Identification of large variation in the photosynthetic induction response among 37 soybean [Glycine max (L.) Merr.] genotypes that is not correlated with steady-state photosynthetic capacity.

Irradiance continuously fluctuates during the day in the field. The speed of the induction response of photosynthesis in high light affects the cumulative carbon gain of the plant and could impact growth and yield. The photosynthetic induction response and its relationship with the photosynthetic capacity under steady-state conditions (P max) were evaluated in 37 diverse soybean [Glycine max (L.) Merr.] genotypes. The induction response of leaf photosynthesis showed large variation among the soybean genotypes. After 5 min illumination with strong light, genotype NAM23 had the highest leaf photosynthetic rate of 33.8 µmol CO2 m-2 s-1, while genotype NAM12 showed the lowest rate at 4.7 µmol CO2 m-2 s-1. Cumulative CO2 fixation (CCF) during the first 5 min of high light exposure ranged from 5.5 mmol CO2 m-2 for NAM23 to 0.81 mmol CO2 m-2 for NAM12. The difference in the induction response among genotypes was consistent throughout the growth season. However, there was no significant correlation between CCF and P max among genotypes suggesting that different mechanisms regulate P max and the induction response. The observed variation in the induction response was mainly attributed to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activation, but soybean lines differing in the induction response did not differ in the leaf content of Rubisco activase α- and ß-proteins. Future studies will be focused on identifying molecular determinants of the photosynthetic induction response and determining whether this trait could be an important breeding target to achieve improved growth of soybeans in the field.

Fiber-optic magnetometry with randomly oriented spins.

We demonstrate fiber-optic magnetometry using a random ensemble of nitrogen-vacancy (NV) centers in nanodiamond coupled to a tapered optical fiber, which provides a waveguide delivery of optical fields for the initialization, polarization, and readout of the electron spin in NV centers.

Technical Note: Novel imaging method to obtain gray matter-attenuated inversion recovery image using low-field magnetic resonance imaging systems.

INTRODUCTION: The double inversion recovery (DIR) technique suppresses two types of tissue signals with different T1 values by applying two inversion recovery (IR) pulses with different inversion times (TI). In contrast, the double tissue suppression with multi-echo acquisition and single TI combining HIRE (DOMUST-HIRE) method, is a technique enabling the white-matter-attenuated inversion recovery (WAIR) images by setting one inversion time (TI) in a sequence based on the multi-echo method and subtracting the second echo image from the first echo image. Here, we propose a new sequence that can provide the gray-matter-attenuated inversion recovery image based on the DOMUST-HIRE method. METHODS: In this small clinical study, we performed determination of optimal TI and physical evaluation by imaging a subject's head with T1WI and our proposed method for GAIR images. RESULTS: Our proposed method could increase the contrast ratio and the contrast-to-noise ratio between white matter (WM) and gray matter (GM), whereas the signal-to-noise ratio WM and GM decreased than with T1WI method. CONCLUSIONS: Our proposed method can be used to suppress GM and CSF signals. IMPLICATIONS FOR PRACTICE: The use of our proposed method in low-field MRI systems could provide GAIR image.

Comparison of apparent diffusion coefficient (ADC) values obtained by echo planar imaging diffusion-weighted imaging (DWI) and radial acquisition regime DWI in low field MRI systems: A phantom study.

INTRODUCTION: Diffusion-weighted imaging (DWI) with radial acquisition regime (RADAR; RADAR-DWI) is a fast spin echo (FSE)-based DWI imaging technique that is known to be robust to magnetic susceptibility artifacts and distortions as compared with echo planar imaging DWI (EPI-DWI). Several reports have suggested that the apparent diffusion coefficient (ADC) values obtained with FSE-based DWI are different from those obtained with EPI-DWI. The purpose of this study was to create phantoms that mimic the T2 and ADC values of various tissues and to demonstrate the ADC values obtained with RADAR-DWI and EPI-DWI in low-field magnetic resonance imaging (MRI) systems. METHODS: Several phantoms were created using sucrose and manganese (II) chloride tetrahydrate mimicking various tissues. RADAR-DWI and EPI-DWI were used to scan the phantoms, and the obtained ADC values were compared. RESULTS: The ADC values obtained with RADAR-DWI were significantly higher than those obtained with EPI-DWI for all phantoms (P < 0.05). The ADC values obtained by RADAR-DWI ranged from 0.70 ± 0.01 to 1.21 ± 0.02 ( × 10-3mm2s-1). Meanwhile, the ADC values obtained with EPI-DWI ranged from 0.59 ± 0.01 to 1.08 ± 0.05 ( × 10-3mm2s-1). CONCLUSIONS: We created phantoms mimicking T2 and ADC values of various tissues and demonstrated the differences in ADC values obtained with RADAR-DWI and EPI-DWI using low-field MRI systems. IMPLICATIONS FOR PRACTICE: ADC values obtained by RADAR-DWI are significantly higher than those obtained by EPI-DWI, with different cutoff values for various tumor malignancies between them.

