85 resultados para Basal respiration
em Université de Lausanne, Switzerland
Resumo:
Adaptation of 24-h energy expenditure (24-h EE) to seasonal variations in food availability was studied, by using a respiration chamber, in 18 rural Gambian men on three occasions: period 1--at the end of the rainy season, which is characterized by low food availability; period 2--during the nutritionally favorable dry season; and period 3--at the onset of the following rainy season. From periods 1 to 2 body weight increased by 2.8 +/- 0.4 kg, and a rise in 24-h EE was observed (from 8556 +/- 212 kJ/d to 9166 +/- 224 kJ/d), which was correlated to weight change (r = 0.73, P less than 0.001). During period 3, 24-h EE averaged 8740 +/- 194 kJ/d. Diet-induced thermogenesis increased significantly from periods 1 to 2 (5.9 +/- 0.5% to 8.2 +/- 0.8%) and subsequently decreased to 3.6 +/- 0.6% during period 3. In rural Gambian men, metabolic adaptations in response to seasonal changes in food availability are reflected by a decrease in body weight, mainly manifested by a loss of fat-free mass accompanied by a decreased 24-h EE and a lowered diet-induced thermogenesis.
Resumo:
There is a need to measure energy expenditure in man for a period of 24 h or even several days. The respiration chamber offers a unique opportunity to reach this goal. It allows the study of energy and nutrient balance; from the latter, acute changes in body composition can be obtained. The respiration chamber built in Lausanne is an air-tight room (5 m long, 2.5 m wide, and 2.5 m high) which forms an open circuit ventilated indirect calorimeter. The physical activity of the subject inside the chamber is continuously measured using a radar system based on the Doppler effect. Energy expenditure of obese and lean women was continuously measured over 24 h and diet-induced thermogenesis was assessed by using an approach which allows one to subtract the energy expended for physical activity from the total energy expenditure. Expressed in absolute terms, total energy expenditure was more elevated in the obese than in the lean controls. Basal metabolic rate was also higher in the obese than in the controls, but diet-induced thermogenesis was found to be blunted in the obese. In a second study, the effect of changing the carbohydrate/lipid content of the diet on fuel utilization was assessed in young healthy subjects with the respiration chamber. After a 7-day adaptation to a high-carbohydrate low-fat diet, the fuel mixture oxidized matched the change in nutrient intake. A last example of the use of the respiration chamber is the thermogenic response and changes in body composition due to a 7-day overfeeding of carbohydrate. Diet-induced thermogenesis was found to be 27%; on the last day of overfeeding, carbohydrate balance was reached by oxidation of 50% of the carbohydrate intake, the remaining 50% being converted into lipid.
Resumo:
By use of a respiration chamber, 24-hour energy expenditure (EE), diet-induced thermogenesis (DIT), and basal and sleeping EE were measured in 20 young rural Gambian men during the "hungry" season (weight, 60.8 +/- 1.4 kg) and in a group of 16 European men matched for body composition (weight, 66.9 +/- 1.9 kg). The 24-h EE was lower in Gambian than in European men (2047 +/- 46 vs 2635 +/- 74 kcal/d, p less than 0.001, respectively). Basal EE and sleeping EE were also lower in Gambian than in European men (1.05 +/- 0.02 vs 1.25 +/- 0.02 kcal/min and 1.0 +/- 0.02 vs 1.18 +/- 0.02 kcal/min, p less than 0.01, respectively). DIT was blunted in Gambian compared with European men (6.3 +/- 0.6% vs 12.1 +/- 0.5%, p less than 0.001 respectively). The net efficiency of walking was greater in Gambian than in European men (23.2 +/- 0.3% vs 20.1 +/- 0.4%, p less than 0.001, respectively). A low basal and sleeping EE, a reduced DIT, and a high work efficiency are important energy-sparing mechanisms in Gambian men, which allow them to cope with a marginal level of dietary intake during the hungry season.
