Effects of PPM1K rs1440581 and rs7678928 on serum branched-chain amino acid levels and risk of cardiovascular disease

OBJECTIVE

This study aimed to investigate the effects of PPM1K rs1440581 and rs7678928 single nucleotide polymorphisms (SNPs) on the serum branched-chain amino acids (BCAAs) levels and cardiovascular disease (CVD) risk.

METHODS

Anthropometric and biochemical examinations were performed at baseline and the end of 4 years in 234 individuals who were randomly recruited from the Diabetes Prevention Programme in Huai'an and received lifestyle intervention and follow up for 4 years. Serum BCAAs (leucine, isoleucine and valine (Val)) levels were measured by hydrophilic interaction chromatography-tandem mass spectrometric method and the PPM1K rs1440581 and rs7678928 were detected by high-throughput SNP genotyping at baseline. The associations of rs1440581 and rs7678928 with serum BCAA levels and risk for CVD after 4 years were further evaluated.

RESULTS

The distribution frequencies of PPM1K rs1440581 and rs7678928 met the Hardy-Weinberg equilibrium (p> .05). The baseline serum levels of Val (p = .022) and total BCAAs (p = .026) in subjects with rs1440581 CC genotype were higher than in those with TT genotype. There were no significant differences in the serum levels of BCAAs among subjects with different genotypes of rs7678928. After 4-year follow-up, the subjects with rs1440581 CC genotype had higher systolic blood pressure (SBP) (p = .027), diastolic blood pressure (DBP) (p = .019), triglycerides (TGs) (p = .019) and lower high-density lipoprotein cholesterol (HDL-c) (p = .008) than those with TT genotype, and had higher AST level than those with TT (p = .030) or TC (p = .003) genotype; the subjects with rs7678928 TT genotype had higher SBP (p = .039) and DBP (p = .019) and lower HDL-c than those with CC (p = .017) genotype. Lifestyle intervention had little influence on the serum levels of fasting plasma glucose (FPG), TG, HDL-c, alanine aminotransferase (ALT), AST and creatinine (CREA) in subjects with rs1440581 CC genotype or rs7678928 TT genotype (p> .05). The incidences of CVD and non-alcoholic fatty liver disease (NAFLD) in subjects with rs1440581 CC genotype were higher than in those with TT genotype; the incidence of CVD in subjects with rs7678928 TT genotype was higher than in those with CC (p < .05) genotype.

CONCLUSIONS

Allele C of PPM1K rs1440581 was associated with elevated serum Val, total BCAAs and CVD risks. rs1440581 CC genotype may be a better marker than baseline serum BCAAs in predicting the risk for CVD.

TRIAL REGISTRATION

Diabetes Prevention Programme in Huai'an of Huai'an Second People's Hospital, ChiCTR-TRC-14005029.KEY MESSAGEAllele C of PPM1K rs1440581 was relevant to elevated serum Val and total BCAAs.PPM1K rs1440581 CC and rs7678928 TT genotypes were associated with CVD risk.PPM1K rs1440581 CC genotype carriers were more likely to have liver injury and develop NAFLD.

Association of Sofosbuvir and Daclatasvir Plasma Trough Concentrations with Patient-, Treatment-, and Disease-Related Factors Among HIV/HCV-Coinfected Persons

BACKGROUND

Sofosbuvir plus daclatasvir achieves high rates of sustained virologic response (SVR), with no differences according to HIV serostatus. However, only limited information is available on the pharmacokinetic variability of sofosbuvir and daclatasvir in HIV/HCV-coinfected patients.

OBJECTIVES

The aim of this study was to identify patient-, treatment-, and disease-related factors that are significantly associated with sofosbuvir and daclatasvir plasma trough concentrations (C_trough), including liver and renal function, among HIV/HCV-coinfected persons.

METHODS

In this observational cohort pilot study, HIV/HCV-coinfected patients undergoing sofosbuvir plus daclatasvir treatment were prospectively enrolled. Biochemical and viro-immunological parameters were assessed at baseline, week 4 (W4), end of treatment (EOT), and after EOT. The FIB-4 score and CKD-EPI equation were used to estimate liver disease and glomerular filtration rate (eGFR), respectively. For sofosbuvir, sofosbuvir metabolite (GS-331007), and daclatasvir, C_trough was measured at W4 and week 8 (W8), and the mean of the values at those two time points (mean-C_trough) was calculated. The Mann-Whitney test and Spearman's rank correlation were used to evaluate the correlations between the mean-C_trough of each direct-acting antiviral (DAA) and the considered variables.

RESULTS

Thirty-five patients were included (SVR 94%). An increased GS-331007 mean-C_trough was significantly correlated with a decreased eGFR at W4 (rho = -0.36; p = 0.037) and EOT (rho = -0.34; p = 0.048). There was a significant correlation between daclatasvir mean-C_trough and FIB-4 at all time points: baseline (rho = -0.35; p = 0.037), W4 (rho = -0.44; p = 0.008), EOT (rho = -0.40; p = 0.023), and after EOT (rho = -0.39; p = 0.028).

CONCLUSIONS

In HIV/HCV-coinfected patients in a real-world setting, exposure to a high GS-331007 C_trough was associated with a slight decrease in renal function, while advanced hepatic impairment was significantly associated with a lower daclatasvir C_trough. Though the clinical and therapeutic relevance of these findings may be limited, increasing clinicians' knowledge regarding DAA exposure in difficult-to-treat patients could be relevant in single cases, and further investigations are warranted.

Associations between Plasma Branched Chain Amino Acids and Health Biomarkers in Response to Resistance Exercise Training Across Age

Leucine, isoleucine and valine (i.e., the branched chain amino acids, BCAA) play a key role in the support and regulation of tissue protein regulation and also as energy substrates. However, positive relationships exist between elevated levels of BCAA and insulin resistance (IR). Thus, we sought to investigate the links between fasting plasma BCAA following a progressive resistance exercise training (RET) programme, an intervention known to improve metabolic health. Fasting plasma BCAA were quantified in adults (young: 18-28 y, n = 8; middle-aged: 45-55 y, n = 9; older: 65-75 y, n = 15; BMI: 23-28 kg/m², both males and females (~50:50), in a cross-sectional, intervention study. Participants underwent 20-weeks whole-body RET. Measurements of body composition, muscle strength (1-RM) and metabolic health biomarkers (e.g., HOMA-IR) were made pre- and post-RET. BCAA concentrations were determined by gas-chromatography mass spectrometry (GC-MS). No associations were observed across age with BCAA; however, RET elicited (p < 0.05) increases in plasma BCAA (all age-groups), while HOMA-IR scores reduced (p < 0.05) following RET. After RET, positive correlations in lean body mass (p = 0.007) and strength gains (p = 0.001) with fasting BCAA levels were observed. Elevated BCAA are not a robust marker of ageing nor IR in those with a healthy BMI; rather, despite decreasing IR, RET was associated with increased BCAA.

Clinical, biochemical, mitochondrial, and metabolomic aspects of methylmalonate semialdehyde dehydrogenase deficiency: Report of a fifth case

Methylmalonate semialdehyde dehydrogenase deficiency (MMSDD; MIM 614105) is a rare autosomal recessive defect of valine and pyrimidine catabolism. Four prior MMSDD cases are published. We present a fifth case, along with functional and metabolomic analysis. The patient, born to non-consanguineous parents of East African origin, was admitted at two weeks of age for failure to thrive. She was nondysmorphic, had a normal brain MRI, and showed mild hypotonia. Gastroesophageal reflux occurred with feeding. Urine organic acid assessment identified excess 3-hydroxyisobutyrate and 3-hydroxypropionate, while urine amino acid analysis identified elevated concentrations of β-aminoisobutyrate and β-alanine. Plasma amino acids showed an elevated concentration of β-aminoisobutyrate with undetectable β-alanine. ALDH6A1 gene sequencing identified a homozygous variant of uncertain significance, c.1261C > T (p.Pro421Ser). Management with valine restriction led to reduced concentration of abnormal analytes in blood and urine, improved growth, and reduced gastroesophageal reflux. Western blotting of patient fibroblast extracts demonstrated a large reduction of methylmalonate semialdehyde dehydrogenase (MMSD) protein. Patient cells displayed compromised mitochondrial function with increased superoxide production, reduced oxygen consumption, and reduced ATP production. Metabolomic profiles from patient fibroblasts demonstrated over-representation of fatty acids and fatty acylcarnitines, presumably due to methylmalonate semialdehyde shunting to β-alanine and subsequently to malonyl-CoA with ensuing increase of fatty acid synthesis. Previously reported cases of MMSDD have shown variable clinical presentation. Our case continues the trend as clinical phenotypes diverge from prior cases. Recognition of mitochondrial dysfunction and novel metabolites in this patient provide the opportunity to assess future patients for secondary changes that may influence clinical outcome.

The Appetite-Suppressant and GLP-1-Stimulating Effects of Whey Proteins in Obese Subjects are Associated with Increased Circulating Levels of Specific Amino Acids

The satiating effect of whey proteins depends upon their unique amino acid composition because there is no difference when comparing whey proteins or a mix of amino acids mimicking the amino acid composition of whey proteins. The specific amino acids underlying the satiating effect of whey proteins have not been investigated to date.

AIMS AND METHODS

The aim of the present study was to evaluate the appetite-suppressant effect of an isocaloric drink containing whey proteins or maltodextrins on appetite (satiety/hunger measured by a visual analogue scale or VAS), anorexigenic gastrointestinal peptides (circulating levels of glucagon-like peptide 1 (GLP-1) and peptide tyrosine tyrosine (PYY)) and amino acids (circulating levels of single, total [TAA] and branched-chain amino acids [BCAA]) in a cohort of obese female subjects (n = 8; age: 18.4 ± 3.1 years; body mass index, BMI: 39.2 ± 4.6 kg/m²).

