Mechanics of Coriolis stimulus and inducing factors of motion sickness.

To specify inducing factors of motion sickness comprised in Coriolis stimulus, or cross-coupled rotation, the sensation of rotation derived from the semicircular canal system during and after Coriolis stimulus under a variety of stimulus conditions, was estimated by an approach from mechanics with giving minimal hypotheses and simplifications on the semicircular canal system and the sensory nervous system. By solving an equation of motion of the endolymph during Coriolis stimulus, rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then the sensation derived from the whole semicircular canal system was particularly considered in two cases of a single Coriolis stimulus and cyclic Coriolis stimuli. The magnitude and the direction of sensation of rotation were shown to depend on an angular velocity of body rotation and a rotating angle of head movement (amplitude of head oscillation when cyclic Coriolis stimuli) irrespective of initial angle (center angle) of the head relative to the vertical axis. The present mechanical analysis of Coriolis stimulus led a suggestion that the severity of nausea evoked by Coriolis stimulus is proportional to the effective value of the sensation of rotation caused by the Coriolis stimulus.     

Influence of the hypothalamic-pituitary axis on the androgen regulation of the ocular secretory immune system

The purpose of the present investigation was to examine the influence of the hypothalamic-pituitary axis on the androgen regulation of the ocular secretory immune system. Studies included the following experiments: (1) Testosterone administration significantly increased the immunoglobulin A (IgA) and free secretory component (SC) levels in tears of adult, orchiectomized and sham-hypophysectomized rats, as compared with those in tears of saline-treated controls. (2) Hypophysectomy completely inhibited this androgen effect. (3) Transfer of the pituitary to under the kidney capsule in orchiectomized and hypophysectomized rats did not restore the physiological conditions required for testosterone's stimulation of tear IgA and SC. (4) Selective ablation of the anterior pituitary gland also interfered with the testosterone-induced elevation of tear IgA and SC content. (5) Treatment of orchiectomized and/or hypophysectomized rats with rat prolactin, growth hormone, alpha-melanocyte-stimulating hormone or vehicle for 4 days had no effect on tear SC and/or IgA levels. Overall, these findings demonstrate that an intact hypothalamic-pituitary axis either supports or mediates the androgen control of the secretory immune system in the eye.     

An analysis of the mechanical forces in each semicircular canal of the cat under single and combined rotations

The vector equation for the general motion of a body in an inertial system is used to analyze the accelerations in the semicircular canals of the cat when the head undergoes rotation about a vertical axis only, rotation about the naso-occipital axis only, and both rotations simultaneously. The corresponding mean forces and mean pressures in the endolymph are calculated by means of a closed line integral along each canal circumference. The importance of the area of the semicircular canal and of its orientation in space become evident. One can see through this mathematical analysis that the input pattern received by the labyrinthine system depends on a set of well-specified geometrical and mechanical conditions, which must be precisely evaluated in order to interpret the nystagmic outputs.     

Three-dimensional vestibular eye and head reflexes of the chameleon: characteristics of gain and phase and effects of eye position on orientation of ocular rotation axes during stimulation in yaw direction

We investigated gaze-stabilizing reflexes in the chameleon using the three-dimensional search-coil technique. Animals were rotated sinusoidally around an earth-vertical axis under head-fixed and head-free conditions, in the dark and in the light. Gain, phase and the influence of eye position on vestibulo-ocular reflex rotation axes were studied. During head-restrained stimulation in the dark, vestibulo-ocular reflex gaze gains were low (0.1-0.3) and phase lead decreased with increasing frequencies (from 100 degrees at 0.04 Hz to < 30 degrees at 1 Hz). Gaze gains were larger during stimulation in the light (0.1-0.8) with a smaller phase lead (< 30 degrees) and were close to unity during the head-free conditions (around 0.6 in the dark, around 0.8 in the light) with small phase leads. These results confirm earlier findings that chameleons have a low vestibulo-ocular reflex gain during head-fixed conditions and stimulation in the dark and higher gains during head-free stimulation in the light. Vestibulo-ocular reflex eye rotation axes were roughly aligned with the head's rotation axis and did not systematically tilt when the animals were looking eccentrically, up- or downward (as predicted by Listing's Law). Therefore, vestibulo-ocular reflex responses in the chameleon follow a strategy, which optimally stabilizes the entire retinal images, a result previously found in non-human primates.     

