Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 70
Filtrar
1.
Am J Physiol Endocrinol Metab ; 321(1): E24-E46, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-33900849

RESUMO

Prematurity is the leading cause of neonatal morbidity and mortality worldwide. Premature infants often require extended hospital stays, with increased risk of developing infection compared with term infants. A picture is emerging of wide-ranging deleterious consequences resulting from innate immune system activation in the newborn infant. Those who survive infection have been exposed to a stimulus that can impose long-lasting alterations into later life. In this review, we discuss sepsis-driven alterations in integrated neuroendocrine and metabolic pathways and highlight current knowledge gaps in respect of neonatal sepsis. We review established biomarkers for sepsis and extend the discussion to examine emerging findings from human and animal models of neonatal sepsis that propose novel biomarkers for early identification of sepsis. Future research in this area is required to establish a greater understanding of the distinct neonatal signature of early and late-stage infection, to improve diagnosis, curtail inappropriate antibiotic use, and promote precision medicine through a biomarker-guided empirical and adjunctive treatment approach for neonatal sepsis. There is an unmet clinical need to decrease sepsis-induced morbidity in neonates, to limit and prevent adverse consequences in later life and decrease mortality.


Assuntos
Sistema Endócrino , Imunidade Inata/fisiologia , Recém-Nascido Prematuro , Redes e Vias Metabólicas , Sepse Neonatal , Animais , Biomarcadores , Gônadas , Humanos , Hidrocortisona/sangue , Sistema Hipotálamo-Hipofisário , Recém-Nascido , Sistemas Neurossecretores , Sepse , Glândula Tireoide
3.
Oral Dis ; 21(1): e121-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24725067

RESUMO

RATIONALE: Obstructive sleep apnoea syndrome (OSAS) is a debilitating condition characterized by recurrent occlusions of the pharyngeal airway during sleep accompanied by arterial hypoxaemia. Upper airway muscle dysfunction is implicated in the pathophysiology of OSAS. Pharmacological agents that improve muscle contractile and endurance properties may have therapeutic value. AIM: We tested the hypothesis that the ß(2) -adrenoceptor agonist terbutaline improves rat sternohyoid muscle performance especially during hypoxic stress. METHODS: Isometric contractile and endurance properties were examined ex vivo in Krebs solution at 35°C. Muscles were incubated in tissue baths under hyperoxic (95% O(2) /5% CO(2)) conditions in the absence (control) or presence of the ß(2) -adrenoceptor agonist terbutaline (1 µM). In additional experiments under hypoxic (95% N(2) /5% CO(2)) conditions, the effects of terbutaline were examined in the presence of the ß-adrenoceptor antagonist propranolol (1 µM). RESULTS: Hypoxia significantly impaired sternohyoid force production. Terbutaline completely recovered hypoxic depression of force, an effect that was blocked by co-application with propranolol. CONCLUSION: The ß(2) -adrenoceptor agonist terbutaline completely recovers hypoxic depression of upper airway muscle force. ß(2) -adrenoceptor agonists warrant investigation in animal models of OSAS reporting upper airway and diaphragm muscle dysfunction.


Assuntos
Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Hipóxia/fisiopatologia , Músculos Faríngeos/efeitos dos fármacos , Terbutalina/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Masculino , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Músculos Faríngeos/fisiopatologia , Propranolol/farmacologia , Ratos , Ratos Wistar
4.
Oral Dis ; 20(2): 162-70, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23445083

RESUMO

Upper airway (UA) dilator muscles are critical for the maintenance of airway patency. Injury or fatigue to this group of muscles, as observed in patients with obstructive sleep apnoea (OSA) and animal models of OSA, may leave the UA susceptible to collapse. Although the mechanisms underlying respiratory muscle dysfunction are not completely understood, there is strong evidence suggesting a link between increased production of reactive oxygen species and altered muscle function. The aim of this study was to examine the effects of H2O2 on rat sternohyoid muscle function in vitro. Sternohyoid contractile and endurance properties were examined at 35 °C under control or hypoxic conditions. Studies were conducted in the presence of varying concentrations of H2O2 (0, 0.01, 0.1 and 1 mM). Muscle function was also examined in the presence of antioxidants [desferoxamine (DFX), catalase] and the reducing agent dithiothreitol (DTT). H2O2 decreased muscle endurance in a concentration-dependent manner. This was partially reversed by catalase, DFX and DTT. Our results suggest that oxidants may contribute to UA respiratory muscle dysfunction with implications for the control of UA patency in vivo.


