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Joshua N Webb, Caroline Dong, Andres Bernal, Giuliano Scarcelli
The goal of this protocol is to mimic the biomechanics of physiological accommodation in a cost-efficient, practical manner. Accommodation is achieved through the contraction of the ciliary body and relaxation of zonule fibers, which results in the thickening of the lens necessary for near vision. Here, we present a novel, simple method in which accommodation is replicated by tensing the zonules connected to the lens capsule via a manual lens stretcher (MLS). This method monitors the radial stretching achieved by a lens when subjected to a consistent force and allows for a comparison of accommodating lenses, which can be stretched, to non-accommodating lenses, which cannot be stretched...
February 23, 2018: Journal of Visualized Experiments: JoVE
Chu Shan Tan, Mun Fei Yam
Previous studies have demonstrated that 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (TMF) content in Orthosiphon stamineus fractions correlate with its vasorelaxation activity. Even with the availability of previous studies, there is still very little information on the vasorelaxation effect of TMF, and few scientific studies have been carried out. Therefore, the present study was designed to investigate the vasorelaxation activity and mechanism of action of the TMF. The vasorelaxation activity and the underlying mechanisms of TMF were evaluated on thoracic aortic rings isolated from Sprague Dawley rats...
March 19, 2018: Naunyn-Schmiedeberg's Archives of Pharmacology
Daisuke Chino, Tomoyo Sone, Kumi Yamazaki, Yuri Tsuruoka, Risa Yamagishi, Shunsuke Shiina, Keisuke Obara, Fumiko Yamaki, Koji Higai, Yoshio Tanaka
Object We aimed to identify the β-adrenoceptor (β-AR) subtypes involved in isoprenaline-induced relaxation of guinea pig colonic longitudinal smooth muscle using pharmacological and biochemical approaches. Methods Longitudinal smooth muscle was prepared from the male guinea pig ascending colon and contracted with histamine prior to comparing the relaxant responses to three catecholamines (isoprenaline, adrenaline, and noradrenaline). The inhibitory effects of subtype-selective β-AR antagonists on isoprenaline-induced relaxation were then investigated...
2018: Journal of Smooth Muscle Research, Nihon Heikatsukin Gakkai Kikanshi
Shunsuke Shiina, Ayaka Kanemura, Chihiro Suzuki, Fumiko Yamaki, Keisuke Obara, Daisuke Chino, Yoshio Tanaka
Object We identified the β-adrenoceptor (β-AR) subtypes responsible for the relaxant responses to adrenaline (AD) and noradrenaline (NA) in the rat thoracic aorta and examined the role of cAMP which is involved in these relaxant responses. Methods The effects of β-AR antagonists or the adenylyl cyclase inhibitor SQ 22,536 on AD- and NA-induced relaxant responses in phenylephrine-induced contraction and increases in cAMP levels were examined in isolated, endothelium-denuded rat thoracic aorta segments. Results AD-induced relaxation was completely suppressed by propranolol (10-7  M) or by ICI-118,551 (10-8  M) plus atenolol (10-6 M), and was also very strongly inhibited by ICI-118,551 (10-8  M) alone...
2018: Journal of Smooth Muscle Research, Nihon Heikatsukin Gakkai Kikanshi
Nicole Schulz, Arne Güssow, Natali Bauer, Andreas Moritz
Magnesium is the second most abundant intracellular cation after potassium. It plays a vital role in almost every metabolic process in the body and is important for bone mineralization, muscle contraction and relaxation, and neuronal signal transduction. Because of its expanding role in intensivecare medicine, there has been a significant increase in knowledge during recent years regarding the functions of magnesium in the body, problems leading to magnesium disorders, and limitations of laboratory testing...
February 2018: Tierärztliche Praxis. Ausgabe K, Kleintiere/Heimtiere
Katalin Szabó, Rudolf Gesztelyi, Nóra Lampé, Rita Kiss, Judit Remenyik, Georgina Pesti-Asbóth, Dániel Priksz, Zoltán Szilvássy, Béla Juhász
Fenugreek is a common herb possessing several bioactive components including diosgenin. Here, dietary fenugreek seed flour and diosgenin were evaluated on a model of endothelium-dependent vasorelaxation by abdominal aortas isolated from rats receiving high-fat, high-sugar diet (HFHSD). 60 male Wistar rats were randomized into six groups: (i) negative control getting conventional rat feed regimen; (ii) positive control receiving HFHSD; (iii) a test group fed 2 g/kg bw/day fenugreek seed flour (containing 10 mg/kg bw/day diosgenin) + HFHSD; (iv) three test groups fed 1, 10 and 50 mg/kg bw/day diosgenin + HFHSD...
