Nuclear Factor Erythroid 2-Related Factor 2 in Vitiligo. / Factor nuclear eritroide similar al factor 2 en el vitíligo.

Vitiligo is a pigmentary disorder, in which oxidative stress has been evidenced as part of the pathogenesis. Pathways responsible for protecting melanocytes from damage caused by reactive oxygen species are known as the nuclear factor erythroid factor 2 (Nrf2) pathway. Nrf2 is a transcription factor that remains inhibited when the organism is in homeostasis, but in the presence of oxidative stress it allows the encoding of phase ii antioxidant enzymes. In vitiligo there are abnormalities in the location and function of Nrf2 as well as polymorphisms that increase the risk of this disease. Currently, multiple molecules that act on Nrf2 have been investigated in order to find useful emerging treatments for vitiligo. A search for articles in Spanish and English was carried out in the PubMed, Ovid, Scopus and Web of Science Clarivate databases, using the keywords "Vitiligo AND nuclear factor erythroid derived 2 like 2 OR NRF2" without time restriction. All in vitro studies, narrative reviews, case series, cohort studies, and randomized and non-randomized clinical trials that specifically addressed the issue of Nrf2 associated with vitiligo were included.

Enlightening the advancements in electrochemical bioanalysis for the diagnosis of Alzheimer's disease and other neurodegenerative disorders.

Neurodegenerative disorders (NDD), and particularly Alzheimer's disease (AD), are one of the greatest challenges facing our current medicine and society because of its increasing incidence and the high burden imposed both on patients' families and health systems. Despite this, their accurate diagnosis, mostly conducted by cerebrospinal fluid (CSF) analysis or neuroimaging techniques, costly, time-consuming, and unaffordable for most of the population, remains a complex task. In this situation, electrochemical biosensors are flourishing as promising alternative tools for the simple, fast, and low-cost diagnosis of NDD/AD. This review article provides the relevant clinical details of NDD/AD along with the closely related genetic (genetic mutations, polymorphisms of ApoE and specific miRNAs) and proteomic (amyloid-ß peptides, total and phosphorylated tau protein) biomarkers circulating mostly in CSF. In addition, the article systematically enlightens a general view of the electrochemical affinity biosensors (mostly aptasensors and immunosensors) reported in the past two years for the determination of such biomarkers. The different developed strategies, analytical performances and applications are comprehensively discussed. Recent advancements in signal amplification methodologies involving smart designs and the use of nanomaterials and rational surface chemistries, as well as the challenges that must be struggled and the prospects in electrochemical affinity biosensing to bring more accessibility to NDD/AD diagnosis, prognosis, and follow-up, are also pointed out.

Electrochemical biosensing to move forward in cancer epigenetics and metastasis: A review.

Early detection and effective treatment are crucial to reduce the physical, emotional, and financial pressure exerted by growing cancer burden on individuals, families, communities, and health systems. Currently, it is clear that the accurate analysis of emerging cancer epigenetic and metastatic-related biomarkers at different molecular levels is envisaged as an exceptional solution for early and reliable diagnosis and the improvement of therapy efficiency through personalized treatments. Within this field, electrochemical biosensing has demonstrated to be competitive over other emerging and currently used methodologies for the determination of these biomarkers accomplishing the premises of user-friendly, multiplexing ability, simplicity, reduced costs and decentralized analysis, demanded by clinical oncology, thus priming electrochemical biosensors to spark a diagnostic revolution for cancer prediction and eradication. This review article critically discusses the main characteristics, opportunities and versatility exhibited by electrochemical biosensing, through highlighting representative examples published during the last two years, for the reliable determination of these emerging biomarkers, with great diagnostic, predictive and prognostic potential. Special attention is paid on electrochemical affinity biosensors developed for the single or multiplexed determination of methylation events, non-coding RNAs, ctDNA features and metastasis-related protein biomarkers both in liquid and solid biopsies of cancer patients. The main challenges to which further work must be addressed and the impact of these advances should have in the clinical acceptance of these emerging biomarkers are also discussed which decisively will contribute to understand the molecular basis involved in the epigenetics and metastasis of cancer and to apply more efficient personalized therapies.

Impact of Vitiligo on Quality of Life. / Impacto del vitíligo en la calidad de vida.