Assuntos
Peróxido de Hidrogênio/farmacologia , Músculos do Pescoço/efeitos dos fármacos , Músculos do Pescoço/fisiologia , Animais , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Fadiga Muscular/efeitos dos fármacos , Fadiga Muscular/fisiologia , Ratos , Ratos Wistar
5.
Community Dent Health ; 31(3): 176-82, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25300154

RESUMO

OBJECTIVE: There are significant levels of dental caries in Australian school-aged children, with children aged five years having a mean dmft of 1.3. It has also been identified that, in general, oral health clinicians lack confidence to treat very young children and this study aimed to increase capacity of public sector oral health clinicians to treat preschool children. BASIC RESEARCH DESIGN: An educational program was developed, implemented and evaluated for its capability to increase the confidence and knowledge of oral health clinicians and dental assistants in providing oral care for children aged 12 months to 5 years. RESULTS: In 2011 and 2012, the course was delivered to 36 clinicians (22 dentists, 12 dental therapists, and two oral health therapists) and showed increases in their confidence and knowledge for participants when providing dental procedures to preschool children. CONCLUSIONS: The educational program that was developed and implemented has met its objective of increasing the knowledge and confidence of practicing oral health clinicians and dental assistants in the management of preschool children. Strategies to further enhance the outcomes of this educational program have been proposed.


Assuntos
Fortalecimento Institucional , Assistência Odontológica para Crianças , Educação Continuada em Odontologia , Modelos Educacionais , Pré-Escolar , Competência Clínica , Odontologia Comunitária/educação , Currículo , Assistentes de Odontologia/educação , Auxiliares de Odontologia/educação , Cárie Dentária/prevenção & controle , Relações Dentista-Paciente , Educação Continuada , Humanos , Lactente , Odontopediatria/educação , Desenvolvimento de Programas , Avaliação de Programas e Projetos de Saúde , Setor Público , Encaminhamento e Consulta , Autoimagem , Vitória
7.
Exp Physiol ; 98(9): 1386-400, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23709586

RESUMO

NEW FINDINGS: What is the central question of this study? Co-ordinated activity of the thoracic pump and pharyngeal dilator muscles is critical for maintaining airway calibre and respiratory homeostasis. Whilst postnatal maturation of the diaphragm has been well characterized, surprisingly little is known about the developmental programme in the airway dilator muscles. What is the main finding and its importance? Developmental increases in force-generating capacity and fatigue in the sternohyoid and diaphragm muscles are attributed to a maturational shift in muscle myosin heavy chain phenotype. This maturation is accelerated in the sternohyoid muscle relative to the diaphragm and may have implications for the control of airway calibre in vivo. The striated muscles of breathing, including the thoracic pump and pharyngeal dilator muscles, play a critical role in maintaining respiratory homeostasis. Whilst postnatal maturation of the diaphragm has been well characterized, surprisingly little is known about the developmental programme in airway dilator muscles given that co-ordinated activity of both sets of muscles is needed for the maintenance of airway calibre and effective pulmonary ventilation. The form and function of sternohyoid and diaphragm muscles from Wistar rat pups [postnatal day (PD) 10, 20 and 30] was determined. Isometric contractile and endurance properties were examined in tissue baths containing Krebs solution at 35°C. Myosin heavy chain (MHC) isoform composition was determined using immunofluorescence. Muscle oxidative and glycolytic capacity was assessed by measuring the activities of succinate dehydrogenase and glycerol-3-phosphate dehydrogenase using semi-quantitative histochemistry. Sternohyoid and diaphragm peak isometric force and fatigue increased significantly with postnatal maturation. Developmental myosin disappeared by PD20, whereas MHC2B areal density increased significantly from PD10 to PD30, emerging earlier and to a much greater extent in the sternohyoid muscle. The numerical density of fibres expressing MHC2X and MHC2B increased significantly during development in the sternohyoid. Diaphragm succinate dehydrogenase activity and sternohyoid glycerol-3-phosphate dehydrogenase activity increased significantly with age. Developmental increases in force-generating capacity and fatigue in the sternohyoid and diaphragm muscles are attributed to a postnatal shift in muscle MHC phenotype. The accelerated maturation of the sternohyoid muscle relative to the diaphragm may have implications for the control of airway calibre in vivo.


