Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Breathing affects left ventricular stroke volume (LVSV) in normal subjects. The observed relationship may result from interaction between the effects of changing lung volume and intrathoracic pressure (IP). 2. To investigate the effect of IP on LVSV with minimal changes in lung volume, beat-by-beat LVSV (pulsed Doppler ultrasound) and systemic blood pressure (Finapres) were measured during obstructed inspiratory and expiratory efforts causing step changes in IP of +/- 15 cmH2O for 10 s, in seven subjects. Changes in mouth pressure (MP) during airway occlusion were used to indicate changes in IP. Group-averaged data for each second were compared to that in the second before the change in MP using Dunnet's multiple range test. 3. Step reductions in MP resulted in immediate and significant falls in LVSV (P < 0.05) and systolic blood pressure (P < 0.01) and increased heart rate, although this was not significant. These responses were transient, lasting only 3 s despite 10 s of reduced MP. 4. Step increases in MP caused biphasic cardiovascular responses. LVSV increased immediately, then fell significantly below control after 8 s (P < 0.01). Heart rate increased significantly between 5 and 9 s after the onset of the increase in MP (P < 0.05), suggesting activation of the baroreflexes by the accompanying progressive fall in systolic blood pressure. 5. The asymmetry in time course and magnitude between the responses to positive and negative pressure may reflect asymmetrical effects of MP on systemic venous return, right ventricular output, pulmonary venous return and left ventricular (LV) after-load, with the baroreceptors limiting changes in arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of positive and negative step changes in intrathoracic pressure on left ventricular function in conscious man. 814 57

The characterization of sensory, motor and cognitive dysfunctions following occlusion of the middle cerebral artery (MCA) is prerequisite to investigations of treatment intervention in animal models of ischemia. Different strategies are used to induce ischemia, but the focal, transient occlusion of the MCA has been reported to result in neuropathology most similar to that seen in clinical cerebral ischemia. If the MCA occlusion technique results in a stroke animal model, then the behavioral impairments inherent in stroke should be manifested in this model. The present study provides a further characterization of behavioral alterations associated with MCA occlusion. Sprague-Dawley rats underwent temporal occlusion of the right MCA, and at 1 mo and 2 mo postischemia, were subsequently tested in passive avoidance behavior, motor coordination, asymmetrical motor behavior, neurological functioning, nocturnal spontaneous and amphetamine-induced locomotor activity, and haloperidol-induced catalepsy. Results revealed that ischemic rats showed long-term impairments in sensory, motor and cognitive functions. The discrepancy with other studies reporting temporal MCA-induced behavioral deficits may be due to techniques used to induce ischemia and consequent CNS damage, differences in time period of testing (i.e., immediate vs. later postischemia, nighttime vs. daytime), number of test-retests over the course of the experiment, and age of the animals. The mechanism involved in the MCA-induced behavioral changes may be represented by loss of dopamine receptors on striatal neurons. Histological analysis revealed damage limited to the lateral aspect of the striatum. These behavioral and anatomical data support MCA occlusion as a model of ischemia, and elucidate important factors that should be controlled for in characterizing the MCA-induced neuropathological alterations.
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PMID:Locomotor and passive avoidance deficits following occlusion of the middle cerebral artery. 857 87

