RESUMO
Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described. Unlike the classic diffusion-adsorption (D-A) model, RDA uses a cylindrical geometry to describe the U uptake in fossil bones. The model was applied across a transverse section of a tibia of an extinct megamammal Macrauchenia patachonica from the La Paz Local Fauna, Montevideo State, Uruguay. Measurements of spatial distribution of Na, K, Ca, and Mg were also performed by neutron activation analysis (NAA). Gamma-ray spectrometric U-series dating was applied to determine the age of the bone sample. From U concentration profile, it was possible to observe the occurrence of a relatively slow and continuous uranium uptake under constant conditions that had not yet reached equilibrium, since the uranium distribution is a âª-shaped closed-system. Predictions of the RDA model were obtained for a specific geochemical scenario, indicating that the effective diffusion coefficient D/R in this fossil bone is (2.4 ± 0.6)10(-12) cm(2)s(-1). Mean values of Na, K, Ca, and Mg contents along the radial line of the fossil tibia are consistent with the expected behavior for spatial distributions of these mineral elements across a modern bone section. This result indicates that the fossil tibia may have its mineral structure preserved.
Assuntos
Arqueologia/métodos , Fósseis , Modelos Teóricos , Paleontologia/métodos , Tíbia/química , Urânio/química , Adsorção , Animais , Cálcio/química , Difusão , Mamíferos , Metais Leves/química , Análise de Ativação de Nêutrons , Espectrometria gama , Urânio/análiseRESUMO
Low-dose antiprogestin administration has been proposed as a new contraceptive modality to interference with endometrial receptivity without disturbing ovarian function. The effects of 1 mg/day mifepristone for 150 days on the menstrual cycle were assessed in 21 surgically sterilized women. The aim was to study each woman for one control cycle and during months 1, 3 and 5 of treatment. Ovulation, endometrial thickness, serum oestradiol and progesterone, urinary luteinizing hormone, endometrial morphology and cervical mucus were assessed. Luteal phase progesterone concentrations were observed in 36 of the 60 treated months assessed and less frequently as treatment progressed. The bleeding pattern was regular in most biphasic cycles, while prolonged interbleeding intervals or no bleeding were associated with monophasic cycles. Altered endometrial morphology was found in all cases irrespective of the occurrence of luteal activity. Increased endometrial thickness and dilated glands were observed in 25 and 34% respectively of the monophasic cycles. Mifepristone, 1 mg/day, interferes with endometrial development while allowing the occurrence of biphasic ovarian cycles and regular bleeding. However, it also prevents ovarian cyclicity in a high proportion of treated months, and this is associated with increased endometrial growth in some women, which may be of concern.
PIP: Low-dose antiprogestin administration has been proposed as a new contraceptive modality that interferes with endometrial receptivity without disturbing ovarian function. To explore this potential, the effects on the menstrual cycle of 1 mg/day of mifepristone for 150 days were assessed in 21 surgically sterilized women from Santiago, Chile. Control cycles were biphasic in all 21 women and ovulatory in 20 women. Luteal phase progesterone concentrations were observed in 36 of the 60 treatment months (1, 3, and 5) assessed. The proportion of ovulatory cycles was highest during month 1 and decreased progressively with treatment. 40% of treatment cycles were monophasic and bleeding cyclicity was altered in 57%. Prolonged inter-bleeding intervals or no bleeding occurred in monophasic cycles. Endometrial morphology was altered in all cases, regardless of the occurrence of luteal activity. Increased endometrial thickness and dilated glands were recorded in 25% and 34%, respectively, of the monophasic cycles. These findings suggest that 1 mg of mifepristone interferes with endometrial development while allowing biphasic ovarian cycles and regular bleeding. Whether these endometrial alterations are sufficient to prevent implantation remains to be established. The long-term effect of prevention of ovarian cyclicity and the associated increased endometrial growth recorded in some women require further investigation.
Assuntos
Anticoncepcionais Orais Sintéticos/administração & dosagem , Mifepristona/administração & dosagem , Reprodução/efeitos dos fármacos , Adulto , Muco do Colo Uterino/efeitos dos fármacos , Muco do Colo Uterino/fisiologia , Anticoncepcionais Orais Sintéticos/efeitos adversos , Anticoncepcionais Orais Sintéticos/farmacologia , Relação Dose-Resposta a Droga , Endométrio/efeitos dos fármacos , Endométrio/crescimento & desenvolvimento , Feminino , Humanos , Ciclo Menstrual/efeitos dos fármacos , Ciclo Menstrual/fisiologia , Mifepristona/efeitos adversos , Mifepristona/farmacologia , Ovário/efeitos dos fármacos , Ovário/fisiologia , Fatores de TempoRESUMO
OBJECTIVES: To establish criteria, evident soon after birth, that predict long-term outcome of neonates with spinal cord injury (SCI) at birth. DESIGN: Retrospective case-series. SETTING: Five Canadian regional neonatal tertiary care centers. PATIENTS: Consecutive samples of patients referred to five centers for a total of 22 subjects, in whom SCI was diagnosed during life. Sites of lesions were above the fourth cervical vertebrae (n = 14), at the fourth cervical to the fourth thoracic vertebrae (n = 6), and at the thoracolumbar region (n = 2). MEASUREMENTS AND MAIN RESULTS: All 14 patients with upper cervical SCI had cephalic presentations, whereas all 6 patients with cervicothoracic SCI had breech presentations (p < 0.0001). The site and extent of lesion were best diagnosed by clinico-imaging correlations. Ultrasonography appeared to be the most useful imaging study. In patients with upper cervical SCI who had no coexistent central nervous system abnormality associated with early death, long-term outcome in survivors (dependency on mechanical ventilation and on aids for upper limb activity and for ambulation) was best predicted by age when breathing was first observed and by rate of recovery of limb motor function in the first 3 months. The presence of breathing movements on day 1 (n = 2) was associated with mild disability. The absence of breathing movements on day 1 and little or no recovery of motor function in the first 3 months was associated with permanent total dependency on mechanical ventilation and severe quadriplegia (n = 5). Apnea on day 1 and intermediate recovery rates in the first 3 months was associated with variable long-term prognoses (n = 3).