Assuntos
Envelhecimento/fisiologia , Diafragma/crescimento & desenvolvimento , Cadeias Pesadas de Miosina/metabolismo , Músculos Faríngeos/crescimento & desenvolvimento , Animais , Glicerolfosfato Desidrogenase/metabolismo , Fibras Musculares Esqueléticas/fisiologia , Ratos , Ratos Wistar , Succinato Desidrogenase/metabolismo
8.
Eur Respir J ; 37(6): 1474-81, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21148231

RESUMO

The effects of chronic hypoxia (CH) on respiratory muscle are poorly understood. The aim of the present study was to examine the effects of CH on respiratory muscle structure and function, and to determine whether nitric oxide is implicated in respiratory muscle adaptation to CH. Male Wistar rats were exposed to CH for 1-6 weeks. Sternohyoid and diaphragm muscle contractile properties, muscle fibre type and size, the density of fibres expressing sarco/endoplasmic reticulum calcium-ATPase (SERCA) 2 and sodium-potassium ATPase (Na+,K+-ATPase) pump content were determined. Muscle succinate dehydrogenase (SDH) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) dehydrogenase activities were also assessed. Acute and chronic blockade of nitric oxide synthase (NOS) was employed to determine whether or not NO is critically involved in functional remodelling in CH muscles. CH improved diaphragm, but not sternohyoid, fatigue tolerance in a time-dependent fashion. This adaptation was not attributable to increased SDH or NADPH dehydrogenase activities. The areal density of muscle fibres and relative area of fibres expressing SERCA2 were unchanged. Na+,K+-ATPase pump content was significantly increased in CH diaphragm. Chronic NOS inhibition decreased diaphragm Na+,K+-ATPase pump content and prevented CH-induced increase in muscle endurance. This study provides novel insight into the mechanisms involved in CH-induced muscle plasticity. The results may be of relevance to respiratory disorders characterised by CH, such as chronic obstructive pulmonary disease.


Assuntos
Diafragma/enzimologia , Hipóxia/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Adaptação Fisiológica/fisiologia , Animais , Doença Crônica , Diafragma/efeitos dos fármacos , Diafragma/fisiopatologia , Inibidores Enzimáticos/farmacologia , Hipóxia/fisiopatologia , Masculino , Fadiga Muscular/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , NADPH Desidrogenase/metabolismo , Óxido Nítrico Sintase/antagonistas & inibidores , Nitroarginina/farmacologia , Resistência Física/fisiologia , Ratos , Ratos Wistar , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Succinato Desidrogenase/metabolismo
10.
Adv Exp Med Biol ; 648: 337-44, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19536497

RESUMO

Obstructive sleep apnoea is characterized by chronic intermittent hypoxia (CIH) due to recurrent apnoea. We have developed a rat model of CIH, which shows evidence of impaired respiratory muscle function. In this study, we wished to characterize the ventilatory effects of CIH in conscious male and female animals. Adult male (n=14) and female (n=8) Wistar rats were used. Animals were placed in chambers daily for 8 h with free access to food and water. The gas supply to one half of the chambers alternated between air and nitrogen every 90 s, for 8 h per day, reducing ambient oxygen concentration in the chambers to 5% at the nadir (intermittent hypoxia; n=7 male, n=4 female). Air supplying the other chambers was switched every 90 s to air from a separate source, at the same flow rates, and animals in these chambers served as controls (n=7 male, n=4 female). Ventilatory measurements were made in conscious animals (typically sleeping) after 10 days using whole-body plethysmography. Normoxic ventilation was increased in both male and female CIH-treated rats compared to controls but this did not achieve statistical significance. However, ventilatory drive was increased in CIH-treated rats of both sexes as evidenced by significant increases in mean and peak inspiratory flow. Ventilatory responses to acute hypoxia (F(I)O(2) = 0.10; 6 min) and hyperoxic hypercapnia (F(I)CO(2) = 0.05; 6 min) were unaffected by CIH treatment in male and female rats (P>0.05, ANOVA). We conclude that CIH increases respiratory drive in adult rats. We speculate that this represents a form of neural plasticity that may compensate for respiratory muscle impairment that occurs in this animal model.


