We determined the efficiency with which maximal exercise ventilatory output could be mimicked voluntarily. Five normal subjects exercised to maximal volitional effort and flow:volume and pressure:volume loops, and end-expiratory lung volume (EELV) and breathing pattern were measured. All subjects increased expiratory flow rate and reduced EELV sufficiently so that the forced vital capacity loop was approximated during at least some portion of expiration, but the generation of pleural pressure remained effective, i.e., equal to or only slightly in excess of that required to produce maximal expiratory flow (Pmax). Subsequently, while at rest, subjects used visual feedback and were able to closely mimic the flow:volume, EELV, and breath-timing achieved in maximal exercise; however: (1) expiratory pressures were excessive and usually exceeded average Pmax; (2) abdominal expiratory muscle activity was increased, as indicated by positive shifts in expiratory gastric pressure; and (3) total ventilatory work was increased 15 to 40% greater than that achieved in maximal exercise. Maximal voluntary efforts (MVV) caused EELV to increase and ventilatory work was increased 20 to 300% greater than during maximal exercise. We conclude that accurate determination of maximal effective ventilatory output available for maximal exercise or precise quantitation of the metabolic cost of producing maximal exercise ventilation requires replication of the pressure:volume, breath-timing, and EELV characteristics achieved in maximal exercise. 相似文献
These clinical practice guidelines aim at providing assistance mainly to primary health care physicians for the diagnosis and management of acute sinusitis. Despite the huge impact of upper respiratory infections, criteria for diagnoses are often vague, and physicians are often uncertain of their diagnoses. This is not surprising, as the sole definition of acute sinusitis is somewhat confusing, not to mention the existing discrepancies between treatments, even among specialists. The Finnish Society of Otorhinolaryngology has set up a committee to evaluate existing data on acute sinusitis and to formulate these guidelines. The committee comprised Finnish experts in adult and paediatric otorhinolaryngology, clinical microbiology, radiology, paediatrics, and epidemiology. Recommendations given are based on the principles of evidence-based medicine, with the level of evidence presented. 相似文献
OBJECTIVE: Accumulation of intimal smooth muscle cells (SMC) is an important event in vein graft-stenosis. Different SMC sources have been reported, but their interrelations have been poorly studied. In a mouse vein graft model we investigated whether recipient-derived intimal SMCs are recruited from the surrounding tissue and whether blockage of SMC recruitment from the surrounding tissue and/or the donor vein will reduce neointimal formation. METHODS: To detect recipient-derived cells, wild-type veins were implanted into ROSA26 transgenic mice. To block cell recruitment from the surrounding tissue, implanted veins were isolated with a tube-shaped plastic film. To exclude vein-derived cells in the neointimal formation, acellular veins were implanted. RESULTS: In vein grafts isolated from the surrounding tissue the recipient contribution became minimal, but the total number of SMCs was not decreased. Acellular grafts contained an equal number of intimal SMCs as cellular controls after 4 weeks. Isolation of acellular grafts from the surrounding tissue decreased the number of intimal SMCs by 90%. CONCLUSIONS: Recipient-derived SMCs are mainly recruited from the surrounding tissue. Cell recruitment from either the vein or the surrounding tissue is enough to form a neointima. Therefore, a simultaneous inhibition of both these sources is needed to reduce accumulation of intimal SMCs. 相似文献
In vitro expanded neural stemprogenitor cells can undergo region-specific differentiation after transplantation to the developing or adult brain, and display morphologies and markers characteristic of mature neurons. Here we have used patch-clamp techniques to explore whether grafted stem cells also can develop physiological properties of mature neurons and become functionally integrated within host neural circuitry. The immortalized neural progenitor cell line, RN33B, prelabeled with GFP by using a lentiviral vector, was transplanted into the cortex or hippocampus of neonatal rats. We found that the grafted GFP-positive cells differentiated into cells with morphological features of cortical or hippocampal pyramidal neurons, and that many of them had established appropriate cortico-thalamic and contralateral hippocampal connections, respectively, as revealed by retrograde tracing. Whole-cell patch-clamp recordings from grafted cells with morphological characteristics of pyramidal neurons showed that they were able to generate action potentials, and received functional excitatory and inhibitory synaptic inputs from neighboring cells. These data provide evidence that grafted neural progenitors can differentiate into morphologically mature pyramidal projection neurons, establish appropriate long-distance axonal projections, exhibit normal electrophysiological properties, and become functionally integrated into host cortical circuitry. 相似文献
In cells that exhibit apical growth, mechanisms that regulate cell polarity are crucial for determination of cellular shape and for the adaptation of growth to intrinsic and extrinsic cues. Broadly conserved pathways control cell polarity in eukaryotes, but less is known about polarly growing prokaryotes. An evolutionarily ancient form of apical growth is found in the filamentous bacteria Streptomyces, and is directed by a polarisome-like complex involving the essential protein DivIVA. We report here that this bacterial polarization machinery is regulated by a eukaryotic-type Ser/Thr protein kinase, AfsK, which localizes to hyphal tips and phosphorylates DivIVA. During normal growth, AfsK regulates hyphal branching by modulating branch-site selection and some aspect of the underlying polarisome-splitting mechanism that controls branching of Streptomyces hyphae. Further, AfsK is activated by signals generated by the arrest of cell wall synthesis and directly communicates this to the polarisome by hyperphosphorylating DivIVA. Induction of high levels of DivIVA phosphorylation by using a constitutively active mutant AfsK causes disassembly of apical polarisomes, followed by establishment of multiple hyphal branches elsewhere in the cell, revealing a profound impact of this kinase on growth polarity. The function of AfsK is reminiscent of the phoshorylation of polarity proteins and polarisome components by Ser/Thr protein kinases in eukaryotes. 相似文献