The objective of this study was to examine the effects of wave propagation properties (global reflection coefficient gamma IG; pulse wave velocity, c(ph); and characteristic impedance zeta(o) on the mechanical performance of the coupled left ventricle-arterial system. Specifically, we sought to quantify effects on aortic pressure (P(ao)) and flow Q(ao) while keeping constant other determinants of P(ao) and Q(ao) (left ventricular end-diastolic volume, V(ed), and contractility, heart rate, and peripheral resistance, R(s)). Isolated rabbit hearts were subjected to real-time, computer-controlled physiological loading. The arterial circulation was modeled with a lossless tube terminating in a complex load. The loading system allowed for precise and independent control of all arterial properties as evidenced by accurate reproduction of desired input impedances and computed left ventricular volume changes. While propagation phenomena affected P(ao) and Q(ao) morphologies as expected, their effects on absolute P(ao) values were often contrary to the current understanding. Diastolic (Pd) and mean (Pm) P(ao) and stroke volume decrease monotonically with increases in gamma G, c(ph), or zeta(o) over wide ranges. In contrast, these increase had variable effects on peak systolic P(ao) (Ps): decreasing with gamma G, biphasic with c(ph), and increasing with zeta(o). There was an interaction between gamma G and c(ph) such that gamma G effects on P(m) and P(d) were augmented a higher C(ph) and vice versa. Despite large changes in system parameters, effects on Pm and Ps were modest ( < 10% and < 5%, respectively); effects on Pd were always two to four times greater. Similar results were obtained when the single-tube model of the arterial system was replaced by an asymmetrical T-tube configuration. Our data do not support the prevailing hypothesis that P(s) (and therefore ventricular load) can be selectively and significantly altered by manipulating gamma G, c(ph), and/or zeta o.
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PMID:Wave propagation in coupled left ventricle-arterial system. Implications for aortic pressure. 862 Dec

Current models for the action of linear biological motors may be grouped in two main categories. The conventional "bind and bend" models rely for their power stroke upon a structural change in the myosin headgroup (S1 fragment) which follows the binding of myosin to the F-actin filament. The more recent ratchet models demonstrate that directional motion of a particle along an asymmetrical ratchet is possible with a symmetrical but time-correlated stochastic drive. In this paper a new type of model is introduced which is deterministic like the "bind and bend" model but it requires no molecular structural changes to power the stroke. Like the ratchet models the motor is driven along the linear stator by tangential forces at the interface but the forces are electrostatic and controlled by the hydrolysis of ATP to ADP.
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PMID:Linear electric traction as an alternative model of the actin/myosin motor. 873 31

Respiratory complications are common in patients with stroke, but the involvement of the diaphragm in this setting is not completely understood. The purpose of this study was to assess corticodiaphragmatic pathways in patients with vascular hemiplegia. Fifteen patients were studied, nine with a capsular type of hemiplegia. Seven age-matched subjects served as the control group, and eight healthy young volunteers were studied to validate the methods by comparison with the literature. Diaphragm electromyogram was recorded bilaterally, using surface electrodes. Abductor pollicis brevis electromyogram was also recorded. After having checked the integrity of peripheral conduction, corticofugal pathways were studied using cortical magnetic stimulation, a reproducible and patient-independent stimulus. Left and right conduction times to the diaphragm were symmetrical in the control subjects, the young volunteers, and the six patients with hemiplegia but without capsular lesion (16.5 to 20.1 ms). Conversely, they were markedly asymmetrical in patients with capsular hemiplegia, diaphragm response on the plegic side being abolished or markedly delayed. Although the clinical impact of these findings remains to be determined, this study confirms that "central diaphragm paralysis" can be present in stroke. It also indicates that there is no bilateral motor representation of each hemidiaphragm.
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PMID:Impairment of central motor conduction to the diaphragm in stroke. 875 19

