Individual Plasma Amino Acids Research Articles

Preserved fetal plasma amino acid concentrations in the presence of maternal hypoaminoacidemia.

The effects on the conceptus of persistently decreased maternal plasma amino acid concentrations were studied in pregnant rats by the infusion of glucagon (0.21 mg/day) to the mother from day 14 to 20 of gestation with a subcutaneous, osmotically driven minipump. Controls received diluent. The experimental animals either had normal caloric intake and weight gain, or diminished caloric intake with no weight gain. Both experimental groups exhibited a decrease in plasma total amino acid concentration of approximately 50%. Maternal plasma glucose and insulin concentrations were unaffected except for slight decreases in the low weight gain group. At cesarean section on day 20, fetal weight was unaffected in the normal weight gain group, while the low weight gain animals exhibited intrauterine growth retardation. Fetal plasma glucose and insulin concentrations were unaffected. Despite the marked decrease in maternal plasma total amino acid concentration, fetal plasma total amino acid concentration was unaffected. Individual plasma amino acid concentrations in the normal weight gain mothers and fetuses revealed a spectrum of changes. Some maternal amino acids were decreased by more than 60% (alpha-aminobutyric acid, asparagine, threonine, glutamine, alanine) while others were unaffected (tyrosine, tryptophan, phenylalanine, histidine). In general, amino acids that were decreased in the mother exhibited no change or a lesser decrease in fetal plasma concentration, while those that were unaffected in the mothers showed increased fetal concentrations. Fetuses from the low weight gain mothers had plasma amino acid profiles that were similar to those of the normal weight gain mothers.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino acid compartmentation in chick blood during the peri-hatching period

1. 1. Individual amino acid levels and compartmentation in chick blood were measured on day 20 of incubation, at hatching (day 0), or after 1 or 5 days of free life, and compared with those of adult chickens. 2. 2. Blood cell amino acid concentrations were almost one order of magnitude higher than those of plasma, with higher values than those found in mammalian erythrocytes. 3. 3. This difference may be due to the capability for protein synthesis of the nucleated cells coupled with a postulated utilization of amino acids as fuel. 4. 4. The most common pattern of individual plasma amino acid levels was a slight rise at hatching followed by a large decrease, with minimal values for adults. 5. 5. The patterns in the cells did not always coincide with those for plasma. 6. 6. Total blood amino acid levels increased steadily during the period studied due to the increase in intracellular amino acids, giving rise to increasing blood-cell/plasma concentration ratios. 7. 7. These changes showed higher availability of plasma amino acids just after hatching, while the cell concentrations increased steadily to the maximum values in adults. 8. 8. The increase in alanine levels in cells with little changes in plasma can be correlated with the role of this amino acid as the main 2-amino nitrogen carrier in the avian bloodstream. 9. 9. The high amino acid levels in the cells suggest that these cells act as inter-organ transporters and reservoirs of amino acids, they have a different role in their handling and metabolism from those of mammals.

Low-protein Feeding in Mink: Effects on Plasma Free Amino Acids, Clinical Blood Parameters, and Fur Quality

Abstract Four groups of mink were fed from weaning to pelting with feed of different protein levels. The metabolizable energy (ME) from protein amounted to 40/36% in the control group and 36/31, 31/27, and 27/23% in the medium, medium-low, and low-protein groups during the early and late growth period, respetively. Weight gain and hematological parameters were within normal range in all groups, but the lowest values were observed in the lowest dietary protein groups. There were no significant differences in plasma urea or creatinine concentrations between the groups. Plasma albumin and total protein increased with age and were highest in the low-protein group. The activities of transaminases, ASAT and ALAT, in plasma were also highest in the low-protein groups. The plasma content of total free amino acids was higher in the low-protein group as compared to the controls, especially essential amino acids. These changes as well as the individual plasma amino acid concentrations indicated a metabolic response ...