Assuntos
Hipóxia/fisiopatologia , Ventilação Pulmonar/fisiologia , Animais , Feminino , Hematócrito , Hipercapnia/fisiopatologia , Masculino , Ratos , Caracteres Sexuais , Fatores de Tempo
11.
J Appl Physiol (1985) ; 105(1): 100-8, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18450982

RESUMO

We undertook the present investigation to establish whether narrowing/closure of the upper airway occurs during spontaneous and provoked respiratory rhythm disturbances and whether pharyngeal constrictor muscle recruitment occurs coincident with upper airway occlusion during prolonged expiratory periods. Upper airway pressure-flow relationships and middle pharyngeal constrictor (mPC) EMG activities were recorded in 11 adult female goats during spontaneous and provoked prolongations in expiratory time (Te). A total of 213 spontaneous prolongations of expiration were recorded. Additionally, 169 prolonged expiratory events preceded by an augmented breath were included in the analyses. In separate trials on different days, Te was prolonged by systemic administration of dopamine, by raising the inspired fraction of O(2) from 0.10 to 1.00 during poikilocapnic conditions or by systemic administration of clonidine. Continuous tonic activation of the mPC EMG was observed during each prolonged Te period regardless of the duration or initiating cause. However, significant increases in subglottic tracheal pressure, with expiratory airflow braking indicative of upper airway narrowing or closure, was only observed during spontaneous events without a preceding augmented breath and during clonidine-induced events. Tonic mPC activation proved an unreliable indicator of airway occlusion. Furthermore, mPC muscle activation alone is not sufficient to induce pharyngeal occlusion during prolonged expiration. Our data suggest that airway closure is not a common occurrence during provoked respiratory disturbances in awake goats. We propose that airway closure, when present during prolonged Te, is more likely dependent on activation of laryngeal adductor muscles with glottic braking independent of pharyngeal narrowing.


Assuntos
Cabras/fisiologia , Músculos Faríngeos/fisiologia , Mecânica Respiratória/fisiologia , Agonistas alfa-Adrenérgicos/farmacologia , Pressão do Ar , Animais , Gasometria , Clonidina/farmacologia , Dopamina/farmacologia , Eletrodos Implantados , Eletromiografia , Feminino , Glote/fisiologia , Hipocapnia/fisiopatologia , Contração Muscular/fisiologia , Músculos Faríngeos/efeitos dos fármacos , Músculos Faríngeos/inervação , Mecânica Respiratória/efeitos dos fármacos , Vigília/fisiologia
12.
Physiol Res ; 65(5): 843-851, 2016 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-27429123

RESUMO

Given that sex differences inherent to muscle might at least contribute to male risk for obstructive sleep apnoea syndrome (OSAS), our objective was to test the hypothesis that male sternohyoid muscle exhibits greater susceptibility to severe hypoxic stress compared with female muscle. Adult male and female C57Bl6/J mouse sternohyoid isometric and isotonic functional properties were examined ex vivo at 35 °C in tissue baths under control and severe hypoxic conditions. Hypoxia was detrimental to peak force (Fmax), work (Wmax) and power (Pmax), but not shortening velocity (Vmax). Two-way analysis of variance revealed a significant sex x gas interaction for Fmax (p<0.05), revealing inferior hypoxic tolerance in male sternohyoid muscle. However, increases in male shortening velocity in severe hypoxia preserved power-generating capacity which was equivalent to values determined in female muscle. Fmax decline in hypoxic female sternohyoid was considerably less than in male muscle, illustrating an inherent tolerance of force-generating capacity mechanisms to hypoxic stress in female airway dilator muscle. We speculate that this could confer a distinct advantage in vivo in terms of the defense of upper airway caliber.


