Sex differences in the subcellular distribution of angiotensin type 1 receptors and NADPH oxidase subunits in the dendrites of C1 neurons in the rat rostral ventrolateral medulla.

The rostral ventrolateral medulla (RVLM), a region critical for the tonic and reflex control of arterial pressure, contains a group of adrenergic (C1) neurons that project to the spinal cord and directly modulate pre-ganglionic sympathetic neurons. Epidemiological data suggest that there are gender differences in the regulation of blood pressure. One factor that could be involved is angiotensin II signaling and the associated production of reactive oxygen species (ROS) by NADPH oxidase, which is emerging as an important molecular substrate for central autonomic regulation and dysregulation. In this study dual electron microscopic immunolabeling was used to examine the subcellular distribution of the angiotensin type 1 (AT(1)) receptor and two NADPH oxidase subunits (p47 and p22) in C1 dendritic processes, in tissue from male, proestrus (high estrogen) and diestrus (low estrogen) female rats. Female dendrites displayed significantly more AT(1) labeling and significantly less p47 labeling than males. While elevations in AT(1) labeling primarily resulted from higher levels of receptor on the plasma membrane, p47 labeling was reduced both on the plasma membrane and in the cytoplasm. Across the estrous cycle, proestrus females displayed significantly higher levels of AT(1) labeling than diestrus females, which resulted exclusively from plasma membrane density differences. In contrast, p47 labeling did not change across the estrous cycle, indicating that ROS production might reflect AT(1) receptor membrane density. No significant differences in p22 labeling were observed. These findings demonstrate that both sex and hormonal levels can selectively affect the expression and subcellular distribution of components of the angiotensin II signaling pathway within C1 RVLM neurons. Such effects could reflect differences in the capacity for ROS production, potentially influencing short term excitability and long term gene expression in a cell group which is critically involved in blood pressure regulation, potentially contributing to gender differences in the risk of cardiovascular disease.

An unusual pathologic feature associated with dermatomyositis.

We present a case of juvenile dermatomyositis with unusual histopathologic findings. The child presented with a course consistent with dermatomyositis, a diagnosis confirmed by finding reticulotubular aggregates in endothelial cells on electron microscopy. However, histopathology of his muscle biopsy revealed a striking pattern of glycogen accumulation, to an extent similar to that seen in glycogen storage diseases; this degree of accumulation could potentially confound histopathologic diagnosis.

Endoscopic thoracic sympathectomy: evaluation of pulsatile laser, non-pulsatile laser, and radiofrequency-generated thermocoagulation.

We describe a modified technique for percutaneous denervation of the thoracic sympathetic chain by laser to treat selected cases of sympathetic causalgia of the upper extremities. The technique involves transpleural ablation with laser under thoracoscopic guidance through the second or third intercostal space-anterior axillary line. We also compare four different modalities of endoscopic denervation: A xenon chloride excimer laser (308 nm, 35 mJ/pulse, 20 pulses/sec, 2.2 mm catheter tip), CO2 laser (14 W, CW, 2 mm spot size), Nd:YAG laser (88 W, CW, 3 mm spot size), and radiofrequency-generated thermocoagulation (3 W, CW, 2.1 mm catheter tip) by performing bilateral thoracic sympathectomy on 12 mongrel dogs (three dogs each). Criteria analyzed included duration of exposure, power density, total energy output, laser penetration and spread, gross morphology, and scanning electron microscopy (SEM) of the destroyed neural tissue. Total ablation of the inferior segment of the stellate ganglion and the T1-T2 nerve roots by excimer laser required 83 +/1 1 Joules over an exposure period of 118 seconds. Ablation by CO2 and Nd:YAG laser required 153 +/- 13 Joules and 554 +/- 47 Joules delivered over 11 and 6 seconds respectively. In contrast, ablation of the same volume of nerve tissue by RF required 810 +/- 50 Joules over 270 seconds. SEM evaluation revealed that excimer and CO2 laser lesions were narrower in configuration compared to RF and Nd:YAG lesions which showed more lateral spread. The actual depth of penetration per 1 second exposure was similar for Excimer and CO2 (1.5 mm) and RF (1.3 mm), but deeper for Nd:YAG (3 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Brainstem projections to lumbar motoneurons in rat--II. An ultrastructural study by means of the anterograde transport of wheat germ agglutinin coupled to horseradish peroxidase and using the tetramethyl benzidine reaction.

The descending projections from the ventrolateral medial reticular formation to the lumbar motoneuronal cell groups were studied in rat at the ultrastructural level using the anterograde transport of wheat germ agglutinin coupled to horseradish peroxidase in combination with the chromogen tetramethyl benzidine. The tissue containing the horseradish peroxidase reaction products was processed for electron microscopy using the method of chemical dehydration. In the ultrathin sections of the lumbar motoneuronal cell groups reaction products were easily recognized by their electron-dense crystal-like structure. These crystals were mostly found in terminals (66%) and to a lesser extent in axons (10%) and dendrites (10%). In the lumbar motoneuronal cell groups six different types of terminals were distinguished. It was found that F-type terminal profiles most frequently contained crystals, whereas fewer S- and G-types did so. The various findings are basically the same as those of a similar ultrastructural autoradiographic study with [3H]leucine as a tracer, except for the labelling of dendrites, which is discussed. It is concluded that the horseradish peroxidase technique employed in the present study can be reliably used for anterograde tracing at the ultrastructural level. Its advantages and disadvantages in comparison with the electron microscopical autoradiographic technique are discussed.

Peptide containing vesicles within neuro-neuronal synapses.

In the descending part of the classical neurosecretory system, the axon terminals are not differentiated or they take the form of presynaptic elements which then form synaptoids or synapses with pituicytes or adenohypophyseal glandular cells respectively. In contrast, the axon terminals of the ascending part fulfil the criteria of true presynaptic elements which form synapses with other neurones. The presence of neurophysin vesicles in the presynaptic element is a particular morphologic feature of these neuro-neuronal synapses.