Acta Medica Okayama volume44 issue4

Neural regulation of the motility between the haustra and taenia coli was studied in the isolated rabbit proximal colon. Four types of haustral and taenial preparations were used: the haustral strip without the taenia coli (type 1), the haustral strip including the taenia coli (type 2), the L-shaped (taenia-haustra) preparations for recording the haustral (circular) response to taenial stimulation (type 3) and the L-shaped (haustra-taenia) preparation for recording the taenial (longitudinal) response to haustral stimulation (type 4). Field electrical stimulation induced a contractile response in the haustra and taenia coli. Hexamethonium reduced the contraction in type 2, 3 and 4 preparations. The desensitization to serotonin reduced the response in type 2 and 3 preparations. After atropinization, the response in types 1 and 4 was reversed to relaxation, and the response in types 2 and 3 was reversed to relaxation followed by contraction which was reduced or abolished by indomethacin. The responses remaining after atropinization in all types of preparations were not affected by other blocking agents tested or desensitization to neuropeptides. Tetrodotoxin abolished all relaxation and contractile responses in all types of preparations. These results suggest that the indirect contractile response to field stimulation is induced mainly via cholinergic and serotonergic neurons, and that the relaxation is mainly mediated by nonadrenergic noncholinergic neurons. The late haustral contractions after atropine may be caused by endogenous prostaglandin.

We examined the effect of fetal calf serum (FCS) on meiotic division, subsequent fertilization, and first cleavage to the 2-cell stage of rat oocytes during in vitro maturation. FCS had no effect on the nuclear progression from dictiate to metaphase of the second maturation in vitro and, FCS had no effect on the first cleavage to the 2-cell stage of fertilized oocytes. However, FCS efficiently increased penetration rate of oocytes and shortened the time required for dissolution of the zona pellucida by alpha-chymotrypsin. These results showed that FCS did not affect cytoplasmic maturation necessary for oocytes to develop to the 2-cell stages. We found that FCS only affects the zona pellucida and does not affect the nucleus or cytoplasm of rat oocytes. FCS may prevent hardening of the zona pellucida.

Ki-67 is a commercially available mouse monoclonal antibody (MoAb), which reacts with a nucleolar antigen (the Ki-67 antigen) expressed in proliferating eukaryotic cells. The author examined the precise localization of the Ki-67 antigen in C-6 cells using immunohistochemical and immunoelectron microscopic methods and estimated the proliferative activity of human brain tumors in situ. Positive nucleoplasmic reactions (early G1 phase) and nucleolar staining (late G1 phase) were observed. The cells showed very weak positive reactions in only one or two nucleoli (S phase) and multiple spicule reactions in the nucleoplasm (G2 phase). During the mitotic phase, the Ki-67 antigen was stained on the surfaces of all chromosomes and finely dispersed in the cytoplasm. By immunoelectron microscopic study, positive reactions were observed on the granular and dense fibrillar components. Therefore, the Ki-67 antigen seems to participate in the processing and assembly of preribosomal particles. In human brain tumors, the Ki-67 score (positive cells/total neoplastic cells), ranging 0 to 36.7%, correlated well with the histopathological grade of malignancy of the tumor. These findings suggest that immunohistochemical staining with the MoAb Ki-67 can be used as a convenient procedure for the simple evaluation of the proliferative activity of brain tumors.

Carbohydrate metabolism of rats with obstructive jaundice caused by bile duct ligation was studied by intravenous glucose tolerance test (IVGTT) and by liver perfusion. The altered levels of carbohydrate-metabolizing enzyme were examined in relation to the glucose metabolism of the cholestatic rats. In the IVGTT, the rate of fractional glucose removal was increased with increases in plasma insulin and glucagon and with a decrease in non-esterified fatty acid. In liver perfusion, neither the glucose uptake nor insulin extraction by the whole liver of icteric rats was different from the control. The increased rate of glucose removal in IVGTT may be due to enhanced glucose utilization by peripheral tissues resulting from hypersecretion of insulin. In liver perfusate supplemented with glucose, a decrease in the glucose uptake per unit liver weight was observed in relation to the lowered glucokinase activity. Formation of glycogen from glucose and of glucose from lactate was also impaired, indicating inhibition of the gluconeogenic system or relative hyperfunction of the glycolytic system, which may further contribute to the reduction in glycogen content. These metabolic disorders correlated well with the changes in activities of key carbohydrate-metabolizing enzymes, which showed a characteristic pattern consistent with the loss of differentiated hepatic functions. Uptake of glucose and its conversion to glycogen were reduced in the cholestatic liver in close association with altered activities of some of related enzymes. However, due to increased utilization by the peripheral tissues, the total amount of glucose utilized in the whole rat was not reduced.

To prevent the development of hepatic metastases after surgery for colorectal cancer, it is important to inhibit the growth of any micrometastases which occur during the operation. We used a hepatic metastasis model in mice to investigate the effects of combination therapy with natural human tumor necrosis factor-alpha (nHuTNF-alpha) and natural murine interferon-alpha/beta (nMuIFN-alpha/beta). Decreased formation of hepatic metastases by murine colon-26 carcinoma was recognized following a single injection of nHuTNF-alpha, nMuIFN-alpha/beta, or both. These inhibitory effects were synergistic. NK activity was also measured, because notaral lerller cells not only have an anti-tumor effect but are also a representative of the host immune system. Both nHuTNF-alpha and nMuIFN-alpha/beta were able to activate NK cells, and the combination of the cytokines more significantly augmented NK activity. The in vivo elevation of NK activity induced by nHuTNF-alpha, nMuIFN-alpha/beta, or their combination may be one of the mechanisms of their antiproliferative effect on experimental hepatic metastases of murine colon-26 carcinoma.