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At least 397 records · Page 22Linked to original sources
PubMed1980

Contractile basis of ameboid movement. VII. Aequorin luminescence during ameboid movement, endocytosis, and capping.

Aequorin luminescence has been utilized to determine the spatial and temporal fluctuations of the free calcium ion concentration [Ca++] in Chaos carolinensis during ameboid movement, pinocytosis, and capping. The [Ca++] increases above approximately 10(-7) M during normal ameboid movement. Three types of luminescent signals are detected in cells: continuous luminescence, spontaneous pulses, and stimulated pulses. Continuous luminescence is localized in the tails of actively motile cells, and spontaneous pulses occur primarily over the anterior regions of cells. We are sometimes able to correlate the spontaneous pulses with extending pseudopods, whereas stimulated pulses are induced by mechanical damage, electrical stimulation, concanavalin A-induced capping, and pinocytosis. The localization of both distinct actin structures and sites where [Ca++] increases suggests cellular sites of contractile activity. The independent evidence from localizing actin structures and the distribution of [Ca++] can also be viewed in relation to the solation-contraction coupling hypothesis defined in vitro.

Actins↗
PubMed1974

Potassium flux and leaf movement in Samanea saman. I. Rhythmic movement.

Samanea leaflets usually open in white light and fold together when darkened, but also open and dose with a circadian rhythm during prolonged darkness. Leaflet movement results from differential changes in the turgor and shape of motor cells on opposite sides of the pulvinus; extensor cells expand during opening and shrink during closure, while flexor cells shrink during opening and expand during closure but change shape more than size. Potassium in both open and closed pulvini is about 0.4 N. Flame photometric and electron microprobe analyses reveal that rhythmic and light-regulated postassium flux is the basis for pulvinar turgor movements. Rhythmic potassium flux during darkness in motor cells in the extensor region involves alternating predominance of inwardly directed ion pumps and leakage outward through diffusion channels, each lasting ca 12 h. White light affects the system by activating outwardly directed K(+) pumps in motor cells in the flexor region.

Biological Transport, Active↗
PubMed2004

Eye movement and visuomotor arm movement deficits following mild closed head injury.

Based on increasing evidence that even mild closed head injury (CHI) can cause considerable neural damage throughout the brain, we hypothesized that mild CHI will disrupt the complex cerebral networks concerned with oculomotor and upper-limb visuomotor control, resulting in impaired motor function. Within 10 days following mild CHI (Glasgow Coma Scale 13-15, alteration of consciousness <20 min), we compared 30 patients (15-37 years) and 30 matched controls on different types of saccades, oculomotor smooth pursuit (sine and random), upper-limb visuomotor performance and several neuropsychological tests known to be sensitive to head trauma. Simple reflexive saccades were not impaired, whereas, on the antisaccade task, the CHI group demonstrated prolonged saccadic latencies, a marginally higher number of directional errors and poorer spatial accuracy. The CHI group exhibited more directional errors and impaired motor accuracy on memory-guided sequences of saccades and produced fewer self-paced saccades within 30 s. Most measures of sinusoidal and random oculomotor smooth pursuit showed no deficits, with the exception of a prolonged lag on random smooth pursuit in the CHI group. While arm movement reaction time and arm steadiness were not impaired, the CHI group showed decreased arm movement speed and decreased upper-limb motor accuracy. Conversely, after controlling for IQ, the CHI group had few head trauma-related neuropsychological deficits. These results indicate that multiple motor systems can be impaired following mild CHI and that this can occur independently of neuropsychological impairment. Our study also indicates that quantitative tests of oculomotor and upper-limb visuomotor function may provide sensitive markers of cerebral dysfunction, suggesting the potential use of such tests to supplement patient assessment. To our knowledge, this study is the first to demonstrate the presence of oculomotor or visuomotor deficits following mild CHI.

Adolescent↗
PubMed2000

Interaction between the tobacco mosaic virus movement protein and host cell pectin methylesterases is required for viral cell-to-cell movement.

Virus-encoded movement protein (MP) mediates cell-to-cell spread of tobacco mosaic virus (TMV) through plant intercellular connections, the plasmodesmata. The molecular pathway by which TMV MP interacts with the host cell is largely unknown. To understand this process better, a cell wall-associated protein that specifically binds the viral MP was purified from tobacco leaf cell walls and identified as pectin methylesterase (PME). In addition to TMV MP, PME is recognized by MPs of turnip vein clearing virus (TVCV) and cauliflower mosaic virus (CaMV). The use of amino acid deletion mutants of TMV MP showed that its domain was necessary and sufficient for association with PME. Deletion of the PME-binding region resulted in inactivation of TMV cell-to-cell movement.

