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1.
Mov Ecol ; 10(1): 52, 2022 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-36447280

RESUMO

BACKGROUND: The movement extent of mammals is influenced by human-modified areas, which can affect population demographics. Understanding how human infrastructure influences movement at different life stages is important for wildlife management. This is true especially for large carnivores, due to their substantial space requirements and potential for conflict with humans. METHODS: We investigated human impact on movement and habitat selection by GPS-collared male brown bears (Ursus arctos) in two life stages (residents and dispersers) in central Sweden. We identified dispersers visually based on their GPS locations and used hidden Markov models to delineate dispersal events. We used integrated step selection analysis (iSSA) to infer movement and habitat selection at a local scale (availability defined by hourly relocations), and resource selection functions (RSFs) to infer habitat selection at a landscape scale (availability defined by the study area extent). RESULTS: Movement of residents on a local scale was facilitated by small forestry roads as they moved faster and selected areas closer to forestry roads, and they avoided areas closer to larger public roads and buildings on both scales. Dispersers were more ambivalent in their response to human infrastructure. Dispersers increased their speed closer to small forestry roads and larger public roads, did not exhibit selection for or against any road class, and avoided areas closer to buildings only at local scale. Dispersers did not select for any features on the landscape, which is likely explained by the novelty of the landscape or their naivety towards it. CONCLUSION: Our results show that movement in male brown bears is life stage-dependent and indicate that connectivity maps derived from movement data of dispersing animals may provide more numerous and more realistic pathways than those derived from resident animal data alone. This suggests that data from dispersing animals provide more realistic models for reconnecting populations and maintaining connectivity than if data were derived from resident animals alone.

2.
Behav Ecol ; 33(1): 137-146, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35197809

RESUMO

How and where a female selects an area to settle and breed is of central importance in dispersal and population ecology as it governs range expansion and gene flow. Social structure and organization have been shown to influence settlement decisions, but its importance in the settlement of large, solitary mammals is largely unknown. We investigate how the identity of overlapping conspecifics on the landscape, acquired during the maternal care period, influences the selection of settlement home ranges in a non-territorial, solitary mammal using location data of 56 female brown bears (Ursus arctos). We used a resource selection function to determine whether females' settlement behavior was influenced by the presence of their mother, related females, familiar females, and female population density. Hunting may remove mothers and result in socio-spatial changes before settlement. We compared overlap between settling females and their mother's concurrent or most recent home ranges to examine the settling female's response to the absence or presence of her mother on the landscape. We found that females selected settlement home ranges that overlapped their mother's home range, familiar females, that is, those they had previously overlapped with, and areas with higher density than their natal ranges. However, they did not select areas overlapping related females. We also found that when mothers were removed from the landscape, female offspring selected settlement home ranges with greater overlap of their mother's range, compared with mothers who were alive. Our results suggest that females are acquiring and using information about their social environment when making settlement decisions.

3.
Lupus ; 26(3): 311-315, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27687028

RESUMO

Objective There is a decreased breast cancer risk in systemic lupus erythematosus (SLE) versus the general population. We assessed a large sample of SLE patients, evaluating demographic and clinical characteristics and breast cancer risk. Methods We performed case-cohort analyses within a multi-center international SLE sample. We calculated the breast cancer hazard ratio (HR) in female SLE patients, relative to demographics, reproductive history, family history of breast cancer, and time-dependent measures of anti-dsDNA positivity, cumulative disease activity, and drugs, adjusted for SLE duration. Results There were 86 SLE breast cancers and 4498 female SLE cancer-free controls. Patients were followed on average for 7.6 years. Versus controls, SLE breast cancer cases tended to be white and older. Breast cancer cases were similar to controls regarding anti-dsDNA positivity, disease activity, and most drug exposures over time. In univariate and multivariate models, the principal factor associated with breast cancers was older age at cohort entry. Conclusions There was little evidence that breast cancer risk in this SLE sample was strongly driven by any of the clinical factors that we studied. Further search for factors that determine the lower risk of breast cancer in SLE may be warranted.


