Histopathology of cell mediated immune reaction in mouse colon--allograft rejection

Photothermal effect by 808-nm laser irradiation of melanin: a proof-of-concept study of photothermal therapy using B16-F10 melanotic melanoma growing in BALB/c mice

The photothermal effect is undergoing great interest due to advances in new photosensitizing materials and better-suited light sources, but studies are frequently hampered by the need to employ exogenous photothermal agents and expensive irradiation devices. Here we present a simple strategy based on direct NIR irradiation of the melanin pigment with a commercial 808-nm laser pointer. Proof-of-concept studies showed efficient photothermal effects on melanin in vitro and in vivo. After NIR irradiation, BALB/c mice bearing B16-F10 melanotic melanoma tumors revealed severe histopathological damage and massive necrosis in melanin-containing tumor tissue, while surrounding healthy tissues showed no damage. Therefore, the feasibility of this approach may allow implementing direct procedures for photothermal therapy of pigmented tumors.

Fetal gastric and colonic implants in syngeneic and allogeneic mice developing typical inflammatory changes

Implants of fetal stomach and colon under the kidney capsule of syngeneic, and H-2 compatible and H-2 incompatible allogeneic mice were examined histologically at different time intervals after the procedure. According to the time of implantation typical inflammatory changes were seen in syngeneic stomach and colon implants, which resembled changes seen in chronic atrophic gastritis and chronic ulcerative colitis. Immunofluorescence studies showed that the host developed antibodies against fetal antigens, while there was no evidence for cellular immune response to fetal syngeneic antigens with the direct leukocyte migration inhibition test. Possible explanations for these results are discussed.

Effects of age, antigen deprivation, and allograft rejection on epithelial cell kinetics in mouse colon

A technique of microdissection of colonic mucosa has allowed the study of mitotic activity, measured by metaphase accumulation following colchicine blockade, in individual crypts of mouse colon. The changes occurring during growth and development of normal colon have been studied and compared with changes found in antigen free colon (colonic isografts) and in cell-mediated immune damage of the bowel (allograft rejection). Metaphase accumulation was steady at two metaphases per hour in baby mouse colon until 18 days after birth. Between 18 and 24 days a rapid, and significant increase in mitotic activity occurred (P less than 0.01), reached adult values, and changed no further. Metaphase accumulation in isografts was similar to normal colon for the first two weeks after transplantation but the rise in mitotic activity in the third week did not occur. Allografts of colon showed two- to three-fold increases in metaphase accumulation when compared with both normal colon and isografts (P less than 0.01). When crypt mitotic activity was compared with the length of crypts measured in histological sections of normal colon, isografts, and allografts, no clear relationship was observed. Both changes in the luminal environment of the gut at the time of weaning and cell-mediated immune reactions in the colonic wall appeared to be associated with increased mitotic activity in colonic crypts.