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1.
Environ Health Prev Med ; 25(1): 56, 2020 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-32979924

RESUMO

BACKGROUND: We previously demonstrated that continuous exposure to nitrous acid gas (HONO) for 4 weeks, at a concentration of 3.6 parts per million (ppm), induced pulmonary emphysema-like alterations in guinea pigs. In addition, we found that HONO affected asthma symptoms, based on the measurement of respiratory function in rats exposed to 5.8 ppm HONO. This study aimed to investigate the dose-response effects of HONO exposure on the histopathological alterations in the respiratory tract of guinea pigs to determine the lowest observed adverse effect level (LOAEL) of HONO. METHODS: We continuously exposed male Hartley guinea pigs (n = 5) to four different concentrations of HONO (0.0, 0.1, 0.4, and 1.7 ppm) for 4 weeks (24 h/day). We performed histopathological analysis by observing lung tissue samples. We examined samples from three guinea pigs in each group under a light microscope and measured the alveolar mean linear intercept (Lm) and the thickness of the bronchial smooth muscle layer. We further examined samples from two guinea pigs in each group under a scanning electron microscope (SEM) and a transmission electron microscope (TEM). RESULTS: We observed the following dose-dependent changes: pulmonary emphysema-like alterations in the centriacinar regions of alveolar ducts, significant increase in Lm in the 1.7 ppm HONO-exposure group, tendency for hyperplasia and pseudostratification of bronchial epithelial cells, and extension of the bronchial epithelial cells and smooth muscle cells in the alveolar duct regions. CONCLUSIONS: These histopathological findings suggest that the LOAEL of HONO is < 0.1 ppm.


Assuntos
Enfisema/induzido quimicamente , Hiperplasia/induzido quimicamente , Exposição por Inalação/efeitos adversos , Pulmão/patologia , Ácido Nitroso/toxicidade , Células Epiteliais Alveolares/efeitos dos fármacos , Animais , Brônquios/efeitos dos fármacos , Relação Dose-Resposta a Droga , Células Epiteliais/efeitos dos fármacos , Cobaias , Pulmão/efeitos dos fármacos , Pulmão/ultraestrutura , Masculino , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Miócitos de Músculo Liso/efeitos dos fármacos
2.
Sci Rep ; 10(1): 15917, 2020 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-32985513

RESUMO

SARS-CoV-2 is the novel coronavirus responsible for the outbreak of COVID-19, a disease that has spread to over 100 countries and, as of the 26th July 2020, has infected over 16 million people. Despite the urgent need to find effective therapeutics, research on SARS-CoV-2 has been affected by a lack of suitable animal models. To facilitate the development of medical approaches and novel treatments, we compared the ACE2 receptor, and TMPRSS2 and Furin proteases usage of the SARS-CoV-2 Spike glycoprotein in human and in a panel of animal models, i.e. guinea pig, dog, cat, rat, rabbit, ferret, mouse, hamster and macaque. Here we showed that ACE2, but not TMPRSS2 or Furin, has a higher level of sequence variability in the Spike protein interaction surface, which greatly influences Spike protein binding mode. Using molecular docking simulations we compared the SARS-CoV and SARS-CoV-2 Spike proteins in complex with the ACE2 receptor and showed that the SARS-CoV-2 Spike glycoprotein is compatible to bind the human ACE2 with high specificity. In contrast, TMPRSS2 and Furin are sufficiently similar in the considered hosts not to drive susceptibility differences. Computational analysis of binding modes and protein contacts indicates that macaque, ferrets and hamster are the most suitable models for the study of inhibitory antibodies and small molecules targeting the SARS-CoV-2 Spike protein interaction with ACE2. Since TMPRSS2 and Furin are similar across species, our data also suggest that transgenic animal models expressing human ACE2, such as the hACE2 transgenic mouse, are also likely to be useful models for studies investigating viral entry.


Assuntos
Betacoronavirus/genética , Infecções por Coronavirus/veterinária , Pandemias/veterinária , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/veterinária , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo , Sequência de Aminoácidos/genética , Animais , Gatos , Biologia Computacional/métodos , Infecções por Coronavirus/patologia , Cricetinae , Modelos Animais de Doenças , Cães , Furões , Furina/genética , Furina/metabolismo , Cobaias , Humanos , Macaca fascicularis , Camundongos , Simulação de Acoplamento Molecular , Peptidil Dipeptidase A/genética , Pneumonia Viral/patologia , Coelhos , Ratos , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo
3.
PLoS Negl Trop Dis ; 14(9): e0008555, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32976538

RESUMO

Junin virus (JUNV) is a New World arenavirus that is the causative agent of Argentine hemorrhagic fever (AHF). Candid#1 (Can) is a live-attenuated vaccine strain of JUNV that since its introduction has resulted in a marked decrease in AHF incidence within the endemic regions of the Pampas in Argentina. Originally, the viral determinants and mechanisms of Can attenuation were not well understood. Recent work has identified the glycoprotein as the major attenuating factor for Can. The establishment of attenuating strategies based on any of the other viral proteins, however, has not been pursued. Here, we document the role of Can Z resulting in incompatibilities with wild type JUNV that results in decreased growth in vitro. In addition, this incompatibility results in attenuation of the virus in the guinea pig model. Further, we identify a single mutation (V64G) in the Z protein that is able to confer this demonstrated attenuation. By establishing and characterizing a novel attenuation strategy for New World mammarenaviruses, we hope to aid future vaccine development for related emerging pathogens including Machupo virus (MACV), Guanarito virus (GTOV), and Sabia virus (SABV).