A CELL MODEL TO ASSESS PROTEIN SYNTHESIS AND AMINO ACID POOLS IN NEONATES

The relation of protein synthesis (PS) to extracellular (EC) and intracellular (IC) amino acid (AA) pools, birthweight, gestational age and postnatal weight change in human neonates is unknown. Viable neutrophils isolated from 1-2 ml venous blood were used as a cell model to evaluate these relationships in 35 infants with complete data at 33 to 44 weeks postconceptual age (2d-14 weeks postnatal age), PS (3H-leucine incorp, p moles/hr/mg DNA) and 19 cell AA (n moles/mg DNA) were quantified in the leukocytes and 19 AAs in the same plasma (n moles/ml) (Dionex high pressure AA analyzer, fluorometric detection). No significant (p <.05) correlations were detected between PS and individual plasma AAs. PS was correlated with 11 of 19 IC AAs and with sets of both essential (ESSAA) and nonessential (NESSAA) IC AAs. PS also was inversely (−) correlated with birthwt., gest.age, postconceptual age and weight at time of study. When studied in a stepwise multiple regression of PS on the age-weight variables, weight at study was the only variable selected by the model and accounted for 20% (R2=.205, p=0.006) of the variance in PS. Of the AAs, the IC ESSA As were the only set explaining a significant proportion of the variance in PS (R2=0.274, p=0.001). Thus it appears that the smaller and more preterm the infant, the greater the rate of protein synthesis; which, in turn, is more closely related to levels of IC ESSA As than to plasma concentrations of the AAs. Measures of protein synthesis and IC AAs are feasible, even in neonates, and should contribute significantly to formulation and evaluation of therapies designed to improve these modalities.

Comparison of plasma and intraluminal amino acid profiles in man after meals containing a protein hydrolysate and equivalent amino acid mixture.

Plasma and intraluminal amino acid profiles were compared in normal subjects 30, 60, 120, 180 minutes after meals containing either a peptide-rich protein hydrolysate (H) or an equivalent free amino acid mixture (AA) as the nitrogen source. Except for asparagine (30 minutes) and glutamine (30 and 60 minutes), which were absorbed to a significantly (p less than 0.05) greater extent from the peptide mixture, there were no significant differences in the plasma increments of the remaining 13 amino acids at any time interval after the meals. Positive correlations (p less than 0.01 or less) between the amino acid composition of the hydrolysate and amino acid meals and both (1) the post-prandial increments in the individual plasma amino acids and (2) the residual intraluminal amino acid content suggested that the amino acid composition of ingested protein, rather than specialised free amino acid and peptide transport systems, dictated the pattern of amino acid absorption. The studies provide no evidence that peptides rather than free amino acids are the ideal nitrogen source in elemental diets.

Growth and diurnal variations in metabolic parameters in the starved bass, Dicentrarchus labrax, after experimental feeding

1. 1. Young bass ( Dicentrarchus labrax) were fed either a natural diet (filleted bogue) or a commercial diet for 107 days and studied after fasting for 7 days. 2. 2. The food consumption index and daily caloric intake was lower in the bass on the natural than on the commercial diet but the growth related parameters were much greater in the first group. 3. 3. Plasma acetoacetate levels showed daily rhythmicity in the bass on a bogue diet and these changes showed a trend similar to that of glucose. 4. 4. Plasma glycerol levels were greater in the bass on a commercial than on a natural diet probably as a result of enhanced lipolysis due to the limited efficiency of energy utilization in the first group. 5. 5. Some individual plasma amino acids showed significant daily rhythms in the bass on either diet. The compiled values of plasma amino acids were very similar in fish on either diet, indicating that in both groups lipid and carbohydrate metabolisms are more sensitive than those of protein-amino acids to the differences in the efficiency of energy utilization.

Effect of zinc deficiency on appetite and plasma amino acid concentrations in the rat.

1. Levels of zinc in liver and plasma of the Zn-depleted rats fluctuated with the feeding cycle and were significantly higher at the bottom than at the top of the cycle. As Zn deficiency became more severe fluctuations in plasma Zn diminished. Concentrations of Zn in liver, in contrast to levels in plasma and femur, were not markedly lowered by day 15. 2. In contrast to ad lib-fed (AL) and overnight-fasted (OF) controls, some pair-fed (PF) controls had elevated levels of Zn in liver and plasma. 3. Intakes of water and food were significantly correlated in Zn-deficient rats. Packed cell volumes were significantly higher for Zn-depleted than for AL and PF rats. 4. Food intakes and plasma glucose concentrations were related in AL, OF and PF control rats but not in Zn-deficient rats. 5. At day 15 of Zn deficiency the order of total plasma amino acid concentrations in the groups of rats was AL greater than Zn-deficient greater than OF greater than PF. Many of the differences between the AL and OF groups for individual plasma amino acids also appeared in the Zn-deficient group at the top and bottom of the feeding cycle. Differences in individual amino acid concentrations at the top and bottom of the feeding cycle tended to be opposite in the PF and the Zn-deficient group. Levels of tyrosine and tryptophan in plasma were correlated (P less than 0.05) with the cyclic feeding pattern of the Zn-deficient group; however, the ratios tryptophan or tyrosine: sum of other large neutral amino acids did not correlate significantly with the eating habits of Zn-deficient rats.