Clinical and MRI investigations were carried out on 27 patients with acquired pendular nystagmus in an attempt to delineate possible sites of lesions responsible for pendular nystagmus and mechanisms underlying the frequent ocular disconjugacy of this nystagmus. The aetiologies were multiple sclerosis (n = 21), brainstem stroke (n = 3) and other neurological conditions. In at least 59% of the patients, pendular nystagmus appeared > 1 year after the first symptom of the disease. Patients MRIs were characterized by multiple areas of abnormal signal and were analysed statistically to identify areas where lesions overlapped significantly between patients. Statistically significant overlap occurred in areas containing the red nucleus, the central tegmental tract, the medial vestibular nucleus and the inferior olive. Patients with horizontal pendular nystagmus showed predominantly pontine lesions whereas patients with torsional pendular nystagmus showed predominantly medullary involvement. The nystagmus was conjugate in 15 patients and disconjugate in amplitude or direction in 12. Internuclear ophthalmoplegia or asymmetrical visual acuity occurred in similar proportions in both groups. Patients with conjugate pendular nystagmus had a higher incidence of symmetrical, "mirror image' lesions on MRI than patients with disconjugate nystagmus. The abundance of abnormal MRI signals in our sample suggests that large or multiple structural lesions may be required to elicit pendular nystagmus, predominantly in the pons but also in the midbrain and medulla. The involvement of structures projecting to the inferior olive supports the hypothesis that oscillatory properties of olivary neurons causes the rhythm of pendular nystagmus. The delay observed between the onset of the underlying disease and the pendular nystagmus supports a mechanism operating via neural deafferentation. Disconjugancies in pendular nystagmus cannot be explained on the basis of the associated internuclear ophthalmoplegias nor on the basis of asymmetrical visual acuity. The association between symmetrical MRI lesions and conjugate nystagmus suggests that asymmetrical damage to brainstem structures concerned with binocular alignment may underlie disconjugate pendular nystagmus.
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PMID:Clinical and MRI correlates in 27 patients with acquired pendular nystagmus. 880 Sep 42

Sodium dichloroacetate (DCA) or placebo, two infusions 30 min in duration and 8 h apart, was administered to healthy subjects under double-blind conditions. The objectives were to characterize accurately the tolerability of DCA, its pharmacokinetics, and the reduction of resting serum lactate concentration by DCA. A hybrid, one-compartment pharmacokinetic model fitted best, with zero-order elimination mean of 27.9 micrograms/ml/h at concentrations above about 80 to 120 micrograms/ml, and with first-order elimination (mean kelim = 0.54) at lower serum concentrations of DCA. Resting serum lactate was dose-independently, maximally reduced within 15 min of the end of all active infusions. The duration of suppression of resting serum lactate was dose-dependent, from 4.5 h (30 mg/kg) to > 8 h (100 mg/kg). Second infusions (15-50 mg/kg) again promptly and maximally reduced resting serum lactate. Hysteresis loops were asymmetrical for all doses but exhibited change in shape that was dose-dependent; no good pharmacokinetic-pharmacodynamic model could be fitted that was consistent between doses. Infusions were well tolerated, 100 mg/kg + 50 mg/kg being the highest doses. Somnolence, the only dose-related adverse event, was reported by 3 of 37 subjects at times corresponding to the highest serum DCA concentrations. This study demonstrates the tolerability of i.v. DCA, proposes a simple pharmacokinetic model for its elimination, characterizes the dose-response relationship in terms of time course of effect, shows the dissociation between elimination of DCA and offset of response and will guide further studies of DCA in patients with head injury or stroke.
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PMID:Reduction of serum lactate by sodium dichloroacetate, and human pharmacokinetic-pharmacodynamic relationships. 893 Jan 72

We report on the neuropsychological and neurolinguistic features of a bilingual patient, E.M., who presented with an uncommon pattern of aphasic deficit consequent to subcortical lesions mainly involving the left basal ganglia. Not only are reports of bilingual subcortical aphasia rare, but E.M.'s deficit is particularly uncommon for it concerns the most used mother tongue (Venetian) much more than a less practiced second language (standard Italian). In this patient, the linguistic deficit in mother tongue production has been observed in spontaneous speech and in cross language translation tasks, where an asymmetrical paradoxical performance has been revealed. Indeed, unlike neurologically intact subjects, E.M. has more difficulties when translating into her mother tongue than into her second language. Although E.M.'s mother tongue is prevalently an oral language, the asymmetrical translation pattern is similar in written and oral translation tasks, thus ruling out the possibility that the deficit simply reflects differences between written and oral language codes. Finally, another remarkable feature of E.M.'s impairment is its stability over almost 5 years from the stroke. We propose that this unusual type of recovery in E.M. is related to the higher degree of automatization of the first language with respect to the second one. This proposal fits with the role of basal ganglia in automatized motor and cognitive performance.
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PMID:Neurolinguistic and follow-up study of an unusual pattern of recovery from bilingual subcortical aphasia. 893 79

