Gabapentin use in the neonatal intensive care unit and beyond: Single center report of 104 cases.

BACKGROUND: We aimed to describe our experience with gabapentin use in infants admitted to our neonatal intensive care unit (NICU), including neurodevelopmental follow-up after discharge. METHODS: We performed a retrospective medical record review of infants prescribed gabapentin during admission to the University of Virginia NICU from 01/01/2015 to 04/30/2021. We report clinical characteristics including gabapentin indication, dosing and side-effects while in the NICU, discharge data, and assessments in outpatient developmental follow-up clinic. RESULTS: Gabapentin was prescribed to 104 infants (median gestational age 29 weeks, median postmenstrual age at initiation 41 weeks). Sixty-one percent of infants were male. The primary indication was irritability in 86%, and 67% were receiving at least one other neurosedative medication. Median maximum dose was 25 mg/kg/day (IQR 15-35 mg/kg/day) and 84% were discharged home on gabapentin. The majority required equipment at discharge (64% gastrostomy or nasogastric tube feeds, 54% supplemental oxygen or mechanical ventilation, and 40% both). At the first neurodevelopmental follow-up appointment, at least one area of delay was identified in 93% of infants and by 2 years corrected age 66% had a diagnosis of global developmental delay. CONCLUSIONS: NICU patients treated with gabapentin often require complex post-discharge care and require close neurodevelopmental follow up.

Screening Echocardiography Identifies Risk Factors for Pulmonary Hypertension at Discharge in Premature Infants with Bronchopulmonary Dysplasia.

HYPOTHESIS: Premature infants with bronchopulmonary dysplasia (BPD) are at increased risk of secondary pulmonary hypertension (BPD-PH). Prior studies yielded mixed results on the utility of echocardiographic screening at 36 weeks post-menstrual age (PMA). We present our experience using echocardiographic screening at the time of BPD diagnosis to identify infants at highest risk of BPD-PH at discharge. MATERIALS AND METHODS: Retrospective cohort analysis of clinical/ demographic data and screening echocardiograms in patients with BPD. Discharge echocardiograms identified infants with or without BPD-PH at discharge. 36 weeks PMA screening echocardiograms and clinical data were then reviewed to identify which factors were associated with increased odds of BPD-PH at discharge. Associations between echocardiographic findings were evaluated with 2- and 3-variable models to predict increased risk of BPD-PH at discharge. RESULTS: In our cohort of 64 infants with severe BPD, BPD-PH was present in 22/64 (34%) infants at discharge. There were no clinical differences at time of 36 weeks PMA screening evaluation (mean PMA 36.6 ± 2.9 weeks). PH at screening was poorly predictive of PH at discharge as PH at screening resolved in 49% of patients. However, having an ASD, RV dilation, hypertrophy, or reduced function on screening, especially in combination, were associated with BPD-PH at discharge. CONCLUSION: In our cohort of premature infants with BPD, 36 weeks PMA screening echocardiogram identified patients at increased risk for BPD-PH at discharge when ASD, RVH, or impaired RV function were present. Larger prospective studies are indicated to validate these findings.

Effect of dexmedetomidine on heart rate in neonates with hypoxic ischemic encephalopathy undergoing therapeutic hypothermia.

BACKGROUND: Sedation is recommended to optimize neuroprotection in neonates with hypoxic ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH). Dexmedetomidine is an alternative agent to opioids, which are commonly used but have adverse effects. Both TH and dexmedetomidine can cause bradycardia. In this study, we describe our experience with dexmedetomidine and fentanyl in neonates undergoing TH for HIE, with a focus on heart rate (HR). METHODS: We performed a retrospective chart review from 2011-2019 at a level IV NICU comparing sedation with dexmedetomidine (n = 14), fentanyl (n = 120), or both (n = 32) during TH for HIE. HR trends were compared based on sedation and gestational age. Neonates were included if they underwent TH and received sedation and were excluded if cooling was initiated past 24hours (h) from birth or if they required ECMO. RESULTS: Of the 166 neonates included, 46 received dexmedetomidine, 14 as monotherapy and 32 in combination with fentanyl. Mean hourly HR from 12-36 h after birth was significantly lower for infants on dexmedetomidine versus fentanyl monotherapy (91±9 vs. 103±11 bpm, p < 0.002). Dexmedetomidine was decreased or discontinued in 22 (47.8%) neonates, most commonly due to inadequate sedation with a low HR. Lower gestational age was associated with higher HR but no significant difference in dexmedetomidine-related HR trends. CONCLUSIONS: Despite an association with lower HR, dexmedetomidine may be successfully used in neonates with HIE undergoing TH. Implementation of a standardized protocol may facilitate dexmedetomidine titration in this population.

