Retrospective spatial analysis of cases of COVID-19 in a single military accommodation block corridor, RMAS, January-March 21

Shared ablutions and stairwells, corridor cross-ventilation and non-deliberate perflation (natural draft blowing through a space) are potential risk factors for COVID-19 transmission in corridor-based accommodation. This paper uses retrospective spatial analysis to identify potential built environmental risk factors during the January-March 2021 outbreak in Victory College, Royal Military Academy Sandhurst.Distance was measured in units of single room spacing. Odds, ORs and 95% CIs were calculated to identify and measure associations between distance from exposure and having COVID-19. Distance response trends were assessed using Pearson's χ2 for trend test. Linear relationships were tested using the t-test or rank-sum test.Stairwells and ablutions were not identified as likely sources of infection for all corridor occupants. Assuming occupants used their nearest ablutions, closer distance among those attributed to using ablutions 2 (one of four sets of ablutions), was identified as a risk factor (p=0.05). Testing distance response by χ2 linear trend testing showed a potential association between nearest adjacent positive room and COVID-19 (p=0.06), strongest if dominant air movement along the corridor length was from the left (p=0.10) compared with the right (p=0.24).Formal qualitative spatial analysis and environmental assessment of ventilation and air movement has a role in outbreak investigation in assessing factors related to the built environment. Environmental investigations would best inform outbreak investigations if undertaken contemporaneously. Pre-emptive and retrospective studies can help inform public health advice to military establishments in business continuity planning for isolation facilities, during outbreaks or in future development of the built environment.

Efficacy and Toxicity of Stereotactic Body Radiotherapy for Early to Advanced Stage Hepatocellular Carcinoma - Initial Experience From an Australian Liver Cancer Service

AIMS

Intrahepatic progression remains the predominant mode of cancer-related death in hepatocellular carcinoma (HCC) underscoring the need for effective local therapies. We report our initial experience with liver stereotactic body radiotherapy (SBRT) in the management of early to advanced stage HCC at an Australian tertiary liver cancer service.

MATERIALS AND METHODS

Patients with liver-confined HCC unsuitable for surgical resection or thermal ablation treated with SBRT between October 2013 and December 2018 were retrospectively evaluated. The primary end point was freedom from local progression. Secondary end points were progression-free survival, disease-specific survival, overall survival and toxicity.

RESULTS

Ninety-six patients were treated for 112 lesions (median size 3.8 cm, range 1.5-17 cm). The median follow-up was 13 months (range 3-65). Forty-six patients had received prior local therapies (median 1, range 1-5), 83 (86%) patients had cirrhosis with baseline Child-Pugh scores of A (88%) and B7-8 (12%). Fifty-nine (61%) patients had Barcelona Clinic Liver Cancer (BCLC) stage 0/A disease and 37 (39%) had stage B/C. Macrovascular invasion was present in 20 (21%). The median biologically effective dose (BED₁₀) was 86 and 60 Gy for the BCLC 0/A and B/C cohorts, respectively. Freedom from local progression at 18 months was 94% for BCLC 0/A and 74% for BCLC B/C. Progression-free survival and overall survival at 12 months were 80 and 95% for BCLC 0/A and 40 and 71% for BCLC B/C, respectively. Five patients (7%) with cirrhosis and without disease progression had an increase in Child-Pugh score >1 within 3 months of SBRT, four of whom had intercurrent infections. Clinical toxicities grade ≥2 were reported in 20% of patients.

CONCLUSION

SBRT is an effective ablative modality for early stage HCC with low rates of significant toxicity. Lower dose SBRT can provide durable local control for advanced stage HCC. However, out-of-field relapse remains common, providing a rationale to investigate SBRT in combination with other therapies.

Targeting chondroitinase ABC to axons enhances the ability of chondroitinase to promote neurite outgrowth and sprouting

BACKGROUND

There is currently no effective treatment for promoting regeneration of injured nerves in patients who have sustained injury to the central nervous system such as spinal cord injury. Chondroitinase ABC is an enzyme, which promotes neurite outgrowth and regeneration. It has shown considerable promise as a therapy for these conditions. The aim of the study is to determine if targeting chondroitinase ABC expression to the neuronal axon can further enhance its ability to promote axon outgrowth. Long-distance axon regeneration has not yet been achieved, and would be a significant step in attaining functional recovery following spinal cord injury.

