Cytokines secreted by lymphokine-activated killer cells induce endogenous nitric oxide synthesis and apoptosis in DLD-1 colon cancer cells

IL-2-activated killer lymphocytes (LAK cells) secrete inflammatory cytokines such as interferon-gamma (IFN-gamma) and tumor necrosis factor alpha (TNFalpha) that can induce nitric oxide (NO) synthesis. We evaluated whether LAK cells could activate NO synthesis in human cancer cells. LAK cells and their culture supernatants induced NO synthesis in DLD-1 colon cancer cells in a dose-dependent manner. NO synthesis was inhibited completely by blocking antibodies to IFN-gamma, demonstrating a key role for this LAK cell cytokine in regulating NO synthesis. The addition of TNFalpha antibodies resulted in partial inhibition. Induction of iNOS mRNA and protein expression in DLD-1 cells was detected. Endogenous NO production inhibited DLD-1 cell proliferation and induced apoptosis, processes that were inhibitable by the NO synthase inhibitor N(G)-monomethyl-l-arginine. Our study has identified a novel, non-contact-dependent LAK cell cytotoxic mechanism: induction of growth inhibition and programmed cell death due to endogenous NO synthesis in susceptible human cancer cells.     

Localization and topology of ratp28, a member of a novel family of putative steroid-binding proteins

We have cloned ratp28, a membrane protein from rat liver homologous to the previously described hpr6.6, a putative steroid-binding protein in humans. Ratp28 has a type II topology as determined by protease digestion experiments on intact and detergent-solubilized membranes. Subcellular fractionation by sucrose density centrifugation revealed a distribution for ratp28 identical to Bip as a marker for membranes of the endoplasmic reticulum. In these experiments no association was found with markers for Golgi or plasma membranes, indicating that ratp28 is localized to the endoplasmic reticulum.     

Retroviral expression of the hepatitis B virus x gene promotes liver cell susceptibility to carcinogen-induced site specific mutagenesis

Mutational inactivation of the tumor suppressor gene p53 is common in hepatocellular carcinomas (HCC). AGG to AGT transversion in codon 249 of exon 7 of the p53 gene occurs in over 50% of HCC from endemic regions, where both chronic infection with the hepatitis B virus (HBV) and exposure to carcinogens such as aflatoxin B1 (AFB1) prevail. In this study, we report the effect of the HBV x protein (HBx) on carcinogen-induced cytotoxicity and AGG to AGT mutation in codon 249 of the p53 gene in the human liver cell line CCL13. Expression of HBx, as revealed by its transactivation function, results in enhanced cell susceptibility to cytotoxicity induced by the AFB1 active metabolite, AFB1-8,9-epoxide, and benzo(a)pyrene diol-epoxide. Under similar conditions, expression of HBx promotes apoptosis in a subset of cell population. Exposure to AFB1-8, 9-epoxide alone induces a low frequency of AGG to AGT mutation in codon 249 of the p53 gene, as determined by an allele-specific polymerase chain reaction (AS-PCR) assay. However, expression of HBx enhances the frequency of AFB1-epoxide-induced AGG to AGT mutation compared to control cells. In summary, this study demonstrates that expression of HBx enhances liver cell susceptibility to carcinogen-induced mutagenesis, possibly through alteration of the balance between DNA repair and apoptosis, two cellular defense mechanisms against genotoxic stress.     

The first human case of Trichinella spiralis infection in Korea

Three cases of human infection by Trichinella spiralis were first confirmed by detecting encysted larvae in the biopsied muscle in December 1997, in Korea. The patients were one 35- and two 39-year-old males residing in Kochang-gun, Kyongsangnam-do. They had a common past history of eating raw liver, spleen, blood and muscle of a badger, Meles meles melanogenys, and complained of high fever, facial and periorbital edema, and myalgia. Hematologic and biochemical examinations revealed leukocytosis and eosinophilia, and highly elevated levels of GOT, GPT, LDH and CPK. In the gastrocnemius muscle of a patient, roundly coiled nematode larvae were detected. The larvae measured 0.775-1.050 (av. 0.908) mm in length, and 0.026-0.042 (av. 0.035) mm in maximum width. The specific IgG antibody levels in three patients' sera were significantly higher when compared with those of normal controls. The patients were treated with flubendazole and albendazole for 15-30 days, and discharged at 13-34 days post-admission. From the above findings, it was confirmed that T. spiralis is present in Korea, and the badger plays a role of as the natural host.     

