Problema de la deuda: gestación, desarrollo, crisis y perspectiva = Problem of the external debt: gestation, development, crisis and prospects = Le probleme de la dette: gestation, evolution, crise et perspectives

Incluye Bibliografía

Problema de la deuda: gestación, desarrollo, crisis y perspectiva = Problem of the external debt: gestation, development, crisis and prospects

Incluye Bibliografía

Relationships between growth of the preovulatory follicle and gestation success in lactating dairy cows

This report summarizes three studies conducted with lactating dairy cows aiming to increase pregnancy rates to fixed time artificial insemination (TAI) protocols. Experiment 1 was designed to determine if changing the timing of PGF2 alpha treatment during an E2/P4-based program would affect fertility to TAI or fixed-time embryo transfer (TET). In experiment 2, pregnancy rates to AI were compared following synchronized ovulation using two protocols that have been developed to reduce the period between follicular wave emergence and TAI. The Ovsynch-type protocol utilizes GnRH to synchronize the follicular wave by inducing ovulation of a dominant follicle at the beginning of the protocol, and to synchronize ovulation at the end of the protocol allowing TAI. In contrast, E2/P4-based protocols utilize E2 products in the presence of P4 to induce atresia of antral follicles and synchronize emergence of a new follicular wave. At the end of E2/P4-based protocol another E2 treatment in the absence of P4 is used to induce LH release and synchronize ovulation and allow TAI. Experiment 3 was designed to determine whether increasing the length time interval with reduced circulating P4 (proestrus) would increase fertility in a TAI program that utilized E2 and P4 to synchronize ovulation of cycling, lactating dairy cows. The overall conclusions are that circulating concentrations of progesterone and estradiol prior to and circulating concentrations of progesterone following ovulation can affect fertility in cattle. In addition, small increases in P4 concentrations near the time of AI, due to lack of complete CL regression, result in reductions in fertility. Earlier treatment with PGF2 alpha should allow greater time for CL regression, an increase in estradiol and subsequent reductions in circulating P4 that could be critical for fertility. Optimization of follicle size in TAI programs is clearly an intricate balance between oocyte quality, adequate circulating E2 near AI, and adequate circulating P4 after AI.

Genetic analysis for gestation length, birth weight, weaning weight, and accumulated productivity in Nellore beef cattle

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Expression of estrus modifies the gene expression profile in reproductive tissues on Day 19 of gestation in beef cows

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of age and endometrial degenerative changes on uterine blood flow during early gestation in mares

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uterine vascular perfusion and spectral-doppler measurements during early gestation in mares: new concepts of evaluation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Porphyromonas gingivalis infection at different gestation periods on fetus development and cytokines profile

Oral Diseases (2012) 18, 648654 Aim: Infective agents may affect pregnancy outcomes by deregulating homeostasis. Objectives: The effects of Porphyromonas gingivalis infection before and at different gestation periods were evaluated. Materials and Methods: Wistar rats infected via subcutaneous with P. gingivalis W83, one week before mating (BM), days 1 (PR1) and 11 of gestation (PR11), and controls were evaluated, and samples were obtained at the end of gestation. P. gingivalis was detected by PCR. Cytokine was determined by ELISA. Results: Infected rats had lower maternal gain of weight. Implantation was not observed in 2/12 BM rats. PR11 presented more fetal-placental resorptions and lower placenta/fetus weight than controls. P. gingivalis was detected in placenta and fetus. IL-6 and TNF-a levels were higher in placenta and serum of infected groups, except for TNF-a in placenta of PR1. IL-1 beta levels were higher in placenta of PR11, but lower in serum and placenta of PR1. There were no differences in IL-10 and PGE2 concentrations among the groups (P < 0.05). Conclusions: The experimental infection by P. gingivalis resulted in alterations in the gestational pattern and in fetal development. The consequences of infection at mid-gestation were more severe than at the beginning, possibly due to the induction of pro-inflammatory cytokines in the fetal compartment.

Morphology and Involution of the Yolk Sac during Early Gestation Bovine (Bos indicus)

