Biology of the neonate最新文献

Objective: To prospectively investigate the longitudinal changes of amplitude-integrated electroencephalographic (aEEG) activity in preterm infants <30 weeks gestational age (GA).

Methods: Infants (GA <30 weeks) without evidence of neurological abnormalities had weekly aEEG recordings performed. The relative duration of the three aEEG patterns (discontinuous low voltage, discontinuous high voltage and continuous) was determined and the influence of GA and postnatal age (PNA) on the occurrence of each pattern was assessed.

Results: Ninety-eight infants (median GA 26 weeks; range 23-29 weeks) were studied. With higher GA (OR 1.68, 95% CI 1.33-2.13) and PNA (OR 1.91, 95% CI 1.53-2.38), the likelihood for the occurrence of continuous activity increased. The discontinuous low-voltage pattern was less likely to occur with increasing GA (OR 0.68, 95% CI 0.55-0.83) and PNA (OR 0.70, 95% CI 0.61-0.81).

Conclusion: Maturation of aEEG activity in preterm infants is influenced by both GA and PNA.

Background: Various cytokines are reportedly associated with many neonatal diseases. Asphyxia is considered to result in ischemia-reperfusion injuries and induces abnormal inflammatory responses involving excessive cytokine production.

Objectives: To evaluate alteration in sera levels of various cytokines/chemokines in case of perinatal asphyxia at birth.

Methods: In order to determine the concentrations of various cytokines/chemokines in sera, we used a highly sensitive fluorescence microsphere method. We measured the concentration of 8 types of cytokines/chemokines in sera obtained from 17 cases of asphyxia, 10 normal neonates, and 6 healthy adults.

Results: The concentrations of IL-6, IL-8, and IL-10 in the sera of asphyxiated neonates were higher than those in the normal neonates. Irrespective of the presence or absence of asphyxia, sera concentrations of IL-2, IL-4, IFN-gamma, and TNF-alpha were higher in the neonates than those in the adults. The concentration of IFN-gamma in the asphyxiated neonates was lower than that in the normal neonates. Sera levels of IL-10 were higher in the asphyxiated cases than those in the normal neonates. The sera levels of IL-6, IL-8, and IL-10 in asphyxiated neonates with either a poor outcome or death were higher than those without poor outcomes.

Conclusions: The concentrations of various types of cytokines/chemokines were different in neonatal sera and some of them increased drastically during asphyxia. The concentration of an anti-inflammatory cytokine IL-10 was elevated in asphyxiated neonates immediately after birth, thereby suggesting that IL-10 might be associated with neuroprotective functions.

Objective: To investigate fetal exposure to toxic metals [lead (Pb), cadmium (Cd)] and fetal levels of trace elements [zinc (Zn), copper (Cu), and iron (Fe)] in newborns from an industrial city. Relationships between meconium mineral contents and parental occupation and location of residence were also tested.

Method: The meconium mineral contents of 117 healthy newborn infants were measured by flame atomic absorption spectrophotometer.

Results: The median concentrations (interquartile range) of toxic metals and trace elements in the meconium were as follows: Pb: 46.5 (1,399) microg/g dry weight (wt), Cd: 2.3 (55.6) microg/g dry wt; Zn: 234 (3,049) microg/g dry wt; Cu: 11.8 (818.7) microg/g dry wt, and Fe 105 (2,980) microg/g dry wt. All the meconium samples contained both toxic metals and trace elements. The proportions of trace elements in the meconium samples with concentration higher than 100 microg/g dry wt of the substances tested were Zn 90%, Cu 64%, and Fe 53%. There were significantly positive correlations between the concentrations of toxic metals and trace elements. Also there were positive correlations between the levels of Zn, Fe, and parental occupations, and between the level of Fe and location of residence of the parents (proximity to the petroleum refinery or the dye industries).

Conclusion: All the meconium samples were positive for toxic metals, and thus may reflect environmental pollution in the city. The occupation environments and the location of the family residence are linked with levels of trace elements in meconium.

Background: Prenatal exposure to magnesium sulfate, a drug that is frequently used for attempted tocolysis in preterm labor, could alter neutrophil functional activity in infants born preterm.

Objectives: To determine the association between maternal tocolysis with magnesium sulfate and the cord blood neutrophil functional activity of preterm neonates.

Methods: The chemotaxis, random motility, and chemiluminescence of neutrophils were compared in the cord blood of 10 preterm neonates born to mothers tocolysed with magnesium sulfate, 10 preterm infants whose mothers had not received any tocolysis, and 10 term infants. Data regarding the maternal and neonatal magnesium and calcium levels were collected and analyzed in association with the cord blood neutrophil functional activity of the preterm infants.