AIM: To estimate the incidence of collagenous colitis (CC) in southern Sweden during 2001-2010.METHODS: Cases were identified by searching for CC in the diagnostic registers at the Pathology Departments in the county of Skåne. The catchment area comprised the south-west part of the county (394 307 inhabitants in 2010) and is a mixed urban and rural type with limited migration. CC patients that had undergone colonoscopy during the defined period and were living in this area were included in the study regardless of where in Skåne they had been diagnosed. Medical records were scrutinized and uncertain cases were reassessed to ensure that only newly diagnosed CC cases were included. The diagnosis of CC was based on both clinical and histopathological criteria. The clinical criterion was non-bloody watery diarrhoea. The histopathological criteria were a chronic inflammatory infiltrate in the lamina propria, a thickened subepithelial collagen layer ≥ 10 micrometers (μm) and epithelial damage such as flattening and detachment.RESULTS: During the ten year period from 2001-2010, 198 CC patients in the south-west part of the county of Skåne in southern Sweden were newly diagnosed. Of these, 146 were women and 52 were men, i.e., a female: male ratio of 2.8:1. The median age at diagnosis was 71 years (range 28-95/inter-quartile range 59-81); for women median age was 71 (range 28-95) years and was 73 (range 48-92) years for men. The mean annual incidence was 5.4/105 inhabitants. During the time periods 2001-2005 and 2006-2010, the mean annual incidence rates were 5.4/105 for both periods [95% confidence interval (CI): 4.3-6.5 in 2001-2005 and 4.4-6.4 in 2006-2010, respectively, and 4.7-6.2 for the whole period]. Although the incidence varied over the years (minimum 3.7 to maximum 6.7/105) no increase or decrease in the incidence could be identified. The odds ratio (OR) for CC in women compared to men was estimated to be 2.8 (95% CI: 2.0-3.7). The OR for women 65 years of age or above compared to below 65 years of age was 6.9 (95% CI: 5.0-9.7), and for women 65 years of age or above compared to the whole group the OR was 4.7 (95% CI: 3.6-6.0). The OR for age in general, i.e., above or 65 years of age compared to those younger than 65 was 8.3 (95% CI: 6.2-11.1). During the last decade incidence figures for CC have also been reported from Calgary, Canada during 2002-2004 (4.6/105) and from Terrassa, Spain during 2004-2008 (2.6/105). Our incidence figures from southern Sweden during 2001-2010 (5.4/105) as well as the incidence figures presented in the studies during the 1990s (Terrassa, Spain during 1993-1997 (2.3/105), Olmsted, United States during 1985-2001 (3.1/105), Örebro, Sweden during 1993-1998 (4.9/105), and Iceland during 1995-1999 (5.2/105) are all in line with a north-south gradient, something that has been suggested before both for CC and inflammatory bowel disease.CONCLUSION: The observed incidence of CC is comparable with previous reports from northern Europe and America. The incidence is stable but the female: male ratio seems to be decreasing. 相似文献
We investigated the effects of ionizing radiation on microvessel structure and complexity in the hippocampus. We also assessed neurogenesis and the neurovascular niche. Postnatal day 14 male C57BL/6 mice received a single dose of 8 Gy to the whole brain and were killed 6 hours, 1 week, 7 weeks, or 1 year later. Irradiation decreased the total number of microvessels and branching points from 1 week onwards and decreased the total microvessel area 1 and 7 weeks after irradiation. After an initial increase in vascular parameter densities, concomitant with reduced growth of the hippocampus, the densities normalized with time, presumably adapting to the needs of the surrounding nonvascular tissue. Irradiation decreased the number of neural stem and progenitor cells in the hippocampus. The relative loss increased with time, resulting in almost completely ablated neurogenesis (DCX+ cells) 1 year after irradiation (77% decreased 1 week, 86% decreased 7 weeks, and 98% decreased 1 year after irradiation compared with controls). After irradiation, the distance between undifferentiated stem cells and microvessels was unaffected, and very few dying endothelial cells were detected. Taken together, these results indicate that the vasculature adjusts to the surrounding neural and glial tissue after irradiation, not vice-versa. 相似文献
Background: Although stroke prevalence is increasing and large proportions of stroke survivors are expected to live many years after stroke onset, research on the long-term consequences of stroke for instrumental activities of daily living (IADL) is limited.
Aim: To explore performance of IADL seven years post-stroke onset and identify predictors of long-term IADL performance based on commonly employed acute measures and demographic characteristics in young and middle-aged stroke survivors.
Methods: Data on stroke survivors were collected from SAHLSIS. IADL performance was assessed at 7 years using the Frenchay Activities Index (FAI). Demographic data and baseline measures were assessed as predictors of FAI outcome, using logistic regression.
Results: 237 stroke survivors with a median age of 63 at follow-up were included. Participants had predominantly suffered a mild stroke and >90% lived at home with no community services. Mean FAI was 25.7(score range 0-45), indicating reduced levels of participation in IADL. Frequency of performance of IADL was lowest for work/leisure activities. Gender, cohabitation status, initial stroke severity and baseline score on mRS were independently associated with IADL outcome.
Conclusions: Reduced levels of participation in IADL persist many years after stroke onset and indicate a need to adapt a long-term perspective on stroke rehabilitation. 相似文献