METHODOLOGY/PRINCIPAL FINDINGS

To investigate this, neuronal cultures were transfected with constructs encoding axon-targeted chondroitinase, non-targeted chondroitinase or GFP, and the effects on neuron outgrowth and sprouting determined on substrates either permissive or inhibitory to neuron regeneration. The mechanisms underlying the observed effects were also explored. Targeting chondroitinase to the neuronal axon markedly enhances its ability to promote neurite outgrowth. The increase in neurite length is associated with an upregulation of β-integrin staining at the axonal cell surface. Staining for phosphofocal adhesion kinase, is also increased, indicating that the β-integrins are in an activated state. Expression of chondroitinase within the neurons also resulted in a decrease in expression of PTEN and RhoA, molecules which present a block to neurite outgrowth, thus identifying two of the pathways by which ChABC promotes neurite outgrowth.

CONCLUSIONS / SIGNIFICANCE

The novel finding that targeting ChABC to the axon significantly enhances its ability to promote neurite extension, suggests that this may be an effective way of promoting long-distance axon regeneration following spinal cord injury. It could also potentially improve its efficacy in the treatment of other pathologies, where it has been shown to promote recovery, such as myocardial infarction, stroke and Parkinson's disease.

Affective Disorders in DSM-5

The DSM-5 Mood Disorders changes recommended by the Mood Disorders Workgroup have been summarized. Each of these changes have been reviewed for soundness of reasons for the change, reports in the literature supporting the change, and a consideration of possible negative consequences of the change by the Scientific Review Committee (SRC) or the Clinical and Public Health Committee (CPHC). While a review of all the literature submitted in support of each of these changes is beyond the scope of this article, general reasons for the changes are discussed. These changes range from the addition or deletion of diagnoses, to changes in criteria and the additions of new specifiers and dimensions. A more mood spectrum view of the range of mood disorders is reflected in the mixed specifier added across unipolar and bipolar disorders. An increased attention to suicide risk assessment is reflected in DSM-5 as well as the addition of a severity of anxiety specifier to draw clinical attention to the importance of these factors.

Mortality from Listeria monocytogenes meningoencephalitis following escalation to alemtuzumab therapy for relapsing-remitting Multiple Sclerosis

We report the case of a patient who died from the rare complication of Listeriosis in the immediate phase following alemtuzumab administration one month after discontinuing dimethyl fumarate (DMF). There is considerable overlap with typical post-infusion symptoms therefore high surveillance and low threshold for empirical or possible prophylactic antibiotic therapy is advocated.

The role of macrophages in the development of biliary injury in a lipopolysaccharide-aggravated hepatic ischaemia-reperfusion model

INTRODUCTION

Endotoxins, in the form of lipopolysaccharides (LPS), are potent inducers of biliary injury. However the mechanism by which injury develops remains unclear. We hypothesized that hepatic macrophages are pivotal in the development of endotoxin-induced biliary injury and that no injury would occur in their absence.

MATERIAL AND METHODS

Clodronate liposomes were used to deplete macrophages from the liver. Forty-eight rats were equally divided across six study groups: sham operation (sham), liposome treatment and sham operation (liposomes+sham), 1mg/kg LPS i.p. (LPS), liposome treatment and LPS administration (liposomes+LPS), hepatic ischaemia-reperfusion injury with LPS administration (IRI+LPS) and liposome treatment followed by IRI+LPS (liposomes+IRI+LPS). Following 6h of reperfusion, blood, bile, and liver tissue was collected for further analysis. Small bile duct injury was assessed, serum liver tests were performed and bile composition was evaluated. The permeability of the blood-biliary barrier (BBB) was assessed using intravenously administered horseradish peroxidase (HRP).

RESULTS

The presence of hepatic macrophages was reduced by 90% in LPS and IRI+LPS groups pre-treated with clodronate liposomes (P<0.001). Severe small bile duct injury was not affected by macrophage depletion, and persisted in the liposomes+IRI+LPS group (50% of animals) and liposomes+LPS group (75% of animals). Likewise, BBB impairment persisted following macrophage depletion. LPS-induced elevation of the chemokine Mcp-1 in bile was not affected by macrophage depletion.

