Historically, the role of the carotid bodies in ventilatory control has been understated, but the current view suggests that the carotid bodies （1） provide a tonic, facilitory input to the respiratory network, （2）...Historically, the role of the carotid bodies in ventilatory control has been understated, but the current view suggests that the carotid bodies （1） provide a tonic, facilitory input to the respiratory network, （2） serve as the major site of peripheral 02 chemoreception and minor contributor to CO2/H＋ chemoreception, and （3） are required for ventilatory adaptation to high altitude. Each of these roles has been demonstrated in studies of ventilation in mammals after carotid body denervation. Following carotid body denervation, many of the compromised ventilatory ＂functions＂ show a time-dependent recovery plasticity that varies in the degree of recovery and time required for recovery. Respiratory plasticity following carotid body denervation is also dependent on species, with contributions from peripheral and central sites/mechanisms driving the respiratory plasticity. The purpose of this review is to provide a summary of the data pointing to peripheral and central mechanisms of plasticity following carotid body denervation. We speculate that after carotid body denervation there are altered excitatory and/or inhibitory neuromodulator mechanisms that contribute to the initial respiratory depression and the subsequent respiratory plasticity, and further suggest that the continued exploration of central effects of carotid body denervation might provide useful information regarding the capacity of the respiratory network for plasticity following neurologic injury in humans.展开更多
Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency （f） by comparison to terrestrial mammals of the same body size, the difference increasing the larger the s...Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency （f） by comparison to terrestrial mammals of the same body size, the difference increasing the larger the species. Among various interpretations, it was suggested that the low-f breathing is a consequence of the end-inspiratory breath-holding pattern adopted by aquatic mammals to favour buoyancy at the water surface, and evolved to be part of the genetic makeup. If this interpretation was correct it could be expected that, differently from f, the heart rate （HR, beats/min） of aquatic and semi-aquatic mammals at rest would not need to differ from that of terrestrial mammals and that their HR-fratio would be higher than in terrestrial species. Literature data for HR （beats/min） in mammals at rest were gathered for 56 terrestrial and 27 aquatic species. In aquatic mammals the allometric curve （HR=191 .M^18; M= body mass, kg） did not differ from that of terrestrial species （HR=212.M^-0.22） and their HR-fratio （on average 32±5） was much higher than in terrestrial species （5±1） （P〈0.0001）. The comparison of these HR allometric curves to those forfpreviously published indicated that the HR-fratio was body size-independent in terrestrial species while it increased significantly with M in aquatic species. The similarity in HR and differences in f between aquatic and terrestrial mammals agree with the possibility that the lowfof aquatic and semi-aquatic mammals may have evolved for a non-respiratory function, namely the regulation of buoyancy at the water surface [Current Zoology 61（4）： 569-577, 2015].展开更多
The aims were to prospectively evaluate the association of glycemic control (HbAlc) with gastric emptying in newly diagnosed Type 1 diabetic patients and subjects with longterm diabetes mellitus. Furthermore, the day ...The aims were to prospectively evaluate the association of glycemic control (HbAlc) with gastric emptying in newly diagnosed Type 1 diabetic patients and subjects with longterm diabetes mellitus. Furthermore, the day to day variability of gastric emptying for solids should be assessed. Methods 13 C octanoic breath tests were performed in 15 type 1 diabetic subjects on two separate days within one week. The influence of metabolic control on gastric emptying was prospectively examined over a mean of 8 months in 14 patients with newly diagnosed type 1 diabetes and 44 long term diabetic patients (type 1: n=31; type 2: n=13).Patients with longterm diabetes were stratified according to their HbA 1c at follow up (group 1: HbA 1c U7.5%, n=17; group 2 HbA 1c >7.5%, n=27). 13 C octanoic breath tests were sampled with an isotope selective non dispersive infrared spectrometer. The gastric emptying parameters were calculated using nonlinear regression analysis of the time course of 13 CO 2 exhalation:half emptying time (t 1/2 ) and lag phase (t lag ). Results The intraindividuell coefficient of variation was 17.8% for t 1/2 , and 28.2% for t lag . Mean t 1/2 and t lag in newly diagnosed type 1 diabetics were normal at baseline and were significantly increased at follow up. In patients with longterm diabetes, gastric emptying was unchanged during follow up. Gastric emptying was significant delayed in group 2 compared with group 1 at baseline and follow up respectively. There was a significant correlation between HbA 1c and t 1/2 , t lag at follow up. Conclusions 13 C octanoic breath test has a relatively good reproducibility in patients with type 1 diabetes. Gastric emptying times are already significantly increased after few months in newly diagnosed type 1 diabetes. There is a more pronounced delay of gastric emptying in longterm diabetic subjects with poor compared to patients with good metabolic control.展开更多
文摘Historically, the role of the carotid bodies in ventilatory control has been understated, but the current view suggests that the carotid bodies （1） provide a tonic, facilitory input to the respiratory network, （2） serve as the major site of peripheral 02 chemoreception and minor contributor to CO2/H＋ chemoreception, and （3） are required for ventilatory adaptation to high altitude. Each of these roles has been demonstrated in studies of ventilation in mammals after carotid body denervation. Following carotid body denervation, many of the compromised ventilatory ＂functions＂ show a time-dependent recovery plasticity that varies in the degree of recovery and time required for recovery. Respiratory plasticity following carotid body denervation is also dependent on species, with contributions from peripheral and central sites/mechanisms driving the respiratory plasticity. The purpose of this review is to provide a summary of the data pointing to peripheral and central mechanisms of plasticity following carotid body denervation. We speculate that after carotid body denervation there are altered excitatory and/or inhibitory neuromodulator mechanisms that contribute to the initial respiratory depression and the subsequent respiratory plasticity, and further suggest that the continued exploration of central effects of carotid body denervation might provide useful information regarding the capacity of the respiratory network for plasticity following neurologic injury in humans.
