Decline In Tension Research Articles

Contraction-induced enhancement of relaxation during high force contractions of mouse lumbrical muscle at 37°C.

Repeated stimulation of unfatigued rodent fast-twitch skeletal muscle accelerates the kinetics of tension relaxation through an unknown mechanism. This effect varies with muscle type and stimulation parameters, and has been observed at physiological temperatures for submaximal but not maximal contractions. The purpose of this study was to compare relaxation kinetics of C57BL/6 mouse lumbrical muscles ex vivo from maximal isometric force (500 Hz for 20 ms) when evoked before (pre) and after (post) an intervening tetanic contraction at 37°C. During post contractions, we noted significant increases in the rate of tension decline during both the slow linear phase and the fast exponential phase of relaxation, as well as a reduced duration of the slow phase of relaxation compared with pre contractions (all P<0.05). This is the first demonstration of enhanced slow and fast relaxation phases from maximal isometric tension induced by prior stimulation in intact muscle at a physiological temperature.

SERCA 2a Gene Therapy, Game-Changer for Heart Failure

Submit Manuscript | http://medcraveonline.com transients recorded with the Ca 2+ probe aequorin during isometric contraction of myocardium in patients with end-stage failure were markedly prolonged, with a peak and then a secondary peak in the [Ca 2+ ]i transient trace, which was associated with a marked prolongation of the time course of the Ca 2+ decline and of tension decline [2]. Because SERCA is responsible for 60% to 90% of the [Ca 2+ ]i decline in mammalian ventricular myocytes, these results were consistent with impaired function of the SR Ca 2+ transport

AGE AND GENDER PECULIARITIES OF DEVELOPMENT OF GALLSTONE DISEASE

Goal. Study of the role of risk factors in mechanized gall stone formation depending on sex and age of patients. Material and methods We examined 210 patients with stage I gallstone disease (GSD). In verification of diagnosis used an ultrasound study of the hepatobiliary system, multi-grade duodenal sounding with subsequent macroscopic, microscopic, chemical and physical examination of bile. In the portions “b” and “C” bile was determined the total concentration of bile acids, cholesterol, with the subsequent calculation it consists of cholesterol ratio. Estimation of surface tension of bile viscosity and bile. In the studied blood levels of total cholesterol, lipoproteins of very low density, lowdensity lipoproteins, high density lipoproteins, triglycerides, were determined the coefficient of atherogenicity. To assess the degree of accumulation of body fat was used the Quetelet index. Studied the relative risk of anamnestic risk factors of GSD. Results. The features of biliary lithogenesis based on gender and age of patients. High value PR for the gall stone formation are female gender — 3,16, Mature and elderly age (older than 50) of 3.67. In young women, gall-stone formation is mainly due to the increase of cholesterol level of bile, at the age of 50 years with a decline in zhelchnokamennaja pool, increased viscosity and surface tension of bile. The most important risk factors of cholecystolithiasis are also gender differences: if women is multiple pregnancies and (or) childbirth (more than 3) — OR 4,62, overweight (BMI over 26) — OR is 4.57 and the violation of the principles of good nutrition (eating disorders, overeating or starvation, the use of large quantities of animal fats) — OR 3,94, for men it’s physical inactivity — OR a 4.25, the increase in KA — PR 3.87 and burdened by GSD genetics — OR of 2.05. Conclusion. The data obtained can be used in the organization of dispensary work with patients with hepatobiliary pathology, and to optimize primary prevention of gall stone formation.

Heat stress redistributes blood flow in arteries of the brain during dynamic exercise.