Assuntos
Neoplasias da Mama/epidemiologia , Lúpus Eritematoso Sistêmico/complicações , Adulto , Fatores Etários , Estudos de Coortes , Feminino , Humanos , Cooperação Internacional , Pessoa de Meia-Idade , Análise Multivariada , Modelos de Riscos Proporcionais , Fatores de Risco
4.
Rev Sci Instrum ; 86(7): 073505, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26233381

RESUMO

We describe an experimental setup for making precision measurements of relative ß-decay rates of (22)Na, (36)Cl, (54)Mn, (60)Co, (90)Sr, (133)Ba, (137)Cs, (152)Eu, and (154)Eu. The radioactive samples are mounted in two automated sample changers that sequentially position the samples with high spatial precision in front of sets of detectors. The set of detectors for one sample changer consists of four Geiger-Müller (GM) tubes and the other set of detectors consists of two NaI scintillators. The statistical uncertainty in the count rate is few times 0.01% per day for the GM detectors and about 0.01% per hour on the NaI detectors. The sample changers, detectors, and associated electronics are housed in a sealed chamber held at constant absolute pressure, humidity, and temperature to isolate the experiment from environmental variations. The apparatus is designed to accumulate statistics over many years in a regulated environment to test recent claims of small annual variations in the decay rates. We demonstrate that absent this environmental regulation, uncontrolled natural atmospheric pressure variations at our location would imprint an annual signal of 0.1% on the Geiger-Müller count rate. However, neither natural pressure variations nor plausible indoor room temperature variations cause a discernible influence on our NaI scintillator detector count rate.

5.
Oncology ; 85(2): 117-21, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23887245

RESUMO

OBJECTIVE: Evidence points to a decreased breast cancer risk in systemic lupus erythematosus (SLE). We analyzed data from a large multisite SLE cohort, linked to cancer registries. METHODS: Information on age, SLE duration, cancer date, and histology was available. We analyzed information on histological type and performed multivariate logistic regression analyses of histological types according to age, SLE duration, and calendar year. RESULTS: We studied 180 breast cancers in the SLE cohort. Of the 155 cases with histology information, 11 were referred to simply as 'carcinoma not otherwise specified'. In the remaining 144 breast cancers, the most common histological type was ductal carcinoma (n = 95; 66%) followed by lobular adenocarcinoma (n = 11; 8%), 15 cancers were of mixed histology, and the remaining ones were special types. In our regression analyses, the independent risk factors for lobular versus ductal carcinoma was age [odds ratio (OR) 1.07, 95% confidence interval (CI) 1.01-1.14] and for the 'special' subtypes it was age (OR 1.06, 95% CI 1.01-1.10) and SLE duration (OR 1.05, 95% CI 1.00-1.11). CONCLUSIONS: Generally, up to 80% of breast cancers are ductal carcinomas. Though our results are not definitive, in the breast cancers that occur in SLE, there may be a slight decrease in the ductal histological type. In our analyses, age and SLE duration were independent predictors of histological status.


Assuntos
Neoplasias da Mama/etiologia , Carcinoma Ductal de Mama/etiologia , Carcinoma Lobular/etiologia , Lúpus Eritematoso Sistêmico/complicações , Adulto , Idoso , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Carcinoma Lobular/patologia , Estudos de Coortes , Suscetibilidade a Doenças/etiologia , Suscetibilidade a Doenças/patologia , Feminino , Humanos , Modelos Logísticos , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Fatores de Risco
6.
Resuscitation ; 82(12): 1496-500, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21907688

RESUMO

OBJECTIVES: As a part of the chain of survival, the emergency medical communication centre (EMCC) and the emergency medical dispatcher (EMD) has an important role in early identification of out-of-hospital cardiac arrests (OHCA). The EMD may provide instructions to the caller and thereby initiate cardiopulmonary resuscitation in a substantial number of subjects and thus contribute to increased survival. The EMCC provides a response with first responders, ambulances, physician manned units and potentially other health care providers. EMCC in many cases initiates the communication with experts in the referral hospital and provide added value to the post resuscitation care by providing advanced transport, logistics and follow up. In research there is a growing focus on the EMCC/EMDs impact on survival in OHCA. The lack of standards in reporting results from medical dispatching is an obstacle for thorough evaluation of results in this area and comparison of data. The objective for this paper is to introduce a framework for uniform reporting of the dispatching process for quality improvement, collecting and reporting data and exchanging information regarding OHCA.


