Comparative study of extracellular recording methods for analysis of afferent sensory information: Empirical modeling, data analysis and interpretation.

BACKGROUND: Physiological studies of sensorial systems often require the acquisition and processing of data extracted from their multiple components to evaluate how the neural information changes in relation to the environment changes. In this work, a comparative study about methodological aspects of two electrophysiological approaches is described. NEW METHOD: Extracellular recordings from deep vibrissal nerves were obtained by using a customized microelectrode Utah array during passive mechanical stimulation of rat´s whiskers. These recordings were compared with those obtained with bipolar electrodes. We also propose here a simplified empirical model of the electrophysiological activity obtained from a bundle of myelinated nerve fibers. RESULTS: The peripheral activity of the vibrissal system was characterized through the temporal and spectral features obtained with both recording methods. The empirical model not only allows the correlation between anatomical structures and functional features, but also allows to predict changes in the CAPs morphology when the arrangement and the geometry of the electrodes changes. COMPARISON WITH EXISTING METHOD(S): This study compares two extracellular recording methods based on analysis techniques, empirical modeling and data processing of vibrissal sensory information. CONCLUSIONS: This comparative study reveals a close relationship between the electrophysiological techniques and the processing methods necessary to extract sensory information. This relationship is the result of maximizing the extraction of information from recordings of sensory activity.

Time-frequency analysis of neuronal populations with instantaneous resolution based on noise-assisted multivariate empirical mode decomposition.

BACKGROUND: Linear analysis has classically provided powerful tools for understanding the behavior of neural populations, but the neuron responses to real-world stimulation are nonlinear under some conditions, and many neuronal components demonstrate strong nonlinear behavior. In spite of this, temporal and frequency dynamics of neural populations to sensory stimulation have been usually analyzed with linear approaches. NEW METHOD: In this paper, we propose the use of Noise-Assisted Multivariate Empirical Mode Decomposition (NA-MEMD), a data-driven template-free algorithm, plus the Hilbert transform as a suitable tool for analyzing population oscillatory dynamics in a multi-dimensional space with instantaneous frequency (IF) resolution. RESULTS: The proposed approach was able to extract oscillatory information of neurophysiological data of deep vibrissal nerve and visual cortex multiunit recordings that were not evidenced using linear approaches with fixed bases such as the Fourier analysis. COMPARISON WITH EXISTING METHODS: Texture discrimination analysis performance was increased when Noise-Assisted Multivariate Empirical Mode plus Hilbert transform was implemented, compared to linear techniques. Cortical oscillatory population activity was analyzed with precise time-frequency resolution. Similarly, NA-MEMD provided increased time-frequency resolution of cortical oscillatory population activity. CONCLUSIONS: Noise-Assisted Multivariate Empirical Mode Decomposition plus Hilbert transform is an improved method to analyze neuronal population oscillatory dynamics overcoming linear and stationary assumptions of classical methods.

Medicamentos de diagnóstico hospitalario: oportunidad de colaboración entre farmacia hospitalaria y comunitaria / Hospital diagnosis drugs: an opportunity for collaboration between hospital and community pharmacy

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Cirugía menor en un centro de salud familiar y concordancia clínico patológica / Minor surgery in a family health center and clinicopathological concordance

INTRODUCCIÓN: Los servicios de Atención Primaria de Salud(APS) realizan Cirugía Menor(CM), evidenciándose beneficios como optimización de recursos y promoción de la actividad preventiva, diagnóstica y terapéutica. OBJETIVO: Describir la actividad de CM en un centro de APS y analizar la concordancia clínica-patológica de las lesiones...

INTRODUCTION: Primary Health Care (PHM) services perform minor surgery (MS), displaying benefits such as resource optimization and the promotion of preventive, diagnostic and therapeutic activities. OBJECTIVE: Describe the MS activity from a PHM center and analyse the clinicopathological concordance of the lesions…

The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests.

