Análisis bibliométrico de la producción científica del Dr. Antonio Vidal Mayorga (1895-1968), Revista Médica Hondureña / Bibliometric analysis of the scientific production of Dr. Antonio Vidal Mayorga (1895-1968), Revista Médica Hondureña

Antecedentes: El Instituto de Enfermedades Infecciosas y Parasitología Antonio Vidal conmemora el trigésimo aniversario de su creación (1993-2023). Objetivo: Realizar un análisis bibliométrico de la producción científica del Dr. Antonio Vidal Mayorga en la Revista Médica Hondureña (RMH). Métodos: Análisis bibliométrico y revisión de alcance mediante búsquedas digitales en la Biblioteca Virtual en Salud de Honduras (https:// honduras.bvsalud.org/) y la RMH (https://revistamedicahondurena. hn/), y archivos físicos del Instituto Antonio Vidal. Los artículos fueron clasificados por tipo, año de publicación, tema específico (enfermedades transmisibles, agentes etiológicos y vectoriales, enfermedades crónicas no transmisibles, otros) y tema general (especialidades médicas, enfermedades, reseñas biográficas, actividades asistenciales y de salud pública, otros). Resultados: En los primeros 18 años de la RMH (1930-1947), el Dr. Vidal publicó 79 artículos: caso clínico 19, opinión 18, original 17, revisiones bibliográficas 11, reseñas de revistas 7 y libros 2, editoriales 5. Los años con mayor número de publicaciones fueron 1934 (10) y 1945 (16). Los temas generales con el mayor número de publicaciones fueron malaria (22) y deficiencias nutricionales (9). Se destacan sus observaciones originales con caracterizaciones clínicas, resultados de laboratorio y observaciones epidemiológicas en el campo, incluyendo observaciones entomológicas, y los artículos de opinión con propuestas sobre la organización y administración de la salud pública del país. Discusión: El Dr. Antonio Vidal Mayorga, médico y maestro ejemplar, se distingue en el contexto de la época en que vivió. Su obra fue impulsada por su capacidad de conjuntar la clínica, la epidemiología, el laboratorio, la salud pública, la investigación, la docencia y la proyección social...(AU)

Etiología viral en el síndrome de Guillain-Barré: buscando una respuesta a lo idiopático / Viral etiology associated with Guillain-Barré Syndrome: seeking an answer to the idiopathic

El Síndrome de Guillain-Barré (SGB) es un raro trastorno del sistema nervioso, donde el sistema inmunológico del paciente ataca las neuronas periféricas en extremidades, causando debilidad muscular, pérdida de sensibilidad y a veces parálisis total. El origen de este trastorno, ha sido asociado a  respuestas inmunes desencadenadas luego de la  infección por Campylobacter spp.   Sin embargo, cuando no existe una causa evidente de la enfermedad, esta no suele ser investigada debido al mayor interés que requiere el tratamiento. Por ello, la mayoría de los casos  se notifican como origen idiopático.  Entre Enero y Marzo de 2016 a nivel mundial se registraron brotes del SGB en 8  países, vinculados con la emergencia del virus Zika. En Perú, desde finales de 2018 ha reportado con mayor frecuencia brotes de SGB y aunque no se ha confirmado asociación con Zika, el incremento de casos, la extensión geográfica donde se produjeron y las características clínicas de los pacientes afectados, tienen patrones comunes que llevan a sospechar un origen infeccioso principalmente de tipo viral . Por lo tanto, es importante conocer la evidencia científica actual acerca del rol que desempeñan algunos virus en este síndrome, permitiendo ampliar nuestro panorama epidemiológico con nuevas herramientas para hacer frente a esta enfermedad.

