RESUMEN
We present the first study of cuticles and compressions of fossil leaves by Focused Ion Beam Scanning Electron Microscopy (FIB-SEM). Cavities preserved inside fossil leaf compressions corresponding to substomatal chambers have been observed for the first time and several new features were identified in the cross-section cuts. These results open a new way in the investigation of the three-dimensional structures of both micro- and nanostructural features of fossil plants. Moreover, the application of the FIB-SEM technique to both fossils and extant plant remains represent a new source of taxonomical, palaeoenvironmental and palaeoclimatic information.
Asunto(s)
Fósiles/ultraestructura , Iones , Microscopía Electrónica de Rastreo/métodos , Hojas de la Planta/ultraestructura , Imagenología TridimensionalRESUMEN
The purpose of the study was to determine if leg strength limits VO2 max and the ability to reach a plateau during VO2 max test in older men during cycle ergometry. Men aged 70-80 years were randomly selected into a strength training (ST, n=12) 3 times weekly for 16 weeks, followed by 4 weeks detraining or a non-training control group (C, n=12). Leg strength and VO2 max were assessed every 4 weeks for 20 weeks; body composition and cardiac function were assessed before and after 16 weeks training and after 4 weeks detraining. Leg strength, upper leg muscle mass (ULMM), arterial-venous O2 difference (a-v O2 difference) and VO2 max increased in the ST group (95±0.6%, 7±0.7%. 6.2±0.5% and 8±0.8%, respectively; P<0.05) after 16 weeks training. After 4 weeks detraining, gains in ULMM (50%) and strength (75%) were retained, but VO2 max and a-v O2 difference returned to pre-training levels. There was no change in the ability of the participants to reach a plateau during VO2 max testing over the 20-week study. These findings indicate that leg strength may not limit either VO2 max or the ability to plateau during VO2 max tests in older men during cycle ergometry.
Asunto(s)
Fuerza Muscular/fisiología , Consumo de Oxígeno/fisiología , Entrenamiento de Fuerza/métodos , Anciano , Anciano de 80 o más Años , Ciclismo/fisiología , Ergometría , Prueba de Esfuerzo , Humanos , Pierna , MasculinoRESUMEN
A 36-year-old man being treated with cisplatinum, vinblastine, and bleomycin for testicular carcinoma developed a dense left homonymous hemianopsia, encephalopathy, and a partial nondominant parietal lobe syndrome. He subsequently had a resolution of all signs and symptoms, suggesting that these alarming events were a toxic but reversible side effect of the chemotherapy.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Encefalopatías/inducido químicamente , Hemianopsia/inducido químicamente , Teratoma/tratamiento farmacológico , Neoplasias Testiculares/tratamiento farmacológico , Adulto , Bleomicina/administración & dosificación , Cisplatino/administración & dosificación , Cisplatino/efectos adversos , Humanos , Masculino , Factores de Tiempo , Vinblastina/administración & dosificaciónRESUMEN
The European Society for Paediatric Endocrinology held a consensus workshop in Manchester, UK in December 2003 to discuss issues relating to the care of GH-treated patients in the transition from paediatric to adult life. Clinicians experienced in the care of paediatric and adult patients on GH treatment, from a wide range of countries, as well as medical representatives from the pharmaceutical manufacturers of GH participated.