CONCLUSIONS

Depletion of hepatic macrophages did not prevent development of biliary injury following LPS or LPS-enhanced IRI. Cholangiocyte activation rather than macrophage activation may underlie this injury. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

A Comparative Study of Preparation Techniques for Improving the Viability of Nigral Grafts using Vital Stains, in Vitro Cultures, and in Vivo Grafts

The intracerebral transplantation of embryonic dopaminergic nigral neurons, although relatively successful, leads to a fairly low yield of surviving cells. Many factors may influence the viability of dopaminergic grafts and one of these is the preparation of the tissue prior to transplantation. We have investigated the effects of different steps during the preparation and storage of embryonic rat nigral cell suspensions on their subsequent survival at a variety of different time points using a combination of techniques and studies. For studies concerned with the first 24 h we employed vital stains, in the period covering the next 7 days we used in vitro cultures, and in the long term experiment we used in vivo grafts. The results suggest that nigral cell suspensions may remain sufficiently viable for grafting for much longer periods than previously reported. In addition a number of parameters which affect cell survival have been characterised, including the age of the embryonic donor tissue, the use of proteolytic enzymes and the trituration procedure used during the preparation of the suspension. The optimal preparation technique, therefore, uses E13-E14 embryos with the dissected ventral mesencephalon being incubated in purified 0.1% trypsin solutions for 60 min and triturated using a flame polished Pasteur pipette. This may have important implications in improving intracerebral transplantation for Parkinson's disease.

The soft mechanical signature of glial scars in the central nervous system

Injury to the central nervous system (CNS) alters the molecular and cellular composition of neural tissue and leads to glial scarring, which inhibits the regrowth of damaged axons. Mammalian glial scars supposedly form a chemical and mechanical barrier to neuronal regeneration. While tremendous effort has been devoted to identifying molecular characteristics of the scar, very little is known about its mechanical properties. Here we characterize spatiotemporal changes of the elastic stiffness of the injured rat neocortex and spinal cord at 1.5 and three weeks post-injury using atomic force microscopy. In contrast to scars in other mammalian tissues, CNS tissue significantly softens after injury. Expression levels of glial intermediate filaments (GFAP, vimentin) and extracellular matrix components (laminin, collagen IV) correlate with tissue softening. As tissue stiffness is a regulator of neuronal growth, our results may help to understand why mammalian neurons do not regenerate after injury.

Trafficking and processing of bacterial proteins by mammalian cells: Insights from chondroitinase ABC

BACKGROUND

There is very little reported in the literature about the relationship between modifications of bacterial proteins and their secretion by mammalian cells that synthesize them. We previously reported that the secretion of the bacterial enzyme Chondroitinase ABC by mammalian cells requires the strategic removal of at least three N-glycosylation sites. The aim of this study was to determine if it is possible to enhance the efficacy of the enzyme as a treatment for spinal cord injury by increasing the quantity of enzyme secreted or by altering its cellular location.

METHODOLOGY/PRINCIPAL FINDINGS

To determine if the efficiency of enzyme secretion could be further increased, cells were transfected with constructs encoding the gene for chondroitinase ABC modified for expression by mammalian cells; these contained additional modifications of strategic N-glycosylation sites or alternative signal sequences to direct secretion of the enzyme from the cells. We show that while removal of certain specific N-glycosylation sites enhances enzyme secretion, N-glycosylation of at least two other sites, N-856 and N-773, is essential for both production and secretion of active enzyme. Furthermore, we find that the signal sequence directing secretion also influences the quantity of enzyme secreted, and that this varies widely amongst the cell types tested. Last, we find that replacing the 3'UTR on the cDNA encoding Chondroitinase ABC with that of β-actin is sufficient to target the enzyme to the neuronal growth cone when transfected into neurons. This also enhances neurite outgrowth on an inhibitory substrate.

CONCLUSION/SIGNIFICANCE

Some intracellular trafficking pathways are adversely affected by cryptic signals present in the bacterial gene sequence, whilst unexpectedly others are required for efficient secretion of the enzyme. Furthermore, targeting chondroitinase to the neuronal growth cone promotes its ability to increase neurite outgrowth on an inhibitory substrate. These findings are timely in view of the renewed prospects for gene therapy, and of direct relevance to strategies aimed at expressing foreign proteins in mammalian cells, in particular bacterial proteins.

