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Isolation and characterization of outer and inner membranes of Selenomonas ruminantium: lipid compositions.

The isolation procedure and characterization of the outer and inner membranes from Selenomonas ruminatium cells, a strictly anaerobic bacterium, are described. The metabolic fate of [14C]decanoate incorporated into the outer and inner membranes was examined. The percent distribution of radioactivities in the outer and inner membranes was about 40 and 50% of the total incorporated activity, respectively. Approximately 47% of the radioactivity incorporated into the outer membrane was recovered in the phospholipid fraction, and the remaining radioactivity was found in both aqueous and phenol layers when the outer membrane was treated with phenol-water. In contrast to [14C]decanoate, the percent distribution of [3H]glycerol in the outer and inner membranes was about 25 and 70% of the total incorporated activity, respectively. Most of the assimilated 3H was located in the phospholipid fraction of both membranes. However, no significant label was detected in either the protein or cell wall fraction. The following observations were made concerning lipid compositions in the outer and inner membranes by chemical and isotopic analyses. (i) The outer and inner membranes contained no detectable phosphatidyl glycerol or cardiolipin. (ii) A prominent radioactive compound, designated band III lipid, was found mainly in the outer membrane as a major radioactive spot when cells were grown with [14C]decanoate. This lipid contained phosphorus, 2-keto-3-deoxyoctulosonic acid and 3-OH fatty acid but no detectable glycerol. This lipid was identified tentatively to be 2-keto-3-deoxyoctulosonic acid-lipid A. (iii) Although the ubiquity of phosphatidyl ethanolamine plasmalogen in both outer and inner membranes was confirmed, the occurrence of the molecular species of phosphatidyl ethanolamine plasmalogen was quite different in the outer and inner membranes.

Aldehydes↗

Growth of Arthrobotrys superba from a birch wood resource base into soil determined by radioactive tracing.

The ability of a nematode-trapping fungus to establish in field soil is an important characteristic when considering its use as a biological control agent. The outgrowth of the nematode-trapping fungus Arthrobotrys superba from wood was recorded by labelling the fungus with [(14)C]3-O-methylglucose and [(32)P]orthophosphoric acid and by using the soil sprinkling method. The fungus reached a distance of 7-8 cm during 25 days in heat-treated (60 degrees C) soil, detected by either radioactive tracing or the soil sprinkling technique. The two labelled compounds were co-distributed at all sampling times (r(2)=0.946) which indicates that the glucose pool (as methylglucose) and phosphorus content were correlated throughout the mycelium. In natural, non-heat-treated soil the fungus reached a distance of 1.5 cm from one disc of birch wood after 30 days, while it reached 3.2 cm during the same period when the food base was a pile of five inoculated discs. The experiments showed, for the first time, that a nematophagous fungus, A. superba, can grow out into soil from a piece of wood and supported by nutrients translocated from the resource base to the edge of the mycelium.

Journal Article↗

Internal irradiation for cystic craniopharyngioma.

The authors report the results of internal irradiation with labeled chromic phosphate (32P) and gold-198 (198Au) colloid in eight cases of cystic craniopharyngiomas. They used a newly developed dosimetric formula, by which the radiation dose at the cyst wall and at any point far from the radioactive source can be calculated. Ten courses of irradiation in eight patients were carried out by injection of either 32P or 198Au colloid into the cyst through an Ommaya drainage system that had been placed at craniotomy. Follow-up studies ranging from 13 to 156 months revealed that all cysts were effectively treated, with elimination of fluid or collapse of the cyst. This was confirmed by Conray cystography and/or computerized tomography. Not only the dose delivered to the wall but also the thickness of the cyst wall and the location of the cyst are important factors in planning internal irradiation. A safe and adequate dose to the cyst wall could range between 9000 to 30,000 rads for craniopharyngioma. This treatment is suitable for large cysts that are thought to be difficult to remove radically, recurrent cysts resistant to previous treatment, or multiple cysts. Internal irradiation may also be applicable in other cystic intracranial tumors if dosimetry is calculated accurately.

Adolescent↗

Comparison of the effects of dobutamine and isoproterenol in ischemic hearts by phosphorus-31 nuclear magnetic resonance spectroscopy.

We compared the effects of 2 inotropic agents, dobutamine and isoproterenol on regional coronary blood flow, contractile function, hemodynamics and levels of phosphate compounds in the acutely ischemic canine heart. Dogs were instrumented to determine regional coronary blood flow (non-radioactive microsphere method), contractile function (sonomicrometry), and hemodynamics. Myocardial phosphate compounds were measured simultaneously by the phosphate-31 (31P) magnetic resonance spectroscopic technique. Both drugs augmented the global performance of the heart, but produced no significant improvement in regional contractile function in the ischemic region. Isoproterenol significantly increased the ratio of inorganic phosphate to phosphocreatine in the ischemic region, as compared to dobutamine. However, no significant differences were seen in myocardial lactate consumption with inotropic stimulation between the 2 groups. 31P magnetic resonance spectroscopy could be used to differentiate between the effects of dobutamine and isoproterenol on energy metabolism in ischemic myocardium despite the lack of significant differences in regional function and myocardial lactate consumption. The significant tachycardia without an augmentation of systemic blood pressure induced by isoproterenol may account for this unfavorable effect on myocardial energy metabolism.

Animals↗

On the synthesis of a 32P-labelled Edman reagent for the sensitive identification of amino-acid derivatives.

A phosphorus-32 containing derivative of phenylisothiocyanate was prepared to increase the sensitivity of amino-acid sequence determination. The respective compound 2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinane 2-oxide showed about the same reactivity, stability, and polarity as the Edman reagent itself. A repetitive yield of 94% was obtained in the stepwise degradation of insulin B chain using a solid phase sequencer. The synthesis of this radioactive reagent was achieved within 5 h but with a specific activity of 1 Ci/mol. Eight amino acids were reacted with the 32P-labelled reagent and identified by autoradiography after two dimensional thin-layer chromatography.

Amino Acid Sequence↗