Quantitation of Neuroblastoma Markers Homovanillic Acid (HVA) and Vanillylmandelic Acid (VMA) in Urine by Gas Chromatography-Mass Spectrometry (GC/MS)

Neuroblastoma and other neural crest tumors can be characterized by the increased production and excretion of catecholamines and their metabolites. Homovanillic acid (HVA) and vanillylmandelic acid (VMA) are important catecholamine metabolites that can be measured to provide relatively rapid laboratory diagnosis and clinical follow-up of neuroblastoma. We present a procedure to quantify HVA and VMA in urine samples which have been diluted to a creatinine concentration of 2 mg/dL. Diluted samples are spiked with deuterated internal standards, acidified, and extracted with an organic solvent. A bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) and pyridine mixture is added to the dried extract to create trimethylsilyl derivatives of HVA and VMA. The derivatized compounds are measured using gas chromatography-mass spectrometry (GC/MS).

A Simple, Fast, and Reliable LC-MS/MS Method for the Measurement of Homovanillic Acid and Vanillylmandelic Acid in Urine Specimens

Homovanillic acid (HVA) and vanillylmandelic acid (VMA) are catecholamine metabolites used in the diagnostic workup of neuroendocrine tumors. Here we describe a simple dilute-and-shoot method for simultaneously quantitating HVA and VMA in human urine specimens. The method employs analyte separation on a reverse-phase liquid chromatography column followed by detection using electrospray ionization triple quadrupole mass spectrometry (ESI-MS/MS), wherein qualifier and quantifier ion transitions are monitored. This is a simple and fast analytical method with an injection-to-injection time of 4 min.

Application of catecholamine metabolites as endogenous population biomarkers for wastewater-based epidemiology

Wastewater-based epidemiology studies use catchment populations to normalise chemical marker mass loads in 24-h composite wastewater samples. However, one of the biggest uncertainties within the field is the accuracy of the population used. A population marker in wastewater may significantly reduce the uncertainty. This study evaluated the catecholamine metabolites - homovanillic acid (HVA) and vanillylmandelic acid (VMA) - as potential population biomarkers. Influent wastewater 24-h composite samples were collected from 38 wastewater catchments from around Australia (representing ~33% of Australia's population), extracted and analysed by liquid chromatography tandem mass spectrometry. Measured mass loads were compared to population sizes determined by mapping catchment maps against high-resolution census data. Both biomarkers correlated with coefficient of determinations (r²) of 0.908 and 0.922 for HVA and VMA, respectively. From the regression analysis, a slope (i.e. the daily per-capita excretion) of 1.241 and 1.067 mg.day^-1.person^-1 was obtained for HVA and VMA, respectively. The mass load ratio between VMA:HVA were very similar to that reported in literature for urinary analysis among all catchments. Overall, this study provided further evidence that catecholamine metabolites are suitable candidates as population biomarkers for future studies.

Urinary vanillylmandelic acid:creatinine ratio in dogs with pheochromocytoma

Pheochromocytoma diagnosis in dogs is challenging because biochemical tests are not always available. In humans, urinary vanillylmandelic acid (VMA) is part of a pheochromocytoma biochemical diagnostic profile, whereas its diagnostic accuracy is currently unknown in dogs with pheochromocytoma. Prospectively, VMA was determined by HPLC and expressed as the ratio with respect to urinary creatinine (VMA:C). The diagnostic accuracy of the VMA:C ratio was evaluated by analyzing the receiver operating characteristic (ROC) curve in 10 healthy dogs, 8 dogs with pituitary-dependent hypercortisolism, 8 dogs with adrenal-dependent hypercortisolism, and 7 dogs with pheochromocytoma. The pheochromocytoma diagnosis was confirmed by histology and immunohistochemistry in all tumors. The VMA:C ratio was significantly higher in dogs with pheochromocytoma (158 [53.4 to 230.8] × 10^-3) than in dogs with adrenal-dependent hypercortisolism (48.1 [24.3 to 144.9] × 10^-3; P < 0.05), dogs with pituitary-dependent hypercortisolism (37.5 [32 to 47.1] × 10^-3; P < 0.001), and healthy dogs (33.8 [13.3 to 87.9] × 10^-3; P < 0.001). When using a VMA:C ratio >58.2 × 10^-3 for pheochromocytoma diagnosis, a sensitivity of 85.7% and a specificity of 88.4% were obtained. Nevertheless, when using a cut-off ratio of 4 times the median VMA:C ratio determined in healthy dogs, there was no overlap (100% specificity). The area under the ROC curve indicated that the VMA:C ratio test could be used to discriminate between dogs with and without pheochromocytoma, what leads to the conclusion that it is useful for pheochromocytoma diagnosis in dogs.

