Estratégias e modos reprodutivos de anuros (Amphibia) em uma poça permanente na Serra de Paranapiacaba, Sudeste do Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ventilação mandatória intermitente sincronizada versus ventilação com suporte pressórico e volume garantido em coelhos induzidos à hemorragia aguda

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Trocas gasosas e ciclo fotossintético da figueira 'Roxo de Valinhos'

No presente trabalho, determinaram-se as trocas gasosas de folhas de figueira 'Roxo de valinhos' e o ciclo fotossintético por meio da relação isotópica 12C/13C. Essas medidas foram realizadas sempre na região mediana das folhas, completamente expandidas e totalmente expostas à radiação solar, no período das 09h00min às 10h30min. As folhas fotossinteticamente ativas da figueira apresentaram área foliar em torno de 160cm², com uma assimilação de 14,38µmol m-2 s-1 de CO2, cujos valores isotópicos médios no ramo 1 e no 2 são -28,98±0,69 e -29,28±0,85 , respectivamente. Com base nos valores da fotossíntese máxima e na discriminação isotópica do 13C, evidenciou-se que a figueira pode ser considerada uma planta do ciclo fotossintético C3.

Variação sazonal da fotossíntese, condutância estomática e potencial da água na folha de laranjeira 'Valência'

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fotossíntese, condutância estomática e transpiração em pupunheira sob deficiência hídrica

Resultados de pesquisa envolvendo aspectos fisiológicos da pupunheira (Bactris gasipaes Kunth), fruteira nativa da América Tropical, são escassos. Procurando completar essa lacuna, um experimento sob deficiência hídrica foi conduzido em casa de vegetação, durante um período de 13 dias, utilizando plantas de 12 meses de idade. O objetivo principal foi avaliar as respostas da pupunheira à deficiência hídrica. As variáveis observadas foram: taxa de assimilação de CO2, transpiração, condutância estomática e potencial de água das folhas. As coletas dos dados foram realizadas diariamente em laboratório e sob fluxo de 1200 mim-2 s-1. Os resultados foram submetidos à análise de variância e de regressão. Verificou-se decréscimo no potencial de água da folha e nas trocas gasosas quando a irrigação foi interrompida por mais de seis dias. Valores mínimos foram obtidos no décimo dia, com redução de 92% da fotossíntese líquida, 87% da condutância estomática e 70% da transpiração. O menor potencial de água nas folhas (-1,9 MPa) foi também observado nesse período. Houve recuperação total de todas as variáveis dois dias após reirrigação, com exceção da condutância estomática. A diminuição da condutância estomática e a queda mais rápida da taxa de transpiração que a queda na fotossíntese, indicam a existência de mecanismos de aclimatação em pupunheira, no sentido de diminuir as perdas de água, quando sob condição de estresse hídrico moderado.

Central control of cardiorespiratory interactions in fish

Fish control the relative flow rates of water and blood over the gills in order to optimise respiratory gas exchange. As both flows are markedly pulsatile, close beat-to-beat relationships can be predicted. Cardiorespiratory interactions in fish are controlled primarily by activity in the parasympathetic nervous system that has its origin in cardiac vagal. preganglionic neurons. Recordings of efferent activity in the cardiac vagus include units firing in respiration-related bursts. Bursts of electrical stimuli delivered peripherally to the cardiac vagus or centrally to respiratory branches of cranial, nerves can recruit the heart over a range of frequencies. So, phasic, efferent activity in cardiac vagi, that in the intact fish are respiration-related, can cause heart rate to be modulated by the respiratory rhythm. In elasmobranch fishes this phasic activity seems to arise primarily from central feed-forward interactions with respiratory motor neurones that have overlapping distributions with cardiac neurons in the brainstem. In teleost fish, they arise from increased levels of efferent vagal activity arising from reflex stimulation of chemoreceptors and mechanoreceptors in the orobranchial, cavity. However, these differences are largely a matter of emphasis as both groups show elements of feed-forward and feed-back control of cardiorespiratory interactions. (C) 2008 Elsevier GmbH. All rights reserved.

