Effects of aging and exercise training on bone and marrow blood flow and vascular function.

Aging leads to progressive bone loss, which is associated with impaired bone and marrow perfusion. The purpose of this study was to determine whether chronic exercise training enhances blood flow to the femur at rest and during exercise, and elucidate whether putative changes in training-induced bone perfusion are associated with alterations in the intrinsic vasomotor properties of the femoral principal nutrient artery (PNA) in old age. Young (4-6 mo old) and old (20-22 mo old) male Fischer-344 rats were either treadmill exercise trained (ET) or remained sedentary (SED).

Effect of diabetes on microvascular morphology and permeability of rat skeletal muscle: in vivo imaging using two-photon laser scanning microscopy.

This investigation evaluated the microvascular permeability and ultrastructure of skeletal muscle capillaries in the skeletal muscle of diabetic (DIA) rats using two-photon laser scanning microscopy (TPLSM) and transmission electron microscopy (TEM). Microvascular permeability was assessed in the tibialis anterior muscle of control (CON) and DIA (streptozocin) male Wistar rats ( = 20, 10-14 wk) by in vivo imaging using TPLSM after fluorescent dye intravenous infusion. Fluorescent dye leakage was quantified to determine microvascular permeability.

Effects of aging on diaphragm hyperemia and blood flow distribution in male and female Fischer 344 rats.

Aging is associated with inspiratory muscle dysfunction; however, the impact of aging on diaphragm blood flow (BF) regulation, and whether sex differences exist, is unknown. We tested the hypotheses in young animals that diaphragm BF and vascular conductance (VC) would be greater in females and that aging would decrease the diaphragm's ability to increase BF with contractions. Young (4-6 mo) and old (22-24 mo) Fischer 344 rats were divided into four groups: young female (YF, = 7), young male (YM, = 8), old female (OF, = 9), and old male (OM, = 9).

Adaptations of bone and bone vasculature to muscular stretch training.

The magnitude of bone formation and remodeling is linked to both the magnitude of strain placed on the bone and the perfusion of bone. It was previously reported that an increase in bone perfusion and bone density occurs in the femur of old rats with moderate aerobic exercise training. This study determined the acute and chronic effects of static muscle stretching on bone blood flow and remodeling.

Pulmonary hypertension impairs vasomotor function in rat diaphragm arterioles.

Pulmonary hypertension (PH) is a chronic, progressive condition in which respiratory muscle dysfunction is a primary contributor to exercise intolerance and dyspnea in patients. Contractile function, blood flow distribution, and the hyperemic response are altered in the diaphragm with PH, and we sought to determine whether this may be attributed, in part, to impaired vasoreactivity of the resistance vasculature. We hypothesized that there would be blunted endothelium-dependent vasodilation and impaired myogenic responsiveness in arterioles from the diaphragm of PH rats.

Pulmonary hypertension alters blood flow distribution and impairs the hyperemic response in the rat diaphragm.

Pulmonary hypertension (PH) is characterized by pulmonary vascular remodeling, respiratory muscle and cardiac impairments, and exercise intolerance. Specifically, impaired gas exchange increases work of the diaphragm; however, compromised contractile function precludes the diaphragm from meeting the increased metabolic demand of chronic hyperventilation in PH. Given that muscle contractile function is in part, dependent upon adequate blood flow (), diaphragmatic dysfunction may be predicated by an inability to match oxygen delivery with oxygen demand.

Impaired microvascular reactivity in patients treated with 5-fluorouracil chemotherapy regimens: Potential role of endothelial dysfunction.

Background: 5-fluorouracil (5-FU) is the second most common cancer chemotherapy associated with short- and long-term cardiotoxicity. Although the mechanisms mediating these toxicities are not well understood, patients often present with symptoms suggestive of microvascular dysfunction. We tested the hypotheses that patients undergoing cancer treatment with 5-FU based chemotherapy regimens would present with impaired microvascular reactivity and that these findings would be substantiated by decrements in endothelial nitric oxide synthase (eNOS) gene expression in 5-FU treated human coronary artery endothelial cells (HCAEC).

Head-up tilt does not enhance prostate tumor perfusion or oxygenation in young rats.