Stabilization of urinary biogenic amines measured in clinical chemistry laboratories

Urinary 5-hydroxyindoleacetic acid (5-HIAA), vanillylmandelic (VMA), homovanillic acid (HVA), catecholamines and metanephrines are produced in excess by catecholamine-producing tumors. These biogenic amines are unstable at low or high pH and require hydrochloric acid (HCl) to prevent their degradation. However, HCl addition may result in very low pH causing degradation or deconjugation of several metabolites. This study evaluated the buffering properties of sodium citrate to stabilize all biogenic amines. The metabolite concentrations were measured by LC-MS/MS or by a coulometric assay in 22 urine samples collected native and with HCl or sodium citrate. We studied the effect of pH, time (48 h, four weeks) and storage temperature at 22 °C, 4 °C, and -20 °C. We found that catecholamines degradation was prevented by HCl and citrate and that 5-HIAA was degraded in 5 out of 22 samples collected with HCl. All biogenic amines were efficiently stabilized by citrate for four weeks at 22 °C, except epinephrine (48 h at 4 °C, or four weeks at -20 °C). Sodium citrate did not cause quantification or analytical artefacts concerns. In conclusion, sodium citrate is a non-hazardous alternative to HCl for patients to send unfrozen urine samples to the laboratory which may safely store the sample for four weeks.

Vanillylmandelic acid protects against reperfusion injury in an experimental animal model of myocardial infarction

Vanillylmandelic acid, a catecholamine end-metabolite, has been shown to have several biological properties in previous studies, despite considered biologically inactive. We examined the potential effects of vanillylmandelic acid on the ischemic heart following myocardial infarction and reperfusion on a rat model. Thirty-four female Wistar rats were randomized into two groups, control and experimental. They were anesthetized and subjected to myocardial infarction through left anterior descending artery ligation. A previously studied dose of vanillylmandelic acid (10 mg/kg) was administered and the following parameters were studied during ischemia and reperfusion: a) mortality b) severity of ventricular tachyarrhythmias c) premature ventricular contractions and d) heart rate. Administration of vanillymandelic acid significantly reduced the severity of ventricular tachyarrhythmias and mortality rate during reperfusion, while it did not affect any other of the parameters studied. In conclusion, reperfusion injury was blunted through vanillylmandelic acid administration, which seems to be mediated by parasympathetic activation.

Polychlorinated biphenyls and depression: cross-sectional and longitudinal investigation of a dopamine-related Neurochemical path in the German HELPcB surveillance program

BACKGROUND

Exposure to polychlorinated biphenyls (PCBs) is associated with depressive symptomatology. A cause of depressive symptoms is a disturbance in the neurotransmitter system of dopamine (DA). Animal as well as human studies report that PCBs can influence the DA system. This study examined whether PCB-related depressive symptoms are affected by DA metabolites in humans with high PCB body burden.

METHODS

This study is part of the German HELPcB surveillance program (Health Effects in high Level exposure to PCB) for occupationally exposed workers and their relatives. Data was collected from 178 participants on two measurement time points (t1 and t2) with a one-year time lag in between the two time points. PCBs were analyzed in plasma via human biomonitoring and a validated questionnaire was used to identify existence and severity of depressive symptoms. As a surrogate for DA, we measured its metabolites homovanillic acid (HVA) and vanillylmandelic acid (VMA) in urine. Mediation analyses were performed to test whether the association between PCB exposure and severity of depressive symptoms is mediated by urinary concentration of DA metabolites HVA and VMA. The mediation was tested with the SPSS macro MEDIATE.

RESULTS

We found a significant mediation over time for lower-chlorinated, higher-chlorinated and dioxin-like PCBs. The positive association between PCB exposure with severity of depressive symptoms was mediated by the main DA metabolite HVA. At t1 a higher exposure with PCBs was associated with lower concentration in urinary HVA. A reduced HVA concentration at t1 was correlated with increased depressive symptoms severity at t2. No meditations were found for VMA.