Amino Acid Sequence↗
PubMed1988

Movement of water in conjunction with plant movement visualized by NMR imaging.

The water distribution in the pulvinus of Mimosa can be visualized by an NMR imaging technique. After stimulation of a Mimosa plant, water in the lower half of the main pulvinus disappeared, the water previously contained in this area seeming to be transferred to the upper half of the main pulvinus. Movement of the water in conjunction with Mimosa movement was visualized sequentially by a non-invasive NMR imaging procedure.

Magnetic Resonance Spectroscopy↗
PubMed2002

Systemic movement of a movement-deficient strain of Cucumber mosaic virus in zucchini squash is facilitated by a cucurbit-infecting potyvirus.

Zucchini squash (Cucurbita pepo) is a systemic host for most strains of the cucumovirus Cucumber mosaic virus (CMV), although the long-distance movement of the M strain of CMV (M-CMV) is inhibited in some cultivars. However, co-infection of zucchini plants with M-CMV and the potyvirus Zucchini yellow mosaic virus strain A (ZYMV-A) allowed M-CMV to move systemically, as demonstrated by tissue-print analysis. These doubly infected plants exhibited severe synergism in pathology. Infection of zucchini squash by M-CMV and an attenuated strain of ZYMV (ZYMV-AG) showed a milder synergy in pathology, in which ZYMV-AG also facilitated the long-distance movement of M-CMV similar to that promoted by ZYMV-A. Variation in the extent of synergy in pathology by the two strains of ZYMV did not correlate with differences in levels of accumulation of either virus. Thus, the extent of synergy in pathology is at least in part independent of the resistance-neutralizing function of the potyvirus.

Cucumovirus↗
PubMed2002

Functional analysis of a DNA-shuffled movement protein reveals that microtubules are dispensable for the cell-to-cell movement of tobacco mosaic virus.

Microtubules interact strongly with the viral movement protein (MP) of Tobacco mosaic virus (TMV) and are thought to transport the viral genome between plant cells. We describe a functionally enhanced DNA-shuffled movement protein (MP(R3)) that remained bound to the vertices of the cortical endoplasmic reticulum, showing limited affinity for microtubules. A single amino acid change was shown to confer the MP(R3) phenotype. Disruption of the microtubule cytoskeleton in situ with pharmacological agents, or by silencing of the alpha-tubulin gene, had no significant effect on the spread of TMV vectors expressing wild-type MP (MP(WT)) and did not prevent the accumulation of MP(WT) in plasmodesmata. Thus, cell-to-cell trafficking of TMV can occur independently of microtubules. The MP(R3) phenotype was reproduced when infection sites expressing MP(WT) were treated with a specific proteasome inhibitor, indicating that the degradation of MP(R3) is impaired. We suggest that the improved viral transport functions of MP(R3) arise from evasion of a host degradation pathway.

DNA, Viral↗
PubMed2002

Feature selection for the classification of movements from single movement-related potentials.

Classification of movement-related potentials recorded from the scalp to their corresponding limb is a crucial task in brain-computer interfaces based on such potentials. Many features can be extracted from raw electroencephalographic signals to be used for classification, but the utilization of irrelevant or superfluous features is detrimental to the performance of classification algorithms. It is, therefore, necessary to select a small number of relevant features for the classification task. This paper demonstrates the use of two feature selection methods to choose a small number (10-20) of relevant features from a bank containing upward of 1000 features. One method is based on information theory and the other on the use of genetic algorithms. We show that the former is poorly suited for the aforementioned classification task and discuss the probable reasons for this. However, using a genetic algorithm on data recorded from five subjects we demonstrate that it is possible to differentiate between the movements of two limbs with a classification accuracy of 87% using as little as 10 features without subject training. With the addition of a simple coding scheme, this method can be applied to multiple limb classification and a 63% classification accuracy rate can be reached when attempting to distinguish between three limbs.

Adult↗
PubMed1980

Studies of parkinsonian movement: 2. Initiation of fast voluntary eye movement during postural disturbance.

Delay in initiation of rapid voluntary eye movements (saccades) in bradykinetic parkinsonian patients and normal subjects was recorded with and without postural disturbances (rotation of the body and head). Parkinsonian patients as a group exhibited longer delays in the initiation of saccades. The delay increased during postural disturbance in both the patients and the normal subjects. The study failed to substantiate the hypothesis that postural reflexes interfere with the initiation of voluntary movement in Parkinsonism.

Adult↗
PubMed1999

Comparison of external load compensation during rhythmic arm movements and rhythmic jaw movements in humans.