Assuntos
Reanimação Cardiopulmonar/métodos , Sistemas de Comunicação entre Serviços de Emergência/normas , Parada Cardíaca Extra-Hospitalar/diagnóstico , Melhoria de Qualidade , Reanimação Cardiopulmonar/normas , Humanos , Parada Cardíaca Extra-Hospitalar/terapia
8.
Eur Respir J ; 35(4): 776-80, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19797127

RESUMO

Interpreting spirometry as normal or abnormal using 95% confidence limits can obscure milder airflow decreases. Other analyses might better persuade cigarette smokers to quit. High-quality spirometric data of ambulatory never- and current-smokers of African-, European- and Latin-American ethnicity from the Third National Health and Nutrition Evaluation Survey (n>9000) were analysed. We desired to calculate, for each decade of life, the odds that specific ratios of forced expiratory volume in 1 s to 6 s (%FEV(1)/FEV(6)) and to forced vital capacity (%FEV(1)/FVC) values came from a current- or never-smoker. We also desired to develop new, simpler and better formulas to estimate changes in physiological lung age (Deltalung age) for males and females. For each decade of life, odds increase strikingly that smoking decreases %FEV(1)/FEV(6) and %FEV(1)/FVC. At least for these three ethnicities, Deltalung age can be easily calculated as the product of (predicted - actual) %FEV(1)/FEV(6) x 4 or (predicted - actual) %FEV(1)/FVC x 3. Through the sixth decade of life, smokers' Deltalung age increase rapidly but little thereafter, presumably due to the inabilities of older smokers to participate in the survey or their deaths. Using odds and Deltalung ages rather than traditional 95% confidence limits might better persuade smokers to quit.


Assuntos
Jogo de Azar , Razão de Chances , Fumar/epidemiologia , Fumar/fisiopatologia , Adulto , Distribuição por Idade , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Motivação , Valor Preditivo dos Testes , Distribuição por Sexo , Fumar/psicologia , Abandono do Hábito de Fumar/psicologia , Espirometria , Adulto Jovem
9.
Proc Natl Acad Sci U S A ; 103(38): 13905-10, 2006 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-16968781

RESUMO

Previous research has identified links between changes in sea surface temperature (SST) and hurricane intensity. We use climate models to study the possible causes of SST changes in Atlantic and Pacific tropical cyclogenesis regions. The observed SST increases in these regions range from 0.32 degrees C to 0.67 degrees C over the 20th century. The 22 climate models examined here suggest that century-timescale SST changes of this magnitude cannot be explained solely by unforced variability of the climate system. We employ model simulations of natural internal variability to make probabilistic estimates of the contribution of external forcing to observed SST changes. For the period 1906-2005, we find an 84% chance that external forcing explains at least 67% of observed SST increases in the two tropical cyclogenesis regions. Model "20th-century" simulations, with external forcing by combined anthropogenic and natural factors, are generally capable of replicating observed SST increases. In experiments in which forcing factors are varied individually rather than jointly, human-caused changes in greenhouse gases are the main driver of the 20th-century SST increases in both tropical cyclogenesis regions.


