Interaction of mycoplasmas and phagocytes

Aspects of the interaction of certain mycoplasmas with macrophages and neutrophils in vivo and in vitro have been studied using two systems, one involving M. pulmonis in mice and the other involving M. bovis with bovine leucocytes. Studies with M. pulmonis indicated that the disappearance of viable organisms from the peritoneal cavity was not enhanced in SPF mice in which a peritoneal exudate rich in neutrophils had been induced. However, viable M. pulmonis organisms disappeared more rapidly from the peritoneal cavities with exudates containing increased numbers of macrophages. Experiments in vitro studied the opsonic effect of bovine IgG isotypes for bovine neutrophils and alveolar macrophages. Both IgG1 and IgG2 promoted killing of M. bovis by alveolar macrophages but IgG2 was more effective than IgG1 at promoting mycoplasma killing by neutrophils. Further studies in vitro indicated that certain bovine mycoplasma could inhibit killing of Escherichia coli by bovine neutrophils.     

Similarities in the heavy and light chains of tetanus toxin suggested by their amino acid compositions

Quantitative comparison of the amino acid compositions of the heavy and light chains of tetanus toxin by the method of Cornish-Bowden [(1983) Methods Enzymol. 91, 60-75)] suggests strongly that there is sequence homology between the two chains and that the heavy chain has two similar halves. Examination (by electrophoresis in polyacrylamide gels in the presence of sodium dodecyl sulphate) of peptides produced from the chains by proteolytic cleavage supports this idea.     

Salt injury to plants with special reference to cations versus anions and ion activities

Summary In contrast with the toxicities of sulfate and chloride salts added to substrates, the anions SO₄ and C1 were not injurious when accumulated without leaf burning by cotton and tomato plants from atmospheres enriched with SO₂ or HC1 gases. The foregoing results are discussed in terms of cationenzyme interactions which appear to represent at least a major cause of salt toxicity. Although anions are largely unreactive with enzymes it has long been observed that chloride salts in soil solutions are far more toxic than sulfate salts. Five of seven species have shown nearly equal growth repressions on substrates with 100 me/1 of C1 salts versus 200 me of SO₄ salts, each added as 50 per cent Na. The ion activities of the two solutions were equal and the sum of cations in the plant saps were similar. The osmotic differentials (average about 10 atm) between the expressed tissue fluids and these substrate solutions were remarkably uniform within species. It is projected that the downward transport of salts via the phloem provides for root concentrations which supply ions to the xylem and thereby control the uptake of substrate salts.     

Viral Antibodies in Diabetes Mellitus

Sera from 123 patients with diabetes mellitus of recent onset, 155 patients with diabetes of more than two years'' duration, and 250 normal persons were collected over a period of two and a half years. All sera were tested for neutralizing antibody to Coxsackie virus types B1–6, and a sample was tested for complement-fixing antibody to a number of viral, rickettsial, and mycoplasmal antigens.In diabetics of recent onset no evidence was found of any excess of antibodies to mumps virus or some common respiratory viruses. Insulin-dependent diabetes within three months of onset were found to have higher antibody titres to Coxsackie B virus, particularly of type B4, than either normal subjects or patients with diabetes of longer duration.