Usability, acceptability, and feasibility of the World Health Organization Labour Care Guide: A mixed-methods, multicountry evaluation.

INTRODUCTION: The World Health Organization's (WHO) Labour Care Guide (LCG) is a "next-generation" partograph based on WHO's latest intrapartum care recommendations. It aims to optimize clinical care provided to women and their experience of care. We evaluated the LCG's usability, feasibility, and acceptability among maternity care practitioners in clinical settings. METHODS: Mixed-methods evaluation with doctors, midwives, and nurses in 12 health facilities across Argentina, India, Kenya, Malawi, Nigeria, and Tanzania. Purposively sampled and trained practitioners applied the LCG in low-risk women during labor and rated experiences, satisfaction, and usability. Practitioners were invited to focus group discussions (FGDs) to share experiences and perceptions of the LCG, which were subjected to framework analysis. RESULTS: One hundred and thirty-six practitioners applied the LCG in managing labor and birth of 1,226 low-risk women. The majority of women had a spontaneous vaginal birth (91.6%); two cases of intrapartum stillbirths (1.63 per 1000 births) occurred. Practitioner satisfaction with the LCG was high, and median usability score was 67.5%. Practitioners described the LCG as supporting precise and meticulous monitoring during labor, encouraging critical thinking in labor management, and improving the provision of woman-centered care. CONCLUSIONS: The LCG is feasible and acceptable to use across different clinical settings and can promote woman-centered care, though some design improvements would benefit usability. Implementing the LCG needs to be accompanied by training and supportive supervision, and strategies to promote an enabling environment (including updated policies on supportive care interventions, and ensuring essential equipment is available).

Ultrastructure of human tracheal smooth muscle from subjects with asthma and nonasthmatic subjects. Standardized methods for comparison.

A characteristic feature of asthma is exaggerated airway narrowing, termed airway hyper-responsiveness (AHR) due to contraction of airway smooth muscle (ASM). Although smooth muscle (SM)-specific asthma susceptibility genes have been identified, it is not known whether asthmatic ASM is phenotypically different from nonasthmatic ASM in terms of subcellular structure or mechanical function. The present study is the first to systematically quantify, using electron microscopy, the ultrastructure of tracheal SM from subjects with asthma and nonasthmatic subjects. Methodological details concerning tissue sample preparation, ultrastructural quantification, and normalization of isometric force by appropriate morphometric parameters are described. We reasoned that genetic and/or acquired differences in the ultrastructure of asthmatic ASM could be associated with functional changes. We recently reported that asthmatic ASM is better able to maintain and recover active force generation after length oscillations simulating deep inspirations. The present study was designed to seek structural evidence to account for this observation. Contrary to our hypotheses, no significant qualitative or quantitative differences were found in the subcellular structure of asthmatic versus nonasthmatic tracheal SM. Specifically, there were no differences in average SM cell cross-sectional area; fraction of the cell area occupied by nonfilamentous area; amounts of mitochondria, dense bodies, and dense plaques; myosin and actin filament densities; basal lamina thickness; and the number of microtubules. These results indicate that functional differences in ASM do not necessarily translate into observable structural changes.

Increase in passive stiffness at reduced airway smooth muscle length: potential impact on airway responsiveness.