We hypothesized that heat stress would decrease anterior and posterior cerebral blood flow (CBF) during exercise, and the reduction in anterior CBF would be partly associated with large increase in extracranial blood flow (BF). Nine subjects performed 40 min of semirecumbent cycling at 60% of the peak oxygen uptake in hot (35°C; Heat) and thermoneutral environments (25°C; Control). We evaluated BF and conductance (COND) in the external carotid artery (ECA), internal carotid artery (ICA), and vertebral artery (VA) using ultrasonography. During the Heat condition, ICA and VA BF were significantly increased 10 min after the start of exercise (P < 0.05) and thereafter gradually decreased. ICA COND was significantly decreased (P < 0.05), whereas VA COND remained unchanged throughout Heat. Compared with the Control, either BF or COND of ICA and VA at the end of Heat tended to be lower, but not significantly. In contrast, ECA BF and COND at the end of Heat were both higher than levels in the Control condition (P < 0.01). During Heat, a reduction in ICA BF appears to be associated with a decline in end-tidal CO2 tension (r = 0.84), whereas VA BF appears to be affected by a change in cardiac output (r = 0.87). In addition, a change in ECA BF during Heat was negatively correlated with a change in ICA BF (r = -0.75). Heat stress resulted in modification of the vascular response of head and brain arteries to exercise, which resulted in an alteration in the distribution of cardiac output. Moreover, a hyperthermia-induced increase in extracranial BF might compromise anterior CBF during exercise with heat stress.

Pre-exercise glucose drink and muscle performance by bicycle ergography

Background: There is a natural linkage between nutrition and exercise physiology. When a skeletal muscle fiber is repeatedly stimulated, the tension developed by the fiber eventually decreases even though the stimulation continues. This decline in muscle tension as a result of previous contractile activity is known as fatigue. Carbohydrate supplementation during exercise delays fatigue by 30–60 min. Ingestion of glucose drink half an hour prior to the exercise improves the muscular performance and delays the occurrence of fatigue. Objective: To study the effect of pre-exercise glucose drink on muscle performance by bicycle ergography and time to fatigue in non-athletes. Materials and Methods: A total of 30 male medical students with mean age of 18.6±1.56 years were recruited for the study. Subjects were made to perform exercise on bicycle ergometer in two sessions each session separated by 1 week. In second session, subjects were given glucose drink half a hour prior to exercise. Work done was calculated and the time for fatigue, total distance traveled was noted in both the sessions. Result: There was a significant difference in the time to fatigue (12.09 ± 7.42 min), work done (6964.00±4517.96 J), total distance traveled (3.55±2.42 km) in the second session having greater values than in the time to fatigue (7.09±4.96 min), work done (4305.33±3065.19 J), and total distance traveled (2.12±1.54 km) in the first session. Conclusion: The performance is better and time to fatigue is delayed in exercise performed after taking glucose drink.

El desgobierno de los jueces

The author presents the institutional evolution of the judicial office during modernity and historical-legal coordinates in which it is inserted, highlighting the decline of parliamentary law, tension and conflict in democratic governments, establishing politicized judiciaries and ascending judicial activism, the consequences not only impact the democratic systems of representation, but in the practice of judicial activity.

An optimal lightweight foamed mortar mix suitable for tunnel drainage carried out using the composite lining method

In this paper, an optimal lightweight foamed mortar mix suitable is proposed for facilitating tunnel drainage carried out using the composite lining method. A physical performance evaluation and pore structure analysis is provided in order to assess the performance of different lightweight foamed mortar mix proportions with various void fractions and foam solution concentrations. Furthermore, on the basis of an in-plane permeability test that simulated the permeation of fines of soil leaking with underground water, the formation and distribution of open-cell foams by measuring the outflow characteristics and outflow volume for each mix of the nonwoven geotextile and lightweight foamed mortar, which are the existing tunnel drainage materials was examined. Consequently, a mix employing a foaming agent with a dilution rate of 2% (#1) showed a better drain performance than all the other mixes, because it had the most appropriately formed and distributed open-cell foams, the key component for tunnel drainage. In other words, the mix of dilution rate of 2% was thought to have achieved stable closed-cell foams because of the decline in the surface tension of the foams, as well as the optimal formation and distribution of open-cell foams that possess excellent permeability because of the cohesiveness between the foams. Moreover, the thickness (drainage space) of it was approximately 17 times that of the nonwoven geotextile, and because the closed-cell and open-cell foams were connected like a spider web, it could be expected to reduce the blocking of drainage caused by the fines of soil.

