Ee-Kyung Kim

Mesenchymal Stem-Cell Transplantation for Hypoxic-Ischemic Brain Injury in Neonatal Rat Model

Neonatal hypoxic-ischemic brain injury (HIE) remains a major cause of neurologic disabilities. However, many experimental therapies have shown limited successes. We assessed whether human mesenchymal stem cells (MSCs) could be transplanted in the HIE rat brain to improve neurologic disabilities. P7 SD rats were either subjected to left carotid artery ligation and hypoxic exposure [hypoxia-ischemia (HI)] or sham operation and normoxic exposure (sham). On P10, rat pubs received either PKH26-labeled MSCs or buffer via intracardial injection, resulting in four experimental groups: sham-buffer, sham-MSC, HI-buffer, and HI-MSC. Cylinder test and accelerating rotarod test were performed 14, 20, 30, and 40 d after injection. Six weeks after injection, cresyl violet and double immunofluorescence staining were performed. MSCs were transplanted to the whole brain mainly after HI. Glial fibrillary acidic protein and OX42 were more abundantly colocalized with MSC than neuronal specific nuclear protein or myelin basic protein. There were no significant differences in the total amounts and cell types between the lesioned and nonlesioned hemisphere. The lesioned hemispheric volume was decreased after HI (p = 0.012) but not restored by MSC. Neurologic performance was significantly impaired only on the cylinder test after HI (p = 0.034), and MSC transplants improved it (p = 0.010). These suggest MSC can be a candidate for the treatment of neonatal HIE.

Risk factors for pulmonary artery hypertension in preterm infants with moderate or severe bronchopulmonary dysplasia.

Background: Despite the potential importance of pulmonary artery hypertension (PAH) in preterm infants with bronchopulmonary dysplasia (BPD), little is known about the risk factors for PAH. Objectives: To investigate the risk factors for PAH in preterm infants with BPD. Methods: Infants diagnosed with BPD were assigned to the PAH group or non-PAH group except for infants with mild BPD who had no PAH. PAH was diagnosed on the basis of echocardiograms demonstrating elevated right ventricle pressure beyond the postnatal age of 2 months. Logistic regression analysis was done for the multivariate assessment of the risk factors for PAH in preterm infants with moderate or severe BPD. Results: A total of 98 infants among 145 infants with BPD were divided into a PAH group (n = 25) or non-PAH group (n = 73), while the remaining 47 infants had mild BPD with no PAH. Among the study patients, survival rate of the PAH group was significantly lower than that of the non-PAH group. Infants with PAH had more severe cases of BPD and underwent longer durations of oxygen therapy, conventional or high-frequency ventilation, and hospitalization compared to those without PAH. Low 5-min Apgar scores (≤6; relative risk (RR) 6.2; 95% confidence interval (CI) 1.4–28.0; p = 0.017) and oligohydramnios (RR 7.7; 95% CI 2.0–29.6; p = 0.030) were found to be significant risk factors for PAH according to multivariate analysis. Conclusions: The present study shows that oligohydramnios is a specific risk factor for PAH in preterm infants with moderate or severe BPD.

Bronchopulmonary Dysplasia in a Rat Model Induced by Intra-amniotic Inflammation and Postnatal Hyperoxia: Morphometric Aspects

Antenatal inflammation is a known risk factor of bronchopulmonary dysplasia. The authors hypothesized that lipopolysaccharide (LPS) administration amplifies hyperoxia-induced lung injury in neonatal rats. LPS (0.5 or 1.0 μg) or normal saline was injected into the amniotic sacs of pregnant rats at 20 d gestation (term 22.5 d). After birth, rats were exposed to 85% oxygen or room air for 1 or 2 wk. Morphometric analysis of lungs was performed on 14 d. One week of hyperoxia without LPS administration resulted in modest lung injury. LPS at 0.5 μg alone did not alter lung morphology, but amplified the effect of 1 wk of hyperoxia resulting in marked inhibition of alveolarization (airspaces were enlarged and alveolar surface areas further reduced). LPS at 1.0 μg independently induced modest lung injury and also amplified the effect of 1 wk of hyperoxia. However, this sensitizing effect of LPS was not observed in rats subjected to 2 wks of hyperoxia, which in itself caused extensive lung injury (possibly masking the effect of LPS). The authors concluded that intra-amniotic LPS sensitizes neonatal rat lungs, and thus, amplifies the hyperoxia-induced inhibition of alveolarization.