Assuntos
Glicoproteínas/genética , Febre Hemorrágica Americana/virologia , Vírus Junin/genética , Mutação , Animais , Linhagem Celular , Chlorocebus aethiops , Cricetinae , Feminino , Glicoproteínas/metabolismo , Cobaias , Vírus Junin/crescimento & desenvolvimento , Células Vero , Proteínas Virais/genética , Proteínas Virais/metabolismo
4.
Nat Commun ; 11(1): 4062, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32811826

RESUMO

Influenza viruses are presumed, but not conclusively known, to spread among humans by several possible routes. We provide evidence of a mode of transmission seldom considered for influenza: airborne virus transport on microscopic particles called "aerosolized fomites." In the guinea pig model of influenza virus transmission, we show that the airborne particulates produced by infected animals are mainly non-respiratory in origin. Surprisingly, we find that an uninfected, virus-immune guinea pig whose body is contaminated with influenza virus can transmit the virus through the air to a susceptible partner in a separate cage. We further demonstrate that aerosolized fomites can be generated from inanimate objects, such as by manually rubbing a paper tissue contaminated with influenza virus. Our data suggest that aerosolized fomites may contribute to influenza virus transmission in animal models of human influenza, if not among humans themselves, with important but understudied implications for public health.


Assuntos
Fômites , Vírus da Influenza A , Influenza Humana/transmissão , Influenza Humana/virologia , Material Particulado , Aerossóis , Animais , Modelos Animais de Doenças , Feminino , Cobaias , Humanos , Vírus da Influenza A Subtipo H3N2 , Infecções por Orthomyxoviridae/virologia , Tamanho da Partícula
5.
Virology ; 548: 93-100, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32838950

RESUMO

Human cytomegalovirus (HCMV) infects the chorioamnion, but whether these infections cause fetal membrane dysfunction remains poorly understood. We sought to assess whether guinea pig cytomegalovirus (GPCMV) infects amnion-derived cells in vitro, compare the inflammatory response of amnion cells to GPCMV and HCMV, and determine if GPCMV infects the amnion in vivo. We found that GPCMV replicates in primary guinea pig amnion derived cells and HPV16 E6/E7-transduced amniotic epithelial cells (AEC[E6/E7]s). HCMV and GPCMV infection of amnion cells increased the transcription of the chemokines CCL5/Ccl5, CXCL8/Cxcl8, and CXCL10/Cxcl10. Myd88-knockdown decreased Ccl5 and Cxc8 transcription in GPCMV-infected AEC[E6/E7]s. GPCMV was detected in the guinea pig amnion after primary maternal infection, revealing that guinea pigs are an appropriate model to study fetal membrane physiology after cytomegalovirus infection. As inflammation is known to cause fetal membrane weakening, the amnion's response to cytomegalovirus infection may cause preterm birth and other adverse pregnancy outcomes.


Assuntos
Âmnio/imunologia , Quimiocinas/imunologia , Infecções por Citomegalovirus/imunologia , Citomegalovirus/fisiologia , Complicações na Gravidez/imunologia , Âmnio/virologia , Animais , Quimiocina CCL5/genética , Quimiocina CCL5/imunologia , Quimiocina CXCL10/genética , Quimiocina CXCL10/imunologia , Quimiocinas/genética , Citomegalovirus/genética , Citomegalovirus/imunologia , Infecções por Citomegalovirus/genética , Feminino , Cobaias , Humanos , Interleucina-8/genética , Interleucina-8/imunologia , Gravidez , Complicações na Gravidez/genética , Complicações na Gravidez/virologia
6.
Sci Total Environ ; 743: 140531, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32758812