Infection status with trematode metacercariae in pond smelts, Hypomesus olidus

Many Koreans usually eat raw pond smelts, Hypomesus olidus, in the winter. This study was performed to evaluate the infection status with trematode metacercariae in pond smelts from January 1998 through February 1999. Among 1,305 fish collected, 459 were purchased from wholesale dealers in Chinchon-gun, Chungchongbuk-do, and the rest of them were caught with a casting net in Soyangho (Lake), Taehoman (Bay) and Paekkokchosuchi (Pond). Seven species of trematode metacercariae including two unidentified ones were detected from 1,305 pond smelts. The number of detected trematode metacercariae according to the species are as follow: Clonorchis sinensis 8, Holostephanus nipponicus 7, Cyathocotyle orientalis 24, Diplostomum sp. 14, and Metorchis orientalis 7. From the above results, it was confirmed that H. olidus plays a role as the second intermediate host of some kinds of trematode including C. sinensis in Korea. Our report shows possible clonorchiasis caused by eating raw pond smelts.     

Do Leptin Levels Predict Weight Gain?—A 5-Year Follow-Up Study in Mauritius

Objective : To investigate whether relative baseline leptin levels predict long-term changes in adiposity and/or its distribution. Research Methods and Procedures : In a longitudinal study of 2888 nondiabetic Mauritians aged 25 years to 74 years who participated in population-based surveys in 1987 and 1992, changes in body mass index (BMI), waist/hip ratio (WHR), and waist circumference were compared between “hyperleptinemic,” “normoleptinemic,” and “hypoleptinemic” groups. “Relative leptin levels” were calculated as standardized residuals from the regression of log₁₀ leptin on baseline BMI to provide a leptin measure independent of BMI. Analyses were performed within each sex. A linear regression model was used to assess the effect of standardized residuals on changes in BMI, WHR, and waist circumference, independent of baseline BMI, age, fasting insulin, and ethnicity. Results : After adjusting for age and baseline BMI by analysis of covariance, there was no difference in changes in BMI, WHR, or waist circumference between men with low, normal, or high relative leptin levels. Among women, there was a significant difference in ΔWHR across leptin groups, such that the largest increase occurred in the “normal” leptin group. For both men and women, the linear regression models explained ?10% of variation in dependent variables, and the only significant independent variables were age, BMI, and being of Chinese origin, compared with Indian origin. Discussion : These findings do not support a role for leptin concentration in predicting weight gain or changes in fat distribution in adults over a 5-year period.     

Components of the Plasminogen Activation System Promote Engraftment of Porous Polyethylene Biomaterial via Common and Distinct Effects

Rapid fibrovascularization is a prerequisite for successful biomaterial engraftment. In addition to their well-known roles in fibrinolysis, urokinase-type plasminogen activator (uPA) and tissue plasminogen activator (tPA) or their inhibitor plasminogen activator inhibitor-1 (PAI-1) have recently been implicated as individual mediators in non-fibrinolytic processes, including cell adhesion, migration, and proliferation. Since these events are critical for fibrovascularization of biomaterial, we hypothesized that the components of the plasminogen activation system contribute to biomaterial engraftment. Employing in vivo and ex vivo microscopy techniques, vessel and collagen network formation within porous polyethylene (PPE) implants engrafted into dorsal skinfold chambers were found to be significantly impaired in uPA-, tPA-, or PAI-1-deficient mice. Consequently, the force required for mechanical disintegration of the implants out of the host tissue was significantly lower in the mutant mice than in wild-type controls. Conversely, surface coating with recombinant uPA, tPA, non-catalytic uPA, or PAI-1, but not with non-catalytic tPA, accelerated implant vascularization in wild-type mice. Thus, uPA, tPA, and PAI-1 contribute to the fibrovascularization of PPE implants through common and distinct effects. As clinical perspective, surface coating with recombinant uPA, tPA, or PAI-1 might provide a novel strategy for accelerating the vascularization of this biomaterial.