The Impact of Prior Season Vaccination on Subsequent Influenza Vaccine Effectiveness to Prevent Influenza-related Hospitalizations Over 4 Influenza Seasons in Canada.

BACKGROUND: Recent studies have demonstrated the possibility of negative associations between prior influenza vaccines and subsequent influenza vaccine effectiveness (VE), depending on season and strain. We investigated this association over 4 consecutive influenza seasons (2011-2012 through 2014-2015) in Canada. METHODS: Using a matched test-negative design, laboratory-confirmed influenza cases and matched test-negative controls admitted to hospitals were enrolled. Patients were stratified into 4 groups according to influenza vaccine history (not vaccinated current and prior season [referent], vaccinated prior season only, vaccinated current season only, and vaccinated both current and prior season). Conditional logistic regression was used to estimate VE; prior vaccine impact was assessed each season for overall effect and effect stratified by age (<65 years, ≥65 years) and type/subtype (A/H1N1, A/H3N2, influenza B). RESULTS: Overall, mainly nonsignificant associations were observed. Trends of nonsignificant decreased VE among patients repeatedly vaccinated in both prior and current season relative to the current season only were observed in the A/H3N2-dominant seasons of 2012-2013 and 2014-2015. Conversely, in 2011-2012, during which B viruses circulated, and in 2013-2014, when A/H1N1 circulated, being vaccinated in both seasons tended to result in a high VE in the current season against the dominant circulating subtype. CONCLUSIONS: Prior vaccine impact on subsequent VE among Canadian inpatients was mainly nonsignificant. Even in circumstances where we observed a trend of negative impact, being repeatedly vaccinated was still more effective than not receiving the current season's vaccine. These findings favor continuation of annual influenza vaccination recommendations, particularly in older adults. CLINICAL TRIALS REGISTRATION: NCT01517191.

Interim estimates of 2013/14 influenza clinical severity and vaccine effectiveness in the prevention of laboratory-confirmed influenza-related hospitalisation, Canada, February 2014.

During the 2013/14 influenza season in Canada, 631 of 654 hospitalisations for laboratory-confirmed influenza enrolled in sentinel hospitals were due to Influenza A. Of the 375 with known subtype, influenza A(H1N1) accounted for 357. Interim unmatched vaccine effectiveness adjusted for age and presence of one or more medical comorbidities was determined by test-negative case-control design to be 58.5% (90% confidence interval (CI): 43.9-69.3%) overall and 57.9% (90% CI: 37.7-71.5) for confirmed influenza A(H1N1).

Valproic acid in association with highly active antiretroviral therapy for reducing systemic HIV-1 reservoirs: results from a multicentre randomized clinical study.

OBJECTIVES: Conflicting results have been reported regarding the ability of valproic acid (VPA) to reduce the size of HIV reservoirs in patients receiving suppressive highly active antiretroviral therapy (HAART). In a randomized multicentre, cross-over study, we assessed whether adding VPA to stable HAART could potentially reduce the size of the latent viral reservoir in CD4 T cells of chronically infected patients. METHODS: A total of 56 virologically suppressed patients were randomly assigned either to receive VPA plus HAART for 16 weeks followed by HAART alone for 32 weeks (arm 1; n = 27) or to receive HAART alone for 16 weeks and then VPA plus HAART for 32 weeks (arm 2; n = 29). VPA was administered at a dose of 500 mg twice a day (bid) and was adjusted to the therapeutic range. A quantitative culture assay was used to assess HIV reservoirs in CD4 T cells at baseline and at weeks 16 and 48. RESULTS: No significant reductions in the frequency of CD4 T cells harbouring replication-competent HIV after 16 and 32 weeks of VPA therapy were observed. In arm 1, median (range) values of IU per log(10) billion (IUPB) cells were 2.55 (range 1.20-4.20), 1.80 (range 1.0-4.70) and 2.70 (range 1.0-3.90; P = 0.87) for baseline, week 16 and week 48, respectively. In arm 2, median values of IUPB were 2.55 (range 1.20-4.65), 1.64 (range 1.0-3.94) and 2.51 (range 1.0-4.48; P = 0.50) for baseline, week 16 and week 48, respectively. CONCLUSIONS: Our study demonstrates that adding VPA to stable HAART does not reduce the latent HIV reservoir in virally suppressed patients.