Asunto(s)
Servicios de Salud del Adolescente , Continuidad de la Atención al Paciente , Trastornos del Crecimiento/tratamiento farmacológico , Hormona de Crecimiento Humana/uso terapéutico , Adolescente , Adulto , HumanosRESUMEN
Large doses of atrial natriuretic peptide (ANP) inhibit renin and aldosterone secretion in normal man, but the effect of physiological levels is unknown. We, therefore, studied the effect of a low infusion rate of alpha-human ANP (alpha hANP; 0.5 microgram/min for 180 min) on the plasma corticosteroid response to graded physiological doses of angiotensin II (0.5, 1.0, 2.0, and 4.0 ng/kg X min, each for 30 min) and ACTH (6.25, 12.5, 25, and 50 mIU, each for 30 min) in six normal men eating a low salt diet (10 mmol sodium and 100 mmol potassium daily). The angiotensin II and ACTH infusions were given from 0900-1100 h on separate days, during which randomized infusions of placebo or alpha hANP were given from 0800-1100 h according to a single blind protocol. Plasma immunoreactive ANP levels were less than 10 pmol/L on the placebo day compared to 30-50 pmol/L during the alpha hANP infusions, and were not altered by either ACTH or angiotensin II. Compared with the control observations, there was no significant change in arterial pressure or heart rate during either the alpha hANP or angiotensin II infusions. ACTH infusions evoked an incremental response in plasma aldosterone and cortisol, and the dose-response relationship was unaltered by alpha hANP. In contrast, while an incremental and significant increase in plasma aldosterone in response to angiotensin II occurred with the placebo infusion, no significant increase occurred in response to angiotensin during the alpha hANP infusion. The slope of the angiotensin II/aldosterone regression line was significantly less during all alpha hANP infusions compared to that during the placebo infusion (P less than 0.02). In addition, on the ACTH infusion day significant suppression of both PRA (P less than 0.05) and plasma angiotensin II (P less than 0.008) occurred during the alpha hANP infusion compared to that during the placebo infusion, whereas PRA was equally suppressed by angiotensin II in the presence or absence of alpha hANP. alpha hANP also increased urine volume [176 +/- 31 (+/- SEM) vs. 113 +/- 19 mL/mmol creatinine with placebo; P less than 0.03] and sodium excretion (2.14 +/- 0.48 vs. 0.58 +/- 0.22 mmol/mmol creatinine with placebo; P less than 0.004) on the ACTH infusion days. With angiotensin II, urine volume was also significantly increased by alpha hANP (150 +/- 27 vs. 81 +/- 15 mL/mmol creatinine with placebo; P less than 0.03), and urine sodium excretion doubled.(ABSTRACT TRUNCATED AT 400 WORDS)
Asunto(s)
Aldosterona/metabolismo , Factor Natriurético Atrial/fisiología , Renina/antagonistas & inhibidores , Hormona Adrenocorticotrópica/farmacología , Adulto , Angiotensina II/farmacología , Depresión Química , Diuresis , Humanos , Masculino , Antagonistas de Receptores de Mineralocorticoides/farmacología , Sodio/metabolismo , Equilibrio HidroelectrolíticoRESUMEN
The effect of 60-min constant iv infusions of alpha-human atrial natriuretic peptide (alpha hANP; 200 micrograms), sufficient to increase the steady state venous plasma alpha hANP concentration to levels found in patients with some circulatory disorders, was studied in six normal men equilibrated on a high sodium diet (200 mmol daily) and again when equilibrated on a low sodium intake (10 mmol daily). In each instance, the responses to alpha hANP were compared to those to control infusions given on the preceding day. The mean steady state plasma immunoreactive ANP concentration during the infusions was 320 pmol/liter and was the same during both diets. Thus, the MCR of alpha hANP was unaffected by major changes in sodium intake. Compared to control day observations, infusions of alpha hANP induced a more than 3-fold increase in sodium excretion and at least a 2-fold increase in urine volume and calcium and magnesium excretion in subjects ingesting 200 mmol sodium daily. During the low sodium diet, alpha hANP was still diuretic and induced comparable magnesium excretion, but the natriuresis was only 11% of that during the high salt diet. No significant changes in blood pressure or heart rate occurred during alpha hANP infusions during either diet, although during both diets there was a significant rise in plasma norepinephrine (P less than 0.02), which persisted well beyond the disappearance of immunoreactive ANP from plasma. Despite this sympathetic activation, renin and aldosterone production was reduced by alpha hANP. During low salt intake, alpha hANP significantly decreased PRA (mean pretreatment, 1.79; posttreatment, 1.25 nmol/liter/h; P less than 0.03), angiotensin II (mean pretreatment, 49; posttreatment, 28 pmol/liter; P less than 0.008), and plasma aldosterone (mean pretreatment, 554; posttreatment 307 pmol/liter; P less than 0.007), whereas values during control infusions did not change. Similar percent decreases in PRA and aldosterone also occurred during the high salt diet. Plasma cortisol and arginine vasopressin did not change during the alpha hANP infusions on either diet. We conclude that steady state levels of alpha hANP in plasma, similar to those in patients with some circulatory disorders, significantly increase sodium excretion and inhibit all elements of the renin-angiotensin-aldosterone system. The natriuretic, but not the hormonal or chronotropic, effects of alpha hANP are reduced by sodium depletion in normal man.