The amplitude of strain in airway smooth muscle (ASM) produced by oscillatory perturbations such as tidal breathing or deep inspiration (DI) influences the force loss in the muscle and is therefore a key determinant of the bronchoprotective and bronchodilatory effects of these breathing maneuvers. The stiffness of unstimulated ASM (passive stiffness) directly influences the amplitude of strain. The nature of the passive stiffness is, however, not clear. In this study, we measured the passive stiffness of ovine ASM at different muscle lengths (relative to in situ length, which was used as a reference length, L(ref)) and states of adaptation to gain insights into the origin of this muscle property. The results showed that the passive stiffness was relatively independent of muscle length, possessing a constant plateau value over a length range from 0.62 to 1.25 L(ref). Following a halving of ASM length, passive stiffness decreased substantially (by 71%) but redeveloped over time ( approximately 30 min) at the shorter length to reach 65% of the stiffness value at L(ref), provided that the muscle was stimulated to contract at least once over a approximately 30-min period. The redevelopment and maintenance of passive stiffness were dependent on the presence of Ca(2+) but unaffected by latrunculin B, an inhibitor of actin filament polymerization. The maintenance of passive stiffness was also not affected by blocking myosin cross-bridge cycling using a myosin light chain kinase inhibitor or by blocking the Rho-Rho kinase (RhoK) pathway using a RhoK inhibitor. Our results suggest that the passive stiffness of ASM is labile and capable of redevelopment following length reduction. Redevelopment and maintenance of passive stiffness following muscle shortening could contribute to airway hyperresponsiveness by attenuating the airway wall strain induced by tidal breathing and DI.

Adaptive response of pulmonary arterial smooth muscle to length change.

Hypervasoconstriction is associated with pulmonary hypertension and dysfunction of the pulmonary arterial smooth muscle (PASM) is implicated. However, relatively little is known about the mechanical properties of PASM. Recent advances in our understanding of plastic adaptation in smooth muscle may shed light on the disease mechanism. In this study, we determined whether PASM is capable of adapting to length changes (especially shortening) and regain its contractile force. We examined the time course of length adaptation in PASM in response to step changes in length and to length oscillations mimicking the periodic stretches due to pulsatile arterial pressure. Rings from sheep pulmonary artery were mounted on myograph and stimulated using electrical field stimulation (12-16 s, 20 V, 60 Hz). The length-force relationship was determined at L(ref) to 0.6 L(ref), where L(ref) was a reference length close to the in situ length of PASM. The response to length oscillations was determined at L(ref), after the muscle was subjected to length oscillation of various amplitudes for 200 s at 1.5 Hz. Release (or stretch) of resting PASM from L(ref) to 0.6 (and vice versa) was followed by a significant force recovery (73 and 63%, respectively), characteristic of length adaptation. All recoveries of force followed a monoexponential time course. Length oscillations with amplitudes ranging from 5 to 20% L(ref) caused no significant change in force generation in subsequent contractions. It is concluded that, like many smooth muscles, PASM possesses substantial capability to adapt to changes in length. Under pathological conditions, this could contribute to hypervasoconstriction in pulmonary hypertension.

A Role for the Hedgehog Effector Gli1 in Mediating Stent-induced Ureteral Smooth Muscle Dysfunction and Aperistalsis.

OBJECTIVE: To better understand the effects of double J stenting on ureteral physiology and function. MATERIALS AND METHODS: In total, 24 pigs were stented cystoscopically unilaterally for 48 hours, 1, 2, 4, and 7 weeks. Controls consisted of un-stented animals (n = 4) or the contralateral un-stented ureter in pigs. Ureters were harvested and tested in tissue baths to evaluate their contractility. Ureteral inflammation and expression of Sonic Hedgehog (Shh) and the transcriptional activator Gli1 (the downstream target of active Hedgehog signaling) were assessed histologically and by immunohistochemistry, respectively. RESULTS: Indwelling ureteral stents were found to abolish normal ureteral function in all animals. Specifically, ureteral smooth muscle (SM) activity was significantly diminished within 48 hours after stenting and persisted at the 1-week time point. Furthermore, ureteral SM dysfunction was associated with increasing ureteral dilation due to the indwelling stent. Simultaneously, we observed a loss of Gli1 expression in SM cells, with a concomitant increase in ureteral inflammation. Expression of Shh was restricted to the urothelium and was not different between controls, stented, and contralateral ureters. CONCLUSION: Stent-induced aperistalsis was associated with diminished SM contractility, increased tissue inflammation, and reduced Gli1 expression in ureteral SM cells, independent of Shh expression. The present study is the first to show that indwelling stents negatively affect ureteral SM activity and identify a role for specific molecular mechanisms involved.