RESULTS

Each drink significantly increased satiety and decreased hunger, the effects being more evident with whey proteins than maltodextrins. Similarly, circulating levels of GLP-1, PYY and amino acids (TAA, BCAA and alanine, arginine, asparagine, citrulline, glutamine, hydroxyproline, isoleucine, histidine, leucine, lysine, methionine, ornithine, phenylalanine, proline, serine, threonine, tyrosine, and valine) were significantly higher with whey proteins than maltodextrins. In subjects administered whey proteins (but not maltodextrins), isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine, and valine were significantly correlated with hunger (negatively), satiety, and GLP-1 (positively).

CONCLUSIONS

Eight specific amino acids (isoleucine, leucine, lysine, methionine, phenylalanine, proline, tyrosine, and valine) were implicated in the appetite-suppressant and GLP-1-stimulating effects of whey proteins, which may be mediated by their binding with nutrient-sensing receptors expressed by L cells within the gastrointestinal wall. The long-term satiating effect of whey proteins and the effectiveness of a supplementation with these amino acids (i.e., as a nutraceutical intervention) administered during body weight reduction programs need to be further investigated.

Dietary Intakes of Branched Chain Amino Acids and the Incidence of Hypertension: A Population-Based Prospective Cohort Study

BACKGROUND

Dietary amino acids have been associated with blood pressure (BP) in previous studies; we conducted this study to examine the association between dietary branched chain amino acids (BCAAs) and the incidence of hypertension among participants of the Tehran Lipid and Glucose Study (TLGS).

METHODS

Analyses were conducted on 4,288 participants aged 20-70 years, who were free of hypertension at baseline (2008- 2011) and were followed for 3 years (2011-2014) to ascertain incident hypertension. Dietary intakes of BCAAs including, valine, leucine, and isoleucine were collected at baseline using the food frequency questionnaire (FFQ). Odds ratio (OR) of hypertension were determined by logistic regression across quartiles of BCAAs, adjusted for sex, age, smoking status, physical activity, body mass index (BMI), diabetes, and some dietary factors.

RESULTS

The mean ± standard deviation for age and BMI of participants (41.9% men) were 39.7 ± 12.8 years and 26.9 ± 4.6 kg/ m2 , respectively. The median intakes of total BCAAs, valine, leucine, and isoleucine was 17.9, 5.5, 7.8, and 4.5 percentage of total amino acids intake, respectively. We documented 429 (10%) hypertension incident cases. The multivariable adjusted OR for the highest vs lowest quartiles of BCAAs was 1.54 (95% confidence interval (CI):1.03-2.32; P for trend = 0.05); furthermore, the OR (95% CI) of hypertension for the highest vs the lowest quartile of valine was 1.61 (1.10-2.36; P for trend = 0.009) in the fully adjusted model. However, we found no significant association between leucine and isoleucine with incidence of hypertension.

CONCLUSION

Findings indicated that higher BCAA intake, in particular valine, is associated with higher risk of incident hypertension.

Seminal plasma amino acid profile in different breeds of chicken: Role of seminal plasma on sperm cryoresistance

Seminal plasma is a key biological fluid that modulates sperm function in the reproduction process. However, its role in sperm biotechnologies is scarce in poultry. The aims of the present study were to study the amino acids profile and total proteins of seminal plasma in 12 Spanish chicken breeds and to investigate the role of seminal plasma on cryoresistance of rooster sperm. To investigate the role of seminal plasma on cryoresistance, diluted pooled semen samples were cryopreserved in the presence and absence of seminal plasma. Glutamic acid was the most abundant free amino acid in seminal plasma, followed by alanine, serine, valine, and glycine. There was an influence of breed (P<0.05) on the percentage of viable sperm after freezing-thawing of samples with seminal plasma. Cluster analysis revealed that White Prat, Black Castellana, Blue Andaluza, Quail Castellana, and Red-Barred Vasca returned the best freezing-thawing response (good freezers). There was a positive correlation between seminal plasma concentrations of valine, isoleucine lysine, leucine and post thaw viability. The evaluation of fertilization capacity of frozen-thawed semen from the breeds White Prat ('good freezer') and Black-Red Andaluza ('bad freezer') showed that good freezer had higher fertility (20/68, 29.4%) compared to bad freezer breed (14/76, 18.4%), even if the difference was not significant (P = 0.08). The TUNEL assay revealed that freezing/thawing procedures in presence of seminal plasma provoked higher DNA fragmentation in most of the breeds, with a positive correlation between seminal alanine, valine, isoleucine, methionine, leucine, tyrosine, phenylalanine concentrations and DNA integrity. DNA fragmentation was lower in absence of seminal plasma and the breed effect on sperm viability was highly reduced. It is concluded that specific seminal plasma amino acids were associated with post-thaw percentage of viable sperm and DNA integrity. The removal of seminal plasma decreases the variability of the results and DNA fragmentation damages.

Metabolites predict cardiovascular disease events in persons living with HIV: a pilot case-control study

INTRODUCTION

Persons living with HIV (PLWH) are at higher risk for cardiovascular disease (CVD) events than uninfected persons. Current risk-stratification methods to define PLWH at highest risk for CVD events are lacking.

METHODS

Using tandem flow injection mass spectrometry, we quantified plasma levels of 60 metabolites in 24 matched pairs of PLWH [1:1 with and without known coronary artery disease (CAD)]. Metabolite levels were reduced to interpretable factors using principal components analysis.

RESULTS

Factors derived from short-chain dicarboxylacylcarnitines (SCDA) (p = 0.08) and glutamine/valine (p = 0.003) were elevated in CAD cases compared to controls.

CONCLUSION

SCDAs and glutamine/valine may be valuable markers of cardiovascular risk among persons living with HIV in the future, pending validation in larger cohorts.

Effects of medical food leucine content in the management of methylmalonic and propionic acidemias

PURPOSE OF REVIEW

The current review highlights the varied effects of medical foods high in leucine (Leu) and devoid of valine (Val) and isoleucine (Ile) in the management of methylmalonic acidemia (MMA) and propionic acidemia and cobalamin C (cblC) deficiency, aiming to advance dietary practices.

RECENT FINDINGS

Leu is a key metabolic regulator with a multitude of effects on different organ systems. Recent observational studies have demonstrated that these effects can have unintended consequences in patients with MMA as a result of liberal use of medical foods. The combination of protein restriction and medical food use in MMA and propionic acidemia results in an imbalanced branched-chain amino acid (BCAA) dietary content with a high Leu-to-Val and/or Ile ratio. This leads to decreased plasma levels of Val and Ile and predicts impaired brain uptake of multiple essential amino acids. Decreased transport of methionine (Met) across the blood-brain barrier due to high circulating Leu levels is of particular concern in cblC deficiency in which endogenous Met synthesis is impaired.

SUMMARY

Investigations into the optimal composition of medical foods for MMA and propionic acidemia, and potential scenarios in which Leu supplementation may be beneficial are needed. Until then, MMA/propionic acidemia medical foods should be used judiciously in the dietary management of these patients and avoided altogether in cblC deficiency.

In Silico Absorption Analysis of Valacyclovir in Wildtype and Pept1 Knockout Mice Following Oral Dose Escalation

PURPOSE

We developed simulation and modeling methods to predict the in vivo pharmacokinetic profiles of acyclovir, following escalating oral doses of valacyclovir, in wildtype and Pept1 knockout mice. We also quantitated the contribution of specific intestinal segments in the absorption of valacyclovir in these mice.

METHODS

Simulations were conducted using a mechanistic advanced compartmental absorption and transit (ACAT) model implemented in GastroPlus™. Simulations were performed for 3 h post-dose in wildtype and Pept1 knockout mice following single oral doses of 10, 25, 50 and 100 nmol/g valacyclovir, and compared to experimentally observed plasma concentration-time profiles of acyclovir.

RESULTS

Good fits were obtained in wildtype and Pept1 knockout mice. Valacyclovir was primarily absorbed from duodenum (42%) and jejunum (24%) of wildtype mice, with reduced uptake from ileum (3%) and caecum/colon (1%), for a total of 70% absorption. In contrast, the absorption of valacyclovir in Pept1 knockout mice was slow and sustained throughout the entire intestinal tract in which duodenum (4%), jejunum (14%), ileum (10%) and caecum/colon (12%) accounted for a total of 40% absorption.

CONCLUSION

The ACAT model bridged the gap between in situ and in vivo experimental findings, and facilitated our understanding of the complicated intestinal absorption processes of valacyclovir.

Neurocognitive profiles in MSUD school-age patients

Maple syrup urine disease (MSUD), an inborn error of amino acids catabolism is characterized by accumulation of branched chain amino acids (BCAAs) leucine, isoleucine, valine and their corresponding alpha-ketoacids. Impact on the cognitive development has been reported historically, with developmental delays of varying degree. Currently, earlier diagnosis and improved management allow a better neurodevelopment, without requirement of special education. However, specific impairments can be observed, and so far, results of detailed neurocognitive assessments are not available. The aim of this study was to analyse neurocognitive profiles of French MSUD patients. This was a multicentre retrospective study on MSUD patients who underwent neurocognitive evaluation at primary school age. Twenty-one patients with classical neonatal onset MSUD were included. The patients' mean age at the time of evaluation was 8.7 years. The mean intellectual quotient (IQ) score was in the normal range (95.1 ± 12.6). In a subset of eight patients, a consistent developmental pattern of higher verbal than performance IQ was observed (mean of the difference 25.7 ± 8.7, p < 0.0001). No correlation could be established between this pattern and long-term metabolic balance (BCAA blood levels), or severity of acute metabolic imbalances, or leucine blood levels at diagnosis and time to toxin removal procedure. These data show that some MSUD patients may exhibit an abnormal neurocognitive profile with higher verbal than performance abilities. This might suggest an executive dysfunction disorder that would need to be further investigated by specialized testing. This pattern is important to detect in MSUD, as appropriate neuropsychological treatment strategies should be proposed.

