Mechanism of initiation of oscillatory motion in human glottis

Phonatory onsets of 17 normal subjects under usual speech conditions were investigated by measuring the cross-sectional area of the glottic aperture, using a photoelectric device. During a normal soft or breathy onset of phonation, the vocal fold vibration begins with an open glottis; the pattern of the optical signal is a sine wave of increasing amplitude with one to eight cycles before steady state oscillation is achieved. The first deflection of the base-line is either towards adduction or towards abduction. The classically assumed--since van den Berg et al. (1957)--retro-aspiration phenomenon, consisting in a narrowing of the glottic chink due to the accelerated air flow, according to Bernoulli's law, is incompatible with these observations. An aerodynamic study, with accurate calibration of the photoelectric transducer in one trained subject, as well as flux and subglottic pressure measurements, suggests that the gas flux (air as well as a helium-oxygen mixture) reaches the condition of turbulence at the level of the glottic nozzle, just before vocal folds are set into oscillatory motion. The setting in motion of the free edge of the vocal folds in normal soft or breathy onset of phonation can be explained by a sudden modification of flow conditions within the expiratory gas : the flow is laminar in the trachea and suddenly becomes turbulent at the level of the glottic nozzle. On the other hand, approximately normal atmospheric pressure values are attained due to a Bernoulli-effect at that level, allowing the vocal folds to oscillate sinusoidally about their vibration axes, corresponding to their virtual resting position, like a forced oscillator.     

Transducer for monitoring respiration during imaging procedures

A transducer system for monitoring respiration is described; it uses a ‘liquid column’ sensor with a remote integrated circuit pressure module. It was designed primarily for non-invasive monitoring and control of respiration during diagnostic imaging procedures, but has also found applications in other areas, e.g. physiotherapy and pulse monitoring. The device is a new version of a system developed several years ago and takes advantage of relatively low cost commercial ‘building blocks’. The output is an analogue voltage (from a low impedance source) capable of driving a wide range of recorders, amplifiers and computer interfaces. Reference is also made in the text to a bio-feedback signal processing and display unit (described elsewhere) which, when used with this transducer, provides a versatile respiratory control system.     

A linear motor and compact cylinder-piston driver for left ventricular bypass

A simple, portable, reliable and noise-free pneumatic driver has been developed. It consists of a linear motor attached to a cylinder piston, in one unit. The motor coil is directly wound on the cylinder, and the permanent magnet is fixed to the piston. As a continuous voltage square wave is applied to the coil, the cylinder reciprocates on the piston periodically, producing air pressure and vacuum alternately. In conjunction with a locally made diaphragm pump, the driver was tested in vitro and in vivo. Results demonstrated that the device could drive the diaphragm pump and so support the circulation of an experimental animal. The driver weighs 12 kg. For 200 mmHg air pressure and — 80 mmHg vacuum the power consumed is 30 W. Its noise is about 30 dB, less than that of an artificial valve and pump.     

USE OF THE ROCKING BED TO AUGMENT VENTILATION IN PATIENTS WITH POLIOMYELITIS

As the first step in an attempt to clarify criteria for use of the rocking bed rather than the respirator as an aid to breathing for patients with weakness of respiratory muscle function caused by poliomyelitis, ventilation studies were done on seven patients with pronounced weakness or paralysis of the respiratory muscles. Average tidal air volume was considerably less when the patient was on the rocking bed than when he was in the respirator. Since the tidal air volume with the patient on the rocking bed represents the maximum that can be produced with the apparatus, whereas the volume in the respirator represents the patient''s usual tidal air and the respirator is capable of a greater volume if necessary, it is apparent that in cases of complete paralysis of the respiratory muscles the respirator has a large margin of safety, the rocking bed none.From clinical observations made on 51 patients who were put upon the rocking bed—23 of them early in the course of the disease and 28 after they had been ill three months or more—it was concluded that the rocking bed is contraindicated for patients who are febrile and in whom the disease is progressing rapidly, and for those with atelectasis or urinary or pulmonary infection. It must be used with extreme care in the case of patients early in the course of the disease who are not tracheotomized, because of a tendency toward increased accumulation of mucus and the danger of atelectasis.General guides were developed with regard to use of the rocking bed for patients with post-acute poliomyelitis, and somewhat different rules were drawn for use of the apparatus in cases in which there is a chronic respiratory problem.The rocking bed will give artificial respiration in cases of respiratory weakness, but will not provide enough tidal air for the patient with paralysis of the muscles of respiration.     

