S-adenosylmethionine in alcoholic liver cirrhosis: a randomized, placebo-controlled, double-blind, multicenter clinical trial

BACKGROUND/AIM

The efficacy of S-adenosylmethionine (AdoMet) in the treatment of liver cell injury has been demonstrated in several experimental models. The aim of this study was to investigate the effects of AdoMet treatment in human alcoholic liver cirrhosis.

METHODS

A randomized, double-blind trial was performed in 123 patients treated with AdoMet (1200 mg/day, orally) or placebo for 2 years. All patients had alcoholic cirrhosis, and histologic confirmation of the diagnosis was available in 84% of the cases. Seventy-five patients were in Child class A, 40 in class B, and 8 in class C. Sixty-two patients received AdoMet and 61 received placebo.

RESULTS

At inclusion into the trial no significant differences were observed between the two groups with respect to sex, age, previous episodes of major complications of cirrhosis, Child classification and liver function tests. The overall mortality/liver transplantation at the end of the trial decreased from 30% in the placebo group to 16% in the AdoMet group, although the difference was not statistically significant (p = 0.077). When patients in Child C class were excluded from the analysis, the overall mortality/liver transplantation was significantly greater in the placebo group than in the AdoMet group (29% vs. 12%, p = 0.025), and differences between the two groups in the 2-year survival curves (defined as the time to death or liver transplantation) were also statistically significant (p = 0.046).

CONCLUSIONS

The present results indicate that long-term treatment with AdoMet may improve survival or delay liver transplantation in patients with alcoholic liver cirrhosis, especially in those with less advanced liver disease.

Provitamin A accumulation in cassava (Manihot esculenta) roots driven by a single nucleotide polymorphism in a phytoene synthase gene

Cassava (Manihot esculenta) is an important staple crop, especially in the arid tropics. Because roots of commercial cassava cultivars contain a limited amount of provitamin A carotenoids, both conventional breeding and genetic modification are being applied to increase their production and accumulation to fight vitamin A deficiency disorders. We show here that an allelic polymorphism in one of the two expressed phytoene synthase (PSY) genes is capable of enhancing the flux of carbon through carotenogenesis, thus leading to the accumulation of colored provitamin A carotenoids in storage roots. A single nucleotide polymorphism present only in yellow-rooted cultivars cosegregates with colored roots in a breeding pedigree. The resulting amino acid exchange in a highly conserved region of PSY provides increased catalytic activity in vitro and is able to increase carotenoid production in recombinant yeast and Escherichia coli cells. Consequently, cassava plants overexpressing a PSY transgene produce yellow-fleshed, high-carotenoid roots. This newly characterized PSY allele provides means to improve cassava provitamin A content in cassava roots through both breeding and genetic modification.

Source of early reactive oxygen species in the apoptosis induced by transforming growth factor-beta in fetal rat hepatocytes

Transforming growth factor-beta (TGF-beta) induces an oxidative stress process in hepatocytes that mediates its apoptotic activity. To determine the cellular source of the early reactive oxygen species (ROS) generated by fetal rat hepatocytes in response to TGF-beta, we used inhibitors that block different ROS-producing systems. Diphenyleneiodonium, which inhibits NADPH oxidase and other flavoproteins, completely blocked the increase in ROS induced by TGF-beta, coincidently with an impairment of caspase-3 activation and cell death. Rotenone, an inhibitor of the NADH dehydrogenase in mitochondrial complex I, attenuated, but did not completely inhibit, ROS-production, caspase activation, and cell death mediated by TGF-beta. No significant protection was observed with inhibitors of other ROS-producing systems, such as cytochrome P450 (metyrapone), cyclooxygenase (indomethacin), and xanthine oxidase (allopurinol). Additional experiments have indicated that two different mechanisms could be involved in the early ROS production by TGF-beta. First, an inducible (cycloheximide-inhibited) NADPH oxidase-like system could account for the extramitochondrial production of ROS. Second, TGF-beta could increase ROS by a rapid downregulation of antioxidant genes. In particular, intramitochondrial ROS would increase by depletion of MnSOD. Finally, glutathione depletion is a late event and it would be more the consequence than the cause of the increase in ROS induced by TGF-beta.