Increased excitability and excitatory synaptic transmission during in vitro ischemia in the neonatal mouse hippocampus.

OBJECTIVE: The present study tested the hypothesis that exposure to in vitro hypoxia-ischemia alters membrane properties and excitability as well as excitatory synaptic transmission of CA1 pyramidal neurons in the neonatal mouse. METHODS: Experiments were conducted in hippocampal slices in P7-P9 C57Bl/6 mice using whole-cell patch clamp in current- and voltage-clamp mode. Passive membrane potential (Vm), input resistance (Rin) and active (action potential (AP) threshold and amplitude) membrane properties of CA1 pyramidal neurons were assessed at baseline, during 10 min in vitro ischemia (oxygen-glucose deprivation (OGD)) and during reoxygenation. Spontaneous and miniature excitatory post-synaptic currents (s and mEPSCs) were studied under similar conditions. RESULTS: OGD caused significant depolarization of CA1 pyramidal neurons as well as decrease in AP threshold and increase in AP amplitude. These changes were blocked by the application of tetrodotoxin (TTX), indicating Na(+) channels' involvement. Following 10 min of reoxygenation, significant membrane hyperpolarization was noted and it was associated with a decrease in Rin. AP threshold and amplitude returned to baseline during that stage. sEPSC and mEPSC frequency increased during both OGD and reoxygenation but their amplitude remained unchanged. Additionally, we found that OGD decreases Ih (hyperpolarization activated current) in CA1 neurons from neonatal mice and this effect persists during reoxygenation. SIGNIFICANCE: These results indicate that in vitro ischemia leads to changes in membrane excitability mediated by sodium and potassium channels. Further, it results in enhanced neurotransmitter release from presynaptic terminals. These changes are likely to represent one of the mechanisms of hypoxia/ischemia-mediated seizures in the neonatal period.

Salmonella berta meningitis in a term neonate.

We report the case of a 37-week male infant born via spontaneous vaginal delivery who developed Salmonella berta sepsis and meningitis. The infant was born to a mother with active diarrhea and stool cultures growing S. berta. On day 3, the infant developed poor feeding, lethargy, apnea and bradycardia prompting a sepsis evaluation. Blood, stool and cerebrospinal fluid cultures were positive for S. berta. An electroencephalogram performed for posturing revealed neonatal status epilepticus. Extensive bilateral periventricular venous hemorrhagic infarctions with multiple herniations were seen on brain magnetic resonance imaging. The infant's condition continued to deteriorate despite maximal support and care was redirected towards comfort measures.

Impact of transient acute hypoxia on the developing mouse EEG.

Hypoxemic events are common in sick preterm and term infants and represent the most common cause of seizures in the newborn period. Neonatal seizures often lack clinical correlates and are only recognized by electroencephalogram (EEG). The mechanisms leading from a hypoxic/ischemic insult to acute seizures in neonates remain poorly understood. Further, the effects of hypoxia on EEG at various developmental stages have not been fully characterized in neonatal animals, in part due to technical challenges. We evaluated the impact of hypoxia on neonatal mouse EEG to define periods of increased susceptibility to seizures during postnatal development. Hippocampal and cortical electrodes were implanted stereotaxically in C57BL/6 mice from postnatal age 3 (P3) to P15. Following recovery, EEG recordings were obtained during baseline, acute hypoxia (4% FiO2 for 4min) and reoxygenation. In baseline recordings, maturation of EEG was characterized by the appearance of a more continuous background pattern that replaced alternating high and low amplitude activity. Clinical seizures during hypoxia were observed more frequently in younger animals (100% P3-4, 87.5% P5-6, 93% P7-8, 83% P9-10, 33% P11-12, 17% P15, r(2)=0.81) and also occurred at higher FiO2 in younger animals (11.2±1.1% P3-P6 vs. 8.9±0.8% P7-12, p<0.05). Background attenuation followed the initial hypoxemic seizure; progressive return to baseline during reoxygenation was observed in survivors. Electrographic seizures without clinical manifestations were observed during reoxygenation, again more commonly in younger animals (83% P3-4, 86% P5-6, 75% P7-8, 71% P9-10, 20% P11-12, r(2)=0.82). All P15 animals died with this duration and degree of hypoxia. Post-ictal abnormalities included burst attenuation and post-anoxic myoclonus and were more commonly seen in older animals. In summary, neonatal mice exposed to brief and severe hypoxia followed by rapid reoxygenation reliably develop seizures and the response to hypoxia varies with postnatal age and maturation.