Background: The bovine yolk sac derives from visceral endoderm and its development occurs between days 18-23 of gestation. The study of this membrane is important for comparative data and has already been performed in rodents, sheep and in cattle, especially Bos taunts. In species Bos indicus the yolk sac has not quite been studied and is believed that there are morphological differences between these species. The yolk sac undergoes a process of involution and degeneration during embryonic development and none vestige of it is found in late gestation. The period in which occurs the involution of the yolk sac coincides with the period of increased pregnancy loss in cattle, and changes in the morphology of this membrane may indicate the reasons for such high loss rates. Thus, considering that the yolk sac is important for embryonic circulation and metabolic transmission, besides participating actively in the process of cattle placentation, this study aimed characterize morphologically the involution of the bovine yolk sac. Materials, Methods & Results: The early gestational period was determined between days 20 and 70 post-insemination (p.i), according to the exterior characteristics of embryo/fetus. For macroscopic analyzes the uterus was dissected to expose the fetal membranes and subsequently the embryo/fetus was photographed. The samples were fixed for light microscopy and transmission electron microscopy. The yolk sac that emerges from the ventral part of the embryo was prominent and composed by a central part with two thin peripheral projections of different lengths. The bovine yolk sac with about 9 cm on day 25 p. i. of pregnancy permanently decreased its total length during this study. Histologically, the yolk sac is composed of three cell layers: the mesothelium, the mesenchyme and the endoderm. In mesenchyme are found blood islets. In the endoderm are formed cells invaginations toward the mesenchyme originating small canaliculi. The ultrastructure of yolk cells presented many mitochondria, rough endoplasmic reticulum, vesicles, euchromatin and the presence of two nucleoli, Discussion: The real first blood circulation in the bovine is attached with the development of yolk sac, differently from other membranes, such as the corium, that does not present evidence of vascularization by the age of 20-30 days. The erythroblasts found in the yolk sac are related to vasculogenesis and the process of differentiation of blood cells during the erythropoiesis. It could be observed on the histology of the yolk sac, in embryos of 30-50 days old, the presence of canaliculi and small folds of the epithelium. The canaliculi collapse is associated with the degeneration of the endoderm wall of the yolk sac. The organelles present in the endoderm cells of the yolk sac are associated with the function of protein metabolism and in the exchange of substances between the mesenchyme and the mesothelium, For these findings, could be observed that the yolk sac epithelium is found active until the 50th day of gestation, and thereafter regresses. However, remnants of this membrane may be present until the 70th day, These features may represent a presence of an active chorionvitelline placenta in this period responsible for the maintenance of pregnancy whereas the chorioallantoic placenta is not definitively established.

Derivation and characterization of progenitor stem cells from canine allantois and amniotic fluids at the third trimester of gestation

Fetal tissues are frequently discarded before (amniocentesis) or after birth, which both facilitates stem cell access and helps to overcome ethical concerns. In the present study, we aimed to isolate and characterize stem cells from the allantoic and amniotic fluids (ALF; AMF) of third trimester canine fetuses. This gestation age has not been previously explored for stem cells isolation. The gestational age, cell culture conditions and method of isolation used in this study allowed for the establishment and efficient expansion of ALF and AMF cells. We showed that the majority of ALF and ALF cells express the stem cell markers, such as vimentin, nestin and cytokeratin 18 (CK18). Under appropriate culture conditions AMF derived cells can undergo differentiation into osteogenic, adipogenic, chondrogenic and neuron-like lineages. ALF derived cells showed adipogenic, and chondrogenic potential. Therefore, ALF and AMF cells derived at the third gestation trimester can be qualified as progenitor stem cells, accordingly referred as (alantoic fluid progenitor/stem) ALF PS cells and (amniotic fluid progenitor/stem) AMF PS cells. (C) 2012 Elsevier Ltd. All rights reserved.

Maternal immune activation in late gestation enhances locomotor response to acute but not chronic amphetamine treatment in male mice offspring: Role of the D1 receptor

Exposure to elevated levels of maternal cytokines can lead to functional abnormalities of the dopaminergic system in the adult offspring, including enhanced amphetamine (AMPH)-induced locomotion. Therefore, it seems reasonable to consider that offspring of challenged mothers would behave differently in models of addictive behavior, such as behavioral sensitization. Thus, we sought to evaluate the effects of prenatal exposure to lipopolysaccharide (LPS) on the locomotor response to acute and chronic AMPH treatment in male mice offspring. For this purpose, LPS (Escherichia coli 0127:B8; 120 mu g/kg) was administered intraperitoneally to pregnant Swiss mice on gestational day 17. At adulthood, male offspring were studied under one of the following conditions: (1) locomotor response to acute AMPH treatment (2.5 or 5.0 mg/kg) in an open field test; (2) behavioral sensitization paradigm, which consists of a daily injection of AMPH (1.0 mg/kg) for 10 days and observation of locomotion in the open field on days 1, 5, 10 (development phase), 15 and 17 (expression phase). The LPS stimulated offspring showed enhancement of the locomotor-stimulant effect after an acute AMPH challenge in comparison to baseline and saline pre-treated mice. They also showed development of behavioral sensitization earlier than the saline pre-treated group, although no changes between saline and LPS pre-treated groups were observed on development or expression of locomotor behavioral sensitization to AMPH. Furthermore, there was up-regulation of D1 receptor protein level within striatum in the LPS-stimulated offspring which was strongly correlated with increased grooming behavior. Taken together, our results indicate that motor and dopaminergic alterations caused by maternal immune activation are restricted to the acute AMPH challenge, mostly due to up-regulation of the D1 receptor within the mesolimbic and nigrostriatal pathways, but no locomotor differences were observed for behavioral sensitization to AMPH. (C) 2012 Elsevier B.V. All rights reserved.

