Thermodynamic and Kinetic Fragility of Freon 113: The Most Fragile Plastic Crystal.

We present a dynamic and thermodynamic study of the orientational glass former Freon 113 (1,1,2-trichloro-1,2,2-trifluoroethane, CCl_{2}F-CClF_{2}) in order to analyze its kinetic and thermodynamic fragilities. Freon 113 displays internal molecular degrees of freedom that promote a complex energy landscape. Experimental specific heat and its microscopic origin, the vibrational density of states from inelastic neutron scattering, together with the orientational dynamics obtained by means of dielectric spectroscopy have revealed the highest fragility value, both thermodynamic and kinetic, found for this orientational glass former. The excess in both Debye-reduced specific heat and density of states (boson peak) evidences the existence of glassy low-energy excitations. We demonstrate that early proposed correlations between the boson peak and the Debye specific heat value are elusive as revealed by the clear counterexample of the studied case.

Implanted muon spin spectroscopy on 2-O-adamantane: a model system that mimics the liquid[Formula: see text]glasslike transitions.

The transition taking place between two metastable phases in 2-O-adamantane, namely the [Formula: see text] cubic, rotator phase and the lower temperature P21/c, Z = 4 substitutionally disordered crystal is studied by means of muon spin rotation and relaxation techniques. Measurements carried out under zero, weak transverse and longitudinal fields reveal a temperature dependence of the relaxation parameters strikingly similar to those exhibited by structural glass[Formula: see text]liquid transitions (Bermejo et al 2004 Phys. Rev. B 70 214202; Cabrillo et al 2003 Phys. Rev. B 67 184201). The observed behaviour manifests itself as a square root singularity in the relaxation rates pointing towards some critical temperature which for amorphous systems is located some tens of degrees above that shown as the characteristic transition temperature if studied by thermodynamic means. The implications of such findings in the context of current theoretical approaches concerning the canonical liquid-glass transition are discussed.

Orientational relaxations in solid (1,1,2,2)tetrachloroethane.

We employ dielectric spectroscopy and molecular dynamic simulations to investigate the dipolar dynamics in the orientationally disordered solid phase of (1,1,2,2)tetrachloroethane. Three distinct orientational dynamics are observed as separate dielectric loss features, all characterized by a simply activated temperature dependence. The slower process, associated to a glassy transition at 156 ± 1 K, corresponds to a cooperative motion by which each molecule rotates by 180° around the molecular symmetry axis through an intermediate state in which the symmetry axis is oriented roughly orthogonally to the initial and final states. Of the other two dipolar relaxations, the intermediate one is the Johari-Goldstein precursor relaxation of the cooperative dynamics, while the fastest process corresponds to an orientational fluctuation of single molecules into a higher-energy orientation. The Kirkwood correlation factor of the cooperative relaxation is of the order of one tenth, indicating that the molecular dipoles maintain on average a strong antiparallel alignment during their collective motion. These findings show that the combination of dielectric spectroscopy and molecular simulations allows studying in great detail the orientational dynamics in molecular solids.

Structure and reorientational dynamics of 1-F-adamantane.

The polymorphism and the dynamics of a simple rigid molecule (1-fluoro-adamantane) have been studied by means of X-ray powder diffraction and broadband dielectric spectroscopy. At temperatures below the melting point, the molecule forms an orientationally disordered Phase I with a cubic-centered structure (Phase I, Fm3¯m, Z = 4). This phase possesses eight equilibrium positions for the fluorine atom, with equal occupancy factors of 1/8. A solid-solid phase transition to a low-temperature tetragonal phase (Phase II, P4¯2(1)c, Z = 2) reduces the statistical disorder to only four possible equivalent sites for the fluorine atom, with fractional occupancies of 1/4. The dynamics has been rationalized under the constraints imposed by the space group of the crystal structure determined by powder X-ray diffraction. The dielectric spectroscopy study reveals that the statistical disorder in Phase II is dynamic in character and is associated with reorientational jumps along the two- and three-fold axes. In the dielectric loss spectra, the cooperative (α) relaxation exhibits a shoulder on the high-frequency side. This remarkable finding clearly reveals the existence of two intrinsic reorientational processes associated with the exchange of the F atom along the four sites. In addition to such "bimodal" relaxation, a secondary Johari-Goldstein relaxation is detected at lower temperatures.

Molecular diffusion and dc conductivity perfectly correlated with molecular rotational dynamics in a plastic crystalline electrolyte.

