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Query: UMLS:C0728731 (prematurity)
 7,134 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because the cutaneous permeability barrier develops late in gestation, prematurity may result in increased morbidity and mortality due to barrier incompetence. The purpose of the present study was to develop an in vitro model of barrier ontogenesis in order to identify those factors critical for fetal barrier formation. Skin explants from gestational day 17 fetal rats (term is 22 days) were incubated in hormone- and serum-free media. After 4 d in culture, a multi-layered stratum corneum (SC) developed that demonstrated a membrane pattern of fluorescence using the hydrophobic probe, nile red, and the deposition of mature lamellar unit structures throughout the SC interstices, ultrastructurally. Transepidermal water loss rates declined during explant culture such that after 4 d a competent barrier was present. Similarly, lanthanum permeation studies showed tracer penetration into all cell layers in 2-d explants, whereas it did not penetrate above the stratum granulosum in 4-d explants. Thus, the chronology of epidermal development in the explants precisely mirrored that observed in utero. Treatment with either 10 nM dexamethasone or 10 nM triiodothyronine accelerated SC development and barrier formation by 2 d. These results indicate that (i) the late events of fetal epidermal development progress in vitro under serum- and growth factor-free conditions, culminating in the formation of a functional barrier, and (ii) both dexamethasone and triiodothyronine accelerate barrier development.
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PMID:Epidermal barrier ontogenesis: maturation in serum-free media and acceleration by glucocorticoids and thyroid hormone but not selected growth factors. 864 68

Hypertrophic pyloric stenosis can be diagnosed accurately by physical examination alone. However, ultrasonographic confirmation is obtained in the majority of cases, often before clinical evaluation by the surgeon. The present study examines whether the easy access to ultrasonography by the primary physician has affected the care of infants with pyloric stenosis. During a 24-month period, 100 infants were treated for pyloric stenosis at the authors' institution. There were 78 boys and 22 girls; the age range was 9 to 90 days (median, 30.0 days). The children were referred for surgical evaluation, but abdominal ultrasonography was ordered concomitantly (or within 1 hour of surgical consultation) in all cases. The median age at the onset of the first symptoms was 24.0 days. The time between onset and hospital admission was less than 7 days for 72 patients, and more than 2 weeks for seven. Metabolic alkalosis or acidosis, hypokalemia, hypochloremia, and dehydration were noted in 10%, 5%, 3% and 9%, respectively. Six infants had prolonged pre- and postoperative courses, because of prematurity (4) or associated conditions (2). For the remaining patients, total hospitalization period and postoperative stay were 3.8 +/- 0.9 days and 2.8 +/- 0.6 days, respectively. Although the diminished importance of clinical skills in the diagnosis of pyloric stenosis may be regrettable, the availability to the primary care physician of this easy, safe, inexpensive, and reliable imaging modality may contribute to prompter treatment. The patients were hospitalized, with a correct diagnosis, within days of the appearance of the initial symptoms. Because so little time had elapsed, water and electrolyte imbalances were not present, and the patients could be operated on within hours of admission.
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PMID:Pyloric stenosis in the age of ultrasonography: fading skills, better patients? 904 58

Immaturity of the epidermal barrier in the preterm infant may have serious clinical consequences. However, regardless of the degree of prematurity, the barrier rapidly matures such that by 2 wk all infants display a competent barrier. To determine whether the change from an aqueous (intrauterine) to a xeric environment might be the stimulus for this accelerated maturation, we examined the effects of air exposure on cutaneous barrier formation in vitro. Skin explants from d 17 fetal rats were incubated either submerged or at the air-medium interface. As previously reported, a competent barrier formed under submerged conditions after 3-4 d, precisely mirroring the time course of maturation in utero. In contrast, barrier maturation was accelerated in air-exposed explants, with functional, histologic, and structural markers of barrier formation observed after only 2 d of incubation. A water-impermeable membrane blocked the acceleration of barrier formation, resulting in a developmental time course comparable to that for submerged explants. In contrast a water vapor-permeable membrane did not block the acceleration. Glucocorticoids and thyroid hormone, which accelerate barrier formation in utero or in vitro under submerged conditions, did not further accelerate barrier formation in the air-exposed model. These data indicate that: 1) air exposure accelerates barrier ontogenesis, suggesting that water flux may be an important signal for the accelerated barrier formation that occurs in premature infants; and 2) factors which accelerate barrier formation in utero may not further accelerate barrier formation in neonates.
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PMID:Acceleration of barrier ontogenesis in vitro through air exposure. 902 53