RESUMO

The performance of eight microbial source tracking (MST) markers was evaluated in a low-resource, tropical community located in Iquitos, Peru. Fecal samples from humans, dogs, cats, rats, goats, buffalos, guinea-pigs, chickens, ducks, pigeons, and parrots were collected (n = 117). All samples were tested with human (BacHum, HF183-Taqman), dog (BactCan), pig (Pig-2-Bac), and avian (LA35, Av4143, ND5, cytB) markers using quantitative PCR (qPCR). Internal validity metrics were calculated using all animal fecal samples, as well as animal fecal samples contextually relevant for the Peruvian Amazon. Overall, Pig-2-Bac performed best, with 100% sensitivity and 88.5% specificity to detect the correct fecal source. Human-associated markers showed a sensitivity of 80.0% and 76.7%, and specificity of 66.2% and 67.6%. When limiting the analysis to contextually relevant animal fecal samples for the Peruvian Amazon, Av143 surpassed cytB with 95.7% sensitivity and 81.8% specificity. BactCan demonstrated 100% sensitivity and 47.4% specificity. The gene copy number detected by BacHum and HF183-Taqman were positively correlated (Pearson's correlation coefficient: 0.785), as well as avian markers cytB with Av4143 (Pearson's correlation coefficient: 0.508) and nd5 (Pearson's correlation coefficient: 0.949). These findings suggest that markers such as Av4143, Pig2Bac, cytb and BacHum have acceptable performance to be impactful in source attribution studies for zoonotic enteric disease transmission in this and similar low-resource communities.


Assuntos
Galinhas , Monitoramento Ambiental , Animais , Biomarcadores , Gatos , Cães , Fezes , Cobaias , Humanos , Peru , Ratos , Microbiologia da Água , Poluição da Água/análise
7.
Cell ; 182(3): 713-721.e9, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32778225

RESUMO

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) threatens global public health. The development of a vaccine is urgently needed for the prevention and control of COVID-19. Here, we report the pilot-scale production of an inactivated SARS-CoV-2 vaccine candidate (BBIBP-CorV) that induces high levels of neutralizing antibodies titers in mice, rats, guinea pigs, rabbits, and nonhuman primates (cynomolgus monkeys and rhesus macaques) to provide protection against SARS-CoV-2. Two-dose immunizations using 2 µg/dose of BBIBP-CorV provided highly efficient protection against SARS-CoV-2 intratracheal challenge in rhesus macaques, without detectable antibody-dependent enhancement of infection. In addition, BBIBP-CorV exhibits efficient productivity and good genetic stability for vaccine manufacture. These results support the further evaluation of BBIBP-CorV in a clinical trial.


Assuntos
Betacoronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Avaliação Pré-Clínica de Medicamentos/métodos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Vacinas de Produtos Inativados/uso terapêutico , Vacinas Virais/uso terapêutico , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Betacoronavirus/genética , Chlorocebus aethiops , Infecções por Coronavirus/virologia , Modelos Animais de Doenças , Feminino , Cobaias , Imunogenicidade da Vacina , Macaca fascicularis , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Filogenia , Pneumonia Viral/virologia , Coelhos , Ratos , Ratos Wistar , Vacinas de Produtos Inativados/efeitos adversos , Células Vero , Vacinas Virais/efeitos adversos
8.
Virology ; 548: 236-249, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32791352

RESUMO

Species-specific guinea pig cytomegalovirus (GPCMV) causes congenital CMV and the virus encodes homolog glycoprotein complexes to human CMV, including gH-based trimer (gH/gL/gO) and pentamer-complex (PC). Platelet-derived growth factor receptor alpha (gpPDGFRA), only present on fibroblast cells, was identified via CRISPR as the putative receptor for PC-independent GPCMV infection. Immunoprecipitation assays demonstrated direct interaction of gH/gL/gO with gpPDGFRA but not in absence of gO. Expression of viral gB also resulted in precipitation of gB/gH/gL/gO/gpPDGFRA complex. Cell-cell fusion assays determined that expression of gpPDGFRA and gH/gL/gO in adjacent cells enabled cell fusion, which was not enhanced by gB. N-linked gpPDGFRA glycosylation inhibition had limited effect and blocking tyrosine kinase (TK) transduction had no impact on infection. Ectopically expressed gpPDGFRA or TK-domain mutant in trophoblast or epithelial cells previously non-susceptible to GPCMV(PC-) enabled viral infection. In contrast, transient human PDGFRA expression did not complement GPCMV(PC-) infection, a potential basis for viral species specificity.


Assuntos
Betaherpesvirinae/fisiologia , Infecções por Herpesviridae/veterinária , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Doenças dos Roedores/metabolismo , Proteínas Virais/metabolismo , Animais , Betaherpesvirinae/genética , Fusão Celular , Cobaias , Infecções por Herpesviridae/genética , Infecções por Herpesviridae/metabolismo , Ligação Proteica , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Doenças dos Roedores/genética , Doenças dos Roedores/virologia , Proteínas Virais/química , Proteínas Virais/genética , Internalização do Vírus
9.
Wiad Lek ; 73(4): 705-707, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32731701

