Influence of the oxygen uptake slow component on the aerobic energy cost of high-intensity submaximal treadmill running in humans

During high-intensity running, the oxygen uptake (V˙O₂) kinetics is characterised by a slow component which delays the attainment of the steady-state beyond the 3rd min of exercise. To assess if the aerobic energy cost of running measured at the 3rd min (C ₃) adequately reflects the variability of the true aerobic energy cost measured during the steady-state (C _ss), 13 highly-trained runners completed sessions of square-wave running at intensities above 80% maximal oxygen uptake (V˙O_2max) on a level treadmill. To evaluate the time at which the steady-state V˙O₂ was attained (t _ss), the V˙O₂ responses were described using a general double-exponential equation and t _ss was defined as the time at which V˙O₂ was less than 1% below the asymptotic value given by the model. All the subjects achieved a steady state for intensities equal to or greater than 92% V˙O_2max, and 8 out of 13 achieved it at 99% V˙O_2max. In all cases, t _ss was less than 13 min. For intensities greater than 85% V˙O_2max, C _ss was significantly higher than C ₃ and was positively related to %V˙O_2max (r= 0.44; P < 0.001) while C ₃ remained constant. The C ₃ only explained moderately the variability of C _ss (0.39 < r ² < 0.72, depending on the velocity or the (relative intensity at which the relationship was calculated). Moreover, the excess aerobic energy cost of running the (difference between C _ss and C ₃) was well predicted by age (0.90 < r ² < 0.93). Therefore, when the aerobic profile of runners is evaluated, it is recommended that their running efficiencies at velocities which reflect their race intensities should be determined, with V˙O₂ data being measured at the true steady-state. Accepted: 1 June 1998     

Substrate use during and following moderate- and low-intensity exercise: Implications for weight control

Substrate utilization during and after low- and moderate-intensity exercise of similar caloric expenditure was compared. Ten active males [age: 26.9 (4.8) years; height: 181.1 (4.8) cm; Mass: 75.7 (8.8) kg; maximum O₂ consumption (V˙O_{2 max} ): 51.2 (4.8) ml · kg⁻¹ · min⁻¹] cycled at 33% and 66% V˙O_{2 max} on separate days for 90 and 45 min, respectively. After exercise, subjects rested in a recumbent position for 6 h. Two h post-exercise, subjects ate a standard meal of 66% carbohydrate (CHO), 11% protein, and 23% fat. Near-continuous indirect calorimetry and measurement of urinary nitrogen excretion were used to determine substrate utilization. Total caloric expenditure was similar for the two trials; however, significantly (P<0.05) more fat [42.4 (3.6) g versus 24.0 (12.2) g] and less CHO [142.5 (28.5) g versus 188.8 (45.2) g] was utilized as a substrate during the low-intensity compared to the moderate-intensity trial. Protein utilization was similar for the two trials. The difference in substrate use can be attributed to the exercise period because over twice as much fat was utilized during low-intensity [30.0 (11.0) g] compared to moderate-intensity exercise [13.6 (6.6) g]. Significantly more (P<0.05) CHO was utilized during the moderate-intensity [106.0 (27.8) g] compared to the low-intensity exercise [68.7 (20.0) g]. Substrate use during the recovery period was not significantly different. We conclude that low-intensity, long-duration exercise results in a greater total fat oxidation than does moderate intensity exercise of similar caloric expenditure. Dietary-induced thermogenesis was not different for the two trials. Accepted: 3 November 1997     

The effects of progressive hypoxia on the crustacean cardiovascular system: a comparison of the freshwater crayfish, (Procambarus clarkii ), and the lobster (Homarus americanus)