The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes

OBJECTIVE To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes. DESIGN Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1beta. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1beta-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting. RESULTS The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100 micro M of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50 micro M. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10 micro M. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1beta, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50 micro M, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level. CONCLUSIONS Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100 micro M of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss.

Randomized Crossover Study of Neurally Adjusted Ventilatory Assist in Preterm Infants

OBJECTIVE To determine whether neurally adjusted ventilatory assist (NAVA), a new method of mechanical ventilation that delivers pressure assistance that is proportional to the electrical activity of the diaphragm (EAdi), could lower the inspiratory pressure and respiratory muscle load in preterm infants supported with ventilators. STUDY DESIGN Twenty-six mechanically ventilated preterm infants were randomized to crossover ventilation with NAVA and synchronized intermittent mandatory ventilation (SIMV) with pressure support (PS) for 4 hours each in a randomized order. A 1-hour interval for washout was provided between the 2 modes of ventilation. The ventilator settings were adjusted to maintain similar levels of end-tidal partial pressure of CO(2). The ventilator parameters, vital signs, and gas exchange effects under the 2 ventilatory modes were compared. RESULTS Nineteen infants completed the 9-hour crossover comparison protocol. Peak inspiratory pressure (PIP), work of breathing, and peak EAdi with NAVA were lower than those in SIMV with PS. Calculated tidal volume to peak EAdi ratio and PIP to peak EAdi ratio were higher with NAVA. There were no significant differences in mean airway pressure, inspiratory oxygen fraction, and blood gas values. The measurements of vital signs did not differ significantly between the 2 modes. CONCLUSION NAVA lowered PIP and reduced respiratory muscle load in preterm infants at equivalent inspiratory oxygen fraction and partial pressure of CO(2) of capillary blood in comparison with SIMV with PS.

Induction of Early Meconium Evacuation Promotes Feeding Tolerance in Very Low Birth Weight Infants

Background: A delay in reaching full enteral feeding is linked to poorer outcome in preterm neonates. Meconium retention has been viewed as a cause of bowel dysfunction in very low birth weight infants (VLBWI). Thus, adequate evacuation of meconium could help to promote feeding tolerance. Objectives: Our goal was to determine the effect of the induction of early meconium evacuation on feeding tolerance in VLBWI. Methods: An observational study involving two subsequent periods was performed in inborn infants with birth weights of <1,500 g, before (control) and after (study) the induction of early meconium evacuation by routine glycerin enema. The total duration of these periods was from January 2003 to December 2005. To evaluate feeding tolerance, we measured time to achieve full enteral feeding. Complications such as sepsis and necrotizing enterocolitis were compared. Results: The study group achieved full enteral feeding significantly faster than the control group (hazard ratio (HR) = 2.9; 95% confidence interval (CI) = 1.8–4.8), and this effect was more definite in infants with a birth weight of <1,000 g (HR = 4.6; 95% CI = 1.9–11.1). The study group passed first meconium faster than the control group (median = 1.4 vs. 3.7 days; p < 0.001). Sepsis, especially as determined by positive culture in central venouscatheter, was significantly reduced in the study group (7.7 vs. 27.8%; p = 0.02). Conclusions: The induction of early meconium evacuation had a significantly positive effect on feeding tolerance and sepsis prevention in VLBWI.

Correlation of urinary inflammatory and oxidative stress markers in very low birth weight infants with subsequent development of bronchopulmonary dysplasia.

Abstract Currently, bronchopulmonary dysplasia (BPD) occurs almost exclusively in pre-term infants. In addition to prematurity, other factors like oxygen toxicity and inflammation can contribute to the pathogenesis. This study aimed to compare urinary inflammatory and oxidative stress markers between the no/mild BPD group and moderate/severe BPD group and between BPD cases with significant early lung disease like respiratory distress syndrome (RDS) (‘classic’ BPD) and with minimal early lung disease (‘atypical’ BPD). A total of 60 patients who were a gestational age < 30 weeks or a birth weight < 1250 g were included. Urine samples were obtained on the 1st, 3rd and 7th day of life and measured the levels of leukotriene E4 (LTE4) and 8-hydroxydeoxyguanosine (8-OHdG). The 8-OHdG values on the 3rd day showed significant correlation to duration of mechanical ventilation. The 8-OHdG levels on the 7th day were the independent risk factor for developing moderate/severe BPD. In ‘classic’ BPD, the 8-OHdG values on the 3rd day were higher than those of ‘atypical’ BPD. In ‘atypical’ BPD, the LTE4 values on the 7th day were higher than the values in ‘classic’ BPD. These results suggest that oxidative DNA damage could be the crucial mechanism in the pathogenesis of current BPD and the ongoing inflammatory process could be an important mechanism in ‘atypical’ BPD.

