128 resultados para CIRCULATORY AND RESPIRATORY PHYSIOLOGY
Resumo:
A venous ulcer is the end result of a long pathological process where venous hypertension represents the principal cause of a number of complications. The physiotherapist by adapting various different therapeutic approaches improves the vascular, joint and respiratory problems of these patients.
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Black-blood fast spin-echo imaging is a powerful technique for the evaluation of cardiac anatomy. To avoid fold-over artifacts, using a sufficiently large field of view in phase-encoding direction is mandatory. The related oversampling affects scanning time and respiratory chest motion artifacts are commonly observed. The excitation of a volume that exclusively includes the heart without its surrounding structures may help to improve scan efficiency and minimize motion artifacts. Therefore, and by building on previously reported inner-volume approach, the combination of a black-blood fast spin-echo sequence with a two-dimensionally selective radiofrequency pulse is proposed for selective "local excitation" small field of view imaging of the heart. This local excitation technique has been developed, implemented, and tested in phantoms and in vivo. With this method, small field of view imaging of a user-specified region in the human thorax is feasible, scanning becomes more time efficient, motion artifacts can be minimized, and additional flexibility in the choice of imaging parameters can be exploited.
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Insight into the function of sleep may be gained by studying animals in the ecological context in which sleep evolved. Until recently, technological constraints prevented electroencephalogram (EEG) studies of animals sleeping in the wild. However, the recent development of a small recorder (Neurologger 2) that animals can carry on their head permitted the first recordings of sleep in nature. To facilitate sleep studies in the field and to improve the welfare of experimental animals, herein, we test the feasibility of using minimally invasive surface and subcutaneous electrodes to record the EEG in barn owls. The EEG and behaviour of four adult owls in captivity and of four chicks in a nest box in the field were recorded. We scored a 24-h period for each adult bird for wakefulness, slow-wave sleep (SWS), and rapid-eye movement (REM) sleep using 4 s epochs. Although the quality and stability of the EEG signals recorded via subcutaneous electrodes were higher when compared to surface electrodes, the owls' state was readily identifiable using either electrode type. On average, the four adult owls spent 13.28 h awake, 9.64 h in SWS, and 1.05 h in REM sleep. We demonstrate that minimally invasive methods can be used to measure EEG-defined wakefulness, SWS, and REM sleep in owls and probably other animals.
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Hepatorenal syndrome is a particular form of functional renal failure which may develop in patients with liver cirrhosis. On a clinical standpoint, precise diagnostic criteria have been established to clearly define this entity, whereas recent advances in the understanding of the biology of vasoactive mediators and the physiology of microcirculation have allowed to better anticipate its pathophysiological mechanisms. During the course of cirrhosis, sinusoidal portal hypertension leads to splanchnic and systemic vasodilation, responsible for a reduction of effective arterial blood volume. As a result, a state of intense renal vasoconstriction develops, leading to renal failure in the absence of any organic renal disease. At this stage, liver transplantation is the only definitive therapy able to reverse renal dysfunction. In recent years, innovative therapies have shown promise to prolong survival in patients with hepatorenal syndrome, including the administration of analogs of vasopressin (mainly terlipressin), the insertion of transjugular intrahepatic portosystemic shunts and the use of novel techniques of dialysis. On a preventive viewpoint, several simple measures have been shown to reduce the risk of hepatorenal syndrome in cirrhotic patients, including the appropriate use of diuretics, the avoidance of nephrotoxic drugs, the prophylaxis of spontaneous bacterial peritonitis and optimal fluid management in patients undergoing large volume paracentesis.
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The ability to withstand environmental temperature variation is essential for plant survival. Former studies in Arabidopsis revealed that light signalling pathways had a potentially unique role in shielding plant growth and development from seasonal and daily fluctuations in temperature. In this paper we describe the molecular circuitry through which the light receptors cry1 and phyB buffer the impact of warm ambient temperatures. We show that the light signalling component HFR1 acts to minimise the potentially devastating effects of elevated temperature on plant physiology. Light is known to stabilise levels of HFR1 protein by suppressing proteasome-mediated destruction of HFR1. We demonstrate that light-dependent accumulation and activity of HFR1 are highly temperature dependent. The increased potency of HFR1 at warmer temperatures provides an important restraint on PIF4 that drives elongation growth. We show that warm ambient temperatures promote the accumulation of phosphorylated PIF4. However, repression of PIF4 activity by phyB and cry1 (via HFR1) is critical for controlling growth and maintaining physiology as temperatures rise. Loss of this light-mediated restraint has severe consequences for adult plants which have greatly reduced biomass.
