Medial prefrontal transection enhances social interaction. II: neurochemical studies

Medial prefrontal cortex (MPFC) transection enhances social interaction in an open arena test. Social interaction enhances dopaminergic activity in the nucleus accumbens (NAC). In the present set of experiments, microdialysis probes were implanted in the NAC, and glutamate, gamma-aminobutyric acid (GABA) and dopamine (DA) were measured during electrical stimulation of the MPFC, after coronal transection caudal to the MPFC and after a systemic injection of amphetamine in transected rats. Electrical stimulation of the MPFC caused a transient enhancement of glutamate release in the NAC, no change in GABA levels and a long lasting increase in DA levels. Medial prefrontal transection did not change basal glutamate or GABA levels in the NAC, but increased basal DA levels. Amphetamine administration decreased GABA levels in medial prefrontal transected rats, had no effect on glutamate and increased DA levels more than in controls. The experiments suggest that glutamatergic activity in the accumbens decreases dopamine release. Medial prefrontal transection reduces glutamatergic tone and enhances dopamine release, which probably decreases GABAergic activity in the NAC. Presumably, GABA inhibition in the NAC enhances social interaction.     

Distribution of protein kinase Mzeta and the complete protein kinase C isoform family in rat brain

Protein kinase C (PKC) is a multigene family of at least ten isoforms, nine of which are expressed in brain (alpha, betaI, betaII, gamma, delta, straightepsilon, eta, zeta, iota/lambda). Our previous studies have shown that many of these PKCs participate in synaptic plasticity in the CA1 region of the hippocampus. Multiple isoforms are transiently activated in the induction phase of long-term potentiation (LTP). In contrast, a single species, zeta, is persistently activated during the maintenance phase of LTP through the formation of an independent, constitutively active catalytic domain, protein kinase Mzeta (PKMzeta). In this study, we used immunoblot and immunocytochemical techniques with isoform-specific antisera to examine the distribution of the complete family of PKC isozymes and PKMzeta in rat brain. Each form of PKC showed a widespread distribution in the brain with a distinct regional pattern of high and low levels of expression. PKMzeta, the predominant form of PKM in brain, had high levels in hippocampus, frontal and occipital cortex, striatum, and hypothalamus. In the hippocampus, each isoform was expressed in a characteristic pattern, with zeta prominent in the CA1 stratum radiatum. These results suggest that the compartmentalization of PKC isoforms in neurons may contribute to their function, with the location of PKMzeta prominent in areas notable for long-term synaptic plasticity.     

Partial left ventriculectomy: which patients can be expected to benefit?

Background. Although some patients with end-stage heart disease will benefit from a partial left ventriculectomy, no criteria have been found for identifying this group preoperatively. Our experience with partial left ventriculectomy at two institutions—the Texas Heart Institute in Houston, TX, USA, and Dedinje Cardiovascular Institute in Belgrade, Yugoslavia—showed a higher survival rate and better postoperative myocardial function in the Yugoslavian patients.

Methods. We reviewed data from 42 patients (21 at each center) who had idiopathic cardiomyopathy, a left ventricular end-diastolic dimension of more than 70 mm, wall thickness of 1 cm or greater, and New York Heart Association class III or IV symptoms. The only significant difference in preoperative status between the two groups was duration of symptoms. Histologic specimens, blinded as to origin, were graded with regard to myocyte hypertrophy, cytoplasmic vacuolation, and fibrosis. Computer-assisted myocyte and nuclear morphometry was also performed.

Results. Immediately postoperatively, there were no significant intergroup differences in the reduction in cardiac dimension or in corrections of mitral regurgitation. During 6-month follow-up, however, the Texas Heart Institute patients had a lower cardiac index (1.8 versus 3.0 L·min⁻¹·m⁻²; p = 0.001) and left ventricular ejection fraction (24% versus 34%; p = 0.006) than the Dedinje Cardiovascular Institute patients. The Texas Heart Institute patients differed from the Dedinje Cardiovascular Institute patients in the degree of severe or moderate changes in myocyte hypertrophy (90% versus 29%; p = 0.0003) and fibrosis (71% versus 29%; p = 0.006), as well as in the measurements of median myocyte diameter (35 ± 7 μm versus 27 ± 4 μm; p = 0.0002) and median nuclear size (15 ± 4 μm versus 12 ± 2 μm; p = 0.0029).

Conclusions. In the Texas Heart Institute patients, the significant intergroup difference in clinical outcome may have been related to increased myocyte hypertrophy and fibrosis. Further studies should be performed to determine the usefulness of these criteria in selecting patients for partial left ventriculectomy.     

L’alimentation des patients neutropéniques d’un service d’onco-hématologie pédiatrique ; l’expérience des hôpitaux universitaires de Strasbourg (HUS)

ObjectiveThis article clarifies the choices made by the HUS concerning the ways of preparing food reserved to neutropenic children hospitalized in pediatric oncology service. We will describe the results of microbiological analysis of food realized from 2002 to 2007.MethodsA specific team prepares this food which is canned and treated by “appertisation” (autoclaving). Each dish portion produced is provided to the service only if the microbiological results are conform, that is to say free of organisms.ResultsThree thousand and seventy-eight dishes were analysed: 82.9% of the analysed packs were conform. The contamination ratio decreased significantly (P < 0.001) from 2002 to 2007. The organisms which cause the majority of dishes contamination are Bacillus (44.7%) and environmental mould exhibiting sterile mycelium (8.7%). The food which is the most frequently “nonconform” is the dry food with a contamination rate of 37.9%. The identified concentrations remain mainly lower than 50 colony-forming units per millilitre (CFU/mL): 66.2% for the bacteria and 97.2% for the fungi.ConclusionConsidering the lack of consensus on the acceptable microbiological thresholds and on the food protection level, the HUS make it a rule to have a maximal precautionary principle. Currently, this principle appears to us to be a safety option required for the patients hospitalized in pediatric oncology service.     

In vitro study of a modified sagittal split osteotomy fixation technique of the mandible: a mechanical test

This study was performed to evaluate the compressive mechanical strength of rigid internal fixation (RIF) using 1.5-mm L-shaped plates fixed with monocortical screws in sagittal split osteotomy (SSO). Thirty synthetic hemimandibles, which had all undergone a 5-mm advancement, were divided into three groups: three 12-mm bicortical titanium screws were placed in an inverted L pattern in group A; one straight 2.0-mm system spaced titanium plate fixed with four 5-mm monocortical screws was used in group B; two 1.5-mm system L-shaped titanium plates, each fixed with four 5-mm monocortical screws, were used in group C. The models were subjected to compressive and progressive mechanical tests with forces applied in the area between the second premolar and first molar to verify resistance in Newtons (N). A displacement speed of 1 mm/min was applied, with a maximum 10 mm displacement of the distal segment or until disruption of the fixation. The deformity and/or eventual rupture of the plates were evaluated, and consequently their technical stability was determined. The results showed that the modified fixation technique tested in this study on synthetic mandibles resulted in adequate stability and superior mechanical behaviour compared to simulated osteosynthesis with the use of a straight 2.0-mm titanium plate.