Biomedical subjects
Publications and source records attributed to Y Yamagata.
An electric discharge was made through a gas mixture of N2 (7 cm Hg), H2 (14 cm Hg) and CO2 (14 cm Hg) over an aqueous solution (100 ml, pH 7.6) of adenosine (0.02 M) and phosphate (0.2 M) in a 5 liter vessel simulating primitive earth conditions. AMP was produced at a constant rate in the solution, and the yield reached about 2% in two months.
Electric discharges between a pair of carbon electrodes were continued for 50 days in a vessel of 5 liters in volume which initially contained nitrogen at a pressure of 15 cm Hg and 200 ml of water. The pressure in the vessel was gradually increased to 60 cm Hg at the end of the run. Gas chromatographic analysis showed that the increase of the pressure mainly results from the production of hydrogen and carbon monoxide. The concentration of ammonia in the aqueous sample was increased to 0.05 M in 50 days of the discharge. After hydrolysis, glycine and serine were detected at the concentrations of 3.4 x 10(-3) M and 0.057 x 10(-3) M in the final solution, respectively, though glycine was found only at the concentration of 6 x 10(-6) M before hydrolysis. TLC analysis indicated the presence of hydantoic acid, N-formylglycine, diketopiperazine, and polymers of glycine.
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Computer experiments simulating prebiotic polymerization were carried out using the Monte Carlo method. A high degree of single optical isomers from racemic monomers occurred by assuming a small asymmetry in their chemical natures, which was included to investigate an amplification of the asymmetry due to parity non-conservation. The asymmetry developed much more slowly than the growth of polymers, and the degree of asymmetry in the polymers increased with the degree of polymerization. Competition between the preferential selection and the disturbance by the statistical fluctuation are discussed.
Di- and tri-glycine were synthesized in 1M aqueous solution of glycine by bubbling for 90 hr with oxygen discharged in the path from an oxygen cylinder. The peptides were also produced by an incubation at 37 degrees C of 2M glycine solution prepared with 75% hydrogen peroxide, and the yields were traced for 200 days. The final yields were about 0.25% and 0.01% for di- and tri-glycine, respectively. The solution at 166 days of incubation was applied to a Sephadex G10 column, and the fractions around the top of the chromatogram were found to increase the intensity of ninhydrin color about 4 approximately 5 times after hydrolysis, indicating an existence of oligo-glycine. The solutions of 1M glycine and 0.5M diglycine prepared with 30% hydrogen peroxide were incubated at 37 degrees C for 38 days, and di- and tetra-glycine were detected in the yields of 0.12% and 0.33%, respectively.
A 57-year-old male showed an abnormal mass shadow in a pulmonary bulla. Thoracotomy was performed and it was ascertained histologically that the tumour was a giant cell type carcinoma. Clinical features, histological findings and prognosis are reported.
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Dehydration reactions involving condensing reagents in aqueous solution have been studied as models of chemical evolution, and one such reagent has been found to be produced in the supposed primitive Earth conditions. We assumed that the dehydration condensation in aqueous solution could occur if the condensing reagents, which appear to be produced by electric discharges in the gas phase, could be carried to the aqueous solution through the recycling of water washing the wall of the vessel. We present here an experimental study of the dehydration condensation between phosphate and adenosine in aqueous solution using a new discharge apparatus (Fig. 1) which simulates prebiotic chemical evolution. The apparatus was designed so that water recycles in a vessel containing a solution at a relatively low temperature (approximately 30 degrees C), achieved by showering water at 18 degrees C from above the vessel. This is a simulation of the recycling system of water on the Earth, depending on a large difference in temperature between the ocean surface and the sky.
8-Methyladenosine 3'-monophosphate dihydrate was synthesized and crystallized in the monoclinic space group P21 with the unit cell dimensions: a = 9.095(2) A, b = 16.750(3) A, c = 5.405(2) A and beta = 97.61(3) degrees. The structure was determined by the application of the heavy atom method and refined to give a final R factor of 0.047. The pertinent conformations are as follows: the syn conformation about the glycosyl bond (chiCN = 216.8 degrees), the C(2')-endo sugar puckering with the displacement of 0.55 A; and the gauche-gauche conformation about the C(4')-C(5') bond capable of forming an intramolecular hydrogen bonding between N(3) of adenine base and O(5') of the hydroxymethylene group on the ribose. The molecule exists in the zwitterionic form with the N(1) of the adenine base protonated by a phosphate proton and is stabilized by three-dimensional networks of hydrogen bonding through the crystalline water molecules or directly between the adjacent nucleotide molecules; no base stacking was observed.
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A 38-year-old man suffering from chronic recurrent hepatic enchephalopathy due to liver cirrhosis complicated with chronic renal failure had been maintained well by regular hemodialysis treatment for 14 months. Only four episodes of hepatic encephalopathy occurred in that period. Each of four episodes of disturbed consciousness was accompanied by slightly elevated blood ammonia levels. Energetic serial dialysis for 5-7 days was necessary for its recovery. The factors causing hepatic encephalopathy did not appear to be easily dialysable as compared with those of uremic coma. It is concluded that the hemodialysis is quite an effective treatment for the recurrent type of hepatic encephalopathy.
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A case of juxtaglomerular cell tumor, the fourth case in the world diagnosed preoperatively, was reported. Neither strict sodium restriction nor loading of upright position increased a grade of hyperreninemia observed at recumbant position on ordinary diet, but Pald elevated in response to them. Abnormal glucose tolerance was considered to be due to hypopotassemia. Selective renal arteriography revealed a small number of tumor vessels, a lucent area on the nephrogram and early appearance of the renal vein of the diseased side. Histologically, the tumor contained some canalicular structures among the polygonal nonepithelial tumor cells with rhomboid bodies. These findings suggested that this tumor was a hamartoma originated from the juxtaglomerular apparatus.
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