Effects of amino acids on the excitability of respiratory bulbospinal neurons in solitary and para-ambigual regions of medulla in cat

The effects of inhibitory (gamma-aminobutyric acid (GABA) and glycine) and excitatory (L-glutamate and DL-homocysteate, DLH) amino acids on the excitability of respiratory bulbospinal neurons were studied in decerebrate, paralyzed, bilaterally vagotomized, artificially ventilated cats. Unit activities were recorded extracellularly in the medulla in both the ventrolateral portion of the nucleus tractus solitarius and the para-ambigual region in the vicinity of the nucleus ambiguus (dorsal and ventral respiratory groups, respectively). All neurons were bulbospinal since they could be antidromically activated by electrical stimuli to the spinal cord. We used variations in antidromic latency (ADL) as a measure of changes in excitability of the soma. All neurons exhibited variations in ADL related to the respiratory cycle, being shortest (minimum ADL) during neural activity and longest (maximum ADL) in the silent period. Neurons whose discharge frequencies fell during application of putative inhibitory amino acids showed an increase of minimum ADL compared to control, indicating hyperpolarization. Minimum ADL, in some cells, became shorter during application of excitatory amino acids, indicating depolarization; in others, mechanisms secondary to increased neuronal firing likely obscured their effects. The transient maximum ADL usually present at the onset of the silent period was increased by excitatory amino acids and, in some units, was reduced or eliminated by inhibitory amino acids. These effects are discussed in terms of a modulation by synaptic inputs and neurotransmitters of the cumulative afterhyperpolarization which follows bursts of action potentials.     

An Intrapleural Lung Prosthesis: Rationale, Design, and Testing

Abstract: Extracorporeal life support (ECLS or ECMO) is standard treatment for severe respiratory failure but poses many contraindications to future lung transplantation. The solution to this dilemma is the implantable gas exchange device (IGED) or artificial lung. Preliminary efforts to create such an artificial lung have been made since 1970 and include designs involving single devices, intravascular devices (i. e., IVOX), and combination heart–lung devices, Stringent requirements govern the design of such a device, the most important of which are high gas exchange efficiency, low resistance to blood flow, and size. This paper describes such a device. It incorporates large diameter inflow and outflow ports in close proximity and a low resistance wound hollow fiber core encapsulated in a compliant outer shell which conserves the work of the right ventricle. In a large animal model (adult sheep) this device was connected in line with the main pulmonary artery in series with the native lungs. This configuration has the advantages of using the lungs as an embolic filter, perfusing the lungs with fully oxygenated blood, and maintaining the integrity of the anatomy necessary for transplant. Laboratory experiments have run >8 h. Preliminary data show that the animals have remained hemodynamically stable while the devices have supported the animals completely by supplying 100% O₂ saturation with PO₂ values ranging from 250–350 mm Hg. Additionally, this model makes possible the study of respiratory failure without introducing other variables such as extracorporeal circuits or pumps. The other metabolic, endocrine, and reticuloendothelial functions of normal and injured lungs can now be studied more precisely by excluding these variables. Further studies are needed to evaluate this device in chronic (long–term implantation) experiments before clinical application.     

A follow-up study of respiratory function in workers exposed to acid aerosols in a food-processing industry

A follow-up investigation was performed on 49 female workers studied 2 years earlier in a vegetable-pickling plant. Acute and chronic respiratory symptoms and ventilatory capacity measurements were recorded during the original and the follow-up studies. Maximal expiratory flow-volume (MEFV) curves were recorded during the Monday morning work shift. The forced vital capacity (FVC), 1-s forced expiratory volume (FEV1), and flow rates at 50% and the last 25% of the FVC (FEF50, FEF25) were measured. There were small increases in the prevalence of chronic symptoms between the two studies for both smokers and nonsmokers, but these did not reach statistical significance. Five workers at the time of the initial study had a diagnosis of occupational asthma; only one of these was still working at the time of follow-up. Workers lost to the follow-up had lower lung function than those seen at follow-up. In workers who were followed, larger than expected mean annual declines were noted for all ventilatory capacity parameters in both smokers (FVC 0.070 l, FEV1 0.070 l; FEF50 0.355 l/s, FEF25 0.270 l/s) and nonsmokers (FVC 0.045 l, FEV1 0.045 l, FEF50 0.285 l/s; FEF25 0.130 l/s). The decrease was particularly pronounced for FEF50 and FEF25. The accelerated decline in ventilatory capacity tests noted in the female nonsmokers suggests an independent effect on lung function of work exposure in this environment. Our data confirm that work in the pickling industry, particularly in small, poorly regulated plants, has deleterious effects on respiratory function. Received: 24 September 1996 / Accepted: 19 June 1997     

海水型呼吸窘迫综合征兔肾皮质酶活性定位和图像分析

采用超微结构细胞化学和图像分析技术，对兔海水型呼吸窘迫综合征（ＳＷ－ＲＤＳ）肾皮质酶活性的变化进行了观察。ＳＷ－ＲＤＳ组肾皮质碱性磷酸酶、５’－核苷酸酶、对－硝基苯磷酸酶和细胞色素氧化酶活性明显下降，而胞嘧啶单核苷酸酶活性明显增强。这表明肾皮质一些酶活性的改变是兔ＳＷ－ＲＤＳ发病机理之一。     

