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The eye lens is responsible for focusing objects at various distances onto the retina and its refractive power is determined by its surface curvature as well as its internal gradient refractive index (GRIN). The lens continues to grow with age resulting in changes to the shape and to the GRIN profile. The present study aims to investigate how the ageing process may influence lens optical development. Murine lenses of accelerated senescence-prone strain (SAMP8) aged from 4 to 50 weeks; senescence-resistant strain (SAMR1) aged from 5 to 52 weeks as well as AKR strain (served as control) aged from 6 to 70 weeks were measured using the X-ray interferometer at the SPring-8 synchrotron Japan within three consecutive years from 2020 to 2022. Three dimensional distributions of the lens GRIN were reconstructed using the measured data and the lens shapes were determined using image segmentation in MatLab. Variations in the parameters describing the lens shape and the GRIN profile with age were compared amongst three mouse strains. With advancing age, both the lens anterior and posterior surface flattens and the lens sagittal thickness increase in all three mouse strains (Anterior radius of curvature increase at 0.008 mm/week, 0.007 mm/week and 0.002 mm/week while posterior radius of curvature increase at 0.002 mm/week, 0.007 mm/week and 0.003 mm/week respectively in AKR, SAMP8 and SAMR1 lenses). Compared with the AKR strain, the SAMP8 samples demonstrate a higher rate of increase in the posterior curvature radius (0.007 mm/week) and the thickness (0.015 mm/week), whilst the SAMR1 samples show slower increases in the anterior curvature radius (0.002 mm/week) and its thickness (0.013 mm/week). There are similar age-related trends in GRIN shape in the radial direction (in all three types of murine lenses nr2 and nr6 increase with age while nr4 decrease with age consistently) but not in the axial direction amongst three mouse strains (nz1 of AKR lens decrease while of SAMP8 and SAMR1 increase with age; nz2 of all three models increase with age; nz3 of AKR lens increase while of SAMP8 and SAMR1 decrease with age). The ageing process can influence the speed of lens shape change and affect the GRIN profile mainly in the axial direction, contributing to an accelerated decline rate of the optical power in the senescence-prone strain (3.5 D/week compared to 2.3 D/week in the AKR control model) but a retardatory decrease in the senescence-resistant strain (2.1 D/week compared to the 2.3D/week in the AKR control model).
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Envejecimiento , Cristalino , Ratones , Animales , JapónRESUMEN
BACKGROUND: The rapid increase in the number of heart failure (HF) patients in parallel with the increase in the number of older people is receiving attention worldwide. HF not only increases mortality but decreases quality of life, creating medical and social problems. Thus, it is necessary to define molecular mechanisms underlying HF development and progression. HMGB2 is a member of the high-mobility group superfamily characterized as nuclear proteins that bind DNA to stabilize nucleosomes and promote transcription. A recent in vitro study revealed that HMGB2 loss in cardiomyocytes causes hypertrophy and increases HF-associated gene expression. However, it's in vivo function in the heart has not been assessed. MethodsâandâResults: Western blotting analysis revealed increased HMGB2 expression in heart tissues undergoing pressure overload by transverse aorta constriction (TAC) in mice. Hmgb2 homozygous knockout (Hmgb2-/-) mice showed cardiac dysfunction due to AKT inactivation and decreased sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a activity. Compared to wild-type mice, Hmgb2-/- mice had worsened cardiac dysfunction after TAC surgery, predisposing mice to HF development and progression. CONCLUSIONS: This study demonstrates that upregulation of cardiac HMGB2 is an adaptive response to cardiac stress, and that loss of this response could accelerate cardiac dysfunction, suggesting that HMGB2 plays a cardioprotective role.