Assuntos
Desastres , Água do Mar , Temperatura , Clima Tropical , Oceano Atlântico , Simulação por Computador , Efeito Estufa , Humanos , Modelos Teóricos , Oceano Pacífico , Fatores de Tempo
10.
Indoor Air ; 16(4): 282-95, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16842609

RESUMO

Indoor/outdoor measurements have been performed in the Oslo metropolitan area during summer and winter periods (2002-2003) at two different residential houses. The objective of the measurement study was to characterize, physically and chemically, the particulate matter (PM) and gaseous pollutants associated with actual human exposure in the selected places, and their indoor/outdoor relationship. In this paper, we focus on the PM measurements and examine the relationship between the indoor and outdoor PM concentrations taking into account the ventilation rate, indoor sources and meteorological conditions. The indoor/outdoor measurements indicate the important contribution of the outdoor air to the indoor air quality and the influence of specific indoor sources such as smoking and cooking to the concentration of PM inside houses. However, no specific correlation was found between the indoor/outdoor concentration ratio and the meteorological parameters. This study provides information on the physical characteristics and the relationship of indoor to outdoor concentration of particulate matter in residential houses. Moreover, the parameters that influence this relationship are discussed. The results presented here are specific to the sampled houses and conditions used and provide data on the actual human exposure characteristics which occur in the spatial and temporal scales of the present study.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Poeira/análise , Habitação , Aerossóis/análise , Cidades , Monitoramento Ambiental , Calefação , Óxidos de Nitrogênio/análise , Noruega , Ozônio/análise , Tamanho da Partícula , Estações do Ano , Emissões de Veículos , Ventilação
11.
Eur Respir J ; 27(6): 1244-50, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16455822

RESUMO

It has been suggested that forced expiratory volume in six seconds (FEV(6)) should be substituted for forced vital capacity (FVC) to measure fractions of timed expired volume for airflow obstruction detection. The present authors hypothesised that this recommendation might be questionable because flow after 6 s of forced expiration from more diseased lung units with the longest time constants was most meaningful and should not be ignored. Furthermore, previous studies comparing FEV(6) and FVC included few subjects with mild or no disease. The present study used spirometric data from the USA Third National Health and Nutrition Evaluation Survey with prior published ethnicity- and sex-specific equations for FEV(1)/FEV(6), FEV(1)/FVC and FEV(3)/FVC, and new equations for FEV(3)/FEV(6), all derived from approximately 4,000 adult never-smokers aged 20-80 yrs. At 95% confidence intervals, 21.3% of 3,515 smokers and 41.3% of smokers aged >51 yrs had airway obstruction; when comparing FEV(1)/FEV(6) with FEV(1)/FVC, 13.5% were concurrently abnormal, 1.5% were false positives and 4.1% were false negatives; and when comparing FEV(3)/FEV(6) with FEV(3)/FVC, 11.6% were concurrently abnormal, 3.3% were false positives and 5.7% were false negatives. Substituting forced expiratory volume in six seconds for forced vital capacity to determine the fractional rates of exhaled volumes reduces the sensitivity of spirometry to detect airflow obstruction, especially in older individuals and those with lesser obstruction.


Assuntos
Volume Expiratório Forçado/fisiologia , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Capacidade Vital/fisiologia , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Programas de Rastreamento , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Fatores Sexuais , Fumar/efeitos adversos , Fumar/fisiopatologia , Espirometria
12.
Science ; 309(5740): 1551-6, 2005 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-16099951

RESUMO

The month-to-month variability of tropical temperatures is larger in the troposphere than at Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations and is consistent with basic theory. On multidecadal time scales, tropospheric amplification of surface warming is a robust feature of model simulations, but it occurs in only one observational data set. Other observations show weak, or even negative, amplification. These results suggest either that different physical mechanisms control amplification processes on monthly and decadal time scales, and models fail to capture such behavior; or (more plausibly) that residual errors in several observational data sets used here affect their representation of long-term trends.

