Chemical modification of aminocyclitol antibiotics

The aminocyclitol antibiotic neamine has been chemically modified at the hydroxyl group on C-6 of the 2-deoxystrepatamine moiety. The partially acetylated neamine derivatives, 6,3,4-tri-O-acetyl- (3) and 5,3-57,4-tri-O-acetyl-1,3,2,6-tetra-N-(ethoxycarbonyl)neamine (4), were prepared by random hydrolysis of the 5,6-O-ethoxyethylidene derivative (2), followed by chromatographic purification. Condensation of 4 and 2,3,5-tri-O-benzoyl-D-ribofuranosyl chloride led to 6-O-(beta-D-ribonfuranosyl)neamine (7). Analogous condensation of 4 with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide or 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide afforded the corresponding 6-O-(D-hexopyranosyl)neamines.

The effect of anti-inflammatory agents on human synovial fibroblast prostaglandin synthetase

Human synovial fibroblast prostaglandin synthetase activity is inhibited by many different non-steroidal anti-inflammatory agents. Aspirin, indomethacin and phenylbutazone significantly inhibit both PGE1, PGE2 and PGF1alpha and PGF2alpha synthesis; whereas penicillamine and aurothioglucose are more potent inhibitors of the F prostaglandins. Histidine and antimalarials do not inhibit, to a significant degree, human synovial prostaglandin synthetase activity. Hydrocortisone has no direct effect on prostaglandin synthetase activity. No changes in synthetase activity are observed when synovial cells are incubated with hydrocortisone, and the prostaglandin synthetase system subsequently isolated and assayed. The proposed inhibitory effects of hydrocortisone on prostaglandin production by synovium may be the resulf of an alteration of enzyme substrate or cofactor concentration rather than a direct effect on prostaglandin synthetase.

A technique for the induction of labor by the extraovular administration of prostaglandin F2alpha

Prostaglandin F2alpha (PG F2alpha) was administered to pregnant women at a dosage of 50 microng or 100 microng by extraovular route around the expected time of childbirth in order to induce labor. (1) PG F2alpha 50 microng or 100 microng dissolved in 10 ml of physiological saline solution was infused by extraovular administration through the cervical canal of the uterus with the use of Nelaton catheter No. 9. The catheter was then immediately withdrawn and the patient allowed to return home. (2) Instilation of 10ml of physiological saline solution was carried out for control purposes. (3) Those who reported labor contractions within 24 hours after the infusion were regarded as cases of excellent response, and those who reported labor contractions more than 24 hours after the infusion, or those who showed dilatation and improvement in effacement of the uterine cervical canal though without the occurrence of labor contractions were deemed to be cases of good response. The overall positive response rate (excellent plus good) was 78.9% for primiparae and 85.7% for multiparae in the group receiving 50 microng and 89.5% for primiparae and 100% for multiparae in the group receiving 100 microng. (4) Labor contraction were induced at a rate of almost 100% in those who showed dilatation of the cervical canal of the uterus to the extent of 3 cm or more and effacement to the extent of 50% or more. (5) It is advisable to perform reinfusion of PG F2alpha or instilation of PG F2alpha as a post-treatment in patients with good responses. (6) The infusion of PG F2alpha is effective for the induction of labor in older primiparae, cases of breech presentation and suspected cases of CPD. (7) There were some cases of enhanced response when PG F2alpha was given as posttreatment.

Analysis of the electron paramagnetic resonance spectrum of the cobalamin intermediate in ribonucleotide reduction

EPR absorption-derivative lineshapes have been computed and least-squares fitted to the spectrum of the intermediate derived from 5'-deoxy-5'-adenosylcobalamin in the ribonucleotide reductase reaction. A Gaussian-type intrinsic lineshape was assumed and the effects of inhomogenous broadening, rotation of coordinate axes of the A-tensor relative to the g-tensor, angular dependence of transition probability and ligand hyperfine splitting have also been investigated. When the overall spectrum was computed as the sum of the lineshapes corresponding to two distinct Co(II) species, A and B, each having rhombic symmetry, the least squares procedure converged to a much better fit than with a single species, and matched almost all of the features of the experimental spectrum. The magnetic properties of A and B were compared with those of a series of other Co(II) complexes by a plot of g - g versus A - A. The results eliminate cobalt with 5-coordination to nitrogen for A and B, and suggest low-spin cobalt complexes having strongly distorted 6-fold coordination. The possibility that the sixth, symmetry-decreasing ligand is the oxygen molecule is excluded by the chemistry of the system and by the EPR properties of previously reported cob(II)alamins. It is suggested that the sixth ligand is a carbonyl, amide or sulfhydryl group of an enzyme sidechain which is inserted off-axis into the coordination position so as to exert the observed symmetry-lowering effect.

Epiphyseal cartilage cyclic nucleotide phosphodiesterase: partial purification and kinetic characteristics of multiple enzymes

Partial purification of chicken epiphyseal PDE activity by centrifugation and column chromatography has defined two distinct peaks of PDE activity. The faster eluting peak (I) has a higher apparent Km for cyclic AMP than the slower eluting major peak (IIs and II). Peak I has greater activity towards cyclic AMP as a substrate than towards cyclic GMP but does use both substrates. Peak I is not inhibited by T-3 or indomethacin at physiological concentrations. Substrates studies demonstrate the presence of at least two overlapping PDE species in the major peak(IIs and II). There is suggestive evidence that indomethacin is a more potent inhibitor of peak IIs which can use either cyclic AMP or cyclic GMP as substrates, whereas T-3 is a more potent inhibitor of fractions eluting where the enzyme only has activity with cyclic AMP.

Human synoviocytes: activation and desensitization by prostaglandins and 1-epinephrine

The human synoviocyte increases its intracellular adenosine 3':5'-cyclic monophosphate (cAMP) concentration significantly after incubation with prostaglandin E1, prostaglandin E2, or l-epinephrine. The cells can be desensitized to these same hormones. Hormone-induced desensitization is receptor site specific and associated with a significant increase in intracellular 3':5'-cyclic AMP phosphodiesterase (EC 3.1.4. 17; 3':5'-cyclic AMP 5'-nucleotidohydrolase) activity, whereas cAMP-induced desensitization is not hormone specific.

Conversion of histidine to hercynine by Neurospora crassa

Cell-free extracts of Neurospora crassa mycelium catalyze the methylation of l-histidine to form hercynine (histidine betaine). The partially methylated compounds, alpha-N-methyl-l-histidine and alpha-N,N-dimethyl-l-histidine, are also methylated by the same enzyme preparation to form hercynine. All three methylation reactions are stimulated by the addition of S-adenosylmethionine.

Magnetic Properties of the Lunar Crystalline Rock and Fines

Magnetic measurements have shown that nondiamagnetic minerals in a lunar crystalline rock of type B are (free Fe(2)+ in paramagnetic pyroxenes) : (antiferromagnetic FeSiO(3)) : (antiferromagnetic FeTiO(3)) : (ferromagnetic iron) = 4.3 : 7 : 20 : 0.08 in weight percentage. The abundance of ferromagnetic Fe in the lunar fines is about 7.5 times its abundance in the crystalline rock. The natural remanent magnetization of the crystalline rock of 7.5 x 10(-6) emu/ g in intensity may not be attributable to its thermoremanent magnetization.