The heart rate of crayfish (Procambarus clarkii) and lobsters (Homarus americanus) decreased (bradycardia) as partial pressure of O₂ (P O ₂) decreased, yet cardiac output (V _b) was maintained via an increased stroke volume (S _v) to P O ₂s of 40 mmHg and 75 mmHg for crayfish and lobsters, respectively. V _b was redistributed in both animals. Flow through the anterior aorta increased while flow dropped through the posterior aorta and sternal artery to a P O ₂ of 30 mmHg; below this flow was no longer maintained in crayfish. In the lobster, flow increased to the lateral arteries and the ventral thoracic artery while flow through the anterior and posterior aortas, sternal artery and ventral abdominal artery decreased to a P O ₂ of 75 mmHg. Anterior hemolymph flow was maintained or increased in both animals presumably to supply nervous tissue and cephalic sense organs better. Crayfish showed an increase in intracardiac and mean arterial hemolymph pressures as P O ₂ declined. The increased pressures combined with the net increase in cardiac filling pressure and diastolic filling time could have accounted for the increased S _V. The cardiovascular response exhibited by both the crayfish and lobster was P O ₂ dependent; below a critical water P O ₂ active compensation was no longer observed. Accepted: 26 November 1997     

Infection with respiratory syncytial virus enhances expression of native receptors for non-pilate Neisseria meningitidis on HEp-2 cells

Respiratory virus infections have been suggested to be predisposing factors for meningococcal disease. Respiratory syncytial virus (RSV) affects young children in the age range at greatest risk of disease caused by Neisseria meningitidis. It has been previously shown that glycoprotein G expressed on the surface of RSV-infected HEp-2 cells (a human epithelial cell line) contributed to higher levels of binding of meningococci compared with uninfected cells. The aim of the present study was to examine the effect of RSV infection on expression of surface molecules native to HEp-2 cells and their role in bacterial binding. Flow cytometry and fluorescence microscopy were used to assess bacterial binding and expression of host cell antigens. Some molecules analysed in this study have not been reported previously on epithelial cells. RSV infection significantly enhanced the expression of CD15 (P < 0.05), CD14 (P < 0.001) and CD18 (P < 0.01), and the latter two contributed to increased binding of meningococci to cells but not the Gram-positive Streptococcus pneumoniae.     

四爪陆龟消化、呼吸系统的解剖

四爪陆龟（Ｔｅｓｔｕｄｏｈｏｒｓｆｉｅｌｄｉ）的消化管总长度为体长的４．５—４．８倍。喙缘锋利，硬腭侧缘具细齿，舌不伸出口，食道扩展性强，胃呈囊状，被肝叶覆盖，小肠较长，盲肠发达。肝较大，重１８．３ｇ，分左叶、中叶和右叶，绿色胆囊位于右肝两小叶间。胰腺长条形，分布于十二指肠内。肺长囊形，紧贴在背甲的内表面，位于肩带和腰带之间。气管较短由１５－２０个软骨环组成，支气管较长由７０个左右的软骨环组成。     

Long-term measurement of heart rate in chicken eggs

Taking advantage of acoustocardiogram (ACG), we measured the heart rate (HR) of chick embryos continuously from day 12 until hatching and then investigated the development of HR irregularities (HRI), HR variability (HRV), and the existence of a circadian rhythm in mean HR (MHR). HRI comprised transient bradycardia and tachycardia, which first developed on day 14 and 16 in most embryos, respectively. Transient bradycardia increased in frequency and magnitude with embryonic development and occurred over periods of up to 30 min in some embryos. MHR was maximal on around days 14-15 and thereafter decreased to about 250-260 bpm on days 16-18. Baseline HRV, which is an oscillation of the MHR baseline, occurred as HR decreased from days 15-16 and became predominant on days 17-18. The magnitude of the baseline oscillations reached up to 50 bpm in some embryos and the period ranged between about 40-90 min (ultradian rhythm). A circadian rhythm of MHR was not found in late chick embryos. On days 18-19, embryonic activities were augmented and then breathing movements began to occur, disturbing ACG signals and thus making it difficult to measure the HR. Instead, the development of breathing activities was recorded. Breathing frequency was irregular at first and then increased to a maximum of about 1.5 Hz prior to hatching.     