RESUMO

OBJECTIVE: The aim is to establish the features of morphological and morphometric changes in the skin of guinea pigs in erythemal, early post-erythemal and late post-erythemic periods after local ultraviolet irradiation. PATIENTS AND METHODS: Materials and methods: Studies were conducted on 54 albino guinea pigs weighing 400-500 g. Ultraviolet erythema was caused by irradiation in 1 minimum erythemal dose. The control group included intact guinea pigs. After 2, 4 hours, on the 3rd, 8th, 15th, 21st, 28th day, the fragments of the irradiated skin were investigated using histochemical and morphometric methods. RESULTS: Results: After 2, 4 hours after irradiation, dyscirculatory changes in the skin develop. By the 3rd day of the experiment a morphological picture of acute inflammation in the epidermis and dermis develops, apoptotic keratinocytes appear (sunburn cells), which is accompanied by thickening of the epidermis and an increase in the density of fibroblasts. By the 8th day proliferative-hyperplastic and degenerative changes begin to prevail, including dystrophic nature, the thickness of the epidermis and the density of fibroblasts reach a maximum. In the long term, on the 15-28th day, dystrophic changes of the epidermis, dyskeratosis, changes in the number and structure of elastic fibers with an increase in uneven fibrosis, collagenization processes and the development of sclerotic changes, as well as a significant thickening of the epidermis, an increase in the density of fibroblasts are observed. CONCLUSION: Conclusions: The data obtained indicate pronounced morphofunctional changes in the skin in the zone of local ultraviolet irradiation observed throughout the entire observation period.


Assuntos
Pele , Raios Ultravioleta , Animais , Cobaias , Hiperplasia
10.
Aust Vet J ; 98(9): 424-428, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32643145

RESUMO

Corynetoxins, members of the tunicamycin group of antibiotics, produce a severe and frequently fatal neurological disorder in ruminant livestock, and guinea pigs are a useful model to study the pathology and pathogenesis of this disease. The aim of this study was to determine whether tunicamycin produced ocular damage in this species, which could have pharmacotherapeutic and diagnostic value. Four 8-week-old guinea pigs were treated with tunicamycin, and two control animals were given the drug vehicle only. Guinea pigs were injected subcutaneously with 400 µg/kg of tunicamycin, in dimethyl sulphoxide, and killed 48 h post-injection. The eyes were then examined by light microscopy. Immunohistochemistry for rhodopsin was also performed. The principal pathological finding was marked retinal photoreceptor damage, which was characterised by disruption and disorganisation of rods, sometimes progressing to necrosis and separation of the outer segment. The cytoplasm of some rods was focally distended by accumulated, proteinaceous material. Rhodopsin immunopositivity in injured rods was markedly diminished and associated with shrinkage and shortening of the injured rod's outer segment. Ocular pathology, in the form of reproducible and extensive retinal photoreceptor damage, was found in guinea pigs given tunicamycin, extending the range of species found to be susceptible to this toxic injury. The guinea pig could prove to be a good animal model to test potential therapeutic interventions, and as brain lesions are often minimal and liver pathology non-specific in intoxicated ruminants, any spontaneously arising ophthalmic injury found in these species could be diagnostically useful.


Assuntos
Células Fotorreceptoras de Vertebrados , Células Fotorreceptoras , Animais , Modelos Animais de Doenças , Cobaias , Rodopsina , Tunicamicina
11.
Int J Nanomedicine ; 15: 4591-4606, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32612358

RESUMO

Objective: Artemisinin (ART) is a natural anti-malarial sesquiterpene lactone which has the ability to treat and activate the CLRN1 pathway to play a pivotal role in hearing loss and hair cell function. To investigate the therapeutic effect of ART in hearing loss induced by gentamicin (GM), an ART-loaded poly(ethylene glycol)-b-poly(ε-caprolactone) mPEG-PCL nanoparticle-based photosensitive hydrogel was developed and tested in this study. Materials and Methods: Artemisinin-loaded mPEG-PCL nanoparticles (mPEG-PCL-ART-NPs) were prepared by a double emulsion method and the formulation was optimized by an orthogonal experimental design. The particle size, zeta potential, morphology and in vitro dissolution of the mPEG-PCL-ART-NPs were well characterized. Biocompatibility of the mPEG-PCL-ART-NPs were tested on HeLa cells with an MTT assay. The photo-crosslinkable biodegradable gelatin methacrylate (GelMA) hydrogel was prepared and its physicochemical properties (such as substitution, photocrosslinking efficiency, cell viability morphology, mechanical and swelling properties) were evaluated. Finally, mPEG-PCL-ART-FITC-NPs, loaded mPEG-PCL-ART-NPs, and loaded mPEG-PCL-ART-NPs-GelMA hydrogels were fabricated and a GM toxicity-induced guinea pig ear damage model was established to determine the effectiveness of the materials on returning auditory function and cochlea pathomorphology. Results: The zeta potential of the mPEG-PCL-ART-NPs was about -38.64 ± 0.21 mV and the average size was 167.51 ± 1.87 nm with an encapsulation efficacy of 81.7 ± 1.46%. In vitro release studies showed that the mPEG-PCL-ART-NPs possessed a sustained-release effect and the MTT experiments showed good biocompatibility properties of the drug-loaded nanoparticles. The results indicated that the 5% GelMA with MA-4% hydrogel had a better crosslinking density and 3D structure for drug loading and drug delivery than controls. Skin penetration results showed that the mPEG-PCL-ART-NPs increased adhesive capacity and avoided fast diffusion in the skin. Most importantly, auditory brainstem response results indicated that the mPEG-PCL-ART-NPs-GelMA hydrogel alleviated hearing loss induced by GM. Conclusion: These results suggested that the presently fabricated mPEG-PCL-ART-NPs-GelMA hydrogels are promising formulations for the treatment of hearing loss induced by GM and lay the foundation for further clinical research of inner ear induction therapy.


