Atypical features of rat dentate granule cells: recurrent basal dendrites and apical axons.

The stereotyped morphology of dentate granule cells in rodents consists of apical dendrites arborizing in the molecular layer and an axon arising from the opposite pole of the soma. Recently, we showed that epilepsy induces the formation of basal dendrites on granule cells and that these dendrites extend into the hilus of the dentate gyrus. The present Golgi study of granule cells from adult rats shows two atypical features for granule cells in control rats. One is the occurrence of recurrent basal dendrites (RBDs) that are defined as basal dendrites arising at or near the hilar pole of the soma and then curving back to the molecular layer. The frequency of granule cells with RBDs was 3.8% in control rats. The second is apical axons of granule cells that were observed to originate from either the apical pole of the soma or an apical dendrite. The incidence of these "apical" axons was about 1%. These morphological findings in the present study suggest that rat granule cells are more heterogeneous than previously indicated. Furthermore, their frequency was not increased in epileptic rats

Ultrastructural features and synaptic connections of hilar ectopic granule cells in the rat dentate gyrus are different from those of granule cells in the granule cell layer.

Several investigators have shown the existence of dentate granule cells in ectopic locations within the hilus and molecular layer using both Golgi and retrograde tracing studies but the ultrastructural features and synaptic connections of ectopic granule cells were not previously examined. In the present study, the biocytin retrograde tracing technique was used to label ectopic granule cells following injections into stratum lucidum of CA3b of hippocampal slices obtained from epileptic rats. Electron microscopy was used to study hilar ectopic granule cells that were located 20-40 microm from the granule cell layer (GCL). They had ultrastructural features similar to those of granule cells in the GCL but showed differences, including nuclei that often displayed infoldings and thicker apical dendrites. At their origin, these dendrites were 6 microm in diameter and they tapered down to 2 microm at the border with the GCL. Both biocytin-labeled and unlabeled axon terminals formed exclusively asymmetric synapses with the somata and proximal dendrites of hilar ectopic granule cells. The mean number of axosomatic synapses for these cells was three times that for granule cells in the GCL. Together, these data indicate that hilar ectopic granule cells are postsynaptic to mossy fibers and have less inhibitory input on their somata and proximal dendrites than granule cells in the GCL. This finding is consistent with recent physiological results showing that hilar ectopic granule cells from epileptic rats are more hyperexcitable than granule cells in the GCL

Venular basement membranes contain specific matrix protein low expression regions that act as exit points for emigrating neutrophils.

Published versio

Gender- and age-related differences in clinical presentation and management of outpatients with stable coronary artery disease

<br>Introduction: Contemporary generalizable data on the demographics and management of outpatients with stable coronary artery disease (CAD) in routine clinical practice are sparse. Using the data from the CLARIFY registry we describe gender- and age-related differences in baseline characteristics and management of these patients across broad geographic regions.</br> <br>Methods: This international, prospective, observational, longitudinal registry enrolled stable CAD outpatients from 45 countries in Africa, Asia, Australia, Europe, the Middle East, and North, Central, and South America.</br> <br>Results: Baseline data were available for 33 280 patients. Mean (SD) age was 64 (10.5) years and 22.5% of patients were female. The prevalence of CAD risk factors was generally higher in women than in men. Women were older (66.6 vs 63.4 years), more frequently diagnosed with diabetes (33% vs 28%), hypertension (79% vs 69%), and higher resting heart rate (69 vs 67 bpm), and were less physically active. Smoking and a history of myocardial infarction were more common in men. Women were more likely to have angina (28% vs 20%), but less likely to have undergone revascularization procedures. CAD was more likely to be asymptomatic in older patients perhaps because of reduced levels of physical activity. Prescription of evidence-based medication for secondary prevention varied with age, with patients ≥ 75 years treated less often with beta blockers, aspirin and angiotensin-converting enzyme inhibitors than patients < 65 years.</br> <br>Conclusions: Important gender-related differences in clinical characteristics and management continue to exist in all age groups of outpatients with stable CAD.</br&gt

Parasitic Oscillations in Smooth-Wall Circular Symmetric Gyrotron Beam Ducts

In order to study parasitic oscillation that may occur in a realistic beam duct upstream to the gyrotron cavity, the self-consistent linear and spectral code TWANGlinspec has been modified. The large inhomogeneities in the smooth-wall beam duct geometry or in the magnetic field profile required the implementation of a numerical approach using a hybrid finite element method. The new model permits to characterize a large number of potentially spurious TE modes. Compared to previous studies on gyrotron beam duct instabilities, an extended interaction space including also the gyrotron cavity has been considered. The role of the connecting part between the beam duct and the cavity, called spacer, is highlighted and it is shown that the gyro backward-wave TE modes excited in this region generally have their minimum starting current. The sensitivity of the minimum starting current on electron beam velocity spread is also evaluated

Novel linear analysis for a gyrotron oscillator based on a spectral approach

With the aim of gaining a better physical insight into linear regimes in gyrotrons, a new linear model was developed. This model is based on a spectral approach for solving the self-consistent system of equations describing the wave-particle interaction in the cavity of a gyrotron oscillator. Taking into account the wall-losses self-consistently and including the main system inhomogeneities in the cavity geometry and in the magnetic field, the model is appropriate to consider real system parameters. The main advantage of the spectral approach, compared with a time-dependent approach, is the possibility to describe all of the stable and unstable modes, respectively, with negative and positive growth rates. This permits to reveal the existence of a new set of eigenmodes, in addition to the usual eigenmodes issued from cold-cavity modes. The proposed model can be used for studying other instabilities such as, for instance, backward waves potentially excited in gyrotron beam tunnels

Start-up scenario studies in gyrotron oscillator using a novel linear and spectral code

A linear and spectral model has recently been developed [1], describing the self-consistent wave-particle interaction in a gyrotron oscillator. The spectral approach, compared to commonly used time-evolution approaches, has the possibility to describe all of the stable and unstable modes, respectively, with negative and positive growth rates. Moreover, this approach is numerically efficient and thus appropriate for parameter scans or start-up scenario studies. The model has been successfully benchmarked against real experiments for gyrotron cavity interaction, in particular concerning start-up scenario studies. In order to study backward-wave instabilities in smooth-wall beam ducts, the numerical model has been recently extended to include a higher order finite element discretization. The model, its numerical implementation and simulation results for high power gyrotrons as well as first results for smooth-wall beam ducts will be presented