The insensitivity of mushroom nuclear RNA polymerase activity to inhibiton by amatoxins

Nuclear fractions isolated from Amanita phalloides, Amanita muscaria and Agaricus bisporus were subjected to in vitro RNA synthesis assays in the presence of various concentrations of amatoxins. The mushroom nuclei were highly insensitive to inhibition by amatoxin when compared to assays of nuclear fractions isolated from the Oömycete fungus, Achlya ambisexualis and from rabbit brain.Abbreviations DTT dithiothreitol - PMSF phenylmethyl sulfonyl fluoride - MES 2[N-morpholino] ethane sulfonic acid Paper no. 1-78     

Interaction of anthelmintic benzimidazoles and benzimidazole derivatives with bovine brain tubulin

The binding and inhibitory properties of 11 benzimidazoles for bovine brain tubulin were investigated. The effects of the benzimidazoles on the initial rates of microtubule polymerization were determined by a turbidimetric assay. The median inhibitory concentrations (I₅₀) for nocodazole, oxibendazole, parbendazole, mebendazole and fenbendazole ranged from 1.97 · 10⁻⁶ to 6.32 · 10⁻⁶ M. Benomyl, cambendazole and carbendazim had I₅₀ values from 5.83 · 10⁻⁵ to 9.01 · 10⁻⁵ M. Thiabendazole had an I₅₀ value of 5.49 · 10⁻⁴ M. Inhibitor constants (K_i) were determined by the colchicine binding assay. Oxibendazole, fenbendazole, and cambendazole had K_i values of 3.20 · 10⁻⁵, 1.73 · 10⁻⁵ and 1.10 · 10⁻⁴ M, respectively. Oxibendazole and fenbendazole were competitive inhibitors of colchicine. In contrast, cambendazole was a noncompetitive inhibitor of colchicine. The ability of these benzimidazoles to inhibit microtubule polymerization and the mode of action for the anthelmintic benzimidazoles is discussed.     

A new variety of spondyloepiphyseal dysplasia characterized by punctate corneal dystrophy and abnormal dermal collagen fibrils

Summary Several individuals from one family are described with a unique form of spondyloepiphyseal dysplasia. Characteristic features include shorttrunked short stature, punctate corneal dystrophy and marked disorganization of dermal collagen fibrils when examined by transmission electron microscopy. Inheritance is compatible with either dominance and a variable expression or X-linkage. Although the basic defect has not been determined, the tissue distribution is consistent with a defect in a non-collagenous component that affects collagen fibril formation or stability.     

Properties of fructose-1,6-diphosphate phosphatase and fructose-1,6-diphosphate aldolase fromPseudomonas putida

The fructose-1,6-P₂ (FDP) phosphatase, (FDPase) and FDP aldolase fromPseudomonas putida were partially purified by a combination of (NH₄)₂SO₄ fractionation and DEAE-Sephadex column chromatography. Michaelis-Menten kinetics were observed with, respect to FDP in both FDPase and FDP aldolase. TheK _m for FDP at pH 8.0 was 1.2×10⁻⁵M for FDPase and 3.0×10⁻⁵M for FDP aldolase. The specific activities of these two enzymes (assayed under optimal conditions in cell-free extracts ofP. putida grown ond-fructose), as well as their kinetic properties, are consistent with the suggestion that during growth ond-fructose most, of the FDP generated is converted to fructose-6-P (F-6-P), which is subsequently utilized via the Entner-Doudoroff pathway (EDP).     

Positional information in imaginal discs transformed by homoeotic mutations

Summary Mutations of the bithorax complex result in segmental transformations in the thorax and abdomen ofDrosophila. The haltere discs from larvae homozygous forbx ³ orpbx are transformed so that the discs contain cells that will produce wing cuticle as well as cells that produce haltere cuticle. The pattern regulation behavior of these discs has been examined. The fate maps of the two discs were established, and then the regulative behavior of a number of fragments from both types of mutant discs was established by culturing the fragments in vivo prior to metamorphosis. The most important conclusion from this work is that the cells producing, haltere cuticle and wing cuticle within the same disc share the same positional information and that they communicate during pattern regulation.     