Design and implementation of a randomized crossover study of valproic acid and antiretroviral therapy to reduce the HIV reservoir.

BACKGROUND: HIV reservoirs represent the major obstacles for eradication and are defined as a cell type that allows persistence of replication-competent HIV in patients on optimal long-term antiretroviral therapy (HAART). Several pilot clinical trials have been implemented to assess the value of experimental therapy to reduce reservoir size or eradicate HIV. In order to eradicate HIV, valproic acid was used as a new strategy to increase viral gene expression in the nucleus of infected cells with the expectation of generating a direct cell death or destruction by nearby cytotoxic cells. Previous pilot studies using VPA have showed conflicting results on the ability of VPA to reduce the size of HIV reservoirs. PURPOSE: As the role of VPA on HIV reservoirs remains unclear, we conducted a multicenter clinical trial with a specific study design to obtain optimal information on reservoir changes while exposing the smallest number of individuals to the experimental medication. METHOD: To this aim, a randomized, crossover design with 2 different treatment durations was implemented. By doubling the therapeutic period in one study arm, we were in a position to assess the impact of an extended duration of VPA on the size of the HIV reservoir and to evaluate the duration of treatment effects upon VPA withdrawal in the other arm. However, limitations for this type of study design included the logistical complexity of 2 uneven study arms and longer study duration. CONCLUSION: Despite the absence of demonstrable impact of VPA on reservoir size, such crossover study design should be considered in the early stage testing of novel HIV therapeutics targeted to reduce reservoir size or eradicate HIV.

Validation of the Seegene RV15 multiplex PCR for the detection of influenza A subtypes and influenza B lineages during national influenza surveillance in hospitalized adults.

Background. The Serious Outcomes Surveillance Network of the Canadian Immunization Research Network (CIRN SOS) has been performing active influenza surveillance since 2009 (ClinicalTrials.gov identifier: NCT01517191). Influenza A and B viruses are identified and characterized using real-time reverse-transcriptase polymerase chain reaction (RT-PCR), and multiplex testing has been performed on a subset of patients to identify other respiratory virus aetiologies. Since both methods can identify influenza A and B, a direct comparison was performed.Methods. Validated real-time RT-PCRs from the World Health Organization (WHO) to identify influenza A and B viruses, characterize influenza A viruses into the H1N1 or H3N2 subtypes and describe influenza B viruses belonging to the Yamagata or Victoria lineages. In a subset of patients, the Seeplex RV15 One-Step ACE Detection assay (RV15) kit was also used for the detection of other respiratory viruses.Results. In total, 1111 nasopharyngeal swabs were tested by RV15 and real-time RT-PCRs for influenza A and B identification and characterization. For influenza A, RV15 showed 98.0 % sensitivity, 100 % specificity and 99.7 % accuracy. The performance characteristics of RV15 were similar for influenza A subtypes H1N1 and H3N2. For influenza B, RV15 had 99.2 % sensitivity, 100 % specificity and 99.8 % accuracy, with similar assay performance being shown for both the Yamagata and Victoria lineages.Conclusions. Overall, the detection of circulating subtypes of influenza A and lineages of influenza B by RV15 was similar to detection by real-time RT-PCR. Multiplex testing with RV15 allows for a more comprehensive respiratory virus surveillance in hospitalized adults, without significantly compromising the reliability of influenza A or B virus detection.

[On the best strategies on the best results for surgery of frontal epilepsy]. / Quelles stratégies pour quels résultats dans la chirurgie des épilepsies partielles frontales?

Frontal lobe epilepsy surgery is the second most common surgery performed for drug-resistant partial epilepsy. We investigated the longitudinal outcome in a cohort of patients investigated since 1990 with SEEG and modern diagnostic techniques. We reviewed 105 patients who underwent surgery between 1990 and 2005 (mean follow-up, six years; range: one to 17 years) and analyzed the year-per-year follow-up according to Engel's classification. Favorable outcome (Class I) was observed for 70% and this result was stable at least five years after surgery. More than 90% of patients with lesion-related epilepsies (focal cortical dysplasia and dysembryoplastic neuroepithelial tumors) became seizure-free. Less than 50% of patients classified as having cryptogenic epilepsy (defined as normal imaging and neuropathology on surgical specimen) had a favorable outcome. Permanent neurological sequelae were subtle and rare, especially after surgery for dysplasia in eloquent cortex (primary motor cortex). Our data indicate that frontal surgery is a successful treatment in patients when electrophysiological and morphological investigations demonstrate a well-defined epileptogenic zone or lesion to be surgically resected. Progress in electrophysiological and brain-imaging techniques will further improve the selection of frontal lobe epilepsy surgery candidates.

