RESUMEN
BACKGROUND: Temperature-controlled radiofrequency (TCRF) device treatment of nasal valve dysfunction (NVD) was superior to a sham procedure control in reducing the symptoms of nasal airway obstruction (NAO) in this randomised controlled trial (RCT). METHODOLOGY: Two-year outcomes for 108 patients actively treated in a prospective, multicenter, patient-blinded RCT were used to determine treatment effect durability and changes in medication/nasal dilator usage. A responder was defined as ≥ 20 reduction in NOSE score or 1 reduction in severity class. RESULTS: The mean (SD) age of patients was 48.5 (12.3) years; 66 (61.1%) women. Baseline NOSE score was 76.3. The 2-year responder rate was 90.4% and NOSE score treatment effect was -41.7; 54.7% improvement. Of 57 patients using medications/nasal dilators at baseline, 45 (78.9%) either stopped all use (33.3%) or stopped/decreased (45.6%) use in >=1 class at 2 years. Concurrent septal deviation, septal swell body, or turbinate enlargement did not significantly affect the odds of exhibiting a NOSE score of ≤ 25 at 2 years. CONCLUSIONS: TCRF device treatment of NVD resulted in significant and sustained improvements in the symptoms of NAO at 2 years, accompanied by a substantial reduction in medication/nasal dilator use.
Asunto(s)
Obstrucción Nasal , Humanos , Obstrucción Nasal/cirugía , Femenino , Persona de Mediana Edad , Masculino , Estudios Prospectivos , Resultado del Tratamiento , Adulto , Terapia por Radiofrecuencia/métodosRESUMEN
There are widespread chemosensitive areas in the brain with varying effects on breathing. In the awake goat, microdialyzing (MD) 50% CO(2) at multiple sites within the medullary raphe increases pulmonary ventilation (Vi), blood pressure, heart rate, and metabolic rate (Vo(2)) (11), while MD in the rostral and caudal cerebellar fastigial nucleus has a stimulating and depressant effect, respectively, on these variables (17). In the anesthetized cat, the pre-Bötzinger complex (preBötzC), a hypothesized respiratory rhythm generator, increases phrenic nerve activity after an acetazolamide-induced acidosis (31, 32). To gain insight into the effects of focal acidosis (FA) within the preBötzC during physiological conditions, we tested the hypothesis that FA in the preBötzC during wakefulness would stimulate breathing, by increasing respiratory frequency (f). Microtubules were bilaterally implanted into the preBötzC of 10 goats. Unilateral MD of mock cerebral spinal fluid equilibrated with 6.4% CO(2) did not affect Vi, tidal volume (Vt), or f. Unilateral MD of 25 and 50% CO(2) significantly increased Vi and f by 10% (P < 0.05, n = 10, 17 trials), but Vt was unaffected. Bilateral MD of 6.4, 25, or 50% CO(2) did not significantly affect Vi, Vt, or f (P > 0.05, n = 6, 6 trials). MD of 80% CO(2) caused a 180% increase in f and severe disruptions in airflow (n = 2). MD of any level of CO(2) did not result in any significant changes in mean arterial blood pressure, heart rate, or Vo(2). Thus the data suggest that the preBötzC area is chemosensitive, but the responses to FA at this site are unique compared with other chemosensitive sites.