INTRODUCTION AND OBJECTIVE: Vitiligo is a chronic autoimmune skin disease caused by the destruction of melanocytes. Although quality of life (QOL) in vitiligo has been studied in different countries, it has not yet been investigated in Mexico. The aim of this study was to assess the QOL of Mexican patients with vitiligo. MATERIAL AND METHOD: We conducted a cross-sectional study at the research unit of Centro Dermatológico Dr. Ladislao de la Pascua in Mexico City. We included adults with vitiligo and excluded those with other pigmentation disorders or a neurological or psychiatric disorder. Patients on psychoactive medications were also excluded. All the patients were administered the Dermatology Life Quality Index (DLQI), a vitiligo-specific quality of life instrument (the VitiQoL), and the Beck Depression and Anxiety Inventories. RESULTS: We studied 150 patients with vitiligo (103 women [68.7%] and 47 men [31.3%]). The median (interquartile range) age was 38 (20) years. The mean (SD) scores on the DLQI and VitiQoL were 5.2 (5.4) and 32.1 (22.7) out of total possible scores of 30 and 90, respectively. The correlation between questionnaire scores was 0.675 (P<.001). Patients with genital involvement scored significantly worse on the VitiQoL than those without lesions in this area (43.95 [28.4]) vs. 28.98 [20.08], P<.001). The prevalence of depression and anxiety was 34% and 60%, respectively. CONCLUSION: Vitiligo has a minimal impact on the QOL of our patients. QOL was worse in patients with genital lesions.

[Effectiveness of an intervention to improve safety culture. Less is more?] / Efectividad de una intervención para mejorar la cultura de seguridad. ¿Menos es más?

OBJECTIVE: To assess the impact of a long-term initiative to improve safety culture among professionals working in a Health Area, and to know their perceived usefulness. MATERIAL AND METHODS: An uncontrolled intervention study was designed in a public health care organization including a 3rd level hospital and 5,000 professionals. To measure the impact, the AHRQ Survey was conducted by telephone. A total of 7 dimensions of culture were measured, before starting the project (2012, n=100) and 3 years later (2015, n=207). Variations between 2012 and the respondents aware of the project in 2015 (RAP) were compared, as also between this last group and the rest of respondents (RNAP). The utility was assessed using a 5-item Likert scale, defining higher utility by medians 4 or higher. RESULTS: The response rates were above 80%. In 2015, the 41.5% of respondents were RAP (95%CI: 34.8-48.3), which was perceived as of high utility. Negative variations were detected in "sense of security" (-9.9%, P<.01, vs. 2012, and -4.2% between 2015 groups) and "feedback and communication errors" (-10.0% vs. 2012, and -8.9% between 2015 groups, P<.05). There was a not-significant positive variation in "openness in communication" (1.3% vs. 2012, and 6.9% between 2015 groups). The "management support" showed a not-significant improve in 2015 (37.0%, 95%CI: 30.9-43.1, in RAP; and 38.3%, 95%CI: 33.1-43.4, in RANP) in comparison to 2012 (31.4%, 95%CI: 28.4-39.7). CONCLUSIONS: A paradoxical worsening is detected in several dimensions, this probably due to immaturity of the organization and the instrument used. Thus, tools explicitly considering the degree of maturity may be more appropriate to measure cultural changes, although more studies are needed.

Hybrid 2D-nanomaterials-based electrochemical immunosensing strategies for clinical biomarkers determination.

Owing to the outstanding conductivity and biocompatibility as well as numerous other fascinating properties of two-dimensional (2D)-nanomaterials, 2D-based nanohybrids have shown unparalleled superiorities in the field of electrochemical biosensors. This review highlights latest advances in electrochemical immunosensors for clinical biomarkers based on different hybrid 2D-nanomaterials. Particular attention will be given to hybrid nanostructures involving graphene and other graphene-like 2D-layered nanomaterials (GLNs). Several recent strategies for using such 2D-nanomaterial heterostructures in the development of modern immunosensors, both for tagging or modifying electrode transducers, are summarized and discussed. These hybrid nanocomposites, quite superior than their rival materials, will undoubtedly have an important impact within the near future and not only in clinical areas. Current challenges and future perspectives in this rapidly growing field are also outlined.

Design and validation of a questionnaire for measuring perceived risk of skin cancer.