Asunto(s)
Factor Natriurético Atrial/farmacología , Hemodinámica/efectos de los fármacos , Hormonas/sangre , Riñón/efectos de los fármacos , Sodio/administración & dosificación , Adulto , Presión Sanguínea/efectos de los fármacos , Dieta , Electrólitos/orina , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Hidrocortisona/sangre , Masculino , Persona de Mediana Edad , Norepinefrina/sangre , Prolactina/sangre , Sistema Renina-Angiotensina/efectos de los fármacosRESUMEN
Increased bone turnover is a sequel of spinal cord injury (SCI) and predisposes to a number of clinically relevant complications, including osteoporosis and fractures. There are limited data available regarding the changes in modern markers of bone metabolism after SCI. We report a 6-month longitudinal follow-up of biochemical markers of bone metabolism (free and total deoxypyridinoline, total pyridinoline, N-telopeptide, osteocalcin, and total alkaline phosphatase) and bone mineral densitometry in 30 subjects with acute SCI. Markers of bone formation showed only a minor rise, remaining within the reference range. In contrast, markers of bone resorption showed a significant rise after acute SCI, peaking around weeks 10-16, with values up to 10 times the upper limit of normal. Paired bone mineral densities (n = 11; on the average, determined 14 weeks apart) showed no change at the hip, lumbar spine, or radius, but demonstrated a decrement in the entire lower limbs. changes in biochemical markers of bone formation and resorption were comparable in patients with quadriplegia and paraplegia, except for a greater increase in quadriplegics in pyridinoline, expressed as a percentage of baseline. In conclusion, a marked increase in bone resorption and modest changes in bone formation occur after SCI, and possibly increased bone resorption occurs in quadriplegia.
Asunto(s)
Remodelación Ósea , Traumatismos de la Médula Espinal/fisiopatología , Adolescente , Adulto , Aminoácidos/orina , Biomarcadores , Densidad Ósea , Resorción Ósea/fisiopatología , Calcitriol/sangre , Calcio/sangre , Calcio/orina , Colágeno/orina , Colágeno Tipo I , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Paraplejía/fisiopatología , Péptidos/orina , Estudios Prospectivos , Cuadriplejía/fisiopatologíaRESUMEN
To examine the interactions between acute exercise and GH on markers of bone and collagen turnover and to assess the potential for detecting GH abuse in athletes using these markers, we studied 17 aerobically trained males (age, 26.9+/-1.5 yr). Sequential studies of exercise, GH administration, and GH withdrawal were undertaken. A randomized, controlled study of rest vs. exercise showed that exercise did not change serum osteocalcin; other markers of formation increased transiently (each P<0.001): bone-specific alkaline phosphatase (+16.1%), carboxyterminal propeptide of type I procollagen (+14.1%), and procollagen III N-terminal extension peptide (+5.0%). The carboxyterminal cross-linked telopeptide of type I collagen, a bone resorption marker, increased 9.7% (P = 0.018) in response to exercise. A randomized, double blind, placebo-controlled, parallel study of recombinant human GH treatment (0.15 IU/kg x day) for 1 week increased serum osteocalcin (net increase preexercise, +/-10.0%; P = 0.017), carboxyterminal propeptide of type I procollagen (+17.6%; P = 0.002), procollagen III N-terminal extension peptide (+48.4%; P = 0.001), and carboxyterminal cross-linked telopeptide of type I collagen (53.3%; P = 0.009). Disappearance half-times after cessation of recombinant human GH for pre- and postexercise markers ranged from 248-770 h. We conclude 1) endurance exercise transiently activates bone and collagen turnover; 2) brief GH administration results in similar but quantitatively greater augmentation; and 3) these data will assist in designing a GH detection strategy.
