RESUMEN
Reverse zoonotic transmission events of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been described since the start of the pandemic, and the World Organisation for Animal Health (WOAH) designated the detection of SARS-CoV-2 in animals a reportable disease. Eighteen domestic and zoo animals in Great Britain and Jersey were tested by APHA for SARS-CoV-2 during 2020-2023. One domestic cat (Felis catus), three domestic dogs (Canis lupus familiaris), and three Amur tigers (Panthera tigris altaica) from a zoo were confirmed positive during 2020-2021 and reported to the WOAH. All seven positive animals were linked with known SARS-CoV-2 positive human contacts. Characterisation of the SARS-CoV-2 variants by genome sequencing indicated that the cat was infected with an early SARS-CoV-2 lineage. The three dogs and three tigers were infected with the SARS-CoV-2 Delta variant of concern (B.1.617.2). The role of non-human species in the onward transmission and emergence of new variants of SARS-CoV-2 remain poorly defined. Continued surveillance of SARS-CoV-2 in relevant domestic and captive animal species with high levels of human contact is important to monitor transmission at the human-animal interface and to assess their role as potential animal reservoirs.
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Animales de Zoológico , COVID-19 , SARS-CoV-2 , Tigres , Animales , Perros , SARS-CoV-2/genética , SARS-CoV-2/aislamiento & purificación , SARS-CoV-2/clasificación , COVID-19/transmisión , COVID-19/epidemiología , COVID-19/veterinaria , COVID-19/virología , Tigres/virología , Gatos , Animales de Zoológico/virología , Inglaterra/epidemiología , Humanos , Filogenia , Enfermedades de los Perros/virología , Enfermedades de los Perros/epidemiología , Enfermedades de los Perros/transmisión , Zoonosis/virología , Zoonosis/transmisión , Zoonosis/epidemiologíaRESUMEN
The global spread of H5N1 highly pathogenic avian influenza virus (HPAIV) in poultry has caused great economic loss to the poultry farmers and industry with significant pandemic threat. The current study involved production of recombinant HA1 protein of clade 2.3.2.1a H5N1 HPAIV (rH5HA1) in E.coli and evaluation of its protective efficacy in chickens. Purification under denaturing conditions and refolding by dialysis against buffers containing decreasing concentrations of urea was found to preserve the biological activity of the expressed recombinant protein as assessed by hemagglutination assay, Western blot and ELISA. The Montanide ISA 71 VGA adjuvanted rH5HA1 protein was used for immunization of chickens. Humoral response was maintained at a minimum of 4log2 hemagglutination inhibition (HI) titre till 154 days post 2nd booster. We evaluated the protective efficacy of rH5HA1 protein in immunized chickens by challenging them with homologous (2.3.2.1a) and heterologous (2.3.2.1c) clades of H5N1 HPAIV. In both the groups, the HI titre significantly increased (P < 0.05) after challenge and the virus shedding significantly (P < 0.05) reduced between 3rd and 14th day post challenge. The virus shedding ratio in oro-pharyngeal swabs did not differ significantly between both the groups except on 7 days post challenge and during the entire experimental period in cloacal swabs. These results indicate that rH5HA1 was able to induce homologous and cross protective immune response in chickens and could be a potential vaccine candidate used for combating the global spread of H5N1 HPAIV threat. To our knowledge, this is the first study to report immunogenicity and protective efficacy of prokaryotic recombinant H5HA1 protein in chicken.
