Publications by authors named "Merchan M"

Gonadotropin releasing hormone (GnRH) synthesis and secretion regulates seasonal fertility. In the brain, the distribution of GnRH-positive neurons is diffuse, hindering efforts to monitor variations in its cellular and tissue levels. Here, we aim at assessing GnRH immunoreactivity in nuclei responsible for seasonal fertility regulation (SFR) within the posterior, anterior, and preoptic areas of the basal hypothalamus during estrous in ewes.

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This paper presents a novel segmentation algorithm specially developed for applications in 3D point clouds with high variability and noise, particularly suitable for heritage building 3D data. The method can be categorized within the segmentation procedures based on edge detection. In addition, it uses a graph-based topological structure generated from the supervoxelization of the 3D point clouds, which is used to make the closure of the edge points and to define the different segments.

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The auditory cortex is the source of descending connections providing contextual feedback for auditory signal processing at almost all levels of the lemniscal auditory pathway. Such feedback is essential for cognitive processing. It is likely that corticofugal pathways are degraded with aging, becoming important players in age-related hearing loss and, by extension, in cognitive decline.

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Presbycusis or age-related hearing loss (ARHL) is one of the most prevalent chronic health problems facing aging populations. Along the auditory pathway, the stations involved in transmission and processing, function as a system of interconnected feedback loops. Regulating hierarchically auditory processing, auditory cortex (AC) neuromodulation can, accordingly, activate both peripheral and central plasticity after hearing loss.

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Intraspecific phenotypic variability is key to respond to environmental changes and anomalies. However, documenting the emergence of behavioral diversification in natural populations has remained elusive due to the difficulty of observing such a phenomenon at the right time and place. Here, we investigated how the emergence of a new trophic strategy in a population subjected to high fluctuations in the availability of its main trophic resource (migrating songbirds) affected the breeding performance, population structure, and population fitness of a specialized color polymorphic predator, the Eleonora's falcon from the Canary Islands.

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Objectives: The study aims to identify the correlation between human papillomavirus (HPV) infection and sociodemographic and sexual reproductive health factors in Ecuadorian women from March to August 2019.

Methods: 120 women were randomly selected from two gynecological clinics to complete a questionnaire and provide a biospecimen. PCR-Hybridization was used to genotype 37 HPV serotypes in samples obtained by endo-cervical brushing for liquid-based cytology.

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The analysis of the topography of brain neuromodulation following transcranial alternating current (AC) stimulation is relevant for defining strategies directed to specific nuclei stimulation in patients. Among the different procedures of AC stimulation, temporal interference (tTIS) is a novel method for non-invasive neuromodulation of specific deep brain targets. However, little information is currently available about its tissue effects and its activation topography in animal models.

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In this study, we describe in detail the anatomy of nuclei involved in seasonal fertility regulation (SFR) in ewes. For this purpose, the intergeniculate leaflet of the visual thalamus, the caudal hypothalamic arcuate nucleus, and suprachiasmatic, paraventricular and supraoptic nuclei of the rostral hypothalamus were morphometrically and qualitatively analyzed in Nissl-stained serial sections, in the three anatomical planes. In addition, data were collected on calcium-binding proteins and cell phenotypes after immunostaining alternate serial sections for calretinin, parvalbumin and calbindin.

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Biliary drainage for Perihilar Cholangiocarcinoma (PCCA) can be performed either by endoscopic retrograde cholangiopancreatography or Percutaneous Transhepatic Biliary Drainage (PTBD). To date there is no consensus about which method is preferred. Taking that into account, the aim of this study is to compare Endoscopic Biliary Drainage (EBD) versus percutaneous transhepatic biliary drainage in patients with perihilar cholangiocarcinoma through a systematic review and metanalysis.

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Article Synopsis
  • A systematic review and meta-analysis was conducted to evaluate the effectiveness of antibiotic prophylaxis in reducing complications for patients undergoing elective endoscopic retrograde cholangiopancreatography (ERCP).
  • The review included 10 randomized controlled trials with a total of 1757 patients, assessing various outcomes like cholangitis, septicemia, and pancreatitis.
  • Results showed no significant difference in major complications between antibiotic and non-antibiotic groups, but antibiotic prophylaxis did reduce the risk of bacteremia by 7%.
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  • The study investigates how disease-modifying therapies, specifically anti-CD20 treatments and sphingosine 1-phosphate receptor modulators (S1PRM), affect immune responses to SARS-CoV-2 vaccines in patients with multiple sclerosis (MS) and other autoimmune diseases.
  • Researchers enrolled 457 patients and measured both humoral (antibody) and cellular (T-cell) immune responses before and after vaccination, finding that responses varied based on treatment type and duration.
  • Results indicate that while anti-CD20 and S1PRM treatments can reduce antibody responses, anti-CD20 patients may still generate T-cell responses even without detectable antibodies, highlighting the complexities of vaccine response in these populations.
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The reduction of CO emissions and its elimination from the atmosphere has become one of the major problems worldwide, since CO is the main cause of the greenhouse effect and climate change. In recent years, a great number of carbonaceous materials that can be used as CO adsorbents have been synthesized. The strategy is usually to synthesize the materials and determine their adsorption capacity without studying previously the factors that influence this capacity.