Studies of cerebrospinal fluid and plasma amino acids in patients with steady-state chronic renal failure

The concentration of free amino acids in the plasma and lumbar CSF of 11 patients with steady-state chronic renal failure has been measured and the CSF: plasma concentration ratios calculated. The results have been compared with the corresponding data from 37 control subjects. In renal failure, elevation of the mean plasma concentration of total amino acids and a reduction in the ratio of essential to total amino acids have been found. Whereas some individual plasma amino acid concentrations in renal failure were higher than normal, others were lower. Striking abnormalities of the CSF amino acid concentration have been observed. Some amino acids have shown similar patterns of abnormality in both CSF and plasma, whereas in the case of others, the changes have been restricted to either CSF or plasma. Significant variations from normal of the CSF : plasma concentration ratios were observed for four amino acids.

Effect of exercise on postoperative nitrogen balance

This study was designed to investigate whether exercise, when used as an adjunct to parenteral nutrition, has any influence on postoperative muscle catabolism, amino acid metabolism, and nitrogen balance. Twenty male Sprague-Dawley rats were divided into two groups of exercised and nonexercised animals. All animals underwent laparotomy and jugular vein cannulation, were placed in metabolic cages, and were infused with a dextrose-protein solution at 15 kcal and 0.56 g amino acids/100 g body wt per 24 h for a total of 96 h. The exercised animals were run on a treadmill for 15 min/day for a total of 3 days. There was no difference in nitrogen balance and body weight change between exercised and nonexercised animals, as well as no difference between animals who experienced different degrees of exercise. Total and individual plasma amino acids in the exercised group were 15% lower than in the nonexercised group; the total and individual free amino acids in muscle of the exercised group were 66% higher than in the nonexercised group. This pattern of high levels of amino acids in the muscle, coupled with decreased plasma concentrations, is suggestive of increased amino acid turnover in the muscle of the exercised animals. We suggest that, in the postoperative or postinjury period, exercise has a stimulating effect on amino acid turnover in the skeletal muscle resulting from 1) amino acid (mainly the branched-chain amino acids) consumption for energg metabolism and gluconeogenesis, and 2) protein synthesis. The net balance of both results in nitrogen equilibrium similar to that of a nonexercised control group.

Determination of stable isotopic enrichment in individual plasma amino acids by chemical ionization mass spectrometry

Determination of stable isotopic enrichment in individual plasma amino acids by chemical ionization mass spectrometry

Milk Production and Nitrogen Utilization in Response to Postruminal Infusion of Sodium Caseinate in Lactating Cows

Five lactating, rumen-fistulated Holstein cows were used to obtain additional information concerning the effects of postruminal infusion of sodium caseinate on milk production and amino acid utilization. A 7-day continuous abomasal infusion of approximately 450 g/day of sodium caseinate was preceded and followed by 7-day infusions of an isonitrogenous-isocaloric solution of glucose, monosodium glutamate, and urea. Total collections of milk, urine, and feces were obtained during the last 5 days of each infusion period. On the last day of each period, arterial and mammary venous blood samples were obtained for analysis of plasma free amino acids. During infusion of sodium caseinate, milk production, milk protein (N times 6.38) production, and efficiency of nitrogen utilization for milk crude protein production were increased. Arterial plasma concentrations of free histidine, isoleucine, phenylalanine, valine, and total essential amino acids were elevated above control levels during infusion of sodium caseinate, while ornithine and tryrosine were decreased. Calculation of the relative concentration of essential amino acids in arterial plasma and in milk protein indicated that methionine and lysine were least abundant in plasma relative to their requirement for milk protein synthesis. A high precentage extraction from arterial plasma by the mammary gland also suggested that methionine and lysine may have been the essential amino acids in most critical supply for milk protein synthesis. Calculation of uptake to output ratios of individual plasma amino acids by the mammary gland suggested that significant quantities of extracted arginine, isoleucine, leucine, threonine, and valine were utilized in pathways other than direct incorporation into milk protein.