Asunto(s)
Huesos/metabolismo , Colágeno/metabolismo , Ejercicio Físico/fisiología , Hormona del Crecimiento/efectos adversos , Hormona del Crecimiento/farmacología , Hormona de Crecimiento Humana/efectos adversos , Hormona de Crecimiento Humana/farmacología , Síndrome de Abstinencia a Sustancias/metabolismo , Adolescente , Adulto , Envejecimiento/metabolismo , Biomarcadores , Desarrollo Óseo/fisiología , Prueba de Esfuerzo , Hormonas/sangre , Humanos , Cinética , Masculino , Resistencia Física/fisiología , Aptitud Física/fisiologíaRESUMEN
GH is being used by elite athletes to enhance sporting performance. To examine the hypothesis that exogenous 22-kDa recombinant human GH (rhGH) administration could be detected through suppression of non-22-kDa isoforms of GH, we studied seventeen aerobically trained males (age, 26.9 +/- 1.5 yr) randomized to rhGH or placebo treatment (0.15 IU/kg/day for 1 week). Subjects were studied at rest and in response to exercise (cycle-ergometry at 65% of maximal work capacity for 20 min). Serum was assayed for total GH (Pharmacia IRMA and pituitary GH), 22-kDa GH (2 different 2-site monoclonal immunoassays), non-22-kDa GH (22-kDa GH-exclusion assay), 20-kDa GH, and immunofunctional GH. In the study, 3 h after the last dose of rhGH, total and 22-kDa GH concentrations were elevated, reflecting exogenous 22-kDa GH. Non-22-kDa and 20-kDa GH levels were suppressed. Regression of non-22-kDa or 20-kDa GH against total or 22-kDa GH produced clear separation of treatment groups. In identical exercise studies repeated between 24 and 96 h after cessation of treatment, the magnitude of the responses of all GH isoforms was suppressed (P < 0.01), but the relative proportions were similar to those before treatment. We conclude: 1) supraphysiological doses of rhGH in trained adult males suppressed exercise-stimulated endogenous circulating isoforms of GH for up to 4 days; 2) the clearest separation of treatment groups required the simultaneous presence of high exogenous 22-kDa GH and suppressed 20-kDa or non-22-kDa GH concentrations; and 3) these methods may prove useful in detecting rhGH abuse in athletes.
Asunto(s)
Hormona de Crecimiento Humana/química , Hormona de Crecimiento Humana/farmacología , Educación y Entrenamiento Físico , Isoformas de Proteínas/farmacología , Adulto , Ciclismo , Humanos , Masculino , Peso Molecular , Concentración Osmolar , Isoformas de Proteínas/sangre , Isoformas de Proteínas/química , Proteínas Recombinantes/farmacologíaRESUMEN
Circulating GH consists of multiple molecular isoforms, all derived from the one gene in nonpregnant humans. To assess the effect of a potent stimulus to pituitary secretion on GH isoforms, we studied 17 aerobically trained males (age, 26.9 +/- 1.5 yr) in a randomized, repeat measures study of rest vs. exercise. Exercise consisted of continuous cycle ergometry at approximately 80% of predetermined maximal oxygen uptake for 20 min. Serum was assayed for total, pituitary, 22-kDa, recombinant, non-22-kDa, 20-kDa, and immunofunctional GH. All isoforms increased during, peaked at the end, and declined after exercise. At peak exercise, 22-kDa GH was the predominant isoform. After exercise, the ratios of non-22 kDa/total GH and 20-kDa GH/total GH increased and those of recombinant/pituitary GH decreased. The disappearance half-times for pituitary GH and 20-kDa GH were significantly longer than those for all other isoforms. We conclude that 1) all molecular isoforms of GH measured increased with and peaked at the end of acute exercise, with 22-kDa GH constituting the major isoform in serum during exercise; and 2) the proportion of non-22-kDa isoforms increased after exercise due in part to slower disappearance rates of 20-kDa and perhaps other non-22-kDa GH isoforms. It remains to be determined whether the various biological actions of different GH isoforms impact on postexercise homeostasis.
Asunto(s)
Ejercicio Físico/fisiología , Hormona de Crecimiento Humana/sangre , Educación y Entrenamiento Físico , Isoformas de Proteínas/sangre , Adulto , Ciclismo , Hormona de Crecimiento Humana/química , Humanos , Masculino , Peso Molecular , Factores de TiempoRESUMEN
The long term effects of GH replacement in adult GH-deficient (GHD) patients have not yet been clarified. We studied 21 GHD adults who originally took part in a randomized, double blind, placebo-controlled trial of GH treatment in 1987. After completion of that trial, 10 patients received continuous GH replacement for the subsequent 10 yr, whereas 11 did not. A group of 11 age- and sex-matched normal controls were also studied in 1987 and 1997. Lean body mass, as assessed by total body potassium measurement and computed tomography scanning of the dominant thigh, increased in the GH-treated group (P < 0.01 for both) only (P < 0.05 between groups for total body potassium). Low density lipoprotein cholesterol decreased in the GH-treated group (P < 0.05) only. Carotid intima media thickness was significantly greater (P < 0.05) in the untreated group than in the GH-treated group. Assessment of psychological well-being using the Nottingham Health Profile revealed improvement in overall score, energy levels, and emotional reaction in the GH-treated group compared with those in the untreated group (P < 0.02). In conclusion, GH treatment for 10 yr in GHD adults resulted in increased lean body and muscle mass, a less atherogenic lipid profile, reduced carotid intima media thickness, and improved psychological well-being.