[Cellular mechanisms of the epilepsies: In vitro studies on human tissue]. / Etudes in vitro sur tissu humain des mécanismes cellulaires des épilepsies.

BACKGROUND AND PURPOSE: Animal models have provided very valuable data to specify the physiopathological mechanisms of the various forms of epilepsy. However, the question arises of knowing which of these experimental results are relevant to the human epileptic brain. The development of epileptic surgery makes it possible to directly study the functional properties of human brain tissue in vitro and to analyze the mechanisms underlying seizures and epileptogenesis. We review some of the results obtained over the last few years in our laboratory based on electrophysiological, immunocytochemical and molecular experiments conducted on human brain tissue. RESULTS: This review covers a number of the mechanisms of neuronal synchronizations generating epileptiform discharges, including the role of electrical synapses connecting the inhibitory interneurons, particularly in Taylor-type focal cortical dysplasia and the functional lability of GABAergic inhibition in epileptogenic human cortical tissue, which may sustain triggering and propagation of seizures. Some of these mechanisms have not been described in animal models. CONCLUSIONS: Studies on human tissue, when carefully designed, are necessary to validate the data collected on animal models and will continue to provide us with new and important information on the cerebral changes related to epilepsy. Moreover, these studies allow development of a class of antiepileptic drugs that have a completely new mechanism of action, which could be effective in the treatment of drug-resistant epilepsies.

A community randomized controlled clinical trial of mixed carotenoids and micronutrient supplementation of patients with acquired immunodeficiency syndrome.

OBJECTIVE: This clinical trial aims to evaluate if natural mixed carotenoids supplementation can improve the health and survival of acquired immunodeficiency syndrome (AIDS) patients. DESIGN: A placebo-controlled, prospective, randomized, double-blind, multicenter clinical trial. SETTING: Community, tertiary care human immunodeficiency virus (HIV) clinics of the Canadian HIV Trials Network (CTN). PARTICIPANTS: Three hundred and thirty-one adults with advanced AIDS on conventional management were recruited during routine clinic visits. INTERVENTIONS: All participants, including 166 controls, received daily oral specially formulated multivitamins including vitamin A and trace elements; 165 treatment group participants received additional daily oral natural mixed carotenoids, equivalent to 120,000 IU (72 mg) of beta-carotene daily. Follow-up was quarterly at routine clinic visits. RESULTS: Mean (s.d.) follow-up was for 13 (6) months. Thirty-six participants died by 18 months. Serum carotene concentration <1.0 micromol/l was present in 16% participants at baseline. Despite variation in carotene content of the treatment medication, serum carotene concentrations increased significantly to twice the baseline levels to 18 months follow-up in participants who received carotenoids treatment compared with controls (P < 0.0001). Although not statistically significant, mortality was increased in participants who did not receive carotenoids treatment compared with those who did (HR time to death 1.76, 95% CI 0.89, 3.47, P = 0.11). In multivariate analysis, survival was significantly and independently improved in those with higher baseline serum carotene concentrations (P = 0.04) or higher baseline CD4 T-lymphocyte counts (P = 0.005). Adjusted mortality was also significantly and independently increased in those who did not receive carotenoids treatment compared with those who did (HR time to death 3.15, 95% CI 1.10, 8.98, P = 0.03). CONCLUSIONS: Low serum carotene concentration is common in AIDS patients and predicts death. Supplementation with micronutrients and natural mixed carotenoids may improve survival by correction of a micronutrient deficiency. Further studies are needed to corroborate findings and elucidate mechanism of action.

Regional and laminar distribution of the dopamine and serotonin innervation in the macaque cerebral cortex: a radioautographic study.