Experiments were performed on human elbow flexor and extensor muscles and jaw-opening and -closing muscles to observe the effect on rhythmic movements of sudden loading. The load was provided by an electromagnetic device, which simulated the appearance of a smoothly increasing spring-like load. The responses to this loading were compared in jaw and elbow movements and between expected and unexpected disturbances. All muscles showed electromyographic responses to unexpected perturbations, with latencies of approximately 65 ms in the arm muscles and 25 ms in the jaw. When loading was predictable, anticipatory responses started in arm muscles approximately 200 ms before and in jaw muscles 100 ms before the onset of loading. The reflex responses relative to the anticipatory responses were smaller for the arm muscles than for the jaw muscles. The reflex responses in the arm muscles were the same with unexpected and expected perturbations, whereas anticipation increased the reflex responses in the jaw muscles. Biceps brachii and triceps brachii showed similar sensory-induced responses and similar anticipatory responses. Jaw muscles differed, however, in that the reflex response was stronger in masseter than in digastric. It was concluded that reflex responses in the arm muscles cannot overcome the loading of the arm adequately, which is compensated by a large centrally programmed response when loading is predictable. The jaw muscles, particularly the jaw-closing muscles, tend to respond mainly through reflex loops, even when loading of the jaw is anticipated. The differences between the responses of the arm and the jaw muscles may be related to physical differences. For example, the jaw was decelerated more strongly by the load than the heavier arm. The jaw was decelerated strongly but briefly, <30 ms during jaw closing, indicating that muscle force increased before the onset of reflex activity. Apparently, the force-velocity properties of the jaw muscles have a stabilizing effect on the jaw and have this effect before sensory induced responses occur. The symmetrical responses in biceps and triceps indicate similar motor control of both arm muscles. The differences in reflex activity between masseter and digastric muscle indicate fundamental differences in sensory feedback to the jaw-closing muscle and jaw-opening muscle.

Adult↗
PubMed1990

Studies of chemotactic, chemotactic movement-inhibiting and random movement-inhibiting effects of interleukin-1 alpha and beta, tumour necrosis factors alpha and beta and interferon gamma on human neutrophils in assays using 'sparse-pore' polycarbonate (Nuclepore) membranes in the Boyden chamber.

Interleukin-1 alpha and beta (IL-1 alpha and beta), tumour necrosis factors alpha and beta (TNF alpha and beta) and interferon gamma (IFN gamma) were tested for their chemotactic effects, their effects on chemotactic movement towards N-formyl-methionyl-leucyl-phenylalanine (FMLP) and their effects on random locomotion of human peripheral blood neutrophils through polycarbonate membranes in Boyden-type chambers. Both IL-1 alpha and beta, but no other cytokine tested were chemotactic for neutrophils using 'sparse-pore' polycarbonate membrane. Both TNFs, but no other cytokine, inhibited neutrophil chemotactic movement towards FMLP using the same membrane. No cytokine influenced random migration of neutrophils through polycarbonate membrane of standard pore density. These results suggest that IL-1 may have a role as a chemotactic mediator of inflammation, but that TNFs may inhibit chemotactic migration of neutrophils into inflammatory lesions.

Biological Factors↗
PubMed1998

[Effects of pregnancy on orthodontic tooth movements: effects of progesterone on orthodontic tooth movements in pregnant rats].

This study evaluated the periodontal responses and progesterone changes to orthodontic tooth movements in pregnant rats. Adult female Sprague-Dawley rats were separated into two groups: non-pregnant and pregnant. All rats were treated with fixed orthodontic appliances that moved the upper incisors in a distal direction during 10 days. At the end of the experiment, the periodontal tissues were examined histologically and immunohistochemically (ABC method). The results showed that in the histological examination of the tension sides of the upper incisors, the bone formation was more obvious in the pregnant group than that in the non-pregnant group. In the immunohistochemical staining, the osteoblasts were positive-stained cells and they exhibited deeper stain and higher percentage in the pregnant group. In a conclusion, the progesterone influences the periodontal reconstruction on orthodontic tooth movements in pregnant rats and may be helpful in alveolar bone formation, which suggests that orthodontic treatments in pregnant patients may not be so harmful as people thought before.

Animals↗
PubMed1991

[Arrangement of neuromuscular movement cycles of free mandibular movements following Le Fort I-operations].

In orthognathic surgery the Le Fort I osteotomy changes the structure of motion of the mandible. This structure and its changes could reliably and quantitatively be described if it was evaluated by a projection of the mandibular movement upon a couple's movement in a gearing system. The comparison of Le Fort I cases with orthodontically treated class-I-cases shows significant differences.

