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91.
We have recorded extracellular, inspiratory-related (IR) unit activity in the medulla at locations corresponding to those of neurons retrogradely labeled by injections of retrograde tracers in the lower brachial and upper thoracic spinal cord, injections that covered cell bodies and dendrites of motoneurons innervating inspiratory muscles. Bulbospinal neurons were distributed throughout the dorsomedial and ventrolateral medulla, from the spinomedullary junction through about 0.8 mm rostral to the obex. Almost all of the 104 IR units recorded were located in corresponding parts of the ventrolateral medulla, rostral to nucleus retroambigualis, where expiratory related units are found. Injections of biotinylated dextran amine at the recording sites labeled projections both to the spinal cord and to the brainstem. In the lower brachial and upper thoracic spinal cord, bulbospinal axons traveled predominantly in the contralateral dorsolateral funiculus and terminated in close relation to the dendrites of inspiratory motoneurons retrogradely labeled with cholera toxin B-chain. In the brainstem, there were predominantly ipsilateral projections to the nucleus retroambigualis, tracheosyringeal motor nucleus (XIIts), ventrolateral nucleus of the rostral medulla, infraolivary superior nucleus, ventrolateral parabrachial nucleus, and dorsomedial nucleus of the intercollicular complex. In all these nuclei, except XIIts, retrogradely labeled neurons were also found, indicating reciprocity of the connections. These results suggest the possibility of monosynaptic connections between inspiratory premotor neurons and inspiratory motoneurons, which, together with connections of IR neurons with other brainstem respiratory-vocal nuclei, seem likely to mediate the close coordination that exists in birds between the vocal and respiratory systems. The distribution of IR neurons in birds is similar to that of the rostral ventral respiratory group (rVRG) in mammals. 相似文献
92.
S Merino A Aguilar JM Tomás R Bonet MJ Martinez D Simón-Pujol F Congregado 《Canadian Metallurgical Quarterly》1997,22(5):315-320
1. We investigated the effect of exercise on plasma adrenomedullin, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations and studied the relationship between these peptides and haemodynamic parameters in nine patients with old myocardial infarction (MI) and in eight normal subjects. 2. The exercise protocol consisted of two fixed work loads (40 and 80 W) for 4 min each and venous blood samples were taken at rest, during each exercise stage and after exercise while monitoring the mean arterial pressure (MAP) and heart rate (HR). In MI, pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure (PCWP), left ventricular end-diastolic pressure (LVEDP) and cardiac output (CO) were measured throughout exercise. 3. Adrenomedullin levels did not significantly increase with exercise. Adrenomedullin levels correlated with PAP and PCWP at rest (P < 0.05). Atrial natriuretic peptide levels correlated with PAP, PCWP and LVEDP throughout exercise (P < 0.05) but, on multiple regression analysis, PCWP correlated only with ANP (P < 0.01). Brain natriuretic peptide levels correlated with LVEDP throughout exercise (P < 0.01) and its increment correlated closely with basal BNP levels at rest (P < 0.01). 4. These results suggest that adrenomedullin does not respond to the acute haemodynamic changes of exercise, whereas ANP responds to it and PCWP is the major stimulus factor. Brain natriuretic peptide responds to exercise in proportion to the basal synthesis of BNP in patients with left ventricular dysfunction and LVEDP may play a role in increasing BNP during exercise. 相似文献
93.
JM Magarey 《Canadian Metallurgical Quarterly》1997,10(3):90-93
Pain management presents exciting opportunities for nurse anesthetists. Today there are thousands of pain clinics and pain services dedicated to the diagnosis and treatment of chronic and acute pain. By becoming familiar with the principles involved in the management of chronic and acute pain, the different treatment modalities available, and the organization of pain clinics and pain services, nurse anesthetists will be able to take advantage of the opportunities they provide. 相似文献
94.
The author considers the shifts produced by mode filters on curved boundaries and contours. It is shown that these are similar to those produced by mean and median filters, the cases of linear intensity variations and of step edges being somewhat different and at opposite extremes of a continuum. Thus, shifts are intrinsic to basic neighbourhood averaging techniques, and can be avoided only by specially designed operators 相似文献
95.
Cdc7 kinase is essential for initiation of DNA replication. Cdc7(-/-) mouse embryonic stem (ES) cells are non-viable but their growth can be rescued by an ectopically expressed transgene (Cdc7(-/-)tg). Here we report that, despite the normal growth capability of Cdc7(-/-)tg ES cells, the mice with the identical genetic background exhibit growth retardation. Concomi tantly, Cdc7(-/-)tg embryonic fibroblasts (MEFs) display delayed S phase entry and slow S phase progression. Furthermore, spermatogenesis of Cdc7(-/-)tg mice is disrupted prior to pachytene stage of meiotic prophase I. The impairment in spermatogenesis correlates with the extremely low level of Cdc7 protein in testes, and is rescued by introducing an additional allele of transgene, which results in increase of Cdc7 expression. The increased level of Cdc7 also recovers the growth of Cdc7(-/-)tg MEFs and mice, indicating that the developmental abnormalities of Cdc7(-/-)tg mice are due to insufficiency of Cdc7 protein. Our results indicate the requirement of a critical level of a cell-cycle regulator for mouse development and provide genetic evidence that Cdc7 plays essential roles in meiotic processes in mammals. 相似文献
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99.
A dyeing profile for a range of reactive dyes suitable for application to cellulosic knitwear is defined. Such a profile shows good level-dyeing, reproducibility and fastness properties together with potential for simplified dyeing processes. 相似文献
100.
JM Robbins 《Canadian Metallurgical Quarterly》1989,40(4):2128-2136