Guillain-Barré Syndrome (GBS) is a rare disorder of the nervous system, where the patient's immune system attacks the peripheral nerve cells in the arms and legs, causing muscle weakness, loss of sensation and sometimes total paralysis. The origin of this disorder has been associated with immune responses triggered by post-infection with Campylobacter spp. However, when there is no obvious cause of the disease, it is usually not investigated due to the greater interest in the treatment. Therefore, most cases are reported as idiopathic origin. Between January and March 2016 worldwide, GBS outbreaks were reported in 8 countries, linked to the emergence of the Zika virus. In Peru, since the end of 2018, outbreaks of GBS have been reported more frequently and although no association with Zika has been confirmed, the increase in cases, the geographical extension where they occurred and the clinical characteristics of affected patients, have common patterns that lead to suspect an infectious origin mainly of viral type. Therefore, it is important to know the current scientific evidence about the role that some viruses play in this syndrome, allowing us to expand our epidemiological picture with new tools to address this disease

Teaching Rapid Assessment Skills in Triage for the Emergency Medicine Clerkship.

BACKGROUND: Rapidly assessing an undifferentiated patient and developing a gestalt for "sick vs. not sick" is a core component of emergency medicine (EM). Developing this skill requires clinical experience and pattern recognition, which can be difficult to attain during a typical EM clerkship. OBJECTIVE: We developed a novel approach to teaching medical students rapid assessment skills in the emergency department (ED) by implementing a teaching shift in triage. METHODS: Fourth-year medical students in our EM clerkship in fall 2019 were scheduled one shift in triage with a dedicated teaching attending. The students evaluated patients under direct supervision, discussed their immediate differential diagnosis, and proposed an initial workup. The attending gave real-time feedback using a standardized direct observation tool. Students completed an electronic pre and post survey (5-point Likert scale) to assess their comfort level in the following areas: performing a rapid triage assessment, determining "sick vs. not sick", performing a focused physical examination, developing a targeted differential diagnosis, and ordering an initial diagnostic workup. RESULTS: Twenty-one students participated in the triage shifts. There was a significant improvement in self-assessed comfort with performing a rapid triage assessment, mean pre 2.76 and post 4.43 (p < 0.0001). There were also significant improvements in the four other survey areas (p < 0.004 or less). CONCLUSIONS: A teaching shift in triage can increase medical students' self-assessed rapid assessment skills for patients in the ED. Benefits to the teaching attending included the opportunity to perform direct observation, give real-time feedback, and identify real-time teaching moments.

Can the banana weevil Cosmopolites sordidus be a vector of Fusarium oxysporum f.sp. cubense race 1? Unravelling the internal and external acquisition of effective inoculum.

BACKGROUND: With the undergoing world outbreak of Fusarium wilt of bananas, it is essential to unravel all the possible process of dissemination of this disease. The host-pest interactions of the banana weevil with banana plants make this insect an important potential vector. This study, carried out in controlled conditions, explores the interaction between the banana weevil and Fusarium oxysporum f.sp. cubense race 1 (Foc), with a focus on the external and internal transport of viable fungal propagules. RESULTS: Viable inoculum of Foc was detected very rapidly on external teguments and in the digestive tract of the insect, i.e. at the lowest time studied of 5 min after contact with infected pseudostems. Maximal inoculum acquisition occurred after 1 h contact with an inoculum source. External inoculum was higher than the inoculum present in the digestive tract, but external and internal inoculum had the same dynamics. After a contact of an infected source, external and internal inoculum decreased exponentially within 50 h, but weevils remained infested for a long time, as long as 2 or 3 days that would be enough for inoculum dispersal. Viable inoculum was also detected in feces. Foc strains isolated were pathogenic when inoculated to banana plants of the Gros Michel variety but did not provoke any symptom on Cavendish banana plants. CONCLUSION: These results demonstrate that the infective structures of Foc remain externally viable in the digestive system and the excreta of the banana weevil. Such excreta are capable of making healthy banana plants of the Gros Michel variety. © 2021 Society of Chemical Industry.

Survey of gastrointestinal parasites, liver flukes and lungworm in feces from dairy cattle in the high tropics of Antioquia, Colombia.

