Effect of different ways of respiratory support on the parameters of respiratory

We investigated the effect of three types of respiratory support on respiratory parameters in conscious healthy humans. For each type of respiratory support set specific changes in the pattern of volume and temporal parameters. One response to all types of respiratory support was hyperventilating, although varying degrees, and as a consequence, hypocapnia. These changes are not related to the metabolic needs and probably are the result of the interaction mechanisms of automatic and voluntary regulation of breathing movements.     

Respiratory potential of maize (Zea mays L.) roots exposed to hypoxia

When hypoxia is not too severe, root aerobic metabolism can be partly supported by oxygen delivery via aerenchymateous tissues. In terms of supplying energy, this adaptation is of special importance in plants with a high metabolic demand, such as maize (Zea mays L.). The ability of maize to respond to hypoxia by morphological changes is well documented; however, little is known on the potential for oxidative metabolism in different types of maize roots. In our study, we assessed the root respiratory potential in seminal and adventious nodal roots of maize exposed to mild short-term hypoxia. Plants responded to the treatment with an increased portion of nodal roots per total root length, while there were no changes in the biomass of shoots and roots. Thick nodal roots had much higher respiratory potential (Electron Transport System Activity – ETS) than nodal roots of smaller diameter or seminal roots, irrespective of the aeration rate. The only change in ETS under oxygen deficiency was found for seminal roots where oxygen consumption increased by 25%. Increased root porosity was observed in all roots, the increase was higher in nodal roots. On the basis of ETS data and taking into account changes of root morphology, it can be concluded that large changes of root respiratory potential are not involved in the response of maize to hypoxia. Obviously, maize can cover the respiratory needs with shifts in the growth of different root types which inherently differ in their potential aerobic respiration.     

Impulse activity of bulbar respiratory neurons in myocardial ischemia in cats

Acute experiments on cats anesthetized with nembutal, using a microelectrode technique, have demonstrated that pinching of the coronary artery involves changes in the patterns of impulse activity in all types of bulbar respiratory neurons, up to the appearance of ischemic shifts on the ECG. Progression of myocardial ischemia is paralleled by changes in all the bulbar respiratory neurons.     

Morphological and pharmacological basis for pulmonary ventilation in Amphiuma tridactylum

Summary The lung of the giant salamander, Amphiuma tridactylum, is divided into respiratory alveoli by muscular septa that increase the surface area of the lung as well as provide a mechanism for its almost complete collapse during exhalation. The epithelium of the internal surface is of two types: respiratory, composed of a single layer of pneumocytes overlying anastomosing capillaries, and non-respiratory, composed of ciliated cells and mucus-secreting goblet cells. Non-respiratory epithelium covers the apical edges of the septa, whereas the respiratory epithelium lines the alveoli. The smooth muscle of the septa and walls of the lung was studied in preparations of uninflated and acetylcholine-contracted lung. The muscle cells are ultrastructurally similar to other types of smooth muscle but are surrounded by extraordinary amounts of extracellular matrix, containing collagen and elastic fibers and numerous fine fibrils of unknown composition. Smooth muscle in isolated lung strips contracted in a dose-dependent manner when treated with acetylcholine or methacholine; contraction was blocked by atropine. Responses of lung strips to adrenergic agents were limited; only high doses of adrenalin caused slight relaxation of previously contracted muscle. These observations support the hypothesis that contraction of pulmonary smooth muscle is responsible for the ventilatory efficiency of the lung.     

Differential contribution of pacemaker properties to the generation of respiratory rhythms during normoxia and hypoxia

Pacemaker neurons have been described in most neural networks. However, whether such neurons are essential for generating an activity pattern in a given preparation remains mostly unknown. Here, we show that in the mammalian respiratory network two types of pacemaker neurons exist. Differential blockade of these neurons indicates that their relative contribution to respiratory rhythm generation changes during the transition from normoxia to hypoxia. During hypoxia, blockade of neurons with sodium-dependent bursting properties abolishes respiratory rhythm generation, while in normoxia respiratory rhythm generation only ceases upon pharmacological blockade of neurons with heterogeneous bursting properties. We propose that respiratory rhythm generation in normoxia depends on a heterogeneous population of pacemaker neurons, while during hypoxia the respiratory rhythm is driven by only one type of pacemaker.     