Hepatic respiratory compensation and blood volume in the frog (Rana esculenta)

In the frog, Rana esculenta (L.), the liver can change in volume by over 25%, depending on the respiratory conditions of the animal: in well-oxygenated specimens the organ can hoard about half of the total amount of erythrocytes in its sinusoids, and release them into the bloodstream under conditions of hypoxia. This phenomenon can be observed at a temperature of 6°C by comparing the liver volumes and haematic values of chlorobutanol-anaesthetized animals exposed to the air or submerged in still water (a condition which induces hypoxia): the blood volume remains constant, at about 5 ml per 100g of body weight, but red blood cell count and haematocrit value differ by as much as 50%. At 18°C there is an increase in oxygen demand and in anaesthetized animals, which rely totally on cutaneous respiration, the compensatory liver mechanism can no longer be observed, since all the available erythrocytes are already circulating in a blood volume which, depending on respiratory conditions, can vary between about 7 and 8ml/100g. At 30°C, cutaneous respiration alone does not allow the anaesthetized animals to survive long enough to stabilize their haematic parameters.     

Comparative characteristic of respiratory pattern responses to kainic acid microinjections in different parts of the nucleus ambiguous

In rats, local chemical isolation of neurones by the kainic acid helped to investigate into comparative role of different parts of the n. ambiguus in respiratory control mechanisms. We disclosed specific peculiarities of responses of rhythm and respiratory pattern to chemical isolation of different parts of the n. ambiguus. In particular, it was found that consecutive isolation of the left and right rostral parts of the n. ambiguus caused a significant decrease of the respiration rate and respiratory volume and also resulted in irreversible cessation of respiration in 83% of experiments. Isolation of symmetric medial parts of the n. ambiguus resulted in bradypnoe and a decrease of pulmonary ventilation; maximal respiratory effect was recorded after kainic acid injection in the symmetric part only, thus the irreversible cessation of respiration was recorded in 50% of experiments. After isolation of symmetric caudal parts of the n. ambiguus we observed an insignificant decrease of the respiration rate without significant changes of the respiratory volume, and number of the respiration cessation was minimal: 33%.     

Cyclic model of respiration applied to asymmetrical ventilation and periodic breathing

A model taking into account the cyclic character of respiration in humans is developed using two classical simplifications: CO₂ is the only respiratory gas involved; and respiration is regulated only by a CO₂ linear controller. The model is used to investigate two important clinical aspects of respiratory disease: asymmetrical ventilation and periodic breathing. We show that asymmetry in ventilation significantly influences the time course of the CO₂ partial pressure in the expired alveolar air at the mouth and the elimination of CO₂ through the lungs. Furthermore, the CO₂ controller delay plays a major role in periodic breathing.     

Effects of Atmospheric CO(2) Enrichment on Photosynthesis, Respiration, and Growth of Sour Orange Trees

Numerous net photosynthetic and dark respiratory measurements were made over a period of 4 years on leaves of 24 sour orange (Citrus aurantium) trees; 8 of them growing in ambient air at a mean CO₂ concentration of 400 microliters per liter, and 16 growing in air enriched with CO₂ to concentrations approaching 1000 microliters per liter. Over this CO₂ concentration range, net photosynthesis increased linearly with CO₂ by more than 200%, whereas dark respiration decreased linearly to only 20% of its initial value. These results, together with those of a comprehensive fine-root biomass determination and two independent aboveground trunk and branch volume inventories, suggest that a doubling of the air's current mean CO₂ concentration of 360 microliters per liter would enhance the growth of the trees by a factor of 3.8.     

Experimental and modelling data contradict the idea of respiratory down-regulation in plant tissues at an internal [O2] substantially above the critical oxygen pressure for cytochrome oxidase