Predictive factors of in-hospital CNS complications following liver transplantation

We prospectively evaluated 84 consecutive adult patients with chronic liver disease before and after liver transplantation to define the type and frequency of post-transplant neurologic complications, and to assess possible pretransplant and operative variables associated with in-hospital CNS complications. There were 25 patients (30%) who presented 23 neurologic complications of the central and six of the peripheral nervous system. Seventy-five percent of the complications occurred in the first month post-transplant. The most frequent CNS complications included anoxic (six patients) and septic (five) encephalopathy, as well as brain hemorrhage (five). Patients who presented CNS complications had a higher mortality rate than those who did not (55% versus 17%, p = 0.002). Multiple logistic regression analysis showed abnormal pretransplant neurologic examination suggestive of chronic hepatic encephalopathy (p = 0.007) and noncholestatic liver disease (p = 0.012) to be independently associated with in-hospital CNS complications. These data indicate that CNS neurologic complications following liver transplant are common in patients with noncholestatic liver disease and are associated with increased mortality. The pretransplant neurologic examination is an important predictor of CNS complications that occur in the immediate post-transplant period.

Control of carotenoid biosynthesis through a heme-based cis-trans isomerase

Plants synthesize carotenoids essential for plant development and survival. These metabolites also serve as essential nutrients for human health. The biosynthetic pathway leading to all plant carotenoids occurs in chloroplasts and other plastids and requires 15-cis-ζ-carotene isomerase (Z-ISO). It was not certain whether isomerization was achieved by Z-ISO alone or in combination with other enzymes. Here we show that Z-ISO is a bona fide enzyme and integral membrane protein. Z-ISO independently catalyzes the cis-to-trans isomerization of the 15–15′ C=C bond in 9,15,9′-cis-ζ-carotene to produce the substrate required by the following biosynthetic pathway enzyme. We discovered that isomerization depends upon a ferrous heme b cofactor that undergoes redox-regulated ligand-switching between the heme iron and alternate Z-ISO amino acid residues. Heme b-dependent isomerization of a large, hydrophobic compound in a membrane is unprecedented. As an isomerase, Z-ISO represents a new prototype for heme b proteins and potentially utilizes a novel chemical mechanism.

Effect of venovenous bypass on perioperative renal function in liver transplantation: results of a randomized, controlled trial

Although venovenous bypass (VVBP) has been suggested to protect the kidneys during liver transplantation and its systematic use has therefore been recommended, this beneficial effect of VVBP has not been clearly demonstrated. In a prospective, randomized, controlled trial, 77 patients receiving liver transplants for chronic liver disease were allocated to be supported with VVBP (group 1, 38 patients) or not (group 2, 39 patients). Both groups were similar in relation to preoperative clinical and laboratory data and operative transfusion requirements. Inulin clearance and urinary beta(2)-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) excretion (to determine glomerular filtration rate and tubular damage, respectively) were measured at different perioperative periods (anesthesia induction, hepatectomy, anhepatic phase, biliary anastomosis, and 24 hours after surgery). A significant decrease in inulin clearance and increase in tubular damage markers were observed in the anhepatic phase, which only partly improved in the subsequent phases. No significant differences were observed between groups 1 and 2 at any perioperative phase, except during the anhepatic phase, in which a more marked renal function impairment occurred in group 2 patients. However, renal function on the 7th postoperative day and the need for hemodialysis/ hemofiltration during the 1st week were similar in both groups. Among 40 variables analyzed, only low mean arterial pressure at anesthesia induction was identified as an independent predictor for early postoperative severe renal failure (inulin clearance < 10 mL/min/1.73 m(2) at the 24th postoperative hour), with no significant relationship between this complication and the use of venovenous bypass. Renal function markedly deteriorates during liver transplantation, and renal impairment persists during the early postoperative period. Because VVBP support is not associated with any clear benefit in renal function, its systematic use does not seem to be justified.

Specialized Plastids Trigger Tissue-Specific Signaling for Systemic Stress Response in Plants

Plastids comprise a complex set of organelles in plants that can undergo distinctive patterns of differentiation and redifferentiation during their lifespan. Plastids localized to the epidermis and vascular parenchyma are distinctive in size, structural features, and functions. These plastids are termed "sensory" plastids, and here we show their proteome to be distinct from chloroplasts, with specialized stress-associated features. The distinctive sensory plastid proteome in Arabidopsis (Arabidopsis thaliana) derives from spatiotemporal regulation of nuclear genes encoding plastid-targeted proteins. Perturbation caused by depletion of the sensory plastid-specific protein MutS HOMOLOG1 conditioned local, programmed changes in gene networks controlling chromatin, stress-related phytohormone, and circadian clock behavior and producing a global, systemic stress response in the plant. We posit that the sensory plastid participates in sensing environmental stress, integrating this sensory function with epigenetic and gene expression circuitry to condition heritable stress memory.