Risk factors for periventricular-intraventricular hemorrhage in premature infants.

Periventricular-intraventricular hemorrhage (PV-IVH) is a major cause of neurological disabilities in preterm newborns. This study aimed to determine the perinatal factors associated with PV-IVH. We conducted a retrospective case-control study from preterm infants born at ≤34 weeks of gestation and admitted to Neonatal Intensive Care Units of Seoul National University Childrens Hospital and Seoul National University Bundang Hospital between June 2003 and December 2007. Neonates with no cranial sonographic data or infants transferred from other centers after three days of age were excluded. Of 1,044 eligible subjects, 59 infants with PV-IVH grade 2, 3, and 4 were allocated to the case group. The control group consisted of 118 infants without PV-IVH who were matched for gestational age and birth weight to each case of PV-IVH. At the multivariate logistic regression model, metabolic acidosis (odds ratio [OR]: 6.94; 95% confidence interval [CI]: 1.12-43.23) and use of inotropes (OR: 3.70; 95% CI: 1.16-11.84) were associated with an increased risk of PV-IVH. Maternal use of antenatal corticosteroids decreases the risk of PV-IVH (OR: 0.36; 95% CI: 0.14-0.92).

Intrauterine Inflammation as a Risk Factor for Persistent Ductus Arteriosus Patency after Cyclooxygenase Inhibition in Extremely Low Birth Weight Infants

OBJECTIVES To test the hypothesis that intrauterine inflammation increases prostaglandin production and may be a risk factor for persistent ductus arteriosus after therapy with indomethacin, a nonselective cyclooxygenase inhibitor. STUDY DESIGN Indomethacin therapy was started after confirming ductus arteriosus within 24 hours after birth in extremely low birth weight infants. After one cycle of therapy, infants with closed ductus were classified as responders, and those with patent ductus were classified as nonresponders. Multiple logistic regression analysis was used to determine important perinatal factors associated with persistent ductus arteriosus. Immunohistochemistry with cyclooxygenase antibodies and radioimmunoassay by 6-keto prostaglandin F(1α) kit were used to determine the relationship between intrauterine inflammation and ductal patency. RESULTS Forty-one infants were responders, and 37 infants were nonresponders. Responders were frequently small for gestational age; nonresponders frequently had lower gestational age, respiratory distress syndrome, and intrauterine inflammation. By multiple logistic regression analysis, respiratory distress syndrome and intrauterine inflammation were more frequent in nonresponders. Cyclooxygenase-1 expression in the umbilical arteries and plasma 6-keto prostaglandin F(1α) levels were higher in nonresponders. CONCLUSIONS Respiratory distress syndrome and intrauterine inflammation were independent risk factors for persistent ductus arteriosus after indomethacin therapy in extremely low-birth weight infants. Intrauterine inflammation may have a negative influence on ductus arteriosus closure via increased cyclooxygenase-1 activity.

The 'Effects of Transfusion Thresholds on Neurocognitive Outcome of Extremely Low Birth-Weight Infants (ETTNO)' Study: Background Aims, and Study Protocol

Background: Infants with extremely low birth weight uniformly develop anemia of prematurity and frequently require red blood cell transfusions (RBCTs). Although RBCT is widely practiced, the indications remain controversial in the absence of conclusive data on the long-term effects of RBCT. Objectives: To summarize the current equipoise and to outline the study protocol of the ‘Effects of Transfusion Thresholds on Neurocognitive Outcome of extremely low birth-weight infants (ETTNO)’ study. Methods: Review of the literature and design of a large pragmatic randomized controlled trial of restrictive versus liberal RBCT guidelines enrolling 920 infants with birth weights of 400–999 g with long-term neurodevelopmental follow-up. Results and Conclusions: The results of ETTNO will provide definite data about the efficacy and safety of restrictive versus liberal RBCT guidelines in very preterm infants.