Case report: carcinoma of the extraorbital lacrimal gland in a female Fischer 344 rat.

A large subcutaneous mass was observed at necropsy in the right neck area of a 95-week-old female Fischer 344 rat that served as an untreated control animal in a 2-year carcinogenicity study. Formalin-fixed, paraffin-embedded sections of the mass were stained with hematoxylin and eosin along with the immunohistochemical biomarkers lactoperoxidase, catalase, and amylase. Based on its histomorphological and immunohistochemical features, the lesion was diagnosed as a carcinoma of the extraorbital lacrimal gland.

Enhancement of growth of human colon tumor cell lines by feeder layers of murine fibroblasts.

The effects of feeder layers of C3H/10T 1/2 cells on the growth of human and mouse cell lines were tested. Feeder layers increased colony formation by cultured cancerous cells in semisolid medium over controls grown in semisolid medium without feeder layers. Maximal colony formation was also attained at a faster rate when feeder layers were used. Plating efficiency by cancerous cells obtained directly from xenografts was increased threefold to fivefold in tissue culture when feeder cells were present as confluent monolayers.

Heterogeneity of malignant cells from a human colonic carcinoma.

Three subpopulations of malignant cells were isolated from a primary cell culture of a single human colonic carcinoma. The variant cells were established as cell lines designated HCT 116, HCT 116a, and HCT 116b, respectively. In vitro characterizations of the variant lines included growth in 0.5% agarose and growth on confluent layers of mouse fibroblasts. HCT 116a showed the highest colony formation in agarose and on confluent fibroblasts, while colony formation by HCT 116 was higher than that of HCT 116b in both of these systems. All of the variant lines were tumorigenic in athymic nude mice given injections of 10 x 10(6) cells, but the time between inoculation and tumor development (latency period) was approximately 10 times longer for HCT 116b as for HCT 116a and 8 times longer than for HCT 116. HCT 116b was not tumorigenic at an inoculum of 5 x 10(6) cells, while both HCT 116 and 116a were tumorgenic at this level. However, HCT 116a was clearly more tumorigenic than was HCT 116 on the basis of the number of animals developing tumors at inoculate of both 10 x 10(6) and 5 x 10(6) cells and on the basis of their differences in latency periods. While all the cell lines had near diploid numbers of chromosomes, each line showed a distinct histological pattern when grown as xenografts in athymic nude mice.

Initiation and characterization of cultures of human colonic carcinoma with different biological characteristics utilizing feeder layers of confluent fibroblasts.

The tissue culture of human colonic carcinoma with and without feeder layers of confluent C3H 10T1/2 mouse fibroblast was compared. In a series of 27 different tumor specimens, 21 long-term cultures (6 mos. or more) were obtained by utilizing feeder layers. Only 3 long-term cultures were obtained from the same set of specimens when feeder layers were not employed. Several of the long-term cultures were established as cell lines weaned from fibroblast feeder layers. These lines could be classified into 3 groups based upon their expression of several biological properties including tumorigenicity in nude mice, degree of differentiation of the tumors growing in nude mice, growth in semisolid medium, morphology in vitro and production of carcinoembryonic antigen in vitro.

Velocity sedimentation of organelles at low centrifugal force in an isokinetic gradient.

Mast-cell granules and polystyrene microspheres (0.600 and 1.011 micrometer in diameter) were sedimented in a previously described [Pretlow (1971) Anal. Biochem. 41, 248--255] isokinetic gradient in a low-speed centrifuge. For the analytical velocity sedimentation of organelles, this gradient offers several advantages over gradients that are commonly used for the sedimentation of organelles: (a) the density gradient (0.0008 g.ml-1.cm-1) is small, and the effective densities of organelles will change relatively little during sedimentation; (b) the densities at all points in the gradient (1.017--1.027 g/ml) are less than those in gradients commonly used for the sedimentation of organelles, the effective densities of sedimenting organelles are consequently relatively large, and the effect of density as a determinant of velocity of sedimentation is less limiting than in conventional gradients; (c) the small slope of the gradient is associated with a relatively slow increase in the viscosity encountered by the sedimenting organelle; (d) the iso-osmotic gradient is not significantly affected by the gradient medium (Ficoll), and the osmolarity can be adjusted to the desired value by the selection of an appropriate salt solution as the solvent for the Ficoll; (e) the gradient will be isokinetic for particles of densities similar to most organelles. An ultracentrifuge is not required for work with this gradient.