Influence of glucocorticoids on glucagon secretion and plasma amino acid concentrations in man.

Plasma concentrations of glucagon, insulin, glucose, and individual plasma amino acids were measured in normal nonobese and obese subjects before and after 3 days of dexamethasone treatment (2 mg/day) and in patients with Cushing's syndrome. The subjects were studied in the basal postabsorptive state and following the infusion of alanine (0.15 g/kg) or ingestion of a protein meal. In nonobese subjects dexamethasone treatment resulted in a 55% increment in basal glucagon levels and in a 60-100% increase in the maximal glucagon response to alanine infusion or protein ingestion. In obese subjects, basal glucagon rose by 110% following dexamethasone, while the response to alanine increased fourfold. In patients with Cushing's syndrome basal glucagon levels were 100% higher and the glucagon response to alanine infusion was 170% greater than in normal controls.Dexamethasone treatment in normal subjects resulted in a 40% rise in plasma alanine concentration which was directly proportional to the rise in basal glucagon. The remaining 14 amino acids were unchanged. In the patients with Cushing's syndrome alanine levels were 40% higher than in normal controls and were directly proportional to basal glucagon concentrations. No other plasma amino acids were significantly altered in the group with Cushing's syndrome. It is concluded that (a) glucocorticoids increase plasma glucagon concentration in the basal state and in response to protein ingestion or aminogenic stimulation; (b) this effect of glucocorticoids occurs in the face of obesity and persists in chronic hypercorticism; (c) hyperalaninemia is a characteristic of acute and chronic glucocorticoid excess, and may in turn contribute to steroid-induced hyperglucagonemia; and (d) increased alpha cell secretion may be a contributory factor in the gluconeogenic and diabetogenic effects of glucocorticoids.

Splanchic glucose production and its regulation in healthy monozygotic twins of diabetics.

1. Splanchnic exchange of glucose, lactate, pyruvate, glycerol and individual plasma amino acids was determined in five clinically unaffected monozygotic twins of insulin-dependent diabetics and in a group of five age- and sex-matched controls. The studies were performed in the postabsorptive state and after stimulation of endogenous insulin secretion by the intravenous infusion of glucose at a rate of 2 mg/min per kg for 45 min. 2. In the basal state the mean splanchnic glucose output was 25% lower for the twins than for the controls while splanchnic uptake of glucose precursors was similar in the two groups. The concentration of circulating insulin (which rose by no more than 10–15 μunits/ml in either group) was lower during the infusion in the twins than in the controls. Despite the lower insulin concentrations, infusion of glucose resulted in a complete shut off of splanchnic glucose production in the twins, while in the controls only a 50% inhibition of basal glucose output was observed. In both the twins and controls estimated peripheral glucose utilization was unchanged during the glucose infusion. 3. It is concluded that: (a) in clinically unaffected identical twins of known diabetics basal splanchnic glucose production is reduced while uptake of glucose precursors is unchanged, suggesting a diminished contribution to basal glucose output from hepatic glycogenolytic processes; (b) in the twins as well as in controls, the liver is the primary site of action of small increments in endogenous insulin; (c) hepatic sensitivity to endogenous insulin is augmented in twins as compared with controls.

POSTWEANING PLASMA AMINO ACID PATTERNS AND NITROGEN CONSTITUENTS IN YEARLING BULLS AND HEIFERS WITH DIFFERENT RATES OF GROWTH

Jugular blood samples were collected from 63 yearling Hereford bulls and 76 yearling Hereford heifers of similar genetic background at the end of a 160-day postweaning test. Plasma protein, amino nitrogen, and urea were determined on samples from all animals. Plasma free amino acids were determined on the 12 highest and 12 lowest gaining bulls and heifers, selected on the basis of 365-day weight. Plasma protein averaged 8.41 g/100 ml, amino nitrogen 56.38 μg/ml, and urea nitrogen 17.19 mg/100 ml for the 63 bulls. In the 76 heifers, plasma protein averaged 7.52 g/100 ml, amino nitrogen 52.90 μg/ml, and urea nitrogen 7.65 mg/100 ml. Plasma protein, amino nitrogen, and urea nitrogen were not significantly different (P &gt; 0.05) between the high- and low-gaining groups within sexes. The concentrations (μmoles/100 ml) of the individual plasma amino acids did not differ significantly (P &gt; 0.05) between the high- and low-gaining groups of bulls or heifers. When calculated on a proportional basis (molar %), the individual plasma amino acids also did not differ significantly (P &gt; 0.05) between the two groups within sexes. Proline and tyrosine were negatively correlated (P &lt; 0.01) to postweaning gain in the bulls, whereas isoleucine and aspartic acid were negatively correlated (P &lt; 0.05) to postweaning average daily gain in the heifers.

