Safety of a novel galacto-oligosaccharide: Genotoxicity and repeated oral dose studies

A series of safety tests were undertaken on a novel galacto-oligosaccharide (GOS) produced from lactose by a two-step enzymatic process involving Sporobolomyces singularis and Kluyveromyces lactis. Bacterial reverse mutation and chromosomal aberration tests, with or without metabolic activation, were performed. These tests showed no mutagenesis in the Ames assay or in Escherichia coli WP2uvrA, and no chromosomal aberrations in cultured fibroblast cells from Chinese hamster lungs (CHL/IU). Micronuclei were not induced in the reticulocytes of mouse peripheral blood following oral administration of GOS. In a 90-day repeated oral dose toxicity study in rats, GOS was administered at 0, 500, 1000 and 2000 mg/kg to male and female Sprague-Dawley rats. There were no GOS-related changes in clinical signs, body weight, water intake, feed intake, urinalysis, ophthalmology, haematology, blood chemistry, organ weights, gross pathology or histopathology in any of the treatment groups compared to the control group. The no observed adverse effect level (NOAEL) of GOS was at least 2000 mg/kg/day in both males and females.

Enzymatic synthesis of aliphatic beta-lactosides as mimic units of glycosphingolipids by use of Trichoderma reesei cellulase

Aliphatic beta-lactosides were directly synthesized by beta-lactosyl transfer reaction from p-nitrophenyl beta-lactoside (Lac beta-pNP) to various 1-alkanols (n = 2-12), utilizing commercially available cellulase preparation of Trichoderma reesei C1. With ethanol acceptor, the enzyme induced ethyl beta-lactoside (1) in 18% yield based on the donor added in aqueous buffer system. When 1-octanol and dodecanol were acceptors, octyl beta-lactoside (2) and dodecyl beta-lactoside (3) were also obtained as transfer products, respectively. In both cases, the addition of sodium cholate as detergent to the reaction system ensured a sufficient solubility of these acceptors and resulted in a remarkable increase of the desired compounds (5-13% yields based on the donor added). Furthermore, the enzyme catalyzed the N-acetyllactosaminyl transfer reaction from p-nitrophenyl beta-N-acetyllactosaminide (LacNAc beta-pNP) not only to 1-alkanol, but also to the OH-4 position of Man and Glc to produce the trisaccharides, Gal beta1-4GlcNAc beta1-4Man (4) and Gal beta1-4GlcNAc beta1-4Glc (5), respectively. The enzyme activities transferring lactosyl and N-acetyllactosaminyl groups were not separated by chromatographies using DEAE-Sepharose Fast Flow and Sephadex 75 pg columns, indicating that the two reactions were catalyzed by a single enzyme. It was specified that a single enzyme works both transglycosylations, based on the substrate competition assay on hydrolysis.

The role of tumor necrosis factor (TNF)-alpha in the antitumor effect of intrapleural injection of Lactobacillus casei strain Shirota in mice

The involvement of several cytokines in the antitumor effect induced by intrapleural (i.pl.) injection of heat-killed cells of Lactobacillus casei strain Shirota (LC 9018) in mice was investigated. Injection of LC 9018 i.pl. into Meth A fibrosarcoma (Meth A)-bearing mice not only significantly prolonged the survival of the mice, but also effectively inhibited the accumulation of malignant pleural fluid in the thoracic cavity. In the thoracic cavity of tumor-bearing mice treated with LC 9018, we observed large amounts of several cytokines including interleukin (IL)-1beta, interferon (IFN)-gamma, IL-12 and tumor necrosis factor (TNF)-alpha. Both anti-IFN-gamma and anti-IL-12 monoclonal antibody (mAb) treatments partially diminished the antitumor activity of LC 9018 in vivo, while the treatment of anti-IL-1beta mAb did not influence the survival of the mice. However, anti-TNF-alpha mAb treatment completely abolished the antitumor effect of LC 9018 in vivo, suggesting that in this model LC 9018 has a survival-prolonging effect involving certain cytokines. Moreover, i.pl. injection of mouse recombinant TNF-alpha into Meth A-bearing mice pretreated with anti-TNF-alpha mAb partially restored the survival-enhancing effect of LC 9018. These results led us to conclude that TNF-alpha induced by i.pl. injection of LC 9018 plays an important role in the antitumor effect of LC 9018 in vivo.