Assuntos
Hipóxia/fisiopatologia , Músculos do Pescoço/fisiopatologia , Caracteres Sexuais , Animais , Feminino , Contração Isotônica , Masculino , Camundongos Endogâmicos C57BL , Fadiga Muscular
13.
Neurogastroenterol Motil ; 28(7): 1016-26, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26920808

RESUMO

BACKGROUND: Duchenne muscular dystrophy (DMD) is a fatal disease characterized by progressive deterioration and degeneration of striated muscle. A mutation resulting in the loss of dystrophin, a structural protein which protects cells from contraction-induced damage, underlies DMD pathophysiology. Damage to muscle fibers results in chronic inflammation and elevated levels of proinflammatory cytokines such as interleukin-6 (IL-6). However, loss of cellular dystrophin also affects neurons and smooth muscle in the gastrointestinal (GI) tract with complaints such as hypomotility, pseudo-obstruction, and constipation reported in DMD patients. METHODS: Using dystrophin-deficient mdx mice, studies were carried out to examine colonic morphology and function compared with wild-type mice. Treatment with neutralizing IL-6 receptor antibodies (xIL-6R) and/or the corticotropin-releasing factor (CRF) 2 receptor agonist, urocortin 2 (uro2) was tested to determine if they ameliorated GI dysfunction in mdx mice. KEY RESULTS: Mdx mice exhibited thickening of colonic smooth muscle layers and delayed stress-induced defecation. In organ bath studies, neurally mediated IL-6-evoked contractions were larger in mdx colons. In vivo treatment of mdx mice with xIL-6R normalized defecation rates and colon lengths. Uro2 treatment did not affect motility or morphology. The potentiated colonic contractile response to IL-6 was attenuated by treatment with xIL-6R. CONCLUSIONS & INFERENCES: These findings confirm the importance of dystrophin in normal GI function and implicate IL-6 as an important regulator of GI motility in the mdx mouse. Inhibition of IL-6 signaling may offer a potential new therapeutic strategy for treating DMD-associated GI symptoms.


Assuntos
Anticorpos Neutralizantes/farmacologia , Distrofina/deficiência , Gastroenteropatias/metabolismo , Receptores de Interleucina-6/antagonistas & inibidores , Receptores de Interleucina-6/metabolismo , Animais , Colo/efeitos dos fármacos , Colo/metabolismo , Gastroenteropatias/fisiopatologia , Motilidade Gastrointestinal/efeitos dos fármacos , Motilidade Gastrointestinal/fisiologia , Interleucina-6/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos mdx , Técnicas de Cultura de Órgãos
14.
J Appl Physiol (1985) ; 85(3): 946-54, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9729568

RESUMO

We examined the ventilatory effects of exogenous dopamine (DA) and norepinephrine (NE) administration in chloralose-anesthetized, paralyzed, artificially ventilated adult goats before and after carotid body denervation (CBD). Intravenous (iv) DA bolus injections and slow iv infusions caused dose-dependent inhibition of phrenic nerve activity (PNA) in carotid body (CB)-intact animals during normoxia and hyperoxia but not during hypercapnia. NE administration in CB-intact goats caused dose-dependent inhibition of PNA of similar magnitude to DA trials. The DA D2-receptor agonists quinelorane and quinpirole inhibited PNA, whereas the DA D1-receptor agonist SKF-81297 had no effect. After CBD, the ventilatory depressant effects of DA persisted, but responses were significantly attenuated compared with CB-intact trials. CBD abolished the inhibitory effect of low-dose NE administration but did not alter ventilatory responses to high-dose NE injection. The peripheral DA D2-receptor antagonist domperidone substantially attenuated the inhibitory effects of DA bolus injections and infusions and reversed the inhibitory ventilatory effect of high-dose DA administration to excitation in some animals. The alpha-adrenoceptor antagonist phentolamine had no effect on DA-induced ventilatory depression. Beta-Adrenoceptor stimulation with isoproterenol produced similar hemodynamic effects to DA administration but had no effect on PNA. We conclude that DA and NE exert both CB-mediated and non-CB-mediated inhibitory effects on respiratory motor output in anesthetized goats. The ventilatory depressant effects that persist in peripherally chemodenervated animals are DA D2-receptor mediated, but their exact location remains speculative.


