Proprioception during voluntary movement

1986 ◽  
Vol 64 (4) ◽  
pp. 499-504 ◽  
Author(s):  
Arthur Prochazka
Keyword(s):  
Human Subjects ◽  
Tonic Component ◽  
Divergence Of Opinion ◽  
Significant Divergence ◽  
Length Changes ◽  
Low Levels ◽  
Fusimotor System ◽  
Awake Cats ◽  
Tendon Organ ◽  
Shortening Contractions

In the last decade, a number of laboratories have accumulated data on the firing of single afferent fibres from muscle and skin during movement in awake cats, monkeys and human subjects. While there is general agreement on the firing behaviour of skin afferents and tendon organ (Ib) afferents during movement, there remains a significant divergence of opinion regarding the way in which the response of muscle spindle afferents (Ia and II) to length changes is modified by fusimotor action (e.g., alpha–gamma linkage versus "fusimotor set"). The controversies surrounding the fusimotor system have tended to overshadow the emergence of several important characteristics of propioceptive behaviour, corroborated in separate laboratories, (i) Mean la firing rates during active movements are nearly always higher than at rest. Thus, activation of the fusimotor system is reserved for the control of, or preparation for, movement. In animals, there is now strong evidence that there is usually a tonic component of fusimotor action during rhythmical movements. (ii) During fast, unloaded movements (peak muscle speeds, 0.2 resting lengths/s or more), the firing of both la and II afferents usually increases during lengthening and decreases during shortening. Ib afferents fire during even the most rapid active shortening of their parent muscles, (iii) During powerful shortening contractions performed against significant loads, la firing is often appreciable, suggesting that there is at least some underlying alpha–gamma coactivation. (iv) During fast imposed muscle stretches, la afferents respond with segmented bursts of firing (threshold speed for segmentation, 0.5–1.0 resting length/s). Ib afferents show far less segmentation of discharge under similar circumstances, (v) There are substantial numbers of tendon organ receptors which fire during tasks involving low levels of force.

Effects of muscle shortening on the responses of cat tendon organs to unfused contractions

1988 ◽  
Vol 59 (5) ◽  
pp. 1510-1523 ◽  
Author(s):  
G. Horcholle-Bossavit ◽  
L. Jami ◽  
J. Petit ◽  
R. Vejsada ◽  
D. Zytnicki
Keyword(s):  
Motor Units ◽  
Tension Development ◽  
Golgi Tendon Organs ◽  
Dynamic Sensitivity ◽  
Single Motor Units ◽  
Muscle Shortening ◽  
Length Changes ◽  
Tendon Organs ◽  
Tendon Organ ◽  
Shortening Contractions

1. The discharges from individual Golgi tendon organs of peroneus tertius and brevis muscles were recorded in anesthetized cats. Responses to unfused isometric contractions of single motor units and combinations of motor units were compared with responses to contractions eliciting muscle shortening (i.e., shortening contractions). 2. In 75% of the examined instances, the effect of muscle shortening during unfused contractions was a slight decrease in tendon organ activation, in keeping with the reduction of contractile tension recorded at the muscle tendon. In other instances there was either no change in tendon organ response or, in less than 10% of instances, a slight increase For two motor units eliciting similar activation of a given tendon organ under isometric conditions, the effect of shortening contraction was not necessarily the same. 3. The reductions observed in tendon organ discharges upon muscle shortening were less than proportional to the reductions of contractile tension and difficult to correlate with the properties of motor units, as determined under isometric conditions. The present observations suggest three main reasons for this lack of relation. 4. The first reason depended on the properties of motor units, in that the relation between length changes and tension changes was not the same for all units. Two motor units developing similar isometric tensions did not necessarily produce the same degree of muscle shortening. Some units produced relatively significant shortening without much loss of tension. 5. Second, the dynamic sensitivity of tendon organs is known to exert a major influence on their responses to isometric unfused contractions, accounting for 1:1 driving of discharge during tension oscillations and high frequency bursts upon abrupt increase of tension. Although less tension was produced and the rate of tension development was slower in shortening contractions, similar manifestations of the dynamic sensitivity of tendon organs were observed. In such cases, the responses of tendon organs were the same whether or not the muscle shortened during contraction. 6. Third, when several motor units were stimulated in combination, the unloading influences of in-parallel units were facilitated by muscle shortening so that unloading effects, which were hardly visible under isometric conditions became evident during shortening contractions.

