Plasma levels and urinary excretion of amino acids by subjects with renal calculi

Plasma levels and urinary amino acid excretions were estimated by high-performance liquid chromatography in 15 control subjects and 36 stone formers (SFs) classified according to the stone type: (1) 22 cases with calcium oxalate stones; (2) four cases with pure uric acid stones; (3) 10 cases with magnesium-ammonium phosphate stones, either pure or mixed with apatite. Some types of stones (namely oxalate and uric acid calculi) are mainly formed as a result of a metabolic deficiency that may affect the amino acid metabolism, and thus may be reflected in the urinary amino acid pattern. Data demonstrated clearly that there is a general tendency towards decreased amino acid excretions in all SFs with all types of stones. As a whole, one can observe a higher percentage of patients with calcium oxalate and phosphate calculosis, who have low urine excretions of amino acids; about 50% are the SFs with lower urine excretion of serine, glycine, taurine and i-leucine; the high percentage of patients with CaOX calculi shows lower urine excretions of tyrosine and ornithine.     

The glomerular mesangium: a comparative study of mesangial handling of iron dextran complex and endogenous IgG in mice and rats

The function and channel system of the glomerular mesangium in mice and rats was investigated by studying the uptake and transport of intravenously injected iron-dextran particles, and the localization of endogenous IgG. Animals were killed at 30 min, 8 h, 1 and 3 days and 1 and 2 weeks after intravenous injection of iron dextran complex. It was found that the tracer was present maximally in the mesangium of the mouse at one day after injection whereas a maximum was not reached until the third day in the rat. Maximal levels of tracer particles in the extra-glomerular lacis area were found at three days in the mouse and at 2 weeks in the rat. Disappearance of the tracer from the blood as indicated by the measured serum iron levels did not seem to differ significantly in the two species. Using an ultrastructural immunoperoxidase technique, considerable amount of endogenous IgG were localized in the mesangial channel system in the stalk region and in the extraglomerular lacis area of mice, whereas in rats only very scanty endogenous IgG was present in these locations. It is suggested that the difference in mesangial handling of macromolecular material in mice and rats is more likely to be due to a different rate of transport through the mesangial channel system than to primary differences in mesangial phagocytotic activity.     

Plasma amino acids and sports injuries

Summary. The aim of this study was to explore the relationship between changes in plasma amino acids and the incidence of sports injuries during a soccer season. Fourteen plasma amino acids were assayed at monthly intervals in 12 young soccer players during a whole soccer season. Based on the number and severity of injuries the soccer players were divided into an injury-prone and a non-injury-prone group. The mean plasma level of the amino acid glycine was significantly lower (P=0.009) in the injury-prone group than the other group, while the mean plasma levels of tyrosine, tryptophan and lysine were higher in the injury-prone group during this period (P<0.05). However there were no significant differences in the calculated plasma tryptophan and tyrosine/large neutral amino acids ratios. Significant linear time trends were observed for taurine, ornithine, lysine and the tryptophan/large neutral amino acids ratio.These results indicate that the plasma concentrations of glycine and to a lesser extent those of tyrosine, tryptophan and lysine may be promising peripheral markers for injury-proneness in young soccer players. Whether a role for glycine substitution will be indicative to reduce the occurrence of sports injuries will need to be investigated in future studies.     

Plasma amino acids in ecstasy users

Recreational use of the illegal drug "ecstasy" has increased dramatically in recent years. We have measured 33 different plasma amino acids in ecstasy users and controls. Significant differences were found for phosphoserine, glutamate, citrulline, methionine, tyrosine and histidine. Resembling changes in the plasma amino acids have been described in acute transient polymorphous psychosis. Thus, alterations in plasma - methionine and phosphoserine or other amino acids could be involved in the psychical symptoms produced by MDMA.     

Olfactory sensitivity for six amino acids: a comparative study in CD-1 mice and spider monkeys

Using a conditioning paradigm, the olfactory sensitivity of five CD-1 mice for the l- and d-forms of cysteine, methionine, and proline was investigated. With all six stimuli, the animals discriminated concentrations ≤0.1 ppm (parts per million) from the odorless solvent, and with three of the six stimuli the best-scoring animals were even able to detect concentrations <0.1 ppb (parts per billion). Three spider monkeys tested in parallel were found to detect the same six stimuli at concentrations <1 ppm, and with four of the six stimuli the best-scoring animals detected concentrations ≤1 ppb. Both CD-1 mice and spider monkeys displayed a higher olfactory sensitivity with the l- and d-forms of cysteine and methionine than with the prolines, suggesting an important role of the sulfur-containing functional groups for detectability. Accordingly, the across-odorant patterns of detection thresholds obtained with mice and spider monkeys showed a significant positive correlation. A comparison of the detection thresholds between the two species tested here and those obtained in human subjects suggests that neither the number of functional olfactory receptor genes nor the absolute or the relative size of the olfactory bulbs reliably predicts a species’ olfactory sensitivity for amino acids.     