We probe the ionic conduction and the molecular dynamics in a pure and lithium-salt doped dinitrile molecular plastic crystal. While the diffusion of the Li(+) ions is decoupled from the molecular reorientational dynamics, in the undoped plastic crystal the temperature dependence of the mobility of dinitrile ions and thus of the conductivity is virtually identical to that of on-site molecular rotations. The undoped material is found to obey the Walden and Stokes-Einstein rules typical of ideal liquid electrolytes, implying that an effective viscosity against diffusion can be defined even for a plastic crystalline phase. These surprising results, never reported before in a translationally ordered solid, indicate that in this dinitrile plastic crystalline material the timescale of translational diffusion is perfectly correlated with that of the purely reorientational on-site dynamics.

Effect of Sildenafil on Pre-Eclampsia-Like Mouse Model Induced By L-Name.

N(omega)-nitro-L-arginine methyl ester (L-NAME) decreases the vasodilator effect of nitric oxide (NO) and induces pre-eclampsia in mouse. Sildenafil inhibits the degradation of nitric oxide and increases vasodilation. This study aimed to determine the effects of sildenafil citrate on angiogenesis and oxidative stress at the maternal foetal interface on pre-eclampsia-like mouse model induced by L-NAME. Twenty pregnant mice were divided into four groups: (i) vehicle control; (ii) L-NAME; (iii) sildenafil; (4) L-NAME+sildenafil. L-NAME was administered from day 7 of pregnancy and sildenafil from day 8 until day 16; animals were euthanized on day 17. Placental and foetal sizes and weights were measured; lipid peroxide levels and catalase activity in placental homogenates were determined, and placental vascular endothelia were identified by lectin-histochemistry using BSA-I lectin. Western blot analysis was used to determine VEGF expression in placental homogenates. No changes were seen in placental and foetal development in mice with normal pregnancies treated with sildenafil. Treatments with L-NAME reduced significantly the placental weight and average height and decreased the percentage of the endothelial surface. These alterations may be mediated by the reduction of NO levels in trophoblastic cells, due to the inhibitory effect of L-NAME on nitric oxide synthase (NOS) synthesis. This effect was offset by the treatment with sildenafil, with an increase in the percentage of the endothelial surface. In conclusion, our results indicate that treatment with sildenafil on pre-eclampsia mouse model can be used without adverse effects on the concept and its use in the treatment of pre-eclampsia is promising.

Adrenal response of male rats exposed to prenatal stress and early postnatal stimulation.

Stress in pregnant rats caused by chronic immobilization alters the pattern of secretion of corticosterone and modifies the hypothalamic-pituitary-adrenal axis (HPA) of the fetus. Early postnatal handling, however, may reverse the effects of increased secretion of corticosterone. We investigated the effects of prenatal stress and postnatal handling on the activity of the HPA axis of male offspring of stressed female rats. Male 90-day-old rats from four groups were investigated: prenatally stressed animals without postnatal handling, prenatally stressed animals with postnatal handling, unstressed control animals with postnatal handling, and unstressed control animals without postnatal handling. After sacrifice, the adrenal glands were weighed to determine the adrenal-somatic index. Apoptosis was evaluated by TUNEL assay and active caspase-3 expression. We found that the adrenal gland cortex:medulla ratio increased in animals with prenatal stress and that eventually the stress caused apoptosis. Handling newborns to simulate maternal activity ameliorated some of the negative effects of prenatal stress.

The effect of chronic stress on prenatal development of the central nervous system.

The survival of developing embryos depends on the control and maintenance of homeostasis. Stress caused by chronic immobilization during pregnancy in rats may alter the normal development of the nervous system and increase susceptibility to psychiatric disorders. We investigated the effects of chronic stress on cell proliferation in the forebrains of embryos at 12 days of gestation, and in the hippocampus, dentate gyrus and cortex in embryos at 17 and 21 days of gestation. We examined serial sections of the embryonic brains of control and stressed rats at days 12, 17 and 21 of gestation. Brain sections were immunolabeled with anti-PCNA and stereological analysis was performed on 540 images. The results showed no statistical differences on days 12 and 17 of gestation in the proliferation area of the structures studied, whereas on day 21 of gestation, proliferation decreased in the cortex and dentate gyrus of embryos of the stressed group. These changes were related to decreased prolactin and increased corticosterone concentrations in the plasma.