Is chronic hypoxemia in patients with chronic obstructive pulmonary disease associated with more marked nutritional deficiency?: A study of the fat-free mass evaluated by anthropometry and bioelectrical impedance methods

In order to determine wheter blood gases abnormalities, specially hypoxemia, are associated with more marked changes in fat-free mass in patients with chronic obstructive pulmonary disease (CPOD), nutritional assessment was performed on 16 normoxemic (PaO 2 > 55 mm Hg) and 16 hypoxemic (PaO 2 < 55 mm Hg) COPD patients in stable clinical condition. Body weight was expressed as percentage of the ideal body weight. Fat-free mass was estimated by anthropometry (FFM-Anthr) and by bioelectrical impedance (FFM- BI). Handgrip-strength was assessed as a measure of peripheral skeletal muscle strength. Patients were age-matched and presented similar degree of airway obstruction. Malnutrition, defined as body weight less than 90% of the ideal, was observed in 19% of the normoxemic patients and in 25% of the hypoxemic patients (p>0,05). FFM values in hypoxemic patients, estimated by both methods, were not different from those observed in normoxemic patients. No significant difference was observed on handgrip values between the two groups. No correlation was found between nutritional indices and pulmonary function and gases exchange parameters. FFM correlated positively with values of peripheral muscle function in normoxemic and hypoxemic patients. These data add further evidence to the hypothesis that hypoxemia is not a primary cause of the nutritional deficiency observed in COPD patients.

Effects of soil water deficit and nitrogen nutrition on water relations and photosynthesis of pot-grown Coffea canephora Pierre

Coffea canephora plants (clone INCAPER-99) were submitted to low N (LN) or high N (HN) applications and two watering regimes (daily irrigation and irrigation every 5 days for a month). Although water potential was not altered significantly by N, HN plants showed higher relative water content than did LN plants under water deficit. Only HN plants exhibited some ability for osmotic adjustment. Plants from both N treatments increased their cell wall rigidity under drought, with a more pronounced augmentation in HN plants. In well-watered plants, carbon assimilation rate increased with increasing N while stomatal conductance did not respond to N supply. Under drought conditions, carbon assimilation decreased by 68-80% compared to well-watered plants, whereas stomatal conductance and transpiration rate declined by 35% irrespective of the N applications. Stable carbon isotope analysis, combined with leaf gas exchange measurements, indicated that regardless of the watering treatments, N increased the long-term water use efficiency through changes in carbon assimilation with little or no effect on stomatal behaviour.

Drought tolerance of two field-grown clones of Coffea canephora

We compared tolerance to soil drought of two field-grown clones of Coffea canephora (clone 46, drought-sensitive; and clone 120, drought-tolerant). Under irrigation, there were no marked differences between the clones in water relation parameters, gas exchange and total leaf area. Under rainfed conditions, clone 46 showed osmotic adjustment and increased tissue rigidity. These adjustments, however, were incapable of preventing substantial decreases in xylem pressure potential. By contrast, clone 120 did not exhibit osmotic adjustment, but was able to increase tissue elasticity and to maintain xylem pressure potentials to a greater extent than clone 46 (despite having twice the total leaf area of this clone). Stomatal conductance was lowered by drought in clone 120 but not in clone 46. Carbon assimilation per unit leaf area in both clones remained unaffected under stress. Long-term water use efficiency (WUE), as estimated through carbon isotope discrimination, was consistently greater in clone 120 than in clone 46. Because of these traits, clone 120 was better able to postpone dehydration and to maintain whole-tree photosynthesis. It is proposed that these features should decisively contribute to buffer its productivity in drought-prone areas. © 2002 Elsevier Science Ireland Ltd. All rights reserved.

Uso do óxido nítrico em pediatria

Objective: To review the literature on inhaled nitric oxide and to describe its main clinical applications in pediatrics. Sources of data: A 10 year literature review with selection of the most important publications on inhaled nitric oxide, using the Medline and Cochrane Systematic Review databases. Summary of the findings: This review was organized as follows: introduction; metabolism and biological effects; clinical applications; dosage, gas administration and weaning; precautions and side-effects. Inhaled nitric oxide use was described in persistent pulmonary hypertension and hypoxia of the newborn, acute respiratory distress syndrome, primary pulmonary hypertension, heart surgery, chronic obstructive pulmonary disease, sickle cell anemia, and bronchospastic disease. Conclusions: Inhaled nitric oxide is a therapeutic approach with wide clinical applications in pediatrics. Its use is safe when administered in pediatric intensive care units under strict monitoring. As a pulmonary vasodilator, nitric oxide has beneficial effects on gas exchange and ventilation. Controlled trials, focusing on early gas administration should be performed under many clinical conditions, especially acute respiratory distress syndrome.

