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Respiratory Control (respiratory + control)
Selected AbstractsDescending respiratory polysynaptic inputs to cervical and thoracic motoneurons diminish during early postnatal maturation in rat spinal cordEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2005Laurent Juvin Abstract Isolated brainstem-spinal cord preparations were used to explore the coexistence of a direct and an indirect descending drive from the brainstem respiratory centre to cervical and thoracic respiratory motoneurons in the neonatal Sprague,Dawley rat. Polysynaptic spinal relay pathways from the respiratory centre were suppressed by selectively perfusing the cord with mephenesin (1 mm) or a solution enriched with Ca2+ and Mg2+. At birth, both direct and spinally relayed pathways are functional and contribute equally to the global descending respiratory drive. However, during the first postnatal week, significant maturational changes appear in the way the respiratory centre controls its target respiratory motoneurons in the cervical and thoracic spinal cord, with the direct respiratory drive becoming progressively predominant with maturation (from 50% to around 75% of the global descending command). The relative contributions of the monosynaptic and the polysynaptic spinal pathways may therefore have important implications for effective respiratory control during early postnatal development. [source] Cardioventilatory Coupling in Resting Human SubjectsEXPERIMENTAL PHYSIOLOGY, Issue 6 2003Y. C. Tzeng In 48 conscious resting subjects we examined the temporal coupling of heart beat timing and the onset of inspiration (cardioventilatory coupling), and the relationship between coupling and spectral indices of autonomic function. Using the proportional Shannon entropy (SH,) of the RI -1 interval (interval between inspiration and the preceding ECG R wave) as a measure of coupling we detected statistically significant coupling in 32 of the 48 subjects. This was confirmed by visual inspection of time series plots of RI intervals, in which coupling was evident as horizontal banding. Coupling resulted in a significant preference for whole number heart rate/respiratory frequency ratios. The strongest coupling was associated with low ventilatory frequency and high heart rate variability in the high (0.15-0.40 Hz) and low (0.04-0.15 Hz) frequency ranges, but was not related to blood pressure variability, or to a spectral measure of baroreflex sensitivity (,-index, low frequency range). There was no difference in coupling strength between males and females. We have previously described cardioventilatory coupling in spontaneously breathing anaesthetised subjects. The current study extends those observations by demonstrating that the qualitative features of coupling seen during anaesthesia are also observed in the conscious state. We conclude that the role of coupling in normal physiological respiratory control needs to be more widely explored. [source] Ethanol Self-Administration and Alterations in the Livers of the Cynomolgus Monkey, Macaca fascicularisALCOHOLISM, Issue 1 2007Priscilla Ivester Background: Most of the studies of alcoholic liver disease use models in which animals undergo involuntary administration of high amounts of ethanol and consume diets that are often high in polyunsaturated fatty acids. The objectives of this study were (1) to evaluate whether cynomolgus monkeys (Macaca fascicularis) drinking ethanol voluntarily and consuming a diet with moderate amounts of lipid would demonstrate any indices of alcoholic liver disease past the fatty liver stage and (2) to determine whether these alterations were accompanied by oxidative stress. Methods: Six adult male and 6 adult female cynomolgus monkeys were allowed to consume ethanol voluntarily for 18 to 19 months. Additional monkeys were maintained on the same consumption protocol, but were not provided with ethanol. During the course of the study, liver biopsy samples were monitored for lipid deposition and inflammation, serum for levels of liver enzymes, and urine for concentrations of the isoprostane (IsoP) metabolite, 2,3-dinor-5,6-dihydro-15-F2t -IsoP, a biomarker for oxidative stress. Liver mitochondria were monitored for respiratory control and liver for concentrations of neutral lipids, adenine nucleotides, esterified F2 isoprostanes, oxidized proteins, 4-hydroxynonenal (HNE)-protein adducts, and protein levels of cytochrome P-450 2E1 and 3A4. Results: Ethanol consumption ranged from 0.9 to 4.05 g/kg/d over the period of the study. Serum levels of aspartate amino transferase were elevated in heavy-consuming animals compared with those in ethanol-naïve or