Rho-kinase mediated cytoskeletal stiffness in skinned smooth muscle.

The structurally dynamic cytoskeleton is important in many cell functions. Large gaps still exist in our knowledge regarding what regulates cytoskeletal dynamics and what underlies the structural plasticity. Because Rho-kinase is an upstream regulator of signaling events leading to phosphorylation of many cytoskeletal proteins in many cell types, we have chosen this kinase as the focus of the present study. In detergent skinned tracheal smooth muscle preparations, we quantified the proteins eluted from the muscle cells over time and monitored the muscle's ability to respond to acetylcholine (ACh) stimulation to produce force and stiffness. In a partially skinned preparation not able to generate active force but could still stiffen upon ACh stimulation, we found that the ACh-induced stiffness was independent of calcium and myosin light chain phosphorylation. This indicates that the myosin light chain-dependent actively cycling crossbridges are not likely the source of the stiffness. The results also indicate that Rho-kinase is central to the ACh-induced stiffness, because inhibition of the kinase by H1152 (1 µM) abolished the stiffening. Furthermore, the rate of relaxation of calcium-induced stiffness in the skinned preparation was faster than that of ACh-induced stiffness, with or without calcium, suggesting that different signaling pathways lead to different means of maintenance of stiffness in the skinned preparation.

Length oscillation mimicking periodic individual deep inspirations during tidal breathing attenuates force recovery and adaptation in airway smooth muscle.

Airway smooth muscle (ASM) is able to generate maximal force under static conditions, and this isometric force can be maintained over a large length range due to length adaptation. The increased force at short muscle length could lead to excessive narrowing of the airways. Prolonged exposure of ASM to submaximal stimuli also increases the muscle's ability to generate force in a process called force adaptation. To date, the effects of length and force adaptation have only been demonstrated under static conditions. In the mechanically dynamic environment of the lung, ASM is constantly subjected to periodic stretches by the parenchyma due to tidal breathing and deep inspiration. It is not known whether force recovery due to muscle adaptation to a static environment could occur in a dynamic environment. In this study the effect of length oscillation mimicking tidal breathing and deep inspiration was examined. Force recovery after a length change was attenuated in the presence of length oscillation, except at very short lengths. Force adaptation was abolished by length oscillation. We conclude that in a healthy lung (with intact airway-parenchymal tethering) where airways are not allowed to narrow excessively, large stretches (associated with deep inspiration) may prevent the ability of the muscle to generate maximal force that would occur under static conditions irrespective of changes in mean length; mechanical perturbation on ASM due to tidal breathing and deep inspiration, therefore, is the first line of defense against excessive bronchoconstriction that may result from static length and force adaptation.

Physical integrity of smooth muscle myosin filaments is enhanced by phosphorylation of the regulatory myosin light chain.

BACKGROUND AND AIMS: Smooth muscle myosin monomers self-assemble in solution to form filaments. Phosphorylation of the 20-kD regulatory myosin light chain (MLC20) enhances filament formation. It is not known whether the phosphorylated and non-phosphorylated filaments possess the same structural integrity. METHODS: We purified myosin from bovine trachealis to form filaments, in ATP-containing zero-calcium solution during a slow dialysis that gradually reduced the ionic strength. Sufficient myosin light chain kinase and phosphatase, as well as calmodulin, were retained after the myosin purification and this enabled phosphorylation of MLC20 within 20-40s after addition of calcium to the filament suspension. The phosphorylated and non-phosphorylated filaments were then partially disassembled by ultrasonification. The extent of filament disintegration was visualized and quantified by atomic force microscopy. RESULTS: MLC20 phosphorylation reduced the diameter of the filaments and rendered the filaments more resistant to ultrasonic agitation. Electron microscopy revealed a similar reduction in filament diameter in intact smooth muscle when the cells were activated. CONCLUSION: Modification of the structural and physical properties of myosin filaments by MLC20 phosphorylation may be a key regulation step in smooth muscle where formation and dissolution of the filaments are required in the cells' adaptation to different cell length.