Alternative method for determining leaf CO2 assimilation without gas exchange measurements: Performance, comparison and sensitivity analysis.

We present an alternative method to determine leaf CO2 assimilation rate (An ), eliminating the need for gas exchange measurements in proximal and remote sensing. This method combines the Farquhar-von Caemmerer-Berry photosynthesis model with mechanistic light reaction (MLR) theory and leaf energy balance (EB) analysis. The MLR theory estimates the actual electron transport rate (J) by leveraging chlorophyll fluorescence via pulse amplitude-modulated fluorometry for proximal sensing or sun-induced chlorophyll fluorescence measurements for remote sensing, along with spectral reflectance. The EB equation is used to directly estimate stomatal conductance from leaf temperature. In wheat and soybean, the MLR-EB model successfully estimated An variations, including midday depression, under various environmental and phenological conditions. Sensitivity analysis revealed that the leaf boundary layer conductance (gb ) played an equal, if not more, crucial role compared to the variables for J. This was primarily caused by the indirect influence of gb through the EB equation rather than its direct impact on convective CO2 exchange on the leaf. Although the MLR-EB model requires an accurate estimation of gb , it can potentially reduce uncertainties and enhance applicability in photosynthesis assessment when gas exchange measurements are unavailable.

Eco-friendly strategy for CO2 enrichment performance in commercial greenhouses based on the CO2 spatial distribution and photosynthesis.

CO2 enrichment is an essential environmental control technology due to its significantly enhancing effect on crop production capacity. Despite being a key energy consumer in protected agriculture (i.e. greenhouse systems), CO2 enrichment remains at a low energy use efficiency level, highlighting the need for developing more energy-efficiency strategies for CO2 enrichment. Therefore, this study employed the computational fluid dynamics (CFD) simulation method to replicate the CO2 diffusion process resulting from CO2 enrichment in three commercial strawberry greenhouses with varying geometric characteristics. Based on the CFD-simulated CO2 concentration distributions, the leaf photosynthetic rate was calculated using a mathematical model group. The CO2 enrichment efficiency was then analysed by calculating the ratio of increased photosynthesis across the cultivation area to the amount of energy (in CO2 equivalent) used. The efficiency peaked when the average CO2 concentration was approximately 500 µmol mol-1, thereby providing guidance for determining the target concentration of CO2 enrichment in production. Although this study is limited as the CFD simulation only considered a typical short-period CO2 enrichment event, future research will provide a broader analysis by considering changes throughout the day.

Upregulation of neuropeptide Y in cardiac sympathetic nerves induces stress (Takotsubo) cardiomyopathy.

Substantial emotional or physical stress may lead to an imbalance in the brain, resulting in stress cardiomyopathy (SC) and transient left ventricular (LV) apical ballooning. Even though these conditions are severe, their precise underlying mechanisms remain unclear. Appropriate animal models are needed to elucidate the precise mechanisms. In this study, we established a new animal model of epilepsy-induced SC. The SC model showed an increased expression of the acute phase reaction protein, c-Fos, in the paraventricular hypothalamic nucleus (PVN), which is the sympathetic nerve center of the brain. Furthermore, we observed a significant upregulation of neuropeptide Y (NPY) expression in the left stellate ganglion (SG) and cardiac sympathetic nerves. NPY showed neither positive nor negative inotropic and chronotropic effects. On the contrary, NPY could interrupt ß-adrenergic signaling in cardiomyocytes when exposure to NPY precedes exposure to noradrenaline. Moreover, its elimination in the left SG via siRNA treatment tended to reduce the incidence of SC. Thus, our results indicated that upstream sympathetic activation induced significant upregulation of NPY in the left SG and cardiac sympathetic nerves, resulting in cardiac dysfunctions like SC.

Assessment of cardiac function in rat endovascular perforation model of subarachnoid hemorrhage; A model of subarachnoid hemorrhage-induced cardiac dysfunction.

