69,525 research outputs found

    What is the importance of sperm subpopulations?

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    .The study of sperm subpopulations spans three decades. The origin, meaning, and practical significance, however, are less clear. Current technology for assessing sperm morphology (CASA-Morph) and motility (CASA-Mot) has enabled the accurate evaluation of these features, and there are many options for data classification. Subpopulations could occur as a result of the stage of development of each spermatozoon in the subpopulation. Spermatogenesis might contribute to the production of these subpopulations. Insights from evolutionary biology and recent molecular research are indicative of the diversity among male gametes that could occur from unequal sharing of transcripts and other elements through cytoplasmic bridges between spermatids. Sperm cohorts exiting the gonads would contain different RNA and protein contents, affecting the spermatozoon physiology and associations with the surrounding environmental milieu. Subsequently, these differences could affect how spermatozoa interact with the environmental milieu (maturation, mixing with seminal plasma, and interacting with the environmental milieu, or female genital tract and female gamete). The emergence of sperm subpopulations as an outcome of evolution, related to the reproductive strategies of the species, genital tract structures, and copulatory and fertilization processes. This kind of approach in determining the importance of sperm subpopulations in fertilization capacity should have a practical impact for conducting reproductive technologies, inspiring and enabling new ways for the more efficient use of spermatozoa in the medical, animal breeding, and conservation fields. This manuscript is a contribution to the Special Issue in memory of Dr. Duane GarnerS

    Neutrophil-Specific Antigens: Immunobiology, Genetics and Roles in Clinical Disorders

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    Neutrophils are the most abundant nucleated cells in blood circulation and play important roles in the innate and adaptive immune responses. Neutrophil-specific antigens, only expressed on neutrophils, are glycoproteins originally identified in studies on neonatal neutropenia due to fetal-maternal incompatibility and autoimmune neutropenia of infancy. The most investigated neutrophil–specific antigens are the NA and NB antigens that their incompatibilities also cause transfusion-induced febrile reactions and acute lung injury, a potentially fatal reaction, and in bone marrow transplantation, causing graft rejection. NA antigens are members of the immunoglobulin superfamily and are low-affinity Fc-receptors FcγRIIIb (CD16b). Fc receptors connect the F(ab), the antigen-binding fragment of the antibody molecules, to neutrophils and lead them to recognize and phagocytize the targeted antigens. The NB (CD177) antigen belongs to the urokinase-type Plasminogen Activator Receptor Superfamily (uPAR, CD59, Ly6), but its specific functions have not been fully determined. It is known, however, that NB antigen binds proteinase-3 (PR3 to the neutrophil membrane), a serine protease. In clinical studies, it was also demonstrated that NB expression is highly elevated in Polycythemia Vera and is unexpectedly expressed in some cancer tissues. Neutrophil-specific antigens are examples of antigens that have important biological and clinical activities beyond antigenicity

    Exploring the Versatility of Benzimidazole Scaffolds as Medicinal Agents: A Brief Update

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    Benzimidazole, one of the finest classes of heterocyclic aromatic compounds have the characteristic structure of benzene fused with a five-membered imidazole ring. Despite being made their first appearance in the late 1870s, they are considered as a ‘privileged molecule’. The applications of this wonder molecule range from medicinal chemistry to material science. Benzimidazole being a potent inhibitor for various enzymes has got therapeutic effects like anticancer, antimicrobial, anthelmintic, antioxidant, anticonvulsant, antifungal, anti-inflammatory, antiviral, antihistaminic, antipsychotic, etc. It has also made its existence in various branches of medical science viz ophthalmology, neurology, cardiology and more. The applications of benzimidazole are not only limited to the biological field but also expanded to the field of material chemistry as well. This chapter summarizes the pharmacological properties of benzimidazole, illustrated on numerous derivatives since 2016

    Adipocytokines: Are They the Theory of Cancer Progression?

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    Adipocytokines have gained significant attention in the scientific community over the past few decades. They are a family of enzymes, hormones, growth factors, proteins, and other bioactive molecules that are important regulators of many processes. Adipocytokines are predominantly produced by preadipocytes and mature adipocytes to act through a network of autocrine, paracrine, and endocrine pathways. Leptin (LEP) is the first adipocytokine discovered that has a role in modulating adiposity and has been shown to exert pleiotropic effects on many metabolic pathways through the leptin receptors (LEPRs). LEP has pro-tumoral roles; it promotes angiogenesis, proliferation, survival of tumor cells, and inhibits apoptosis. To exercise its role in tumorigenesis, LEP-LEPR signaling and epithelial-mesenchymal transitions (EMTs) play a significant role. LEP is an oncogenic factor mainly due to its proinflammatory and proangiogenic effects. In angiogenesis, LEP acts directly as an endothelial growth factor or indirectly through cellular pathways, such as STAT3/ERK1/2, JAK2/STAT3, MAPK/ERK, PI3K/AKT, p38, p53, MAPK, and Wnt/β-catenin

