Changes in cortical acetylcholine and gamma-aminobutyric acid outflow during morphine withdrawal involve alpha-1 and alpha-2 receptors

Naloxone (0.3-9 mumol kg-1), electrical stimulation of locus ceruleus or clonidine at low doses (7.5-112 nmol kg-1) increased the release of acetylcholine from the exposed parietal cortex of freely moving, morphine-tolerant guinea pigs. This increase was not additive and was prevented by prazosin (35.8 nmol kg-1), suggesting the involvement of alpha-1 receptors. At high doses (374 nmol kg-1 or more) clonidine inhibited acetylcholine release through alpha-2 receptors, as it did in naive animals at 7.5 nmol kg-1. Clonidine (374 nmol kg-1) and prazosin (35.8 nmol kg-1) reduced the objective signs of naloxone-precipitated withdrawal. Electrical stimulation of the locus ceruleus or naloxone treatment reduced the release of gamma-aminobutyric acid (GABA) from the exposed parietal cortex of morphine-tolerant guinea pigs. This reduction was not additive and was prevented by idazoxan (84 nmol kg-1), suggesting the involvement of alpha-2 receptors. Clonidine (7.5 nmol kg-1), too, reduced the release of GABA in morphine-tolerant animals. However, when tested jointly with naloxone, clonidine (7.5-112 nmol kg-1) induced alpha-1-mediated facilitation of GABA release (like that elicited in naive animals at 112-374 nmol kg-1) leaving the signs of withdrawal unchanged. This points to the stimulation of alpha-1 receptors highly responsive to this agonist (but not to locus ceruleus stimulation) during naloxone-precipitated withdrawal. In conclusion, chronic morphine treatment modifies the alpha-1- and alpha-2-mediated control of GABA and acetylcholine neurons.(ABSTRACT TRUNCATED AT 250 WORDS)     

Localized overexpression of FGF-2 and BDNF in hippocampus reduces mossy fiber sprouting and spontaneous seizures up to 4 weeks after pilocarpine-induced status epilepticus

Purpose: We have recently reported that viral vector–mediated supplementation of fibroblast growth factor‐2 (FGF‐2) and brain‐derived neurotrophic factor (BDNF) in a lesioned, epileptogenic rat hippocampus limits neuronal damage, favors neurogenesis, and reduces spontaneous recurrent seizures. To test if this treatment can also prevent hippocampal circuit reorganization, we examined here its effect on mossy fiber sprouting, the best studied form of axonal plasticity in epilepsy. Methods: A herpes‐based vector expressing FGF‐2 and BDNF was injected into the rat hippocampus 3 days after an epileptogenic insult (pilocarpine‐induced status epilepticus). Continuous video–electroencephalography (EEG) monitoring was initiated 7 days after status epilepticus, and animals were sacrificed at 28 days for analysis of cell loss (measured using NeuN immunofluorescence) and mossy fiber sprouting (measured using dynorphin A immunohistochemistry). Key Findings: The vector expressing FGF‐2 and BDNF decreased both mossy fiber sprouting and the frequency and severity of spontaneous seizures. The effect on sprouting correlated strictly with the cell loss in the terminal fields of physiologic mossy fiber innervation (mossy cells in the dentate gyrus hilus and CA3 pyramidal neurons). Significance: These data suggest that the supplementation of FGF‐2 and BDNF in an epileptogenic hippocampus may prevent epileptogenesis by decreasing neuronal loss and mossy fiber sprouting, that is, reducing some forms of circuit reorganization.     

C4d analysis in endomyocardial biopsies of heart transplant patients: is there a correlation with hemodynamic data?

Background

Endomyocardial biopsy (EMB) is the gold standard for immunologic follow-up to detect acute cellular rejection after cardiac transplantation. Conversely, protocols for the diagnosis and treatment of antibody-mediated rejection (AMR) are not well defined. Histologically, AMR is diagnosed by the presence of capillary damage associated with complement activation. The aim of this study was to correlate C4d expression of activated complement in EMB with hemodynamic compromise upon right heart catheterization.

Methods

Heart transplant patients underwent hemodynamic and histologic follow-up with EMB and right heart catheterization between January 2008 and December 2009 for a total of 491 procedures. The cardiac biopsy was evaluated for acute cellular and AMR by means of the presence of the C4d complement fraction. The histologic results were compared with hemodynamic data registered during right heart catheterization.

