Correlation between Mechanical Properties and Collagen Degeneration in Fibrous Tissue.

Fibrosis is a disease that causes abnormal accumulation of collagen and other extracellular matrix components. It can lead to organ failure and is responsible for one-third of all deaths worldwide. However, there is no cure for this disease, and the development of minimally invasive therapies is urgently needed. We have previously reported techniques for adjusting the shape and flexibility of fibrous tissue by traction while denaturing it with heat. However, studies comparing heat and traction on fibrous tissue are limited, so this paper examined that. Applying heat and traction to bovine Achilles tendon tissue has been shown to cause the denaturation of collagen molecules to accumulate in the tissue in response to these loads. Heat-induced collagen denaturation was nondirectional and omnidirectional, whereas mechanical stress-induced collagen denaturation was concentrated in the direction of traction. When both heat and traction were applied, collagen denaturation increased more than under a single load, indicating a synergistic effect.

Prospective clinical study for claudication after endovascular aneurysm repair involving hypogastric artery embolization.

PURPOSE: This prospective study aimed to assess the prognosis of claudication after endovascular aneurysm repair (EVAR) involving hypogastric artery (HGA) embolization. METHODS: Patients who were scheduled to undergo EVAR involving bilateral or unilateral HGA embolization (BHE or UHE, respectively) between May 2017 and January 2019 were included in this study. Patients underwent the walk test preoperatively, one week postoperatively, and monthly thereafter for six months. The presence of claudication and the maximum walking distance (MWD) were recorded. A near-infrared spectroscopy monitor was placed on the buttocks, and the recovery time (RT) was determined. A walking impairment questionnaire (WIQ) was completed to determine subjective symptoms. RESULTS: Of the 13 patients who completed the protocol, 12 experienced claudication in the 6-min walk test. The MWD was significantly lower at one week postoperatively than preoperatively. The claudication prevalence was significantly higher at five and six months postoperatively after BHE than after UHE. BHE was associated with longer RTs and lower WIQ scores than UHE. CONCLUSIONS: We noted a trend in adverse effects on the gluteal circulation and subjective symptoms ameliorating within six months postoperatively, with more effects being associated with BHE than with UHE. These findings should be used to make decisions concerning management strategies for HGA reconstruction.

Gliding performance is affected by cranial movement of abdominal organs.

Swimming is an extremely popular sport around the world. The streamlined body position is a crucial and foundational position for swimmers. Since the density of lungs is low, the center of buoyancy is always on the cranial side and the center of gravity is always on the caudal side. It has been reported that the greater the distance between the centers of buoyancy and gravity, the swimmer's legs will sink more. This is disadvantageous to swimming performance. However, the way to reduce the distance between the centers of buoyancy and gravity is yet to be elucidated. Here we show that swimmers with high gliding performance exhibit different abdominal cavity shapes in the streamlined body position, which causes cranial movement of the abdominal organs. This movement can reduce the distance between the centers of buoyancy and gravity, prevent the legs from sinking, and have a positive effect on gliding performance.

Non-invasive screening using ventilatory gas analysis to distinguish between chronic thromboembolic pulmonary hypertension and pulmonary arterial hypertension.

BACKGROUND AND OBJECTIVE: Clinical presentations associated with chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) at rest are highly similar. Differentiating between CTEPH and PAH using non-invasive techniques remains challenging. Thus, we examined whether analysis of ventilatory gas in response to postural changes can be useful as a non-invasive screening method for pulmonary hypertension (PH), and help differentiate CTEPH from PAH. METHODS: We prospectively enrolled 90 patients with suspected PH and performed right heart catheterization, ventilation/perfusion scan and ventilatory gas analysis. Various pulmonary function parameters were examined in the supine and sitting postures, and postural changes were calculated (Δ(supine - sitting)). RESULTS: In total, 25 patients with newly diagnosed PAH, 40 patients with newly diagnosed CTEPH and 25 non-PH patients were included. ΔEnd-tidal CO2 pressure (PET CO2 ) was significantly lower in patients with CTEPH and PAH than in non-PH patients (both P < 0.001). ΔPET CO2 < 0 mm Hg could effectively differentiate PH from non-PH (area under the curve (AUC) = 0.969, sensitivity = 89%, specificity = 100%). Postural change from sitting to supine significantly increased the ratio of ventilation to CO2 production (VE/VCO2 ) in the CTEPH group (P < 0.001). By contrast, VE/VCO2 significantly decreased in the PAH group (P = 0.001). Notably, CTEPH presented with higher ΔVE/VCO2 than PAH, although no differences were observed in haemodynamic and echocardiographic parameters between the two groups (P < 0.001). Furthermore, ΔVE/VCO2 > 0.8 could effectively differentiate CTEPH from PAH (AUC = 0.849, sensitivity = 78%, specificity = 88%). CONCLUSION: Postural changes in ventilatory gas analysis are useful as a non-invasive bedside evaluation to screen for the presence of PH and distinguish between CTEPH and PAH.