Chronic stress and its effects on adrenal cortex apoptosis in pregnant rats.

The model of chronic intermittent stress by immobilization during pregnancy may produce alterations in the mechanisms that maintain adrenal gland homeostasis. In earlier investigations using this model, significant variations in plasma prolactin and corticosterone levels, and adrenal gland weights were observed. We hypothesized that chronic stress causes changes in apoptosis in the adrenal glands of pregnant rats. We identified and quantified apoptotic cells in the adrenal cortex and examined their ultrastructural characteristics using transmission electron microscopy. Adrenal glands of pregnant rats at gestation days 12, 17 and 21 were studied for control and experimental (stressed) rats. Immunolabelling techniques, stereological analysis and image quantification of adrenal gland sections were combined to determine differences in apoptosis in the different cell populations of the adrenal cortex. The apoptotic index of the experimental rats showed a significant reduction at gestation day 17, while at days 12 and 21 there were no differences from controls. Moreover, the apoptotic index of the reticular zones in control and experimental animals showed a significant increase compared to the glomerular and fascicular zones at the three gestation times studied. Chronic stress by immobilization reduced the caspase-dependent apoptotic index at gestation day 17, which may be related to variations in plasma concentrations of estrogens and prolactin.

Laparoscopically harvested omental flap for breast reconstruction in Poland syndrome.

BACKGROUND/PURPOSE: Poland syndrome (PS) is a congenital anomaly of the thoracic wall characterised by a variable degree of unilateral agenesis of pectoralis major and minor muscles associated with ipsilateral breast, rib and upper-arm anomalies. In female patients, breast reconstruction is particularly challenging because of cranial pectoralis muscle defects and partial or complete breast agenesis. Different techniques have been used to treat the thoracic anomaly, including the positioning of an implant, fat transfer or latissimus dorsi transposition, but in some cases these techniques are not feasible resulting in a poor reconstruction. METHODS: We present our experience in correction of the chest anomaly of PS in a teenage population by using a pedicled laparoscopically harvested omental flap (LOF) to cover a pectoral or breast prosthesis. Procedures were performed by a surgical team which included experienced plastic surgeons and general paediatric surgeons. Preoperative endocrinological and psychological evaluation helped to determine the best timing for the correction. RESULTS: The technique was adopted in 20 patients aged 14-18 years, affected by the syndrome. In all cases, it was possible to harvest an adequate amount of pedicled omentum laparoscopically. Neither significant complications nor conversions to open surgery occurred. The aesthetic outcome of the LOF technique was, in all cases, a soft, natural-looking breast and a satisfactorily corrected infraclavicular defect. CONCLUSIONS: The LOF technique is a valid alternative to reconstruction in selected PS cases. It provides a satisfactory reconstruction of the breast and pectoral region and corrects the infraclavicular defect by filling in the area. It avoids the invasiveness and morbidity of a latissimus dorsi transposition.

Reproductive response in offspring male rats exposed to prenatal stress and to early postnatal stimulation / Respuestas reproductivas en ratas estresadas prenatalmente, expuestas a estimulación postnatal

Stress in pregnant rats alters the pattern of secretion of corticosterone (COR) and modifies transplacentally hypothalamic-pituitary-adrenal axis (HPA) fetus. Prenatal stress during the critical hypothalamic differentiation is related to decreased fertility of male offspring by an increase in the basal level of COR. This modification could induce long-term changes in the process of apoptosis in the testis. However, early postnatal handling increases maternal behavior and could reverse the effects caused by increased secretion of COR. The aim of this research was to investigate the effects of early postnatal stimulation of male rats prenatal stressed by chronic immobilization during the last two weeks of pregnancy, on the hypothalamic-pituitary-gonadal axis and their relationship with the activity of the HPA. Male Wistar rats 3 month olds, were separated in four groups: (a) prenatally stressed animals by immobilization (IMO), without postnatal stimulation; (b) prenatally stressed animals with postnatal stimulation; (c) control animals without prenatal stress, without postnatal stimulation and (d) control animals without prenatal stress, with postnatal stimulation. In different animals groups plasmatic levels of COR, Testosterone (T) and Luteinizing Hormone (LH) were analyzed. Gonadosomatic index and testicular apoptosis was determined. In conclusion that prenatal stress by IMO increased levels of COR and inhibits the HHG axis obtaining low values of plasmatic LH and T, testicular weight, and induction of apoptosis in testes. On other hand, early postnatal stimulation results in an increase in maternal care to the offspring reversing the effects of prenatal stress on the HPG axis. This effect could be mediated by a mechanism independent of the HPA axis.

