Obtaining surrogate consent for a minimal-risk research study in the intensive care unit setting.

BACKGROUND: Obtaining surrogate consent for clinical research studies conducted in the intensive care unit (ICU) setting is logistically challenging. PURPOSE: To determine whether differences in proportions consenting to trial enrollment existed among patients eligible to consent directly versus those requiring surrogate decision makers in a minimal-risk study to evaluate the accuracy of continuous glucose monitoring in the ICU setting. METHODS: Low initial enrollment rates prompted a detailed tracking of the screening and consent process. We analyzed the subset of eligible patients identified during a single year to document whether they were approached about trial enrollment, whether they consented or declined, the reasons for declining, and the method of consent (self or surrogate). The proportion of participants who consented and the reasons for declining were compared for self-consenting and surrogate-consenting participants. RESULTS: Of the 3041 patients screened, one-third (n = 982) were eligible; 119 of the 982 were approached regarding enrollment. Absence of a surrogate accounted for the majority of eligible patients (726; 84%) not approached. The most common reasons for refusal in the self versus surrogate groups included feeling overwhelmed (13% vs 24%), fear of discomfort (22% vs 12%), and fear of risk (7% vs 4%). Of the 57 eligible patients capable of consenting directly, 11 (19%) enrolled versus 12 (19%) of the 62 who required surrogate consent. When recruitment hours were expanded to include evening time, more eligible patients or their surrogates could be approached than during the day-shift hours alone. Consent was obtained for a larger proportion of potential participants with a history of diabetes (40%) than for those without a history of diabetes (14%). LIMITATIONS: The findings are from a subset of the entire study sample; data were available only for participants who could be approached, who may have differed from those who could not be approached. CONCLUSIONS: Surrogate and self-consent rates were similar. Surrogate unavailability was a major barrier to enrollment; overlap of staffing with usual visiting hours should be considered when planning trials in the ICU.

Neuronal type-specific gene expression profiling and laser-capture microdissection.

The human brain is an exceptionally heterogeneous structure. In order to gain insight into the neurobiological basis of neural circuit disturbances in various neurologic or psychiatric diseases, it is often important to define the molecular cascades that are associated with these disturbances in a neuronal type-specific manner. This can be achieved by the use of laser microdissection, in combination with molecular techniques such as gene expression profiling. To identify neurons in human postmortem brain tissue, one can use the inherent properties of the neuron, such as pigmentation and morphology or its structural composition through immunohistochemistry (IHC). Here, we describe the isolation of homogeneous neuronal cells and high-quality RNA from human postmortem brain material using a combination of rapid IHC, Nissl staining, or simple morphology with Laser-Capture Microdissection (LCM) or Laser Microdissection (LMD).

Gene expression profiling of substantia nigra dopamine neurons: further insights into Parkinson's disease pathology.

Parkinson's disease is caused by a progressive loss of the midbrain dopamine (DA) neurons in the substantia nigra pars compacta. Although the main cause of Parkinson's disease remains unknown, there is increasing evidence that it is a complex disorder caused by a combination of genetic and environmental factors, which affect key signalling pathways in substantia nigra DA neurons. Insights into pathogenesis of Parkinson's disease stem from in vitro and in vivo models and from postmortem analyses. Recent technological developments have added a new dimension to this research by determining gene expression profiles using high throughput microarray assays. However, many of the studies reported to date were based on whole midbrain dissections, which included cells other than DA neurons. Here, we have used laser microdissection to isolate single DA neurons from the substantia nigra pars compacta of controls and subjects with idiopathic Parkinson's disease matched for age and postmortem interval followed by microarrays to analyse gene expression profiling. Our data confirm a dysregulation of several functional groups of genes involved in the Parkinson's disease pathogenesis. In particular, we found prominent down-regulation of members of the PARK gene family and dysregulation of multiple genes associated with programmed cell death and survival. In addition, genes for neurotransmitter and ion channel receptors were also deregulated, supporting the view that alterations in electrical activity might influence DA neuron function. Our data provide a 'molecular fingerprint identity' of late-stage Parkinson's disease DA neurons that will advance our understanding of the molecular pathology of this disease.