Leader-follower formation control based on non-inertial frames for non-holonomic mobile robots.

A chain formation strategy based on mobile frames for a set of n differential drive mobile robots is presented. Considering two consecutive robots in the formation, robots Ri and Ri+1. It is intended that robot Ri+1 follows the delayed trajectory, τ units of time, of the leader robot Ri. In this way, the follower robot Ri+1 becomes the leader robot for robot Ri+ 2 in the formation and so on. With this formation policy, the trailing distance between two consecutive robots varies accordingly to the velocity of the Ri leader robot. Mobile frames are located on the body of the vehicles, in such a way that the position of robot Ri is determined with respect to the frame located on Ri+1 robot. The strategy relies on the fact that the general leader robot R1 describes any trajectory generated by bounded linear v1(t) and angular ω1(t) velocities. For the remaining vehicles in the string, the strategy considers a desired trajectory for the follower robot Ri+1 obtained by an estimation of the delayed trajectory of the leader robot Ri. This desired estimated trajectory is obtained under the knowledge of the actual and past input velocities of the Ri robot. To formally prove the convergence of the formation strategy, the equations describing the time variation of the relative posture between any pair of consecutive vehicles in the formation are obtained, and a feedback law based on local measurements is proposed to get the convergence of robot Ri+1 to the delayed trajectory, τ units of time, of the trajectory previously described by robot Ri. Lyapunov techniques are considered for this fact. The effectiveness of the chain formation solution is evaluated by means of numerical simulations and real time experiments showing an adequate convergence.

ANOVA to Compare Three Methods to Track COVID-19 in Nine Countries / ANOVA en la comparación de tres métodos para rastrear COVID-19 en nueve países

ABSTRACT A new coronavirus denominated first 2019-nCoV and later SARS-CoV-2 was found in Wuhan, China in December of 2019. This paper compares three mathematical methods: nonlinear regression, SIR, and SEIR epidemic models, to track the covid-19 disease in nine countries affected by the SARS-CoV-2 virus, to help epidemiologists to know the disease trajectory, considering initial data in the pandemic, mainly 100 days from the beginning. To evaluate the results obtained with the three methods one-way ANOVA is applied. The average of predicted infected cases with SARS-CoV-2, obtained with the mentioned methods was: for United States of America 1,098,508, followed by Spain with 226,721, Italy with 202,953, France with 183,897 United Kingdom with 182,190, Germany with 159,407, Canada with 58,696, Mexico with 50,366 and Argentina with 4,860 in average. The one-way ANOVA does not show a significant difference among the results of the projected infected cases by SARS-CoV-2, using nonlinear regression, SIR, and SEIR epidemic methods. The above could mean that initially any method can be used to model the pandemic course.

RESUMEN Un nuevo coronavirus denominado primero 2019-nCoV y más tarde SARS-CoV-2 fue encontrado en Wuhan, China en diciembre de 2019. El objetivo de este trabajo es comparar tres métodos matemáticos: regresión no lineal, modelos epidemiológicos SIR y SEIR, para rastrear la enfermedad del COVID-19 en nueve países infectados por el virus SARS-CoV-2, con el propósito de ayudar al epidemiólogo a conocer el curso de la pandemia, considerando principalmente sus primeros 100 días. Para evaluar los resultados obtenidos de la aplicación de los tres métodos, se aplicó ANOVA de una vía. El número promedio de casos infectados con SARS-CoV-2, obtenidos con los tres métodos descritos son: para Estados Unidos 1,098,508, seguido de España con 226,721, Italia con 202,953, Francia con 183,897 Reino Unido con 182,190, Alemania con 159,407, Canadá con 58,696, México con 50,366 y Argentina con 4,860 en promedio. El ANOVA de una vía no muestra diferencias significativas entre los resultados de los casos infectados proyectados por SARS-CoV-2, utilizando la regresión no lineal y los métodos SIR and SEIR. Lo anterior podría señalar que cualquiera de los tres métodos estudiados puede modelar el curso de la pandemia en las condiciones descritas para cada uno.

DIAGNOSTIC PERFORMANCE OF WAIST CIRCUMFERENCE MEASUREMENTS FOR PREDICTING CARDIOMETABOLIC RISK IN MEXICAN CHILDREN.