SIZE AND SHAPE TRANSFORMATIONS CORRELATED WITH OXIDATIVE PHOSPHORYLATION IN MITOCHONDRIA : I. Swelling-Shrinkage Mechanisms in Intact Mitochondria

Two types of swelling-shrinkage change manifested by isolated mammalian heart mitochondria have been studied. One type, designated as phase I or "low amplitude" swelling-shrinkage, is estimated to lead to changes in mitochondrial volume of 20 to 40 per cent, to changes in light scattering of about 30 per cent, and to changes in viscosity. These physical changes in mitochondria are brought about rapidly and reversibly by normal reactants of the respiratory chain. Their speed, specificity, and reversibility indicate that they are closely geared to the normal function of the respiratory chain and are a true reflection of a mechanochemical coupling process characteristic of the physiology of mitochondria. A second type of swelling-shrinkage mechanism, designated as phase II or "high amplitude," leads to changes in light scattering, viscosity, and mitochondrial volume which, frequently but not always, are of higher magnitude than the phase I type. Phase II swelling-shrinkage seems to be only partly under the control of the respiratory chain. Prior to the completion of phase II swelling, a stepwise loss of mitochondrial function can be identified, such as changes in the rate of substrate utilization and loss of respiratory control. Reversal of this type of swelling cannot be effected if the swelling change reaches a steady state. This type of swelling may provide cells with a mechanism for destroying mitochondrial substance.     

Invited review: Neural network plasticity in respiratory control.

Respiratory network plasticity is a modification in respiratory control that persists longer than the stimuli that evoke it or that changes the behavior produced by the network. Different durations and patterns of hypoxia can induce different types of respiratory memories. Lateral pontine neurons are required for decreases in respiratory frequency that follow brief hypoxia. Changes in synchrony and firing rates of ventrolateral and midline medullary neurons may contribute to the long-term facilitation of breathing after brief intermittent hypoxia. Long-term changes in central respiratory motor control may occur after spinal cord injury, and the brain stem network implicated in the production of the respiratory rhythm could be reconfigured to produce the cough motor pattern. Preliminary analysis suggests that elements of brain stem respiratory neural networks respond differently to hypoxia and hypercapnia and interact with areas involved in cardiovascular control. Plasticity or alterations in these networks may contribute to the chronic upregulation of sympathetic nerve activity and hypertension in sleep apnea syndrome and may also be involved in sudden infant death syndrome.     

小鼠感染合胞病毒与鼠流感病毒后肺脏病理学比较研究

目的与方法用合胞病毒(RSV)和鼠肺流感病毒(IVP)感染SPF级BALB/c小鼠,复制两种不同的小鼠病毒性肺炎动物模型,观察其临床症状,并对两种模型各自的肺部组织病理学特点进行研究。结果与结论IVP模型组与RSV模型组小鼠感染病毒后,分别在试验的2天和3天发病,临床症状均表现为精神沉郁、耸毛、卷缩、毛无光泽、活动减少、呼吸急促、咳嗽。但IVP感染模型组小鼠在发病后出现死亡,第7天其死亡率达到40%,而RSV感染模型组小鼠7日试验内无死亡病例发生。病理组织学诊断,RSV模型组小鼠为急性渗出性间质性肺炎,IVP模型组小鼠为出血性间质性肺炎。     

A quantitative evaluation of the extent of inner mitochondrial membrane destruction after freezing-thawing based on functional studies

An assay based on comparative investigation of ATPase and ATP synthetase changes in the activity in rat liver mitochondria after low temperature and uncoupler 2,4-dinitrophenol treatment is considered. By varying the activity of the respiratory chain, three extents of membrane cryoinjury could be distinguished by monitoring the changes in ATPase activity under different types of cryoinfluence. The first extent corresponds to a minimum membrane destruction, where the action of the respiratory chain compensates the changes in proton permeability and the cryotreatment does not change the ATPase activity. The second extent corresponds to changes in ion permeability which is partially compensated by the respiratory chain action. The third extent corresponds to a maximum membrane destruction and, therefore, maximum increase in permeability which is related to the irreversible stimulation of the ATPase activity and complete inhibition of the phosphorylation. In this study the extent of cryoinjury in mitochondrial preparations frozen and thawed at different rates was evaluated using this method.     

Deficiency of the complex I of the mitochondrial respiratory chain but improved adenylate control over succinate-dependent respiration are human gastric cancer-specific phenomena

The purpose of study was to comparatively characterize the oxidative phosphorylation (OXPHOS) and function of respiratory chain in mitochondria in human gastric corpus mucosa undergoing transition from normal to cancer states and in human gastric cancer cell lines, MKN28 and MKN45. The tissue samples taken by endobiopsy and the cells were permeabilized by saponin treatment to assess mitochondrial function in situ by high-resolution oxygraphy. Compared to the control group of endobiopsy samples, the maximal capacity of OXPHOS in the cancer group was almost twice lower. The respiratory chain complex I-dependent respiration, normalized to complex II-dependent respiration, was reduced that suggests deficiency of complex I, but the respiratory control by ADP in the presence of succinate was increased. Similar changes were observed also in mucosa adjacent to cancer tissue. The respiratory capacity of MKN45 cells was higher than that of MKN28 cells, but both types of cells exhibited a deficiency of complex I of the respiratory chain which appears to be an intrinsic property of the cancer cells. In conclusion, human gastric cancer is associated with decreased respiratory capacity, deficiency of the respiratory complex I of mitochondria, and improved coupling of succinate oxidation to phosphorylation in tumor tissue and adjacent atrophic mucosa. Detection of these changes in endobiopsy samples may be of diagnostic value.     