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Introduction : Population aging leads to a considerable increase in the prevalence of specific diseases. We aimed to assess if those changes were already reflected in an Internal Medicine ward. Methods : Anonymous data was obtained from the administrative database of the department of internal medicine of the Lausanne University Hospital (CHUV). All hospitalizations of adult (>=18 years) patients occurring between 2003 and 2011 were included. Infections, cancers and diseases according to body system (heart, lung...) were defined by the first letter of the ICD-10 code for the main cause of hospitalization. Specific diseases (myocardial infarction, heart failure...) were defined by the first three letters of the ICD-10 codes for the main cause of hospitalization. Results : Data from 32,741 hospitalizations occurring between 2003 and 2011 was analyzed. Cardiovascular (ICD-10 code I) and respiratory (ICD-10 code J) diseases ranked first and second, respectively, and their ranks did not change during the study period (figure). Digestive and endocrine diseases decreased while psychiatric diseases increased from rank 9 in 2003 to rank 6 in 2011 (figure). Among specific diseases, pneumonia (organism unspecified, code J18) ranked first in 2003 and second in 2011. Acute myocardial infarction (code I21) ranked second in 2003 and third in 2011. Chronic obstructive pulmonary disease with acute lower respiratory infection (code J44) ranked third in 2003 and decreased to rank 8 in 2011. Conversely, heart failure (code I50) increased from rank 8 in 2003 to rank 1 in 2011 and delirium (not induced by alcohol and other psychoactive substances, code F05) increased from below rank 20 in 2003 to rank 4 in 2011. For more details, see table. Conclusion : In less than 10 years, considerable changes occurred in the presentation of patients attending an Internal Medicine ward. The changes in diseases call for adaptations in hospital staff and logistics.
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The brain regulates all metabolic processes within the organism, and therefore, its energy supply is preserved even during fasting. However, the underlying mechanism is unknown. Here, it is shown, using (31)P-magnetic resonance spectroscopy that during short periods of hypoglycemia and hyperglycemia, the brain can rapidly increase its high-energy phosphate content, whereas there is no change in skeletal muscle. We investigated the key metabolites of high-energy phosphate metabolism as rapidly available energy stores by (31)P MRS in brain and skeletal muscle of 17 healthy men. Measurements were performed at baseline and during dextrose or insulin-induced hyperglycemia and hypoglycemia. During hyperglycemia, phosphocreatine (PCr) concentrations increased significantly in the brain (P = 0.013), while there was a similar trend in the hypopglycemic condition (P = 0.055). Skeletal muscle content remained constant in both conditions (P > 0.1). ANOVA analyses comparing changes from baseline to the respective glycemic plateau in brain (up to +15%) vs. muscle (up to -4%) revealed clear divergent effects in both conditions (P < 0.05). These effects were reflected by PCr/Pi ratio (P < 0.05). Total ATP concentrations revealed the observed divergency only during hyperglycemia (P = 0.018). These data suggest that the brain, in contrast to peripheral organs, can activate some specific mechanisms to modulate its energy status during variations in glucose supply. A disturbance of these mechanisms may have far-reaching implications for metabolic dysregulation associated with obesity or diabetes mellitus.
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The epithelial sodium channel (ENaC) is responsible for Na(+) and fluid absorption across colon, kidney, and airway epithelia. Short palate lung and nasal epithelial clone 1 (SPLUNC1) is a secreted, innate defense protein and an autocrine inhibitor of ENaC that is highly expressed in airway epithelia. While SPLUNC1 has a bactericidal permeability-increasing protein (BPI)-type structure, its NH2-terminal region lacks structure. Here we found that an 18 amino acid peptide, S18, which corresponded to residues G22-A39 of the SPLUNC1 NH2 terminus inhibited ENaC activity to a similar degree as full-length SPLUNC1 (∼2.5 fold), while SPLUNC1 protein lacking this region was without effect. S18 did not inhibit the structurally related acid-sensing ion channels, indicating specificity for ENaC. However, S18 preferentially bound to the βENaC subunit in a glycosylation-dependent manner. ENaC hyperactivity is contributory to cystic fibrosis (CF) lung disease. Unlike control, CF human bronchial epithelial cultures (HBECs) where airway surface liquid (ASL) height was abnormally low (4.2 ± 0.6 μm), addition of S18 prevented ENaC-led ASL hyperabsorption and maintained CF ASL height at 7.9 ± 0.6 μm, even in the presence of neutrophil elastase, which is comparable to heights seen in normal HBECs. Our data also indicate that the ENaC inhibitory domain of SPLUNC1 may be cleaved away from the main molecule by neutrophil elastase, suggesting that it may still be active during inflammation or neutrophilia. Furthermore, the robust inhibition of ENaC by the S18 peptide suggests that this peptide may be suitable for treating CF lung disease.