moderate drinkers. Many of the ethanol consumers developed fatty liver and most showed loci of inflammation. Both hepatic energy charge and phosphorylation potential were decreased and NADH-linked respiration was slightly, but significantly depressed in coupled mitochondria as a result of heavy ethanol consumption. The urinary concentrations of 2,3-dinor-5,6-dihydro-15-F2t -IsoP increased as high as 33-fold over that observed in ethanol-abstinent animals. Liver cytochrome P-450 2E1 concentrations increased in ethanol consumers, but there were no ethanol-elicited increases in hepatic concentrations of the esterified F2 isoprostanes, oxidized proteins, or HNE-protein adducts. Conclusion: Our studies show that cynomolgus monkeys undergoing voluntary ethanol consumption for 1.5 years exhibit many of the features observed in the early stages of human alcoholic liver disease. Ethanol-elicited fatty liver, inflammation, and elevated serum aspartate amino transferase were evident with a diet that contained modest amounts of polyunsaturated lipids. The dramatic increases in urinary IsoP demonstrated that the animals were being subjected to significant oxidative stress that correlated with their level of ethanol consumption. [source] Morphine-6-glucuronide: Actions and mechanismsMEDICINAL RESEARCH REVIEWS, Issue 5 2005Gavin J. Kilpatrick Abstract Morphine-6-glucuronide (M6G) appears to show equivalent analgesia to morphine but to have a superior side-effect profile in terms of reduced liability to induce nausea and vomiting and respiratory depression. The purpose of this review is to examine the evidence behind this statement and to identify the possible reasons that may contribute to the profile of M6G. The vast majority of available data supports the notion that both M6G and morphine mediate their effects by activating the µ-opioid receptor. The differences for which there is a reasonable consensus in the literature can be summarized as: (1) Morphine has a slightly higher affinity for the µ-opioid receptor than M6G, (2) M6G shows a slightly higher efficacy at the µ-opioid receptor, (3) M6G has a lower affinity for the ,-opioid receptor than morphine, and (4) M6G has a very different absorption, distribution, metabolism, and excretion (ADME) profile from morphine. However, none of these are adequate alone to explain the clinical differences between M6G and morphine. The ADME differences are perhaps most likely to explain some of the differences but seem unlikely to be the whole story. Further work is required to examine further the profile of M6G, notably whether M6G penetrates differentially to areas of the brain involved in pain and those involved in nausea, vomiting, and respiratory control or whether µ-opioid receptors in these brain areas differ in either their regulation or pharmacology. © 2005 Wiley Periodicals, Inc. Med Res Rev [source] Brainstem respiratory control: Substrates of respiratory failure of multiple system atrophyMOVEMENT DISORDERS, Issue 2 2007Eduardo E. Benarroch MD Abstract Multiple system atrophy may manifest with severe respiratory disorders, including sleep apnea and laryngeal stridor, which reflect a failure of automatic control of respiration. This function depends on a pontomedullary network of interconnected neurons located in the parabrachial/Kölliker Fuse nucleus in the pons, nucleus of the solitary tract, and ventrolateral medulla. Neurons in the preBötzinger complex expressing neurokinin-1 receptors are critically involved in respiratory rhythmogenesis, whereas serotonergic neurons in the medullary raphe and glutamatergic neurons located close to the ventral medullary surface are involved in central chemosensitivity to hypercapnia, hypoxia, or both. Pathological studies using selective neurochemical markers indicate that these neuronal groups are affected in multiple system atrophy. This finding may provide potential anatomical substrates for the respiratory manifestations of the disease. © 2006 Movement Disorder Society [source] Neuromuscular electrical stimulation in neurorehabilitation,MUSCLE AND NERVE, Issue 5 2007Lynne R. Sheffler MD Abstract This review provides a comprehensive overview of the clinical uses of neuromuscular electrical stimulation (NMES) for functional and therapeutic applications in subjects with spinal cord injury or stroke. Functional applications refer to the use of NMES to activate paralyzed muscles in precise sequence and magnitude to directly accomplish functional tasks. In therapeutic applications, NMES may lead to a specific effect that enhances function, but does not directly provide function. The specific neuroprosthetic or "functional" applications reviewed in this article