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Proteína HMGB2/análisis , Insuficiencia Cardíaca/etiología , Animales , Western Blotting , Cardiotónicos/análisis , Cardiotónicos/farmacología , Constricción Patológica/complicaciones , Proteína HMGB2/genética , Proteína HMGB2/farmacología , Insuficiencia Cardíaca/prevención & control , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Proto-Oncogénicas c-akt/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismoRESUMEN
Varying temperature affects cardiac systolic and diastolic function and the left ventricular (LV) pressure-time curve (PTC) waveform that includes information about LV inotropism and lusitropism. Our proposed half-logistic (h-L) time constants obtained by fitting using h-L functions for four segmental phases (Phases I-IV) in the isovolumic LV PTC are more useful indices for estimating LV inotropism and lusitropism during contraction and relaxation periods than the mono-exponential (m-E) time constants at normal temperature. In this study, we investigated whether the superiority of the goodness of h-L fits remained even at hypothermia and hyperthermia. Phases I-IV in the isovolumic LV PTCs in eight excised, cross-circulated canine hearts at 33, 36, and 38 °C were analyzed using h-L and m-E functions and the least-squares method. The h-L and m-E time constants for Phases I-IV significantly shortened with increasing temperature. Curve fitting using h-L functions was significantly better than that using m-E functions for Phases I-IV at all temperatures. Therefore, the superiority of the goodness of h-L fit vs. m-E fit remained at all temperatures. As LV inotropic and lusitropic indices, temperature-dependent h-L time constants could be more useful than m-E time constants for Phases I-IV.
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Fiebre/fisiopatología , Corazón/fisiología , Hipotermia/fisiopatología , Contracción Miocárdica/fisiología , Función Ventricular Izquierda/fisiología , Animales , Circulación Cruzada , Perros , Modelos LogísticosRESUMEN
The Na+/Ca2+ exchanger 1 (NCX1) is an essential Ca2+ efflux system in cardiomyocytes. Although NCX1 is distributed throughout the sarcolemma, a subpopulation of NCX1 is localized to transverse (T)-tubules. There is growing evidence that T-tubule disorganization is a causal event that shifts the transition from hypertrophy to heart failure (HF). However, the detailed molecular mechanisms have not been clarified. Previously, we showed that induced NCX1 expression in pressure-overloaded hearts attenuates defective excitation-contraction coupling and HF progression. Here, we examined the effects of induced NCX1 overexpression on the spatial distribution of L-type Ca2+ channels (LTCCs) and junctophilin-2 (JP2), a structural protein that connects the T-tubule and sarcoplasmic reticulum membrane, in pressure-overloaded hearts. Quantitative analysis showed that the regularity of NCX1 localization was significantly decreased at 8 weeks after transverse aortic constriction (TAC)-surgery; however, T-tubule organization and the regularities of LTCC and JP2 immunofluorescent signals were maintained at this time point. These observations demonstrated that release of NCX1 from the T-tubule area occurred before the onset of T-tubule disorganization and LTCC and JP2 mislocalization. Moreover, induced NCX1 overexpression at 8 weeks post-TAC not only recovered NCX1 regularity but also prevented the decrease in LTCC and JP2 regularities at 16 weeks post-TAC. These results suggested that NCX1 may play an important role in the proper spatial distribution of LTCC and JP2 in T-tubules in the context of pressure-overloading.
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Canales de Calcio Tipo L/metabolismo , Ventrículos Cardíacos/metabolismo , Hipertrofia Ventricular Izquierda/metabolismo , Proteínas de la Membrana/metabolismo , Microtúbulos/metabolismo , Proteínas Musculares/metabolismo , Intercambiador de Sodio-Calcio/metabolismo , Animales , Masculino , Ratones , Ratones Transgénicos , Miocitos Cardíacos , Especificidad de Órganos , Distribución Tisular , Regulación hacia ArribaRESUMEN
The liquid junction potential (LJP), the phenomenon that occurs when two electrolyte solutions of different composition come into contact, prevents accurate measurements in potentiometry. The effect of the LJP is usually remarkable in measurements of diluted solutions with low buffering capacities or low ion concentrations. Our group has constructed a simple method to eliminate the LJP by exerting spatiotemporal control of a liquid junction (LJ) formed between two solutions, a sample solution and a baseline solution (BLS), in a flow-through-type differential pH sensor probe. The method was contrived based on microfluidics. The sensor probe is a differential measurement system composed of two ion-sensitive field-effect transistors (ISFETs) and one Ag/AgCl electrode. With our new method, the border region of the sample solution and BLS is vibrated in order to mix solutions and suppress the overshoot after the sample solution is suctioned into the sensor probe. Compared to the conventional method without vibration, our method shortened the settling time from over two min to 15 s and reduced the measurement error by 86% to within 0.060 pH. This new method will be useful for improving the response characteristics and decreasing the measurement error of many apparatuses that use LJs.