The Effect of Facial and Trapezius Muscle Tension on Respiratory Impedance in Asthma

This study tested two theories about the relationship between voluntary changes in muscle tension and pulmonary function in asthma. Kotses has theorized that decreased facial muscle tension decreases respiratory impedance via a hypothesized vagaltrigeminal reflex, but that muscle tension in other muscle groups has no such effect. Others have suggested that decreased thoracic muscle tension improves pulmonary function. Subjects were 19 volunteer asthmatic adults. They performed 3-minute cycles of deliberate muscle contraction, alternating two each for the shoulder and forehead muscles, followed by dominant forearm contraction. Surface EMG was measured from the frontalis and right trapezius areas. Airway impedance was measured by forced oscillation pneumography. Cardiac interbeat interval and respiratory sinus arrhythmia were measured to assess vagal tone. Frequency dependence of respiratory impedance increased during shoulder tension, giving some support to the theory relating thoracic tension to impairment in pulmonary function. Correlational analyses suggested a negative relationship between changes in cardiac interbeat interval and both frontalis muscle tension and decreased compliance of tissues in the airways. These findings are the opposite of those predicted by the vagal-trigeminal reflex theory.     

Effects of induced bronchoconstriction on pulmonary blood flow

Allergic bronchoconstriction may be associated with hemodynamic alterations due to changes in respiratory mechanics (or the associated changes in arterial blood gas composition) or the cardiovascular effects of chemical mediators. In an attempt to differentiate between these two possible mechanisms, we obtained measurements of hemodynamics, respiratory mechanics, and O2 consumption (VO2) in nine asymptomatic adult ragweed asthmatics before and after inhalation challenge with either ragweed extract or methacholine. We measured specific airway conductance (sGaw) by body plethysmography, pleural pressure with an esophageal balloon catheter, pulmonary blood flow (Q) and VO2 by a rebreathing technique, and heart rate. For a similar degree of bronchoconstriction after the two types of challenge (mean +/- SD sGaw 0.06 +/- 0.03 and 0.05 +/- 0.02 cmH2O-1 . s-1, P = NS), mean Q increased by 29 and 29%, and mean VO2 by 33 and 37% 15-20 min after ragweed and methacholine, respectively. Since heart rate did not change, there was a concomitant increase in mean stroke volume by 25 and 35%, respectively (P less than 0.05). The respiratory pleural pressure swings during quiet breathing and the rebreathing maneuver and the work of breathing during rebreathing also increased to a similar degree after the two types of challenge. These observations suggest that, if chemical mediators are released into the circulation during antigen-induced bronchoconstriction, their blood concentrations are too low for appreciable cardiovascular effects. The increase in rebreathing cardiac output during allergic and nonallergic bronchoconstriction is probably due to increases in intrathoracic pressure swings and in the work of breathing.     

Current Perspectives for Management of Acute Respiratory Insufficiency in Premature Infants with Acute Respiratory Syndrome

Current perspectives for management of acute respiratory insufficiency in premature infants with acute respiratory syndrome and the pathology of acute respiratory insufficiency in the preterm infant, including the current therapy modalities on disposition are presented. Since the therapeutical challenge and primary clinical goal are to normalize ventilation ratio and lung perfusion, when respiratory insufficiency occurs, it is very important to introduce the respiratory support as soon possible, in order to reduce development of pulmonary cyanosis and edema, and intrapulmonary or intracardial shunts. A characteristic respiratory instability that reflects through fluctuations in gas exchange and ventilation is often present in premature infants. Adapting the respiratory support on a continuous basis to the infant’s needs is challenging and not always effective. Although a large number of ventilation strategies for the neonate are available, there is a need for additional consensus on management of acute respiratory distress syndrome in pediatric population lately redefined by Berlin definition criteria, in order to efficiently apply various modes of respiratory support in daily pediatrician clinical use.     

Controlled trial of respiratory health worker visiting patients with chronic respiratory disability.

Seventy five patients with chronic respiratory disability were randomised to a group visited by a respiratory health worker (42) or control group (33). The first group was visited monthly by a respiratory nurse, who gave education and support. The effect of the intervention was assessed in terms of quality of life (by questionnaires), the number and duration of admissions to hospital, and the number of deaths. The questionnaires on quality of life showed no changes in either group during the study, but nearly all of the group visited by a respiratory health worker said that they valued the visits and wished them to continue. Their knowledge about their condition also improved compared with that of the controls. The duration of stay in hospital for respiratory reasons in the group visited by a respiratory health worker was longer than that of control patients. This was explained by their being scored as more ill than the controls on admission. Fewer patients died in the group visited by a respiratory health worker than in the control group (p = 0.11). The patients in the group visited by respiratory health workers may have survived longer because they sought help rather than dying at home. If confirmed this could have implications for the cost of their care.     

