High incidence of nitrosamine-induced tumorigenesis in mice lacking DNA repair methyltransferase

The enzyme O6-methylguanine-DNA methyltransferase repairs alkylation- induced DNA damage, O6-methylguanine and O4-methylthymine, the former being formed more frequently. Previously, by means of gene targeting, we generated mice in which alleles for methyltransferase were disrupted. We now use these mouse lines, which are totally deficient in methyltransferase activity, to examine protective effects of the enzyme against tumor formation. In gene-targeted female mice given an i.p. injection of 5 mg/kg of dimethylnitrosamine, a larger number of liver and lung tumors occurred, as compared with normal female mice treated in the same manner. In male mice given a lower dose of carcinogen, the difference between normal and gene-targeted mice was statistically insignificant although more tumors did form in the gene-targeted mice. Methyltransferase apparently afforded protection from nitrosamine- induced tumorigenesis.      

Initial steroid bolus injection promotes vigorous CD8+ alloreactive responses toward early graft acceptance immediately after liver transplantation in humans.

We have found that steroid bolus withdrawal prior to graft reperfusion increased the incidence of acute cellular rejection (ACR). This study aims to clarify how initial steroid bolus (ISB) injection at reperfusion influences the kinetics of CD8(+) alloreactive immune responses immediately after living donor liver transplantation (LDLT). A total of 49 hepatitis C virus (HCV)-infected recipients were classified into 3 groups according to hierarchical clustering by preoperative CD8(+)CD45 isoforms. The naive T cell proportion was considerably higher in Group I than in Groups II and III, whereas Group II recipients had the highest effector memory (EM) T cells and Group III the highest effector T cells. The frequency of ACR was significantly higher in recipients without ISB than in those with ISB. In particular, the ACR rates were the highest in Group II without ISB. Following ISB, the proportion of effector T cells was promptly upregulated within 6 hours after graft reperfusion, simultaneously with the upregulation of CD27(-)CD28(-) subsets, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha and perforin expression, which significantly correlated with increasing interleukin (IL)-12 receptor beta 1 cells. These were then downregulated to below preoperative levels by tacrolimus (Tac) administered at 24 hours. These changes did not occur in the absence of ISB. In Group II without ISB, the downregulation of IL-12Rbeta1(+) cells was the greatest, consistent with the highest rates of ACR and mortality (60%). In conclusion, ISB must be done in place, especially in Group II with preexisting high EM T cells, to enable the development of early allograft acceptance.     

Carcinoma of the main hepatic duct junction: indications, operative morbidity and mortality, and long-term survival

Carcinoma of the main hepatic duct junction tends to spread extensively along the hepatic ducts into the liver parenchyma. Therefore extensive resection of the bile ducts combined with hepatic resection is the procedure of choice. Between January 1973 and April 1989, 25 of 50 patients with this type of carcinoma underwent resection, a resectability rate of 50%. One patient died of staphylococcal sepsis on the postoperative day 42 after right trisegmentectomy and resection of the bile ducts, a hospital death rate of 4%. Twenty-four patients were discharged from the hospital. The 5-year actuarial survival rate calculated by the Kaplan-Meier method was 19%. Four patients lived longer than 5 years after surgery; the longest survival was 9 years after right trisegmentectomy and resection of the bile ducts. These four patients had clear margins at the resected bile ducts. This article was designed to clarify the point at issue by presenting our results in terms of indications, operative morbidity and mortality, and long-term survival.     

Binding of Clostridium botulinum type C neurotoxin to different neuroblastoma cell lines.

Binding of type C neurotoxin (C1 toxin) from Clostridium botulinum (strain Stockholm) to neuroblastoma cell lines was studied by using biotinylated anti-toxin antibody and avidin-biotinylated peroxidase complex. The neurotoxin bound with high efficiency to mouse neuroblastoma (NS-20Y and NIE-115) cells and to hybridomas of rat glioblastoma and mouse neuroblastoma (NG108-C15) cells. The toxin bound little to human neuroblastoma, rat astrocytoma, and nonneural cell lines. Binding of the neurotoxin to NG108-C15 cells was inhibited by gangliosides (GT1b and GM1) and by monoclonal antibodies (CA-12 and C-9), although inhibition was not complete. Sequential preincubation of C1 toxin with GT1b and CA-12 caused complete inhibition. A Scatchard plot of binding of 125I-labeled C1 toxin to NG108-C15 cells showed a hyperbolic curve. Monoclonal antibody CA-12 but not C-9 neutralized the lethal activity of the toxin toward mice. Only C-9 clearly inhibited toxin binding to GT1b. These results suggest that NG108-C15 cells have at least two kinds of receptors for C1 toxin. From the results of binding tests with neuraminidase-, pronase-, and trypsin-treated NG108-C15 cells, the chemical nature of the high-affinity site was presumed to be a glycoprotein containing sialic acid. GT1b may have an important role in low-affinity sites.     