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The protective effect of the efferent system against acoustic trauma (AT) has been shown by several experimental approaches, including damage to one ear, sectioning of the olivocochlear bundle (OCB) in the floor of the IV ventricle, and knock-in mice overexpressing outer hair cell (OHC) cholinergic receptors, among others. Such effects have been related to changes in the regulation of the cholinergic efferent system and in cochlear amplification, which ultimately reverse upon protective hearing suppression. In addition to well-known circuits of the brainstem, the descending corticofugal pathway also regulates efferent neurons of the olivary complex.

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Graphene oxide is a derivate of graphene obtained by oxidation of graphite and other carbonaceous materials. The more accepted structure consists in carbonyl and carboxyl groups located at the edge of the graphene network and hydroxyl and epoxy groups attached to the basal plane. The percentage of O-groups depends on the synthesis route and the material used as carbon source.

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Article Synopsis
  • The study investigated how changes in cerebrospinal fluid (CSF) shunt valve settings affect intracranial pressure (ICP) in patients with complex symptoms.
  • A total of 51 patients underwent valve adjustments monitored over 24 hours, revealing that responses to these adjustments varied: 57% showed expected responses, 18% had paradoxical responses, and 24% showed no significant effect on ICP.
  • The findings highlight the occurrence of paradoxical ICP changes post-adjustment, emphasizing the importance of this consideration for future smart shunt technology development.
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We address here the role of oxidation impurities on the structure of graphene oxide films at the air-water interface by specular neutron reflectivity (SNR). We study films of purified graphene oxide (PGO) and nonpurified graphene oxide in the close-packed state. Nonpurified graphene oxide is constituted by graphene oxide (GO) layers with oxidation impurities adsorbed on the basal plane, while in PGO sheets, impurities are eliminated.

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Deafness affects the expression and distribution of voltage-dependent potassium channels (Kvs) of central auditory neurons in the short-term, i.e., hours to days, but the consequences in the expression of Kvs after long-term deafness remain unknown.

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Visual cortex (VC) over-activation analysed by evoked responses has been demonstrated in congenital deafness and after long-term acquired hearing loss in humans. However, permanent hearing deprivation has not yet been explored in animal models. Thus, the present study aimed to examine functional and molecular changes underlying the visual and auditory cross-modal reaction.

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Rat auditory cortex was subjected to 0.1 mA anodal direct current in seven 10-min sessions on alternate days. Based on the well-known auditory cortex control of olivocochlear regulation through corticofugal projections, auditory brainstem responses (ABRs) were recorded as an indirect test of the effectiveness and reversibility of the multisession protocol of epidural stimulation.

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The rat auditory cortex (AC) is becoming popular among auditory neuroscience investigators who are interested in experience-dependence plasticity, auditory perceptual processes, and cortical control of sound processing in the subcortical auditory nuclei. To address new challenges, a procedure to accurately locate and surgically expose the auditory cortex would expedite this research effort. Stereotactic neurosurgery is routinely used in pre-clinical research in animal models to engraft a needle or electrode at a pre-defined location within the auditory cortex.

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Cross-modal reorganization in the auditory and visual cortices has been reported after hearing and visual deficits mostly during the developmental period, possibly underlying sensory compensation mechanisms. However, there are very few data on the existence or nature and timeline of such reorganization events during sensory deficits in adulthood. In this study, we assessed long-term changes in activity-dependent immediate early genes c-Fos and Arc/Arg3.

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The auditory cortex (AC) dynamically regulates responses of the Organ of Corti to sound through descending connections to both the medial (MOC) and lateral (LOC) olivocochlear efferent systems. We have recently provided evidence that AC has a reinforcement role in the responses to sound of the auditory brainstem nuclei. In a molecular level, we have shown that descending inputs from AC are needed to regulate the expression of molecules involved in outer hair cell (OHC) electromotility control, such as prestin and the α10 nicotinic acetylcholine receptor (nAchR).

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Large oceanic sharks represent a suitable model to investigate the influence of a host's oceanic conditions on the structure of its helminth communities. In this study, we describe the intestinal helminth fauna, and investigate determinants of infracommunity structure, in 39 specimens of shortfin mako Isurus oxyrinchus collected in the NE Atlantic. Six cestode species were found in the spiral valve of makos: 3 are typical from lamnid sharks, namely, gravid specimens of Clistobothrium montaukensis, Gymnorhynchus isuri and Ceratobothrium xanthocephalum, and 3 are immature specimens of cestode species common to several elasmobranchs, namely, Dinobothrium septaria, Nybelinia lingualis, and Phyllobothrium cf.

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The OH radical is a well-known mediator in the oxidation of biological structures like DNA. Over the past decades, the precise events taking place after reaction of DNA nucleobases with OH radical have been widely investigated by the scientific community. Thirty years after the proposal of the main routes for the reaction of OH with adenine ( Vieira , A.

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