Two-Year Outcomes After Minimally Invasive Surfactant Therapy in Preterm Infants: Follow-Up of the OPTIMIST-A Randomized Clinical Trial

Importance

The long-term effects of surfactant administration via a thin catheter (minimally invasive surfactant therapy [MIST]) in preterm infants with respiratory distress syndrome remain to be definitively clarified.

Objective

To examine the effect of MIST on death or neurodevelopmental disability (NDD) at 2 years' corrected age.

Design, Setting, and Participants

Follow-up study of a randomized clinical trial with blinding of clinicians and outcome assessors conducted in 33 tertiary-level neonatal intensive care units in 11 countries. The trial included 486 infants with a gestational age of 25 to 28 weeks supported with continuous positive airway pressure (CPAP). Collection of follow-up data at 2 years' corrected age was completed on December 9, 2022.

Interventions

Infants assigned to MIST (n = 242) received exogenous surfactant (200 mg/kg poractant alfa) via a thin catheter; those assigned to the control group (n = 244) received sham treatment.

Main Outcomes and Measures

The key secondary outcome of death or moderate to severe NDD was assessed at 2 years' corrected age. Other secondary outcomes included components of this composite outcome, as well as hospitalizations for respiratory illness and parent-reported wheezing or breathing difficulty in the first 2 years.

Results

Among the 486 infants randomized, 453 had follow-up data available (median gestation, 27.3 weeks; 228 females [50.3%]); data on the key secondary outcome were available in 434 infants. Death or NDD occurred in 78 infants (36.3%) in the MIST group and 79 (36.1%) in the control group (risk difference, 0% [95% CI, -7.6% to 7.7%]; relative risk [RR], 1.0 [95% CI, 0.81-1.24]); components of this outcome did not differ significantly between groups. Secondary respiratory outcomes favored the MIST group. Hospitalization with respiratory illness occurred in 49 infants (25.1%) in the MIST group vs 78 (38.2%) in the control group (RR, 0.66 [95% CI, 0.54-0.81]) and parent-reported wheezing or breathing difficulty in 73 (40.6%) vs 104 (53.6%), respectively (RR, 0.76 [95% CI, 0.63-0.90]).

Conclusions and Relevance

In this follow-up study of a randomized clinical trial of preterm infants with respiratory distress syndrome supported with CPAP, MIST compared with sham treatment did not reduce the incidence of death or NDD by 2 years of age. However, infants who received MIST had lower rates of adverse respiratory outcomes during their first 2 years of life.

Trial Registration

anzctr.org.au Identifier: ACTRN12611000916943.

Effect of Minimally Invasive Surfactant Therapy vs Sham Treatment on Death or Bronchopulmonary Dysplasia in Preterm Infants With Respiratory Distress Syndrome: The OPTIMIST-A Randomized Clinical Trial

IMPORTANCE

The benefits of surfactant administration via a thin catheter (minimally invasive surfactant therapy [MIST]) in preterm infants with respiratory distress syndrome are uncertain.

OBJECTIVE

To examine the effect of selective application of MIST at a low fraction of inspired oxygen threshold on survival without bronchopulmonary dysplasia (BPD).

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial including 485 preterm infants with a gestational age of 25 to 28 weeks who were supported with continuous positive airway pressure (CPAP) and required a fraction of inspired oxygen of 0.30 or greater within 6 hours of birth. The trial was conducted at 33 tertiary-level neonatal intensive care units around the world, with blinding of the clinicians and outcome assessors. Enrollment took place between December 16, 2011, and March 26, 2020; follow-up was completed on December 2, 2020.

INTERVENTIONS

Infants were randomized to the MIST group (n = 241) and received exogenous surfactant (200 mg/kg of poractant alfa) via a thin catheter or to the control group (n = 244) and received a sham (control) treatment; CPAP was continued thereafter in both groups unless specified intubation criteria were met.

MAIN OUTCOMES AND MEASURES

The primary outcome was the composite of death or physiological BPD assessed at 36 weeks' postmenstrual age. The components of the primary outcome (death prior to 36 weeks' postmenstrual age and BPD at 36 weeks' postmenstrual age) also were considered separately.

RESULTS

Among the 485 infants randomized (median gestational age, 27.3 weeks; 241 [49.7%] female), all completed follow-up. Death or BPD occurred in 105 infants (43.6%) in the MIST group and 121 (49.6%) in the control group (risk difference [RD], -6.3% [95% CI, -14.2% to 1.6%]; relative risk [RR], 0.87 [95% CI, 0.74 to 1.03]; P = .10). Incidence of death before 36 weeks' postmenstrual age did not differ significantly between groups (24 [10.0%] in MIST vs 19 [7.8%] in control; RD, 2.1% [95% CI, -3.6% to 7.8%]; RR, 1.27 [95% CI, 0.63 to 2.57]; P = .51), but incidence of BPD in survivors to 36 weeks' postmenstrual age was lower in the MIST group (81/217 [37.3%] vs 102/225 [45.3%] in the control group; RD, -7.8% [95% CI, -14.9% to -0.7%]; RR, 0.83 [95% CI, 0.70 to 0.98]; P = .03). Serious adverse events occurred in 10.3% of infants in the MIST group and 11.1% in the control group.

CONCLUSIONS AND RELEVANCE

Among preterm infants with respiratory distress syndrome supported with CPAP, minimally invasive surfactant therapy compared with sham (control) treatment did not significantly reduce the incidence of the composite outcome of death or bronchopulmonary dysplasia at 36 weeks' postmenstrual age. However, given the statistical uncertainty reflected in the 95% CI, a clinically important effect cannot be excluded.

TRIAL REGISTRATION

anzctr.org.au Identifier: ACTRN12611000916943.

Prolonged Tracheal Intubation and the Association Between Patent Ductus Arteriosus and Bronchopulmonary Dysplasia: A Secondary Analysis of the PDA-TOLERATE trial

In the PDA-TOLERATE trial, persistent (even for several weeks) moderate to large patent ductus arteriosus (PDA) was not associated with an increased risk of BPD when the infant required <10 days of intubation. However, in infants requiring intubation for ≥10 days, prolonged PDA exposure (≥11 days) was associated with an increased risk of moderate/severe BPD.

Lack of Equipoise in the PDA-TOLERATE Trial: A Comparison of Eligible Infants Enrolled in the Trial and Those Treated Outside the Trial

The PDA: TO LEave it alone or Respond And Treat Early trial compared the effects of 2 strategies for treatment of patent ductus arteriosus (PDA) in infants <28^0/7 weeks of gestation; however 137 potentially eligible infants were not recruited and received treatment of their PDA outside the PDA-TOLERATE trial due to "lack-of-physician-equipoise" (LPE). Despite being less mature and needing more respiratory support, infants with LPE had lower rates of mortality than enrolled infants. Infants with LPE treated before day 6 had lower rates of late respiratory morbidity than infants with LPE treated ≥day 6. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01958320.

