Epidemiological analysis of the first 1000 cases of SARS-CoV-2 lineage BA.1 (B.1.1.529, Omicron) compared with co-circulating Delta in Wales, UK.

BACKGROUND: The Omicron (lineage B.1.1.529) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wales, UK, on 3 December 2021. The aim of the study was to describe the first 1000 cases of the Omicron variant by demographic, vaccination status, travel and severe outcome status and compare this to contemporaneous cases of the Delta variant. METHODS: Testing, typing and contact tracing data were collected by Public Health Wales and analysis undertaken by the Communicable Disease Surveillance Centre (CDSC). Risk ratios for demographic factors and symptoms were calculated comparing Omicron cases to Delta cases identified over the same time period. RESULTS: By 14 December 2021, 1000 cases of the Omicron variant had been identified in Wales. Of the first 1000, just 3% of cases had a prior history of travel revealing rapid community transmission. A higher proportion of Omicron cases were identified in individuals aged 20-39, and most cases were double vaccinated (65.9%) or boosted (15.7%). Age-adjusted analysis also revealed that Omicron cases were less likely to be hospitalised (0.4%) or report symptoms (60.8%). Specifically a significant reduction was observed in the proportion of Omicron cases reporting anosmia (8.9%). CONCLUSION: Key findings include a lower risk of anosmia and a reduced risk of hospitalisation in the first 1000 Omicron cases compared with co-circulating Delta cases. We also identify that existing measures for travel restrictions to control importations of new variants identified outside the United Kingdom did not prevent the rapid ingress of Omicron within Wales.

A retrospective validation of the FocalPoint GS slide profiler NFR technology by analysis of interval disease outcomes compared with manual cytology.

BACKGROUND: To the authors' knowledge, published studies reporting on the performance of the FocalPoint GS (FPGS) imaging system have yielded conflicting results to date. However, the results of the MAVARIC study indicated that the FPGS "No Further Review" (NFR) aspect of the technology demonstrated potential and warranted further investigation. The current validation study was performed prior to implementing the NFR slide reporting technology within the routine cervical screening program in Wales, United Kingdom. METHODS: A total of 45,317 SurePath liquid-based cytology cervical screening samples were submitted for FPGS scanning by 4 Welsh laboratories between 2006 and 2011. The current study (Computer Assisted Evaluation, Screening and Reporting [CAESAR]), reports on a comparison between slides categorized as NFR (8130 slides) and slides manually screened as negative (93,473 slides). Both interventions had a subsequent negative quality control screen. RESULTS: The histological outcome rates of cervical intraepithelial neoplasia 2 (CIN-2) (high-grade squamous intraepithelial lesion or worse [HSIL+]) at 2 years and subsequently 3 years after an FPGS NFR result versus a manually screened negative result were compared. Significantly fewer cases were detected in the NFR cohort compared with the manually screened cohort (P = .043 at 2 years and P = .027 at 3 years). When these cases were subcategorized as cancers and precancers, the interval cancer prevalence between NFR and manually screened samples at 2 years and 3 years was similar; however, the interval precancer prevalence for FPGS NFR was significantly lower (P = .023 at 2 years and P = .026 at 3 years) at approximately one-half that of manual screening. CONCLUSIONS: The negative predictive potential of the FPGS NFR technology is higher than that of manual screening, and the technology has quality/throughput benefits to support and enhance a laboratory cervical screening service.

Growth and differentiation of progenitor/stem cells derived from the human mammary gland.

Estrogen is necessary for the full development of the mammary gland and it is also involved in breast cancer development. We set out to identify and characterise progenitor/stem cells in the human mammary gland and to explore the role of estrogen in their proliferation and differentiation. Three candidate stem cell populations were isolated: double positive (DP) cells co-expressed the luminal and myoepithelial markers, EMA and CALLA, respectively, whereas double negative (DN) cells did not express these cell surface markers; side population (SP) cells were characterised by their differential ability to efflux the dye Hoechst 33342. The ABC transporter, breast cancer resistance protein (BCRP) was more highly expressed in SP cells than in non-SP cells and a specific BCRP inhibitor, Ko143, reduced SP formation, suggesting that BCRP confers the SP phenotype in mammary epithelial cells, as has been demonstrated in other tissues. Interestingly, SP cells were double negative for the EMA and CALLA antigens and therefore represent a separate and distinct population to DP cells. Single cell multiplex RT-PCR indicated that the SP and DN cells do not express detectable levels of ERalpha or ERbeta, suggesting that estrogen is not involved in their proliferation. DP cells expressed ERalpha but at a lower level than differentiated luminal cells. These findings invoke a potential strategy for the breast stem/progenitor cells to ignore the mitogenic effects of estrogen. All three cell populations generated mixed colonies containing both luminal and myoepithelial cells from a single cell and therefore represent candidate multipotent stem cells. However, DN cells predominately generated luminal colonies and exhibited a much higher cloning efficiency than differentiated luminal cells. Further characterisation of these candidate progenitor/stem cells should contribute to a better understanding of normal mammary gland development and breast tumorigenesis.

Functional and molecular characterisation of mammary side population cells.

BACKGROUND: Breast cancer is thought to arise in mammary epithelial stem cells. However, the identity of these stem cells is unknown. METHODS: Studies in the haematopoetic and muscle systems show that stem cells have the ability to efflux the dye Hoechst 33342. Cells with this phenotype are referred to as the side population (SP). We have adapted the techniques from the haematopoetic and muscle systems to look for a mammary epithelial SP. RESULTS: Of mammary epithelial cells isolated from both the human and mouse mammary epithelia, 0.2-0.45% formed a distinct SP. The SP was relatively undifferentiated but grew as typical differentiated epithelial clones when cultured. Transplantation of murine SP cells at limiting dilution into cleared mammary fat pads generated epithelial ductal and lobuloalveolar structures. CONCLUSION: These data demonstrate the existence of an undifferentiated SP in human and murine mammary epithelium. Purified SP cells are a live single-cell population that retain the ability to differentiate in vitro and in vivo. Studies of haematopoetic cells have suggested that the SP phenotype constitutes a universal stem cell marker. This work therefore has implications for mammary stem cell biology.