INTRODUCTION: A perceived risk of cancer encourages preventive behavior while the lack of such a perception is a barrier to risk reduction. There are no instruments in Spanish to measure this perceived risk and thus quantify response to interventions for preventing this disease at a population level. The aim of this study was to design and validate a self-administered questionnaire for measuring the perceived risk of skin cancer. MATERIAL AND METHODS: A self-administered questionnaire with a visual Likert-type scale was designed based on the results of the analysis of the content of a survey performed in 100 patients in the Dr. Ladislao de la Pascua Skin Clinic, Distrito Federal México, Mexico. Subsequently, the questionnaire was administered to a sample of 359 adult patients who attended the clinic for the first time. As no gold standard exists for measuring the perceived risk of skin cancer, the construct was validated through factor analysis. RESULTS: The final questionnaire had 18 items. The internal consistency measured with Cronbach α was 0.824 overall. In the factor analysis, 4 factors (denoted as affective, behavioral, severity, and susceptibility) and an indicator of risk accounted for 65.133% of the variance. CONCLUSIONS: The psychometric properties of the scale were appropriate for measuring the perception of risk in adult patients (aged 18 years or more) who attended the dermatology clinic.

Nanostructured rough gold electrodes as platforms to enhance the sensitivity of electrochemical genosensors.

An electrochemical DNA genosensor constructed by using rough gold as electrode support is reported in this work. The electrode surface nanopatterning was accomplished by repetitive square-wave perturbing potential (RSWPP). A synthetic 25-mer DNA capture probe, modified at the 5' end with a hexaalkylthiol, able to hybridize with a specific sequence of lacZ gene from the Enterobacteriaceae bacterial family was assembled to the rough gold surface. A 25 bases synthetic sequence fully complementary to the thiolated DNA capture probe and a 326 bases fragment of lacZ containing a fully matched sequence with the capture probe, which was amplified by a specific asymmetric polymerase chain reaction (aPCR), were employed as target sequences. The hybridization event was electrochemically monitored by using two different indicators, hexaammineruthenium (III) chloride showing an electrostatic DNA binding mode, and pentaamineruthenium-[3-(2-phenanthren-9-yl-vinyl)-pyridine] (in brief RuL) which binds to double stranded DNA (dsDNA) following an intercalative mechanism. After optimization of the different variables involved in the hybridization and detection reactions, detection limits of 5.30 pg µL(-1) and 10 pg µL(-1) were obtained for the 25-mer synthetic target DNA and the aPCR amplicon, respectively. A RSD value of 6% was obtained for measurements carried out with 3 different genosensors prepared in the same manner.

[Severe thrombocytopenia on admission to the intensive care unit in patients with multiple organ failure]. / Trombocitopenia grave al ingreso en una unidad de cuidados intensivos en pacientes con disfunción multiorgánica.

OBJECTIVE: To evaluate the frequency of severe thrombocytopenia (STCP) (≤ 50,000/µl) in the first 24 hours in patients with multiple organ dysfunction syndrome, and the factors that influence its occurrence. DESIGN: A retrospective, observational study. AREA: Medical-surgical intensive care unit (ICU). Tertiary hospital. PATIENTS: Those with failure of at least two organs, according to SOFA criteria, with the exclusion of neurological and traumatologic critical cases. VARIABLES: Medical history, regular medication, baseline functional status, demographic variables, severity scores in ICU, multiple-organ failure data, course in ICU and main hospital data. RESULTS: A total of 587 patients were included; 6.3% (37 patients) presented with STCP during the first day of admission; 64.6% were men; SOFA 8 (5-10); APACHE II 18 (13-24); APACHE IV 59 (46-73); 32.5% were surgical patients. A total of 79.9% subsequently needed mechanical ventilation, and 71.4% required vasoactive drugs. Overall stay in ICU: 4 (2-10) days, main hospital stay 18 (9-35) days. A total of 29.2% died in the ICU; 11.7% developed STCP during admission to the ICU. Multivariate analysis found the main determining factors in the occurrence of thrombocytopenia on admission to be: history of hospitalization in the last year, albumin and bilirubin levels, and sepsis. CONCLUSION: The prevalence of STCP among critical patients was 6.3%. Its occurrence was associated with albumin and bilirubin levels, sepsis, and with patient admittance in the last year.

[Relationship between the alveolar-arterial oxygen gradient and PaO2/FiO2-introducing PEEP into the model]. / Relación entre el gradiente alveolo-arterial de oxígeno y la PaO2/FiO2 introduciendo la PEEP en el modelo.