March 10, 2018: International Journal of Molecular Sciences
Vivek Krishna Pulakazhi Venu, Mahmoud Saifeddine, Koichiro Mihara, Mahmoud El-Daly, Darrell Belke, Jonathan L E Dean, Edward R O'Brien, Simon A Hirota, Morley D Hollenberg
BACKGROUND AND PURPOSE: Previously, we demonstrated that exogenous Heat Shock Protein 27 (HSP27/gene, HSPB1) treatment of human endothelial progenitor cells (EPCs) increases the synthesis and secretion of VEGF, improves EPC-migration/re-endothelialization and decreases neo-intima formation, suggesting a role for HSPB1 in regulating EPC function. We hypothesized that HSPB1 could also affect mature endothelial cells (ECs) to alter EC-mediated vasoreactivity in vivo. Our work focused on eNOS/NO-dependent relaxation caused by acetylcholine and the coagulation pathway-activated receptor, proteinase-activated receptor-2 (PAR2)...
March 12, 2018: British Journal of Pharmacology
Lucía Isidoro, Mercedes Ferrer, Mercedes Perusquía
BACKGROUND: Testosterone, 5α- and 5β-dihydrotestosterone (-DHT) induce an acute in vitro vasorelaxation and in vivo vasodepressor, hypotensive and antihypertensive responses. Our aim was to study whether androgen-induced blood pressure (BP) reduction is involved with a blockade of Ca2+ influx through L-type voltage-operated calcium channels (L-VOCCs) and/or the signaling pathways of α1 -adrenoceptors to induce vasoconstriction, which are one of the major mechanisms of BP maintenance...
March 12, 2018: Endocrine Research
Wen Pan, Ziqi Yang, Jun Cheng, Cheng Qian, Yanggan Wang
The transmural heterogeneity of the contractility in ventricular muscle has not been well-studied. Here, we investigated the calcium transient and sarcomere contraction/relaxation in the endocardial (Endo) and epicardial (Epi) myocytes. Endo and Epi myocytes were isolated from C57/BL6 mice by Langendorff perfusion. Ca2+ transient and sarcomere contraction/relaxation were recorded simultaneously at different stimulation frequencies using a dual excitation fluorescence photomultiplier system. We found that the Endo myocytes have higher baseline diastolic calcium, significantly larger calcium transient and stronger sarcomere shortening than Epi myocytes...
March 12, 2018: Journal of Cellular Physiology
M Tavares-Silva, D Ferreira, S Cardoso, A R Raimundo, J Barbosa-Breda, A Leite-Moreira, A Rocha-Sousa
Urocortin 2 (UCN2) is a peptide related to corticotropin-releasing factor, capable of activating CRF-R2. Among its multisystemic effects, it has actions in all 3 muscle subtypes. This study's aim was to determine its potential role in two of the intrinsic eye muscle kinetics. Strips of iris sphincter (rabbit) and ciliary (bovine) muscles were dissected and mounted in isometric force-transducer systems filled with aerated-solutions. Contraction was elicited using carbachol (10(-6) M for iris sphincter, 10(-5) M for ciliary muscle), prior to all testing substances...
March 12, 2018: Physiological Research
Ipsita Mohanty, Subas Chandra Parija, Sujit Suklabaidya, Satish Rattan
Extracellular pH is an important physiological determinant of vascular tone that is normally maintained within 7.35-7.45. Any change outside this range leads to severe pathological repercussions. We investigated the unknown effects of extracellular acidosis on relaxation in the superior mesenteric artery (SMA) of goat. SMA rings were employed to maintain isometric contractions at extracellular pH (pHo ) 7.4 and 6.8. We analyzed the effect of acidosis (pHo 6.8) compared to physiological pH (pHo 7.4) on three signaling mediators of endothelium-dependent hyperpolarization: nitric oxide (NO), prostaglandin I2 (PGI2 ), and myoendothelial gap junctions (MEGJ)...
March 7, 2018: European Journal of Pharmacology
Ian C Smith, Jahaan Ali, Geoffrey A Power, Walter Herzog
PURPOSE: We examined how muscle length and time between stimuli (inter-pulse interval, IPI) influence declines in force (sag) seen during unfused tetani in the human adductor pollicis muscle. METHODS: A series of 16-pulse contractions were evoked with IPIs between 1 × and 5 × the twitch time to peak tension (TPT) at large (long muscle length) and small (short muscle length) thumb adduction angles. Unfused tetani were mathematically deconstructed into a series of overlapping twitch contractions to examine why sag exhibits length- and IPI-dependencies...
March 8, 2018: European Journal of Applied Physiology
Anshul Sharma, Jan P F Lagerwall
We present a robust method to prepare thin oriented nematic liquid crystalline elastomer-polymer (LCE-polymer) core-sheath fibers. An electrospinning setup is utilized to spin a single solution of photo-crosslinkable low molecular weight reactive mesogens and a support polymer to form the coaxial LCE-polymer fibers, where the support polymer forms the sheath via in situ phase separation as the solvent evaporates. We discuss the effect of phase separation and compare two different sheath polymers (polyvinylpyrrolidone and polylactic acid), investigating optical and morphological properties of obtained fibers, as well as the shape changes upon heating...