Feasibility of salt pads to improve fat suppression in low-field MRI systems.

INTRODUCTION: Fat-suppressed images are essential in clinical practice but are often affected by magnetic field inhomogeneity, resulting in poor image quality. We hypothesized that salt (99% sodium chloride [NaCl]) could be used as a magnetic field uniformity assist pad and verified whether salt pads improve magnetic field uniformity and the fat suppression effect in low-field magnetic resonance imaging (MRI) systems. METHODS: We conducted a small clinical study where coronal 2D fast spin-echo T2-weighted MRI with fat suppression was performed. The subjects were 10 healthy volunteers (six men and four women) with no surgical history, with a mean age of 20.5 years (range, 20-30 years). In the clinical study, we performed physical and visual evaluation by imaging a subject's knee with and without salt pads. RESULTS: The results of the clinical study indicated that the use of salt pads improved the magnetic field uniformity, thus increasing the fat suppression effect. CONCLUSIONS: Salt pads improved the homogeneity of the magnetic field and the fat suppression effect in low-field MRI systems. IMPLICATIONS FOR PRACTICE: The use of salt pads in low-field MRI systems could provide more accurate fat suppression images.

Dark-bright mixing of interband transitions in symmetric semiconductor quantum dots.

In photoluminescence spectra of symmetric [111] grown GaAs/AlGaAs quantum dots in longitudinal magnetic fields applied along the growth axis, we observe in addition to the expected bright states also nominally dark transitions for both charged and neutral excitons. We uncover a strongly nonmonotonic, sign-changing field dependence of the bright neutral exciton splitting resulting from the interplay between exchange and Zeeman effects. Our theory shows quantitatively that these surprising experimental results are due to magnetic-field-induced ±3/2 heavy-hole mixing, an inherent property of systems with C(3v) point-group symmetry.

Lasing in ultra-narrow emission from GaAs quantum dots coupled with a two-dimensional layer.

We report electrically injected lasing in GaAs quantum dots (QDs) grown on GaAs(001) by droplet epitaxy. High-quality GaAs QDs with superior uniformity are formed using improved growth techniques involving the insertion of a two-dimensional layer, control of the As flux for GaAs crystallization, and thin AlGaAs layer capping with high-temperature annealing. The QDs show ultra-narrow luminescence with a linewidth of 20 meV. Ground-state lasing from a laser diode containing fivefold-stacked QD layers is observed at low temperature under pulsed operation.

Ultra-narrow emission from single GaAs self-assembled quantum dots grown by droplet epitaxy.

We realized ultra-narrow excitonic emission from single GaAs/AlGaAs quantum dots (QDs) grown by a refined droplet epitaxy technique. We found that uncapped quantum dots can be annealed at 400 degrees C without major changes in their morphology, thus enabling an AlGaAs capping layer to be grown at that temperature. Consequently, we demonstrate a fourfold reduction of the linewidth of the emission together with an increased recombination lifetime, compared to the conventional droplet epitaxial QDs. The averaged linewidth of neutral excitons measured by micro-photoluminescence on single quantum dots was around 35 microeV.

Light propagation from a fluorescent particle embedded in a photonic cluster of micrometer-sized dielectric spheres.

In self-assembled multilayer arrays of micrometer-sized spheres that include small amounts of fluorescent particles, unique six-dot-triangular and seven-dot-hexagonal patterns have been known to appear in the fluorescence microscopic images. Although it has been suggested that these two types of patterns correspond to local domain structures, i.e., face centered cubic (fcc) or hexagonal closed packed (hcp), no conclusive evidence has been provided to support this claim. In this study, we systematically investigated the relationship between the propagation patterns and the arrangement of the particles. Through a cross-check between an experiment using well-defined clusters fabricated by a micromanipulation technique and a rigorous calculation based on the expansion of vector spherical harmonics, we confirmed that the six-dot-triangular and seven-dot-hexagonal patterns correspond to the fcc and hcp domains, respectively. Further, we also found that the propagation patterns depend on the size of the clusters. As a result of a quantitative discussion on the light propagation in clusters with various sizes, it was clarified that a sufficient domain size is necessary for the appearance of clear triangular or hexagonal patterns.

