Time course of the carbon tetrachloride-induced decrease in mitochondrial aldehyde dehydrogenase activity

Hepatic microsomal enzymes like cytochrome P-450 and glucose 6-phosphatase are inhibited after exposure to CCl4 in vivo. Since comparatively less is known about the effects of CCl4 on nonmicrosomal enzymes, we investigated the rapidity by which CCl4 inhibits the low Km mitochondrial aldehyde dehydrogenase (ALDH) isozyme, an enzyme known to be inhibited 24 hr after CCl4 treatment. The activity of this ALDH isozyme was significantly lowered 6 and 12 hr after a single 1 ml/kg intragastric dose of CCl4. The mitochondrial low Km ALDH specific activities exhibited a similar pattern of destruction/inhibition to the documented target enzyme microsomal cytochrome P-450 in that lowest values were observed 6 hr after CCl4. These values were 44 and 37% of control for cytochrome P-450 content and the low Km ALDH activity, respectively. Alcohol dehydrogenase activity, expressed as activity per gram liver, was depressed 12 hr after CCl4 dosing. Finally, the activity of the low Km cytosolic ALDH, the isozyme that metabolizes malondialdehyde at low concentrations, was not affected by CCl4 treatment. The CCl4-induced decline in the activity of the matrix ALDH isozyme occurs earlier than previously reported mitochondrial damage. The study of sensitive enzymes like the low Km ALDH may provide valuable information by which it may be possible to determine the relationship of the truly rapid biochemical effects of CCl4 such as microsomal lipid peroxidation with later effects on nonmicrosomal components.     

Benign glandular inclusions in the abdominal lymph nodes of a man

The occurrence of benign glandular inclusions in the abdominal lymph nodes of a man is reported. The cells lining the glands were most likely derived from metaplastic mesothelial cells. Awareness of these benign glandular inclusions is essential, in that they simulate metastatic adenocarcinoma morphologically.     

In Vitro and In Situ Characterization of Fish Thymic Nurse Cells

We present an enzyme- and immuno-cytochemical, and ultrastructural characterization of trout thymic nurse cells (TNCs). Our data suggest that isolated trout thymic multicellular complexes are epithelial cells with acidic compartments that may be involved in the processing of antigens and in the generation of the MHC-II proteins that these cell express, and also that isolated TNCs are the In Vitro equivalent of the pale and intermediate electronlucent epithelial cells located in the inner zone of the trout thymus, constituting indirect evidence of the phylogenetical relationships of the inner zone of the teleost thymus with the thymic cortex of higher vertebrates.     

Bacteriostatic qualities of human milk

A practical concern of the working mother is the bacteriostatic quality of human milk over time without benefit of refrigeration. Therefore, quantitative cultures of human milk stored at room temperature were performed at 0, 2, 4, 6, and 24 hours after expression. Milk from 10 mothers less than six days postpartum (colostrum) and from 10 mothers 7 to 42 weeks postpartum (mature milk) was studied. The number of colony-forming units per milliliter of milk cultured at 0 time did not significantly increase in mature milk after 6 hours nor in colostrum after 24 hours of storage at room temperature. Thus, mothers who express milk for their own infants while at work may assume that the bacterial contamination of their milk will not increase significantly for up to but no longer than 6 hours after expression, even if they have no access to refrigeration.     

In vitro models of xenobiotic metabolism in trout for use in environmental bioaccumulation studies

1.?In vitro screens are sought as informative, alternatives to the use of animals in vivo and to improve upon the current use of fish liver 9000?g supernatants (S9) in environmental risk assessment.

2.?The rates of ethoxyresorufin-O-deethylation (relative to S9 protein) measured under different conditions of culture of rainbow trout hepatocytes were significantly higher than those detected in S9, in the order of freshly isolated hepatocytes > 10-day spheroid cultures > primary hepatocytes in culture > S9. The percentage of conjugated metabolites was also similar between freshly isolated and spheroid cultured hepatocytes (9.9 and 13.5%).

3.?The rate of oxidation was enhanced (1.7 fold) when S9 was supplemented with cofactors for phase II conjugation but this was only approximately one tenth of the rate in freshly isolated hepatocytes (7.1 pmol/min/mg S9 protein equivalent).

4.?Hepatocytes also hydroxylated ibuprofen, producing two metabolites, in contrast to only one (identified as the 1-hydroxy derivative) using hepatic S9 fractions.

5.?Since the bioaccumulation potential of chemicals is often based on un-supplemented S9 in incubations ≥1?h when activity declines, it is recommended that predictability would be greatly improved through the use of hepatocyte spheroids, due to their maintenance of activity and longevity.