GABA transport and neuroinflammation are coupled in multiple sclerosis: regulation of the GABA transporter-2 by ganaxolone

Interactions between neurotransmitters and the immune system represent new prospects for understanding neuroinflammation and associated neurological disease. GABA is the chief inhibitory neurotransmitter but its actions on immune pathways in the brain are unclear. In the present study, we investigated GABAergic transport in conjunction with neuroinflammation in models of multiple sclerosis (MS). Protein and mRNA levels of γ-amino butyric acid transporter 2 (GAT-2) were examined in cerebral white matter from MS and control (Non-MS) patients, in cultured human macrophages, microglia and astrocytes, and in spinal cords from mice with and without experimental autoimmune encephalomyelitis (EAE) using western blotting, immunocytochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). GABA levels were measured by HPLC. The GAT-2's expression was increased in MS patients' (n=6) white matter, particularly in macrophage lineage cells, compared to Non-MS patients (n=6) (p<0.05). Interferon-γ (IFN-γ) stimulation of human macrophage lineage cells induced GAT-2 expression and reduced extracellular GABA levels (p<0.05) but soluble GABA treatment suppressed HLA-DRα, GAT-2 and XBP-1/s expression in stimulated macrophage lineage cells (p<0.05). Similarly, the synthetic allopregnanolone analog, ganaxolone (GNX), repressed GAT-2, JAK-1 and STAT-1 expression in activated macrophage lineage cells (p<0.05). In vivo GNX treatment reduced Gat-2, Cd3ε, MhcII, and Xbp-1/s expression in spinal cords following EAE induction (p<0.05), which was correlated with improved neurobehavioral outcomes and reduced neuroinflammation, demyelination and axonal injury. These findings highlight altered GABAergic transport through GAT-2 induction during neuroinflammation. GABA transport and neuroinflammation are closely coupled but regulated by GNX, pointing to GABAergic pathways as therapeutic targets in neuroinflammatory diseases.

Prenatal and childhood antecedents of suicide: 50-year follow-up of the 1958 British Birth Cohort study

BACKGROUND

We aimed to elucidate early antecedents of suicide including possible mediation by early child development.

METHOD

Using the 1958 birth cohort, based on British births in March 1958, individuals were followed up to adulthood. We used data collected at birth and at age 7 years from various informants. Suicides occurring up to 31 May 2009 were identified from linked national death certificates. Multivariable Cox proportional hazard models were used to investigate risk factors.

RESULTS

Altogether 12399 participants (n = 44 suicides) had complete data. The strongest prenatal risk factors for suicide were: birth order, with risk increasing in later-born children [p trend = 0.063, adjusted hazard ratio (HR)], e.g. for fourth- or later-born children [HR = 2.27, 95% confidence interval (CI) 0.90-5.75]; young maternal age (HR = 1.18, 95% CI 0.34-4.13 for ⩽19 years and HR = 0.41, 95% CI 0.19-0.91 for >29 years, p trend = 0.034); and low (<2.5 kg) birth weight (HR = 2.48, 95% CI 1.03-5.95). The strongest risk factors at 7 years were externalizing problems in males (HR = 2.96, 95% CI 1.03-8.47, p trend = 0.050) and number of emotional adversities (i.e. parental death, neglected appearance, domestic tension, institutional care, contact with social services, parental divorce/separation and bullying) for which there was a graded association with risk of suicide (p trend = 0.033); the highest (HR = 3.12, 95% CI 1.01-9.62) was for persons with three or more adversities.

CONCLUSIONS

Risk factors recorded at birth and at 7 years may influence an individual's long-term risk of suicide, suggesting that trajectories leading to suicide have roots in early life. Some factors are amenable to intervention, but for others a better understanding of causal mechanisms may provide new insights for intervention to reduce suicide risk.