Assuntos
Dopamina/fisiologia , Sistema Nervoso Periférico/fisiologia , Músculos Respiratórios/fisiologia , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Corpo Carotídeo/fisiologia , Dopamina/farmacologia , Agonistas de Dopamina/farmacologia , Feminino , Cabras , Hemodinâmica/fisiologia , Hipercapnia/fisiopatologia , Masculino , Denervação Muscular , Fentolamina/farmacologia , Mecânica Respiratória/fisiologia
15.
J Appl Physiol (1985) ; 87(2): 590-7, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10444617

RESUMO

The purpose of this study was to determine the extent to which alpha(2)-adrenoceptor (alpha(2)-AR) pathways affect the central motor output to upper airway muscles that regulate airflow. Electromyogram (EMG) measurements were made from posterior cricoarytenoid (PCA), cricothyroid (CT), thyroarytenoid (TA), and middle (MPC) and inferior (IPC) pharyngeal constrictor muscles in awake standing goats. Systemic administration of the alpha(2)-AR agonist clonidine induced a highly dysrhythmic pattern of ventilation in all animals that was characterized by alternating episodes of tachypnea and slow irregular breathing patterns, including prolonged and variable expiratory time intervals. Periods of apnea were commonly observed. Dysrhythmic ventilatory patterns induced by clonidine were associated with differential recruitment of upper airway muscles. alpha(2)-AR stimulation preferentially decreased the activity of the PCA, CT, and IPC muscles while increasing TA and MPC EMG activities. Clonidine-induced apneas were associated with continuous tonic activation of laryngeal (TA) and pharyngeal (MPC) adductors, leading to airway closure and arterial oxygen desaturation. Tonic activation of the TA and MPC muscles was interrupted only during the first inspiratory efforts after central apnea. Laryngeal abductor, diaphragm, and transversus abdominis EMG activities were completely silenced during apneic events. Ventilatory and EMG effects were reversed by selective alpha(2)-AR blockade with SKF-86466. The results demonstrate that alpha(2)-AR pathways are important modulators of central respiratory motor outputs to the upper airway muscles.


Assuntos
Clonidina/farmacologia , Respiração/efeitos dos fármacos , Agonistas de Receptores Adrenérgicos alfa 2 , Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Apneia/induzido quimicamente , Benzazepinas/farmacologia , Eletromiografia , Feminino , Cabras , Músculos Laríngeos/efeitos dos fármacos , Medidas de Volume Pulmonar , Masculino , Músculos Faríngeos/efeitos dos fármacos
16.
Brain Res ; 759(2): 233-40, 1997 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-9221942

RESUMO

The effects of partial division of the great auricular nerve of adult rabbits were evaluated on the responsiveness of cutaneous C-fiber polymodal nociceptors (CPMs) to sympathetic stimulation (SS), close-arterial injections of epinephrine (EPI) and other alpha-adrenergic agonists. In normal unanesthetized rabbits, the two ears were usually at the same temperature. Two to 4 weeks after partial nerve lesions, however, the operated ear was cooler by 1-3 degrees C in the majority of animals, suggestive of increased vasoconstriction and possible denervation supersensitivity. Neither SS nor EPI (50 ng) excited CPM units (n = 23) from intact anesthetized animals. In contrast, 14-27 days after partial nerve lesions, SS (8 out of 38 units) and EPI (12 out of 38 units) were excitatory for a class of CPMs. There was notable variability in the response of different units and of a given unit between first and second trials. Responses consisted of 1-22 impulses for SS and 1-23 impulses for EPI in the 60 s following a trial. Arterial occlusion did not activate responsive units, suggesting that the excitation was not caused by vascular or temperature changes. Selective alpha2-adrenoceptor blockade with yohimbine (0.6-1.0 mg/kg i.v.) or rauwolscine (1.0 mg/kg i.v.) reversibly antagonized the effects of SS and EPI. EPI-responsive units were also excited by norepinephrine (50 ng) and guanabenz (10 microg) but not by clonidine (3 microg) or B-HT 933 (3 microg). The results suggest that circulating EPI, acting via an alpha-adrenoceptor subtype, can play a part in the development and/or maintenance of aberrant pain syndromes such as causalgia and other sympathetically related dystrophies.