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Electrodos , Concentración de Iones de Hidrógeno , Potenciometría/métodosRESUMEN
Investigating ventricular diastolic properties is crucial for understanding the physiological cardiac functions in organisms and unraveling the pathological mechanisms of cardiovascular disorders. Ventricular stiffness, a fundamental parameter that defines ventricular diastolic functions in chordates, is typically analyzed using the end-diastolic pressure-volume relationship (EDPVR). However, comparing ventricular stiffness accurately across chambers of varying maximum volume capacities has been a long-standing challenge. As one of the solutions to this problem, we propose calculating a relative ventricular stiffness index by applying an exponential approximation formula to the EDPVR plot data of the relationship between ventricular pressure and values of normalized ventricular volume by the ventricular weight. This article reviews the potential, utility, and limitations of using normalized EDPVR analysis in recent studies. Herein, we measured and ranked ventricular stiffness in differently sized and shaped chambers using ex vivo ventricular pressure-volume analysis data from four animals: Wistar rats, red-eared slider turtles, masu salmon, and cherry salmon. Furthermore, we have discussed the mechanical effects of intracellular and extracellular viscoelastic components, Titin (Connectin) filaments, collagens, physiological sarcomere length, and other factors that govern ventricular stiffness. Our review provides insights into the comparison of ventricular stiffness in different-sized ventricles between heterologous and homologous species, including non-model organisms.
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Ventrículos Cardíacos , Animales , Ratas , Diástole/fisiología , Ventrículos Cardíacos/fisiopatología , Especificidad de la Especie , Función Ventricular/fisiología , Tortugas , SalmónRESUMEN
Connectin (also known as titin) is a giant striated muscle protein that functions as a molecular spring by providing elasticity to the sarcomere. Novex-3 is a short splice variant of connectin whose physiological function remains unknown. We have recently demonstrated using in vitro analyses that in addition to sarcomere expression, novex-3 was also expressed in cardiomyocyte nuclei exclusively during fetal life, where it provides elasticity/compliance to cardiomyocyte nuclei and promotes cardiomyocyte proliferation in the fetus, suggesting a non-sarcomeric function. Here, we analyzed novex-3 knockout mice to assess the involvement of this function in cardiac pathophysiology in vivo. Deficiency of novex-3 compromised fetal cardiomyocyte proliferation and induced the enlargement of individual cardiomyocytes in neonates. In adults, novex-3 deficiency resulted in chamber dilation and systolic dysfunction, associated with Ca2+ dysregulation, resulting in a reduced life span. Mechanistic analyses revealed a possible association between impaired proliferation and abnormal nuclear mechanics, including stiffer nuclei positioned peripherally with stabilized circumnuclear microtubules in knockout cardiomyocytes. Although the underlying causal relationships were not fully elucidated, these data show that novex-3 has a vital non-sarcomeric function in cardiac pathophysiology and serves as an early contributor to cardiomyocyte proliferation.
