Deficits in coordinated neuronal activity and network topology are striatal hallmarks in Huntington's disease

Background

Network alterations underlying neurodegenerative diseases often precede symptoms and functional deficits. Thus, their early identification is central for improved prognosis. In Huntington’s disease (HD), the cortico-striatal networks, involved in motor function processing, are the most compromised neural substrate. However, whether the network alterations are intrinsic of the striatum or the cortex is not fully understood.

Results

In order to identify early HD neural deficits, we characterized neuronal ensemble calcium activity and network topology of HD striatal and cortical cultures. We used large-scale calcium imaging combined with activity-based network inference analysis. We extracted collective activity events and inferred the topology of the neuronal network in cortical and striatal primary cultures from wild-type and R6/1 mouse model of HD. Striatal, but not cortical, HD networks displayed lower activity and a lessened ability to integrate information. GABA_A receptor blockade in healthy and HD striatal cultures generated similar coordinated ensemble activity and network topology, highlighting that the excitatory component of striatal system is spared in HD. Conversely, NMDA receptor activation increased individual neuronal activity while coordinated activity became highly variable and undefined. Interestingly, by boosting NMDA activity, we rectified striatal HD network alterations.

Conclusions

Overall, our integrative approach highlights striatal defective network integration capacity as a major contributor of basal ganglia dysfunction in HD and suggests that increased excitatory drive may serve as a potential intervention. In addition, our work provides a valuable tool to evaluate in vitro network recovery after treatment intervention in basal ganglia disorders.

Social and clinical predictors associated with prolonged hospital stays for patients with severe exacerbation of chronic obstructive pulmonary disease

OBJECTIVE

To determine whether there are social factors that affect the prolonged hospital stay (PHS) of patients with severe chronic obstructive pulmonary disease exacerbation (COPDE), as well as clinical-demographic factors.

METHODOLOGY

We conducted a prospective cohort study that consecutively included patients who were admitted to a Pneumology department for COPDE. We recorded demographic, clinical (tobacco use, exacerbations and infections, dyspnoea, impact according to CAT questionnaire, pulmonary function, comorbidities, oxygen therapy and noninvasive ventilation) and social (financial status, caregiver availability and overload, dependence for basic and instrumental activities, social risk and use of social services) variables, employing questionnaires and indices such as Barthel, Lawton-Brody, Zarit, Barber and Gijón. We performed a univariate and multivariate analysis using a logistic regression model.

RESULTS

The study included 253 patients, with a mean age of 68.9±9.8years; 77.1% of whom were men. The logistic regression model included active tobacco use, FEV₁ value, CAT score >10, dyspnoea 3-4 on the MMRC, the presence of bacteria in sputum cultures, cardiovascular comorbidity, anaemia, home oxygen therapy, living alone, rural residence, caregiver overload and detecting social-family risks/problems. The variables independently associated with the possibility of PHS were a CAT score >10 (OR, 8.9; P=.04) and detecting a social-family risk/problem (OR, 2.6; P=.04). Active smoking was a predictor of shorter stays (OR, 0.15; P=.002).

CONCLUSIONS

Variables related to the social sphere play a relevant role in hospital stays, as do the impact of the disease and the persistent use of tobacco by patients with severe COPD exacerbation.

Canards in a minimal piecewise-linear square-wave burster

We construct a piecewise-linear (PWL) approximation of the Hindmarsh-Rose (HR) neuron model that is minimal, in the sense that the vector field has the least number of linearity zones, in order to reproduce all the dynamics present in the original HR model with classical parameter values. This includes square-wave bursting and also special trajectories called canards, which possess long repelling segments and organise the transitions between stable bursting patterns with n and n + 1 spikes, also referred to as spike-adding canard explosions. We propose a first approximation of the smooth HR model, using a continuous PWL system, and show that its fast subsystem cannot possess a homoclinic bifurcation, which is necessary to obtain proper square-wave bursting. We then relax the assumption of continuity of the vector field across all zones, and we show that we can obtain a homoclinic bifurcation in the fast subsystem. We use the recently developed canard theory for PWL systems in order to reproduce the spike-adding canard explosion feature of the HR model as studied, e.g., in Desroches et al., Chaos 23(4), 046106 (2013).

Endometrial adenocarcinoma and mucometra in a 6-year-old Alaska Malamute dog

A 6-year-old female Alaska Malamute dog was presented for evaluation of abdominal enlargement referred by a local veterinarian. On the history, the owner complained of chronic abdominal enlargement initiated more than 4 months ago, reduced appetite, occasional vomiting and general dullness. He also complained of greenish mucous intermittent vaginal discharge starting 10 days ago. The bitch was chronically treated with medroxiprogesterone acetate. A laparatomy was performed and fluid in the abdomen was found and aspirated during the surgery. Also a very fluid-filled distended uterus and a mass in the distal part of the left uterine horn were found. The mass was encapsulated by the omentum, but areas of necrosis and calcification were identified. Histopathological diagnosis was endometrial adenocarcinoma.