Some observations of the structure of the choroid plexus and its cysts

The structure of the choroid plexus was studied in five normal human embryos, three normal fetuses and three fetuses with choroid plexus cysts. These were detected by ultrasound and the fetuses were karyotypically normal. The choroid plexus appears in the lateral cerebral ventricles at the seventh developmental week. The early structure is lobulated with vessels running in the mesenchymal stroma and forming capillary nets under the single-layered ependymal epithelium. This embryonal structure is converted into the fetal type during the ninth developmental week as the embryonal capillary net is replaced by elongated loops of wavy capillaries that lie under regular longitudinal epithelial folds. The choroid plexus cysts exhibited accumulation of fluid within distended mesenchymal stroma and did not show the wavy folds on this surface, which was smooth. Within this connective tissue of the cyst wall were distended angiomatous interconnecting thin-walled capillaries. Therefore, filled cavities were not lined by any epithelium. We suggest that fetal choroid plexuses cysts (at least in many cases) are in fact pseudocysts exhibiting angiomatous patterns of capillaries in their walls. Copyright © 2002 John Wiley & Sons, Ltd.     

Molecular taxonomy of vestimentiferans of the western Pacific and their phylogenetic relationship to species of the eastern Pacific

The nucleotide sequence of part (624 bp) of a mitochondrial gene for cytochrome oxidase I was determined for 46 escarpiid vestimentiferans collected from seven sites in the western Pacific and 49 individual specimens of Arcovestia ivanovi from two sites in the Manus Basin. Phylogenetic analysis, based on the newly obtained and previously reported sequences, indicated that escarpiids in the western Pacific can be divided into two tentative species, as we proposed in a previous report. While members of the first tentative species have been collected exclusively from a seep area at a depth of 300 m off the coast of central Japan, the members of the second species inhabit some sites at depths greater than 1,100 m, namely, seep areas in Japanese and Papua-New Guinean waters as well as hydrothermal vent fields in the Okinawa Trough and the Manus Basin. We detected no genetic structure among populations of the second tentative species. The first tentative species was more closely related to a species in the eastern Pacific, Escarpia spicata, and to a species in the Gulf of Mexico, Escarpia laminata, than to the second tentative species in the western Pacific. Sequences obtained from all arcovestiids were identical with the exception of those from three individuals, each of which included a single synonymous nucleotide substitution relative to the dominant haplotype, and no genetic differences were detected between specimens from the two sites in the Manus Basin.     

The role of new technologies in reducing energy demand

Energy efficiency is often stated to be the most cost-effective measure for satisfying our energy demand with minimal environmental damage. However, the potential energy savings attainable in 'the real world' are frequently overestimated, as is shown in an industrial case study of the glass industry. Nevertheless, there are significant energy savings to be realized, and the role of new technologies in this is important. However, the key to the effective use of new technology for improved energy efficiency is good management and. for best effect, it must be integrated into the normal resource management activities of a company.     

Taking Sustainable Cities Seriously: a comparative analysis of twenty-four US cities

After briefly reviewing some conceptual underpinnings of sustainable cities, this paper analyses and compares sustainable cities initiatives in 24 US cities. The central question addressed in the paper is why some cities seem to take sustainability more seriously than others. Numerous demographic, socioeconomic and other characteristics of the cities are correlated with an Index of Taking Sustainability Seriously, which is a composite of some 34 different variables indicating whether each city engages in specific sustainability programmes, policies or activities. Many of the standard explanations, such as the income and wealth of the community, the liberalness of the city and the growth pressures placed on the city, are found to exhibit no correlation with the seriousness of the sustainability effort. What do correlate with the Index are: reliance on manufacturing, where having more residents employed in manufacturing industries is associated with less seriousness; and, the age of the population, where cities with older populations take sustainability more seriously. This has three implications for the future development of sustainable cities. First, some of the cities that might be said to need sustainability programmes the most--cities with heavy manufacturing that are more prone to pollution production--are the least likely to take such programmes seriously. Secondly, as cities' manufacturing bases decline, they should find it increasingly feasible to engage in sustainability initiatives. And, thirdly, as the populations of cities age, policy-makers should also find it easier to support, develop and take seriously sustainability programmes.     

Biological monitoring of particulate pollutants during exploration work at a niobium mineralization in Greenland

The purpose of this investigation was to monitor airborne dipersion of particulates in connection with exploration activities at a niobium-mineralization in the Sarfartoq area, SW Greenland, during the summer of 1989, and to provide a basis for monitoring strategies in later phases of the development of the mining site. During three periods moss bags were exposed at 9 stations close to the outcrop and at 3 background stations, and indigenous lichens and mosses were sampled before and after the exploration work.Analyses of element concentrations showed that the natural enrichment of elements in the indigenous vegetation is restricted to areas immediately at or on the outcrop. The elements found in elevated concentrations were Nb, La, Ce, Th and U.The moss bags and the indigenous monitor organisms showed rises in concentrations of the elements Nb, Ce, Cd, Pb and Zn after the exploration activities during the summer. This shows that some dispersion of dust has occurred in the area.     

Role of vitamin A in the haematotoxicity of hexachlorocyclohexane (HCH) in the rat.

The haematotoxicity of technical hexachlorocyclohexane (HCH) (1000 ppm) was investigated in male albino rats fed with diet free of vitamin A or containing vitamin A at 2000 or 10(5) I.U./kg. Assessment of HCH-induced haematotoxicity at the end of the 7 weeks feeding period was done on the basis of haemoglobin content, total count of red blood cells and white blood cells and the differential counts of the white blood cells as well as by parameters such as packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin content, prothrombin time and clotting time. In the rats fed with vitamin A-free diet containing HCH, significant reductions were noticed in the total white blood cells count, clotting time and prothrombin time indicating severe haematotoxicity. Differential count of the white blood cells of these rats revealed a non-significant reduction in the lymphocyte count. The only indication of haematotoxicity caused by hexachlorocyclohexane in the vitamin A supplemented rats was a slight but statistically significant reduction of the total count of white blood cells. These results demonstrate that the haematotoxicity of hexachlorocyclohexane in the rats is enhanced by vitamin A-deficiency and its supplementation particularly in excess but not at hypervitaminotic level is protective against the toxicity.