High concentration of branched-chain amino acids promotes oxidative stress, inflammation and migration of human peripheral blood mononuclear cells via mTORC1 activation

Leucine, isoleucine and valine are essential aminoacids termed branched-chain amino acids (BCAA) due to its aliphatic side-chain. In several pathological and physiological conditions increased BCAA plasma concentrations have been described. Elevated BCAA levels predict insulin resistance development. Moreover, BCAA levels higher than 2mmol/L are neurotoxic by inducing microglial activation in maple syrup urine disease. However, there are no studies about the direct effects of BCAA in circulating cells. We have explored whether BCAA could promote oxidative stress and pro-inflammatory status in peripheral blood mononuclear cells (PBMCs) obtained from healthy donors. In cultured PBMCs, 10mmol/L BCAA increased the production of reactive oxygen species (ROS) via both NADPH oxidase and the mitochondria, and activated Akt-mTOR signalling. By using several inhibitors and activators of these molecular pathways we have described that mTOR activation by BCAA is linked to ROS production and mitochondrial dysfunction. BCAA stimulated the activation of the redox-sensitive transcription factor NF-κB, which resulted in the release of pro-inflammatory molecules, such as interleukin-6, tumor necrosis factor-α, intracellular adhesion molecule-1 or CD40L, and the migration of PBMCs. In conclusion, elevated BCAA blood levels can promote the activation of circulating PBMCs, by a mechanism that involving ROS production and NF-κB pathway activation. These data suggest that high concentrations of BCAA could exert deleterious effects on circulating blood cells and therefore contribute to the pro-inflammatory and oxidative status observed in several pathophysiological conditions.

The metabolites in peripheral blood mononuclear cells showed greater differences between patients with impaired fasting glucose or type 2 diabetes and healthy controls than those in plasma

To determine differences between peripheral blood mononuclear cells and the plasma metabolites in patients with impaired fasting glucose or type 2 diabetes and healthy controls. In all, 65 nononobese patients (aged 30-70 years) with impaired fasting glucose or type 2 diabetes and 65 nonobese sex-matched healthy controls were included, and fasting peripheral blood mononuclear cell and plasma metabolomes were profiled. The diabetic or impaired fasting glucose patients showed higher circulating and peripheral blood mononuclear cell lipoprotein phospholipase A₂ activities, high-sensitivity C-reactive protein and tumour necrosis factor-α than controls. Compared with controls, impaired fasting glucose or diabetic subjects showed increases in 11 peripheral blood mononuclear cell metabolites: six amino acids (valine, leucine, methionine, phenylalanine, tyrosine and tryptophan), l-pyroglutamic acid, two fatty acid amides containing palmitic amide and oleamide and two lysophosphatidylcholines. In impaired fasting glucose or diabetic patients, peripheral blood mononuclear cell lipoprotein phospholipase A₂ positively associated with peripheral blood mononuclear cell lysophosphatidylcholines and circulating inflammatory markers, including tumour necrosis factor-α, high-sensitivity C-reactive protein and lipoprotein phospholipase A₂ activities. In plasma metabolites between patients and healthy controls, we observed significant increases in only three amino acids (proline, valine and leucine) and decreases in only five lysophosphatidylcholines. This study demonstrates significant differences in the peripheral blood mononuclear cell metabolome in patients with impaired fasting glucose or diabetes compared with healthy controls. These differences were greater than those observed in the plasma metabolome. These data suggest peripheral blood mononuclear cells as a useful tool to better understand the inflammatory pathophysiology of diabetes.

"Zombie" Outbreak Caused by the Synthetic Cannabinoid AMB-FUBINACA in New York

BACKGROUND

New psychoactive substances constitute a growing and dynamic class of abused drugs in the United States. On July 12, 2016, a synthetic cannabinoid caused mass intoxication of 33 persons in one New York City neighborhood, in an event described in the popular press as a "zombie" outbreak because of the appearance of the intoxicated persons.

METHODS

We obtained and tested serum, whole blood, and urine samples from 8 patients among the 18 who were transported to local hospitals; we also tested a sample of the herbal "incense" product "AK-47 24 Karat Gold," which was implicated in the outbreak. Samples were analyzed by means of liquid chromatography-quadrupole time-of-flight mass spectrometry.

RESULTS

The synthetic cannabinoid methyl 2-(1-(4-fluorobenzyl)-1H-indazole-3-carboxamido)-3-methylbutanoate (AMB-FUBINACA, also known as MMB-FUBINACA or FUB-AMB) was identified in AK-47 24 Karat Gold at a mean (±SD) concentration of 16.0±3.9 mg per gram. The de-esterified acid metabolite was found in the serum or whole blood of all eight patients, with concentrations ranging from 77 to 636 ng per milliliter.

CONCLUSIONS

The potency of the synthetic cannabinoid identified in these analyses is consistent with strong depressant effects that account for the "zombielike" behavior reported in this mass intoxication. AMB-FUBINACA is an example of the emerging class of "ultrapotent" synthetic cannabinoids and poses a public health concern. Collaboration among clinical laboratory staff, health professionals, and law enforcement agencies facilitated the timely identification of the compound and allowed health authorities to take appropriate action.

[Plasma metabonomics of Guifu Dihuang Wan in the treatment of yang deficiency]

OBJECTIVE

To assess the effect of Guifu Dihuang Wan (GFDHW) in the treatment of yang deficiency and explore the underlying molecular mechanism.

METHODS

Sixty-two participants without diseases were randomized into control group (n=31) and experimental group (n=31) and were given lifestyle intervention additional GFDHW treatment for a month. NMR technology was used for metabonomics analysis.

RESULTS

Intervention with GFDHW resulted in significantly decreased conversion scores of yang deficiency in the experimental group compared with the control group (P<0.005). The concentrations of lactate, valine, proline, arginine and 3-hydroxybutyrate were increased in the plasma of yang-deficient subjects after lifestyle intervention. GFDHW treatment with lifestyle intervention significantly increased the concentrations of lactate, valine, proline, arginine and 3-hydroxybutyrate and also the levels of alanine, glutamine, alpha glucose, isoleucine, betaine and propylene glycol.

CONCLUSION

GFDHW treatment improves yang deficiency possibly by increasing the concentrations of alanine, glutamine, alpha glucose, isoleucine, betaine and propylene glycol and promoting energy metabolism of the body.

Short-term health effects in the general population following a major train accident with acrylonitrile in Belgium

BACKGROUND

Following a train derailment, several tons of acrylonitrile (ACN) exploded, inflamed and part of the ACN ended up in the sewage system of the village of Wetteren. More than 2000 residents living in the close vicinity of the accident and along the sewage system were evacuated. A human biomonitoring study of the adduct N-2-cyanoethylvaline (CEV) was carried out days 14-21 after the accident.

OBJECTIVES

(1) To describe the short-term health effects that were reported by the evacuated residents following the train accident, and (2) to explore the association between the CEV concentrations, extrapolated at the time of the accident, and the self-reported short-term health effects.

METHODS

Short-term health effects were reported in a questionnaire (n=191). An omnibus test of independence was used to investigate the association between the CEV concentrations and the symptoms. Dose-response relationships were quantified by Generalized Additive Models (GAMs).

RESULTS

The most frequently reported symptoms were local symptoms of irritation. In non-smokers, dose-dependency was observed between the CEV levels and the self-reporting of irritation (p=0.007) and nausea (p=0.007). Almost all non-smokers with CEV concentrations above 100pmol/g globin reported irritation symptoms. Both absence and presence of symptoms was reported by non-smokers with CEV concentrations below the reference value and up to 10 times the reference value. Residents who visited the emergency services reported more symptoms. This trend was seen for the whole range of CEV concentrations, and thus independently of the dose.

DISCUSSION AND CONCLUSION

The present study is one of the first to relate exposure levels to a chemical released during a chemical incident to short-term (self-reported) health effects. A dose-response relation was observed between the CEV concentrations and the reporting of short-term health effects in the non-smokers. Overall, the value of self-reported symptoms to assess exposure showed to be limited. The results of this study confirm that a critical view should be taken when considering self-reported health complaints and that ideally biomarkers are monitored to allow an objective assessment of exposure.

Ratios of N-(2,3,4-trihydroxybutyl) valine and N-(2-hydroxy-3-butenyl) valine formed hemoglobin adducts in female mice inhalation exposure with 1,3-butadiene

1,3-Butadiene (BD) is a known rodent and probable human carcinogen (IARC, group 2A) or ‘known to be a human carcinogen’ (Department of Health and Human Services, 2000). Exposure to BD can occur either via petrochemical products or through the general environment. Adducts can be used as biomarkers for biological monitoring of carcinogen exposure. This study investigated the hemoglobin adducts in blood after inhalation exposure to BD in ICR female mice for three weeks (5 h/day-5 days/week). During the inhalation exposure, the body weights of mice were significantly lower from day 9 onward for the 500 ppm BD group and from day 4 onward for the 1000 ppm BD group. On the 1st, 2nd and 3rd weeks after inhalation exposure, the concentrations of HB Val adducts were 1.8, 3.7 and 6.2 pmol/mg globin for the 500 ppm BD group, and 5.7, 7.4 and 16.0 pmol/mg globin for the 1000 ppm BD group. The concentrations of THB Val adducts were 32.0, 42.0 and 55.0 pmol/mg globin for the 500 ppm BD group, and 67.8, 72.7 and 83.5 pmol/mg globin for the 1000 ppm BD group. Their defined ratios were higher at the earlier exposure period and at the lower concentration. They were 17.8, 11.4 and 8.87 for the 500 ppm BD group, and 11.9, 9.8 and 5.2 for the 1000 ppm BD group, on the 1st, 2nd and 3rd weeks after inhalation exposure. THB Val and HB Val adducts appear to be the important hemoglobin adducts for monitoring BD exposure, with the latter being a more predictable biomarker than the former.