TRPV1 Activation Modulates Acetylcholine Release at Myoneural Junctions

Transient receptor potential (TRP) proteins are non-selective cation channel proteins that are expressed throughout the body. Previous studies show that TRP Vanilloid 1 (TRPV1), capsaicin (CAP) receptor, is expressed in sensory neurons. Here we report that TRPV1 protein is expressed at the motor nerve terminals and that activation of TRPV1 by CAP suppresses acetylcholine release, in vitro. We analyzed twitch tension, spontaneous and nerve stimulus evoked acetylcholine release from phrenic nerve diaphragm nerve muscle preparations (NMP) isolated from isoflurane anesthetized adult wild type mice and that genetically lacked TRPV1 (TRPV1-/-). When acutely applied to isolated NMP, 1 µM CAP produced a concentration-dependent decline of twitch tension and a significant decline in the amplitude of stimulus evoked endplate currents (EPCs) and quantal content without any effect on the miniature endplate currents (mEPCs). The suppression of nerve stimulus evoked acetylcholine release by CAP was antagonized by capsazepine (CPZ; 10 µM), a TRPV1 antagonist. However, CAP did not suppress phrenic nerve stimulus evoked acetylcholine release in TRPV1−/− mice. Also, CAP treatment, in vitro, interfered with the localization of adapter protein 2 in cholinergic Neuro 2a cells. Wortmannin, (WMN; 10 µM; non-selective phosphoinositol kinase inhibitor), mimicked the effects of CAP by inhibiting the acetylcholine exocytosis. Our data suggest that TRPV1 proteins expressed at the motor nerve terminal are coupled to the exo-endocytic mechanisms to regulate neuromuscular functions.

L-lysine escinat, thiotriazolin, gordox and mydocalm influence on oxygen tension in the intestinal wall and acid-base balance and limited proteolysis in intestinal venous blood in terms of intraabdominal hypertension modeling.

In acute experiments on rabbits there were studied changes in oxygen tension in the intestinal wall tissues, acid-base balance and limited proteolysis and its inhibitors in intestinal venous blood, protective action of L-lysine escinat (0,15 mg/kg / single dose), thiotriazolin (25 mg/kg / single dose), aprotinin (gordox) (10,000 units/kg / single dose) in sequential modeling of standard levels increasing of intra-abdominal hypertension (IAH) — 50, 100, 150, 200, 250, 300, 350 m H2O, and also of tolperison (mydocalm) (5 mg/kg / single dose) on modeling of stable 3-hour IAH 200 m H2O. The IAH modeling was performed by means of stand of our construction. Under the influence of IAH the compensated metabolic acidosis in intestinal venous blood with a compensative hyperpnoe develops, decline of oxygen tension in tissues and activating of a limited proteolysis as well as decline of its inhibitors activity in intestinal venous blood occur. By the degree of metabolic acidosis prevention investigational preparations were distributed as follows gordox &gt; thiotriazolin = L-lysine escinat = mydocalm, and by prevention of decline of oxygen tension in tissues — thiotriazolin &gt; L-lysine escinat &gt; mydocalm &gt; gordox, it is is connected with different rate of methabolic products excretion into the blood, due to the influence on blood circulation and transcapilary exchange. By the degree of prevention of proteolytic activity and inhibitory potential changes, investigational preparations were distributed as follows: gordox &gt; mydocalm &gt; thiotriazolin &gt; L-lysine escinat, this is connected with inhibition of proteolysis in gordox, and in other ones – with reduction of ischemic damage of tissues. Owing to different mechanism of action thiotriazolin, L-lysine escinat and mydocalm may be simultaneously recommended for a conservative treatment of patients with intraabdominal hypertension syndrome.

Capsaicin modulates acetylcholine release at the myoneural junction

Transient receptor potential (TRP) proteins are non-selective cation channel proteins that are expressed throughout the body. Previous studies demonstrated the expression of TRP Vanilloid 1 (TRPV1), capsaicin (CAP) receptor, in sensory neurons. Recently, we reported TRPV1 expression in mouse motor nerve terminals [MNTs; (Thyagarajan et al., 2009)], where we observed that CAP protected MNTs from botulinum neurotoxin A (BoNT/A). Phrenic nerve diaphragm nerve muscle preparations (NMP) isolated from isoflurane anesthetized adult mice were analyzed for twitch tension, spontaneous (mEPCs) and nerve stimulus evoked (EPCs) acetylcholine release. When acutely applied to isolated NMP, CAP produced a concentration-dependent decline of twitch tension and produced a significant decline in the amplitude of EPCs and quantal content without any effect on the mEPCs. The suppression of nerve stimulus evoked acetylcholine release by CAP was antagonized by capsazepine (CPZ), a TRPV1 antagonist. CAP did not suppress phrenic nerve stimulus evoked acetylcholine release in TRPV1 knockout mice. Also, CAP treatment, in vitro, interfered with the localization of adapter protein 2 in cholinergic Neuro 2a cells. Wortmannin, (WMN; non-selective phosphoinositol kinase inhibitor), mimicked the effects of CAP by inhibiting the acetylcholine exocytosis. Our data suggest that TRPV1 proteins expressed at the MNT are coupled to the exo-endocytic mechanisms to regulate neuromuscular functions.

