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A novel apparatus in which fluids may be injected and sampled at high pressure is described. Bioseparation applications of the apparatus were demonstrated in three model systems: (1) lambdaDNA was eluted under pressure from an anion exchange column into a low-salt (0.25 M) buffer, thereby eliminating conventional time-consuming desalting procedures required for downstream analysis of the DNA; (2) RNA was separated under pressure from a RNA/DNA mixture, thereby enabling rapid differential preparation of nucleic acids; and (3) an antibody was purified from a protein mixture by affinity capture at one pressure and dissociation from the antigen binding partner at a second pressure, thereby enabling the immunoreactivities of both antibody and antigen to be preserved during the separation process., (Copyright 1999 Academic Press.)

Astroglial cells dispersed from newborn rat hemispheres were established in medium supplemented with 20 per cent fetal calf serum (FBS) and then grown to a confluent monolayer in the presence of 10 per cent FBS or charcoal-stripped FBS (CS). Type 1 astrocytes were subcultured and either maintained under the same conditions of the primary cultures or converted to serum-free chemically defined medium (CDM). No differences were found in either MAO A or MAO B activity of astrocytes grown in the presence of FBS or CS after 15 and 21 days in vitro (day 1 and 6 of subculture). In contrast, on day 21 both MAO A and MAO B activities were markedly higher in astrocytes subcultured in CDM compared with cells maintained in serum-supplemented medium. This difference appeared to be due to increased number of enzyme molecules, since kinetic analysis showed an increase in Vmax of both MAO isoenzymes in serum-free medium, but no change in Km. Consistently, the recovery of MAO A and MAO B activity after irreversible enzyme inhibition by clorgyline and deprenyl was faster in CDM than in FBS-supplemented medium, indicating enhanced enzyme synthesis under serum-free condition. Estimates of half-lives for the recovery of MAO A and MAO B activity indicated that, under both culture conditions, type A activity had a higher turnover rate than type B. The effect of CDM on astrocyte MAO does not appear to be due to selection of a subpopulation of cells, but rather linked to a morphological change (differentiation) with increased synthesis of both MAO isoenzymes.

The present study was performed to determine the effect of the duration of chronic caerulein administration given at different doses, on the rat pancreas. Four groups of rats, one treated with 0.9% NaCl (control) and the others with caerulein 2, 5 and 10 micrograms/Kg twice a day i.p. were used. After a treatment period of 15, 30 and 60 days, 6 rats from each group were anesthetized, the pancreas was removed, and growth and composition of pancreatic tissue were determined. Small samples were taken for histological examination. Caerulein induced pancreatic hyperplasia and hypertrophy. The dose of caerulein used and the length of the treatment did not significantly modify the trophic effect. Focal perivascular and periductular lymphomonocytic infiltrates associated with cellular abnormalities were seen at 30 and 60 days. The results suggest that 1) the trophic effect of caerulein is not dose-and-time dependent and 2) morphological abnormalities can appear during long term treatment with CCK analogous.

Alkaline elution was employed to study DNA damage in CHO-Kl cells treated with a series of biotic and xenobiotic aldehydes. DNA cross-linking was measured in terms of the reduction in the effect of methyl methanesulphonate on the kinetics of DNA elution and was observed in cells treated with formaldehyde, acetaldehyde, methylglyoxal and malonaldehyde. Propionaldehyde, valeraldehyde, hexanal and 4-hydroxynonenal produced DNA single-strand breaks, or lesions which were converted to breaks in alkali. Both types of DNA damage occurred in cells exposed to malealdehyde. These findings support the hypothesis of a carcinogenic effect of the aldehydic products (malonaldehyde, methylglyoxal, propionaldehyde, hexanal, 4-hydroxynonenal) released in biomembranes during lipid peroxidation.

The alkaline elution method was adapted to the evaluation of DNA damage induced in vivo through a practical and reliable microfluorometric procedure, without any need for tissue pre-labeling. The DNA damage induced in vivo by treatment with a single dose of N-nitrosodimethylamine (DMNA), N-methyl-N-nitroso-urea (MNU), 1,2-dimethylhydrazine (DMH) or cycasin has been detected in different organs of mice or rats. The results obtained are rather consistent with the organotropism of these carcinogens, and show a satisfactory dose dependent of DNA damage. DMH and cycasin, both negative in the Ames' Salmonella/microsome mutagenicity test, are clearly positive with in vivo DNA damage/alkaline elution assay. This latter method, complemented with other short-term tests, may play a useful role in the pre-screening of chemical carcinogens.

DNA single-strand breaks induced in various organs of BALB/c mice by treatment with a single dose of 1,2-dimethylhydrazine (DMH) were studied by means of the alkaline elution method modified in order to allow the evaluation of DNA damage in vivo with no need of radioactive prelabelling. DNA damage was detected in liver, lung, kidney, stomach and colon mucosa, with the liver showing the greatest amount of damage. Its degree was dependent on the dose and route of administration. A differential effect was evident in colon mucosa from Swiss and C57BL/6 mice which are respectively susceptible and resistant to the induction of bowel tumors by DMH. The higher degree of DNA damage found in liver in comparison with colon mucosa is consistent with the previously reported higher degree of DNA methylation, but does not correlate with the specificity of this carcinogen in inducing tumors of the large intestine in mice given repeated subcutaneous injections.