Effects of Alpha-Ketoglutarate on Glutamine Metabolism in Piglet Enterocytes in Vivo and in Vitro

Alpha-ketoglutarate (AKG) plays a vital part in the tricarboxylic acid cycle and is a key intermediate in the oxidation of L-glutamine (Gln). The study was to evaluate effects of AKG on Gln metabolism in vivo and in vitro. A total of twenty-one piglets were weaned at 28 days with a mean body weight (BW) of 6.0 ± 0.2 kg, and randomly divided into 3 groups: corn soybean meal based diet (CON group); the basal diet with 1% alpha-ketoglutarate (AKG treatment group); and the basal diet with 1% L-glutamine (GLN treatment group). Intestinal porcine epithelial cells-1 (IPEC-1) were incubated to investigate effects of 0.5, 2, and 3 mM AKG addition on Gln metabolism. Our results showed that there were no differences (P > 0.05) among the 3 treatments in initial BW, final BW, and average daily feed intake. However, average daily gain (P = 0.013) and gain:feed (P = 0.041) of the AKG group were greater than those of the other two groups. In comparison with the CON group, the AKG and GLN groups exhibited an improvement in villus length, mucosal thickness, and crypt depth in the jejunum of piglets. Serum concentrations of Asp, Glu, Val, Ile, Tyr, Phe, Lys, and Arg in the piglets fed the 1% AKG or Gln diet were lower than those in the CON group. Compared with the CON group, the mRNA expression of jejunal and ileal amino acid (AA) transporters in the AKG and GLN groups were significantly increased (P < 0.05). Additionally, the in vitro study showed that the addition of 0.5, 2, and 3 mM AKG dose-dependently decreased (P < 0.05) the net utilization of Gln and formulation of ammonia, Glu, Ala, and Asp by IPEC-1. In conclusion, dietary AKG supplementation, as a replacement for Gln, could improve Gln metabolism in piglet enterocytes and enhance the utilization of AA.

Living related versus deceased donor liver transplantation for maple syrup urine disease

Maple syrup urine disease (MSUD) is an inherited disorder of branched chain ketoacid (BCKA) oxidation associated with episodic and chronic brain disease. Transplantation of liver from an unrelated deceased donor restores 9-13% whole-body BCKA oxidation capacity and stabilizes MSUD. Recent reports document encouraging short-term outcomes for MSUD patients who received a liver segment from mutation heterozygous living related donors (LRDT). To investigate effects of living related versus deceased unrelated grafts, we studied four Brazilian MSUD patients treated with LRDT who were followed for a mean 19 ± 12 postoperative months, and compared metabolic and clinical outcomes to 37 classical MSUD patients treated with deceased donor transplant. Patient and graft survival for LRDT were 100%. Three of 4 MSUD livers were successfully domino transplanted into non-MSUD subjects. Following LRDT, all subjects resumed a protein-unrestricted diet as mean plasma leucine decreased from 224 ± 306 μM to 143 ± 44 μM and allo-isoleucine decreased 91%. We observed no episodes of hyperleucinemia during 80 aggregate postoperative patient-months. Mean plasma leucine:isoleucine:valine concentration ratios were ~2:1:4 after deceased donor transplant compared to ~1:1:1.5 following LRDT, resulting in differences of predicted cerebral amino acid uptake. Mutant heterozygous liver segments effectively maintain steady-state BCAA and BCKA homeostasis on an unrestricted diet and during most catabolic states, but might have different metabolic effects than grafts from unrelated deceased donors. Neither living related nor deceased donor transplant affords complete protection from metabolic intoxication, but both strategies represent viable alternatives to nutritional management.

Insight in genome-wide association of metabolite quantitative traits by exome sequence analyses

Metabolite quantitative traits carry great promise for epidemiological studies, and their genetic background has been addressed using Genome-Wide Association Studies (GWAS). Thus far, the role of less common variants has not been exhaustively studied. Here, we set out a GWAS for metabolite quantitative traits in serum, followed by exome sequence analysis to zoom in on putative causal variants in the associated genes. ¹H Nuclear Magnetic Resonance (¹H-NMR) spectroscopy experiments yielded successful quantification of 42 unique metabolites in 2,482 individuals from The Erasmus Rucphen Family (ERF) study. Heritability of metabolites were estimated by SOLAR. GWAS was performed by linear mixed models, using HapMap imputations. Based on physical vicinity and pathway analyses, candidate genes were screened for coding region variation using exome sequence data. Heritability estimates for metabolites ranged between 10% and 52%. GWAS replicated three known loci in the metabolome wide significance: CPS1 with glycine (P-value  = 1.27×10⁻³²), PRODH with proline (P-value  = 1.11×10⁻¹⁹), SLC16A9 with carnitine level (P-value  = 4.81×10⁻¹⁴) and uncovered a novel association between DMGDH and dimethyl-glycine (P-value  = 1.65×10⁻¹⁹) level. In addition, we found three novel, suggestively significant loci: TNP1 with pyruvate (P-value  = 1.26×10⁻⁸), KCNJ16 with 3-hydroxybutyrate (P-value  = 1.65×10⁻⁸) and 2p12 locus with valine (P-value  = 3.49×10⁻⁸). Exome sequence analysis identified potentially causal coding and regulatory variants located in the genes CPS1, KCNJ2 and PRODH, and revealed allelic heterogeneity for CPS1 and PRODH. Combined GWAS and exome analyses of metabolites detected by high-resolution ¹H-NMR is a robust approach to uncover metabolite quantitative trait loci (mQTL), and the likely causative variants in these loci. It is anticipated that insight in the genetics of intermediate phenotypes will provide additional insight into the genetics of complex traits.

Human metabolic individuality is under strict control of genetic and environmental factors. In our study, we aimed to find the genetic determinants of circulating molecules in sera of large set of individuals representing the general population. First, we performed a hypothesis-free genome wide screen in this population to identify genetic regions of interest. Our study confirmed four known gene metabolite connections, but also pointed to four novel ones. Genome-wide screens enriched for common intergenic variants may miss causal genetic variations directly changing the protein sequence. To investigate this further, we zoomed into regions of interest and tested whether the association signals obtained in the first stage were direct, or whether they represent causal variations, which were not captured in the initial panel. These subsequent tests showed that protein coding and regulatory variations are involved in metabolite levels. For two genomic regions we also found that genes harbour more than one causal variant influencing metabolite levels independent of each other. We also observed strong connection between markers of cardio-metabolic health and metabolites. Taken together, our novel loci are of interest for further research to investigate the causal relation to for instance type 2 diabetes and cardiovascular disease.

Increased amino acids levels and the risk of developing of hypertriglyceridemia in a 7-year follow-up

BACKGROUND

Recently, five branched-chain and aromatic amino acids were shown to be associated with the risk of developing type 2 diabetes (T2D).

AIM

We set out to examine whether amino acids are also associated with the development of hypertriglyceridemia.

MATERIALS AND METHODS

We determined the serum amino acids concentrations of 1,125 individuals of the KORA S4 baseline study, for which follow-up data were available also at the KORA F4 7 years later. After exclusion for hypertriglyceridemia (defined as having a fasting triglyceride level above 1.70 mmol/L) and diabetes at baseline, 755 subjects remained for analyses.

RESULTS

Increased levels of leucine, arginine, valine, proline, phenylalanine, isoleucine and lysine were significantly associated with an increased risk of hypertriglyceridemia. These associations remained significant when restricting to those individuals who did not develop T2D in the 7-year follow-up. The increase per standard deviation of amino acid level was between 26 and 40 %.

CONCLUSIONS

Seven amino acids were associated with an increased risk of developing hypertriglyceridemia after 7 years. Further studies are necessary to elucidate the complex role of these amino acids in the pathogenesis of metabolic disorders.

NMR-based metabolomics and breath studies show lipid and protein catabolism during low dose chronic T(1)AM treatment

OBJECTIVE

3-Iodothyronamine (T1 AM), an analog of thyroid hormone, is a recently discovered fast-acting endogenous metabolite. Single high-dose treatments of T1 AM have produced rapid short-term effects, including a reduction of body temperature, bradycardia, and hyperglycemia in mice.

DESIGN AND METHODS

The effect of daily low doses of T1 AM (10 mg/kg) for 8 days on weight loss and metabolism in spontaneously overweight mice was monitored. The experiments were repeated twice (n = 4). Nuclear magnetic resonance (NMR) spectroscopy of plasma and real-time analysis of exhaled (13) CO2 in breath by cavity ring down spectroscopy (CRDS) were used to detect T1 AM-induced lipolysis.

RESULTS

CRDS detected increased lipolysis in breath shortly after T1 AM administration that was associated with a significant weight loss but independent of food consumption. NMR spectroscopy revealed alterations in key metabolites in serum: valine, glycine, and 3-hydroxybutyrate, suggesting that the subchronic effects of T1 AM include both lipolysis and protein breakdown. After discontinuation of T1 AM treatment, mice regained only 1.8% of the lost weight in the following 2 weeks, indicating lasting effects of T1 AM on weight maintenance.