? Some recent data on O(2) scavenging by root segments showed a two-phase reduction in respiration rate starting at/above 21 kPa O(2) in the respirometer medium. The initial decline was attributed to a down-regulation of respiration, involving enzymes other than cytochrome oxidase, and interpreted as a means of conserving O(2). As this appeared to contradict earlier findings, we sought to clarify the position by mathematical modelling of the respirometer system. ? The Fortran-based model accommodated the multicylindrical diffusive and respiratory characteristics of roots and the kinetics of the scavenging process. Output included moving images and data files of respiratory activity and [O(2)] from root centre to respirometer medium. ? With respiration at any locus following a mitochondrial cytochrome oxidase O(2) dependence curve (the Michaelis-Menten constant K(m) = 0.0108 kPa; critical O(2) pressure, 1-2 kPa), the declining rate of O(2) consumption proved to be biphasic: an initial, long semi-linear part, reflecting the spread of severe hypoxia within the stele, followed by a short curvilinear fall, reflecting its extension through the pericycle and cortex. ? We conclude that the initial respiratory decline in root respiration recently noted in respirometry studies is attributable to the spread of severe hypoxia from the root centre, rather than a conservation of O(2) by controlled down-regulation of respiration based on O(2) sensors.     

The coordination and interaction between respiration and deglutition in young pigs

The anatomical pathways for inspired air and ingested food cross in the pharynx of mammals, implying that breathing and swallowing must be separated either in space or in time. In this study we investigated the time relationship between swallowing and respiration in young pigs, as a model for suckling mammals. Despite the high morphological position of the larynx in young mammals, allowing liquid to pass in food channels lateral to the larynx, respiration and swallowing are not wholly independent events. Although, when suckling on a veterinary teat, the swallows occurred at various points in the respiratory cycle, there was always a period of apnea associated with the swallow. Finally, an increase in the viscosity of the milk altered this coordination, changing respiratory cycle length and also restricting the relative rate at which swallows occurred in some parts of the respiratory cycle. These results suggest that the subsequent changes in respiratory activity at weaning, associated with passage of a solid bolus over the larynx, is preceded by the ability of the animal to alter coordination between respiration and swallowing for a liquid bolus. Accepted: 29 September 1997     

Design of a new pulse duplicator system for prosthetic heart valves

This paper discusses results of a computer simulation for designing a new pulse duplicator system for mechanical heart valves. The design objective of the system is to obtain a compact, efficient pulse duplicator system capable of accurately measuring the volume flow rate across a valve. The volume flow rate is determined as the derivative of the volume displacement of an actuator piston which directly drives the fluid. The system does not need any circulatory loop, since the piston is controlled on-line to follow command signals representing an aortic impedance. The results of the computer simulation show: the designed PI-controllers of the actuator can precisely control valve motion to follow given command signals, the eigenvalues of the controllers have to be carefully chosen to prevent unstable behaviors of a valve in diastole, and the dimensions of the actuator is optimized by minimizing a cost function of the total efficiency of the system.     

Apparatus for the automated measurement of the responses of humans to odorants

An automated system for the measurement of the psychophysicaland physiological responses of humans to odorant stimulationof the nose and eyes is described. All aspects of the generationand production of odor stimuli, the recording of physiologicaland psychophysical responses of the subjects and the storageof data are managed by an Apple He computer. Both the nasaland ocular olfactometers are based on electronic mass flow controllerswhich are used to control the ratios of volume flow rates ofclean and odorant-saturated air. The output of each olfactometeris measured by a photo-ionization detector. Odor stimuli aredelivered to custom-fitted face masks, that allow separate stimulationof the nose and eyes, through Teflon (rtm) flow valves. A videocamera records the responses of the eyes and a pneumotachograph,in combination with a pressure transducer, records changes inrespiratory behavior. An electronic mouse is used to enter thesubject's psychophysical responses directly into the computer.The advantages of this methodology and its current and potentialapplications are discussed.     

Regulation of respiration: visceral and behavioural components

The review segregates two aspects of respiration regulation: autonomous respiration regulation as a visceral function ensuring metabolic needs of a body by maintaining stability of own respiratory environment, on the one hand, and behavioural regulation of respiration under control of the volitional sphere, on the other hand. The authors focus on respiratory rythmogenesis, the problem that has not yet been resolved, and on the mechanism of precise correlation of lung ventillation with the metabolic level, in case of muscular exercise, in particular. The authors discuss interaction of visceral and behavioural mechanisms of respiratory regulation. The substance of the phenomenon of respiratory embarrassment is considered in this connection as a visceral signal addressed to the behavioural sphere. Reasonableness of introduction of a new breathing system in a healthy person is doubted. The article justifies the pracice of bioregulation of the respiratory function.     