Adult↗
PubMed1998

Ablative therapy for movement disorders. Complications in the treatment of movement disorders.

Presently, there is a renaissance in the surgical treatment of movement disorders. Prompted by the growing recognition of the limitations of drug therapy, this resurgence has been further promoted by progress in neuronal transplantation, advances in neuroimaging and stereotactic surgical techniques, and innovative therapies, such as deep brain stimulation for abnormal movements. Mortality associated with thalamotomy and pallidotomy is rare, but morbidity is not inconsiderable, particularly in the elderly and those with preexisting brain damage. Judicious patient selection and physiologic confirmation of stereotactic targets are cornerstones to complication avoidance.

Antiparkinson Agents↗
PubMed1985

Both electrical and chemical transmission between the 'lobula giant movement detector' and the 'descending contralateral movement detector' neurons of locusts are supported by electron microscopy.

Conventional electron microscopy combined with cobalt staining techniques has revealed chemical synapses and gap junction-like areas denoting specific regions of contact between two large, uniquely identifiable visual interneurons in the brain of the locust Schistocerca gregaria. The morphological demonstration of chemical synapses suggests that one of the two neurons, the 'descending contralateral movement detector', receives a chemically mediated input from its main presynaptic element, the 'lobula giant movement detector'. This observation supports recent electrophysiological studies demonstrating synaptic delays between the two cells, characteristic of chemical synapses. However, regions with the appearance of gap junctions are also observed. This corroborates earlier work which suggested that these two neurons are coupled electrically.

Animals↗
PubMed1986

Decision-making to initiate voluntary movements in the rat is altered during deprivation of rapid eye movement sleep.

Eight male rats were deprived of rapid eye movement (REM) sleep for 6 days by means of a cuff pedestal which makes it possible to use the animal as its own control. In order to obtain access to food, the rat had to jump from its pedestal to a strip of wire mesh suspended from the ceiling of the deprivation chamber. The number as well as duration of hangings on the wire mesh was continuously recorded. An initial increase in jumping frequency was associated with decreased duration of hangings. This initial effect was totally reversed from the fourth day of deprivation onwards. It is suggested that the threshold in decision making to initiate voluntary movement is altered during the course of REM sleep deprivation.

Animals↗
PubMed2006

Periodic leg movements in sleep and periodic limb movement disorder: prevalence, clinical significance and treatment.

Periodic leg movements in sleep (PLMS) are a frequent finding in polysomnography. The prevalence of PLMS is estimated to be 4-11% in adults. In childhood, PLMS rarely occur although medical conditions like sleep apnea syndrome or neuropsychiatric disorders can lead to high rates of PLMS. In the elderly, PLMS are also common in subjects without sleep disturbances. In sleep studies, PLMS are found most frequently in restless legs syndrome (RLS) and often occur in narcolepsy, sleep apnea syndrome and REM sleep behavior disorder. Some patients with otherwise unexplained insomnia or hypersomnia reveal an elevated number of PLMS, a condition defined as periodic limb movement disorder (PLMD). PLMS were found also in various medical and neurological disorders that do not primarily affect sleep. A summary of these is presented. In sleep disorders related to dopaminergic dysfunction such as RLS, PLMS are considered to be a symptom of the disease. In other disorders like primary insomnia, the clinical relevance of PLMS is still being controversially discussed. Studies with findings both pro and contra are referred. To date, only a few studies have evaluated the efficacy of therapeutic substances in reducing PLMS in PLMD patients. Their results need to be confirmed in controlled randomized trials.

Aged↗
PubMed2001

The organization of rapid eye movement activity during rapid eye movement sleep is further impaired in very old human subjects.

Rapid eye movement activity (REMA) during rapid eye movement (REM) sleep was studied in seven very old ('old-old') subjects. Beyond global quantitative features (REMA density), we evaluated the organizational aspects of REMA, that is its occurrence in burst mode, which were compared to a group of younger elderly subjects ('young-old'). REMA density in 'old-old' subjects is not significantly different from that of 'young-old' subjects. The same lack of difference in the two groups is found for the number of REMA bursts. By contrast, the duration of REMA bursts is reduced in the 'old-old' subjects, as well as the 'burst state-to-burst-state' probability, i.e. the probability for successive inter-REMA time intervals to be part of the same REMA burst. Our results clearly show that the trend towards an impairment of REMA organizational aspects continues with aging. This is consistent with the hypothesis that sleep disorganization keeps worsening with age. However, it is of interest to observe that the capability of producing REMA bursts is preserved despite aging.

Age Factors↗