Although the association between cardiac dysfunction and subarachnoid hemorrhage (SAH) has been recognized, its precise underlying mechanism remains unknown. Furthermore, no suitable animal models are available to study this association. Here, we established an appropriate animal model of SAH-induced cardiac dysfunction and elucidated its mechanism. In this rat model, contrast-enhanced computed tomography of the brain confirmed successful induction of SAH. Electrocardiography detected abnormalities in 55% of the experimental animals, while echocardiography indicated cardiac dysfunction in 30% of them. Further evaluation of left ventriculography confirmed cardiac dysfunction, which was transient and recovered over time. Additionally, in this SAH model, the expression of the acute phase reaction protein, proto-oncogene c-Fos increased in the paraventricular hypothalamic nucleus (PVN), the sympathetic nerve center of the brain. Polymerase chain reaction analysis revealed that the SAH model with cardiac dysfunction had higher levels of the macrophage-associated chemokine (C-X-C motif) ligand 1 (CXCL-1) and chemokine (C-C motif) ligand 2 (CCL-2) than the SAH model without cardiac dysfunction. Our results suggested that SAH caused inflammation and macrophage activation in the PVN, leading to sympathetic hyperexcitability that might cause cardiac dysfunction directly and indirectly. This animal model may represent a powerful tool to investigate the mechanisms of the brain-heart pathway.

Orbital-resolved visualization of single-molecule photocurrent channels.

Given its central role in utilizing light energy, photoinduced electron transfer (PET) from an excited molecule has been widely studied1-6. However, even though microscopic photocurrent measurement methods7-11 have made it possible to correlate the efficiency of the process with local features, spatial resolution has been insufficient to resolve it at the molecular level. Recent work has, however, shown that single molecules can be efficiently excited and probed when combining a scanning tunnelling microscope (STM) with localized plasmon fields driven by a tunable laser12,13. Here we use that approach to directly visualize with atomic-scale resolution the photocurrent channels through the molecular orbitals of a single free-base phthalocyanine (FBPc) molecule, by detecting electrons from its first excited state tunnelling through the STM tip. We find that the direction and the spatial distribution of the photocurrent depend sensitively on the bias voltage, and detect counter-flowing photocurrent channels even at a voltage where the averaged photocurrent is near zero. Moreover, we see evidence of competition between PET and photoluminescence12, and find that we can control whether the excited molecule primarily relaxes through PET or photoluminescence by positioning the STM tip with three-dimensional, atomic precision. These observations suggest that specific photocurrent channels can be promoted or suppressed by tuning the coupling to excited-state molecular orbitals, and thus provide new perspectives for improving energy-conversion efficiencies by atomic-scale electronic and geometric engineering of molecular interfaces.

Single-molecule laser nanospectroscopy with micro-electron volt energy resolution.

Ways to characterize and control excited states at the single-molecule and atomic levels are needed to exploit excitation-triggered energy-conversion processes. Here, we present a single-molecule spectroscopic method with micro-electron volt energy and submolecular-spatial resolution using laser driving of nanocavity plasmons to induce molecular luminescence in scanning tunneling microscopy. This tunable and monochromatic nanoprobe allows state-selective characterization of the energy levels and linewidths of individual electronic and vibrational quantum states of a single molecule. Moreover, we demonstrate that the energy levels of the states can be finely tuned by using the Stark effect and plasmon-exciton coupling in the tunneling junction. Our technique and findings open a route to the creation of designed energy-converting functions by using tuned energy levels of molecular systems.

Dynamic modelling of cold-hardiness in tea buds by imitating past temperature memory.