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Acidosis/fisiopatología , Células Quimiorreceptoras/metabolismo , Hipercapnia/fisiopatología , Ventilación Pulmonar , Centro Respiratorio/fisiopatología , Mecánica Respiratoria , Vigilia , Acidosis/inducido químicamente , Acidosis/metabolismo , Animales , Dióxido de Carbono , Modelos Animales de Enfermedad , Cabras , Concentración de Iones de Hidrógeno , Hipercapnia/inducido químicamente , Hipercapnia/metabolismo , Microdiálisis , Centro Respiratorio/metabolismo , Volumen de Ventilación Pulmonar , Factores de TiempoRESUMEN
Abrupt neurotoxic destruction of >70% of the pre-Bötzinger complex (preBötzC) in awake goats results in respiratory and cardiac failure (Wenninger JM, Pan LG, Klum L, Leekley T, Bastastic J, Hodges MR, Feroah TR, Davis S, Forster HV. J Appl Physiol 97: 1629-1636, 2004). However, in reduced preparations, rhythmic respiratory activity has been found in other areas of the brain stem (Huang Q, St. John WM. J Appl Physiol 64: 1405-1411, 1988; Janczewski WA, Feldman JL. J Physiol 570: 407-420, 2006; Lieske SP, Thoby-Brisson M, Telgkamo P, Ramierz JM. Nature Neurosci 3: 600-607, 2000; St. John WM, Bledsoe TA. J Appl Physiol 59: 684-690, 1985); thus we hypothesized that, when the preBötzC is destroyed incrementally over weeks, time-dependent plasticity within the respiratory network will result in a respiratory rhythm capable of maintaining normal blood gases. Microtubules were bilaterally implanted into the presumed preBötzC of seven goats. After recovery from surgery, studies were completed to establish baseline values for respiratory parameters. At weekly intervals, increasing volumes (in order 0.5, 1, 5, and 10 microl) of ibotenic acid (IA; 50 mM) were then injected into the preBötzC. All IA injections resulted in an acute tachypnea and dysrhythmia featuring augmented breaths, apneas, and increased breath-to-breath variation in breathing. In studies at night, apneas were nearly all central and occurred in the awake state. Breath-to-breath variation in breathing was greater (P < 0.05) during wakefulness than during non-rapid eye movement sleep. However, one week after the final IA injection, the breathing pattern, breath-to-breath variation, and arterial blood gases and pH were unchanged from baseline, but there was a 20% decrease in respiratory frequency (f) and CO(2) sensitivity (P < 0.05), as well as a 40% decrease in the ventilatory response to hypoxia (P < 0.001). In subsequent histological analysis of the presumed preBötzC region of lesioned goats, it was determined that there was a 90 and 92% reduction from control goats in total and neurokinin-1 receptor neurons, respectively. Therefore, it was concluded that 1) the dysrhythmic effects on breathing are state dependent; and 2) after incremental, near total destruction of the presumed preBötzC region, time-dependent plasticity within the respiratory network provides a rhythm capable of sustaining normal arterial blood gases.
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Dióxido de Carbono/sangre , Degeneración Nerviosa/fisiopatología , Plasticidad Neuronal , Oxígeno/sangre , Centro Respiratorio/fisiopatología , Mecánica Respiratoria , Sueño , Vigilia , Adaptación Fisiológica , Animales , Presión Sanguínea , Agonistas de Aminoácidos Excitadores/administración & dosificación , Femenino , Cabras , Concentración de Iones de Hidrógeno , Ácido Iboténico/administración & dosificación , Inyecciones , Modelos Animales , Degeneración Nerviosa/inducido químicamente , Degeneración Nerviosa/patología , Periodicidad , Ventilación Pulmonar , Centro Respiratorio/efectos de los fármacos , Centro Respiratorio/patología , Factores de TiempoRESUMEN
Ventilatory sensitivity to CO(2) in awake adult Brown Norway (BN) rats is 50-75% lower than in adult Sprague-Dawley (SD) and salt-sensitive Dahl S (SS) rats. The purpose of the present study was to test the hypothesis that this difference would be apparent during the development of CO(2) sensitivity. Four litters of each strain were divided into four groups such that rats were exposed to 7% inspired CO(2) for 5 min in a plethysmograph every third day from postnatal day (P) 0 to P21 and again on P29 and P30. From P0 to P14, CO(2) exposure increased pulmonary ventilation (Ve) by 25-50% in the BN and SD strains and between 25 to over 200% in the SS strain. In all strains beginning around P15, the response to CO(2) increased progressively reaching a peak at P19-21 when Ve during hypercapnia was 175-225% above eucapnia. There were minimal changes in CO(2) sensitivity between P21 and P30, and at both ages there were minimal between-strain differences. At P30, the response to CO(2) in the SS and SD strains was near the adult response, but the response in the BN rats was 100% greater at P30 than in adults. We conclude that 1) CO(2)-sensing mechanisms, and/or mechanisms downstream from the chemoreceptors, change dramatically at the age in rats when other physiological systems are also maturing ( approximately P15), and 2) there is a high degree of age-dependent plasticity in CO(2) sensitivity in rats, which differs between strains.