OBJECTIVE: The accumulation of abdominal fat is associated with cardiometabolic abnormalities. Waist circumference (WC) measurements allow an indirect evaluation of abdominal adiposity. However, controversy exists over which WC reference values are the most suitable for identifying the pediatric population at risk. The aim of the study was to evaluate the ability of various WC indices to identify abdominal obesity as diagnostic tools for predicting cardiometabolic risk in Mexican children and adolescents. METHODS: Anthropometric measurements were performed and biochemical profiles determined in a crosssectional study that included 366 children and adolescents. Four parameters were used to evaluate abdominal obesity in our study group: (1) WC >90th percentile, according to the Fernández reference in a Mexican-American population measured by the National Center for Health Statistics (NCHS) technique; (2) WC >90th percentile, according to the Klünder reference in a Mexican population (measured by the World Health Organization [WHO] technique); (3) waist-to-height ratio (WHtR) >0.5 according to WHO; and (4) WHtR >0.5 according to NCHS. The ability of each of the indices to discriminate cardiometabolic abnormalities (fasting plasma glucose, dyslipidemia, and hypertension) was assessed. RESULTS: WHtR >0.5 according to WHO or NCHS references showed greater sensitivity to detect metabolic abnormalities compared to percentile reference parameters (74.3 to 100% vs. 59.0 to 88.9%; P<.05). However, the percentiles displayed more specificity to identify these alterations (46.2 to 62.2 vs. 21.3 to 46.9; P<.05). Area under the curve analysis showed that WHtR >0.5 can more readily detect hypertriglyceridemia (0.642), hypoalphalipoproteinemia (0.700), and a combination of two or more metabolic abnormalities (0.661), whereas WC >90th percentile, according to Klünder, better detected hyperglycemia (0.555). CONCLUSION: WHtR >0.5 is a sensitive measure to identify pediatric patients with cardiometabolic alterations, despite its low specificity, and is a useful diagnostic tool to detect populations at risk. Based on the results of this study, we recommend preferential use of the Klünder waist circumference references over the Fernández method in Mexican pediatric populations. ABBREVIATIONS: AUC = area under the curve BMI = body mass index HDL = high-density lipoprotein IDF = International Diabetes Federation LDL = low-density lipoprotein MS = metabolic syndrome NCHS = National Center for Health Statistics ROC = receiver operating characteristic WC = waist circumference WHO = World Health Organization WHtR = waist-to-height ratio.

Knowledge of appropriate foods and beverages needed for weight loss and diet of patients in an Obesity Clinic.

BACKGROUND/OBJECTIVE: Knowledge does not automatically translate into behaviour change. This study examined the relationship between knowledge of appropriate foods and beverages needed for weight loss and the diet of patients seeking weight management. SUBJECTS/METHODS: A cross-sectional study of 104 consecutive first-time patients (55 women and 49 men) seeking weight management, with a mean age of 37.3 ± 11.8 years and a BMI of 44.9 ± 9.4 kg/m(2), was carried out; 67.3% of these patients had a BMI of 40 kg/m(2) or greater. Patients were told to design a detailed weight-loss diet that they would recommend to a person with the same characteristics (recommended diet or RD) as themselves and asked whether the RD was similar to their own. Consumed diet (CD) was assessed by a different dietitian through a 24-h diet recall. Estimated energy requirement (EER), energy content of RD and CD and number of fruit, vegetable, cereal and sweetened-beverage portions were calculated. Statistical differences were assessed through the Pearson's correlation and the Wilcoxon's rank-sum tests. RESULTS: RD and CD were 1104 ± 243 and 1976 ± 708 kcal for women and 1254 ± 287 and 2743 ± 1244 kcal for men, with statistical differences for both genders (P<0.001). Energy content of the RD was lower than the EER in men and women (P<0.001); CD was lower than the EER in women (P=0.033). Number of fruit/vegetable portions was lower in CD than in the RD in women (P<0.001), whereas cereal and sweetened-beverage portions were higher in CD than in the RD in both genders (P<0.001). RD was not followed by 46.1% of the patients. CONCLUSIONS: Patients with obesity seeking care have knowledge of the appropriate dietary strategies needed for weight loss, but do not translate it into practice. Treatment approaches should include tools that help patients to implement their nutrition knowledge.

