ABSTRACT
Insect flight muscle fibres were relaxed by the combined action of MgAMPPNP and ethylene glycol, as measured by the stiffness of the fibres. Relaxation occurred over a small range of glycol concentration. Addition of Ca2+ raised the glycol required for relaxation. The speed at which the stiffness measurement was made did not influence the glycol concentration at which relaxation occurred. Glycol in excess of that needed to relax the muscle caused a slight rise in high-frequency stiffness. Removal of the glycol restored the rigor stiffness. Under glycol-relaxed conditions, much of the AMPPNP bound in muscle fibres was retained during cold-chase (elution of [3H] AMPPNP by nonradioactive AMPPNP); the intensity ratio of the inner equatorial X-ray diffraction peaks rose upon glycol relaxation to a value slightly below that characteristic of natural relaxation. The results are interpreted in terms of cooperative attachment of the crossbridges to actin.
Subject(s)
Adenosine Triphosphate/analogs & derivatives , Adenylyl Imidodiphosphate/pharmacology , Ethylene Glycols/pharmacology , Muscle Contraction , Muscle Relaxation , Animals , Biomechanical Phenomena , Ethylene Glycol , Insecta , Muscle Rigidity , Muscles/drug effects , Nucleotides/metabolism , Osmolar Concentration , X-Ray DiffractionABSTRACT
The skin flora of 20 normal subjects was sampled from 7-cm2 sites on the volar forearm, forehead and ball of the foot. Interactions between all aerobic and anaerobic strains isolated from the same site were examined by a deferred-antagonism technique. Seventeen subjects possessed inhibitory strains on at least one skin site. Of the Micrococcaceae tested, 20.6% were inhibitory. Of the aerobic diphtheroids, more strains were sensitive (19.2%) than inhibitory (5.1%). Inhibitory Micrococcaceae and aerobic diphtheroids revealed intergeneric and intrageneric inhibition. Antagonistic propionibacteria were found (7.4%) but no sensitive strains. Several Micrococcaceae were specifically antagonistic towards only one strain isolated from the same skin site; no sensitive strains from other skin sites or other subjects were found. Quantitative sampling showed that only 17.5% of the inhibitory strains clearly dominated their skin sites numerically.
Subject(s)
Bacteria/isolation & purification , Skin/microbiology , Adult , Anti-Bacterial Agents/pharmacology , Antibiosis , Bacteria/drug effects , Female , Humans , Male , Middle AgedSubject(s)
Bacteriocins/analysis , Analysis of Variance , Biological Assay , Densitometry , Methods , Pseudomonas aeruginosaSubject(s)
Penicillium , Spores , Centrifugation , Freeze Drying , Glutamates , Methods , Penicillium chrysogenum , Spores, FungalABSTRACT
Purified pyocin, administered parenterally to mice infected with sensitive strains of Pseudomonas aeruginosa, afforded significant protection against two of the three strains studied.
