Ethylene oxide sterilization of bone grafts. Residual gas concentration and fibroblast toxicity

We examined the concentration of ethylene oxide in bone allografts after gas sterilization. Chips of the human femoral head were investigated. Residual gas concentration was determined by gas chromatography after the bone chips had been subjected to defatting and freeze-drying, followed by ethylene oxide gas sterilization. Bones were prepared in various ways in an attempt to reduce the concentration of residual ethylene oxide. The concentration was higher when gas sterilization was performed before freeze-drying than when it was done afterwards. An experiment performed with fibroblasts showed the high toxicity of residual ethylene oxide in bone chips, even when the concentration was very low. The growth of fibroblast was reduced more in medium which had been shaken with bones sterilized with ethylene oxide before freeze-drying than in medium which had been shaken with bones sterilized after freeze-drying. The higher residual ethylene oxide concentrations resulted in a decrease in fibroblastic culture activity. Our experiment showed the importance of reducing the residual ethylene oxide gas concentration. Defatting and freeze-drying result in lower residual ethylene oxide concentrations.     

High Precision Simulation of WEDM Using Parametric Programming

This paper describes the development of a simulation method for WEDM (Wire Electrical Discharge Machining) which can accurately reproduce the discharge phenomena of WEDM on computer. The simulation process consists of searching for discharge locations, removing the workpiece and analyzing wire vibration. Since unclarified parameters such as ignition delay time, explosive force, damping coefficient, and permittivity of dielectric in simulation are difficult to measure from experiments, they were obtained by solving the reverse problem using parametric programming. With the parametric programming method, optimum parameters for simulation are searched simultaneously to minimize differences between simulation results and experimental results.     

Dietary docosahexaenoic acid increases cerebral acetylcholine levels and improves passive avoidance performance in stroke-prone spontaneously hypertensive rats

We have recently shown that inferior performance in passive avoidance task is accompanied with decreased hippocampal choline (Ch) in stroke-prone spontaneously hypertensive rats (SHRSP) compared with normotensive control Wistar-Kyoto rats (WKY). We also reported that dietary docosahexaenoic acid (DHA) suppresses the development of hypertension and stroke-related behavioral changes, resulting in the prolongation of the life span of SHRSP. In this study, we examined the effect of dietary DHA on the cerebral acetylcholine (ACh) levels and learning performance in passive avoidance tasks in SHRSP. The arachidonic acid decreased and the DHA increased in plasma lipids dose dependently with dietary DHA treatments, which decreased the systolic blood pressure in SHRSP. Dietary DHA significantly restored the significantly inferior learning performance in passive avoidance response observed in control SHRSP (DHA 0%). Furthermore, the hippocampal ACh levels were correlated positively with the total response latency in passive avoidance tasks. These results suggest that cholinergic dysfunction in the brain of control SHRSP is responsible, at least in part, for the impaired learning ability and the dietary DHA ameliorates this performance failure.     

Renal metabolic changes relating to calculogenesis in an experimental model of calcium containing renal stone formation in rabbits

In histochemical studies it was shown that sulfated acid glycosaminoglycans (AGAGS) were produced and secreted into the tubular lumen in renal papilla, but not in the renal cortex of muddy stone forming kidney. There was no secretion of sulfated AGAGS in renal papilla histochemically during hydronephrosis before stone formation. On autoradiographic study with the use of 45Ca and 35S for labeling of sulfated AGAGS, we found that 45Ca accumulated in renal papilla of muddy stone forming kidney, but not in the other. 35S apparently accumulated into muddy stones. Measurement of calcium content of the renal papilla and cortex proved the results of autoradiographic studies, and measurement of uronic acid in the urine showed increased secretion of AGAGS in the urine from muddy stone forming kidney. From these results it was proposed that the sulfate AGAGS secreted in the urine could bind calcium crystals to each other amd make crystals aggregate massively.     

Solutions spinning of the high Tc oxide superconductor. II. Effect of organic acid on the complex formation of PVA with the copper (II) ion

As basic research for the solution spinning of the high T_c oxide superconductor, the effect of organic acid on the complex formation of poly(vinyl alcohol) (PVA) with the copper [Cu(11)] ion was explored with various carboxylic acids, such as formic acid, acetic acid, n-butylic acid, and lactic acid. The effects of these acids on the interaction between PVA and Cu(II) acetate in aqueous solution were nonexistent, while a chelation of the Cu(II) ion and lactic acid was detected. In the solid state, a linear complex of PVA with the Cu(II) ion was formed by adding organic acid. The ligand of the linear complex was highly dependent on the kind of acid used. © 1994 John Wiley & Sons, Inc.     

The effects of nucleotides and potassium channel openers on the SUR2A/Kir6.2 complex K+ channel expressed in a mammalian cell line, HEK293T cells

The aim of this study was to evaluate whether long-term administration of L-arginine, a physiological substrate for the production of nitric oxide, improved blood pressure, heart rate, cardiac hypertrophy and particularly structural changes in the coronary and carotid artery of spontaneously hypertensive rats (SHR). The experiments started with three groups of 10-week-old animals: control Wistar rats, untreated SHR and SHR treated with L-arginine (SHR + L-arginine). L-Arginine was administered to SHR in a daily dose of 300 mg kg-1 intraperitoneally for 6 weeks. Blood pressure and heart rate were recorded each week. At the end of the experiment in one-half of each group heart weight and body weight were determined and the heart weight/body weight index was calculated. In the other animals, the cardiovascular system was perfused via the left ventricle with a glutaraldehyde fixative at 120 mmHg and the coronary and carotid arteries were processed for transmission electron microscopy. The inner diameter and wall thickness (tunica intima and tunica media) were measured on semithin sections. The reliability of the genetic feature in the SHR group was proved by the increased heart weight, heart weight/body weight index, wall thickness and wall thickness/inner diameter ratio of coronary and carotid arteries in comparison to the group of control Wistar rats. Long-term administration of L-arginine did not significantly influence blood pressure and heart rate in comparison with untreated SHR. Neither were any differences found in cardiac hypertrophy or the geometry of the coronary and carotid arteries (thickness of arterial wall, inner diameter, wall/diameter ratio). In conclusion, the changes in the cardiovascular system in SHR were not reversed, or even alleviated, by chronic treatment with L-arginine.     

Phenomenological viscoelasticity of some rice starch gels

The applicability of a powerful but still easy to use technique, based on a phenomenological theory of viscoelasticity, for processing and analyzing dynamic mechanical data of some rice gels was investigated. Based on this theory a continuous relaxation spectra was generated by application of Tikhonov regularization procedure on continuous Maxwell model. Interpretation of relaxation spectra in terms of number of peaks, its peak intensity H(λ) and appearance of its main distribution peak and magnitude of equilibrium elasticity modulus (G_e) of continuous Maxwell model was found to appropriately reflect main peculiarities of the viscoelastic behavior of rice starch gels. An increase in number of peaks in the relaxation spectra was observed for starch gels having higher amylose content indicating the creation of more heterogeneous structure. H(λ) and G_e values also increased with increase in amylose content demonstrating a transition of the system to more stable state like a gel.