Oxygen uptake kinetics and time to exhaustion in cycling and running: A comparison between trained and untrained subjects

The objective of the present study was to compare pulmonary gas exchange kinetics (VO 2 kinetics) and time to exhaustion (Tlim) between trained and untrained individuals during severe exercise performed on a cycle ergometer and treadmill. Eleven untrained males in running (UR) and cycling (UC), nine endurance cyclists (EC), and seven endurance runners (ER) were submitted to the following tests on separate days: (i) incremental test for determination of maximal oxygen uptake (VO 2max) and the intensity associated with the achievement of VO 2max (IVO 2max) on a mechanical braked cycle ergometer (EC and UC) and on a treadmill (ER and UR); (ii) all-out exercise bout performed at IVO 2max to determine the time to exhaustion at IVO 2max (Tlim) and the time constant of oxygen uptake kinetics (τ). The τ was significantly faster in trained group, both in cycling (EC = 28.2 ± 4.7 s; UC = 63.8 ± 25.0 s) and in running (ER = 28.5 ± 8.5 s; UR = 59.3 ± 12.0 s). Tlim of untrained was significantly lower in cycling (EC = 384.4 ± 66.6 s vs. UC; 311.1 ± 105.7 s) and higher in running (ER = 309.2 ± 176.6 s vs. UR = 439.8 ± 104.2 s). We conclude that the VO 2 kinetic response at the onset of severe exercise, carried out at the same relative intensity is sensitive to endurance training, irrespective of the exercise type. The endurance training seems to differently influence Tlim during exercise at IVO 2max in running and cycling. © 2003 Taylor & Francis Ltd.

Different doses of exogenous surfactant for treatment of meconium aspiration syndrome in newborn rabbits.

OBJECTIVE: To evaluate the effects of 2 different doses of exogenous surfactant on pulmonary mechanics and on the regularity of pulmonary parenchyma inflation in newborn rabbits. METHOD: Newborn rabbits were submitted to tracheostomy and randomized into 4 study groups: the Control group did not receive any material inside the trachea; the MEC group was instilled with meconium, without surfactant treatment; the S100 and S200 groups were instilled with meconium and were treated with 100 and 200 mg/kg of exogenous surfactant (produced by Instituto Butantan) respectively. Animals from the 4 groups were mechanically ventilated during a 25-minute period. Dynamic compliance, ventilatory pressure, tidal volume, and maximum lung volume (P-V curve) were evaluated. Histological analysis was conducted using the mean linear intercept (Lm), and the lung tissue distortion index (SDI) was derived from the standard deviation of the means of the Lm. One-way analysis of variance was used with a = 0.05. RESULTS: After 25 minutes of ventilation, dynamic compliance (mL/cm H2O.kg) was 0.87 +/- 0.07 (Control); 0.49 +/- 0.04 (MEC*); 0.67 +/- 0.06 (S100); and 0.67 +/- 0.08 (S200), and ventilatory pressure (cm H2O) was 9.0 +/- 0.9 (Control); 16.5 +/- 1.7 (MEC*); 12.4 +/- 1.1 (S100); and 12.1 +/- 1.5 (S200). Both treated groups had lower Lm values and more homogeneity in the lung parenchyma compared to the MEC group: SDI = 7.5 +/- 1.9 (Control); 11.3 +/- 2.5 (MEC*), 5.8 +/- 1.9 (S100); and 6.7 +/- 1.7 (S200) (*P < 0.05 versus all the other groups). CONCLUSIONS: Animals treated with surfactant showed significant improvement in pulmonary mechanics and more regularity of the lung parenchyma in comparison to untreated animals. There was no difference in results after treatment with either of the doses used.

