La paradoja de la inmigración: las madres haitianas y latinoamericanas en Chile / The Immigration Paradox: Haitian and Latin American Mothers in Chile

Introducción: Existe información internacional sobre las diferencias en parto prematuro y peso al nacer para madres migrantes de diferentes etnias originarias. El objetivo de este trabajo es evaluar parto prematuro y peso al nacer de madres de nacionalidad diferente, cuyos partos ocurrieron en Chile. Materiales y métodos Se utilizó la base de datos nacional del Departamento de Informática del Ministerio de Salud de Chile. Se incluyeron los recién nacidos del período Septiembre 2012 a Diciembre 2016. Se evaluaron los datos perinatales básicos, parto prematuro, bajo peso al nacer y su relación con la edad gestacional de nacidos de madres chilenas y de otras nacionalidades. Resultados En el periodo estudiado hubo 1.048490 nacimientos, de los cuales 50995 son de madres extranjeras. El porcentaje de nacidos antes de 37 semanas en madres de Bolivia, Colombia, Ecuador, Perú y Venezuela es entre un 4.8 y 7.3 %, versus 8% en madres chilenas. Los percentiles 10 para el peso al nacer entre 30 y 40 semanas para madres chilenas y Haitianas (en paréntesis) expresados en gramos: 1045 (1102), 1195 (1160), 1360 (1370), 1550 (1503), 1750 (1508), 2000 (1669), 2235 (1982), 2500 (2237), 2810 (2607), 2970 (2710), 3080 (2858). Los z-score de madres Haitianas fueron significativamente menores después de las 35 semanas. Conclusiones La paradoja de la inmigración se verifica en la experiencia nacional, con tasas de natalidad prematuras y bajo peso al nacer más favorables para las madres extranjeras en comparación con las mujeres chilenas y con sus países de origen. Las madres afro-caribeñas tuvieron nacimientos con peso menor, en edades gestacionales donde se toman decisiones frecuentes, con diferencias de hasta un 20 % entre las 35- 37 semanas.

SUMMARY The immigration paradox: Haitian and Latin American mothers in Chile Introduction There is international information on the differences in preterm birth and birth weight for migrant mothers of different ethnicities. The objective is to evaluate prematurity and birth weight of mothers of different national origin, whose deliveries occurred in Chile. Materials and methods The national database of the Department of Informatics of the Ministry of Health of Chile was used. Newborns from the period of September 2012 to December 2016 were included. Basic perinatal data, preterm birth, low birth weight and their relationship with the gestational age of babies born to mothers of local origin and other nationalities were evaluated. Results 1,048,490 births, 50,995 foreign mothers were studied. The percentage of those born before 37 weeks of mothers from Bolivia, Colombia, Ecuador, Peru, and Venezuela is between 4.8 and 7.3%, compared to nationals with 8%. The 10th percentiles for birth weight from 30 to 40 weeks for Chilean and Haitian mothers (in parentheses) were (g): 1045 (1102), 1195 (1160), 1360 (1370), 1550 (1503), 1750(1508 ), 2000 (1669), 2235 (1982), 2500 (2237), 2810 (2607), 2970 (2710), 3080 (2858). The z-scores of Haitian mothers were significantly lower. Conclusions The immigration paradox is verified in the national experience, with preterm birth rates and low birth weight more favorable to foreign mothers compared to chileans Afro-Caribbean mothers had births with a lower weight, at gestational ages where relevant decisions are made, with differences of up to a 20% between 35-37 weeks.

Estrogen withdrawal transiently increased bone turnover without affecting the bone balance along the tooth socket in rats.