    Macrophage: A Key Player of Teleost Immune System

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    Fish, the free-living organisms, residing in aquatic environment, are earliest vertebrates with fully developed innate and adaptive immunity. Immune organs homologous to those of mammalian immune system are found in fish. Macrophages are best known for their role in immunity, basic function of which being cytokine production and phagocytosis. Due to environmental adaptation and whole genome duplication, macrophages in teleost are differently modulated (pro-inflammatory, M1-type, and anti-inflammatory/regulatory, M2-type) and perform a variety of different functions as compared with those of mammals. Phagocytosis is a major mechanism for removing pathogens and/or foreign particles in immune system and therefore is a critical component of the innate and adaptive immune system. One of the most competent phagocytes in teleost is found to be macrophages/monocytes. Increasing experimental evidence demonstrates that teleost phagocytic cells can recognize and destroy antigens to elicit adaptive immune responses that involve multiple cytokines. A detail understanding of teleost macrophages and phagocytosis would not only help in understanding the immune mechanism but will also help in disease prevention in teleost

    The association between neurodegeneration and local complement activation in the thalamus to progressive multiple sclerosis outcome

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    The extent of grey matter demyelination and neurodegeneration in the progressive multiple sclerosis (PMS) brains at post‐mortem associates with more severe disease. Regional tissue atrophy, especially affecting the cortical and deep grey matter, including the thalamus, is prognostic for poor outcomes. Microglial and complement activation are important in the pathogenesis and contribute to damaging processes that underlie tissue atrophy in PMS. We investigated the extent of pathology and innate immune activation in the thalamus in comparison to cortical grey and white matter in blocks from 21 cases of PMS and 10 matched controls. Using a digital pathology workflow, we show that the thalamus is invariably affected by demyelination and had a far higher proportion of active inflammatory lesions than forebrain cortical tissue blocks from the same cases. Lesions were larger and more frequent in the medial nuclei near the ventricular margin, whilst neuronal loss was greatest in the lateral thalamic nuclei. The extent of thalamic neuron loss was not associated with thalamic demyelination but correlated with the burden of white matter pathology in other forebrain areas (Spearman r = 0.79, p < 0.0001). Only thalamic neuronal loss, and not that seen in other forebrain cortical areas, correlated with disease duration (Spearman r = −0.58, p = 0.009) and age of death (Spearman r = −0.47, p = 0.045). Immunoreactivity for the complement pattern recognition molecule C1q, and products of complement activation (C4d, Bb and C3b) were elevated in thalamic lesions with an active inflammatory pathology. Complement regulatory protein, C1 inhibitor, was unchanged in expression. We conclude that active inflammatory demyelination, neuronal loss and local complement synthesis and activation in the thalamus, are important to the pathological and clinical disease outcomes of PMS

    S. Coronopifolius Bromoterpenos : atividade antitumoral e caraterização de vias de sinalização intracelulares em modelos in vitro