A cross sectional study was undertaken to determine the prevalence and intensity of parasitic infections in dairy cattle in the high tropics of Colombia. A total of 1003 rectal samples were collected from dairy cows at 29 farms between May and June 2014 to represent the number of farms, age groups, and size of the 65,000-cow population in the municipality of San Pedro de los Milagros. Coprological techniques were used to detect gastrointestinal nematodes, liver flukes, coccidian oocysts, and first larval stage counts of Dictyocaulus viviparus. In order of decreasing prevalence, the following parasites were detected: coccidial oocyst (36.7%; 95% CIs, 31.6-42.7), strongyle nematodes (31.6%, 27.8-35.4), liver flukes (30.9%, 21.5-37.5), cestodes (8.4%, 7.1-9.7), and D. viviparus (5.4%, 3.4-7.5). Co-infections by all possible combinations of the three most predominant groups occurred in 11 to 15% of the animals. There were significant differences in infection rates between age groups, with higher risk of liver fluke infection in animals older than 1 year of age (odds ratio (OR) = 3.2), but lower presence for coccidia and strongyles (OR = 0.19 and 0.51, respectively). For Fasciola hepatica, within-herd prevalences of > 25% in 16 farms and 94 of 281 (33.5%) animals with > 5 eggs per gram (epg) indicate that significant production losses are likely occurring. The variation in the prevalence of gastrointestinal parasites and liver flukes, together with the level of infection among age groups, could be used in integrated management programs to establish selective anthelmintic treatments and select for heritable traits of host resistance. These results serve as a baseline for future studies to determine the success of control measures and should increase awareness that subclinical parasitism is widespread in the livestock sector.

Efficient transformation of Mycosphaerella fijiensis by underwater shock waves.

Black leaf streak disease, also known as black Sigatoka, causes dramatic losses in production of banana and plantains fruits. The disease is caused by the pathogenic fungus Mycosphaerella fijiensis (anamorph Pseudocercospora fijiensis; Mycosphaerellaceae). Genetic transformation of M. fijiensis would allow a better understanding of molecular basis of pathogenicity and design novel approaches to control the infection caused by this pathogen. However, transformation of this fungus has not been easy. We report here a protocol for genetic transformation of M. fijiensis employing underwater shock waves and intact conidia. The recombinant strains recovered showed genetic stability over >10 generations. The frequency of transformation obtained was between 75 and 150 times higher than the efficiency reported in the only article published on transformation of M. fijiensis using spheroplasts. This improvement allowed the use of a thousand times less cells than the amount employed before, avoiding the need for cumbersome successive batch cultures. Our protocol is simple, highly efficient, fast and reproducible and together with the available genomes of M. fijiensis and Musa acuminata, it offers new possibilities to study the diverse mechanisms of pathogenesis of the fungus.

Comparative analysis of the in vitro and in planta secretomes from Mycosphaerella fijiensis isolates.

Black Sigatoka, a devastating disease of bananas and plantains worldwide, is caused by the fungus Mycosphaerella fijiensis. Several banana cultivars such as 'Yangambi Km 5' and Calcutta IV, have been known to be resistant to the fungus, but the resistance has been broken in 'Yangambi Km 5' in Costa Rica. Since the resistance of this variety still persists in Mexico, the aim of this study was to compare the in vitro and in planta secretomes from two avirulent and virulent M. fijiensis isolates using proteomics and bioinformatics approaches. We aimed to identify differentially expressed proteins in fungal isolates that differ in pathogenicity and that might be responsible for breaking the resistance in 'Yangambi Km 5'. We were able to identify 90 protein spots in the secretomes of fungal isolates encoding 42 unique proteins and 35 differential spots between them. Proteins involved in carbohydrate transport and metabolism were more prevalent. Several proteases, pathogenicity-related, ROS detoxification and unknown proteins were also highly or specifically expressed by the virulent isolate in vitro or during in planta infection. An unknown protein representing a virulence factor candidate was also identified. These results demonstrated that the secretome reflects major differences between both M. fijiensis isolates.