Results

Comparison of the hemodynamic data of subjects with versus without C4d positivity showed no significant difference. Furthermore, there was no significant difference comparing patients with versus without C4d positivity in the absence of significant acute cellular rejection episodes. (C4d−/ACR− vs C4d+/ACR−). The variation of each single hemodynamic parameter from its basal value (defined as the mean value in case of C4d−/ACR−) seemed to not be influenced by the presence of C4d+.

Conclusions

In our experience, C4d has been routinely evaluated in the majority of EMBs. We could not demonstrate a significant correlation of C4d positivity with hemodynamic compromise. These findings suggest that significant allograft dysfunction is not related to C4d positivity. Therefore, the diagnosis of AMR is difficult to establish, because allograft dysfunction is 1 of the 3 fundamental criteria.     

Loss of cortical GABA terminals in Unverricht-Lundborg disease

Unverricht-Lundborg disease (ULD) is the most common progressive myoclonic epilepsy. Its etiology has been identified in a defect of a protease inhibitor, cystatin B (CSTB), but the mechanism(s) by which this defect translates in the clinical manifestations of the disease are still obscure. We tested the hypothesis that ULD is accompanied by a loss of cortical GABA inhibition in a murine model (the CSTB knockout mouse) and in a human case. Cortical GABA signaling has been investigated measuring VGAT immunohistochemistry (a histological marker of the density of GABA terminals), GABA release from synaptosomes and paired-pulse stimulation. In CSTB knockout mice, a progressive decrease in neocortex thickness was found, associated with a prevalent loss of GABA interneurons. A marked reduction in VGAT labeling was found in the cortex of both CSTB knockout mice and an ULD patient. This implicates a reduction in GABA synaptic transmission, which was confirmed in the mouse model as reduction in GABA release from isolated nerve terminals and as loss of electrophysiologically measured GABA inhibition. The alterations in VGAT immunolabeling progressed in time, paralleling the worsening of myoclonus. These results provide direct evidence that loss of cortical GABA input occurs in a relevant animal model and in a case of human ULD, leading to a condition of latent hyperexcitability that favors myoclonus and seizures. These findings contribute to the understanding of the pathogenic mechanism of ULD and of the neurobiological basis of the effect of currently employed drugs.     

Smoking addiction and the risk of upper‐aerodigestive‐tract cancer in a multicenter case–control study

Although previous studies on tobacco and alcohol and the risk of upper‐aerodigestive‐tract (UADT) cancers have clearly shown dose‐response relations with the frequency and duration of tobacco and alcohol, studies on addiction to tobacco smoking itself as a risk factor for UADT cancer have not been published, to our knowledge. The aim of this report is to assess whether smoking addiction is an independent risk factor or a refinement to smoking variables (intensity and duration) for UADT squamous cell carcinoma (SCC) risk in the multicenter case–control study (ARCAGE) in Western Europe. The analyses included 1,586 ever smoking UADT SCC cases and 1,260 ever smoking controls. Addiction was measured by a modified Fagerström score (first cigarette after waking up, difficulty refraining from smoking in places where it is forbidden and cigarettes per day). Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for UADT cancers with addiction variables were estimated with unconditional logistic regression. Among current smokers, the participants who smoked their first cigarette within 5 min of waking up were two times more likely to develop UADT SCC than those who smoked 60 min after waking up. Greater tobacco smoking addiction was associated with an increased risk of UADT SCC among current smokers (OR = 3.83, 95% CI: 2.56–5.73 for score of 3–7 vs. 0) but not among former smokers. These results may be consistent with a residual effect of smoking that was not captured by the questionnaire responses (smoking intensity and smoking duration) alone, suggesting addiction a refinement to smoking variables.     

Clinical and histopathological analysis of oral squamous cell carcinoma in young people: a descriptive study in Brazilians

We retrospectively analysed the clinical and histological characteristics of oral squamous cell carcinoma (SCC) in a sample of Brazilian patients 45 years of age or less. Files from a single oral histopathological service were studied during the period 1990 to 2005 and the clinical data collected. The histological sections of the invasive part of each tumour were analysed and classified using the criteria of Bryne et al. A total of 46 patients were selected, 36 (78%) of whom were white; 38 (83%) were male; and the most common site was the floor of the mouth (n=14, 30%) followed by the tongue (n=13, 28%). Most selected patients used tobacco and alcohol, and 43 were diagnosed as having clinical stages III and IV disease. Nine of the tumours (20%) were well differentiated, 23 were moderately differentiated, and the rest (n=14) were poorly differentiated. The characteristics of this group suggest that oral SCC in young patients does not behave differently from the oral SCC found in the overall population.