Loose complexation of weakly charged microemulsion droplets and a polyelectrolyte.

The effect of polyelectrolyte addition on the properties of an oil-in-water (O/W) microemulsion of weakly charged spherical micelles is studied. The 81 A radius O/W droplets in this system can be charged by the partial substitution of the nonionic surfactant by a cationic surfactant. The effect of the addition of poly(acrylic acid) (PAA), which is a charged pH-dependent polyelectrolyte, on the interactions between charged or noncharged droplets has been investigated using SANS. We have characterized the phase behavior of this pH-smart system as a function of the microemulsion and the polyelectrolyte concentration and the number of charges per droplet at three pH values: pH = 2, 4.5, and 12. In particular, an associative phase separation due to the bridging of the droplets by the neutral PAA chains through H-bonds is observed with extremely low PAA addition at low pH. At the opposite, an addition of PAA at pH = 4.5 generates a strong repulsive contribution between neutral droplets. Electrostatic bonds between charged droplets and PAA, controlled by the number of charges per droplet, are responsible for a pH drift and then for an associative phase separation similar to that observed at low pH. Finally, at high pH, the creation of electrostatic bonds between fully charged PAA and charged droplets liberates sufficiently counterions in solution at high droplet charge density to screen the electrostatic interactions and to allow an associative phase separation.

Apolipoprotein E polymorphism and response to electroconvulsive therapy.

The aim of this study was to determine whether the apolipoprotein E genotype differs in patients who respond or do not respond to electroconvulsive therapy (ECT). Inpatients, out-patients, and day-treatment patients who had received ECT comprised the study group. The 34 patients included met DSM-III-R criteria for affective or schizoaffective disorder. Responder or nonresponder status was assessed using the Clinical Global Inventory and Montgomery Asberg Depression Rating Scale. Blood samples were taken and coded when the patients entered the study. DNA extraction and apolipoprotein E genotyping were performed with no knowledge of the clinical classification of the patients. A significant difference in E4 genotype distribution was found between ECT responders and nonresponders (p < 0.02); psychosis was significantly less frequent in this group (p = 0.046), and there was a trend toward older onset of depression among these persons (p = 0.10). Only the E3/3 genotype was found in the patients with early-onset depression. The E4 genotype appears to define a subgroup of patients with late-onset depression who respond to ECT. If confirmed in prospective studies, this may provide a useful marker in the treatment decision-making process for late-onset depression.

Prognostic validity of clinical and psychometric variables in psychogeriatric inpatients.

The prognostic validity of both clinical and psychometric variables in a sample of psychogeriatric inpatients was evaluated. Elderly patients were divided into three outcome groups (nondischarged, n = 29; discharged-readmitted, n = 38; and discharged-nonreadmitted, n = 67), and comparisons were made on the clinical and psychometric variables. Results were cross-validated on a new sample of patients. Discriminant analysis yielded two predictive functions, which appeared to represent physical status and behavioral disturbance. Results suggest that a combination of clinical and psychometric variables yields the best level of prediction.

The dissolution of language in Alzheimer's disease.

Language impairment in Alzheimer's disease has become an important clinical issue. It has been recognized for some time that the disease may begin with aphasia and even before frank aphasia develops, some of the earliest changes in a large number of individuals consist of impairment of word fluency and semantic access manifesting itself in word finding difficulty. The second major issue concerning language in Alzheimer's disease is that the cases which have early severe language impairment may represent a more progressive familial variety of disease as it has been suggested in the literature. This is still subject to controversy. Finally, it will be documented that the later stage of the disease shows language invariably impaired and goes through stages of dissolution that resemble anomic, transcortical sensory. Wernicke's and global aphasias. Accurate assessment of language may turn out to be one of the most reliable predictors of the stages of Alzheimer's disease and provides important insights into the cerebral organization of language, semantic access, relationship of semantic and episodic memory and the pathophysiology of the disease.

Hyperammonemia in Alzheimer's disease.

Postprandial blood ammonia levels were significantly higher in 22 patients with Alzheimer's disease than in 37 control subjects. In the Alzheimer group, fasting blood ammonia levels were significantly higher in patients whose EEGs showed triphasic waves than in patients without this change. The direction of change from fasting to postprandial blood ammonia levels was also significantly different between these two groups.