CONCLUSIONS

This work indicates that the association of PCB exposure and an increase of depressive symptoms after one year is mediated by the DA metabolite HVA as a surrogate for DA. These are first steps towards finding an explanation for an underlying neurochemical pathomechanism of PCB-related depressive symptomatology.

Polychlorinated biphenyls and depression: cross-sectional and longitudinal investigation of a dopamine-related Neurochemical path in the German HELPcB surveillance program

BACKGROUND

Exposure to polychlorinated biphenyls (PCBs) is associated with depressive symptomatology. A cause of depressive symptoms is a disturbance in the neurotransmitter system of dopamine (DA). Animal as well as human studies report that PCBs can influence the DA system. This study examined whether PCB-related depressive symptoms are affected by DA metabolites in humans with high PCB body burden.

METHODS

This study is part of the German HELPcB surveillance program (Health Effects in high Level exposure to PCB) for occupationally exposed workers and their relatives. Data was collected from 178 participants on two measurement time points (t1 and t2) with a one-year time lag in between the two time points. PCBs were analyzed in plasma via human biomonitoring and a validated questionnaire was used to identify existence and severity of depressive symptoms. As a surrogate for DA, we measured its metabolites homovanillic acid (HVA) and vanillylmandelic acid (VMA) in urine. Mediation analyses were performed to test whether the association between PCB exposure and severity of depressive symptoms is mediated by urinary concentration of DA metabolites HVA and VMA. The mediation was tested with the SPSS macro MEDIATE.

RESULTS

We found a significant mediation over time for lower-chlorinated, higher-chlorinated and dioxin-like PCBs. The positive association between PCB exposure with severity of depressive symptoms was mediated by the main DA metabolite HVA. At t1 a higher exposure with PCBs was associated with lower concentration in urinary HVA. A reduced HVA concentration at t1 was correlated with increased depressive symptoms severity at t2. No meditations were found for VMA.

CONCLUSIONS

This work indicates that the association of PCB exposure and an increase of depressive symptoms after one year is mediated by the DA metabolite HVA as a surrogate for DA. These are first steps towards finding an explanation for an underlying neurochemical pathomechanism of PCB-related depressive symptomatology.

Simple dilute-and-shoot method for urinary vanillylmandelic acid and homovanillic acid by liquid chromatography tandem mass spectrometry

BACKGROUND

Neuroblastomas are pediatric tumors characterized by overproduction of catecholamines. The catecholamine metabolites, vanillylmandelic acid (VMA) and homovanillic acid (HVA), are used in clinical evaluation of neuroblastoma. Tandem mass spectrometry (LC-MS/MS) is an effective analytical method for measurement of VMA and HVA in urine.

METHODS

Dilute-and-shoot sample preparation was performed in a 96-well format using a liquid handler. Chromatographic separation was achieved using a reverse phase column; detection was accomplished by triple quadrupole mass spectrometry with electrospray ionization in positive mode. Data were acquired by multiple reaction monitoring. Two transitions, quantifier and qualifier, were monitored for each analyte and its stable isotope-labeled internal standard. Analytical specificity studies were performed.

RESULTS

Injection-to-injection time was 4min. The method was validated for linearity, limit of quantification, imprecision, accuracy, and interference. Linearity was 0.5-100mg/l for both analytes. Within-run, between-day, and total imprecision were 1.0-4.1% for VMA and 0.8-3.8% for HVA. The method correlated well with our established HPLC method. Interferences precluding quantitation of VMA in 3% of specimens were reduced significantly (to 0.1% of specimens) using a modified LC gradient to reanalyze affected samples.

CONCLUSIONS

A simple, robust, economical, fast LC-MS/MS method was developed and validated for measurement of urinary VMA and HVA.