include upper- and lower-limb motor movement for self-care tasks and mobility, respectively, bladder function, and respiratory control. Specific therapeutic applications include motor relearning, reduction of hemiplegic shoulder pain, muscle strengthening, prevention of muscle atrophy, prophylaxis of deep venous thrombosis, improvement of tissue oxygenation and peripheral hemodynamic functioning, and cardiopulmonary conditioning. Perspectives on future developments and clinical applications of NMES are presented. Muscle Nerve, 2007 [source] Home care for chronic respiratory failure in children: 15 years experiencePEDIATRIC ANESTHESIA, Issue 4 2002L. APPIERTO MD Background:,Advances in paediatric intensive care have reduced mortality but, unfortunately, one of the consequences is an increase in the number of patients with chronic diseases. It is generally agreed that home care of children requiring ventilatory support improves their outcomes and results in cost saving for the National Health Service. Methods:,Since 1985, the Children's Hospital Bambino Gesù of Rome has developed a program of paediatric home care. The program is performed by a committed Home Health Care Team (HHCT) which selects the eligible patients for home care and trains the families to treat their child. During the period January 1985 to January 2001, 53 children with chronic respiratory failure were included in the home care program. Of these, seven patients were successively excluded and six died in our intensive care unit (ICU), while one still lives in our ICU since 1997. The results obtained in the remaining 46 children are reported. Results:,The pathologies consisted of disorders of respiratory control related to brain damage (26%), upper airways obstructive disease (26%), spinal muscular atrophy (22%), myopathies and muscular dystrophies (6.5%), bronchopulmonary dysplasia (6.5%), tracheomalacia (6.5%), central hypoventilation syndrome (4.3%) and progressive congenital scoliosis (2.2%). Of these 46 patients, 34 children are mechanically ventilated and the median of their ICU stay was 109.5 days (range 54,214 days), while the remaining 12 children were breathing spontaneously and the median of their ICU stay was 90.5 days (range 61,134 days). We temporarily readmitted six patients to our ICU to perform scheduled otolaryngological surgery, eight patients for acute respiratory infections and two patients for deterioration of their neurological status due to high pressure hydrocephalus for placement of a ventriculoperitoneal shunt; these 16 patients were discharged back home again. Two other patients were readmitted for deterioration of their chronic disease and died in our ICU, while seven patients died at home. Conclusions:,Thirty-seven children are still alive at home and four of them improved their respiratory condition so that it was possible to remove the tracheostomy tube. Our oldest patient has now achieved 15 years of mechanical ventilation at home. [source] Lung-function tests in neonates and infants with chronic lung disease: Tidal breathing and respiratory controlPEDIATRIC PULMONOLOGY, Issue 5 2006BMedSc, David N. Baldwin MBBS Abstract This paper is the fourth in a series of reviews that will summarize available data and critically discuss the potential role of lung-function testing in infants with acute neonatal respiratory disorders and chronic lung disease of infancy. The current paper addresses information derived from tidal breathing measurements within the framework outlined in the introductory paper of this series, with particular reference to how these measurements inform on control of breathing. Infants with acute and chronic respiratory illness demonstrate differences in tidal breathing and its control that are of clinical consequence and can be measured objectively. The increased incidence of significant apnea in preterm infants and infants with chronic lung disease, together with the reportedly increased risk of sudden unexplained death within the latter group, suggests that control of breathing is affected by both maturation and disease. Clinical observations are supported by formal comparison of tidal breathing parameters and control of breathing indices in the research setting. Pediatr Pulmonol. 