经鼻高流量湿化氧疗对肺癌放射性肺炎合并呼吸衰竭患者的临床疗效观察

摘要 目的：探究经鼻高流量湿化氧疗对肺癌放射性肺炎合并呼吸衰竭患者的临床疗效,以期为临床治疗提供参考。方法：选取2020年9月至2022年8月在我院呼吸内科住院的因肺癌放射治疗出现放射性肺炎合并呼吸衰竭患者86例为研究对象,根据氧疗方法的不同分为HFNC组和COT组,每组各43例, COT组患者在此基础上给予鼻导管供氧治疗。HFNC组患者给予HFNC氧疗方式。比较两组患者治疗前后血气分析指标、呼吸频率及舒适度、疲劳程度评分的差异及对比两组的预后情况。结果：治疗后12 h、24 h、48 h两组PaO₂//FiO₂/指标均较治疗前明显升高（P<0.05）,且治疗后各个时间点HFNC组对PaO₂/FiO₂/指标改善明显优于COT组,差异具有统计学意义（P<0.01）。治疗后12 h、24 h、48 h两组呼吸频率均较治疗前明显降低（P<0.05）,且治疗后各个时间点HFNC组对呼吸频率改善明显优于COT组,差异具有统计学意义（P<0.01）。治疗后两组患者舒适度评分均较治疗前明显升高、疲劳程度评分较治疗前明显降低（P<0.05）,HFNC组对舒适度、疲劳程度评分改善程度明显优于COT组（P<0.01）。HFNC组患者气管插管占比、非机械通气天数明显少于COT组（P<0.01）,死亡人数占比两组患者差异无统计学意义（P>0.05）。结论：经鼻高流量湿化氧疗可以改善肺癌放射性肺炎合并呼吸衰竭患者氧合指数,降低患者呼吸频率,改善患者舒适度和促进患者预后。     

反复呼吸道感染患者的微生态学分析

冬季是呼吸道反复感染的多发季节。我们对反复发生呼吸道感染病人口咽粘膜菌群的定植进行了分析。结果表明,正常组需氧菌群密度为４．１１３５±０．０８８４,厌氧菌群密度为４．４１０１±０．３５８６１;患者需氧菌群密度为４．５２９０±０．００８６,厌氧菌群密度为４．８７１８±０．３４２４。反复呼吸道感染患者需氧菌和厌氧菌的含量均不于正常对照组（Ｐ＜０．０５）。１８例病人分离出两种以上需氧菌,奈瑟氏菌和肺炎链球菌检出率较高,分别为３８．７％和２２．６％;厌氧菌以韦荣氏球菌和消化链球菌为多见,检出率分别为３２．２％和５８．１％。有７例病人分离出白色念珠菌。４例病人分离出绿脓杆菌,明显表现出微生态失调。药敏结果表明,不同菌株对抗生素均有一定的耐药性存在。     

用纤维支气管镜检查236例肺部感染者的病原学分析

本文报告了２３６例支气管肺部感染者,用纤支镜双塞保护法采样,病原菌培养结果。总阳性率７４．６％。共分离到２２种２９１株病原菌。球茵占１６．７％、肠杆菌科占１１．７％、非发酵菌占３７．１％,厌氧菌占２２．３％、真菌占１２．７％,３９．２％的病例为复合菌感染。还报告了８种带见病原菌对２８种抗生素的敏感试验结果。对近年肺部感染的病原菌谱型变化及复合菌感染等进行了讨论。     

Neural organization of the ventilatory activity in the frog,Rana catesbeiana. II

The paralyzed, decerebrate frog, Rana catesbeiana, displays “fictive” oropharyngeal and pulmonary ventilations. In order to evaluate the neuronal correlates of these two centrally programmed ventilatory bursting patterns, we have performed intra-and extracellular recordings of bulbar respiratory neurons in this fictively breathing preparation. A total of 123 respiratory neurons were recorded from the caudal medulla. Of 51 antidromically activated neurons, 20 were vagal motoneurons and 31 were hypoglossal motoneurons. Respiratory neurons that depolarized during the lung (L) or non-lung (N) ventilatory phases were classified as L or N neurons, respectively. Phase spanning neurons (S) were active during both L and N phases. Some neurons showed oscillations of membrane potential synchronous with oropharyngeal ventilation. Those active during the buccal elevation phase were exclusively L neurons whereas those having buccal depressor activity were exclusively N neurons. Synaptic drive potentials were observed in all neurons recorded intracellularly. In some neurons, hyperpolarization was caused by inhibitory postsynaptic potentials, as demonstrated by reversal of membrane potential trajectory after intracellular chloride iontophoresis. Some individual motoneurons and interneurons exhibited both pulmonary and buccal ventilatory activity, indicating that both pattern generators project to a common motor control system. 1994 John Wiley & Sons, Inc.