Assuntos
Artemisininas/administração & dosagem , Artemisininas/farmacologia , Gentamicinas/efeitos adversos , Perda Auditiva/tratamento farmacológico , Hidrogéis/administração & dosagem , Animais , Artemisininas/farmacocinética , Sistemas de Liberação de Medicamentos , Etilenoglicóis/química , Gelatina , Cobaias , Células HeLa , Perda Auditiva/induzido quimicamente , Humanos , Hidrogéis/química , Metacrilatos/química , Nanopartículas/química , Tamanho da Partícula , Poliésteres/química , Polietilenoglicóis/química
12.
Georgian Med News ; (302): 82-85, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32672695

RESUMO

The aim is to study the features of the influence of local ultraviolet radiation on the organization and structure of collagen fibers in the radiation area. The studies were performed on 30 albino guinea pigs weighing 400-500 g, exposed to local ultraviolet radiation. Animals were removed from the experiment after 2 hours, 4 hours, 3 days, 8 days after irradiation. The control group was intact guinea pigs. To assess the structure and location of collagen fibers, skin sections in the irradiated area were studied using histological methods with polarized light analysis of collagen, and they were also analyzed using a scoring system for three parameters: composition, refraction intensity, and orientation of collagen fibers. The revealed structural features of collagen fibers reflect the course of the process of degeneration of the collagen skeleton of the dermis with a violation of the orientation and ordering of collagen fibers and an increase in the content of type III collagen with an increase in the observation period. According to the results of a semi-quantitative assessment of the state of collagen fibers, a significant deterioration in their structure and composition was recorded starting from 4 hours after exposure to ultraviolet radiation and progressed with an increase in the observation period. On the 8th day, the maximum deviation from the structure of the normal dermis is determined by the total number of points. The influence of local ultraviolet radiation in the minimum erythema dose on the skin of guinea pigs leads to the development of disturbances of the organization (abnormal position and ordering) and structure (increase in collagen content of type III) of collagen fibers of the dermis, which progress with an increase of the observation period.


Assuntos
Pele , Raios Ultravioleta , Animais , Colágeno , Derme , Cobaias
13.
Am J Physiol Heart Circ Physiol ; 319(2): H396-H409, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32678707

RESUMO

Myocardial ischemia leads to conduction slowing, cell-to-cell uncoupling, and arrhythmias. We previously demonstrated that varying perfusate sodium (Na+) and calcium (Ca2+) attenuates conduction slowing and arrhythmias during simulated ischemia with continuous perfusion. Cardioprotection was selectively associated with widening of the perinexus, a gap junction adjacent nanodomain important to ephaptic coupling. It is unknown whether perfusate composition affects the perinexus or ischemic conduction during nonsimulated ischemia, when coronary flow is reduced or halted. We hypothesized that altering preischemic perfusate composition could facilitate perinexal expansion and attenuate conduction slowing during global ischemia. To test this hypothesis, ex vivo guinea pig hearts (n = 49) were Langendorff perfused with 145 or 153 mM Na+ and 1.25 or 2.0 mM Ca2+ and optically mapped during 30 min of no-flow ischemia. Altering Na+ and Ca2+ did not substantially affect baseline conduction. Increasing Na+ and decreasing Ca2+ both lowered pacing thresholds, whereas increasing Ca2+ narrowed perinexal width (Wp). A least squares mean estimate revealed that reduced perfusate Na+ and Ca2+ resulted in the most severe conduction slowing during ischemia. Increasing Na+ alone modestly attenuated conduction slowing, yet significantly delayed the median time to conduction block (10 to 16 min). Increasing both Na+ and Ca2+ selectively widened Wp during ischemia (22.7 vs. 15.7 nm) and attenuated conduction slowing to the greatest extent. Neither repolarization nor levels of total or phosphorylated connexin43 correlated with conduction slowing or block. Thus, perfusate-dependent widening of the perinexus preserved ischemic conduction and may be an adaptive response to ischemic stress.NEW & NOTEWORTHY Conduction slowing during acute ischemia creates an arrhythmogenic substrate. We have shown that extracellular ionic concentrations can alter conduction by modulating ephaptic coupling. Here, we demonstrate increased extracellular sodium and calcium significantly attenuate conduction slowing during no-flow ischemia. This effect was associated with selective widening of the perinexus, an intercalated disc nanodomain and putative cardiac ephapse. These findings suggest that acute changes in ephaptic coupling may serve as an adaptive response to ischemic stress.


