The amygdala is part of the behavioural reinforcement system modulating long-term potentiation in rat hippocampus

Long-term potentiation (LTP) in the dentate gyrus can be modulated and prolonged by emotional/motivational influences when concurrently activated. A similar effect on LTP can be obtained by stimulating the amygdala, suggesting that this limbic structure might be part of the neural system involved in behavioural reinforcement. To confirm this we have performed a series of experiments in which the basolateral amygdala was either temporary inactivated by injection of lidocaine or permanently lesioned electrolytically. Both manipulations completely blocked the reinforcing effect of a motivational stimulus (drinking after 24-h deprivation) on LTP at the perforant pathway-dentate gyrus synapses, whilst leaving intact the non-reinforced potentiation. These results demonstrate that the basolateral amygdala is a key structure within the system involved in the modulatory interaction between the affective status of the animal and the mechanisms of functional plasticity.     

Partial purification and characterization of anhydrotetracycline oxygenase of Streptomyces aureofaciens

Anhydrotetracycline oxygenase was purified both by affinity chromatography and by hydrophobic interaction chromatography. Molecular weight of anhydrotetracycline oxygenase was determined to be 115,000 by Sephadex G-200 gel filtration. Using preparative isoelectric focusing the isoelectric point of the enzyme was estimated to be 5.3. The enzyme showed a sensitivity to thiol-specific inhibitors. During the hydrophobic interaction purification step, the activity dropped considerably. Reactivation occurred when a heat treated crude extract was added to the reaction mixture.     

Structure-intestinal transport and structure-metabolism correlations of some potential cancerostatic pyrimidine nucleosides in isolated rat jejunum

Summary Both transport and biotransformation processes for a series of pyrimidine nucleobases, ribonucleosides, 2-deoxyribonucleosides, and acetyl and 5-substituted derivatives of the cancerostatic agent araC were studied in the isolated everted rat jejunum with a continuous perfusion technique. Metabolic alterations during penetration were assessed by HPLC. 5-Halogeno and 5-deoxy derivatives of cytosine nucleosides exhibited higher transport rates and higher stability towards the deamination reaction than did unsubstituted derivatives. Octanol-buffer partition coefficients were estimated for the study compounds, and fragmental constants for the sugar moieties of nucleosides were assessed. With the present study compounds there was no correlation between lipophilicity and transport rate, as previously reported, but there was a correlation between lipophilicity and metabolic alteration of araC derivatives (r=0.99, n=5).     

Inhibition of two imidazole antimycotics, eberconazole and clotrimazole, by different components of Candida albicans serotype B membrane protoplasts

The inhibitory activity of different components from Candida albicans membrane protoplasts against clotrimazole and eberconazole was studied. The phospholipid fraction had the most inhibitory activity and the antimycotic activity of eberconazole was more affected than that of clotrimazole.     

Poly (triethylenglycol monomethacrylate) and poly(glycerol monomethacrylate) cross-linked gel as potential viscoelastics for intraoperative use

Background: The highly swelling poly(glycerol monomethacrylate) gel (polyGLYMA) and hydrophilic polymer poly(triethylenglycol monomethacrylate (polyTEGMA) were tested as potential viscoelastics for intraopertive use in anterior segment surgery. Methods: PolyGLYMA was implanted into the anterior chamber in 5 rabbits, and 40% polyTEGMA in 16 rabbits. The eyes were enucleated 1 week to 3 months after the operation. The corneal endothelium was examined with specular microscopy, and then the whole eye histopathologically. Results: In all eyes of the polyGLYMA group, the clinical findings were characterized by a marked ciliary injection and severe secondary glaucoma, and the histologic ones by a marked inflammatory infiltration and thickening of Descemet's membrane in the anterior chamber angle. Specular microscopy revealed a decrease in the endothelial cell density and polymorphism of the endothelial cells. In the polyTEGMA group, the anterior segment and the fundus were physiologic all the time, and specular microscopy and histologic findings showed no degenerative and/or inflammatory changes. Conclusions: PolyGLYMA proved unsuitable for intracameral application in rabbits. The new polymer polyTEGMA is characterized by high biologic tolerance after its implantation into the anterior chamber of rabbits. PolyTEGMA 40% might be considered as a potential viscoelastic material in humans.     