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Dióxido de Carbono/farmacología , Hipercapnia/inducido químicamente , Ventilación Pulmonar/efectos de los fármacos , Sistema Respiratorio/efectos de los fármacos , Administración por Inhalación , Animales , Animales Recién Nacidos , Animales no Consanguíneos , Dióxido de Carbono/administración & dosificación , Hipercapnia/fisiopatología , Pletismografía Total , Ventilación Pulmonar/fisiología , Ratas , Ratas Endogámicas BN , Ratas Endogámicas Dahl , Ratas Endogámicas/fisiología , Ratas Sprague-Dawley , Sistema Respiratorio/crecimiento & desarrollo , Especificidad de la EspecieRESUMEN
OBJECTIVE: Patient portals are online applications that allow patients to interact with healthcare organizations. Portal adoption is increasing, and secure messaging between patients and healthcare providers is an emerging form of outpatient interaction. Research about portals and messaging has focused on medical specialties. We characterized adoption of secure messaging and the contribution of messaging to outpatient interactions across diverse clinical specialties after broad portal deployment. METHODS: This retrospective cohort study at Vanderbilt University Medical Center examined use of patient-initiated secure messages and clinic visits in the three years following full deployment of a patient portal across adult and pediatric specialties. We measured the proportion of outpatient interactions (i.e., messages plus clinic visits) conducted through secure messaging by specialty over time. Generalized estimating equations measured the likelihood of message-based versus clinic outpatient interaction across clinical specialties. RESULTS: Over the study period, 2,422,114 clinic visits occurred, and 82,159 unique portal users initiated 948,428 messages to 1,924 recipients. Medicine participated in the most message exchanges (742,454 messages; 78.3% of all messages sent), followed by surgery (84,001; 8.9%) and obstetrics/gynecology (53,424; 5.6%). The proportion of outpatient interaction through messaging increased from 12.9% in 2008 to 33.0% in 2009 and 39.8% in 2010 (p<0.001). Medicine had the highest proportion of outpatient interaction conducted through messaging in 2008 (23.3% of outpatient interactions in medicine). By 2010, this proportion was highest for obstetrics/gynecology (83.4%), dermatology (71.6%), and medicine (56.7%). Growth in likelihood of message-based interaction was greater for anesthesiology, dermatology, obstetrics/gynecology, pediatrics, and psychiatry than for medicine (p<0.001). CONCLUSIONS: This study demonstrates rapid adoption of secure messaging across diverse clinical specialties, with messaging interactions exceeding face-to-face clinic visits for some specialties. As patient portal and secure messaging adoption increase beyond medicine and primary care, research is needed to understand the implications for provider workload and patient care.
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Seguridad Computacional , Atención a la Salud/tendencias , Correo Electrónico/tendencias , Medicina/estadística & datos numéricos , Pacientes Ambulatorios , Adulto , Niño , Estudios de Cohortes , Registros Electrónicos de Salud , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios RetrospectivosRESUMEN
In medical centers with many high risk pregnancies, the ability to perform a large number of urinary estriol measurements is required. The analytical procedure should provide simplicity, specificity, and economy. A solid phase radioimmunoassay is presented which utilizes antibody generated against an estriol 16-glucuronide-bovine serum albumin conjugate. The assay allows analysis of the principal component of maternal urinary estriol without hydrolysis or purification, with adequate specificity and the capacity for processing large numbers of samples.