Physiologic and pharmacologic considerations for hypothermia therapy in neonates.

With mounting evidence that hypothermia is neuroprotective in newborns with hypoxic-ischemic encephalopathy (HIE), an increasing number of centers are offering this therapy. Hypothermia is associated with a wide range of physiologic changes affecting every organ system, and awareness of these effects is essential for optimum patient management. Lowering the core temperature also alters pharmacokinetic and pharmacodynamic properties of medications commonly used in asphyxiated neonates, necessitating close attention to drug efficacy and side effects. Rewarming introduces additional risks and challenges as the hypothermia-associated physiologic and pharmacologic changes are reversed. In this review we provide an organ system-based assessment of physiologic changes associated with hypothermia. We also summarize evidence from randomized controlled trials showing lack of serious adverse effects of moderate hypothermia therapy in term and near-term newborns with moderate-to-severe HIE. Finally, we review the effects of hypothermia on drug metabolism and clearance based on studies in animal models and human adults, and limited data from neonates.

Therapeutic hypothermia on neonatal transport: 4-year experience in a single NICU.

OBJECTIVE: Therapeutic hypothermia instituted within 6 h of birth has been shown to improve neurodevelopmental outcomes in term newborns with moderate-to-severe hypoxic-ischemic encephalopathy (HIE). The majority of infants who would benefit from cooling are born at centers that do not offer the therapy, and adding the time for transport will result in delays in therapy, that may lead to suboptimal or no neuroprotection for some patients. Our objective was to evaluate the effect of our center's experience with therapeutic hypothermia on neonatal transport. STUDY DESIGN: Retrospective review of all cases of therapeutic hypothermia at a single neonatal intensive care unit from 2005 to 2009. RESULT: Of 50 infants with HIE treated with hypothermia, 40 were outborn and 35 were cooled on transport. The majority of patients were passively cooled by the referring clinicians, then actively cooled by our transport team. Overcooling to <32 degrees C occurred in 34% of patients, but there were no significant differences in admission vital signs or laboratory values between overcooled and appropriately cooled infants. The average time after birth of initiation of passive cooling was 1.4 h and active cooling was 2.7 h compared with the time of admission to our unit of 5.9 h. CONCLUSION: We discuss the important aspects of our program, including the education of referring and receiving clinicians and avoidance of overcooling.

Implementation of a 'Hypothermia for HIE' program: 2-year experience in a single NICU.

Hypothermia has been shown to be neuroprotective in some newborns with moderate-to-severe perinatal hypoxic-ischemic encephalopathy (HIE). In 2006, the American Academy of Pediatrics recommended that institutions that choose to use therapeutic hypothermia do so in the context of a rigorous protocol, with systematic collection of patient data including neurodevelopmental follow-up. In this report, we describe our experience with implementation of a 'Hypothermia for HIE' program in a single tertiary care Neonatal Intensive Care Unit (NICU). Important components of the program include detailed protocols, staff and outreach education, early initiation of cooling in both inborn and outborn patients, maintaining stable hypothermia during neonatal transport, and comprehensive neurologic evaluation including serial EEGs, brain MRI and neurodevelopmental follow-up. In the first 2 years of the program, we have used hypothermia therapy in 21 patients, 18 with perinatal and 3 with early postnatal events leading to HIE. Eleven of fifteen outborn patients were cooled prior to and during transport, resulting in initiation of therapy 3 h sooner than if therapy had been delayed until arrival at our center. While lowering the body temperature of encephalopathic newborns is not difficult, addressing the complex medical problems of this vulnerable group of patients requires an experienced multidisciplinary team in regional referral centers.

Hypoxia modifies nuclear calcium uptake pathways in the cerebral cortex of the guinea-pig fetus.