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    Nowadays, cancer is one of the major threats to human health and, due to distinct factors, it is expected that its incidence will increase in the next decades leading to an urgent need to develop new approaches to fight it, including the development of new anticancer drugs. Marine environment has revealed to harbor a vast diversity of unusual and distinct chemical structures with high potential to be used as scaffolds for the design and development of new drugs with great effectiveness and specificity to human illnesses, such as cancer. Therefore, the main goal of the present thesis was to study the chemical profile of the red alga Sphaerococcus coronopifolius collected in the Berlenga Nature Reserve (Peniche, Portugal) as well as to evaluate the antitumor activities of its major metabolites. The study of S. coronopifolius chemical profile allowed, through antitumor bioguied screening, to identify seven compounds, including five already known terpenes, alloaromadendrene (1), bromosphaerol (3), sphaerococcenol A (4),12S-hydroxy-bromosphaerol (5), and 12R-hydroxy-bromosphaerol (7), as well as two new natural molecules, a new brominated dactylomelane diterpene, named sphaerodactylomelol (2) and a new brominated 7-epi-eudesmane sesquiterpene, named 6-acetyl-sphaeroeudesmanol (6). Compounds (2-5, 7) exhibited antiproliferative activity on an in vitro model of human hepatocellular carcinoma (HepG2) in an IC50 range between 42.87 to 279.93 μM being the highest activity induced by sphaerococcenol A (4) (IC50: 42.87 μM). The new diterpene, sphaerodactylomelol (2), was the only compound that induced cytotoxicity (IC50: 719.85 μM) on HepG2 cells. Hence, due to the cytotoxic activities exhibited by the compounds 2-5 and 7 on HepG2 cells, their antitumor potential was evaluated on several in vitro human cancer cells derived from distinct tissues (SH-SY5Y; MCF-7; A549; NCI-H226; PC-3; HCT-15; CACO-2; SK-MEL-28; RenG2) to define their selectivity and potency (0.1 - 100 μM; 24 hours). Murine fibroblasts (3T3) were used as non-tumor cells. S. coronopifolius compounds did not displayed selective activity for specific tumor tissue as well as for cancer cells. Concerning the potency of the effects, S. coronopifolius metabolites exhibited an IC50 range between 4.47 to 89.41 μM. Sphaerococcenol A (4) showed the highest cytotoxicity exhibiting a range of IC50 between 4.47 to 16.59 μM and sphaerodactylomelol (2) displayed the lowest cytotoxicity showing a range of IC50 between 33.04 and 89.41 μM. In addition, to understand the intracellular signaling pathways linked to their cytotoxic activities, hallmarks associated to reactive oxygen species production, namely through hydrogen peroxide (H2O2) real-time production, and apoptosis (membrane translocation of phosphatidylserine, mitochondrial membrane potential, Caspase-9 activity, and DNA condensation and/ or fragmentation) were studied on an in vitro breast carcinoma model (MCF-7 cells). Genotoxic activities were evaluated on fibroblasts derived from mouse tissues (L929 cells). The treatment of MCF-7 cells with compounds induced changes in the mitochondrial membrane potential, increased Caspase-9 activity, and promoted DNA condensation and/or fragmentation. In addition, with the exception of bromosphaerol (3), all compounds promoted the increase of H2O2 levels production. Regarding genotoxic effects, only bromosphaerol (3) mediated DNA damage in L929 cells. Additionally, to evaluate the compounds' effects in a system similar to a tissue, co-cultures of non-malignant human bronchial fibroblasts and malignant human bronchial epithelial cells were implemented. 12R-hydroxy-bromosphaerol (7) revealed to be the compound with highest potential exhibiting cytotoxicity and ability to prevent the formation of malignant stem cells. Summarizing, Sphaerococcus coronopifolius bromoditerpenes exhibited cytotoxic activities, which seems to be linked to apoptosis, H2O2 generation and induction of DNA damage. Despite the interesting results achieved, this work is an initial approach being of utmost importance to deeply characterize the intracellular signaling pathways associated with antitumor activities mediated by these compounds in order to define their effective pharmacological potential in cancer therapeutics.Atualmente, o cancro representa um dos maiores desafios para a saúde humana e, devido a diversos fatores, é expectável que a sua incidência aumente nas próximas décadas tornando-se de extrema importância desenvolver novas abordagens terapêuticas, incluindo o desenvolvimento de novos fármacos. Neste âmbito, o ambiente marinho tem revelado albergar uma elevada diversidade de estruturas químicas incomuns e distintas com potencial para serem usadas como “scaffolds” no design e desenvolvimento de novos fármacos com grande eficácia e especificidade para o tratamento de doenças humanas, como o cancro. Desta forma, o principal objetivo da presente tese consistiu em estudar o perfil químico da alga vermelha Sphaerococcus coronopifolius recolhida na Reserva Natural da Berlenga (Peniche, Portugal) assim como avaliar as atividades antitumorais dos seus principais metabolitos. O estudo do perfil químico da alga S. coronopifolius, através de screening bioguiado, permitiu identificar sete compostos, incluindo cinco terpenos previamente descritos e denominados como alloaromadendrene (1), bromosphaerol (3), sphaerococcenol A (4), 12S-hydroxy-bromosphaerol (5) e 12R-hydroxy-bromosphaerol (7), assim como duas novas moléculas de origem natural, nomeadamente um diterpeno dactilomelano bromado, designado sphaerodactylomelol (2), e um novo sesquiterpeno 7-epi-eudesmano bromado, designado 6-acetyl-sphaeroeudesmanol (6). Os compostos (2-5 e 7) exibiram atividade antiproliferativa num modelo in vitro de carcinoma hepatocelular humano (HepG2) num intervalo de IC50 entre 42.87 e 279.93 μM, sendo a atividade mais potente induzida pelo sphaerococcenol A (4) (IC50: 42.87 μM). Por sua vez, o novo diterpeno, sphaerodactylomelol (2), foi o único composto que induziu citotoxicidade (IC50: 719.85 μM) nas células HepG2. Consequentemente, devido às atividades exibidas pelos compostos 2-5 e 7 nas células HepG2, o seu potencial antitumoral foi avaliado em diferentes modelos celulares in vitro de cancro humano derivados de diferentes tecidos (SH-SY5Y; MCF-7; A549; NCI-H226; PC-3; HCT-15; CACO-2; SK-MEL-28; RenG2) de modo a definir a sua seletividade e potência (0.1 - 100 μM; 24 h). Fibroblastos derivados de tecidos murinos (3T3) foram usados como modelo não tumoral. Os compostos não demonstraram seletividade nem para células tumorais nem entre os modelos derivados de diferentes tecidos. No que diz respeito à capacidade citotóxica, os compostos exibiram um intervalo de IC50 entre 4.47 e 89.41 μM. O sphaerococcenol A (4) induziu o maior efeito citotóxico exibindo um intervalo de IC50 entre 4.47 e 16.59 μM enquanto o sphaerodactylomelol (2) demonstrou ser o composto menos citotóxico exibindo um intervalo de IC50 entre 33.04 e 89.41 μM. De modo a compreender as vias de sinalização intracelular envolvidas nas atividades citotóxicas observadas, biomarcadores associados à produção de espécies reativas de oxigénio, nomeadamente a produção de peróxido de hidrogénio (H2O2) em tempo real, e apoptose (translocação da fosfatidilserina, potencial mitocondrial membranar, atividade da Caspase-9, condensação de ADN e/ ou fragmentação) foram estudados num modelo in vitro de carcinoma humano da mama (MCF-7). As atividades genotóxicas foram avaliadas em fibroblastos derivados de tecidos murinos (L929). O tratamento realizado nas células MCF-7 com os compostos isolados induziu alterações no potencial mitocondrial membranar, aumentou a atividade da Caspase-9 e promoveu a condensação e/ ou a fragmentação de ADN. Com a exceção do bromosphaerol (3), todos os compostos promoveram um aumento da produção dos níveis de H2O2. No que diz respeito aos ensaios de genotoxicidade, apenas o bromosphaerol (3) mediou danos no ADN das células L929. Tendo em vista avaliar os supracitados compostos num sistema que mais se aproximasse a um tecido foram implementadas co-culturas de fibroblastos bronquiais humanos não malignos e células do epitélio bronquial humano malignizadas tendo o 12R-hydroxy-bromosphaerol (7) induzido citotoxicidade e capacidade de impedir a formação de células estaminais malignas. Resumindo, os bromoterpenos isolados da alga vermelha Sphaerococcus coronopifolius exibiram atividades citotóxicas relevantes, as quais parecem estar associadas aos processos de apoptose, produção de H2O2 e danos de ADN. Por sua vez, o composto 12R-hydroxy-bromosphaerol (7) demonstrou ser o composto mais promissor nos ensaios realizados em sistema de co-cultura impedindo a formação de células tumorais com fenótipo estaminal. Apesar dos resultados obtidos, este trabalho consistiu numa abordagem inicial sendo de extrema importância caraterizar profundamente as vias de sinalização intracelular associadas às atividades antitumorais mediadas por estes compostos de modo a compreender o seu verdadeiro potencial como agentes farmacológicos na terapia do cancro.Programa Doutoral em Ciência, Tecnologia e Gestão do Ma