Evaluating the Use of a Decision Aid for Parents Facing Extremely Premature Delivery: A Randomized Trial

OBJECTIVE

To assess decisional conflict and knowledge about prematurity among mothers facing extreme premature delivery when the counseling clinicians were randomized to counsel using a validated decision aid compared with usual counseling.

STUDY DESIGN

In this randomized trial, clinicians at 5 level III neonatal intensive care units in the US were randomized to supplement counseling using the decision aid or to counsel mothers in their usual manner. We enrolled mothers with threatened premature delivery at 22^0/7 to 25^6/7 weeks of gestation within 7 days of their counseling. The primary outcome was the Decisional Conflict Scale (DCS) score. One hundred mothers per group were enrolled to detect a clinically relevant effect size of 0.4 in the Decisional Conflict Scale. Secondary outcomes included knowledge about prematurity; scores on the Preparedness for Decision Making scale; and acceptability.

RESULTS

Ninety-two clinicians were randomized and 316 mothers were counseled. Of these, 201 (64%) mothers were enrolled. The median gestational age was 24.1 weeks (IQR 23.7-24.9). In both groups, DCS scores were low (16.3 ± 18.2 vs 16.8 ± 17, P = .97) and Preparedness for Decision Making scores were high (73.4 ± 28.3 vs 70.5 ± 31.1, P = .33). There was a significantly greater knowledge score in the decision aid group (66.2 ± 18.5 vs 57.2 ± 18.8, P = .005). Most clinicians and parents found the decision aid useful.

CONCLUSIONS

For parents facing extremely premature delivery, use of a decision aid did not impact maternal decisional conflict, but it significantly improved knowledge of complex information. A structured decision aid may improve comprehension of complex information.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT01713894.

PDA-TOLERATE Trial: An Exploratory Randomized Controlled Trial of Treatment of Moderate-to-Large Patent Ductus Arteriosus at 1 Week of Age

OBJECTIVE

To compare early routine pharmacologic treatment of moderate-to-large patent ductus arteriosus (PDA) at the end of week 1 with a conservative approach that requires prespecified respiratory and hemodynamic criteria before treatment can be given.

STUDY DESIGN

A total of 202 neonates of <28 weeks of gestation age (mean, 25.8 ± 1.1 weeks) with moderate-to-large PDA shunts were enrolled between age 6 and 14 days (mean, 8.1 ± 2.2 days) into an exploratory randomized controlled trial.

RESULTS

At enrollment, 49% of the patients were intubated and 48% required nasal ventilation or continuous positive airway pressure. There were no differences between the groups in either our primary outcome of ligation or presence of a PDA at discharge (early routine treatment [ERT], 32%; conservative treatment [CT], 39%) or any of our prespecified secondary outcomes of necrotizing enterocolitis (ERT, 16%; CT, 19%), bronchopulmonary dysplasia (BPD) (ERT, 49%; CT, 53%), BPD/death (ERT, 58%; CT, 57%), death (ERT,19%; CT, 10%), and weekly need for respiratory support. Fewer infants in the ERT group met the rescue criteria (ERT, 31%; CT, 62%). In secondary exploratory analyses, infants receiving ERT had significantly less need for inotropic support (ERT, 13%; CT, 25%). However, among infants who were ≥26 weeks gestational age, those receiving ERT took significantly longer to achieve enteral feeding of 120 mL/kg/day (median: ERT, 14 days [range, 4.5-19 days]; CT, 6 days [range, 3-14 days]), and had significantly higher incidences of late-onset non-coagulase-negative Staphylococcus bacteremia (ERT, 24%; CT,6%) and death (ERT, 16%; CT, 2%).

CONCLUSIONS

In preterm infants age <28 weeks with moderate-to-large PDAs who were receiving respiratory support after the first week, ERT did not reduce PDA ligations or the presence of a PDA at discharge and did not improve any of the prespecified secondary outcomes, but delayed full feeding and was associated with higher rates of late-onset sepsis and death in infants born at ≥26 weeks of gestation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01958320.

Human Umbilical Cord Blood Cells Ameliorate Motor Deficits in Rabbits in a Cerebral Palsy Model

Cerebral palsy (CP) has a significant impact on both patients and society, but therapy is limited. Human umbilical cord blood cells (HUCBC), containing various stem and progenitor cells, have been used to treat various brain genetic conditions. In small animal experiments, HUCBC have improved outcomes after hypoxic-ischemic (HI) injury. Clinical trials using HUCBC are underway, testing feasibility, safety and efficacy for neonatal injury as well as CP. We tested HUCBC therapy in a validated rabbit model of CP after acute changes secondary to HI injury had subsided. Following uterine ischemia at 70% gestation, we infused HUCBC into newborn rabbit kits with either mild or severe neurobehavioral changes. Infusion of high-dose HUCBC (5 × 10(6) cells) dramatically altered the natural history of the injury, alleviating the abnormal phenotype including posture, righting reflex, locomotion, tone, and dystonia. Half the high dose showed lesser but still significant improvement. The swimming test, however, showed that joint function did not restore to naïve control function in either group. Tracing HUCBC with either MRI biomarkers or PCR for human DNA found little penetration of HUCBC in the newborn brain in the immediate newborn period, suggesting that the beneficial effects were not due to cellular integration or direct proliferative effects but rather to paracrine signaling. This is the first study to show that HUCBC improve motor performance in a dose-dependent manner, perhaps by improving compensatory repair processes.

A Critical Review of Models of Perinatal Infection

One of the central, unanswered questions in perinatology is why preterm infants continue to have such poor long-term neurodevelopmental, cognitive and learning outcomes, even though severe brain injury is now rare. There is now strong clinical evidence that one factor underlying disability may be infection, as well as nonspecific inflammation, during fetal and early postnatal life. In this review, we examine the experimental evidence linking both acute and chronic infection/inflammation with perinatal brain injury and consider key experimental determinants, including the microglia response, relative brain and immune maturity and the pattern of exposure to infection. We highlight the importance of the origin and derivation of the bacterial cell wall component lipopolysaccharide. Such experimental paradigms are essential to determine the precise time course of the inflammatory reaction and to design targeted neuroprotective strategies to protect the perinatal brain from infection and inflammation.

