Comparative analysis of ventricular stiffness across species.

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.

Optical development in the murine eye lens of accelerated senescence-prone SAMP8 and senescence-resistant SAMR1 strains.

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).

Cardiac hemodynamics and ventricular stiffness of sea-run cherry salmon (Oncorhynchus masou masou) differ critically from those of landlocked masu salmon.

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.

Protective roles of MITOL against myocardial senescence and ischemic injury partly via Drp1 regulation.

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.

Postnatal expression of cell cycle promoter Fam64a causes heart dysfunction by inhibiting cardiomyocyte differentiation through repression of Klf15.

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.

Elimination of fukutin reveals cellular and molecular pathomechanisms in muscular dystrophy-associated heart failure.

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.

Loss of Endogenous HMGB2 Promotes Cardiac Dysfunction and Pressure Overload-Induced Heart Failure in Mice.

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. Methods and Results: 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.

Isolation of Lactic Acid Bacteria Eliminating Trimethylamine (TMA) for Application to Fishery Processing.

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.

Absorption and Metabolism of Luteolin in Rats and Humans in Relation to in Vitro Anti-inflammatory Effects.

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.

Nuclear connectin novex-3 promotes proliferation of hypoxic foetal cardiomyocytes.

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.

Fam64a is a novel cell cycle promoter of hypoxic fetal cardiomyocytes in mice.

Fetal cardiomyocytes actively proliferate to form the primitive heart in utero in mammals, but they stop dividing shortly after birth. The identification of essential molecules maintaining this active cardiomyocyte proliferation is indispensable for potential adult heart regeneration. A recent study has shown that this proliferation depends on a low fetal oxygen condition before the onset of breathing at birth. We have established an isolation protocol for mouse fetal cardiomyocytes, performed under strict low oxygen conditions to mimic the intrauterine environment, that gives the highest proliferative activities thus far reported. Oxygen exposure during isolation/culture markedly inhibited cell division and repressed cell cycle-promoting genes, and subsequent genome-wide analysis identified Fam64a as a novel regulatory molecule. Fam64a was abundantly expressed in hypoxic fetal cardiomyocyte nuclei, but this expression was drastically repressed by oxygen exposure, and in postnatal cardiomyocytes following the onset of breathing and the resulting elevation of oxygen tension. Fam64a knockdown inhibited and its overexpression enhanced cardiomyocyte proliferation. Expression of a non-degradable Fam64a mutant suggested that optimum Fam64a expression and subsequent degradation by anaphase-promoting complex/cyclosome (APC/C) during the metaphase-to-anaphase transition are required for fetal cardiomyocyte division. We propose that Fam64a is a novel cell cycle promoter of hypoxic fetal cardiomyocytes in mice.

Temperature-dependent inotropic and lusitropic indices based on half-logistic time constants for four segmental phases in isovolumic left ventricular pressure-time curve in excised, cross-circulated canine heart.

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.

Complete primary structure of the I-band region of connectin at which mechanical property is modulated in zebrafish heart and skeletal muscle.

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.

Effects of induced Na+/Ca2+ exchanger overexpression on the spatial distribution of L-type Ca2+ channels and junctophilin-2 in pressure-overloaded hearts.

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.

ANGPTL2 activity in cardiac pathologies accelerates heart failure by perturbing cardiac function and energy metabolism.

A cardioprotective response that alters ventricular contractility or promotes cardiomyocyte enlargement occurs with increased workload in conditions such as hypertension. When that response is excessive, pathological cardiac remodelling occurs, which can progress to heart failure, a leading cause of death worldwide. Mechanisms underlying this response are not fully understood. Here, we report that expression of angiopoietin-like protein 2 (ANGPTL2) increases in pathologically-remodeled hearts of mice and humans, while decreased cardiac ANGPTL2 expression occurs in physiological cardiac remodelling induced by endurance training in mice. Mice overexpressing ANGPTL2 in heart show cardiac dysfunction caused by both inactivation of AKT and sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a signalling and decreased myocardial energy metabolism. Conversely, Angptl2 knockout mice exhibit increased left ventricular contractility and upregulated AKT-SERCA2a signalling and energy metabolism. Finally, ANGPTL2-knockdown in mice subjected to pressure overload ameliorates cardiac dysfunction. Overall, these studies suggest that therapeutic ANGPTL2 suppression could antagonize development of heart failure.

Induced NCX1 overexpression attenuates pressure overload-induced pathological cardiac remodelling.

AIMS: Although increased Na(+)/Ca(2+) exchanger 1 (NCX1) expression is observed during heart failure (HF), the pathological role of NCX1 during the progression of HF remains unclear. We examined alterations of NCX1 expression and activity in hearts after transverse aortic constriction (TAC) surgery and explored whether NCX1 influences pressure overload-induced pathological cardiac remodelling. METHODS AND RESULTS: We generated novel transgenic mice in which NCX1 expression is controlled by a cardiac-specific, doxycycline (DOX)-dependent promoter. In the absence of DOX, TAC surgery caused substantial chamber dilation with a gradual decrease in contractility by 16 weeks. Cardiomyocytes showed a decline in contractility with abnormal Ca(2+) handling during excitation-contraction (E-C) coupling. Reduced NCX1 activity was observed 8 weeks after TAC and was still apparent at 17 weeks. Induced NCX1 overexpression by DOX treatment starting 8 weeks after TAC returned NCX1 activity to pre-TAC levels and prevented chamber dilation with cardiac dysfunction. DOX treatment not only upregulated NCX1 expression in TAC-operated hearts but also returned L-type Ca(2+) channel and sarcoplasmic reticulum (SR) Ca(2+) ATPase expression levels to those in sham-operated hearts. In DOX-treated myocytes, contractility, T-tubule integrity, synchrony of Ca(2+) release from the SR, and Ca(2+) handling during E-C coupling was preserved 16 weeks after TAC surgery. In addition, DOX treatment attenuated the down-regulation of survival signalling and up-regulation of apoptosis signalling 16 weeks after TAC surgery. CONCLUSION: Induced overexpression of NCX1 attenuated pressure overload-induced pathological cardiac remodelling. Thus, maintaining NCX1 activity may be a potential therapeutic strategy for preventing the progression of HF.