OBJECTIVES: To determine whether the alveolar-arterial oxygen gradient (Grad[A-a]O2) helps confirm the influence of PEEP on PaFi (PaO2/FiO2). DESIGN: Observational study; we used linear regression to perform a multivariate study to improve the PaFi formula by taking PEEP into account. SETTING: Tertiary hospital. PATIENTS: We included all patients who were admitted to the intensive care unit, regardless of pulmonary damage. VARIABLES: We recorded personal history, clinical judgment, intensive care data, severity scores on the first day and progression. Two calculated variables: PaFi and Grad(A-a)O2. RESULTS: A total of 956 patients were included: 63.9% men; median age 68 years. On the first day, 31.8% did not have mechanical ventilation (MV), 13.1% had non-invasive MV and 55.1% had invasive MV. PaFi values: 32.9% 0-200, 32.2% 201-300, and 34.8% >300. PEEP values: 0-5 69.8%, 6-10 27.5% and >10 2.6%. We observed a correlation (Pearson) between Grad(A-a)O2 and PaFi of -0.84 (p<0.001). On performing multiple regression (dependent variable: Grad[A-a]O2), the following variables were included in the model: PaFi, PEEP, APACHE IV and SOFA; coefficient of determination (R²) of 0.62 without PEEP and 0.72 with PEEP. We changed the PaFi formula, referring to it as PaFip (PaFi plus PEEP): Ln (PaFi/[PEEP+12]). Correlation index between PaFip and Grad(A-a)O2: -0.9 (p<0.001). We performed linear regression (dependent variable: Grad[A-a]O2) and used PaFip instead of PaFi. Only PaFi remained in the model, and was discretely complemented by APACHE IV; R²=0.8. CONCLUSIONS: By adding PEEP to the PaFi model (PaFip), we clearly improve the latter, as reflected by a better goodness of fit.

[Nebulized colistin treatment of multi-resistant Acinetobacter baumannii pulmonary infection in critical ill patients]. / Utilización de la colistina nebulizada en la colonización e infección respiratoria por Acinetobacter baumannii en pacientes críticos.

OBJECTIVE: To analyze the efficacy of nebulized colistin in the microbiological eradication and clinical improvement of patients with pulmonary infection by multi-resistant Acinetobacter baumannii (MAB). DESIGN: A retrospective study. SETTING: Intensive Care Unit of a Tertiary hospital. PATIENTS: Hospitalized patients on invasive mechanical ventilation with positive MAB cultures of the airway. INTERVENTIONS: All received treatment with colistin (CL). Nosocomial pneumonia (NP) or Tracheobronchitis (TB) was determined according to routine criteria and colonization (CO) was determined in the case of a positive culture in the absence of infection criteria. Three groups of patients were defined: those treated with nebulized CL, those treated with IV CL and those treated with IV CL plus nebulized CL. MAIN MEASUREMENTS: Baseline characteristics. Microbiological eradication and clinical recovery were evaluated according to routine criteria. RESULTS: 83 patients were studied, 54 of whom were treated, with the following diagnoses: 15 (27.8%) with NP, 16 (29.6%) with TB and 23 patients (42.6%) with CO. Nebulized CL was used in 36 patients (66.7%): 66.7% of which for CO, 33.3% in treatment for TB and in no case of NP. In 61.1% of the patients, IV CL was used: 22.2% of which for CO, 38.9% for TB and 38.9% in NP. The combination of IV CL and nebulized CL was used in 15 patients (27.8%): 5 patients (33.3%) CO, 2 patients (13.3%) TB and 8 patients (53.3%) NP. Microbiological eradication was achieved in 32 patients (59.3%), with the following distribution: 8 (47.1%) with IV CL, 15 (83.3%) with nebulized CL and 9 patients (69.2%) with a combination of IV CL and nebulized CL. Clinical recovery was achieved in 42 patients (77.8%): 12 (80%) with IV CL, 18 (94.7%) with nebulized CL and 12 (85.7%) with a combination of nebulized and IV CL. These differences were not significant. In the group of patients with infection due to TB and NP (31 patients, 57.4%), microbiological eradication was achieved in 5 patients (100%) treated with nebulized CL and in 6 of the 9 patients (42.9%) treated with IV CL, the difference being significant (P<.05). Clinical recovery in this group was 100% (6 patients) treated with nebulized CL and 75% (9 of the 12 patients) in the IV CL group. This difference was not significant. CONCLUSIONS: Our study suggests that treatment with colistin in patients with pulmonary infection with multi-resistant Acinetobacter baumannii could be more efficient if it were to be administrated solely nebulized or in combination with IV colistin rather than administered solely intravenously.

[Immunization and bacterial pathogens in the oropharynx as risk factors for alopecia areata]. / Inmunizaciones y bacterias patógenas en la faringe como factores de riesgo para alopecia areata.

