Paradoxical effect of cytosine arabinoside on mouse leukemia cell line L1210 cells

We investigated the effects of 1-beta-D-arabinofuranosylcytosine (ara-C) on the growth of murine leukemic L1210 cells, which were cultured with high (2.0 x 10(3) ng/ml), middle (100 ng/ml) and low doses (5.0 ng/ml) of ara-C. In the analysis by flow cytometry, high dose ara-C arrested the cell cycle in the G0/G1-phase. Middle and low doses ara-C induced a block in the S-phase, that was not completely blocked by the low dose. Analysis of DNA fragmentation revealed that ara-C dose-dependently induced apoptosis, which was only slightly induced by the low dose. We measured activities of cellular thymidylate synthase (TS) and thymidine kinase (TK) after 24-h culture. Low and middle doses, but not high dose ara-C markedly enhanced TS activity to 2.9- in low and 5.3-fold in middle doses ara-C, and TK activity to 1.3- in low and 2.2-fold in middle doses, respectively, compared with those of the control. The cells accumulated in the S-phase by 48-h culture with low dose ara-C and markedly proliferated compared to that of the control in ara-C-free medium. These results indicate that non-high dose ara-C enhances DNA-synthesizing enzyme activities in L1210 cells, and withdrawal of the non-high dose ara-C results in paradoxical cell proliferation. Thus, daily intramuscular injections with an insufficient dose of ara-C may induce cells into S-phase, resulting in the proliferation of leukemic cells.

The usefulness of 2-nitroimidazole-sodium borocaptate-10B conjugates as 10B-carriers in boron neutron capture therapy

We evaluated the usefulness of five new (10)B-compounds (TX-2016, TX-2017, TX-2018, TX-2041, and TX-2042) as (10)B-carriers in boron neutron capture therapy (BNCT). They are 2-nitroimidazole-sodium borocaptate-(10)B (BSH) conjugates, that is, hybrid compounds that have both hypoxic tumor cell sensitizing unit under gamma-ray irradiation, 2-nitroimidazoles, and thermal neutron-sensitizing unit, BSH. (10)B distribution analyses in tumors and blood indicated that TX-2041 has the most favorable characteristics for localizing a sufficient amount of (10)B into tumors and keeping the (10)B concentration high during neutron beam irradiation. In addition, TX-2041 showed a significantly higher radio-sensitization effect with reactor thermal neutron beams than BSH on both total (=proliferating (P) + quiescent (Q)) and hypoxia-rich Q cell populations in solid tumors. Further, TX-2041 clearly demonstrated a radio-sensitization effect with gamma-rays on both cell populations, which could never be achieved by BSH. (10)B-carriers with a hypoxic tumor cell-sensitizing effect on tumors with gamma-rays as well as the potential to selectively localize and keep (10)B in tumors, such as TX-2041, are promising for use in actual BNCT.

[Successful staged repair of a symptomatic neonate of tetralogy of Fallot with severe absent pulmonary valve syndrome]

Tetralogy of Fallot with absent pulmonary valve has been classified to a few groups. The most severe one is characterized by symptomatic onset immediately after birth. The others are no or slightly symptomatic at least during their neonatal period. In a severely symptomatic 12-day-old neonate of tetralogy of Fallot with absent pulmonary valve who had required intubation immediately after birth, tight pulmonary banding and left side modified Blalock-Taussig shunt were performed on emergency basis. Consequently, prior massive pulmonary regurgitation was decreased significantly. Forty-five days after this first stage operation, he weaned from respiratory management. At 1-year-old, radical repair based on conotruncal repair, which consisted of patch closure of ventricular septal defect preserving the tricuspid septal leaflet function, resection of anterior wall of enlarged left pulmonary artery, and right ventricular outflow tract reconstruction using autologous tissue and a pericardial patch was performed. Bicuspid pulmonary valve, posterior one of procured autologous pulmonary wall and anterior one of polytetrafluoroethylene (PTFE) respectively, was created to minimize deterioration of the pulmonary insufficiency. Although postoperative cardiac function was kept feasible showing his central venous pressure of 7 mmHg in the main, postoperative general course was eventful especially regarding the respiratory function. The patient was weaned from the prolonged ventilator management 5 months after this radical repair eventually. Generally, to diminish the massive pulmonary regurgitation in early lifetime period could reduce a progressive airway obstruction and minimize pulmonary tissue damage. However, even after the total correction in this case, considerable peripheral segmental pulmonary obstructive lesions were persistent according to the perfusion lung scanning with 99mTc macroaggregated albumin and 99mTechnegas ventilation lung scanning studies. This persistent, supposed to be innate, pulmonary obstructive lesions might prevent ordinal recovery after cardiac radical repair for this most severe subtype of absent pulmonary valve syndrome.

