Court-ordered assessments and routine access to confidential health information: findings from a regional forensic mental health service.

Health Assessors undertaking court ordered assessments are granted access to material related to the alleged They do not have access to defendant's confidential health records. Defendant's consent must be obtained for their health information to be accessed. One hundred files of court ordered reports were audited, to see whether Health Assessors in a New Zealand regional forensic mental health service had obtained such consent. The results were categorised as follows: Category 1: Consent was provided and health record accessed, c (n = 76). Category 2: Consent was not provided and health information not accessed (n = 5) - included defendants deemed unfit to stand trial and unable to give informed consent (n = 2). Category 3: Consent was not provided but health information accessed (n = 19). Ethical and medico-legal implications of Health Assessors accessing defendant's confidential health records are discussed. Recommendations are made for improving services so that public trust in the integrity of confidential information can be maintained.

Quantitative investigation into methods for evaluating neocortical slice viability.

BACKGROUND: In cortical and hippocampal brain slice experiments, the viability of processed tissue is usually judged by the amplitude of extracellularly-recorded seizure-like event (SLE) activity. Surprisingly, the suitability of this approach for evaluating slice quality has not been objectively studied. Furthermore, a method for gauging the viability of quiescent tissue, in which SLE activity is intentionally suppressed, has not been documented. In this study we undertook to address both of these matters using the zero-magnesium SLE model in neocortical slices. METHODS: Using zero-magnesium SLE activity as the output parameter, we investigated: 1) changes in the pattern (amplitude, frequency and length) of SLE activity as slice health either deteriorated; or was compromised by altering the preparation methodology and; 2) in quiescent tissue, whether the triggering of high frequency field activity following electrode insertion predicted subsequent development of SLE activity - and hence slice viability. RESULTS: SLE amplitude was the single most important variable correlating with slice viability, with a value less than 50 µV indicative of tissue unlikely to be able to sustain population activity for more than 30-60 minutes. In quiescent slices, an increase in high frequency field activity immediately after electrode insertion predicted the development of SLE activity in 100% of cases. Furthermore, the magnitude of the increase in spectral power correlated with the amplitude of succeeding SLE activity (R2 40.9%, p < 0.0001). CONCLUSION: In conclusion, the findings confirm that the amplitude of population activity is a suitable field potential parameter for judging brain slice viability - and can be applied independent of the mechanism of tissue activation.

Impact of variation in tissue preparation methodology on the functional outcome of neocortical mouse brain slices.

The in vitro cortical slice preparation is a widely used tool for electrophysiological investigation of brain neurophysiology. However, slice quality can be highly variable despite attempts to standardise practice. The purpose of this study was to determine the extent to which this variability is due to sensitivity to aspects of the preparation methodology. The study ultilised the no-magnesium seizure-like event (SLE) model and was in two parts. In the first, slice outcome was quantified following a standardised hypoxic-ischaemic insult applied to pre-prepared slices. The hypoxia-induced changes in SLE activity were used to characterise the effect of tissue damage on commonly measured electrophysiological variables. In the second, multivariate data associated with the slice preparation methodology was collected and related to tissue outcome, according to the same SLE characteristics. Hypoxia-ischaemia damage was reflected most strongly in a reduction in SLE amplitude, inter-event frequency and intra-event high frequency activity. The number of active locations was also markedly reduced. In the second part of the study, between 21% and 47% of outcome variation was attributable to variability in the methodological parameters tested. Most important were slice position from the tissue block, depth of slice submersion during recording and the experience level of the experimenter. The latter showed a paradoxical relationship between inexperience, heightened SLE amplitude and reduced spatial viability. While much of the variation in slice outcome remained unexplained, the factors shown to correlate with tissue viability will aid slice experimentalists in preparing tissue of optimal quality for electrophysiological investigation. In particular, using population event amplitude as the sole criterion of slice quality in the no-magnesium model is overly simplistic and must be viewed in the context of spatial activity.

Quantification of neocortical slice diffusion characteristics using pharmacokinetic and pharmacodynamic modelling.

Pharmacological brain slice experiments are complicated by the need to ensure adequate drug delivery deep into the healthy layers of the tissue. Because tissue slices have no blood supply, this is achieved solely by passive drug diffusion. The aim of this study was to determine whether pharmacokinetic/pharmacodynamic (PKPD) modeling could be adapted to estimate drug diffusion times in neocortical brain slices. No-magnesium seizure-like event (SLE) activity was generated in 41 slices (400 µ m). Two anesthetic agents, etomidate (24 µ M, n = 14) and thiopental (250 µ M, n = 14), and magnesium ions (n = 13) were delivered to effect reversible reductions in SLE frequency. Concentration-effect hysteresis loops were collapsed using a first order rate constant model and equilibrium half-lives (t1/2Ke0) derived. The t1/2Ke0 values obtained were consistent with expectations. The median (range) t1/2Ke0 of 83.1 (19.4-330.1) min for etomidate is in keeping with its known slow diffusion into brain slice tissue. Values for etomidate and thiopental (111.8 (27.8-198.0) min) were similar, while magnesium had a significantly faster equilibration rate (t1/2Ke0 of 26.1 (8.6-77.0) min) compared to the anesthetics, as expected for a simple ion. In conclusion, PKPD modeling is a simple and practical method that can be applied to brain slice experiments for investigating drug diffusion characteristics.