Prevalence and Induction of Circulating Antibodies against Recombinant Staphylokinase

1994 ◽  
Vol 71 (01) ◽  
pp. 129-133 ◽  
Author(s):  
P J Declerck ◽  
S Vanderschueren ◽  
J Billiet ◽  
H Moreau ◽  
D Collen
Keyword(s):  
Intravenous Administration ◽  
Human Subjects ◽  
Microtiter Plates ◽  
Staphylococcus Aureus Bacteremia ◽  
Alternative Agent ◽  
Antibody Titers ◽  
Potential Alternative ◽  
Circulating Antibodies ◽  
Low Levels ◽  
Antibody Levels

SummaryStreptokinase (SK) is a routinely used thrombolytic agent but it is immunogenic and allergenic; staphylokinase (STA) is a potential alternative agent which is under early clinical evaluation. The comparative prevalence of antibodies against recombinant STA (STAR) and against SK was studied in healthy subjects and their induction with intravenous administration in small groups of patients.Enzyme-linked immunosorbent assays, using microtiter plates coated with STAR or SK and calibration with affinospecific human antibodies, revealed 2.1 to 65 μg/ml (median 11 μg/ml) anti-STAR antibodies and 0.9 to 370 μg/ml (median 18 μg/ml) anti-SK antibodies (p <0.001 vs anti-STAR antibodies) in plasma from 100 blood donors, with corresponding values of 0.6 to 100 μg/ml (median 7.1 μg/ml) and 0.4 to 120 μg/ml (median 7.3 μg/ml), respectively, in 104 patients with angina pectoris. Three out of 17 patients with Staphylococcus aureus bacteremia had significantly increased anti-STAR antibody levels (150, 75 and 75 μg/ml), and STAR neutralizing activities (2.2, 3.6 and 4.1 μg STAR neutralized per ml plasma, respectively). In 6 patients with acute myocardial infarction, given 10 mg STAR intravenously over 30 min, median anti-STAR antibody levels were 3.5 μg/ml at baseline, 2.9 μg/ml at 6 to 8 days and 1.2 μg/ml at 2 to 9 weeks, with median corresponding titers of STAR neutralizing activity at 2 to 9 weeks of 42 μg/ml plasma. Conversely, in 5 patients treated with 1,500,000 units SK over 60 min, median anti-SK antibodies increased from 2.9 μg/ml at baseline to 360 μg/ml at 5 to 10 days, with corresponding median SK neutralizing activities of 13 μg/ml. Antibodies against STAR did not cross-react with SK and vice versa.Plasma from human subjects contains low levels of circulating antibodies against recombinant staphylokinase, and intravenous administration of this compound boosts antibody titers. These antibodies do however not cross-react with streptokinase, whereby the use of these two immunogenic thrombolytic agents would not be mutually exclusive.

scholarly journals Human Subjects Requirements and Economic Education Researchers

2007 ◽  
Vol 51 (2) ◽  
pp. 49-60 ◽  
Author(s):  
Jane S. Lopus ◽  
Paul W. Grimes ◽  
William E. Becker ◽  
Rodney A. Pearson
Keyword(s):  
Human Subjects ◽  
Economic Education ◽  
Opportunity Costs ◽  
Federal Regulations ◽  
Research Projects ◽  
Human Subjects Research ◽  
Web Based ◽  
American Universities ◽  
Net Benefits ◽  
Low Levels

This paper presents the results of a web-based survey of economic educators who were asked about their knowledge and experience with human subjects research and the mandated federal protocols that govern such research at most American universities. The results indicate that while economic education researchers are experienced in conducting human subjects research and are aware of the federal regulations, they are not well informed about key details of the regulations. They are skeptical of the net benefits of the mandated protocols because of the perceived discouraging burdens of the paperwork that rarely result in significant modifications of their research projects. The authors conclude that recent calls for modifications to the federal regulations for classroom-based research projects may be justified given the opportunity costs of adhering to the regulations compared to the relatively low levels of perceived benefits.