Probucol, a hypocholesterolemic agent, prevents the development of uterine adenomyosis induced by pituitary grafting in mice

This in vivo experimental study was designed to investigate the effects of probucol, a hypocholesterolemic agent, on uterine adenomyosis which is frequently induced by pituitary grafting in mice. SHN mice, which are known to develop uterine adenomyosis spontaneously, and much sooner after pituitary grafting, were used and histopathological study on the uteri in pituitary gland-implanted mice with or without probucol treatment was performed. Four out of 10 pituitary gland-implanted mice developed uterine adenomyosis with dilated blood vessels, but none of the probucol-treated mice. There were no differences between pituitary-grafted mice with or without probucol treatment in body weight and wet weights of uterus, ovaries, kidney and liver except spleen. Probucol markedly reduced the serum levels of total cholesterol, free cholesterol, free fatty acids, phospholipids and triglycerides and, thus, this agent inhibited the incidence of uterine adenomyosis induced by pituitary grafting in mice.

Natural IgM antibodies in sera from various animals but not the cat kill Toxoplasma gondii by activating the classical complement pathway

Sera from swine, rabbit, and dog, that had never been exposed to Toxoplasma gondii, demonstrated significant killing of T. gondii tachyzoites in vitro, while cat serum did not. Swine and rabbit sera contained natural IgM antibody against the tachyzoites, and the classical complement pathway was activated by the binding of natural IgM antibody to the tachyzoites, leading to lysis. Anti-T. gondii antibodies, induced in swine or cat infected with T. gondii, had no killing effect by themselves but killed the tachyzoites in the presence of swine complement. However, the anti-T. gondii antibodies of swine or cat demonstrated a very low killing effect in the presence of cat complement. This suggests that T. gondii tachyzoites have an evasion mechanism to prevent lysis which is specific for cat complement.

SAG1 Is a Host-Targeted Antigen for Protection against Toxoplasma gondii Infection

We previously reported that SAG1 transgenic (tg) mice have an elevated susceptibility resulting from their inability to elicit strong Th1-based protection against Toxoplasma gondii infection. Here, we demonstrate that SAG1 tg mice were protected against T. gondii infection, characterized by a decline in IFN-gamma levels, following administration of a lethal dose of T. gondii. Moreover, immunization with T. gondii homogenate conferred protection and induced production of IgG, with IgG1 and IgG2a subclasses driven by Th2 and Th1 responses, respectively, in both SAG1 tg and wild-type (wt) mice. IgG titers were significantly higher from day 10 after immunization in wt mice compared to those in SAG1 tg mice. There were no significant differences observed in levels of IgG1 in both groups. However, significantly lower IgG2a titers were measured in the sera from SAG1 tg mice on days 10, 15 and 20. IFN-gamma levels in sera were significantly lower in SAG1 tg mice compared to those in wt mice on day 20 after immunization. When challenged with a lethal dose of the Beverley strain of T. gondii, 80 and 100% survival rates were observed in SAG1 tg and wt mice, respectively, indicating that SAG1 tg mice were protected to a lesser extent from challenge due to the decrease in protective immunity. These results suggest that SAG1 plays a critical role in eliciting protection, hence a target antigen for the development of protective Th1-based responses against T. gondii infection in mice.

Unresponsiveness to surface antigen 1 modifies cytokine profiles in acute Toxoplasma gondii infection

Resistance to Toxoplasma gondii involves the development of a highly polarized Th1-type cytokine expression. SAG1 transgenic mice are highly susceptible to T. gondii infection due to their non-reactivity to SAG1 of the protozoan parasite. Here we describe cytokine profiles during the acute phase of T. gondii infection, which are associated with the susceptibility of SAG1 transgenic mice. SAG1 transgenic mice showed a 4.5-fold increase in susceptibility upon inoculation with a sublethal dose of the Beverley strain of T. gondii compared to their wild-type counterparts (mortality: 81 vs. 18%, respectively). When analysis of the most important cytokines involved in the mediation of resistance to infection was carried out, SAG1 transgenic mice exhibited low production levels of IL-12, IFN-gamma and TNF-alpha in sera during the acute phase of T. gondii infection. Antibody and T cells specific for SAG1 were not mounted upon SAG1 stimulation in SAG1 transgenic mice. Moreover, in vitro studies indicated that in SAG1 transgenic mice IFN-gamma and IL-12 production was lower than in their wild-type counterparts, although levels of TNF-alpha increased in SAG1 transgenic mice on day 9 after infection. Low IgG2a levels were detected in SAG1 transgenic mouse sera. Unresponsiveness to SAG1 of T. gondii renders SAG1 transgenic mice unable to develop a strong Th1-based protection against T. gondii infection. These results provide evidence that SAG1 is a pivotal antigen involved in the induction of immune responses towards the development of Th1-protective immunity during T. gondii infection.