Elucidation of the region responsible for EDTA tolerance in PQQ glucose dehydrogenases by constructing Escherichia coli and Acinetobacter calcoaceticus chimeric enzymes

We constructed various chimeric PQQ glucose dehydrogenases (PQQGDHs) from an EDTA-sensitive PQQGDH from Escherichia coli and an EDTA-tolerant PQQGDH from Acinetobacter calcoaceticus by homologous recombination of their structural genes. The EDTA tolerance of the resulting chimeric enzymes was investigated. Our results demonstrated that EDTA tolerance of PQQGDHs can be completely altered by substituting each corresponding region. The EDTA tolerance of A. calcoaceticus PQQGDH is mostly within a region composed of about 90 amino acid residues located between 45 and 56% of the distance from the N-terminal region.

A multiple regression analysis of hemoglobin values and iron status in Japanese farmers

The authors performed multiple regression analysis of hemoglobin values and the parameters related to iron dynamics. The subjects consisted of 37 farmers whose Hb, Ht, GB, SI, %-St, SFR and FEP was examined once a month for one year. 19.2% of the female farmers had anemia of which 73.8% was iron-deficiency anemia, 13.7% being latent iron deficiency. Hb, GB and FEP in males and SI, %-St, SFR, FEP in females revealed clear seasonal variations. Multiple correlation coefficient between Hb and SI, %-St, SFR, FEP as independent variables was significant in females but not in males, and the ratio of contribution (38.7%) was not very high, however, the multiple correlation coefficient was significantly high (0.622). Standard regression coefficients between Hb and SFR, FEP were significantly high (p less than 0.01). When Ht and GB were added to these 4 variables, multiple correlation coefficients (male, 0.906; female, 0.957) were remarkably high, which means serum-related variables such as Ht and GB have an undeniably important role as explanatory variables of hemoglobin levels. These standard regression coefficients showed seasonal changes.

Anti-tumour effect of humoral and cellular immunities mediated by a bacterial immunopotentiator, Lactobacillus casei, in mice

Administration of a mixture containing Lactobacillus casei YIT 9018 (LC9018) and methylcholanthrene-induced fibrosarcoma (Meth A) cells into the peritoneum of syngeneic BALB/c mice suppressed the tumour growth and protected the mice from tumour death. With the appearance of the anti-tumour activity, serum complement-dependent tumour cytotoxic (CDC) antibody was induced on the 5th day after the administration as a result of the adjuvant effect. The cytotoxic antibody was not found in serum on the 5th day after inoculation of Meth A cells alone, but it was induced before the mice died of the tumours. Adjuvant induction of the cytotoxic serum antibody at an early time was also observed using Kirsten murine sarcoma virus-transformed tumour (K234) cells. Both of these cytotoxic antibodies in sera from Meth A-suppressed and the tumour-bearing mice were specific for the tumour cells and were IgM class, since they were absorbed with rabbit anti-mouse IgM antibody. However, the cytotoxic antibody was not found in the peritoneal cavity which was the tumour inoculation site, but binding antibody against the tumour cells was faintly detected in the region using an enzyme-linked immunoabsorbent assay (ELISA). In neutralization tests, the cytotoxic antibody did not exert anti-tumour activity in recipient mice when it was administered to the mice along with the tumour cells or when it was administered i.v. at the time of tumour inoculation. Moreover, the cytotoxic antibody was not available for the antibody-dependent cell-mediated cytotoxicity (ADCC). These results suggest that the cytotoxic antibody did not exert anti-tumour activity in the tumour-suppressed mice. In contrast, peritoneal exudate cells (PEC) on the 5th day, and PEC and spleen cells on the 15th day after i.p. administration of the mixture exerted strong anti-tumour activity as measured by the Winn test. In conclusion, the adjuvant effect of LC9018 induced tumour-specific humoral and cellular immunities but the anti-tumour activity was dependent only on the cellular effectors of the host. The possible use of LC9018 in tumour immunotherapy is discussed.

