Cerebral autoregulation is preserved in multiple system atrophy: A transcranial Doppler study.

Patients with multiple system atrophy (MSA) present large changes in blood pressure (BP) due to autonomic disturbances. We analyzed how this change may influence dynamic cerebral autoregulation (DCA). Simultaneous recordings of arterial BP (Finapres) and middle cerebral artery (MCA) blood flow velocity (BFV) (transcranial Doppler) were performed in 10 patients with MSA (61 +/- 12 yr of age) and 12 healthy volunteers (61 +/- 11 yr of age): cerebral BFV response to oscillations in mean BP was studied in the supine position by cross-spectral analysis of mean BP and mean MCA BFV. The DCA was also studied during the decrease in BP the first seconds when standing up from a sitting position by the assessment of the cerebrovascular resistance index (CR; mean BP/mean MCA BFV ratio). The MCA BFV/BP cross-spectral analysis showed a phase for the mid-frequency band (0.07-0.2 Hz) significantly larger in MSA, suggesting more active autoregulation in response to larger changes in BP. Changes in CR reflecting the rate of autoregulation, when standing did not differ between the two groups. These data suggest that dynamic cerebral autoregulation is preserved in MSA.     

Measurement of alveolar derecruitment in patients with acute lung injury: computerized tomography versus pressure–volume curve

Introduction  

Positive end-expiratory pressure (PEEP)-induced lung derecruitment can be assessed by a pressure–volume (P–V) curve method or by lung computed tomography (CT). However, only the first method can be used at the bedside. The aim of the study was to compare both methods for assessing alveolar derecruitment after the removal of PEEP in patients with acute lung injury or acute respiratory distress syndrome.     

Factors influencing the variations of ejection fraction during exercise in chronic aortic regurgitation

The influence of left ventricular volume variations and regurgitant fraction variations upon left ventricular ejection fraction, during exercise was examined using equilibrium radionuclide angiography in patients suffering from aortic regurgitation. Ejection fraction (EF), regurgitant fraction (RF), end diastolic volume (EDV) and end systolic volume (ESV) variations from rest to peak exercise were determined in 44 patients suffering from chronic aortic regurgitation (AR) and in 8 healthy volunteers (C). In C, EF increased (+0.10±0.03, P<0.01) and ESV decreased significantly (-23%±12%, P<0.01) RF and EDV did not vary significantly. In AR patients, EF, EDV and ESV did not vary significantly because of important scattering of individual values. Changes in EF and ESV were inversely correlated (r=-0.79, P<0.01) and RF decreased significantly (-0.12±0.10, P<0.01). Volumes and EF changes during exercise occurred in three different ways. In a 1st subgroup of 7 patients, EF increased (+0.09±0.03, P<0.05) in conjunction with a reduction of ESV (-24%±12%, P<0.05) without a significant change in EDV. In a 2nd group of 22 patients. EF decreased (-0.04±0.07, P<0.01) in association with an increase in ESV (+17%±16%, P<0.01) and no change in EDV. In a 3rd subgroup of 15 patients, EF decreased (-0.02±0.06, P<0.01) despite a reduction in ESV (-7%±6%, P<0.01) because of a dramatic EDV decrease (-10%±6%, P<0.05). In this subgroup, changes in EF were inversely correlated with changes in ESV (r=-0.55, P<0.01) and positively related to EDV variations (r=0.42, P=0.02). EDV related to EDV variations (r=0.42, P=0.02). EDV changes were weakly, but significantly, correlated to RF decrease (r=0.39, P<0.05). We conclude that changes in left ventricular ejection fraction during exercise in patients with chronic aortic regurgitation are significantly related in some patients to changes in ventricular loading conditions as well as contractile state. Therefore, a correct interpretation of EF changes during exercise requires the simultaneous determination of changes in LV volumes.Abbreviations EDV end diastolic volume - EF ejection fraction - ESV end systolic volume - LV left ventricle - RV right ventricle     

Blood velocity assessment using 3D bright-blood time-resolved magnetic resonance angiography.

Blood velocity is a functional parameter that is not easily assessed noninvasively, especially in small animals. A new noninvasive method that uses magnetic resonance angiography (MRA) to measure blood flows is proposed. This method is based on the time-of-flight (TOF) phenomenon. By initially suppressing the signal from the stationary spins in the area of interest, it is possible to sequentially visualize only the signal from the moving spins entering a given volume. With this method, 3D cine images of the blood flow can be generated by positive contrast, with unparalleled spatial (<200 microm) and temporal resolutions (<10 ms/image). As a result, it is possible to measure flow in sinuous paths. The present method was applied in vivo to measure the blood velocity in mouse carotid arteries. Because of its robustness and simplicity of implementation, this method has numerous potential applications for fundamental studies in small animal models.     

