Anatomy and pathology of lymphatic vessels under physiological and inflammatory conditions in the mouse diaphragm

Effects of body postures on respiratory muscle force and coughing in healthy people

The respiratory muscle force determines the intensity of cough force. A greater cough force for cleaning the airways is essential for preventing and managing pneumonia. Body posture can affect the onset of aspiration pneumonia. However, the effects of body posture on the respiratory muscle and cough forces remain unclear. Thus, we aimed to explore the influence of the four body postures on respiratory muscle force, cough pressure, subjective ease of coughing, and pulmonary function in healthy individuals. Twenty healthy individuals were included in this study. Body postures were 0-degree supine, 30- and 60-degree semi-recumbent, and 90-degree sitting. The maximal inspiratory and expiratory pressures, maximal cough pressure, subjective ease of coughing, and pulmonary function, including peak expiratory flow, were evaluated. We set the measured values in the supine posture to 100% and showed the relative values. The 60-degree posture showed stronger inspiratory (125.1 ± 3.9%, mean ± standard error [SE]) and expiratory (116.4 ± 3.0%) muscle force, cough pressure, more subjective ease of coughing, and greater peak expiratory flow (113.4 ± 3.0%) than the supine posture. The sitting posture also showed greater inspiratory muscle force and peak expiratory flow than the supine posture. The correlation coefficient for the 60-degree posture showed that the maximal inspiratory pressure was moderately correlated with the maximal expiratory pressure (r = 0.512), cough pressure (r = 0.495), and peak expiratory flow (r = 0.558). The above findings suggest the advantage of keeping a 60-degree posture and avoiding the supine posture to generate a greater cough force in the prevention and management of pneumonia.

Association between Low Forced Vital Capacity and High Pneumonia Mortality, and Impact of Muscle Power

Impaired % predicted value forced vital capacity (% FVC) is related to higher all-cause mortality in aged adults, and strong muscle force may improve this relationship. A muscle disease, sarcopenia, causes higher mortality. We aimed to identify the unknown disease that relates impaired % FVC with higher mortality in aged adults among the three major leading causes of death, and the effect of strong leg force on this relationship. Cox proportional hazard model analyzed the longitudinal Tsurugaya cohort that registered 1048 aged Japanese for 11 years. The primary outcome was the relationship between % FVC and mortality by cancer, cardiovascular disease, or pneumonia. Exposure variables were % FVC or leg force divided by 80% or median values, respectively. The secondary outcome was the effects of leg force on the relationship. Among the diseases, % FVC < 80% was related only to higher pneumonia mortality (hazard ratio [HR], 4.09; 95% CI, 1.90-8.83) relative to the % FVC ≥ 80% group before adjustment. Adding the leg force as an explanatory variable reduced the HR to 3.34 (1.54-7.25). Weak leg force might indicate sarcopenia, and its prevention may improve higher pneumonia mortality risk related to impaired % FVC, which we may advise people in clinical settings.

Differential regulation of lymphatic junctional morphology and the potential effects on cardiovascular diseases

The lymphatic vasculature provides an essential route to drain fluid, macromolecules, and immune cells from the interstitium as lymph, returning it to the bloodstream where the thoracic duct meets the subclavian vein. To ensure functional lymphatic drainage, the lymphatic system contains a complex network of vessels which has differential regulation of unique cell-cell junctions. The lymphatic endothelial cells lining initial lymphatic vessels form permeable "button-like" junctions which allow substances to enter the vessel. Collecting lymphatic vessels form less permeable "zipper-like" junctions which retain lymph within the vessel and prevent leakage. Therefore, sections of the lymphatic bed are differentially permeable, regulated in part by its junctional morphology. In this review, we will discuss our current understanding of regulating lymphatic junctional morphology, highlighting how it relates to lymphatic permeability during development and disease. We will also discuss the effect of alterations in lymphatic permeability on efficient lymphatic flux in health and how it may affect cardiovascular diseases, with a focus on atherosclerosis.

The Importance of the Diaphragm in Neuromotor Function in the Patient with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a constant and chronic narrowing of the respiratory airways, with numerous associated symptoms, not always related to the pathological adaptation of the lungs. Statistical projections show that COPD could become the third leading cause of death globally by 2030, with a significant increase in deaths by 2060. Skeletal muscle dysfunction, including the diaphragm, is one of the causes linked to the increase in mortality and hospitalization. Little emphasis is given by the scientific literature to the importance of the diaphragm towards functional neuromotor pathological expressions. The article reviews the adaptation of the skeletal muscles, with greater attention to the adaptations of the diaphragm, thereby highlighting the non-physiological variations that the main respiratory muscle undergoes and the neuromotor impairment found in COPD. The text could be an important reflection from a clinical and rehabilitation point of view, to direct greater attention to the function and adaptation of the diaphragm muscle.

Morphological, Mechanical and Hydrodynamic Aspects of Diaphragmatic Lymphatics

The diaphragmatic lymphatic vascular network has unique anatomical characteristics. Studying the morphology and distribution of the lymphatic network in the mouse diaphragm by fluorescence-immunohistochemistry using LYVE-1 (a lymphatic endothelial marker) revealed LYVE1⁺ structures on both sides of the diaphragm-both in its the muscular and tendinous portion, but with different vessel density and configurations. On the pleural side, most LYVE1⁺ configurations are vessel-like with scanty stomata, while the peritoneal side is characterized by abundant LYVE1⁺ flattened lacy-ladder shaped structures with several stomata-like pores, particularly in the muscular portion. Such a complex, three-dimensional organization is enriched, at the peripheral rim of the muscular diaphragm, with spontaneously contracting lymphatic vessel segments able to prompt contractile waves to adjacent collecting lymphatics. This review aims at describing how the external tissue forces developing in the diaphragm, along with cyclic cardiogenic and respiratory swings, interplay with the spontaneous contraction of lymphatic vessel segments at the peripheral diaphragmatic rim to simultaneously set and modulate lymph flow from the pleural and peritoneal cavities. These details may provide useful in understanding the role of diaphragmatic lymphatics not only in physiological but, more so, in pathophysiological circumstances such as in dialysis, metastasis or infection.