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Núcleo Celular , Proliferación Celular , Conectina , Ratones Noqueados , Miocitos Cardíacos , Animales , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Ratones , Núcleo Celular/metabolismo , Conectina/genética , Conectina/metabolismo , Sarcómeros/metabolismo , Proteínas Musculares/metabolismo , Proteínas Musculares/genética , Proteínas Musculares/deficiencia , Calcio/metabolismoRESUMEN
Although propofol is commonly used for general anesthesia, its direct effects on left ventricular (LV) contractility and energetics remain unknown. Accordingly, we studied the effects of intracoronary propofol on excised cross-circulated canine hearts using the framework of the Emax (a contractility index)-PVA (systolic pressure-volume area, a measure of total mechanical energy)-V(O2) (myocardial oxygen consumption per beat) relationship. We obtained 1) the V(O2)-PVA relationship of isovolumic contractions with varied LV volumes at a constant Emax, 2) the V(O2)-PVA relationship with varied LV volumes at a constant intracoronary concentration of propofol, and 3) the V(O2)-PVA relationship under increased intracoronary concentrations of either propofol or CaCl(2) at a constant LV volume to assess the cardiac mechanoenergetic effects of propofol. We found that propofol decreased Emax dose-dependently. The slope of the linear V(O2)-PVA relationship (oxygen cost of PVA) remained unchanged by propofol. The PVA-independent V(O2)-Emax relationship (oxygen cost of Emax) was the same for propofol and Ca(2+). In conclusion, propofol showed a direct negative inotropic effect on LV. At its clinical concentrations, decreases in contractility by propofol were relatively small. Propofol shows mechanoenergetic effects on the LV that are similar to those of Ca(2+) blockers or ß-antagonists-i.e., it exerts negative inotropic effects without changing the oxygen costs of Emax and PVA.
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Anestésicos Intravenosos/farmacología , Metabolismo Energético/efectos de los fármacos , Ventrículos Cardíacos/efectos de los fármacos , Contracción Miocárdica/efectos de los fármacos , Consumo de Oxígeno/efectos de los fármacos , Propofol/farmacología , Animales , Circulación Cruzada , Perros , Técnicas In VitroRESUMEN
Ventricular diastolic mechanical properties are important determinants of cardiac function and are optimized by changes in cardiac structure and physical properties. Oncorhynchus masou masou is an anadromous migratory fish of the Salmonidae family, and several ecological studies on it have been conducted; however, the cardiac functions of the fish are not well known. Therefore, we investigated ventricular diastolic function in landlocked (masu salmon) and sea-run (cherry salmon) types at 29-30 months post fertilization. Pulsed-wave Doppler echocardiography showed that the atrioventricular inflow waveforms of cherry salmon were biphasic with early diastolic filling and atrial contraction, whereas those of masu salmon were monophasic with atrial contraction. In addition, end-diastolic pressure-volume relationship analysis revealed that the dilatability per unit myocardial mass of the ventricle in cherry salmon was significantly suppressed compared to that in masu salmon, suggesting that the ventricle of the cherry salmon was relatively stiffer (relative ventricular stiffness index; p = 0.0263). Contrastingly, the extensibility of cardiomyocytes, characterized by the expression pattern of Connectin isoforms in their ventricles, was similar in both types. Histological analysis showed that the percentage of the collagen accumulation area in the compact layer of cherry salmon increased compared with that of the masu salmon, which may contribute to ventricle stiffness. Although the heart mass of cherry salmon was about 11-fold greater than that of masu salmon, there was no difference in the morphology of the isolated cardiomyocytes, suggesting that the heart of the cherry salmon grows by cardiomyocyte proliferation, but not cell hypertrophy. The cardiac physiological function of the teleosts varies with differences in their developmental processes and life history. Our multidimensional analysis of the O. masou heart may provide a clue to the process by which the heart acquires a biphasic blood-filling pattern, i.e., a ventricular diastolic suction.
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Oncorhynchus , Animales , Oncorhynchus/fisiología , HemodinámicaRESUMEN
Introduction of fetal cell cycle genes into damaged adult hearts has emerged as a promising strategy for stimulating proliferation and regeneration of postmitotic adult cardiomyocytes. We have recently identified Fam64a as a fetal-specific cell cycle promoter in cardiomyocytes. Here, we analyzed transgenic mice maintaining cardiomyocyte-specific postnatal expression of Fam64a when endogenous expression was abolished. Despite an enhancement of cardiomyocyte proliferation, these mice showed impaired cardiomyocyte differentiation during postnatal development, resulting in cardiac dysfunction in later life. Mechanistically, Fam64a inhibited cardiomyocyte differentiation by repressing Klf15, leading to the accumulation of undifferentiated cardiomyocytes. In contrast, introduction of Fam64a in differentiated adult wildtype hearts improved functional recovery upon injury with augmented cell cycle and no dedifferentiation in cardiomyocytes. These data demonstrate that Fam64a inhibits cardiomyocyte differentiation during early development, but does not induce de-differentiation in once differentiated cardiomyocytes, illustrating a promising potential of Fam64a as a cell cycle promoter to attain heart regeneration.