Asunto(s)
Estriol/orina , Embarazo , Animales , Sitios de Unión , Bovinos , Reacciones Cruzadas , Femenino , Humanos , Matemática , Métodos , Peso Molecular , Unión Proteica , Radioinmunoensayo , Albúmina Sérica Bovina , Relación Estructura-Actividad , TritioRESUMEN
Plasma cortisol, dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), and androstenedione (delta4-A) were measured by RIA during ACTH infusion in preadrenarchal children with constitutional short stature, normal adults, and patients with secondary adrenal insufficiency resulting from hypothalamic-pituitary disease or corticosteroid therapy. The plasma levels of all four steroids were decreased in patients with secondary adrenal insufficiency compared to normal adults, but the decrease in DHA and DHAS was considerably greater than that in cortisol and delta4-A, resulting in significant decreases in the plasma ratios of DHA to cortisol, DHAS to cortisol, DHA to delta4-A, and DHAS to delta4-A (P less than 0.00001). The decreased DHA and DHAS responses to ACTH persisted in one glucocorticoid-treated patient after glucocorticoid therapy was terminated and the cortisol response to ACTH had normalized. The data suggest that adrenal atrophy due to hypothalamic-pituitary disease or corticosteroid therapy is associated with a greater impairment in the secretion of the delta5 adrenal androgens DHA and DHAS than in the secretion of cortisol and delta4-A, and that the capacity to secrete cortisol and delta4-A recovers more rapidly than the capacity to secrete the delta5 adrenal androgens when corticosteroid therapy is withdrawn.
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Glándulas Suprarrenales/metabolismo , Insuficiencia Suprarrenal/fisiopatología , Andrógenos/metabolismo , Hidrocortisona/metabolismo , Adolescente , Hormona Adrenocorticotrópica , Adulto , Factores de Edad , Niño , Preescolar , Femenino , Humanos , Sistema Hipotálamo-Hipofisario/fisiopatología , Cinética , MasculinoRESUMEN
The plasma metabolic clearance rate (MCRp) of 2-hydroxyestrone was measured in normal young adults by two methods: infusion of unlabeled 2-OHE1 to equilibrium with radioimmunoassay of plasma 2-OHE1 levels, and infusion of [3H]2-OHE1 to equilibrium with measurement of chromatographically purified plasma [3H]2-OHE1. MCR's were 40--70,000 L/day and 15--50,000 L/day, respectively. This is the highest known MCR for a naturally occurring steroid. The only measurable plasma metabolite of [3H]2-OHE1 co-migrated with 2-methoxyestrone. When [3H]2-OHE1 was incubated with blood samples in vitro, [3H] xi-methoxyestrone was rapidly formed. Since this MCR is higher than cardiac output, clearance must occur primarily in the blood compartment, probably largely by the action of erythrocyte catechol-0-methyltransferase.
Asunto(s)
Estrona/análogos & derivados , Hidroxiestronas/sangre , Adulto , Estrona/sangre , Humanos , Cinética , Tasa de Depuración Metabólica , RadioinmunoensayoRESUMEN
A series of nine 2,4-diamino-5-[6-( or 7-)quinolylmethyl]pyrimidines has been prepared by condensations of quinolinecarboxaldehydes with beta-anilinopropionitriles, followed by treatment with guanidine. All compounds has basic or methoxy substituents at the 2- or 4-positions of the quinoline ring. All of the 6-quinolylmethyl derivatives were highly inhibitory against Escherichia coli dihydrofolate reductase (DHFR), provided that an 8-substituent was present in the quinoline ring. Those compounds that had basic substituents in the 2-position of the quinoline ring were also highly specific for bacterial dihydrofolate DHFR, relative to a vertebrate counterpart. Protonation on the quinoline ring nitrogen is a possible cause of specificity.
Asunto(s)
Antibacterianos/síntesis química , Pirimidinas/síntesis química , Quinolinas/síntesis química , Animales , Fenómenos Químicos , Química , Escherichia coli/enzimología , Antagonistas del Ácido Fólico , Hígado/enzimología , Pruebas de Sensibilidad Microbiana , Neisseria gonorrhoeae/enzimología , Pirimidinas/farmacología , Quinolinas/farmacología , Ratas , Relación Estructura-ActividadRESUMEN
Use of maternal urinary estriol excretion to monitor fetal status is often hampered by the difficulties of obtaining 24-hour specimens. Evidence is presented that timed, 12-hour overnight specimens may be substituted for the 24-hour specimens in certain patient groups. A simple non-refrigerated transport system which facilitates outpatient estriol monitoring is also described.