Resumo:
1. The relation between dietary carbohydrate: lipid ratio and the fuel mixture oxidized during 24 h was investigated in eleven healthy volunteers (six females, and five males) in a respiration chamber. Values of the fuel mixture oxidized were estimated by continuous indirect calorimetry and urinary nitrogen measurements. 2. The subjects, were first given a mixed diet for 7 d and spent the last 24 h of the 7 d period in a respiration chamber for continuous gas-exchange measurement. The fuels oxidized during 2.5 h or moderate exercise were also measured in the respiration chamber. After an interval of 2 weeks from the end of the mixed-diet period, the same subjects were given an isoenergetic high-carbohydrate low-fat diet for 7 d, and the same experimental regimen was repeated. 3. Dietary composition markedly influenced the fuel mixture oxidized during 24 h and this effect was still present 12 h after the last meal in the postabsorptive state. However, the diets had no influence on the substrates oxidized above resting levels during exercise. With both diets, the 24 h energy balance was slightly negative and the energy deficit was covered by lipid oxidation. 4. With the high-carbohydrate low-fat diet, the energy expenditure during sleep was found to be higher than that with the mixed diet. 5. It is concluded that: (a) the composition of the diet did not influence the fuel mixture utilized for moderate exercise, (b) the energy deficit calculated for a 24 h period was compensated by lipid oxidation irrespective of the carbohydrate content of the diet, (c) energy expenditure during sleep was found to be higher with the high-carbohydrate low-fat diet than with the mixed diet.
Resumo:
The metabolic and respiratory effects of intravenous 0.5 M sodium acetate (at a rate of 2.5 mmol/min during 120 min) were studied in nine normal human subjects. O2 consumption (VO2) and CO2 production (VCO2) were measured continuously by open-circuit indirect calorimetry. VO2 increased from 251 +/- 9 to 281 +/- 9 ml/min (P < 0.001), energy expenditure increased from 4.95 +/- 0.17 kJ/min baseline to 5.58 +/- 0.16 kJ/min (P < 0.001), and VCO2 decreased nonsignificantly (211 +/- 7 ml/min vs. 202 +/- 7 ml/min, NS). The extrapulmonary CO2 loss (i.e., bicarbonate generation and excretion) was estimated at 48 +/- 5 ml/min. This observation is consistent with 1 mol of bicarbonate generated from 1 mol of acetate metabolized. Alveolar ventilation decreased from 3.5 +/- 0.2 l/min basal to 3.1 +/- 0.2 l/min (P < 0.001). The minute ventilation (VE) to VO2 ratio decreased from 22.9 +/- 1.3 to 17.6 +/- 0.9 l/l (P < 0.005), arterial PO2 decreased from 93.2 +/- 1.9 to 78.7 +/- 1.6 mmHg (P < 0.0001), arterial PCO2 increased from 39.2 +/- 0.7 to 42.1 +/- 1.1 mmHg (P < 0.0001), pH from 7.40 +/- 0.005 to 7.50 +/- 0.007 (P < 0.005), and arterial bicarbonate concentration from 24.2 +/- 0.7 to 32.9 +/- 1.1 (P < 0.0001). These observations indicate that sodium acetate infusion results in substantial extrapulmonary CO2 loss, which leads to a relative decrease of total and alveolar ventilation.
Resumo:
Migmatization of gabbroic rocks at 2-3 kbar has occurred in the metamorphic contact aureole of a mafic pluton in the Fuerteventura Basal Complex (Canary Island;). Migmatites are characterized by a dense network: of closely spaced millimetre-wide leucocratic veins with perfectly preserved igneous textures. They are all relatively enriched in Al, Na I: Sr Ba, Nb, Y and the rare earth elements compared with the unaffected country rock beyond the aureole. Migmatization under such low-pressure conditions war possible because of the unusual tectonic and magmatic contact in which ii occurred. Multiple basic intrusions associated with extrusive volcanic activity created high heat flow in a small area. Alkaline and metasomatized rocks present in the country rock of the intruding pluton were leached by high-temperature fluids during contact metamorphism. These enriched fluids then favoured partial melting of the host gabbroic rocks, and contaminated both the leucosomes and melanosomes. A transpressive tectonic setting at the time of intrusion created shearing along the contact between the intrusion and its host rock. This shearing enhanced circulation of the fluids and allowed segregation of the nea-formed melts from their restite by opening tension veins into which the melts migrated. Depending on the relative timing of melt segregation and recrystallization leucosomes range in composition from a 40-60% mixture of clinopyroxene (+/- amphibole) and plagioclase to almost pure feldspathic veins. Comparable occurrences of gabbros migmatized at low pressure are expected only at a snail scale in localized areas of high heat flow in the presence of fluids, such as in. mid-ocean ridges or ocean-islands.