• We present the results from a litter translocation experiment along a 2800-m elevation gradient in Peruvian tropical forests. The understanding of the environmental factors controlling litter decomposition is important in the description of the carbon and nutrient cycles of tropical ecosystems, and in predicting their response to long-term increases in temperature. • Samples of litter from 15 species were transplanted across all five sites in the study, and decomposition was tracked over 448 d. • Species' type had a large influence on the decomposition rate (k), most probably through its influence on leaf quality and morphology. When samples were pooled across species and elevations, soil temperature explained 95% of the variation in the decomposition rate, but no direct relationship was observed with either soil moisture or rainfall. The sensitivity of the decay rate to temperature (κ(T)) varied seven-fold across species, between 0.024 and 0.169 °C⁻¹, with a mean value of 0.118 ± 0.009 °C⁻¹ (SE). This is equivalent to a temperature sensitivity parameter (Q10) for litter decay of 3.06 ± 0.28, higher than that frequently assumed for heterotrophic processes. • Our results suggest that the warming of approx. 0.9 °C experienced in the region in recent decades may have increased decomposition and nutrient mineralization rates by c. 10%.

Use of monoclonal antibodies for the identification of Leishmania spp. isolated from humans and wild rodents in the State of Campeche, Mexico.

The genus Leishmania includes 30 described species which infect a wide variety of mammalian hosts. The precise identification of leishmanial parasites at the species level is very important in order to determine whether an organism, causing the disease in a given area, is of the same biotype as that found in suspected mammalian reservoirs. The objectives of the present study were (1) to identify leishmanial parasites isolated from humans and wild rodents from the State of Campeche, an endemic focus of localized cutaneous leishmaniasis (LCL) in southern Mexico, using an indirect immunofluorescent assay (IFA) with monoclonal antibodies (Mabs); and (2) to determine if the parasites of the two types of hosts were of the same biotype. All the wild rodents (six Ototylomys phyllotis, eight Oryzomys melanotis, five Peromyscus yucatanicus and two Sigmodon hispidus) and 96% (24/25) of the human isolates were identified as Leishmania (L.) mexicana confirming that this specific LCL focus is a wild zoonosis. The presence of one human isolate of L. (Viannia) braziliensis in the State of Campeche, confirmed the importance of an accurate taxonomic identification at species level.

[CHRONIC DIARRHEA OF INFECTIOUS ETIOLOGY] / La Diarrea Crónica de Etiología Infecciosa.

Chronic Diarrhea syndrome is due to several causes. In LatinAmericen countries, infectious and parasitic etiology is frequent. Withinthese infections, the following has been determined: parasitic and enterobacterial agents, overpopulation of bacteria syndrome in the upper small bowel (SOBIA, abbreviation for Síndrome de Sobrepoblación Bacteriana del Intestino Delgado Alto), intestinal TBC, and AIDS. In these processes, the precipitating factor may be unique or multifactor; or there could also exist a tendency towards pathologies for these infections. There has been evidence of SOBIA cases without associated factor in Latin American countries. A study made in Peru shows SOBIA cases in 30 percent of chronic diarrhea.In chronic diarrhea cases, and even more, in those diarrheas of infectiousetiology, a complete study should be made, considering the several factorsthat generate diarrhea in a same one case, such as the mechanisms ofimmunodeficiency, neurological, endocrinemetabolic, and others associated with intestinal infections. This approach will be helpful to make a complete diagnosis and apply timely treatment.

Characterization of the tobacco glycoprotein surface binding property of heart and skeletal muscle cells. I. Modulation of the heart cell membrane TGP interaction by anti-TGP IgG.