Celsior preserves cardiac mechano-energetics better than University of Wisconsin solution by preventing oxidative stress.

OBJECTIVES: Identity of the optimal heart preservation solution remains unknown. Because oxidative stress contributes to contractile failure in the ischaemic/reperfused myocardium and the main characteristic of Celsior is its antioxidant effect, it is important to elucidate the relationship between the inhibitory effect on oxidative stress and cardiac mechano-energetics. We therefore evaluated the efficacy of Celsior from both aspects by comparison with the University of Wisconsin solution (UWS). METHODS: We used 18 excised cross-circulated canine hearts. Excised hearts were preserved with UWS (n = 6) or Celsior (n = 6) for 3 h at 4 °C; the remaining six served as controls. Hearts were then cross-circulated and rewarmed. The end-systolic pressure-volume ratio (LV Emax) and the ventricular pressure-volume area, which is a measure of total mechanical energy, were assessed after reperfusion. Biopsies were taken from the endocardium after excising the heart, before reperfusion, after reperfusion and 4 h after reperfusion to assess the inhibitory effect of each agent on oxidative stress. Endo-myocardial biopsy samples were studied immunohistochemically for expression of 4-hydroxy-2-nonenal (HNE)-modified protein, which is a major lipid peroxidation product. RESULTS: Emax in the UWS group was significantly smaller than in the control group, whereas the Emax in the Celsior group was preserved. Oxygen cost of Emax in the UWS group was significantly higher than in the Celsior group. Myocardial HNE-modified protein levels increased gradually, both under preservation and after reperfusion in the UWS group. Myocardial HNE-modified protein levels in the Celsior group were lower, mainly before and 4 h after reperfusion compared with the UWS group. CONCLUSIONS: Celsior may maintain cardiac contractility and conserve oxygen cost by inhibiting oxidative stress.

Ankle-Brachial Index, Toe-Brachial Index, and Pulse Volume Recording in Healthy Young Adults.

OBJECTIVE: To clarify the characteristics of ankle-brachial index (ABI), toe-brachial index (TBI), and pulse volume recording (PVR) of the ankle with brachial-ankle pulse wave velocity (baPWV) in healthy young adults. MATERIAL AND METHODS: We analyzed ABI, TBI, baPWV, and PVR in the ankle of healthy adults aged 20 to 25 years (median, 20 years) using an automatic oscillometric device between 2002 and 2013. The ABI, baPWV, and PVR in 1282 legs of 641 subjects (301 men and 340 women) and the TBI in 474 toes of 237 subjects (117 men and 120 women) were evaluated. RESULTS: The measured values showed no bilateral differences. ABI and baPWV were higher in men than in women, but TBI was similar in both sexes. ABI <1.0 was observed in 18.1% of the legs in men and in 25.6% in women. TBI <0.7 was observed in 16.2% of the toes in men and 19.1% in women. For ankle PVR, the % mean arterial pressure was higher in women than in men. The upstroke time was <180 ms in most subjects. CONCLUSIONS: For young people, ABI <1.0 or TBI <0.7 may not always indicate vascular abnormalities. When evaluating circulatory indexes, age and sex should be considered.

A simple method for decreasing the liquid junction potential in a flow-through-type differential pH sensor probe consisting of pH-FETs by exerting spatiotemporal control of the liquid junction.

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.

Cdk5rap1-mediated 2-methylthio modification of mitochondrial tRNAs governs protein translation and contributes to myopathy in mice and humans.

Transfer RNAs (tRNAs) contain a wide variety of posttranscriptional modifications that are important for accurate decoding. Mammalian mitochondrial tRNAs (mt-tRNAs) are modified by nuclear-encoded tRNA-modifying enzymes; however, the physiological roles of these modifications remain largely unknown. In this study, we report that Cdk5 regulatory subunit-associated protein 1 (Cdk5rap1) is responsible for 2-methylthio (ms(2)) modifications of mammalian mt-tRNAs for Ser(UCN), Phe, Tyr, and Trp codons. Deficiency in ms(2) modification markedly impaired mitochondrial protein synthesis, which resulted in respiratory defects in Cdk5rap1 knockout (KO) mice. The KO mice were highly susceptive to stress-induced mitochondrial remodeling and exhibited accelerated myopathy and cardiac dysfunction under stressed conditions. Furthermore, we demonstrate that the ms(2) modifications of mt-tRNAs were sensitive to oxidative stress and were reduced in patients with mitochondrial disease. These findings highlight the fundamental role of ms(2) modifications of mt-tRNAs in mitochondrial protein synthesis and their pathological consequences in mitochondrial disease.