A method for repositioning the external ear

The malposition of an otherwise normal-appearing external ear is not uncommon in certain craniofacial syndromes. This paper presents a 10-year experience of 14 patients who underwent external ear repositioning. In this technique, a posterior incision is used to mobilize surrounding soft tissues circumferentially around the external auditory canal, which then serves as an axis for anterior rotation and elevation. Elevation of up to 8 mm and rotation up to 30 degrees can be achieved. Further elevation is limited by the ensuing constriction and resistance of the external auditory canal. More rotation can be achieved with a Z-plasty transposition of an inferiorly based postauricular skin flap.     

电刺激蝙蝠小脑对中脑上丘神经元听反应的影响

实验在２３只成年中华鼠耳蝠（Ｍｙｏｌｉｓｃｈｉｎｅｎｓｉｓ）上进行。使用常规电生理学方法,观察了电刺激小脑对上丘神经元听反应的影响。在所观察的１７１个上丘神经元中,有１１６个（占６７．８４％）神经元听反应受到影响,其中７２个（占４２．１１％）表现为抑制效应,４４个（占２５．７３％）为易化效应。刺激小脑对上丘神经听反应的影响是双侧的。抑制或易化程度与电刺激强度、声刺激强度以及声、电刺激间隔有关。结果提示,小脑可以对上丘神经元听反应进行调制,这种调制作用可能是小脑调控回声定位过程中听觉－运动的中枢机制之一。     

Motion from the past. A new method to infer vestibular capacities of extinct species

The vestibular system detects head movement in space and maintains visual and postural stability. The semicircular canal system is responsible for registering head rotation. How it responds to head rotation is determined by the rotational axis and the angular acceleration of the head, as well as the sensitivity and orientation of each semicircular canal. The morphological parameters of the semicircular canals are supposed to allow an optimal detection of head rotations induced by some behaviours, especially locomotor. We propose a new method of semicircular canal analysis, based on the computation of central streamlines of virtually reconstructed labyrinths. This method allows us to ascertain the functional structure of the semicircular canal system and to infer its capacity to detect particular head rotations, induced by particular behaviours. In addition, this method is well-suited for datasets provided by any kind of serial sectioning methods, from MRI to μCT scanning and even mechanical serial sectioning, of extant and extinct taxa.     

Decrease of the slow phase velocities of postrotatory nystagmi as a result of the otolith organs stimulation

Intact pigeons were rotated in darkness in a horizontal plane at various orientations relative to axis of rotation, which passed between labyrinths, or was displaced relative to them. Trapezoidal (tests 1) and triangular (tests 2) rotation programs were used. In the tests 1, positive and negative angular accelerations were separated by two-minute periods of rotation with constant angular velocity. Such periods were absent in the tests 2. Results of the canal-otolith interactions in the tests 1 and 2 were different only in postrotatory nystagmi: the peak velocities of the slow phases decreased in both postrotatory nystagmi in the tests 1, but only in one of them in the tests 2. Apparently, at oppositely directed postrotatory nystagmi, decrease of peak velocities in the tests 1 is provided with different mechanisms. At one of them the decrease of nystagmus velocity reflects a result of a summation of canal and otolithic signals on the interneurones of the semicircular canal reflex arches, whereas at another one it is related with long-lasting activity imbalance of these interneurones which is supported by otolithic afferentation during rotation at constant angular velocity.     

