John Melton

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This work documents a new method for rapid and robust Cartesian mesh generation for component-based geometry. The new algorithm adopts a novel strategy which first intersects the components to extract the wetted surface before proceeding with volume mesh generation in a second phase. The intersection scheme is based on a robust geometry engine that uses(More)
This review is a summary of the effects of brain hypoxia on respiration with a particular emphasis on those studies relevant to understanding the cellular basis of these effects. Special attention is given to mechanisms that may be responsible for the respiratory depression that appears to be the primary sequela of brain hypoxia in animal models. Although a(More)
Exposure of anesthetized paralyzed vagotomized peripherally chemodenervated cats to hypoxia results in initial depression and subsequent loss of the phrenic neurogram. To determine whether hypoxic respiratory depression results from the inhibition of respiratory premotor neurons by bulbospinal neurons of the Bötzinger complex (Böt-E neurons), extracellular(More)
We assessed the role of gamma-aminobutyric acid (GABA) as a potential causative agent of hypoxic respiratory depression by monitoring the response of the phrenic neurogram to systemic infusion of the GABA antagonist bicuculline (0.01 under control conditions and during isocapnic brain hypoxia produced by CO inhalation in separate groups of(More)
In peripherally chemodenervated, vagotomized, chloralose-anesthetized cats, hypoxia can produce central cardiorespiratory depression or excitation depending on severity. We monitored phrenic and cervical sympathetic neurograms during either hypoxic depression or gasping and 30 min of subsequent isocapnic reoxygenation to determine whether the response of(More)
Dilutional (DH) and isosmotic (IH) hyponatremia (plasma [Na+] = 103-109 meq/l) were produced in conscious rats over 3-6 h by intraperitoneal injection of water or mannitol Ringer solution. During DH, CSF [Na+], [Cl-], and osmolality decreased as predicted by passive dilution by the water load. During IH, these variables exhibited little change. Brain water(More)
Previous studies suggested that phrenic motor output is largely refractory to afferent stimuli during gasping. We tested this concept by electrically stimulating the carotid sinus nerve (CSN) or the superior laryngeal nerve (SLN) of anesthetized peripherally chemodenervated vagotomized ventilated cats during eupnea or gasping induced by hypoxia. During(More)
Acute dilutional hyponatremia (DH) (plasma [Na+] approximately equal to 110 meq/l over 3 h) was produced by intraperitoneal dialysis with distilled water in pentobarbital-anesthetized rats with either closed (SC) or open (SO) skulls. SO rats showed marked brain protrusion during DH, but the loss of brain Na+ and Cl- and gain in brain water was the same as(More)