BACKGROUND AND AIMS: Most perennial plants memorize cold stress for a certain period and retrieve the memories for cold acclimation and deacclimation, which leads to seasonal changes in cold-hardiness. Therefore, a model for evaluating cold stress memories is required for predicting cold-hardiness and for future frost risk assessments under warming climates. In this study we develop a new dynamic model of cold-hardiness by introducing a function imitating past temperature memory in the processes of cold acclimation and deacclimation. METHODS: We formulated the past temperature memory for plants using thermal time weighted by a forgetting function, and thereby proposed a dynamic model of cold-hardiness. We used the buds of tea plants (Camellia sinensis) from two cultivars, 'Yabukita' and 'Yutakamidori', to calibrate and validate this model based on 10 years of observed cold-hardiness data. KEY RESULTS: The model captured more than 90 % of the observed variation in cold-hardiness and predicted accurate values for both cultivars, with root mean square errors of ~1.0 °C. The optimized forgetting function indicated that the tea buds memorized both short-term (recent days) and long-term (previous months) temperatures. The memories can drive short-term processes such as increasing/decreasing the content of carbohydrates, proteins and antioxidants in the buds, as well as long-term processes such as determining the bud phenological stage, both of which vary with cold-hardiness. CONCLUSIONS: The use of a forgetting function is an effective means of understanding temperature memories in plants and will aid in developing reliable predictions of cold-hardiness for various plant species under global climate warming.

Mexiletine shortens the QT interval in a pedigree of KCNH2 related long QT syndrome.

A 23-year-old female had been suffering from recurrent syncopal episodes during sleep since her childhood. She had a family history of sudden death and her QTc interval was remarkably prolonged to 537 ms A Holter ECG revealed torsade de pointes, corresponding to syncope. She was started on mexiletine and her QTc interval shortened. Her symptoms were controlled after ß-blockers and Ca-blockers were added. A genetic analysis with a next generation sequencer identified a frameshift mutation at the C terminus of the KCNH2 gene. Here we present a type 2 long QT syndrome case in which mexiletine was effective.

Selective triplet exciton formation in a single molecule.

The formation of excitons in organic molecules by charge injection is an essential process in organic light-emitting diodes (OLEDs)1-7. According to a simple model based on spin statistics, the injected charges form spin-singlet (S1) excitons and spin-triplet (T1) excitons in a 1:3 ratio2-4. After the first report of a highly efficient OLED2 based on phosphorescence, which is produced by the decay of T1 excitons, more effective use of these excitons has been the primary strategy for increasing the energy efficiency of OLEDs. Another route to improving OLED energy efficiency is reduction of the operating voltage2-6. Because T1 excitons have lower energy than S1 excitons (owing to the exchange interaction), use of the energy difference could-in principle-enable exclusive production of T1 excitons at low OLED operating voltages. However, a way to achieve such selective and direct formation of these excitons has not yet been established. Here we report a single-molecule investigation of electroluminescence using a scanning tunnelling microscope8-20 and demonstrate a simple method of selective formation of T1 excitons that utilizes a charged molecule. A 3,4,9,10-perylenetetracarboxylicdianhydride (PTCDA) molecule21-25 adsorbed on a three-monolayer NaCl film atop Ag(111) shows both phosphorescence and fluorescence signals at high applied voltage. In contrast, only phosphorescence occurs at low applied voltage, indicating selective formation of T1 excitons without creating their S1 counterparts. The bias voltage dependence of the phosphorescence, combined with differential conductance measurements, reveals that spin-selective electron removal from a negatively charged PTCDA molecule is the dominant formation mechanism of T1 excitons in this system, which can be explained by considering the exchange interaction in the charged molecule. Our findings show that the electron transport process accompanying exciton formation can be controlled by manipulating an electron spin inside a molecule. We anticipate that designing a device taking into account the exchange interaction could realize an OLED with a lower operating voltage.

Many-Body State Description of Single-Molecule Electroluminescence Driven by a Scanning Tunneling Microscope.