Integrin signalling and traffic during axon growth and regeneration

Adult corticospinal tract axons do not regenerate because they have low intrinsic growth ability, and are exposed to inhibitory molecules after injury. PNS axons have a better regenerative capacity, mediated in part by integrins (extracellular matrix receptors). These are subject to complex regulation by signalling and trafficking. Recent studies have found that integrin mediated axon growth relies on signalling via focal adhesion molecules, and that integrins are inactivated by inhibitory molecules in the CNS. Forced activation of integrins can overcome inhibition and increase axon regeneration, however integrins are not transported into some CNS axons. Studies of PNS integrin traffic have identified molecules that can be manipulated to increase axonal integrin expression, suggesting strategies for repairing the injured spinal cord.

Academic potential and cognitive functioning of long-term survivors after childhood liver transplantation

This cross-sectional study assessed intellect, cognition, academic function, behaviour, and emotional health of long-term survivors after childhood liver transplantation. Eligible children were >5 yr post-transplant, still attending school, and resident in Queensland. Hearing and neurocognitive testing were performed on 13 transplanted children and six siblings including two twin pairs where one was transplanted and the other not. Median age at testing was 13.08 (range 6.52-16.99) yr; time elapsed after transplant 10.89 (range 5.16-16.37) yr; and age at transplant 1.15 (range 0.38-10.00) yr. Mean full-scale IQ was 97 (81-117) for transplanted children and 105 (87-130) for siblings. No difficulties were identified in intellect, cognition, academic function, and memory and learning in transplanted children or their siblings, although both groups had reduced mathematical ability compared with normal. Transplanted patients had difficulties in executive functioning, particularly in self-regulation, planning and organization, problem-solving, and visual scanning. Thirty-one percent (4/13) of transplanted patients, and no siblings, scored in the clinical range for ADHD. Emotional difficulties were noted in transplanted patients but were not different from their siblings. Long-term liver transplant survivors exhibit difficulties in executive function and are more likely to have ADHD despite relatively intact intellect and cognition.

Subsyndromal depression in the United States: prevalence, course, and risk for incident psychiatric outcomes

BACKGROUND

Subsyndromal depression (SD) may increase risk for incident major depressive and other disorders, as well as suicidality. However, little is known about the prevalence, course, and correlates of SD in the US general adult population. Method Structured diagnostic interviews were conducted to assess DSM-IV Axis I and II disorders in a nationally representative sample of 34 653 US adults who were interviewed at two time-points 3 years apart.

RESULTS

A total of 11.6% of US adults met study criteria for lifetime SD at Wave 1. The majority (9.3%) had <5 total symptoms required for a diagnosis of major depression; the remainder (2.3%) reported ⩾5 symptoms required for a diagnosis of major depression, but denied clinically significant distress or functional impairment. SD at Wave 1 was associated with increased likelihood of developing incident major depression [odds ratios (ORs) 1.72-2.05], as well as dysthymia, social phobia, and generalized anxiety disorder (GAD) at Wave 2 (ORs 1.41-2.92). Among respondents with SD at Wave 1, Cluster A and B personality disorders, and worse mental health status were associated with increased likelihood of developing incident major depression at Wave 2.

CONCLUSIONS

SD is prevalent in the US population, and associated with elevated rates of Axis I and II psychopathology, increased psychosocial disability, and risk for incident major depression, dysthymia, social phobia, and GAD. These results underscore the importance of a dimensional conceptualization of depressive symptoms, as SD may serve as an early prognostic indicator of incident major depression and related disorders, and could help identify individuals who may benefit from preventive interventions.

The perineuronal net and the control of CNS plasticity

Perineuronal nets (PNNs) are reticular structures that surround the cell body of many neurones, and extend along their dendrites. They are considered to be a specialized extracellular matrix in the central nervous system (CNS). PNN formation is first detected relatively late in development, as the mature synaptic circuitry of the CNS is established and stabilized. Its unique distribution in different CNS regions, the timing of its establishment, and the changes it undergoes after injury all point toward diverse and important functions that it may be performing. The involvement of PNNs in neuronal plasticity has been extensively studied over recent years, with developmental, behavioural, and functional correlations. In this review, we will first briefly detail the structure and organization of PNNs, before focusing our discussion on their unique roles in neuronal development and plasticity. The PNN is an important regulator of CNS plasticity, both during development and into adulthood. Production of critical PNN components is often triggered by appropriate sensory experiences during early postnatal development. PNN deposition around neurones helps to stabilize the established neuronal connections, and to restrict the plastic changes due to future experiences within the CNS. Disruption of PNNs can reactivate plasticity in many CNSs, allowing activity-dependent changes to once again modify neuronal connections. The mechanisms through which PNNs restrict CNS plasticity remain unclear, although recent advances promise to shed additional light on this important subject.