    Identification of Hindbrain Neural Substrates for Motor Initiation in the hatchling Xenopus laevis Tadpole

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    Animal survival profoundly depends on the ability to detect stimuli in the environment, process them and respond accordingly. In this respect, motor responses to a sensory stimulation evolved into a variety of coordinated movements, which involve the control of brain centres over spinal locomotor circuits. The hatchling Xenopus tadpole, even in its embryonic stage, is able to detect external sensory information and to swim away if the stimulus is considered noxious. To do so, the tadpole relies on well-known ascending sensory pathway, which carries the sensory information to the brain. When the stimulus is strong enough, descending interneurons are activated, leading to the excitation of spinal CPG neurons, which causes the undulatory movement of swimming. However, the activation of descending interneurons that marks the initiation of motor response appears after a long delay from the sensory stimulation. Furthermore, the long-latency response is variable in time, as observed in the slow-summating excitation measured in descending interneurons. These two features, i.e. long-latency and variability, cannot be explained by the firing time and pattern of the ascending sensory pathway of the Xenopus tadpole. Therefore, a novel neuronal population has been proposed to lie in the hindbrain of the tadpole, and being able to 'hold' the sensory information, thus accounting for the long and variable delay of swim initiation. In this work, the role of the hindbrain in the maintenance of the long and variable response to trunk skin stimulation is investigated in the Xenopustadpole at developmental stage 37/38. A multifaceted approach has been used to unravel the neuronal mechanisms underlying the delayed motor response, including behavioural experiments, electrophysiology analysis of fictive swimming, hindbrain extracellular recordings and imaging experiments. Two novel neuronal populations have been identified in the tadpole's hindbrain, which exhibit activation patterns compatible with the role of delaying the excitation of the spinal locomotor circuit. Future work on cellular properties and synaptic connections of these newly discovered populations might shed light on the mechanism of descending control active at embryonic stage. Identifying supraspinal neuronal populations in an embryonic organism could aid in understanding mechanisms of descending motor control in more complex vertebrates
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