CONCLUSIONS

CRDS in combination with NMR and (13) C-metabolic tracing constitute a powerful method of investigation in obesity studies for identifying in vivo biochemical pathway shifts and unanticipated debilitating side effects.

Plasma sphingolipids are biomarkers of metabolic syndrome in non-human primates maintained on a Western-style diet

BACKGROUND

The intake of a Western diet enriched in animal fat has been shown to be a major risk factor for Type 2 diabetes and obesity. Previous rodent studies have indicated that these conditions may be triggered by the accumulation of the sphingolipid ceramide in insulin-sensitive tissues. However, data are lacking in this regard from both humans and non-human primates.

OBJECTIVE

Here we have investigated the relationship between plasma ceramides and metabolic syndrome in Rhesus macaques fed a high-fat and high-fructose (HFFD) 'western' diet.

METHODS

We investigated this relationship in cohorts of monkeys fed a HFFD for a period of 8 months to 5 years. Animals were classified as control, pre-diabetic or diabetic based on fasting plasma parameters and insulin sensitivity.

RESULTS

HFFD treatment produced significant increases in body weight and body fat and also resulted in a decline in insulin sensitivity. In parallel to the reduction in insulin sensitivity, significant increases in both plasma ceramide and dihydroceramide levels were observed, which further increased as animals progressed to the diabetic state. Plasma levels of the rare sphingolipid C18:0 deoxysphinganine, a marker of increased metabolic flux through serine palmitoyl transferase (SPT), were also elevated in both pre- and diabetic animals. Furthermore, plasma serine levels were significantly elevated in diabetic monkeys, which may indicate a shift in SPT substrate selectivity from serine to alanine or glycine. In contrast, branch chain amino acids were unchanged in pre-diabetic non-human primates, and only plasma valine levels were elevated in diabetic animals.

CONCLUSION

Together, these data indicate that HFFD induces de novo synthesis of ceramides in non-human primates, and that increased production of plasma ceramides is significantly correlated with the decline in insulin sensitivity.

[Clinical characteristics and analysis of mass spectrometric data in 33 patients with maple syrup urine disease]

OBJECTIVE

To explore the clinical characteristics and the diagnostic method of maple syrup urine disease (MSUD).

METHODS

From January 2003 to December 2011, a total of 14 000 patients with suspected inherited metabolism diseases were tested. The blood levels of leucine and valine of these patients were detected by tandem mass spectrometry. The urinary level of branched-chain α-ketoacids was tested by gas chromatography-mass spectrometry. And the diagnosis was based on the elevated levels of leucine and valine in blood and branched-chain α-ketoacids in urine.

RESULTS

Thirty-three MSUD patients were confirmed. Their median age of initial visit was 0.17 years old (range: 7 days to 30 years old). The peak onset age of them was 2-30 days old, including 28 cases of neonatal onset (84.8%). The presenting symptoms of 28 cases were feeding difficulties (n=14), poor response, lethargy and seizures. Their median blood levels of leucine and valine (1901 (458-5804) and 600 (315-1617) µmol/L) were significantly higher than their normal levels ((50-300) and (60-250) µmol/L, both P<0.01). Their urinary levels of 2-OH-isovaleric acid, 2-keto-isovaleric acid, 2-keto-3-methylvaleric acid, 2-keto-isocaproic and acetylglycine (262.5 (5.4-624.3), 35.8 (1.9-156.0), 133.8 (7.4-611.5), 518.7 (17.2-2121.2) and 280.5 (11.0-1087.9) respectively) significantly higher than their normal levels (0, <0.1, 0, 0, <0.1 respectively, all P<0.01). In 5 intermittent MSUD patients, their blood levels of leucine and valine (402 (348-958) and 556 (322-808) µmol/L) were significantly higher than their normal levels (both P<0.01). The urinary level of 2-OH-isovaleric acid was significantly higher than its normal levels (P<0.01) while the urinary levels of other α-ketoacids were normal.

CONCLUSIONS

The confirmation of MSUD remains difficult because of a lack of specific clinical features. The detections of tandem mass spectrometry and gas chromatography-mass spectrometry may aid its early diagnosis.

High-carbohydrate/low-protein-induced hyperinsulinemia does not improve protein balance in children after cardiac surgery

OBJECTIVE

In pediatric cardiac surgery, fluid-restricted low-protein (LoProt) diets account for cumulative protein deficits with increased morbidity. In this setting, we aimed to inhibit proteolysis by a high-carbohydrate (HiCarb)-intake-induced hyperinsulinemia and improve protein balance.

METHODS

The effect of a HiCarb/LoProt (glucose 10 mg · kg(-1) · min(-1)/protein 0.7 g · kg(-1) · d(-1)) versus a normal-carbohydrate (NormCarb)/LoProt (glucose 7.5 mg · kg(-1) · min(-1)/protein 0.3 g · kg(-1) · d(-1)) enteral diet on whole-body protein breakdown and balance was compared in a prospective, randomized, single-blinded trial in 24 children after cardiac surgery. On the second postoperative day, plasma insulin and amino acid concentrations, protein breakdown (endogenous rate of appearance of valine), protein synthesis (non-oxidative disposal of valine), protein balance, and the rate of appearance of urea were measured by using an isotopic infusion of [1-(13)C]valine and [(15)N(2)]urea.

RESULTS

The HiCarb/LoProt diet led to a serum insulin concentration that was three times higher than the NormCarb/LoProt diet (596 pmol/L, 80-1833, and 198 pmol/L, 76-1292, respectively, P = 0.02), without differences in plasma glucose concentrations. There were no differences in plasma amino acid concentrations, non-oxidative disposal of valine, and endogenous rate of appearance of valine between the groups, with a negative valine balance in the two groups (-0.65 μmol · kg(-1) · min(-1), -1.91 to 0.01, and -0.58 μmol · kg(-1) · min(-1), -2.32 to -0.07, respectively, P = 0.71). The serum cortisol concentration in the HiCarb/LoProt group was lower compared with the NormCarb/LoProt group (204 nmol/L, 50-544, and 532 nmol/L, 108-930, respectively, P = 0.02).

CONCLUSION

In children with fluid restriction after cardiac surgery, a HiCarb/LoProt diet compared with a NormCarb/LoProt diet stimulates insulin secretion but does not inhibit proteolysis further and therefore cannot be advocated for this purpose.

Validation of a capillary electrophoresis method for the simultaneous determination of amlodipine besylate and valsartan in pharmaceuticals and human plasma

A rapid, simple, and sensitive capillary electrophoresis (CE) method was developed and validated for the simultaneous determination of amlodipine (AML) and valsartan (VAL) in pharmaceuticals and human plasma using a UV photodiode array detector. Electrophoretic conditions were optimized to improve separation, sensitivity, and rapidity. The optimal conditions were 25 mM phosphate buffer at pH 8.0, injection time 10.0 s, voltage 25 kV, and column temperature 25 degrees C, with detection at 214 nm. The method was found to be linear in the range of 1.0-35 and 1.0-350 mg/L, with weighted regression 0.9999 and 0.9994, for AML and VAL, respectively. Validation of the method showed acceptable intraday and interday accuracy (85.5-95.3%) and precision (RSD 1.64-4.2%) in pharmaceutical formulation and human plasma analysis. The sensitivity of the method was enhanced by both optimization of the CE procedure and preconcentration performed by liquid-liquid extraction. The LOD for both AML and VAL was 0.03 mg/L, which allows analysis at the level of the drugs possibly found in human plasma. Therefore, the proposed method is suitable for QC in pharmaceutical laboratories and therapeutic drug monitoring in clinical laboratories.

A LC-MS-based method for quantification of biomarkers from serum of allergic rats

Allergies are highly complex disorders with clinical manifestations ranging from mild oral, gastrointestinal, recurrent wheezing, and cutaneous symptoms to life-threatening systemic conditions. The levels of arachidonic acid, eicosanoids, histamine, organic acids and valine are considered to have a variety of physiological functions in connection with allergies. In this research, we have developed a RP-LC/MS method to separate and quantitate six different potential endogenous biomarkers, including leukotrieneB₄ (LTB₄), prostaglandinD₂ (PGD₂), arachidonic acid (AA), histamine (HI), lactic acid (LA) and valine (VAL), from serum of rats with ovalbumin (OVA)-induced allergy and normal rats, and the discrepancies between the model group and the control group were compared. The separation was performed on a Prevail C₁₈ column (250 mm × 4.6 mm, 5 μm) with a gradient elution of acetonitrile with 0.1% formic acid (v/v) and 10 mM ammonium formate (adjusted to pH 4.0 with formic acid) at a flow rate of 0.5 mL min⁻¹ The method was validated and shown to be sensitive, accurate (recovery values 76.16–92.57%) and precise (RSD < 10% for all compounds) with a linear range over several orders of magnitude. The method was successfully applied to rat serum and shown to be indicative of the endogenous levels of biomarkers within the rat body. The analysis of the biomarkers can provide insight into the allergic mechanisms associated with related diseases.