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MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression post-transcriptionally. MiRNAs are implicated in various biological processes associated with obesity, including adipocyte differentiation and lipid metabolism. We used a neuronal-specific inhibition of miRNA maturation in adult mice to study the consequences of miRNA loss on obesity development. Camk2a-CreERT2 (Cre+) and floxed Dicer (Dicerlox/lox) mice were crossed to generate tamoxifen-inducible conditional Dicer knockouts (cKO). Vehicle- and/or tamoxifen-injected Cre+;Dicerlox/lox and Cre+;Dicer+/+ served as controls. Four cohorts were used to a) measure body composition, b) follow food intake and body weight dynamics, c) evaluate basal metabolism and effects of food deprivation, and d) assess the brain transcriptome consequences of miRNA loss. cKO mice developed severe obesity and gained 18 g extra weight over the 5 weeks following tamoxifen injection, mainly due to increased fat mass. This phenotype was highly reproducible and observed in all 38 cKO mice recorded and in none of the controls, excluding possible effects of tamoxifen or the non-induced transgene. Development of obesity was concomitant with hyperphagia, increased food efficiency, and decreased activity. Surprisingly, after reaching maximum body weight, obese cKO mice spontaneously started losing weight as rapidly as it was gained. Weight loss was accompanied by lowered O2-consumption and respiratory-exchange ratio. Brain transcriptome analyses in obese mice identified several obesity-related pathways (e.g. leptin, somatostatin, and nemo-like kinase signaling), as well as genes involved in feeding and appetite (e.g. Pmch, Neurotensin) and in metabolism (e.g. Bmp4, Bmp7, Ptger1, Cox7a1). A gene cluster with anti-correlated expression in the cerebral cortex of post-obese compared to obese mice was enriched for synaptic plasticity pathways. While other studies have identified a role for miRNAs in obesity, we here present a unique model that allows for the study of processes involved in reversing obesity. Moreover, our study identified the cortex as a brain area important for body weight homeostasis.
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Chest physiotherapy (CP) using passive expiratory manoeuvres is widely used in Western Europe for the treatment of bronchiolitis, despite lacking evidence for its efficacy. We undertook an open randomised trial to evaluate the effectiveness of CP in infants hospitalised for bronchiolitis by comparing the time to clinical stability, the daily improvement of a severity score and the occurrence of complications between patients with and without CP. Children <1 year admitted for bronchiolitis in a tertiary hospital during two consecutive respiratory syncytial virus seasons were randomised to group 1 with CP (prolonged slow expiratory technique, slow accelerated expiratory flow, rarely induced cough) or group 2 without CP. All children received standard care (rhinopharyngeal suctioning, minimal handling, oxygen for saturation ≥92%, fractionated meals). Ninety-nine eligible children (mean age, 3.9 months), 50 in group 1 and 49 in group 2, with similar baseline variables and clinical severity at admission. Time to clinical stability, assessed as primary outcome, was similar for both groups (2.9 ± 2.1 vs. 3.2 ± 2.8 days, P = 0.45). The rate of improvement of a clinical and respiratory score, defined as secondary outcome, only showed a slightly faster improvement of the respiratory score in the intervention group when including stethoacoustic properties (P = 0.044). Complications were rare but occurred more frequently, although not significantly (P = 0.21), in the control arm. In conclusion, this study shows the absence of effectiveness of CP using passive expiratory techniques in infants hospitalised for bronchiolitis. It seems justified to recommend against the routine use of CP in these patients.
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Fasting is associated with significant changes in nutrient metabolism, many of which are governed by transcription factors that regulate the expression of rate-limiting enzymes. One factor that plays an important role in the metabolic response to fasting is the peroxisome proliferator-activated receptor alpha (PPARalpha). To gain more insight into the role of PPARalpha during fasting, and into the regulation of metabolism during fasting in general, a search for unknown PPARalpha target genes was performed. Using subtractive hybridization (SABRE) comparing liver mRNA from wild-type and PPARalpha null mice, we isolated a novel PPARalpha target gene, encoding the secreted protein FIAF (for fasting induced adipose factor), that belongs to the family of fibrinogen/angiopoietin-like proteins. FIAF is predominantly expressed in adipose tissue and is strongly up-regulated by fasting in white adipose tissue and liver. Moreover, FIAF mRNA is decreased in white adipose tissue of PPARgamma +/- mice. FIAF protein can be detected in various tissues and in blood plasma, suggesting that FIAF has an endocrine function. Its plasma abundance is increased by fasting and decreased by chronic high fat feeding. The data suggest that FIAF represents a novel endocrine signal involved in the regulation of metabolism, especially under fasting conditions.