Elevated spinal monoamine neurotransmitters after antenatal hypoxia-ischemia in rabbit cerebral palsy model

We hypothesized that a deficiency in the descending serotonergic input to spinal cord may underlie postnatal muscle hypertonia after global antenatal hypoxic-ischemic injury in a rabbit model of cerebral palsy. Neurotransmitter content was determined by HPLC in the spinal cord of newborns with and without muscle hypertonia after fetal global hypoxic-ischemic brain injury and naïve controls. Contrary to our hypothesis, serotonin levels in both cervical and lumbar expansions and norepinephrine in cervical expansion were increased in hypertonic kits relative to non-hypertonic kits and controls, with unchanged number of serotonergic cells in caudal raphe by stereological count. Serotonergic fiber length per unit of volume was also increased in hypertonic kits' cervical and lumbar spinal cord, both in dorsal and ventral horns. Gene expression of serotonin transporter was increased and 5-HTR2 receptors were decreased in hypertonic kits relative to controls in cervical and lumbar cord. Intrathecal administration of non-selective serotonin receptor inhibitor methysergide decreased muscle tone in hypertonic kits only. Conversely, intrathecal administration of serotonin solution increased muscle tone only in non-hypertonic kits. We speculate that maturation of serotonergic system in spinal cord may be directly affected by decreased corticospinal connectivity after antenatal hypoxic-ischemic brain injury. Following prenatal hypoxia-ischemia, newborn rabbits exhibit elevated levels of serotonin in the spinal cord that were linked to muscle hypertonia. Serotonergic terminal density was also increased in hypertonic newborns' spinal cord. Intrathecal administration of the non-selective serotonin receptor inhibitor methysergide decreased muscle tone in hypertonic newborns only. Elevated spinal serotonin thus suggests a novel pathophysiological mechanism of hypertonia in cerebral palsy.

Functional correlates of central white matter maturation in perinatal period in rabbits

Anisotropy indices derived from diffusion tensor imaging (DTI) are being increasingly used as biomarkers of central WM structural maturation, myelination and even functional development. Our hypothesis was that the rate of functional changes in central WM tracts directly reflects rate of changes in structural development as determined by DTI indices. We examined structural and functional development of four major central WM tracts with different maturational trajectories, including internal capsule (IC), corpus callosum (CC), fimbria hippocampi (FH) and anterior commissure (AC). Rabbits were chosen due to perinatal brain development being similar to humans, and four time points were studied: P1, P11, P18 and adults. Imaging parameters of structural maturation included fractional anisotropy (FA), mean and directional diffusivities derived from DTI, and T2 relaxation time. Axonal composition and degree of myelination were confirmed on electron microscopy. To assess functional maturation, conduction velocity was measured in myelinated and non-myelinated fibers by electrophysiological recordings of compound action potential in perfused brain slices. Diffusion indices and T2 relaxation time in rabbits followed a sigmoid curve during development similar to that for humans, with active changes even at premyelination stage. The shape of the developmental curve was different between the fiber tracts, with later onset but steeper rapid phase of development in IC and FH than in CC. The structural development was not directly related to myelination or to functional development. Functional properties in projection (IC) and limbic tracts (FH) matured earlier than in associative and commissural tracts (CC and AC). The rapid phase of changes in diffusion anisotropy and T2 relaxation time coincided with the development of functional responses and myelination in IC and FH between the second and third weeks of postnatal development in rabbits. In these two tracts, MRI indices could serve as surrogate markers of the early stage of myelination. However, the discordance between developmental change of diffusion indices, myelination and functional properties in CC and AC cautions against equating DTI index changes as biomarkers for myelination in all tracts.

Unmyelinated axon loss with postnatal hypertonia after fetal hypoxia

OBJECTIVE

White matter (WM) injury due to myelination defects is believed to be responsible for the motor deficits seen in cerebral palsy. We tested the hypothesis that the predominant injury is to functional electrical connectivity in unmyelinated WM fibers by conducting a longitudinal study of central WM tracts in newborn rabbit kits with hypertonia in our model of cerebral palsy.

METHODS

Pregnant rabbits at 70% gestation underwent 40-minute uterine ischemia. Motor deficits in newborn kits, including muscle hypertonia, were assessed by neurobehavioral testing. Major central WM tracts, including internal capsule, corpus callosum, anterior commissure, and fimbria hippocampi, were investigated for structural and functional injury using diffusion tensor magnetic resonance imaging (MRI), electrophysiological recordings of fiber conductivity in perfused brain slices, electron microscopy, and immunohistochemistry of oligodendrocyte lineage.

RESULTS

Motor deficits were observed on postnatal day 1 (P1) when WM tracts were unmyelinated. Myelination occurred later and was obvious by P18. Hypertonia was associated with microstructural WM injury and unmyelinated axon loss at P1, diagnosed by diffusion tensor MRI and electron microscopy. Axonal conductivity from electrophysiological recordings in hypertonic P18 kits decreased only in unmyelinated fibers, despite a loss in both myelinated and unmyelinated axons.

INTERPRETATION

Motor deficits in cerebral palsy were associated with loss of unmyelinated WM tracts. The contribution of injury to myelinated fibers that was observed at P18 is probably a secondary etiological factor in the motor and sensory deficits in the rabbit model of cerebral palsy.

Developmental susceptibility of neurons to transient tetrahydrobiopterin insufficiency and antenatal hypoxia-ischemia in fetal rabbits

Tetrahydrobiopterin (BH4) is important for normal brain development as congenital BH4 deficiencies manifest movement disorders at various childhood ages. BH4 transitions from very low levels in fetal brains to higher "adult" levels postnatally, with the highest levels in the thalamus. Maternal supplementation with the BH4 precursor sepiapterin reduces postnatal motor deficits and perinatal deaths after 40-min fetal hypoxia-ischemia (HI) at 70% gestation, suggesting that brain BH4 is important in improving function after HI. We tested the hypothesis that the intrinsically low concentrations of BH4 made fetal neurons vulnerable to added insults. Brains were obtained from naïve fetal rabbits or after 40-min HI, at 70% (E22) and 92% gestation (E29). Neuronal cultures were prepared from basal ganglia, cortex, and thalamus, regions with different intrinsic levels of BH4. Cultures were grown with or without added BH4 for 48h. Cell survival and mitochondrial function were determined by flow cytometry. At E22, thalamic cells had the lowest survival rate in a BH4-free milieu, in both control and HI groups, whereas BH4 supplementation ex vivo increased neuronal survival only in HI cells. Neuronal survival was similar in all regions without BH4 at E29. BH4 supplementation increased cell survival and cells with intact mitochondrial membrane potential, from basal ganglia and cortex, but not thalamus. After E29 HI, however, the benefit of BH4 was limited to cortical neurons. We conclude that BH4 is important for fetal neuronal survival after HI especially in the premature thalamus. Supplementation of BH4 has a greater benefit at an earlier gestational age.

Enteral feeding during indomethacin and ibuprofen treatment of a patent ductus arteriosus

OBJECTIVE

To test the hypothesis that infants who are just being introduced to enteral feedings will advance to full enteral nutrition at a faster rate if they receive "trophic" (15 mL/kg/d) enteral feedings while receiving indomethacin or ibuprofen treatment for patent ductus arteriosus.

STUDY DESIGN

Infants were eligible for the study if they were 23(1/7)-30(6/7) weeks' gestation, weighed 401-1250 g at birth, received maximum enteral volumes ≤60 mL/kg/d, and were about to be treated with indomethacin or ibuprofen. A standardized "feeding advance regimen" and guidelines for managing feeding intolerance were followed at each site (N = 13).