Asunto(s)
Hormona del Crecimiento/uso terapéutico , Hormona de Crecimiento Humana/deficiencia , Adulto , Presión Sanguínea/efectos de los fármacos , Composición Corporal , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de TiempoRESUMEN
Measurements of serum insulin-like growth factor I (IGF-I) and related markers are routinely used in the diagnosis and treatment of GH deficiency and excess. The validity of these markers for assessment of exogenous GH exposure in healthy adults is, however, unknown. We therefore conducted a double blind, placebo-controlled GH treatment trial in 99 healthy subjects [49 women and 50 men; mean +/- SE age, 25.6+/-0.6 (women)/25.7+/-0.6 yr (men)]. Blood was collected weekly during a 4-week treatment period (days 1-28), and the subjects were subsequently followed for additional 8 weeks (days 29-84). The treatment arms included: I) 0.1 IU/kg x day GH (n = 30; GH 0.1), II) 0.2 IU/kg x day GH (n = 29; GH 0.2), and III) placebo (n = 40). At baseline no gender-specific differences existed, except that the acid-labile subunit (ALS) levels were higher in females. Serum insulin-like growth factor I (IGF-I) levels in males receiving GH increased significantly through day 42 with no significant difference between the 2 doses. The absolute IGF-I response was significantly lower in females, and there was a clear dose-response relationship. ALS levels in males increased through day 30 (P < 0.001). In females ALS levels were only modestly increased on day 28 compared with those in the placebo group (P < 0.02). IGF-binding protein-3 (IGFBP-3) levels in males increased significantly in the GH 0.1 and the GH 0.2 groups on day 30 (P < 0.03), whereas no solid IGFBP-3 increase was detected in females. IGFBP-2 levels decreased insignificantly during GH exposure in both genders. A gender-specific upper normal range for each analyte was arbitrarily defined as 4 SD above the mean level at baseline. On the basis of IGF-I levels alone, GH exposure in the GH 0.2 group was detected in 86% of the males and in 50% of the females on day 21. On day 42 GH exposure was only weakly detectable in males and was not detectable in females. We conclude that 1) males are significantly more responsive than females to exogenous GH; 2) the increase in IGF-I is more robust compared with those in IGFBP-3 and ALS; 3) IGFBP-2 changes very little during GH treatment; and 4) among IGF-related substances, IGF-I is the most specific marker of supraphysiological GH exposure.
Asunto(s)
Hormona de Crecimiento Humana/farmacología , Proteína 2 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/metabolismo , Adolescente , Adulto , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Masculino , Placebos , Subunidades de Proteína , Valores de Referencia , Caracteres SexualesRESUMEN
GH treatment in adults with GH deficiency has numerous beneficial effects, but most studies have been small. We report the results of an Australian multicenter, randomized, double-blind, placebo-controlled trial of the effects of recombinant human GH treatment in adults with GH deficiency. GH deficiency was defined as a peak serum GH of < 5 mU/liter in response to insulin-induced hypoglycemia. Patients were randomly assigned to receive either GH (0.125 U/kg per week for 1 month and 0.25 U/kg per week for 5 months) or placebo. After 6 months, all patients received GH. The primary end points were biochemical responses, body composition, quality of life, and safety. One hundred sixty-six patients (72 females and 91 males) with a mean age of 40 +/- 1 yr (+/- SEM; range 17-67 yr) were recruited. Serum insulin-like growth factor-I (IGF-I) increased from a standard deviation score of -2.64 +/- 0.27 (range -8.8 +3.82; n = 78) to +1.08 +/- 2.87 (range -7.21 to +6.42) at 6 months in the GH/GH group; 38% of the whole group were above the age-specific reference range following treatment [17.6% and 68.9% with subnormal (< 2 SD) or normal (+/- 2 SD) pretreatment