Descripción de un nuevo concepto en el campo de la neuropsicología: Estado premórbido de la cognición / Description of a new concept in the field of neuropsychology: Premorbid state of cognition

Los numerosos trabajos presentados a lo largo de la historia en la literatura nosológica de los estados demenciales dan cuenta de diagnósticos diferenciales siguiendo criterios relativamente precisos para cada tipo de enfermedad demencial. Se establecieron criterios para los deterioros cognitivos mínimos que en la mayoría de los casos evolucionan hacia una demencia. Este trabajo pretende realizar un recorrido por distintos autores haciendo referencia a los estados de salud mental en sujetos añosos, como así también realizar un recorrido por la nosología del deterioro cognitivo mínimo. El propósito es esbozar, en un cuadro nomenclador, un nuevo concepto de un estadio de cognición: “estado premórbido de la cognición” que obraría de bisagra entre los estados saludables y los patológicos en los sujetos añosos. Dicho estado de la cognición posee factores de riesgo significativos que están en la base de un posible deterioro cognoscitivo, los cuales no son detectados por las pruebas neuropsicológicas, ni tampoco por los análisis clínicos incluyendo las neuroimágenes, a pesar de poseer una connotación subjetiva en el individuo y su familia, que en cierta medida perturba la vida cotidiana. Finalmente se esboza un posible tratamiento no farmacológico (taller de estimulación cognitiva) con el objeto de retrasar el posible deterioro y mejorar la calidad de vida.

Descripción de un nuevo concepto en el campo de la neuropsicología: Estado premórbido de la cognición / Description of a new concept in the field of neuropsychology: Premorbid state of cognition

Los numerosos trabajos presentados a lo largo de la historia en la literatura nosológica de los estados demenciales dan cuenta de diagnósticos diferenciales siguiendo criterios relativamente precisos para cada tipo de enfermedad demencial. Se establecieron criterios para los deterioros cognitivos mínimos que en la mayoría de los casos evolucionan hacia una demencia. Este trabajo pretende realizar un recorrido por distintos autores haciendo referencia a los estados de salud mental en sujetos añosos, como así también realizar un recorrido por la nosología del deterioro cognitivo mínimo. El propósito es esbozar, en un cuadro nomenclador, un nuevo concepto de un estadio de cognición: ôestado premórbido de la cogniciónö que obraría de bisagra entre los estados saludables y los patológicos en los sujetos añosos. Dicho estado de la cognición posee factores de riesgo significativos que están en la base de un posible deterioro cognoscitivo, los cuales no son detectados por las pruebas neuropsicológicas, ni tampoco por los análisis clínicos incluyendo las neuroimágenes, a pesar de poseer una connotación subjetiva en el individuo y su familia, que en cierta medida perturba la vida cotidiana. Finalmente se esboza un posible tratamiento no farmacológico (taller de estimulación cognitiva) con el objeto de retrasar el posible deterioro y mejorar la calidad de vida.(AU)

Inaccuracy of the global assessment score in the emergency medicine standard letter of recommendation.

OBJECTIVES: The standard letter of recommendation (SLOR) is used by most emergency medicine (EM) faculty to submit evaluations for medical students applying for EM residency programs. In the global assessment score (GAS) section, there is a crucial summative question that asks letter writers to estimate the applicant's rank order list (ROL) position in their own program. The primary aim of the study was to determine if these estimated global assessment tiers agreed with the actual ROL, using the criteria recommended by the Council of Emergency Medicine Residency Directors (CORD). METHODS: Data from SLORs written by EM faculty from five California institutions were retrospectively collected from the 2008-2009 residency application year. Descriptive and comparative statistical analyses were performed using the documented GAS tiers and actual ROL positions. RESULTS: A total of 105 SLORs were reviewed from the five participating institutions. Three SLORs were excluded and 102 were analyzed. Only 27 (26%) SLORs documented a GAS tier that accurately predicted the applicant's actual ROL position. The GAS tier overestimated the applicant's position on the ROL in 67 (66%) SLORs, whereas it underestimated the position in eight (8%) SLORs. Accuracy was poor regardless of the number of letter writers on the SLOR (p = 0.890), the writer's administrative title (p = 0.326), whether the student was a home or visiting student (p = 0.801), or if the student had prior EM rotation experience (p = 0.793). CONCLUSIONS: Standard letter of recommendation writers are inaccurate in estimating the ROL position of the applicant using the GAS tier criteria. The GAS tiers were accurate only 26% of the time. Because of the valuable role that the SLOR plays in determining an applicant's competitiveness in the National Resident Matching Program (NRMP) in EM, future discussion should focus on improving the consistency and accuracy of the GAS section. Furthermore, there needs to be a national dialogue to reassess the utility of the criterion-based GAS within the SLOR.

