Effects of hypercapnea and of hypercapnea in combination with hypoxia on midbrain-induced cardiac dysrhythmias

Stimulation of the midbrain during acute combined arterial hypoxia and hypercapnea produces serious cardiac dysrhythmias which are not evoked when stimulation is elicited either with normal arterial blood gas tensions or with isolated mild hypercapnea. The cardiac dysrhythmias are mediated by both enhanced sympathetic and parasympathetic efferent discharge. The results support the concept that increased autonomic activity in combination with acute arterial hypoxia and hypercapnea contribute significantly to the exhibition of serious cardiac rhythm disturbances. Acute hypoxia appears to be the major determinant of such dysrhythmias.     

The role of cellular degeneration in the normal development of (rat) otocyst

From day 12 to 16 of gestation a highly circumscribed zone of cellular degeneration has been observed in the otocyst of more than 50 normal rats. This zone appears to be produced by selective or programmed cell death, and results in the elimination of unneeded cellular elements. That cells in this zone are also selectively destroying subcellular organelles as a first step in specialization is also discussed. Programmed cellular death has long been known in other systems and is often an obligatory companion to cellular specialization. The ear now joins the long list of organs which demonstrate this phenomenon.     

Viremia in young herons and ibis infected with Venezuelan encephalitis virus

Fifty-seven of 61 nestling, 8- to 30-day-old herons of three species (Black-crowned Night Heron, Great Egret, and Snowy Egret), developed viremia lasting one to three days following subcutaneous inoculation with small doses of endemic or epidemic strains of Venezuelan encephalitis virus from Mexico, Guatemala or Venezuela. Two epidemic strains from Guatemala or Venezuela stimulated levels of viremia similar to those following infection with enzootic strains. Great Egrets, Striated and Boat-billed Herons and Scarlet Ibis older than 30 days of age developed viremias of lower levels and shorter durtions than did young birds. Marked differences in levles of viremia were not observed among Black-crowned Night Herons, Great Egrets, or Snowy Egrets. Over 50% of viremic blood samples from herons 8-30 days of age contained 1000 or more chick embryo cell culture plaque forming units of Venezuelan encephalitis per ml, levels sufficient to infect some vector species mosquitoes.     

Hemoglobin QIndia, alpha 64 (E13) Asp replaced by His, and beta-thalassemia in a Canadian family

Cellulose acetate electrophoresis at pH 8.4 showed a hemoglobin variant with the mobility of hemoglobin S in a Canadian family. Sequence analysis revealed that histidine was substituted for aspartic acid at position 64 in the alpha-chain. This variant was found in association with a beta-thalassemia trait condition.     

The GUM, Bayesian inference and the observation and measurement equations

In this paper, we compare uncertainty evaluation procedures based on the measurement and observation equation approaches applied to a class of models covering many practical measuring systems. We derive general conditions for when the two approaches give the same distributions associated with the measurand and give examples of how and where they differ. We argue that while it is possible to interpret the measurement equation approach as determining a state of knowledge distribution for the measurand, for some problems there are conceptual, and for highly nonlinear models, practical difficulties with this interpretation. These conceptual difficulties do not arise if the measurement equation approach is interpreted as characterising the behaviour of a measuring system. The discussion presented here is relevant to the revision of the GUM, currently being undertaken by the Joint Committee for Guides in Metrology.     

OMVPE of InAs quantum dots on an InGaP surface

The organometallic vapor phase epitaxy of InAs quantum dots has been investigated by comparing the effect the underlying surface has on the quantum dot physical characteristics. Atomic force microscopy measurements were used to identify the InAs QDs coalesce to significantly larger size when deposited on an InGaP surface compared to a GaAs surface. Quantitative assessment of the total QD volume on different surfaces such as GaAs, InGaP, and GaAsP implicates the role of indium in the underlying surface for the increase in QD size on InGaP surfaces.     

Galvanic vestibular stimulation elicits consistent head-neck motion in seated subjects

Humans actively stabilize the head-neck system based on vestibular, proprioceptive and visual information. Galvanic vestibular stimulation (GVS) has been used previously to demonstrate the role of vestibular feedback in standing balance. This study explores the effect of GVS on head-neck kinematics and evaluates the approach to investigate the vestibular contribution to head-neck stabilization. GVS was applied to 11 seated subjects using seven different stimuli (single sinusoids and multisines) at amplitudes of 0.5-2 mA and frequencies of 0.4-5.2 Hz using a bilateral bipolar configuration while 3-D head and torso kinematics were recorded using motion capture. System identification techniques were used evaluating coherence and frequency response functions (FRFs). GVS resulted in significant coherence in roll, yaw and lateral translation, consistent with effects of GVS while standing as reported in the literature. The gain of the FRFs varied with frequency and no modulation was observed across the stimulus amplitudes, indicating a linear system response for the stimulations considered. Compared to single sine stimulation, equivalent FRFs were observed during unpredictable multisine stimulation, suggesting the responses during both stimuli to be of a reflexive nature. These results demonstrate the potential of GVS to investigate the vestibular contribution to head-neck stabilization.     

Excitation of hypothalamic nucleus arcuatus neuron induced decrease of plasma sialic acid level in rats

The effect of sodium glutamate (Glu) on plasma sialic acid (SA) level was studied by means of microinjection into the nucleus arcuatus (ARC) and ultraviolet spectrophotometry. The results indicate: (1) The plasma SA level was significantly decreased after microinjection of Glu into the ARC (P < 0.01). With increasing Glu concentration, the onset of the decrease occurred earlier. (2) When Glu was microinjected into ARC after intraventricular injection of apomorphine, the plasma SA level was significantly decreased (P < 0.01) and the time required to cause the decrease was shortened. (3) When Glu was microinjected into ARC after intraventricular injection of spiperone, no change was found in the plasma SA level (P > 0.05). The above results suggest that the mechanism underlying the decrease of plasma SA level is probably related to modulated dopamine (DA) release of hypothalamic dopaminergic neurons by DA-D2 receptor.