El estrés en ratas preñadas altera el patrón de secreción de corticosterona (COR) materna la cual, por vía transplacentaria, produce una alteración del eje Hipotálamo-Hipófiso-Adrenal (HHA) fetal. El estrés prenatal producido durante la etapa crítica de diferenciación hipotalámica, está relacionado con la disminución de la fertilidad en las crías macho, por un aumento en el nivel de COR basal. Esta modificación podría inducir cambios a largo plazo en el proceso de apoptosis testicular. Sin embargo, la estimulación postnatal temprana mejora el comportamiento materno, revirtiendo las alteraciones producidas por el aumento de COR en las crías adultas. El objetivo fue investigar el efecto de la estimulación postnatal temprana sobre el eje Hipotálamo-Hipófiso-Gonadal (HHG) en ratas macho estresadas prenatalmente (EP), por inmovilización crónica durante las dos últimas semanas de la preñez. Se utilizaron crías de 3 meses de edad, que fueron divididas en 4 grupos: (a) individuos EP y sin estimulación postnatal; (b) individuos EP con estimulación postnatal; (c) individuos controles no estresados prenatalmente (CP) y sin estimulación postnatal; y (d) individuos CP con estimulación postnatal. En todos los grupos se midió COR, Testosterona (T) y Hormona Luteinizante (LH). Se determinaron la apoptosis y la Caspasa 3 testicular y el índice gonadosomático. Se concluye que el estrés prenatal por inmovilización aumenta los niveles de COR del eje HHA e inhibe el eje HHG obteniendo valores bajos de LH y T plasmáticas. Se observa disminución del tamaño testicular y aumento de la apoptosis de las células testiculares. Por otro lado, la estimulación postnatal temprana se traduce en un aumento del cuidado materno hacia la cría, lo que revierte los efectos producidos por el estrés prenatal sobre el eje HHG. Este efecto podría estar mediado por algún mecanismo independiente del eje HHA.

Automated three-dimensional coded contrast imaging hysterosalpingo-contrast sonography: feasibility in office tubal patency testing.

OBJECTIVE: To evaluate the feasibility of transvaginal hysterosalpingo-contrast sonography (HyCoSy) with new automated three-dimensional coded contrast imaging (3D-CCI) software in the evaluation of tubal patency and visualization of tubal course. METHODS: Patients undergoing HyCoSy with automated 3D-CCI software were evaluated prospectively. First, to evaluate the feasibility of 3D visualization of tubal course, we performed consecutive volume acquisitions while injecting SonoVue contrast agent. We then performed conventional two-dimensional (2D) real-time HyCoSy to confirm tubal patency status by detection of saline and air bubbles moving through the Fallopian tubes and around the ovaries. We also evaluated visualization with CCI of the contrast agent around the ovaries, side effects and pain during and after the procedure, by visual analog scale (VAS) (ranging from 0 to 10, with 0 corresponding to no pain and 10 corresponding to maximum pain). RESULTS: A total of 126 patients (252 tubes) underwent 3D-CCI HyCoSy followed by 2D real-time HyCoSy. According to the final 2D real-time evaluation, bilateral tubal patency was observed in 111 patients, bilateral tubal occlusion in four patients and unilateral tubal patency in 11 patients. The concordance rate for tubal patency status between the first 3D volume acquisition and the final 2D real-time evaluation was 84% and that between the second 3D volume acquisition and the final 2D real-time evaluation was 97%. A pain score >5 on VAS was recorded in 58% of patients during the procedure, but a pain score ≤ 5 was recorded in 85.7% of patients immediately after the procedure. CONCLUSIONS: HyCoSy with automated 3D-CCI technology retains the advantages of conventional 2D HyCoSy while overcoming the disadvantages. 2D HyCoSy is highly observer-dependent and is only accurate in the hands of experienced investigators; by obtaining a volume of the uterus and tubes, automated 3D volume acquisition permits visualization of the tubes in the coronal view and of the tubal course in 3D space, and should allow less experienced operators to evaluate tubal patency status relatively easily.

Adenomyosis: three-dimensional sonographic findings of the junctional zone and correlation with histology.

