Dopamine differentially modulates the size of projection neuron ensembles in the intact and dopamine-depleted striatum

Dopamine (DA) is a critical modulator of brain circuits that control voluntary movements, but our understanding of its influence on the activity of target neurons in vivo remains limited. Here, we use two-photon Ca2+ imaging to monitor the activity of direct and indirect-pathway spiny projection neurons (SPNs) simultaneously in the striatum of behaving mice during acute and prolonged manipulations of DA signaling. We find that increasing and decreasing DA biases striatal activity toward the direct and indirect pathways, respectively, by changing the overall number of SPNs recruited during behavior in a manner not predicted by existing models of DA function. This modulation is drastically altered in a model of Parkinson's disease. Our results reveal a previously unappreciated population-level influence of DA on striatal output and provide novel insights into the pathophysiology of Parkinson's disease.

Relative value of the Ankle-Brachial Index of intermittent claudication

INTRODUCTION

The Ankle-Brachial Index (ABI) makes it possible to identify patients with peripheral artery disease (PAD). Intermittent claudication (IC) is the first major symptom of PAD, although many patients with an ABI ≤ 0.9 do not exhibit IC, and the range of ABI among those who do have IC is very variable. This study evaluates the correlation between ABI and the perception (symptomatology) of claudicant patients.

MATERIAL AND METHODS

An observational, cross-sectional and multicentre, study of 920 patients with IC. Clinical history, ABI, Walking Impairment Questionnaire (WIQ) and European Quality of Life Questionnaire (EQ-5D) were recorded. Associations were analysed using Spearman's correlation coefficient.

RESULTS

The mean ABI of the series was 0.63 (SD = 0.19). The mean WIQ-distance was 34.07 (SD = 26.77), values being smaller for lower ABI values (r = 0.343, p < 0.001). The mean EQ-5D score of the series was 0.58 (SD = 0.21), also showing lower values as the ABI decreased (r = 0.278, p < 0.001). The correlations of WIQ and EQ-5D with ABI were statistically significant in both cases, but always less than 0.400 (between 0.278 and 0.343).

CONCLUSIONS

The correlations of ABI with the questionnaires of walking capacity and quality of life are weak. For this reason, although in clinical practice the ABI of CI patients is commonly measured, decisions should not be taken during the development of IC exclusively on the basis of the ABI.

Direct association between C-reactive protein serum levels and endothelial dysfunction in patients with claudication

OBJECTIVES

To evaluate the relationship between C-Reactive Protein (hsCRP), a serum marker of inflammation, and endothelial dysfunction in patients with intermittent claudication.

DESIGN, PATIENTS AND METHODS

Cross-sectional study with stratified sampling on dependent variables of age, genre, hypertension, hyperlipidemia, diabetes, smoking status and ankle-brachial index (ABI) to select 156 patients from a target population of 4,100 patients with claudication. We assessed the flow-mediated arterial dilation (FMAD) as a reporter of endothelial function and plasma levels of hsCRP and fibrinogen.

RESULTS

Patients with a FMAD<3% (range for the lowest 5% of healthy subjects) had increased levels of plasma hsCRP (6.3 vs 2.3mg/L; p<0.05) and fibrinogen (351vs 302mg/L; p<0.05) in comparison to those with FMAD>3%. There was a negative correlation between hsCRP and FMAD(r=-0.465; p<0.05).

CONCLUSION

Impaired endothelial dysfunction is association with increased plasma concentrations of inflammatory markers, and both may have a role in the aetiopathogenesis of peripheral arterial disease.

Impact of endovascular surgery on management of critical lower-limb ischemia in a vascular surgery department

The authors analyzed the impact of introduction of endovascular techniques on management and evolution of critical ischemia (CI) in an Angiology and Vascular Surgery department. This is a retrospective review of patients admitted for CI during 2 2-year periods (A: January 1997-December 1998 and B: January 2000-December 2001) differentiated by introduction of endovascular techniques in 1999. Demographic data, clinical symptoms, treatment used, and evolution were recorded and compared between the 2 periods. Survival and limb salvage were analyzed by life tables and compared by log-rank test. One hundred and ninety-three admissions (limbs) for CI were recorded in period A and 226 admissions (limbs) in period B, with no differences in terms of age, sex, clinical severity, or region affected. The distribution of the treatments used in groups A, B, and group B with exclusion of endovascular techniques (B*), was as follows: revascularization (A: 67.4%; B: 50%; B*: 65%); endovascular (A: 0%; B: 23%; B*: 0%); primary amputation (A: 11.4%; B: 11.1%; B*: 14%); conservative (A: 21.2%; B: 15.9%; B*: 21%). Excluding the endovascular procedures, there were no differences between periods as regards the type of treatment or the surgical technique used. There were no differences in early mortality or complication rates. Long-term survival was significantly better in periods B and B* than in period A (p < 0.01). Insignificant improvement in limb salvage was observed in period B (A 74% vs B 82.5%; 12 months). Endovascular procedures extend the therapeutic arsenal, but they do not change management and evolution of CI. Improved survival observed in period B is maintained when endovascular procedures are excluded (period B*), so cannot be attributed only to endovascular techniques.

Peroneal arteriovenous fistula as a complication of above-knee femoropopliteal polytetrafluorethylene graft thrombectomy with the Fogarty catheter

The Fogarty catheter is an invaluable tool in the surgical practice of a vascular surgeon. Arteriovenous fistula is an unusual but potentially dangerous complication of its use. We present the case of a man who suffered a peroneal arteriovenous fistula as a result of an above-knee femoropopliteal polytetrafluorethylene graft thrombectomy. As the fistula compromised the viability of the extremity, surgical correction was warranted. It was performed without further complications to the patient. The few cases reported in the literature are reviewed. We conclude that this complication should be repaired as soon as it is detected.