We summarize from previous works the functions of circular vs. longitudinal muscle in esophageal peristaltic bolus transport using a mix of experimental data, the conservation laws of mechanics and mathematical modeli...We summarize from previous works the functions of circular vs. longitudinal muscle in esophageal peristaltic bolus transport using a mix of experimental data, the conservation laws of mechanics and mathematical modeling. Whereas circular muscle tone generates radial closure pressure to create a local peristaltic closure wave, longitudinal muscle tone has two functions, one physiological with mechanical implications, and one purely mechanical. Each of these functions independently reduces the tension of individual circular muscle fibers to maintain closure as a consequence of shortening of longitudinal muscle locally coordinated with increasing circular muscle tone. The physiological function is deduced by combining basic laws of mechanics with concurrent measurements of intraluminal pressure from manometry, and changes in cross sectional muscle area from endoluminal ultrasound from which local longitudinal shortening (LLS) can be accurately obtained. The purely mechanical function of LLS was discovered from mathematical modeling of peristaltic esophageal transport with the axial wall motion generated by LLS. Physiologically, LLS concentrates circular muscle fibers where closure pressure is highest. However, the mechanical function of LLS is to reduce the level of pressure required to maintain closure. The combined physiological and mechanical consequences of LLS are to reduce circular muscle fiber tension and power by as much as 1/10 what would be requiredfor peristalsis without the longitudinal muscle layer, a tremendous benefit that may explain the existence of longitudinal muscle fiber in the gut. We also review what is understood of the role of longitudinal muscle in esophageal emptying, reflux and pathology.展开更多
Objective BAG3-related myopathy is a rare condition so far reported in twenty patients worldwide.The purpose of this study was to draw attention to this rare disease and to the fact that BAG3-related myopathy should b...Objective BAG3-related myopathy is a rare condition so far reported in twenty patients worldwide.The purpose of this study was to draw attention to this rare disease and to the fact that BAG3-related myopathy should be considered as a rare differential diagnosis of hypercapnia.Methods We report a sporadic case of a 14-year-old Chinese girl with a de novo p.Pro209 Leu mutation in BAG3 and reviewed the literatures for reported cases related to this mutation.Results We described a 14-year-old Chinese girl who presented with gradually appearing symptoms of hypercapnia that required assisted ventilation.The muscle biopsy and the blood whole-exome sequencing results confirmed the diagnosis of myofibrillar myopathy with a de novo p.Pro209 Leu mutation in BAG3.Totally twentyone patients from twenty families with a confirmed diagnosis of BAG3-related myopathy were reported to date,including this patient and literature review.The male to female ratio was 11:10 and most showed initial symptoms in the first decade of life.Most patients presented toe/clumsy walking or running as the onset symptom,followed by muscle weakness or atrophy.Creatine kinase levels were elevated in fourteen patients and were normal in three.Eighteen patients developed respiratory insufficiency during the disease course and thirteen(one could not tolerate non-invasive assisted ventilation)required non-invasive assisted ventilation for treatment.Except for one not reported,heart involvement was found in seventeen patients during the disease course and seven underwent heart transplantation.Z-disk streaming and aggregation could be observed in most of the patients’muscle histology.In the long-term follow-up,five patients died of cardiac or respiratory failure.Conclusion BAG3-associated myopathy is a rare type of myofibrillar myopathy.It should be considered as a rare differential diagnosis of hypercapnia.展开更多
文摘We summarize from previous works the functions of circular vs. longitudinal muscle in esophageal peristaltic bolus transport using a mix of experimental data, the conservation laws of mechanics and mathematical modeling. Whereas circular muscle tone generates radial closure pressure to create a local peristaltic closure wave, longitudinal muscle tone has two functions, one physiological with mechanical implications, and one purely mechanical. Each of these functions independently reduces the tension of individual circular muscle fibers to maintain closure as a consequence of shortening of longitudinal muscle locally coordinated with increasing circular muscle tone. The physiological function is deduced by combining basic laws of mechanics with concurrent measurements of intraluminal pressure from manometry, and changes in cross sectional muscle area from endoluminal ultrasound from which local longitudinal shortening (LLS) can be accurately obtained. The purely mechanical function of LLS was discovered from mathematical modeling of peristaltic esophageal transport with the axial wall motion generated by LLS. Physiologically, LLS concentrates circular muscle fibers where closure pressure is highest. However, the mechanical function of LLS is to reduce the level of pressure required to maintain closure. The combined physiological and mechanical consequences of LLS are to reduce circular muscle fiber tension and power by as much as 1/10 what would be requiredfor peristalsis without the longitudinal muscle layer, a tremendous benefit that may explain the existence of longitudinal muscle fiber in the gut. We also review what is understood of the role of longitudinal muscle in esophageal emptying, reflux and pathology.
基金supported by the Youth Program of National Natural Science Foundation of China(Grant No.82003309)the National Key Research and Development Program of China(Grant 2020YFB1313700)。
文摘Objective BAG3-related myopathy is a rare condition so far reported in twenty patients worldwide.The purpose of this study was to draw attention to this rare disease and to the fact that BAG3-related myopathy should be considered as a rare differential diagnosis of hypercapnia.Methods We report a sporadic case of a 14-year-old Chinese girl with a de novo p.Pro209 Leu mutation in BAG3 and reviewed the literatures for reported cases related to this mutation.Results We described a 14-year-old Chinese girl who presented with gradually appearing symptoms of hypercapnia that required assisted ventilation.The muscle biopsy and the blood whole-exome sequencing results confirmed the diagnosis of myofibrillar myopathy with a de novo p.Pro209 Leu mutation in BAG3.Totally twentyone patients from twenty families with a confirmed diagnosis of BAG3-related myopathy were reported to date,including this patient and literature review.The male to female ratio was 11:10 and most showed initial symptoms in the first decade of life.Most patients presented toe/clumsy walking or running as the onset symptom,followed by muscle weakness or atrophy.Creatine kinase levels were elevated in fourteen patients and were normal in three.Eighteen patients developed respiratory insufficiency during the disease course and thirteen(one could not tolerate non-invasive assisted ventilation)required non-invasive assisted ventilation for treatment.Except for one not reported,heart involvement was found in seventeen patients during the disease course and seven underwent heart transplantation.Z-disk streaming and aggregation could be observed in most of the patients’muscle histology.In the long-term follow-up,five patients died of cardiac or respiratory failure.Conclusion BAG3-associated myopathy is a rare type of myofibrillar myopathy.It should be considered as a rare differential diagnosis of hypercapnia.