Interaction between vitamin D receptor gene polymorphisms and 25-hydroxyvitamin D concentrations on metabolic and cardiovascular disease outcomes

AIM

25-hydroxyvitamin D (25OHD) concentrations have been shown to be associated with major clinical outcomes, with a suggestion that individual risk may vary according to common genetic differences in the vitamin D receptor (VDR) gene. Hence, we tested for the interactions between two previously studied VDR polymorphisms and 25OHD on metabolic and cardiovascular disease-related outcomes in a large population-based study.

METHODS

Interactions between two previously studied VDR polymorphisms (rs7968585 and rs2239179) and 25OHD concentrations on metabolic and cardiovascular disease-related outcomes such as obesity- (body mass index, waist circumference, waist-hip ratio (WHR)), cardiovascular- (systolic and diastolic blood pressure), lipid- (high- and low-density lipoprotein, triglycerides, total cholesterol), inflammatory- (C-reactive protein, fibrinogen, insulin growth factor-1, tissue plasminogen activator) and diabetes- (glycated haemoglobin) related markers were examined in the 1958 British Birth cohort (n up to 5160). Interactions between each SNP and 25OHD concentrations were assessed using linear regression and the likelihood ratio test.

RESULTS

After Bonferroni correction, none of the interactions reached statistical significance except for the interaction between the VDR SNP rs2239179 and 25OHD concentrations on waist-hip ratio (WHR) (P=0.03). For every 1nmol/L higher 25OHD concentrations, the association with WHR was stronger among those with two major alleles (-4.0%, P=6.26e(-24)) compared to those with either one or no major alleles (-2.3%, P≤8.201e(-07), for both) of the VDR SNP rs2239179.

CONCLUSION

We found no evidence for VDR polymorphisms acting as major modifiers of the association between 25OHD concentrations and cardio-metabolic risk. Interaction between VDR SNP rs2239179 and 25OHD on WHR warrants further confirmation.

Metabolomic profiling in multiple sclerosis: insights into biomarkers and pathogenesis

Metabolomics enables the provision of sensitive bio-markers of disease. We performed 800 MHz 1H-nuclear magnetic resonance (NMR) spectroscopic analyses of cerebrospinal fluid (CSF) specimens to identify biomarkers of multiple sclerosis (MS), yielding reproducible detection of 15 metabolites from MS ( n=15) and non-MS ( n=17) patients. Mean levels of choline, myo-inositol and threonate were increased, whereas 3-hydroxybutyrate, citrate, phenylalanine, 2-hydroxyisovalerate and mannose were decreased in MS-derived CSF ( p<0.05), suggesting alterations to energy and phospholipid metabolism. Multivariate hierarchal cluster analysis indicated a high correlation within the metabolite profiles, significantly clustering samples into the two clinical groups, which was corroborated using principal components analysis. CSF metabolomics have the capacity to yield quantitative biomarkers and insights into the pathogenesis of MS.

Humanised xenograft models of bone metastasis revisited: novel insights into species-specific mechanisms of cancer cell osteotropism

The determinants and key mechanisms of cancer cell osteotropism have not been identified, mainly due to the lack of reproducible animal models representing the biological, genetic and clinical features seen in humans. An ideal model should be capable of recapitulating as many steps of the metastatic cascade as possible, thus facilitating the development of prognostic markers and novel therapeutic strategies. Most animal models of bone metastasis still have to be derived experimentally as most syngeneic and transgeneic approaches do not provide a robust skeletal phenotype and do not recapitulate the biological processes seen in humans. The xenotransplantation of human cancer cells or tumour tissue into immunocompromised murine hosts provides the possibility to simulate early and late stages of the human disease. Human bone or tissue-engineered human bone constructs can be implanted into the animal to recapitulate more subtle, species-specific aspects of the mutual interaction between human cancer cells and the human bone microenvironment. Moreover, the replication of the entire "organ" bone makes it possible to analyse the interaction between cancer cells and the haematopoietic niche and to confer at least a partial human immunity to the murine host. This process of humanisation is facilitated by novel immunocompromised mouse strains that allow a high engraftment rate of human cells or tissue. These humanised xenograft models provide an important research tool to study human biological processes of bone metastasis.

