Search results for "contraction"

Partial isometries and the conjecture of C.K. Fong and S.K. Tsui

2016

Abstract We investigate some bounded linear operators T on a Hilbert space which satisfy the condition | T | ≤ | Re T | . We describe the maximum invariant subspace for a contraction T on which T is a partial isometry to obtain that, in certain cases, the above condition ensures that T is self-adjoint. In other words we show that the Fong–Tsui conjecture holds for partial isometries, contractive quasi-isometries, or 2-quasi-isometries, and Brownian isometries of positive covariance, or even for a more general class of operators.

Role of JAK2/STAT3 pathway in vascular function of pulmonary fibrosis patients

2015

Background: Idiopathic Pulmonary Fibrosis (IPF) is a chronic progressive lung disease with a life expectancy of 2-5 years. A proportion of IPF patients develop pulmonary hypertension (PH), characterized by vasoconstriction and remodeling of pulmonary arteries. Currently, no therapy can improve survival of patients diagnosed with this disease. JAK2/STAT3 molecular route is overexpressed in proliferative disorders, however, its role in PH- associated IPF is unknown. Objective: To analyze the role of JAK2/STAT3 in vascular function of IPF patients with PH. We hypothesized that inhibition of JAK2, STAT3 or JAK2/STAT3 may improve vascular function. Methods: Human precision cut lung slices and ar…

Muscle activity in upper and lower rectus abdominus during abdominal exercises.

1996

Abstract Objective: To compare the intensity of the upper versus lower rectus abdominis (RA) muscle activity provoked by each of two different abdominal exercises and to contrast the intensity of contraction elicited by two different abdominal exercises on each RA muscle portion. Design: Nonrandomized control trial. Setting: Kinesiology laboratory in a university medicine faculty. Participants: Convenience sample of 33 healthy volunteers. Subjects who had practiced endurance or strength training activities (1.5 hours 3 days a week for 3 years) and those who had not accomplished that criterion comprised a high and a low physical activity group, respectively. Each of these two groups was divi…

Assessment of bioelectrical activity of pelvic floor muscles depending on the orientation of the pelvis in menopausal women with symptoms of stress u…

2017

Background Menopausal women often experience the prolapse of the uterus, bladder and rectum resulting from the failure and weakening of the pelvic floor muscles (PFM). Strengthening of the PFM through the standard exercises is recognized as an effective way of preventive measures and conservative treatment of the symptoms listed above, but still need to be improved. Aim The goal was the objective assessment of resting and functional bioelectrical activity of PFM in women during menopause and its comparison in three different positions of the pelvis: anterior pelvic tilt - position 1 (P1), posterior pelvic tilt - position 2 (P2), and neutral pelvic tilt - position 3 (P3). Design Prospective,…

Small bowel motility: relationship between smooth muscle contraction and electroenterogram signal.

2000

A study is made to correlate the electrical and mechanical activity of the smooth muscle of the small bowel. Bioelectrical signal recording from the intestinal serosa (electroenterogram) comprises a slow wave (SW) and spike burst (SB), though only the latter reflects intestinal pressure. The electroenterogram and smooth muscle pressure are simultaneously recorded in the canine small bowel. Spectral and time series analysis of the electroenterogram are performed to establish those electrical parameters that best reflect intestinal pressure. The results reveal an underlying correlation between the estimated parameters of electrical activity and smooth muscle pressure. In addition, parameters …

Dual effect mediated by protease-activated receptors on the mechanical activity of rat colon

2002

1. The present study examined the mechanical effects of agonist enzymes and receptor-activating peptides for protease-activated receptor (PAR)-1 and PAR-2 on longitudinal and circular muscle of rat isolated colonic segments in the attempt to clarify the PAR functional role in intestinal motility. 2. The responses to PAR-1 and PAR-2 activation were examined in vitro by recording simultaneously the changes of endoluminal pressure (index of circular muscle activity) and of isometric tension (index of longitudinal muscle activity). 3. Both PAR-1 agonists, thrombin (0.1 nM - 3 microM) and SFLLRN-NH2 (1 nM - 3 microM), and PAR-2 agonists, trypsin (0.1 nM - 10 microM) and SLIGRL-NH2 (1 nM - 10 mic…

Hemmung der Adenosintriphosphatase durch Colchicin

1951

The ATPase activity is inhibited by Colchicin in concentrations of 10−3 m and 10−4 m at a rate of 40 to 20 %, but in no way in the range of 10−7 m and 10−8 m, where Colchicin exerts its typical spindle-blocking action on the mitotic cell division. It is therefore no evidence, that Colchicin acts by influence on the energy yielding ATP-ATPase system, which was proposed to be responsible for the spindle contraction.

Über das Verschwinden von Adenosintriphosphat bei der Superpräzipitation von Aktomyosin-Gel

1952

(1) In the synerizing (“contraction”) of actomyosin gel, the ATP added disappears almost completely, while in the control experiment (contraction inhibited, ATPase intact), the greater part of the ATP remains.

Active contractility of the lymphangion and coordination of lymphangion chains

1976

Über den Chemismus von Zustandsänderungen des Aktomyosins

1950

(1) By means of a simple method the conditions were investigated for contraction and relaxation of actomyosin (AM) under the influence of potassium, magnesium, and calcium ions, of adenosintriphosphate (ATP) or muscle-adenylic-acid and phosphocreatin.