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Subtipo H5N1 del Virus de la Influenza A , Vacunas contra la Influenza , Gripe Aviar , Animales , Pollos , Escherichia coli/genética , Subtipo H5N1 del Virus de la Influenza A/genética , Vacunas contra la Influenza/genética , Aceite Mineral , Proteínas Recombinantes/genética , Diálisis RenalRESUMEN
Lyssaviruses are an important genus of zoonotic viruses which cause the disease rabies. The United Kingdom is free of classical rabies (RABV). However, bat rabies due to European bat lyssavirus 2 (EBLV-2), has been detected in Daubenton's bats (Myotis daubentonii) in Great Britain since 1996, including a fatal human case in Scotland in 2002. Across Europe, European bat lyssavirus 1 (EBLV-1) is commonly associated with serotine bats (Eptesicus serotinus). Despite the presence of serotine bats across large parts of southern England, EBLV-1 had not previously been detected in this population. However, in 2018, EBLV-1 was detected through passive surveillance in a serotine bat from Dorset, England, using a combination of fluorescent antibody test, reverse transcription-PCR, Sanger sequencing and immunohistochemical analysis. Subsequent EBLV-1 positive serotine bats have been identified in South West England, again through passive surveillance, during 2018, 2019 and 2020. Here, we confirm details of seven cases of EBLV-1 and present similarities in genetic sequence indicating that emergence of EBLV-1 is likely to be recent, potentially associated with the natural movement of bats from the near continent.
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Quirópteros/virología , Lyssavirus/patogenicidad , Animales , Lyssavirus/genética , Rabia/virología , Infecciones por Rhabdoviridae/epidemiología , Infecciones por Rhabdoviridae/virología , Reino Unido/epidemiologíaRESUMEN
PURPOSE: To characterize the prevalence of work-related musculoskeletal disorders (MSD), symptoms, and risk factors among ophthalmologists. METHODS: An online survey was distributed to ophthalmologist members of the Maryland Society of Eye Physicians and Surgeons. The survey consisted of 34 questions on respondent demographics, practice characteristics, pain, and effects of MSD on their practice patterns. Participants were excluded if they were not ophthalmologists or if they had MSD symptoms prior to the start of their ophthalmology career. Demographics and practice patterns were compared for those with or without MSD symptoms using the Welch t test and the Fisher exact test. RESULTS: The survey was completed by 127 of 250 active members (response rate, 51%). Of the 127, 85 (66%) reported experiencing work-related pain, with an average pain level of 4/10. With regard to mean age, height, weight, years in practice, number of patients seen weekly, and hours worked weekly, there was no difference between respondents reporting pain and those without. Those reporting MSD symptoms spent significantly more time in surgery than those who did not (mean of 7.9 vs 5.3 hours/week [P < 0.01]). Fourteen percent of respondents reported plans to retire early due to their symptoms. CONCLUSIONS: A majority of respondents experienced work-related MSD symptoms, which was associated with time spent in surgery. Modifications to the workplace environment focusing on ergonomics, particularly in the operating room, may benefit ophthalmologists.
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Ergonomía/métodos , Enfermedades Musculoesqueléticas/epidemiología , Oftalmólogos/estadística & datos numéricos , Lugar de Trabajo/normas , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Musculoesqueléticas/diagnóstico , Prevalencia , Factores de Riesgo , Encuestas y Cuestionarios , Estados Unidos/epidemiologíaRESUMEN
Basosquamous carcinoma (BSC) is a malignant and aggressive neoplasm with unclear molecular etiology. It is often misdiagnosed as basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) on biopsy as there are unclear histologic criteria for this neoplasm. It has been interchangeably referred to as metatypical BCC and collision tumor, although these entities are different. On histology, BSC consists of basal cells with areas with nests of squamous cells and an intermediate transition zone. The nature of this transition zone is not clearly defined in literature; however, Ber-EP4 staining is diagnostic for BSC. A gradation of Ber-EP4 staining from strongly positive in basaloid areas to weakly positive in an intermediate zone is demonstrated (no staining of squamous areas). Treatment with an array of modalities including wide local excision, Mohs surgery, radiotherapy, and palliative chemotherapy has been performed. We recommend further molecular studies in understanding the genetic mechanisms leading to BSC. For the purpose of good clinical practice, multiple biopsies and immunohistochemical studies should be performed to avoid sampling error that can lead to a misdiagnosis of BSC.