Simvastatin decreases IL-6 and IL-8 production in epithelial cells.

Many cardiovascular studies have suggested that 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors (statins) have anti-inflammatory effects independent of cholesterol lowering. As a chronic inflammatory disease, periodontitis shares some mechanisms with atherosclerosis. Since oral epithelial cells participate importantly in periodontal inflammation, we measured simvastatin effects on interleukin-6 and interleukin-8 production by cultured human epithelial cell line (KB cells) in response to interleukin-1alpha. Simvastatin decreased production, an effect reversed by adding mevalonate or geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. Simvastatin was found to reduce NF-kappaB and AP-1 promoter activity in KB cells. Dominant-negative Rac1 severely inhibited interleukin-1alpha-induced NF-kappaB and AP-1 promoter activity. Our results may indicate an anti-inflammatory effect of simvastatin on human oral epithelial cells, apparently involving Rac1 GTPase inhibition.

Biochemical analysis of decreased ornithine transport activity in the liver mitochondria from patients with hyperornithinemia, hyperammonemia and homocitrullinuria.

Hyperornithinemia, hyperammonemia and homocitrullinuria (HHH disorder) is an inherited metabolic disorder which shows peculiar amino acid changes in the serum and urine. The primary defect is considered to be the transport of ornithine across the mitochondrial membrane, but there is no direct evidence for this so far. We have analyzed ornithine transport activities in the liver mitochondria from three patients with HHH disorder. In coupled liver mitochondria we demonstrated low activities of citrulline synthesis and low rates of ornithine uptake. However, there were no abnormalities in carbamoyl-phosphate synthetase activity, ornithine carbamoyltransferase activity, N-acetylglutamate levels or O2 uptake with succinate. We also performed a kinetic study of citrulline synthesis as a function of ornithine concentration. We found increased Km values for ornithine and varied Vmax values of citrulline synthesis, which suggested the presence of a mutant transport protein. From these results we conclude that the defect of hyperornithinemia, hyperammonemia and homocitrullinuria lies in the transport of ornithine across the mitochondrial membrane.

Enhanced light amplification due to group-velocity anomaly peculiar to two- and three-dimensional photonic crystals.

An analytical expression was derived for light amplification by stimulated emission in arbitrary photonic crystals, which showed and enhancement due to small group velocity. This enhancement was evaluated quantitatively for a two-dimensional crystal with a finite thickness, and an extremely large enhancement due to group-velocity anomaly peculiar to two- and three-dimensional crystals was found even for quite a thin crystal.

Novel approach to photonic bands with frequency-dependent dielectric constants.

We formulated a novel method to calculate the dispersion relations of arbitrary photonic crystals with frequency-dependent dielectric constants based on the numerical simulation of dipole radiation. As an example, we applied this method to a two-dimensional square lattice of metallic cylinders and obtained a good agreement with the previous result by means of the plane-wave expansion method by Kuzmiak et al. [Phys. Rev. B 50, 16 835 (1994)]. In addition to the dispersion relations, we could obtain the symmetries and the wave functions of the eigenmodes.

Low-threshold laser oscillation due to group-velocity anomaly peculiar to two- and three-dimensional photonic crystals.

An analytical expression of the lasing threshold for arbi trary photonic crystals was derived, which showed their reduction due to small group velocities of electromagnetic eigenmodes. The lasing threshold was also evaluated numerically for a two-dimensional photonic crystal by examining the divergence of its transmission and reflection coeffcients numerically. A large reduction of lasing threshold caused by a group-velocity anomaly that is peculiar to two- and three- dimensional photonic crystals was found.

Eigenmode symmetry for simple cubic lattices and the transmission spectra.

The existence of uncoupled modes is identified by gaps in the transmission spectra when the density of states is nonzero. We use a group theoretic analysis of the photonic band structure for a simple cubic lattice to tag the symmetry and polarization of each band. The results are compared with transmission spectra calculated by the transfer matrix method.