RESULTS

Infants (N = 177, 26.3 ± 1.9 weeks' mean ± SD gestation) were randomized at 6.5 ± 3.9 days to receive "trophic" feeds ("feeding" group, n = 81: indomethacin 80%, ibuprofen 20%) or no feeds ("fasting [nil per os]" group, n = 96: indomethacin 75%, ibuprofen 25%) during the drug administration period. Maximum daily enteral volumes before study entry were 14 ± 15 mL/kg/d. After drug treatment, infants randomized to the "feeding" arm required fewer days to reach the study's feeding volume end point (120 mL/kg/d). Although the enteral feeding end point was reached at an earlier postnatal age, the age at which central venous lines were removed did not differ between the 2 groups. There were no differences between the 2 groups in the incidence of infection, necrotizing enterocolitis, spontaneous intestinal perforation, or other neonatal morbidities.

CONCLUSION

Infants required less time to reach the feeding volume end point if they were given "trophic" enteral feedings when they received indomethacin or ibuprofen treatments.

Intrauterine fetal demise can be remote from the inciting insult in an animal model of hypoxia-ischemia

BACKGROUND

Fetal hypoxia-ischemia (H-I) results in significant morbidity and mortality. Little is known about the timing of death in human stillbirths. The vulnerability of the fetus varies with age at the time of insult, but it is unknown what happens to the timing of fetal death in relation to a fetal insult. We asked the question of whether the timing of fetal death was influenced by the age at which the insult occurred.

METHODS

Fetal H-I was achieved at three ages by sustained uterine ischemia in rabbits, mimicking the acute placental insufficiency of placental abruption.

RESULTS

H-I at 22 d gestation (E22) resulted in fewer perinatal deaths than at E25 and E29. Fetal deaths were grouped into early and late perinatal deaths. Early perinatal death mostly occurred immediately after H-I and these fetuses delivered before term. Late perinatal death occurred between the insult and delivery at term gestation. Early perinatal death occurred more often in the E25 hypoxic-ischemic group as compared with those of the E22 hypoxic-ischemic group.

CONCLUSION

There is an increasing vulnerability to hypoxia with increasing gestational age. Perinatal deaths may occur long after the episode of H-I. The timing of an intrauterine hypoxic-ischemic event cannot be inferred from the detection of fetal death.

Near-term fetal hypoxia-ischemia in rabbits: MRI can predict muscle tone abnormalities and deep brain injury

BACKGROUND AND PURPOSE

The pattern of antenatal brain injury varies with gestational age at the time of insult. Deep brain nuclei are often injured at older gestational ages. Having previously shown postnatal hypertonia after preterm fetal rabbit hypoxia-ischemia, the objective of this study was to investigate the causal relationship between the dynamic regional pattern of brain injury on MRI and the evolution of muscle tone in the near-term rabbit fetus.

METHODS

Serial MRI was performed on New Zealand white rabbit fetuses to determine equipotency of fetal hypoxia-ischemia during uterine ischemia comparing 29 days gestation (E29, 92% gestation) with E22 and E25. E29 postnatal kits at 4, 24, and 72 hours after hypoxia-ischemia underwent T2- and diffusion-weighted imaging. Quantitative assessments of tone were made serially using a torque apparatus in addition to clinical assessments.

RESULTS

Based on the brain apparent diffusion coefficient, 32 minutes of uterine ischemia was selected for E29 fetuses. At E30, 58% of the survivors manifested hind limb hypotonia. By E32, 71% of the hypotonic kits developed dystonic hypertonia. Marked and persistent apparent diffusion coefficient reduction in the basal ganglia, thalamus, and brain stem was predictive of these motor deficits.

CONCLUSIONS

MRI observation of deep brain injury 6 to 24 hours after near-term hypoxia-ischemia predicts dystonic hypertonia postnatally. Torque-displacement measurements indicate that motor deficits in rabbits progressed from initial hypotonia to hypertonia, similar to human cerebral palsy, but in a compressed timeframe. The presence of deep brain injury and quantitative shift from hypo- to hypertonia may identify patients at risk for developing cerebral palsy.

Cell therapy for neonatal hypoxia-ischemia and cerebral palsy

Perinatal hypoxic-ischemic brain injury remains a major cause of cerebral palsy. Although therapeutic hypothermia is now established to improve recovery from hypoxia-ischemia (HI) at term, many infants continue to survive with disability, and hypothermia has not yet been tested in preterm infants. There is increasing evidence from in vitro and in vivo preclinical studies that stem/progenitor cells may have multiple beneficial effects on outcome after hypoxic-ischemic injury. Stem/progenitor cells have shown great promise in animal studies in decreasing neurological impairment; however, the mechanisms of action of stem cells, and the optimal type, dose, and method of administration remain surprisingly unclear, and some studies have found no benefit. Although cell-based interventions after completion of the majority of secondary cell death appear to have potential to improve functional outcome for neonates after HI, further rigorous testing in translational animal models is required before randomized controlled trials should be considered.

Involvement of neuronal nitric oxide synthase in ongoing fetal brain injury following near-term rabbit hypoxia-ischemia

Neuronal nitric oxide synthase (nNOS) and nitric oxide (NO) are implicated in neuronal injury following acute hypoxia-ischemia (HI). Our hypothesis was that NO from nNOS is responsible for ongoing mitochondrial dysfunction in near-term fetal HI. Recently, we synthesized new selective nNOS inhibitors that prevent the cerebral palsy phenotype in our animal model. We tested the efficacy of a selective nNOS inhibitor (JI-8) in fetal brains after in utero HI in our rabbit model. Brain slices at 29 days gestation were obtained after in utero HI, and immediately cultured in medium containing JI-8 or saline for 3-6 days. Mitochondrial membrane integrity and function were determined by flow cytometry using rhodamine 123 and JC-1, and cell death by using propidium iodide. JI-8 decreased NO production in brain slices and also showed significant preservation of mitochondrial function at both 3 and 6 days (p < 0.05) when compared with saline and inducible NOS inhibitor 1400W. There was no difference in cell death. In conclusion, nNOS is involved in ongoing mitochondrial dysfunction after in utero HI. The subacute brain slice model could be a tool for studying the mechanisms involved in ongoing neuronal injury, and for rapidly assessing potential neuroprotectants.

