Subdural electrode recording of generalized photoepileptic responses.

We evaluated the spatiotemporal distribution of photic driving (PDR), photoparoxysmal (PPR), and photoconvulsive (PCR) responses recorded by intracranial electrodes (ic-EEG) in a patient with generalized photosensitivity and right frontal lobe cortical dysplasia. Intermittent light stimulation (ILS) was performed thirteen times in nine days. Cortical responses to ILS recorded by ic-EEG were reviewed and classified as PDRs, PPRs, and PCRs. Photic driving responses were restricted to the occipital lobe at ILS frequencies below 9 Hz, spreading to the parietal and central regions at > 9 Hz. Photoparoxysmal responses commonly presented as focal, medial occipital, and parietal interictal epileptic discharges (IEDs), the latter propagating to the sensorimotor cortices. Generalized IEDs were also generated in the setting of PPRs. Photoconvulsive responses, characterized by repetitive bilateral upper extremity myoclonus sustained until the end of the stimulus, were associated with propagation of the medial parieto-occipital discharge to the primary sensorimotor and supplementary area cortices, while generalized myoclonic seizures were associated with a generalized spike-and-wave discharge with an interhemispheric posterior cingulate onset sparing the sensorimotor cortices. Both types of PCR could occur during the same stimulus. Regardless of the pathway, PCRs only occurred when PDRs involved the parietal cortices. While there may be more than one pathway underlying PCRs, parietal lobe association cortices appear to be critical to their generation.

Accuracy in gamma camera measurements of point source velocities.

Mucociliary clearance is impaired in many diseases of the respiratory system. We have developed a method for measuring tracheal mucus velocity by the dynamic study of a single point source of radioactivity deposited in the trachea by cricothyroid injection. Preliminary results suggest that patients with airways disease have very low tracheal mucus velocities (<2 mm x min(-1)). The aim of this experiment was to explore the ability of current scintillation detection systems to track a single point as it moves in a dynamic study in small increments and at low velocity (movements of the order of 1 mm). Background noise was estimated to contribute an error in positioning of 0.16 mm (1 standard deviation). Overall errors in velocity were estimated at 0.2 mm x min(-1). This suggests that standard instrumentation in use in most nuclear medicine departments has the capacity to measure accurately velocities as low as 1 mm x min(-1).

Lung cancer in New South Wales: current trends and the influence of age and sex.

OBJECTIVE: To examine the effects of time, sex and age at diagnosis on lung cancer incidence rates and the distribution of the histological types of lung cancer in New South Wales. DESIGN AND SETTING: Retrospective analysis of data from the NSW Cancer Registry and Australian Bureau of Statistics population data for NSW for 1985-1995. MAIN OUTCOME MEASURES: Trends in lung cancer incidence rates between 1985 and 1995 for men and women aged over 30 years; changes in incidence rates within age groups; and incidence rates of histological subtypes relative to sex and age. RESULTS: The incidence of lung cancer in men aged 40-80 years fell, while that in women aged over 65 rose. Rates were stable in younger women and older men. Incidence rates in men aged 40-60 years fell by 40%-60%. Were it not for the reduction in incidence rates in men between 1985 and 1995, the number of male lung cancer cases in 1995 would have been greater by 389 (95% CI, 362-415). In women, increasing incidence rates were responsible for an extra 242 cases (95% CI, 232-253) in 1995. Adenocarcinoma comprised a greater percentage of lung cancer cases in younger people, while squamous-cell carcinoma increases steadily with age in both men and women. Women with lung cancer are less likely to have squamous-cell carcinoma (25% for women v. 40% for men) and therefore more likely than men to have adenocarcinoma (35% of new female cases v. 26% for men) or small-cell lung cancer (24% v. 19%). CONCLUSIONS: Increased smoking cessation has seen a halving of lung cancer rates in middle-aged men. Whether this represents delayed or prevented cases is uncertain. The distribution of histological subtypes of lung cancer in women is different from that in men, and it is not clear whether this difference is hormone-dependent or related to historical patterns of smoking.

Integrative research review of risk behaviors among adolescents in rural, suburban, and urban areas.

PURPOSE: The purpose of this integrative review was to describe the state of the science regarding adolescent risk behaviors, with particular emphasis on comparisons among rural, urban, and suburban populations. METHOD: The review was done at two levels, moving from the major national survey studies which included data collected in the late 1980s up to 1993, to more focused topical areas including studies with data collection and publication between 1990 and 1996 within each identified category of adolescent health issues. A total of 137 published works across several disciplines were reviewed. Suggestions for clinical practice were drawn from the significant research findings. In addition, risk behaviors were compared to national baseline data and objectives. RESULTS: The level of research in this topic area was primarily descriptive. Currently, only a small portion of the national objectives for decreasing adolescent risk behaviors have been met. Successful intervention programs, although few in number, usually included not only topical education but also adolescent interaction with peers and support systems to raise awareness and change behaviors. CONCLUSIONS: The risk behaviors for the adolescent population as a whole have been well described. Education alone is not sufficient to change behaviors. Objective outcomes must be identified and health care providers need to use research findings in their practice with adolescents. It is time to intervene with developmentally and culturally appropriate strategies. There was a large gap in the literature regarding risk behaviors and protective factors for rural adolescents. The few studies that included subjects from rural settings indicated that the view that rural adolescents are engaged in fewer or less severe risk behaviors is misleading.