Wheel-shaped Cu(20)-tungstophosphate [Cu(20)X(OH)(24)(H(2)O)(12)(P(8)W(48)O(184))](25-) ion (X = Cl, Br, I) and the role of the halide guest.

We have synthesized the known [Cu(20)Cl(OH)(24)(H(2)O)(12)(P(8)W(48)O(184))](25-) (1) and report here its bromide and iodide analogues, [Cu(20)Br(OH)(24)(H(2)O)(12)(P(8)W(48)O(184))](25-) (2) and [Cu(20)I(OH)(24)(H(2)O)(12)(P(8)W(48)O(184))](25-) (3). These polyanions were characterized in the solid state by IR spectroscopy and single-crystal X-ray diffraction. Magnetic susceptibility and magnetization data over 1.8-300 K show that the Cu(2+) ions in 1-2 are antiferromagnetically coupled, leading to a diamagnetic ground state. The effective exchange coupling constant J(eff) was estimated as approximately -3 K for both 1 and 2. Electron paramagnetic resonance measurements were made on 1 and 2 over 5-295 K at microwave frequencies of 9.5, 34, and 220 GHz. The observed (weak) signals were characteristic of randomly distributed Cu(2+) ions only, with g values and hyperfine constants typical of the unpaired electron in a 3d(x(2)-y(2)) orbital of Cu(2+). No signals attributable to the copper-hydroxo cluster were detected, supporting the conclusions from the magnetization measurements. DFT calculations were performed as well to obtain additional information on the anionic guest inside the cavity created by the copper-hydroxo cage related to electronic structure and energies of encapsulation. The polyanions 2 and 3 were also characterized by cyclic voltammetry (CV) in a pH 5 medium. Their CVs are composed by an initial two-step reduction of the Cu(2+) centers to Cu(0) through Cu(+), followed at more negative potential by the redox processes of the W centers. A comparison with the CV characteristics of the previously studied compound 1 indicates that the potential locations of the Cu or W waves of the three analogues do not depend significantly upon the identity of the central halide X. This observation is in accordance with conclusions of DFT calculations. The modified electrodes based on 2 and the room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate triggers an efficient reduction of nitrate. To our knowledge, this is the first example of electrocatalytic nitrate reduction by a polyanion entrapped in room-temperature ionic liquid films.

The role of neuroimmunomodulation in Alzheimer's disease.

The idea that alterations in the brain immunomodulation are critical for Alzheimer's disease (AD) pathogenesis provides the most integrative view on this cognitive disorder, considering that converging research lines have revealed the involvement of inflammatory processes in AD. We have proposed the damage signal hypothesis as a unifying scheme in that release of endogenous damage/alarm signals, in response to accumulated cell distress (dyslipidemia, vascular insults, head injury, oxidative stress, iron overload, folate deficiency), is the earliest triggering event in AD, leading to activation of innate immunity and the inflammatory cascade. Inflammatory cytokines play a dual role, either promoting neurodegeneration or neuroprotection. This equilibrium is shifted toward the neurodegenerative phenotype upon the action of several risk factors that trigger innate damage signals that activate microglia and the release of tumor necrosis factor-alpha, interleukin-6, and some trophic factors. In this neuroimmunomodulatory hypothesis we integrate different risk factors with microaglial activation and the resulting neuronal alterations and hyperphosphorylations of tau protein. The progression of AD, with slowly increasing damage in brain parenchyma preceding the onset of symptoms, suggests that tissue distress triggering damage signals drives neuroinflammation. These signals via toll-like receptors, receptors for highly glycosylated end products, or other glial receptors activate sensors of the native immune system, inducing the anomalous release of cytokines and promoting the neurodegenerative cascade, a hallmark of brain damage that correlates with cognitive decline.

The damage signals hypothesis of Alzheimer's disease pathogenesis.