文摘Aquatic and semi-aquatic mammals, while resting at the water surface or ashore, breathe with a low frequency （f） by comparison to terrestrial mammals of the same body size, the difference increasing the larger the species. Among various interpretations, it was suggested that the low-f breathing is a consequence of the end-inspiratory breath-holding pattern adopted by aquatic mammals to favour buoyancy at the water surface, and evolved to be part of the genetic makeup. If this interpretation was correct it could be expected that, differently from f, the heart rate （HR, beats/min） of aquatic and semi-aquatic mammals at rest would not need to differ from that of terrestrial mammals and that their HR-fratio would be higher than in terrestrial species. Literature data for HR （beats/min） in mammals at rest were gathered for 56 terrestrial and 27 aquatic species. In aquatic mammals the allometric curve （HR=191 .M^18; M= body mass, kg） did not differ from that of terrestrial species （HR=212.M^-0.22） and their HR-fratio （on average 32±5） was much higher than in terrestrial species （5±1） （P〈0.0001）. The comparison of these HR allometric curves to those forfpreviously published indicated that the HR-fratio was body size-independent in terrestrial species while it increased significantly with M in aquatic species. The similarity in HR and differences in f between aquatic and terrestrial mammals agree with the possibility that the lowfof aquatic and semi-aquatic mammals may have evolved for a non-respiratory function, namely the regulation of buoyancy at the water surface [Current Zoology 61（4）： 569-577, 2015].
文摘The aims were to prospectively evaluate the association of glycemic control (HbAlc) with gastric emptying in newly diagnosed Type 1 diabetic patients and subjects with longterm diabetes mellitus. Furthermore, the day to day variability of gastric emptying for solids should be assessed. Methods 13 C octanoic breath tests were performed in 15 type 1 diabetic subjects on two separate days within one week. The influence of metabolic control on gastric emptying was prospectively examined over a mean of 8 months in 14 patients with newly diagnosed type 1 diabetes and 44 long term diabetic patients (type 1: n=31; type 2: n=13).Patients with longterm diabetes were stratified according to their HbA 1c at follow up (group 1: HbA 1c U7.5%, n=17; group 2 HbA 1c >7.5%, n=27). 13 C octanoic breath tests were sampled with an isotope selective non dispersive infrared spectrometer. The gastric emptying parameters were calculated using nonlinear regression analysis of the time course of 13 CO 2 exhalation:half emptying time (t 1/2 ) and lag phase (t lag ). Results The intraindividuell coefficient of variation was 17.8% for t 1/2 , and 28.2% for t lag . Mean t 1/2 and t lag in newly diagnosed type 1 diabetics were normal at baseline and were significantly increased at follow up. In patients with longterm diabetes, gastric emptying was unchanged during follow up. Gastric emptying was significant delayed in group 2 compared with group 1 at baseline and follow up respectively. There was a significant correlation between HbA 1c and t 1/2 , t lag at follow up. Conclusions 13 C octanoic breath test has a relatively good reproducibility in patients with type 1 diabetes. Gastric emptying times are already significantly increased after few months in newly diagnosed type 1 diabetes. There is a more pronounced delay of gastric emptying in longterm diabetic subjects with poor compared to patients with good metabolic control.