In a statewide survey of 856 Iowa municipal drinking water supplies in 1986-1987 the Rathbun rural water system was found to contain elevated levels of triazine herbicides. Rates of low birth weight, prematurity, and intrauterine growth retardation (IUGR) in live singleton births during the period 1984-1990 by women living in 13 communities served by the Rathbun water system were compared to other communities of similar size in the same Iowa counties. The Rathbun communities had a greater risk of IUGR than southern Iowa communities with other surface sources of drinking water (relative risk = 1.8; 95% CI = 1.3, 2.7). Multiple linear regression analyses revealed that levels of the herbicides atrazine, metolachlor, and cyanzinc were each significant predictors of community IUGR rates in southern Iowa after controlling for several potentially confounding factors including maternal smoking and socioeconomic variables. The association with IUGR was strongest for atrazine, but all three herbicides were intercorrelated and the independent contributions of each to IUGR risk could not be determined. We conclude that communities in southern Iowa with drinking water supplies contaminated with herbicides have elevated rates of IUGR compared to neighboring communities with different water supplies. Because of the limitations of the ecologic design of this study, including aggregate rather than individual measures of exposure and limited ability to control for confounding factors related to source of drinking water and risk of IUGR, a strong causal relationship between any specific water contaminant and risk of IUGR cannot yet be inferred. The association between the water supplied to the Rathbun communities and the increased risk of IUGR should be considered a preliminary finding that needs to be verified by more detailed epidemiologic studies.
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PMID:Intrauterine growth retardation in Iowa communities with herbicide-contaminated drinking water supplies. 917 92

The mucosa covering the interarytenoid space at the entrance to the larynx contains specialized nerve endings (receptors) that are stimulated when a fluid comes into contact with the mucosal surface. These receptors mediate several aspiration preventive reflex responses, which include swallowing, cessation of breathing, airway constriction or closure, and coughing. The laryngeal receptors are more sensitive to water than to saline, and therefore the combined reflex response to receptor stimulation is termed the "laryngeal chemoreflex." This reflex can be activated during regurgitation of gastric contents into the pharynx, in which case the several components of the reflex serve to prevent intrapulmonary aspiration of gastric fluid. In certain infants a hyperactive laryngeal chemoreflex may cause episodic prolonged apnea. Such reflex-mediated apnea has been implicated in several kinds of prolonged infantile apnea, including apea of prematurity, gastric regurgitation-related apnea, and apnea associated with upper respiratory infection.
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PMID:Reflux associated apnea in infants: evidence for a laryngeal chemoreflex. 942 36

Pregnancy in women receiving renal replacement therapy is not without risk to the mother and fetus. This article reviews the information on fetal outcome in pregnancies associated with renal transplantation and dialysis. The incidence of neonatal mortality, prematurity, and small-for-gestational-age infants is increased in pregnancies associated with maternal renal replacement therapy. Conversely, there does not appear to be a significant increase in the rate of congenital malformations. Whereas the fetal risk for inheritable renal disease is clearly defined in most cases, the risk associated with a host of new immunosuppressive medications is poorly understood. In addition, the newborn may be at risk for abnormalities in water homeostasis caused by the large solute load transferred from the mother receiving dialysis and requires close observation. Continued accumulation of clinical data will permit women receiving dialysis or with a kidney transplant to make informed decisions about current or future pregnancies.
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PMID:Neonatal outcome in pregnancies associated with renal replacement therapy. 947 15

Little is known about the effect of prematurity on water reabsorption in the renal tubules by anti-diuretic hormone (vasopression: ADH). The purpose of this study was to assess the different mechanisms of maintaining water balance in newborn and in adult rats on ADH and aquaporin-2 (AQP2) axis. After the dehydration, the plasma ADH in newborn and adult rose 104.6% and 117.2%, respectively. In immunocytochemical study, AQP2 stained more intensively in dehydrated rats. The dehydrated adult rats apical membrane in the IMCD cells showed more intensive staining than in the control rats. Adult rats revealed more intensive staining than newborn after the dehydration in the IMCD cells. We conclude that low ADH secretion in response to dehydration might lead to inadequate production of AQP2 resulting in an increased tendency in newborn to become dehydrated.
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PMID:Adaptation to water depletion in the newborn rat--immunocytochemical localization of aquaporin-2. 971 47