Effect of hospital and surgeon volume on patient outcomes following treatment of abdominal aortic aneurysms: a systematic review

OBJECTIVES

This systematic review assessed the efficacy of centralisation for the treatment of unruptured and ruptured abdominal aortic aneurysms. Patient outcomes achieved by low and high volume hospitals/surgeons, including morbidity, mortality and length of hospital stay, were used as proxy measures of efficacy.

DESIGN

Systematic review was designed to identify, assess and report on peer-reviewed articles reporting outcomes from unruptured and ruptured abdominal aortic aneurysms. No language restriction was placed on the databases searched.

MATERIALS

Only peer-reviewed journals articles were included.

METHODS

To ensure the contemporary nature of this review, only studies published between January 1997 and June 2007 were sought. Studies were included if they reported on at least one volume type and patient outcome.

RESULTS

Twenty two studies were included in this review. In the majority of group assessments, the number of studies reporting statistical significance was similar to the number of studies reporting no statistical significance.

CONCLUSION

The paucity of studies reporting statistically significant results demonstrates that although this evidence exists, its potential to be overstated must also be taken into account when drawing conclusions as to its efficacy for twenty first century healthcare systems.

Can pharmacotherapists be too supportive? A process study of active medication and placebo in the treatment of depression

BACKGROUND

This study examined therapist-patient interactions during clinical management with antidepressant medication and pill-placebo.

METHOD

The sample consisted of 80 patients on active medication and 40 patients in a pill-placebo condition from a randomized controlled trial for moderate to severe depression. Pharmacotherapist-patient interactions were characterized using observer ratings of the therapeutic alliance, pharmacotherapist-offered facilitative conditions, pharmacotherapist adherence to clinical management treatment guidelines and pharmacotherapist competence. Patients, therapists and raters were blind to treatment condition and outcome.

RESULTS

Provision of greater non-specific support (facilitative conditions) in early sessions predicted less subsequent improvement in depressive symptoms for patients receiving pill-placebo but not those receiving active medications, for which none of the process ratings predicted subsequent change. Early symptom change predicted later alliance and adherence in both conditions and therapist competence in the active condition.

CONCLUSIONS

Higher levels of support in early sessions predict poorer subsequent response among placebo patients. It remains unclear whether patients who are likely to be refractory elicit greater non-specific support or whether the provision of such support has a deleterious effect in unmedicated patients. Differences in treatment process variables between conditions late in treatment are likely to be largely a consequence of symptom relief produced by active medications.

Mechanical difference between white and gray matter in the rat cerebellum measured by scanning force microscopy

The mechanical properties of tissues are increasingly recognized as important cues for cell physiology and pathology. Nevertheless, there is a sparsity of quantitative, high-resolution data on mechanical properties of specific tissues. This is especially true for the central nervous system (CNS), which poses particular difficulties in terms of preparation and measurement. We have prepared thin slices of brain tissue suited for indentation measurements on the micrometer scale in a near-native state. Using a scanning force microscope with a spherical indenter of radius ∼20μm we have mapped the effective elastic modulus of rat cerebellum with a spatial resolution of 100μm. We found significant differences between white and gray matter, having effective elastic moduli of K=294±74 and 454±53Pa, respectively, at 3μm indentation depth (n(g)=245, n(w)=150 in four animals, p<0.05; errors are SD). In contrast to many other measurements on larger length scales, our results were constant for indentation depths of 2-4μm indicating a regime of linear effective elastic modulus. These data, assessed with a direct mechanical measurement, provide reliable high-resolution information and serve as a quantitative basis for further neuromechanical investigations on the mechanical properties of developing, adult and damaged CNS tissue.