Renal handling of amino acids in 5/6-nephrectomized rats: Stimulation of renal amino acid reabsorption after treatment with triiodothyronine or dexamethasone under amino acid load

Summary In anaesthetized adult female rats, the renal amino acid handling was measured six days after 5/6 nephrectomy (5/6NX). The distinct rise in blood urea nitrogen as well as the significant reduction in urine flow and GFR indicate an impairment of kidney function. In principle, in 5/6NX rats amino acid plasma concentrations were comparable to those of control animals with two intact kidneys, whereas the fractional excretions (FE_AA) of most endogenous amino acids measured were significantly enhanced. After bolus injection of leucine or taurine (each 20 mg/100 g b.wt.) or glutamine (90 mg/ 100 g b.wt.), dissolved in 2m1 normal saline per 100 g b.wt., the FE_AA of both the amino acids administered and the endogenous amino acids increased as a sign of overloaded amino acid reabsorption capacity. This effect was more pronounced in 5/6NX rats than in controls. As early as one hour after amino acid load, plasma concentrations and FE_AA returned to baseline values of 5/6NX rats. A pretreatment with triiodothyronine (20,µg/100 g b.wt.) or dexamethasone (60 µg/100 g b.wt.), both given intraperitoneally once daily for 3 days, stimulated the renal amino acid transport capacity in 5/6NX rats: the increase in FE_AA after amino acid load was significantly lower compared to non-pretreatred animals. This stimulation could be shown for the bolus amino acids and the endogenous amino acids and was more distinct in 5/6NX rats than in controls with two intact kidneys.     

Branched chain amino acids chronic treatment and muscular exercise performance in athletes: a study through plasma acetyl-carnitine levels

Summary In relation to energy request during physical exercise, muscular tissue Branched Chain Amino Acids (BCAA) are metabolized particularly when the oxidation rises. But in the whole-human body, it is difficult to estimate, in a quantitative sense, the role played by BCAA in sustaining exercise. During a BCAA treatment, made on a group of athletes kept under observation, it was observed, through Conconi's test, that this treatment influenced physical performance. Aim of present work is to investigate if BCAA chronic treatment effect on physiological trial is confirmed on blood circulating biochemical energy parameters and in particular on acetyl-carnitine, since acetyl-linked compounds may be an important biochemical factor.Fourteen athletic well trained male subjects, were randomly divided into two subgroups; a first group was submitted to a chronic treatment (n = 7) of BCAA (oral intake was 0.2 g/Kg die) and a second group, as controls (n = 7), assumed oral placebo. Conconi's test demonstrated a significant difference (p < 0.005) in the exercise performance of the two sub-groups, comparing the measurements of ratios of deflection velocity (V _d ), before and after the treatment. Therefore we studied the athletes performing a muscular exercise test (40 Km/h, cycle race, for 90 min) after one month of treatment. During this treatment period the subjects followed a well standardized diet. Samples of blood were drawn before, at the end and during the recovery (60 min) to study if traditional biochemical parameters varied and confirmed the observed differences in Conconi's test. The measurements of concentrations of FFA, KB, free carnitine, acetyl-carnitine and BCAA were performed. Plasma BCAA levels did not demonstrate variations either before or after the exercise performance, or between the two groups. The biochemical factors, substrates and hormones, KB, FFA, lactate, insulin and growth hormone plasma levels did not demonstrate significant differences from the patterns present in literature. Plasma free and acetyl-carnitine followed the well known variations, but only acetyl-carnitine levels demonstrated, at the end increase in acetyl-carnitine levels could be related to a minor fatigue situation and to a larger energy supply availability perhaps present in BCAA treated athletes (Sahlin et al., 1990; May et al., 1989). Both mentioned hypothesis seem in concordance with a smaller acetyl-CoA substrate accumulation, or better for present study, is even more successful with athletes who give a better physical performance. In fact Conconi's test in the two sub-groups of athletes seems to suggest that BCAA treated athletes were able to give a better performance, furthermore out of curiosity we point out that the athletes treated with BCAA won more races than the untreated.We would also like to add in conclusion that although confirming the difficulties of studies in the whole-body, our work gives an interesting clue about the possibility to use acetyl-carnitine plasma levels to understand the biochemical importance of the BCAA as substrate able to influence physical performance, but further research is needed.The phenomenon presence might be showed better perhaps by studying untrained groups during prolonged exercise and with physical performance at exhaustion. If treatment were able to help the physical performance and to shift the fatigue, then confirmation might be a less raised plasma acetyl-carnitine level. In effect blood ammonium levels in present study did not demonstrate any variation in and between sub-groups; this latter observation could be caused by the quantity of work load, and training state of the athletes (Ji et al., 1987; Kirkendall, 1990). Moreover, as observed by Hageloch et al. (1990), the ammonia increases less during prolonged endurance exercise, and in fact the athletes of present study were all middle distance racing cyclists, and the physical performance was a prolonged endurance exercise.     