Electron transport and optical properties of a single molecule in contact with conductive materials have attracted considerable attention because of their scientific importance and potential applications. With the recent progress in experimental techniques, especially by virtue of scanning tunneling microscope (STM)-induced light emission, where the tunneling current of the STM is used as an atomic-scale source for induction of light emission from a single molecule, it has become possible to investigate single-molecule properties at subnanometer spatial resolution. Despite extensive experimental studies, the microscopic mechanism of electronic excitation of a single molecule in STM-induced light emission has yet to be clarified. Here we present a formulation of single-molecule electroluminescence driven by electron transfer between a molecule and metal electrodes based on a many-body state representation of the molecule. The effects of intramolecular Coulomb interaction on conductance and luminescence spectra are investigated using the nonequilibrium Hubbard Green's function technique combined with first-principles calculations. We compare simulation results with experimental data and find that the intramolecular Coulomb interaction is crucial for reproducing recent experiments for a single phthalocyanine molecule. The developed theory provides a unified description of the electron transport and optical properties of a single molecule in contact with metal electrodes driven out of equilibrium, and thereby, it contributes to a microscopic understanding of optoelectronic conversion in single molecules on solid surfaces and in nanometer-scale junctions.

[A Case of Hypertrophic Pachymeningitis with Symptomatic Venous Congestion due to Sinus Stenosis].

We report a patient with hypertrophic pachymeningitis and symptomatic stenosis of the superior sagittal sinus. A 71-year-old man presented with right hemiparesis, sensory-dominant aphasia, and right hemispatial neglect that had been worsening over 2 weeks. Computed tomography showed isodense crescent-shaped lesions deforming the surface of the left cerebral hemisphere, mimicking a subdural hematoma with atypical perifocal edema in the left parietal lobe. Magnetic resonance imaging showed diffuse thickening of the dura mater with contrast enhancement of his left cerebral hemisphere. Histopathological examination of the dural specimen obtained by burr-hole surgery revealed mononuclear inflammatory cell infiltration, and he was diagnosed with hypertrophic pachymeningitis. Dynamic cerebral angiography showed superior sagittal sinus stenosis with reduced venous flow through the left parietal lobe. Administration of high-dose steroid therapy led to neurological improvement. In the case of a subdural mass with atypical parenchymal edema such as a chronic subdural hematoma, other etiology should be taken into consideration.

Single-Molecule Investigation of Energy Dynamics in a Coupled Plasmon-Exciton System.

We investigate the near-field interaction between an isolated free-base phthalocyanine molecule and a plasmon localized in the gap between an NaCl-covered Ag(111) surface and the tip apex of a scanning tunneling microscope. When the tip is located in the close proximity of the molecule, asymmetric dips emerge in the broad luminescence spectrum of the plasmon generated by the tunneling current. The origin of the dips is explained by energy transfer between the plasmon and molecular excitons and a quantum mechanical interference effect, where molecular vibrations provide additional degrees of freedom in the dynamic process.

Real-space investigation of energy transfer in heterogeneous molecular dimers.

Given its central role in photosynthesis and artificial energy-harvesting devices, energy transfer has been widely studied using optical spectroscopy to monitor excitation dynamics and probe the molecular-level control of energy transfer between coupled molecules. However, the spatial resolution of conventional optical spectroscopy is limited to a few hundred nanometres and thus cannot reveal the nanoscale spatial features associated with such processes. In contrast, scanning tunnelling luminescence spectroscopy has revealed the energy dynamics associated with phenomena ranging from single-molecule electroluminescence, absorption of localized plasmons and quantum interference effects to energy delocalization and intervalley electron scattering with submolecular spatial resolution in real space. Here we apply this technique to individual molecular dimers that comprise a magnesium phthalocyanine and a free-base phthalocyanine (MgPc and H2Pc) and find that locally exciting MgPc with the tunnelling current of the scanning tunnelling microscope generates a luminescence signal from a nearby H2Pc molecule as a result of resonance energy transfer from the former to the latter. A reciprocating resonance energy transfer is observed when exciting the second singlet state (S2) of H2Pc, which results in energy transfer to the first singlet state (S1) of MgPc and final funnelling to the S1 state of H2Pc. We also show that tautomerization of H2Pc changes the energy transfer characteristics within the dimer system, which essentially makes H2Pc a single-molecule energy transfer valve device that manifests itself by blinking resonance energy transfer behaviour.