Acute and sustained effects of early administration of inhaled nitric oxide to children with acute respiratory distress syndrome

OBJECTIVE: To determine the acute and sustained effects of early inhaled nitric oxide on some oxygenation indexes and ventilator settings and to compare inhaled nitric oxide administration and conventional therapy on mortality rate, length of stay in intensive care, and duration of mechanical ventilation in children with acute respiratory distress syndrome. DESIGN: Observational study. SETTING: Pediatric intensive care unit at a university-affiliated hospital. PATIENTS: Children with acute respiratory distress syndrome, aged between 1 month and 12 yrs. INTERVENTIONS: Two groups were studied: an inhaled nitric oxide group (iNOG, n = 18) composed of patients prospectively enrolled from November 2000 to November 2002, and a conventional therapy group (CTG, n = 21) consisting of historical control patients admitted from August 1998 to August 2000. MEASUREMENTS AND MAIN RESULTS: Therapy with inhaled nitric oxide was introduced as early as 1.5 hrs after acute respiratory distress syndrome diagnosis with acute improvements in Pao(2)/Fio(2) ratio (83.7%) and oxygenation index (46.7%). Study groups were of similar ages, gender, primary diagnoses, pediatric risk of mortality score, and mean airway pressure. Pao(2)/Fio(2) ratio was lower (CTG, 116.9 +/- 34.5; iNOG, 62.5 +/- 12.8, p <.0001) and oxygenation index higher (CTG, 15.2 [range, 7.2-32.2]; iNOG, 24.3 [range, 16.3-70.4], p <.0001) in the iNOG. Prolonged treatment was associated with improved oxygenation, so that Fio(2) and peak inspiratory pressure could be quickly and significantly reduced. Mortality rate for inhaled nitric oxide-patients was lower (CTG, ten of 21, 47.6%; iNOG, three of 18, 16.6%, p <.001). There was no difference in intensive care stay (CTG, 10 days [range, 2-49]; iNOG, 12 [range, 6-26], p >.05) or duration of mechanical ventilation (TCG, 9 days [range, 2-47]; iNOG, 10 [range, 4-25], p >.05). CONCLUSIONS: Early treatment with inhaled nitric oxide causes acute and sustained improvement in oxygenation, with earlier reduction of ventilator settings, which might contribute to reduce the mortality rate in children with acute respiratory distress syndrome. Length of stay in intensive care and duration of mechanical ventilation are not changed. Prospective trials of inhaled nitric oxide early in the setting of acute lung injury in children are needed.

Aplicação da espirometria durante teste padrão de exercício progressivo em esteira para avaliação da troca gasosa respiratória de equinos da raça árabe

The current study evaluated equine gas exchange responses through spirometry, by measuring oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory exchange ratio (R) and maximum oxygen uptake (VO2max) of Arabian horses during a standard incremental exercise test performed on a high-speed treadmill. Six clinically healthy Arabian horses were submitted to a standard incremental exercise test, performed on a high-speed treadmill at a 6% slope, and initial speed of 1,8 m.s-1 for 5 minutes, then 4,0 m.s-1 for 3 minutes, 6,0 m.s-1 for 2 minutes and 8,0 m.s-1, 9,0 m.s-1, 10,0 m.s-1 and 11,0 m.s-1 for one minute for each of these speed. The end of the exercise test was defined as the point in which the horse was no longer able to keep pace with the treadmill. Gas exchange was measured through respiratory analyses horse mask on the last 10 seconds at the end of each speed transition and at 1, 2 and 3 minutes after the end of the exercise, defined as experiment moments. During exercise, it was noticed an increase on both VO2 and VCO2 with linear relationship between exercise and speed. Arabian horses VO2max was 114,9 mL.kg-1.min-1. The respiratory exchange ratio increased over 1,0 by the speed of 9,0 m.s-1, indicating the preponderance of the anaerobic metabolism, and remains at a high level on the post-exercise period.

Características fotossintéticas de genótipos de capim-elefante anão (Pennisetum purpureum Schum.), em estresse hídrico

The experiment was carried out aiming to evaluate the gas exchange of dwarf elephant grass genotypes under different hydric conditions, in a randomized design with three replications. Genotypes of dwarf elephant grass (Mott, CNPGL 94-34-3 and CNPGL 92-198-7) were analyzed under two hydric conditions: irrigated (I) and non-irrigated (NI). Differences between treatments I and NI were observed for all genotypes for photosynthesis, stomatal conductance, transpiration and water vapor pressure deficit. Genotype CNPGL 94-34-3 presented highest tolerance to hydric stress, followed by Mott and CNPGL 92-198-7 genotypes. All genotypes presented high photosynthetic rate, under ideal conditions of soil humidity, thus characterizing the analyzed dwarf elephant grass genotypes as plants with high photosynthetic efficiency.