Peyer's patches: organized lymphoid structures for the induction of mucosal immune responses in the intestine

Peyer's patches (PP) comprise transmucosal clusters of lymphoid follicles overlaid with a specialized lympho-epithelium and consequently play a central role in the induction of mucosal immune responses in the gut. Despite considerable achievements in the last 3 decades, in our understanding of how PP are involved in the induction of immune responses, much remains to be learned about these major organized lymphoid organs. The history and current status of PP termed 'the major inductive site of immune responses' is reviewed. The present understanding of PP biology and function, taking into account their preferential and unique retention of immune competent cells at specific sites, is discussed.

Protective effect of urinary trypsin inhibitor on myocardial mitochondria during hemorrhagic shock and reperfusion

OBJECTIVE

To examine the mitochondrial function in the myocardium after hemorrhagic shock and reperfusion and to evaluate the protective effect of urinary trypsin inhibitor (UTI) on mitochondria.

DESIGN

Animal experiment.

SETTING

University research laboratory.

SUBJECTS

Wistar rats receiving 50,000 units/kg/hr of UTI (n = 27; UTI group) and control rats (n = 26; control group).

INTERVENTIONS

Rats were subjected to low-perfusion ischemia with the left ventricular systolic pressure maintained at 50 mm Hg for 60 mins by bleeding, followed by a 60-min reperfusion by transfusion of shed blood. UTI was infused continuously from 10 mins before bleeding. Cardiac function was measured before bleeding, after bleeding, and after transfusion; at each determination point, the myocardial contents of adenosine triphosphate (ATP), creatine phosphate (P-Cr), pyruvate (Pyr), and lactate (Lac) were measured enzymatically. The cytosolic phosphorylation potential (PP) as well as the redox potential of the oxidized form of nicotinamide adenine dinucleotide/reduced form of nicotinamide adenine dinucleotide couple in mitochondria (Eh(NAD+/NADH)) and change of Gibbs free energy in ATP hydrolysis (deltaG(ATP hydrolysis) energy) were calculated.

MEASUREMENTS AND MAIN RESULTS

Cardiac function decreased during hemorrhagic shock but improved significantly in the UTI group after transfusion compared with the control group. Lac and the Lac/Pyr ratio were significantly lower in the UTI group than in the control group after transfusion. ATP and P-Cr were significantly higher in the UTI group than in the control group after transfusion. PP (x10(3) M-1), Eh(NAD+/NADH) (x - 1 mV), and deltaG(ATP hydrolysis) (x - 1 kcal/mol) were 1.9 +/- 0.4, 266 +/- 4, and 9.7 +/- 0.2, respectively, in the control group and 4.0 +/- 0.9, 274 +/- 5 and 13.0 +/- 0.2, respectively, in the UTI group after transfusion (p <.001, p <.001, and p <.001, respectively).

CONCLUSIONS

In reperfusion after hemorrhagic shock, oxidative phosphorylation in myocardial mitochondria is impaired and energy production remains reduced, even after reperfusion. UTI contributed to the recovery of cardiac function after reperfusion, probably by reducing the severity of mitochondrial dysfunction during a state of shock and by maintaining energy production.

Effects of hydroxyapatite in combination with far-infrared rays on spontaneous mammary tumorigenesis in SHN mice

We have found that the administration of a diet containing 5% hydroxyapatite (HAP) derived from pig and cattle bones, and exposure to far-infrared rays (FIR) markedly inhibited spontaneous mammary tumorigenesis in SHN mice. Thus, the effect of combined treatment with HAP and FIR on mammary tumorigenesis was examined. The significant inhibition of tumor development by individual treatment with HAP or FIR was not enhanced by combined treatment; instead, the decrease in the inhibitory effect of HAP with age was ameliorated. Associated with this, life span was elongated and a decline in ovarian function was prevented by HAP plus FIR. Normal and preneoplastic growth of mammary glands and plasma component levels were not significantly affected by any treatment. The findings indicate that HAP and FIR have characteristics common to most natural products; in combination with other agents, they have little additive effect, when each is highly active.

