Apart from tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA), a third PA appears to occur in human plasma. Its activity is initiated when appropriate triggers of the contact system are added, and the activation depends on the presence of factor XII and prekallikrein in plasma. The activity of this, so-called, contact-system dependent PA accounts for 30% of the PA activity in the dextran sulphate euglobulin fraction of plasma and was shown not to be an intrinsic property of one of the contact-system components, nor could it be inhibited by inhibitory antibodies against t-PA or u-PA. We have succeeded in identifying this third PA in dextran sulphate euglobulin fractions of human plasma. Its smallest unit (SDS-PAGE) is an inactive 110 kDa single-chain polypeptide which upon activation of the contact system is converted to a cleaved, disulphide-bridged molecule with PA activity. The native form, presumably, is an oligomer, since the apparent Mr on gel-chromatography is 600,000. The IEP is 4.8, much lower than that of t-PA and u-PA. Although the active 110 kDa polypeptide cannot be inhibited by anti-u-PA, it yet comprises a 37 kDa piece with some u-PA related antigenic determinants. However, these determinants are in a latent or cryptic form, only detectable after denaturation by SDS. The 110 kDa polypeptide is evidently not a dimer of 55 kDa u-PA or a complex of u-PA with an inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)
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QUESTIONS: What are the perceived reasons for people with chronic obstructive pulmonary disease (COPD) to be physically active or sedentary? Are those reasons related to the actual measured level of physical activity?DESIGN: A mixed-methods study combining qualitative and quantitative approaches.PARTICIPANTS: People with mild to very severe COPD.OUTCOME MEASURES: Participants underwent a semi-structured interview and physical activity was measured by a triaxial accelerometer worn for one week.RESULTS: Of 118 enrolled, 115 participants (68% male, mean age 65 years, mean FEV1 57% predicted, mean modified Medical Research Council dyspnoea score 1.4) completed the study. The most frequently reported reason to be physically active was health benefits, followed by enjoyment, continuation of an active lifestyle from the past, and functional reasons. The most frequently reported reason to be sedentary was the weather, followed by health problems, and lack of intrinsic motivation. Mean steps per day ranged between 236 and 18 433 steps. A high physical activity level was related to enjoyment and self-efficacy for physical activity. A low physical activity level was related to the weather influencing health, financial constraints, health and shame.CONCLUSION: We identified important facilitators to being physically active and barriers that could be amenable to change. Furthermore, we distinguished three important potential strategies for increasing physical activity in sedentary people with COPD, namely reducing barriers and increasing insight into health benefits, tailoring type of activity, and improvement of self-efficacy.
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Stimulating physical activity behaviour in persons with a physical disability is important, especially after discharge from rehabilitation. A tailored counselling programme covering both the period of the rehabilitation treatment and the first months at home seems on the average effective. However, a considerable variation in response is observed in the sense that some patients show a relevant beneficial response while others show no or only a small response on physical activity behaviour. The Rehabilitation, Sports and Active lifestyle (ReSpAct) study aims to estimate the associations of patient and programme characteristics with patients' physical activity behaviour after their participation in a tailored counselling programme. METHODS AND ANALYSIS: A questionnaire-based nationwide longitudinal prospective cohort study is conducted. Participants are recruited from 18 rehabilitation centres and hospitals in The Netherlands. 2000 participants with a physical disability or chronic disease will be followed during and after their participation in a tailored counselling programme. Programme outcomes on physical activity behaviour and patient as well as programme characteristics that may be associated with differences in physical activity behaviour after programme completion are being assessed. Data collection takes place at baseline and 14, 33 and 52 weeks after discharge from rehabilitation. ETHICS AND DISSEMINATION: The study protocol has been approved by the Medical Ethics Committee of the University Medical Centre Groningen and at individual participating institutions. All participants give written informed consent. The study results will provide new insights into factors that may help explain the differences in physical activity behaviour of patients with a physical disability after they have participated in the same physical activity and sports stimulation programme. Thereby, it will support healthcare professionals to tailor their guidance and care to individual patients in order to stimulate physical activity after discharge in a more efficient and effective way.
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