Investigation of the migration of triclabendazole residues to milk products manufactured from bovine milk, and stability therein, following lactating cow treatment

Triclabendazole (TCB) is a flukicide used in the treatment of liver fluke in cattle; however, its use is currently prohibited in lactating dairy cows. In this study, following administration of 10% Fasinex (triclabendazole, Novartis Animal Health UK Ltd., Camberley, UK) the milk of 6 animals was used to manufacture dairy products, to ascertain if TCB residues in milk migrate into dairy products. The detection limit of the ultra-high-performance liquid chromatography-tandem mass spectrometry method used was 0.67 μg/kg. The highest concentrations of TCB residue measured, within the individual cow milk yield, was 1,529 ± 244 µg/kg (n=6), on d 2 posttreatment. Days 2 and 23 posttreatment represented high and low residue concentrations, respectively. At each of these 2 time points, the milk was pooled into 2 independent aliquots and refrigerated. Milk products, including cheese, butter, and skim milk powder were manufactured using pasteurized and unpasteurized milk from each aliquot. The results for high residue milks demonstrated that TCB residues concentrated in the cheese by a factor of 5 (5,372 vs. 918 µg/kg for cheese vs. milk) compared with the starting milk. Residue concentrations are the sum of TCB and its metabolites, expressed as keto-TCB. Residues were concentrated in the butter by a factor of 9 (9,177 vs. 1,082 μg/kg for butter vs. milk) compared with the starting milk. For milk, which was separated to skim milk and cream fractions, the residues were concentrated in the cream. Once skim milk powder was manufactured from the skim milk fraction, the residue in powder was concentrated 15-fold compared with the starting skim milk (7,252 vs. 423 µg/kg for powder vs. skim milk), despite the high temperature (185 °C) required during powder manufacture. For products manufactured from milk with low residue concentrations at d 23 posttreatment, TCB residues were detected in butter, cheese, and skim milk powder, even though there was no detectable residue in the milk used to manufacture these products. Triclabendazole residues were concentrated in some milk products (despite manufacturing treatments), exceeding residue levels in the starting milk and, depending on the storage conditions, may be relatively stable over time.

Nerve growth factor acts through the TrkA receptor to protect sensory neurons from the damaging effects of the HIV-1 viral protein, Vpr

Distal sensory polyneuropathy (DSP) with associated neuropathic pain is the most common neurological disorder affecting patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Viral protein R (Vpr) is a neurotoxic protein encoded by HIV-1 and secreted by infected macrophages. Vpr reduces neuronal viability, increases cytosolic calcium and membrane excitability of cultured dorsal root ganglion (DRG) sensory neurons, and is associated with mechanical allodynia in vivo. A clinical trial with HIV/AIDS patients demonstrated that nerve growth factor (NGF) reduced the severity of DSP-associated neuropathic pain, a problem linked to damage to small diameter, potentially NGF-responsive fibers. Herein, the actions of NGF were investigated in our Vpr model of DSP and we demonstrated that NGF significantly protected sensory neurons from the effects of Vpr. Footpads of immunodeficient Vpr transgenic (vpr/RAG1(-/-)) mice displayed allodynia (p<0.05), diminished epidermalinnervation (p<0.01) and reduced NGF mRNA expression (p<0.001) compared to immunodeficient (wildtype/RAG1(-/-)) littermate control mice. Compartmented cultures confirmed recombinant Vpr exposure to the DRG neuronal perikarya decreased distal neurite extension (p<0.01), whereas NGF exposure at these distal axons protected the DRG neurons from the Vpr-induced effect on their cell bodies. NGF prevented Vpr-induced attenuation of the phosphorylated glycogen synthase-3 axon extension pathway and tropomyosin-related kinase A (TrkA) receptor expression in DRG neurons (p<0.05) and it directly counteracted the cytosolic calcium burst caused by Vpr exposure to DRG neurons (p<0.01). TrkA receptor agonist indicated that NGFacted through the TrkA receptor to block the Vpr-mediated decrease in axon outgrowth in neonatal and adult rat and fetal human DRG neurons (p<0.05). Similarly, inhibiting the lower affinity NGF receptor, p75, blocked Vpr's effect on DRG neurons. Overall, NGF/TrkA signaling or p75 receptor inhibition protects somatic sensory neurons exposed to Vpr, thus laying the groundwork for potential therapeutic options for HIV/AIDS patients suffering from DSP.