Regulation of PaCO2 and ventilation in humans inspiring low levels of CO2

1982 ◽  
Vol 52 (2) ◽  
pp. 287-294 ◽  
Author(s):  
H. V. Forster ◽  
J. P. Klein ◽  
L. H. Hamilton ◽  
J. P. Kampine
Keyword(s):  
Measurement Error ◽  
Experimental Design ◽  
Human Subjects ◽  
Consistent Difference ◽  
Arterial Pco2 ◽  
Arterial Blood ◽  
Apparent Reason ◽  
Low Levels ◽  
Isocapnic Hyperpnea ◽  
Sensory Mechanism

This study was designed to determine whether 1) arterial PCO2 (PaCO2) increases when inspired PCO2 (PICO2) is increased from less than 0.4 Torr (eupnea) to 7 or 14 Torr, and 2) ventilatory sensitivity to CO2 (delta VE/ delta PaCO2) is greater at low levels of PICO2 (7–21 Torr) than it is at higher levels (28–42 Torr). Human subjects were studied while seated in an environmental chamber that permitted alteration of PICO2 by changing the chamber PCO2. In study 1, arterial blood was sampled over the final 5 min of a eupneic period and again 10–15 min later when PICO2 was 7 or 14 Torr. With this protocol, PACO2 was increased above eupnea by 0.7 (P less than 0.02) and 0.9 Torr (P less than 0.01) when PICO2 was 7 and 14 Torr, respectively. In study 2, arterial blood was sampled every 5 min during two 1-h periods of eupnea that were separated by 3 h during which PICO2 was increased by 7 Torr each 0.5 h. With this protocol there was no consistent difference in PACO2 between eupneic periods and periods when PICO2 was 7–14 Torr. There was a progressively increased hypercapnia as PICO2 was increased from 7 to 42 Torr. The delta VE/ delta PaCO2 was less than half for data obtained at low relative to high PICO2. The two studies demonstrated that measurement error and physiologic variation necessitate using a “powerful” experimental design (study 1) to detect small increases in PaCO2. On the basis of these results, we have concluded that there is no apparent reason to postulate a sensory mechanism other than the carotid and intracranial chemoreceptors to account for the hyperpnea during CO2 inhalation. Specifically, isocapnic hyperpnea probably does not occur.

Activity of spindle afferents from cat anterior thigh muscles. III. Effects of external stimuli

1985 ◽  
Vol 54 (3) ◽  
pp. 578-591 ◽  
Author(s):  
G. E. Loeb ◽  
J. A. Hoffer ◽  
W. B. Marks
Keyword(s):  
Motor Program ◽  
Sartorius Muscle ◽  
Muscle Spindle Afferents ◽  
Implanted Electrodes ◽  
Hamstring Muscles ◽  
Highly Sensitive ◽  
Motoneuron Activity ◽  
Fusimotor System ◽  
External Stimuli ◽  
Awake Cats

Chronically implanted electrodes were used to record the activity of identified single muscle spindle afferents in awake cats during responses to various types of manual and electrical stimulation. During vigorous cyclical responses such as shaking and scratching, spindle afferents generally maintained at least some activity during both lengthening and shortening of the parent muscle, indicating that the programs for these movements include both extra- and intrafusal recruitment. During noncyclical responses such as ipsilateral limb withdrawal and crossed-extension, spindle activity was modest and poorly correlated with extrafusal activity. Weak cutaneous nerve shocks during walking elicited complex excitatory and inhibitory phase-dependent reflexes in the various muscles studied but caused relatively little change in spindle afferent activity, indicating a lack of correlation between alpha and gamma motoneuron activity. A primary and a secondary afferent from sartorius muscle were recorded simultaneously during walking cycles that were perturbed by electrically induced twitches of the antagonist hamstring muscles; both demonstrated highly sensitive, short latency responses to the resulting skeletal motion, consistent with their previously suggested roles in detecting small brief mechanical perturbations. The degree to which fusimotor responses were correlated with extrafusal responses to somatosensory perturbations was highly dependent on the specific nature of the stimulus and the response. Fusimotor reprogramming of the spindle sensitivity appears to be a feature of cyclical movements that are presumably under proprioceptive control, whereas brief perturbations within the context of a particular motor program may be ignored by the fusimotor system.

scholarly journals Natural selection at the RASGEF1C (GGC) repeat in human and divergent genotypes in late-onset neurocognitive disorder

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Z. Jafarian ◽  
S. Khamse ◽  
H. Afshar ◽  
H.R. Khorram Khorshid ◽  
A. Delbari ◽  
...  
Keyword(s):  
Natural Selection ◽  
Late Onset ◽  
Core Promoter ◽  
Human Subjects ◽  
Primate Species ◽  
Control Group ◽  
Specific Gene ◽  
Repeat Allele ◽  
The Status ◽  
Significant Divergence