Cortisol response to an acute injection of IL-2 in healthy subjects and cancer patients: a first immunoneuroendocrine standardized clinical test to explore the interactions between immune and neuroendocrine systems

Preliminary clinical studies would suggest that the immune alterations characterizing severe human illnesses, such as autoimmune diseases and cancer itself, may depend at least in part on an anomalous psychoneuroendocrine regulation of the immunity. Unfortunately, at present the psychoneuroimmune interactions may be clinically investigated only by separately analyzing the neuroendocrine and the immune systems, since there is no standardized clinical test capable of detecting the physiological response of the endocrine secretion to an immune stimulation. One of the main endocrine functions influenced by the immune activation is the hypothalamic-pituitary-adrenal axis. In fact, several cytokines have appeared to stimulate cortisol secretion by acting at a central site. On this basis, a study was planned to evaluate cortisol response to an acute IL-2 injection in healthy subjects and metastatic cancer patients, in an attempt to standardize a clinical neuroendocrinoimmune test capable of documenting possible alterations of the link between neuroendocrine and immune systems. The study included 10 healthy subjects as a control group and 10 cancer patients with metastatic disease. Control subjects were evaluated in basal conditions to determine the physiological circadian rhythm of cortisol, and after the subcutaneous (SC) injection of IL-2 (3 and 9 million IU). IL-2 at 3 million IU stimulated cortisol release in all healthy controls and in none of the cancer patients. IL-2 at 9 million IU induced a significant increase in cortisol mean levels in cancer patients, whose values, however, were still significantly lower with respect to those seen in controls in response to IL-2 at 3 million IU. No important IL-2 related side-effect occurred. This study shows that an acute SC injection of low-dose IL-2 with a following evaluation of cortisol secretion may constitute a first standardized immunoendocrine test, capable of exploring the status of the physiological link between neuroendocrine and immune systems, and of documenting the existence of important alterations in human diseases related to an immune dysfunction, such as advanced cancer, which has appeared to be characterized by a hyposensitivity of the hypothalamic-pituitary-adrenal axis to an acute cytokine administration.     

A linear canal-otolith interaction model to describe the human vestibulo-ocular reflex

A control systems model of the vestibulo-ocular reflex (VOR) originally derived for yaw rotation about an eccentric axis (Crane et al. 1997) was applied to data collected during ambulation and dynamic posturography. The model incorporates a linear summation of an otolith response due to head translation scaled by target distance, adding to a semi-circular canal response that depends only on angular head rotation. The results of the model were compared with human experimental data by supplying head angular velocity as determined by magnetic search coil recording as the input for the canal branch of the model and supplying linear acceleration as determined by flux gate magnetometer measurements of otolith position. The model was fit to data by determining otolith weighting that enabled the model to best fit the data. We fit to the model experimental data from normal subjects who were: standing quietly, walking, running, or making active sinusoidal head movements. We also fit data obtained during dynamic posturography tasks of: standing on a platform sliding in a horizontal plane at 0.2 Hz, standing directly on a platform tilting at 0.1 Hz, and standing on the tilting platform buffered by a 5-cm thick foam rubber cushion. Each task was done with the subject attending a target approximately 500, 100, or 50 cm distant, both in light and darkness. The model accurately predicted the observed VOR response during each test. Greater otolith weighting was required for near targets for nearly all activities, consistent with weights for the otolith component found in previous studies employing imposed rotations. The only exceptions were for vertical axis motion during standing, sliding, and tilting when the platform was buffered with foam rubber. In the horizontal axis, the model always fit near target data better with a higher otolith component. Otolith weights were similar with the target visible and in darkness. The model predicts eye movement during both passive whole-body rotation and free head movement in space implying that the VOR is controlled by a similar mechanism during both situations. Factors such as vision, proprioception, and efference copy that are available during head free motion but not during whole-body rotation are probably not important to gaze stabilization during ambulation and postural stabilizing movement. The linearity of the canal-otolith interaction was tested by re-analysis of the whole body rotation data on which the model is based (Crane et al. 1997). Normalized otolith-mediated gain enhancement was determined for each axis of rotation. This analysis uncovered minor non-linearities in the canal-otolith interaction at frequencies above 1.6 Hz and when the axis of rotation was posterior to the head. Received: 11 March 1998 / Received in revised form: 1 March 1999     

