Effect of sex hormones on oxalate-synthesizing enzymes in male and female rat livers

PURPOSE: We studied the effect of changes in sex hormones on oxalate metabolism in rats. MATERIALS AND METHODS: Adult male and female rats were administered a precursor of oxalate, and the relationship between dose and urinary oxalate was examined. Levels of sex hormones were varied in rats and glycolate oxidase (GO) and serine pyruvate aminotransferase (SPT) activities were measured under the conditions of being fed tap water or loading with 0.5% ethylene glycol. In addition, urinary oxalate excretion was evaluated. RESULTS: Ethylene glycol and glycolate increased urinary oxalate concentration in male rats dose-dependently but less in female rats. There was almost no change during glycine loading in either male or female rats. GO activity was significantly lower in intact female and gonadectomized male rats. SPT activity was slightly higher in the female than in the male controls. There were no differences in urinary oxalate excretions between male and female rats. During ethylene glycol loading, GO and SPT activities were similar to those with tap water intake. However, urinary oxalate excretion increased to two times the control value in male rats but only slightly increased in female rats. CONCLUSIONS: Sex-related differences exist in the metabolic conversion of glycolate to oxalate in rats, and GO activity is promoted by testosterone. Although difference in GO activity has no physiological effect on oxalate synthesis, GO activity affects urinary oxalate excretion during ethylene glycol loading. We could also conclude that estrogen decreases GO activity in male rats from our results.     

Iodine Excess as an Environmental Risk Factor for Autoimmune Thyroid Disease

The global effort to prevent iodine deficiency disorders through iodine supplementation, such as universal salt iodization, has achieved impressive progress during the last few decades. However, iodine excess, due to extensive environmental iodine exposure in addition to poor monitoring, is currently a more frequent occurrence than iodine deficiency. Iodine excess is a precipitating environmental factor in the development of autoimmune thyroid disease. Excessive amounts of iodide have been linked to the development of autoimmune thyroiditis in humans and animals, while intrathyroidal depletion of iodine prevents disease in animal strains susceptible to severe thyroiditis. Although the mechanisms by which iodide induces thyroiditis are still unclear, several mechanisms have been proposed: (1) excess iodine induces the production of cytokines and chemokines that can recruit immunocompetent cells to the thyroid; (2) processing excess iodine in thyroid epithelial cells may result in elevated levels of oxidative stress, leading to harmful lipid oxidation and thyroid tissue injuries; and (3) iodine incorporation in the protein chain of thyroglobulin may augment the antigenicity of this molecule. This review will summarize the current knowledge regarding excess iodide as an environmental toxicant and relate it to the development of autoimmune thyroid disease.     

Gamma-ray and neutron dosimetry by EPR and AMS, using tooth enamel from atomic-bomb survivors: a mini review

The electron paramagnetic resonance (EPR, or electron spin resonance) method was used to measure CO??· radicals recorded in tooth enamel by exposure to atomic-bomb gamma rays. The EPR-estimated doses (i.e. ??Co gamma-ray equivalent dose) were generally in good correlation with cytogenetic data of the same survivors, whereas plots of EPR-estimated dose or cytogenetically estimated dose against DS02 doses turned out to scatter more widely. Because those survivors whose EPR doses were higher (or lower) than DS02 doses tended to show also higher (or lower) responses for cytogenetic responses, the apparent variation appears primarily due to problems in individual DS02 doses rather than the measurement errors associated with the EPR or cytogenetic technique. A part of the enamel samples were also used for evaluation of neutron doses by measuring ?1Ca/??Ca ratios using the accelerator mass spectrometry technique. The results for the measured ratios were on average ~85 % of the calculated ratios by DS02 (but within the 95 % confidence bounds of the simulated results), which lends support to DS02-derived neutron doses to the survivors.     

Variable-length segmental transmission line and its design guidelines

Waveform distortion is a serious problem in higher-frequency signals on printed circuit boards (PCBs). To overcome this problem, we have already proposed the segmental transmission line (STL) method, which divides transmission lines into several segments with different line widths. Each line width is adjusted to make the reflection noises cancel each other out in order to minimize the signal distortion. In this research, we first analyze the waveform reshaping mechanism of STL. Next, we apply STL to a dual in-line memory module (DIMM) clock-line for high-speed computers. The results give helpful guidelines for STL designs, which shows the efficiency of STL. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Confined Catalytic Janus Swimmers in a Crowded Channel: Geometry‐Driven Rectification Transients and Directional Locking