Mechanosensitivity of astrocytes on optimized polyacrylamide gels analyzed by quantitative morphometry

Cells are able to detect and respond to mechanical cues from their environment. Previous studies have investigated this mechanosensitivity on various cell types, including neural cells such as astrocytes. In this study, we have carefully optimized polyacrylamide gels, commonly used as compliant growth substrates, considering their homogeneity in surface topography, mechanical properties, and coating density, and identified several potential pitfalls for the purpose of mechanosensitivity studies. The resulting astrocyte response to growth on substrates with shear storage moduli of G' = 100 Pa and G' = 10 kPa was then evaluated as a function of coating density of poly-D-lysine using quantitative morphometric analysis. Astrocytes cultured on stiff substrates showed significantly increased perimeter, area, diameter, elongation, number of extremities and overall complexity if compared to those cultured on compliant substrates. A statistically significant difference in the overall morphological score was confirmed with an artificial intelligence-based shape analysis. The dependence of the cells' morphology on PDL coating density seemed to be weak compared to the effect of the substrate stiffness and was slightly biphasic, with a maximum at 10-100 µg ml(-1) PDL concentration. Our finding suggests that the compliance of the surrounding tissue in vivo may influence astrocyte morphology and behavior.

Assessment of the biocompatibility of photosensitive polyimide for implantable medical device use

Polyimides have been widely used for biosensor encapsulation and more recently as substrates for neural implants. They have excellent thermal stability, high chemical resistance, and can be prepared as thin, flexible films. Photosensitive polyimides present similar physical properties to polyimides, and have the advantage that they can be photo-lithographically patterned. However, to date little data on their biocompatibility has been reported. Two commercially available polyimides (PI) and one photo-sensitive polyimide (PSPI) were evaluated in vitro using the ISO 10993 standard on biocompatibility. The materials were Dupont Kapton foil HN, HD Microsystem PI2611, and Fujifilm Durimide 7020 (PSPI). PI2611 and Durimide 7020 were spin-coated on silicon wafers, cured at temperatures ranging from 150 to 450 degrees C, and sterilized by autoclave. All materials were evaluated using a scanning electron microscope pre- and postcell culture. Cell viability was determined by an MTS assay. Their mechanical properties and stability during cell culture as a function of time and environment were investigated by nanoindentation. The MTS results show that PSPI is noncytotoxic compared with the negative control of polyethylene and the conventional PIs tested. Fibroblast adhesion, morphology, and spreading were good and better on the PSPI substrate than on the PI2611. Schwann cell appearance was similar on each of the PIs and the PSPI tested. The results suggest that PSPIs may have potential use for biological microsystem and neuroprosthetic applications.

Long micro-channel electrode arrays: a novel type of regenerative peripheral nerve interface

We have demonstrated that micro-channel electrode arrays with 100 microm x 100 microm cross-section channels support axon regeneration well, and that micro-channels of similar calibre and up to 5 mm long can support axon regeneration and vascularisation. They may be microfabricated using silicon, silicone, or polyimide and thin metal films to form 3-D bundles of long micro-channels. Arrays of "mini-nerves," i.e., miniature nerve fascicles with their own blood vessels, successfully grew through implants 0.5-5 mm long. Furthermore, guiding the regenerating nerve fibres into the small insulating channels allows for a significant increase of the extracellular (recordable) amplitude of action potentials, which promises considerable improvement for in vivo electrophysiology.

An efficient method for derivation and propagation of glioblastoma cell lines that conserves the molecular profile of their original tumours

A growing body of evidence suggests that glioma stem-like cells are more representative of their parent tumours when cultured under defined serum-free conditions with the mitogens epidermal growth factor (EGF) and fibroblast growth factor (FGF). However, culturing these cells as free-floating spheroids can result in difficulty in efficiently deriving and propagating cell lines. We have combined neurosphere and monolayer culture techniques to improve the efficiency with which cells can be derived from clinical tumour samples under defined serum-free conditions. We have applied our protocol to consecutive samples of glioblastoma to show that they can form experimental tumours that recapitulate many of the histological features of the parent tumour. We go on to show that the tumour initiating cells also retain the cytogenetic abnormalities of the parent tumour. Finally we examined the cell lines for expression of markers associated with neural stem cells. Our results confirm the expression of transcription factors associated with neural patterning and specification including Sox2, Olig2, Pax6 and Nkx2.2. We went on to establish that these factors were also expressed in the parent tumour indicating that their expression was not a function of our culture conditions. The Cambridge Protocol is an efficient method of deriving stem-like tumour initiating cells from glioblastoma. Improving the efficiency of derivation will facilitate the improvement of in vitro and in vivo model systems to study disease mechanisms, screen drugs and develop novel therapeutic approaches in the future.