Schlemm's Canal Is a Unique Vessel with a Combination of Blood Vascular and Lymphatic Phenotypes that Forms by a Novel Developmental Process

Schlemm''s canal (SC) plays central roles in ocular physiology. These roles depend on the molecular phenotypes of SC endothelial cells (SECs). Both the specific phenotype of SECs and development of SC remain poorly defined. To allow a modern and extensive analysis of SC and its origins, we developed a new whole-mount procedure to visualize its development in the context of surrounding tissues. We then applied genetic lineage tracing, specific-fluorescent reporter genes, immunofluorescence, high-resolution confocal microscopy, and three-dimensional (3D) rendering to study SC. Using these techniques, we show that SECs have a unique phenotype that is a blend of both blood and lymphatic endothelial cell phenotypes. By analyzing whole mounts of postnatal mouse eyes progressively to adulthood, we show that SC develops from blood vessels through a newly discovered process that we name “canalogenesis.” Functional inhibition of KDR (VEGFR2), a critical receptor in initiating angiogenesis, shows that this receptor is required during canalogenesis. Unlike angiogenesis and similar to stages of vasculogenesis, during canalogenesis tip cells divide and form branched chains prior to vessel formation. Differing from both angiogenesis and vasculogenesis, during canalogenesis SECs express Prox1, a master regulator of lymphangiogenesis and lymphatic phenotypes. Thus, SC development resembles a blend of vascular developmental programs. These advances define SC as a unique vessel with a combination of blood vascular and lymphatic phenotypes. They are important for dissecting its functions that are essential for ocular health and normal vision.     

Influence of the motor cortex on lateral geniculate responses evoked in the cat by contralateral superior colliculus stimulation

It is shown that in nembutal anesthetized cats, a single stimulation of motor cortex (MC) causes a response in lateral geniculate nucleus (LGN). The development of this response had a conditioning effect on the LGN response evoked by stimulation of the contralateral superior colliculus (SC), markedly inhibiting it. The degree of this inhibition depended on the time interval between the cortical conditioning stimulation and the tectal test stimulation. A single conditioning MC stimulation did not noticeably change the LGN responses evoked by a light stimulus, but markedly inhibited visual responses from deep SC layers (those regions which on stimulation gave rise to LGN responses). From the results, it is suggested that the MC monitors the execution of tectal influences on LGN function at the tectal level rather than the geniculate level, and it is precisely by this means that it regulates saccadic suppression of LGN function, in the realization of which, as presumed earlier, the SC takes part.A. I. Karaev Institute of Physiology, Azerbaijan Academy of Sciences, Baku. Translated from Neirofiziologiya, Vol. 24, No. 4, July–August 1992.     

The effect of otolith and semicircular canal convergence on the VOR during eccentric rotation

VOR gain modulation was systematically investigated in the Rhesus monkey (M. mulatta) during centric and variable eccentric (up to 50 cm) sinusoidal rotation (4 Hz, 0.75 degree) with the nose facing in- or outward to test convergence of otolith and semicircular canal afferences. Earth-stationary lit LED-targets were placed at different distances (12-180 cm) from the monkey. Results were compared to biological demands. During centric rotation at 4 Hz when smooth pursuit mechanisms do not play a role, VOR gain--as expected--was approximately 1 without dependence on target distance. Phase of VOR and centrifuge were shifted by about 180 degrees as was predicted. If the monkey was rotated eccentrically with the nose facing outward the expected gain enhancement for close targets was obtained. Maximal experimental VOR gain during 4 Hz rotation was 4.4 which was close to demand at 50 cm eccentricity and 15 cm target distance (predicted gain: 4.6). If the nose points inward three situations have to be distinguished from simulation: (1) target behind the axis of rotation--VOR gain decrement should occur; (2) target on the axis of rotation--"inverse VOR suppression"; (3) target between monkey and axis of rotation--phase reversal. Experimentally, VOR gain decrement was obtained (situation 1). VOR gain was minimal (but not zero) for targets around the axis of rotation (situation 2). Situation 3 has not been investigated in detail so far.     