Anesthetic Management of Clinically Silent Familial Pheochromocytoma with MEN 2A: A Report of Four Cases

Familial pheochromocytomas are commonly associated with multiple endocrine neoplasia type 2 (MEN 2) syndrome. Majority of the patients present with normal clinical and biochemical parameters in the preoperative period, the incidence of hypertension being only 50 %. Even though patients may be clinically asymptomatic, surveillance and proper preoperative evaluation is important, as surgery for associated tumors may precipitate a hypertensive crisis and result in severe complications. A family of 19 members, of which 12 were positive for MEN 2A syndrome, presented to our hospital. Seven of the 12 patients had pheochromocytoma and medullary thyroid carcinoma (MTC), while the other 5 had only raised plasma calcitonin levels. Two of the 7 patients presented with bilateral pheochromocytoma and underwent an open adrenalectomy. The other 5 patients had a left-sided adrenal tumor and underwent left laparoscopic adrenalectomy under combined general and epidural anesthesia. We present our experience with four of these five cases. We here state that how paucity of literature on perioperative preparation of clinically and biochemically silent pheochromocytomas led to serious intraoperative complications in one of four cases.

Preanalytical validation and reference values for a mass spectrometric assay of serum vanillylmandelic acid for screening of catecholamine secreting neuroendocrine tumors

BACKGROUND

Urinary vanillylmandelic acid (VMA) is used to diagnose and monitor catecholamine secreting neuroendocrine tumors (NETs). We developed and validated a new liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for determination of serum VMA.

METHODS

We used serum samples from healthy volunteers (n=314) and patients suspected for NET (n=36). Deuterated VMA as an internal standard was added to samples before solid phase extraction (SPE) and LC-MS/MS analysis. We studied the effects of sample storage, sampling device and a meal on serum VMA and metanephrine concentrations. Diurnal variation and age-dependent reference intervals were established. The diagnostic performance was compared with a urinary HPLC assay for VMA and metanephrines and a serum metanephrine LC-MS/MS assay.

RESULTS

Serum VMA is stable at least for one day at +4°C, seven days at room temperature and 98 days at -20°C. Type of sampling device was not critical, but elevated serum VMA occurs after a meal (p = 0.031). Serum VMA increased with age. Therefore, we suggest clinical cut-off values of 62 nmol/L, 80 nmol/L and 108 nmol/L for age groups 18-50 yrs, 51-70 yrs and > 70 yrs, respectively. Comparison between a urinary VMA HPLC assay and serum VMA LC-MS/MS assay showed good correlation.

CONCLUSIONS

Our LC-MS/MS assay is fast and sensitive and suits well for use in a clinical laboratory. Compared to 24-h urine collection our serum assay enables well controlled sampling and convenient preanalytical steps.

The effects of seeds with hot and cold temperaments on serum thyroid hormones, corticosterone and urine vanillylmandelic acid concentrations of healthy rats

ETHNOPHARMACOLOGICAL RELEVANCE

Hot and cold temperaments are the basic concepts of Iranian traditional medicine (ITM). Nevertheless, studies on the functional mechanisms of medicinal herbs based on hot and cold temperaments are not very extensive. This study aimed to evaluate the effects of diets containing hot or cold temperament seeds according to ITM on some hormonal and neuromediator parameters with a regulatory role in thermogenesis and energy metabolism in acute (24 hr) and subacute (7-day) experiments that were performed on rats.

MATERIALS AND METHODS

Each experiment was performed on 42 male Wistar rats, which were randomly divided into 7 groups. while 1 group received usual diet (controls), 6 other groups were fed with a diet containing 10% seeds, namely, anise, fennel, or ajowan (hot temperament groups) or cucumber, pumpkin, or watermelon (cold temperament groups), respectively. The levels of the rats׳ serum free thyroxin (FT4), free triiodothyronin (FT3), triiodothyronin (T3), thyroxin (T4), corticosterone and urine vanillylmandelic acid (VMA) were analyzed.

RESULTS

After 24 hours, a significant decrease in FT3 was observed in groups that were fed anise or fennel seeds. However, a significant increase in T3 was observed in the ajowan seed-fed group, and no changes in other parameters were observed in this group. On the 7th day, FT4 was significantly increased in fennel seed-fed group; T3 was significantly increased in the anise, fennel, ajowan and watermelon seed-fed groups; corticosterone was significantly increased in the watermelon and pumpkin seed-fed groups; and VMA was significantly increased in the fennel seed-fed group and significantly decreased in the cucumber seed-fed group.

CONCLUSION

Alterations induced by hot and cold temperament seeds in measured hormonal and neuromediator levels that have a regulatory role in thermogenesis and the body׳s energy metabolism revealed that hot and cold temperament characteristics of studied seeds may most likely be related to their intervention in the body׳s energy metabolism, in that hot temperament seeds may increase energy metabolism and cold temperament ones may decrease it.