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Abnormal mitochondrial fragmentation by dynamin-related protein1 (Drp1) is associated with the progression of aging-associated heart diseases, including heart failure and myocardial infarction (MI). Here, we report a protective role of outer mitochondrial membrane (OMM)-localized E3 ubiquitin ligase MITOL/MARCH5 against cardiac senescence and MI, partly through Drp1 clearance by OMM-associated degradation (OMMAD). Persistent Drp1 accumulation in cardiomyocyte-specific MITOL conditional-knockout mice induced mitochondrial fragmentation and dysfunction, including reduced ATP production and increased ROS generation, ultimately leading to myocardial senescence and chronic heart failure. Furthermore, ischemic stress-induced acute downregulation of MITOL, which permitted mitochondrial accumulation of Drp1, resulted in mitochondrial fragmentation. Adeno-associated virus-mediated delivery of the MITOL gene to cardiomyocytes ameliorated cardiac dysfunction induced by MI. Our findings suggest that OMMAD activation by MITOL can be a therapeutic target for aging-associated heart diseases, including heart failure and MI.
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Endothelial glycocalyx (GCX) has been reported as a protective factor for vascular endothelial cells (VEC) in diabetes and hypertension. However, the involvement of GCX impairment in ocular vasculopathy remains unclear. We evaluated the changes in the GCX thicknesses of the retinal and choroidal capillaries in rats with diabetes and hypertension by cationic colloidal iron staining using a transmission electron microscope. In the control group, the mean (standard error of the mean) thicknesses of retinal and choroidal GCX were 60.2 (1.5) nm and 84.3 (3.1) nm, respectively. The diabetic rats showed a significant decrease of GCX thickness in the retina, but not in the choroid, compared to controls (28.3 (0.3) nm, p<0.01 and 77.8 (1.4) nm, respectively). In the hypertensive rats, both retinal and choroidal GCX were significantly decreased compared to the control values (10.9 (0.4) nm and 13.2 (1.0) nm, respectively, both p<0.01). Moreover, we could visualize the adhesion of leukocytes and platelets on the luminal surface of VEC, at the site where the GCX was markedly degraded. These findings suggest that the GCX prevents adhesion of leukocytes and platelets to the VEC surface, and this impairment may lead to ocular vasculopathy in diabetes and hypertension.
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Capilares/metabolismo , Coroides/irrigación sanguínea , Diabetes Mellitus Experimental/metabolismo , Endotelio Vascular/metabolismo , Glicocálix/metabolismo , Hipertensión/metabolismo , Vasos Retinianos/metabolismo , Animales , Plaquetas/patología , Plaquetas/ultraestructura , Capilares/patología , Capilares/ultraestructura , Adhesión Celular , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/patología , Modelos Animales de Enfermedad , Endotelio Vascular/patología , Endotelio Vascular/ultraestructura , Hipertensión/complicaciones , Hipertensión/patología , Leucocitos/patología , Leucocitos/ultraestructura , Masculino , Microscopía Electrónica de Transmisión , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Estreptozocina , Enfermedades Vasculares/etiología , Enfermedades Vasculares/metabolismo , Enfermedades Vasculares/patologíaRESUMEN
Impaired deformability might contribute to the accumulation of activated leukocytes within pulmonary microcapillaries, leading to acute lung injury. The purpose of our study was to investigate changes in leukocyte deformability during periods of inflammation after esophagectomy. The study group comprised 20 patients who underwent esophagectomy. Changes in leukocyte deformability were investigated by examining filtration through a silicon microchannel, which simulated human pulmonary microcapillaries. Changes in the neutrophil cytoskeleton were investigated by measuring neutrophil F-actin assembly. The severity of patient clinical outcome was evaluated by the lung injury score. Leukocyte filtration through the microchannel was significantly weaker in esophagectomy patients than in healthy subjects (p<0.01). After esophagectomy, filtration was further impaired compared with preoperative values (p<0.05). The neutrophil F-actin content was higher in patients than in controls (p<0.01), and increased after esophagectomy compared with preoperative values (p<0.01). We concluded that circulating leukocytes showed reduced deformability and appeared to be sequestered within microcapillaries after esophagectomy. Changes in neutrophil cytoskeleton were considered to be responsible for the reduced deformability. Leukocyte accumulation within pulmonary microcapillaries might be related to the pathogenesis of lung injury after esophagectomy.