Solid tumors contain hypoxic regions that contribute to anticancer therapy resistance. Thus, mitigating tumor hypoxia may enhance the efficacy of radiation therapy which is commonly utilized for patients with prostate cancer. Increasing perfusion pressure in the prostate with head-up tilt (HUT) may augment prostate tumor perfusion and decrease hypoxia.

A Rare Case of Hemophagocytic Lymphohistiocytosis in an Adult.

This case report involves an adult patient diagnosed with a rare disease, hemophagocytic lymphohistiocytosis (HLH). We will discuss the patient's clinical presentation, symptoms, and treatment. Due to the rarity of HLH being found in adults, we will break down the essential elements to recognize and diagnose this disease.

Supplemental oxygen administration during mechanical ventilation reduces diaphragm blood flow and oxygen delivery.

During mechanical ventilation (MV), supplemental oxygen (O) is commonly administered to critically ill patients to combat hypoxemia. Previous studies demonstrate that hyperoxia exacerbates MV-induced diaphragm oxidative stress and contractile dysfunction. Whereas normoxic MV (i.

Prediction of loss of correction after hemiepiphysiodesis for the alignment of lower limb angular deformities.

Guided growth by temporary hemiepiphysiodesis (HEPD) is established for the alignment of lower limb angular deformities. This retrospective cohort study was designed to assess the effect of HEPD in idiopathic coronal plane deformities around the knee and on the frontal knee joint line orientation, and to test the frontal knee joint line as predictive means for recurrence.Fourty-four patients (78 deformities: valgus n = 64, varus n = 14) were enrolled in the retrospective observational study.

Post-occlusive reactive hyperemia and skeletal muscle capillary hemodynamics.

Unlabelled: Post-occlusive reactive hyperemia (PORH) is an accepted diagnostic tool for assessing peripheral macrovascular function. While conduit artery hemodynamics have been well defined, the impact of PORH on capillary hemodynamics remains unknown, despite the microvasculature being the dominant site of vascular control. Therefore, the purpose of this investigation was to determine the effects of 5 min of feed artery occlusion on capillary hemodynamics in skeletal muscle.

Prolonged mechanical ventilation increases diaphragm arteriole circumferential stretch without changes in stress/stretch: Implications for the pathogenesis of ventilator-induced diaphragm dysfunction.

Introduction: Prolonged mechanical ventilation (MV; ≥6 h) results in large, time-dependent reductions in diaphragmatic blood flow and shear stress. We tested the hypothesis that MV would impair the structural and material properties (ie, increased stress/stretch relation and/or circumferential stretch) of first-order arterioles (1A) from the medial costal diaphragm.

Methods: Shear stress was estimated from isolated arterioles and prior blood flow data from the diaphragm during spontaneous breathing (SB) and prolonged MV (6 h MV).

Sexual dimorphism in vascular ATP-sensitive K channel function supporting interstitial via convective and/or diffusive O transport.

Key Points: Inhibition of pancreatic ATP-sensitive K (K ) channels is the intended effect of oral sulphonylureas to increase insulin release in diabetes. However, pertinent to off-target effects of sulphonylurea medication, sex differences in cardiac K channel function exist, whereas potential sex differences in vascular K channel function remain unknown. In the present study, we assessed vascular K channel function (topical glibenclamide superfused onto fast-twitch oxidative skeletal muscle) supporting blood flow and interstitial O delivery-utilization matching ( is) during twitch contractions in male, female during pro-oestrus and ovariectomized female (F+OVX) rats.

Aerobic exercise training reduces cardiac function and coronary flow-induced vasodilation in mice lacking adiponectin.

We tested the hypothesis that adiponectin deficiency attenuates cardiac and coronary microvascular function and prevents exercise training-induced adaptations of the myocardium and the coronary microvasculature in adult mice. Adult wild-type (WT) or adiponectin knockout (adiponectin KO) mice underwent treadmill exercise training or remained sedentary for 8-10 wk. Systolic and diastolic functions were assessed before and after exercise training or cage confinement.

Effects of high-intensity training on prostate cancer-induced cardiac atrophy.