Synergistic interactions between carotene ring hydroxylases drive lutein formation in plant carotenoid biosynthesis

Plant carotenoids play essential roles in photosynthesis, photoprotection, and as precursors to apocarotenoids. The plastid-localized carotenoid biosynthetic pathway is mediated by well-defined nucleus-encoded enzymes. However, there is a major gap in understanding the nature of protein interactions and pathway complexes needed to mediate carotenogenesis. In this study, we focused on carotene ring hydroxylation, which is performed by two structurally distinct classes of enzymes, the P450 CYP97A and CYP97C hydroxylases and the nonheme diiron HYD enzymes. The CYP97A and HYD enzymes both function in the hydroxylation of β-rings in carotenes, but we show that they are not functionally interchangeable. The formation of lutein, which involves hydroxylation of both β- and ε-rings, was shown to require the coexpression of CYP97A and CYP97C enzymes. These enzymes were also demonstrated to interact in vivo and in vitro, as determined using bimolecular fluorescence complementation and a pull-down assay, respectively. We discuss the role of specific hydroxylase enzyme interactions in promoting pathway flux and preventing the formation of pathway dead ends. These findings will facilitate efforts to manipulate carotenoid content and composition for improving plant adaptation to climate change and/or for enhancing nutritionally important carotenoids in food crops.

Rapid biosensor development using plant hormone receptors as reprogrammable scaffolds

A general method to generate biosensors for user-defined molecules could provide detection tools for a wide range of biological applications. Here, we describe an approach for the rapid engineering of biosensors using PYR1 (Pyrabactin Resistance 1), a plant abscisic acid (ABA) receptor with a malleable ligand-binding pocket and a requirement for ligand-induced heterodimerization, which facilitates the construction of sense-response functions. We applied this platform to evolve 21 sensors with nanomolar to micromolar sensitivities for a range of small molecules, including structurally diverse natural and synthetic cannabinoids and several organophosphates. X-ray crystallography analysis revealed the mechanistic basis for new ligand recognition by an evolved cannabinoid receptor. We demonstrate that PYR1-derived receptors are readily ported to various ligand-responsive outputs, including enzyme-linked immunosorbent assay (ELISA)-like assays, luminescence by protein-fragment complementation and transcriptional circuits, all with picomolar to nanomolar sensitivity. PYR1 provides a scaffold for rapidly evolving new biosensors for diverse sense-response applications.

Local and remote sustained trigger point therapy for exacerbations of chronic low back pain. A randomized, double-blind, controlled, multicenter trial

STUDY DESIGN

A randomized, double-blind, controlled, multicenter trial was conducted.

OBJECTIVES

To assess the efficacy of neuroreflexotherapy in the management of low back pain.

SUMMARY AND BACKGROUND DATA

Neuroreflexotherapy consists of temporary implantation of epidermal devices in trigger points in the back and referred tender points in the ear.

METHODS

The rheumatology and rehabilitation departments of three teaching hospitals in Madrid recruited 78 patients with chronic low back pain. These patients were randomly assigned to the control group (37 patients) or to the treatment group (41 patients). Patients in the treatment group underwent one neuroreflexotherapeutic intervention. The control group received sham treatment consisting of placement of the same number of epidermal devices within a 5-cm radius of the target zones. Patients from both groups were allowed to continue drug treatment as previously prescribed. The use of medications during the trial was recorded.

RESULTS

Patients underwent clinical evaluations on three occasions: within 5 minutes before intervention, within 5 minutes after intervention, and 45 days later. The preintervention assessment was carried out by the physician from each hospital department who included the patient in the study. Each of the two follow-up assessments were carried out independently by two of three physicians who had no connection with the research team. Patients in the treatment group showed immediate lessening of pain compared with the results in patients in the control group. The pain relief was clinically relevant and statistically significant, and it persisted up to the end of the trial.

CONCLUSIONS

Neuroreflexotherapy intervention seems to be a simple and effective treatment for rapid amelioration of pain episodes in patients with chronic low back pain. At this time, the duration of pain relief beyond 45 days has not been evaluated.