An evidence-based assessment of primary care needs in an economically deprived urban community

BACKGROUND

As healthcare and longevity improve and fertility rates decline, we see a demographic shift towards a predominantly elderly population. Because ageing brings its own physiological changes and complications, the need arises for practical and feasible approaches in providing the healthcare required by this population. With government strategy promoting enhanced community-based healthcare, the development of primary care infrastructure should reflect population needs.

AIMS

To describe the profile of older patients attending a general practice in an underprivileged urban setting, specifically initial medical presentation, referrals for secondary care, and the medicines prescribed to them. To thereby enhance our understanding of the primary care requirements of elderly people in this setting.

METHODS

The anonymised records of an older patient cohort (n=427, age>55 years) that presented to a General Practice over a 12-month period were retrospectively analysed to determine the nature of the clinical encounters, subsequent referral patterns and drugs prescribed.

RESULTS

There were 3,448 discrete clinical encounters (mean=8.0 per patient), predominantly for respiratory conditions, leading to 401 issued scripts and to 216 patients being referred for secondary care. Women were referred more often than men. There was a notable need for specialised dietary advice and drug prescribing was often complex.

CONCLUSION

This study provides evidence of primary care needs in an economically deprived area of an Irish city highlighting the complexity of associated prescribing and secondary care referrals in this setting.

Morning salivary cortisol and cognitive function in mid-life: evidence from a population-based birth cohort

BACKGROUND

The hormone 'cortisol' has been associated with cognitive deficits in older ages, and also with childhood cognition. The extent to which the associations of cortisol with cognitive deficits in later life reflect associations with childhood cognition ability is unclear. This study aimed to assess associations between adult cortisol levels and subsequent cognitive functions, while considering childhood cognition and other lifetime covariates.

METHOD

Data are from the 1958 British Birth Cohort. Two morning salivary cortisol samples were obtained at 45 years: 45 min after waking (t1) and 3 h later (t2). Standardized tests assessing immediate and delayed verbal memory, verbal fluency and speed of processing were administered at 50 years. Information on cortisol, cognitive outcomes and covariates [e.g., birthweight, lifetime socio-economic position (SEP), education, smoking and drinking habits, body mass index (BMI), menopausal status, and depression/anxiety] was obtained for 4655 participants.

RESULTS

Worse immediate and delayed verbal memory and verbal fluency at 50 years were predicted by elevated t2 cortisol at 45 years. For instance, for 1 standard deviation (s.d.) increase in t2 cortisol, individuals scored -0.05 s.d. lower on verbal memory and fluency tests. Childhood cognition explained about 30% of these associations, but associations with adult cognition remained.

CONCLUSIONS

This study suggests that higher cortisol levels in late morning at 45 years are associated with poorer verbal memory and fluency at 50 years, with a contribution from childhood cognition to these associations.

Is there a requirement for axillary lymph node dissection following identification of micro-metastasis or isolated tumour cells at sentinel node biopsy for breast cancer?

INTRODUCTION

Recent decades have seen a significant shift towards conservative management of the axilla. Increasingly, immunohistochemical analysis of sentinel nodes leads to the detection of small tumour deposits, the significance of which remains uncertain. The aims of this study are to examine patients whose sentinel lymph nodes are positive for macro-metastasis, micro-metastasis or isolated tumour cells (ITCs) and to determine the rate of further nodal disease after axillary lymph node dissection (ALND).

METHODS

A retrospective analysis of all patients undergoing a sentinel lymph node biopsy (SLNB) between January 2007 and December 2010 in a tertiary referral breast unit was performed. Patients who underwent an axillary lymph node dissection for macro-metastasis, micro-metastasis or ITCs were identified. Demographics, histological data and the rate of further axillary disease were examined.

