Neurogenesis and development of callosal and intracortical connections in the hamster

The developmental time-course of callosal and ipsilateral corticocortical projections was studied in embryonic and postnatal hamsters, from the time of neurogenesis until the appearance of adult patterns. Callosal neurogenesis was determined by combining the incorporation of [3H]thymidine injected on specific embryonic days with retrograde labelling of callosal neurons in the adult animal. The development of both callosal and corticocortical projections was studied by the transport of wheat germ agglutinin conjugated to horseradish peroxidase. Despite a significant radial disperson of postmigratory neurons born on the same day, it was found that the birthdates of callosally-projecting neurons in the frontal cortex were not restricted to a short period of time, but extended between embryonic days 13 and 15. This period covers the neurogenesis of cells in cortical layers III-V. Elongation of callosal axons (and possibly also of corticocortical fibres) started a couple of days before birth in the frontal cortex, and continued through the first postnatal days. After a "waiting period" of a few days, axons from both sets of projections were seen innervating restricted target sectors of the cortex. The zones of origin of these projections were initially exuberant, but were subsequently trimmed to overlap completely with the corresponding terminal fields. It is concluded that callosal and ipsilateral corticocortical projections undergo similar sequences of ontogenetic stages, suggesting that the development of neocortical connectivity as a whole may be governed by one and the same set of rules.     

Evaluation of oxygen saturation monitoring by pulse oximetry in neonates in the delivery system

The pulse oximeter was evaluated for use in neonates in the delivery room. One hundred neonates, delivered vaginally or by Caesarean section with general or epidural anaesthesia, were studied. After delivery, pulse oximetry probes were placed simultaneously on the ulnar side of the right hand and on the right Achilles tendon to determine whether there was a difference in arterial oxygenation (SpO2). Measurements of SpO2 were taken at 1, 5, 10 min, and 24 hr after delivery. At one and five minutes, SpO2 recorded from the right hand was higher than that recorded from the lower extremities (71.9% +/- 6.5% vs 63.4% +/- 4.3% and 83.3% +/- 4.2% vs 76% +/- 4.1%, mean +/- SD, respectively). At ten minutes these differences diminished, and had almost completely disappeared after 24 hr. These results can be explained by the presence of R-L shunting at the ductus arteriosus level, producing reduced SaO2 in the lower extremities. Oxygen saturation did not differ between neonates delivered vaginally or by Caesarean section, regardless of the presence or type of anaesthesia. We concluded that neonates remain relatively desaturated in the immediate postpartum period and that the SpO2 obtained from the right hand is a better index of neonatal oxygenation than that obtained from the heel.     

Early postnatal expression of L1 by retinal fibers in the optic tract and synaptic targets of the Syrian hamster

Previous immunohistochemical studies in mouse, rat, and chick have reported that the expression of the glycoprotein and cell adhesion molecule L1, a member of the immunoglobulin superfamily, shows regulation during development of retina and optic nerve. To extend our understanding of the role of L1 in developing neural circuitry, we have examined L1 expression in the optic tract and thalamic and midbrain synaptic targets of retinal fibers in the early postnatal Syrian hamster, a well-characterized developmental model of the primary visual projection. Metabolic labeling studies reveal that a synaptically targeted, sulfated, and glycosylated form of L1 undergoes rapid axonal transport from the retina. Retinofugal transport of L1 decreases commensurate with the decline in immunoreactivity of retinal fibers in the visual pathway. Retinal ganglion cell axons show intense L1 immunoreactivity as they navigate in highly fasciculated bundles in the optic tract overlying the lateral geniculate body and in the superior colliculus. We found no evidence of L1 immunoreactivity on retinal axon collaterals as they defasciculate from the optic tract and branch into target neuropils. L1 immunoreactivity wanes in optic tract as axon terminal arbors are elaborated in the lateral geniculate body and superior colliculus and as myelination in the visual pathway commences. This pattern of L1 expression suggests that, in the early postnatal period, L1 may support fasciculation of retinal fibers, maintaining them within the optic tract, and that subsequent down-regulation of L1 may facilitate their terminal arborization and myelination.     

A Survey of Practices in the United States Regarding Hepatitis C Screening in Pregnant Women

PurposeHepatitis C virus (HCV) cases have increased in the past decade, with many cases in pregnant patients. However, recommendations for HCV screening during pregnancy vary by professional organization.MethodsPrenatal care providers were surveyed via e-mail about factors affecting choice of HCV screening.FindingsA total of 86 completed surveys were received. Providers using risk-based screening valued guidance from obstetrics and gynecology societies and risk for vertical transmission. Providers using universal screening valued availability of curative treatment in addition to guidance from the Centers for Disease Control and Prevention/infectious diseases societies and obstetrics and gynecology societies.ImplicationsThe results highlight the need for consensus guidelines on HCV screening as a part of prenatal care.     

Live Attenuated Influenza Vaccine: Is Past Performance a Guarantee of Future Results?

Live attenuated influenza vaccine (LAIV) has had a tumultuous recent history that can be difficult for many to follow and understand. Prior to 2013, LAIV had a record of accomplishment of providing equal or superior protection against influenza in children. Since 2013, concerns about the lack of protection with LAIV against pandemic H1N1 strains led to the withdrawal of any recommendation for use in the US by the Advisory Committee on Immunization Practices (ACIP). After some significant changes to the content, evaluation and production of LAIV, it has been be recommended again for use in the US in 2018-19. This commentary reviews the origin of LAIV, the events and circumstances that led to the withdrawal of any recommendation for LAIV use by the ACIP, the merits, shortcomings and repercussions of that decision and finally offers some thoughts about the future of LAIV.     

Unique Challenges of Hepatitis C in Infants,Children, and Adolescents

Purpose

Hepatitis C, a chronic disease with deadly consequences, is no longer predominantly a disease of older people.

The epidemiology of milk allergy in US children

BackgroundMilk is one of the most common food allergies in US children, yet little is known about its distribution and diagnosis.ObjectiveTo better understand current pediatric milk allergy distribution and diagnosis trends in the United States.MethodsA randomized, cross-sectional survey was administered to parents belonging to a representative sample of US households with children from June 2009 to February 2010. Data from 38,480 parents regarding demographic characteristics, allergic symptoms associated with food ingestion, and methods used to diagnose food allergy were collected and analyzed as weighted proportions. Adjusted models were estimated to examine association of these aspects with odds of milk allergy.ResultsOf the 3,218 children identified with food allergy, 657 (19.9%) were reported to have milk allergy. Asian (odds ratio [OR], 0.5) and black (OR, 0.4) children were half as likely as white children to develop milk allergy. The highest percentage of milk-allergic children (23.8%) were aged 6 to 10 years, and the lowest percentage of milk-allergic children (15.0%) were aged 11 to 15 years. Nearly one-third (31.4%) of children with milk allergy had a history of severe reactions. Compared with children with other food allergies, children with milk allergy had a higher odds of having physician-diagnosed allergy (OR, 1.7) and were twice as likely (OR, 2.1) to outgrow their milk allergy.ConclusionChildhood milk allergy, which accounts for one-fifth of US food allergies, is less prevalent among Asian and black children than white children. Although less than half of children with milk allergy received confirmatory testing, it is the most commonly diagnosed food allergy.