Embryonic loss in pony mares induced by intrauterine infusion of Candida parapsilosis

Pony mares which were detected pregnant by transrectal ultrasonography received a single intrauterine infusion of either sterile saline (control, n = 12 mares) or 10(6)Candida parapsilosis (treated, n = 12 mares) between Days 11 to 14 postovulation. Subsequent embryonic loss was studied by daily ultrasonography of the mare's uterus, by serum progesterone levels, by endometrial swabs for cytologic and microbiologic examination and by endometrial biopsies that were taken after embryonic loss was detected. Significantly fewer (P<0.01) embryonic losses occurred in control than in treated mares (4 12 vs 12 12 ). The mean interval from intrauterine infusion until embryonic loss was 5.8 +/- 2.8 d for control mares (n = 4) and 2.1 +/- 0.2 d for treated mares (n = 12). Prior to embryonic loss, moderate to marked edema of the endometrial folds in 12 of 12 treated mares and free fluid in the uterine lumen of 5 of 12 treated mares were detected by ultrasonography. After embryonic loss, Candida parapsilosis was cultured from the uteri of 8 of 12 treated mares, and E . coli was cultured from the uteri of 2 of 4 control mares. Postloss endometrial smears had cytologic evidence of inflammation in 10 of 12 treated mares and 3 of 4 control mares. Intrauterine inoculation of C. parapsilosis consistently induced embryonic loss and may provide a basis to further study the relationship between endometritis and embryonic loss in mares.     

Structural Features of Human Monoamine Oxidase A Elucidated from cDNA and Peptide Sequences

Monoamine oxidase (MAO), an important enzyme for the degradation of amine neurotransmitters, has been implicated in neuropsychiatric illness. The amino acid sequence for one form of the enzyme, MAO-A, has been deduced from human cDNA clones and verified against proteolytic peptides. The covalent binding site for the flavin adenine dinucleotide (FAD) cofactor is near the C-terminal region. The presence of features characteristic of the ADP-binding fold suggests that the N-terminal region is also involved in the binding of FAD. These cDNAs should facilitate the study of the structure, function, and intracellular targeting of MAO, as well as the analysis of its expression in normal and pathological states.     

Phloem Mobility of Xenobiotics: II. Bioassay Testing of the Unified Mathematical Model

Two bioassays were used to test phloem mobility of selected xenobiotic compounds: (a) excised bean leaf assay; (b) rooted bean leaf assay. Compounds assayed were N-alkylpyridiniums with systematic variation in octanol-water partition coefficients (log K_ow), substituted benzoic acids with about the same log K_ow value but variable acidities. Results of the assays strongly conform, quantitatively, to the predictions of the unified mathematical model. Results also indicate that the membrane permeability value of a compound, which depends directly on log K_ow value, is the overriding factor in determining phloem mobility. When the weak acid functionality of a compound confers increased phloem mobility, it does so principally by making the log K_ow value, and consequently the membrane permeability of the compound more optimal.     

Toxic Effects of Copper on Photosystem II of Spinach Chloroplasts

The room temperature fluorescence induction of chloroplasts was utilized as a probe to locate the site of inhibition on PSII by copper. It was found that, while the initial fluorescence yield was hardly affected, the variable fluorescence yield was lowered without significant change in its kinetics. Addition of DCMU, or abolishing oxygen evolution capability by Tris treatment, did not alter this basic inhibition pattern. Copper was also found to lower the fluorescence yield of chloroplasts treated with linolenic acid which inhibited the secondary electron transport on both oxidizing and reducing sides of PSII. The data indicate that copper adversely affects the primary charge separation at the PSII reaction center. We suggest that the inhibition is due to creation of a lesion close to the reaction center, leading to increased dissipation of incoming excitation energy to heat.     

Hydrolysis of myelin basic protein in human myelin by terminal complement complexes

The participation of terminal complement complexes (TCC) in demyelination has been shown in rodent cerebellar cultures. Since TCC modulates activities of various membrane-associated enzymes and increases the level of cellular Ca2+ we investigated whether TCC could activate Ca2+-dependent neutral proteases in myelin that would lead to hydrolysis of myelin basic protein (BP). Addition of antibody and C7-deficient serum plus C7 to sealed myelin vesicles of two to six bilayers caused significant BP hydrolysis compared to the hydrolysis caused by antibody and C7-deficient serum. Significant hydrolysis occurred at the stage of C5b6,7 assembly, which increased in magnitude at the C5b6-8 stage. C5b6-9 formation did not enhance the effect of C5b6-8. BP hydrolysis by C5b6,7 did not require Ca2+ whereas the effect of C5b6-8/C5b6-9 was, in part, Ca2+-dependent. We postulated that TCC formation in myelin membranes causes activation of myelin-associated neutral proteases with subsequent hydrolysis of BP as a consequence of complement peptide insertion and channel formation. Such processes may alter the structure of myelin and augment the action of other inflammatory cells and their products in demyelinating diseases that could ultimately lead to the loss of myelin.     

Rapid profiling of bacterial quinones by two-dimensional thin-layer chromatography

Bacterial quinones were analysed by two-dimensional thin-layer chromatography with ready-made, multi-phase silica gel plates which allowed good separation of complicated quinone mixtures. A combination of this method and silver-ion-modified thin-layer chromatography made it possible to identify partially hydrogenated quinones.     

Ellipticine increases the superhelical density of intracellular SV40 DNA by intercalation.

We investigated the in vivo effect of ellipticine, a mammalian topoisomeraseII(topoII) inhibitor, on SV40 DNA topology. In contrast to epipodophyllotoxins, ellipticine did not cause significant double stranded cleavage of intracellular SV40 DNA. Furthermore, ellipticine reduced cleavage induced by epipodophyllotoxins, VP16 and VM26. Unexpectedly, ellipticine dramatically increased the superhelical density of a fraction of intracellular SV40 DNA. Several lines of evidence suggest that the formation of this highly supercoiled DNA species (Ih form DNA) is not due to the inhibition of topoII per se, but is the result of intercalation by ellipticine in a subfraction of the intracellular SV40 chromatin followed by the fixation of DNA linking number by a topoisomerase activity. Based on the linking number change and the known unwinding angle of ellipticine, the intercalation density was calculated as one ellipticine molecule per 10-20 bp in the Ih DNA. This result suggests the existence of different populations of intracellular SV40 chromatin with respect to the accessibility to ellipticine intercalation.