Circulatory shock in pregnant sheep. I. Effects of endotoxin on uteroplacental and fetal umbilical circulation

The response of the uteroplacental and fetal circulations and oxygen transfer to injection of E. coli endotoxin into the pregnant sheep was investigated. Endotoxin injection into the mother was comprised of three distinct phases: First came a precipitous fall in arterial pressure and uteroplacental blood flow with an increase in uteroplacental vascular resistance. This phase was followed by a progressive recovery period during which flow, pressure, and resistance returned to control values. A third phase occurred during which arterial pressure and uteroplacental blood flow decreased until death of the animal. Despite the marked changes in uteroplacental hemodynamics and a decrease in uteroplacental oxygen transfer, the fetal circulation did not show any major alteration until the terminal phase of shock, when arterial pressure and umbilical flow decreased. There was a fall in fetal oxygen content difference.     

Studies of Bioaccumulation and Biotransformation of PCBs in Mustelids Based on Concentration and Congener Patterns in Predators and Preys

Bioaccumulation of non-, mono-, and di-ortho–substituted chlorobiphenyls (CBs) was investigated in four species of mustelids (weasel, stoat, polecat, and otter) and their preys, from a restricted area in the northern part of The Netherlands. Diets of these mustelids ranged from terrestrial (weasel, stoat, and polecat) to aquatic (otter). Diet-specific biomagnification factors (BMFs), CB in diet relative to CB in mustelids, were calculated for the sum of 28 congeners (ΣCB), for the sum of the toxic equivalent concentration (ΣTEQ) and on an individual congener basis. Biotransformation was studied in relation to structural CB properties (vicinal H-atom substitution). In addition, the methylsulphonyl CB-metabolites were determined. The concentration of ΣCB on lipid weight basis increased in the order weasel < stoat < polecat < otter. On the basis of ΣTEQ, the order changed to weasel < polecat < stoat < otter. Most of the differences in BMFs between the CBs could be explained by the vicinal H-atom structure-activity rules. For all mustelids, the lowest BMFs were found for congeners with vicinal H-atoms in the meta, para position. Indications were found that all mustelid species can metabolize these congeners. For some of the CBs, their methylsulphonyl-CB metabolites were determined and found to be present in concentrations up to 350-fold higher than those of the parent compounds. In addition, the non-ortho CBs 126 and 169 are selectively retained in the liver of weasel, stoat, and otter. These CBs had the highest BMFs of all congeners. However, rather surprisingly, in polecat the highest BMFs were found for di-ortho–substituted CBs. This animal was able to metabolize all congeners with vicinal H-atoms in the ortho and meta position (non- and mono-ortho CBs). The information concerning the differences in bioaccumulation of CBs for closely related mustelid species increased the understanding of reported differences in PCB toxicity between mink and ferrets, and suggest that weasel, stoat, and otter are at least as sensitive to CBs as are mink, while polecats are less sensitive. As otter is exposed to much higher concentrations of CBs trough their diet than weasel and stoat, the toxic threat of CBs will be the greatest for this animal. Received: 10 February 1998/Accepted: 6 July 1998     

Ocular antigens VIII: assay of delayed hypersensitivity to corneal epithelium in the rabbit.

Rabbits were sensitised with complete bovine corneal epithelium. The lymphocyte stimulation test was performed with the lymphocytes of these rabbits using the soluble and sonicated insoluble fraction of the corneal epithelium as the antigens. A striking difference existed in the optimal test conditions for these antigen fractions. By comparing the results of the lymphocyte stimulation test with other immunological parameters, namely, skin test reaction, antibody titre, and phytohaemagglutinin stimulation of the lymphocytes, we concluded that both antigen fractions stimulate predominantly the T-lymphocyte system, although boosting augmented the humoral immune response. Stimulation of the cultured lymphocytes by both the separate and mixed antigen fractions is evidence for the existence of crossreacting antigens between the soluble and insoluble epithelial fractions.     

Experimental uveitis in isolated humoral and cellular immunity

Summary Passive transfer of homologous immune serum in rabbits followed by intravitreous injection with the corresponding antigen resulted in an uveal inflammation which resembled the Arthus-type reaction. Clinically and histologically, the reaction was maximal 24 h after antigen injection. The histologically observed cell infiltration consisted predominantly of polymorphonuclear leukocytes.Passive transfer of sensitized homologous thymocytes followed by intravitreous injection with the corresponding antigen resulted in an uveal inflammation which resembled the delayed-type hypersensitivity reaction. Tissue infiltration of polymorphonuclear cells as well as mononuclear cells occurred predominantly during the first day following antigen injection. An exudate containing almost exclusively eosinophils was present in the aqueous humor and/or vitreous body of most of these rabbits. During the second day an increase in the ratio mononuclear cells/polymorphonuclear cells could be observed.