Assuntos
Bradicardia/prevenção & controle , Cálcio/metabolismo , Bloqueio Cardíaco/prevenção & controle , Sistema de Condução Cardíaco/metabolismo , Frequência Cardíaca , Isquemia Miocárdica/metabolismo , Sódio/metabolismo , Potenciais de Ação , Animais , Bradicardia/etiologia , Bradicardia/metabolismo , Bradicardia/fisiopatologia , Circulação Coronária , Modelos Animais de Doenças , Cobaias , Bloqueio Cardíaco/etiologia , Bloqueio Cardíaco/metabolismo , Bloqueio Cardíaco/fisiopatologia , Preparação de Coração Isolado , Masculino , Isquemia Miocárdica/complicações , Isquemia Miocárdica/fisiopatologia , Transdução de Sinais , Fatores de Tempo
14.
Am J Physiol Heart Circ Physiol ; 319(2): H306-H319, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32618513

RESUMO

Dilated cardiomyopathy (DCM) is clinically characterized by dilated ventricular cavities and reduced ejection fraction, leading to heart failure and increased thromboembolic risk. Mutations in thin-filament regulatory proteins can cause DCM and have been shown in vitro to reduce contractility and myofilament Ca2+-affinity. In this work we have studied the functional consequences of mutations in cardiac troponin T (R131W), cardiac troponin I (K36Q) and α-tropomyosin (E40K) using adenovirally transduced isolated guinea pig left ventricular cardiomyocytes. We find significantly reduced fractional shortening with reduced systolic Ca2+. Contraction and Ca2+ reuptake times were slowed, which contrast with some findings in murine models of myofilament Ca2+ desensitization. We also observe increased sarcoplasmic reticulum (SR) Ca2+ load and smaller fractional SR Ca2+ release. This corresponds to a reduction in SR Ca2+-ATPase activity and increase in sodium-calcium exchanger activity. We also observe dephosphorylation and nuclear translocation of the nuclear factor of activated T cells (NFAT), with concordant RAC-α-serine/threonine protein kinase (Akt) phosphorylation but no change to extracellular signal-regulated kinase activation in chronically paced cardiomyocytes expressing DCM mutations. These changes in Ca2+ handling and signaling are common to all three mutations, indicating an analogous pathway of disease pathogenesis in thin-filament sarcomeric DCM. Previous work has shown that changes to myofilament Ca2+ sensitivity caused by DCM mutations are qualitatively opposite from hypertrophic cardiomyopathy (HCM) mutations in the same genes. However, we find several common pathways such as increased relaxation times and NFAT activation that are also hallmarks of HCM. This suggests more complex intracellular signaling underpinning DCM, driven by the primary mutation.NEW & NOTEWORTHY Dilated cardiomyopathy (DCM) is a frequently occurring cardiac disorder with a degree of genetic inheritance. We have found that DCM mutations in proteins that regulate the contractile machinery cause alterations to contraction, calcium-handling, and some new signaling pathways that provide stimuli for disease development. We have used guinea pig cells that recapitulate human calcium-handling and introduced the mutations using adenovirus gene transduction to look at the initial triggers of disease before remodeling.


Assuntos
Sinalização do Cálcio , Cardiomiopatia Dilatada/genética , Proteínas dos Microfilamentos/genética , Mutação , Contração Miocárdica , Miócitos Cardíacos/enzimologia , Fatores de Transcrição NFATC/metabolismo , Proteína Oncogênica v-akt/metabolismo , Função Ventricular Esquerda , Animais , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/fisiopatologia , Cardiomiopatia Hipertrófica/genética , Cardiomiopatia Hipertrófica/metabolismo , Cardiomiopatia Hipertrófica/fisiopatologia , Células Cultivadas , Predisposição Genética para Doença , Cobaias , Masculino , Proteínas dos Microfilamentos/metabolismo , Fenótipo , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Tropomiosina/genética , Tropomiosina/metabolismo , Troponina I/genética , Troponina I/metabolismo , Troponina T/genética , Troponina T/metabolismo
15.
Am J Physiol Regul Integr Comp Physiol ; 319(3): R243-R254, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32639864

