmacokinetics of single intravenous and oral doses of L-carnitine 2 and 6 g was studied in 6 healthy subjects on a low-carnitine diet. Carnitine was more rapidly eliminated from plasma after the 6 g dose. Comparing the doses, the t1/2 beta of the elimination phase (beta) was 6.5 h vs 3.9 h, the elimination constant 0.40 vs 0.50 h-1 and the plasma carnitine clearance was 5.4 vs 6.11.h-1 for the 2 g and 6 g doses, respectively, showing dose-related elimination. Saturable kinetics were not found. The apparent volumes of distribution after the two doses were not significantly different and were of the same order as the total body water. Urinary recoveries of the 2 g and 6 g doses were 70% and 82%, respectively, during the first 24 h. Following the oral doses, there was no significant difference between the areas under the plasma carnitine concentration-time curves. Urinary recovery was 8% and 4% for the 2 g and 6 g doses during the first 24 h. Oral bioavailability was 16% for the 2 g dose and 5% for the 6 g dose. The results suggest that the mucosal absorption of carnitine was already saturated by the 2 g dose.

The effect of L-carnitine on FFA turnover and regional utilisation over the leg was investigated using infusion of 14C-oleic acid and measurement of the respiratory quotient (RQ) in eight artificially ventilated patients with severe post-operative infection and at least 2 weeks of carnitine free TPN. Carnitine or placebo was added to the daily infusion of lipid during two consecutive 4-day periods in a randomised cross-over fashion. The total dose of carnitine was 110 mg/kg over 4 days. Before carnitine supplementation, total plasma carnitine levels ranged between 39 and 152 micromol/l. The RQ was 0.87 +/- 0.02 (SEM). The turnover (185 +/- 64 micromol/min) and fractional turnover (0.39 +/- 0.04/min) of oleic acid as well as the uptake (31 +/- 10 micromol/min) and fractional uptake (0.46 +/- 0.05) over the leg were similar to previously reported values in healthy subjects. Carnitine supplementation, despite a doubling of the average plasma carnitine level, did not influence the RQ or the whole body turnover and regional exchange of oleic acid. The present results suggest that four days of carnitine supplementation in patients with persistent post-operative infection has no measurable effect on FFA utilisation, indicating that the patients' carnitine reserves were sufficient to maintain normal FFA utilisation.

One group of 8 patients with primary biliary cirrhosis and one group of 7 patients with common duct stone both had generally high levels of blood coagulation factors and a wide range of other plasma proteins. In contrast, one group of 6 patients with chronic active hepatitis generally had low levels of the same coagulation factors and plasma proteins. Analyses of factor II-VII-X, plasminogen, ceruloplasmin, beta1C/1A-globulin, IgG and IgM are especially helpful in the differentiation between primary biliary cirrhosis and chronic active hepatitis. The data are interpreted as suggesting a generally increased synthesis of liver-produced proteins in cholestasis, although more specific factors may modify the degree of increase of the individual proteins.

Cysteine sulfinate is an intermediary compound in the metabolism of sulfur-containing amino acids. An enzymatic method based on the transamination of cysteine sulfinate and 2-oxoglutarate by aspartate aminotransferase (EC 2.6.1.1) followed by detection of the formed sulfite was modified and applied to human urine. Using this method no cysteine sulfinate was found in human urine. This is in contrast to other reports where a urinary excretion of cysteine sulfinate in the range of 50–100 μmole/ 24 hr was found determined by amino acid analysis. Neither were appreciable amounts of sulfocysteine or phosphoserine found in normal human urine.

Carnitine is necessary for the transport of long-chain fatty acids across the mitochondrial membrane. Carnitine is derived from the diet and from endogenous synthesis from lysine and methionine. About 98% of the body's carnitine pool is located in skeletal muscle tissue. Skeletal muscle carnitine levels were determined in two groups of malnourished patients, eight patients with anorexia nervosa with a weight loss of 32.4% +/- 1.8 (mean +/- SEM) and six surgical patients with major gastrointestinal disorders and a weight loss of 15.2% +/- 2.7. Their hepatic and kidney functions were normal. On admission, the muscle carnitine levels were 16.9 +/- 4.0 mumol/g dry weight (mean +/- SD) for the surgical patients and 20.8 +/- 5.0 mumol/g dry weight for the anorexia nervosa patients, which corresponded to carnitine levels seen in healthy subjects. No statistical significance was found between the two groups. Total parenteral nutrition was given to the surgical patients for 2 weeks and to the anorexia nervosa patients for 3-5 weeks. No statistical difference in muscle carnitine levels was found in either group after nutritional support. These malnourished patients had no decreased muscle carnitine levels on admission and maintained them during several weeks of total parenteral nutrition.