The regional density and laminar distribution of dopamine (DA) and serotonin (5-HT) afferents were investigated in the cerebral cortex of cynomolgus monkeys using a radioautographic technique that is based on the high affinity uptake capacity of these aminergic neurons. Large vibratome sections, 50 micron thick, were incubated with [3H] DA (0.2 microM) and desipramine (5 microM) or with unlabeled norepinephrine (5 microM) and [3H] 5-HT (0.6 microM), which allowed for the specific labeling of the DA and 5-HT innervations, respectively. After fixation, these sections were dried, defatted, and radioautographed by dipping. Semiquantitative data on the DA innervation also were provided by counting [3H] DA-labeled axonal varicosities in radioautographs from 4-micron-thick sections of the slices obtained after epon embedding. The DA innervation was widespread and differed in density and laminar distribution in the agranular and granular cortices. DA afferents were densest in the anterior cingulate (area 24) and the motor areas (areas 4, 6, and supplementary motor area [SMA]). In the latter they displayed a trilaminar pattern of distribution, predominating in layers I, IIIa, and V-VI, with characteristic cluster-like formations in layer IIIa, especially in the medial part of motor areas. In the granular prefrontal (areas 46, 9, 10, 11, 12), parietal (areas 1, 2, 3, 5, 7), temporal (areas 21, 22), and posterior cingulate (area 23) cortices, DA afferents were less dense and showed a bilaminar pattern of distribution, predominating in the depth of layer I and in layers V-VI; density in layers II, III, and IV was only 20% of that in layer I. The lowest density was in the visual cortex, particularly in area 17, where the DA afferents were almost restricted to layer I. The density of 5-HT innervation was generally greater than that of DA except in the motor areas and in the anterior cingulate cortex. Region-specific laminar patterns characterized (1) motor areas where a lower density in layer III contrasted with the clusters of DA axons in the same layer; (2) the primary visual cortex (area 17), where two bands of higher density in layers III-IV and layer V outlined a poorly innervated zone in layer IVc-beta; (3) the peristriate area 18, where the 5-HT network was relatively loose but with a denser band in layer III. Thus, DA innervation of the cerebral cortex displays major differences between rodents and primates, characterized by expanded cortical targets and by a highly differentiated laminar distribution.(ABSTRACT TRUNCATED AT 400 WORDS)

The proprotein convertase PC2 is involved in the maturation of prosomatostatin to somatostatin-14 but not in the somatostatin deficit in Alzheimer's disease.

A somatostatin deficit occurs in the cerebral cortex of Alzheimer's disease patients without a major loss in somatostatin-containing neurons. This deficit could be related to a reduction in the rate of proteolytic processing of peptide precursors. Since the two proprotein convertases (PC)1 and PC2 are responsible for the processing of neuropeptide precursors directed to the regulated secretory pathway, we examined whether they are involved first in the proteolytic processing of prosomatostatin in mouse and human brain and secondly in somatostatin defect associated with Alzheimer's disease. By size exclusion chromatography, the cleavage of prosomatostatin to somatostatin-14 is almost totally abolished in the cortex of PC2 null mice, while the proportions of prosomatostatin and somatostatin-28 are increased. By immunohistochemistry, PC1 and PC2 were localized in many neuronal elements in human frontal and temporal cortex. The convertases levels were quantified by Western blot, as well as the protein 7B2 which is required for the production of active PC2. No significant change in PC1 levels was observed in Alzheimer's disease. In contrast, a marked decrease in the ratio of the PC2 precursor to the total enzymatic pool was observed in the frontal cortex of Alzheimer patients. This decrease coincides with an increase in the binding protein 7B2. However, the content and enzymatic activity of the PC2 mature form were similar in Alzheimer patients and controls. Therefore, the cortical somatostatin defect is not due to convertase alteration occuring during Alzheimer's disease. Further studies will be needed to assess the mechanisms involved in somatostatin deficiency in Alzheimer's disease.

Utilization of venous thromboembolism prophylaxis in a medical-surgical ICU.