Nebulization of Active Pharmaceutical Ingredients with the eFlow®rapid: Impact of Formulation Variables on Aerodynamic Characteristics

Nebulization of active pharmaceutical ingredient (API) solutions is a well-established means to achieve pulmonary drug deposition. The current study identified the impact of formulation variables on the aerosolization performance of the eFlow(®) rapid with special respect to optimized lung application. API formulations (including excipient-supplemented samples) were investigated for physicochemical properties, then nebulized using vibrating-mesh technology. The generated aerosol clouds were analyzed by laser diffraction. Aerosol deposition characteristics in the human respiratory tract were estimated using an algebraic model. Remarkable effects on aerosolization performance [i.e., mass median aerodynamic diameter (MMAD)] of API solutions were obtained when the sample conductivity (by API concentration and type, sodium chloride addition) and dynamic viscosity (by application of sucrose and poly(ethylene glycol) 200) were elevated. A similar influence was observed for a decline in surface tension (by ethanol addition). Thus, a defined adjustment of formulation parameters allowed for a decrease of the MMAD from ∼ 8.0 μm to values as small as ∼ 3.5 μm. Consequently, the pattern and efficiency of aerosol deposition in the human respiratory tract were improved. In conclusion, identification of physicochemical variables and their way of influencing vibrating-mesh nebulization has been provided to deliver a platform for tailoring aerosol characteristics and thus, advancing pulmonary therapy.

Effects of organoclay on the compatibility and interfacial phenomena of PE/EVA blends with UCST phase behavior

The compatibilization effects of organically modified nanoclay on the miscibility window, phase separation kinetics, biphasic morphology, interfacial tension, and final properties of polyethylene/ethylene vinyl acetate copolymer blends exhibiting UCST behavior have been investigated. Regardless of blend composition, intercalated nanoclay decreases the phase transition temperatures to lower values and changes the symmetry of phase diagram. The miscibility of PE and EVA phases in the amorphous regions of nanocomposites noticeably enhances and finer biphasic morphology is obtained by the incorporation of organoclay. The pinning influence of the nanofiller on polymer chain diffusion causes much slower phase separation kinetics for the nanocomposites. Similar to conventional compatibilizers such as block copolymers, the interfacial activity of nanoclay leads to a sharp decline in the interfacial tension of PE/EVA up to 2‐orders of magnitude. Moreover, the results show that imposing restrictions on the phase separation phenomenon increases the impact strength of the virgin blend and related nanocomposite. However, this improvement has been much more noticeable in the presence of nanoparticles, which is due to the simultaneous roles of organoclay as an effective compatibilizer and reinforcement. POLYM. COMPOS., 35:2329–2342, 2014. © 2014 Society of Plastics Engineers

The Effect of pH and Heat Pre-Treatments on the Physicochemical and Emulsifying Properties of β-lactoglobulin

The overall goal of this research was to investigate structure-function mechanisms associated the emulsifying properties β-lactoglobulin (β-LG). Specifically the physicochemical (i.e., surface charge and hydrophobicity, size and interfacial tension) and emulsifying (i.e., emulsification activity (EAI) and stability indices (ESI)) properties of β-LG were investigated in response to changes in pH (3.0, 5.0 and 7.0) and heat pre-treatment conditions (25, 55 and 85 °C). Hydrophobicity was found to be greatest at pH 5.0/85 °C, whereas at all conditions it was significantly lower. Surface charge on β-LG was found to be neutral at ~ pH 3.9, regardless of conditions. Aggregate size was also found to be highest at pH 5.0/85 °C (avg. hydrodynamic radii of ~714 nm), corresponding to a reduced net surface charge and high hydrophobicity. Little size dependence of aggregates was observed at pH 3.0 regardless to the temperature pre-treatments (radii ~120 nm). In contrast, at pH 7.0 slight temperature dependence was apparent, where treatments at 25, 55 and 85 °C led to radii of 412.8, 307.2 and 232.3 nm, respectively. Overall, the addition of β-LG to a canola oil–water system resulted in a decline in interfacial tension from ~28 mN/m to ~18 mN/m, however the effect of pH/temperature conditions was minimal. EAI was found to be highest when β-LG solutions displayed high surface charge combined with moderate hydrophobicity. In contrast, ESI was higher under conditions where β-LG solutions remained in a native (25 °C) or fully denatured state (85 °C) versus one in where partially unravelling may be occurring (55 °C).