Results: Neutrophil functional activity in the cord blood of the preterm neonates was significantly lower than in term neonates. However, the alteration of neutrophil chemotaxis, random motility and chemiluminescence was more noticeable in neonates with intrapartum exposure to magnesium sulfate as compared to preterm infants whose mothers received no tocolysis (30.9 +/- 2.3 vs. 36.7 +/- 2.7 microm, p < 0.01; 26.6 +/- 1.9 vs. 33.1 +/- 3.1 microm, p < 0.01; and 74.3 +/- 6.5 vs. 89.9 +/- 6.25 x 10(3) counts per min (cpm), p < 0.01, respectively). Furthermore, the reduction in neutrophil functional activity of preterm infants with intrapartum exposure to magnesium was directly correlated with the maternal serum magnesium levels (r = -0.90 to -0.85, p < 0.01).

Conclusion: In infants born preterm, intrapartum exposure to magnesium sulfate is a risk factor contributing to the alteration in neutrophil motility and post-phagocytic bactericidal capacity.

Background: The hyperbilirubinemic j/j Gunn rat is frequently used to study the effects of neonatal hyperbilirubinemia on the developing central nervous system (CNS). Despite evidence that the cerebellar region and males are predisposed to bilirubin-induced brain injury in this animal model, there are limited regional and no sex-specific brain bilirubin content data.

Objective/methods: To characterize and contrast the regional (cortex, brainstem, cerebellum) and sex-specific CNS bilirubin contents of hyperbilirubinemic j/j Gunn rat pups and their age-matched (15-19 days) nonjaundiced J/j counterparts. Pups were injected 24 h prior to sacrifice with sulfadimethoxine (200 mg/kg i.p.) to enhance the CNS bilirubin content.

Results: The CNS bilirubin contents in each region and total serum bilirubin levels were significantly greater in jaundiced j/j pups versus nonjaundiced J/j pups. Within the sulfadimethoxine-treated male j/j cohort, the mean brain bilirubin content was highest in the cerebellum (18.9 +/- 7.8 microg/g), intermediate in the brainstem (10.7 +/- 8.0 microg/g), and lowest in the cortex (4.7 +/- 3.0 microg/g) (F = 11.31, p < 0.001 by ANOVA), and the cerebellar bilirubin level was significantly higher than in the littermate-matched sulfadimthoxine-treated j/j female pups (p < 0.02). The serum albumin levels were not different between j/j male and j/j female pups.

Conclusions: We conclude that the brain bilirubin content of hyperbilirubinemic j/j Gunn rat pups is greater than in nonjaundiced J/j pups and varies as a function of CNS region and sex. We speculate that the higher cerebellar bilirubin content may preferentially predispose male j/j Gunn rat pups to bilirubin-induced neurotoxicity.

Background: Human newborn infants display a variety of immunodeficiencies of immaturity, including diminished neutrophil adhesion, chemotaxis, and migration. Rac2, a guanosine triphosphate-binding protein, is an essential regulator of human neutrophil migration and chemotaxis. Since human subjects and mice deficient in Rac2 display deficiencies in neutrophil functions similar to newborn infants, we postulated that newborn neutrophils may be deficient in Rac2.

Objectives: The aim of the study was to measure Rac1 and Rac2 concentrations in neutrophils from umbilical cord blood.

Methods: Neutrophils from cord and adult blood were isolated, total cell lysates extracted, and Rac protein concentrations determined using Western blot analysis.

Results: Rac2 concentrations were significantly lower in the neutrophil protein lysates isolated from cord blood compared to adult blood despite similar levels of Rac1.

Conclusions: Diminished Rac2 expression in cord blood neutrophils may contribute to the defects observed in cord blood neutrophil function.

Background: Sodium bicarbonate (NaHCO3) is often used for correction of metabolic acidosis in preterm infants. The effects of NaHCO3 administration on cerebral hemodynamics and oxygenation are not well known. Furthermore, there is no consensus on infusion rate of NaHCO3.

Objectives: To evaluate the effects of rapid versus slow infusion of NaHCO3 on cerebral hemodynamics and oxygenation in preterm infants.

Methods: Twenty-nine preterm infants with metabolic acidosis were randomized into two groups (values are mean +/-SD): In group A (GA 30.5 +/- 1.7 weeks, b.w. 1,254 +/- 425 g) NaHCO3 4.2% was injected as a bolus. In group B (GA 30.3 +/- 1.8 weeks, b.w. 1,179 +/- 318 g) NaHCO3 4.2% was administered over a 30-min period. Concentration changes of oxyhemoglobin (cO2Hb) and deoxyhemoglobin (cHHb) were assessed using near infrared spectrophotometry. Changes in HbD (= cO2Hb - cHHb) represent changes in cerebral blood oxygenation and changes in ctHb (= cO2Hb + cHHb) reflect changes in cerebral blood volume. Cerebral blood flow velocity was intermittently measured using Doppler ultrasound. Longitudinal data analysis was performed using linear mixed models (SAS procedure MIXED), to account for the fact that the repeated observations in each individual were correlated.

Results: Administration of NaHCO3 resulted in an increase of cerebral blood volume which was more evident if NaHCO3 was injected rapidly than when infused slowly. HbD and cerebral blood flow velocity did not show significant changes in either group.

