CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - ACTIVATION PATTERNS IN VIVO

1994 ◽  
Vol 187 (1) ◽  
pp. 261-274
Author(s):  
R Josephson ◽  
D Stokes
Keyword(s):  
Coefficient Of Variation ◽  
High Frequency ◽  
Interspike Interval ◽  
Carcinus Maenas ◽  
Single Muscle ◽  
Stroke Frequency ◽  
Activation Patterns ◽  
Animal Mass ◽  
Animal Size

1. The flagella of crustaceans are small appendages, borne on the maxillipeds, which beat repetitively when active. Flagellar movement is brought about by contraction of a single muscle, the flagellum abductor (FA). 2. The stroke frequency of the flagella of the green crab, Carcinus maenas, was about 11 Hz at 15 °C and was relatively independent of animal size [frequency is proportional to (animal mass)-0.07], even though scaling considerations suggest that, for constant muscle stress, frequency should be proportional to mass-0.33. The coefficient of variation for intervals between successive strokes of a flagellum was about 4 %. 3. The FA is innervated by two excitatory motoneurones. Each of the neurones fired 0­5 times during a stroke. The interspike interval when a neurone fired more than once during a stroke was 3­4 ms.

CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - CONTRACTION KINETICS

1994 ◽  
Vol 187 (1) ◽  
pp. 275-293 ◽  
Author(s):  
D Stokes ◽  
R Josephson
Keyword(s):  
High Frequency ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Length Change ◽  
Shortening Velocity ◽  
Long Duration ◽  
Maximum Isometric Force ◽  
Small Muscle

1. The flagella (small appendages on the maxillipeds) of the crab Carcinus maenas beat regularly when active at about 10 Hz (15 °C). The beat of a flagellum is due to contraction of a single small muscle, the flagellum abductor (FA). The optimal stimulus frequency for tetanic contraction of the FA was about 200 Hz. When the muscle was stimulated at 10 Hz with paired stimuli per cycle, the interstimulus interval that maximized peak force was 2­4 ms, which corresponded well to the interspike intervals within bursts recorded from motor axons during normal beating. 2. Contraction of the isolated FA showed pronounced neuromuscular facilitation and many stimuli were needed to activate the muscle fully. The dependence on facilitation in isolated muscles appeared to be greater than that in vivo. It is suggested that neuromodulators in the blood of the crab enhance neuromuscular transmission and reduce the dependency on facilitation in intact animals. 3. The FA had a narrow length­tension curve. Tetanic tension became vanishingly small at muscle lengths less than about 90 % of the maximum in vivo length. The maximum length change of the muscle during in vivo contraction was about 5 %. 4. The maximum isometric force of the FA was low (about 6 N cm-2) but its shortening velocity was high. Vm, the maximum shortening velocity determined from isotonic shortening, was 4.0 muscle lengths s-1; V0, the maximum shortening velocity from slack test measurements, was about 8 lengths s-1. 5. The structure and physiology of the FA are compared with those of locust flight muscle, chosen because it too is a muscle capable of long-duration, high-frequency performance.

CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - MECHANICAL POWER OUTPUT

1994 ◽  
Vol 187 (1) ◽  
pp. 295-303 ◽  
Author(s):  
R Josephson ◽  
D Stokes
Keyword(s):  
Power Output ◽  
High Frequency ◽  
Carcinus Maenas ◽  
Mechanical Power ◽  
Abductor Muscle ◽  
Mechanical Power Output ◽  
Loop Technique ◽  
Number Of Cycles ◽  
Work Loop

The mechanical power output during oscillatory contraction was determined for the flagellum abductor muscle of the crab Carcinus maenas using the work loop technique. Measurements were made at 10 Hz, which is the normal operating frequency of the muscle. The temperature was 15 °C. Increasing the number of stimuli per cycle (given at an interstimulus interval of 3.3 ms) decreased the number of cycles required to reach a work plateau and increased the work per cycle at the plateau to a maximum at 4­5 stimuli per cycle. The maximum mechanical power output was 9.7 W kg-1 muscle (about 26 W kg-1 myofibril). The optimum strain for work output (5.7 %) was close to the estimated muscle strain in vivo (5.2 %).

Аpplying of high-frequency monopolar diathermocoagulation in the treatment of chronic pulpitis

2020 ◽  
Vol 1 (12) ◽  
pp. 40-42
Author(s):  
F. Yu. Daurova ◽  
D. I. Tomaeva ◽  
S. V. Podkopaeva ◽  
Yu. A. Taptun
Keyword(s):  
Root Canal ◽  
High Frequency ◽  
Antibacterial Effect ◽  
Comparison Group ◽  
Poor Quality ◽  
Endodontic Treatment ◽  
Root Canals ◽  
The Third ◽  
Before And After

Relevance: the reason for the development of complications in endodontic treatment is poor-quality instrumental treatment root canals.Aims: a study of the animicrobial action and clinical efficacy of high-frequency monopolar diathermocoagulation in the treatment of chronic forms of pulpitis.Materials and methods: 102 patients with various chronic forms of pulpitis were divided into three groups of 34 patients each. In the first two groups, high-frequency monopolar diathermocoagulation was used in endodontic treatment in different modes. In the third group, endodontic treatment was carried out without the use of diathermocoagulation (comparison group). The root canal microflora in chronic pulpitis in vivo was studied twice-before and after diathermocoagulation.Results: it was established that high-frequency monopolar diathermocoagulation in the effect mode is 3, power is 4 (4.1 W) and effect is 4, power is 4 (5.4 W) with an exposure time of 3 seconds, it has a pronounced antibacterial effect on all presented pathogenic microflora obtained from the root canals of the teeth.