March 7, 2018: Materials
Xue-Yi Sun, Zhi Yu, Zhi-Yu Chen, Bin Xu
OBJECTIVE: To observe the effect of manual acupuncture stimulation of different layers (skin, muscle, peritoneum, sub-peritoneum) of "Tianshu" (ST 25) region on proximal colonic pressure in normal rats. METHODS: Forty-eight male SD rats were divided into 6 groups: all layer-needling, brushing, cutaneous needling, muscular needling, peritoneum-needling and sub-peritoneum-needling groups ( n =8 in each group). Manual needling or brushing was applied to "Tianshu" (ST 25) region...
February 25, 2018: Zhen Ci Yan Jiu, Acupuncture Research
Carla Blum-Johnston, Richard B Thorpe, Chelsea Wee, Raechel Opsahl, Monica Romero, Samuel Murray, Alexander Brunelle, Quintin Blood, Rachael Wilson, Arlin B Blood, Lubo Zhang, Lawrence D Longo, William J Pearce, Sean M Wilson
Bradykinin-induced activation of the pulmonary endothelium triggers a rise in intracellular Ca2+ , which activates nitric oxide (NO)-dependent vasorelaxation. Chronic hypoxia is commonly associated with increased pulmonary vascular tone, which can cause pulmonary hypertension in responsive individuals. In the present study, we tested the hypothesis that long-term high altitude hypoxia (LTH) diminishes bradykinin-induced Ca2+ signals and inhibits eNOS, PGI2 and BKCa channels in sheep, which are moderately responsive to LTH, resulting in decreased pulmonary arterial vasorelaxation...
March 7, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
Hiroyuki Nakayama, Kinya Otsu
Mitochondria play a central role in multiple cellular functions, including energy production, calcium homeostasis, and cell death. Currently, growing evidence indicates the vital roles of mitochondria in triggering and maintaining inflammation. Chronic inflammation without microbial infection - termed sterile inflammation - is strongly involved in the development of heart failure. Sterile inflammation is triggered by the activation of pattern recognition receptors (PRRs) that sense endogenous ligands called damage-associated molecular patterns (DAMPs)...
March 6, 2018: Biochemical Journal
Tobias Vogt, Kouki Kato, Nils Flüthmann, Oliver Bloch, Hiroki Nakata, Kazuyuki Kanosue
OBJECTIVE: Motor-related cortical potentials (MRCP) often compared separated muscle activations; however, MRCP preceding combined contraction onsets and relaxation offsets of one consecutive motor task sequence remain to be elucidated. METHODS: Twelve healthy males (27.92±4.33 years, 181.83±7.15 cm, 84.58±7.15 kg) performed 40 submaximal isometric right-limb wrist flexions (i.e. motor task sequences). Each motor task sequence combined timed contractions to and relaxations from distinct torque levels, i...
March 1, 2018: Journal of Musculoskeletal & Neuronal Interactions
Stéphanie Thibault-Gagnon, Corrie Goldfinger, Caroline Pukall, Susan Chamberlain, Linda McLean
BACKGROUND: Digital intravaginal palpation remains the favored method for clinical assessment of pelvic floor muscle (PFM) function in women; however, there is growing interest in using transperineal ultrasound imaging (TPUSI). TPUSI does not involve vaginal penetration, making it particularly relevant for PFM assessment in women with genito-pelvic pain and penetration disorders. AIMS: To study the relations between measures of PFM morphology and function assessed using 3-dimensional (3D) TPUSI and PFM assessment through intravaginal palpation...
March 2018: Journal of Sexual Medicine
C Unterbuchner, M Blobner
Neuromuscular blockade (TOF count = 0) can improve tracheal intubation and microlaryngeal surgery. It is also frequently used in many surgical fields including both nonlaparoscopic and laparoscopic surgery to improve surgical conditions and to prevent sudden muscle contractions. Currently there is a controversy regarding the need and the clinical benefits of deep neuromuscular blockade for different surgical procedures. Deep neuromuscular relaxation improves laparoscopic surgical space conditions only marginally when using low intra-abdominal pressure...
March 1, 2018: Der Anaesthesist
Konstantin Nadein, Oliver Betz
We describe the kinematics and performance of the natural jump in the weevil Orchestes fagi (Fabricius, 1801) (Coleoptera: Curculionidae) and its jumping apparatus with underlying anatomy and functional morphology. In weevils, jumping is performed by the hind legs and involves the extension of the hind tibia. The principal structural elements of the jumping apparatus are (1) the femoro-tibial joint, (2) the metafemoral extensor tendon, (3) the extensor ligament, (4) the flexor ligament, (5) the tibial flexor sclerite and (6) the extensor and flexor muscles...
February 26, 2018: Arthropod Structure & Development
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