Fourier transform infrared spectroscopy of dysplastic, papillomavirus-positive cervicovaginal lavage specimens

To assess the utility of a new, rapid, economical procedure that may prove valuable in cervical screening, Fourier transform infrared (ir) spectroscopy was performed on 25 cervicovaginal lavage specimens from women referred for colposcopy on the basis of a cytological abnormality detected on their Pap smear and whose lavage specimen was positive for human papillomavirus. Of the 18 classed as CIN I or less by histopathology, 11 showed band frequencies that deviated only slightly from spectra that characterize normal cervical cells and 3 of 5 "atypia" specimens had spectra identical to normal. Two of 3 classed as CIN II had spectra only slightly more abnormal to these 11. In the case of 2 graded as CIN I, several bands were similarly altered in the direction of the pattern seen for 4 CIN III specimens. A further CIN I sample gave a spectrum that was even further shifted toward the latter and the remaining CIN I sample had a pattern that matched the 4 CIN IIIs. The most obvious change in each of the CIN IIIs was an additional peak at 972 cm-1 and this has been suggested as a key indicator for malignancy. One of the 3 CIN IIs had this peak. Other characteristic spectral changes were seen as well in the CIN III samples. High-risk HPV18 was present in 3 of the CIN III samples, as well as in one specimen classed as atypia, but having an abnormal ir spectrum. Low-risk HPV 6 or 11 was seen along in samples with a normal or slightly abnormal ir spectrum, but never in those that showed an ir pattern that was abnormal. The current study has therefore shown complete concordance between ir spectral findings and histopathology result in the case of CIN III specimens, but less precise matching for other grades of CIN. The spectral differences revealed by ir spectroscopy are likely to characterize molecular abnormalities in cervical cells during progression to cancer and may therefore have potential in assisting with clinical decision making. More studies will, however, be required to establish the place of this technique in cervical screening.

Role of intestinal mucus in transepithelial passage of bacteria across the intact ileum in vitro

BACKGROUND

Although gastrointestinal mucus is one of a number of putative host defense mechanisms that protect the gut barrier against microbial translocation, little experimental data are available to show its role in this process. The present study sought to determine the role of mucus depletion on the transepithelial passage of bacteria across viable segments of rat ileum mounted in Ussing chambers in vitro.

METHODS

Intestinal mucus was depleted in 12 rats after injection with pilocarpine (160 mg/kg intraperitoneally) 45 minutes before intestinal harvest. The mucosal surfaces of the perfused gut segments mounted in the Ussing chamber were exposed to 5 x 10(9) CFU/ml Escherichia coli C-25. Viability was monitored by continuous measurements of the potential difference generated by the membranes. The electrical characteristics were unaltered by pilocarpine pretreatment or exposure to bacteria.

RESULTS

Bacterial passage occurred in 100% of pilocarpine membranes as compared with 33.3% in controls (p < 0.05). Pilocarpine-treated membranes resulted in 19.9 +/- 7.5 mg of retrievable mucus as compared with 28.8 +/- 7.2 mg in controls (p < 0.05). Light and transmission electron microscopy revealed an intact epithelial surface in all membranes. There was a marked decrease in mucus on the surface of pilocarpine-treated membranes.

CONCLUSIONS

Intestinal mucus secretion is a critical factor in the barrier function of the gut, and its depletion results in a dramatic increase in bacterial passage across the intact rat ileum.