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Biomarcadores de Tumor/análisis , Carcinoma Basoescamoso/diagnóstico , Neoplasias Cutáneas/diagnóstico , Piel/patología , Biomarcadores de Tumor/metabolismo , Biopsia , Carcinoma Basocelular/diagnóstico , Carcinoma Basocelular/patología , Carcinoma Basoescamoso/patología , Carcinoma Basoescamoso/terapia , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/patología , Quimioradioterapia/métodos , Diagnóstico Diferencial , Errores Diagnósticos/prevención & control , Humanos , Inmunohistoquímica , Cirugía de Mohs , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/terapiaRESUMEN
PURPOSE: To determine the amount of time ophthalmologists using Electronic Health Records (EHRs) spend looking at the patient and its correlation on patient satisfaction. METHODS: This prospective cohort study examined 67 patients seeking care at two different ophthalmology clinics. Videos of entire office visits were recorded and each video was graded for amount of time spent by physicians gazing at the patient, computer, paper medical records, or other areas. Videos were also graded for the amount of time examining the patient, and the physician speaking during each visit. A patient satisfaction survey was administered at the end of each office encounter. Time of physician gaze to the patient was correlated to satisfaction outcome measures. RESULTS: Ophthalmologists spent 28.0% ± 21.2% of the visit looking at the computer. Overall, patient satisfaction levels were very high (4.8 ± 0.5, 5-point Likert scale). Ophthalmologists spent the same amount of time looking at patients who were extremely satisfied (28.8% ± 16.7%) as those who were not extremely satisfied (28.8% ± 15.9%). CONCLUSIONS: Ophthalmologists on EHRs spend over a third of each patient visit looking at the computer. However, patient satisfaction levels are very high. The amount of time that the ophthalmologist gazes at the patient or the computer does not appear to have an effect on patient satisfaction in this particular study. Further research still needs to be performed regarding the effects of EHRs on the patient experience. Physicians should continue to be sensitive to their patients' needs and approach the use of EHRs in patient encounters on an individual basis.
RESUMEN
The present study was aimed at generating a reassortant vaccine candidate virus with clade 2.3.2.1 Hemagglutinin (HA) and its evaluation in a challenge study for protection against homologous (2.3.2.1 clade) and heterologous (2.2 clade) highly pathogenic avian influenza (HPAI) H5N1 viruses. Plasmid-based reverse genetics technique was used to rescue a 5â¯+â¯3 reassortant H5N2 strain containing the modified HA of H5N1 (clade 2.3.2.1), the Neuraminidase (NA) of H9N2, the Matrix (M) of H5N1 and the internal genes of A/WSN/33 H1N1. In addition, another 6â¯+â¯2 reassortant virus containing modified HA from H5N1 (clade 2.3.2.1), the NA from H9N2 and the internal genes of A/WSN/33 H1N1 was also rescued. The 5â¯+â¯3 reassortant H5N2 virus could grow to a higher titer in both MDCK cells and chicken eggs compared to the 6â¯+â¯2 reassortant H5N2 virus. The vaccine containing the inactivated 5â¯+â¯3 reassortant H5N2 virus was used in a two-dose immunization regime which protected specific pathogen free (SPF) chickens against two repeated challenges with homologous 2.3.2.1 clade and heterologous 2.2 clade HPAI H5N1 viruses. The 5â¯+â¯3 reassortant H5N2 virus based on clade 2.3.2.1 generated in this study can be effective in protecting chickens in the case of an outbreak caused by antigenically different clade 2.2 HPAI H5N1 viruses and opens the way to explore its applicability as potential vaccine candidate especially in the Asian countries reporting these clades frequently. The study also indicates that sequential immunization can broaden protection level against antigenically diverse strains of H5N1 viruses.