Neuronal nitric oxide synthase inhibition prevents cerebral palsy following hypoxia-ischemia in fetal rabbits: comparison between JI-8 and 7-nitroindazole

Cerebral palsy and death are serious consequences of perinatal hypoxia-ischemia (HI). Important concepts can now be tested using an animal model of cerebral palsy. We have previously shown that reactive oxygen and nitrogen species are produced in antenatal HI. A novel class of neuronal nitric oxide synthase (nNOS) inhibitors have been designed, and they ameliorate postnatal motor deficits when administered prior to the hypoxic-ischemic insult. This study asks how the new class of inhibitors, using JI-8 (K(i) for nNOS: 0.014 μM) as a representative, compare with the frequently used nNOS inhibitor 7-nitroindazole (7-NI; K(i): 0.09 ± 0.024 μM). A theoretical dose equivalent to 75 K(i) of JI-8 or equimolar 7-NI was administered to pregnant rabbit dams 30 min prior to and immediately after 40 min of uterine ischemia at 22 days gestation (70% term). JI-8 treatment resulted in a significant decrease in NOS activity (39%) in fetal brain homogenates acutely after HI, without affecting maternal blood pressure and heart rate. JI-8 treatment resulted in 33 normal kits, 2 moderately and 13 severely affected kits and 5 stillbirths, compared with 8 normal, 3 moderately affected and 5 severely affected kits and 10 stillbirths in the 7-NI group. In terms of neurobehavioral outcome, 7-NI was not different from saline treatment, while JI-8 was superior to saline and 7-NI in its protective effect (p < 0.05). In the surviving kits, JI-8 significantly improved the locomotion score over both saline and 7-NI scores. JI-8 was also significantly superior to saline in preserving smell, muscle tone and righting reflex function, but 7-NI did not show significant improvement. Furthermore, a 100-fold increase in the dose (15.75 μmol/kg) of 7-NI significantly decreased systolic blood pressure in the dam, while JI-8 did not. The new class of inhibitors such as JI-8 shows promise in the prevention of cerebral palsy and is superior to the previously more commonly used nNOS inhibitor.

Timing of appearance of late oligodendrocyte progenitors coincides with enhanced susceptibility of preterm rabbit cerebral white matter to hypoxia-ischemia

Emerging evidence supports that premature infants are susceptible to both cerebral white and gray matter injury. In a fetal rabbit model of placental insufficiency, preterm rabbits at embryonic day 22 (E22) exhibited histologic evidence of gray matter injury but minimal white matter injury after global hypoxia-ischemia (H-I). We hypothesized that the dissociation between susceptibility to gray and white matter injury at E22 was related to the timing of appearance of late oligodendrocyte progenitors (preOLs) that are particularly vulnerable in preterm human white matter lesions. During normal rabbit oligodendrocyte (OL) lineage progression, early OL progenitors predominated at E22. PreOL density increased between E24 and E25 in major forebrain white matter tracts. After H-I at E22 and E25, we observed a similar magnitude of cerebral H-I, assessed by cortical microvascular blood flow, and gray matter injury, assessed by caspase activation. However, the increased preOL density at E25 was accompanied by a significant increase in acute white matter injury after H-I that coincided with enhanced preOL degeneration. At E29, significant white matter atrophy developed after H-I at E25 but not E22. Thus, the timing of appearance of preOLs coincided with onset of a developmental window of enhanced white but not gray matter susceptibility to H-I.

Tetrahydrobiopterin in the prevention of hypertonia in hypoxic fetal brain

OBJECTIVE

Tetrahydrobiopterin (BH(4)) deficiency is a cause of dystonia at birth. We hypothesized that BH(4) is a developmental factor determining vulnerability of the immature fetal brain to hypoxic-ischemic injury and subsequent motor deficits in newborns.

METHODS

Pregnant rabbits were subjected to 40-minute uterine ischemia, and fetal brains were investigated for global and focal changes in BH(4). Newborn kits were assessed by neurobehavioral tests following vehicle and sepiapterin (BH(4) analog) treatment of dams.

RESULTS

Naive fetal brains at 70% gestation (E22) were severely deficient for BH(4) compared with maternal and other fetal tissues. BH(4) concentration rapidly increased normally in the perinatal period, with the highest concentrations found in the thalamus compared with basal ganglia, frontal, occipital, hippocampus, and parietal cortex. Global sustained 40-minute hypoxia-ischemia depleted BH(4) in E22 thalamus and to a lesser extent in basal ganglia, but not in the frontal, occipital, and parietal regions. Maternal supplementation prior to hypoxia-ischemia with sepiapterin increased BH(4) in all brain regions and especially in the thalamus, but did not increase the intermediary metabolite, 7,8-BH(2). Sepiapterin treatment also reduced incidence of severe motor deficits and perinatal death following E22 hypoxia-ischemia.

INTERPRETATION

We conclude that early developmental BH(4) deficiency plays a critical role in hypoxic-ischemic brain injury. Increasing brain BH(4) via maternal supplementation may be an effective strategy in preventing motor deficits from antenatal hypoxia-ischemia.

Hypoxia-ischemia causes persistent movement deficits in a perinatal rabbit model of cerebral palsy: assessed by a new swim test

The relationship of movement between different muscle groups has not been quantified before in the newborn period. Cerebral palsy (CP), which often occurs as a result of perinatal hypoxia-ischemia (H-I), is categorized depending on clinical presentation, brain region involvement and extent of involvement. In order to test different brain region involvement, this study investigates individual and multi-joint involvement in a rabbit model of CP. Pregnant rabbits at 70% gestation were subjected to 40-min uterine ischemia. Newborn rabbit kits were subjected to a swim test at 5 time points over the first 11 days of life. H-I kits were divided into hypertonic and non-hypertonic groups based on muscle tone at birth. The ranges and velocity of angular movement of the forelimb and hind limb joints (wrist, elbow, shoulder, ankle, knee and hip) during supported swimming were determined. Severely impaired (hypertonic) animals have significantly reduced range and angular velocity of joint motion, which do not improve over time. The non-hypertonic group showed deficits in wrist and hind limb movements that were not evident on prolonged observation. Preventive treatment with an inhibitor of neuronal nitric oxide synthase decreased the incidence of severely impaired kits; the non-hypertonic kits showed a different pattern of swimming. Supported swimming allows quantification of limb and joint motion in the principal plane of movement in the absence of weight bearing and decreases the need for balance control. Identification and quantification of milder deficits allows mechanistic studies in the causation of H-I injury as well as estimation of recovery with therapeutic agents.

Selective neuronal nitric oxide synthase inhibitors and the prevention of cerebral palsy

OBJECTIVE

To design a new class of selective neuronal nitric oxide synthase (NOS) inhibitors, and demonstrate that administration in a rabbit model for cerebral palsy (CP) prevents hypoxia-ischemia-induced deaths and reduces the number of newborn kits exhibiting signs of CP.

METHODS

We used a novel computer-based drug design method called fragment hopping to identify new chemical entities, synthesized them, and conducted in vitro enzyme inhibition studies with the three isozymes of NOS and in vivo experiments to monitor cardiovascular effects on pregnant rabbit dams, NOS activity, and NO(x) (NO and NO(2)) concentration in fetal brain, and assess neurobehavioral effects on kits born to saline- and compound treated dams.

RESULTS

The computer-based design led to the development of powerful and highly selective compounds for inhibition of neuronal NOS over the other isozymes. After maternal administration in a rabbit model of CP, these compounds were found to distribute to fetal brain, to be nontoxic, without cardiovascular effects, inhibit fetal brain NOS activity in vivo, reduce NO concentration in fetal brain, and dramatically ameliorate deaths and number of newborn kits exhibiting signs of CP.

INTERPRETATION

This approach may lead to new preventive strategies for CP.