Asunto(s)
Estriol/orina , Pruebas de Función Placentaria , Atención Ambulatoria , Femenino , Humanos , Embarazo , Refrigeración , Riesgo , Manejo de Especímenes , Factores de TiempoRESUMEN
Umbilical artery velocimetry was investigated to determine whether abnormal flow patterns improved with bed rest and if the prognosis of the pregnancy was different in the improved groups. Abnormal flow waveform was defined as a systolic-diastolic ratio (S/D) above the 95th percentile of established normal values. One hundred twenty-eight women had abnormal waveforms. They were placed on bed rest in the left lateral position and monitored by biophysical profile and growth indices. Sixty-six subjects (51.5%) reverted to normal flow waveforms following bed rest, at a mean (+/- SD) interval of 4.5 +/- 1.5 weeks (range 3-10), and 62 (48.5%) exhibited persistent abnormal flow. None of the improved group exhibited fetal distress or perinatal mortality, whereas in the group with persistent abnormal flow, 15 (24%) experienced fetal distress and 13% experienced perinatal mortality. The diagnosis-to-delivery interval in the improved group was 63 +/- 14 days, versus 26 +/- 21 days in the unimproved group, and the mean gestational age at delivery was 37.3 +/- 2.0 versus 32.8 +/- 3.6 weeks, respectively (P less than .0001). We conclude that a subset of patients with abnormal Doppler velocimetry findings will improve on bed rest and have a better perinatal outcome, whereas persistence of abnormal flow defines a group of patients who are at risk for poor perinatal outcome and who require intensive monitoring and intervention.
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Reposo en Cama , Resultado del Embarazo , Arterias Umbilicales/diagnóstico por imagen , Velocidad del Flujo Sanguíneo , Diástole , Femenino , Estudios de Seguimiento , Humanos , Estudios Longitudinales , Embarazo , Complicaciones del Embarazo/fisiopatología , Estudios Prospectivos , Factores de Riesgo , Sístole , UltrasonografíaRESUMEN
We report eight cases of intrauterine rupture of the dividing membranes in diamniotic twin gestations and the resulting perinatal morbidity and mortality. The poor outcomes associated with these intrauterine amniotic ruptures included fetal and neonatal death secondary to cord entanglement, preterm rupture of the membranes, preterm labor and delivery, and amniotic band syndrome. The overall perinatal mortality rate was 44% (seven of 16), and the mean gestational age at delivery was 29 weeks (range 22-34). Possible etiologies for this intrauterine diamniotic rupture include fetal trauma to the dividing membranes, amniocentesis, infection, and developmental disturbances. A new theory is examined to explain the surviving twin's morbidity associated with intrauterine death of the co-twin. This study suggests that intrauterine rupture of diamniotic twin membranes carries a perinatal mortality consistent with that of true monoamniotic gestations and that, in fact, this entity may be more common than previously thought. Finally, a suspected monoamniotic gestation cannot be ruled out by the historic presence of a dividing membrane on previous ultrasound examination.