Banks grass mite (Oligonychus pratensis) abundance on sorghum cultivars with different levels of nitrogen use and metabolism efficiency

Banks grass mite (Oligonychus pratensis (Banks)), abundance was recorded for three years on sorghum (Sorghum bicolor (L.) Moench) cultivars with different levels of nitrogen (N) use and metabolism efficiency. The cultivars included 77CS1, SC630-11E, R6956, and SC325-12. Nitrogen fertilizer was applied to plots containing each cultivar at 0,45, and 180 kg Na ha^–1. Significantly more mites were on plants at 180 kg N ha^–1 than at 0 or 45 kg N ha^–1. The lowest mite densities were recorded on SC325-12, the N-use-inefficient and N-metabolism-efficient cultivar. In July,O. pratensis abundance was statistically equivalent on SC325-12 and on R6956, the other N-metabolism-efficient cultivar. In August, mite densities on R6956 were as high as on 77CS1 and SC630-11E, which are N-metabolism-ineficient cultivars. Mite densities were lower on N-use-inefficient and N-metabolism-efficient sorghum cultivars than on their respective efficiency counterparts. Physiological differences in N-use and metabolism-inefficient cultivars may influence the amount of leaf N plus the amount and form of amino acids and other N-based chemicals in sorghum leaves. These plant chemicals have been shown to influence mite abundance on several hosts, and may have been key to influencing the results of these experiments.     

Ultrastructure of the synaptic autosomes and the ZW bivalent in chicken oocytes

Chromosomal axes of chicken oocytes from pre- and post-hatching chickens were analyzed with a microspreading technique for electron microscopy. At leptotene, chromosomal axes begin to be formed as discontinuous, non-polarized axial segments. During zygotene synaptonemal complex (SC) formation begins at the axial ends attached to the nuclear envelope. Polarization of axial ends is nearly simultaneous with the beginning of SC formation. The complete SC set is found at pachytene and it consists of 38 SC's and an unequal SC which has been identified as the ZW pair. This unequal SC is formed by two axes of different length. The Z and W axes represent 6.2% and 4.5% respectively of the combined length of the SC set plus the Z axis. The unpaired segment of the Z axis shortens markedly from early to mid-pachytene and becomes thicker than the lateral elements of SCs. In the paired region the Z axis forms most of the twists around a straighter W axis, suggesting some extent of non-homologous pairing between the Z and W chromosomes in this region. The existence of partial synapsis of the Z and W axes without heteropycnosis of the sex chromosomes is in marked contrast to partial synapsis in the heteropycnotic XY body of mammalian spermatocytes.     

Electrophysiological relations between the superior colliculus and the red nucleus in the cat.

The electrical activity of single units located in the parvicellular part of the red nucleus (pRP) was recorded extracellularly in nitrous oxide anesthetized and C1-transected adult cats. In this area, neurons were found to respond to electrical stimulation applied to intermediate and deep layers of the right superior colliculus (SC). Forty neurons located in the pRN of both sides were studied. Three neurons out of 18 (16.6%) located in the contralateral pRN and six neurons out of 22 (27.3%) located in the ipsilateral pRN were driven by the right SC stimulation. The pRN neurons were separated into four groups according to the latency response to the SC stimulation: 1) 0.6-1.9 ms, 2) 2-4 ms, 3) 4-6 ms, 4) variable latency responses. Each of these four groups of neurons showed a particular pattern of discharge, even though their discharge frequency showed a strong consistency. Four pRN neurons, which responded to SC stimulation, showed a significant correlation with spontaneous horizontal eye movements of saccadic type. It is known that the SC represents one of the main outputs of the striato-nigral motor system. The relation between the SC and the pRN described in the present study suggest that connections exist between the cortico-rubral and the striato-nigral systems, since both have the SC as a common output structure. It is likely, therefore, that the cortico-rubral-SC system is involved in the control of oculomotor functions, and that the SC may serve to establish interactions between systems concerned with eye movements.     