Asunto(s)
Inmunización/métodos , Subtipo H5N1 del Virus de la Influenza A/aislamiento & purificación , Subtipo H5N2 del Virus de la Influenza A/genética , Vacunas contra la Influenza/inmunología , Gripe Aviar/prevención & control , Vacunas de Productos Inactivados/inmunología , Animales , Anticuerpos Antivirales/sangre , Pollos , Perros , Subtipo H5N1 del Virus de la Influenza A/patogenicidad , Subtipo H5N2 del Virus de la Influenza A/crecimiento & desarrollo , Subtipo H5N2 del Virus de la Influenza A/fisiología , Subtipo H9N2 del Virus de la Influenza A/química , Subtipo H9N2 del Virus de la Influenza A/genética , Vacunas contra la Influenza/administración & dosificación , Vacunas contra la Influenza/genética , Gripe Aviar/inmunología , Células de Riñón Canino Madin Darby , Neuraminidasa/genética , Virus Reordenados/genética , Genética Inversa/métodos , Genética Inversa/veterinaria , Vacunas de Productos Inactivados/administración & dosificación , Vacunas de Productos Inactivados/genética , Inactivación de Virus , Esparcimiento de VirusRESUMEN
The recent reports of human infection due to H6 subtype avian influenza viruses (AIV), which are prevalent in terrestrial poultry, indicate evolution of the virus to a possible pandemic strain. Here, we report antigenic and genetic characterization of two H6N2 viruses isolated from apparently healthy domestic ducks in Kerala and Assam, India during 2014 and 2015, respectively. Hemagglutination inhibition assay revealed antigenic divergence between the two isolates, which was corroborated by amino acid differences at 55 positions (15.98%) between their hemagglutinin (HA) 1.The sequence analyses indicated that both the viruses are avian origin with avian receptor specificity, low pathogenic to poultry and sensitive to oseltamivir. However, Kerala14 had V27I mutation marker for amantadine resistance in M2. The Assam15 virus had an additional N-linked glycosylation on HA2 (position 557) compared to Kerala14 virus. Phylogenetic analysis of the HA gene revealed that both the viruses belonged to distinct lineages (Eurasian and Asia II). Phylogeny of neuraminidase and internal gene segments revealed that both the viruses are novel reassortants and are genetically distinct with different gene constellations. The results suggest independent introductions of the two H6N2 viruses into India and migratory wild birds in the Central Asian flyway might be the source of H6N2 viruses in ducks in India. Therefore, continued AIV surveillance in poultry and wild birds is essential for early detection of emergence of novel strains with pandemic potential and control of their spread.
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Patos/virología , Virus de la Influenza A/genética , Gripe Aviar/virología , Virus Reordenados/genética , Animales , India , FilogeniaRESUMEN
INTRODUCTION: Atopic dermatitis (AD) is a common disease in children and adults which causes severe physical discomfort and psychosocial distress. Recently novel therapies for AD have been FDA approved for use which creates the need to review the safety surrounding current FDA approved AD medications. AREAS COVERED: Published clinical studies involving topical and oral FDA approved medications for AD are included in this review. Authors used PubMed research database to search for clinical trials involving AD patients. EXPERT OPINION: AD is a common disease which currently has limited FDA approved medications. Given the chronicity of this disease, medications are needed which control disease while minimizing side effects to allow for long term use. Newer approved medications show promise but safety data is limited given their relatively new utilization for AD.
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Dermatitis Atópica/tratamiento farmacológico , Fármacos Dermatológicos/administración & dosificación , Administración Cutánea , Administración Oral , Adulto , Niño , Dermatitis Atópica/patología , Fármacos Dermatológicos/efectos adversos , Aprobación de Drogas , Humanos , Estados Unidos , United States Food and Drug AdministrationRESUMEN
The association of long non-coding RNAs (lncRNAs) with dengue disease progression is currently unknown. Therefore, the present study aimed to identify lncRNAs in different categories of dengue patients and evaluate their association with dengue disease progression. Herein, we examined the expression profiles of lncRNAs and protein-coding genes between other febrile illness (OFI) and different grade of dengue patients through high-throughput RNA sequencing. We identified Nuclear Enriched Abundant Transcript 1 (NEAT1) as one of the differentially expressed lncRNAs (adjusted P ≤ 0.05 and log-fold change ≥ 2) and subsequently validated the expression by qRT-PCR. The co-expression analysis further revealed that NEAT1 and the coding gene IFI27 were highly co-expressed and negatively correlated with dengue severity. Using regression analysis, we observed that NEAT1 expression was significantly dependent on disease progression (Coefficient = -0.27750, SE Coefficient = 0.07145, and t = -3.88).Further, receiver operating characteristic (ROC) curve revealed that NEAT1 expression could discriminate DI from DS (sensitivity and specificity of 100% (95%CI: 85.69 - 97.22) and area under the curve (AUC) = 0.97). Overall, the results of this study offer the first experimental evidence demonstrating the correlation between lncRNAs and severe dengue phenotype. Monitoring NEAT1and IFI27 expression in PBMC may be useful in understanding dengue virus-induced disease progression.
