Age-dependent acute interference with stem and progenitor cell proliferation in the hippocampus after exposure to 1800 MHz electromagnetic radiation.

To investigate the effects of exposure to an 1800 MHz electromagnetic field on cell death and cell proliferation in the developing brain, postnatal day 7 (P7) and P21 healthy Kunming mice were randomly assigned into the experimental and control groups. The experimental groups were exposed to an 1800 MHz electromagnetic field for 8 h daily for three consecutive days. The thymidine analog 5-bromo-2-deoxyuridine (BrdU) was injected intraperitoneally 1 h before each exposure session, and all animals were sacrificed 24 h after the last exposure. Cell death and proliferation markers were detected by immunohistochemistry in the dentate gyrus of the hippocampus. Electromagnetic exposure has no influence on cell death in the dentate gyrus of the hippocampus in P7 and P21 mice as indicated by active caspase-3 immunostaining and Fluoro-Jade labeling. The basal cell proliferation in the hippocampus was higher in P7 than in P21 mice as indicated by the number of cells labeled with BrdU and by immunohistochemical staining for phosphor-histone H3 (PHH3) and brain lipid-binding protein (BLBP). Electromagnetic exposure stimulated DNA synthesis in P7 neural stem and progenitor cells, but reduced cell division and the total number of stem cells in the hippocampus as indicated by increased BrdU labeling and reduced PHH3 and BLBP labeling compared to P7 control mice. There were no significant changes in cell proliferation in P21 mice after exposure to the electromagnetic field. These results indicate that interference with stem cell proliferation upon short-term exposure to an 1800 MHz electromagnetic field depends on the developmental stage of the brain.

[Effects of erythropoietin on neuronal proliferation and apoptosis in neonatal rats after infection-induced brain injury].

OBJECTIVE: To investigate the effects of erythropoietin (EPO) on the neuronal proliferation and apoptosis in neonatal rats after infection-induced brain injury and the neuroprotective mechanism of EPO in neonatal rats with infection-induced brain injury. METHODS: Twenty-six two-day-old neonatal rats were randomly divided into 3 groups: control group (intraperitoneally given an equal volume of normal saline), lipopolysaccharide (LPS) group (intraperitoneally given LPS 0.6 mg/kg), and EPO group (intraperitoneally given LPS 0.6 mg/kg and EPO 5 000 U/kg). These groups were injected with respective drugs for 5 consecutive days. Meanwhile, each group was intraperitoneally injected with 5-bromo-2'-deoxyuridine (BrdU) (50 mg/kg) once a day for 5 consecutive days. The expression of BrdU and cleaved Caspase-3 in the hippocampal dentate gyrus was detected by immunohistochemistry at 24 hours after the last injection. RESULTS: The number of neuronal cells in the hippocampal dentate gyrus in the LPS and EPO groups was significantly greater than in the control group (P<0.05), but there was no significant difference between the LPS and EPO groups. The EPO group had a significantly higher number of BrdU-positive cells in the subgranular zone of hippocampal dentate gyrus than the LPS group (51±9 vs 29±6; P<0.05), but a significantly lower number of BrdU-positive cells than the control group (51±9 vs 67±12; P<0.05). The EPO group had a significantly lower number of cleaved Caspase-3-positive cells in the subgranular zone of hippocampal dentate gyrus than the LPS group (27.9±1.5 vs 34.0±1.3; P<0.05), but a significantly higher number of cleaved Caspase-3-positive cells than the control group (27.9±1.5 vs 21.0±1.7; P<0.05). CONCLUSIONS: EPO can promote hippocampal neuronal proliferation and reduce neuronal apoptosis in neonatal rats after infection-induced brain injury.

Characteristics of respiratory distress syndrome in infants of different gestational ages.

BACKGROUND: The purpose of this study was to compare the risk factors, clinical characteristics, and complications of respiratory distress syndrome (RDS) in infants delivered very preterm, late preterm, and term in order to help optimize the management of RDS in neonates. METHODS: A retrospective study was conducted on neonates admitted to the NICU between January 2006 and December 2010. The enrolled infants with RDS were categorized as very preterm (<32(0/7) weeks gestation), moderately preterm (32(0/7)-33(6/7) weeks), late preterm (34(0/7)-36(6/7) weeks), and term (37(0/7)-42(0/7) weeks). The rates, potential risk factors, clinical characteristics, and complications of RDS of these four groups were comparatively analyzed. RESULTS: There was an increasing trend in incidence of RDS among the NICU admissions annually. Caesarean section without labor was significantly associated with RDS in term and late preterm infants (P < 0.001). Rates of requirements for ventilator and pulmonary surfactant were similar in very preterm and term infants but significantly lower in late preterm infants (P < 0.001). The oxygenation index value was not substantially lower in late preterm and term infants compared to very preterm infants, and the arterial oxygenation efficiency was improved slowly (P < 0.001). Incidence of pneumonia and occurrence of pneumothorax were significantly higher in term infants (P < 0.001). CONCLUSIONS: Term infants with RDS showed an association of RDS with caesarean section without labor and lung infection. These infants also showed slower improvement of oxygenation after surfactant administration and mechanical ventilation, and they experienced a high rate of pneumothorax complication, which was also noticed in late preterm neonates.

[Perinatal conditions of preterm infants with different severities of respiratory distress syndrome].

OBJECTIVE: To understand the risk factors for respiratory distress syndrome (RDS) by comparing the perinatal conditions of preterm infants with different severities of RDS. METHODS: A total of 667 preterm infants with RDS were classified into 4 groups according to the chest X-ray severity: grade I (217 cases), grade II (225 cases), grade III (126 cases) and grade IV (99 cases). The perinatal conditions of the preterm infants were reviewed retrospectively. RESULTS: There were no significant differences in the gender, the percentage of twins, the percentage of the younger one in twins, maternal age, the percentage of using antenatal corticosteroids, the percentage of premature rupture of membranes, the percentage of placental abruption, the delivery mode and the fertilization mode in preterm infants with different severities of RDS. With the increasing severity of RDS, the birth weight and the gestational age decreased, and the percentage of the infants with Apgar score ≤7 or maternal pregnancy-induced hypertension increased (P<0.05). CONCLUSIONS: The severity of RDS is related to gestational age, birth weight and perinatal asphyxia in preterm infants.