Movements of the Schwann cell nucleus implicate progression of the inner (axon-related) Schwann cell process during myelination

Although it has been known for several decades that peripheral myelin is formed from an extended, spiraled, and compacted sheet of Schwann cell (SC) plasma membrane, the mechanism by which this unique spiraling is accomplished remains unknown. We have studied the movements of SC nuclei before, during, and subsequent to myelin formation (over periods of 24-72 h) to determine if this nuclear motion (noted in earlier reports) would provide useful insights into the mechanism of myelinogenesis. We used rodent sensory neuron and SC cultures in which initiation of myelinogenesis is relatively synchronized and bright field conditions that allowed resolution of the axon, compact myelin, and position of the SC nucleus. Observed areas were subsequently examined by electron microscopy (EM); eight myelinating SCs with known nuclear movement history were subjected to detailed EM analysis. We observed that, prefatory to myelination, SCs extended along the length of larger axons, apparently competing with adjacent SCs for axonal surface contact. This lengthening preceded the deposition of compact myelin. SC nuclear circumnavigation of the axon was found to attend early myelin sheath formation. This movement was rarely greater than 0.25 turns per 3 h; on the average, more nuclear motion was seen in relation to internodes that formed during observation (0.8 +/- 0.1 turns/24 h) than in relation to those that had begun to form before observation (0.3 +/- 0.1 turns/24 h). Nuclear circumnavigation generally proceeded in one direction, could be in similar or opposite direction in neighboring myelinating SCs on the same axon, and was not proportional to the number of major dense lines within the myelin sheath. A critical finding was that, in all eight cases examined, the overall direction of nuclear movement was the same as that of the inner end of the spiraling SC process, and thus opposite the direction of the outer end of the spiral. We conclude that the correspondence of the direction of nuclear rotation and inner end of the spiraling cytoplasmic lip implicates active progression of the inner lip over the axonal surface to form the membranous spiral of myelin, the nuclear motion resulting from towing by the advancing adaxonal lip. This interpretation fits with finding basal lamina and macular adhering junctions associated with the external lip of SC cytoplasm; these attributes would imply anchorage rather than movement of this region of the SC.     

Subcortical rotation in Xenopus eggs: an early step in embryonic axis specification

The amphibian egg undergoes a rotation of its subcortical cytoplasm relative to its surface during the first cell cycle. Nile blue spots applied to the egg periphery move with the subcortical cytoplasm and make rotation directly observable (J.-P. Vincent, G.F. Oster, and J. C. Gerhart (1986). Dev. Biol. 113, 484). We have previously shown that the direction of rotation accurately predicts the orientation of the embryonic axis developed by the egg. This suggests an important role for subcortical rotation in axis specification. In this report, we provide two kinds of experimental evidence for the essential role of rotation, and against a role for other concurrent cytoplasmic movements such as the convergence of subcortical cytoplasm toward the sperm entry point in the animal hemisphere. First, dispermic eggs develop only one embryonic axis, which is oriented accurately in line with the direction of the single rotation movement and not with the two convergence foci that form in the animal hemisphere. Rotation probably modifies the vegetal, not animal, hemisphere since axial development is normal in dispermic eggs despite highly altered animal subcortical movement. Second, we show that the amount of rotation correlates with the extent of dorsal development. UV irradiation of the vegetal hemisphere, or cold shock of the egg, inhibits rotation effectively. When there is no rotation, there is no dorsal development. On average within the egg population, increasing amounts of rotation correlate with the increasingly anterior limit of the dorsal structures of the embryonic body axis. However, individual partially inhibited eggs vary greatly in the amount of axis formed following a given amount of movement. Furthermore, the egg normally rotates more than is necessary for the development of a complete axis. These findings suggest that rotation, although essential, does not directly pattern the antero-posterior dimension of the body axis, but triggers a response system which varies from egg to egg in its sensitivity to rotation. This system is artificially sensitized by exposure of the egg to D2O shortly before rotation. We show that D2O-treated eggs produce extensive axes despite very limited rotation, often developing into hyperdorsal embryos. However, like normal eggs, they depend on rotation and cannot form dorsal structures if it is eliminated.