无创正压通气改善慢性阻塞性肺疾病并呼吸衰竭的临床观察

目的评价无创正压通气(NPPV)治疗慢性阻塞性肺疾病(COPD)的临床效果.方法51例COPD急性加重并Ⅱ型呼吸衰竭患者随机分为常规治疗组(26例)和NPPV组(25例),观察两组患者治疗前后动脉血气变化及病情转归.结果与治疗前比较,NPPV组治疗24 h后PaO2明显升高,PaCO2明显下降(P＜0.01),常规治疗组治疗24 h后PaO2亦有上升(P＜0 05),PaCO2则无明显变化,(P＞0.05).治疗24 h后NPPV组PaO2升高和PaCO2下降较常规治疗组更为显著(P＜0.05).常规治疗组的失败率(34.6%)显著高于NPPV组(16.0%,P＜0.05).NPPV组的平均住院天数(14.5±6.7)d明显短于常规治疗组(23.8±9.2)d,P＜0.05.结论NPPV可明显改善COPD急性加重并Ⅱ型呼吸衰竭患者的气体交换,纠正低氧血症和高碳酸血症,提高抢救成功率.     

Prevalence of respiratory allergy in a platinum refinery

Summary In a cross-sectional study, 65 workers in the chemical industry with exposure to platinum salts were investigated with regard to the prevalence to allergic respiratory tract diseases. A respriatory questionnaire, a skin-prick test with K₂PtCl₆ and environmental allergens, determination of total IgE, platinum-specific IgE and histamine release in basophilic granulocytes and lung function tests were applied before and after a Monday shift and after a Friday shift. Work-related symptoms of respiratory allergy were present in 23% of all workers, but were significantly more frequent in the most exposed group in the platinum refinery (52.4%). Of all workers, 18.7% had a positive skin-prick test with platinum salt. As compared to the other workers, the workers with work-related symptoms of respiratory allergy had significantly more positive skin-prick tests (64.3%) and a higher total IgE and platinum-specific IgE; they did not, however, show higher histamine release. In the course of the week, a significant fall in lung function, namely in FEV₁ and FEF25, was recorded in the group of workers with work-related symptoms.     

A new respiratory valve system for measuring oxygen uptake during swimming

We describe a new respiratory valve system with minimal dead space, which allows measurement of ventilation and oxygen uptake during swimming. The device offers considerable advantages in efficiency and accuracy over current equipment, and can be used in conjunction either with a miniaturized telemetry system for oxygen uptake measurement or with a conventional system. The valve has a low airflow resistance, a small dead space (15 ml), and an electrically operating, closed-circuit pump to remove excess water from the expiratory tube. The external form and the buoyancy of the valve have been hydrostatically and hydrodynamically designed to reduce drag and to ensure a correct mass in the water. To obtain this result a very sophisticated material, carbon fibre, has been utilized. Our studies showed that this respiratory system is ideal for obtaining valid and reliable values of oxygen uptake during swimming, even at high speed and in endurance swimming tests.     

急性氨中毒致上呼吸道损伤的临床分析

目的 :观察氨中毒损伤上呼吸道的症状及治疗效果。方法 :回顾分析急性氨中毒致上呼吸道损伤1 67例的临床资料。结果 :患者均愈后良好 ,无因上呼吸道损伤而死亡的病例 ,有少数患者遗留声嘶及慢性咽炎。结论 :在急性氨中毒致上呼吸道损伤患者的救治过程中合理应用糖皮质激素、酸性雾化液及抗生素至关重要。     

肺脾双补治疗小儿反复呼吸道感染

目的 :观察肺脾双补法治疗小儿反复呼吸道感染 (RRTI)的疗效并探讨其作用机理。方法 :RRTI患儿 1 2 0例随机分为治疗组及对照组 ,治疗组在急性呼吸道感染期给以中药汤剂 ,感染好转后口服中药 (玉屏风散合四君子汤加减 ) ,每日一剂 ,连用两周。对照组感染期间使用西药抗生素及抗病毒剂治疗 ,感染缓解后不用药 ,两组于治疗前及治疗后 1月检测免疫球蛋白、T细胞亚群。结果 :治疗组有效率为 92 .6% ,对照组有效率为 34.6% ,两组比较差异显著( p <0 .0 1 )。治疗组IgA、IgG及CD3、CD4、CD4/CD8增高 ,CD8降低 ,与对照组比较有显著差异。结论 :肺脾双补法对RRTI有较好疗效 ,并有提高体液免疫与细胞免疫的作用     

延髓腹外侧区在调节呼吸和心血管系统中的作用

现已知延髓腹外侧区在呼吸调节和心血管调节中起着重要作用．延髓腹外侧区有两个重要的血管运动中枢，称为头侧和尾侧血管运动中枢．参与呼吸调节的中枢化学感受器位于延髓腹外侧区浅表部位；延髓腹外侧区还参与中枢和外周化学感受器的传入冲动的整合．文章对一些最重要的有争论的观点作一综述