Alterations of the architecture of cerebral white matter in the developing human brain can affect cortical development and result in functional disabilities. A line scan diffusion-weighted magnetic resonance imaging (MRI) sequence with diffusion tensor analysis was applied to measure the apparent diffusion coefficient, to calculate relative anisotropy, and to delineate three-dimensional fiber architecture in cerebral white matter in preterm (n = 17) and full-term infants (n = 7). To assess effects of prematurity on cerebral white matter development, early gestation preterm infants (n = 10) were studied a second time at term. In the central white matter the mean apparent diffusion coefficient at 28 wk was high, 1.8 microm2/ms, and decreased toward term to 1.2 microm2/ms. In the posterior limb of the internal capsule, the mean apparent diffusion coefficients at both times were similar (1.2 versus 1.1 microm2/ms). Relative anisotropy was higher the closer birth was to term with greater absolute values in the internal capsule than in the central white matter. Preterm infants at term showed higher mean diffusion coefficients in the central white matter (1.4 +/- 0.24 versus 1.15 +/- 0.09 microm2/ms, p = 0.016) and lower relative anisotropy in both areas compared with full-term infants (white matter, 10.9 +/- 0.6 versus 22.9 +/- 3.0%, p = 0.001; internal capsule, 24.0 +/- 4.44 versus 33.1 +/- 0.6% p = 0.006). Nonmyelinated fibers in the corpus callosum were visible by diffusion tensor MRI as early as 28 wk; full-term and preterm infants at term showed marked differences in white matter fiber organization. The data indicate that quantitative assessment of water diffusion by diffusion tensor MRI provides insight into microstructural development in cerebral white matter in living infants.
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PMID:Microstructural development of human newborn cerebral white matter assessed in vivo by diffusion tensor magnetic resonance imaging. 977 50

Nosocomial pneumonia is a major cause of morbidity and mortality in hospitalized patients. The risk is especially high in the neonatal intensive care unit (NICU) particularly in infants with mechanically assisted ventilation. During the 5-year period of the study, 160 infants with problems including prematurity (60.6%), respiratory distress (55.6%) and birth asphyxia (45.0%) were admitted to the NICU. One hundred and thirty-three infants (83.1%) received mechanical ventilation. Nosocomial pneumonia was found in 65 infants (40.6%) or 88.3 cases per 1,000 ventilator-days. Low birth weight, prematurity, respiratory distress and hyperbilirubinemia were found more significantly in the pneumonia group. They underwent more manipulations such as the placement of an umbilical catheter and orogastric tube. Infants with pneumonia received mechanical ventilation at a higher percentage and for a longer period than those without pneumonia (96.9% vs 73.7%, odds ratio = 11.2, p = 0.000) with a mean duration of 11.7 and 3.5 days respectively (p = 0.000). The etiologic organisms recovered from hemoculture were Acinetobacter calcoaceticus var. anitratus 44.0 per cent, Enterobacter spp. 16.0 per cent, Klebsiella pneumoniae 16.0 per cent, coagulase-negative staphylococci 12.0 per cent. There was no concordance of the bacteriologic results in endotracheal aspirate culture and hemoculture in each infant. Leukocytosis and granulocytosis as well as blood gas values could not differentiate the presence of pneumonia. The mean hospital stay for the infants with pneumonia was longer (23.0 days vs 6.4 days, p = 0.000). Nosocomial pneumonia did not only prolong hospital stay but also contributed to mortality. Twenty-seven (41.5%) of the infants with pneumonia died, compared with 46 (48.4%) of the other group without pneumonia (p = 0.422). The risk of nosocomial pneumonia can be reduced by using infection control measures, including meticulous hand washing and gloving during respiratory manipulation, heat-treated water supply in a nebulizing unit of the ventilator and proper care of umbilical catheterization.
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PMID:Nosocomial pneumonia in a newborn intensive care unit. 1080 99

The incidence of sudden infant death syndrome (SIDS) has been found to be consistently higher in preterm and low birth weight infants than in infants born at term and this increase is inversely related to gestational age. The incidence and severity of apnoea of prematurity, are also inversely related to gestational age. The aim of this study was to investigate whether a neonatal history of apnoea/bradycardia affected the maturation of arousal responses. Twenty-five premature infants were studied. A perinatal risk score was determined for each infant and infants were divided into those with a neonatal history of apnoea/bradycardia (n=16) and those without (n=9). All infants were studied using daytime polysomnography on three occasions: (a) a preterm study around 36 weeks gestation, (b) within 3 weeks of term, and (c) 2-3 months post-term. Multiple measurements of arousal threshold (cm H2O) in response to air-jet stimulation applied alternately to the nares were made in both active sleep (AS) and quiet sleep (QS). Arousal thresholds were elevated in apnoeic infants compared to control infants in both AS (P<0.05) and QS (P<0.001) at the term study and in QS at 2-3 months post-term (P<0.01). In addition, arousal thresholds were positively correlated with perinatal risk score in both sleep states, in all studies, with the exception of AS at 2-3 months when all infants were readily arouseable. We conclude that a history of prematurity with neonatal apnoea has a persisting effect on decreasing arousabilty from sleep and these infants may be at increased risk for SIDS.
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PMID:Apnoea of prematurity and arousal from sleep. 1122 74


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