Screening and quantification of pesticide residues in fruits and vegetables making use of gas chromatography-quadrupole time-of-flight mass spectrometry with atmospheric pressure chemical ionization

An atmospheric pressure chemical ionization source has been used to enhance the potential of gas chromatography coupled with quadrupole time-of-flight (QTOF) mass spectrometry (MS) for screening and quantification purposes in pesticide residue analysis. A screening method developed in our laboratory for around 130 pesticides has been applied to fruit and vegetable samples, including strawberries, oranges, apples, carrots, lettuces, courgettes, red peppers, and tomatoes. Samples were analyzed together with quality control samples (at 0.05 mg/kg) for each matrix and for matrix-matched calibration standards. The screening strategy consisted in first rapid searching and detection, and then a refined identification step using the QTOF capabilities (MS(E) and accurate mass). Identification was based on the presence of one characteristic m/z ion (Q) obtained with the low collision energy function and at least one fragment ion (q) obtained with the high collision energy function, both with mass errors of less than 5 ppm, and an ion intensity ratio (q/Q) within the tolerances permitted. Following this strategy, 15 of 130 pesticides were identified in the samples. Afterwards, the quantitation capabilities were tested by performing a quantitative validation for those pesticides detected in the samples. To this aim, five matrices were selected (orange, apple, tomato, lettuce, and carrot) and spiked at two concentrations (0.01 and 0.1 mg/kg), and quantification was done using matrix-matched calibration standards (relative responses versus triphenyl phosphate used as an internal standard). Acceptable average recoveries and relative standard deviations were obtained for many but not all pesticide-matrix combinations. These figures allowed us to perform a retrospective quantification of positives found in the screening without the need for additional analysis. Taking advantage of the accurate-mass full-spectrum data provided by QTOF MS, we searched for a higher number of compounds (up to 416 pesticides) in a second stage by performing extra data processing without any new sample injection. Several more pesticides were detected, confirmed, and/or tentatively identified when the reference standard was unavailable, illustrating in this way the potential of gas chromatography-QTOF MS to detect pesticides in addition to the ones targeted in quantitative analysis of pesticides in food matrices.

Liver transplantation in high-risk patients: hepatopulmonary syndrome and portopulmonary hypertension

Two pulmonary vascular disorders, considered mutually exclusive, may be present in candidates for orthotopic liver transplantation (OLT). On the one hand, hepatopulmonary syndrome (HPS), with a prevalence about 20% in end-stage liver disease, is characterized by pulmonary vascular dilatation and abnormal gas exchange. On the other hand, portopulmonary hypertension (POPH), a process defined by pulmonary hypertension associated with portal hypertension, is less common than HPS (4%). These entities have very distinct clinical implications; whereas HPS is clinically characterized by respiratory symptoms that evolve to severe hypoxemia, patients with POPH are commonly asymptomatic, frequently diagnosed in the setting of OLT, and the symptoms appear when there is hemodynamic compromise. The pathogenesis of both entities is a putative mechanism, the imbalance of vasoactive substances in pulmonary vessels. The role of OLT to reverse these vascular disorders is controversial, although complete resolution of HPS and, less frequently, POPH following OLT has been reported. The recognition that the presence of both HPS and POPH is an important cause of morbidity and mortality among recipients of OLT has resulted in a change in the policy to select OLT candidates. Accurate identification of patients with pulmonary vascular disorders associated with liver disease should be the first step in the management of OLT candidates. Because the determinants of the prognosis of OLT in the setting of these pulmonary vascular changes have not been well established, an accurate cardiopulmonary evaluation with careful assessment of pulmonary gas exchange (in HPS) and right ventricular function (in POPH) of potential OLT recipients is mandatory before the procedure.

Simultaneous determination of Cd(II), Cu(II) and Pb(II) in surface waters by solid phase extraction and flow injection analysis with spectrophotometric detection

A method for heavy metal monitoring using spectrophotometric detection is presented. Traces of Cu(II), Pb(II) and Cd(II) at the low microg l(-1) level can be determined simultaneously after both selective removal of metal interferences and preconcentration using 'extraction chromatographic resins'. Lewatit TP807'84, which contains di(2,4,4-trimethylpentyl)phosphinic acid as active component, was used as solid adsorbent. Two minicolumns containing this resin were used: one at pH 3.2 for the removal of interferences, such as Zn(II) and Fe(III), and the other at pH 5.5 for the selective preconcentration of the target analytes. Spectrophotometric determination used FIA methodology with sulfarsazene as chromogenic reagent and partial least-squares multivariate calibration. The method was successfully applied to the analysis of surface waters from the Llobregat river and ground water samples from wells in the Guadiamar basin. Accuracy, expressed in terms of recoveries, was in the range 80-120% and relative standard deviations were below 10%.