Cardiovascular and eletrocardiographic parameters after tonin administration in Wistar rats

In order to understand the mechanisms of interaction between tonin–angiotensin and renin–angiotensin systems (RAS) we evaluated, “in vivo” and “in vitro”, in Wistar rats, cardiovascular and electrocardiographic parameters after tonin administration. Arterial pressure (AP) and electrocardiogram (ECG) were recorded in awake animals before and after tonin administration. Langendorff technique was used to analyze cardiac function in isolated heart in the presence of tonin and video motion edge detection system was used to evaluate the effect of tonin upon contractile function of isolated rat ventricular cardiomyocytes. After tonin infusion rats presented significantly higher diastolic and mean arterial pressure (MAP) and heart rate (HR) as compared with control. The ECG analysis revealed shorter RR interval, increase in the low-frequency (LF) range of the heart rate variability (HRV) power (%) and decrease in the high-frequency (HF) of HRV power (%). Isolated hearts perfused with tonin presented an increase in the arterial coronary pressure (ACP) and decline in the ventricular systolic tension (ST), maximal (dT/dt+) and minimal (dT/dt) contractility. The rates of contraction and relaxation of isolated ventricular cardiomyocytes were significantly increased due to the presence of tonin. The angiotensin II (Ang II) levels in the coronary sinus effluent increased in the presence of tonin in a dose-dependent manner and the effect of tonin upon ACP was completely blocked by candesartan. Tonin is able to generate the vasoconstrictor peptide Ang II in the isolated heart of the rat and the cardiovascular response induced by tonin was completely blocked by candesartan, an indication that the action of Ang II on Ang II type 1 (AT1) receptors is the major mechanism of the heart effects. Tonin affects cardiomyocyte contractile function which may be due to interference with Ca2+ handling.

Molecular-targeted therapy hypoxia in head and neck squamous cell carcinoma patients

Despite advances in surgical techniques, radiotherapy, and chemotherapy, 5-year survival in patients with late-stage head and neck squamous cell carcinoma (HNSCC) have not improved significantly over the past decades. HNSCC tumors are commonly associated with hypoxia, which is characterized by an acute and/or chronic decline in oxygen tension. Hypoxia is an important cancer-aggravating microenvironmental factor that contributes to malignant behaviors such as acquisition of antiapoptotic ability by cancer cells and tumor progression, invasion, metastasis, and resistance to chemotherapy and radiotherapy. Numerous studies have assessed tumor hypoxia and identified molecular markers that are promising therapeutic targets in HNSCC cases. Moreover, investigators have suggested a number of molecular strategies to target cell processes critical to hypoxia development in HNSCC patients via the direct or indirect regulation of hypoxia-inducible factor-1α expression in cancer cells. In this review, we described recent advances in the identification and development of molecular-targeted therapy targeting hypoxia in HNSCC patients.

Surface Tension and Aggregation Properties of Novel Cationic Gemini Surfactants with Diethylammonium Headgroups and a Diamido Spacer

A series of novel cationic gemini surfactants with diethylammonium headgroups and a diamido spacer were synthesized, and their surface and bulk properties were investigated by surface tension, electrical conductivity, fluorescence, viscosity, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements. An interesting phenomenon, that is, the obvious decline in surface tension upon increasing concentration above the critical micelle concentration (cmc), was found in these gemini surfactant solutions, and two explanations were proposed. This surface tension behavior could be explained by the rapid increase in the counterion activity in the bulk phase or the continued filling of the interface with increasing surfactant concentration above the cmc. More interestingly, not only vesicles but also the surfactant-concentration-induced vesicle to larger aggregate (spongelike aggregate) transition and the salt-induced vesicle and spongelike aggregate to micelle transition were found in the aqueous solutions of these gemini surfactants. The spongelike aggregate that is first reported in the cationic gemini surfactant-water binary system is probably caused by the adhesion and fusion of vesicles at high surfactant concentration.