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Lesión Pulmonar Aguda/inmunología , Esofagectomía/efectos adversos , Neutrófilos/fisiología , Complicaciones Posoperatorias/inmunología , Lesión Pulmonar Aguda/fisiopatología , Estudios de Casos y Controles , Femenino , Citometría de Flujo , Hemorreología/inmunología , Humanos , Inflamación/fisiopatología , Masculino , Microcirculación/inmunología , Técnicas Analíticas Microfluídicas , Neutrófilos/ultraestructura , Circulación Pulmonar/inmunologíaRESUMEN
Fishy odor of fish flesh (meat) presents a severe problem for marine production. The main cause of fishy odor is trimethylamine (TMA), which increases during storage. It is produced from trimethylamine oxide (TMAO), an osmosis-regulating substance in fish cells that functions by a reduction reaction. Bacterial growth in fish meat increases TMA. Its odor reduces the commercial value of the meat. Technologies for its regulation and elimination are desired. This chapter presents a description of the use of lactic acid to eliminate TMA. The lactic acid is producible safely by bacteria during food processing using picric acid-toluene.A method of eliminating TMA was demonstrated using Lactobacillus plantarum H78. Furthermore, an assay method was explained for reducing TMA in fish meat by fermenting the H78 strain.
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Biotransformación , Explotaciones Pesqueras , Lactobacillales/aislamiento & purificación , Lactobacillales/metabolismo , Metilaminas/metabolismo , Odorantes , Metilaminas/aislamiento & purificación , Alimentos MarinosRESUMEN
Heart failure is the major cause of death for muscular dystrophy patients, however, the molecular pathomechanism remains unknown. Here, we show the detailed molecular pathogenesis of muscular dystrophy-associated cardiomyopathy in mice lacking the fukutin gene (Fktn), the causative gene for Fukuyama muscular dystrophy. Although cardiac Fktn elimination markedly reduced α-dystroglycan glycosylation and dystrophin-glycoprotein complex proteins in sarcolemma at all developmental stages, cardiac dysfunction was observed only in later adulthood, suggesting that membrane fragility is not the sole etiology of cardiac dysfunction. During young adulthood, Fktn-deficient mice were vulnerable to pathological hypertrophic stress with downregulation of Akt and the MEF2-histone deacetylase axis. Acute Fktn elimination caused severe cardiac dysfunction and accelerated mortality with myocyte contractile dysfunction and disordered Golgi-microtubule networks, which were ameliorated with colchicine treatment. These data reveal fukutin is crucial for maintaining myocyte physiology to prevent heart failure, and thus, the results may lead to strategies for therapeutic intervention.