A novel hypoxia-dependent 2-nitroimidazole KIN-841 inhibits tumour-specific angiogenesis by blocking production of angiogenic factors

Tumour angiogenesis is initiated by angiogenic factors that are produced in large amounts by hypoxic tumour cells. The inhibition of this step may lead to tumour-specific antiangiogenesis because normal tissues are not usually hypoxic. On the other hand, blocking a biological function of endothelial cells is known to result in angiogenic inhibition. To produce a tumour-specific and powerful antiangiogenesis, we determined whether potent angiogenic inhibition could be achieved by inhibiting the production of angiogenic factors by hypoxic tumour cells and simultaneously blocking certain angiogenic steps in endothelial cells under normoxia. We focused on the 2-nitroimidazole moiety, which is easily incorporated into hypoxic cells and exhibits its cytotoxicity as hypoxic cytotoxin. We designed and synthesised 2-nitroimidazole derivatives designated as KIN compounds, and investigated their antiangiogenic activities under normoxia using a chick embryo chorioallantoic membrane. KIN-841 (2-nitroimidazole 1-acetylhydroxamate) showed a potent angiogenic inhibition in a dose-dependent manner. This compound inhibited the proliferation of bovine pulmonary arterial endothelial (BPAE) cells more strongly than that of tumour cells, such as Lewis lung carcinoma (3LL) cells, under normoxia. The inhibition of cell proliferation by KIN-841 under hypoxia increased about five-fold compared to that under normoxia. Moreover, under hypoxia, KIN-841 significantly decreased the excessive production of vascular endothelial cell growth factors induced by 3LL cells as determined by tritium-labelled thymidine ([(3)H]thymidine) incorporation into BPAE cells and by ELISA. Intraperitoneal administration of KIN-841 suppressed 3LL-cell-induced in vivo angiogenesis in the mouse dorsal air sac system. These results indicate that the regulation of the production of angiogenic factors by hypoxic tumour cells is a useful target for tumour-specific angiogenesis inhibition, and that KIN-841, which causes simultaneous direct inhibition of endothelial cell function and production of angiogenic factors by hypoxic tumour cells, is a very potent inhibitor of tumour-specific angiogenesis. Thus, the potential for clinical use of KIN-841 as an antitumour drug is very high.

Increased bystander mutagenic effect in DNA double-strand break repair-deficient mammalian cells

PURPOSE

We have shown previously that when monolayer cultures of Chinese hamster ovary (CHO) cells are exposed to very low fluences of alpha-particles, HPRT mutations are induced in non-irradiated 'bystander' cells in the population. The present investigation was designed to examine the role of DNA repair in this process.

MATERIALS AND METHODS

The DNA double-strand repair-deficient mutant cell line xrs-5 was exposed to mean doses of alpha-particles as low as 0.04 cGy whereby less than 1% of the nuclei were traversed by an alpha track and thus received any radiation exposure.

RESULTS

With this very low alpha-particle fluence, most of the cells in the xrs-5 population appeared to be at risk for the induction of mutations, indicating a much larger bystander effect than observed with wild-type CHO cells. Molecular structural analyses showed that xrs-5 mutants primarily involved partial and total gene deletions as opposed to wild-type cells where point mutations predominated in bystander cells.

CONCLUSIONS

These results indicate a very large bystander effect in xrs-5 cells. They support the hypothesis that unrepaired or misrepaired double-strand breaks (DSB), arising from opposed DNA lesions, enhance the sensitivity of bystander cells in xrs-5 cultures to the induction of mutations.

A matrix metalloproteinase inhibitor, ONO-4817, retards the development of mammary tumor and the progression of uterine adenomyosis in mice

The inhibitory effects of a novel matrix metalloproteinase inhibitor, ONO-4817, on the development of mammary tumors and the progression of uterine adenomyosis were examined in SHN mice. First, multiparous mice which developed mammary tumors spontaneously were used. The first palpable tumor was removed, and the mice were thereafter fed chow containing ONO-4817. Any second mammary tumor developing in the other mammary fat pad was also removed, and the mice were continuously fed the chow containing ONO-4817. The mice were killed when a third tumor was detected in the other fat pad. The periods between the occurrence of the first and second tumors, and the second and third ones were significantly increased in the mice treated with ONO-4817 compared to the mice not given ONO-4817 treatment. Second, to test ONO-4817 suppression of the progression of the invasion of uterine adenomyotic tissue, mice with experimentally-induced adenomyosis were treated with ONO-4817 for 4 weeks. The degree of pathological progression of adenomyosis was less in the uteri exposed to ONO-4817 than in the uteri not exposed to the inhibitor.