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Enfermedades Fetales/etiología , Rotura Prematura de Membranas Fetales/complicaciones , Embarazo Múltiple , Adolescente , Adulto , Femenino , Enfermedades Fetales/mortalidad , Humanos , Embarazo , GemelosRESUMEN
Previous investigations have shown blacks to have a significantly lower resting heart rate (HR) compared with whites. Our purpose was to determine if this difference exists during submaximal exercise and to compare other cardiovascular responses during submaximal exercise in black and white males. Sixteen black and 16 white males matched on age, body surface area, and maximal O2 consumption exercised at 0, 50, and 100 W on a cycle ergometer. HR, O2 consumption, and cardiac output via CO2 rebreathing were measured at rest and at each work rate. Stroke volume was then calculated. O2 consumption was not significantly different between blacks and whites at rest or at work rates of 0, 50, or 100 W. Cardiac output increased from rest with 0, 50, and 100 W work for both blacks and whites (6.1 to 13.0, 14.4, and 16.9 l/min and 5.7 to 12.2, 14.3, and 16.3 l/min, respectively). The differences in cardiac output between blacks and whites at rest and all work rates were not statistically significant. At rest and work rates of 0, 50, and 100 W, HR was significantly lower in blacks compared with whites (71, 99, 108, and 119 beats/min vs. 80, 107, 114, and 127 beats/min, respectively). The lower HR in blacks compared with whites was accompanied by a trend toward a higher stroke volume at rest and work rates of 0, 50, and 100 W (85.2, 130.3, 134.7, and 142.9 ml vs. 72.5, 114.9, 126.4, and 127.4 ml, respectively). No differences in resting blood pressures were found.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Ejercicio Físico/fisiología , Hemodinámica/fisiología , Adulto , Población Negra , Presión Sanguínea/fisiología , Superficie Corporal , Dióxido de Carbono/sangre , Prueba de Esfuerzo , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Consumo de Oxígeno/fisiología , Intercambio Gaseoso Pulmonar , Análisis de Regresión , Volumen Sistólico/fisiología , Resistencia Vascular/fisiología , Población BlancaRESUMEN
Short-term (0 to 30 minutes) physiologic responses of neonatal lambs infused with a trichloroacetic extract of a type III (strain 878) group B streptococcus (878-TCA) were studied. Bolus injections of 878-TCA were associated with pulmonary hypertension, peripheral arterial hypoxemia, and reductions in circulating white blood cell and platelet counts. These events were associated with a rise in plasma levels of prostaglandins F2 alpha and E and could be prevented by proper treatment with ibuprofen. Continuous infusions of 878-TCA were associated with a dose-dependent rise in systemic and pulmonary arterial pressures and a fall in arterial PO2. During infusion, inhibition of prostaglandin synthesis resulted in a return toward preinfusion values. The authors conclude that venous infusions of extracts of 878-TCA induce significant pulmonary and systemic arterial vascular perturbations in the neonatal lamb and that some of these alterations are associated with the release of prostaglandins or other arachidonic acid metabolites.
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Hipertensión/etiología , Prostaglandinas/biosíntesis , Streptococcus agalactiae , Ácido Tricloroacético/farmacología , Animales , Animales Recién Nacidos , Extractos Celulares/administración & dosificación , Extractos Celulares/farmacología , Dinoprost , Femenino , Hipertensión/metabolismo , Ibuprofeno/farmacología , Infusiones Parenterales , Inyecciones , Recuento de Leucocitos , Pulmón/patología , Masculino , Oxígeno/sangre , Recuento de Plaquetas , Prostaglandinas E/biosíntesis , Prostaglandinas F/biosíntesis , Arteria Pulmonar/fisiopatología , Ovinos , Choque Séptico/etiología , Streptococcus agalactiae/análisis , Ácido Tricloroacético/administración & dosificaciónRESUMEN
