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PubMed1995

Role of adjuvant therapy in surgically resected colorectal carcinoma.

An important advance in cancer treatment has been made in recent years with the finding that adjuvant therapy can significantly improve the survival of patients with colorectal cancer. In patients with resected lymph node-positive colon carcinomas (TNM stage 3), adjuvant 5-fluorouracil and levamisole produced an unequivocal survival advantage that established this combination as the standard of clinical practice. Given that biochemical modulation of fluorouracil by leucovorin can increase response rates in advanced disease, this combination is undergoing evaluation as an adjuvant treatment. Preliminary results indicate that 5-fluorouracil and leucovorin are effective in reducing disease relapse; however, the effect of this regimen on patient survival rates awaits extended follow-up. In the treatment of stages 2 and 3 rectal cancer, significant reductions in local recurrence and death rates have been achieved with the combination of 5-fluorouracil and radiation therapy. Immunologic approaches and newer chemotherapeutic agents may further improve patient outcome and are under investigation, as are efforts to reduce the toxic effects of cancer chemotherapy. Increased understanding of the biology of these diseases is likely to yield prognostic markers capable of identifying subgroups of earlier stage patients at high risk of disease relapse who may also benefit from adjuvant therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Influence of ionizing radiation on crotoxin: biochemical and immunological aspects.

Irradiation of crotoxin and its subunits with 2000 Gy of gamma-rays from 60Co source leads to aggregation and generation of lower mol. wt breakdown products. Aggregates separated by gel filtration retain at least part of their higher-ordered structure, based on their reactivity with monoclonal antibodies known to react with conformational epitopes in native crotoxin. These same aggregates can serve as antigens to raise antisera that cross-react and neutralize crotoxin. Compared with native crotoxin, aggregates appear less myotoxic, are largely devoid of phospholipase activity, and are virtually non-toxic in mice. These results indicate that irradiation of toxic proteins can promote significant detoxification, but still retain many of the original antigenic and immunological properties of native crotoxin.

Animals↗
PubMed1992

Simultaneous analysis of chromosome damage and aneuploidy in cytokinesis-blocked V79 Chinese hamster lung cells using an antikinetochore antibody.

A modified antikinetochore antibody technique was established in the V79 Chinese hamster lung cells to simultaneously analyze chromosome damage and aneuploidy induced by various agents. The method involved sequential treatment of slides with crest serum, fluoresceinated goat-antihuman and swine-antigoat antibodies, and propidium iodide. In this method, cytoplasm (green), nuclei or micronuclei (red), and kinetochores (yellow), are identified using the same filter setting under blue excitation (440-490 nm) with a barrier filter at 520 nm. Using this method, three agents, vinblastine (VB), X-rays, and methyl methanesulfonate (MMS) were tested for micronucleus/aneuploidy induction. An aneugen, VB and a clastogen, X-rays, induced predominantly kinetochore positive (K+) and negative (K-) micronucleated binucleate (MNBN) cells, respectively, in a dose-dependent fashion. An alkylating agent, MMS, produced both K+ and K- MNBN cells. These results are comparable with the results reported in the literature on these compounds using various methods and thus demonstrate the usefulness of this assay in distinguishing clastogenicity from aneugenicity.

Aneuploidy↗
PubMed1997

Tying loose ends: roles of Ku and DNA-dependent protein kinase in the repair of double-strand breaks.

A convergence of information from biochemistry, yeast and mammalian genetics, immunology, and radiation biology has permitted identification of some of the protein participants - Ku, DNA-PK, XRCC4 - and the reaction intermediates in DNA end joining, suggesting how broken chromosomal ends may be recognized and repaired in eukaryotic cells. Some components may be defective in inherited disorders.

Animals↗
PubMed1974

Protection of lethally irradiated mice by spleen cells from neonatally thymectomized mice.

Long-lived, immunologically vigorous (C3H(f) x A(f))F(1) hybrids were produced after lethal irradiation by administration of spleen cells from C3H(f) or syngeneic donors. Further, neonatally thymectomized C3H(f) or A(f) strain donors reconstituted irradiated C3H(f) or (C3H(f) x A(f))F(1) hosts. In addition, C3H(f) spleen cells from nonthymectomized 10- to 15-day-old donors protected irradiated hybrid mice, but A(f) cells of young mice as well as of older mice produced graft-versus-host reaction and early death in irradiated C3H(f) or (C3H(f) x A(f))F(1) hybrids. Abrogation of secondary disease by treatment of irradiated mice with spleen cells from allogeneic neonatally thymectomized mice is possibly attributable to diminished immunologic competence of the cells grafted, followed by the development of immunological tolerance of the donor cells. Donor cells, receiving thymus influence in the recipient host after transplantation, could explain the long-lived immunologically vigorous radiation chimeras that did not experience graft-versus-host reactions. The findings of this study help to understand the differential susceptibility of A(f) and C3H(f) mice to development of tolerance to one another's antigens observed in prior investigations. It appears that, in these mice, the host thymus influences the maturation of the spleen cells from young mice or from neonatally thymectomized mice. However, this influence was often greater in mice given 767 rads than in those given 1046 rads. This differential influence is possibly attributable to irradiation damage to the thymus produced by the higher dose of irradiation. Spleen cells from neonatally thymectomized mice can be differentiated and expanded by the thymus of the host. The differential susceptibility of T(1), early differentiation stages, of thymus-dependent lymphocytes and T(2), late differentiation stages, of thymus-dependent lymphocytes to tolerance induction and immunostimulation, respectively, are proposed as the bases for these otherwise paradoxical influences.

Animals↗
PubMed1964

STUDIES ON ANTIBODY PRODUCTION X. MODE OF FORMATION OF PLASMOCYTES IN CELL TRANSFER EXPERIMENTS.

Cells from lymph nodes of rabbits injected repeatedly with bovine serum albumin were transferred subcutaneously to previously irradiated rabbits, and the recipients were immediately injected with bovine serum albumin. A good antibody response resulted. In a series of such animals killed on successive days, skin samples at sites of cell deposition were removed and examined by immunofluorescence and by light microscopy. In these tissues abundant plasmocytes were found to have multiplied and differentiated in a regular progression from immature, to medium, to mature plasmocytes. During the 6 days of the experiment the small plasmocytes accumulated until they reached 85 per cent of the total plasmocytic population. The mitotic index of the large and medium plasmocytes averaged 11 per cent, implying a generation time of 6.3 hours on the basis of a 1 hour mitotic time. This rate of growth is sufficiently rapid to account for all the plasmocytes on the 6th day as deriving from less than 1 per cent of the population initially transferred. This rate and the orderly progression in the evolution of the plasmocytic population, make it highly improbable that plasmocytes arise from transformation of lymphocytes, but rather indicate that they spring from specific precursors already present among the transferred cells.

Animals↗