RESUMO

We hypothesized that the physiological adaptations of the fetus in response to chronic intrauterine hypoxia depend on its sex and the gestational age of exposure. Pregnant guinea pigs were exposed to room air (normoxia, NMX) or 10.5% O2 (hypoxia, HPX) at either 25 days (early onset) or 50 days (late onset) of gestation until term (~65 days). We evaluated the effects of HPX on hemodynamic and cardiac function indices using Doppler ultrasound and determined sex-related differences in near-term fetuses. Indices of uterine/umbilical artery pulsatility (PI index) and fetal heart systolic and diastolic function [Tei index and passive filling (E-wave) to filling due to atrial contraction (A-wave) (E/A ratios), respectively] were measured in utero and fetal body (FBW) and organ weights measured from extracted fetuses. Both early- and late-onset HPX decreased FBW in both males and females, had no effect on placenta weights, and increased placenta weight-to-FBW ratios. Early- but not late-onset HPX increased uterine artery PI, but neither HPX condition affected umbilical artery PI. Early-onset HPX increased left ventricle E/A ratios in both males and females, whereas late-onset HPX increased the right ventricle E/A ratio in females only. Hypoxia had no effect on the Tei index in either sex. Early- and late-onset HPX induce placental insufficiency and fetal growth restriction and increase diastolic filling depending on the sex, with female fetuses having a greater capacity than males to compensate for intrauterine hypoxia.


Assuntos
Retardo do Crescimento Fetal/fisiopatologia , Coração Fetal/fisiopatologia , Caracteres Sexuais , Artérias Umbilicais/diagnóstico por imagem , Animais , Feminino , Cobaias , Humanos , Hipóxia/fisiopatologia , Masculino , Insuficiência Placentária/fisiopatologia , Gravidez
16.
Int J Nanomedicine ; 15: 3771-3790, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32547027

RESUMO

Introduction: Rapamycin has been considered as a potential treatment for osteoarthritis (OA). Drug carriers fabricated from liposomes can prolong the effects of drugs and reduce side effects of drugs. Low-intensity pulsed ultrasound (LIPUS) has been found to possess anti-OA effects. Materials and Methods: The anti-osteoarthritic effects of liposome-encapsulated rapamycin (L-rapa) combined with LIPUS were examined by culture of normal and OA chondrocytes in alginate beads and further validated in OA prone Dunkin-Hartley guinea pigs. Results: L-rapa with LIPUS largely up-regulated aggrecan and type II collagen mRNA in human OA chondrocytes (HOACs). L-rapa with LIPUS caused significant enhancement in proteoglycan and type II collagen production in HOACs. Large decreases in both MMP-13 and IL-6 proteins were found in the HOACs exposed to L-rapa with LIPUS. Intra-articular injection of 40 µL L-rapa at both 5 µM and 50 µM twice a week combined with LIPUS thrice a week for 8 weeks significantly increased GAGs and type II collagen in the cartilage of knee. Results on OARSI score showed that intra-articular injection of 5 µM L-rapa with LIPUS displayed the greatest anti-OA effects. Immunohistochemistry revealed that L-rapa with or without LIPUS predominantly reduced MMP-13 in vivo. The values of complete blood count and serum biochemical examinations remained in the normal ranges after the injections with or without LIPUS. These data indicated that intra-articular injection of L-rapa collaborated with LIPUS is not only effective against OA but a safe OA therapy. Conclusion: Taken together, L-rapa combined with LIPUS possessed the most consistently and effectively anabolic and anti-catabolic effects in HOACs and the spontaneous OA guinea pigs. This study evidently revealed that liposome-encapsulation collaborated with LIPUS is able to reduce the effective dose and administration frequency of rapamycin and further stably reinforce its therapeutic actions against OA.


Assuntos
Osteoartrite/terapia , Sirolimo/uso terapêutico , Ondas Ultrassônicas , Animais , Peso Corporal/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Células Cultivadas , Condrócitos/efeitos dos fármacos , Condrócitos/patologia , Condrócitos/efeitos da radiação , Colágeno Tipo II/metabolismo , Liberação Controlada de Fármacos , Cobaias , Humanos , Injeções Intra-Articulares , Interleucina-6/metabolismo , Lipossomos/ultraestrutura , Masculino , Metaloproteinase 13 da Matriz/metabolismo , Pessoa de Meia-Idade , Osteoartrite/sangue , Osteoartrite/patologia , Proteoglicanas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sirolimo/administração & dosagem , Sirolimo/farmacologia
17.
J Pharmacol Sci ; 143(4): 325-329, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32487451

RESUMO

The effects of class I antiarrhythmic drugs on the automaticity of isolated guinea pig pulmonary vein myocardia were investigated using microelectrode and voltage clamp methods. All of the drugs examined reduced the maximum rate of rise of automatic action potentials. The firing frequency and rate of diastolic depolarization were decreased by aprindine, flecainide and propafenone, but not by cibenzoline, disopyramide and pilsicainide, which correlated with blockade of the sodium current component induced by ramp depolarization mimicking the diastolic depolarization. In conclusion, class I antiarrhythmic drugs which block the diastolic sodium current component inhibit the automaticity of the pulmonary vein myocardium.