levels, respectively]. Fasting total cholesterol (P = 0.042) and low-density lipoprotein cholesterol (P = 0.006) decreased over the first 6 months. Fat-free mass increased in the first 6 months whether measured by bioelectrical impedance (P < 0.001) or dual energy x-ray absorptiometry (DEXA; P < 0.001). Total-body water increased in the first 6 months whether measured by bioelectrical impedance (P < 0.001) or deuterium dilution (P = 0.002). Fat mass measured by DEXA (P < 0.001), skinfold thicknesses (P < 0.001), and waist/hip ratio (P = 0.001) decreased in the first 6 months. Most changes in body composition were complete by 3 months of treatment and maintained to 12 months. Whole-body bone mineral density (BMD) (by DEXA) was unaffected by GH treatment. Self-reported quality of life was considered good before treatment, and beneficial treatment effects were observed for energy, pain, and emotional reaction as assessed by the Nottingham Health Profile. In the initial 6 months, adverse effects were reported by 84% of patients in the GH and 75% in the placebo group, with more symptoms relating to fluid retention in the GH group (48% vs. 30%; P = 0.016). Such symptoms were mild and resolved in 70% of patients despite continued treatment. Resting blood pressure did not change over the initial 6 months. In summary, GH treatment in adults with GH deficiency resulted in 1) prominent increases in serum IGF-I at the doses employed, in some cases to supraphysiological levels; 2) modest decreases in total- and low-density lipoprotein cholesterol, together with substantial reductions in total-body and truncal fat mass consistent with an improved cardiovascular risk profile; 3) substantial increases in lean tissue mass; and 4) modest improvements in perceived quality of life. The excessive IGF-I response and side-effect profile suggests that lower doses of GH may be a required for prolonged GH treatment in adults with severe GH deficiency.
Asunto(s)
Hormona de Crecimiento Humana/deficiencia , Hormona de Crecimiento Humana/uso terapéutico , Calidad de Vida , Adulto , Análisis de Varianza , Australia , Presión Sanguínea , Densidad Ósea/efectos de los fármacos , Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Dexametasona , Método Doble Ciego , Emociones , Femenino , Hormona de Crecimiento Humana/efectos adversos , Hormona de Crecimiento Humana/sangre , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/análisis , Masculino , Persona de Mediana Edad , Placebos , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico , Triglicéridos/sangre , Equilibrio Hidroelectrolítico/efectos de los fármacosRESUMEN
GH abuse by elite athletes is currently undetectable. To define suitable markers of GH doping, we assessed the effects of acute exercise, GH administration, and GH withdrawal on the GH/insulin-like growth factor (IGF) axis in athletic adult males. Acute endurance-type exercise increased serum GH, GH-binding protein (GHBP), total IGF-I, IGF-binding protein (IGFBP)-3, and acid-labile subunit (ALS), each peaking at the end of exercise. IGFBP-1 increased after exercise was completed. Free IGF-I did not change with exercise. Recombinant human GH treatment (0.15 IU/kg x day) for 1 week increased serum total IGF-I, IGFBP-3, and ALS, exaggerating the responses to exercise. IGFBP-2 and IGFBP-1 were trivially suppressed. After GH withdrawal, the GH response to identical exercise was suppressed. Total IGF-I, IGFBP-3, and ALS returned to baseline over 3-4 days. In summary, 1) acute exercise transiently increased all components of the IGF-I ternary complex, possibly due to mobilization of preformed intact complexes; 2) GH pretreatment augmented the exercise-induced changes in ternary complexes; 3) postexercise IGFBP-1 increments may protect against delayed onset hypoglycemia; 4) serum total IGF-I, IGFBP-3, and ALS may be suitable markers of GH abuse; and 5) differences in disappearance times altered the sensitivity of each marker for detecting GH abuse.