Resumo:
Short-term overfeeding with carbohydrate induced a marked stimulation of energy expenditure, amounting to 33 per cent of the excess energy intake on the 7th day of overfeeding. This value is larger than that previously reported in man. Stimulation of lipogenesis and increased activity of the sympathetic nervous system seem to be the two major mechanisms which account for the stimulation of energy expenditure during carbohydrate overfeeding.
Resumo:
Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical-basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause deregulation of the Hippo tumor suppressor pathway and hyperactivation of its downstream effectors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). However, whether AJs and Scrib act through the same or independent mechanisms to regulate Hippo pathway activity is not known. Here, we dissect how disruption of AJs or loss of basolateral components affect the activity of the Drosophila YAP homolog Yorkie (Yki) during imaginal disc development. Surprisingly, disruption of AJs and loss of basolateral proteins produced very different effects on Yki activity. Yki activity was cell-autonomously decreased but non-cell-autonomously elevated in tissues where the AJ components E-cadherin (E-cad) or α-catenin (α-cat) were knocked down. In contrast, scrib knockdown caused a predominantly cell-autonomous activation of Yki. Moreover, disruption of AJs or basolateral proteins had different effects on cell polarity and tissue size. Simultaneous knockdown of α-cat and scrib induced both cell-autonomous and non-cell-autonomous Yki activity. In mammalian cells, knockdown of E-cad or α-cat caused nuclear accumulation and activation of YAP without overt effects on Scrib localization and vice versa. Therefore, our results indicate the existence of multiple, genetically separable inputs from AJs and cell polarity complexes into Yki/YAP regulation.
Resumo:
We studied the effect of smoking on energy expenditure in eight healthy cigarette smokers who spent 24 hours in a metabolic chamber on two occasions, once without smoking and once while smoking 24 cigarettes per day. Diet and physical exercise (30 minutes of treadmill walking) were standardized on both occasions. Physical activity in the chamber was measured by use of a radar system. Smoking caused an increase in total 24-hour energy expenditure (from a mean value [+/- SEM] of 2230 +/- 115 to 2445 +/- 120 kcal per 24 hours; P less than 0.001), although no changes were observed in physical activity or mean basal metabolic rate (1545 +/- 80 vs. 1570 +/- 70 kcal per 24 hours). During the smoking period, the mean diurnal urinary excretion of norepinephrine (+/- SEM) increased from 1.25 +/- 0.14 to 1.82 +/- 0.28 micrograms per hour (P less than 0.025), and mean nocturnal excretion increased from 0.73 +/- 0.07 to 0.91 +/- 0.08 micrograms per hour (P less than 0.001). These short-term observations demonstrate that cigarette smoking increases 24-hour energy expenditure by approximately 10 percent, and that this effect may be mediated in part by the sympathetic nervous system. The findings also indicate that energy expenditure can be expected to decrease when people stop smoking, thereby favoring the gain in body weight that often accompanies the cessation of smoking.
Resumo:
There are numerous variants of cutaneous tumors involving the eyelids. Tumors of a different nature may at times be observed simultaneously in the same area of the eyelid. A clinicopathologic case of a 36-year-old male patient with 2 different cutaneous tumors at the nasal part of the left eyelid is reported. One was a nodular tumor on the inner canthus with a pearly appearance; the other had a papillomatous pattern. After surgical removal, the histopathological study of the tumors disclosed a typical basal cell carcinoma and a squamous cell papilloma. Both tumors can be commonly observed on the eyelids and surgical excision cured the patient.