13.
APMIS ; 110(2): 123-31, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12064867

RESUMO

Several functions have been assigned to the extensive glycosylation of HIV-1 envelope glycoprotein gp120, especially immune escape mechanisms, but the intramolecular interactions between gp120 and its carbohydrate complement are not well understood. To analyse this phenomenon we established a new microwell deglycosylation assay for determining N-linked glycan accessibility after binding of gp120-specific agents. Orientation-specific exposition of gp120 in ELISA microplates was achieved by catching with either anti-C5 antibody D7324 or anti-V3 antibody NEA-9205. We found that soluble CD4 inhibited the deglycosylation of gp120 only when gp120 was caught by D7324 and not by NEA9205. In contrast, antibodies from HIV-infected individuals inhibited the deglycosylation best when gp120 was caught by NEA9205. These results demonstrated that both the CD4-binding site and the epitopes recognised by antibodies from HIV-infected individuals have N-glycans in the close vicinity. However, the difference in gp120 orientation indicates that antibodies in HIV-infected individuals, at least partly, bind to epitopes different from the CD4-binding site. Finally, we determined the structural class of the glycan of one V1 glycosylation site of prototype HIV-1 LAI gp120, which remained unsolved from previous studies, and found that it belonged to the complex type of glycans.


Assuntos
Amidoidrolases , Ensaio de Imunoadsorção Enzimática/métodos , Anticorpos Anti-HIV/análise , Proteína gp120 do Envelope de HIV/imunologia , HIV-1/imunologia , Sítios de Ligação , Antígenos CD4/imunologia , Humanos , Testes de Neutralização , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase , Polissacarídeos
14.
J Med Ethics ; 28(2): 86-8, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11934935

RESUMO

Restrictions on research on therapeutic cloning are questionable as they inhibit the development of a technique which holds promise for successful application of pluripotent stem cells in clinical treatment of severe diseases. It is argued in this article that the ethical concerns are less problematic using therapeutic cloning compared with using fertilised eggs as the source for stem cells. The moral status of an enucleated egg cell transplanted with a somatic cell nucleus is found to be more clearly not equivalent to that of a human being. Based on ethical considerations alone, research into therapeutic cloning should be encouraged in order to develop therapeutic applications of stem cells.


Assuntos
Bioética , Clonagem de Organismos , Pesquisas com Embriões , Embrião de Mamíferos , Ética Médica , Fertilização in vitro , Princípios Morais , Células-Tronco , Clonagem de Organismos/legislação & jurisprudência , Clonagem de Organismos/psicologia , Embrião de Mamíferos/citologia , Humanos , Filosofia Médica , Pesquisa/normas , Transplante de Células-Tronco
16.
Proc Natl Acad Sci U S A ; 98(26): 14778-83, 2001 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-11752424

RESUMO

The growth rate of climate forcing by measured greenhouse gases peaked near 1980 at almost 5 W/m(2) per century. This growth rate has since declined to approximately 3 W/m(2) per century, largely because of cooperative international actions. We argue that trends can be reduced to the level needed for the moderate "alternative" climate scenario ( approximately 2 W/m(2) per century for the next 50 years) by means of concerted actions that have other benefits, but the forcing reductions are not automatic "co-benefits" of actions that slow CO(2) emissions. Current trends of climate forcings by aerosols remain very uncertain. Nevertheless, practical constraints on changes in emission levels suggest that global warming at a rate +0.15 +/- 0.05 degrees C per decade will occur over the next several decades.

17.
Circulation ; 104(4): 429-35, 2001 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-11468205

RESUMO

BACKGROUND: Patients with primary pulmonary hypertension (PPH) have a pulmonary vasculopathy that leads to exercise intolerance due to dyspnea and fatigue. To better understand the basis of the exercise limitation in patients with PPH, cardiopulmonary exercise testing (CPET) with gas exchange measurements, New York Heart Association (NYHA) symptom class, and resting pulmonary hemodynamics were studied. METHODS AND RESULTS: We retrospectively evaluated 53 PPH patients who had right heart catheterization and cycle ergometer CPET studies to maximum tolerance as part of their clinical workups. No adverse events occurred during CPET. Reductions in peak O(2) uptake (VO(2)), anaerobic threshold, peak O(2) pulse, rate of increase in VO(2), and ventilatory efficiency were consistently found. NYHA class correlated well with the above parameters of aerobic function and ventilatory efficiency but less well with resting pulmonary hemodynamics. CONCLUSIONS: Patients with PPH can safely undergo noninvasive cycle ergometer CPET to their maximal tolerance. The CPET abnormalities were consistent and characteristic and correlated well with NYHA class.