Causas que inciden en cancelación de cirugías desde la percepción del personal de salud / Causes which yield to surgery call-offs from the perspective of the health staff

Introducción: La calidad en la atención en los servicios hospitalarios depende de múltiples factores, cada proceso que se ejecuta para el cumplimiento del cuidado, debe ser indicador de atención. La cancelación de cirugías es uno los indicadores que revelan las dificultades que se pueden estar presentando en los centros sanitarios. Objetivo: Identificar desde la percepción de los profesionales de salud, los factores que inciden en la cancelación de cirugías en un hospital de alta complejidad. Métodos: El diseño del estudio fue descriptivo transversal, la muestra estuvo conformada por 30 sujetos: 15 enfermeras y 15 médicos, de los cuales 3 médicos y 2 enfermeras decidieron voluntariamente no participar en el estudio. Los investigadores recogieron la información a través de un cuestionario de preguntas abiertas y cerradas; tomando como referencia la lista de chequeo de "cirugía segura", los datos se analizaron en EPI-INFOTM versión 18. Conclusión: Se identificó que los profesionales de la salud perciben una escasa gestión administrativa para cumplir con todos los procedimientos quirúrgicos que se deben realizar, lo cual repercute de forma negativa en el paciente y su familia, además de los altos costos a nivel institución que esto implica.

Introduction: Quality in hospital health services depend on multiple factors. Therefore, each process related to the accomplishment of care should be an indicator of the attention level. Surgery call-offs is one of the indicators revealing difficulties which health settings might be having. Objective: The objective of this study was to identify, from the perspective of health professionals, those factors which yield to surgery call-offs in a highly complex hospital. Methods: The study design was basic and descriptive with a sample of 30 subjects: 15 nurses and 15 doctors, from which 2 nurses and 3 doctors ultimately decided not to participate. The researchers gathered the data through a questionnaire with open and close questions, having as a reference the "Safe Surgery" check list. These data were analyzed using the EPI-INFOTM version 18 software. Results: The most relevant findings were: 44% of the surgery call-offs motives were considered administrative, while 28% were attributed to assistance causes. Conclusion: As a conclusion, it was identified that health professionals perceive a low grade administration management to accomplish all the surgical procedures which should be performed, thus, negatively affecting the patients and their families, and generating impacts on the institutional costs.

Highly correlated ab initio study of the low frequency modes of propane and various monosubstituted isotopologues containing D and 13C.

With the purpose of providing some clues that could encourage the spectral recordings of propane and various monodeuterated and (13)C isotopologues and also to explore their far infrared spectra at low temperatures, the energy levels corresponding to their three lowest frequency modes are determined variationally using a flexible model in three dimensions. Five vibrationally corrected potential energy surfaces are computed using CCSD(T) ab initio calculations. In spite of the quality of these highly correlated potentials in molecules with similar structures, it was proven that an empirical adjustment of the surfaces would enclose accurately the experimental and theoretical frequency residuals and therefore it is also used in the present work. Interacting terms, energy levels and tunneling splittings are provided for CH3CH2CH3, CH3(13)CH2CH3, (13)CH3CH2CH3, CH2DCH2CH3 and CH3CHDCH3. Infrared and Raman transitions of CH3CH2CH3 are assigned. Correlation between symmetry species of the five isotopologue symmetry groups (G36, G36, G18, G6 and G'18, respectively) is established for the classification of the levels and torsional splittings. The rotational constants are determined with CCSD(T)/CBS (A0 = 29263.46 MHz, B0 = 8454.10 MHz and C0 = 7466.64 MHz) using a non-relativistic procedure. Fundamental anharmonic frequencies corresponding to the high and medium amplitude modes are computed for all the isotopologues. The adjusted parameters are accurate enough to be employed in further spectral analysis.

B-vitamin mixture improves the analgesic effect of diclofenac in patients with osteoarthritis: a double blind study.

According to the high consumption of the mixture of B vitamins and diclofenac in several countries, this combination has constituted a frequently used option in pain therapy from inflammatory origin. Although the evidence obtained from inflammatory pain animal models has shown the existence of analgesic synergy between diclofenac and the B vitamins mixture, the corresponding clinical evidence is scarce. A double-blind, randomized clinical trial study was designed to characterize the analgesic effect and safety of diclofenac and B vitamins against diclofenac alone in patients with severe osteoarthritis. Forty eight patients programmed to total knee arthroplasty with a pain level ≥7 in a 1-10 cm visual analogue scale were allocated to receive a single intramuscular injection of sodium diclofenac (75 mg) alone or combined with thiamine (100 mg), pyridoxine (100 mg) and cyanocobalamin (5 mg), and the pain level was evaluated during 12 h post-injection. Diclofenac+B vitamins mixture showed a superior analgesic effect during the assessed period and also a better assessment of the pain relief perception by patients than diclofenac alone. This study constitutes a clinical support on the improvement of the analgesic effect of diclofenac by B vitamins in patients with osteoarthritis programmed to total knee arthroplasty, as a clinical model of inflammatory pain.

Diversity of Flavobacterium psychrophilum and the potential use of its phages for protection against bacterial cold water disease in salmonids.