Disseminated intravascular coagulation after hepatic resection

Disseminated intravascular coagulation (DIC) after hepatic resection is a serious complication that leads to a fatal outcome unless prompt treatment is instituted. Between April 1973 and June 1988, DIC occurred postoperatively in 18 of 192 patients who underwent hepatic resection because of a variety of diseases of the liver and biliary tract. The diagnosis was made on the basis of changes in platelet count, fibrinogen level, serum level of fibrin degradation product (FDP), and protamine sulfate test. Heparin was used in an earlier series but has been discontinued because of difficulty in determining the optimal dose in patients undergoing liver resection. Instead, we now use gabexate mesilate, which blocks the coagulation cascade without the aid of antithrombin III and works as an anticoagulant. Fifteen patients had uneventful recoveries, but three died. Two died of aggravation of DIC, which was a result of reoperation performed under the diagnosis of surgical bleeding. The other patient died of liver failure after fever of unknown cause persisted for 4 months. The rationale for the diagnosis and treatment of DIC after liver resection is documented, and the problems involved are discussed.     

A case report of multiple-transfused aplastic anemia complicated by hemolysis and delayed neutrophil recovery after bone marrow transplantation]

The authors report an 18-year-old female who developed severe hemolytic reaction and delayed neutrophil recovery after bone marrow transplantation (BMT) for aplastic anemia from her HLA-identical sibling. She had received much transfusion (61 units of red blood cells including 4 units of fresh whole blood from her parents and 350 units of platelets) for 12 years before BMT. To prevent graft rejection, she received an intensified preparative regimen consisted of cyclophosphamide 200 mg/kg followed by 5 Gy total body irradiation and 5 Gy total lymphoid irradiation. Prophylaxis for GVHD was short term methotrexate and cyclosporin-A. Despite of the removal of the red cells from the marrow, marked hemolytic reaction caused by antibodies directed to rh" (E) and hr' (c) red cell antigens was observed when rh" (E) and hr' (c) positive donor erythroid began to recover. The recovery of neutrophils, especially the fraction of segmented cells was also delayed. Flow cytometry showed that the serially collected patient's sera reacted to neutrophils derived from both patient's blood on the 64th post-transplant day and the donor's blood. The reactivity was strongest in pre-BMT sera. We conclude that residual antibodies sensitized before BMT are a major cause of these hematological problems.     

Chymase participates in chronic dermatitis by inducing eosinophil infiltration

An epicutaneous application of 2,4-dinitrofluorobenzene (DNFB) to a mouse ear caused a transient skin swelling, and the repetition of the challenge enlarged the contact dermatitis. The repeated challenge with DNFB also induced eosinophil infiltration on the application site. Administration of a chymase inhibitor significantly inhibited the ear swelling as well as eosinophil accumulation. An intradermal injection of human chymase to the mouse ear also elicited transient skin swelling and eosinophil infiltration, both of which were augmented in proportion to the number of injections. Human serum albumin and heat-inactivated chymase failed to induce such skin reactions, suggesting the participation of proteolytic activity of the enzyme. In addition, chymase stimulated eosinophil migration in vitro in a concentration-dependent manner. Taken together, these observations suggest that mast cell chymase may contribute to development of the DNFB-induced dermatitis, probably by promoting eosinophil infiltration. It is therefore possible that chymase plays a role in pathogenesis of chronic dermatitis such as atopic dermatitis.     

An ambulatory respirometer (Hotmate) as a tool for screening of sleep apnea syndrome

The gold standard diagnostic method for sleep apnea syndrome(SAS) is overnight polysomnography(PSG), but is costly in terms of time and money. We studied the usefulness of a 24-hour ambulatory respirometer equipped with oximeter(Hotmate) for screening of SAS. Seventy-six cases of suspected SAS were enrolled(68 males and 8 females, mean age 51). The correlation between data from Hotmate and PSG was evaluated in 24 cases who underwent both of the tests for the final diagnosis of SAS. There was a good correlation between the two parameters of the data obtained by Hotmate(H) (H-apnea index(AI) vs H-desaturation index(DI)). Among 24 cases who underwent both Hotmate and PSG, there was a good correlation between the data from PSG and Hotmate(PSG-AI vs H-AI: r = 0.80, p < 0.001). Both sensitivity and specificity were highest when screening criteria of H-DI > 15 was utilized(sensitivity = 91.7%, specificity = 66.7%). Our findings suggest that the respiromonitor with oximeter is useful for the screening the patients with SAS.