Amino Acids In Sweat Research Articles

Quantification of amino acids in small volumes of palm sweat samples

This study investigates the significance of quantifying amino acids in minute sweat volumes using high-performance liquid chromatography with fluorescence detection. Sweat, a valuable biofluid for non-invasive health monitoring, provides real-time insights into physiological changes. Amino acids, which are critical for various physiological processes, are key to protein synthesis and cellular regulation. Therefore, analyzing sweat's amino acid profiles can offer insights into metabolic states, exercise-induced stress, and potential biomarkers for health conditions. For sensitive analysis, amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), followed by liquid chromatographic separation on an octadecylsilyl column and fluorescence detection. The developed method was validated and applied to human sweat samples, enabling the quantification of 14 amino acids. The most abundant amino acids in the samples were serine, glycine, and alanine, which aligns with prior studies. This method offers a non-invasive and efficient way to screen for diseases by detecting amino acids in sweat, even with minimal sweat volumes. The approach could also be used to analyze other biomolecules in sweat, expanding its potential applications.

Preparation of Polyvinyl Alcohol/Ninhydrin Blend Nanomembranes by Needleless Electrospinning and Their Application in Latent Finger Mark Detection

Finger mark identification, which is one of the biological recognition methods, has a history of more than 100 years. In this study, polyvinyl alcohol (PVA)/ninhydrin blend nanomembranes were prepared using needleless electrospinning and applied in latent finger mark detection. The morphology and structure of the PVA/ninhydrin nanomembranes were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results showed that the preferable composition for the best spinnability of the complex solution was 86.9 g/L PVA and 76.1 g/L ninhydrin, using water as solvent. The ninhydrin was uniformly dispersed in the PVA/ninhydrin nanomembranes in the amorphous regions. There was a small amount of hydrogen bonds between the PVA and ninhydrin. The addition of ninhydrin did not affect the crystal structure of PVA. When subjected to hot steam of a weak acidic water bath (pH = 6), the PVA/ninhydrin nanomembranes completely displayed the latent invisible finger marks left on glass or ceramic surfaces in purple within 3–5 min of the steam exposure, which were easily observed by the naked eyes. The purple finger marks on the nanomembranes were due to the reaction of ninhydrin with amino acids in sweat released from the fingers. Both chemical cross-linking and physical adhesion of the membrane to the surface occurred in the area of the finger mark regions. Physical adhesion also developed in the regions without finger marks. Therefore, finger marks identification using electrospun PVA/ninhydrin nanomembranes is simple, rapid, harmless, and sensitive, and does not need large instruments or any type of liquid chemical reagent.

Relationships between electrolyte and amino acid compositions in sweat during exercise suggest a role for amino acids and K+ in reabsorption of Na+ and Cl- from sweat.

Concentrations of free amino acids and [K+] in human sweat can be many times higher than in plasma. Conversely, [Na+] and [Cl-] in sweat are hypotonic to plasma. It was hypothesised that the amino acids and K+ were directly or indirectly associated with the resorption of Na+ and Cl- in the sweat duct. The implication would be that, as resources of these components became limiting during prolonged exercise then the capacity to resorb [Na+] and [Cl-] would diminish, resulting in progressively higher levels in sweat. If this were the case, then [Na+] and [Cl-] in sweat would have inverse relationships with [K+] and the amino acids during exercise. Forearm sweat was collected from 11 recreational athletes at regular intervals during a prolonged period of cycling exercise after 15, 25, 35, 45, 55 and 65 minutes. The subjects also provided passive sweat samples via 15 minutes of thermal stimulation. The sweat samples were analysed for concentrations of amino acids, Na+, Cl-, K+, Mg2+ and Ca2+. The exercise sweat had a total amino acid concentration of 6.4 ± 1.2mM after 15 minutes which was lower than the passive sweat concentration at 11.6 ± 0.8mM (p<0.05) and showed an altered array of electrolytes, indicating that exercise stimulated a change in sweat composition. During the exercise period, [Na+] in sweat increased from 23.3 ± 3.0mM to 34.6 ± 2.4mM (p<0.01) over 65 minutes whilst the total concentrations of amino acids in sweat decreased from 6.4 ± 1.2mM to 3.6 ± 0.5mM. [Na+] showed significant negative correlations with the concentrations of total amino acids (r = -0.97, p<0.05), K+ (r = -0.93, p<0.05) and Ca2+ (r = -0.83, p<0.05) in sweat. The results supported the hypothesis that amino acids and K+, as well as Ca2+, were associated with resorption of Na+ and Cl-.