Effect of lipine, a new antihypoxic agent on some respiratory indices in newborn infants after asphyxia]

Lipine, a new antihypoxic drug, has been studied for its effect on respiration and pulmonary gaseous exchange in 47 newborn children, health and with respiratory distress syndrome stresses (SRD) after perinatal asphyxia. It is shown that lipine inhalations cause a considerable increase in duration of respiratory cycle, decrease of respiration frequency, ratio of ispiration di time, to expiration time, increase of alveolar ventilation volume and decrease of respiratory dead space ventilation volume in all lung ventilation volume in newborns with SRD, to a larger degree pronounced in premature children. A conclusion is made on the positive effect of lipine on the state of respiration function and gaseous exchange in lungs in newborn children with symptoms of SRD.     

A Portable System for Measuring the Photosynthesis and Transpiration of Graminaceous Leaves

A portable system has been developed for measuring rates ofphotosynthesis and transpiration of Graminaceous leaves; itcomprises a transparent chamber, into which the leaves are sealed,and a gas supply. The chamber is made from poly 4-methylpent-1-ene(PMP), chosen for its transparency and small water absorption.The leaf is sealed into the chamber by an inflatable rubberseal. The chamber contains a humidity sensor, photocell, thermistor,and a fan which is positioned to give efficient gas-mixing andrapid thermal equilibration. The chamber is surrounded by aPerspex tube to absorb part of the incident infrared radiation.Another fan blows ambient air between the chamber and the Perspextube to counteract solar heating of the chamber wall. The gas supply to the chamber comes from a gas cylinder viaa dilutor. The dilutor contains four small orifices arrangedin parallel. Each orifice is mounted in the inlet of a two-waygas valve: one way goes to the leaf chamber directly, the othervia a CO₂ absorber. The total gas flow-rate is independent ofvalve position, and the CO₂ concentration entering the chambercan be varied from zero to the cylinder concentration by switchingthe valves. The system has been tested both in the laboratory and in thefield, with satisfactory results.     

Augmentation of hypoxic respiration after brief hyperoxia in the anesthetized cat: Putative function of GABA<Subscript>A</Subscript> neurotransmission

In this study, we attempted to determine the role of GABA neurotransmission in augmentation of hypoxic respiration by antecedent hyperoxic breathing. The experiments were performed in anesthetized, paralyzed and vagotomized cats divided into control and bicuculline (a GABA_A receptor blocker)-injected groups. The experimental protocol consisted of exposing the animals to successive hypoxic-hyperoxic-hypoxic conditions. Respiration was assessed using phrenic electroneurograms, from which the peak phrenic height, a surrogate of the tidal volume component, and respiratory rate were obtained, and their product, the respiratory minute output, was calculated. We found that prior hyperoxic ventilation increased the subsequent respiratory response to hypoxia by an average of 23.5%, compared with the preoxygen response. This increase was driven by volume respiration. The biphasic character of the hypoxic respiratory response, consisting of stimulatory and depressant phases, was sustained. Bicuculline abolished the augmentative effect on hypoxic respiration of prior hyperoxia, which suggests that oxygenation induces GABA_A-mediated hyperexcitability of respiratory neurons, possibly by the liberation of reactive oxygen species. We concluded that GABA neurotransmission is pertinent to the effect of hyperoxia on hypoxic respiratory reactivity.     

Actuating Mechanism and Design of a Cylindrical Traveling Wave Ultrasonic Motor Using Cantilever Type Composite Transducer

Background

Ultrasonic motors (USM) are based on the concept of driving the rotor by a mechanical vibration excited on the stator via piezoelectric effect. USM exhibit merits such as simple structure, quick response, quiet operation, self-locking when power off, nonelectromagnetic radiation and higher position accuracy.

Principal Findings

A cylindrical type traveling wave ultrasonic motor using cantilever type composite transducer was proposed in this paper. There are two cantilevers on the outside surface of cylinder, four longitudinal PZT ceramics are set between the cantilevers, and four bending PZT ceramics are set on each outside surface of cantilevers. Two degenerate flexural vibration modes spatially and temporally orthogonal to each other in the cylinder are excited by the composite transducer. In this new design, a single transducer can excite a flexural traveling wave in the cylinder. Thus, elliptical motions are achieved on the teeth. The actuating mechanism of proposed motor was analyzed. The stator was designed with FEM. The two vibration modes of stator were degenerated. Transient analysis was developed to gain the vibration characteristic of stator, and results indicate the motion trajectories of nodes on the teeth are nearly ellipses.