Usefulness of ventilatory gas analysis for the non-invasive evaluation of the severity of chronic thromboembolic pulmonary hypertension.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by organic thrombotic obstructions in the pulmonary arteries with reduced pulmonary vascular reserve. This study aimed to examine whether postural changes in ventilatory gas analysis parameters are useful for assessing pulmonary hemodynamics in patients with CTEPH. METHODS: A total of 44 patients with newly diagnosed CTEPH (CTEPH group), 33 patients with improved CTEPH (mean pulmonary arterial pressure [mPAP] <25 mm Hg), and 25 controls were enrolled. Patients with improved CTEPH referred to patients without residual PH who were previously diagnosed with CTEPH and already received optimal therapies. Various pulmonary function parameters were examined in supine and sitting positions, and postural changes were calculated (Δ[supine - sitting]). In 32 patients with CTEPH, we examined hemodynamic and ventilatory gas analysis parameters before the first balloon pulmonary angioplasty (BPA) and during follow-up. RESULTS: Patients with CTEPH had significantly lower supine end-tidal carbon dioxide pressure (PETCO2) and ΔPETCO2 than controls (both P < 0.001), and these parameters were significantly correlated with mPAP (R2 = 0.507, P < 0.0001 and R2 = 0.470, P < 0.001, respectively). Supine PETCO2 and ΔPETCO2 were significantly lower in patients with improved CTEPH than in controls (both P < 0.001). Hemodynamic and echocardiographic parameters were comparable in both groups. Furthermore, significant correlation between the change in mPAP and change in supine PETCO2 by BPA was noted (R2 = 0.478, P < 0.001). CONCLUSION: These results indicate that postural changes in ventilatory gas analysis parameters are useful and non-invasive method for the evaluation of mPAP, which is one of the hemodynamic parameters of CTEPH severity.

Hip flexor muscle dysfunction during walking at self-selected and fast speed in patients with aortoiliac peripheral arterial disease.

OBJECTIVE: Intermittent claudication aggravates physical function and is associated with an increased risk of death in patients with peripheral arterial disease (PAD). Previous studies on kinetic parameters (joint moment and power) of lower limbs in these patients have largely focused on the decline in the ankle plantar flexor moment and power at self-selected (SS) walking speed, which may not be an optimal condition to induce claudication pain. In the present study, we investigated the abnormalities in joint kinetic parameters in patients with PAD at both SS and at fast walking speeds. METHODS: We recruited 16 patients with aortoiliac PAD (4 unilateral and 12 bilateral) and 10 healthy controls. The participants were instructed to walk at SS and fast speeds along a 7-meter walkway embedded with a force plate. Spatiotemporal parameters and joint kinetic parameters of the lower limbs during the stance phase were recorded using a three-dimensional motion analysis device. RESULTS: Compared with the controls, patients with PAD showed a significant reduction in their walking speed, step length, stride length, and cadence. Further, a reduction in peak hip flexor moment at fast walking speed and in peak hip flexor generation power was observed in both modes of walking. However, no significant between-group differences were observed for the peak ankle plantar flexor moment or power at either walking speed. Multiple regression analysis showed peak hip flexor generation power was a strong contributor to reduction at both SS and fast walking speeds in patients with PAD. CONCLUSIONS: Patients with aortoiliac PAD walk slowly and show reduced kinetic parameters of the hip joint at both SS and fast walking speeds. Our results suggest that hip flexor muscles may be a useful target for exercise training in patients with aortoiliac PAD.

Chronic Running Exercise Alleviates Early Progression of Nephropathy with Upregulation of Nitric Oxide Synthases and Suppression of Glycation in Zucker Diabetic Rats.

Exercise training is known to exert multiple beneficial effects including renal protection in type 2 diabetes mellitus and obesity. However, the mechanisms regulating these actions remain unclear. The present study evaluated the effects of chronic running exercise on the early stage of diabetic nephropathy, focusing on nitric oxide synthase (NOS), oxidative stress and glycation in the kidneys of Zucker diabetic fatty (ZDF) rats. Male ZDF rats (6 weeks old) underwent forced treadmill exercise for 8 weeks (Ex-ZDF). Sedentary ZDF (Sed-ZDF) and Zucker lean (Sed-ZL) rats served as controls. Exercise attenuated hyperglycemia (plasma glucose; 242 ± 43 mg/dL in Sed-ZDF and 115 ± 5 mg/dL in Ex-ZDF) with increased insulin secretion (plasma insulin; 2.3 ± 0.7 and 5.3 ± 0.9 ng/mL), reduced albumin excretion (urine albumin; 492 ± 70 and 176 ± 11 mg/g creatinine) and normalized creatinine clearance (9.7 ± 1.4 and 4.5 ± 0.8 mL/min per body weight) in ZDF rats. Endothelial (e) and neuronal (n) NOS expression in kidneys of Sed-ZDF rats were lower compared with Sed-ZL rats (p<0.01), while both eNOS and nNOS expression were upregulated by exercise (p<0.01). Furthermore, exercise decreased NADPH oxidase activity, p47phox expression (p<0.01) and α-oxoaldehydes (the precursors for advanced glycation end products) (p<0.01) in the kidneys of ZDF rats. Additionally, morphometric evidence indicated renal damage was reduced in response to exercise. These data suggest that upregulation of NOS expression, suppression of NADPH oxidase and α-oxoaldehydes in the kidneys may, at least in part, contribute to the renal protective effects of exercise in the early progression of diabetic nephropathy in ZDF rats. Moreover, this study supports the theory that chronic aerobic exercise could be recommended as an effective non-pharmacological therapy for renoprotection in the early stages of type 2 diabetes mellitus and obesity.