Splanchnic and peripheral glucose and amino acid metabolism in diabetes mellitus.

Splanchnic and leg exchange of glucose, lactate, pyruvate, and individual plasma amino acids was studied in diabetics 24 hr after withdrawal of insulin and in healthy controls. Measurements were made in the basal postabsorptive state and during the administration of glucose at a rate of 2 mg/kg per min for 45 min. In the basal state, net splanchnic glucose production did not differ significantly between diabetics and controls. However, splanchnic uptake of alanine and other glycogenic amino acids was 1(1/2)-2 times greater in the diabetics, while lactate and pyruvate uptake was increased by 65-115%. Splanchnic uptake of these glucose precursors could account for 32% of hepatic glucose output in the diabetics, as compared to 20% in the controls. This increase in precursor uptake was a consequence of a two- to threefold increment in fractional extraction of these substrates inasmuch as arterial levels of alanine, glycine, and threonine were reduced in the diabetics, while the levels of the remaining substrates were similar in the two groups. Peripheral output of alanine and other glycogenic amino acids as reflected in arterio-femoral venous differences was similar in both groups. An elevation in arterial valine, leucine, and isoleucine was observed in the diabetics, but could not be accounted for on the basis of alterations in splanchnic or peripheral exchange of these amino acids. Administration of glucose (2 mg/kg per min) for 45 min resulted in an 80% reduction in splanchnic glucose output in controls, but failed to inhibit hepatic glucose release in the diabetics despite a twofold greater increment in arterial glucose levels. In both groups no consistent changes in arterial glucagon were observed during the infusion. It is concluded that in nonketotic diabetics (a) total splanchnic output of glucose is comparable to controls, but the relative contribution of gluconeogenesis may be increased by more than 50%; (b) accelerated splanchnic uptake of glucose precursors is a consequence of increased hepatic extraction of available substrates rather than a result of augmented substrate supply; and (c) the failure of glucose infusion to inhibit hepatic glucose output suggests that the exquisite sensitivity of the liver to the infusion of glucose in normal man is a consequence of glucose-induced insulin secretion.

Experimental Obesity in Man: Hyperaminoacidemia and Diminished Effectiveness of Insulin in Regulating Peripheral Amino Acid Release.

Meeting Abstracts1 May 1972Experimental Obesity in Man: Hyperaminoacidemia and Diminished Effectiveness of Insulin in Regulating Peripheral Amino Acid Release.Philip Felig, M.D., F.A.C.P., Edward S. Horton, M.D., Carl F. Runge, M.D., Ethan A. H. Sims, M.D., F.A.C.P.Philip Felig, M.D., F.A.C.P.Search for more papers by this author, Edward S. Horton, M.D.Search for more papers by this author, Carl F. Runge, M.D.Search for more papers by this author, Ethan A. H. Sims, M.D., F.A.C.P.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-76-5-857_4 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptInsulin modulates plasma levels of specific amino acids by regulating their outflow from peripheral protein reservoirs, particularly muscle. In spontaneous, severe obesity, hyperaminoacidemia has been demonstrated and may be a manifestation of insulin resistance. To evaluate further the interaction of insulin and amino acid metabolism in obesity, the effect of insulin on amino acid exchange across the forearm was studied in five subjects at ideal weight and after a 17 to 25% (16 kg) weight gain induced by over-eating and limited physical activity. Sixteen individual plasma amino acid levels were measured in simultaneous forearm arterial and deep venous (draining primarily... This content is PDF only. To continue reading please click on the PDF icon. Author, Article, and Disclosure InformationAffiliations: New Haven, Conn., and Burlington, Vt. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetails Metrics 1 May 1972Volume 76, Issue 5Page: 857-857KeywordsAmino acidsBlood plasmaExerciseInsulinInsulin resistanceMorbid obesityMuscle proteinsObesityPlasma proteinsWeight gain Issue Published: 1 May 1972 PDF downloadLoading ...

