Alexander J. Watson

A controlled trial of prednisolone treatment in primary biliary cirrhosis: Three-year results

The results of a 3-year, placebo-controlled trial of prednisolone treatment in primary biliary cirrhosis (PBC) are presented. The active (n = 19) and placebo (n = 17) arms were initially well matched for age, menopausal status and disease severity. At 3 years hepatic symptoms were relatively improved in the prednisolone group. Hepatic mortality was 3/19 (prednisolone), 5/17 (placebo) (p = n.s.). For all liver blood tests the trend favoured prednisolone treatment, though the differences were only significant for alkaline phosphatase and protein. All immunoglobulins fell significantly. Quantitative ELISA determination of antimitochondrial antibody showed a significant fall in the prednisolone group compared with placebo (p less than 0.001 at 1 year, p less than 0.05 at 3 years). Deterioration in histology (appearance of cirrhosis) was more common in the placebo group. Overall hepatic function (hepatic mortality, doubling in bilirubin, 6 milligrams fall in albumin, de novo appearance of cirrhosis or symptoms of portal hypertension) was significantly worse in the placebo group (p less than 0.01). After 3 years no significant differences could be detected in bone mineral content (single photon absorptiometry of radius and femur) between the two groups or in comparison with other PBC patients. Thus, after 3 years, prednisolone treatment was associated with a better overall hepatic outcome and little evidence of increased bone loss.

Cell kinetics in flat (avillous) mucosa of the human small intestine

A new method for the analysis of small-intestinal crypt-cell kinetics using routine peroral diagnostic biopsies is described. Untreated patients with childhood and adult coeliac disease and adults with the gluten-sensitive enteropathy of dermatitis herpetiformis were studied, together with groups of adult and childhood controls. In the classical flat avillous mucosae the increase in crypt size was found to be three-dimensional. The number of proliferating cells per crypt was shown to be markedly increased, and an even greater rise in the crypt-cell production rate was demonstrated. A significant increase in the mitotic index was also confirmed in the avillous mucosae. On the basis of these findings it is suggested that the characteristic crypt morphology in glutensensitive enteropathy can be explained as an adjustment to accommodate the expanded mass of proliferating and maturing cells necessary to support the augmented cell production rate. We may speculate that this in turn is a response to a pathologically rapid loss of cells from the mucosal surface.

Studies on the mechanism of diurnal variation of proliferative indices in the small bowel mucosa of the rat.

In the rat small bowel mucosa significant variation was found in both the labelling and the mitotic indices with time of day. The zenith and the nadir of labelling and mitotic activity coincided at 15.00 and 02.00 hours respectively. Small changes were found in the ‘cut‐off’ position, but this variation in proliferative compartment size was insufficient to account for the comparatively wider fluctuations in proliferative indices. Measurements of the rate of entry into mitosis, using metaphase arrest with vincristine at three widely separated times during the day, showed no significant change.

Cell population kinetics in the mouse jejunal crypt

SummaryThe time parameters of the cell cycle were determined in the jejunal crypts of male Balb/c mice by an FLM experiment. The cell cycle time was 12.42 ±0.11 h, and the duration of DNA synthesis was 7.61 ±0.09 (mean values ± S.E.). A stathmokinetic technique using vincristine gave a value of Tc of 11.8 h.The growth fraction (Ip) calculated from cycle parameters and the labelling index was 0.61, while a value of Ip estimated from a labelling index distribution curve was 0.65.For the whole crypt a value of 0.86 h was obtained for the duration of mitosis, longer than that in the rat. The mitotic duration was found to vary with cell position, but values of between 0.8 and 1.2 h prevailed throughout the proliferative compartment; values in the basal cell positions appeared shorter. Apparent cell cycle times were longest in the basal cell positions.A value for crypt migration rate calculated from a cumulative birth rate curve was 1.48 cell positions per h, compared with a value of 1.8±0.27 cell positions per h as measured from movement of the 50% peak value on the labelling index distribution curve with time after tritiated thymidine.The crypt cell production rate was calculated from microdissected and squashed crypts to be about 14 cells per crypt per h. There was a total crypt population of 282± 65 (S.E.) cells, of which 172 were proliferative.