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Insuficiencia Cardíaca/etiología , Músculo Esquelético/patología , Distrofias Musculares/complicaciones , Miocitos Cardíacos/patología , Transferasas/genética , Adulto , Factores de Edad , Animales , Animales Recién Nacidos , Sistemas CRISPR-Cas/genética , Células Cultivadas , Modelos Animales de Enfermedad , Distroglicanos/metabolismo , Femenino , Técnicas de Inactivación de Genes , Glicosilación , Células HEK293 , Insuficiencia Cardíaca/patología , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/patología , Humanos , Masculino , Proteínas de la Membrana/genética , Ratones , Ratones Noqueados , Músculo Esquelético/citología , Distrofias Musculares/genética , Distrofias Musculares/patología , Contracción Miocárdica/genética , Miocitos Cardíacos/citología , Cultivo Primario de Células , Sarcolema/patología , Transferasas/metabolismoRESUMEN
Hypovolemia results in hypotension due to a decrease in left ventricular (LV) stroke volume. We have showed a logistic relaxation time constant (tauL) that is a superior lusitropic index during the LV pressure (LVP) falling phase independent of LV preload compared with the conventional monoexponential relaxation time constant (tauE). In the present study, we investigated the effect of decreasing LV preload on tauL and tauE during the LV contraction and other relaxation phases. The isovolumic LVP curve was analyzed at LV Volumes (LVVs) of 18, 14, and 10 mL during 2-Hz pacing in seven excised, cross-circulated canine hearts. TauL and tauE were evaluated using logistic and monoexponential analyses of the four phases of the cardiac cycle: the period from the onset to the maximum time derivative of LVP (LV dP/dtmax), from LV dP/dtmax to peak LVP, from peak LVP to the minimum time derivative of LVP (LV dP/dtmin), and from LV dP/dtmin to LV end-diastolic pressure. TauL and tauE during the four phases did not change significantly with the decrease in LVV. During the change in LVV, the logistic function always fit significantly better compared with the monoexponential function. In conclusion, hypovolemia does not affect the speed of isovolumic LV contraction and relaxation. Each phase of the LVP curve is of a logistic nature. TauL is as a useful index for estimation of the speed of alteration during each phase of cardiac systole and diastole.
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Hipovolemia/fisiopatología , Disfunción Ventricular Izquierda/fisiopatología , Animales , Volumen Sanguíneo/fisiología , Circulación Cruzada , Perros , Modelos Logísticos , Modelos Cardiovasculares , Contracción Miocárdica/fisiologíaRESUMEN
Human vascular endothelial cells form the interface between the bloodstream and vessel walls and are continuously subjected to mechanical stimulation. When endothelial cells are stretched cyclically, along one axis, they align perpendicular to the axis of stretch. We previously reported that applying a cyclic, uni-axial strain to cells induced tyrosine phosphorylation of focal adhesion kinase and stimulated mitogen-activated protein kinase. However, it is difficult to quantify and analyze the spatial distribution of tyrosine phosphorylation in these cells, as they form focal adhesions randomly. In this study, we developed a system to overcome this problem by preparing individual, uniform, patterned cells that could be stretched cyclically and uni-axially. We constructed polydimethylsiloxane stretch chambers and used microcontact printing technology to imprint a pattern of 2 microm fibronectin dots (10 lines x 10 columns in a 38 microm square) before seeding them with human umbilical vein endothelial cells (HUVEC). We found that most HUVEC attached to the patterned dots after 2h and were similar in size and morphology, based on phase-contrast microscopy. In this system we were able to statistically analyze tyrosine phosphorylation and actin polymerization in these patterned cells, when subjected to a cyclic, uni-axial strain, using fluorescent microscopy.
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Adhesión Celular/fisiología , Técnicas de Cultivo de Célula/métodos , Dimetilpolisiloxanos/química , Células Endoteliales/citología , Células Endoteliales/fisiología , Fibronectinas/farmacología , Mecanotransducción Celular/fisiología , Nylons/química , Adhesión Celular/efectos de los fármacos , Polaridad Celular/efectos de los fármacos , Células Cultivadas , Células Endoteliales/efectos de los fármacos , Fibronectinas/química , Humanos , Mecanotransducción Celular/efectos de los fármacosRESUMEN
Luteolin is a flavonoid present in plants in the form of aglycone or glucosides. In this study, luteolin glucosides (i.e., luteolin-7- O-ß-d-glucoside, luteolin-7- O-[2-(ß-d-apiosyl)-ß-d-glucoside], and luteolin-7- O-[2-(ß-d-apiosyl)-6-malonyl-ß-d-glucoside]) prepared from green pepper leaves as well as luteolin aglycone were orally administered to rats. Regardless of the administered luteolin form, luteolin glucuronides were mainly detected from plasma and organs. Subsequently, luteolin aglycone, the most absorbed form of luteolin in rats, was orally administered to humans. As a result, luteolin-3'- O-sulfate was mainly identified from plasma, suggesting that not only luteolin form but also animal species affect the absorption and metabolism of luteolin. When LPS-treated RAW264.7 cells were treated with luteolin glucuronides and luteolin sulfate (the characteristic metabolites identified from rats and humans, respectively), the different luteolin conjugates were metabolized in different ways, suggesting that such difference in metabolism results in their difference in anti-inflammatory effects.
