Effects of daily water drinking on orthostatic and postprandial hypotension in patients with multiple system atrophy

OBJECTIVE : It has been demonstrated that the increased blood pressure (BP) caused by a single dose of water alleviates orthostatic hypotension (OH) and postprandial hypotension (PPH) in patients with autonomic failure (AF). The aim of this study was to evaluate the practical effect of daily water drinking on OH and PPH in the morning when patients with AF are usually most affected. METHODS : In five patients with multiple system atrophy (MSA) characterized by intractable OH and PPH, we measured seated, standing and postprandial BP in the morning without and with ingestion of 350 ml tap water at 07.30 hours for seven successive days. The changes from the basal BP level at 07.30 hours (DeltaBP) were assessed as an index of the effect of water drinking. RESULTS : Water drinking elicited a rapid pressor response in all patients. The DeltaBP during sitting, standing and after a meal following water drinking (day 1 and day 7) was significantly higher than without water drinking (day 0). The effects of reducing OH and PPH on day 7 were equivalent to those on day 1. No adverse effects associated with daily water drinking were observed, except later diuresis, which occurred in one patient. CONCLUSIONS : Daily water drinking demonstrated constant pressor effects in the morning with no severe adverse effects in MSA patients. This finding suggests that water drinking should be tried as a practical measure to prevent or reduce OH and PPH.     

West syndrome in a patient with balanced translocation t(X;18)(p22;p11.2)

We describe a case of West syndrome with the balanced translocation t(X;18)(p22;p11.2). Treatment with high-dose vitamin B6, adrenocorticotropic hormone, thyrotropin-releasing hormone, and antiepileptic compounds was not effective, and the patient exhibited persistent refractory seizures and severe developmental delays. Although no mutation analysis and X chromosome inactivation were performed, we suggest that the chromosomal abnormality in the present patient is the main etiologic factor responsible for the infantile spasms and severe developmental delay.     

Voxel-based analysis of P300 electrophysiological topography associated with positive and negative symptoms of schizophrenia

Abnormal P300 waveforms of the event-related potentials during the auditory oddball task are one of the most consistent findings in patients with schizophrenia. In the present study, we sought to test the hypothesis that the abnormal P300 waveform results from composite representation of neural activity in anatomically distinct brain regions responsible for the manifestation of positive and negative symptoms. We used the low-resolution brain electromagnetic tomography (LORETA) to obtain current density images of the P300 component from 26 patients with schizophrenia. The statistical parametric mapping (SPM) was applied to the LORETA images in order to identify brain regions that are related with the severity of psychotic symptoms as evaluated by the Brief Psychiatric Rating Scale (BPRS). The BPRS Total score was negatively correlated with the P300 current density in the left superior temporal gyrus (r=-0.615, corrected p=0.009) and that in the right medial frontal region (r=-0.571, corrected p=0.019) by means of SPM single-subject covariates model. These brain regions were included in the region-specific P300 sources as represented by the current density maxima (corrected p<0.05) using SPM one-sample t-test. A subsequent region-of-interest analysis of Pearson correlations revealed specific relationships between the Positive subscale score and the mean current density in the left superior temporal gyrus (r=-0.528, p=0.005) and between the Negative subscale score and the mean current densities in the medial frontal region (r=-0.551, p=0.003) and left superior temporal gyrus (r=-0.499, p=0.009). These results indicate that functional disturbances of neural networks involving the medial prefrontal and superior temporal regions may be responsible for the generation of positive and the negative psychotic symptoms of schizophrenia.     

In vitro selection of DNA aptamers that block toxic effects of AGE on cultured retinal pericytes

Microvessels are composed of endothelial cells and pericytes. We have previously shown that advanced glycation end products (AGE) not only inhibit DNA synthesis but also induce apoptosis in cultured retinal pericytes, thereby being involved in pericyte loss, the earliest histopathological hallmark of diabetic retinopathy. Since pericytes play a central role in the maintenance of microvascular homeostasis in the retina, blockade of the harmful effects of AGE on retinal pericytes may become a novel therapeutic strategy for the treatment of diabetic retinopathy. In this study, we selected DNA aptamers directed against AGE in vitro and then examined their cytoprotective effects on AGE-exposed retinal pericytes. We identified 15 DNA aptamers directed against AGE-human serum albumin using combinatorial chemistry techniques in vitro. Structural analysis revealed that they had bulge-loop structures with cytosine-rich sequences. All of the aptamers, but not non-binding control aptamers, were found to inhibit the AGE-induced decrease in DNA synthesis as well as apoptotic cell death in pericytes. Among the selected aptamers, the clone 9 aptamer completely blocked the toxic effects of AGE, and its dissociation constant was 1 micromol/L. These results indicate that DNA aptamers are a useful tool for inhibiting the cytotoxic effects of AGE on cultured retinal pericytes. Our study suggests that blockade of the AGE effects by DNA aptamers may lead to a novel therapeutic strategy for the treatment of diabetic retinopathy.