Determination of lipid hydroperoxides in native low-density lipoprotein by a chemiluminescent flow-injection assay

Lipid hydroperoxides have been implicated in the pathogenesis of atherosclerosis. This work was therefore set up to obtain a fast and specific chemiluminescent assay for measuring hydroperoxides in native low-density lipoprotein (LDL). The apparatus was a complete HPLC system including two pumps, an autosampler, a computer and a chemiluminescent detector with a T-mixing coil in the place of the column. Samples were injected from the autosampler and mixed with luminescent reagent (3 microM luminol and 1 microM microperoxidase in 0.1 M carbonate buffer (pH 10)) in the T-piece. To generate a calibration curve, linoleic acid hydroperoxide was obtained by incubating soybean lipoxygenase with linoleic acid. The calculated conjugated diene concentration was in good agreement with the nominal linoleic acid hydroperoxide concentration. The chemiluminescence was linear with the amount of linoleic acid hydroperoxide injected and the detection limit was about 3 pmol linoleic acid hydroperoxide. The chemiluminescence induced by copper-oxidized LDL was linear with concentration; the detection limit, when compared with linoleic acid hydroperoxide, was similar. The reproducibility of the linoleic acid hydroperoxide and of oxidized LDL hydroperoxide was examined in single pools. The coefficient of variation on the triplicates of each pool was about 3%. The titre of the linoleic acid hydroperoxide and oxidized LDL peroxides was quite stable for at least 10 days when stored under argon at 4 degrees C in the presence of EDTA. The mean value of the LDL hydroperoxides in 16 control subjects was 145.20 +/- 98.81 pmol/mg LDL protein. In conclusion, the microperoxidase-luminol-dependent chemiluminescence flow-injection assay is a rapid, sensitive and selective method for measuring lipid hydroperoxides in native LDL.

Experimental observations on the specificity of Strigea falconispalumbi (Trematoda: Strigeidae) toward planorbid first intermediate hosts

Planorbis planorbis, Planorbarius corneus and Biomphalaria alexandrina (Egyptian strain) were ascertained as new experimental first intermediate hosts, thus bringing the total number of planorbid experimental first intermediate hosts to eight. The highest degree of compatibility was exhibited with P. planorbis (infection prevalence 80%) followed by P. corneus (46.6%), whereas B. alexandrina (as snail species not occurring in the geographical range of S. falconispalumbi) showed the lowest degree of compatibility (23.3%).

Adaptation of postimplantation embryos to culture: membrane lipid synthesis and response to valproate

The environment of the conceptus in culture is quite different from that in utero. It is likely that the embryo adapts to this environment in various ways, but little is known of adaptation, nor of its significance to mechanistic studies using embryo culture. To illustrate this area, we summarize data from two comparative studies: of membrane lipid synthesis by conceptuses in culture and in utero, and of the morphologic response of conceptuses to valproate in these two environments. The synthesis of the major membrane lipids, cholesterol and phospholipids, is significantly affected by culture. De novo synthesis of cholesterol progressively increases during culture, compared to equivalent stages in utero. In contrast, phospholipid synthesis decreases in culture. Cultured conceptuses were morphologically similar to those in utero, suggesting that apparent structural normality does not guarantee biochemical activity equivalent to that in vivo. Conceptuses exposed to valproate in vivo showed a wide range of severity of defects. Those abnormalities that apparently permit survival to term seem relatively subtle, while more severe defects (as usually reported in culture studies) appear to be lethal. Subtle defects, very similar to those induced in vivo, can be reproduced in culture, but only with short-term, not continuous, exposure. We have previously proposed that valproate may interfere with embryonic lipid synthesis. Thus, despite lipid synthetic pathways adapting to the culture environment, the response to valproate in vitro, can mimic that in utero, with appropriate exposure conditions.

The development of handed asymmetry in aggregation chimeras of situs inversus mutant and wild-type mouse embryo

Mutant iv/iv mice develop as if they have no sense of left and right, so the development of asymmetry is random: half normal, half as a mirror-image of normal, situs inversus. We have made aggregation chimeras of 8-cell stage iv/iv and +/+ embryos, transferred them into pseudopregnant mice, and examined their phenotype on day 10 of gestation. The contribution of mutant and wild-type cells to tissues of the embryo was estimated by strain-specific isozyme (GPI-1) analysis. We have also performed reciprocal embryo transfers, iv/iv blastocysts into +/+ mice, and vice versa. These transfers show that the development of handed asymmetry is determined by embryonic genotype, and is unaffected by the maternal environment (at least after day 3), or by the procedures of embryo collection, culture and transfer. Our observations on the development of 21 viable chimeric embryos show that neither iv/iv nor +/+ cells are dominant. All embryos (12) with less than 50% contribution of iv/iv cells to the heart developed with normal situs. Of 9 embryos with greater than 50% iv/iv cells, only 2 developed with inverted situs. These findings suggests that there was partial ‘rescue’ of embryos by some influence of normal over mutant cells. However, we cannot, statistically, exclude an alternative interpretation that cells are behaving autonomously. Interestingly, the embryos that developed with inverted situs were unique in having greater than two thirds contribution of iv/iv cells to both the heart and the visceral yolk-sac.

The development of asymmetry: the sidedness of drug-induced limb abnormalities is reversed in situs inversus mice

We are studying the development of handedness, in particular the relationships between handed structures with bilateral symmetry, for example the limbs, and those with lateral asymmetry, such as the heart, lungs and gut. Asymmetric (unilateral) developmental limb abnormalities can be induced by chemical treatment of mouse embryos, either in utero by acetazolamide, or in culture by misonidazole. We have examined these effects in mice homozygous for the iv gene. The development of bilateral symmetry in iv/iv mice is normal, but the control of asymmetry appears to be random, that is 50% develop normally (situs solitus), 50% with laterally inverted viscera (situs inversus). We find that the handedness of induced asymmetric limb defects is highly correlated with embryonic visceral situs. Right limb defects are induced in situs solitus embryos, left-sided defects in situs inversus. This suggests that the mechanism of induction of asymmetric defects is not related to any intrinsic difference between the development of left and right limbs, but is connected to visceral asymmetry. In addition, the high correlation of limb defects with situs was observed in culture as well as in utero suggesting that the maternal environment plays no role in the development of asymmetry.

Fatal recurrence of neuroleptic malignant syndrome

The clinical features of a fatal case of the neuroleptic malignant syndrome are presented. The fatal episode was a recurrence of the syndrome after a milder episode 3 months earlier. Prescription of neuroleptics was continued unchanged following the latter, as a correct diagnosis was not made at the time. The case emphasises the importance of early recognition of the syndrome and the possibility of spontaneous remission of symptoms despite continued neuroleptic treatment.

Morphology of the carnation-light synthetic lethal focus in Drosophila melanogaster

A histological study of the carnation-light lethal focus revealed morphological abnormalities in brain tissue. The ratio of core width to total brain width and brain texture consistently differed between lethal (car-lt) and their non-lethal sibs.

The "Pooh Corner" vision study

Two groups of children were screened by selected optometrical tests. Infants between the ages of 3 and 24 months and kindergarten children aged from 2 to 5 years were tested. The results indicated that meaningful data can be obtained from both groups and that the tests revealed visuosensory and visuomotor defects, correction of which at an early stage is not only desirable but, in most cases, essential.