Normalization of Naxos plakoglobin levels restores cardiac function in mice.

Arrhythmogenic cardiomyopathy (AC) is associated with mutations in genes encoding intercalated disc proteins and ultimately results in sudden cardiac death. A subset of patients with AC have the autosomal recessive cardiocutaneous disorder Naxos disease, which is caused by a 2-base pair deletion in the plakoglobin-encoding gene JUP that results in a truncated protein with reduced expression. In mice, cardiomyocyte-specific plakoglobin deficiency recapitulates many aspects of human AC, and overexpression of the truncated Naxos-associated plakoglobin also results in an AC-like phenotype; therefore, it is unclear whether Naxos disease results from loss or gain of function consequent to the plakoglobin mutation. Here, we generated 2 knockin mouse models in which endogenous Jup was engineered to express the Naxos-associated form of plakoglobin. In one model, Naxos plakoglobin bypassed the nonsense-mediated mRNA decay pathway, resulting in normal levels of the truncated plakoglobin. Moreover, restoration of Naxos plakoglobin to WT levels resulted in normal heart function. Together, these data indicate that a gain of function in the truncated form of the protein does not underlie the clinical phenotype of patients with Naxos disease and instead suggest that insufficiency of the truncated Naxos plakoglobin accounts for disease manifestation. Moreover, these results suggest that increasing levels of truncated or WT plakoglobin has potential as a therapeutic approach to Naxos disease.

Endothelin-1 induces myofibrillar disarray and contractile vector variability in hypertrophic cardiomyopathy-induced pluripotent stem cell-derived cardiomyocytes.

BACKGROUND: Despite the accumulating genetic and molecular investigations into hypertrophic cardiomyopathy (HCM), it remains unclear how this condition develops and worsens pathologically and clinically in terms of the genetic-environmental interactions. Establishing a human disease model for HCM would help to elucidate these disease mechanisms; however, cardiomyocytes from patients are not easily obtained for basic research. Patient-specific induced pluripotent stem cells (iPSCs) potentially hold much promise for deciphering the pathogenesis of HCM. The purpose of this study is to elucidate the interactions between genetic backgrounds and environmental factors involved in the disease progression of HCM. METHODS AND RESULTS: We generated iPSCs from 3 patients with HCM and 3 healthy control subjects, and cardiomyocytes were differentiated. The HCM pathological phenotypes were characterized based on morphological properties and high-speed video imaging. The differences between control and HCM iPSC-derived cardiomyocytes were mild under baseline conditions in pathological features. To identify candidate disease-promoting environmental factors, the cardiomyocytes were stimulated by several cardiomyocyte hypertrophy-promoting factors. Interestingly, endothelin-1 strongly induced pathological phenotypes such as cardiomyocyte hypertrophy and intracellular myofibrillar disarray in the HCM iPSC-derived cardiomyocytes. We then reproduced these phenotypes in neonatal cardiomyocytes from the heterozygous Mybpc3-targeted knock in mice. High-speed video imaging with motion vector prediction depicted physiological contractile dynamics in the iPSC-derived cardiomyocytes, which revealed that self-beating HCM iPSC-derived single cardiomyocytes stimulated by endothelin-1 showed variable contractile directions. CONCLUSIONS: Interactions between the patient's genetic backgrounds and the environmental factor endothelin-1 promote the HCM pathological phenotype and contractile variability in the HCM iPSC-derived cardiomyocytes.

Distinct iPS Cells Show Different Cardiac Differentiation Efficiency.