Flavobacterium psychrophilum causes rainbow trout fry syndrome (RTFS) and cold water disease (CWD) in salmonid aquaculture. We report characterization of F. psychrophilum strains and their bacteriophages isolated in Chilean salmonid aquaculture. Results suggest that under laboratory conditions phages can decrease mortality of salmonids from infection by their F. psychrophilum host strain. Twelve F. psychrophilum isolates were characterized, with DNA restriction patterns showing low diversity between strains despite their being obtained from different salmonid production sites and from different tissues. We isolated 15 bacteriophages able to infect some of the F. psychrophilum isolates and characterized six of them in detail. DNA genome sizes were close to 50 Kbp and corresponded to the Siphoviridae and Podoviridae families. One isolate, 6H, probably contains lipids as an essential virion component, based on its chloroform sensitivity and low buoyant density in CsCl. Each phage isolate rarely infected F. psychrophilum strains other than the strain used for its enrichment and isolation. Some bacteriophages could decrease mortality from intraperitoneal injection of its host strain when added together with the bacteria in a ratio of 10 plaque-forming units per colony-forming unit. While we recognize the artificial laboratory conditions used for these protection assays, this work is the first to demonstrate that phages might be able protect salmonids from RTFS or CWD.

A comparative study of the traditional method, and a point-score system for allocation of deceased-donor kidneys: a national multicenter study in Mexico.

BACKGROUND: The National Transplant Center in Mexico has ruled that deceased-donor kidney allocation is a function of each hospital's Internal Transplant Committee. The aim of this study was to compare and analyze results for of the traditional method and a point-score system in the allocation of deceased patient's kidneys. METHODS: The 12 major kidney transplant centers in the country having a deceased-donor program were invited to participate. Only 3 of them replied to the invitation during 2010. A point-score system was proposed to them, comprising blood group, waiting list time, HLA type, and donor and recipient ages. Once the final recipient was chosen, an explanation of reasons for the choice was requested. Thirty-eight transplants were presented. Kappa coefficient was used to measure degree of agreement in both allocation systems. Organs donated for transplantation came from patients between 4 and 54 years old, including 52% female, 52% O+ blood type, 31% A+, and 11% B+, 44% cranial-encephalic trauma, and 44% brain hemorrhage. RESULTS: Global agreement was 52.6% (kappa = 0.343), and partial agreement was 76.3% (weighted kappa = 0.204), assigning more intensity to extreme values, but with a lower correlation index. A more intense agreement, without discriminating by hospital, was found for "A" category (blood group), followed by "B" category (waiting list time). DISCUSSION: Taking into consideration the determining factors for long-term graft survival, it is indispensable to include criteria such as donor and recipient ages and HLA typife in the allocation process. This first draft of a point-score system in organ allocation included waiting list time, blood group, urgency related to vascular/peritoneal access for dialysis, clinical condition, donor/recipient age ratio, and HLA antigenic compatibility.

Pre-transplant mycophenolate mofetil pharmacokinetics in Mexican children.

Mycophenolate mofetil is an immunosuppressive pro-drug frequently used to prevent renal graft rejection. It is hydrolyzed by esterases to obtain the active drug mycophenolic acid (MPA). There is high inter-patient variation in mycophenolic acid pharmacokinetics. Area under the concentration versus time curve (AUC) is used for therapeutic drug monitoring and recommended levels are 30-60 microg x hr/L. The aim of this study was to determine mycophenolic acid pharmacokinetics in children awaiting renal allograft in order to predict mycophenolate mofetil dose requirements. Children with end-stage renal disease on the waiting list for renal allograft transplantation were invited to participate in the study. A nine-point pharmacokinetic profile was performed. All patients received a single dose (600 mg/m2, subcutaneously) of mycophenolate mofetil at time zero. Mycophenolic acid was measured by HPLC. The AUC0-12h was estimated by the trapezoidal rule. Ten children were included in the study. Mean age was 13.5 +/- 3.5 years. The median AUC0-12h was 20.3 microg x hr/L, median Cmax = 0.7 microg/mL. Two children (20%) had no detectable levels of mycophenolic acid after a single mycophenolate mofetil dose, other two patients had AUC > 60 microg x hr/L. One patient had abdominal pain 1 hr after the mycophenolate mofetil dose. Twenty percent of our patients had AUC0-12h higher than the recommended value after a single mycophenolate mofetil dose, those patients should receive lower mycophenolate mofetil dose since the beginning of the transplant to avoid adverse events, and another 20% of patients had no detectable mycophenolic acid levels after a single mycophenolate mofetil dose. UGT1A9 gene polymorphisms remain to be studied in our patients, since they could explain the differences in bioavailability.