Inclusive K(S);(0)K(S);(0) resonance production in ep collisions at HERA

Inclusive K_{S};{0}K_{S};{0} production in ep collisions at the DESY ep collider HERA was studied with the ZEUS detector using an integrated luminosity of 0.5 fb;{-1}. Enhancements in the mass spectrum were observed and are attributed to the production of f_{2}(1270)/a_{2};{0}(1320), f_{2};{'}(1525) and f_{0}(1710). Masses and widths were obtained using a fit which takes into account theoretical predictions based on SU(3) symmetry arguments, and are consistent with the Particle Data Group values. The f_{0}(1710) state, which has a mass consistent with a glueball candidate, was observed with a statistical significance of 5 standard deviations. However, if this state is the same as that seen in gammagamma-->K_{S};{0}K_{S};{0}, it is unlikely to be a pure glueball state.

Major neurological events following foam sclerotherapy

Aim

This report describes two complications of severe neurologic alterations (TIA, CVA) after foamed sclerotherapy injection.

Methods

Using foam sclerotherapy in accepted concentrations, volume, and in standard ratio of air to sclerosant, two serious neurologic complications occurred.

Results

In both cases described, unknown atrial communications existed resulting in foam emboli. One case involving the vertebral system resolved without treatment. The other involving the cerebral system was treated with hyperbaric oxygen.

Conclusions

Foam sclerotherapy can cause serious neurologic phenomenon even though the incidence is rarely described. Immediate treatment with 100% O2 and possible hyperbaric O2 therapy should be considered.

Serial diffusion tensor imaging detects white matter changes that correlate with motor outcome in premature infants

The objective of the study was to assess predictive value of serial diffusion tensor MRI (DTI) for the white matter injury and neurodevelopmental outcome in a cohort of premature infants. Twenty-four infants less than 32 weeks' gestation were stratified to a control group (n = 11), mild brain injury with grades 1-2 of intraventricular hemorrhage (n = 6) and severe brain injury with grades 3-4 intraventricular hemorrhage (n = 4). Serial DTI studies were performed at around 30 and 36 weeks' gestation. Fractional anisotropy (FA) and apparent diffusion coefficient were calculated. Twelve infants were followed up for developmental outcome. Developmental testing was performed with the Bayley Scales of Infant Development to obtain psychomotor index (Performance Developmental Index). Apparent diffusion coefficient was higher in the severe injury group at the second MRI in the central and occipital white matter, and corona radiata; FA was lower in optic radiation compared to controls. Performance Developmental Index score correlated with FA on the scan taken at the 30th week and inversely with the change of FA between scans in internal capsule and occipital white matter. A low value of FA at 30 weeks and a higher change of FA predicted less favorable motor outcome at 2 years and suggests that early subtle white matter injury can be detected in premature infants even without obvious signs of injury.

Fetal brain magnetic resonance imaging response acutely to hypoxia-ischemia predicts postnatal outcome

OBJECTIVE

Cerebral palsy (CP) is caused by either hypoxia-ischemia (H-I) or long-standing causative factors such as inflammation or genetics. Multiple pathophysiological events over time are thought to contribute eventually to cerebral palsy. Our objective was to examine whether the immediate response of the fetus to an acute H-I event determined the motor deficits associated with cerebral palsy.

METHODS

Serial diffusion-weighted imaging were performed on 79% gestation New Zealand white rabbits using a 3-Tesla magnetic resonance scanner during 40 minutes of uterine ischemia, 20 minutes of reperfusion, and at 4, 24, and 72 hours. Individual fetuses were tracked to near term, and the delivered kits were divided into hypertonic H-I (n = 18), nonhypertonic H-I (n = 9), stillbirth H-I (n = 4), and control groups (n = 16).

RESULTS

The hypertonia group had significantly less of a nadir in apparent diffusion coefficient (ADC) during H-I (71.6 +/- 23.8% vs 84.5 +/- 9.3% baseline) and slower and incomplete recovery of ADC during reperfusion compared with the nonhypertonic group. All fetuses in the hypertonic and stillbirth groups had an ADC nadir of less than 0.83 microm(2)/msec (70.3% decrease from baseline), whereas 94% of control animals had an ADC nadir greater than this value. The difference between outcome groups was the largest at 4 hours reperfusion and persisted for 24 hours.

INTERPRETATION

Serial fetal brain scans indicate that the immediate response of a fetus to H-I is crucial to the development of hypertonia. If the fetal brain can be scanned at the time of insult, ADC changes can predict which fetuses will have an unfavorable outcome.

A model of cerebral palsy from fetal hypoxia-ischemia

Disorders of the maternal-placental-fetal unit often results in fetal brain injury, which in turn results in one of the highest burdens of disease, because of the lifelong consequences and cost to society. Investigating hypoxia-ischemia in the perinatal period requires the factoring of timing of the insult, determination of end-points, taking into account the innate development, plasticity, and enhanced recovery. Prenatal hypoxia-ischemia is believed to account for a majority of cerebral palsy cases. We have modeled sustained and repetitive hypoxia-ischemia in the pregnant rabbit in utero to mimic the insults of abruptio placenta and labor, respectively. Rabbits have many advantages over other animal species; principally, their motor development is in the perinatal period, akin to humans. Sustained hypoxia-ischemia at 70% (E22) and 79% (E25) caused stillbirths and multiple deficits in the postnatal survivors. The deficits included impairment in multiple tests of spontaneous locomotion, reflex motor activity, motor responses to olfactory stimuli, and the coordination of suck and swallow. Hypertonia was observed in the E22 and E25 survivors and persisted for at least 11 days. Noninvasive imaging using MRI suggests that white matter injury in the internal capsule could explain some of the hypertonia. Further investigation is underway in other vulnerable regions such as the basal ganglia, thalamus and brain stem, and development of other noninvasive determinants of motor deficits. For the first time critical mechanistic pathways can be tested in a clinically relevant animal model of cerebral palsy.

White matter injury correlates with hypertonia in an animal model of cerebral palsy

Hypertonia and postural deficits are observed in cerebral palsy and similar abnormalities are observed in postnatal rabbits after antenatal hypoxia-ischemia. To explain why some kits become hypertonic, we hypothesized that white matter injury was responsible for the hypertonia. We compared newborn kits at postnatal day 1 (P1) with and without hypertonia after in vivo global fetal hypoxia-ischemia in pregnant rabbits at 70% gestation. The aim was to examine white matter injury by diffusion tensor magnetic resonance imaging indices, including fractional anisotropy (FA). At P1, FA and area of white matter were significantly lower in corpus callosum, internal capsule, and corona radiata of the hypertonic kits (n=32) than that of controls (n=19) while nonhypertonic kits (n=20) were not different from controls. The decrease in FA correlated with decrease in area only in hypertonia. A threshold of FA combined with area identified only hypertonic kits. A reduction in volume and loss of phosphorylated neurofilaments in corpus callosum and internal capsule were observed on immunostaining. Concomitant hypertonia with ventriculomegaly resulted in a further decrease of FA from P1 to P5 while those without ventriculomegaly had a similar increase of FA as controls. Thus, hypertonia is associated with white matter injury, and a population of hypertonia can be identified by magnetic resonance imaging variables. The white matter injury manifests as a decrease in the number and density of fiber tracts causing the decrease in FA and volume. Furthermore, the dynamic response of FA may be a good indicator of the plasticity and repair of the postnatal developing brain.