Ten collegiate rowers performed discontinuous incremental exercise to their tolerable limit on two occasions: once on a rowing ergometer and once on a treadmill. Ventilation and pulmonary gas exchange were monitored continuously, and blood was sampled from a venous catheter located in the back of the hand or forearm for determination of blood lactate ([La]) and plasma epinephrine ([Epi]) and norepinephrine ([NE]) concentrations. Thresholds for lactate (LT), epinephrine (Epi-T), and norepinephrine (NE-T) were determined for each subject under each condition and defined as breakpoints when plotted as a function of O2 uptake (VO2). For running, LT (3.76 +/- 0.18 l/min) was lower (P < 0.05) than Epi-T (4.35 +/- 0.14 l/min) and NE-T (4.04 +/- 0.19 l/min). For rowing, LT (3.35 +/- 0.16 l/min) was lower (P < 0.05) than Epi-T (3.72 +/- 0.22 l/min) and NE-T (3.70 +/- 0.18 l/min) and was lower (P < 0.05) than LT for running. Within each mode of exercise, Epi-T and NE-T did not differ. Because LT occurred at a significantly lower VO2 than either Epi-T or NE-T, we conclude that catecholamine thresholds, per se, were not the cause of LT. However, for both modes of exercise LT occurred at a plasma [Epi] of approximately 200-250 pg/ml (rowing, 221 +/- 48 pg/ml; running, 245 +/- 45 pg/ml); these concentrations are consistent with the plasma [Epi] reported necessary for eliciting increments in blood [La] during Epi infusion at rest. Plasma [NE] at LT differed significantly between modes (rowing, 820 +/- 127 pg/ml; running, 1,712 +/- 217 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Catecolaminas/sangre , Ejercicio Físico/fisiología , Lactatos/sangre , Carrera , Adulto , Umbral Anaerobio/fisiología , Brazo/fisiología , Epinefrina/sangre , Ergometría , Humanos , Ácido Láctico , Pierna/fisiología , Masculino , Norepinefrina/sangre , Consumo de Oxígeno/fisiologíaRESUMEN
Seven untrained male subjects [age 25.6 +/- 1.5 (SE) yr, peak O2 uptake (VO2) 3.20 +/- 0.19 l/min] trained on a cycle ergometer 4 days/wk for 6 wk, with the absolute training workload held constant for the duration of training. Before and at the end of each week of training, the subjects performed 20 min of constant-power exercise at a power designed to elicit a pronounced slow component of VO2 (end-exercise VO2-VO2 at minute 3 of exercise) in the pretraining session. An additional 20-min exercise bout was performed after training at this same absolute power output during which epinephrine (Epi) was infused at a rate of 100 ng.kg-1.min-1 between minutes 10 and 20. After 2 wk of training, significant decreases in VO2 slow component, end-exercise VO2, blood lactate ([La-] and glucose concentrations, plasma Epi ([Epi]) and norepinephrine concentrations, ventilation (VE), and heart rate (HR) were observed (P < 0.05). Although the rapid attenuation of the VO2 slow component coincided temporally with reductions in plasma [Epi], blood [La-], and VE, the infusion of Epi after training significantly increased plasma [Epi] (delta 2.22 ng/ml), blood [La-] (delta 2.4 mmol/l) and VE (delta 10.0 l/min) without any change in exercise VO2. We therefore conclude that diminution of the VO2 slow component with training is attributable to factors other than the reduction in plasma [Epi], blood [La-] and VE.
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Adaptación Fisiológica/fisiología , Ejercicio Físico/fisiología , Consumo de Oxígeno/fisiología , Intercambio Gaseoso Pulmonar/fisiología , Adaptación Fisiológica/efectos de los fármacos , Adulto , Epinefrina/administración & dosificación , Frecuencia Cardíaca , Humanos , Infusiones Intravenosas , Lactatos/sangre , Ácido Láctico , Masculino , Norepinefrina/sangre , Consumo de Oxígeno/efectos de los fármacos , Intercambio Gaseoso Pulmonar/efectos de los fármacos , Pruebas de Función Respiratoria , Simpatomiméticos/administración & dosificaciónRESUMEN
The usefulness of recrystallization in establishing the radiochemical purity of steroids is widely recognized, but the potential limitations of the technique have received little attention. The current study reports the failure of standard recrystallization procedures using methanol/water as the solvent pair to separate contaminating 14C-17-hydroxyprogesterone (17-hydroxy-4-pregnene-3, 20-dione) from 3H- and 14C-labeled 11-deoxycortisol (17,21-dihydroxy-4-pregnene-3,20-dione) despite ten serial crystallizations. The standard criteria of radiochemical purity were met despite gross impurity of the crystals as evidenced by thin layer chromatography. Thus, recrystallization may, under certain conditions, yield misleading results when employed as the only method for identifying radioactive steroids. These observations illustrate the importance of an optimal choice of solvent and crystallization conditions, and emphasize the need for confirmation by derivative formation and chromatography.