Effects of excitatory amino acid antagonists on social recognition of male rats

The effects of NMDA and non-NMDA glutamate receptor antagonists were evaluated on social recognition of adult male rats. Adult animals were injected (s.c.) with drug or saline immediately after the initial exposure to a juvenile male, 21-24 days old, and re-exposed to the same or to a novel juvenile 30min later. If the time spent by animals in social investigation during re-exposure to the same juvenile was comparable with the time measured during the initial exposure and with the time of animals re-exposed to a novel juvenile, the effect of a drug was designated as amnesia. Such an effect was found in adult animals administered 1 and 1.5mg/kg phencyclidine, 0.1mg/kg dizoclipine, 2.5mg/kg CPP, and 4mg/kg CGS 19755. Amnesic effects were observed at doses not affecting motor performance. No amnesic effect was produced by CNQX and NBQX (2.5, 5 and 10mg/kg). These results show that while recognition capacity in adult male rats is disrupted by several NMDA antagonists, non-NMDA antagonists do not interfere with short-term retention of individual odours. This suggests that NMDA glutamate receptors may be involved in the processing of socially relevant olfactory information.     

The SOL formulas for converting SMOG readability scores between health education materials written in Spanish, English, and French

The SMOG formula is widely used to determine how easy written health education materials are to read and comprehend. This study was conducted to assess whether the SMOG formula, originally developed and tested in English, was also valid for texts written in Spanish and French. Readability scores from a sample of passages written in Spanish, English, and French were analyzed. Study results showed that the SMOG formula seemed to be consistent in measuring readability in the three languages. However, SMOG scores varied from language to language. Two hypotheses are being laid out to explain these results. First, the SMOG equation is systematically biased for texts in Spanish or French. Second, English is more readable than French, and French is more readable than Spanish. Under the assumption of a systematic bias in the SMOG formula, the so-called SOL formulas are presented here to convert SMOG scores between Spanish, English, and French. In addition, a new scale for grading reading difficulty is proposed based on SMOG scores obtained from classical literature. This is important to the extent that it will provide Spanish speaking and French speaking health communicators with a readability formula for preparing written materials appropriate to the level of comprehension of specific target audiences.     

Prognostic factors in fetal hydronephrosis: a multivariate analysis

With the increasing use of obstetric echography fetal hydronephrosis has been reported more frequently. The purpose of this study was to identify prognostic factors associated with adverse outcome, such as renal failure and death, in fetal hydronephrosis. One hundred and forty-eight children with fetal hydronephrosis were admitted, submitted to a systematic protocol, and prospectively followed. Prognostic factors associated with fetal echography and clinical and laboratory findings on admission were studied. The median follow-up was 39 months. The analysis was conducted in two steps. In a univariate analysis, variables associated with adverse outcome were identified by the Kaplan-Meier method. The variables that were significantly associated with adverse outcome were then included in a multivariate analysis. This analysis, using the multivariate Cox’s model, was performed to identify variables that were independently associated with a worse prognosis. Only variables that remained independently associated with adverse outcome were included in the final model. After final adjustment by Cox’s multivariate model, three variables were identified as independent predictors of adverse outcome: oligohydramnios, prematurity, and glomerular filtration rate lower than 20 ml/min. Thus, in the presence of oligohydramnios, prematurity, and abnormal renal function, the medical team must plan appropriate follow-up for infants at health centers prepared to investigate and treat uropathies in newborns. Received: 24 August 1998 / Revised: 7 December 1998 / Accepted: 11 December 1998