Rapid whole blood lactate measurement in the fetus and mother during labour

Lactic acidemia in human immunodeficiency virus-uninfected infants exposed to perinatal antiretroviral therapy

OBJECTIVE

To investigate potential mitochondrial toxicity in HIV-uninfected infants exposed to highly active antiretroviral therapy (HAART) in utero and/or neonatal zidovudine.

DESIGN

A prospective observational study performed in a tertiary referral center for HIV-infected women and their infants and children.

METHODS

Plasma lactate was measured repeatedly during the first 6 months of life in a consecutive cohort of infants exposed to HAART in utero and/or neonatal zidovudine. Maternal CD4, HIV RNA concentration, antiretroviral and substance use histories, mode of delivery, infant gender, cord pH, Apgar score and birth weight were collected.

RESULTS

The plasma lactate was above normal on at least 1 occasion in 35 of 38 (92%) infants and reached levels > or =5 mmol/l in 10 (26%) infants. Overall 78 of 117 (68%) lactate measurements were elevated, with 11 (10%) in the serious (> or =5 mmol/l) range. None of the infants received antiretrovirals beyond 6 weeks, yet elevated lactates persisted up to age 6 months. Two infants had reversible symptoms consistent with those of lactic acidemia. No association was found between the infant peak lactate and the type of therapy during pregnancy, its duration or maternal substance use.

CONCLUSION

Transient lactic acidemia was observed in the majority of HIV uninfected infants exposed to HAART in utero and/or zidovudine neonatally. We hypothesize that the hyperlactatemia is a consequence of persistent, primarily subclinical, mitochondrial toxicity from the transplacental and neonatal exposure to antiretrovirals and of impaired hepatic lactate clearance. Although the clinical relevance of our findings is unknown, we recommend lactate monitoring in these infants, considering discontinuation of neonatal zidovudine in symptomatic infants with lactate > or =5 mmol/l and careful long term follow up of these children.

Critical role for glial cells in the propagation and spread of lymphocytic choriomeningitis virus in the developing rat brain

Inoculation of the neonatal rat with lymphocytic choriomeningitis virus (LCMV) results in the selective infection of several neuronal populations and in focal pathological changes. However, the pathway by which LCMV reaches the susceptible neurons has not been described, and the nature and time course of the pathological changes induced by the infection are largely unknown. This study examined the sequential migration of LCMV in the developing rat brain and compared the pathological changes among infected brain regions. The results demonstrate that astrocytes and Bergmann glia cells are the first cells of the brain parenchyma infected with LCMV and that the virus spreads across the brain principally via contiguous glial cells. The virus then spreads from glial cells into neurons. However, not all neurons are susceptible to infection. LCMV infects neurons in only four specific brain regions: the cerebellum, olfactory bulb, dentate gyrus, and periventricular region. The virus is then cleared from glial cells but persists in neurons. LCMV induces markedly different pathological changes in each of the four infected regions. The cerebellum undergoes an acute and permanent destruction, while the olfactory bulb is acutely hypoplastic but recovers fully with age. Neurons of the dentate gyrus are unaffected in the acute phase but undergo a delayed-onset mortality. In contrast, the periventricular region has neither acute nor late-onset cell loss. Thus, LCMV infects four specific brain regions in the developing brain by spreading from glial cells to neurons and then induces substantially different pathological changes with diverse time courses in each of the four infected regions.

Fetal scalp blood lactate as an indicator of intrapartum hypoxia

Fetal scalp blood lactate was measured during labour by a simple, rapid method and its value as an indicator of fetal intrauterine hypoxia was assessed and compared with that of pH measurement. The normal ranges of lactate concentration and of pH values were calculated. Significantly higher concentrations of lactate and lower pH values were found in samples of scalp blood taken close to delivery from babies with Apgar scores of less than or equal to 6 at 1 min compared with those from healthy babies with Apgar scores of greater than or equal to 7 at 1 min. A similarly significant difference was observed between the cord blood lactate and pH values of these two groups of babies. Ominous fetal heart rate patterns were associated with higher lactate concentrations and lower pH values in fetal scalp blood than were normal fetal heart rate patterns. The measurement of fetal scalp blood lactate or pH, or continuous electronic fetal heart rate monitoring were equally good at predicting the condition of the infant at birth.