STUDY OBJECTIVE: To assess the utilization of venous thromboembolism (VTE) prophylaxis in a medical-surgical ICU. DESIGN: Prospective cohort study. SETTING: A closed (mandatory critical care consult) medical-surgical ICU of a large community teaching hospital. INTERVENTIONS: The medical records of consecutive medical-surgical ICU admissions were evaluated by a single investigator during a 3-month period. Risk factors for VTE and the type and timing of VTE prophylaxis were recorded. MEASUREMENTS AND RESULTS: Of 308 admissions evaluated, 209 were included in the study. VTE prophylaxis was administered within the first 24 h of ICU admission to 179 of the 209 study patients or 86%. Fifty-three percent (n=111) were surgical patients and 47% (n=98) were medical patients. The study patients had an average of 4.4 risk factors for VTE. Thirty study patients (14%) did not receive VTE prophylaxis. CONCLUSION: Eighty-six percent of the medical-surgical patients included in this study received VTE prophylaxis. The utilization of VTE prophylaxis described in this study is higher compared to previously published data. The nature of physician coverage in our medical-surgical ICU (closed unit), consistent practice patterns of a designated ICU staff, and a continuing medical education program involving VTE prophylaxis are the factors believed to be responsible for these results.

Validation of an inexpensive B-mode ultrasound device for detection of deep vein thrombosis.

OBJECTIVE: To validate a portable, inexpensive, real-time, B-mode ultrasound device compared with duplex ultrasound in the detection of proximal lower extremity deep vein thrombosis in hospitalized patients clinically suspected of having deep vein thrombosis. DESIGN: Prospective cohort study. SETTING: Tertiary care community teaching hospital. PATIENTS: Medical-surgical hospitalized patients undergoing duplex ultrasonography for clinically suspected lower extremity deep vein thrombosis. INTERVENTIONS: Hospitalized patients who underwent duplex ultrasound examinations were enrolled in the study. Blinded from the duplex ultrasound results, the investigators utilized the study ultrasound device to perform compression ultrasonography of the common femoral, superficial femoral, and popliteal veins within 48 h of the duplex examinations. The results of the study ultrasound device were recorded as normal (compressible) or abnormal (noncompressible). RESULTS: Of the 198 lower limbs evaluated, duplex ultrasonography documented 34 proximal lower extremity deep vein thrombi. The study ultrasound device detected 32 of the 34 proximal thrombi detected by duplex ultrasonography. One false-positive result of an examination occurred with the study ultrasound device. Compared with duplex ultrasonography, the study ultrasound device had a sensitivity of 94%, specificity of 99%, positive predictive value of 97%, and negative predictive value of 98%. CONCLUSIONS: The results of this investigation document that the study ultrasound device has an acceptable sensitivity, specificity, and diagnostic accuracy for clinical use in detection of proximal lower extremity deep vein thrombosis. Further evaluation and validation of this ultrasound device are warranted.

Posterior tracheal wall perforation during percutaneous dilational tracheostomy: an investigation into its mechanism and prevention.

OBJECTIVES: Part 1: To describe the complication of posterior tracheal wall injury and perforation associated with the percutaneous dilational tracheostomy (PDT). Part 2: To determine the mechanism of posterior tracheal wall injury during PDT. DESIGN: Prospective observational study. SUBJECTS: Part 1: Medical-surgical ICU patients requiring tracheostomy. Part 2: Swine and cadaver models. INTERVENTIONS: Part 1: Consecutive medical-surgical ICU patients undergoing tracheostomy tube insertion via the percutaneous dilation technique with bronchoscopic guidance were enrolled in the study. Demographic data and complications were recorded. Part 2: Tracheostomy tubes were inserted via the percutaneous dilational technique in the swine model with concomitant bronchoscopic video recording from the proximal and distal airways. Tracheostomy tubes were inserted via the percutaneous dilational technique in the cadaver model followed by anatomic inspection of the airway. RESULTS: Part 1: Seven (29%) of 24 medical-surgical ICU patients sustained complications associated with PDT. Three patients (12.5%) sustained posterior tracheal wall perforations followed by the development of tension pneumothoraces. Part 2: The swine model demonstrated that posterior tracheal wall perforation may occur during PDT when the guiding catheter is withdrawn into the dilating catheters. Five-centimeter posterior tracheal wall mucosal lacerations occurred when the guidewire and the guiding catheter were not properly stabilized during PDT. CONCLUSION: Percutaneous dilational tracheostomy was associated with a 29% complication rate in this observational study. Of concern was the high rate (12.5%) of posterior tracheal wall perforation. The swine and cadaver models suggest that posterior tracheal wall injury or perforation may occur if the guidewire and guiding catheter are not properly stabilized. To avoid posterior tracheal wall injury, the guidewire and guiding catheter should be firmly stabilized during PDT.