Degradation of immobilized azo dyes by Klebsiella sp. UAP-b5 isolated from maize bioadsorbent.

The degradation of two immobilized dyes by Klebsiella sp. UAP-b5 was studied. In batch experiments, the azo dyestuffs Basic Blue 41 and Reactive Black 5 were immobilized onto corn cobs by adsorption, and the adsorption process was characterized by a pseudo-second-order kinetic equation. Klebsiella sp. UAP-b5 was previously isolated from the corn waste and shown to decolorize these dyes in liquid systems. Here, we demonstrate anaerobic decolorization and reductive biodegradation of these dyes by means of spectrophotometry, HPLC, and IR spectroscopy of the solid waste and desorption solutions. We also demonstrate adsorption of compounds that resemble known degradation products.

Rotura del tendón tibial anterior / Tibialis anterior rupture

The tibialis anterior muscle is the main ankle extensor. Its tendon ruptures are very infrecuent, and there are only a few case reports about them in literature. Treatment in these patients must be tailored to their functional activity, being only those who are inactive candidates to orthopedic treatment. In most cases treatment is surgical, by termino-terminal repair, augmentation techniques with extensor hallucis longus (EHL) or tibialis anterior tendon allografting, among other techniques, depending mainly on the type of lesion and the time of evolution. In this case report we present a male 60 year old patient with End Stage Chronic Kidney Disease on Hemodialysis, who after a minor trauma in left foot while on plantar flexion presents acute pain in ankle’s medial aspect and step page gait. In the Emergency Department evaluation he was unable to stand in his heels, despite an adequate foot dorsiflexion. On Magnetic Resonance Imaging a rupture of the distal part of the tibialis anterior tendon was shown. Two weeks later a surgical termino-terminal repair with ethibond was performed, followed by 9 weeks of inmobilization and then rehabilitation. Twelve weeks after the surgical procedure the patient regain his normal activities, without gait limitation.

El músculo tibial anterior es el principal extensor del tobillo. Las roturas de su tendón son muy poco frecuentes y existen en la literatura sólo casos aislados que reportan su existencia. El tratamiento en estos pacientes debe basarse en la actividad funcional de estos, siendo sólo los pacientes inactivos candidatos al tratamiento ortopédico con órtesis. En la mayoría de los casos el tratamiento es quirúrgico, indicándose reparación término-terminal, técnicas de transferencia tendínea con extensor hallucis longus (EHL) o la utilización de aloinjerto entre otras técnicas, dependiendo del tipo de rotura y tiempo de evolución. En este reporte se relata el caso de un hombre de 60 años, con antecedentes de insuficiencia renal crónica, en diálisis, quien al sufrió un trauma menor en flexión plantar del pie izquierdo, presentó dolor agudo en la región medial del tobillo y posteriorincapacidad de extender el tobillo al realizar la marcha. Fue evaluado en el servicio de urgencia destacando la imposibilidad de mantenerse en talones, pese a tener una dorsiflexión adecuada al examen físico. Se solicitó una Resonancia Magnética (RM), donde se evidenció una rotura completa en la región distal del tendón tibial anterior. Se operó a las 2 semanas, realizándose una reparación término-terminal con sutura no reabsorbible. El post operatorio se manejó con inmovilización por 9 semanas y posterior rehabilitación. El paciente no presentó complicaciones, logrando reintegrarse a sus actividades laborales a las 12 semanas.

Plastia de Lapidus en el tratamiento quirúrgico del quinto ortejo supra aducto / Lapidus procedure for treatment of overlapped fifth toe

The varus fifth toe pathology, in spite of its relative frequency and clinical relevance, has been barely studied in relation to the treatment results. 28 overlapped fifth toes operated according to the Lapidus Technique were evaluated retrospectively, corresponding to 17 patients, age average 28 years, opered since year2003. The minimum follow up time was 6 months. The surgical technique consisted on a dorsal approach in "italic s" on the 5° metatarsophalangic joint, capsulotomy and transference of the EDL to the digiti quinti abductor. Preoperative Hallux Metatarsophalangeal-lnterphalangeal AOFAS Scale average was 88,1 and varied to 99,4 points to the six months of pursuit. 100% of the patients showed complete satisfaction with the result. Only 2 patients presented minor postoperative complications (wound infection and dehiscence), which were handled ambulatory. Lapidus Procedure is a safe procedure and effective in the correction of overlapping fifth toe.

