Access of Quaternary Ammonium Blockers to the Internal Pore of Cyclic Nucleotide-gated Channels: Implications for the Location of the Gate

Cyclic nucleotide-gated (CNG) channels play important roles in the transduction of visual and olfactory information by sensing changes in the intracellular concentration of cyclic nucleotides. We have investigated the interactions between intracellularly applied quaternary ammonium (QA) ions and the α subunit of rod cyclic nucleotide-gated channels. We have used a family of alkyl-triethylammonium derivatives in which the length of one chain is altered. These QA derivatives blocked the permeation pathway of CNG channels in a concentration- and voltage-dependent manner. For QA compounds with tails longer than six methylene groups, increasing the length of the chain resulted in higher apparent affinities of ∼1.2 RT per methylene group added, which is consistent with the presence of a hydrophobic pocket within the intracellular mouth of the channel that serves as part of the receptor binding site. At the single channel level, decyltriethyl ammonium (C10-TEA) ions did not change the unitary conductance but they did reduce the apparent mean open time, suggesting that the blocker binds to open channels. We provide four lines of evidence suggesting that QA ions can also bind to closed channels: (1) the extent of C10-TEA blockade at subsaturating [cGMP] was larger than at saturating agonist concentration, (2) under saturating concentrations of cGMP, cIMP, or cAMP, blockade levels were inversely correlated with the maximal probability of opening achieved by each agonist, (3) in the closed state, MTS reagents of comparable sizes to QA ions were able to modify V391C in the inner vestibule of the channel, and (4) in the closed state, C10-TEA was able to slow the Cd2+ inhibition observed in V391C channels. These results are in stark contrast to the well-established QA blockade mechanism in Kv channels, where these compounds can only access the inner vestibule in the open state because the gate that opens and closes the channel is located cytoplasmically with respect to the binding site of QA ions. Therefore, in the context of Kv channels, our observations suggest that the regions involved in opening and closing the permeation pathways in these two types of channels are different

Constitutional Confidentiality

Federal Certificates of Confidentiality (“Certificates”) protect sensitive information about human research subjects from disclosure and use in judicial, administrative, and legislative proceedings at both the state and federal levels. When they were first authorized by Congress in the 1970s, Certificates covered sensitive information collected in research about drug addiction use. Today, however, they extend to virtually all personal information gathered by biomedical research studies. The broad reach of Certificates, coupled with their power to override state subpoenas and warrants issued in the context of law enforcement, abortion regulation, and other police powers typically under state control, beg the question whether Certificates are constitutional. This Article, for the first time, examines the fundamental constitutional underpinnings of Certificates and situates them within the context of federal statutory privilege law. In so doing, it makes several contributions to the existing literature. First, after a brief background about Certificates and other congressional action relating to biomedical research, this Article argues that the Certificate statute creates a federal statutory privilege. To date, the language of privilege has been wholly absent from discussions of Certificates and their reach. Yet understanding the Certificate as a privilege provides well understood nomenclature and legal principles for applying the Certificate statute. Second, this Article locates the primary constitutional authority undergirding the Certificate statute in the Commerce Clause. Third, this Article argues that Congress’s power to tax and spend provides further constitutional grounding for Certificates, at least with respect to federally-funded researchers and institutions. For both bases of constitutional authority, this Article maps new territory, yielding clarity where there has previously been uncertainty. Fourth, this Article brings together constitutional doctrines limiting both congressional power and evidentiary privileges to illuminate how these doctrines may require Certificate protections to give way in exceptional cases. In so doing, it bridges traditional constitutional law and evidence law, reaping insights from their intersection from which scholars in both fields may benefit. Finally, this Article considers the implications of this constitutional analysis not only on Certificates, but also on congressional action aimed at regulating human subjects research more generally and on the law surrounding federal statutory privileges

Estado periodontal y microbiota subgingival en mujeres preeclámpticas.

Objetivos: Describir el estado periodontal y la microbiota subgingival de mujeres gestantes con diagnostico de preeclampsia en el Hospital Universitario del Valle (HUV) de Cali-Colombia. Metodología: Participaron 81 mujeres con diagnóstico de preeclampsia, internadas en el Hospital Universitario del Valle, a quienes se les colectaron datos médicos y periodontales tales como profundidad al sondeo, nivel de inserción clínica, índice gingival y periodontal, con el fin de realizar el diagnóstico clínico periodontal teniendo en cuenta los parámetros de la Academia Americana de Periodoncia (AAP 1999); además se tomaron muestras microbiológicas subgingivales para cultivo e identificación de bacterias periodontopatógenas. Resultados: El 63 de la gestantes presentó preeclampsia leve y el 27.2 preeclampsia severa. Un 91.4 (n=74) de las pacientes presentó afección en el estado de salud periodontal dentro del cual el 59.3 (n=48) presentó un diagnóstico de periodontitis crónica y solo el 8.6 de las gestantes presentó un buen estado de salud periodontal. Los microorganismos periodontopáticos más frecuentes en las mujeres con preeclampsia fueron Fusobacterium ssp 80.2 (n=65), Porphyromonas gingivalis 59.3 (n = 48) y Prevotella intermedian/nigrescens 51.9 (n=42). Conclusiones: Se encontró que una alta proporción de las mujeres con preeclampsia tuvo afección en el estado periodontal con predominio de un diagnostico clínico de periodontitis crónica y presencia de una microbiota periodontopática. Solo un bajo porcentaje de las gestantes presentaron un estado de salud periodontal