Identification of endogenous acyl amino acids based on a targeted lipidomics approach

Using a partially purified bovine brain extract, our lab identified three novel endogenous acyl amino acids in mammalian tissues. The presence of numerous amino acids in the body and their ability to form amides with several saturated and unsaturated fatty acids indicated the potential existence of a large number of heretofore unidentified acyl amino acids. Reports of several additional acyl amino acids that activate G-protein coupled receptors (e.g., N-arachidonoyl glycine, N-arachidonoyl serine) and transient receptor potential channels (e.g., N-arachidonoyl dopamine, N-acyl taurines) suggested that some or many novel acyl amino acids could serve as signaling molecules. Here, we used a targeted lipidomics approach including specific enrichment steps, nano-LC/MS/MS, high-throughput screening of the datasets with a potent search algorithm based on fragment ion analysis, and quantification using the multiple reaction monitoring mode in Analyst software to measure the biological levels of acyl amino acids in rat brain. We successfully identified 50 novel endogenous acyl amino acids present at 0.2 to 69 pmol g⁻¹ wet rat brain.     

Effects of endogenous estrogen on renal calcium and phosphate handling in elderly women

High postmenopausal endogenous estrogen concentrations are an important determinant of preservation of bone mass and reduced fracture in elderly women. Calcium supplementation can also reduce bone loss in these patients, suggesting an interaction between estrogen deficiency and calcium balance. Potential mechanisms of estrogen on calcium transport include direct effects on the bone, the kidney, and the bowel. Previous studies have demonstrated effects of estrogen on renal phosphate handling. We have used a cross-sectional, population-based analysis of biochemical data obtained from ambulant elderly women to determine the association of endogenous estradiol with urine calcium and phosphorus excretion. The subjects were 293 postmenopausal women >70 yr old. Factors associated with renal calcium and phosphate excretion were measured, including the filtered calcium and phosphate load, parathyroid hormone (PTH), estradiol, and sex hormone-binding globulin (SHBG). The free estradiol concentration (FE) was calculated from a previously described formula. A high plasma estradiol concentration (r(2) = 0.023, P = 0.01) and a high FE (r(2) = 0.045, P = 0.001) were associated with reduced renal calcium excretion. The estradiol and FE effect on renal calcium excretion remained significant after adjusting for calcium filtered at the glomerulus and serum PTH. A high FE was associated with a reduced renal phosphate threshold in univariate analysis (r(2) = 0.023, P = 0.010). The effect remained significant after adjustment for serum PTH. The size of the effect of the FE was of the same order of magnitude as the effect of PTH on reducing renal calcium excretion and increasing renal phosphate excretion. These data support in vitro and animal data demonstrating an effect of estradiol on renal calcium and phosphate handling and indicate that, in elderly postmenopausal women, the effect is of a similar magnitude to the well-recognized effects of PTH on these physiologically regulated parameters.     

The amino acids used in reproduction by butterflies: a comparative study of dietary sources using compound-specific stable isotope analysis

It is a nutritional challenge for nectar-feeding insects to meet the amino acid requirements of oviposition. Here we investigate whether egg amino acids derive from larval diet or are synthesized from nectar sugar in four species of butterfly: Colias eurytheme, Speyeria mormonia, Euphydryas chalcedona, and Heliconius charitonia. These species exhibit a range of life history and differ in degree of shared phylogeny. We use 13C differences among plants to identify dietary sources of amino acid carbon, and we measure amino acid 13C using compound-specific stable isotope analysis. Egg essential amino acids derived solely from the larval diet, with no evidence for metabolic carbon remodeling. Carbon in nonessential amino acids from eggs derived primarily from nectar sugars, with consistent variation in amino acid turnover. There was no relationship between the nonessential amino acids of eggs and host plants, demonstrating extensive metabolic remodeling. Differences between species in carbon turnover were reflected at the molecular level, particularly by glutamate and aspartate. Essential amino acid 13C varied in a highly consistent pattern among larval host plants, reflecting a common isotopic "fingerprint" associated with plant biosynthesis. These data demonstrate conservative patterns of amino acid metabolism among Lepidoptera and the power of molecular stable isotope analyses for evaluating nutrient metabolism in situ.     

Lack of effect of excitatory amino acids on endogenous cyclic AMP levels in rat cerebrocortical tissue in vitro.

The spin-traps, 5,5′-Dimethyl-1-pyrroline-1-oxide and phenyltertiary-butylnitrone have been used to investigate the primary free radical involved in lipid peroxidation. In this report, we wish to present evidence that a NADPH-dependent hydroxyl radical (OH·), which may be the primary free radical that initiates lipid peroxidation, is generated in liver microsomes. A mechanism for the generation of the hydroxyl radical in liver microsomes is also postulated.     