Monolayers of L6 rat skeletal myoblast cells formed surface binding isotherms with the purified tobacco leaf glycoprotein TGP1 and the enriched cigarette tar glycoprotein TGP2. Scatchard analysis showed that the binding in the range of the limited concentrations tested was to a single class molecule and the calculated affinity constant (Kd) for TGP1 and TGP2 showed similar values (9.78 x 10(-13) M and 3.09 x 10(-13) M, respectively). The bound TGPs were almost totally displaced by excess nonradiolabeled molecules. The calculated Bmax of the L6 myoblast monolayer was 2.93 fmol for TGP1 and 0.217 fmol for TGP2 per 32.2 mm2. Guinea pig heart sarcolemma binding isotherms were also formed with radiolabeled TGP1 and TGP2. The interaction of tobacco leaf TGP1 with the heart cell membranes was irreversible because only 15-20% of the bound TGP1 was displaced by 100-fold, non-labeled molecules but the interaction of tar TGP2 with heart sarcolemma was reversible and probably saturable. The heart sarcolemma TGP2 affinity constant (Kd) was 5.88 x 10(-7) M and the Bmax, 2.45 x 10(-8) M per 12.5 micrograms sarcolemma. Pretreatment of heart sarcolemma with increasing concentrations of leaf TGP1 did not displace tar TGP2 binding but its absorption on the membrane resulted in increased TGP2 sarcolemma attachment by a complex and unexplained mechanism. Increasing concentrations of the sera of 10 of 15 guinea pigs (67%) that received mainstream emissions of tobacco smoke from a University of Kentucky cigarette smoking machine for 152 days, displaced cigarette tar TGP2 heart cell sarcolemma attachment and this inhibition was significantly different from that produced by the sera of sham smoked and of non-exposed animals (Mann-Whitney test, p = 0.0082). Staphylococcus protein A inhibited the displacement of TGP2 produced by the sera of cigarette smoke exposed guinea pigs and this observation indicated that this action was mediated by IgG molecules. The specific immunoprecipitation of a radiolabeled surface epitope of the L6 myoblast monolayers pretreated with TGP1 or TGP2 by immune IgG against TGP2 and by the IgG of an antiserum against standard TGP showed that the tobacco glycoproteins attached to a unit polypeptide of the plasma membrane of the muscle cells of approximately 76 kDa. These data support the notion that TGP molecules in cigarette smoke are absorbed systemically on smoking and may have a direct toxic effect when they attach to the surface TGP binding proteins of heart and skeletal muscle cells.

Induction of allograft tolerance in rats by an HLA class-I-derived peptide and cyclosporine A.

T cell recognition of MHC molecules initiates a cascade of events resulting in allograft rejection. CTLs damage the graft by targeting nonself-MHC class I molecules. We and others have previously shown that small synthetic peptides corresponding to regions of certain MHC class I molecules can inhibit the CTL response against MHC class I alloantigens in vitro. Here we report that rat heart allografts survived survived indefinitely when transplanted into recipients treated with a synthetic peptide corresponding to residues 75-84 of (B7.75-84) in combination with a subtherapeutic dose of cyclosporine A. Furthermore, this treatment induced long-term donor-specific tolerance that was mediated by anergic cells, indicating that such peptides may have potential as therapeutics for human organ transplantation.

Estudio clínico y etiológico de 90 casos de diarrea crónica / Clinical and ethiologic study of 90 cases of chronic diarrhea

Se realizó el presente estudio prospectivo en 90 pacientes con diarrea crónica, atendidos en la consulta externa de una clínica privada de Lima, durante los años 1990 y 1991. De acuerdo a un esquema metodológico para llegar a los factores causales y/o enfermedades generadoras de la diarrea crónica. En todos los casos se practicaron exámenes hematológicos, bioquímicos, coprocultivos, coproparasitológico, radiografías de torax y tránsito intestinal. En 11, el cultivo de contenido duodenal. Radigrafías del colon en 25 casos; proctosigmoidoscopias en 14 y endoscopía digestiva alta en 19 pacientes. Ecografías abdomnales en 12 y TAC en 2 casos. Los resultados finales mostraron como enfermedades determinantes de la diarrea crónica, por orden de frecuencia, enteroparasitosis ( 23.3 por ciento ), trastornos funcionales digestivos ( 20.0 por ciento ), sobrepoblación bacteriana intestinal ( 15.5 por ciento ), de causa no determinada ( 8.8 por ciento ), divertículos del colon ( 7.7 por ciento ), infección intestinal ( 7.7 por ciento ) comprobada y probable ( 5.5 por ciento ), intolerancia a la lactosa ( 3.3 por ciento ), diabetes mellitus ( 2.2 por ciento ); y un caso ( 1.1 por ciento ) las siguientes: linfoma intestinal, tumor de páncreas, SIDA, deformación colónica y anemia megaloblástica. Las causas de diarrea crónica son variadas y multifactoriales, y en presente estudio se comprueba la predominancia de las parasitosis intestinales, transtornos funcionales y sobrepoblación bacteriana intestinal; y en menor frecuencia otras patologías variadas