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Virus del Dengue , Progresión de la Enfermedad , Leucocitos Mononucleares/metabolismo , Proteínas de la Membrana/metabolismo , ARN Largo no Codificante/metabolismo , Dengue Grave/sangre , Adolescente , Adulto , Anciano , Biomarcadores/sangre , Niño , Simulación por Computador , Femenino , Humanos , Masculino , Proteínas de la Membrana/genética , Persona de Mediana Edad , ARN Largo no Codificante/genética , Curva ROC , Análisis de Regresión , Análisis de Secuencia de ARNRESUMEN
INTRODUCTION: Rosacea is a chronic skin condition characterized by transient and persistent erythema of the central face. The symptom of persistent erythema can be particularly frustrating for both patients and physicians as it is difficult to treat. Areas covered: Current treatment options for the treatment of rosacea include metronidazole, azelaic acid, sodium sulfacetamide-sulfur, and brimonidine. Until recently, brimonidine gel was the only option approved specifically for the treatment of facial erythema. However, oxymetazoline hydrochloride 1% cream is a newly FDA approved topical medication for adult rosacea patients. A primarily alpha-1a agonist, oxymetazoline hydrochloride (HCl) is thought to diminish erythema through vasoconstriction. Our paper seeks to evaluate evidence for topical oxymetazoline HCl with respect to its efficacy and safety for its approved indication of treating the persistent erythema associated with rosacea. Expert commentary: While assessment of available clinical trial data indicates that the medication is as effective as other available treatment for controlling rosacea-associated erythema with minimal risk of adverse effects, studies of long-term duration and direct comparison will be necessary to establish its place in treatment guidelines and clinical practice. As further evidence becomes available, the real-world clinical potential of topical oxymetazoline cream will become clearer.
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Eritema/tratamiento farmacológico , Oximetazolina/administración & dosificación , Rosácea/tratamiento farmacológico , Administración Cutánea , Agonistas alfa-Adrenérgicos/administración & dosificación , Agonistas alfa-Adrenérgicos/efectos adversos , Agonistas alfa-Adrenérgicos/farmacología , Fármacos Dermatológicos/administración & dosificación , Fármacos Dermatológicos/efectos adversos , Fármacos Dermatológicos/farmacología , Eritema/etiología , Eritema/patología , Humanos , Oximetazolina/efectos adversos , Oximetazolina/farmacología , Rosácea/patología , Crema para la Piel , Vasoconstricción/efectos de los fármacosRESUMEN
Patients infected with Dengue virus usually present a mild, self-limiting febrile dengue infection (DI) that occasionally leads to a potentially lethal complication, called the severe dengue (DS). The ability to identify the prognostic markers of DS could allow an improved disease intervention and management. To identify the transcriptional signatures associated with the dengue disease progression, we carried out the high-throughput sequencing of the RNA isolated from the peripheral blood mononuclear cells (PBMCs) of the dengue patients of varying severity and compared with that in the patients with other febrile illnesses (OFIs) or the healthy controls. The transcriptional signatures that discriminated the DS patients from OFI and DI patients were broadly related to the pathways involving glycine, serine, and threonine metabolisms, extracellular matrix organization, ubiquitination, and cytokines and inflammatory response. Several upregulated genes in the inflammatory process (MPO, DEFA4, ELANE, AUZ1, CTSG, OLFM4, SLC16A14, and CRISP3) that were associated with the dengue disease progression are known to facilitate leukocyte-mediated migration, and neutrophil activation and degranulation process. High activity of MPO and ELANE in the plasma samples of the follow-up and recovered dengue patients, as well as and the presence of a larger amount of cell-free dsDNA in the DS patients, suggested an association of neutrophil-mediated immunity with dengue disease progression. Careful monitoring of some of these gene transcripts, and control of the activity of proteins encoded by them, may have a great translational significance for the prognosis and management of the dengue patients.