OBJECTIVE: To correlate with histopathological features the adenomyosis-induced morphological alterations of the outer myometrium and the inner myometrium ('junctional zone', JZ) detectable on two- (2D) and three-dimensional (3D) transvaginal ultrasound imaging (TVS), and to evaluate their diagnostic accuracy for adenomyosis. METHODS: Premenopausal patients scheduled for hysterectomy for benign pathology were enrolled in this prospective study. Before hysterectomy all patients underwent detailed 2D-TVS and 3D volume acquisition of the entire uterus. The major sonographic signs of adenomyosis were noted. On the multiplanar coronal and longitudinal views obtained by 3D-TVS we measured the maximum and minimum JZ thickness from the basal endometrium to the internal layer of the outer myometrium (JZmax, JZmin), the difference between them (JZdif = JZmax - JZmin) and the ratio JZmax/total maximum myometrial thickness. Results of these examinations were correlated blindly to the presence of adenomyosis on histological specimens. RESULTS: A total of 72 premenopausal patients underwent 2D- and 3D-TVS before hysterectomy. The histological prevalence of adenomyosis was 44.4% (32/72 patients). In diagnosing adenomyosis, the presence of myometrial cysts was the most specific 2D-TVS feature (specificity, 98%; accuracy, 78%) and heterogeneous myometrium was the most sensitive (sensitivity, 88%; accuracy, 75%). The 3D-TVS markers JZdif ≥ 4 mm and JZ infiltration and distortion had high sensitivity (88%) and the best accuracy (85% and 82%, respectively). For 2D-TVS and 3D-TVS, respectively, the overall accuracy for diagnosis of adenomyosis was 83% and 89%, the sensitivity was 75% and 91%, the specificity was 90% and 88%, the positive predictive value was 86% and 85% and the negative predictive value was 82% and 92%. CONCLUSIONS: The coronal section of the uterus obtained by 3D-TVS permits accurate evaluation and measurement of the JZ, and its alteration has good diagnostic accuracy for adenomyosis.

Scaling the dynamics of orientationally disordered mixed crystals.

The evolution of the primary relaxation time of orientationally disordered (OD) mixed crystals [(CH(3))(2)C(CH(2)OH)(2)](1-X)[(CH(3))C(CH(2)OH)(3)](X), with 0 < X < or = 0.5, on approaching the glass temperature (T(g)) is discussed. The application of the distortion-sensitive, derivative-based procedure revealed a limited adequacy of the Vogel-Fulcher-Tammann parametrization and a superiority of the critical-like description tau proportional to (T - T(C))(-phi(') ), phi(') = 9-11.5, and T(C) approximately T(g) - 10 K. Basing on these results as well as that of Drozd-Rzoska et al. [J. Chem. Phys. 129, 184509 (2008)] the question arises whether such behavior may be suggested as the optimal universal pattern for dynamics in vitrifying OD crystals (plastic crystals). The obtained behavior is in fair agreement with the dynamic scaling model (DSM) [R. H. Colby, Phys. Rev. E 61, 1783 (2000)], originally proposed for vitrifying molecular liquids and polymers. The application of DSM made it possible to estimate the size of the cooperatively rearranging regions ("heterogeneities") in OD phases near T(g).

Absorbable stabilisation of the bar in minimally invasive repair of pectus excavatum.

INTRODUCTION: The minimally invasive repair of pectus excavatum has become the preferred technique in most centres. One of the most important technical points for the final result is stabilisation of the bar, usually obtained by one or two metal stabilisers. Recently, long-term absorbable stabilisers have become available (LactoSorb, Biomet, Jacksonville, FL, USA). Made of poly-L-lactic and polyglycolic acid, they have been introduced with the aim of reducing local discomfort and making removal of the bar easier. Their efficacy for the stabilisation of the bar has not been proved yet. In this paper we compare the surgical outcome in two groups of patients, one treated with metallic and the other with absorbable stabilisers. MATERIAL AND METHODS: A total of 280 patients underwent pectus excavatum repair using a Nuss technique in two centres. In 194 patients (group 1), operated on since 2001, the metallic stabiliser was used. In 86 patients (group 2), operated on since February 2007, the LactoSorb stabiliser was preferred. We compared both groups in terms of surgical details, local symptoms or complications, and bar instability rate. RESULTS: The surgical technique for the stabilisation of the bar was identical in both groups, but in group 1 the stabiliser was fastened to the bar with a steel wire, while in group 2 polyglycolic sutures were used. No differences in local discomfort or postoperative pain were observed between the groups. The LactoSorb stabiliser was palpable for at least 6-9 months, and progressively disappeared at 9-12 months. In group 1 we observed 6 local complications. In particular, two patients presented with infection, one of them associated with a skin lesion and opening over the metallic stabiliser (revision of the wound was performed). Another patient developed a thoracic wall haematoma after suffering a trauma over the metallic stabiliser, 13 months after operation. Three patients developed a seroma. In group 2 we observed 3 subcutaneous swellings at the site of the LactoSorb stabiliser at 6, 8 and 9 months after the operation. We did not observe either skin lesions or infections. In the group with metallic stabiliser, 3 patients (1.5 %) had bar dislocation, while we did not observe bar instability in the group with LactoSorb stabiliser. CONCLUSIONS: LactoSorb stabiliser is safe and effective for stabilising the bar in pectus surgery. We suggest its routine use as it appears to be less traumatic and could make bar removal easier.