Testicular development, body weight changes, puberty and semen traits of growing guzerat and Nellore bulls

One hundred fifty-nine purebred Guzerat (8 to 110 months of age) and sixty Nellore bulls (8-30 months of age) were used in two trials to examine testicular development and consistency, body weight changes, puberty and semen traits. Scrotal circumference measurements and semen collections by electroejaculation were made every 28 d. At both trial locations, bulls were maintained under grazing conditions and fed commercial protein supplements (2 kg/head/day) during the dry season. Age and body weight affected (P<0.01) scrotal circumference in both breeds. Scrotal circumference increased (P<0.01) linearly with age and body weight. However, scrotal circumference tended to reach mature size more rapidly than did body weight in both Guzerat and Nellore bulls. Correlation coefficients between scrotal circumference and semen traits were positive (P<0.01) ranging from 0.49 to 0.73 in the two breeds, but were not significant for testicular consistency in either breed. Scrotal circumference and age at puberty of Guzerat and Nellore bulls averaged 25.6 +/- 2.2 cm at 18.0 +/- 2.0 mo and 23.6 +/- 0.2 cm at 18.5 +/- 2.7 mo, respectively. Nellore bulls were 42 kg lighter than Guzerat at puberty. Testicular consistency was not affected by either age of body weight (P>0.10) in these young bulls. The percentages of abnormal spermatozoa were higher (P<0.01) at 13 to 15 mo of age in Guzerat (11.1%) and Nellore (14.4%) bulls than at 22 to 24 mo (6.7 and 8.0%, respectively). These data indicate that scrotal circumference measurements can be a useful tool for selecting and improving semen traits of young Guzerat and Nellore bulls under tropical grazing conditions.

Is clinical expressiveness of Paget's disease of bone decreasing?

Recent data have suggested secular changes implying a current trend toward decreased clinical severity of Paget's disease of bone (PD). To test this hypothesis, we conducted a study comparing the characteristics of two groups of PD patients, as disclosed from a sample assessed systematically. The investigation was a hospital-based study of all cases followed up at our unit since 1980. Throughout the follow-up period, diagnosis was based on standard X-ray criteria and the same clinical assessment was applied. Group I (n = 124) represented patients born before 1926, whereas group II (n = 109) included those born after that year. A bone scan performed with 99mTc-EHDP was available for all patients. X-rays of the pelvis and spine, and views of any hot spot observed on the scintigraphy scans were reviewed. The skeletal extent of PD, based on bone scan uptake, was determined by using the index proposed by Coutris. Alkaline phosphatase and hydroxyproline excretion levels were determined in blood and urine, respectively. Baseline characteristics were recorded on a purpose-designed computerized database. The proportion of males (47% in group I vs. 65% in group II; p = 0.007) and the mean (+/-SD) age at diagnosis (69.0 +/- 8.15 vs. 54.3 +/-9.14; p < 0.001) differed significantly between groups. The year of birth showed a strong negative correlation with age at diagnosis (r = -0.83, p < 0.0001) and a weak, but significant, negative correlation with extent of bone lesion (r = -0.20; p = 0.002). Likewise, subjects born prior to 1926 showed a greater percentage of affected skeleton cases (9.6 plus minus 8.01 vs. 7.06 +/- 5.79; p = 0.001). Group I individuals who had pelvic and/or femoral bone lesions were more prone to suffer "pagetic coxopathy" (65% vs. 40%; p = 0.003) with "protrusio acetabuli" (32% vs. 17%; p = 0.01), and the percentage of patients showing radiographic Monckeberg-type vascular calcifications (36% vs. 14%; p = 0.0006) was higher than in those born after 1926. No other epidemiologically clinically, or biochemically relevant differences were seen in the crude analysis. Multivariate analysis identified extent of skeletal lesions (OR = 0.76; p = 0.01), age at diagnosis (OR = 0.79; p = 0.008), number of bones involved (OR = 1.53; p = 0.03), and occupation (p < 0.0001) as the predictive variables linked to year of birth. Our data are consistent with a temporal tendency toward a smaller number of bone lesions and a decreased percentage of instances of affected skeleton. An earlier age at recent diagnosis times and absence of any relevant clinical or biochemical differences seems more likely linked to recent changes in referral and sociological patterns.

