Differential inhibition of trophoblast outgrowth and inner cell mass growth by actinomycin D in cultured mouse embryos.

Treatment of preimplantation mouse embryos in vitro with 10(-3) to 10(-1) mug actinomycin D/ml for 2 hr showed that (i) postimplantation development in vitro was inhibited most when embryos were treated at the morula stage and (ii) after the morula stage actinomycin D inhibited trophoblast outgrowth less than inner cell mass development.     

Studies of murine erythroid cell development. Synthesis of heme and hemoglobin

Techniques of cell separation were used to isolate murine erythroid precursors at different states of maturation. Cells were studied before and after short-term incubation in the presence or absence of erythropoietin. Complementary results were obtained by direct examination of the cell fractions and by the short-term culture experiments. Indices of heme synthesis, including incorporation of 59Fe or [2-14C]glycine into heme and activity of delta-aminolevulinic acid synthetase, were already well developed in the least mature cells, chiefly pronormoblasts. Activity then rose moderately in the cell fractions consisting primarily of basophilic and polychromatophilic normoblasts, and fell off with further increases in cell maturity. On short-term culture in the presence of erythropoietin, activity declined with increasing cell maturation except in the least mature fraction where the original level of activity was maintained. By contrast, synthesis of labeled hemoglobin ([3H]leucine) was very low in the least mature cell fractions and rose progressively with increasing cell maturity. The rate of hemoglobin synthesis increase in cells at all stages of maturation when cultured in the presence of erythropoietin. Despite the different patterns observed for heme synthesis and hemoglobin synthesis, both synthetic activities were consistently higher in cells cultured with erythropoietin as compared to controls. These findings suggest that erythropoietin stimulates biochemical differentiation of erythroid precursors at various stages of maturation. They also demonstrate an asynchronism between heme synthesis and hemoglobin syhthesis; heme synthesis is already well developed in the least mature erythroid cells and begins to diminish as the capacity for hemoglobin synthesis continues to rise.     

The effect of CPTA analogs and other nitrogenous compounds on the biosynthesis of carotenoids in Phycomyces blakesleeanus mutants

The inhibitory effect of a series of analogs of CPTA, 2-(4-chlorophenylthio)-triethylamine-HCl, and ammonia derivatives on carotenoid biosynthesis in Phycomyces blakesleeanus mutants was studied. The types of inhibition exhibited allowed no firm conclusions about the biosynthetic route to β-carotene from either β-zeacarotene or lycopene. However, the evidence suggests at present that both pathways are operative. It was found that a slight change in structure of inhibitor resulted in a different type of action. Conclusions based on a single inhibitor could be cited as “evidence” for a certain pathway.     

An abnormality of oestrogen feedback in amenorrhoea-galactorrhoea.

Fourteen patients with amenorrhoea and hyperprolactin-anemia but no evidence of pituitary tumours were each given an intramuscular injection of 1 mg oestradiol benzoate. Thirteen patients failed to release luteinizing hormone in response to the oestrogen. This hypothalamic abnormality may help to explain the menstrual disturbances in subjects with hyperprolactinaemia.     

Five-in-One: Simultaneous isolation of multiple major liver cell types from livers of normal and NASH mice

NASH is a chronic liver disease that affects 3%–6% of individuals and requires urgent therapeutic developments. Isolating the key cell types in the liver is a necessary step towards understanding their function and roles in disease pathogenesis. However, traditional isolation methods through gradient centrifugation can only collect one or a few cell types simultaneously and pose technical difficulties when applied to NASH livers. Taking advantage of identified cell surface markers from liver single-cell RNAseq, here we established the combination of gradient centrifugation and antibody-based cell sorting techniques to isolate five key liver cell types (hepatocytes, endothelial cells, stellate cells, macrophages and other immune cells) from a single mouse liver. This method yielded high purity of each cell type from healthy and NASH livers. Our five-in-one protocol simultaneously isolates key liver cell types with high purity under normal and NASH conditions, enabling for systematic and accurate exploratory experiments such as RNA sequencing.     

Variation in Specificity of HIV Rapid Diagnostic Tests over Place and Time: An Analysis of Discordancy Data Using a Bayesian Approach

Background

Recent trends to earlier access to anti-retroviral treatment underline the importance of accurate HIV diagnosis. The WHO HIV testing strategy recommends the use of two or three rapid diagnostic tests (RDTs) combined in an algorithm and assume a population is serologically stable over time. Yet RDTs are prone to cross reactivity which can lead to false positive or discordant results. This paper uses discordancy data from Médecins Sans Frontières (MSF) programmes to test the hypothesis that the specificity of RDTs change over place and time.

Methods

Data was drawn from all MSF test centres in 2007-8 using a parallel testing algorithm. A Bayesian approach was used to derive estimates of disease prevalence, and of test sensitivity and specificity using the software WinBUGS. A comparison of models with different levels of complexity was performed to assess the evidence for changes in test characteristics by location and over time.

Results

106, 035 individuals were included from 51 centres in 10 countries using 7 different RDTs. Discordancy patterns were found to vary by location and time. Model fit statistics confirmed this, with improved fit to the data when test specificity and sensitivity were allowed to vary by centre and over time. Two examples show evidence of variation in specificity between different testing locations within a single country. Finally, within a single test centre, variation in specificity was seen over time with one test becoming more specific and the other less specific.

Conclusion

This analysis demonstrates the variable specificity of multiple HIV RDTs over geographic location and time. This variability suggests that cross reactivity is occurring and indicates a higher than previously appreciated risk of false positive HIV results using the current WHO testing guidelines. Given the significant consequences of false HIV diagnosis, we suggest that current testing and evaluation strategies be reviewed.