N2 and P3 modulation during partial inhibition in a modified go/nogo task.

The neural response following the partial inhibition of responses can provide insight into the processes underlying response inhibition. We examined the N2 and P3 on trials where participants correctly responded to go stimuli, successfully inhibited their response to nogo stimuli, and nogo trials where they initiated but did not complete their response (partial inhibitions) in an adult sample (N=24, M(age)=21.17, SD(age)=3.52). An enhanced and delayed N2 was observed on partially inhibited compared to successfully inhibited nogo trials. Further analysis showed that this modulation was error-related. An enhanced central P3 was observed following successful inhibitions compared to correct go trials, but not following partial inhibitions. The results suggest that the central P3 enhancement is specific to the complete and successful inhibition of responses. Therefore, the absence of a central P3 on partial inhibitions could reflect insufficient inhibition or a monitored failure in inhibiting the response. Although, our findings provide support for the role of P3 in response inhibition, it raises questions about the processes involved in the subsequent inhibition or correction of the erroneous response. Further research examining the neural response following both partial and unsuccessful inhibitions could provide insight regarding these processes.

Personal NO2 exposure monitoring shows high exposure among ice-skating schoolchildren.

A method for measuring personal nitrogen dioxide (NO2) exposure, using passive samplers, was tested among schoolchildren. Activity patterns and NO2 exposure levels were studied in relation to urban and rural living. Stationary air monitoring data indicated that the urban children were supposed to be exposed to NO2 levels that were among the highest in Sweden. It was shown that NO2 levels measured at the stationary air monitoring station were not representative for the children's exposure. The children spent 90% of their time indoors; only a small percentage of their time was spent in transit. The median daily NO2 exposure level in the urban area (13 micrograms NO2/m3, 7 ppb) was significantly higher (p < .001) than in the rural area (7 micrograms NO2/m3, 4 ppb). The most important source of exposure was the indoor ice-skating arenas, where levels up to 8,000 micrograms NO2/m3 (4 240 ppb) were measured during 1-h periods.

Prognostic factors in breast cancer--a pathological and immunological study of patients with stage 1 breast cancer.

In order to analyze which features determine a poorer prognosis we undertook a study of 91 consecutive patients with pathological Stage I breast cancer operated on at Beth Israel Medical Center (1968-71). Tumor tissue slides were reviewed and features such as: tumor size, histologic type, nuclear grade, lymphocytic and perivenular lymphocytic infiltration, as well as sinus histiocytosis in the lymph nodes removed. Records were reviewed and classified according to age and ethnic background. Survival and recurrence data were recorded up to 14 years post-mastectomy. Also determined was the presence of an antigen, previously detected in certain human breast cancer tumor tissues, which has been found to cross-react immunologically with the 52,000 dalton major envelope protein of the mouse mammary tumor virus (MMTV--gp52). Ten-year cumulative disease-free survival was 0.65. Univariate analysis of survival within various factors revealed that the only statistically significant influencing factor was the presence or absence of the antigen. Factors such as perivenous lymphocytic infiltration, diffuse lymphoid infiltration and sinus histiocytosis in regional lymph nodes also showed trends in favor of improved survival but the sample may be too small for statistical significance. The presence or absence of the antigen was independent of the host immunological reaction. There was no relationship between localization of tumor, whether medial or lateral and survival, nor with presence or absence of antigen.