INTRODUCTION: Alopecia areata is an autoimmune inflammatory disease affecting the hair follicles. Researchers are currently interested in whether the presence of bacterial pathogens and/or a history of immunization can trigger an autoimmune response in patients who are genetically predisposed. OBJECTIVES: This study aimed to determine whether there is an association between the development of alopecia areata and throat carriage of bacterial pathogens or a history of immunization. MATERIAL AND METHODS: Sixty-five men and women with alopecia areata and 65 control patients with other skin diseases were studied at the Dr Ladislao de la Pascua Dermatology Clinic between September 2008 and February 2009. The patients ranged in age from 18-59 years. Patients with scalp diseases were excluded from the control group. In all cases, the patient was questioned about immunizations received in the previous 6 months, and a throat swab was cultured. RESULTS: A history of immunization (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.6-6.7; P=.001), the presence of bacterial pathogens in the oropharynx (OR, 2.6; 95% CI, 1.1-6.2; P=.033), and being a carrier of Streptococcus pyogenes (OR, 2.1; 95% CI, 1.7-2.5; P=.042) were risk factors for alopecia areata. Klebsiella pneumoniae, S. pyogenes, Pseudomonas aeruginosa, Streptococcus pneumoniae, Serratia marcescens and Escherichia coli were isolated from cultures. CONCLUSIONS: This is the first study to show an association between alopecia areata and throat carriage of bacterial pathogens or history of immunization, as risk factors for development of the disease. Given the characteristics of our study population, the association appears valid for patients with less than 25% hair loss and a course of disease under 1 year.

Treatment of BK virus-associated nephropathy with Cidofovir in renal transplantation.

BK virus-associated nephropathy (BKVN) has become recognized as an important cause of allograft dysfunction among transplant recipients. Despite reduction in immunosuppression, 30%-40% of recipients progress to allograft loss. Cidofovir is an antiviral agent that has been proposed for treatment of BKVN. We describe the clinical course, renal function, and blood viral measurement in 6 renal transplant recipients with BKVN who were treated with low doses of cidofovir. Administration of cidofovir was associated with clearance of BK virus DNA from blood and stabilization of renal function in 5 cases. These data suggest that cidofovir may be useful as adjuvant therapy for BKVN.

[Light chain deposition disease. Experience in our environment]. / Enfermedad por depósito de cadenas ligeras. Experiencia en nuestro medio.

UNLABELLED: The Light chain deposition disease (LCDD) is a strange entity characterised by the deposition of only one type of light chain in the renal tubular basement membranes. It can be associated to a plasma cell dyscrasia, however, it can occur in the absence of any detectable hematological disorder and it is called idiopathic LCDD. The clinical manifestation is renal insufficiency and nephrotic proteinuria, it does not have a clearly fixed treatment and has a severe prognosis. The aim of this work is to analyse the characteristics of the LCDD cases diagnosed within our environment. Six cases were identified, all of them between 1999 and 2005, from a total amount of 640 renal biopsies performed during this period, 4 women and 2 men, average age of 57. Multiple myeloma in 3 patients were detected (50%). The acute renal failure or rapidly progressive renal insufficiency was the most frequent clinical presentation (66%) together with nephrotic proteinuria (66%). All the biopsies showed tubular basement membranes thickening and kappa chains with a linear distribution within the same. The most frequent glomerular pathological finding was the nodular sclerosing glomerulopathy (83%). In one of the cases the affectation was exclusively tubular interstitial with tubular casts. 3 patients were treated, 2 with multiple myeloma. 5 patients needed dialysis: 3 with idiopathic LCDD within an average time of 7 days from the diagnosis to its reception and 2 with myeloma, who started needing dialysis in an average of 46 days. 4 patients died, 2 of them with myeloma. The monitoring time until the death was 13 weeks for the patients with myeloma and 110 weeks for the rest. CONCLUSION: The LCDD seems to be more frequent than what has been published and it is associated to the myeloma in half of the cases. It appears together with severe renal insufficiency and the patient's and renal prognosis is poor.

Determination of the herbicide desmetryne in organised media by adsorptive stripping voltammetry.