Molecular control of brain plasticity and repair

Recovery of function after damage to the CNS is limited due to the absence of axon regeneration and relatively low levels of plasticity. Plasticity in the CNS can be reactivated in the adult CNS by treatment with chondroitinase ABC, which removes glycosaminoglycan (GAG) chains from chondroitin sulfate proteoglycans (CSPGs). Plasticity in the adult CNS is restricted by perineuronal nets (PNNs) around many neuronal cell bodies and dendrites, which appear at the closure of critical periods and contain several inhibitory CSPGs. Formation of these structures and the turning off of plasticity is triggered by impulse activity in neurons. Expression of a link protein by neurons is the event that triggers the formation of PNNs. Treatment with chondroitinase removes PNNs and other inhibitory influences in the damaged spinal cord and promotes sprouting of new connections. However, promoting plasticity by itself does not necessarily bring back useful behavior; this only happens when useful connections are stabilized and inappropriate connections removed, driven by behavior. Thus after rodent spinal cord injury, combining a daily rehabilitation treatment for skilled paw function with chondroitinase produces much greater recovery than either treatment alone. The rehabilitation must be specific for the behavior that is to be enhanced because non-specific rehabilitation improves locomotor behavior but not skilled paw function. Plasticity-enhancing treatments may therefore open up a window of opportunity for successful rehabilitation.

Repair in the central nervous system

The subject of central nervous system damage includes a wide variety of problems, from the slow selective 'picking off' of characteristic sub-populations of neurons typical of neurodegenerative diseases, to the wholesale destruction of areas of brain and spinal cord seen in traumatic injury and stroke. Experimental repair strategies are diverse and the type of pathology dictates which approach will be appropriate. Damage may be to grey matter (loss of neurons), white matter (cutting of axons, leaving neurons otherwise intact, at least initially) or both. This review will consider four possible forms of treatment for repair of the human central nervous system.

Combinatorial ShcA docking interactions support diversity in tissue morphogenesis

Changes in protein-protein interactions may allow polypeptides to perform unexpected regulatory functions. Mammalian ShcA docking proteins have amino-terminal phosphotyrosine (pTyr) binding (PTB) and carboxyl-terminal Src homology 2 (SH2) domains, which recognize specific pTyr sites on activated receptors, and a central region with two phosphorylated tyrosine-X-asparagine (pYXN) motifs (where X represents any amino acid) that each bind the growth factor receptor-bound protein 2 (Grb2) adaptor. Phylogenetic analysis indicates that ShcA may signal through both pYXN-dependent and -independent pathways. We show that, in mice, cardiomyocyte-expressed ShcA directs mid-gestational heart development by a PTB-dependent mechanism that does not require the pYXN motifs. In contrast, the pYXN motifs are required with PTB and SH2 domains in the same ShcA molecule for the formation of muscle spindles, skeletal muscle sensory organs that regulate motor behavior. Thus, combinatorial differences in ShcA docking interactions may yield multiple signaling mechanisms to support diversity in tissue morphogenesis.

Cancer is overtaking cardiovascular disease as the main driver of socioeconomic inequalities in mortality: New Zealand (1981-99)

BACKGROUND

Relative socioeconomic disparities in cardiovascular mortality have increased in New Zealand, as in many Western countries in Northern Europe, the US and Australia during the late 20th century. However, substantial declines in cardiovascular mortality mean that its absolute contribution to overall mortality has decreased.

RESEARCH QUESTIONS

How did the absolute contribution of major causes of death to socioeconomic inequalities in New Zealand change during the 1980s and 90s?

METHODS

Linked census-mortality cohorts were used to calculate the contribution of different causes of death to inequalities in mortality, measured with the slope index of inequality, by household income.

RESULTS

Between 1981-4 and 1996-9, the contribution of cardiovascular disease (CVD) to total inequality declined from 55% to 28% among women, whereas at the same time the contribution of cancers increased from 14% to 37%. Among men, the contribution of CVD to total inequality peaked at 47% in 1986-9, then declined to 38% in 1996-9. The contribution of cancer increased from 19% to 26% in men.