Patient-specific induced pluripotent stem (iPS) cells can be generated by introducing transcription factors that are highly expressed in embryonic stem (ES) cells into somatic cells. This opens up new possibilities for cell transplantation-based regenerative medicine by overcoming the ethical issues and immunological problems associated with ES cells. Despite the development of various methods for the generation of iPS cells that have resulted in increased efficiency, safety, and general versatility, it remains unknown which types of iPS cells are suitable for clinical use. Therefore, the aims of the present study were to assess (1) the differentiation potential, time course, and efficiency of different types of iPS cell lines to differentiate into cardiomyocytes in vitro and (2) the properties of the iPS cell-derived cardiomyocytes. We found that high-quality iPS cells exhibited better cardiomyocyte differentiation in terms of the time course and efficiency of differentiation than low-quality iPS cells, which hardly ever differentiated into cardiomyocytes. Because of the different properties of the various iPS cell lines such as cardiac differentiation efficiency and potential safety hazards, newly established iPS cell lines must be characterized prior to their use in cardiac regenerative medicine.

Human pentraxin 3 (PTX3) as a novel biomarker for the diagnosis of pulmonary arterial hypertension.

BACKGROUND: Although inflammation is an important feature of pulmonary arterial hypertension (PAH), the usefulness of local inflammatory markers as biomarkers for PAH is unknown. In this study, we tested whether plasma concentrations of human pentraxin 3 (PTX3), a local inflammatory marker, would be a useful biomarker for detecting PAH. METHODS: Plasma PTX3 concentrations were evaluated in 50 PAH patients (27 with idiopathic PAH, 17 with PAH associated with connective tissue disease (CTD-PAH), and six with congenital heart disease), 100 age and sex-matched healthy controls, and 34 disease-matched CTD patients without PAH. Plasma concentrations of B-type natriuretic peptide (BNP) and C-reactive protein (CRP) were also determined. RESULTS: Mean PTX3 levels were significantly higher in all PAH patients than in the healthy controls (4.40±0.37 vs. 1.94±0.09 ng/mL, respectively; P<0.001). Using a threshold level of 2.84 ng/mL, PTX3 yielded a sensitivity of 74.0% and a specificity of 84.0% for the detection of PAH. In CTD-PAH patients, mean PTX3 concentrations were significantly higher than in CTD patients without PAH (5.02±0.69 vs. 2.40±0.14 ng/mL, respectively; P<0.001). There was no significant correlation between plasma levels of PTX3 and BNP or CRP. Receiver operating characteristic (ROC) curves for screening PAH in patients with CTD revealed that PTX3 (area under the ROC curve 0.866) is superior to BNP. Using a PTX3 threshold of 2.85 ng/mL maximized true-positive and false-negative results (sensitivity 94.1%, specificity 73.5%). CONCLUSION: Plasma concentrations of PTX3 may be a better biomarker of PAH than BNP, especially in patients with CTD.

Development, maturation, and transdifferentiation of cardiac sympathetic nerves.

The heart is electrically and mechanically controlled as a syncytium by the autonomic nervous system. The cardiac nervous system comprises the sympathetic, parasympathetic, and sensory nervous systems that together regulate heart function on demand. Sympathetic electric activation was initially considered the main regulator of cardiac function; however, modern molecular biotechnological approaches have provided a new dimension to our understanding of the mechanisms controlling the cardiac nervous system. The heart is extensively innervated, although the innervation density is not uniform within the heart, being high in the subepicardium and the special conduction system. We and others showed previously that the balance between neural chemoattractants and chemorepellents determine cardiac nervous development, with both factors expressed in heart. Nerve growth factor is a potent chemoattractant synthesized by cardiomyocytes, whereas Sema3a is a neural chemorepellent expressed specifically in the subendocardium. Disruption of this well-organized molecular balance and innervation density can induce sudden cardiac death due to lethal arrhythmias. In diseased hearts, various causes and mechanisms underlie cardiac sympathetic abnormalities, although their detailed pathology and significance remain contentious. We reported that cardiac sympathetic rejuvenation occurs in cardiac hypertrophy and, moreover, interleukin-6 cytokines secreted from the failing myocardium induce cholinergic transdifferentiation of the cardiac sympathetic system via a gp130 signaling pathway, affecting cardiac performance and prognosis. In this review, we summarize the molecular mechanisms involved in sympathetic development, maturation, and transdifferentiation, and propose their investigation as new therapeutic targets for heart disease.