Development and evaluation of an enzyme-linked immunosorbent assay with recombinant SAG2 for diagnosis of Toxoplasma gondii infection in cats

Cats are pivotal in the transmission of Toxoplasma gondii. To develop a sensitive and specific serodiagnostic method for feline toxoplasmosis, surface antigen 2 (SAG2) of T. gondii was expressed in Escherichia coli and its diagnostic potential evaluated in an enzyme-linked immunosorbent assay (ELISA). The ELISA with recombinant SAG2 (rSAG2) was able to differentiate very clearly between sera from cats experimentally infected with T. gondii and sera from normal cats. Serum samples collected from domestic cats in Japan were investigated by the ELISA, and the results were compared with those of a commercially available latex agglutination test (LAT) kit. Of the 192 samples screened, 42 (21.9%) were positive by ELISA. Among the 42 ELISA-positive samples, 39 were positive by LAT. There was a significant correlation between ELISA and LAT titers. All the 150 ELISA-negative samples were negative by LAT. These results indicate that the ELISA with rSAG2 expressed in E. coli should be a useful method for detection of T. gondii infection in cats.

Antigen presentation by murine peritoneal cavity macrophage-derived dendritic cells

Murine peritoneal cavity macrophage derived dendritic cells (PEC-DC) generated using early growth factors, interleukin 4 and granulocyte-macrophage colony-stimulating factor followed by maturation in interferon-gamma plus either, Toxoplasma lysate antigen (TLA) or lipopolysaccharide, bind TLA by a nonspecific mechanism and continue to express major histocompatibility complex class II antigens after 24 h of culture in vitro. Moreover, the proliferation of CD3+ spleen T cells from mice immunized with Toxoplasma gondii homogenate, induced by PEC-DC-mediated antigen presentation was statistically significant and of consistent amplitude. This accessory function of PEC-DC is antigen specific.

Bystander effects: intercellular transmission of radiation damage signals

Biological effects were examined in confluent cultures of fibroblasts and epithelial cells exposed to very low mean doses of alpha radiation, doses by which only 1-2% of the cells were actually traversed by an alpha particle. Enhanced frequencies of sister chromatid exchanges and HPRT mutations occurred in the non-irradiated, 'bystander' cells associated with a similar increase in the frequency of micronuclei, indicating the induction of DNA damage in these cells. In order to gain information concerning molecular pathways, changes in gene expression were examined in bystander cells by western analysis and in situ immunofluorescence staining. The expression levels of p53, p21 and MDM2 were significantly modulated in bystander cells; the damage signals leading to these changes were transmitted from irradiated to bystander cells by gap junction mediated intercellular communication. The bystander response was suppressed by incubation with superoxide dismutase as well as an inhibitor of NADPH oxidase, suggesting the effect may be mediated by oxidative stress. To examine other signalling pathways responsive to oxidative stress, the activation of stress-related kinases and their downstream transcription factors were analysed in bystander cells by western blotting and electrophoretic mobility shift assays; a 2-4-fold increase in the phosphorylation levels of JNK, ERK1/2, p90RSK, Elk-1 and ATF2 was observed. These changes were detected by 15 min after irradiation and persisted for at least 1 h. These findings indicate the activation of multiple signal transduction pathways in bystander cells, involving signals arising from the plasma membrane as well as from DNA damage.

Effects of bitter melon (Momordica charantia l.) or ginger rhizome (Zingiber offifinale rosc) on spontaneous mammary tumorigenesis in SHN mice

The effects of chronic treatment with hot water extract of Bitter Melon (Momordica charantia L.) or Ginger Rhizome (Zingiber offifinale Rosc) on spontaneous mammary tumorigenesis were examined in SHN virgin mice. In mice given free access to extract of Bitter Melon (0.5%) or Ginger (0.125%) in drinking water, the development of mammary tumors was significantly inhibited. Furthermore, the former inhibited uterine adenomyosis with a common pathological background to mammary tumors and the latterinhibited mammary tumor growth. While the mechanism of the effects of these natural products remains to be clarified, there were no adverse effects of chronic treatment with these agents as estimated from body weight, food and water intake and various plasma component levels as well as external appearance. Thus, these natural products, popular in Japan as foodstuffs, also appear to have a health benefit.