Resumo:
Previous studies have demonstrated the difference between the basal metabolic rate (BMR) and the sleeping metabolic rate (SMR): however, the difference in the Japanese population has not yet been explored. This study examined the relationship between the BMR and SMR in ninety-four healthy Japanese subjects (37 males and 57 females, 39 +/- 12 y of age and 22.0 +/- 7.4% body fat) in a respiratory chamber. The SMR was significantly lower than the BMR (1416 +/- 245 vs. 1492 +/- 256 kcal/d): however, there was a highly significant correlation between the two (r = 0.867; p < 0.001). The ratio of SMR/BMR largely varied among individuals (0.95 +/-0.08, 8.4% of the coefficient of variation). The ratio was significantly lower in males than in females (0.93 +/- 0.10 vs. 0.97 +/- 0.06, p < 0.05). None of the anthropometric measures (age, weight, body mass index, body surface area or percent body fat) correlated with the ratio. These results showed that SMR was 95%, of BMR on average in a healthy Japanese group. However, when applied over a longer time period (24 h or more), the difference tends to become negligible for most analyses in a group. Although the difference between SMR and BMR will induce a 5% gap of physical activity level defined as the total energy expenditure divided by the BMR or SMR, this factor seems to have little practical importance in epidemiological research.
Resumo:
The treatment of morphoeic (or sclerosing) basal cell carcinoma (mBCC) of the face is associated with high rates of incomplete excision and recurrence. A principal risk factor for incomplete resection is the grade of surgeon. We did a prospective, randomised study of 40 consecutive patients with mBCC of the face. The extent of the tumour was assessed under standard conditions by consultant surgeons and compared with assessments by resident surgeons with the help of the Varioscope, a combination of microscope and loupe glasses with strong illumination and a maximal magnification of 7x. The data from a former retrospective study of all excisions of mBCC of the face during a five-year period at the hospital served as control. Residents with the support of the Varioscope achieved a rate of incomplete excisions similar to that of consultants under standard conditions. There was a significant reduction of the rate of incomplete resections by resident surgeons thanks to high magnification and good lighting (p=0.02). High magnification and good lighting were useful in learning how to recognise skin changes associated with mBCC of the face and achieving a low rate of incomplete excisions.
Resumo:
The basal sliding surfaces in large rockslides are often composed of several surfaces and possess a complex geometry. The exact morphology and location in three dimensions of the sliding surface remains generally unknown, in spite of extensive field and subsurface investigations, such as those at the Åknes rockslide (western Norway). This knowledge is crucial for volume estimations, failure mechanisms, and numerical slope stability modeling. This paper focuses on the geomorphologic characterization of the basal sliding surface of a postglacial rockslide scar in the vicinity of Åknes. This scar displays a stepped basal sliding surface formed by dip slopes of the gneiss foliation linked together by steeply dipping fractures. A detailed characterization of the rockslide scar by means of high-resolution digital elevation models permits statistical parameters of dip angle, spacing, persistence, and roughness of foliation surfaces and step fractures to be obtained. The characteristics are used for stochastic simulations of stepped basal sliding surfaces at the Åknes rockslide. These findings are compared with previous models based on geophysical investigations. This study discusses the investigation of rockslide scars and rock outcrops for a better understanding of potential rockslides. This work identifies possible basal sliding surface locations, which is a valuable input for volume estimates, design and location of monitoring instrumentation, and numerical slope stability modeling.
Resumo:
Basal cell carcinoma of the skin is the most common human cancer. It is also the most frequent malignant tumor of the eyelid. In Europe, its most common clinical presentation is a hard indurated, and sometimes ulcerated nodule. The authors report a giant palpebral basal cell carcinoma in a black non albinos Cameroonian patient. The ethnic origin, localization and macroscopic aspect are discussed. The problems connected with diagnosis and treatment of malignant tumors in Africa are noted.