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Dengue/patología , Regulación de la Expresión Génica , Transcripción Genética , Adolescente , Adulto , Secuencia de Bases , Niño , Dengue/metabolismo , Virus del Dengue/clasificación , Virus del Dengue/aislamiento & purificación , Femenino , Humanos , Leucocitos Mononucleares , Masculino , ARN/genética , ARN/metabolismo , Transcriptoma , Adulto JovenRESUMEN
Highly pathogenic avian influenza (H5N8) viruses were detected in waterfowl at 2 zoos in India in October 2016. Both viruses were different 7:1 reassortants of H5N8 viruses isolated in May 2016 from wild birds in the Russian Federation and China, suggesting virus spread during southward winter migration of birds.
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Animales de Zoológico , Subtipo H5N8 del Virus de la Influenza A/genética , Gripe Aviar/virología , Virus Reordenados , Animales , Aves , India/epidemiología , Gripe Aviar/epidemiología , FilogeniaRESUMEN
Highly pathogenic avian influenza (HPAI) H5N1 viruses are a threat to poultry in Asia, Europe, Africa and North America. Here, we report isolation and characterization of H5N1 viruses isolated from ducks and turkeys in Kerala, Chandigarh and Uttar Pradesh, India between November 2014 and March 2015. Genetic and phylogenetic analyses of haemagglutinin gene identified that the virus belonged to a new clade 2.3.2.1c which has not been detected earlier in Indian poultry. The virus possessed molecular signature for high pathogenicity to chickens, which was corroborated by intravenous pathogenicity index of 2.96. The virus was a reassortant which derives its PB2 gene from H9N2 virus isolated in China during 2007-2013. However, the neuraminidase and internal genes are of H5N1 subtype. Phylogenetic and network analysis revealed that after detection in China in 2013/2014, the virus moved to Europe, West Africa and other Asian countries including India. The analyses further indicated multiple introductions of H5N1 virus in Indian poultry and internal spread in Kerala. One of the outbreaks in ducks in Kerala is linked to the H5N1 virus isolated from wild birds in Dubai suggesting movement of virus probably through migration of wild birds. However, the outbreaks in ducks in Chandigarh and Uttar Pradesh were from an unknown source in Asia which also contributed gene pools to the outbreaks in Europe and West Africa. The widespread incidence of the novel H5N1 HPAI is similar to the spread of clade 2.2 ("Qinghai-like") virus in 2005, and should be monitored to avoid threat to animal and public health.