CONCLUSION

CVD mortality has declined at all income levels and so too has the contribution of CVD to mortality inequalities. Concurrently, the contribution of cancer to inequalities in mortality by income has increased and, in women at least, is now greater than the contribution of CVD. It is hypothesised that a similar crossover is occurring in other populations where CVD mortality has declined, although socioeconomic differences in the distribution and effect of the obesity epidemic for CVD may ensure its continuing importance. Prevention efforts aimed at reducing socioeconomic inequalities in mortality will need to increasingly focus on socioeconomic inequalities in cancer mortality.

Effect of nelfinavir on insulin metabolism, proteasome activity and protein degradation in HepG2 cells

HIV-1 protease inhibitors have revolutionized the treatment of HIV infection, but their use has been associated with lipodystrophy and insulin resistance. One suggestion for this has been the inhibition of insulin-degrading enzyme (IDE). We have previously demonstrated that insulin, through IDE, can inhibit the proteasome, thus decreasing cytosolic protein degradation. We examined whether the protease inhibitor nelfinavir inhibited IDE and its effect on protein degradation both in vitro and in whole cells. 125I-Insulin degradation was measured by trichloroacetic acid precipitation. Proteasome activities were measured using fluorogenic peptide substrates. Cellular protein degradation was measured by prelabelling cells with 3H-leucine and determining the release of TCA-soluble radioactivity. Nelfinavir inhibited IDE in a concentration-dependent manner with 50% inhibition at the maximal concentration tested, 100 microm. Similarly, the chymotrypsin-like and trypsin-like activities of the proteasome were decreased with an IC50 of approximately 3 microm. The ability of insulin to inhibit the proteasome was abrogated by nelfinavir. Treatment of HepG2 cells with 50 microm nelfinavir decreased 125I-insulin degradation and increased cell-associated radioactivity. Insulin alone maximally decreased protein degradation by 15%. Addition of 50 microm nelfinavir inhibited cellular protein degradation by 14% and blunted the effect of insulin. These data show that nelfinavir inhibits IDE, decreases insulin's ability to inhibit protein degradation via the proteasome and provides another possible mechanism for the insulin resistance seen in protease inhibitor-treated HIV patients.

Spinal Cord Regeneration

Repairing the damaged spinal cord has for a long time eluded neuroscientists. Few other achievements in neuroscience would have such a tremendous impact amongst the medical profession and the public. Despite numerous efforts, no patient has yet benefited from a regeneration therapy. Recent advances in the basic science of axon regeneration have opened new doors of hope towards prevention and cure of the devastating effects of spinal cord injury (SCI), and treatments that could encourage a partial repair of spinal injury are imminent. This article reviews the impact of SCI on patients, the current reparative strategies being explored and their potential clinical applications.

CCR5-Delta32 mutation is strongly associated with primary sclerosing cholangitis

CCR5 plays a key role in the distribution of CD45RO+ T cells and contributes to generation of a T helper 1 immune response. CCR5-Delta32 is a 32-bp deletion associated with significant reduction in cell surface expression of the receptor. We investigated the role of CCR5-Delta32 on susceptibility to ulcerative colitis (UC), Crohn's disease (CD) and primary sclerosing cholangitis (PSC). Genotype and allelic association analyses were performed in 162 patients with UC, 131 with CD, 71 with PSC and 419 matched controls. There was a significant difference in CCR5 genotype (OR 2.27, P=0.003) between patients with sclerosing cholangitis and controls. Similarly, CCR5-Delta32 allele frequency was significantly higher in sclerosing cholangitis (17.6%) compared to controls (9.9%, OR 2.47, P=0.007) and inflammatory bowel disease patients without sclerosing cholangitis (11.3%, OR 1.9, P=0.027). There were no significant differences in CCR5 genotype or allele frequency between those with either UC or CD and controls. Genotypes with the CCR5-Delta32 variant were increased in patients with severe liver disease defined by portal hypertension and/or transplantation (45%) compared to those with mild liver disease (21%, OR 3.17, P=0.03). The CCR5-Delta32 mutation may influence disease susceptibility and severity in patients with PSC.