Heterogeneous distribution of glucose 6-phosphatase in rat liver microsomal fractions as shown by adaptation of a cytochemical technique

1. A novel technique for the subfractionation of rat liver smooth and rough microsomal fractions according to their content of glucose 6-phosphatase is described. This technique, based on the Gomori lead histochemical procedure, involves incubation of smooth and rough microsomal fractions with low concentrations of Pb(NO(3))(2) and glucose 6-phosphate. Control experiments, in which enzyme was assayed in the presence of various amounts of Pb(NO(3))(2) or in which microsomal fractions were reisolated after incubation with low concentrations of Pb(NO(3))(2) and glucose 6-phosphate, showed that lead does not interfere with glucose 6-phosphatase activity. 2. Discontinuous sucrose-density-gradient centrifugation of microsomal fractions which had previously been incubated with various amounts of Pb(NO(3))(2) and glucose 6-phosphate showed that it is possible to subfractionate both smooth- and rough-microsomal fractions into several bands, owing to a differential modification of the density of the microsomal vesicles by the trapping of lead phosphate within them. 3. When the material in the bands obtained by density-gradient centrifugation of incubated microsomal fractions was assayed for glucose 6-phosphatase activity, it was found that the modification of the density of the microsomal fractions was directly related to their relative enrichment in glucose 6-phosphatase activity. Control experiments, in which microsomal fractions were incubated with Pb(NO(3))(2) and glucose 6-phosphate and then treated with EDTA, showed that the subfractionation was not due to aggregation of microsomal vesicles, lead and glucose 6-phosphate. Thus the resolution of microsomal preparations into subfractions with different glucose 6-phosphatase activities is interpreted as indicating heterogeneity of glucose 6-phosphatase distribution in the microsomal vesicles. 4. Electron micrographs of both smooth- and rough-microsomal subfractions show deposits of lead phosphate within the microsomal vesicles. The frequency and extent of these deposits correlate with the different amounts of glucose 6-phosphatase activity measured biochemically. 5. The nature of the heterogeneous distribution of glucose 6-phosphatase is discussed and the more general applicability of the technique for studying membrane fractions containing a heterogeneous distribution of phosphatases is indicated.

Survival of root-infecting fungi in soil. 13. Decomposition of flavonoids and other phenolics in soil and their effects on Fusarium root rot of bean

The flavonoids rutin and quercetin and two of their decomposition products, phloroglucinol and protocatechuic acid, were rapidly degraded in soil. Less than 10% of their phenolic nuclei were detected in soil, and from 27 to 57% of their structural carbons remained in soil after 9 weeks of incubation. Phenolic intermediates were not detected in soils amended with rutin or quercetin. There were no differences in the decomposition of any of the substrates in noninfested soil and in soils infested with F. solani f. sp. phaseoli. In pure culture, two virulent isolates of the pathogen could effectively metabolize a glucose–rhamnose mixture and protocatechuic acid, but only one of the isolates could use phloroglucinol and rutin to any great extent. When incorporated into soil at a rate of 0.1% and 0.3%, rutin, phloroglucinol, protocatechuic acid, and a glucose–rhamnose mixture significantly increased propagule numbers of the pathogen over that of the control. From 1 week, to the termination of the experiment after 9 weeks, more than 80% of the propagules of F. solani f. sp. phaseoli existed in the soils as chlamydospores. Propagule numbers were higher in soils amended with 0.3% substrate than in soils amended with 0.1% substrate, and the numbers 1 week after amendment addition were similar to those obtained 9 weeks after amendment addition. In the first and second crops of beans (planted 3 and 6 weeks after amendment incorporation), protocatechuic acid and phloroglucinol, at a concentration of 0.3%, were very effective in reducing root-rot severity. The other amendments, except quercetin, were effective in suppressing disease to various degrees. The effectiveness of the various amendments depended upon amendment concentration and time of planting. Quercetin, added to soil at either concentration, did not increase inoculum density but did increase disease severity.

A reappraisal of vascular effects of hexamethonium

The paper is a study of the contrasting effects of peripheral vasomotion on "ganglionic blockade" versus catecholamine depletion. Displacement plethysmography was reported on ambient temperature in 19 subjects, and digital flow at a constant temperature of 72° with similar clothing and in the horizontal position in 10 subjects. At the conclusion of the plethysmography a crude sweating test was applied to hand and foot in 10 cases. Ganglionic blockade with hexamethonium intravenously, independent of its blood pressure lowering effect, resulted in a slight to moderate decrease in the flow in the index finger and a moderate to significant increase in the flow in the great toe. Normal sweating of the hand and abolition of sweating in the foot was first incidentally observed by noting the moist hand and the warm dry foot during the course of preliminary studies and confirmed by sweating. Catecholamine depletion by guanethidine or bethanidine showed no change in the peripheral vasomotion unless the brachial blood pressure was lowered. It was then found that there was almost always an increased flow in both finger and toe, though usually greater in the toe than the finger. These observations suggest that there is a difference in response between the sympathetic ganglion supply to the upper extremity and that to the lower extremity, as reflected in both vasomotion and sweating.

Effects of tannins on spore germination and growth of Fusarium solani f. phaseoli and Verticillium albo-atrum

Gallotannin, wattle, canaigre, and chestnut tannins in a complete medium affected in vitro spore germination and mycelial growth of Fusarium solani f. phaseoli and Verticillium albo-atrum. The pH values and tannin concentration were important factors determining the effectiveness of tannins as inhibitors. Under acidic conditions (pH 5), gallotannin, canaigre, and chestnut tannins at concentrations varying from 39 p.p.m. to 625 p.p.m. inhibited spore germination of both fungi. At a concentration of 1000 p.p.m. these tannins completely prevented growth at pH 5 of both fungi during a 20-day period. Under near neutral conditions (pH 6–7) there was a minimum inhibition of spore germination and mycelial growth with all tannins tested. Under alkaline conditions (pH 8) there was some degree of inhibition of spore germination, but, in general, growth was similar to that under neutral conditions. Wattle tannin was unusual in that it did not prevent growth of either fungus under acidic conditions although the growth of V. albo-atrum was appreciably reduced compared with the control. Gallotannin, however, prevented growth of both fungi under alkaline as well as acidic conditions.

Ventricular tachycardia associated with the administration of methylphenidate during guanethidine therapy

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Long-Term Follow-up of Patients with Hypertensive Disease Treated with Guanethidine

Sixty-three hypertensive patients treated with guanethidine, usually in conjunction with chlorthalidone, were followed up for periods as long as 2(1/2) years. The guanethidine dosage was not found to be related to the size of the patient, duration of hypertension or its severity. Two patients developed intolerable syncope without satisfactory control of blood pressure. No aggravation of bronchitis or diabetes was observed. Faintness and diarrhea occasioned by the drug lessened with time. Symptomatic improvement was noted in the majority, as was improvement in the optic fundus, the electrocardiogram and the heart size. Four deaths were unrelated to therapy, but were the result of complications of underlying vascular disease.