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Brotes de Enfermedades , Subtipo H5N1 del Virus de la Influenza A/genética , Subtipo H9N2 del Virus de la Influenza A/genética , Gripe Aviar/epidemiología , Filogenia , Virus Reordenados/genética , África/epidemiología , Animales , Pollos/virología , Patos/virología , Monitoreo Epidemiológico , Europa (Continente)/epidemiología , Expresión Génica , Glicoproteínas Hemaglutininas del Virus de la Influenza/genética , India/epidemiología , Subtipo H5N1 del Virus de la Influenza A/clasificación , Subtipo H9N2 del Virus de la Influenza A/clasificación , Gripe Aviar/transmisión , Gripe Aviar/virología , Neuraminidasa/genética , Filogeografía , Aves de Corral/virología , Virus Reordenados/clasificación , Pavos/virologíaRESUMEN
A reduced sinoatrial node (SAN) functional reserve underlies the age-associated decline in heart rate acceleration in response to stress. SAN cell function involves an oscillatory coupled-clock system: the sarcoplasmic reticulum (SR), a Ca(2+) clock, and the electrogenic-sarcolemmal membrane clock. Ca(2+)-activated-calmodulin-adenylyl cyclase/CaMKII-cAMP/PKA-Ca(2+) signaling regulated by phosphodiesterase activity drives SAN cells automaticity. SR-generated local calcium releases (LCRs) activate Na(+)/Ca(2+) exchanger in the membrane clock, which initiates the action potential (AP). We hypothesize that SAN cell dysfunctions accumulate with age. We found a reduction in single SAN cell AP firing in aged (20-24 mo) vs. adult (3-4 mo) mice. The sensitivity of the SAN beating rate responses to both muscarinic and adrenergic receptor activation becomes decreased in advanced age. Additionally, age-associated coincident dysfunctions occur stemming from compromised clock functions, including a reduced SR Ca(2+) load and a reduced size, number, and duration of spontaneous LCRs. Moreover, the sensitivity of SAN beating rate to a cAMP stress induced by phosphodiesterase inhibitor is reduced, as are the LCR size, amplitude, and number in SAN cells from aged vs. adult mice. These functional changes coincide with decreased expression of crucial SR Ca(2+)-cycling proteins, including SR Ca(2+)-ATPase pump, ryanodine receptors, and Na(+)/Ca(2+) exchanger. Thus a deterioration in intrinsic Ca(2+) clock kinetics in aged SAN cells, due to deficits in intrinsic SR Ca(2+) cycling and its response to a cAMP-dependent pathway activation, is involved in the age-associated reduction in intrinsic resting AP firing rate, and in the reduction in the acceleration of heart rate during exercise.
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Envejecimiento/fisiología , Calcio/deficiencia , Proteínas Quinasas Dependientes de AMP Cíclico/deficiencia , AMP Cíclico/deficiencia , Transducción de Señal/fisiología , Nodo Sinoatrial/fisiopatología , Potenciales de Acción/fisiología , Animales , Calcio/fisiología , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/deficiencia , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/fisiología , AMP Cíclico/fisiología , Proteínas Quinasas Dependientes de AMP Cíclico/fisiología , Frecuencia Cardíaca/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Modelos Animales , Retículo Sarcoplasmático/fisiología , Estrés Fisiológico/fisiologíaRESUMEN
Recent perspectives on sinoatrial nodal cell (SANC)(*) function indicate that spontaneous sarcoplasmic reticulum (SR) Ca(2+) cycling, i.e. an intracellular "Ca(2+) clock," driven by cAMP-mediated, PKA-dependent phosphorylation, interacts with an ensemble of surface membrane electrogenic molecules ("surface membrane clock") to drive SANC normal automaticity. The role of AC-cAMP-PKA-Ca(2+) signaling cascade in mouse, the species most often utilized for genetic manipulations, however, has not been systematically tested. Here we show that Ca(2+) cycling proteins (e.g. RyR2, NCX1, and SERCA2) are abundantly expressed in mouse SAN and that spontaneous, rhythmic SR generated local Ca(2+) releases (LCRs) occur in skinned mouse SANC, clamped at constant physiologic [Ca(2+)]. Mouse SANC also exhibits a high basal level of phospholamban (PLB) phosphorylation at the PKA-dependent site, Serine16. Inhibition of intrinsic PKA activity or inhibition of PDE in SANC, respectively: reduces or increases PLB phosphorylation, and markedly prolongs or reduces the LCR period; and markedly reduces or accelerates SAN spontaneous firing rate. Additionally, the increase in AP firing rate by PKA-dependent phosphorylation by ß-adrenergic receptor (ß-AR) stimulation requires normal intracellular Ca(2+) cycling, because the ß-AR chronotropic effect is markedly blunted when SR Ca(2+) cycling is disrupted. Thus, AC-cAMP-PKA-Ca(2+) signaling cascade is a major mechanism of normal automaticity in mouse SANC.