Virtually none of the hypotheses on Alzheimer's disease (AD) pathogenesis address the earliest events that trigger the molecular alterations that precede cerebral degeneration and account for the diversity of risk factors that converge on a well-defined disease phenotype. We propose that long-term activation of the innate immune system by an individual array of risk factors constitutes a unifying mechanism leading to the triggering of an inflammatory cascade that converges in cytoskeletal alterations (tau aggregation, paired helical filament formation) as a previously hypothesized final common pathway in AD. The key pathogenic phenomena consist in the long-term, maladaptive activation of innate immunity-triggering receptors--such as the toll-like and advanced glycation end-products receptors, and others located in the microglial membrane--by seemingly heterogeneous risk factors such as hyperlipidemia, hyperglycemia, oxidative stress, head injury, amyloid oligomers, etc. Our hypothesis provides a unifying mechanism that explains both the diversity of risk factors acting over long periods of time and the individual response to such insults. This formulation is amenable to both empirical testing and implementation into therapeutic strategies that may lead to effective prevention of AD as well as other disorders in which impaired regulation of the innate immunity is the unifying cause of the condition.

Neuroinflammation: implications for the pathogenesis and molecular diagnosis of Alzheimer's disease.

During the past few years, an increasing set of evidence has supported the major role of deregulation of the interaction patterns between glial cells and neurons in the pathway toward neuronal degeneration. Neurons and glial cells, together with brain vessels, constitute an integrated system for brain function. Inflammation is a process related with the onset of several neurodegenerative disorders, including Alzheimer's disease (AD). Several hypotheses have been postulated to explain the pathogenesis of AD, but none provides insight into the early events that trigger metabolic and cellular alterations in neuronal degeneration. The amyloid hypothesis was sustained on the basis that Abeta-peptide deposition into senile plaques is responsible for neurodegeneration. However, recent findings point to Abeta oligomers as responsible for synaptic impairment in neuronal degeneration. Amyloid is only one among many other major factors affecting the quality of neuronal cells. Another explanation derives from the tau hypothesis, supported by the observations that tau hyperphosphorylations constitute a common feature of most of the altered signaling pathways in degenerating neurons. Altered tau patterns have been detected in the cerebrospinal fluids of AD patients, and a close correlation was observed between the levels of hyperphosphorylated tau isoforms and the degree of cognitive impairment. On the other hand, the anomalous effects of cytokines and trophic factors share in common the activation of tau hyperphosphorylation patterns. In this context, a neuroimmunological approach to AD becomes relevant. When glial cells that normally provide neurotrophic factors essential for neurogenesis are activated by a set of stressing events, they overproduce cytokines and NGF, thus triggering altered signaling patterns in the etiopathogenesis of AD. A solid set of discoveries has strengthened the idea that altered patterns in the glia-neuron interactions constitute early molecular events within the cascade of cellular signals that lead to neurodegeneration in AD. A direct correlation has been established between the Abeta-induced neurodegeneration and cytokine production and its subsequent release. In effect, neuroinflammation is responsible for an abnormal secretion of proinflammatory cytokines that trigger signaling pathways that activate brain tau hyperphosphorylation in residues that are not modified under normal physiological conditions. Other cytokines such as IL-3 and TNF-alpha seem to display neuroprotective activities. Elucidation of the events that control the transitions from neuroprotection to neurodegeneration should be a critical point toward elucidation of AD pathogenesis.

Polyoxometalates with internal cavities: redox activity, basicity, and cation encapsulation in [Xn+P5W30O110](15-n)- Preyssler complexes, with X = Na+, Ca2+, Y3+, La3+, Ce3+, and Th4+.