AbstractExpression dysregulation of the neuron-specific gene, RASGEF1C (RasGEF Domain Family Member 1C), occurs in late-onset neurocognitive disorders (NCDs), such as Alzheimer’s disease. This gene contains a (GGC)13, spanning its core promoter and 5′ untranslated region (RASGEF1C-201 ENST00000361132.9). Here we sequenced the (GGC)-repeat in a sample of human subjects (N = 269), consisting of late-onset NCDs (N = 115) and controls (N = 154). We also studied the status of this STR across various primate and non-primate species based on Ensembl 103. The 6-repeat allele was the predominant allele in the controls (frequency = 0.85) and NCD patients (frequency = 0.78). The NCD genotype compartment consisted of an excess of genotypes that lacked the 6-repeat (divergent genotypes) (Mid-P exact = 0.004). A number of those genotypes were not detected in the control group (Mid-P exact = 0.007). The RASGEF1C (GGC)-repeat expanded beyond 2-repeats specifically in primates, and was at maximum length in human. We conclude that there is natural selection for the 6-repeat allele of the RASGEF1C (GGC)-repeat in human, and significant divergence from that allele in late-onset NCDs. STR alleles that are predominantly abundant and genotypes that deviate from those alleles are underappreciated features, which may have deep evolutionary and pathological consequences.

scholarly journals The Potential Benefits of Therapeutic Treatment Using Gaseous Terpenes at Ambient Low Levels

2019 ◽  
Vol 9 (21) ◽  
pp. 4507 ◽  
Author(s):  
Jo-Chun Kim ◽  
Trieu-Vuong Dinh ◽  
Hong-Keun Oh ◽  
Youn-Suk Son ◽  
Ji-Won Ahn ◽  
...  
Keyword(s):  
Human Subjects ◽  
Detection Threshold ◽  
Stress Index ◽  
Therapeutic Effects ◽  
Mean Values ◽  
Psychological Conditions ◽  
Forest Bathing ◽  
Potential Benefits ◽  
Low Levels ◽  
Alpha Waves

Biological volatile organic compounds (BVOCs) are emitted abundantly from the flora. Among BVOCs, monoterpenes (MTs) have been used for aromatherapy (e.g., forest bathing) to treat human physiological and psychological conditions. However, relatively little is known about the therapeutic effects of MTs at low part per billion by volume (ppbv) levels. The effects of artificial MTs on human subjects were assessed by both olfactory and therapeutic parameters (brain alpha waves and stress index). Gaseous standards of three monoterpenes (i.e., α-pinene, β-pinene, and d-limonene) prepared at low ppbv levels were used individually and as mixtures. Fifty-nine healthy and non-asthmatics volunteer university students were selected for the test. All human subjects inhaled low ppbv levels of monoterpene in the testing room. Brain alpha waves and stress index were investigated during the inhalation time. Questionnaires were also used after testing. It was found that the detection threshold of MTs was close to 5 ppbv. When the MT levels increased from 0 to 20 ppbv, the mean values of brain alpha waves derived from all participants increased from 9.8 to 15.1. In contrast, the stress index values declined from 46.2 to 34.7. The overall results suggest that MTs have great potential to positively affect the relaxation state of subjects in a manner similar to forest bathing in terms of short-term effect. They can thus be applied as potential therapeutic media for mental health care.

scholarly journals Experience using pipeline embolization device with Shield Technology in a patient lacking a full postoperative dual antiplatelet therapy regimen

2018 ◽  
Vol 24 (3) ◽  
pp. 270-273 ◽  
Author(s):  
Kirill Orlov ◽  
Dmitry Kislitsin ◽  
Nikolay Strelnikov ◽  
Vadim Berestov ◽  
Anton Gorbatykh ◽  
...  
Keyword(s):  
Antiplatelet Therapy ◽  
Thromboembolic Event ◽  
Dual Antiplatelet Therapy ◽  
Human Subjects ◽  
Thromboembolic Events ◽  
Pipeline Embolization Device ◽  
Therapy Regimen ◽  
Hemorrhagic Complications ◽  
Luminal Stenosis ◽  
Low Levels