Pharmacokinetic and bioequivalence study of two brands of valsartan tablets in healthy male volunteers

Valsartan (CAS 137862-53-4) is an antihypertensive drug belonging to the family of angiotensin II receptor antagonists acting at the AT1 receptor, which mediates all known effects of angiotensin II on the cardiovascular system. In the present study, the pharmacokinetic parameters of two oral formulations of valsartan tablets were compared in a randomized, single oral dose, two-treatment crossover design in 24 healthy male volunteers under fasting conditions. After an overnight fast, the volunteers received 80 mg valsartan. Blood samples were collected up to 48 h and drug concentrations were determined by a reverse-phase HPLC method with fluorescence detection. Various pharmacokinetic parameters were determined from the plasma concentration-time curves of both formulations. The obtained values for test and reference products were 3067.7 +/- 1,281.7 and 3,304.3 +/- 1,196.4 ng/ml for Cmax; 17,834.4 +/- 7,083.8 and 18,319.1 +/- 7,800.7 ng x h/ml for AUC0-48; 18,825.7 +/- 7,553.2 and 19,172.2 +/- 8,307.2 ng x h/ml for AUC0-infinity, respectively. The 90% confidence intervals obtained by analysis of variance were 86.84-100.87% for Cmax and 93.43-115.54% for AUC0-t, which are within the acceptance range of 80-125%. Therefore it can be concluded that both products are bioequivalent in terms of rate and extent of drug absorption and therefore interchangeable.

Development of a competitive immunoassay for the determination of N-(2-hydroxypropyl)valine adducts in human haemoglobin and its application in biological monitoring

Propylene oxide (PO) is an important industrial compound and a directly acting mutagen. Human exposure to PO can be monitored by the determination of haemoglobin adducts. An immunoassay that quantifies the N-terminal adduct N-(2-hydroxypropyl)valine in whole haemoglobin was developed and its potential usefulness as a tool for biologically monitoring occupational exposure was demonstrated. Analytical reliability was confirmed in a comparative study with GC-MS (range 3.7-992 nmol g-1 haemoglobin (Hb), correlation coefficient 0.99, n=10). The assay has been configured as a competitive enzyme-linked immunosorbent assay to facilitate the rapid throughput of samples. The assay employs a whole blood matrix and has a working range of 2-250 pmol g-1 Hb. It does not appear to be affected by structurally similar metabolites and has been used to determine adducts in human blood samples. The first results in potentially exposed workers indicate the assay's high potential usefulness in routine occupational biomonitoring of exposure to PO.

Hemoglobin adducts and mercapturic acid excretion of acrylamide and glycidamide in one study population

The aim of this study was to determine the relationship between the oxidative and reductive metabolic pathways of acrylamide (AA) in the nonsmoking general population. For the first time both the blood protein adducts and the urinary metabolites of AA and glycidamide (GA) were quantified in an especially designed study group with even distribution of age and gender. The hemoglobin adducts N-carbamoylethylvaline (AAVal) and N-( R, S)-2-hydroxy-2-carbamoylethylvaline (GAVal) were detected by GC-MS/MS in all blood samples with median levels of 30 and 34 pmol/g of globin, respectively. Concentrations ranged from 15 to 71 pmol/g of globin for AAVal and from 14 to 66 pmol/g of globin for GAVal. The ratio GAVal/AAVal was 0.4-2.7 (median = 1.1). The urinary metabolites were determined by LC-MS/MS. Of all urine samples examined 99% of N-acetyl- S-(2-carbamoylethyl)- l-cysteine (AAMA) levels and 73% of N-( R/ S)-acetyl- S-(2-carbamoyl-2-hydroxyethyl)- l-cysteine (GAMA) levels were above the LOD (1.5 microg/L). Concentrations ranged from <LOD to 229 microg/L (median = 29 microg/L) for AAMA and from <LOD to 85 microg/L (median = 7 microg/L) for GAMA. The ratio of GAMA/AAMA varied from 0.004 to 1.4 (median = 0.3). Using hemoglobin adduct levels in blood and mercapturic acid excretion in urine for calculation of daily AA intake gave practically identical values. The median daily intakes were 0.43 (0.21-1.04) microg/kg of body weight(bw)/day using Hb adducts and 0.51 (<LOD-2.32) microg/kg of bw/day using mercapturic acids for calculations. Children take up approximately 1.3-1.5 times more AA per kilogram of body weight than adults. The ratio GAMA/AAMA is significantly higher in the group of young children (6-10 years) with a median level of 0.5. A gender-related difference in internal exposure and metabolism was not observed.

MDR1 genotypes do not influence the absorption of a single oral dose of 600 mg valacyclovir in healthy Chinese Han ethnic males

AIMS

To investigate the influence of three single nucleotide polymorphisms (SNPs) in exon 12 (C1236T), exon 21 (G2677T/A) and exon 26 (C3435T) of MDR1 gene on the absorption of valacyclovir after a single oral administration in the Chinese Han ethnic population.

METHODS

Two hundred healthy Chinese subjects were genotyped for the SNPs of C1236T, G2677T/A and C3435T in the MDR1 gene using allele-specific polymerase chain reaction. Linkage disequilibrium (LD) was analysed. Twenty-four subjects derived from a large random sample (n = 200) received a single oral dose of 600 mg valacyclovir. Plasma concentrations of acyclovir were determined up to 14 h after administration to obtain a pharmacokinetic profile.

RESULTS

LD existed between G2677T/A in exon 21 and C3435T in exon 26 (P < 0.001), between C1236T in exon 12 and C3435T (P < 0.001), but not between C1236T and G2677T/A (P > 0.05). C(max), AUC(0-1.5 h) and AUC(0-infinity) were used as indices of valacyclovir absorption. AUC(0-infinity) for the 2677TA genotype was 17.45 +/- 2.40 microg x h/ml, which was much higher compared with the 2677GG, GA and TT genotypes of 10.44 +/- 1.00, 11.84 +/- 2.83, 11.34 +/- 2.32 microg x h/ml, respectively (P < 0.05). Similarly, a statistically significant difference of AUC(0-infinity) was also observed for different linked genotypes at position 2677 vs. 3435, and 1236 vs. 3435 (P < 0.05). However, there was no significant difference in valacyclovir absorptive pharmacokinetics between carriers and noncarriers of different haplotypes (P > 0.05).

CONCLUSIONS

Three SNPs of MDR1 gene did not influence the absorption of a single oral dose of 600 mg valacyclovir in healthy Chinese Han ethnic subjects.

[Metabonomic study of blood plasma in the assessment of liver graft function]

OBJECTIVE

To access the capability of 1H nuclear magnetic resonance (NMR) -based metabonomics in the evaluation of graft function in the perioperation period of liver transplantation.

METHODS

Plasma samples of 15 male primary hepatic carcinoma patients were collected for clinical biochemical analysis and 1H NMR spectroscopy 1 day before operation, 1 day and 1 week after the operation. The NMR data were analyzed using principal component analysis.

RESULTS

Metabonomic analysis indicated that, compared with those before operation, blood concentrations of valine, alanine, acetone, succinic acid, glutamine, choline, lactate, and glucose increased significantly 1 day after transplantation. One week later, the levels of lipids and choline increased notably, while those of glucose and amino acids decreased. Principal component analysis showed significant difference between metabolic profiles of plasma samples of variant periods of liver transplantation, due to the variation of the levels of glucose, lipids, lactate, and choline. A good agreement was observed between clinical chemistry and metabonomic data.

CONCLUSIONS

Metabonomic analysis can clearly identify the difference between the plasma samples of primary hepatic carcinoma patients at different time during the perioperation period of liver transplantation. It therefore may be a promising new technology in predicting the outcomes of liver transplantation.

Simultaneous determination of fixed dose combination of nebivolol and valsartan in human plasma by liquid chromatographic-tandem mass spectrometry and its application to pharmacokinetic study

A rapid, sensitive and accurate liquid chromatographic-tandem mass spectrometry method is described for the simultaneous determination of nebivolol and valsartan in human plasma. Nebivolol and valsartan were extracted from plasma using acetonitrile and separated on a C18 column. The mobile phase consisting of a mixture of acetonitrile and 0.05 mM formic acid (50:50 v/v, pH 3.5) was delivered at a flow rate of 0.25 ml/min. Atmospheric pressure ionization (API) source was operated in both positive and negative ion mode for nebivolol and valsartan, respectively. Selected reaction monitoring mode (SRM) using the transitions of m/z 406.1-->m/z 150.9; m/z 434.2-->m/z 179.0 and m/z 409.4-->m/z 228.1 were used to quantify nebivolol, valsartan and internal standard (IS), respectively. The linearity was obtained over the concentration range of 0.01-50.0 ng/ml and 1.0-2000.0 ng/ml and the lower limits of quantitation were 0.01 ng/ml and 1.0 ng/ml for nebivolol and valsartan, respectively. This method was successfully applied to the pharmacokinetic study of fixed dose combination (FDC) of nebivolol and valsartan formulation product after an oral administration to healthy human subjects.

Biovalidation of an SPE-HPLC-UV-fluorescence method for the determination of Valsartan and its metabolite valeryl-4-hydroxy-valsartan in human plasma

A simple and fast method for the simultaneous determination of the antihypertensive drug Valsartan and its metabolite in human plasma has been validated. The proposed method deals with SPE, followed by an HPLC separation coupled with fluorimetric and photometric detection. The optimization of the SPE-HPLC method was achieved by an experimental design. The separation was performed on an RP C18 Atlantis 100 mmx3.9 mm column. The mobile phase consisted of a mixture of ACN 0.025% TFA and phosphate buffer (5 mM, pH = 2.5) 0.025% TFA and was delivered in gradient mode at a flow rate of 1.30 mL/min. The eluent was monitored with a fluorescence detector at 234 and 378 nm excitation and emission wavelengths, respectively, and at 254 nm using a photometric detector. The full analytical validation was performed according to the Food and Drug Administration (FDA) 'guidance for industry: bioanalytical method validation' and the recoveries obtained for Valsartan and its metabolite ranged from 94.6 to 108.8%. The validated method was successfully applied to 12 plasma samples obtained from patients under antihypertensive treatment with Valsartan.

