Further characterization of the complementation group B temperature-sensitive mutant of respiratory syncytial virus

ts-2, a temperature-sensitive and plaque morphology mutant of respiratory syncytial virus and sole representative of complementation group B, was compared with members of the other complementation groups of respiratory syncytial virus (group A [ts-1] and group C [ts-7]). ts-2 was found to be 10- to 1,000-fold more restricted in growth and ability to spread at restrictive temperatures (37, 38, and 39 degrees C) than at the permissive temperature (32 degrees C). In temperature shift-up experiments, the ts defect of ts-1 and other members of complementation group A was found to effect a late function that was required for at least 13 h in the replicative cycle. The ts lesion of ts-7 affected a function early in the replication cycle. In contrast, ts-2 was not temperature sensitive when studied by the shift-up technique. The discrepancy between the ts plaque property and failure to detect temperature sensitivity during the shift-up experiment was resolved when it was shown that ts-2 had a defect in adsorption or penetration or both at the restrictive temperature. Clonal analysis of revertant ts-2 showed a coordinate restoration of ts+ phenotype ans syncytium-forming capacity. It appears that ts-2 has a defect in a protein that is involved in adsorption and/or penetration of virus and is also responsible for cell fusion activity.     

Effect of thymic polypeptide factor on the cyclic nucleotide system of immunocompetent cells

Thyramine, a polypeptide factor from thymus, at wide range of concentrations increased the cAMP content in rat thymocytes. Increase in the cAMP content was less distinct in spleen lymphoid cells. Thyramine decreased the cGMP content in thymocytes; minimal nucleotide level was found within 15 min of incubation. The data obtained suggest that the rate of lymphocyte maturation is important for response of the cells to the effect of immunoregulating agents.     

The lower cervical spine in trauma: a study of false-negative and false-positive findings

Evaluation of roentgenographic studies of the lower cervical spine may be complicated by posttraumatic immobility, certain body types, and technical factors which produce equivocal findings. False-positive and false-negative findings are reported, with suggestions for additional views and more diagnostic evaluation.     

Synthesis of novel alkyl-aryl polyamide

A laboratory procedure for synthesizing an alkylaryl polyamide curing agent for liquid epoxy resins from commercially available, low cost materials is given. The various chemical reactions required to obtain the desired end-product are described, and several properties of the novel polyamide are listed. This agent was found suitable for producing foamed or frothed epoxy products.     

Crystallinity determination in polymers and a quantitative comparison for polyethylene

A review is given of methods most often used in determining the crystallinity of polymers. In general, emphasis is placed on specific features peculiar to the various techniques rather than experimental aspects. Because of the considerable and increasing use of differential scanning calorimetry, enthalpic methods of crystallinity determination are considered in some detail. The need for a critical selection of parameters representing the fully amorphous and crystalline states is emphasised. This selection can be made for polyethylene, and results of crystallinity determinations using several methods are given for this polymer. Agreement is generally good for unoriented melt-crystallised material (the n.m.r. value is, as expected, anomalous). Interfacial effects are therefore negligible and the structure is adequately represented by a simple two-phase model. Complications arise when polymer is oriented (single crystals grown from solution are included here) and there is little correlation between the various crystallinities.     

Evidence for plasmid-associated crystal toxin production in Bacillus thuringiensis subsp. israelensis

Three crystalliferous (Cry+) strains of Bacillus thuringiensis subsp. israelensis (serotype 14) that produce parasporal protein crystals toxic to dipteran larvae and several acrystalliferous (Cry-) mutants, either induced or spontaneously derived from a single Cry+ parent, were examined for the presence of covalently closed circular (CCC) DNA in attempts to correlate toxin production with the presence of a specific plasmid. The plasmid profiles of both Cry+ and Cry- variants were analyzed by both a cleared lysate- and a modified Eckhardt lysate-electrophoresis technique. All of the Cry- mutants derived from the Cry+ parental strain had lost a 4.0- to 4.4-megadalton (Mdal) plasmid. Bioassay data confirmed loss of toxin production by the Cry- variants. All three Cry+ strains, including the parent of the Cry- strains, contained CCC plasmids DNAs of the following approximate molecular weights: 4.0 to 4.4, 5.2 to 6.0, and 11.4 to 13.0 Mdal. One Cry+ strain contained an additional CCC plasmid of 6.7 to 7.2 Mdal. The plasmid patterns for several Cry- derivatives differed in other respects from the pattern for their parent strain. The various Cry+ and Cry- strains could be distinguished either by phenotypical differences in antibiotic sensitivity, crystal production, and toxicity, or by differences in their plasmid profiles.