Early rather than late aldosterone blockade improves myocardial function in spontaneously hypertensive rats without heart failure

The purpose of this study was to compare the effect of early and late aldosterone blockade with spironolactone (SPR) on ventricular remodeling in spontaneously hypertensive rats (SHR) without HF.MethodsSHR were divided into four groups: control: CTL13 (n=20) 13 month‐old and CTL16 (n=72) 16 month‐old; SPR: SPR13 (n=24) 13 month‐old and SPR16 (n=34) 16 month‐old. SPR groups were treated with SPR for six months (20 mg/kg/day). Systolic blood pressure (BP) was measured. Echocardiogram (ECHO) was performed to evaluate cardiac structures and left ventricular (LV) function. Myocardial function was analyzed in LV papillary muscle preparations. Statistics: two way ANOVA and Student‐Newman‐Keuls. Significance: p&lt;0.05.ResultsBP was not different between groups (CTL13: 184±24; SPR13: 197±22; CTL16: 199±43; SPR16: 200±35 mmHg; p&gt;0.05). ECHO did not show differences between groups. In vitro evaluated myocardial function was improved in SPR13 vs. CTL13 group (developed tension (dT): 7.00±1.68 vs. 5.22±1.64 g/mm2; maximum rate of dT: 61.0±17.4 vs. 46.8±5.00 g/mm2/s; maximum rate of tension decline: 28.9±7.06 vs. 21.6±5.40 g/mm2/s; p&lt;0.05). Mortality rate was significantly lower in SPR16 than CTL16 (38% vs. 71%; p&lt;0.05).ConclusionAldosterone blockade initiated at 13 months but not at 16 months induces beneficial effects on myocardial function and collagen accumulation in SHR without heart failure.

Sepsis, Kidney, and Tissue Oxygenation

Sepsis, Kidney, and Tissue Oxygenation

Reply to “Should the Gibbs Analysis Be Revised?”

Plots of surface tension vs log [surfactant] show a steep linear decline until the CMC is reached. Conventional “Gibbs analysis” declares that the air/water interface is saturated with surfactant throughout this linear region, thereby enabling an area-per-molecule to be determined. We have previously provided evidence from four independent experimental methods that cast doubt on the “saturated interface” concept. In the preceding paper, Laven and de With question our results with deceptively authoritative but specious arguments devoid of any new experiments (e.g., they explain our conductance data by postulating the presence of two different coexisting micellar structures). However, consider the Gibbs analysis from strictly an intuitive standpoint. The Gibbs analysis demands that surfactant in the bulk phase (even at submillimolar concentrations) causes a dramatic decline in the surface tension of an interface that is already saturated. The Gibbs analysis also forces the conclusion that initial saturation...

Surface tension phenomena in the xylem sap of three diffuse porous temperate tree species

In plant physiology models involving bubble nucleation, expansion or elimination, it is typically assumed that the surface tension of xylem sap is equal to that of pure water, though this has never been tested. In this study we collected xylem sap from branches of the tree species Populus tremuloides, Betula papyrifera and Sorbus aucuparia over 3 months. We measured the instantaneous surface tension and followed changes over a period of 0.5-5 h using the pendant drop technique. In all three species the instantaneous surface tension was equal to or within a few percent of that of pure water. Further, in B. papyrifera and S. aucuparia the change over time following drop establishment, although significant, was very small. In P. tremuloides, however, there was a steep decline in surface tension over time that leveled off towards values 21-27% lower than that of pure water. This indicated the presence of surfactants. The values were lower for thinner distal branch segments than for proximal ones closer to the trunk. In some species it appears valid to assume that the surface tension of xylem sap is equal to that of water. However, in branch segments of P. tremuloides close to the terminal bud and hence potentially in other species as well, it may be necessary to take into account the presence of surfactants that reduce the surface tension over time.