National population prevalence of antibodies to SARS-CoV-2 among pregnant women in Scotland during the second wave of the COVID-19 pandemic: a prospective national serosurvey.

OBJECTIVES: This study aimed to determine SARS-CoV-2 seroprevalence among pregnant women in the Scottish population during the second wave of the COVID-19 pandemic. STUDY DESIGN: Prospective national serosurvey. METHODS: We tested 13,428 residual samples retrieved from pregnant women participating in the first trimester combined ultrasound and biochemical screening for fetal trisomy across Scotland for SARS-CoV-2 antibodies over a 6-month period from November 2020 to April 2021. Seroprevalence estimates were adjusted for the sensitivity and specificity of the assays and weighted to reference populations. RESULTS: Seroprevalence rates in the antenatal samples significantly increased from 5.5% (95% confidence interval [CI] 4.7%-6.5%) in the 5-week period up to and including International Organization for Standardization (ISO) Week 51 (w/b Monday 14 December 2020) to 11.3% (95% CI 10.1%-12.6%) in the 5-week period up to and including ISO Week 14 (w/b Monday 5 April 2021). Increasing seroprevalence trends across the second wave were observed among all age groups. CONCLUSIONS: By the end of the second wave of the COVID-19 pandemic, approximately one in 10 women tested around the end of the first trimester of pregnancy had antibodies to SARS-CoV-2, suggesting that the vast majority were still susceptible to COVID-19 as they progressed to the later stages of pregnancy, when risks from infection are elevated for both mother and baby.

Gap junctions revealed by freeze-fracture electron microscopy.

Gap junctions provide the basis for the formation of elaborate networks of communication between cells in animal tissues. Electron microscopic examination of thin sections of plastic embedded gap junctions has provided valuable information on the anatomy and function of these remarkable structures. Freeze-fracture electron microscopy, however, has made available unique vistas of gap junction-bearing intramembrane surface--surface previously inaccessible to the researcher's eyes. Data on population density, distribution, size, geometry of intramembrane particle packing, and structural responses of gap junction components to experimental manipulation are simply and easily obtained with freeze fracture. Recent developments of sophisticated protocols of immunocytochemistry as applied to freeze-fracture replicas further serve to reinforce the notion that freeze-fracture is a powerful tool for study of gap junctions. Molecular techniques of gap junction gene transfection promise to add a truly unique dimension to investigations of the broad spectrum of functional roles of gap junctions.

Crustecdysone-induced modulation of electrical coupling and gap junction structure in crayfish hepatopancreatocytes.

Crustecdysone, the hormone responsible for onset and regulation of the molt cycle in Crustacea, causes an increase in ionic coupling of cells of the hepatopancreas concomitant with the events of the molt. Hepatopancreatic tissue incubated for up to 4 hr in modified Eagle Basal Medium containing crustecdysone, exhibited an approximate 29% decrease in intercellular resistance as compared with tissue incubated in control medium. This represents a 29% increase in ionic coupling between hepatopancreatocytes following treatment with crustecdysone. Examination of platinum replicas of freeze-fractured, crustecdysone-treated hepatocyte plasma membrane revealed that most of the gap junction plaques were round with tightly packed intramembrane particles; a condition indicative of highly coupled cells. Similar preparations of control plasmalemmae demonstrated many gap junction plaques which were round or irregular in shape with very loosely packed particles and were indicative of uncoupled junctions. Results of this study are identical to those from a previous investigation of the electrophysiology and freeze-fracture morphology of hepatopancreatocytes during the molt cycle (McVicar and Shivers, 1984), and are thus presumed to reflect a crustecdysone-controlled increase in cell communications in vivo.