The Preyssler anion, of general formula [Xn+P5W30O110](15-n)-, is the smallest polyoxometalate (POM) with an internal cavity allowing cation exchange with the solution. The Preyssler anion features a rich chemistry evidenced by its ability to accept electrons at low potentials, to selectively capture various metal cations, and to undergo acid-base reactions. A deep understanding of these topics is herein provided by means of DFT calculations on the title series of compounds. We evaluate the energetics of the release/encapsulation process for several Xn+ cations and identify the effect of the encapsulated ion on the properties of the Preyssler anion. We revisit the relationship between the internal cation charge and the electrochemical behavior of the POM. A linear dependence between the first one-electron reduction energies and the encapsulated Xn+ charge is found, with a slope of 48 mV per unit charge. The protonation also shifts the reduction potential to more positive values, but the effect is much larger. In connection to this, the last proton's pKa = 2 for the Na+ derivative was estimated to be in reasonable agreement with experiment. The electronic structure of lanthanide derivatives is more complex than conventional POM structures. The reduction energy for the CeIV-Preyssler + 1e- --> CeIII-Preyssler process was computed to be more exothermic than that of very oxidant species such as S2Mo18O624-.

Variables asociadas con la presentación de carne PSE (Pálida, Suave, Exudativa) en canales de cerdo / Variables associated PSE (Pale, Soft, Exudative) to meat in porcine carcasses

La presencia de la condición PSE (pálida, suave, exudativa) en canales porcinas causa altas pérdidas económicas a la industria cárnica y según estudios presenta asociación con muchas variables. Para analizarlas se muestrearon 474 canales de cerdos comerciales y se les midió el pH (pHmetro IQ 200 Scientific Instruments®, con sonda de silicio tipo ISFET®) a 45 minutos (pH45) y a 24 horas post-sacrificio en el músculo semimembranoso. Las variables analizadas fueron genética, sexo, alimento, tiempo de ayuno, peso vivo; duración del transporte, densidad, temperatura y humedad relativa durante el transporte; tipo de camión, tiempo de reposo, grasa dorsal, rendimiento en canal y mermas. En el análisis estadístico se aplicó la técnica de componentes principales, GLM con prueba de contraste de Tukey con un 95% de significancia, y distribución de frecuencias univariada y bivariada. Los resultados demuestran que hubo asociación altamente significativa (p<0.01) entre el pH45 y la densidad, alimento, camión, genética y reposo; el sexo y el tiempo de transporte tuvieron asociación significativa (p<0.05). Se encontró diferencia entre los tipos de genética, entre los sexos y entre los tipos de alimento (p<0.05). Se presentaron las interacciones sexo-ayuno, sexo-alimento, sexo-reposo y sexo-transporte (p<0.05). Esto indica que la condición PSE no es unicausal y como tal debe ser manejada.

The presence of the PSE (pale, soft and exudative) condition in porcine carcass causes high economic losses to the meat industry. The PSE appearance depends on many variables, some of which are intrinsic of the animal, and others are related to transportation conditions to the slaughterhouse. The aim of the present study was to determine if there is or not an association between some of the above mentioned variables and the PSE condition. The studied variables were: genetic, sex, food, weight, time of fasting, time of transportation, density, temperature and humidity during transportation, type of truck, resting time, dorsal fat, carcass efficiency and carcass weight losses. Carcasses of commercial genetic pigs (n = 474) were tested and semimembranous muscle pH was done at 45 minutes (pH45 ) and then at 24 h post-sacrifice, using IQ 200 Scientific Instruments®, with an ISFET® type probe. Test of principal components of GLM with contrast test of Tukey with 95% of significance, and univariate and divariate frequencies distribution was applied. The results demonstrate that there was highly significant association (p<0.01) between pH45 and variables as density, food, type of truck, genetic and the resting time. The sex and the time of transportation also had significant association (p<0.05), but only with pH45 . Additionally, differences between genetic, sex (highest values of pH45 to males) and food (p<0.05) were found. Also, there were interactions between: sex - fasting, sex - food, sex - resting and sex - transportation (p<0.05). According to the results, PSE condition is not a unicausal phenomenon and consequently it needs an integral managment.

Density functional theory and ab initio study of electronic and electrochemistry properties of the tetranuclear sandwich complex [FeIII4(H2O)2(PW9O34)2]6-.

Quantum chemistry calculations have been performed to unravel the electronic and electrochemical properties of a FeIII-sandwich polyoxometalate. Using a combination of methods, it is shown that in these clusters the first reduction occurs in the so-called external Fe, which is bonded to a water ligand. Calculations also show that the electron reductions are coupled with protonation processes, in full agreement with existing experimental results.