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17-Hidroxicorticoesteroides/aislamiento & purificación , Cortodoxona/aislamiento & purificación , Cristalización , Hidroxiprogesteronas/aislamiento & purificación , Radioisótopos de Carbono , Errores Diagnósticos , Metanol , Tritio , AguaRESUMEN
The purpose of this study was to extend our knowledge of running related injuries by determining whether relationships exist between selected anthropometric, biomechanical, muscular strength and endurance, and training variables and runners afflicted with patellofemoral pain (PFP). Specifically, the objectives of this study were to examine differences in selected measures between a non-injured control group (C) of runners (N = 20) and a group of injured runners (INJ) diagnosed by an orthopedic surgeon as having PFP (N = 16). High speed photography, a force platform, and isokinetic dynamometry were used to determine rearfoot motion, ground reaction forces, and knee muscular strength and endurance. Stepwise discriminant function analyses were performed on the anthropometric, biomechanical, and muscular strength and endurance variables. Q angle was a significant discriminator (P less than 0.01) between the INJ and C groups. The muscular endurance data revealed several significant discriminators with the INJ subjects being weaker in knee extension endurance. Kinetic analysis revealed several significant discriminators whereas rearfoot movement variables were not good discriminators between the groups. The training data revealed that the INJ group ran significantly less (P less than 0.01) miles.wk-1 than the C group. Our results suggest that Q angle is a strong discriminator between runners afflicted with PFP and non-injured runners. In addition, several muscular endurance and kinetic variables may also be important components of the etiology of PFP.
Asunto(s)
Rodilla/fisiopatología , Dolor/etiología , Carrera/lesiones , Adolescente , Adulto , Antropometría , Fenómenos Biomecánicos , Femenino , Humanos , Cinética , Masculino , Persona de Mediana Edad , Educación y Entrenamiento Físico/métodos , Resistencia Física , Rango del Movimiento Articular/fisiologíaRESUMEN
To assess the influence of exercise training on the growth hormone (GH) response to acute exercise, six untrained males completed a 20-min, high-intensity, constant-load exercise test prior to and after 3 and 6 wk of training (the absolute power output (PO) during each test remained constant x PO = 182.5 +/- 29.5 W). Training increased (pre- vs post-training) oxygen uptake (VO2) at lactate threshold (1.57 +/- 0.33 L.min-1 vs 1.97 +/- 0.24 L.min-1 P < or = 0.05). VO2 at 2.5 mM blood lactate concentration ([HLa]) (1.83 +/- 0.38 L.min-1 vs 2.33 +/- 0.38 L.min-1, P < or = 0.05), and VO2peak (3.15 +/- 0.54 L.min-1 vs 3.41 +/- 0.47 L.min-1, P < or = 0.05). Power output at the lactate threshold (PO-LT) increased with training from 103 +/- 28 to 132 +/- 23W (P < or = 0.05). Integrated GH concentration (20 min exercise + 45 min recovery) (microgram.L-1 x min) after 3 wk (138 +/- 106) and 6 wk (130 +/- 145) were significantly lower (P < or = 0.05) than pre-training (238 +/- 145). Plasma epinephrine and norepinephrine responses to training were similar to the GH response (EPI-pre-training = 2447 +/- 1110; week 3 = 1046 +/- 144; week 6 = 955 +/- 322 pmol.L-1; P < or = 0.05; NE pre-training = 23.0 +/- 5.2; week 3 = 13.4 +/- 4.8; week 6 = 12.1 +/- 6.8 nmol.L-1; P < or = 0.05). These data indicate that the GH and catecholamine response to a constant-load exercise stimulus are reduced within the first 3 wk of exercise training and support the hypothesis that a critical threshold of exercise intensity must be reached to stimulate GH release.
Asunto(s)
Ejercicio Físico/fisiología , Hormona de Crecimiento Humana/fisiología , Ácido Láctico/sangre , Adulto , Epinefrina/sangre , Hormona de Crecimiento Humana/sangre , Humanos , Masculino , Norepinefrina/sangre , Consumo de Oxígeno , Estudios Prospectivos , Factores de TiempoRESUMEN
Prostaglandins have been detected in high levels in the fetal circulation. These substances are known to cause marked changes in the fetal and uterine circulations. The present study demonstrated an increase in fetal and maternal circulating levels of i prostaglandin F2 alpha in fetal lambs with acute acidosis. Both levels correlated with the degree of fetal acidosis. No consistent change in levels of i PGE were noted. Prostaglandins may play a role in the pathogenesis of response to fetal stress.