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A method is described enabling the direct measurement of vincristine resistance in intact tissues in vivo by morphological study. Using the metaphase arresting properties of the drug, counts were made of escaping anaphase and telophase mitotic figures at a range of doses. The proportion of post-metaphase mitotic figures is called the post-metaphase index (PMI). In 95 primary intestinal tumours induced by dimethylhydrazine (DMH) in rats, an increase in resistance to vincristine was shown over normal mucosa (P less than 0.001). The data were analysed by computer modelling and a linear relationship is demonstrated between the logit of the post-metaphase index, and log dose of vincristine. To achieve a PMI of 1% the fitted lines show an enhanced vincristine dose requirement over normal mucosa of 6 times in colonic tumours, and 8 times in small intestinal tumours. Non-neoplastic mucosa from the DMH-treated animals requires an enhanced dose of vincristine of 1.5 times, compared with normal mucosa, to achieve a PMI of 1%. Given current interest in the mechanism of vincristine resistance in cell lines this new approach provides a technique for assessing the resistance of solid tumours, both in vivo and in vitro, and for subsequent experimental manipulation.

Carbon fibre patches were inserted as prostheses into the dorsal lumbar fascia of rabbits. Their incorporation into the tissues was observed over a period of 15 weeks, and their mechanical properties were compared with those of implants made of a conventional Mersilene mesh. Although the mechanical properties of carbon fibre patches are initially poor, the development of a superior connective tissue response after several weeks suggests that a layered composite of carbon fibre and Mersilene with the latter giving initial strength may provide a useful material for clinical use as a hernia prosthesis.

We have measured mitotic indices and 3H-thymidine-labelling indices for the colonic epithelial tumours induced in rats by the administration of dimethyl-hydrazine (DMH). The fraction-of-labelled-mitoses (FLM) technique has been used to estimate the duration of the cell-cycle phases. In general, mitotic and labelling indices in the tumours are similar to those in the proliferation zone of the normal crypt epithelium; lesions considered to be least well differentiated on histological grounds appear to have the lowest mean labelling index. Benign tumours and the different types of malignant tumours have mean cell-cycle times about half those of the normal mucosa.

Mucosal explants were prepared from the colons of normal rats and from the non-neoplastic colonic mucosa of rats which had been treated chronically with the intestinal carcinogen dimethylhydrazine. They were maintained in an organ culture system which permitted survival up to at least 25 days. Morphological preservation of the mucosa was excellent up to 6 days in culture and thereafter changes began to occur. But even at 25 days normal crypt structures were still evident. The hyperplastic and dysplastic changes seen in pre-culture samples of DMH-treated mucosae remained recognisable during the first two days in culture. They were no longer seen in explants examined after this time however and, indeed, there appeared to be no difference in the morphology and survival of control and DMH-treated mucosae. It is possible that our culture system does not permit further neoplastic progression, but an alternative explanation is that the system discriminates specifically against the survival of neoplastic elements.

A case of visceral Kaposi's sarcoma occurred in a patient with adult celiac disease. A search of the literature has failed to disclose any previous case showing this association, although Kaposi's disease has been reported to occur in a variety of situations in which immunological abnormalities have been manifest. Conversely, celiac disease has been shown to predispose to the development of a variety of malignant neoplasms.

Using a system designed to preserve, in vitro, both the epithelial and the connective tissue elements, we have maintained adult colonic mucosa in organ culture for up to 336 hours and have investigated the sequential morphological changes which occur. During the first 48 hours, normal micro-architecture is preserved, but there is progressive loss of cytoplasmic mucin from crypt cells. Subsequently, accelerated degenerative changes develop; cells are lost from the crypts and, because cell proliferation in the crypt is reduced, these lost cells are not replaced. For a time, the crypts are represented by discrete acinar formations or clusters of cells in the lamina propria, apparently discontinuous with the intact surface epithelial layer. These remnants manifest intense proliferative activity during the period between 72 and 96 hours after explantation, leading to the restoration of well formed crypts lined by columnar epithelial cells between 120 and 144 hours; differentiation of goblet cells ensues and this state of virtually normal structure persists until the termination of culture between 186 and 336 hours. It is concluded that the determination of normal crypt structure and of crypt-cell differentiation is governed by intrinsic control mechanisms although these may be subject to extrinsic modulation. Whether or not the degeneration phase can be eliminated, it is clear that long term culture of adult human colonic mucosa is possible. Such a system may be useful in the study of mucosal function and of mucosal response to drugs, carcinogens and trophic factors.

This study was undertaken in order to compare cell proliferation at different sites along the length of the large bowel of the mouse. Simple morphometry has been used along with 3HTdR labelling studies and metaphase arrest with vincristine. Differences have been described in the shape and size of crypts, the distribution of proliferating cells, the duration of the cell cycle, as well as in the rate of cell production by the crypts. The findings explain some of the apparent inconsistencies in the literature.

At eight time points over a period of 24 hours, crypt length (in cells) and crypt cell birth rate were measured by the stathmokinetic method with vincristine and evaluated at two sites in the small intestine and two in the colon in Wistar Porton rats. Normal animals were compared with animals which had received 24 injections, at weekly intervals, of the intestinal carcinogen 1,2-dimethylhydrazine. In the treated animals, crypts were significantly longer at sites prone to tumour formation but not at those sites known to be resistant to the effects of the carcinogen. In neither group of animals was there any significant fluctuation in mean crypt length over a 24 hours period. Crypt cell birth rates showed a considerable fluctuation. No difference was noted between normal animals and those treated with dimethylhydrazine and statistical analysis failed to confirm the presence of any true periodic fluctuation.

