Effect of beef broth protein on the thermal inactivation of staphylococcal enterotoxin B1.

Enterotoxin B produced by Staphylococus aureus 243 in brain heart infusion broth was concentrated by dialysis against 40% polyethylene glycol (20 M), partially purified on a Sephadex G-100 column and heated at 110 degrees C in thermal death time cans. Various heating menstrua included 0.04 M Veronal buffer (pH 7.4), beef broth, and fractions of beef broth obtained by ultrafiltration or precipitation with ammonium sulfate. The toxin was assayed serologically using the microslide gel double-diffusion method. The time requiring for 90% inactivation at 110 degrees C (D110 value) obtained in buffer and in beef broth was 18 and 60 min, respectively. When the concentration of beef broth was increased fivefold, the D110 increased to 78 min. The apparent protective effect or protein was further investigated using beef broth protein obtained by precipitation with (NH4)2SO4. The D110 values were 51 and 70 min when the protein concentration in the heating menstruum was 3.8 and 7.7 mg/ml, respectively. However, when the beef broth protein was dialyzed against buffer before use as a heating menstrum, the D110 was only 39 or 41 min at comparable protein concentrations. Results indicated a dialyzable factor, whose protective effect was partially destroyed by trypsin and chymotrypsin but did not by disodium ethylenediaminetetraacetate, was involved in the protection of enterotoxin B during heating.     

Ultra-short acting beta-blockers: a proposal for the treatment of the critically ill patient

Beta-blockade is of proven value in the therapy of acute myocardial infarction but, unfortunately, may produce cardiac failure by removal of needed sympathetic support. The long duration of action of available blockers (hours) makes reversal of failure a complicated problem and precludes rapid modification of therapy to match changing autonomic conditions. To improve the safety and efficacy of beta-blockade in this setting we have developed the concept of ultra-short beta-blockade and have identified a novel beta-blocker (ASL-8052) which possesses a duration of action less than 15 minutes. This compound is cardioselective and possesses efficacy in an animal model of acute myocardial infarction. It, therefore, appears to be suitable for rapid attainment of controlled levels of beta-blockade via intravenous infusion and rapid recovery from beta-blockade if required by the clinical situation. The compound should, therefore, be useful for safe therapy in critically ill cardiac patients.     

Increased root exudation of14C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria

Summary Organic components leaked fromSorghum bicolor seedlings (‘root exudates’) were examined by recovering¹⁴C labelled compounds from root solutions of seedlings inoculated withAzospirillum brasilense, Azotobacter vinelandii orKlebsiella pneumoniae nif-. Up to 3.5% of the total¹⁴C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of¹⁴C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of¹⁴C in the solutions did not occur. Quantities of¹⁴C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with¹⁴CO₂, about 15% of the total¹⁴C recovered within 48 hours exposure was found in soil leachates.     

Gamma-ray irradiation as a pretreatment for the enzymatic hydrolysis of cellulose

Summary The susceptibility of cellulose to enzymatic hydrolysis can be significantly affected through pretreatment by means of gamma-ray radiation. Experiments were carried out to investigate the effects of this radiation on enzymatic hydrolysis and on the two major structural features of cellulose that most influence hydrolysis, namely, specific surface area and crystallinity.D. H. Beardmore is currently with Phillips Petroleum Company, Bartlesville, OK 74004, U.S.A.     

Pituitary corticotropin-inhibiting peptide: Properties and use in study of corticotropin action

The biological properties of the naturally occurring pituitary peptide α_h^7–38-adrenocorticotropin (ACTH) have been investigated. α_h^7–38-ACTH is devoid of steroidogenic activity but inhibits competitively ACTH-induced steroidogenesis in vitro as well as in vivo. The long-term actions of ACTH on normal and tumor adrenal cells in culture are also antagonized by α_h^7–38-ACTH. The apparent K_i for the inhibition of cyclic AMP production by α_h^7–38-ACTH (301 ± 62 nm) was significantly higher than the apparent K_i for the inhibition of corticosterone synthesis (21.6 ± 6.8 nm). Analysis of the inhibition of ACTH-induced steroidogenesis and cyclic AMP production in normal rat adrenocortical cells indicates that two separate receptors may be involved in mediating these responses.     

Immunological and biochemical analysis of a null mutant of α-glycerolphosphate dehydrogenase from Drosophila melanogaster

Summary A Drosophila null mutant(BO-1-4) of -glycerolphosphate dehydrogenase induced by ethylmethane sulfonate(EMS) was analyzed by double immunodiffusion, enzyme immuno-inactivation, immunoelectrophoresis and two-dimensional electrophoresis. Based on all the immunological evidence, this mutant appears to express no protein that can cross-react with the antiserum specific to -glycerolphosphate dehydrogenase. A protein spot corresponding to -glycerolphosphate dehydrogenase was identified on two-dimensional gels of the soluble fly homogenates. The absence of this protein spot on two-dimensional gels of this null mutant further supported the immunological data. The activities of seven other enzymes in the related metabolic pathways were determined for the mutant and the control Drosophila. The null mutant does not show significant alterations in activities of these enzymes. The relationship between the deficiency of this enzyme and the inability for the sustained flight of the null mutant was discussed in terms of cellular metabolic regulations.Abbreviations used -GPD -glycerolphosphate dehydrogenase (EC 1.1.1.8) - EMS ethylmethane sulfonate - TEMED N,N,N,N-tetramethylene diamine - pI isolectric point - CRM immunological cross-reacting material     

The effect of reserpine, oestradiol and in-vitro perfusion on oviduct calcium levels in the mouse during egg transport.

Mouse oviduct calcium content, determined by atomic absorbance after ashing of the tissue, showed a significant fall on Day 2 of pregnancy followed by a significant rise on Day 3. This pattern was altered by administration of reserpine and oestradiol in doses which were shown to alter the rate of egg transport. In-vitro perfusion of the oviduct, capable of maintaining muscular activity and back and forth movement of eggs for 24 h, was associated with lack of forward progressive motion of eggs and by a more rapid increase in tissue calcium levels during incubation than occurred in vivo.