Identification of a novel vitamin D response element from the rat genome.

1 alpha,25-Dihydroxyvitamin D3 [1,25-(OH)2D3], the active form of vitamin D3, has been thought to be a multifunctional agent. In order to discover novel roles of 1,25-(OH)2D3, we have been looking for new genes that are regulated by 1,25-(OH)2D3. Because the actions of 1,25-(OH)2D3 are mediated through the vitamin D receptor (VDR), that is a DNA binding transcription factor, vitamin D regulated genes should have VDR binding sites in their regulatory regions. In this paper, we describe a novel vitamin D response element (VDRE)-containing sequence, clone 3, which was isolated through binding to VDR. DNA sequence analysis of clone 3 did not reveal any significant similarity with sequences reported previously. Clone 3 had two regions consisting of a direct repeated sequence of AGTTCA motifs, both of which bound to VDR independently. Whereas each direct repeat sequence alone could not mediate transcriptional activation efficiently, with their co-existence there was a strong response to 1,25-(OH)2D3, indicating that these two direct repeated sequences act cooperatively.

Portopulmonary shunt by splenopneumopexy as a surgical treatment of Budd-Chiari syndrome.

Portopulmonary shunting by splenopneumopexy was devised as a new surgical procedure for treatment of portal hypertension accompanied by Budd-Chiari syndrome. Technique of this procedure is simple and is safely performed. The remarkable portopulmonary shunts were visualized by splenoportography postoperatively. Splenic pulp pressure was reduced to a postoperative mean value of 258.3 mm H2O from a preoperative mean value of 336.8 mm H2O. Hemorrhage from esophageal varices and ascites were well controlled after operation. Postoperative liver function tests were essentially unchanged from the preoperative values. Any respiratory and circulatory complications after this shunting have not been observed so far. It is concluded that portopulmonary shunt by splenopneumopexy is an effective procedure for portal hypertension caused by Budd-Chiari syndrome.

Long-term follow-up result of portopulmonary shunt by splenopneumopexy on membranous obstruction of the inferior vena cava.

A patient with membranous obstruction of the inferior vena cava (MOVC) who underwent portopulmonary shunting by splenopneumopexy 13 years before developed hepatocellular carcinoma (HCC). Postmortem studies revealed HCC in the bilateral lobes of the liver with cirrhosis and complete MOVC. There were numerous new vessel formations in the portion of the splenopneumopexy, which proved persistence of the patency. Clinically, postshunt encephalopathy, hepatic deterioration, and cardiac-respiratory dysfunction in the long-term follow-up period were not noticed. Factors that contributed to the occurrence of HCC are also discussed.

Metastasis of malignant struma ovarii to the cranial vault during pregnancy.

Malignant struma ovarii is a rare type of ovarian teratoma; only 16 cases with distant metastases have been reported previously. We report an extremely rare case of malignant struma ovarii metastatic to the cranial vault, which developed during pregnancy. A 28-year-old woman in the 26th week of pregnancy, who had undergone resection of an ovarian tumor 3 years previously, noticed a mass in her left frontal region that had enlarged gradually in 6 months. Magnetic resonance imaging revealed a massive extradural tumor growing through the cranium. Under fetal heart monitoring, the patient underwent total resection of the tumor, including the adjacent cranial bone and dura, and a healthy infant was delivered at full term. Pathological examination showed that the tumor was a follicular adenocarcinoma. Because there was no abnormality in the patient's thyroid gland, this tumor was considered to be a metastasis from the ovarian tumor, a malignant struma ovarii, resected 3 years previously. The management of brain tumor during pregnancy is also discussed.

Coincidental pituitary adenoma and parasellar meningioma: case report.

We report a patient who had pituitary adenoma and parasellar meningioma coincidentally, with neither irradiation nor a history of head injury. Preoperative computed tomographic (CT) scan had shown a large intrasellar mass with ring-like enhancement; in contact with this mass, another well-enhanced mass had been shown. Histopathologically, the intrasellar mass was diagnosed as chromophobic pituitary adenoma and the other mass as meningotheliomatous meningioma. We present clinical, radiological, and histopathological findings and discuss previously reported cases of coincidental pituitary adenoma and meningioma without irradiation. This is the first case report since the advent of CT that pituitary adenoma and parasellar meningioma in contact with each other could be clearly demonstrated by CT.