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Glucósidos/metabolismo , Luteolina/metabolismo , Administración Oral , Adulto , Animales , Capsicum/química , Cromatografía Liquida , Humanos , Masculino , Ratones , Persona de Mediana Edad , Estructura Molecular , Hojas de la Planta/química , Células RAW 264.7 , Ratas , Ratas Sprague-Dawley , Espectrometría de Masas en Tándem , Adulto JovenRESUMEN
Loss of cardiomyocyte proliferative capacity after birth is a major obstacle for therapeutic heart regeneration in adult mammals. We and others have recently shown the importance of hypoxic in utero environments for active foetal cardiomyocyte proliferation. Here, we report the unexpected expression of novex-3, the short splice variant of the giant sarcomeric protein connectin (titin), in the cardiomyocyte nucleus specifically during the hypoxic foetal stage in mice. This nuclear localisation appeared to be regulated by the N-terminal region of novex-3, which contains the nuclear localisation signal. Importantly, the nuclear expression of novex-3 in hypoxic foetal cardiomyocytes was repressed at the postnatal stage following the onset of breathing and the resulting elevation of oxygen tension, whereas the sarcomeric expression remained unchanged. Novex-3 knockdown in foetal cardiomyocytes repressed cell cycle-promoting genes and proliferation, whereas novex-3 overexpression enhanced proliferation. Mechanical analysis by atomic force microscopy and microneedle-based tensile tests demonstrated that novex-3 expression in hypoxic foetal cardiomyocytes contributes to the elasticity/compliance of the nucleus at interphase and facilitates proliferation, by promoting phosphorylation-induced disassembly of multimer structures of nuclear lamins. We propose that novex-3 has a previously unrecognised role in promoting cardiomyocyte proliferation specifically at the hypoxic foetal stage.
Asunto(s)
Conectina/metabolismo , Hipoxia/metabolismo , Miocitos Cardíacos/metabolismo , Animales , Biomarcadores , Ciclo Celular/genética , Núcleo Celular/metabolismo , Conectina/química , Conectina/genética , Técnica del Anticuerpo Fluorescente , Expresión Génica , Hipoxia/genética , Interfase/genética , Laminas/química , Laminas/metabolismo , Ratones , Miocitos Cardíacos/citología , Fosforilación , Regiones Promotoras Genéticas , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Señales de Clasificación de Proteína , Transporte de ProteínasRESUMEN
Connectin, also called titin, is the largest protein with a critical function as a molecular spring during contraction and relaxation of striated muscle; its mutation leads to severe myopathy and cardiomyopathy. To uncover the cause of this pathogenesis, zebrafish have recently been used as disease models because they are easier to genetically modify than mice. Although the gene structures and putative primary structures of zebrafish connectin have been determined, the actual primary structures of zebrafish connectin in heart and skeletal muscles remain unclear because of its large size and the PCR amplification-associated difficulties. In this research, using RT-PCR amplification from zebrafish heart and skeletal muscles, we determined the complete primary structures of zebrafish connectin in the I-band region at which mechanical property is modulated by alternative splicing. Our results showed that the domain structures of zebrafish connectins were largely similar to those of human connectins; however, the splicing pathways in the middle-Ig segment and the PEVK segment were highly diverse in every isoform. We also found that a set of 10 Ig domains in the middle-Ig segment of zebrafish connectin had been triplicated in human connectin. Because these triplicate regions are expressed in human leg and diaphragm, our findings may provide insight into the establishment of walking with limbs and lung respiration during tetrapod evolution.