Haemophilus influenzae causing conjunctivitis in day-care children.

The role of Haemophilus influenzae in acute purulent conjunctivitis was studied during an outbreak among children in day care. Five day-care centers contributed 20 cases and 35 controls. All the children were subjected to culture of the nasopharynx and the eyes. H. influenzae was carried in the nasopharynx of 53% of the children (range between day care centers, 20 to 91%). Of the 20 children with acute conjunctivitis 8 had eye cultures positive for H. influenzae, 2 had Moraxella and the remaining were culture-negative. Ten colonies of H. influenzae were isolated from each positive culture and identified by capsular type, biotype and multi-locus enzyme electrophoresis. All but one of the isolates were nonencapsulated. They belonged to 4 biotypes and 8 electrophoretic types. The same strain was recovered from the eyes and nasopharynx of the symptomatic children, suggesting that the H. influenzae in the eyes originated from the nasopharynx. There was no evidence for spread of the same H. influenzae strains between day-care centers. Even within each center the Haemophilus strains recovered from the eyes varied among the symptomatic children. The in vitro capacity to attach to oropharyngeal epithelial cells was not increased among the H. influenzae recovered from the eyes. The results question if the majority of conjunctivitis cases were caused by H. influenzae and suggested that eyes were colonized with the nasopharyngeal carrier strain rather than infected by an isolate with special virulence for the eye.

Facilitation of focal cobalt-induced epilepsy after lesions of the noradrenergic locus coeruleus system.

In this study we analyzed the electrophysiological and clinical effects of selective removal of the forebrain noradrenergic projection from the locus coeruleus, induced by bilateral injections of 6-hydroxydopamine into the dorsal tegmental bundle on focal cobalt-induced epilepsy. Noradrenaline depletion caused a marked potentiation of the epilepsy by increasing the duration and intensity of both the clinical and electrophysiological epileptic parameters: epileptic discharges and myoclonic jerks started earlier; spiking and clinical activity were facilitated; duration of the epileptic syndrome was prolonged. On the basis of the present and previous results it is proposed that the ascending noradrenergic system plays a modulatory role on the spread of paroxysmal activities and on the severity of cobalt-induced epilepsy.

Co-localization of histamine with GABA but not with galanin in the human tuberomamillary nucleus.

The presence of GABA and galanin in histaminergic neurons was previously reported in the rodent brain but whether such co-localizations also occur in the human brain was not known. We used in situ hybridization histochemistry and immunohistochemistry to study the co-localization of histamine with GABA and galanin in neurons of the tuberomamillary nucleus of adult human posterior hypothalamus. On consecutive formalin-fixed paraffin-embedded sections, co-localization was assessed using the in situ hybridization for L-histidine decarboxylase mRNA and immunocytochemistry for glutamate decarboxylase-67 kDa or galanin in the two profiles of same cell. The pattern of distribution and number of histaminergic neurons identified by in situ hybridization of the synthesizing enzyme gene transcripts were in accordance with data reported for histamine immunoreactivity. The great majority of neurons within the main divisions of the tuberomamillary nucleus containing L-histidine decarboxylase mRNA was also immunoreactive for glutamate decarboxylase-67 kDa. The range of co-localization of the two markers varied from 72% in the lateral part, to 75-87% in the medial part and 83-88% in the ventral part. In contrast, no cell containing L-histidine decarboxylase mRNA was immunoreactive for galanin. We conclude that tuberomamillary neurons in human co-express histamine with GABA but, unlike the neurons in rodents, do not express galanin, indicating that neurotransmitter co-localization patterns differ in the two species.

Alterations of noradrenaline and serotonin uptake and metabolism in chronic cobalt-induced epilepsy in the rat.