Nervous control of respiration: oxygen-sensitive elements in the prosoma of Limulus polyphemus.

1.Responses of oxygen-sensitive units in the prosomal haemal nerve of Limulus polyphemus were examined while varying the oxygen content of sea water bathing the intercoxal cuticle. 2. When exposed to high oxygen levels these units units maintained a continuous background discharge of spikes. Unit activity was inhibited when oxygen content decreased. Upon reintroduction of oxygen tonic spike discharge resumed. 3. Mechanosensitive units with receptive fields on the prosomal shield or intercoxal cuticle were also present in the haemal nerve. Neither the mechanosensitivity nor the background discharge of these units was affected by changes in oxygen content. 4. It is proposed that the oxygen-sensitive respiratory reflexes of Limulus are an adaption to existence in the tertidal zone. Published observations of the respiratory stress responses of many intertidal animals support this hypothesis.     

Ventrolateral medullary respiratory network participation in the expiration reflex in the cat.

The expiration reflex is a distinct airway defensive response characterized by a brief, intense expiratory effort and coordinated adduction and abduction of the laryngeal folds. This study addressed the hypothesis that the ventrolateral medullary respiratory network participates in the reflex. Extracellular neuron activity was recorded with microelectrode arrays in decerebrated, neuromuscular-blocked, ventilated cats. In 32 recordings (17 cats), 232 neurons were monitored in the rostral (including B?tzinger and pre-B?tzinger complexes) and caudal ventral respiratory group. Neurons were classified by firing pattern, evaluated for spinal projections, functional associations with recurrent laryngeal and lumbar nerves, and firing rate changes during brief, large increases in lumbar motor nerve discharge (fictive expiration reflex, FER) elicited during mechanical stimulation of the vocal folds. Two hundred eight neurons were respiratory modulated, and 24 were nonrespiratory; 104 of the respiratory and 6 of the nonrespiratory-modulated neurons had altered peak firing rates during the FER. Increased firing rates of bulbospinal neurons and expiratory laryngeal premotor and motoneurons during the expiratory burst of FER were accompanied by changes in the firing patterns of putative propriobulbar neurons proposed to participate in the eupneic respiratory network. The results support the hypothesis that elements of the rostral and caudal ventral respiratory groups participate in generating and shaping the motor output of the FER. A model is proposed for the participation of the respiratory network in the expiration reflex.     

营养风险筛查NRS2002的临床应用观察

采用营养风险筛查2002(NRS2002),选取2012年1月至2012年12月在上海市第十人民医院呼吸内科、肝胆内科、神经内科、普通外科、脊柱外科的新入院住院患者进行营养风险筛查,并调查住院期间的营养支持状况及营养指标的变化。结果显示,共有750例患者入选,呼吸内科和神经内科营养风险最高均为42%,但存在营养风险的患者营养支持率分别为23.8%和31.7%,肝胆内科存在营养风险的患者营养支持率最高,但也仅为47.6%;营养风险≥3分的患者中体质指数(BMI)、血清前白蛋白(PA)、血红蛋白(HB)3个指标均低于营养风险<3分的患者,且存在统计学意义(p<0.05)。结果表明,NRS2002适用于住院患者营养风险筛查,存在营养风险的患者营养支持率普遍较低,相关营养指标可辅助判断营养状况。     

An automated system for biocide testing on biofilms*

The paper presents and discusses a novel on-line real-time non-destructive continuous-flow system for biocide testing on industrial biofilms. This laboratory system is capable of monitoring changes in growth, accumulation and respiratory activity of biofilms in response to biocidal treatment. The system incorporates a fouling monitor for continuous measuring of the rate of biofilm accumulation (heat transfer resistance), a sensor for monitoring of microbial activity (oxygen meter for monitoring the rate of biofilm respiratory activity), and subsystems necessary for microbial life support and control of operation parameters. Examples of system operation and testing of oxidizing and non-oxidizing biocides are presented. Received 25 May 1997/ Accepted in revised form 25 November 1997     

Bronchoscopic transillumination guidance for open standard surgical tracheostomy

The standard tracheostomy technique, described in 1909 by Jackson, has been increasingly used in intensive care units. Since 1957, several different types of percutaneous tracheostomy techniques have been described and performed with the support of bronchoscopic transillumination. The authors present the case of a respiratory failure due to obstruction of the upper airway by an exceptionally large goiter, which was successfully resolved by a standard open surgical tracheostomy. In this case, surgical tracheostomy was preceded by bronchoscopic transillumination, which facilitated identification of the appropriate tracheostomy site.