Coagulation factors and other plasma proteins were studied in 19 male chronic alcoholics during the first abstinence week after a period of heavy alcohol consumption. In spite of a decade of chronic alcoholism and a daily alcohol consumption before admission of more than twice the 'normal' alcohol-metabolizing capacity, the data indicated a well-preserved protein-synthesizing capacity. In fact, the mean levels of some liver-synthesized proteins were above the upper reference limits. Minor changes within the reference ranges during the abstinence suggested a declining acute inflammatory reaction after cessation of intoxication.

We examined 1) the effect of L-carnitine supplementation on free fatty acid (FFA) utilization during exercise and 2) exercise-induced alterations in plasma levels and skeletal muscle exchange of carnitine. Seven moderately trained human male subjects serving as their own controls participated in two bicycle exercise sessions (120 min, 50% of VO2max). The second exercise was preceded by 5 days of oral carnitine supplementation (CS; 5 g daily). Despite a doubling of plasma carnitine levels, with CS, there were no effects on exercise-induced changes in arterial levels and turnover of FFA, the relation between leg FFA inflow and FFA uptake, or the leg exchange of other substrates. Heart rate during exercise after CS decreased 7–8%, but O2 uptake was unchanged. Exercise before CS induced a fall from 33.4 +/- 1.6 to 30.8 +/- 1.0 (SE) mumol/l in free plasma carnitine despite a release (2.5 +/- 0.9 mumol/min) from the leg. Simultaneously, acylated plasma carnitine rose from 5.0 +/- 1.0 to 14.2 +/- 1.4 mumol/l, with no evidence of leg release. Consequently, total plasma carnitine increased. We concluded that in healthy subjects CS does not influence muscle substrate utilization either at rest or during prolonged exercise and that free carnitine released from muscle during exercise is presumably acylated in the liver and released to plasma.

A digital computer program is described for the estimation of parameters in an open two compartment system distinguishing 3 models. The mathematical function to be fitted to a given set of experimental data is given initial estimates for the parameters of the function. The program uses an iterative procedure to adjust the parameters until the sum of squares of residuals has converged to a minimum. Assuming that a given substance is introduced into compartment 1, the function can be fitted to the set of experimental data of that compartment. A set of experimental data from compartment 2 can also be included in the minimizing function. Two optional weighting functions are presented. From the constants of the two-exponential functions the physiological parameters of the three models are determined. Experimental observations of compartment 1 only allow for calculation of physiological parameters of two of the models.

A spectrophotometric method for carnitine has been adapted to the Cobas Bio centrifugal analyzer. The addition of carnitine to a system containing carnitine acetyltransferase (EC 2.3.1.7) and acetyl-CoA gives rise to the formation of CoA. The system is coupled to 5,5'-dithiobis(2-nitrobenzoate) (DTNB). Assay response varied linearly with concentration of carnitine over a wide concentration range. The total CV was 5.5% for a carnitine concentration in serum of 58.0 mumol/L. Analytical recovery of carnitine added to a serum sample was 93%. No interference was found in icteric, not grossly hemolyzed, lipemic, or uremic sera. Comparison with a radioenzymatic method showed that results correlated well (r greater than 0.965) but the present method gave values proportionally greater by 10 to 25% for samples of plasma, dialysis fluid, urine, and muscle tissue. Advantages over the original spectrophotometric assays involving DTNB include low reagent costs, rapidity, simplicity, and reproducibility. However, this modification is not as sensitive and probably not as specific as the radioenzymatic methods.