The high affinity uptake of noradrenaline and serotonin, and the concentrations of these monoamines and their metabolites, have been measured in the perifocal cortical area at various stages of the evolution of cobalt-induced epilepsy in the rat. Noradrenaline uptake was maximally reduced at days 8-10 after cortical cobalt application, a time corresponding to the onset of epileptic discharges; it remained diminished during the spiking activity period of the focus (days 14-20) and was back to normal values at day 40, at which time the epileptic syndrome had disappeared. Serotonin uptake was also diminished at days 8-10 but to a lesser extent than was noradrenaline uptake. In the homotopic cerebral cortex contralateral to cobalt application, noradrenaline uptake was reduced at day 10 only and to a lesser extent than in the perifocal area, whereas serotonin uptake was unaffected. Kinetic analysis of the cobalt-induced monoamine uptake alterations at day 10 revealed a diminution of the maximal velocity with no change in the Km. Noradrenaline and dihydroxyphenylethyleneglycol concentrations in the perifocal area were also maximally reduced at days 8-10 but were unaffected at day 2 and day 40 post cobalt application. A reduction of serotonin levels in the perifocal area was observed only at days 8-10 while 5-hydroxyindoleacetic acid remained unaffected throughout the time period studied. The levels of these monoamines and their metabolites were unchanged in the homotopic contralateral cortex 2-40 days after cobalt application. These results indicate that cortical cobalt application induces alterations of the biochemical indices of the density of noradrenaline-containing terminals that closely parallel the evolution of the epileptic syndrome. These data further emphasize the important role of the cortical noradrenergic system in cobalt-induced epilepsy.

Immunocytochemical localization and morphology of GABA-containing neurons in the prefrontal and frontoparietal cortex of the rat.

The distribution and morphology of gamma-aminobutyric acid (GABA)-containing neurons in the rat prefrontal, frontal and parietal cortex were examined using a specific polyclonal antiserum directed against GABA and the immunoperoxidase method. The reaction product was present in the cell bodies, as well as in terminals and some processes without using colchicine. The immunoreactive neurons were observed in all layers but their laminar distribution was different in each cortical area. The immunoreactive cells were more numerous: in layer II and layer V-VI of the frontal cortex, in the deep layers (IV, V, VI) of the parietal cortex and in layer II and layer VI of the prefrontal cortex. The neurons displaying a labelling both in perikarya and processes were classified as multipolar and bipolar neurons. We distinguished various subtypes in each category. Multipolar neurons: cells with a large round soma and thin dendrites radiating in all directions; small neurons with ovoid or angular soma; large neurons with multiangular soma; neurons with a piriform soma. Bipolar neurons: horizontal bipolar cells with ovoid soma and vertical bipolar neurons with fusiform soma.

Co-localization of tyrosine hydroxylase and GABA immunoreactivities in human cortical neurons.

Samples of human cerebral cortex were stained immunocytochemically for tyrosine hydroxylase (TH) and gamma-aminobutyric acid (GABA). TH-positive neurons were in small number and predominated in the deep infragranular layers V-VI contrasting with numerous GABA-positive neurons scattered in all layers. Co-localization of TH- and GABA-like immunoreactivities in a single cell was studied by the double immunolabeling technique with the elution-restaining procedure. Only 50% of the TH-positive neurons also expressed GABA-like immunoreactivities. The two markers were detectable in the somata and not in the processes of the cells. The double-labeled cells were mainly fusiform and medium-sized and were observed in layer VI. These observations suggest that the TH-positive cells form a mixed neuronal population, only a part of which corresponds to the GABAergic class of intrinsic interneurons.

Major dopamine innervation of the cortical motor areas in the cynomolgus monkey. A radioautographic study with comparative assessment of serotonergic afferents.

Dopamine (DA) and serotonin (5-HT) innervations were revealed by radioautography in primary motor, premotor and supplementary motor (SMA) cortex in Cynomolgus monkeys, using uptake of tritiated amines in vibratome sections under specific conditions that were previously established. DA and 5-HT axons were distributed throughout all cortical layers. A denser DA innervation was found in layers I, III and to a lesser extent layer V with a striking cluster-like arrangement in layer III, particularly in the SMA. 5-HT axons appeared less numerous; their lower density in comparison with DA axons was especially apparent in layer III, particularly in the premotor and motor areas. A DA-5-HT complementarity was thus suggested in this layer. These results suggest that in addition to the motor control exerted through the nigrostriatal pathway, the cortical DA projections could directly modulate the neuronal activity in motor areas. This could be of major importance in the pathophysiology of motor disorders such as Parkinson's disease.