Assuntos
Tolerância ao Exercício/fisiologia , Hipertensão Pulmonar/fisiopatologia , Adulto , Pressão Sanguínea/fisiologia , Teste de Esforço/métodos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Troca Gasosa Pulmonar/fisiologia , Testes de Função Respiratória
18.
Tidsskr Nor Laegeforen ; 121(8): 904-7, 2001 Mar 20.
Artigo em Norueguês | MEDLINE | ID: mdl-11332375

RESUMO

BACKGROUND: There are few Norwegian recommendations for quality and efficacy of ambulance performance. A report commissioned by the Ministry of Health and Social Affairs concluded that the ambulance service was the weakest link in the chain of survival. The report proposed standards for response intervals in emergencies: 90% of the population in cities and urban areas should be reached by an ambulance within eight minutes. In rural areas, 90% should be reached within 25 minutes. MATERIAL AND METHODS: This study describes the ambulance response interval for the 2,589 red code emergencies in the 15 municipalities in Vestfold County in 1998, a county with a population of 208,687, or 97.5 inhabitants per square kilometre, with seven ambulance stations. A retrospective analysis was made of data for the year 1998. RESULTS: The proposed standard was not reached in any municipality in the county. The city of Tønsberg had the best performance, but even here only 48.9% of the population were reached by ambulance within eight minutes. The worst performance was found in the rural municipality of Tjøme; here, only 63.3% were reached within 25 minutes. INTERPRETATION: Achieving the standards proposed will require a major restructuring of existing ambulance services.


Assuntos
Ambulâncias , Serviços Médicos de Emergência , Ambulâncias/normas , Ambulâncias/estatística & dados numéricos , Bases de Dados Factuais , Serviços Médicos de Emergência/normas , Serviços Médicos de Emergência/estatística & dados numéricos , Humanos , Noruega , Estudos Retrospectivos , Serviços de Saúde Rural/normas , Serviços de Saúde Rural/estatística & dados numéricos , Serviços de Saúde Suburbana/normas , Serviços de Saúde Suburbana/estatística & dados numéricos , Estudos de Tempo e Movimento , Serviços Urbanos de Saúde/estatística & dados numéricos
19.
J Appl Physiol (1985) ; 90(5): 1798-810, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11299270

RESUMO

To calculate cardiac output by the indirect Fick principle, CO(2) concentrations (CCO(2)) of mixed venous (Cv(CO(2))) and arterial blood are commonly estimated from PCO(2), based on the assumption that the CO(2) pressure-concentration relationship (PCO(2)-CCO(2)) is influenced more by changes in Hb concentration and blood oxyhemoglobin saturation than by changes in pH. The purpose of the study was to measure and assess the relative importance of these variables, both in arterial and mixed venous blood, during rest and increasing levels of exercise to maximum (Max) in five healthy men. Although the mean mixed venous PCO(2) rose from 47 Torr at rest to 59 Torr at the lactic acidosis threshold (LAT) and further to 78 Torr at Max, the Cv(CO(2)) rose from 22.8 mM at rest to 25.5 mM at LAT but then fell to 23.9 mM at Max. Meanwhile, the mixed venous pH fell from 7.36 at rest to 7.30 at LAT and to 7.13 at Max. Thus, as work rate increases above the LAT, changes in pH, reflecting changes in buffer base, account for the major changes in the PCO(2)-CCO(2) relationship, causing Cv(CO(2)) to decrease, despite increasing mixed venous PCO(2). Furthermore, whereas the increase in the arteriovenous CCO(2) difference of 2.2 mM below LAT is mainly due to the increase in Cv(CO(2)), the further increase in the arteriovenous CCO(2) difference of 4.6 mM above LAT is due to a striking fall in arterial CCO(2) from 21.4 to 15.2 mM. We conclude that changes in buffer base and pH dominate the PCO(2)-CCO(2) relationship during exercise, with changes in Hb and blood oxyhemoglobin saturation exerting much less influence.