Comparison of antitumor activity of Lactobacillus casei with other bacterial immunopotentiators

Antitumor activity of Lactobacillus casei YIT 9018 (LC9018) was demonstrated by intralesional (i.l.) or intravenous (i.v.) administration into tumor-bearing mice which were inoculated with methylcholanthrene-induced fibrosarcoma (Meth A) or Kirsten murine sarcoma virus-transformed tumor (K234) cells. Its activity was significantly superior to the activity of two other species of lactobacilli but was nearly the same as that of Corynebacterium parvum or Mycobacterium bovis Bacille Calmette-Guérin (BCG). I.l. or i.v. administration of LC9018 into the tumor bearers caused local transient swelling or hepatosplenomegaly but did not cause other pronounced lesions. There was no significant difference in the degree of hepatosplenomegaly in LC9018 and that in other immunopotentiators. In mice whose tumors had regressed as a result of administration of LC9018 or the other immunopotentiators, the phytohemagglutinin P (PHA-P) response of the spleen cells was less than that of mice whose tumors progressed, and approached the normal level. The PHA-P response of popliteal lymph node cells proximal to the tumor lesion was fairly low compared with the splenic PHA-P response and there was no difference between the lymphocytes from mice whose tumors had regressed or progressed. Adjuvant activity of LC9018 in inducing tumor immunity was demonstrated by administering a mixture of LC9018 and Meth A cells to mice. This adjuvant activity was of the same efficiency as that of C. parvum and BCG. The presence of the antitumor activity of LC9018 in cell wall components was deduced from fact that removal of its cell wall by endo-N-acetylmuramidase (M-1 enzyme) abolished the activity. The possible availability of LC9018 for immunotherapy of tumors is discussed.

Host-mediated antitumor activity of Lactobacillus casei in mice

Antitumor activity of Lactobacillus casei YIT 9018 ( LC9018 ) was studied in BALB/c mice by using two syngeneic tumors; methylcholanthrene-induced tumor (Meth A fibrosarcoma) and Kirstein murine sarcoma virus-transformed BALB/3T3 ( K234 tumor). Administration of an LC9018 -Meth A cell mixture induced complete suppression of the tumor growth, while simultaneous injections of LC9018 and Meth A cells into different sites had no suppressive effect on the tumor growth. Administration of the mixture subsequently induced specific transplantation immunity to the challenge tumor, which started to be generated on about the 5th day after the administration and continued to at least the 30th day. Administration of an LC9018 - K234 cell mixture also induced suppression of the tumor growth and generated specific antitumor immunity. Neutralization (Winn type) tests showed that T lymphocytes possessed tumor cytotoxicity but humoral immune serum did not, suggesting that the T cells with LC9018 -potentiated antitumor immunity functioned in the suppression of the tumor growth.

Immunogenicity of Bacteroides isolated from mice: relationship between immunogenicity and cell wall antigens

Three different strains of Bacteroides were isolated from feces and cecal contents of mice. The immunogenicity of the strains was determined by measuring the serum agglutinin titers after intraperitoneal antigen injection. There were marked differences in quantity and quality of produced antibodies among the three strains. One strain (2-2) induced low antibody titers in both the primary and secondary responses, and a significant 2-mercaptoethanol (2-ME)-resistant antibody production occurred. Another strain (Y) induced low antibody titers in the primary response and high titers in the secondary response, but 2-ME-resistant antibody production did not occur. The third strain (2-4) induced very high antibody titers in both the responses, and a large amount of 2-ME-resistant antibody production occurred. Further, heat-ethanol-treated strain Y induced only immunoglobulin M antibody, but periodate-treated strain Y induced no antibody. Heat-ethanol- or periodate-treated strain 2-4 induced immunoglobulin M or G antibody, respectively. These observations suggest that the surface antigens of the two strains are distinctly different: the antigen of strain Y would be mostly O-antigen, whereas those of strain 2-4 would be O-antigen and protein moieties.

A comparative study on the humoral immune responses in germ-free and conventional mice

The plaque-forming cell (PFC) responses to sheep red blood cell (SRBC) dinitrophenyl-lysine-Ficoll (DNP-lys-Ficoll), and dinitrophenylated bovine serum albumin (DNP-BSA) have been studied in both germ-free and conventionally reared ICR mice. In germ-free mice, the IgG response to SRBC and the IgM and IgG responses to DNP-BSA were lower than in conventional mice, but no difference was observed in the IgM response to SRBC or the IgM and IgG responses to DNP-lys-Ficoll. Further, the number of 0-bearing cells in the spleen was smaller, and the mitogenic response of spleen cells to PHA was lower in germ-free mice than in conventional mice. These observations suggest that T cells of germ-free mice remain functionally immature.