Auditory frequency discrimination in children with specific language impairment: a longitudinal study.

It has been proposed that specific language impairment (SLI) is caused by an impairment of auditory processing, but it is unclear whether this problem affects temporal processing, frequency discrimination (FD), or both. Furthermore, there are few longitudinal studies in this area, making it hard to establish whether any deficit represents a developmental lag or a more permanent deficit. To address these issues, the authors retested a group of 10 children with SLI and 12 control children first tested 42 months previously. At Time 1, the children with SLI (between 9 and 12 years of age) had significantly elevated FD thresholds compared to the matched controls. At Time 2, the thresholds of both groups had improved, but the children with SLI still had poorer FD thresholds than those of the controls. To assess temporal resolution, auditory backward masking was measured and it was found that most of the children with SLI performed as well as the controls, but 2 children had exceptionally high thresholds. There was also greater variability among the children with SLI compared to that measured among the controls on the FD task. These studies indicate considerable heterogeneity in auditory function among children with SLI and suggest that, as with auditory temporal deficits, difficulties in FD discrimination are important in this population.

Fungal endocarditis after homograft valve replacement: difficulties in diagnosis and treatment.

Fungal endocarditis is an uncommon but important problem after cardiac surgery. Two cases of fungal endocarditis after homograft valve replacement are reported. In both patients prolonged periods of antifungal chemotherapy with apparently satisfactory clinical responses ultimately failed to eradicate the infection. Both patients remain free of infection two years after excision of the infected valves and further chemotherapy. The value of serial estimations of fungal antibody titres in diagnosis and treatment is demonstrated and the necessity for early operation is emphasised.

Prevention of spontaneous leukemia in mice by oncornavirus immunization.

C57L, NIH, and SWR mice were immunized with inactivated Gross leukemia virus (GLV) and then mated with AKR males. Their F1 offspring were then immunized with the murine sarcoma virus pseudotype of GLV, MSV(GLV). The concentrations of infectious ecotropic AKR virus in tail extracts of immunized mice were 100- to 1,000-fold lower than in non-immunized controls when tested at 30--40 days of age. Although viral titers increased slightly with time, the titers remained at least one log10 lower in the immunized mice than in non-immunized F1 control mice at all times tested. The reduction in the level of expression of endogenous ecotropic virus showed a highly significant positive correlation with the reduction in incidence of spontaneous leukemia in these mice. These data thus show that successful immunoprevention of leukemia in mice can be achieved with viral vaccines.

Suppression of murine type-C RNA virogenes by type-specific oncornavirus vaccines: prospects for prevention of cancer.

Immunization of crossbred and F1 mice with combined killed and live Gross leukemia virus AKR type-C viral vaccines suppressed endogeneous N-type AKR virus up to 10,000-fold for significant periods during early life. Since several previous studies in the same and similar crossbred systems revealed direct correlations between low and high levels of type-C virus early in life with low and high incidences of leukemia and other cancers later in life, we believe that prospects for suppression of spontaneous neoplasms are good; however, 8-14 months will be required to achieve the final results. Should cancers be prevented by serotype-specific vaccines, such evidence would provide conclusive proof of endogenous viral etiology.

Chemical and antigenic analysis of the cell walls of Neisseria meningitidis group B.

Vedros, Neylan A. (Naval Medical Research Institute, Bethesda, Md.), and Paul R. Hill. Chemical and antigenic analysis of the cell walls of Neisseria meningitidis group B. J. Bacteriol. 91:1992-1997. 1966.-Cell walls have been isolated from Neisseria meningitidis group B, by rapid freeze-thawing or treatment with sodium deoxycholate. Chemical analysis of the cell walls indicated that the amino acid composition, and content of hexosamines and of lipids, were similar to those reported for Escherichia coli, except for higher concentrations of alanine, methionine, glutamic acid, and phenylalanine. The meningococcal cell walls showed groupspecificity in the complement-fixation test, were nontoxic for rabbits, and in rabbits produced antibodies which protected mice from challenge with the homologous strain.