Assuntos
Dióxido de Carbono/sangue , Exercício Físico/fisiologia , Esforço Físico/fisiologia , Adulto , Bicarbonatos/sangue , Testes Respiratórios , Dióxido de Carbono/análise , Débito Cardíaco , Teste de Esforço , Veia Femoral , Frequência Cardíaca , Humanos , Concentração de Íons de Hidrogênio , Cinética , Masculino , Modelos Biológicos , Oxigênio/análise , Oxigênio/sangue , Pressão Parcial , Artéria Pulmonar
20.
Chest ; 119(3): 824-32, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11243964

RESUMO

STUDY OBJECTIVES: The ventilatory equivalent for CO(2) (ie, the ratio of minute ventilation [VE] to carbon dioxide output [VCO(2)]) is increased in patients with primary pulmonary hypertension (PPH) consequent to an increase in physiologic dead space and alveolar ventilation. We wished to see whether the VE/V(2) ratio correlated with the abnormality in pulmonary hemodynamics in PPH patients and whether it changed in response to prostacyclin infusion. METHODS: Following right-sided heart catheterization, 10 patients with severe PPH were studied in the coronary-care unit while hemodynamic and gas exchange measurements were measured simultaneously before and after infusion with epoprostenol (Epo), a prostacyclin analog. Studies were performed at baseline and during IV infusion of two to three increasing dosages of Epo in 10 PPH patients (NYHA class III-IV). Four patients had radial artery catheters for simultaneous blood gas measurements. Nine healthy subjects who were matched by sex, height, and weight underwent gas exchange analyses only. RESULTS: The mean (+/- SD) VE/VCO(2) ratio was higher in PPH patients than in control subjects (50.7 +/- 9.7 vs 30.6 +/- 3.8; p < 0.001). Thirteen measurements made in four patients showed that the VE/VCO(2) ratio correlated with the physiologic dead space/tidal volume ratio (r = 0.78; p = 0.002). The VE/VCO(2) ratio measurement at baseline correlated significantly with total pulmonary vascular resistance (TPVR) (r = 0.70; p = 0.02) but not with mean pulmonary artery pressure (mPAP) or cardiac index. During Epo infusion, the VE/VCO(2) ratio decreased with increasing dosage in 6 of 10 patients, with no change or slight increases in the 4 remaining patients. Considering all doses, the VE/VCO(2) ratio decreased significantly in response to the short-term administration of Epo. The decrease tended to parallel the pattern of decrease in TPVR, but the changes in both variables were too small to provide a statistically significant correlation. The mPAP did not change significantly in response to Epo infusion, although TPVR did change at the highest dosage. CONCLUSIONS: In patients with severe PPH, the VE/VCO(2) ratio correlated significantly with TPVR but not with mPAP or cardiac index. The VE/VCO(2) ratio decreased systematically from baseline with the dose of Epo in some but not all patients. The VE/VCO(2) ratio and TPVR decreased significantly in response to Epo when all doses were considered. Further studies are needed to elucidate whether noninvasive gas exchange measurements may be clinically useful in the evaluation of the severity of pulmonary vascular disease and the effectiveness of pulmonary vasodilator therapy.


Assuntos
Epoprostenol , Hipertensão Pulmonar/fisiopatologia , Inibidores da Agregação Plaquetária , Circulação Pulmonar/fisiologia , Cateterismo Cardíaco , Estudos de Casos e Controles , Feminino , Humanos , Hipertensão Pulmonar/diagnóstico , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Artéria Pulmonar/fisiopatologia , Troca Gasosa Pulmonar/fisiologia , Ventilação Pulmonar/fisiologia , Resistência Vascular/fisiologia
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