Arterial Thrombus Dissolution In Vivo Using a Transducer-Tipped, High-Frequency Ultrasound Catheter and Local Low-Dose Urokinase Delivery

2001 ◽  
Vol 8 (3) ◽  
pp. 282-290 ◽  
Author(s):  
Shaul Atar ◽  
Huai Luo ◽  
Tomoo Nagai ◽  
Roger A. Sahm ◽  
Michael C. Fishbein ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Dose ◽  
High Frequency Ultrasound ◽  
Arterial Thrombus ◽  
Frequency Ultrasound

Bone heating and implant removal using a high‐frequency electrosurgical device. An in vivo experimental study

2021 ◽  
Author(s):  
Atsushi Kawamura ◽  
Yosuke Akiba ◽  
Masako Nagasawa ◽  
Makiko Takashima ◽  
Yoshiaki Arai ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Frequency ◽  
Implant Removal

scholarly journals Selective elimination of immunosuppressive T cells in patients with multiple myeloma

Leukemia ◽  
2021 ◽  
Author(s):  
Mohamed H. S. Awwad ◽  
Abdelrahman Mahmoud ◽  
Heiko Bruns ◽  
Hakim Echchannaoui ◽  
Katharina Kriegsmann ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
Immune Responses ◽  
High Frequency ◽  
Surface Markers ◽  
Selective Elimination ◽  
Related Transcription Factor ◽  
Cell Membrane Protein

AbstractElimination of suppressive T cells may enable and enhance cancer immunotherapy. Here, we demonstrate that the cell membrane protein SLAMF7 was highly expressed on immunosuppressive CD8+CD28-CD57+ Tregs in multiple myeloma (MM). SLAMF7 expression associated with T cell exhaustion surface markers and exhaustion-related transcription factor signatures. T cells from patients with a high frequency of SLAMF7+CD8+ T cells exhibited decreased immunoreactivity towards the MART-1aa26–35*A27L antigen. A monoclonal anti-SLAMF7 antibody (elotuzumab) specifically depleted SLAMF7+CD8+ T cells in vitro and in vivo via macrophage-mediated antibody-dependent cellular phagocytosis (ADCP). Anti-SLAMF7 treatment of MM patients depleted suppressive T cells in peripheral blood. These data highlight SLAMF7 as a marker for suppressive CD8+ Treg and suggest that anti-SLAMF7 antibodies can be used to boost anti-tumoral immune responses in cancer patients.

Interspike interval dependency from arterial chemoreceptors

1985 ◽  
Vol 59 (5) ◽  
pp. 1566-1570 ◽  
Author(s):  
D. F. Donnelly ◽  
W. F. Nolan ◽  
E. J. Smith ◽  
R. E. Dutton
Keyword(s):  
Carotid Body ◽  
Interspike Interval ◽  
Correlation Coefficients ◽  
Feedback System ◽  
Serial Dependence ◽  
Control Series ◽  
First Order ◽  
System Operating ◽  
Poisson Type

The carotid body impulse generator has been previously characterized as a Poisson-type random process. We examined the validity of this characterization by analyzing sinus nerve spike trains for interspike interval dependency. Fifteen single chemoreceptive afferents were recorded in vivo under hypoxic-hypercapnic conditions, and approximately 1,000 consecutive interspike intervals for each fiber were timed and analyzed for serial dependence. The same set of intervals placed in shuffled order served as a control series without serial dependence. The original spike interval trains showed significantly negative first-order serial correlation coefficients and less variability in joint interval distributions than did the shuffled interval trains. These results suggest that the chemoreceptor afferent train is not random and may reflect a negative feedback system operating within the carotid body that limits variation about a mean frequency.

High-Frequency Yarn Tension Variations in Spinning

1980 ◽  
Vol 102 (1) ◽  
pp. 45-50
Author(s):  
E. Dyson ◽  
G. Afshari
Keyword(s):  
Experimental Investigation ◽  
Periodic Structure ◽  
Coefficient Of Variation ◽  
Rotational Speed ◽  
High Frequency ◽  
Ring Spinning ◽  
Statistical Parameters ◽  
Yarn Tension ◽  
Rotor Spinning

A description of an experimental investigation of the variations in yarn tension during both ring and rotor open-end spinning which have frequencies equal to, or greater than, the rotational speed of the system is given. Typical results are illustrated and discussed both in terms of statistical parameters such as the coefficient of variation and in terms of their spectra. Tension variations during rotor spinning are shown to have, in general, a much less pronounced periodic structure then the corresponding variations during ring spinning.

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