2006; 41:391,419. © 2006 Wiley-Liss, Inc. [source] Disordered respiratory control in children with partial cerebellar resectionsPEDIATRIC PULMONOLOGY, Issue 1 2005Maida Lynn Chen MD Abstract While the cerebellum is not traditionally thought of as having an important role in respiratory control, breathing involves cyclic motor acts that require cerebellar coordination. We postulate that children with partial cerebellar resections have disordered respiratory control due to altered synchronization of ventilatory muscles. We reviewed the records of 36 children following partial cerebellar resections due to neoplasms confined to the cerebellum. P values were elevated in 19% of patients. Six patients had apneic or bradypneic events documented within the first month after resection. Two patients required intubation with assisted ventilation, and one needed assisted ventilation for 7.3 weeks. Those with apnea had lower oxygen saturations, and a longer need for supplemental oxygen. Patients with apnea were older than those without apnea. Swallowing, which uses many of the same muscles as those needed to maintain upper airway patency, was dysfunctional in 50% of those with apneas. We conclude that children with cerebellar resections have an increased incidence of apnea, hypoventilation, and hypoxemia not otherwise explained by pulmonary disease, and some require prolonged assisted ventilation. We speculate that these abnormalities are manifestations of altered respiratory control caused by dysfunctional cerebellar coordination of ventilatory muscles. © 2005 Wiley-Liss, Inc. [source] Pontine respiratory-modulated activity before and after vagotomy in decerebrate catsTHE JOURNAL OF PHYSIOLOGY, Issue 17 2008Thomas E. Dick The dorsolateral (DL) pons modulates the respiratory pattern. With the prevention of lung inflation during central inspiratory phase (no-inflation (no-I or delayed-I) tests), DL pontine neuronal activity increased the strength and consistency of its respiratory modulation, properties measured statistically by the ,2 value. This increase could result from enhanced respiratory-modulated drive arising from the medulla normally gated by vagal activity. We hypothesized that DL pontine activity during delayed-I tests would be comparable to that following vagotomy. Ensemble recordings of neuronal activity were obtained before and after vagotomy and during delayed-I tests in decerebrate, paralysed and ventilated cats. In general, changes in activity pattern during the delayed-I tests were similar to those after vagotomy, with the exception of firing-rate differences at the inspiratory,expiratory phase transition. Even activity that was respiratory-modulated with the vagi intact became more modulated while withholding lung inflation and following vagotomy. Furthermore, we recorded activity that was excited by lung inflation as well as changes that persisted past the stimulus cycle. Computer simulations of a recurrent inhibitory neural network model account not only for enhanced respiratory modulation with vagotomy but also the varied activities observed with the vagi intact. We conclude that (a) DL pontine neurones receive both vagal-dependent excitatory inputs and central respiratory drive; (b) even though changes in pontine activity are transient, they can persist after no-I tests whether or not changes in the respiratory pattern occur in the subsequent cycles; and (c) models of respiratory control should depict a recurrent inhibitory circuitry, which can act to maintain the stability and provide plasticity to the respiratory pattern. [source] Respiratory complications related to bulbar dysfunction in motor neuron diseaseACTA NEUROLOGICA SCANDINAVICA, Issue 4 2001S. Hadjikoutis Bulbar dysfunction resulting from corticobulbar pathway or brainstem neuron degeneration is one of the most important clinical problems encountered in motor neuron disease (MND) and contributes to various respiratory complications which are major causes of morbidity and mortality. Chronic malnutrition as a consequence of bulbar muscle weakness may have a considerable bearing on respiratory muscle function and survival. Abnormalities of the control and strength of the laryngeal and pharyngeal muscles may cause upper airway obstruction increasing resistance to airflow. Bulbar muscle weakness prevents adequate peak cough flows to clear airway debris. Dysphagia can lead to aspiration of microorganisms, food and liquids and hence pneumonia. MND patients with bulbar involvement commonly display an abnormal respiratory pattern during swallow characterized by inspiration after swallow, prolonged swallow apnoea and multiple swallows per bolus. Volitional respiratory function tests such as forced vital capacity can be inaccurate in patients with bulbofacial weakness and/or impaired volitional respiratory control. Bulbar muscle weakness with abundant secretions may increase the risk of aspiration and make successful non-invasive assisted ventilation more difficult. We conclude that an evaluation of bulbar dysfunction is an essential element in the assessment of respiratory dysfunction in MND. [source] | |||||||||||||