RESULTS

In total, 664 breast cancer patients attended the symptomatic breast unit during the study period, 360 of whom underwent a SLNB. Seventy patients had a SLNB positive for macro-metastasis. All of these patients underwent ALND. A positive SLNB with either micro-metastasis or ITCs was identified in 58 patients. Only 41 of the 58 patients went on to have an ALND, due primarily to variations in surgeons' preferences. Nineteen patients with micro-metastasis underwent an ALND. Four patients had further axillary disease (21%). Twenty-two patients had ITCs identified, of whom only one had further disease (4.5%). No statistically significant difference was found between the two groups in terms of tumour size, grade, lymphovascular invasion or oestrogen receptor status.

CONCLUSION

ALND should be considered in patients with micro-metastasis at SLNB. It should rarely be employed in the setting of SLNB positive for ITCs.

Promises and challenges of stem cell research for regenerative medicine

In recent years, stem cells have generated increasing excitement, with frequent claims that they are revolutionizing medicine. For those not directly involved in stem cell research, however, it can be difficult to separate fact from fiction or realistic expectation from wishful thinking. This article aims to provide internists with a clear and concise introduction to the field. While recounting some scientific and medical milestones, the authors discuss the 3 main varieties of stem cells-adult, embryonic, and induced pluripotent-comparing their advantages and disadvantages for clinical medicine. The authors have sought to avoid the moral and political debates surrounding stem cell research, focusing instead on scientific and medical issues.

Will cell reprogramming resolve the embryonic stem cell controversy? A narrative review

In the past few years, relatively straightforward laboratory techniques have been developed to reprogram normal body cells to enter an embryonic stem cell-like state. Not only do these induced pluripotent stem cells hold great medical promise--perhaps greater than that of embryonic stem cells--but they also have escaped the ethical controversy in which the latter is mired. This article examines how cell reprogramming is likely to transform regenerative and reproductive medicine and highlights some of the medical, moral, and political hurdles that it faces. It also argues that induced pluripotent stem cells are more ethically problematic than most people believe and that cell reprogramming will not solve the stem cell controversy but complicate it further.

Neurologic disease burden in treated HIV/AIDS predicts survival: a population-based study

BACKGROUND

Combination antiretroviral therapy (cART) has improved the survival of patients with HIV/AIDS but its impact remains uncertain on the changing prevalence and incidence of neurologic disorders with ensuing effects on mortality.

METHODS

The prevalence and incidence of neurologic disorders were examined in patients receiving active care in a regional HIV care program from 1998 to 2008. The mortality hazard ratio (HR) was calculated by Cox proportional hazard models with adjustment for demographic and clinical variables.

RESULTS

Of 1,651 HIV-infected patients assessed, 404 (24.5%) were identified as having one or more neurologic disorders, while 41% of AIDS-affected persons exhibited neurologic disease. Symptomatic distal sensory polyneuropathy (DSP, 10.0%) and HIV-associated neurocognitive disorder (HAND, 6.2%) represented the most prevalent disorders among 53 recognized neurologic disorders. Patients with at least one neurologic disorder exhibited higher mortality rates (17.6% vs 8.0%, p < 0.0001), particularly AIDS-related deaths (9.7% vs 3.2%, p < 0.0001), compared with those without neurologic disorders. The highest mortality HR was associated with opportunistic infections of CNS (HR 5.3, 95% confidence interval [CI] 2.5-11.2), followed by HAND (HR 3.1, 95% CI 1.8-5.3) and the presence of any neurologic disorder (HR 2.0, 95% CI 1.2-3.2). The risk of AIDS-related death with a neurologic disorder was increased by 13.3% per 100 cells/mm(3) decrement in blood CD4+ T-cell levels or by 39% per 10-fold increment in plasma viral load.

CONCLUSIONS

The burden and type of HIV-related neurologic disease have evolved over the past decade and despite the availability of cART, neurologic disorders occur frequently and predict an increased risk of death.