Background: Recent evidence suggests prostate cancer independent of treatment has atrophic effects on whole heart and left ventricular (LV) masses, associated with reduced endurance exercise capacity. In a pre-clinical model, we tested the hypothesis that high-intensity training could prevent cardiac atrophy with prostate cancer and alter cardiac protein degradation mechanisms.

Methods: Dunning R-3327 AT-1 prostate cancer cells (1×10) were injected into the ventral prostate lobe of 5-6 mo immunocompetent Copenhagen rats (n=24).

Vascular ATP-sensitive K channels support maximal aerobic capacity and critical speed via convective and diffusive O transport.

Key Points: Oral sulphonylureas, widely prescribed for diabetes, inhibit pancreatic ATP-sensitive K (K ) channels to increase insulin release. However, K channels are also located within vascular (endothelium and smooth muscle) and muscle (cardiac and skeletal) tissue. We evaluated left ventricular function at rest, maximal aerobic capacity ( O max) and submaximal exercise tolerance (i.

Effects of elevated positive end-expiratory pressure on diaphragmatic blood flow and vascular resistance during mechanical ventilation.

Although mechanical ventilation (MV) is a life-saving intervention, prolonged MV can lead to deleterious effects on diaphragm function, including vascular incompetence and weaning failure. During MV, positive end-expiratory pressure (PEEP) is used to maintain small airway patency and mitigate alveolar damage. We tested the hypothesis that increased intrathoracic pressure with high levels of PEEP would increase diaphragm vascular resistance and decrease perfusion.

Transcapillary PO gradients in contracting muscles across the fibre type and oxidative continuum.

Key Points: Within skeletal muscle the greatest resistance to oxygen transport is thought to reside across the short distance at the red blood cell-myocyte interface. These structures generate a significant transmural oxygen pressure (PO ) gradient in mixed fibre-type muscle. Increasing O flux across the capillary wall during exercise depends on: (i) the transmural O pressure gradient, which is maintained in mixed-fibre muscle, and/or (ii) elevating diffusing properties between microvascular and interstitial compartments resulting, in part, from microvascular haemodynamics and red blood cell distribution.

DEVELOPMENT OF A NEW SECONDARY STANDARD FOR H*(10).

A secondary standard for ambient dose equivalent, H*(10), is necessary for the dissemination of the unit Sievert (Sv), but there is no such standard commercially available currently. Furthermore, the measurement of H*(10) instead of calculating H*(10) from air kerma and conversion coefficients is needed for unknown radiation fields. We developed a prototype of a new secondary standard for H*(10) based on a spherical 1 l ionization chamber for air kerma.

The role of vascular function on exercise capacity in health and disease.

Three sentinel parameters of aerobic performance are the maximal oxygen uptake ( ), critical power (CP) and speed of the kinetics following exercise onset. Of these, the latter is, perhaps, the cardinal test of integrated function along the O transport pathway from lungs to skeletal muscle mitochondria. Fast kinetics demands that the cardiovascular system distributes exercise-induced blood flow elevations among and within those vascular beds subserving the contracting muscle(s).

Central and peripheral factors mechanistically linked to exercise intolerance in heart failure with reduced ejection fraction.

Exercise intolerance is a primary symptom of heart failure (HF); however, the specific contribution of central and peripheral factors to this intolerance is not well described. The hyperbolic relationship between exercise intensity and time to exhaustion (speed-duration relationship) defines exercise tolerance but is underused in HF. We tested the hypotheses that critical speed (CS) would be reduced in HF, resting central functional measurements would correlate with CS, and the greatest HF-induced peripheral dysfunction would occur in more oxidative muscle.

Daily Passive Muscle Stretching Improves Flow-Mediated Dilation of Popliteal Artery and 6-minute Walk Test in Elderly Patients with Stable Symptomatic Peripheral Artery Disease.

Background: Patients with peripheral arterial disease (PAD) often have walking impairment due to insufficient oxygen supply to skeletal muscle. In aged rats, we have shown that daily stretching of calf muscles improves endothelium-dependent dilation of arterioles from the soleus muscle and increases capillarity and muscle blood flow during exercise. Therefore, we hypothesized that daily muscle stretching of calf muscles would improve endothelium-dependent vasodilation of the popliteal artery and walking function in PAD patients.