Effects of Long-Acting Muscarinic Antagonists on Promoting Ciliary Function in Airway Epithelium

Background Mucociliary clearance (MCC) is an essential defense mechanism in airway epithelia for removing pathogens from the respiratory tract. Impaired ciliary functions and MCC have been demonstrated in asthma and chronic obstructive pulmonary disease (COPD). Long-acting muscarinic antagonists (LAMAs) are a major class of inhaled bronchodilators, which are used for treating asthma and COPD; however, the effects of LAMAs on ciliary function remain unclear. This study aimed to identify the effects of LAMAs on airway ciliary functions. Methods Wild-type BALB/c mice were treated with daily intranasal administrations of glycopyrronium for 7 days, and tracheal samples were collected. Cilia-driven flow and ciliary activity, including ciliary beat frequency (CBF), ciliary beating amplitude, effective stroke velocity, recovery stroke velocity and the ratio of effective stroke velocity to recovery stroke velocity, were analyzed by imaging techniques. Using in vitro murine models, tracheal tissues were transiently cultured in media with/without LAMAs, glycopyrronium or tiotropium, for 60 min. Cilia-driven flow and ciliary activity were then analyzed. Well-differentiated normal human bronchial epithelial (NHBE) cells were treated with glycopyrronium, tiotropium, or vehicle for 60 min, and CBF was evaluated. Several mechanistic analyses were performed. Results Intranasal glycopyrronium administration for 7 days significantly increased cilia-driven flow and ciliary activity in murine airway epithelium. In the murine tracheal organ culture models, treatment with glycopyrronium or tiotropium for 60 min significantly increased cilia-driven flow and ciliary activity in airway epithelium. Further, we confirmed that 60-min treatment with glycopyrronium or tiotropium directly increased CBF in well-differentiated NHBE cells. In the mechanistic analyses, neither treatment with glycopyrronium nor tiotropium affected intracellular calcium ion concentrations in well-differentiated NHBE cells. Glycopyrronium did not increase protein kinase A activity in well-differentiated NHBE cells. Moreover, glycopyrronium had no effect on extracellular adenosine triphosphate concentration. Conclusions LAMAs exert a direct effect on airway epithelium to enhance ciliary function, which may improve impaired MCC in asthma and COPD. Further investigations are warranted to elucidate the underlying mechanisms of the effects of LAMAs on the promotion of airway ciliary function.

Effects of Long-acting Muscarinic Antagonists on Promoting Ciliary Function in Airway Epithelium

BackgroundMucociliary clearance (MCC) is an essential defense mechanism in airway epithelia for removing pathogens from the respiratory tract. Impaired ciliary functions and MCC have been demonstrated in asthma and chronic obstructive pulmonary disease (COPD). Long-acting muscarinic antagonists (LAMAs) are a major class of inhaled bronchodilators, which are used for treating asthma and COPD; however, the effects of LAMAs on ciliary function remain unclear. This study aimed to identify the effects of LAMAs on airway ciliary functions.MethodsWild-type BALB/c mice were treated with daily intranasal administrations of glycopyrronium for 7 days, and tracheal samples were collected. Cilia-driven flow and ciliary activity, including ciliary beat frequency (CBF), ciliary beating amplitude, effective stroke velocity, recovery stroke velocity and the ratio of effective stroke velocity to recovery stroke velocity, were analyzed by imaging techniques. Using in vitro murine models, tracheal tissues were transiently cultured in media with/without LAMAs, glycopyrronium or tiotropium, for 60 min. Cilia-driven flow and ciliary activity were then analyzed. Well-differentiated normal human bronchial epithelial (NHBE) cells were treated with glycopyrronium, tiotropium, or vehicle for 60 min, and CBF was evaluated. Several mechanistic analyses were performed.ResultsIntranasal glycopyrronium administration for 7 days significantly increased cilia-driven flow and ciliary activity in murine airway epithelium. In the murine tracheal organ culture models, treatment with glycopyrronium or tiotropium for 60 min significantly increased cilia-driven flow and ciliary activity in airway epithelium. Further, we confirmed that 60-min treatment with glycopyrronium or tiotropium directly increased CBF in well-differentiated NHBE cells. In the mechanistic analyses, neither treatment with glycopyrronium nor tiotropium affected intracellular calcium ion concentrations in well-differentiated NHBE cells. Glycopyrronium did not increase protein kinase A activity in well-differentiated NHBE cells. Moreover, glycopyrronium had no effect on extracellular adenosine triphosphate concentration.ConclusionsLAMAs exert a direct effect on airway epithelium to enhance ciliary function, which may improve impaired MCC in asthma and COPD. Further investigations are warranted to elucidate the underlying mechanisms of the effects of LAMAs on the promotion of airway ciliary function.