Resistance to chenodeoxycholic acid (CDCA) treatment in obese patients with gall stones

In most patients with radiolucent gall stones who were given chenodeoxycholic acid (CDCA) in doses of 13-15 mg/kg body weight/day the bile became unsaturated in cholesterol, and their gall stones dissolved. The patients whose stones did not dissolve were significantly heavier and fatter than the responders, which suggested that obese patients might be “resistant” to the effects of CDCA. To test this hypothesis, 32 consecutive patients presenting for medical treatment of gall stones had their ideal body weight (IBW) and estimated body fat mass calculated. The eight most obese and the eight least obese patients were then selected, and their fasting bile lipid responses to CDCA 13-15 mg/kg/day were measured. The very obese patients were also given larger doses, and any changes in bile lipid composition were studied in relation to subsequent gall-stone dissolution.Before treatment the obese patients had a higher mean biliary cholesterol saturation index than the non-obese patients, and this difference was maintained during treatment with the normal dose of CDCA: the bile in the obese patients remained supersaturated while that in the non-obese became unsaturated with cholesterol. When the obese patients were given larger doses of CDCA their bile ultimately became unsaturated in cholesterol. Gall stones dissolved partially or completely in five of the eight non-obese patients after 6-18 months of 13-15 mg CDCA/kg/day, but none of the obese patients showed any response after comparable periods of treatment with this standard dose. With increased doses and unsaturated bile, however, three of the obese patients showed partial gall-stone dissolution after 3-12 months'' treatment and one showed complete gall-stone dissolution after three years'' treatment.These results suggest that when giving CDCA to patients with gall stones, larger than normal doses (some 18-20 mg/kg/day) should be prescribed. Alternatively the lipid composition of the patients'' bile should be monitored by duodenal intubation and the CDCA dose increased until the bile becomes unsaturated in cholesterol.     

Synthesis and biological properties of 12-fluoroprostacyclins

The synthesis of the sodium salts of enantiomerically pure 12-fluoroPGI₂ (9), (±)-12-fluoroPGI₂ (9), (±)-15-epi-12-fluoroPGI₂ (10), (±)-12-fluoro-13,14-dihydroPGI₂ (11), (±)-12-fluoro-4(E)-isoPGI₂ (12), and (±)-5,6-dihydro-12-fluoroPGI₂ (13) is detailed starting from the corresponding derivatives of 12-fluoroPGF_2α methyl ester. Prostacyclins 9, (±)-9, (±)-10, (±)-11, (±)-12, and (±)-13 have been evaluated for their ability to inhibit human platelet aggregation and their effect on smooth muscle (isolated cat coronary artery).     

Radical scavenging as the mechanism for stimulation of prostaglandin cyclooxygenase and depression of inflammation by lipoic acid and sodium iodide

Certain radical-trapping reducing agents have been shown to stimulate prostaglandin biosynthesis (1–6) and to depress phorbol myristate acetate-induced mouse ear edema (16). The increased prostaglandin synthesis resulted from influences on the cyclooxygenase. To ascertain whether these alterations were due to direct interaction with the enzyme or to indirect scavenging of the oxidant released during PGG₂ reduction, we report the effects of lipoic acid and sodium iodide.Both of these agents stimulated the enzymatic oxygenation of arachidonic acid, increased the reduction of PGG₂ to PGH₂, quenched the EPR signal induced by arachidonic acid and depressed mouse ear edema. In addition to discovering two unusual antiinflammatory agents, we have confirmed that materials with entirely different structures can have identical effects on the cyclooxygenase, suggesting indirect stimulation of this enzyme due to trapping of the oxidant.     

Studies of cyclic AMP action using mutant tissue culture cells

Summary S49 mouse lymphoma cell mutants, each with a specific defect in its ability to generate or respond to cyclic AMP, have been isolated. Analysis of the properties of these cells has begun to provide information on complex and significant biologic problems related to the cyclic AMP system. Presented in the Opening Symposium on Nutritional Factors and Differentiation at the 28th Annual Meeting of the Tissue Culture Association, New Orleans, Louisiana, June 6–9, 1977. The work was supported in part by National Science Foundation Grant BMS 75-06764 and National Institutes of Health Grants GM 16496 and GM 00001. P.C. is the recipient of National Institutes of Health Research Career Development Award GM 00308. P. A. I. is an Established Investigator of the American Heart Association.     

Serum Glutathione Peroxidase Activity and Blood Selenium in Pigs

Blood serum glutathione peroxidase activity and blood selenium concentration were measured in blood samples from pigs subjected to experimentally induced selenium deficiency and dietary selenium supplementation on graded levels. A highly significant correlation between blood selenium and serum GSH-Px activity in pigs, especially in selenium deficient pigs, was demonstrated. There was also a strong relationship between blood selenium concentration and serum GSH-Px activity in pigs receiving dietary selenium at graded levels. Serum GSH-Px activity exhibited an excellent close-response relationship to dietary selenium. Linear regression analysis showed that the increased serum GSH-Px activity was a function of the dietary selenium concentration. The fitness of serum in monitoring slight changes of the selenium status of pigs with help of the estimation of GSH-Px activity was discussed. The measurement of serum GSH-Px activity seems to provide a useful and rapid means for defining selenium requirements and for identifying selenium deficiency in growing pigs.