Early Low-Grade Proteinuria: Causes, Short-Term Evolution and Long-Term Consequences in Renal Transplantation

Proteinuria 1 year after transplantation is associated with poor renal outcome. It is unclear whether low-grade (<1 g/24 h) proteinuria earlier after transplantation and its short-term change affect long-term graft survival. The effects of proteinuria and its change on long-term graft survival were retrospectively assessed in 484 renal transplant recipients. One- and 3-month proteinuria correlated with donor age, donor cardiovascular death, prolonged cold and warm ischemia times and acute rejection. One- and 3-month proteinuria (per 0.1 g/24 h, hazard ratio (HR): 1.07 and 1.15, p<0.0001)-especially low-grade proteinuria (HR: 1.20 and 1.26, p<0.0001)-were powerful, independent predictors of graft loss. Its short-term reduction correlated with arterial pressure (AP) (the lower the 3-month diastolic and 12-month systolic AP, the lower the risk of increasing proteinuria during 1-3 months and 3-12 months periods, respectively: Odds ratio (OR) per 10 MmHg: 0.78, p=0.01 and 0.85, respectively, p=0.02), and was associated with decreased long-term graft loss (per 0.1 g/24 h: HR: 0.88 and 0.98, respectively, p<0.0001), independently of initial proteinuria. Early low-grade proteinuria due to pre-transplant renal lesions, ischemia-reperfusion and immunologic injuries is a potent predictor of graft loss. Short-term reduction in proteinuria is associated with improved long-term graft survival.     

Pharmacokinetics of cefotaxime and its desacetyl metabolite in plasma and in cerebrospinal fluid

The aim of the study was to investigate the pharmacokinetic modelling of Cefotaxime (CTX) and its main metabolite Desacetyl Cefotaxime (DCTX) which has a less antibacterial activity than the CTX. After intravenous administration of 1g of CTX to 26 patients, the plasma concentrations determined by HPLC showed that the pharmacokinetics of CTX and transformation to DCTX can be described with an open five-compartment model. The implications of this are discussed from the clinical point of view.     

Neuropathy associated with “benign” anti-myelin-associated glycoprotein IgM gammopathy: Clinical,immunological, neurophysiological pathological findings and response to treatment in 33 cases

We studied 33 patients presenting with a peripheral neuropathy associated with non-malignant anti-myelin-associated glycoprotein (MAG) IgM monoclonal gammopathy (MG) in an attempt to delineate their clinical, immunological, electrophysiological and pathological characteristics; we also reviewed our experience concerning long-term follow-up and therapy. Peripheral neuropathy associated with non-malignant anti-MAG IgM MG was observed mostly in males (sex ratio 7.2), and mean age at onset was 67 years (range 46–81). A predominantly sensory pattern was noted in more than 80% of cases, although some patients were affected by a predominantly motor peripheral neuropathy. Although disease progression was slow in most cases, 45% of patients suffered severe disability, and in 2 cases, the patient's death appeared to stem directly from the neuropathy. The electrophysiological findings were indicative of a demyelinating process in 90% of cases, and electron microscopic examination of nerve biopsy specimens demonstrated widening of the myelin lamellae in more than 95% of cases. Most of our patients showed a disappointing response to steroids and chemotherapy or plasma exchanges. Intravenous immune globulin, evaluated in 17 patients, had a transient, mostly subjective effect in 35% and led to a clear-cut improvement in 24% of cases. We did not observe any correlation between the severity of the clinical picture and the anti-sulphoglucuronyl paragloboside antibody titre; in individual cases, clinical improvement occurred without lowering of IgM levels. Although the severity and the rate of progression may greatly vary from patient to patient, the combination of clinical, electrophysiological and pathological features delineates a characteristic pattern in peripheral neuropathy associated with non-malignant anti-MAG IgM MG.     

Cardiac MIBG scintigraphy is a sensitive tool for detecting cardiac sympathetic denervation in Parkinson's disease.

[(123)I]Metaiodobenzylguanidine ([(123)I]MIBG) cardiac scintigraphy could be helpful to differentiate Parkinson's disease (PD) from multiple system atrophy (MSA), demonstrating that, in PD with autonomic failure but not in MSA, there is a myocardial postganglionic sympathetic dysfunction. To investigate whether this method is more sensitive than standard autonomic testing to detect early involvement of sympathetic cardiac efferent, we analyse MIBG myocardial uptake in 8 PD patients with normal autonomic testing (nondysautonomia PD group, NDPD) in comparison with 10 PD patients with abnormal autonomic testing (dysautonomia PD group, DPD) and 10 MSA patients. Global MIBG uptake was assessed using the ratio of [(123)I]MIBG uptake in the heart to the upper mediastinum (H/M) on planar scintigraphic data. Regional MIBG uptake was determined on two single photon emission tomography scans in regions of the left ventricle. The mean H/M ratios were significantly different among the three groups (P < 0.0001). H/M ratios of both NDPD and DPD patients groups (H/M = 1.83 +/- 0.50 and 1.24 +/- 0.40, respectively) were significantly lower than in MSA patients (H/M = 2.52 +/- 0.60). However, in NDPD patients, H/M was significantly higher than in DPD patients. When compared to MSA patients, NDPD patients showed a regional reduction in MIBG uptake in all left ventricle regions markedly in the apex and the inferior wall. Our results suggest that MIBG myocardial scintigraphy (analysis of both H/M ratio and regional MIBG uptake) may be more sensitive than standard autonomic testing for the early detection of silent autonomic dysfunction in PD.     

Efficacy of anti-digoxin antibodies in a premature neonate

Through the case report of severe digitalis intoxication in a premature born after 27 weeks of gestation with a birthweight of 800 g, the authors show that anti-digoxin antibodies constitute a very efficacious therapeutic tool which, up to the present, has not been used in prematures.