Plasma amino acids concentration in amyotrophic lateral sclerosis patients

Summary.  Previous investigations showed an impairment of amino acids (AA) metabolism in amyotrophic lateral sclerosis (ALS). It was hypothesized that excitatory AA may play an important role in the etiopathogenesis of this disease. The aim of the study was to determine plasma AA concentrations in ALS patients, and to examine the relationship between AA and the clinical state of ALS patients, the type of ALS onset and the duration of the disease. The study involved 20 ALS patients and 30 control group people. The AA analysis was performed by ion – exchange chromatography on an automatic AA analyser. The results showed significantly decreased concentrations of valine, isoleucine, leucine, tyrosine and aspartate in the plasma of the whole group of ALS patients compared to the control group, and a significantly decreased concentration of arginine in the patients with a long duration of ALS compared to the patients with a short duration. The clinical state of ALS patients significantly influenced only plasma alanine concentration. Other plasma AA concentrations were not significantly associated with clinical parameters of the disease. Our study confirms that metabolic abnormalities concerning AA exist in ALS patients. However, the normal plasma glutamate concentration observed in this study in the whole group of ALS patients compared to the controls does not exclude that this excitatory AA may play a role in neurodegeneration in ALS. Received June 22, 2002 Accepted October 3, 2002 Published online January 23, 2003 Correspondence: Joanna Iłżecka M.D., Department of Neurology, Medical University, Jaczewskiego 8, 20-954 Lublin, Poland, Fax: +48 81 742 55 34, E-mail: Ilzecka@medscape.com     

Plasma amino acids in 3/sec spike-wave epilepsy

Plasma levels of 14 amino acids were determined in 44 probands with 3/sec spike-wave epilepsy, 27 of their first-degree relatives, and 22 controls. Six ratios of metabolically related amino acids were also calculated. Statistically significant differences were found for 7/20 variables when the experimental and control probands were compared, and for 6/20 variables when the relatives were compared with controls. Tau, Asp, and Tau/Glu were decreased and Glu was increased in both the experimental probands and their first degree relatives. When discriminant analysis was used, age- and sex-matched epileptic probands could be distinguished from the age- and sex-matched control probands with 100% accuracy employing only 3 amino acids (Asp, Glu, Val) and one ratio (Thr/Ser).     

Diurnal variations of amino acids and organic acids in xylem fluid from Lagerstroemia indica: an endogenous circadian rhythm

Diurnal variations in the concentrations of major organic compounds occurred in xylem fluid extracted from Lagerstroemia indica L. The concentration of amino acids and the N/C ratio was at a maximum and that of organic acids was at a minimum between 1230 and 2030 h. Since the concentrations of total organic nitrogen, total amino acids and most individual amino acids (but not organic acids or sugars) were also proportional to xylem tension two experiments were performed to discern whether variations in chemistry were a consequence of diurnal changes in moisture stress. In the first experiment, L. indica , exposed to variable levels of moisture stress during midday, manifested an increase in organic acids and a reduction in the N/C ratio. In the second experiment, chemical profiles of xylem fluid were collected and compared for plants exposed to a natural photoperiod, constant darkness or continuous light at noon and midnight. After 1 day amino acids increased in concentration during midday for all treatments; the variation was greatest (10-fold) for plants in constant darkness where xylem tension varied from 0.20 to 0.25 MPa. Only plants exposed to continuous light lost a diurnal rhythm after 3 days. Thus, the circadian rhythm was endogenous, terminated in continuous light and was not mediated by changes in moisture stress. Glutamine accounted for most of the diurnal variation in total amino acids, organic nitrogen and the N/C ratio in xylem fluid.     

Food provisioning and stone handling tradition in Japanese macaques: a comparative study of ten troops

By addressing the influence of food provisioning on stone handling (SH), a behavioral tradition in Japanese macaques, this study contributes to the ongoing debate in cultural primatology by asking whether human intervention influences the emergence or propagation of behavioral traditions. SH is a form of object play consisting of the manipulation of stones by performing various behavioral patterns. We tested the hypothesis that the frequency of food provisioning affects the daily performance, form, and context of occurrence of SH by influencing a troop's feeding-related activity budget. We used a standardized observation procedure to investigate SH in ten troops of Japanese macaques. In troops provisioned several times a day, SH was more frequent, longer, and more prevalent during provisioning than nonprovisioning periods. These effects of provisioning were not significant in troops provisioned less frequently. SH was more frequently integrated with food-related activities in troops supplied with food several times a day than in the other troops. Food provisioning may be a key factor in the innovation and transformation phases of the SH tradition in Japanese macaques.