Physiological, physical and behavioural changes in dogs (Canis familiaris) when kennelled: testing the validity of stress parameters

Domestic dogs (Canis familiaris) housed in kennelling establishments are considered at risk of suffering poor welfare. Previous research supporting this hypothesis has typically used cortisol:creatinine ratios (C/Cr) to measure acute and chronic stress in kennelled dogs. However, the value of C/Cr as a welfare indicator has been questioned. This study aimed to test the validity of a range of physiological, physical and behavioural welfare indicators and to establish baseline values reflecting good dog welfare. Measurements were taken from 29 privately-owned dogs (14 males, 15 females), ranging in age and breed, in their own home and in a boarding kennel environment, following a within-subjects, counterbalanced design. Pairwise comparisons revealed that C/Cr and vanillylmandelic acid:creatinine ratios (VMA/Cr) were higher in the kennel than home environment (P=0.003; P=0.01, respectively) and were not associated with differences in movement/exercise between environments. Dogs' surface temperature was lower in kennels (P=0.001) and was not associated with ambient temperature. No association with age, or effects of kennel establishment, kennelling experience, sex or source were found. Dogs were generally more active in kennels, but showed considerable individual variability. C/Cr and 5-HIAA:creatinine ratios (5-HIAA/Cr) were negatively correlated with lip licking in kennels. Baseline values for each parameter are presented. The emotional valence of responses was ambiguous and no definitive evidence was found to suggest that dogs were negatively stressed by kennelling. It was concluded that C/Cr and, particularly, VMA/Cr and surface temperature provide robust indicators of psychological arousal in dogs, while spontaneous behaviour might be better used to facilitate interpretation of physiological and physical data on an individual level.

Urinary homovanillic and vanillylmandelic acid in the diagnosis of neuroblastoma: report from the Italian Cooperative Group for Neuroblastoma

BACKGROUND

Urinary homovanillic and vanillylmandelic acid (HVA and VMA) are well known biomarkers for the management of neuroblastoma (NB). Very few and contradictory publications on their diagnostic performance are present in the literature. The aim of this study is to review the results of HVA/Cr and VMA/Cr obtained by the reference laboratory of the Italian Cooperative Group for NB within a 7-year period using HPLC-EC.

PROCEDURE

Updated reference intervals based on age as a continuous variable were calculated by using a multivariate statistical analysis. The diagnostic performance of the two biomarkers has been established by calculating their specificity and sensitivity and by receiver operating characteristics (ROC) curves for different ages and stages of disease.

RESULTS

Accurate age-related reference intervals were obtained from 648 HVA/Cr and 671 VMA/Cr results derived from patients in which the diagnosis of neuroendocrine tumors was excluded. Sensitivity, specificity and ROC curves were obtained from 169 HVA/Cr and 179 VMA/Cr results from confirmed NB patients. The best diagnostic performance was obtained in stage 4S tumors and in children <18months.

CONCLUSIONS

This is the first report, to our knowledge, that analyzes in depth the diagnostic performance of HVA/Cr and VMA/Cr for NB in different stages and age subgroups. In addition, the present work provides cut-off points able to discriminate between NB patients and negative subjects suspected to have NB and could be of help in taking medical decisions.

Ascending monoaminergic systems alterations in Alzheimer's disease. translating basic science into clinical care

Extensive neuropathological studies have established a compelling link between abnormalities in structure and function of subcortical monoaminergic (MA-ergic) systems and the pathophysiology of Alzheimer's disease (AD). The main cell populations of these systems including the locus coeruleus, the raphe nuclei, and the tuberomamillary nucleus undergo significant degeneration in AD, thereby depriving the hippocampal and cortical neurons from their critical modulatory influence. These studies have been complemented by genome wide association studies linking polymorphisms in key genes involved in the MA-ergic systems and particular behavioral abnormalities in AD. Importantly, several recent studies have shown that improvement of the MA-ergic systems can both restore cognitive function and reduce AD-related pathology in animal models of neurodegeneration. This review aims to explore the link between abnormalities in the MA-ergic systems and AD symptomatology as well as the therapeutic strategies targeting these systems. Furthermore, we will examine possible mechanisms behind basic vulnerability of MA-ergic neurons in AD.