The cell cycle time in the flat (avillous) mucosa of the human small intestine

A hyperproductive mucosal state in gluten-sensitive enteropathy has been proposed on the basis of an elevated mitotic index, but this parameter is dependent on the mitotic duration when used as an index of proliferative status. The mitotic duration was therefore measured in two control patients with normal villous mucosae and in two patients with the flat avillous mucosa of untreated gluten-sensitive enteropathy, using two different stathmokinetic techniques with vincristine. No significant difference in mitotic duration was found but values obtained for cell cycle time showed a halving in the flat mucosae. An increased rate of cell production in the small bowel mucosa of untreated gluten-sensitive enteropathy is thus confirmed.

Cell proliferation at different sites along the length of the rat colon

SummaryThis study has been undertaken in order to compare in detail cell proliferation in the mucosal crypts at several sites along the length of the large bowel of the rat. The techniques which have been used include simple morphometry, calculation of mitotic and tritiated thymidine labelling indices, metaphase arrest with vincristine, and the fraction of labelled mitoses method.Major differences exist in the size and shape of the crypts at different sites. In particular the distribution of the proliferating cells within the crypt varies. Mean cell cycle time ranges from 58 h in the descending colon to 25 h in the caecum; this variation appears to be brought about largely by changes in the duration of G1, the other phase durations remaining relatively constant. There is also variation in cell cycle time and growth fraction at different levels within the crypt; throughout the bowel cells appear to cycle more slowly at the bottom of the crypt, but changes in growth fraction do not display a similarly consistent pattern.Clearly the organisation of cell proliferation in the normal rat colon is very complex, and strict definition of anatomical location is required in any study of cell proliferation whether in normal or in diseased animals.

The effect of a single injection of hydroxyurea on cell population kinetics in the small bowel mucosa of the rat.

The effect of a single injection of hydroxyurea (HU) on cell population kinetics in the jejunal crypt of the rat was studied using autoradiography with tritiated thymidine and metaphase arrest with vincristine. HU appeared to act selectively on cells in the S phase producing inhibition of DNA synthesis and cell death. The deficit in proliferating cells was made good by a decrease in cell cycle time and an increase in growth fraction. Particular attention was paid to the basal, slowly cycling (and possibly clonogenic) crypt cells; early in the recovery sequence an increase in cell production rate was found in the base of the crypt.

THE CELL CYCLE TIME IN THE RAT JEJUNAL MUCOSA

The regional variation of the duration of cell cycle parameters was studied by constructing fraction of labelled mitoses curves at several levels in the jejunal crypt column of male Wistar rats. Prolonged Tc and Ts values were apparent only in the bottom eight cell positions, and these differences were shown to be significant compared with the remaining cell positions by analysing the data by the method of Gilbert (1972). Above cell position 8 the proliferating crypt cells showed effectively the same phase durations. For the whole crypt column Tc was 11.32 ± 0.14 (SE) and Ts 6.49 ± 0.10.

Pathological features of the colonic tumours induced in rats by the administration of 1,2-dimethylhydrazine

SummaryThe parenteral administration of 1,2-dimethylhydrazine to rats caused the development of colonic neoplasms in about 90% of animals by 24–30 weeks of treatment. Usually there were multiple tumours with a mean of 2.7 per rat. The lesions have been classified histologically into adenomata (26% of all tumours) and carcinomata, the latter showing varying degrees of differentiation. No completely anaplastic tumours were seen, and there were none originating in connective tissue. The distributions of the different tumour types along the length of the colon varied. The more benign lesions were situated predominantly in the distal half of the colon, while the poorly differentiated adenocarcinomata were concentrated in the proximal third of the colon.There was good evidence to suggest that adenomata often progressed to frank malignancy in the distal colon. In the proximal part, however, it appeared that tumours frequently developed de novo as poorly differentiated carcinomata. Perhaps regional variations in the kinetic organisation of the normal colonic mucosa somehow influence the nature of the neoplastic change induced by DMH, thus accounting for the differences in tumor distribution.After 24 weeks of DMH treatment there was only a small increase in the mean number of tumours per rat.

CELL POPULATION KINETICS IN THE RAT JEJUNAL CRYPT

Cell kinetics in the jejunal crypt of the male Wistar rat were studied using autoradiographic techniques with tritiated thymidine and a stathmokinetic technique with vincristine. The migration rate measured by following the movement of the 50 % peak on the labelling index distribution curve with time after injection of tritiated thymidine gave a value of 1.43 ± 0.14 (SE) cell positions per hour, compared with a value from a cumulative birth rate of 1.78 cell positions per hour.