Hybrid metachronal rowing augments swimming speed and acceleration via increased stroke amplitude

Numerous aquatic invertebrates use drag-based metachronal rowing for swimming, in which closely spaced appendages are oscillated starting from the posterior, with each appendage phase-shifted in time relative to its neighbor. Continuously swimming species such as Antarctic krill generally use “pure metachronal rowing” consisting of a metachronal power stroke and a metachronal recovery stroke, while burst swimming species such as many copepods and mantis shrimp typically use “hybrid metachronal rowing” consisting of a metachronal power stroke followed by a synchronous or nearly synchronous recovery stroke. Burst swimming organisms need to rapidly accelerate in order to capture prey and/or escape predation, and it is unknown whether hybrid metachronal rowing can augment acceleration and swimming speed compared to pure metachronal rowing. Simulations of rigid paddles undergoing simple harmonic motion showed that collisions between adjacent paddles restrict the maximum stroke amplitude for pure metachronal rowing. Hybrid metachronal rowing similar to that observed in mantis shrimp (Neogonodactylus bredini) permits oscillation at larger stroke amplitude while avoiding these collisions. We comparatively examined swimming speed, acceleration, and wake structure of pure and hybrid metachronal rowing strategies by using a self-propelling robot. Both swimming speed and peak acceleration of the robot increased with increasing stroke amplitude. Hybrid metachronal rowing permitted operation at larger stroke amplitude without collision of adjacent paddles on the robot, augmenting swimming speed and peak acceleration. Hybrid metachronal rowing generated a dispersed wake unlike narrower, downward-angled jets generated by pure metachronal rowing. Our findings suggest that burst swimming animals with small appendage spacing, such as copepods and mantis shrimp, can use hybrid metachronal rowing to generate large accelerations via increasing stroke amplitude without concern of appendage collision.

CONSTRAINT INDUCED MOVEMENT THERAPY FOR MOTOR RECOVERY IN CHRONIC STROKE PATIENT IN RURAL INDIA

A possible explanation for the substantial remaining motor deficits in stroke patients might be the occurrence of learned nonuse, a phenomenon first described by Taub. Stroke patients who initially attempt to use the affected extremity find themselves unable to do so because the process of spontaneous recovery of function has not yet proceeded sufficiently far. This results in the experience of failure or punishment for attempts to move the extremity and in positive reinforcement for compensatory movements by the unaffected extremity-a learning process that might be supported by the teaching of compensatory activity during rehabilitation. Keywords: CIMT, Motor recovery, Stroke patients

Substrate binding and turnover modulate the affinity landscape of dihydrofolate reductase to increase its catalytic efficiency

It is generally accepted that enzymes structures evolved to stabilize the transition-state of a catalyzed reaction. Here, observing single molecules with a multi-turnover resolution, we provide experimental evidence for a more sophisticated narrative. We found that the binding of the NADPH cofactor to DHFR induces a first allosteric change that increases the affinity of the enzyme for the substrate. Then the enthalpy generated by the chemical step provides a power stroke that switches the enzyme to the product-bound conformations and promotes the release of the oxidized cofactor NADP+. The subsequent binding of NADPH to the vacated site provides the free energy for the recovery stroke, which induces the allosteric release of the product and resets the initial configuration. Intriguingly, the cycle is not perfect. Occasionally, DHFR undergoes second-long catalytic pauses, most likely reflecting the occupancy of an off-path conformation induced by excess energy liberated by the chemical step. This catalytic remodeling of the affinity landscape of DHFR is likely to have evolved to improve the efficiency of the reaction to cope with the high concentration of NADP+ in E. coli. And might be a general feature for complex enzymatic reaction where the binding and release of the products must be tightly controlled.

Abstract WP184: The Road to Recovery Stroke Support Group: A Feasibility Assessment of an Inpatient Multi-Disciplinary Stroke Support Group

Background: Stroke is life changing for both patients and caregivers. Recovery from stroke affects the physical, social and emotional aspects of life. Transitioning to a new normal should begin immediately after stroke, ideally during hospital admission. Most support groups exist outside of the hospital setting and begin weeks to months after the ictus. The Road to Recovery Stroke Support Group (RRSSG) was created to bridge the gap between the inpatient and outpatient setting. Purpose: RRSSG aims to provide a weekly platform for stroke survivors and caregivers in an in-hospital setting. During sessions, attendees learn about types of challenges after stroke, rehabilitation services available to them and what to expect after leaving the hospital. Patients can return to the same support group once discharged from the hospital. Methods: RRSSG was launched in November 2018. Candidates for the weekly RRSSG meeting were identified by nurses and the stroke case manager. Meetings were facilitated by a stroke survivor volunteer, case management and physical and social medicine. Invitations were extended to patients and their caregivers prior to discharge. Data were collected for 7 months and analyzed for the following: patient demographics, types of stroke and discharge disposition. Results: During the 7-month period, 514 patients were discharged with a stroke diagnosis, 24.3% of which attended the RRSSG. The demographics were 53.7% women with a median age of 66 years; 33.1% White/European, 36% Hispanic/Latino, 18.0% African American, 10.8% Asian, and 2.1% other. 61.6% had an ischemic stroke, 30.4% had an intracerebral hemorrhage, 11.2% had a subarachnoid hemorrhage. More patients who attended RRSSG were discharged to an acute rehabilitation hospital (6.5% RRSG vs. 1.8% non-RRSG, p=0.04). There was no difference in those discharged to: home (54.0% RRSSG vs. 55.5% non-RRSSG) and skilled nursing facility (27.3% RRSSG vs. 20.1% non-RRSSG). Conclusion: Creating and sustaining an inpatient multi-disciplinary stroke support group on a weekly basis is feasible. The future goals are to assess the impact of the in-hospital support group on stroke knowledge retention, medication compliance, post-stroke depression, recurrent stroke and re-admission rates.