Visual event-related potentials in first-episode psychotic patients and their relatives

We conducted a comprehensive examination of the sensory visual event-related potential (ERP) of psychiatric patients and their relatives using a methodology that improves upon those used previously by other investigators. One hundred thirty-five patients at the onset of their first psychotic episode, 146 first-degree relatives of these patients, and 113 normal controls were exposed to light flashes of four different intensities while their ERPs were recorded from three central scalp sites. For most analyses, various ERP amplitude measures did not discriminate the different psychiatric groups or their relatives either from one another or from the normal controls. These findings indicate that patients with schizophrenia, schizophreniform disorder, and affective disorder at the early stage of their illness do not display significant deficits in the processing and regulation of simple sensory visual stimulation.     

The impact of sleep duration and subject intelligence on declarative and motor memory performance: how much is enough?

Recent findings clearly demonstrate that daytime naps impart substantial memory benefits compared with equivalent periods of wakefulness. Using a declarative paired associates task and a procedural motor sequence task, this study examined the effect of two lengthier durations of nocturnal sleep [either a half night (3.5 h) or a full night (7.5 h) of sleep] on over-sleep changes in memory performance. We also assessed whether subject intelligence is associated with heightened task acquisition and, more importantly, whether greater intelligence translates to greater over-sleep declarative and procedural memory enhancement. Across both tasks, we demonstrate that postsleep performance gains are nearly equivalent, regardless of whether subjects obtain a half night or a full night of sleep. Remarkably, the over-sleep memory changes observed on both tasks are very similar to findings from studies examining performance following a daytime nap. Consistent with previous research, we also observed a strong positive correlation between amount of Stage 2 sleep and motor skill performance in the full-night sleep group. This finding contrasts with a highly significant correlation between spectral power in the spindle frequency band (12–15 Hz) and motor skill enhancement only in the half-night group, suggesting that sigma power and amount of Stage 2 sleep are both important for optimal motor memory processing. While subject intelligence correlated positively with acquisition and retest performance on both tasks, it did not correlate with over-sleep changes in performance on either task, suggesting that intelligence may not be a powerful modulator of sleep's effect on memory performance.     

Reconstruction of three-dimensional anatomical landmark coordinates using video-based stereophotogrammetry

A method is described for reconstructing the 3-dimensional coordinates of anatomical landmarks from multiple video images. This method consists of 2 stages: (1) separate reconstructions of landmark coordinates visible in dorsal and ventral orientations using Direct Linear Transformation (Abdel-Aziz & Karara, 1972), and (2) least-squares alignment of the partial reconstructions using landmarks present in both. The repeatability of the overall reconstructions and of individual landmarks were assessed by performing multiple independent reconstructions of landmark coordinates for 2 canid specimens. Results indicate that the repeatability of interlandmark distances based on stereophotogrammetric reconstructions from standard-resolution video images is comparable to that of caliper measurement, and slightly superior to that of electronic 3-dimensional digitisation. At least 4 images should be available per landmark for optimal repeatability, but additional images allow only a slight increase in repeatability.     

Involvement of tobacco in alcoholism and illicit drug use

Survey data from the United States indicate that tobacco use is associated with the initiation of use of other addicting substances, and that increasing levels of tobacco use are associated with increasing levels of use of other psychoactive substances. Furthermore, factors affecting initiation, abstinence, and relapse to the use of tobacco, alcohol, and opioids are similar in nature. In addition, there are similarities in the addictive processes underlying the use of these substances. Taken together, these data suggest that tobacco use is involved, possibly more than by simple association, in the use of other substances containing psychoactive chemicals. In the present paper we discuss the involvement of tobacco in the use of alcohol, opioids, cocaine, and other substances, as well as some of the implications of these observations for researchers and clinicians. One such implication is that it may be possible to use tobacco and nicotine as models for phenomena of interest to other substance use researchers. For example, drug abuse treatment and prevention strategies could be explored using tobacco use as a target behavior, and biological phenomena such as the development of tolerance and physical dependence may be more readily studied with nicotine than with many other drugs. Certain pharmacologic differences across substances are also discussed in tight of their implications for development of treatment and drug control policies.     

THE CHEMISTRY AND CONFORMATIONAL AND BIOLOGICAL ANALYSIS OF VITAMIN D3, ITS METABOLITES AND ANALOGUES

The chemical properties, sterochemical relationships and solution confromation, as assessed in part by proton NMR spectroscopy, for vitamin D₃, its major metabolites [including 1α, 25-(OH)₂ D₃, its hormonally active form] and a number of A-ring and side chain analogues are evaluated and discussed in relation ot their biological activity. In particular the relative ability of many of these seco-steroids to compet both with 25-OHD₃ for its chick serum binding protein and 1α, 25-(OH)₂-D₃ for its chick intenstinal cytosol-chromation receptor systme was quantitated, in vitro , Further, the relative effectiveness of all these metabolites and analogues to mediate in vivo intestinal calcium absorption and bone calcium mobilization was determined. Collectiveily these chemical and bilogical studies constitute a 'systems analysis'of the various steroid structural parameters both required and tolerated by the multi-stepped endocrine system associated with the bilogical actions of vitamin D.