Nuclear Ca2+ signals are thought to play a critical role in the initiation and progression of programmed cell death. The present study tests the hypothesis that hypoxia alters nuclear Ca2+ transport pathways and leads to an increase in nuclear Ca(2+)-influx in cerebral cortical neuronal nuclei. To test this hypothesis the effect of tissue hypoxia on high affinity Ca(2+)-ATPase activity and the binding characteristics of inositol 1,4,5-triphosphate (IP3) and inositol 1,3,4,5-tetrakisphosphate (IP4) receptors were studied in neuronal nuclei from the cerebral cortex of guinea-pig fetuses. Results show increased high-affinity Ca(2+)-ATPase activity (nmol/mg protein/h) in the hypoxic group 969.7+/-79 as compared with 602.4+/-90.9 in the normoxic group, P<0.05. The number of IP3 receptors (Bmax, fmol/mg protein) increased from 61+/-21 in the normoxic group to 164+/-49 in the hypoxic group, P<0.05. K(d) values did not change following hypoxia. In contrast, IP4 receptor Bmax (fmol/mg protein) and K(d) (nM) values increased from 360+/-32 in the normoxic group to 626+/-136 in the hypoxic group (P<0.001) and, from 26+/-1 in the normoxic group to 61+/-9 in the hypoxic group (P<0.001), respectively. 45Ca(2+)-influx (pmol/mg protein) significantly increased from 6.3+/-1.9 in the normoxic group to 10.9+/-1.1 the hypoxic group (P<0.001). The data show that hypoxia modifies nuclear Ca2+ transport pathways and results in increased nuclear Ca(2+)-influx. We speculate that hypoxia increases nuclear Ca2+ uptake from the cytoplasm to the nucleoplasm, resulting in increased transcription of proapoptotic genes and subsequent activation of programmed cell death pathways.

Nitration is a mechanism of regulation of the NMDA receptor function during hypoxia.

The present study tested the hypothesis that nitration is a mechanism of hypoxia-induced modification of the N-methyl-D-aspartate (NMDA) receptor. To test this hypothesis the effect of hypoxia on the nitration of the NR1, NR2A and NR2B subunits of the NMDA receptor was determined. Furthermore, the effect of administration of a nitric oxide synthase (NOS) inhibitor, N-nitro-L-arginine (NNLA) on the hypoxia-induced nitration of the NMDA receptor subunits as well as the NMDA receptor-mediated Ca2+ influx, an index of NMDA receptor-ion channel function, were determined in cortical synaptosomes. Studies were performed in newborn piglets divided into normoxic, hypoxic and hypoxic-NNLA groups. Hypoxia was induced by decreasing the FiO(2) to 0.07-0.09 for 60 min. Cerebral tissue hypoxia was confirmed by determining the levels of high energy phosphates ATP and phosphocreatine. Nitration of the NMDA receptor subunits was determined by immunoprecipitation using specific antibodies and western blot analysis. NMDA receptor-ion channel-mediated Ca2+ influx was determined using 45Ca2+. There was a significant increase in the nitrated NR1, NR2A and NR2B subunits following hypoxia: 104+/-11 vs. 275+/-18 optical density (OD)xmm(2) for NR1 (P<0.05), 212+/-36 vs. 421+/-16 ODxmm(2) for NR2A (P<0.05) and 246+/-44 vs. 360+/-26 ODxmm(2) for NR2B (P<0.05). This increase in nitrated NR1, NR2A and NR2B subunits of the NMDA receptor was prevented by the administration of NNLA prior to hypoxia (NR1 160+/-19, P=NS, NNLA vs. normoxic; NR2A 304+/-49, P=NS, NNLA vs. normoxic, and NR2B 274+/-19, P=NS, NNLA vs. normoxic). The increase in nitration of the NR1, NR2A and NR2B subunits of the NMDA receptor increased as a function of decreased cerebral high-energy phosphates, ATP and phosphocreatine, during hypoxia. Furthermore, NOS blockade prior to hypoxia resulted in prevention of the hypoxia-induced increase in NMDA receptor-mediated Ca2+ influx. Our results demonstrate that hypoxia results in increased nitration of the NMDA receptor subunits and that administration of an NOS inhibitor prior to hypoxia prevents the hypoxia-induced nitration of the NMDA receptor subunits as well as the hypoxia-induced increase in NMDA receptor-mediated Ca2+ influx. We conclude that nitration is a mechanism of modification of the NMDA receptor function during hypoxia in the newborn piglet brain.