Time lags of the kilohertz quasi-periodic oscillations in the low-mass X-ray binaries 4U 1608−52 and 4U 1636−53

We studied the energy and frequency dependence of the Fourier time lags and intrinsic coherence of the kilohertz quasi-periodic oscillations (kHz QPOs) in the neutron-star lowmass X-ray binaries 4U 1608−52 and 4U 1636−53, using a large data set obtained with the Rossi X-ray Timing Explorer. We confirmed that, in both sources, the time lags of the lower kHz QPO are soft and their magnitude increases with energy. We also found that: (i) In 4U 1636−53, the soft lags of the lower kHz QPO remain constant at∼30 μs in the QPO frequency range 500–850 Hz, and decrease to ∼10 μs when the QPO frequency increases further. In 4U 1608−52, the soft lags of the lower kHz QPO remain constant at 40 μs up to 800 Hz, the highest frequency reached by this QPO in our data. (ii) In both sources, the time lags of the upper kHz QPO are hard, independent of energy or frequency and inconsistent with the soft lags of the lower kHz QPO. (iii) In both sources the intrinsic coherence of the lower kHz QPO remains constant at ∼0.6 between 5 and 12 keV, and drops to zero above that energy. The intrinsic coherence of the upper kHz QPO is consistent with being zero across the full energy range. (iv) In 4U 1636−53, the intrinsic coherence of the lower kHz QPO increases from ∼0 at ∼600 Hz to ∼1, and it decreases to ∼0.5 at 920 Hz; in 4U 1608−52, the intrinsic coherence is consistent with the same trend. (v) In both sources the intrinsic coherence of the upper kHz QPO is consistent with zero over the full frequency range of the QPO, except in 4U 1636−53 between 700 and 900 Hz where the intrinsic coherence marginally increases. We discuss our results in the context of scenarios in which the soft lags are either due to reflection off the accretion disc or up-/down-scattering in a hot medium close to the neutron star. We finally explore the connection between, on one hand the time lags and the intrinsic coherence of the kHz QPOs, and on the other the QPOs’ amplitude and quality factor in these two sources.

Perinatal care at the limit of viability between 22 and 26 completed weeks of gestation in Switzerland. 2011 revision of the Swiss recommendations

Perinatal care of pregnant women at high risk for preterm delivery and of preterm infants born at the limit of viability (22-26 completed weeks of gestation) requires a multidisciplinary approach by an experienced perinatal team. Limited precision in the determination of both gestational age and foetal weight, as well as biological variability may significantly affect the course of action chosen in individual cases. The decisions that must be taken with the pregnant women and on behalf of the preterm infant in this context are complex and have far-reaching consequences. When counselling pregnant women and their partners, neonatologists and obstetricians should provide them with comprehensive information in a sensitive and supportive way to build a basis of trust. The decisions are developed in a continuing dialogue between all parties involved (physicians, midwives, nursing staff and parents) with the principal aim to find solutions that are in the infant's and pregnant woman's best interest. Knowledge of current gestational age-specific mortality and morbidity rates and how they are modified by prenatally known prognostic factors (estimated foetal weight, sex, exposure or nonexposure to antenatal corticosteroids, single or multiple births) as well as the application of accepted ethical principles form the basis for responsible decision-making. Communication between all parties involved plays a central role. The members of the interdisciplinary working group suggest that the care of preterm infants with a gestational age between 22 0/7 and 23 6/7 weeks should generally be limited to palliative care. Obstetric interventions for foetal indications such as Caesarean section delivery are usually not indicated. In selected cases, for example, after 23 weeks of pregnancy have been completed and several of the above mentioned prenatally known prognostic factors are favourable or well informed parents insist on the initiation of life-sustaining therapies, active obstetric interventions for foetal indications and provisional intensive care of the neonate may be reasonable. In preterm infants with a gestational age between 24 0/7 and 24 6/7 weeks, it can be difficult to determine whether the burden of obstetric interventions and neonatal intensive care is justified given the limited chances of success of such a therapy. In such cases, the individual constellation of prenatally known factors which impact on prognosis can be helpful in the decision making process with the parents. In preterm infants with a gestational age between 25 0/7 and 25 6/7 weeks, foetal surveillance, obstetric interventions for foetal indications and neonatal intensive care measures are generally indicated. However, if several prenatally known prognostic factors are unfavourable and the parents agree, primary non-intervention and neonatal palliative care can be considered. All pregnant women with threatening preterm delivery or premature rupture of membranes at the limit of viability must be transferred to a perinatal centre with a level III neonatal intensive care unit no later than 23 0/7 weeks of gestation, unless emergency delivery is indicated. An experienced neonatology team should be involved in all deliveries that take place after 23 0/7 weeks of gestation to help to decide together with the parents if the initiation of intensive care measures appears to be appropriate or if preference should be given to palliative care (i.e., primary non-intervention). In doubtful situations, it can be reasonable to initiate intensive care and to admit the preterm infant to a neonatal intensive care unit (i.e., provisional intensive care). The infant's clinical evolution and additional discussions with the parents will help to clarify whether the life-sustaining therapies should be continued or withdrawn. Life support is continued as long as there is reasonable hope for survival and the infant's burden of intensive care is acceptable. If, on the other hand, the health car...