Utilization of flow diverting devices is accompanied with dual antiplatelet therapy to reduce the risk of thromboembolic events, even though this increases the risk of hemorrhagic complications. The updated Pipeline Flex embolization device with Shield Technology has been created using a phosphorylcholine coating that reduces thrombogenicity and possibly reduces the need for dual antiplatelet therapy. However, because of the potential risk to patients of utilizing a pipeline embolization device without dual antiplatelet therapy, the pipeline embolization device with Shield Technology has not been tested in human subjects without dual antiplatelet therapy, and its contribution to preventing thromboembolic events is therefore unknown. We report a case in which a patient, following complications that limited his absorption of dual antiplatelet therapy, had low levels of dual antiplatelet therapy medications in his bloodstream following treatment for an intracranial aneurysm with a pipeline embolization device with Shield Technology. The patient recovered without signs of luminal stenosis or thromboembolic event.

scholarly journals Directional Gene Movement from Human-Pathogenic to Commensal-Like Streptococci

2001 ◽  
Vol 69 (8) ◽  
pp. 4858-4869 ◽  
Author(s):  
Awdhesh Kalia ◽  
Mark C. Enright ◽  
Brian G. Spratt ◽  
Debra E. Bessen
Keyword(s):  
Genetic Relatedness ◽  
Human Subjects ◽  
Housekeeping Genes ◽  
Group A Streptococci ◽  
Highly Pathogenic ◽  
Evolution Of Virulence ◽  
Genotypic Analysis ◽  
History Of ◽  
Group A ◽  
Low Levels

ABSTRACT Group A streptococci (GAS) are highly pathogenic for humans, and their closest genetic relatives, group C and G streptococci (GCS and GGS, respectively), are generally regarded as commensals, although they can be found in association with human disease. As part of an effort to better understand the evolution of virulence, the phylogenetic relationships between GAS, GCS, and GGS were examined. The nucleotide sequence was determined for an internal portion of seven housekeeping (neutral) loci among >200 isolates of GAS and 34 isolates of GCS or GGS obtained from human subjects. Genotypic analysis failed to show support for the separation of GCS and GGS into two distinct populations. Unlike GAS, there was poor concordance betweenemm type and genetic relatedness among GCS and GGS. All housekeeping genes within GAS displayed relatively low levels of sequence diversity. In contrast, individual GCS and GGS strains had mosaic genomes, containing alleles at some loci that were similar or identical to GAS alleles, whereas the alleles at other loci were about 10 to 30% diverged. The data provide evidence for a history of recent interspecies transfer of neutral genes that exhibits a strong net directionality from GAS donors to GCS and GGS recipients. A model for the evolution of GAS and of GCS and GGS is described.

scholarly journals Novel biological implication of a strictly monomorphic GCC repeat in the human PRKACB gene

2021 ◽  
Author(s):  
Safoura Khamse ◽  
Zahra Jafarian ◽  
Ali Bozorgmehr ◽  
Mostafa Tavakoli ◽  
Hossein Afshar Iranian ◽  
...  
Keyword(s):  
Late Onset ◽  
Human Subjects ◽  
Three Dimensional ◽  
Dna Structure ◽  
Dimensional Structure ◽  
Protein Coding ◽  
Three Dimensional Structure ◽  
Significant Divergence ◽  
The Impact ◽  
The Brain

Abstract Across human protein-coding genes, PRKACB (Protein Kinase CAMP-Activated Catalytic Subunit Beta) contains one of the longest GCC-repeats, and is predominantly expressed in the brain. Here we studied this STR in 300 human subjects, consisting of late-onset neurocognitive disorder (NCD) (N = 150) and controls (N = 150). We also studied the impact of this STR on the three-dimensional structure of DNA. While the PRKACB GCC-STR was strictly monomorphic at 7-repeats, we detected two 7/8 genotypes only in the NCD group. In comparison to all other lengths, (GCC)7 had the least effect on the three-dimensional structure of DNA, evidenced by minimal divergence between 0 and 7-repeats (divergence score = 0.04) and significant divergence between 0 and 8 repeats (divergence score = 0.50). A similar inert effect to the GCC-repeat was not detected in other classes of STRs such as GA and CA repeats. In conclusion, we report monomorphism of an exceptionally long GCC repeat in the PRKACB gene in human, its inert effect on DNA structure, and divergence in two cases of late-onset NCD. This is the first indication of natural selection for an exceptionally long monomorphic GCC-repeat, which probably evolved to function as an “epigenetic knob”, without changing the regional DNA structure.

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