Metabolomic stability of exercise-induced sweat

Due to increased interest in the use of excreted sweat for biomarker discovery, data must be generated supporting sample collection and handling methods to allow for controlled, large-scale biomarker discovery studies to be performed. In this manuscript, twelve amino acids were quantitated from exercise-induced excreted sweat held at room temperature or a simulated body temperature of 37 °C for up to 90 min. The data illustrate a large dynamic range exists among amino acids in sweat. Additionally, the amino acid quantities vary across individuals and among the same individual under different storage conditions, with alanine, arginine, and threonine showing a significant statistical difference between sampling events (p < 0.05). Furthermore, the results establish amino acids are relatively invariant, at both storage temperatures tested, for up to 90 min illustrated by <10% (15/156) of the amino acids measurements demonstrating change greater than 10% from the time zero value. An untargeted metabolomics approach was also applied to the data set to evaluate global changes to the metabolome. The results show more than 88% of all data points fall within the established limits, regardless of temperature condition and ionization mode. Collectively, this study demonstrates that sweat is largely invariant at two distinct temperatures for up to 90 min. These results establish sweat collection and sample handling is possible for up to 90 min with minimal changes in metabolite abundances.

Sex differences in amino acids lost via sweating could lead to differential susceptibilities to disturbances in nitrogen balance and collagen turnover

Fluid collected during sweating is enriched with amino acids derived from the skin’s natural moisturising factors and has been termed “faux” sweat. Little is known about sex differences in sweat amino acid composition or whether faux sweat amino acid losses affect nitrogen balance. Faux sweat collected by healthy adults (n = 47) after exercise, and at rest by chronic fatigue patients, was analysed for amino acid composition. Healthy females had higher total amino acid concentrations in sweat (10.5 ± 1.2 mM) compared with healthy males (6.9 ± 0.9 mM). Females had higher levels of 13 amino acids in sweat including serine, alanine and glycine. Higher hydroxyproline and proline levels suggested greater collagen turnover in females. Modelling indicated that with conservative levels of exercise, amino acid losses in females via faux sweat were triple than those predicted for urine, whereas in males they were double. It was concluded that females were more susceptible to key amino acid loss during exercise and/or hot conditions. Females reporting chronic fatigue had higher levels of methionine in faux sweat than healthy females. Males reporting chronic fatigue had higher levels of numerous amino acids in faux sweat compared to healthy males. Higher amino acid loss in faux sweat associated with chronic fatigue could contribute to a hypometabolic state. Depending on activity levels, climatic conditions and gender, amino acid losses in sweat and skin leachate could influence daily protein turnover where periods of continuously high turnover could lead to a negative net nitrogen balance.

Sweat facilitated losses of amino acids in Standardbred horses and the application of supplementation strategies to maintain condition during training

Little is known about the amino acid composition of horse sweat, but significant fluid losses can occur during exercise with the potential to facilitate substantial nutrient losses. Sweat and plasma amino acid compositions for Standardbred horses were assessed to determine losses during a standardised training regime. Two cohorts of horses 2013 (n=5) and 2014 (n=6) were assessed to determine baseline levels of plasma and sweat amino acids. An amino acid supplement designed to counter losses in sweat during exercise was provided after morning exercise daily for 5 weeks (2013, n=5; 2014, n=4). After the supplementation period, blood and sweat samples were collected to assess amino acid composition changes. From baseline assessments of sweat in both cohorts, it was found that serine, glutamic acid, histidine and phenylalanine were present at up to 9 times the corresponding plasma concentrations and aspartic acid at 0-2.2 μmol/l in plasma was measured at 154-262 μmol/l in sweat. In contrast, glutamine, asparagine, methionine and cystine were conserved in the plasma by having lower concentrations in the sweat. The predominant plasma amino acids were glycine, glutamine, alanine, valine, serine, lysine and leucine. As the sweat amino acid profile did not simply reflect plasma composition, it was proposed that mechanisms exist to generate high concentrations of certain amino acids in sweat whilst selectively preventing the loss of others. The estimated amino acid load in 16 l of circulating plasma was 3.8-4.3 g and the calculated loss via sweat during high intensity exercise was 1.6-3.0 g. Following supplementation, total plasma amino acid levels from both cohorts increased from initial levels of 2,293 and 2,044 µmol/l to post-supplementation levels of 2,674 and 2,663 µmol/l respectively (P&lt;0.05). It was concluded that the strategy of providing free amino acids immediately after exercise resulted in raising resting plasma amino acid levels.

Study of sample preparation for quantitative analysis of amino acids in human sweat by liquid chromatography–tandem mass spectrometry

The determination of physiological levels of amino acids is important to aid in the diagnosis and treatment of several diseases and nutritional status of individuals. Amino acids are frequently determined in biofluids such as blood (serum or plasma) and urine; however, there are less common biofluids with different concentration profiles of amino acids that could be of interest. One of these biofluids is sweat that can be obtained in a non-invasive manner and is characterized by low complex composition. The analysis of amino acids in human sweat requires the development of sample preparation strategies according to the sample matrix and small collected volume. The influence of sample preparation on the quantitative analysis of amino acids in sweat by LC–MS/MS has been assessed through a comparison between two strategies: dilution of sweat and centrifugal microsolid-phase extraction (c-μSPE). In both cases, several dilution factors were assayed for in-depth knowledge of the matrix effects, and the use of c-μSPE provided the best results in terms of accuracy. The behavior of the target analytes was a function of the dilution factor, thus providing a pattern for sample preparation that depended on the amino acid to be determined. The concentration of amino acids in sweat ranges between 6.20ngmL−1 (for homocysteine) and 259.77µgmL−1 (for serine) with precision, expressed as relative standard deviation, within 1.1–21.4%.

