Distribution and phenotype of Phox2a-containing neurons in the adult sprague-dawley rat.

Phox2a is a transcription factor that plays an essential role, with Phox2b, in the specification of the adrenergic and noradrenergic phenotype in developing brain. Localization of Phox2a in developing brainstem has demonstrated a high degree of correspondence between neurons expressing the transcription factor and those involved in the regulation of autonomic function. Although it is well established that the paralogous gene product Phox2b is widely expressed in adult brain, no study has mapped the distribution of Phox2a in the adult.

Distribution of hypothalamic neurons with orexin (hypocretin) or melanin concentrating hormone (MCH) immunoreactivity and multisynaptic connections with diaphragm motoneurons.

Prior work showed that neurons in the lateral, dorsal, and perifornical regions of the tuberal and mammillary levels of the hypothalamus participate in the control of breathing. The same areas also contain large numbers of neurons that produce either orexins (hypocretins) or melanin concentrating hormone (MCH). These peptides have been implicated in regulating energy balance and physiological changes that occur in transitions between sleep and wakefulness, amongst other functions.

Localization of serotoninergic neurons that participate in regulating diaphragm activity in the cat.

Although a considerable body of literature indicates that serotoninergic neurons affect diaphragm activity both through direct inputs to phrenic motoneurons and multisynaptic connections involving the brainstem respiratory groups, the locations of the serotoninergic neurons that modulate breathing have not been well defined. The present study identified these neurons in cats by combining the transneuronal retrograde transport of rabies virus from the diaphragm with the immunohistochemical detection of the N-terminal region of tryptophan hydroxylase-2 (TPH2), the brain-specific isoform of the enzyme responsible for the initial and rate-limiting step in serotonin synthesis. TPH2-immunopositive neurons were present in the midline raphe nuclei, formed a column in the ventrolateral medulla near the lateral reticular nucleus, and were spread across the dorsal portion of the pons just below the fourth ventricle.

Neural circuits controlling diaphragm function in the cat revealed by transneuronal tracing.

Although a number of studies have considered the neural circuitry that regulates diaphragm activity, these pathways have not been adequately discerned, particularly in animals such as cats that utilize the respiratory muscles during a variety of different behaviors and movements. The present study employed the retrograde transneuronal transport of rabies virus to identify the extended neural pathways that control diaphragm function in felines. In all animals deemed to have successful rabies virus injections into the diaphragm, large, presumed motoneurons were infected in the C(4)-C(6) spinal segments.

Development of a hinge compatible with the kinematics of the knee joint.

This study aims to present a new concept of a knee hinge based on a crossed four-bar linkage mechanism which has been designed to optimally follow a motion curve representing the knee kinematics in the position at which the knee hinge should be placed. The methodology used to determine the optimal knee hinge is based on the optimization of certain variables of the crossed four-bar mechanism using genetic algorithms in order to follow a certain motion curve, which was determined using a biomechanical model of the knee motion. Two current, commercially available knee hinges have been used to theoretically determine their motion by means of the path performed by their instantaneous helical axis.