Ultrastructural study of spermatogenesis in Eisenia foetida (Annelida, Oligochaeta)

La espermatogénesis y ultraestructura del espermatozoide siguen un patrón común en los oligoquetos terrestres, sin embargo, muchos de sus aspectos son distintivos de cada especie y tienen importancia para los estudios filogenéticos y taxonómicos. Con el objetivo de profundizar sobre aspectos de la espermatogénesis y, en especial, sobre la ultraestructura del espermatozoide maduro de Eisenia foetida, se estudiaron sus células germinales mediante técnicas convencionales de microscopía electrónica. La espermatogénesis ocurre en las vesículas seminales y sigue un patrón comparable con el de otras especies de oligoquetos. Los detalles ultraestructurales del espermatozoide revelaron que es una célula filiforme, con el acrosoma situado en posición anterior, seguido por el núcleo, pieza intermedia y cola, la que posee el flagelo con la configuración microtubular típica de 9+2. Podemos concluir que el espermatozoide de Eisenia foetida es del tipo apomórfico,ya que presenta varias características consideradas evolucionadas, como son: acrosoma muy largo, vesícula acrosómica primaria contenida dentro del tubo acrosómico, varilla axial muy extendida y terminada en un capítulo desarrollado y el número de mitocondrias de la pieza intermedia igual a seis.

Spermatogenesis and the spermatozoon ultrastructure follow a common pattern in terrestrial oligochaetes. However, many of their characteristics are distinctive of each species and they are of great importance for phylogenetic and taxonomic studies. Germinal cells were studied through conventional electronic microscope techniques in order to go deep on spermatogenesis, especially on the mature spermatozoon ultrastructure of Eisenia foetida. Spermatogenesis occurs in seminal vesicles and follows a pattern comparable to that of some other oligachaetes species. Spermatozoon ultrastructural details revealed that it is a filiform cell, with the acrosome placed in anterior position, followed by the nucleus, the midpiece and the tail which flagellum has a 9+2 typical microtubular configuration. We may conclude that Eisenia foetida spermatozoon is of a apomorphic type since it presents several evolved characteristics such as: a very large acrosome; the primary acrosomic vesicle is held within the acrosomal tube, the axial rod is very elongated and ended in a developed capitulum and a number of mitochondria of the midpiece equal to six.

Relative Concentrations of Placental Lactogen II and PRL-Like Protein-A in Stressed Rats Placenta / Concentraciones del Lactógeno Placentario II y la Proteína A Ligada a Prolactina en Placentas de Ratas Estresadas

The chronic stress induces functional adaptations in the hypothalamo-pituitary- adrenocortical (HPA) and in the sympathetic-medullary-adrenal axis (SAM). Both axis are considered vital regulators of the homeostasis in vertebrates (Seyle, 1936; Ostrandrer et al, 2006. On the other hand, the placenta provides highly specialized functions during gestation that are critical for the normal development of the embryo/fetus (Soares et al., 1991). We hypothesized that the chronic immobilization (IMO) stress in pregnancy rats produces alterations in prolactin concentrations in placental tissue and also changes in the response of SAM axis. Chronic stress by IMO was applied on days 12, 17 and 21 of pregnancy rats. Relative concentrations and localization of placental lactogen-II (PL-II) and the PRL- like protein A (PLP-A) in chorioalantoic placenta were estimated by Immunoblotting and Immunocytochemical analysis. The levels of catecholamines metabolite, acid 3-metoxi 4-hidroximandélico (VMA), were analyzed in stressed rats urines on 6,12,17,21 days of pregnancy, by HPLC, in order to determine the response of SAM axis. During the days of the pregnancy studied, chronic stress did not induce any changes neither in the localization nor in placental concentrations of PL-II and PLP-A. The VMA values in stressed mothers urines increased on the day 6 respecting the control ones at the same time of pregnancy. VMA values in stressed rats at 21 days of pregnancy are smaller than the respective controls. We conclude that the chronic stressed mothers activated the SAM axis at the beginning of pregnancy and then they diminished the metabolites catecholamines that were interpreted as a stress adaptation coincident with normal concentrations of both placentary prolactines at this stage of the pregnancy.

