RESUMEN
We describe a novel method of single-shot trap frequency measurement for a confined Bose-Einstein Condensate, which uses an atom laser to repeatedly sample the mean velocity of trap oscillations as a function of time. The method is able to determine the trap frequency to an accuracy of 39 ppm (16 mHz) in a single experimental realization, improving on the literature by a factor of three. Further, we show that by employing a reconstructive aliasing approach our method can be applied to trap frequencies more than a factor of 3 greater than the sampling frequency.
RESUMEN
Nitric oxide (NO) has been implicated as a signalling molecule in many cellular processes. As nitric oxide synthase 2 (NOS-2) is the main isoform expressed in mouse decidua and metrial gland, mice with a targeted disruption of the gene encoding NOS-2 were used to determine the potential roles of this enzyme during pregnancy. Reproductive success and the morphology of implantation sites throughout pregnancy were compared in NOS-2 deficient (NOS-2-/-) and wild-type (WT) mice. Although there were no significant differences in the duration of gestation or birth weight, NOS-2-/- mice had significantly fewer viable embryos at mid-gestation and delivered smaller litters than did WT mice. Histological sections of uteroplacental units from WT and NOS-2-/- mice were compared to establish the mechanisms underlying the loss of fetuses. No morphological differences were observed on day 6 or day 8 of gestation, indicating that implantation and early development of implantation sites were unaffected by the absence of NOS-2. However, by mid-gestation, decidua of NOS-2-/- mice had reduced cellularity and their decidual arteries had abnormally thickened walls. These observations were quantified by morphometric measurements, which showed a significant reduction in decidual cellular area and a significant increase in the blood vessel wall:lumen ratio in NOS-2-/- mice. The increase in the thickness of the blood vessel walls was not due to abnormal cellular infiltration or to altered expression of alpha-actin in vascular smooth muscle. These results indicate that NOS-2 has a functional role in the maintenance of decidual cellular integrity and development of appropriate uterine vasculature, and may play a supportive role in promoting embryo survival.
Asunto(s)
Decidua/irrigación sanguínea , Decidua/patología , Óxido Nítrico Sintasa/genética , Óxido Nítrico/fisiología , Preñez/metabolismo , Actinas/análisis , Animales , Arterias/patología , Decidua/química , Ensayo de Inmunoadsorción Enzimática/métodos , Femenino , Muerte Fetal , Edad Gestacional , Histocitoquímica/métodos , Immunoblotting/métodos , Inmunohistoquímica/métodos , Interferón gamma/análisis , Queratinas/análisis , Tamaño de la Camada , Ratones , Ratones Noqueados , NADPH Deshidrogenasa/análisis , Óxido Nítrico Sintasa de Tipo II , Embarazo , ARN Mensajero/análisisRESUMEN
In species with hemochorial placentation, which includes humans, mice and rats, antigen-specific T and B lymphocytes which are responsible for acquired immunity are virtually absent from the maternal-fetal interface. In contrast, non-antigen specific natural killer cells and macrophages which provide innate immunity are abundant and highly specialized. Autocrine/paracrine factors such as steroid and polypeptide hormones, prostaglandins and anti-inflammatory cytokines that are present in the uterine environment during pregnancy re-program their secretory profiles. Recent studies using transgenic mice and other approaches indicate that these environmentally modified leukocytes have major pregnancy-associated functions that include facilitation of implantation, modulation of the maternal uterine vasculature, supply of growth factors to the placenta, promotion of trophoblast differentiation and facilitation of parturition.
Asunto(s)
Leucocitos/fisiología , Útero/citología , Animales , Citocinas/genética , Citocinas/fisiología , Femenino , Humanos , Intercambio Materno-Fetal/genética , Intercambio Materno-Fetal/fisiología , Ratones , Ratones Transgénicos , Placenta/citología , Placenta/fisiología , Embarazo , Receptores de Factores de Crecimiento/genética , Receptores de Factores de Crecimiento/fisiología , Útero/irrigación sanguíneaRESUMEN
In human, mouse, and rat pregnancy, maternal NK cells accumulate and differentiate at implantation sites. These cells, termed uterine NK (uNK) cells, express NO synthase (NOS)-2 and develop cytolytic molecules such as perforin and granzymes during differentiation in situ. In this study, relationships between expression of the NOS-2 gene, uNK cell population density and tissue distribution, and synthesis of perforin were investigated. Uteri from wild-type (WT) and NOS-2-/- mice were collected at gestation days (g.d.) 8, 10, 12, 14, and 16 (n, >2/g.d.). Histochemical staining failed to reveal any differences between the population densities or tissue distributions of uNK cells in WT and NOS-2-/- uteri at any stage of gestation. By contrast, immunohistochemical staining with anti-perforin Abs demonstrated significantly fewer perforin-positive uNK cells in two uterine compartments of NOS-2-/- mice in comparison to the same compartments in WT mouse uteri. Perforin-positive uNK cells were reduced in NOS-2-/- metrial glands at g.d. 8, 10, and 12 and in decidua basalis at g.d. 12 (p < 0.05). Analysis of perforin protein by immunoblotting confirmed this observation. Northern blot hybridization studies showed that loss of perforin protein in NOS-2-/- mice was accompanied by decreased steady-state levels of perforin mRNA. These results demonstrate that migration of uNK cells into the uterus, selection of residency sites, and proliferation in situ are independent of NOS-2. By contrast, their differentiation, including transcription and translation of the cytotoxic molecule perforin, was shown to rely on normal expression of the NOS-2 gene.