Development of micellar electro kinetic chromatography for the separation and quantitation of L-valine, L-leucine, L-isoleucin and L-phenylalanine in human plasma and comparison with HPLC

Phenylketonuria (PKU) and Maple Syrup Urine Disease (MSUD) are two inborn metabolic diseases which are carried by autosomal recessive genes in man. These genetic errors result in accumulation of phenylalanine (in PKU) or valine, leucine and isoluecin (in MSUD). At high concentrations, amongst other problems, these amino acids cause mental retardation. However if detected early after birth, using special diets and other forms of therapy, mental abnormalities can be prevented. As a result in many countries screening of infants for MSUD and PKU, by measuring plasma amino acids has become a routine neonatal test. Capillary Electrophoresis (CE) assays have a number of advantages over the traditional chromatography techniques (such as GC or HPLC). These include low cost, high speed of analysis and high resolution. These characteristics, make CE an ideal method for the screening of inborn errors of metabolism. We developed a CE assay based on pre-column derivatisation of amino acids with phenylisothiocyanate. This conjugate has strong absorbance at 254 nm. CE was carried out using a Spectraphoresis 1000 instrument, fitted with 40 cm of a 25 microm capillary, at 17 degrees C. A running voltage of 18KV was used to separate the amino acid mixture in an electrophoretic buffer containing 45 mM imidazole, 6 mM borate and 208 mM SDS, fixed at pH 9 with 2-N-morpholino ethane sulfonic acid. The assay was calibrated using various concentrations of amino acid standards. LOD, LOQ, recovery, inter-day and intra-day variations of the assay were determined. Also, levels of the 4 amino acids in normal and abnormal plasma were determined and compared with HPLC.

Erythrocyte glutathione peroxidase activity and plasma selenium concentration are reduced in maple syrup urine disease patients during treatment

Maple syrup urine disease (MSUD) is an inherited disorder caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex activity. In the present study we evaluated selenium levels in plasma from MSUD patients at diagnosis and under treatment and the activities of glutathione peroxidase, catalase and superoxide dismutase in erythrocytes from treated patients. We verified that MSUD patients present a significant selenium deficiency at diagnosis, which becomes more pronounced during treatment, as well as a decrease of erythrocyte glutathione peroxidase activity during treatment. In contrast, erythrocyte catalase and superoxide dismutase activities were not altered in these patients. Our present results suggest that the reduction of an important antioxidant enzyme activity may be partially involved in the pathomechanisms of this disorder and that plasma selenium levels must be corrected through dietary supplementation in MSUD patients.

A liquid chromatography/tandem mass spectrometry method for the simultaneous quantification of valsartan and hydrochlorothiazide in human plasma

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated for simultaneous quantification of valsartan and hydrochlorothiazide in human plasma. After a simple protein precipitation using acetonitrile, the analytes were separated on a Zorbax SB-Aq C18 column using acetonitrile-10mM ammonium acetate (60:40, v/v, pH 4.5) as mobile phase at a flow rate of 1.2 mL/min. Valsartan and hydrochlorothiazide were eluted at 2.08 min and 1.50 min, respectively, ionized using ESI source, and then detected by multiple reaction monitoring (MRM) mode. The precursor to product ion transitions of m/z 434.2-350.2 and m/z 295.9-268.9 were used to quantify valsartan and hydrochlorothiazide, respectively. The method was linear in the concentration range of 4-3600 ng/mL for valsartan and 1-900 ng/mL for hydrochlorothiazide. The method was successfully employed in a pharmacokinetic study after an oral administration of a dispersible tablet containing 80 mg valsartan and 12.5 mg hydrochlorothiazide to each of the 20 healthy volunteers.

An absorption study of dietary administered acrylamide in swine

Acrylamide is a food toxicant suspected to be carcinogenic to humans. It is formed in the heat processing of carbohydrate-rich food. A current issue in food safety is whether acrylamide actually represents a risk for human health. At present, available information is insufficient to reach any conclusions. Inter alias, a still unclear matter is the fraction of acrylamide ingested by food that is absorbed and metabolized. This study compared the in vivo relative absorption of acrylamide formed in cooked food with that of the pure compound dissolved in drinking water using the pig (25 Italian Large White females) as the animal model. Acrylamide intakes of about 0.8 and 8 microg kg(-1) pig body wt day(-1) equal to one and ten times, respectively, the maximum average acrylamide daily intake for humans from the diet (expressed on a body wt basis) in industrialized countries, were chosen for the study. Adducts with the N-terminal valine of haemoglobin formed by acrylamide and its epoxide metabolite glycidamide, were used as exposure markers. Analyses were carried out by gas chromatography/mass spectrometry following in-house method validation. Both for the low and the high dose regimen, the glycidamide adduct levels in swine globins were lower of the limit of quantification of the method. As concerns acrylamide adducts, it was found that the relative absorption of acrylamide from feed and water was the same and that there is a direct proportionality between the adduct concentration and acrylamide intake.

Development and validation of a method for quantitative determination of valsartan in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of valsartan in human plasma was developed and validated. A 0.5 ml aliquot was extracted using solid-phase extraction in an Empore high performance extraction disk plate, universal resin 96-well format. The estimated calibration range of the method was 2-2000 ng/ml. The method was fully validated with intra-day mean accuracy and precision of 94.8-107% and 2.19-5.40% and inter-day mean accuracy and precision of 93.5-105% and 1.87-5.67%, respectively. No significant loss of valsartan in processed samples was confirmed in processed samples for up to 24 h at 10 degrees C. Sample dilution up to 50-fold with blank human plasma provided acceptable analyses. No interference peaks or matrix effects were observed. No effect of QC sample location results was observed in a 96-well plate. This LC-MS/MS technique was found to improve quantitative determination of valsartan allowing its pharmacokinetic evaluation with clinically relevant doses.

Optimizationvia experimental design of an SPE-HPLC-UV-fluorescence method for the determination of valsartan and its metabolite in human plasma samples

A chemometric approach was applied for the optimization of the extraction and separation of the antihypertensive drug valsartan and its metabolite valeryl-4-hydroxy-valsartan from human plasma samples. Due to the high number of experimental and response variables to be studied, fractional factorial design (FFD) and central composite design (CCD) were used to optimize the HPLC-UV-fluorescence method. First, the significant variables were chosen with the help of FFD; then, a CCD was run to obtain the optimal values for the significant variables. The measured responses were the corrected areas of the two analytes and the resolution between the chromatographic peaks. Separation of valsartan, its metabolite valeryl-4-hydroxy-valsartan and candesartan M1, used as internal standard, was made using an Atlantis dC18 100 mm x 3.9 mm id, 100 angstroms, 3 microm chromatographic column. The mobile phase was run in gradient elution mode and consisted of ACN with 0.025% TFA and a 5 mM phosphate buffer with 0.025% TFA at pH 2.5. The initial percentage of ACN was 32% with a stepness of 4.5%/min to reach the 50%. A flow rate of 1.30 mL/min was applied throughout the chromatographic run, and the column temperature was kept to 40+/-0.2 degrees C. In the SPE procedure, experimental design was also used in order at achieve a maximum recovery percentage and extracts free from plasma interferences. The extraction procedure for spiked human plasma samples was carried out using C8 cartridges, phosphate buffer (pH 2, 60 mM) as conditioning agent, a washing step with methanol-phosphate buffer (40:60 v/v), a drying step of 8 min, and diethyl ether as eluent. The SPE-HPLC-UV-fluorescence method developed allowed the separation and quantitation of valsartan and its metabolite from human plasma samples with an adequate resolution and a total analysis time of 1 h.

Stimulation of Macroautophagy Can Rescue Older Cells from 8-OHdG mtDNA Accumulation: A Safe and Easy Way to Meet Goals in the SENS Agenda

Reduction of oxidative stress within mitochondria is a major focus and important part in the SENS agenda. The age-related accumulation of mitochondria rich in oxidatively altered DNA may be a biomarker of malfunctioning and increased oxidative stress. Macroautophagy is the cell repair mechanism responsible for the disposal of excess or altered mitochondria under the inhibitory control of nutrition and insulin, and may mediate the antiaging effects of caloric restriction. The authors investigated the effects of stimulation of macroautophagy by the injection of an antilipolytic agent on the age-related accumulation of oxidatively altered mitochondrial DNA (mtDNA) in rat liver cells. Results showed that treatment rescued older cells from the accumulation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the mtDNA in less than 6 hours. It is concluded that the age-related changes in mtDNA and function are likely to be the consequence of a failure of macroautophagy in the recognition and disposal of a small number of severely injured mitochondria, and that easy and safe ways are available to counteract this change.

Urinary mercapturic acids and a hemoglobin adduct for the dosimetry of acrylamide exposure in smokers and nonsmokers

Acrylamide, used in the manufacture of polyacrylamide and grouting agents, is also present in the diet and tobacco smoke. It is a neurotoxin and a probable human carcinogen. Analytical methods were established to determine the mercapturic acids of acrylamide (N-acetyl-S-(2-carbamoylethyl)-L-cysteine, AAMA) and its metabolite glycidamide (N-(R/S)-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine, GAMA) by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), as well as the N-terminal valine adduct of acrylamide (N-2-carbamoylethylvaline, AAVal) released by N-alkyl Edman degradation of hemoglobin by gas chromatography-mass spectrometry (GC-MS). Twenty-four-hour urine samples from 60 smokers and 60 nonsmokers were analyzed for AAMA and GAMA, and blood samples were analyzed for AAVal. Smokers excreted 2.5-fold higher amounts of AAMA and 1.7-fold higher amounts of GAMA in their urine and had 3-fold higher levels of AAVal in their blood. All three biomarkers of acrylamide exposure were strongly correlated with the smoking dose as determined by the daily cigarette consumption, nicotine equivalents (the molar sum of nicotine, cotinine, trans-3'-hydroxycotinine, and their respective glucuronides) in urine, salivary cotinine, and carbon monoxide in expired breath. In nonsmokers, a weak but significant correlation between AAMA and the estimated dietary intake of acrylamide was found. It is concluded that all three biomarkers of acrylamide are suitable for the determination of exposure in both smokers and nonsmokers.