An electroanalytical method for the determination of the herbicide desmetryne at nanomolar levels in dispersed media, based on adsorptive stripping voltammetry, is reported. The adsorption of desmetryne at the hanging mercury drop electrode was checked both in micellar solutions, where the anionic surfactant sodium pentanesulphonate was chosen as the most suitable surfactant agent, and in oil-in-water emulsions prepared with ethyl acetate as the organic solvent. In a micellar medium formed with 0.02% sodium pentanesulphonate and with 0.1 mol l(-1) Britton-Robinson buffer (pH 1.5), the herbicide could be determined over the 1.0 x 10(-8)-4.0 x 10(-7) mol l(-1) concentration range, when an accumulation potential of -0.70 V was applied for 50 s. On the other hand, in an oil-in-water emulsion formed with 2% ethyl acetate and 0.04% sodium pentanesulphonate as emulsifying agent in 0.1 mol l(-1) HClO(4), desmetryne could be determined over the 2.0 x 10(-9)-1.0 x 10(-7) mol l(-1) concentration range. The limits of detection were 2.4 x 10(-9) and 4.2 x 10(-10) mol l(-1) in micellar and emulsified media, respectively, with R.S.D.s (n=10) 3.6 and 3.7%. The degree of interference from some other s-triazines on the desmetryne differential pulse response was also evaluated. Finally, the method developed in emulsified medium was applied to the determination of desmetryne in spiked apple juice.

Ruthenium and ruthenium dioxide-modified graphite-ethylene/ propylene/diene and graphite-teflon composite electrodes as amperometric flow detectors. Application to the determination of methionine.

The flow injection amperometric performance of solid composite graphite electrodes with ethylene/propylene/diene (EPD) or Teflon as binding agents, and with Ru or RuO2 particles as electrocatalytic modifiers has been compared. Both, Ru and RuO2 modified electrodes exhibited electrocatalytic properties on the methionine oxidation process in alkaline media. The electrodes composition and the hydrodynamic and chemical variables were optimized. Graphite-EPD (GEPD) electrodes showed a better analytical performance than graphite-Teflon (GPTFE) electrodes. Furthermore, a better sensitivity, repeatability and reproducibility was observed for RuO2-GEPD electrodes when compared with Ru-GEPD electrodes. At an applied potential of +0.50 V, a detection limit for methionine of 4.8x10(-5) mol L(-1), similar to those reported in the literature for other RuO2-modified electrodes, was obtained. The analytical applicability of RuO2-GEPD electrodes was demonstrated by determining methionine in a complex pharmaceutical formulation.

Oil-in-water emulsions as suitable working media for the direct polarographic determination of aziprotryne and desmetryne from its organic extracts in water samples.

The electroanalytical behavior of the reduction of the herbicides aziprotryne (2-azido-4-isopropylamino-6-methylthio-1,3,5-triazine) and desmetryne (4-isopropylamino-6-methylamino-2-methylthio-1,3,5-triazine) in oil-in-water emulsions is reported. This medium allows the differential pulse polarographic determination of these s-triazines directly from their sample extracts in an appropriate organic solvent. Sodium pentanesulfonate was chosen as the most suitable surfactant to be used as emulsifying agent, whereas ethyl acetate was selected as the organic solvent to form the emulsions. The peak current was maximum in a 0.3 mol L(-1) HClO4 medium of the continuous aqueous phase for aziprotryne, and at pH 3.0 for desmetryne, and the potential became more negative as the pH increased for both herbicides. The limiting current is diffusion controlled and the electrode process is irreversible. Four electrons are involved in the overall electrochemical reduction process as determined by controlled potential coulometry, whereas the alpha n(a) values suggested that two electrons are involved in the rate-determining step. Using differential pulse polarography, aziprotryne and desmetryne can be determined in the emulsified medium over the concentration ranges 1.0 x 10(-7)-1.0 x 10(-4) mol L(-1), with limits of detection of 4.5 x 10(-8) mol L(-1) and 6.6 x 10(-8) mol L(-1), respectively. The method was applied to the determination of aziprotryne and desmetryne in spiked irrigation water. At concentration levels of 6.0 x 10(-7) mol L(-1) aziprotryne and 4.0 x 10(-7) mol L(-1) desmetryne, recoveries of 94 +/- 3% and 94 +/- 4%, respectively, were obtained after preconcentration on Sep-Pack C18 cartridges. Finally, partial least-squares regression (PLSR) has been used for treatment of the polarographic data obtained from mixtures of aziprotryne, desmetryne and simazine in oil-in-water emulsions. The size of the calibration set was of 29 samples by ninety two current measurements at different potentials. Prediction of the herbicides concentration within the range 1.0 x 10(-6)-1.0 x 10(-5) mol L(-1) was possible.