Amino acid losses in human sweat. Influence of oral contraceptives, physical exercise and sex on the excretion of amino acids in sweat (author's transl)

With the aid of ion exchange column chromatography we determined quantitatively the free amino acids in thermal sweat of the total human body surface. Sweat of 60 healthy men and 63 healthy women (aged 18-31 years) collected during 12 min of sauna bathing was investigated. Thirty men and 31 women were well trained, 33 women were taking oral, hormonal contraceptives. Sweat was deproteinised by adding an equal volume of 5% sulphosalicylic acid. 1. The comparison of the women taking oral contraceptives with the women not taking oral contraceptives showed no qualitative or significant quantitative differences in the excretion of amino acids in thermal sweat collected from the total body surface. 2. The comparison of the trained women with the untrained women neither revealed qualitative or significant quantitative differences in the excretion of amino acids in thermal sweat collected from the total body surface. 3. As compared to the trained men, untrained men excreted in thermal sweat collected from the total body surface significantly more alanine, arginine, citrulline, cystine, glycine, histidine, isoleucine, leucine, lysine, phenylalanine, serine, threonine, tyrosine, and valine. 4. The sex-specific comparison of the amino acid excretion in sweat showed that men had a significantly increased excretion of cystine, histidine, leucine, and taurine. Proline was detected only in the sweat of women. 5. The quantitative results obtained for the amino acid excretions during 12 min of sauna bathing suggest that persons exposed to hard, physical activity and/or high environmental temperatures have quite equal amino acid losses in sweat and in 24 h urine.

Total free amino acids, ammonia, and protein in the sweat of children

The concentrations of total free amino acids, ammonia, and protein in sweat of 44 children, 20 males, and 24 females, 6 to 8 years old, were determined. The children were divided into three groups according to their height, weight, and body weight/height ratio; group I children had heights and weights below the 10th percentile for their age, group II had heights and weights between the 10th and 90th percentile, and group III had heights and weights above the 90th percentile. Sweating was induced by allowing the child to be moderately active. The temperature at the time of the experiment was 31 to 33C and the relative humidity 48%. The mean concentrations of total free amino acids (mg/100 ml) in sweat from groups I, II, and III children were 318.9 ± 52.5, 293.9 ± 82.9 and 265.1 ± 57.0, respectively. Alanine, glycine, phenylalanine, threonine, and serine were the principal amino acids in sweat. The concentrations of ammonia in the sweat of group I, II, and HI children were 6.90 ± 2.97, 2.35 ± 0.81, and 1.17 ± 0.48 mg/100 ml, respectively. Protein concentrations were 44.15 ± 14.07, 40.70 ± 16.60, and 35.75 ± 5.46 mg/100 ml, respectively.

Ion-Exchange Chromatography of Amino Acids in Sweat Collected from Healthy Subjects during Sauna Bathing

Abstract Amino acids were measured by ion-exchange liquid chromatography in sweat samples obtained from 22 healthy men during sauna bathing. Amino acids were also measured in plasma (collected before breakfast) and urine (24-h collections) from the same subjects. Serine, ornithine, citrulline, and aspartic acid were present in sweat in mean concentrations &amp;gt;10-fold their mean concentrations in plasma. In contrast, glutamine, cystine, α-aminobutyric acid, and α-aminoadipic acid were present in sweat in mean concentrations that were &amp;lt;0.2 times their mean concentrations in plasma. Concentrations of specific amino acids in sweat bore no apparent relationship to their concentrations in urine. Thus, citrulline was abundant in sweat, whereas only traces of citrulline were found in urine. Conversely, glutamine, taurine, cystine, and several other amino acids were abundant in urine but were present in very low or undetectable concentrations in sweat samples. This study indicates that the physiological mechanisms controlling excretion of amino acids in sweat differ fundamentally from those regulating renal excretion of amino acids.

A study of the free amino acids in sweat from patients with cystic fibrosis.

There has been a paucity of work on the amino acid composition of sweat in healthy and sick children. In cystic fibrosis of the pancreas the sweat glands excrete sodium and chloride in a concentration far above that found in a control group. The potassium is also elevated but to less extent.1,2In view of this dysfunction of the sweat glands in cystic fibrosis it appeared reasonable to investigate other components of sweat. Unpublished work from this laboratory indicates that other constituents in sweat from patients with cystic fibrosis, such as urea, lactic acid, citric acid, sulfate, and phosphorus, do not differ from the normal.3It is intended in this paper to present our findings of the amino acid distribution and of the total α-amino nitrogen concentration in sweat in patients with cystic fibrosis and a control group. Rothman and Sullivan4found 11 amino acids in water-wipings