The albumin values determined by the bromcresol green methods do not compare well with values by more specific methods for albumin determination. The discrepancies have been related to, among other things, acute-phase reactants and are especially pronounced in the lower albumin range. These disadvantages are also inherent in a routine continuous-flow method for albumin (SMAC). The bromcresol green method has been improved considerably by shortening the reaction time before the absorbance is measured, as is described here. The modified method yields values that better agree with those by more specific methods and an influence of acute-phase reactants is no longer observed.

Total plasma carnitine was analysed in 19 women, with uncomplicated pregnancies, who underwent elective caesarean section, and in their neonates. The women were given a balanced glucose (glucose group) or saline (saline group) infusion, group allocation being on a random basis. The carnitine levels in maternal or infant plasma did not differ between these two groups. At delivery, the mean maternal carnitine value, 17.4 +/- 1.25 mumol/l, was lower than the mean infant value, 25.9 mumol/l +/- 2.67 (mean +/- SE, p less than 0.005) and lower than the mean value in non-pregnant, fertile women, i.e. 40.9 +/- 1.22 mumol/l. The mean carnitine value in the unfed neonate had not changed when the infant was 4 hours old. A positive correlation was found between carnitine levels in maternal and infant plasma (p less than 0.01). At delivery, the levels of non-esterified fatty acids and 3-OH-butyrate in infant plasma were different in the two groups, but not at 4 hours of age. The results suggest that the maternal carnitine level is the most important factor governing plasma carnitine levels in the neonate.

The muscle contents of water, electrolytes, creatine, alkali-soluble protein (ASP) and carnitine were determined using percutaneous muscle biopsy technique. Seven patients with prolonged catabolic states and subsequent respiratory failure were studied. Twelve age- and sex-matched healthy subjects were used for comparison. The muscle content of alkali-soluble protein in relation to the content of DNA was less than half of control values, indicating a loss of more than 50% of muscle protein content. The muscle carnitine content was 25.9 ± 6.5 μmol/g alkali-soluble protein, suggesting a preserved muscle carnitine concentration. Total muscle water was increased by over 20%, mainly due to an increase in extracellular water. Muscle sodium and chloride contents were doubled. The content of magnesium was slightly reduced but muscle potassium was normal. The marked depletion of muscle protein may have contributed to the requirements for artificial ventilation and the difficulties in weaning off the ventilator. The increase in muscle water masks the loss of metabolically active muscle tissue yielding low values for energy expenditure when relating to body weight. The benefit of the use of the ASP/DNA ratio in nutritional assessment is emphasised.

Intravenous fat tolerance tests were performed with (carboxyl-14C)-triolein labelled Intralipid in four normal subjects with and without L-carnitine administration, 20 and 25 mg/kg body weight. The pharmacokinetics of L-carnitine was studied simultaneously with measurements of variables reflecting fat metabolism during 4 h. 3-OH-butyrate concentration in plasma was higher in all subjects when carnitine was given. No effect of carnitine was found in elimination of the exogenous triglycerides, the 14CO2 activity in expired air, concentration and specific radioactivity of non- esterified fatty acids or glucose in plasma. The data suggest that carnitine may slightly increase fatty acid oxidation in normal subjects provided that increase of 3-OH-butyrate concentration in plasma is the most sensitive variable reflecting fatty acid oxidation of the variables applied in this study.

This study assessed the time course ofdecrease in plasma camitine during pregnancy and compared the renal clearance of carnitine during late pregnancy with nonpregnant women. As early as the 8th wk of pregnancy, the mean (±SD) value of total plasma-carnitine concentration in 19 women was significantly decreased from 39.0 ± 6.3to32.8± 4.6 �tmol/l and the values continued to fall to 17.3 �emol/l by the 36th wk. The pattern was due to a fall in free-carnitine level; acylcarnitine remained unchanged. In 12 other women examined during late pregnancy, the renal clearance of acylcarnitine was significantly higher than in nonpregnant women, 53.9 ± 29.4 versus 13.3 ± 3.0 ml/min, in contrast to free carnitine, 3.5 ± 2.8 versus 2.8 ± 1.9 ml/min.Urinaryexcretion of carnitine (expressed per mol creatinine) did not differ between the two groups. Pregnant women showed sustained excretion of carnitine in the presence of low plasma-carnitine concentrations. Am J C/in Nuir l986;44:379-383.