Vicuña (Vicugna v. mensalis) herds modify their behaviour after being captured and sheared: implications on conservation and management

Póster presentado al Joint meeting of the 33rd International Ethological Conference (IEC) & the Association for the Study of Animal Behaviour (ASAB), celebrado en Newcastle-Gateshead (UK) del 4 al 8 de agosto de 2013.We present here evidence of a modification in foraging and guarding rates in vicuña herds subject to a traditional shearing management in Central Andes, Perú. The study was conducted from March to December 2011. We recorded behaviour of a vicuña population made up of ca. 300 individuals, living in semi-captive conditions and captured once a year for shearing. We registered foraging and guarding rates of adult males and females as well as calves, and distinguished three periods: before being captured, after being captured for marking and after being captured for shearing. Guarding behaviour is predominantly made by males, it is negatively related to group size, and varies according to the habitat and management period, decreasing significantly after shearing. Foraging behaviour rate is higher in females than in males and lambs, and significantly increases for all individuals after capture and shearing, it is positively related to group size. We hypothesize that after shearing vicuñas are prone to increase their daily foraging rate due to energy demands; this affecting their guarding rate and in turn their vulnerability to predators.Thanks to funding obtained in the Fifth Call for Research in Ecology and Conservation Biology from BBVA Foundation (BIOCON08-059).Peer Reviewe

Block of transmitter release by botulinum C1 actiuon on syntaxin at the squid giant synapse

Electrophysiological, morphological, and biochemical approaches were combined to study the effect of the presynaptic injection of the light chain of botulinum toxin C1 into the squid giant synapse. Presynaptic injection was accompanied by synaptic block that occurred progressively as the toxin filled the presynaptic terminal. Neither the presynaptic action potential nor the Ca2+ currents in the presynaptic terminal were affected by the toxin. Biochemical analysis of syntaxin moiety in squid indicates that the light chain of botulinum toxin C1 lyses syntaxin in vitro, suggesting that this was the mechanism responsible for synaptic block. Ultrastructure of the injected synapses demonstrates an enormous increase in the number of presynaptic vesicles, suggesting that the release rather than the docking of vesicles is affected by biochemical lysing of the syntaxin molecule

Anticuerpos IgG anti-toxoplasma gondii en pacientes con síntomas atribuíbles a toxoplasmosis

6,520 patients with symptoms attributed to toxoplasmosis were evaluated for the prevalence of IgG anti-Toxoplasma gondii, employing the indirect immunofluorescence test. 51.27% of the evaluated proved to be positive. 60.85% of the patients with ocular disorders were seropositive to IgG anti-T.gondii; followed by 56.25% and 48.10% from those with general and gynecobstetric disorders. The symptoms and manifestations which showed the greatest positivity percentages were: asthenia, chorioretinitis, menstrual disorders, cephaleas and uveitis.Se evaluaron 6.520 pacientes con síntomas atribuíbles a toxoplasmosis por la presencia de anticuerpos IgG anti - Toxoplasma gondii mediante la técnica de inmunofluorescencia indirecta. El 51,27% de los evaluados resultaron positivos.El 60,85% de los pacientes con trastornos oculares son seropositivos a IgG anti - T. gondii; seguidos del 56,25 y 48,10% para aquellos con trastornos generales y gineco-obstétricos. Los síntomas o manifestaciones que evidenciaron mayor porcentaje de positividad fueron: astenia, coriorretinitis, trastornos menstruales, cefaleas y uveítis

Variante no reportada del gen THRB en un paciente con resistencia a hormonas tiroideas

Introducción: las variantes en el gen del receptor de hormona tiroidea beta son la principal causa del síndrome de resistencia a las hormonas tiroideas (RHT), donde la herencia es autosómica dominante y se caracteriza por un descenso en la sensibilidad de los tejidos a las hormonas tiroideas, además, las manifestaciones clínicas son variables con síntomas de hiper o de hipotiroidismo. Objetivo: documentar una variante genética potencialmente patogénica del gen      receptor de hormona tiroidea beta relacionada con síndrome de RHT no reportada en la literatura y proporcionar información sobre el abordaje diagnóstico. Presentación del caso: masculino de 43 años con síntomas de hipertiroidismo a quien se le documentaron niveles elevados de T4 libre con una TSH inapropiadamente normal, resonancia magnética de silla turca simple y contrastada sin lesiones en la hipófisis y prueba de estímulo con TRH con respuesta adecuada, indicando un diagnóstico presuntivo de RHT, además, el estudio genético reveló una variante: c.1046_1047insCCTGGT (p.Val349_Ser350insLeuVal) en el gen THR-B, Se procedió al análisis bioinformático de la proteína, indicando ser patogénica con una confianza del 89,4?%. Discusión y conclusión: la sospecha diagnóstica está dada por la discrepancia en los valores de tirotropina, tiroxina y triyodotironina, por lo que realizó un abordaje diagnóstico completo que descartó la interferencia en los ensayos, anormalidades del transporte de las hormonas tiroideas y en la tirotropinoma; la prueba de estímulo con TRH orientó el diagnóstico y la prueba genética su confirmación. Así, reportamos una nueva mutación relacionada con el fenotipo de síndrome resistencia a las hormonas tiroideas, donde este caso demostró la importancia de hacer énfasis en la evaluación genética