Conclusions

The study results verify the feasibility of the proposed design. The wave excited in the cylinder isn''t an ideal traveling wave, and the vibration amplitudes are inconsistent. The distortion of traveling wave is generated by the deformation of bending vibration mode of cylinder, which is caused by the coupling effect between the cylinder and transducer. Analysis results also prove that the objective motions of nodes on the teeth are three-dimensional vibrations. But, the vibration in axial direction is minute compared with the vibrations in circumferential and radial direction. The results of this paper can guide the development of this new type of motor.     

Post-embryonic development of water- and airbreathing organs of Anabas testudineus (Bloch)

The development of respiratory surfaces in post-embryonic stages of Anabas testudineus was studied using morphometric methods on serial sections through the pharyngeal region of specimens obtained by induced breeding of known parentage. The larvae and fry were fixed in glutaraldehyde and osmium tetroxide. In the young stages aquatic respiration was found to be obligatory. The hatchlings come out of the egg membranes about 10 h after fertilization. During the yolk-sac stages gaseous exchange takes place through the well vascularized skin. The gills start differentiating at about 24 h and become functional at about 39 h. The labyrinthine organs begin to develop after 51 h but the hatchlings do not take an air breath until they reach 13–14 days. The appearance of scales at 11–14 days probably hinders cutaneous respiration and is correlated with the onset of aerial respiration.
Morphometric analysis using stereological methods shows high surface: volume ratios for the gills and labyrinthine organs as adaptations to gas exchange function. A marked decrease in surface: volume ratio for the suprabranchial cavities between 7 and 11 days indicates an increase in volume to accommodate the expanding labyrinthine plates which retain a fairly constant surface: volume ratio.     

Oxygen reperfusion damage in an insect

The deleterious effects of anoxia followed by reperfusion with oxygen in higher animals including mammals are well known. A convenient and genetically well characterized small-animal model that exhibits reproducible, quantifiable oxygen reperfusion damage is currently lacking. Here we describe the dynamics of whole-organism metabolic recovery from anoxia in an insect, Drosophila melanogaster, and report that damage caused by oxygen reperfusion can be quantified in a novel but straightforward way. We monitored CO(2) emission (an index of mitochondrial activity) and water vapor output (an index of neuromuscular control of the spiracles, which are valves between the outside air and the insect's tracheal system) during entry into, and recovery from, rapid-onset anoxia exposure with durations ranging from 7.5 to 120 minutes. Anoxia caused a brief peak of CO(2) output followed by knock-out. Mitochondrial respiration ceased and the spiracle constrictor muscles relaxed, but then re-contracted, presumably powered by anaerobic processes. Reperfusion to sustained normoxia caused a bimodal re-activation of mitochondrial respiration, and in the case of the spiracle constrictor muscles, slow inactivation followed by re-activation. After long anoxia durations, both the bimodality of mitochondrial reactivation and the recovery of spiracular control were impaired. Repeated reperfusion followed by episodes of anoxia depressed mitochondrial respiratory flux rates and damaged the integrity of the spiracular control system in a dose-dependent fashion. This is the first time that physiological evidence of oxygen reperfusion damage has been described in an insect or any invertebrate. We suggest that some of the traditional approaches of insect respiratory biology, such as quantifying respiratory water loss, may facilitate using D. melanogaster as a convenient, well-characterized experimental model for studying the underlying biology and mechanisms of ischemia and reperfusion damage and its possible mitigation.     

Relationships between specialized cells, capillaries and intermediary cytofibrillary elements. XVth note. Biological evolution of the respiratory stereotype and subsystem in aquatic vertebrates

The author continues in aquatic vertebrates the study of the evolution of the respiratory stereotype initiated in the XIIth note of this series and carried out in the light of the systemic conception (Bertalanffy), of Needham's theory of order in nature, and of the theory of biological stereotypes (Marza, Repciuc, Eskenasy). The stability of some characters of the respiratory stereotype inherited by vertebrates from invertebrates is pointed out. The respiratory stereotype in vertebrates gradually passed from the respiration of water-dissolved oxygen through branchiae and skin, to the concomitant uptake of this form and of air oxygen (through buccopharyngeal formations, gaseous bladder or rudimentary lungs in osseous fishes), the double respiration (in Amphibia) and later the air respiration in Reptilia. The five steps of this gradual evolution are described, as well as the conditions of the evolution from crossopterygians to Tetrapoda (amphibians and reptiles).