Self‐propelled Janus particles, acting as microscopic vehicles, have the potential to perform complex tasks on a microscopic scale, suitable, e.g., for environmental applications, on‐chip chemical information processing, or in vivo drug delivery. Development of these smart nanodevices requires a better understanding of how synthetic swimmers move in crowded and confined environments that mimic actual biosystems, e.g., network of blood vessels. Here, the dynamics of self‐propelled Janus particles interacting with catalytically passive silica beads in a narrow channel is studied both experimentally and through numerical simulations. Upon varying the area density of the silica beads and the width of the channel, active transport reveals a number of intriguing properties, which range from distinct bulk and boundary‐free diffusivity at low densities, to directional “locking” and channel “unclogging” at higher densities, whereby a Janus swimmer is capable of transporting large clusters of passive particles.     

Simulations of construction learning for neuron-computer resources

It is well known that information processing in the brain depends on neuron systems. Simple neuron systems are neural networks, and their learning methods have been studied. However, we believe that research on large-scale neural network systems is still incomplete. Here, we propose a learning method for millions of neurons as resources for a neuron computer. The method is a type of recurrent path-selection, so the neural network objective must have nesting structures. This method is executed at high speed. When information processing is executed by analogue signals, the accumulation of errors is a grave problem. We equipped a neural network with a digitizer and AD/DA (Analogue Digital) converters constructed of neurons. They retain all information signals and guarantee precision in complex operations. By using these techniques, we generated an image shifter constructed of 8.6 million neurons. We believe that there is the potential to design a neuron computer using this scheme. This work was presented in part at the Fifth International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28, 2000     

Signal-integrity improvement method and its robustness evaluation for VLSI and VLSI-packaging

Nowadays, a GHz frequency signal needs to be propagated on a printed circuit board (PCB) with low distortions. In addition, a higher-frequency signal of 10 GHz or more will also need to be propagated with low distortion in very-large-scale integration (VLSI) in the future. However, signal propagation with low distortion is getting more and more difficult as the frequency increases. In order to solve this problem and to ensure signal integrity, we have proposed a novel transmission line called a “segmental transmission line” (STL). In the STL, a transmission line is divided into multiple segments of individual characteristic impedance. The multiple segments are designed to fix the waveform distortion on the transmission line by solving a combinatorial explosion problem using a genetic algorithm. In a previous article, we have shown the effectiveness of an STL designed for a GHz clock signal in computer simulations. We have also fabricated two scaled-up STL prototypes for a clock signal using real printed circuit boards (PCBs). In this article, we input a random signal by changing its frequency to the scaled-up STL prototype designed for a 150-MHz clock signal. We show that the STL has high robustness to the random signals and the frequency fluctuations, which indicates the generality of the STL technique.     

Ultra-sensitive high-speed density measurement of the “piston effect” in a critical fluid

In order to conduct a detailed investigation of the piston effect, the peculiar heat transportation phenomenon in critical fluids, an ultra-sensitive high-speed density measurement system was developed using a very thin heater, a sensitive interferometer and a large-capacity high-speed data acquisition system. As the first step of the investigation, an experiment was conducted to measure the velocity of sound in CO2 near its critical point. Short heat pulses suppressing the disturbance of natural convection were applied to a small cell filled with almost-critical CO2 fluid and were detected by the measurement system. Because the pulses propagated through the cell at the velocity of sound and were reflected several times between the cell walls, the velocity could be precisely determined by measuring the time intervals between successive reflections. The resulting velocity profile versus temperature showed good agreement with theoretical prediction and numerical simulations. This result validated the density measurement system, and it is considered that the measurement system will be a very effective tool for further studies on critical phenomena with the aid of numerical simulation.     

Stereoscopic 3‐D display with optical correction for the reduction of the discrepancy between accommodation and convergence

Abstract— This paper describes a method for reducing the discrepancy between accommodation and convergence when viewing stereoscopic 3‐D images. The method uses a newly developed stereoscopic 3‐D display system with a telecentric optical system and a mobile LCD. The examination of a mono‐focal lens showed that a correction lens having the appropriate refractive power and conditions for presenting stereoscopic 3‐D images clearly reduces the discrepancy between accommodation and convergence. The authors also developed a stereoscopic 3‐D display that uses dynamic optical correction to reduce the discrepancy between accommodation and convergence. The display equalizes the theoretical points of accommodation and convergence. The purpose of the development was to expand the regeneration range of a stereoscopic 3‐D image having the appropriate accommodation. An evaluation of the developed display showed that it resolves the discrepancy between convergence and accommodation.