Liver Transplant From Unexpected Donation After Circulatory Determination of Death Donors: A Challenge in Perioperative Management

Unexpected donation after circulatory determination of death (uDCD) liver transplantation is a complex procedure, in particular when it comes to perioperative recipient management. However, very little has been published to date regarding intraoperative and immediate postoperative care in this setting. Herein, we compare perioperative events in uDCD liver recipients with those of a matched group of donation after brain death liver recipients. We demonstrate that the former group of recipients suffers significantly greater hemodynamic instability and derangements in coagulation following graft reperfusion. Based on our experience, we recommend a proactive recipient management strategy in uDCD liver transplantation that involves early use of vasopressor support; maintaining adequate intraoperative levels of red cells, platelets, and fibrinogen; and routinely administering tranexamic acid before graft reperfusion.

Resistance to TGF-beta-induced apoptosis in regenerating hepatocytes

Treatment with transforming growth factor beta (TGF-beta) of hepatocytes from two different proliferative conditions, such as fetal development and adult liver regeneration, shows that regenerating cells respond to this cytokine in terms of growth inhibition, but are less sensitive than the fetal ones to the apoptosis induced by this factor. Regenerating TGF-beta treated cells show higher cell viability and lower percentage of apoptotic cells than the fetal treated ones. Furthermore, TGF-beta treated regenerating hepatocytes maintain a well-preserved parenchyma-like organization. Treatment with TGF-beta induces the loss of mitochondrial transmembrane potential in fetal but not in regenerating hepatocytes and activation of caspase-3 is lower in regenerating than in fetal cells. Regenerating hepatocytes show higher intracellular levels of some antiapoptotic proteins, such as Bcl-x(L) and c-IAP-1 and, interestingly, they present higher intracellular glutathione levels, which might provide of mechanisms to avoid potential dangerous effects of the oxidative stress-mediated apoptosis induced by TGF-beta. In fact, treatment with BSO (a glutathione synthesis inhibitor) restores the response of regenerating hepatocytes to TGF-beta in terms of cell death. In conclusion, increased levels of Bcl-x(L) and cIAP-1 and higher intracellular glutathione levels could confer resistance to the apoptosis induced by TGF-beta during liver regeneration.

User-defined single pot mutagenesis using unamplified oligo pools

User-defined mutagenic libraries are fundamental for applied protein engineering workflows. Here we show that unamplified oligo pools can be used to prepare site saturation mutagenesis libraries from plasmid DNA with near-complete coverage of desired mutations and few off-target mutations. We find that oligo pools yield higher quality libraries when compared to individually synthesized degenerate oligos. We also show that multiple libraries can be multiplexed into a single oligo pool, making preparation of multiple libraries less expensive and more convenient. We provide software for automatic oligo pool design that can generate mutagenic oligos for saturating or focused libraries.

A robust GC-MS/MS method for the determination of chlorothalonil in fruits and vegetables

Chlorothalonil is a non-systemic fungicide that is easily degraded in contact with plants and soil or even by the effect of light and pH. A method for the determination of chlorothalonil in courgettes, strawberries, oranges, leeks and tomato by solvent extraction followed by GC-MS/MS with a triple quadrupole analyser was developed. The causes of chlorothalonil degradation during sample treatment were studied and minimised. The final method was based on extraction with acetone in the presence of 0.1 M EDTA sodium salt solution, and clean-up by SPE using OASIS HLB cartridges. Isotope-labelled hexachlorobenzene (HCB-(13)C(6)) was added as an internal standard to the SPE extracts before analysis by GC-MS/MS (EI) (QqQ) analysis in order to correct for instrumental deviations. Quantification was performed by matrix-matched standard calibration using relative responses to the internal standard. Two MS/MS transitions were used for mass spectrometric determination of chlorothalonil to ensure reliable quantification and confirmation. The method was validated using blank samples (for all matrices) spiked at two levels. Recoveries between 77% and 110% and an RSD below 20% were obtained for 0.1 and 0.01 mg kg(-1) spiking levels (n = 5). The validated method was applied to treated and untreated samples collected from an experimental field where a chlorothalonil formulated was applied.