Asunto(s)
Ejercicio Físico , Hormona de Crecimiento Humana/sangre , Hormona de Crecimiento Humana/farmacología , Educación y Entrenamiento Físico , Somatomedinas/análisis , Adulto , Proteínas Portadoras/sangre , Glicoproteínas/sangre , Hormona de Crecimiento Humana/administración & dosificación , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/análisis , Cinética , Masculino , Resistencia Física , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacología , Medicina Deportiva/métodos , Trastornos Relacionados con Sustancias/diagnóstico , Factores de TiempoRESUMEN
Seven cases of upward transtentorial herniation occurred. In each patient, coma with reactive, miotic pupils, asymmetrical or absent caloric responses, and decerebrate posture indicated brain-stem compression. In this setting, the development of unequal, then midposition, fixed pupils signaled midbrain failure from upward herniation. Vertebral angiography showed upward displacement of the superior cerebellar arteries. Results of autopsy confirmed the existence of grooving of the vermis by the tentorial margins and, in one case, of anterior displacement and distortion of the midbrain. In five of 45 reported cases of upward herniation, the conditions were diagnosed antemortem. Instances of cerebellar hematoma and tumor predominated. In at least seven patients, performance of ventriculography may have precipitated herniation. Clinical details were provided in only nine patients and did not separate upward herniation from brain-stem compression. Cerebellar ischemic infarct found in one of our patients is a rarely reported cause of upward herniation.
Asunto(s)
Enfermedades Cerebelosas/patología , Cerebelo/patología , Encefalocele/patología , Adulto , Enfermedades Cerebelosas/diagnóstico por imagen , Enfermedades Cerebelosas/etiología , Cerebelo/diagnóstico por imagen , Encefalocele/diagnóstico por imagen , Encefalocele/etiología , Femenino , Humanos , Masculino , RadiografíaRESUMEN
A 60-year-old patient suffered a lethal hemispheric infarction 3 days after angiographically documented occlusion of the ipsilateral cervical internal carotid artery and while receiving anticoagulant therapy. Pathologic evidence is consistent with embolism from the distal "tail" of a propagated carotid thrombus as the mechanism of his stroke.
Asunto(s)
Trombosis de las Arterias Carótidas/complicaciones , Trastornos Cerebrovasculares/etiología , Trombosis de las Arterias Carótidas/diagnóstico , Arteria Carótida Interna , Infarto Cerebral/diagnóstico , Infarto Cerebral/etiología , Trastornos Cerebrovasculares/diagnóstico , Humanos , Masculino , Persona de Mediana EdadRESUMEN
A syndrome consisting of a subacute encephalopathy, sensorineural hearing loss, and retinal arteriolar occlusions is described in two women. Laboratory investigations did not reveal any systemic vasculitis. CT and cerebral angiography showed no abnormalities, but magnetic resonance imaging revealed small, discrete lesions in the white matter. Biopsy of cortical brain from one patient showed disseminated microinfarcts in the gray matter as well as sclerosis of small vessels. This syndrome is characterized as an occlusive vasculopathy rather than vasculitis, and should be considered in evaluations of young women presenting with encephalopathy and hearing loss.
Asunto(s)
Arteriopatías Oclusivas/patología , Encefalopatías/patología , Trastornos de la Audición/patología , Vasos Retinianos , Adulto , Arteriopatías Oclusivas/diagnóstico , Arteriopatías Oclusivas/tratamiento farmacológico , Arteriolas , Encefalopatías/diagnóstico , Infarto Cerebral/patología , Ciclofosfamida/uso terapéutico , Femenino , Angiografía con Fluoresceína , Fondo de Ojo , Trastornos de la Audición/diagnóstico , Humanos , Espectroscopía de Resonancia Magnética , Prednisona/uso terapéutico , SíndromeRESUMEN
There is evidence that melatonin may play a role in modulating pituitary secretion, although the mechanisms are unclear. We examined the effects of a single dose of oral melatonin (5mg) on exercise-induced GH secretion. In a randomised, double-blind, placebo-controlled study, seven healthy male subjects undertook an initial period of graded bicycle ergometric exercise to determine maximum workload and oxygen uptake (VO(2max)). Subjects were subsequently studied on two further occasions, receiving either melatonin or placebo in random order at the onset of each study (-60min). At 0 min a period of bicycle exercise was performed for 8 min at a workload corresponding to 70% of that achieved at VO(2max). Serum GH and IGF-binding protein-1 (IGFBP-1) concentration was measured at 15-min intervals from the onset of the study until 120 min post-exercise. Blood was also sampled for the measurement of plasma glucose, insulin, non-esterified fatty acids, IGFBP-3, melatonin and vasopressin concentration. There was an exercise-induced increase in GH concentration following melatonin which was greater compared with placebo as assessed by both area under the curve (P<0.01) and peak increase in GH levels (P<0.01). The peak increase in IGFBP-1 levels post-exercise was also significantly greater following melatonin compared with placebo (P<0. 01) but did not quite reach levels of significance as measured by area under the curve (P=0.07). Since exercise-induced GH secretion is thought to be mediated predominantly through a hypothalamic pathway, it seems likely that melatonin facilitates GH secretion at a hypothalamic level.