In conditions in which ciliated cortical sheets prepared from detergent-extracted Paramecium multimicronucleatum cells adhered to glass coverslips on a microscope stage, perfusion of a reactivation medium containing ATP plus cyclic AMP or cyclic GMP generated metachronal waves. An analysis of the ciliary movements that generate these metachronal waves yielded the following results. During the generation of metachronal waves, there were phase differences in the ciliary orientation of adjacent cilia in the direction of wave propagation. Addition of cyclic AMP or cyclic GMP increased the rotational angular velocities during the effective stroke of ciliary beating, but did not increase the rotational angular velocity of the recovery stroke. When the ATP concentration in the cyclic GMP reactivation medium was increased, the rotational angular velocity during the effective stroke rose steeply and saturated at 0.8 mmol l-1 ATP, whereas that during the recovery stroke rose gradually. Addition of cyclic nucleotides caused a single cilium isolated from neighbouring cilia on the cortical sheet to incline almost parallel to the cortical surface during the recovery stroke. Addition of cyclic GMP increased the amplitude of bending of cilia detached from the cortical sheet. From these results, it was concluded that increases in the asymmetrical movement of individual cilia, caused by the addition of cyclic nucleotides, create the ciliary interaction that generates the metachronal waves.
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PMID:RECONSTITUTION OF METACHRONAL WAVES IN CILIATED CORTICAL SHEETS OF PARAMECIUM - ASYMMETRY OF THE CILIARY MOVEMENTS 931 63

Flying locusts orient to sounds in their environment. Sounds similar to those produced by echolocating bats cause a flying locust to change its flight path. We used high-speed cinematography and videography to study changes in body posture and wing kinematics of tethered locusts in response to stimulation with bat-like sounds. Locusts showed both negative and positive phonotaxis to this stimulus. Within a few wingbeats of stimulus onset (between 126 and 226ms), locusts deflected their abdomens to one side, and the angle of the left and right forewings with respect to the dorsal&shy;ventral body axis became asymmetrical during the downstroke. This forewing asymmetry, in which the forewing on the inside of the turn became more depressed, ranged from 20 to 45&deg; (37&plusmn;9.7&deg;, mean &plusmn; s.d.) and was correlated with the direction and magnitude of abdomen deflection, a measure of steering in tethered, flying locusts. Hindwing stroke angle asymmetries were minimal or non-existent after stimulation. Coincident with changes in forewing asymmetry and abdomen deflection was a decrease in stroke amplitude (19&plusmn;6.5&deg;) of the forewing on the inside of the attempted turn. Motor patterns from forewing first basalar (M97) muscles showed an asymmetry in the timing of left and right depressor activation that ranged from 10.4 to 1.6ms (4.23&plusmn;2.85ms). The number of spikes per depressor burst increased to a maximum of three spikes in the muscle on the inside of the attempted turn, and depressor frequency (wingbeat frequency) increased by approximately 2Hz (2.17&plusmn;0.26Hz). We suggest that the asymmetry in forewing first basalar activity is causally related to the asymmetry in the timing of the initiation of the downstroke, resulting in an asymmetry in the ranges of the stroke angles of the forewings, which would impart a roll torque to the locust. This would augment the steering torques generated by concurrent changes in the angle of attack of the fore- and hindwings and changes in abdomen position to effect rapid avoidance manoeuvres.
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PMID:Forewing asymmetries during auditory avoidance in flying locusts 932 Feb 44


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