BACKGROUND: Estrogen withdrawal causes marked bone loss in the appendicular skeleton but slightly affects mandibular cancellous bone; in contrast, little is known of its effects on alveolar wall turnover associated with tooth drift. In this study, we assessed short-term changes in alveolar wall turnover after an ovariectomy and compared it to other bone sites exhibiting different levels of turnover. METHODS: Forty Sprague-Dawley rats were ovariectomized or sham operated. Right mandibles and femurs were processed without demineralization for bone histomorphometry in three different sites: the alveolar wall around the first molar buccal root, apical interradicular bone, and femoral metaphysis. Bone changes were assessed 14 and 28 days after the ovariectomy. Data were compared using non-parametric statistics. RESULTS: At 14 days, on the resorption side of the alveolar wall, resorption parameters were higher in the ovariectomized rats (P <0.01), whereas the formation was lower (P <0.05); on the formation side, the daily mineral apposition rate increased (P <0.01). The root resorption was higher in ovariectomized rats (P <0.05). In the periodontal ligament, the numbers of osteoclast precursors were significantly higher. At 28 days, the drift slowed down in both the sham and ovariectomized groups. The ovariectomy had no effect on interradicular bone turnover, whereas bone loss and numbers of osteoclasts were strongly increased in the femur as soon as 14 days after the ovariectomy. CONCLUSIONS: Estrogen withdrawal had transient repercussions on alveolar wall turnover. The different reactivities of the three envelopes studied suggest that a response to an ovariectomy in the short term is related to initial basal turnover.

The three-dimensional microanatomy of the rabbit and human cornea. A chemical and mechanical microdissection-SEM approach.

The three-dimensional (3D) microanatomy of the cornea is the major determinant of its optical and mechanical properties. Scanning electron microscopy (SEM) is the most commonly used method to obtain information on the overall 3D microanatomy of organs. However, SEM has not been successful in revealing the 3D microanatomy of the cornea, because the interior of the cornea is too compact to be explored by the electron beam. In this study, the 3D organisation of the cells and extracellular materials of human and rabbit corneas was examined after exposure by HCl and NaOH digestion, and by microdissection by the adhesive tape method. In the cornea of both species, all epithelial cells exhibited microplicae regardless of their location. This raises doubts about the tear film-holding role assigned to the microplicae of the superficial cells. Human and rabbit corneas differed in the collagen fibre patterns of the epithelial basement membranes. The 3D organisation of the stromal lamellae was similar in both species. In humans and rabbits, the keratocytes showed similar 3D features. However, the surface of human keratocytes located near Descemet's membrane exhibited small fenestrations that were not present in the rabbit keratocytes. The pattern of keratocyte innervation by the stromal neural plexus and 3D keratocyte microanatomy confirms that keratocytes form a large intercommunicating network within the corneal stroma. Two morphologically discrete subpopulations of keratocytes located at different stromal levels were identified in both human and rabbit corneas, suggesting that keratocytes are not functionally homogeneous. In addition, the density of the stromal neural plexus appeared to be greater in rabbits than in humans. Clear differences between human and rabbit corneas were observed in the collagen arrangement in Descemet's membrane, which may reflect their different biomechanical requirements.

Evidence of a new transitory extracellular structure within the developing rhombencephalic cavity. An ultrastructural and immunoelectron-microscopic study in the chick.

The first rudiment of the central nervous system is a simple tube, the neural tube, and its cavities become the cerebro-ventricular system. The elements located within this system, their composition and precise morphogenetic role are poorly understood. This study used transmission (TEM) and scanning (SEM) electron microscopy, and immunoelectron microscopy, and describes in the chick the development, ultrastructure, composition, and regression of a previously undescribed extracellular structure located in close relationship with the luminal pole of the developing rhombencephalic tectoria lamina. We have called it the rhombencephalic roof network (RRN). The RRN was first observed in stage 12, closely related to a cluster of apoptotic cells. Between stages 15 and 18, the RRN attained its greatest development; it was rhomboid in shape and SEM revealed a network of fibers. Between stages 19 and 22, the RRN underwent a process of fragmentation and regression, and was not observed after stage 23. With TEM, the RRN appeared formed by amorphous ruthenium-red-positive material and sets of tubes between 4 and 25 nm in diameter. Each tube was formed by the superposition of annular units. Immunolabelling showed the presence of laminin and heparan sulfate proteoglycan in both the amorphous material and fibers; the former also contained tenascin. In terms of ultrastructure and composition, the fibers were similar to one the basic components of the lamina densa of basement membranes. The developing tectoria lamina exhibited openings as early as stage 12+, showing that the neural cavity is not a closed system and that the neural tube fluid (NTF) could be a circulating liquid. The presence in the RRN of three molecules of the extracellular materials actively involved in several developmental processes and the very early appearance of the RRN suggest that this structure plays a developmental role in rhombencephalic morphogenesis.