Assuntos
Epinefrina/farmacologia , Fibras Nervosas/efeitos dos fármacos , Nociceptores/efeitos dos fármacos , Sistema Nervoso Simpático/lesões , Animais , Feminino , Masculino , Fibras Nervosas/fisiologia , Coelhos
17.
Eur J Pharmacol ; 218(2-3): 229-36, 1992 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-1330594

RESUMO

The 5-HT3 receptor antagonists zacopride and GR38032F are highly effective inhibitors of emesis induced by ionizing radiation and chemotherapeutic drugs such as cisplatin. The present study evaluated zacopride and GR38032F for efficacy in inhibiting the formation of the conditioned taste aversion (CTA) induced by cisplatin or lithium chloride in rats. The glucocorticoid dexamethasone, which has been reported to be effective against both the emetic and CTA-inducing effects of cisplatin, was included as a reference compound. When administered alone by i.p. injection, zacopride (0.1-10 mg/kg), GR38032F (10 mg/kg) and cisplatin (0.32-1.8 mg/kg) induced a CTA to an 0.1% saccharin solution; lower doses of each compound were ineffective. When administered as a pretreatment, neither zacopride (0.001-0.1 mg/kg) nor GR38032F (0.01-10 mg/kg) attenuated the CTA induced by cisplatin (0.32 and 0.56 mg/kg) or lithium chloride (10 mg/kg). In contrast, dexamethasone (0.32 and 1.0 mg/kg) attenuated the CTA induced by 0.32 but not 0.56 mg/kg of cisplatin. In an attempt to evaluate higher doses of zacopride against cisplatin without the potentially confounding factor that these doses by themselves induce a CTA, rats were injected with zacopride on three separate days prior to the aversion conditioning session. This pre-exposure treatment blocked the formation of the zacopride-induced CTA, but did not improve the efficacy of zacopride in attenuating the cisplatin-induced CTA. These results suggest that neither the cisplatin- nor the lithium-induced CTA in rats are due to effects that are sensitive to 5-HT3 receptor blockade.


Assuntos
Antieméticos/uso terapêutico , Benzamidas/uso terapêutico , Compostos Bicíclicos Heterocíclicos com Pontes , Compostos Bicíclicos com Pontes/uso terapêutico , Cisplatino/antagonistas & inibidores , Ondansetron/uso terapêutico , Antagonistas da Serotonina/uso terapêutico , Análise de Variância , Animais , Cloretos/antagonistas & inibidores , Dexametasona/uso terapêutico , Relação Dose-Resposta a Droga , Lítio/antagonistas & inibidores , Cloreto de Lítio , Masculino , Ratos , Ratos Endogâmicos , Distúrbios do Paladar/induzido quimicamente , Distúrbios do Paladar/prevenção & controle
18.
Respir Physiol Neurobiol ; 138(2-3): 301-8, 2003 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-14609518

RESUMO

Obstructive sleep apnoea (OSA) is a major clinical disorder that is characterised by multiple episodes of upper airway obstruction due to failure of the upper airway dilator muscles to maintain upper airway patency. The incidence of OSA is high in many endocrine disorders including both insulin-dependent and non-insulin-dependent diabetes but the reasons for this are not known. We wished to test the hypothesis that central respiratory motor output to the upper airway muscles is preferentially impaired in a rat model of diabetes mellitus. Sternohyoid (SH) and diaphragm (DIA) EMG activities were recorded in control and streptozotocin (STZ)-induced diabetic rats during normoxia, hypoxia (7.5% O2 in N2) and asphyxia (7.5% O2 and 3% CO2) under pentobarbitone anaesthesia. SH EMG responses to acute hypoxia and asphyxia were significantly impaired in STZ-induced diabetic rats compared to control animals (+47.1 +/- 5.7 vs. +11.7 +/- 1.9% during hypoxia in control and diabetic animals respectively and +56.5 +/- 7.9 vs. +15.7 +/- 5.0% during asphyxia). However, DIA EMG responses to hypoxia and asphyxia were not different for the two groups. We propose that the higher prevalence of OSA in diabetic patients is related to preferential impairment of cranial motor output to the dilator muscles of the upper airway in response to physiological stimuli.