La patología del 5° ortejo varo, a pesar de su relativa frecuencia y relevancia clínica ha sido escasamente estudiada en relación a los resultados de tratamiento. Se evaluaron retrospectivamente 28 quintos ortejos supra aducto flexibles operados según la técnica de Lapidus, correspondientes a 17 pacientes, edad promedio 28 años, operados desde el año 2003. El seguimiento mínimo fue de 6 meses. La técnica quirúrgica consistió en abordaje dorsal en "s" itálica sobre la 5° articulación metatarsofalángica, capsulotomía y transferencia del EDL al abductor digiti quinti. El promedio de la Escala AOFAS para antepie preoperatoria fue de 88,1 y varió a 99,4 puntos a los seis meses de seguimiento. 100 por ciento pacientes mostraron satisfacción completa con el resultado. Sólo 2 pacientes presentaron complicaciones menores posoperatorias (infección de la herida y dehiscencia) que se manejaron ambulatoriamente. La plastia de Lapidus es un procedimiento seguro y eficaz en la corrección del quinto ortejo varo flexible.

Lack of correlation between DNA copy number and mRNA expression levels of c-myc in gamma-radiation-induced mouse thymic lymphomas by using quantitative real-time PCR.

BACKGROUND: It is well documented that over-expression of the c-myc proto-oncogene occurs in the vast majority of mouse thymic lymphomas induced by gamma-irradiation, evidencing the importance of this gene in T-cell lymphomagenesis. However, it remains unknown whether elevated levels of c-myc expression are driven by extra c-myc copy numbers. MATERIALS AND METHODS: Here we use a quantitative test on the basis of real-time PCR to determine the cellular copy number of c-myc in a set of 14 g-radiation- induced thymic lymphomas obtained from (C57BL/6J x BALB/cJ) F1 hybrid mice with increased mRNA c-myc expression. RESULTS: Since 5 out of 14 (35.7%) cases had no extra copy numbers of c-myc, gene amplification was obviously not the cause of c-myc over-expression in these tumours. In the remaining 9 tumours, c-myc over-expression was also accompanied with extra DNA copy numbers. Therefore, c-myc amplification might be a consequence of the genomic instability subsequent to the up-regulation of c-myc. However, linear regression analysis showed a lack of correlation between increasing DNA copy numbers and mRNA over expression of c-myc in these tumours (r = 0.029, p = 0.94). CONCLUSION: De-regulation of c-myc does not necessarily imply amplification of this gene in these tumours. This report is, to our knowledge, the first one comparing c-myc amplification with expression in lymphomas of the T-cell lineage.

Procesamiento léxico-semántico en un grupo de sujetos sanos: estudio con potenciales relacionados a eventos

resumen está disponible en el texto completo

Abstract: Introduction: An insight into the meaning of words is one of the central processes of semantic memory. To evalúate the access to the cognitive representation of the meaning of words, in the present study we used the lexical decision paradigm developed by Marcos. In this situation, the subject has to recognize if the presented stimulus corresponds to a word or a pseudo-word with the purpose of building a model of normal processing. Once such a model of normal processing is obtained, the findings can be contrasted with pathologies in which semantic memory is altered. Method: The sample consisted of 32 healthy subjects (7 men, 25 women), right-handed and with no personal or familial history of neurological or psychiatric conditions. The average age of the subjects was 34.4 (+ 9.56) years and they had an average educational level of 16.2 (+ 4.4) years. The lexical decision paradigm employed in this study is constituted by 408 stimuli, 240 words and 168 pseudo-words. The criteria for word selection were: frequency, length, grammatical category and morphology. Electroencephalogram (EEG) monopolar recording was obtained from 19 derivations (F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5, T6, Fz, Cz and Pz), as well as event-related potentials (ERPs) for the word and pseudo-word sub-states. Results: In the first place, a chi-squared analysis was performed to establish whether significative differences existed between the rates of correct and incorrect answers for both sub-states. The value of chi-squared was 65.7 (gl=1) and significant for p<0.0001. A correlation value of 0.43 (p< 0.02) was found when the educational level and the percentage of correct answers in the sub-sate word were compared. On the other hand, for the pseudo-word sub-state, the value 0.24 was encountered for the same correlation, being statistically non-significant. Pearson's correlation coefficient was also calculated for the educational level variable compared to the mistakes committed when subjects were presented with frequent and infrequent words. In the case of infrequent words, a value of r = - 0.43 (p<0.02) was obtained when the educational level and the number of mistakes were correlated. No correlation was found when the educational level and the number of mistakes commited for frequent words were compared (r = - 0.06). A multivariate variance analysis for repeated measures was performed to determine significant differences between the reaction times when recognizing words or pseudo-words. The outcome showed that all effects were significant in the following cases: reaction times for words and pseudo-words, notwithstanding whether they were correct or incorrect; comparison between correct and incorrect answers, independently of their being words or pseudo-words, as well as the interactions between both effects. To determine differences between average ERPs for both sub-states, Student's T-test was applied with Bonferroni's correction and p<0.0002 as the significance level. Significant differences were encountered between the two sub-states, independently of the age or gender. In the 375-495 ms latency interval, a negative component was appreciated in the pseudo-words case, showing significant differences (p<0.0002) in the following derivations: F3, F4, C3, C4, P3, P4, O1, O2, T3, T5, T6, Fz, Cz and Pz. Amplitude differences between the two sub-states were more evident in Pz and P3 derivations followed by Cz. In addition, a positive component in the 700-795 ms latency interval was detected (mainly in 795 ms) when pseudo-words were presented. Here, the significant differences (p<0.0002) were manifest in the following derivations: F3, C3, P3, F7, T3, T5 and Pz. Amplitude differences between the two sub-states were mainly patent in Pz and P3 followed by C3. Discussion: When analyzing behavioral aspects, subjects made more mistakes when presented with words. However, individuals with less education were the ones committing more mistakes. From this we can infer that this variable may be associated with the range of lexical repertoire. A relation was encountered between educational level and word recognition. With regard to reaction times, significant differences were detected between both sub-states, since the recognition of both words and correct answers was achieved in shorter reaction times. Average reaction times for words and pseudo-words were 819.73 ms and 999.35 ms, respectively. Similarly, the latest potential component appeared in an interval of significant differences between 600 and 940 ms, though with a significance p<0.0005 between 690 and 805 ms. This means that positiveness occurred much sooner than the response, implying that the activity underlying ERPs is related to a cognitive processing of information due to the paradigm used. The analysis of ERPs primary components for both sub-states shows that significant differences arise until 270 ms. The negative component in this study was present between 270 and 580 ms, rendering it similar to N400 given its latency (around 400 ms). Although well-defined in centro-parietal regions, its distribution was generalized, which corresponds to the results of studies using the semantic incongruence paradigm. According to the data from previous research on ERPs, N400 has been associated with the integration process. If this were the case, this association would be equivalent to the semantic incongruence within a lexical integration process described in conventional literature as a "semantic facilitator", only that this time it would be limited to the process of access to the lexicon, which can be interpreted as a discrimination of the answer by assigning a meaning to a word, that is, to process information in the semantic module. This negative component may be related to the generalized response to brain activity when given a meaningless stimulus, i.e., a pseudo-word. Similarly, the wave amplitude may be related to the amount of activation necessary to gain access to the semantic representation of the stimulus in the memory. With regard to the positive component in this study, it is present between 600 and 940 ms and is interpreted as a late P300 (P3b), which has a latency in the 500-1400 ms interval. It is distributed over the centro-parietal region, making it a liable participant in the task categorization process, in which it is necessary to discriminate between the target from the non-target stimulus, and also reflects focalized attentional processes (voluntary) involved in the execution of the task. From the former, it is believed that this component may be related to attentional resources necessary to process the presentation of pseudo-words. Research dealing with the P600 component locate it within the context of statements and associate it with an anomaly in statement syntax. Therefore, even though the positive component lies within the P600 latency domain, this particular component was not considered as being present in this study, because a syntax incongruence paradigm was not used. Finally, the contribution of the present study lies in the finding of N400 and "P600" components, which have been reported when the "semantic facilitator" and the syntax incongruence paradigm were respectively used, but had not been observed when a lexical decision paradigm based on word recognition per se was utilized. Similarly, given that our results stem from a sample of healthy subjects, a comparison can be made with a patient population with semantic memory alterations.

Tendinitis cálcica del músculo longus colli: a propósito de un caso / Calcific tendinitis of the longus colli muscle: case report

We report a case of calcific tendinitis of the Longus Colli muscle. We reviewed the differencial diagnosis and performed a literature search. To our knowledge this is the first Chilean report on this unusual disease.

Nosotros reportamos un caso de Tendinitis cálcica del músculo Longus Colli. Se revisa la literatura y los diagnósticos diferenciales. Se trata de una enfermedad infrecuente, según nuestro conocimiento sería el primer caso reportado en la literatura chilena.

Chromatographic and electrochemical determination of quercetin and kaempferol in phytopharmaceuticals.