Phosphorylation of Bcl-2 and Bax proteins during hypoxia in newborn piglets.

Studies indicate that phosphorylated Bcl-2 cannot form a heterodimer with Bax and thus may lose its antiapoptotic potential. The present study tests the hypothesis that graded hypoxia in cerebral tissue induces the phosphorylation of Bcl-2, thus altering the heterodimerization of Bcl-2 with Bax and subsequently leading to apoptosis. Anesthetized, ventilated newborn piglets were assigned to a normoxic and a graded hypoxic group. Cerebral cortical neuronal nuclei were isolated and immunoprecipitated; immune complexes were separated and reacted with Bcl-2 and Bax specific antibodies. The results show an increased level of serine/tyrosine phosphorylated Bcl-2 in nuclear membranes of hypoxic animals. The level of phosphorylated Bcl-2 protein increased linearly with decrease in tissue PCr. The level of phosphorylated Bax in the neuronal nuclear membranes was independent of cerebral tissue PCr. The data shows that during hypoxia, there is increased phosphorylation of Bcl-2, which may prevent its heterodimerization with Bax and lead to increased proapoptotic activity due to excess Bax in the hypoxic brain. Further increased phosphorylation of Bcl-2 may alter the Bcl-2/Bax-dependent antioxidant, lipid peroxidation and pore forming activity, as well as the regulation of intranuclear Ca2+ and caspase activation pathways. We speculate that increased phosphorylation of Bcl-2 in neuronal nuclear membranes is a potential mechanism of programmed cell death activation in the hypoxic brain.

Acute hypoxia-induced alterations of calbindin-D28k immunoreactivity in cerebellar Purkinje cells of the guinea pig fetus at term.

Purkinje cells (PCs) are vulnerable to hypoxic/ischemic insults and rich in calcium and calcium-buffering/sequestering systems, including calcium-binding proteins (CaBPs). Calbindin-D28k is an EF-hand CaBP, which is highly expressed in PCs where it acts primarily as a cellular Ca++ buffer. Elevation of [Ca++] in the cytosol and nuclei of PCs is pivotal in hypoxic/ischemic cell death. We hypothesize that hypoxia results in decreased concentration, or availability of calbindin-D28k in PCs, thereby decreasing their buffering capacity and resulting in increase of intracellular and intranuclear [Ca++]. Cerebellar tissues from normoxic fetuses were compared to fetuses obtained from term pregnant guinea pigs exposed to hypoxia [7% FiO2] for 60 min. The pregnant guinea pigs were either killed upon delivery immediately following hypoxia (Hx0h) or were subsequently allowed to recover for 24 h (Hx24h) or 72 h (Hx72h). Fetal brain hypoxia was documented biochemically by a decrease in brain tissue levels of ATP and phosphocreatine. Compared to normoxic fetuses, there is a predominantly somatodendritic loss or decrease of calbindin-D28k immunohistochemical staining in PCs of Hx0h (p < 0.005), Hx24h (p < 0.05), and Hx72h (p < 0.005) fetuses. Hypoxia-induced alterations of calbindin-D28k immunoreactivity are qualitatively similar at all time points and include a distinctive intranuclear localization in subpopulations of PCs. A similar trend is demonstrated by immunoblotting. Subpopulations of TUNEL+/calbindin-D28k- PCs lacking morphologic features of apoptosis or necrosis are demonstrated in Hx24h and Hx72h fetuses. The present study demonstrates an abrogating effect of perinatal hypoxia on calbindin-D28k immunoreactivity in cerebellar PCs. The perturbation of this Ca++ buffer protein in hypoxia-induced neuronal injury may herald delayed cell death or degeneration.

Effect of graded hypoxia on cerebral cortical genomic DNA fragmentation in newborn piglets.