Sensory deficits and olfactory system injury detected by novel application of MEMRI in newborn rabbit after antenatal hypoxia–ischemia

Sensory deficits are frequently observed in cerebral palsy patients. The motor response to smell was found to be abnormal in an animal model of cerebral palsy following fetal hypoxia-ischemia. We hypothesized that fetal hypoxia-ischemia causes long-lasting and selective olfactory tract injury. A population of newborn rabbits with motor deficits was selected after spontaneous delivery following uterine ischemia at 22 days gestation (E22, 70% term). MnCl(2), 20 mg/kg, was administered in both nostrils at postnatal day 1 (E32). One nostril was occluded to control for smell augmentation through the other open nostril by intermittent amyl acetate stimulation for 6 h. T1-weighted MRI images were obtained on newborn rabbits. Amyl acetate exposure increased augmentation of Mn(2+) uptake in olfactory epithelium on the open side in control group but the augmentation was decreased after hypoxia. The proportion of animals with a greater enhancement in the open side increased in controls after amyl acetate, but not in hypoxia. Mn(2+) took longer to arrive at the olfactory bulbs and the rate of subsequent increase was slower in hypoxia. Concomitantly, the thickness of olfactory epithelium and the number of mature olfactory neurons, detected on olfactory marker protein immunostaining, were significantly less in the hypoxic group. Functional MRI studies are superior to neurobehavioral smell testing in the rabbit kits as they are more sensitive and quantifiable measures and do not depend upon the motor response. Antenatal hypoxia-ischemia causes long-lasting injury to neuronal tracts of the olfactory system including olfactory epithelium.

Developmental changes in diffusion anisotropy coincide with immature oligodendrocyte progression and maturation of compound action potential

Disruption of oligodendrocyte lineage progression is implicated in the white-matter injury that occurs in cerebral palsy. We have previously published a model in rabbits consistent with cerebral palsy. Little is known of normal white-matter development in perinatal rabbits. Using a multidimensional approach, we defined the relationship of oligodendrocyte lineage progression and functional maturation of axons to structural development of selected cerebral white-matter tracts as determined by diffusion tensor imaging (DTI). Immunohistochemical studies showed that late oligodendrocyte progenitors appear at gestational age 22 [embryonic day 22 (E22)], whereas immature oligodendrocytes appear at E25, and both increase rapidly with time (approximately 13 cells/mm2/d) until the onset of myelination. Myelination began at postnatal day 5 (P5) (E36) in the internal capsule (IC) and at P11 in the medial corpus callosum (CC), as determined by localization of sodium channels and myelin basic protein. DTI of the CC and IC showed that fractional anisotropy (FA) increased rapidly between E25 and P1 (E32) (11% per day) and plateaued (<5% per day) after the onset of myelination. Postnatal maturation of the compound action potential (CAP) showed a developmental pattern similar to FA, with a rapid rise between E29 and P5 (in the CC, 18% per day) and a slower rise from P5 to P11 (in the CC, <5% per day). The development of immature oligodendrocytes after E29 coincides with changes in FA and CAP area in both the CC and IC. These findings suggest that developmental expansion of immature oligodendrocytes during the premyelination period may be important in defining structural and functional maturation of the white matter.

Model of cerebral palsy in the perinatal rabbit

Perinatal brain injury results in one of the highest burdens of disease in view of the lifelong consequences and is of enormous cost to society. This makes it imperative to develop better animal models that mimic the human condition. Many neurodevelopmental deficits, such as cerebral palsy, are believed to be a result of prenatal hypoxia-ischemia in humans. Fetal global hypoxia-ischemia is most commonly a consequence of acute placental insufficiency. Our laboratory has modeled in utero sustained and repetitive hypoxia-ischemia in the pregnant rabbit to mimic the insults of abruptio placenta and labor, respectively. Sustained hypoxia-ischemia at 70% (22 days' gestation) and 79% (25 days' gestation) and repetitive hypoxia-ischemia at 90% gestation (28 days' gestation) caused stillbirths and multiple deficits in the postnatal survivors. The deficits included impairment in multiple tests of spontaneous locomotion, reflex motor activity, motor responses to olfactory stimuli, and the coordination of suck and swallow. Hypertonia was observed in the 22 and 25 days' gestation survivors but not in the 28 days' gestation group. Hypertonic survivors were artificially fed and found to have the motor deficits persist for at least 11 postnatal days. A spectrum of brain abnormalities is found on magnetic resonance imaging. This is the first animal model to mimic cerebral palsy. The findings also suggest a window of vulnerability during brain development when the injury results in hypertonia in newborn pups.

Preterm fetal hypoxia-ischemia causes hypertonia and motor deficits in the neonatal rabbit: a model for human cerebral palsy?

Prenatal hypoxia-ischemia to the developing brain has been strongly implicated in the subsequent development of the hypertonic motor deficits of cerebral palsy (CP) in premature and full-term infants who present with neonatal encephalopathy. Despite the enormous impact of CP, there is no animal model that reproduces the hypertonia and motor disturbances of this disorder. We report a rabbit model of in utero placental insufficiency, in which hypertonia is accompanied by marked abnormalities in motor control. Preterm fetuses (67-70% gestation) were subjected to sustained global hypoxia. The dams survived and gave spontaneous birth. At postnatal day 1, the pups that survived were subjected to a battery of neurobehavioral tests developed specifically for these animals, and the tests were videotaped and scored in a masked manner. Newborn pups of hypoxic groups displayed significant impairment in multiple tests of spontaneous locomotion, reflex motor activity, and the coordination of suck and swallow. Increased tone of the limbs at rest and with active flexion and extension were observed in the survivors of the preterm insult. Histopathological studies identified a distinct pattern of acute injury to subcortical motor pathways that involved the basal ganglia and thalamus. Persistent injury to the caudate putamen and thalamus at P1 was significantly correlated with hypertonic motor deficits in the hypoxic group. Antenatal hypoxia-ischemia at preterm gestation results in hypertonia and abnormalities in motor control. These findings provide a unique behavioral model to define mechanisms and sequelae of perinatal brain injury from antenatal hypoxia-ischemia.

