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Biomedical subjects

J Eichberg

Publications and source records attributed to J Eichberg.

At least 91 records · Page 5Linked to original sources

Cyanamide mediated synthesis under plausible primitive earth conditions. VI. The synthesis of glycerol and glycerophosphates.

The formation of glycerol occurs when a solution of DL-glyceraldehyde is heated in the presence of hydrogen sulfide at room temperature. DL-glyceraldehyde and dihydroxyacetone treated with hydrazine, as well as DL-glyceraldehyde incubated with formaldehyde are also partially converted to glycerol. The yields of the above reactions are from approximately 1% to about 3%. The formation of glycerophosphates occurs when glycerol is heated with ammonium dihydrogen phosphate and either urea or cyanamide. The yield of glycerophosphates is about 30%, most of which is sn-glycero-1 (3)-phosphate. These findings indicate that glycerol and sn-glycero-3-phosphate, which are moieties of glycerolipids, could have been formed under conditions which may have prevailed on the primitive Earth.

Biological Evolution↗

Photoelectron emission microscopy of biological tissue; the influence of glutaraldehyde and heavy or biligrafin on the emission image of chicken liver in methacrylate.

The effect of various preparations on the emission image was studied taking into account the influence of UV wave length, section thickness and specimen support. By suitable selection of these parameters, images with sufficient contrast can be obtained of unstained specimens which are only fixed with glutaraldehyde. With glutaraldehyde fixation intravitally injected Biligrafin used as a stain in cholecystography is recognized in the emission image of liver tissue labeling the intravital transport path from the blood capillaries to the bile ducts. Hypotheses for the image forming process are discussed.

Aldehydes↗

Cyanamide mediated syntheses under plausible primitive earth conditions. V. The synthesis of phosphatidic acids.

A mixture of ammonium palmitate, 14C-sn-glycero-1(3)-phosphate, cyanimide and imidazole when heated for several hours formed significant quantities of phospholipids. These reaction products were shown by chromatographic, chemical and enzymatic procedures to be monopalmitoylglycerophosphate (MPGP), dipalmitoylglycerophosphate (DPGP) and monopalmitoyl cyclic glycerophosphate (cMPGP). A portion of the MPGP and DPGP possessed the same steric configuration as naturally occurring lysophosphatidic acid and phosphatidic acid. The yield of total phospholipid was maximal at temperatures between 60 degrees and 90 degrees after 8 h. When ratios of reactants were varied, up to 45% of radioactive glycerophosphate was converted into phospholipids. The average proportions of individual phosphatidic acids were: 60% MPGP, 27% DPGP and 13% cMPGP. Evidence was obtained for a synergistic relationship between cyanamide and imidazole in promoting the formation of phosphatidic acids. These results suggest that phosphatidic acids, which are essential precursors for the biochemical synthesis of more complex membrane phospholipids, could have been produced on the primitive Earth.

Cyanamide↗

A rapid biosynthetic method for the preparation of radioactive phosphatidyl-CMP(CDP-diacylglycerol) of high specific activity.

A procedrue is described for the preparation of [32P]phosphatidyl-CMP(CDP-diacylglycerol) from rat pineal glands incubated with [32P]orthophosphate and DL-propranolol. The product is 95% radiopure and a high specific acitivity. The yield of liponucleotide is 0.4--0.9 micron Ci/mCi of [32P]orthophosphate in the medium. The same method can also be used for the biosynthesis and purification of [3H]phosphatidyl-CMP when [3H]cytidine is the precursor.

Animals↗

Cyanamide mediated syntheses under plausible primitive earth conditions. IV. The synthesis of acylglycerols.

The synthesis of palmitoylglycerols in good yields occurs when a solution of glycerol, ammonium palmitate, cyanamide and imidazole is dried and heated at ambient humidity at temperatures ranging from 60 degrees--100 degrees C for 16 h. Much less product is formed in the absence of either or both cyanamide or imidazole. This work suggests that acylglycerols could have been synthesized on the primitive Earth under plausible prebiotic conditions which were similar but not identical to those which have been shown to condense deoxynucleotides into oligodeoxynucleotides and amino acids into peptides.

Chemical Phenomena↗

Identification of cytidine diphosphate-diglyceride in the pineal gland of the rat and its accumulation in the presence of DL-propranolol.

CDP-diglyceride, an important metabolic intermediate in the biosynthesis of phospholipids, has been isolated for the first time from a mammalian tissue. The isolated material, labeled in incubations of intact rat pineal glands with 32P, [3H]cytidine, or [3H]CTP in the presence of DL-propranolol, was chromatographically identical with authentic CDP-diglyceride and was able to serve as phosphatidyl donor in the enzymatic synthesis of phosphatidylinositol and phosphatidyglycerol. It yielded the expected products upon enzymatic and chemical degradation. No dCDP-diglyceride was detected No radioactive CDP-diglyceride was detected following incubations in the absence of propranolol. Stimulation of CDP-diglyceride labeling from 32P1 occurred at propranolol concentrations between 0.03 and 1.0 mM. Net synthesis of the liponucleotide was shown. At 0.1 mM, propranolol incrased the incorporation of radioactivity into phosphatidylglycerol, phosphatidylinositol, and phosphatidic acid. When inositol (10 mM) and propranolol (0.1 mM) were both present, phosphatidylinositol labeling was further increased, wheas stimulation of phosphatidylglycerol and CPD-diglyceride labeling was abolished. Since CDP-diglyceride did not accumulate in the absence of the drug, its availability may normally be the limiting factor in phosphatidylinositol and phosphatidylglycerol biosynthesis. When propranol is present, inositol may become limiting and thus may lead to the observed labeling pattern.

Animals↗