Assuntos
Asfixia/fisiopatologia , Diabetes Mellitus Experimental/fisiopatologia , Eletromiografia , Hipóxia/fisiopatologia , Análise de Variância , Animais , Asfixia/etiologia , Asfixia/veterinária , Glicemia , Peso Corporal , Diabetes Mellitus Experimental/induzido quimicamente , Diafragma/fisiopatologia , Modelos Animais de Doenças , Hipóxia/complicações , Hipóxia/veterinária , Masculino , Ratos , Ratos Wistar , Músculos Respiratórios/fisiopatologia , Estreptozocina , Fatores de Tempo
19.
Eur J Cardiothorac Surg ; 5(2): 82-92; discussion 93, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-2018659

RESUMO

Patients with a recent myocardial infarction have a higher morbidity and mortality than comparable patients with chronic myocardial ischaemia. We postulated that this might be due to a reduced overall tolerance of the heart to cardioplegic arrest in the presence of a recent infarct. We postulated that orotic acid, a pyrimidine precursor which augments the rate of protein synthesis, might improve the response of the recently infarcted heart to cardioplegic arrest. Myocardial infarction was produced in rats by coronary ligation. The rats were then divided into two groups according to whether they were treated with oral orotic acid (10 mg/kg per day) or untreated. A sham-operated (non-infarcted) group served as normal controls. After 2 days, the hearts (n = 12 per group) underwent 1 h of cardioplegic arrest at 23 degrees C on the isolated working heart apparatus. Before arrest, maximum cardiac function in the untreated infarct group was lower than in the normal group (P less than 0.05), whereas in the treated group, function was similar to the normal group. After arrest there was severe depression of cardiac function in the untreated infarct group: only 57% recovery of the pre-arrest value compared with 86% in the normal group (P less than 0.001). In the orotic acid treated group, recovery (90%) was significantly greater than in the untreated group (P less than 0.001) and equivalent to the normal group. Oxygen utilisation, when corrected for external work, was higher in both infarct groups than in the normal group before and after arrest (P less than 0.05 in both cases). Total uridine nucleotide content of the infarcted and non-infarcted zones of the heart was increased. Treatment with orotic acid produced a further upward trend in uridine nucleotide levels. We conclude that an established, recent infarct reduces the overall tolerance of the heart to hypothermic cardioplegia. Treatment with orotic acid improves the function of the infarcted heart following cardioplegic arrest, and may therefore improve the results of urgent cardiac surgery in patients with myocardial infarction.


Assuntos
Parada Cardíaca Induzida , Infarto do Miocárdio/fisiopatologia , Ácido Orótico/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Débito Cardíaco/efeitos dos fármacos , Débito Cardíaco/fisiologia , Coração/efeitos dos fármacos , Coração/fisiopatologia , Isquemia/fisiopatologia , Masculino , Infarto do Miocárdio/patologia , Miocárdio/química , Miocárdio/metabolismo , Ácido Orótico/administração & dosagem , Consumo de Oxigênio/efeitos dos fármacos , Consumo de Oxigênio/fisiologia , Ratos , Ratos Endogâmicos , Nucleotídeos de Uracila/análise
20.
Am J Sports Med ; 24(4): 472-6, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8827306

RESUMO

We evaluated the comparability of four commonly used shoulder scoring systems in the United States. Fifty-two patients had 53 shoulder stabilization procedures. Surgical procedures included 34 open Bankart-type repairs, 15 capsular shifts, and 4 arthroscopic stabilizations. Results were assessed using the following scales: 1) Rowe, 2) modified-Rowe, 3) University of California at Los Angeles, and 4) the pre-1994 American Shoulder and Elbow Surgeons scale. No consensus has been reached on the relative value of these systems. We observed significant variations using these systems. A majority of our patients (85%) had excellent results when the University of California at Los Angeles scoring system was used. However, only 38% of the patients had excellent results when the modified-Rowe scale was used. Overall, good or excellent results were observed in 89% to 95% of the patients using these four scoring systems. The University of California at Los Angeles score correlated poorly with the other systems. Interrater reliability between the four systems was poor. Generalized results of an investigation can be biased based on the selection of a scoring system. The lack of a widely accepted scoring system for the shoulder limits comparison of management for shoulder conditions. Thus, a widely accepted shoulder scoring system is needed.


Assuntos
Instabilidade Articular/epidemiologia , Instabilidade Articular/cirurgia , Articulação do Ombro , Índices de Gravidade do Trauma , Adolescente , Adulto , Artroscopia , Endoscopia , Estudos de Avaliação como Assunto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA