Comparison of informal caregiver and named nurse assessment of symptoms in elderly patients dying in hospital using the palliative outcome scale.

OBJECTIVES: A prospective study of symptom assessments made by a healthcare professional (HCP; named nurse) and an informal caregiver (ICG) compared with that of the patient with a terminal diagnosis. To look at the validity of HCP and ICG as proxies, which symptoms they can reliably assess, and to determine who is the better proxy between HCP and ICG. METHODS: A total of 50 triads of patient (>65 years) in the terminal phase, ICG and named nurse on medical wards of an acute general hospital. Assessments were made using the patient and caregiver versions of the palliative outcome scale (POS), all taken within a 24 h period. Agreement between patient-rated, ICG-rated and HCP-rated POS and POS for symptoms (POS-S) was measured using weighted-κ statistics. Demographic and clinical data on each group of participants were collected. RESULTS: ICG assessments have higher agreement with those of the patient than HCP. Better agreement in both groups was found for physical symptoms, and best agreement was for pain. The worst agreements were for psychological symptoms, such as anxiety and depression, and for satisfaction with information given. Psychological symptoms are overestimated by both ICG and HCP. CONCLUSIONS: ICGs are more reliable proxies than HCPs. A trend for overestimation of symptoms was found in both groups which may lead to undervaluation of the quality of life by proxy and overtreatment of symptoms. This highlights the need to always use the patient report when possible, and to be aware of the potential flaws in proxy assessment. Reasons for overestimation by proxies deserve further research.

Molecular mechanism of rectification at identified electrical synapses in the Drosophila giant fiber system.

Electrical synapses are neuronal gap junctions that mediate fast transmission in many neural circuits. The structural proteins of gap junctions are the products of two multigene families. Connexins are unique to chordates; innexins/pannexins encode gap-junction proteins in prechordates and chordates. A concentric array of six protein subunits constitutes a hemichannel; electrical synapses result from the docking of hemichannels in pre- and postsynaptic neurons. Some electrical synapses are bidirectional; others are rectifying junctions that preferentially transmit depolarizing current anterogradely. The phenomenon of rectification was first described five decades ago, but the molecular mechanism has not been elucidated. Here, we demonstrate that putative rectifying electrical synapses in the Drosophila Giant Fiber System are assembled from two products of the innexin gene shaking-B. Shaking-B(Neural+16) is required presynaptically in the Giant Fiber to couple this cell to its postsynaptic targets that express Shaking-B(Lethal). When expressed in vitro in neighboring cells, Shaking-B(Neural+16) and Shaking-B(Lethal) form heterotypic channels that are asymmetrically gated by voltage and exhibit classical rectification. These data provide the most definitive evidence to date that rectification is achieved by differential regulation of the pre- and postsynaptic elements of structurally asymmetric junctions.

An amphioxus Gli gene reveals conservation of midline patterning and the evolution of hedgehog signalling diversity in chordates.

BACKGROUND: Hedgehog signalling, interpreted in receiving cells by Gli transcription factors, plays a central role in the development of vertebrate and Drosophila embryos. Many aspects of the signalling pathway are conserved between these lineages, however vertebrates have diverged in at least one key aspect: they have evolved multiple Gli genes encoding functionally-distinct proteins, increasing the complexity of the hedgehog-dependent transcriptional response. Amphioxus is one of the closest living relatives of the vertebrates, having split from the vertebrate lineage prior to the widespread gene duplication prominent in early vertebrate evolution. PRINCIPAL FINDINGS: We show that amphioxus has a single Gli gene, which is deployed in tissues adjacent to sources of hedgehog signalling derived from the midline and anterior endoderm. This shows the duplication and divergence of the Gli gene family, and hence the origin of vertebrate Gli functional diversity, was specific to the vertebrate lineage. However we also show that the single amphioxus Gli gene produces two distinct transcripts encoding different proteins. We utilise three tests of Gli function to examine the transcription regulatory capacities of these different proteins, demonstrating one has activating activity similar to Gli2, while the other acts as a weak repressor, similar to Gli3. CONCLUSIONS: These data show that vertebrates and amphioxus have evolved functionally-similar repertoires of Gli proteins using parallel molecular routes; vertebrates via gene duplication and divergence, and amphioxus via alternate splicing of a single gene. Our results demonstrate that similar functional complexity of intercellular signalling can be achieved via different evolutionary pathways.

Differential range and activity of various forms of the Hedgehog protein.

BACKGROUND: The Hedgehog (Hh) family of secreted proteins act as extracellular messengers to control and coordinate growth and differentiation. The mechanism by which Hh protein travels across a field of cells, and results in a range of specific effects relating to the distance from the source, has been the subject of much debate. It has been suggested that the range and activity of the pathway can be linked to modifications of the Hh protein, specifically the addition of lipid groups at N- and C-terminal sites. RESULTS: Here we have addressed the potency of different forms of Hh protein by expressing these in Drosophila, where we are able to precisely establish pathway activity and range in naïve but responsive tissues. As expected, a construct that can produce all forms of Hh recapitulates endogenous signaling potencies. In comparison, expression of a form that lacks the cholesterol moiety (HhN) leads to an extended range, but the product is less effective at inducing maximal Hh responses. Expression of a point mutant that lacks the N-terminal palmitate binding site shows that the palmitoylation of Hh is absolutely required for activity in this system. CONCLUSION: We conclude that the addition of the cholesterol moiety limits the range of the protein and is required for maximal activity, while addition of palmitate is required for all activity. These findings have implications for understanding how Hedgehog proteins move, and thus their potential at influencing distant sites, and concomitantly, how modifications of the signaling protein can affect the efficacy of the response in exposed cells.