Previous studies have shown that hypoxia is associated with modification of the cerebral cortical nuclear membrane, leading to increased intranuclear calcium. The increased intranuclear calcium activates calcium-dependent endonucleases, resulting in DNA fragmentation. The present study tests the hypothesis that the fragmentation of neuronal genomic DNA increases with an increase in the degree of cerebral tissue hypoxia. Sixteen newborn piglets were anesthetized, ventilated and divided into normoxic and hypoxic groups with varying degrees of hypoxia. Cerebral hypoxia was documented biochemically by measuring tissue levels of ATP and phosphocreatine. Isolation of cerebral cortical neuronal nuclei and DNA and their purity was confirmed by standard techniques. DNA samples were separated by electrophoresis on 1% agarose gel and stained with ethidium bromide. In the hypoxic samples, multiple low-molecular-weight DNA fragments were present as a smear pattern from 200 to 2,000 base pairs. Levels of high-energy phosphates were compared to the area of each smear for each animal to correlate the degree of hypoxia with the degree of DNA fragmentation. DNA fragmentation increased when high-energy phosphate levels decreased. We conclude that there is a critical threshold value of oxidative metabolism beyond which there are progressive changes in the cortical neuronal cells, leading to DNA fragmentation.

Effect of graded hypoxia on the high-affinity CPP binding site of the NMDA receptor in the cerebral cortex of newborn piglets.

Previous studies have shown that the N-methyl-D-aspartate (NMDA) receptor is modified during hypoxia in the cerebral cortex of newborn piglets. The present study tests the hypothesis that the NMDA receptor 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) high-affinity binding site is modified during hypoxia and that the degree of modification correlates with the progressive decrease in cerebral cellular energy metabolism and increase in lipid peroxidation induced by hypoxia. Studies were conducted in twelve anesthetized, ventilated newborn piglets, five normoxic and seven hypoxic which were exposed to decreased fraction of inspired oxygen (FiO2) to achieve varying phosphocreatine (PCr) levels. 3[H]-CPP binding was performed with CPP concentrations ranging from 0.5 to 1500 nM at 23 degrees C for 40 min in P2 membrane fractions. Brain tissue PCr levels were determined biochemically. Conjugated dienes (CDs) were measured as an index of lipid peroxidation. In the normoxic group, B(max) (receptor number) for the CPP binding site was 329+/-93 fmol/mg protein and Kd (dissociation constant) 137+/-44 nM, the mean PCr value was 2.5+/-0.4 micromol/g brain and the CD level was 0.0 nmol/g brain. As tissue hypoxia worsened, there was a gradual decline in tissue PCr as well as receptor B(max) and K(d) values, and there was an increase in conjugated dienes. Both the receptor B(max) (r=0.90) and Kd (r=0.72) decreased in a linear relationship as PCr decreased. As the levels of CDs increased both the receptor B(max) (r=0.88) and Kd (r=0.68) decreased in a linear fashion. The data show that there is not a critical hypoxic threshold for modification of the CPP binding site of the NMDA receptor, but that modification is coupled to a gradual decrease in brain cell energy metabolism and increase in lipid peroxidation. We speculate that hypoxia-induced modification of the NMDA receptor is mediated not only by changes in the receptor recognition site but also by an alteration of brain cell membrane structure secondary to conjugated diene formation.

Peroxynitrite-induced modification of the N-methyl-D-aspartate receptor in the cerebral cortex of the guinea pig fetus at term.

The present study tests the hypothesis that nitration is a potential mechanism of N-methyl-D-aspartate (NMDA) receptor modification, by assessing the effect of peroxynitrite in vitro on the glutamate and ion-channel sites of the NMDA receptor in the fetal guinea pig. Nitration of NMDA receptor subunits was confirmed by Western blot. Following peroxynitrite exposure, (3)H-MK-801 bindings show an increase in the B(max) and a decrease in the K(d), while (3)H-glutamate bindings show a decrease in the K(d) with no change in the B(max). We conclude that peroxynitrite regulates the NMDA receptor function by increasing the affinity of the ion-channel and glutamate sites, and by exposing additional ion-channel sites. We propose that nitration of the NMDA receptor is a potential mechanism for the regulation of the receptor during hypoxia.

[Bacterial meningitis in infants 1 to 8 weeks old]. / Méningites bactériennes du nourrisson âgé de une à huit semaines.