Determination and validation of ketoprofen, pantoprazole and valsartan together in human plasma by high performance liquid chromatography

A rapid and specific high-performance liquid chromatographic method was developed and validated for the simultaneous determination of ketoprofen, valsartan and pantoprazole in human plasma. Chromatographic separation of ketoprofen, valsartan and pantoprazole was performed using a Chromasil C18 column (250 mm x 4.6 mm i.d., 5 microm particle size). The mobile phase consisted of a mixture of 0.02 M sodium dihydrogen phosphate buffer (pH 3.15) and acetonitrile (58:42, v/v) pumped through the chromatographic system at a flow rate of 1 mL x min(-1). The Diode Array detector was operated at 225 and 272 nm. Rofecoxib was used as an internal standard. Sample treatment procedure consisted of deproteinisation with acetonitrile-methanol (50:50 v/v). Analytical recoveries were in the range of 79.00-118.00% of nominal values of valsartan, ketoprofen and pantoprazole. The method was reproducible and accurate with lower limits of quantification 250 microg x L(-1) for pantoprazole and 500 microg x L(-1) for ketoprofen and valsartan. This method was relatively easy to perform and allows simultaneous determination of these three drugs in plasma at nanogram levels.

Whole-body valine and cysteine kinetics and tissue fractional protein synthesis rates in lambs fed Sulla (Hedysarum coronarium) and infected or not infected with adult Trichostrongylus colubriformis

Poor growth during parasitic infection may be due to a redistribution of amino acids away from skeletal muscle protein synthesis to the intestinal site of infection. The effect of a Trichostrongylus colubriformis infection on whole-body amino acid kinetics and tissue fractional protein synthesis rates were determined in lambs fed fresh Sulla (Hedysarum coronarium; 800 g DM/d). Lambs were dosed with 6000 L3 Trichostrongylus colubriformis larvae daily for 6 d (n 6) or kept as parasite-free controls (n 6). On day 45 post-infection, the lambs received an intravenous injection of 2H2O and infusions (8 h) of [35S]sulphate to measure the size of the whole-body water and sulphate pools, respectively. On day 48, the lambs were continuously infused for 8 h with [3,4-3H]valine into the jugular vein as well as with [1-13C]valine and [35S]cysteine into the abomasum. After the 8 h infusions, the lambs were killed and tissue samples collected from the duodenum, ileum, mesenteric lymph nodes, liver, spleen, thymus, muscle and skin. Feed intake (769 v. 689 (sd 47) g DM/d) was not affected by infection, whereas liveweight gains (50 v. -50 (sd 70) g/d) were lower and intestinal worm burdens (240 v. 18,000 (sd 7000) worms) higher in the infected lambs. Parasitic infection increased the fractional protein synthesis rates in the small intestine, mesenteric lymph nodes and liver but did not affect skin and skeletal muscle fractional protein synthesis rates during the established parasitic infection.

Effects of organic anion transporting polypeptide 1B1 haplotype on pharmacokinetics of pravastatin, valsartan, and temocapril

OBJECTIVE

Recent reports have shown that genetic polymorphisms in organic anion transporting polypeptide (OATP) 1B1 have an effect on the pharmacokinetics of drugs. However, the impact of OATP1B1*1b alleles, the frequency of which is high in all ethnicities, on the pharmacokinetics of substrate drugs is not known after complete separation of subjects with OATP1B1*1a and *1b. Furthermore, the correlation between the clearances of OATP1B1 substrate drugs in individuals has not been characterized. We investigated the effect of genetic polymorphism of OATP1B1, particularly the *1b allele, on the pharmacokinetics of 3 anionic drugs, pravastatin, valsartan, and temocapril, in Japanese subjects.

METHODS

Twenty-three healthy Japanese volunteers were enrolled in a 3-period crossover study. In each period, after a single oral administration of pravastatin, valsartan, or temocapril, plasma and urine were collected for up to 24 hours.

RESULTS

The area under the plasma concentration-time curve (AUC) of pravastatin in *1b/*1b carriers (47.4 +/- 19.9 ng.h/mL) was 65% of that in *1a/*1a carriers (73.2 +/- 23.5 ng.h/mL) (P = .049). Carriers of *1b/*15 (38.2 +/- 15.9 ng.h/mL) exhibited a 45% lower AUC than *1a/*15 carriers (69.2 +/- 23.4 ng.h/mL) (P = .024). In the case of valsartan we observed a similar trend as with pravastatin, although the difference was not statistically significant (9.01 +/- 3.33 microg.h/mL for *1b/*1b carriers versus 12.3 +/- 4.6 microg.h/mL for *1a/*1a carriers [P = .171] and 6.31 +/- 3.64 microg.h/mL for *1b/*15 carriers versus 9.40 +/- 4.34 microg.h/mL for *1a/*15 carriers [P = .213]). The AUC of temocapril also showed a similar trend (12.4 +/- 4.1 ng.h/mL for *1b/*1b carriers versus 18.5 +/- 7.7 ng.h/mL for *1a/*1a carriers [P = .061] and 16.4 +/- 5.0 ng.h/mL for *1b/*15 carriers versus 19.0 +/- 4.1 ng.h/mL for *1a/*15 carriers [P = .425]), whereas that of temocaprilat (active form of temocapril) was not significantly affected by the haplotype of OATP1B1. Interestingly, the AUC of valsartan and temocapril in each subject was significantly correlated with that of pravastatin (R = 0.630 and 0.602, P < .01). The renal clearance remained unchanged for each haplotype for all drugs.

CONCLUSION

The major clearance mechanism of pravastatin, valsartan, and temocapril appears to be similar, and OATP1B1*1b is one of the determinant factors governing the interindividual variability in the pharmacokinetics of pravastatin and, possibly, valsartan and temocapril.

Anabolic signaling and protein synthesis in human skeletal muscle after dynamic shortening or lengthening exercise

We hypothesized a differential activation of the anabolic signaling proteins protein kinase B (PKB) and p70 S6 kinase (p70(S6K)) and subsequent differential stimulation of human muscle protein synthesis (MPS) after dynamic shortening or lengthening exercise. Eight healthy men [25 +/- 5 yr, BMI 26 +/- 3 kg/m(-2) (means +/- SD)] were studied before and after 12 min of repeated stepping up to knee height, and down again, while carrying 25% of their body weight, i.e., shortening exercise with the "up" leg and lengthening exercise with contralateral "down" leg. Quadriceps biopsies were taken before and 3, 6, and 24 h after exercise. After exercise, over 2 h before the biopsies, the subjects ingested 500 ml of water containing 45 g of essential amino acids and 135 g of sucrose. Rates of muscle protein synthesis were determined via incorporation over time of [1-(13)C]leucine (<or=6 h after exercise) or [1-(13)C]valine (21-24 h after exercise) and phosphorylation of signaling proteins by Western analysis. PKB and p70(S6K) phosphorylation increased approximately 3-fold after 3 h and remained elevated at 6 and 24 h. After exercise, rates of myofibrillar and sarcoplasmic protein synthesis were unchanged over the period including exercise and 3 h of recovery but had increased significantly at 6 (approximately 3.0- and 2.4-fold, respectively) and 24 h (approximately 3.2- and 2.0-fold, respectively), independently of the mode of exercise. Short-term dynamic exercise in either shortening or lengthening mode increases MPS at least as much as resistance exercise and is associated with long-term activation of PKB and p70(S6K).

Rapid determination of valsartan in human plasma by protein precipitation and high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for the determination of valsartan in human plasma is reported. The assay is based on protein precipitation with methanol and reversed-phase chromatography with fluorimetric detection. The preparation of a batch of 24 samples takes 20 min. The liquid chromatography was performed on an octadecylsilica column (50 mm x 4 mm, 5 microm particles), the mobile phase consisted of acetonitrile -15 mM dihydrogenpotassium phosphate, pH 2.0 (45:55, v/v). The run time was 2.8 min. The fluorimetric detector was operated at 234/374 nm (excitation/emission wavelength). The limit of quantitation was 98 ng/ml using 0.2 ml of plasma. Within-day and between-day precision expressed by relative standard deviation was less than 5% and inaccuracy did not exceed 8%. The assay was applied to the analysis of samples from a pharmacokinetic study.

N-Methylenvaline in a group of subjects occupationally exposed to formaldehyde

Aim of this pilot study was to correlate the human exposure to formaldehyde (F) with N-methylenvaline, a molecular adduct formed by addiction of F to the N-terminal valine in hemoglobin. A group of 21 subjects employed in a plywood factory and a laminate factory, and occupationally exposed to F, together with a group of 30 controls, were recruited as volunteers to test this biomarker. Each subject received a questionnaire and a passive personal F sampler. Exposure to F vapors and occurrence of N-methylenvaline in blood were measured. Integrated F concentrations always proved lower than threshold limit value as a ceiling (TLV-TWA) (0.37 mg/m(3), 0.3 ppm). N-Methylenvaline distribution in blood, as measured by GC/MS upon derivatization, showed direct positive relationship to F exposure, with r=0.465. Prevalence of the molecular adduct expressed in nmol/g of globin was significantly higher in the exposed group (p<0.04) than in the control group. However, the N-methylenvaline marker was unable to provide significant distinction between the subjects exposed to F through tobacco smoke habit and the non smokers. Despite this interference, in this pilot study the usefulness of N-methylenvaline as a biomarker for testing occupational exposure to F was demonstrated.