Amino acid metabolism in lactic acidosis

Individual plasma amino acid levels have been determined in six patients with severe lactic acidosis. A consistently distorted pattern was observed whether the disorder was due to shock or was of the idiopathic type. A sixfold elevation in mean alanine concentration was observed, and a significant correlation of alanine with pyruvate concentrations was demonstrated. Since alanine is normally released from muscle and stoichiometrically extracted by liver, normal formation of alanine from pyruvate is suggested by the findings. However, uptake and metabolism of alanine by isolated, perfused rat liver was significantly inhibited by perfusate concentrations of lactate and pyruvate equivalent to those observed in the patients. Thus the high levels of alanine in lactic acidosis are viewed as consistent with normal or increased peripheral release combined with impaired hepatic disposal. The levels of fifteen of the nineteen amino acids measured were elevated. Of the remaining four, three were intermediates of the urea cycle.

Changes in individual plasma amino acids following experimentally induced sand fly fever virus infection

Fasting concentrations of 21 individual plasma amino acids were determined in daily (7:30 a.m.) serial samples from eight volunteers infected with sand fly fever virus and compared to values obtained in six separate daily preexposure baseline measurements in each volunteer, as well as to serial measurements in three unexposed control subjects. By 47 hr after inoculation and before the onset of fever or other clinical indications of infection, most individual plasma amino acids were significantly depressed below preexposure values. These changes began before the marked decrement in protein intake during the illness. Such changes in plasma amino acids did not occur in control subjects. Reduction in amino acid concentrations persisted until after the lysis of fever and did not coincide in timing with alterations in white blood counts or serum Zn and Fe values. Urinary total nitrogen, urea, and alpha amino nitrogen were not altered during the course of sand fly fever in these subjects. Although food intake was reduced during sand fly fever, the magnitude of the amino acid depression was far greater than that reported during starvation or protein deprivation in non-infected subjects, and the sequence of changes in plasma valine, alanine, and glycine followed patterns different from those reported during starvation. It may be postulated that unusually large quantities of certain plasma amino acids were taken up by the cells of the liver and other visceral tissues during this infection. Plasma phenylalanine responded in a manner different from that of the other amino acids. It was decreased on day 2 after exposure to the virus but by day 4 and 5 was significantly increased above preinfection values. This resulted in a significant increase in the phenylalaninetyrosine ratio during the febrile phase of sand fly fever.

A quantitative assessment of the contribution of individual plasma amino acids to the synthesis of milk proteins by the goat mammary gland.

1. Arteriovenous differences of plasma free amino acids across the lactating mammary glands of six goats have been measured. 2. In four experiments, measurements of blood flow, amino acid arteriovenous differences, milk yield and milk nitrogen showed that the uptake of nitrogen in the form of amino acids was sufficient to provide all the nitrogen of the milk proteins synthesized in the mammary gland. 3. In the same four experiments the uptake from the plasma and output into the milk of individual amino acids per unit time were compared. The uptakes of essential amino acids and glutamic acid were approximately equal to the corresponding output figures. The uptake of serine was consistently less than the output, and the uptake of other non-essential amino acids was very variable, in some experiments being approximately equal to the output figures and in others being considerably less. 4. As in cows, there was an uptake of ornithine in all experiments, though ornithine is absent from milk. In goats, though not in cows, the uptake of arginine was consistently greatly in excess of the requirement for arginine residues in milk protein. 5. The possible significance of the uptakes of arginine and ornithine for the synthesis of serine and other non-essential amino acids in the mammary gland is discussed. 6. The importance of clamping the external pudic vein, when sampling mammary venous blood from the caudal superficial epigastric vein, is indicated.

Effect of Glucose Infusion on the Individual Plasma Free Amino Acids in Man.

SummaryGlucose, with and without exogenous insulin, was infused into normal males under conditions which produced a submaximal fall in total plasma FAA concentrations. Analysis of the individual free plasma amino acids revealed a significant decrease in the following essential amino acids; leucine, valine, threonine, isoleucine, phenyl-alanine and tyrosine. This effect is enhanced by the presence of exogenous insulin.