El estrés crónico induce adaptaciones funcionales en los ejes hipotálamo-pituitario-adrenal (UPA) y en el simpático médulo adrenal (SAM). Ambos ejes son considerados reguladores vitales de la homeostasis en los vertebrados (Seyle, 1936; Ostrandrereí al., 2006). Por otro lado, el desarrollo y crecimiento fetal de los mamíferos dependen en gran medida del buen funcionamiento de la placenta (Soares, 1991). Nosotros hipotetizamos que el estrés crónico por inmovilización (IMO) aplicado a las ratas gestantes produce alteraciones en las concentraciones de las prolactinas en el tejido placentario y cambios en la respuesta del eje SAM. Se le aplicó estrés crónico por IMO a las hembras en los días 12, 17 y 21 de la preñez y se analizó por inmunocitoquímica e inmunoblotting la localización y concentraciones del lactógeno placentario dos (PL-II) y la proteína A ligada a la prolactina (PLP-A) en la placenta. Se analizaron por HPLC, en las orinas de ratas preñadas (6,12,17,21 días), los niveles del metabolito de las catecolaminas, (ácido 3-metoxi 4-hidroximandélico) (VMA), a fin de determinar la respuesta del eje SAM al tratamiento. El estrés crónico no indujo cambios tanto en la localización como en las concentraciones de PL-II y PLP-A en las placentas en los días de la preñez estudiados. Los valores de VMA en las orinas de las madres estresadas se incrementaron en el día 6 con respecto al control del mismo tiempo de preñez. Mientras que a los 21 días los valores de VMA de las ratas estresadas son menores que los controles respectivos. Concluimos que en las madres estresadas crónicamente, no se alteraron las concentraciones de ambas prolactinas placentarias. En cambio se activó el eje SAM al comienzo de la preñez ante el primer estímulo estresante y luego una reducción de la respuesta del eje ante el estrés crónico, a medida que avanza la preñez.

Chronic stress effects on the apoptotic index of the adrenal cortex of pregnant rats

Chronic stress by immobilization during gestation can alter several mechanisms that maintain homeostasis in adrenal gland. The aim of this work was to quantify the apoptotic index of adrenal cortex during mid-pregnancy and to prove cytological characteristics by electron microscopy. The apoptotic index did not present significant differences between the adrenal cortex areas of control and experimental rats in any of the three ages studied. The day of gestation influenced significantly on the apoptotic index in both groups. This index increased as gestation progressed. It may be concluded that chronic stress by immobilization might induce the increase of apoptotic index in adrenal cortex as gestation progresses which might be related variations of plasmatic corticosterone and prolactin, and to the decrease of specific growth factors. On the other hand, it might be concluded that each zone of adrenal cortex behaves independently in regards to apoptosis and cellular proliferation via paracrine and/or autocrine regulatory mechanisms without being affected by other zones.

Chronic stress effects on the apoptotic index of the adrenal cortex of pregnant rats

Chronic stress by immobilization during gestation can alter several mechanisms that maintain homeostasis in adrenal gland. The aim of this work was to quantify the apoptotic index of adrenal cortex during mid-pregnancy and to prove cytological characteristics by electron microscopy. The apoptotic index did not present significant differences between the adrenal cortex areas of control and experimental rats in any of the three ages studied. The day of gestation influenced significantly on the apoptotic index in both groups. This index increased as gestation progressed. It may be concluded that chronic stress by immobilization might induce the increase of apoptotic index in adrenal cortex as gestation progresses which might be related variations of plasmatic corticosterone and prolactin, and to the decrease of specific growth factors. On the other hand, it might be concluded that each zone of adrenal cortex behaves independently in regards to apoptosis and cellular proliferation via paracrine and/or autocrine regulatory mechanisms without being affected by other zones.(AU)