Asunto(s)
Ejercicio Físico/fisiología , Hormona de Crecimiento Humana/metabolismo , Melatonina/farmacología , Adulto , Ciclismo , Glucemia/metabolismo , Método Doble Ciego , Ácidos Grasos no Esterificados/sangre , Hormona de Crecimiento Humana/sangre , Humanos , Insulina/sangre , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Cinética , Masculino , Melatonina/administración & dosificación , Consumo de Oxígeno , Placebos , Vasopresinas/sangreRESUMEN
In a 3-year period 157 single lumen Broviac catheters were inserted in 145 children with various neoplastic diseases. The overall duration of the catheter courses was 30,533 days (median, 171; range, 2 to 647). Sixty-five percent of the catheter courses (102 of 157) were complicated by at least 1 febrile episode, for a total of 157 episodes. According to European Organization for Research on Treatment of Cancer criteria, 79 febrile episodes (50%) were classified as microbiologically documented infections, 57 (36%) with and 22 (14%) without septicemia; 31 (20%) as clinically documented infections; and 47 (30%) as possible infections. Of the 79 microbiologically documented infections 21 were catheter-related infections (CRI), 32 were catheter-unrelated infections and 26 were infections of unknown source. Only 48% of CRI occurred during neutropenia (less than 1000 neutrophils/mm3), compared with 88% of catheter-unrelated infections and 96% of infections of unknown origin (P = 0.00007). Gram-positive microorganisms (56% staphylococci) accounted for 78% of all isolates in CRI, 47% in catheter-unrelated infections and 43% in infections of unknown origins (P = 0.03). Fungi represented 12% of all isolates. Clinical and microbiologic resolution without removal of the catheter was achieved in 12 of 21 CRI (57%) and no patient died from a CRI. This study indicates that over 3 of 4 of CRI are caused by Gram-positive bacteria, occur in neutropenic and non-neutropenic patients (approximately 50%) and can be successfully treated without removing the catheter.
Asunto(s)
Catéteres de Permanencia/efectos adversos , Infección Hospitalaria/microbiología , Neoplasias/microbiología , Infecciones Oportunistas/microbiología , Adolescente , Agranulocitosis/microbiología , Bacterias/aislamiento & purificación , Niño , Preescolar , Femenino , Humanos , Masculino , Sepsis/microbiologíaRESUMEN
The effects of 6 months' treatment with recombinant human growth hormone (rhGH) on serum lipids and lipoproteins were assessed in 24 adult patients with GH deficiency in a double-blind, placebo-controlled trial. Compared with age-, weight-, and sex-matched controls, the patients had significantly higher serum concentrations of total cholesterol (P = .002), low-density lipoprotein (LDL) cholesterol (P < .001), apolipoprotein B ([apoB] P = .011), and triglyceride (P = .017), and lower concentrations of high-density lipoprotein (HDL) cholesterol (P < .001). The prevalence of elevated serum cholesterol, triglyceride, LDL cholesterol, and apo B levels was 39%, 26%, 39%, and 25%, respectively; 75% of patients had decreased concentrations of HDL cholesterol. Treatment with rhGH (0.07 U/kg daily) resulted in decreases in total cholesterol level (5.8 +/- 0.3 to 5.1 +/- 0.3 mmol.L-1 over 6 months; P = .01 compared with placebo), LDL cholesterol level (4.22 +/- 0.25 to 3.19 +/- 0.23 mmol.L-1; P = .0003), LDL:HDL cholesterol ratio (5.57 +/- 0.47 to 3.29 +/- 0.33; P = .03), apo B level (1.07 +/- 0.06 to 0.84 +/- 0.07 g.L-1; P = .003), and apo B: A-1 ratio (0.73 +/- 0.05 to 0.69 +/- 0.05; P = .01). HDL cholesterol and apo A-1 levels did not change following rhGH treatment. The changes in lipid and lipoprotein levels were not significantly related to changes in insulin, thyroid hormones, insulin-like growth factor-1 (IGF-1), or indices of adiposity.(ABSTRACT TRUNCATED AT 250 WORDS)