The successful development of a long-term organ culture system has made it possible to perform experiments on rat colonic mucosa in vitro. However, the effect of trauma or the withdrawal of trophic influences in culture may result in the disturbance of proliferation within the tissue. In this paper we describe an investigation designed to characterise the culture system by a comparison of the proliferative parameters in vitro with those in vivo. Stathmokinetic experiments were performed in vivo and in vitro to estimate cell birth rate. Mitotic indices were also calculated. The in vivo birth rate (7.8 +/- 0.8 cells/1000 cells/hour) and the in vitro birth rate for the whole explant (7.7 +/- 0.5 cells/1000 cells/hour) were found to be similar. A study of crypts in the centre and at the edge of the cultured explants, however, indicated that proliferation at the two sites differed markedly, the birth rate at the edge (7.5 +/- 0.9 cells/1000 cells/hour) being approximately twice that at the centre (3.2 +/- 0.9 cells/1000 cells/hour). Provided that this topological difference in proliferation within the explant is recognised the in vitro model, in particular the basal level found at the centre, may still be regarded as a valid system for studying tissue responses to carcinogens and trophic factors.

In organ culture tissues undergo adaptive changes which complicate the assessment of proliferative indices. In the present study, a technique devised to preserve collagen metabolism and mesenchymal stroma in tissues of mixed origin was employed to investigate the kinetic behaviour of human colorectal mucosa over the first 24 hours in culture. During this period the structural preservation of tissue is good. The mitotic index in mucosa is profoundly depressed throughout the explants during the first 2-6 hours in culture. During this same period, however, heavy uptake of tritiated thymidine, indicating DNA synthesis, is observed within 150 micron of the cut edge of the samples but not centrally. This phenomenon has been described previously and assumed to be the result of inadequate diffusion of oxygen into the tissue. The 'edge labelling' phenomenon is followed by a wave of mitosis in the tissue edge at 8-18 hours in culture. This delay between tritiated thymidine uptake and the appearance of mitoses in the tissue edge may simply represent the duration of the S + G2 phase of the cell cycle, but is more likely to be due to cells in G1 moving into the S phase followed by cells hitherto blocked in G2 being stimulated into the M phase. After 18 hours the mitotic and labelling indices become more uniform throughout the samples suggesting that 'edge labelling' is partly due to local stimulation of cell proliferation by trauma rather than central inhibition due to diffusion problems. These results suggest that in this organ culture system, assessment of proliferative indices should be carried out after these adaptive changes have settled.

Gastric hyalinization is an unusual abnormality that has in the past been regarded by some authorities as a postmortem artifact. We describe a 69-year-old patient who presented with symptoms due to the condition, and who was treated by surgical resection of the diseased stomach. To our knowledge, no other case presenting in life has been identified in the literature, which we reviewed in the light of the present case. The cause of the condition remains unknown.

Administration of 1,2 dimethylhydrazine (DMH) to rats by weekly s.c. injections causes the development of multiple epithelial tumours of the large bowel. These appear to arise as localized dysplastic abnormalities in hitherto apparently morphologically normal crypts. This study was undertaken in order to examine cell proliferation in such apparently normal crypts of DMH-treated animals. A number of proliferative abnormalities are evident, including changes in the size of the crypts, changes in the disposition of proliferating cells within them and reduced cell-cycle times. The nature and the extent of the abnormalities vary from site to site along the length of the bowel, and reflect the vulnerability of the different segments of the bowel, not only to the carcinogenic effects of DMH, but also to short-term toxicity.

When symmetrical 1,2 dimethylhydrazine was administered to rats by weekly s.c. injection, 37% of the animals had developed small intestinal carcinomas after 21-27 weeks. These lesions were largely localized to duodenum and upper jejunum. At the same time there was a diffuse crypt hyperplasia in the jejunum which affected all the treated animals, not just those with neoplasms. This marked hyperplasia was preceded by a modest sustained crypt elongation which was seen soon after DMH injections began. In these hyperplastic jejunal crypts the absolute size of the proliferative compartment was increased, but the growth fraction calculated from labelling studies appeared to fall, probably by reduction in relative size of the proliferating population within the proliferative compartment. No convincing alteration in actual cell-cycle time was observed in the abnormal crypts. There was a slight (25%) increase in cell-production rate in the abnormal crypts.

Twenty eight patients with colonic cancer, who were asymptomatic after intestinal resection and anastomosis, underwent colonoscopy as part of their routine follow up, and biopsies were obtained from the anastomosis and several other sites. Sections were stained by haematoxylin and eosin, several methods for mucin, and by the peroxidase-antiperoxidase method for carcinoembryonic antigen. Non-specific inflammatory changes were seen at the anastomosis in 11 of the 28 cases, apparent in several two years after operation; focal surface ulceration was seen in over half these samples. Neither dysplastic nor adenomatous change was detected, but at seven anastomoses the so called transitional change, which has been regarded as a preneoplastic change, was apparent. There was no consistent alteration in carcinoembryonic antigen reactivity. It is concluded that there is morphological evidence of a continued stimulus to regenerative activity at some anastomoses and that this may represent a promoting factor enhancing further carcinogenesis.