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Coagulopathy and alveolar fibrin deposition are common in sick neonates and attributed to the primary disease, as opposed to their ventilatory support. Hypothesizing that high tidal volume ventilation activates the extrinsic coagulation pathway, we air ventilated newborn and adult rats at low (10 ml/kg) or high (30 ml/kg) tidal volume and compared them with age-matched nonventilated controls. Blood was collected at the end of the experiment for measurement of clot time, tissue factor, and other coagulation factor content. Similar measurements were obtained from lung lavage material. The newborn clot time (44+/-1) was lower and plasma tissue factor content higher (103.4+/-0.4) than adults (88+/-4 s and 26.6+/-1.4 units; P<0.01). High, but not low, tidal volume ventilation of newborns for as little as 15 min significantly reduced clot time and increased plasma tissue factor content (P<0.01). High volume ventilation increased plasma factor Xa (0.1+/-0.1 to 1.6+/-0.4 nM; P<0.01) and thrombin (1.3+/-0.2 to 2.2+/-0.4 nM; P<0.05) and decreased antithrombin (0.12+/-0.01 to 0.05+/-0.01; P<0.01) in the newborn. Lung lavage material of high volume-ventilated newborns showed increased (P<0.01) factor Xa and thrombin. No changes in these parameters were observed in adult rats that were high volume ventilated for up to 90 min. Compared with adults, newborn rats have a greater propensity for volutrauma-activated intravascular coagulation. These data suggest that mechanical ventilation promotes neonatal thrombosis via lung tissue factor release.
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High altitude constitutes an exciting natural laboratory for medical research. Over the past decade, high-altitude studies have provided important new insight into the regulation of the pulmonary circulation. Studies in high-altitude pulmonary edema (HAPE)-prone subjects, a condition characterized by exaggerated hypoxic pulmonary hypertension, have provided evidence for the central role of pulmonary vascular endothelial and respiratory epithelial nitric oxide for pulmonary artery pressure homeostasis. Studies of healthy and maladapted high-altitude dwellers have provide important new insight into mechanisms conferring protection against/predisposing to pulmonary hypertension. Finally, the ambient hypoxia associated with high-altitude exposure facilitates the detection of pulmonary (and systemic) vascular dysfunction at an early stage. Here, we will summarize recent studies that, by capitalizing on these observations, have led to the description of novel mechanisms underpinning pulmonary hypertension and to the first direct demonstration of fetal programming of pulmonary vascular dysfunction in humans.
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Purpose: We evaluated the potential for hybrid PET/MRI devices to provide integrated metabolic, functional and anatomic characterisation of patients with suspected coronary artery disease.Methods and Materials: Ten patients (5 with suspected hibernating myocardium and 5 healthy volunteers) performed an imaging study using a hybrid PET/MRI (Philips). Viability assessed by 18F-FDG was performed in diseased patients along with MRI anatomic and functional study and reassessed within 30 minutes by conventional PET/CT. Non-contrast right coronary artery (RCA) targeted and whole heart 3D coronary angio-MRI using ECG-gating and respiratory navigator was performed in healthy volunteers with reconstruction performed using MPR and volume rendering. The extent of metabolic defect (MD) using PET/MRI and PET/CT was compared in patients and coronary territories (LAD, CX, RCA). Assessability of coronary lumen was judged as good, sub-optimal or non-assessable using a 16-segments coronary model.Results: Metabolic assessment was successful in all patients with MD being 19.2% vs 18.3% using PET/MRI and PET/CT, respectively (P=ns). The MD was 10.2%, 6 %, and 3 % vs 9.3%, 6 % and 3 % for LAD, CX and RCA territories, respectively (P= ns). Coronary angio-MRI was successful in all volunteers with 66 coronary segments visualised overall. The RCA was fully visualised in 4/5 volunteers and the left coronary arteries in 4/5 volunteers. Assessability in visualised segments was good, sub-optimal and non-assessable in 88 %, 2 % and 10 %, respectively.Conclusion: Hybrid PET/MRI devices may enable metabolic evaluation comparable to PET/CT with additional value owing to accurate functional and anatomical information including coronary assessment.