Involvement of napsin A in the C- and N-terminal processing of surfactant protein B in type-II pneumocytes of the human lung

Surfactant protein B (SP-B) is a critical component of pulmonary surfactant, and a deficiency of active SP-B results in fatal respiratory failure. SP-B is synthesized by type-II pneumocytes as a 42-kDa propeptide (proSP-B), which is posttranslationally processed to an 8-kDa surface-active protein. Napsin A is an aspartic protease expressed in type-II pneumocytes. To characterize the role of napsin A in the processing of proSP-B, we colocalized napsin A and precursors of SP-B as well as SP-B in the Golgi complex, multivesicular, composite, and lamellar bodies of type-II pneumocytes in human lungs using immunogold labeling. Furthermore, we measured aspartic protease activity in isolated lamellar bodies as well as isolated human type-II pneumocytes and studied the cleavage of proSP-B by napsin A and isolated lamellar bodies in vitro. Both, napsin A and isolated lamellar bodies cleaved proSP-B and generated three identical processing products. Processing of proSP-B by isolated lamellar bodies was completely inhibited by an aspartic protease inhibitor. Sequence analysis of proSP-B processing products revealed several cleavage sites in the N- and C-terminal propeptides as well as one in the mature peptide. Two of the four processing products generated in vitro were also detected in type-II pneumocytes. In conclusion, our results show that napsin A is involved in the N- and C-terminal processing of proSP-B in type-II pneumocytes.

Hypoxia-ischemia in fetal rabbit brain increases reactive nitrogen species production: quantitative estimation of nitrotyrosine

Reactive nitrogen species (RNS) cause nitration of protein-bound tyrosine that is used as biomarker for detection. We hypothesized that RNS are formed in fetal rabbit brain following acute placental insufficiency. Near-term pregnant rabbits were randomized to either repetitive uterine ischemia or no ischemia, and fetal brains obtained. Only one electrochemical HPLC method (of three tested) was successful in detecting brain nitrotyrosine. Protein nitrotyrosine was significantly increased following cumulative 40 min ischemia and 20 min reperfusion compared to controls. Repetitive hypoxia-ischemia results in the increased formation of RNS in near-term fetal brains.

The in vitro fate of rabbit fetal brain cells after acute in vivo hypoxia

In the investigation of ischemia-induced brain damage, traditional methods using histopathology estimate brain cell death at a time remote from ischemic insult. These observations fail to take into account endogenous repair processes or ongoing injury cascades like apoptosis. The cells that are injured but not killed initially are the population most amenable to rescue. The hypothesis was that in vivo uterine ischemia-reperfusion would result in more cell death and apoptosis in fetal brain cells cultured in vitro. Near-term, 29 d gestation, pregnant New Zealand White rabbits were subjected to repetitive uterine ischemia for a cumulative time of 40 min ischemia and 20 min reperfusion. Immediately after uterine ischemia, the fetal brains were removed and dissociated into a cell suspension. The ischemic group had more cell death than non-ischemic controls as assessed by Trypan Blue exclusion and propidium iodide (PI) uptake on a flow cytometer. Aliquots of cells were plated and cultured for 24 and 48 hr. The ischemic group had significantly more cell death (propidium iodide) than non-ischemic controls at 24 hr and significantly more apoptosis, as assessed by annexin-V binding in cells at 24 hr and caspase-3 activity at 48 hr. Fewer cells attached to the culture plates at 48 hr in the ischemia group. After uterine ischemia, certain fetal brain cells die immediately, and other cells undergo ongoing damage resulting in necrosis and apoptosis that is manifest later. This method offers insight into the fate of those cells and provides a tool for assessing interventions to decrease cell injury.

Relation of maternal ethnicity to infant birthweight in east London, England

OBJECTIVE

We sought to determine whether black race is a risk factor for very low birthweight in a developed country other than the United States.

DESIGN

A cross-sectional study was performed.

SETTING

We analyzed a dataset of 1987-1990 birth records from three hospitals in East London, England.

PARTICIPANTS

All live born African (N = 3,495), West Indian (N = 3,471), and European white (N = 20,313) singleton infants born to East London residents.

MAIN OUTCOME MEASURES

For each ethnic group, we calculated the proportion of very low birthweight (< 1500g) and moderately low birthweight (1500-2499g) infants.

RESULTS

The very low birthweight rate was 2.9% for infants of West Indian descent and 2.2% for infants of African descent vs. 1.3% for European whites; odds ratio (95% confidence interval) = 2.1(1.7-2.8) and 1.8(1.2-3.1), respectively. West Indian and white mothers were similar in terms of age, social support, and prenatal care. African mothers were older and had less social support. The West Indian:white and African:white differentials in very low birthweight rates persisted among low risk mothers; odds ratio (95% confidence interval) = 2.7(1.7-4.0) and 2.3(1.5-3.6), respectively.

CONCLUSIONS

We conclude that black race is a risk factor for very low birthweight in the United Kingdom.

Structure and properties of surfactant protein B

Surfactant protein B is a small homodimeric protein that is found tightly associated with surfactant lipids in the alveolar space. In this review, we discuss the actions of SP-B on phospholipid membranes using information predominantly obtained from model membrane systems. We try to correlate these model actions with current concepts of SP-B structure and proposed biological functions. These functions may include critical roles in the intracellular assembly of surfactant through a role in lamellar body organogenesis, the structural rearrangement of secreted surfactant lipids into tubular myelin, and the subsequent rapid insertion of secreted surfactant phospholipids into the surface film itself. The relevance of SP-B to human biology is emphasized by the fatal respiratory distress that is associated with a genetic deficiency of SP-B and the important role of SP-B in certain exogenous surfactant formulations in wide clinical use.

Video-assisted thoracic surgery: applications and outcome

Thoracoscopy has been revived and expanded by recent improvements in endoscopic technology. The enhanced application and outcome of VATS (video assisted thoracic surgery) was retrospectively studied. Between 1992 and 1995, 82 patients underwent diagnostic thoracoscopy or interventional VATS. Indications included: shortness of breath with nonspecific x-ray abnormality (45%), pulmonary nodule (25%), pleural effusion/empyema (21%), pneumothorax (14%), and hemoptysis, chronic cough or lung consolidation (5%). Sixty-six (83%) of the procedures were completed thoracoscopically. Eight procedures (10%) required addition of a utility mini-thoracotomy and 6 procedures (7%) were converted to formal thoracotomy. Specific diagnostic and/or therapeutic applications of VATS included: inspection; lysis of adhesions; stapling of blebs; biopsy of lung, pleura, or mediastinal structures; drainage and decortication of empyema; mechanical and chemical pleurodesis; wedge resection; and segmental resection. Diagnosis was established and/or treatment completed in 95% of cases. Pathologic diagnoses included: interstitial pneumonitis (22%), cancer (19%), bullous disease (15%), cocci nodule (9%), and other (18%). There were twenty-two complications (28.9%) and four deaths (4.8%). All four deaths were from causes unrelated to the surgery. The most common complications were: residual pneumothorax or hydrothorax (7), failed pleurodesis (3), and prolonged incisional pain (2). The advantage of reduced chest wall and muscle trauma utilizing VATS as opposed to traditional thoracotomy translates to less patient discomfort. The excellent magnified visualization afforded by VATS offers the opportunity to successfully conduct diagnostic and therapeutic interventions in the chest with equal or better visibility. Our findings suggest that the applicability and success of VATS is greatly expanding and its complication rate is less or, at worst, comparable to traditional thoracotomy.