An NP-HPLC method both with diode-array (DAD) and electrochemical detection (ED) was developed and validated for the determination of quercetin and kaempferol, the principal active constituents in phytopharmaceuticals of Ginkgo Biloba. Calculated retention of the two flavonoids was contrasted with experimental values in five different reversed phase columns for methanol-water, acetonitrile-water, THF-water and dioxane-hexane binary mixtures as mobile phases. The capacity factor k, selectivity alpha and asymmetry factor F were evaluated and compared in DAD-RP-HPLC, DAD-NP-HPLC, ED-RP-HPLC and ED-NP-HPLC. The methods were used for the quantitative analysis of acid hydrolyzed extracts of tablet phytopharmaceuticals. Calibration curves were linear within the range 10 and 40 microg ml(-1) for the DAD and 10-270 microg ml(-1) for the ED, whereby limits of detection ranged from 0.5 microg ml(-1) (quercetin) to 0.1 microg ml(-1) (kaempferol). The electrochemical method based on differential pulse voltammetry (DPV) with a C-PVC electrode resolved the quercetin and kaempferol peaks and exhibited a two orders higher sensitivity in comparison with a carbon fiber electrode. DPV calibration curves were linear within the range 96-300 microg ml(-1) for quercetin and 68-960 microg ml(-1) for kaempferol. The respective oxidation peaks appeared at 462 and 518+/-2 mV and were used in the direct determination of quercetin in extracts of commercial phytopharmaceuticals.

Origin of Mayans according to HLA genes and the uniqueness of Amerindians.

The HLA allele frequency distribution of the Mayans from Guatemala was studied and compared with those of other First American Natives and worldwide populations (a total of 12,364 chromosomes and 6182 individuals from 60 different populations). The main conclusions were (1): the closest Amerindian group to Mayans is the Arhuacs, who were the first recorded Caribbean Islands' inhabitants (2). Mayans are not so close to Mesoamerican Zapotec, Mixe and Mixtec Amerindians, who genetically cluster together. Mixe had been related to Mayans only on linguistic bases (3). DRB1*0407 and DRB1*0802 alleles are found in 50% of Mayans; these alleles are also found in other Amerindians, but the Mayans' high frequencies may be showing a founder effect for this Mesoamerican-Caribbean population (4). Extended Mayan specific HLA haplotypes are described for the first time (5). Language and genes do not completely correlate in microgeographical studies (6). Significant genetic input from outside is not noticed in Meso and South American Amerindians according to the genetic analyses; while all world populations (including Africans, Europeans, Asians, Australians, Polynesians, North American Na-Dene Indians and Eskimos) are genetically related. Meso and South American Amerindians tend to remain isolated in the neighbour joining analyses.

[Sarcoidosis and idiopathic intracranial hypertension. A case report]. / Sarcoidosis e hipertension intracraneal idiopática. A proposito de un caso.

INTRODUCTION: Sarcoidosis is a multisystemic disease of unknown etiology, characterized by non caseating granulomas in different organs. The respiratory system is the most frequently involved organ system. Up to 90% of patients with sarcoidosis have pulmonary involvement. The neurological involvement is rare and only occurs in the 5 7% of the patients. CASE REPORT: We present the case of a 41 years old woman who had severe headache and a sixth nerve palsy. Diagnosis of sarcoidosis was made in association with idiopathic intracranial hypertension (IIH). CONCLUSIONS: Sarcoidosis can involve any portion of the nervous system. An etiologic association between sarcoidosis and IIH could be identified in this case. Treatment with corticosteroids, repeated lumbar punctures and diuretics were prescribed and induced a significant clinical improvement.

Prevalence and correlates of erectile dysfunction in Salvador, northeastern Brazil: a population-based study.

Our objectives were to determine the prevalence of erectile dysfunction (ED) in Brazil and to explore potential sociodemographic, medical, and lifestyle correlates. A cross-sectional, population-based, household survey was conducted in Salvador, Bahia, Brazil. Cluster samples of representative households were randomly selected for interviews. Of 654 eligible subjects, 602 (92%) participated. A structured questionnaire was administered by trained interviewers. ED was categorized as 'none', 'mild', 'moderate', or 'severe' according to the ability to 'attain and/or maintain an erection satisfactory for sexual intercourse'. All data were obtained by self-report. The age-adjusted prevalence of ED was 39.5% (minimal 25.1%, moderate 13.1%, severe 1.3%). Prevalence and severity increased with age. Having never been married, diabetes, depression, or prostate disease and current depressive or lower urinary tract symptoms were significantly (P<0.05) associated with increased prevalence. Medical, sociodemographic, and lifestyle variables associated with ED may alert physicians to patients at risk for ED and offer insight to its etiology.