Epithelial involution and basement membrane loss during early rhombencephalic tectoria lamina development.

Extracellular material molecules play a key role in the regulation of morphogenesis and differentiation of a large number of organs including the central nervous system. However, the role of the neural basement membrane in the growth of different parts of the neural tube has yet to been delineated. Here, the structural and compositional modifications of the basement membrane (BM) of rhombencephalic tectoria lamina anlage (RTLA) have been examined during the process of RTLA epithelial attenuation. Between stages 10 to 11-the presumptive RTLA epithelium showed a structure, thickness and cell-proliferating capacity similar to those observed in other zones of the rhombencephalic walls. Moreover, the rhombencephalic vesicles were surrounded by a continuous BM that was heterogeneous both ultrastructurally and with regard to ruthenium red, laminin and tenascin distribution. After stage 11, the RTLA epithelium underwent a rapid process of attenuation and change to a stratified flattened epithelium. During this remodelling process, apoptosis and inhibition of both PCNA expression and 3H-thymidine uptake occurred in the RTLA epithelium. The BM of the RTLA underwent a process of degration at the beginning of the remodelling, and apoptosis and cell proliferation inhibition of RTLA epithelium were also observed. The loss of the biochemical signals encoded within the BM could lead to cell shape changes, cell proliferation inhibition and to the anoikis type of cell death. Our findings support the idea that the BM surrounding the neural tube plays a key role in controlling both the structure and growth of the CNS during the early developmental stages.

Supraependymal cells and fibers during the early stages of chick rhombencephalic development.

Supraependymal cellular elements are a constant feature in the adult cerebroventricular system. However, there has been no analysis of their distribution and morphology during the embryonic stages of the chick brain. The ultrastructural features of the rhombencephalic luminal surface of chick embryos ranging from stage 10 to 22 were studied with both scanning and transmission electron microscopy. In addition, immunocytochemistry and confocal laser microscopy were used to examine the presence of 68 kD neurofilaments in supraependymal elements. The ultrastructural observations revealed significant morphological differences in the apical cell surface between the cells at rhombomere boundaries and those in the rhombomere bodies. These differences support the idea that the boundary and the body of rhombomeres contain two morphologically distinct cell types. Supraependymal (SE) cells and SE fibers were present in the rhombencephalon of all embryos studied from stage 12 to 22. The cells were bipolar spindle-shaped. The SE fibers showed a characteristic spatial pattern within the rhombencephalon, following a straight course parallel to the rhombomere boundaries. The SE fibers showed varicosities and their endings contained small vesicles. Both SE cells and SE fibers were positive for 68 kD neurofilaments. Their morphology and reactivity for neurofilaments indicate a neuronal function. The constant presence of SE cells and SE fibers on the surface of the developing rhombencephalon, their special pattern and close relationship with the neural tube fluid (NTF) suggest that these supraependymal elements may be involved in a neuronal signalling pathway between different parts of the same rhombomere and also in chemical communication and integration within the ventricular system, linking distant parts of the developing central nervous system by means of NTF.

Lectin-binding sites and silver affinity of the macula densa basement membranes in the rabbit kidney.

Fluorochrome-labelled lectins and the Jones method of silver impregnation preceded by different oxidation and enzymatic digestion procedures were used to study the patterns of glycosylation and silver affinity of the macula densa (MD) and thick ascending limb (TAL) basement membranes of the rabbit kidney. The goal of this study was to analyse the morphological basis of MD basement membrane permeability and its possible role in modulation of the signal involved in tubuloglomerular feedback control of the juxtaglomerular apparatus. The lectin-binding pattern and silver affinity of basement membrane differed clearly from those of the TAL basement membrane. The former had greater WGA and Con A affinity than the latter. Furthermore, the MD basement membrane lost argyrophilia in permanganate oxidized sections whereas that of the TAL did not. The cell coat of MD cells differed from that of the TAL cells in that it had N-acetyl neuraminic acid and Con A binding sites. Our results suggest that the MD basement membrane has a distinctive macromolecular composition which may be related to its permeability to high molecular weight molecules.