Genome-wide mapping of unselected transcripts from extraembryonic tissue of 7.5-day mouse embryos reveals enrichment in the t-complex and under-representation on the X chromosome

Mammalian embryos can only survive if they attach to the uterus (implantation) and establish proper maternal-fetal interactions. To understand this complex implantation pathway, we have initiated genomic analysis with a systematic study of the cohort of genes expressed in extraembryonic cells that are derived from the conceptus and play a major role in this process. A total of 2103 cDNAs from the extraembryonic portion of 7.5-day post-conception mouse embryos yielded 3186 expressed sequence tags, approximately 40% of which were novel to the sequence databases. Furthermore, when 155 of the cDNA clones with no homology to previously detected genes were genetically mapped, apparent clustering of these expressed genes was detected in subregions of chromosomes 2, 7, 9 and 17, with 6.5% of the observed genes localized in the t-complex region of chromosome 17, which represents only approximately 1.5% of the mouse genome. In contrast, X-linked genes were under-represented. Semi-quantitative RT-PCR analyses of the mapped genes demonstrated that one third of the genes were expressed solely in extraembryonic tissue and an additional one third of the genes were expressed predominantly in the extraembryonic tissues. The over-representation of extraembryonic-expressed genes in dosage- sensitive autosomal imprinted regions and under-representation on the dosage-compensated X chromosome may reflect a need for tight quantitative control of expression during development.      

Effect of 2450 MHz microwave energy on the blood-brain barrier to hydrophilic molecules. C. Effect on the permeability to [C]sucrose

Intravenously injected [¹⁴C]sucrose was used as a small molecular weight (342 daltons), hydrophilic tracer for determination of 2450 MHz CW microwave and ambient heat effects on rat blood-brain barrier permeability in the cerebral cortex, hypothalamus, cerebellum and medulla. The tracer was injected 4 min following exposure of conscious, unrestrained rats to microwaves at 0 or 65 mW/cm² for 30 or 90 min (SAR 13.0 W/kg) or to ambient heat (42 ± 2 °C) for 90 min.Comparison of mean permeability-surface area products (PA) and uptake ratios between sham and microwave-exposed animals revealed a statistically significant (P < 0.05) decrease of both PA and uptake ratios for the hypothalamus, cerebellum and medulla of rats exposed to microwaves for 30 min. This decrease was not apparent for rats exposed to microwaves for 90 min. A pertinent observation, with regard to this latter group of animals, was the increased circulating level of the tracer when colonic temperature was raised to approximately 41.4 °C or higher.     

Use of the Phoenix system for bacteriology

A dedicated microbiology data processing system with remote batched job entry to an obsolete computer, has been superseded by the inclusion of bacteriology in an on-line interactive clinical pathology system which had previously incorporated chemical pathology and haematology. The original Phoenix system has been adapted to allow for the entry of bacteriology data using mnemonic codes and to deal with the problems caused by the longer processing time of bacteriology specimens. Particular advantages of the new system include the immediate linkage of all specimens for each patient and an easy recall and display of results in the laboratories and on the wards.     

The ultrasonographic appearance of cystic hepatoblastoma

Cystic hepatoblastomas share ultrasonographic characteristics with simple hepatic cysts; however, a distinction can be made by the demonstration of internal septations. The differentiation is important because cystic hepatoblastoma may have malignant potential. The ultrasonographic and scintigraphic findings in five children with cystic hepatoblastoma are reviewed.