Photoemission electron microscopy for connectomics

Detailing the physical basis of neural circuits with large-volume serial electron microscopy (EM), 'connectomics', has emerged as an invaluable tool in the neuroscience armamentarium. However, imaging synaptic resolution connectomes is currently limited to either transmission electron microscopy (TEM) or scanning electron microscopy (SEM). Here, we describe a third way, using photoemission electron microscopy (PEEM) which illuminates ultra-thin brain slices collected on solid substrates with UV light and images the photoelectron emission pattern with a wide-field electron microscope. PEEM works with existing sample preparations for EM and routinely provides sufficient resolution and contrast to reveal myelinated axons, somata, dendrites, and sub-cellular organelles. Under optimized conditions, PEEM provides synaptic resolution; and simulation and experiments show that PEEM can be transformatively fast, at Gigahertz pixel rates. We conclude that PEEM imaging leverages attractive aspects of SEM and TEM, namely reliable sample collection on robust substrates combined with fast wide-field imaging, and could enable faster data acquisition for next-generation circuit mapping.

Back illuminated photo emission electron microscopy (BIPEEM)

A new, complementary technique based on Photo Emission Electron Microscopy (PEEM) is demonstrated. In contrast to PEEM, the sample is placed on a transparent substrate and is illuminated from the back side while electrons are collected from the other (front) side. In this paper, the working principle of this technique, coined back-illuminated PEEM (BIPEEM), is described. In BIPEEM, the electron intensity is strongly thickness-dependent. This dependence can be described by a simple model which contains the optical attenuation length and the electron mean free path. Electrons forming an image in BIPEEM hence carry information of the inner part of the sample, as well as of the surface, as we demonstrate experimentally.

Milk production after preterm, late preterm and term delivery; effects of different breast pump suction patterns

OBJECTIVE

This study aimed to compare the effectiveness of two different breast pump suction patterns (BPSP) during the initiation of lactation in mothers of term, late preterm and preterm infants.

METHODS

Breast pump-dependent mothers (n=130) of term (n=19), late preterm (n=44) and preterm (n=67) infants were assigned to either a standard or irregular-BPSP after birth until the onset of secretory activation. Both groups used the same standard maintenance BPSP thereafter. Time to secretory activation, time to full milk production and daily milk output were compared between the standard and I-BPSP groups, and between the term, late preterm and preterm groups.

RESULTS

Mothers using the irregular-BPSP demonstrated significantly greater daily milk output and established secretory activation significantly earlier. This effect was observed in mothers of term, late preterm and preterm infants.

CONCLUSION

The irregular-BPSP mimicking sucking of healthy newborns is more effective at achieving secretory activation and an earlier adequate milk supply than the standard-BPSP. The irregular-BPSP can be used successfully for mothers of preterm up to term infants who are breast pump dependent during the establishment of lactation.