Assuntos
Traumatismos do Nascimento/diagnóstico , Traumatismos da Medula Espinal/diagnóstico , Traumatismos do Nascimento/complicações , Traumatismos do Nascimento/diagnóstico por imagem , Eletromiografia , Feminino , Seguimentos , Humanos , Recém-Nascido , Imageamento por Ressonância Magnética , Masculino , Mielografia , Valor Preditivo dos Testes , Prognóstico , Estudos Retrospectivos , Traumatismos da Medula Espinal/complicações , Traumatismos da Medula Espinal/diagnóstico por imagem , Tomografia Computadorizada por Raios X , UltrassonografiaRESUMO
A multicentered study was undertaken at three institutions in Hungary, Mexico and Thailand in women of reproductive age to evaluate the effects of full and half doses of HRP112 (depot-medroxyprogesterone acetate (DMPA) plus estradiol cypionate) and DMPA alone on ovarian function, bleeding patterns and HDL-cholesterol levels. Full dose HRP112 contained 25mg DMPA plus 5mg, of estradiol cypionate and the half dose, 12.5mg DMPA plus 2.5mg of estradiol cypionate. The full and half dose DMPA were 25 and 12.5mg respectively. In all, 88 women were recruited in the study and randomized within each centre, to the four treatment groups. Subjects were studied for a control cycle, three one-month injection intervals and followed-up for a further two months. Serum concentrations of estradiol, progesterone and medroxyprogesterone acetate were determined three times a week during the third injection interval and during the two months of follow-up. While the results from all centres indicated that the four preparations were all effective in inhibiting ovulation for at least one month, there were marked between centre differences in pharmacokinetic profiles. More regular bleeding patterns were observed in women who received the estrogen-progestogen combination preparations than in those who received DMPA alone.
Assuntos
Anticoncepcionais Femininos/farmacocinética , Estradiol/análogos & derivados , Medroxiprogesterona/análogos & derivados , Adolescente , Adulto , HDL-Colesterol/sangue , Ensaios Clínicos como Assunto , Anticoncepcionais Femininos/administração & dosagem , Anticoncepcionais Femininos/efeitos adversos , Anticoncepcionais Orais Combinados/administração & dosagem , Anticoncepcionais Orais Combinados/efeitos adversos , Anticoncepcionais Orais Combinados/sangue , Anticoncepcionais Orais Combinados/farmacocinética , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Estradiol/administração & dosagem , Estradiol/efeitos adversos , Estradiol/sangue , Estradiol/farmacocinética , Feminino , Humanos , Injeções Intramusculares , Medroxiprogesterona/administração & dosagem , Medroxiprogesterona/efeitos adversos , Medroxiprogesterona/sangue , Medroxiprogesterona/farmacocinética , Acetato de Medroxiprogesterona , Distribuição AleatóriaRESUMO
To assess the possible involvement of arginine vasopressin in the pathogenesis of late hyponatremia in preterm infants, serial measurements of sodium balance, fractional sodium excretion, plasma and urine osmolality and sodium concentration, and urinary aldosterone and arginine vasopressin excretion were performed at weekly intervals in nine healthy preterm infants. During the course of late hyponatremia, there was a significant increase in urinary aldosterone and arginine vasopressin excretion, from 0.94 +/- 0.16 to 4.30 +/- 0.76 micrograms/day and from 0.38 +/- 0.08 to 1.19 +/- 0.26 ng/day, respectively, from the first to the fourth to fifth weeks. A significant negative correlation was found between fractional sodium excretion and urinary aldosterone excretion. Aldosterone excretion, however, correlated positively with urinary arginine vasopressin excretion in seven of the nine infants. The parallel increase in urinary aldosterone and arginine vasopressin excretion in salt-losing premature infants may occur in response to the protracted contraction of the extracellular fluid compartment, and may contribute to the restoration of volume in the body fluid compartments and to the development of late hyponatremia.