Bacterial meningitis in the newborn and infant remains a serious problem, with a mortality rate of 24% and a morbidity rate ranging from 30 to 50%. This retrospective study conducted between January 1982 and December 1997, aims to characterize the epidemiology of bacterial meningitis in infants less than 60 days of age. Thirty-five infants between 6 and 60 days of age, hospitalized for bacterial meningitis in the pediatric units of Edouard-Herriot Hospital in Lyon, France, were included. The clinical presentation was not specific for most cases, hyperthermia being the most common symptom (97%). Neurological symptoms such as bulging fontanelle or nuchal rigidity were present in 30% and 8% of the cases, respectively. The four predominant meningeal pathogens were: group B streptococcus (36%), Escherichia coli (28%), meningogoccus (8.6%) and Staphylococcus aureus (8.6%). This study emphasizes the importance of prompt diagnosis, including CSF evaluation, and antimicrobial therapy in infants less than 2 months of age presenting an isolated fever.

Effect of nitric oxide synthase inhibition on high affinity Ca(2+)-ATPase during hypoxia in cerebral cortical neuronal nuclei of newborn piglets.

Previous studies have shown that during hypoxia, neuronal nuclear high affinity Ca(2+)-ATPase activity is increased in the cerebral cortex of newborn piglets. The present study tests the hypothesis that pretreatment with N-nitro-L-arginine (NNLA) will prevent the hypoxia-induced increase in high affinity Ca(2+)-ATPase activity in cortical neuronal nuclear membrane of newborn piglets. We also tested the hypothesis that nitration is a mechanism of elevation of the high affinity Ca(2+)-ATPase activity during hypoxia. Studies were performed in five normoxic, five hypoxic, and six NNLA-pretreated (40 mg/kg) hypoxic newborn piglets. Cerebral cortical neuronal nuclei were isolated and the high affinity Ca(2+)-ATPase activity was determined. Further, normoxic samples were aliquoted into two sub-groups for in vitro nitration with 0.5 mM peroxynitrite and subsequent determination of the high affinity Ca(2+)-ATPase activity. The activity increased from 309+/-40 nmol Pi/mg protein/h in the normoxic group to 520+/-108 nmol Pi/mg protein/h in the hypoxic group (P<0.05). In the NNLA-pretreated group, the activity was 442+/-53 nmol Pi/mg protein/h (P<0.05), which is 25% lower than in the hypoxic group. In the nitrated group the enzyme activity increased to 554+/-59 nmol Pi/mg protein/h (P<0. 05). Thus peroxynitrite-induced nitration in vitro increased the high affinity Ca(2+)-ATPase activity and NNLA administration in vivo partially prevented the hypoxia-induced increase in neuronal nuclear high affinity Ca(2+)-ATPase activity. We conclude that the hypoxia-induced increase in nuclear membrane high affinity Ca(2+)-ATPase activity is NO-mediated and that nitration of the enzyme is a mechanism of its modification.

Hypoxia-induced generation of nitric oxide free radicals in cerebral cortex of newborn guinea pigs.

Previous studies have shown that brain tissue hypoxia results in increased N-methyl-D-aspartate (NMDA) receptor activation and receptor-mediated increase in intracellular calcium which may activate Ca++-dependent nitric oxide synthase (NOS). The present study tested the hypothesis that tissue hypoxia will induce generation of nitric oxide (NO) free radicals in cerebral cortex of newborn guinea pigs. Nitric oxide free radical generation was assayed by electron spin resonance (ESR) spectroscopy. Ten newborn guinea pigs were assigned to either normoxic (FiO2 = 21%, n = 5) or hypoxic (FiO2 = 7%, n = 5) groups. Prior to exposure, animals were injected subcutaneously with the spin trapping agents diethyldithiocarbamate (DETC, 400 mg/kg), FeSO4.7H2O (40 mg/kg) and sodium citrate (200mg/kg). Pretreated animals were exposed to either 21% or 7% oxygen for 60 min. Cortical tissue was obtained, homogenized and the spin adducts extracted. The difference of spectra between 2.047 and 2.027 gauss represents production of NO free radical. In hypoxic animals, there was a difference (16.75+/-1.70 mm/g dry brain tissue) between the spectra of NO spin adducts identifying a significant increase in NO free radical production. In the normoxic animals, however, there was no difference between the two spectra. We conclude that hypoxia results in Ca2+-dependent NOS mediated increase in NO free radical production in the cerebral cortex of newborn guinea pigs. Since NO free radicals produce peroxynitrite in presence of superoxide radicals that are abundant in the hypoxic tissue, we speculate that hypoxia-induced generation of NO free radical will lead to nitration of a number of cerebral proteins including the NMDA receptor, a potential mechanism of hypoxia-induced modification of the NMDA receptor resulting in neuronal injury.