Ten premature infants with a mean gestational age of 29 weeks (range, 27-32) and a mean birth weight of 1,294 g (range, 930-2,300) and without complications at birth were studied during the first 14 days after birth. Their breast milk intake was recorded and the carnitine content determined in each daily portion. During the first week, the daily mean carnitine intake was low and increased to 6-7 mumoles/kg and day during the second week. Breast milk carnitine concentration ranged from 17 to 148 mumoles/L. Plasma carnitine and its derivatives did not change during the observation period. No relationship was found between the individual cumulative breast milk carnitine intake and total plasma carnitine levels or between carnitine and its derivatives and nonesterified fatty acids or 3-OH-butyrate. The urinary carnitine excretion, in millimoles of carnitine per mole of creatinine, was higher during the second week. In other studies, declining plasma carnitine levels have been observed in premature infants on total parenteral nutrition. The results from this study indicated that premature infants without complicating disorders were able to maintain their plasma carnitine levels.

When studying the correlation between the change of a variable during treatment and the value before treatment, random errors (errors of measurement as well as intra-individual biological variation) may yield seriously biased results. In the present work a method to adjust for this bias is presented. The method was applied to data from blood coagulation factor and plasma protein analyses in chronic alcoholics before and after one week of abstinence. It was found that many of the significant correlations were lost when the data were adjusted.

The pharmacokinetics of single intravenous and oral doses of L-carnitine 2 g and 6 g has been investigated in 6 healthy subjects on a low carnitine diet. Carnitine was more rapidly eliminated from plasma after the higher dose. Comparing the 2-g and 6-g doses, the t1/2 beta of the elimination phase (beta) was 6.5 h vs 3.9 h, the elimination constant was 0.40 vs 0.50 h-1 and the plasma carnitine clearance was 5.4 vs 6.1 1 x h-1 (p less than 0.025), thus showing dose-related elimination. Saturable kinetics was not found in the range of doses given. The apparent volumes of distribution after the two doses were not significantly different and they were of the same order as the total body water. Urinary recoveries after the 2-g and 6-g doses were 70% and 82% during the first 24 h, respectively. Following the two oral dosing, there was no significant difference in AUCs of plasma carnitine. Urinary recoveries were 8% and 4% for the 2-g and 6-g doses during the first 24 h. The oral bioavailability of the 2-g dose was 16% and of the 6 h dose 5%. The results suggest that the mucosal absorption of carnitine is already saturated at the 2-g dose.

The variations in the number of platelets, platelet retention, blood coagulation, fibrinolysis and various plasma proteins were studied during the menstrual cycle in 30 normal women. Blood samples were taken on 6 occasions; day 1,2, and 3 of menstruation, day 5–9 (follicular phase), day 12–16 (around ovulation), and day 19–23 (luteal phase), respectively. The concentration of fibrinogen was lower during menstruation than in the luteal phase. Factor II-VII-X and platelet retention were lowest and the recalcification time was shortest during the menstruation. The number of platelets was highest in the ovulatory phase. The fibrinolytic activity was higher in the luteal phase and during the menstruation than in the follicular phase. The results might indicate an intrauterine clotting during the menstruation. The close correlations between the variations of most of the plasma proteins indicate the presence of some general not identified factor which is probably not the variation in the intravascular water content.

This investigation determines the effect of two isocaloric diet regimens on plasma carnitine and urinary carnitine excretion in man. Seven healthy men were served a high-carbohydrate, low-fat (C) or a low-carbohydrate, high-fat (F) diet for 2 wk, ie, one diet regimen for 4 d followed by a 3-dbreak and concluded with 4 d more on the other diet regimen. The two regimens contained the same amount of carnitine-rich food. Plasma free carnitine rose significantly from the initial value on F diet and was significantly higher from day 3 than C diet. Plasma acyl carnitine increased on bothdiets. Urinary excretion of carnitine increased only on F diet. Renal clearance of both free and acyl carnitine was significantly greater on F diet than on C diet. Resultsshowed that composition of a diet withconstant carnitine content influenced carnitine metabolism in man. Am J C/in Nuir l987;45:725-9.