Assuntos
Antiarrítmicos/farmacologia , Veias Pulmonares/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Animais , Antiarrítmicos/classificação , Cobaias , Técnicas In Vitro , Microeletrodos , Técnicas de Patch-Clamp , Veias Pulmonares/metabolismo , Sódio/metabolismo
18.
Clin Sci (Lond) ; 134(11): 1219-1242, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32501497

RESUMO

Research using animal models of asthma is currently dominated by mouse models. This has been driven by the comprehensive knowledge on inflammatory and immune reactions in mice, as well as tools to produce genetically modified mice. Many of the identified therapeutic targets influencing airway hyper-responsiveness and inflammation in mouse models, have however been disappointing when tested clinically in asthma. It is therefore a great need for new animal models that more closely resemble human asthma. The guinea pig has for decades been used in asthma research and a comprehensive table of different protocols for asthma models is presented. The studies have primarily been focused on the pharmacological aspects of the disease, where the guinea pig undoubtedly is superior to mice. Further reasons are the anatomical and physiological similarities between human and guinea pig airways compared with that of the mouse, especially with respect to airway branching, neurophysiology, pulmonary circulation and smooth muscle distribution, as well as mast cell localization and mediator secretion. Lack of reagents and specific molecular tools to study inflammatory and immunological reactions in the guinea pig has however greatly diminished its use in asthma research. The aim in this position paper is to review and summarize what we know about different aspects of the use of guinea pig in vivo models for asthma research. The associated aim is to highlight the unmet needs that have to be addressed in the future.


Assuntos
Asma/patologia , Modelos Animais de Doenças , Cobaias/fisiologia , Animais , Desenvolvimento de Medicamentos , Edição de Genes , Cobaias/genética , Pulmão/patologia , Pulmão/fisiopatologia
19.
J Vis Exp ; (160)2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32568243

RESUMO

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere's disease, though the pathophysiologic mechanism(s) remain unclear. In order to adequately study the attributes of endolymphatic hydrops, such as the origins of low-frequency hearing loss, a reliable model is needed. The guinea pig is a good model because it hears in the low-frequency regions that are putatively affected by endolymphatic hydrops. Previous research has demonstrated that endolymphatic hydrops can be induced surgically via intradural or extradural approaches that involve drilling on the endolymphatic duct and sac. However, whether it was possible to create an endolymphatic hydrops model using an extradural approach that avoided dangerous drilling on the endolymphatic duct and sac was unknown. The objective of this study was to demonstrate a revised extradural approach to induce experimental endolymphatic hydrops at 30 days post-operatively by obliterating the endolymphatic sac and injuring the endolymphatic duct with a fine pick. The sample size consisted of seven guinea pigs. Functional measurements of hearing were made and temporal bones were subsequently harvested for histologic analysis. The approach had a success rate of 86% in achieving endolymphatic hydrops. The risk of cerebrospinal fluid leak was minimal. No perioperative deaths or injuries to the posterior semicircular canal occurred in the sample. The presented method demonstrates a safe and reliable way to induce endolymphatic hydrops at a relatively quick time point of 30 days. The clinical implications are that the presented method provides a reliable model to further explore the origins of low-frequency hearing loss that can be associated endolymphatic hydrops.


Assuntos
Ducto Coclear/cirurgia , Hidropisia Endolinfática/fisiopatologia , Animais , Cobaias
20.
Heart Rhythm ; 17(9): 1445-1451, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32479900

RESUMO

BACKGROUND: Early during the current coronavirus disease 19 (COVID-19) pandemic, hydroxychloroquine (HCQ) received a significant amount of attention as a potential antiviral treatment, such that it became one of the most commonly prescribed medications for COVID-19 patients. However, not only has the effectiveness of HCQ remained questionable, but mainly based on preclinical and a few small clinical studies, HCQ is known to be potentially arrhythmogenic, especially as a result of QT prolongation. OBJECTIVE: The purpose of this study was to investigate the arrhythmic effects of HCQ, as the heightened risk is especially relevant to COVID-19 patients, who are at higher risk for cardiac complications and arrhythmias at baseline. METHODS: An optical mapping technique utilizing voltage-sensitive fluorescent dyes was used to determine the arrhythmic effects of HCQ in ex vivo guinea pig and rabbit hearts perfused with the upper therapeutic serum dose of HCQ (1000 ng/mL). RESULTS: HCQ markedly increased action potential dispersion, resulted in development of repolarization alternans, and initiated polymorphic ventricular tachycardia. CONCLUSION: The study results further highlight the proarrhythmic effects of HCQ.


Assuntos
Antimaláricos/farmacologia , Frequência Cardíaca/efeitos dos fármacos , Coração/efeitos dos fármacos , Coração/fisiopatologia , Hidroxicloroquina/farmacologia , Animais , Estimulação Cardíaca Artificial , Infecções por Coronavirus/tratamento farmacológico , Cobaias , Coração/diagnóstico por imagem , Coelhos , Técnicas de Cultura de Tecidos , Imagens com Corantes Sensíveis à Voltagem
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