Conclusion: To minimize fluctuations in cerebral hemodynamics, slow infusion of sodium bicarbonate is preferable to rapid injection.

Objectives: Maintenance of appropriate body temperature, humidification and prevention of skin injury are very important in the management of extremely premature infants with immature skin. We have developed a new closed liquid incubator, utilising the characteristics of perfluorochemical (PFC) liquids, i.e., high specific gravity and chemical and biological inertness. The potential of this incubator to control body temperature was evaluated in rats.

Methods: PFC liquid (FC43; 3M Company, Tokyo, Japan) within the incubator was heated or cooled and the rectal temperature of each rat and the PFC temperature were monitored.

Results: The rectal temperature of rats floating on the PFC liquid surface changed almost in parallel to the temperature of PFC within the incubator, indicating that this technique can be used to warm or cool adults rats in a stable manner. The relative humidity of air within the incubator was maintained constant at 100%.

Conclusions: The liquid incubator used in the present study maintained an environment with a relative humidity of 100% and allowed stable maintenance of temperature in adult rats. We also demonstrated that heating and cooling the PFC liquid allowed control of body temperature. Although further studies are required, this new incubator may be useful for the clinical management of extremely premature infants.

Background: Previous studies demonstrated that dopamine infusion reduces plasma concentration of thyroxine (T4), thyroid stimulating hormone (TSH), prolactin (PRL), and growth hormone (GH) in adults, children, and infants.

Objectives: The purpose of this prospective observational study was to evaluate the relationship between dopamine infusion and the dynamics of T4, TSH, PRL, and GH in preterm newborns weighing less than 1,500 g (very low birth weight infants, VLBW) admitted in a neonatal intensive care unit of a university hospital over a one year period.

Methods: A total of 97 preterm newborns were enrolled and divided into two groups: group B included hypotensive infants treated with plasma expanders and dopamine infusion; group A was the control group including newborns who were never treated with dopamine. The newborns were studied dynamically through blood samples taken every day till 10 days. Newborns of group B were studied during dopamine infusion and after its withdrawal.

Results: Among the VLBW newborns who were given dopamine, the four pituitary hormones had different dynamics: a reduction of T4, TSH, and PRL levels was noticed since the first day of treatment, and a rebound of their levels was evident since the first day after its interruption. On the contrary, the postprandial GH levels were roughly constant: GH plasma concentrations were in fact a little lower in newborns treated with dopamine, and a slight increase was observed after its withdrawal. However, observed differences were not statistically significant.

Conclusions: The results suggest that dopamine infusion reduces T4, TSH, and PRL plasma levels in preterm VLBW infants and have no effect on postprandial GH rate. This hormonal suppression reverses rapidly after dopamine withdrawal. This observation suggests that the iatrogenic pituitary suppression probably cannot produce long-term injuries.

Background/aim: Nitrofen (2,4-dichloro-4 -nitrodiphenyl ether), a teratogen with oxidant properties, induces congenital diaphragmatic hernia (CDH) with lung hypoplasia and delayed lung development and maturation in rat embryos. Several phenotypic features of the alveolar epithelium including surfactant proteins A and B synthesis and its regulation by transcription factors are reproduced in cultured human H441 pneumocytes. The aim of the present study was to test whether vitamins A, E and C with anti-oxidant properties were able to recover the expression of such regulators in an in vitro setting.

Materials and methods: Cultured human H441 pneumocytes were treated with nitrofen with or without additional exposure to vitamins A, E and C. Thyroid transcription factor 1 (TTF-1), hepatocyte nuclear factor 3-beta (HNF-3beta) and hepatocyte nuclear factor 3-beta surfactant protein B (SP-B) mRNAs were measured by real-time polymerase chain reaction (RT-PCR). The cells were also immunohistochemically stained for assessment of proliferation (PCNA) and apoptosis (bis-benzimide) status and SP-B and TTF-1 protein expressions. Results were compared by ANOVA with a significant threshold of 5%.

Results: Nitrofen severely decreased TTF-1, HNF-3beta and SP-B mRNA expression by H441 pneumocytes in culture. Addition of vitamin E normalized the levels of the three transcripts, while vitamin A normalized only those of TTF-1 and SP-B mRNA. Vitamin C was significantly beneficial only for SP-B transcript. Nitrofen decreased proliferation and TTF-1 and SP-B protein expressions with no apparent effect on apoptosis. Additional exposure to vitamins A, C or E rescued near normal values.

Conclusions: The changes induced by nitrofen in cultured H441 human pneumocytes are reverted in part by anti-oxidant vitamins by upregulating TTF-1, HNF-3beta and SP-B and stimulating proliferation and maturity in nitrofen-treated cells. These effects of anti-oxidant vitamins could be of some interest for developing new transplacental therapeutic strategies aimed at improving lung development and maturation in fetuses with CDH.