Activation of hepatic NKT cells and subsequent liver injury following administration of alpha-galactosylceramide

It has been established that alpha-galactosylceramide (alpha-GalCer), a glycolipid, is recognized by natural killer T (NKT) cells together with the monomorphic MHC-like antigen, CD1d, in mice and humans. In this study, we examined how NKT cells are modulated by in vivo administration of alpha-GalCer in mice. When 2 microg (or more)/mouse of alpha(-GalCer was injected i.p., the majority of NKT cells disappeared in the liver and spleen, possibly undergoing apoptosis, on day 1. At this time, NKT cytotoxicity seen in liver lymphocytes also disappeared. In parallel with this numerical and functional change of NKT cells, there was always concomitant hepatocyte damage, as shown by histology and elevated levels of transaminases. Subsequently, the number and function of NKT cells continued to increase from day 3 to day 7. The response seen in hepatic (and splenic) NKT cells did not occur in thymic NKT cells. All these phenomena induced in the liver did not appear in NKT-deficient mice such as beta2-microglobulin(-/-) and CD1d(-/-) mice. These results shed further light on the in vivo interaction between NKT cells and alpha-GalCer in mice.     

Lipopolysaccharide Induces CD25-Positive, IL-10-Producing Lymphocytes Without Secretion of Proinflammatory Cytokines in the Human Colon: Low MD-2 mRNA Expression in Colonic Macrophages

Despite the huge number of colonized Gram-negative bacteria in the colon, the normal colon maintains its homeostasis without any excessive immune response. To investigate the potential mechanisms involved, human colonic lamina propria mononuclear cells (LPMCs) obtained from uninflamed mucosa were cultured with lipopolysaccharide (LPS) prepared from Bacteroides vulgatus (BV-LPS) or Bacteroides fragilis (BF-LPS), as representatives of indigenous flora, or pathogenic Salmonella minnesota (SM-LPS). Colonic LPMCs failed to produce inflammatory cytokines in response to any type of LPS. Colonic macrophages barely expressed mRNA for MD-2, an essential association molecule for LPS signaling via Toll-like receptor 4. Further, BV-LPS induced CD25 and Foxp3 expression in lymphocytes and CD4(+)CD25(+) cells expressed IL-10 mRNA. Thus, the low expression of functioning LPS receptor molecules and induction of IL-10-producing CD4(+)CD25(+) lymphocytes by indigenous LPS may play a central role in the maintenance of colonic immunological homeostasis.     

ECoG sleep-waking rhythms and bodily activity in the cerveau isolé rat

In rats with a high mesencephalic transection, isolating both the locus coeruleus and raphe nuclei from the forebrain, Electrocorticogram (ECoG) and Electromyogram (EMG) of the neck muscles were continuously recorded. Normal sleep-waking ECoG changes with a significant circadian rhythm reappeared in 4 to 9 days after transection. Neck muscle EMG and bodily movements were independent of the ECoG changes and did not show any significant circadian rhythm. In these high mesencephalic rats with sleep-waking ECoG changes, large bilateral hypothalamic lesions were made by passing DC current either in the preoptic area or in the posterior hypothalamus. After the preoptic area lesions the amount of low voltage fast ECoG per day markedly increased, whereas after the posterior hypothalamic lesions, the total amount of low voltate fast wave per day decreased showing long-lasting slow wave sleep pattern. These results support an idea that the forebrain, especially in the hypothalamus including the preoptic area, a mechanism inducing sleep-waking ECoG changes is localized.     

Specific amplification of Rickettsia tsutsugamushi DNA from clinical specimens by polymerase chain reaction.

Polymerase chain reaction (PCR) was used to detect Rickettsia tsutsugamushi-specific DNA in clinical specimens. The primer pair used for PCR was designed from the nucleotide sequence of the gene encoding the 56-kDa antigen of the Gilliam strain. Theses primers led to a 78-bp fragment by amplifying the genomic DNAs from five serovariants, i.e., the Gilliam, Karp, Kato, Kawasaki, and Kuroki strains of R. tsutsugamushi, and also the DNA from blood clots of patients with scrub typhus, even at the early stage of onset of the disease. This indicates that this method is suitable for the diagnosis of scrub typhus.     

Further Survey of Aflatoxin M1 in Milk Powders by ELISA

A survey of AFM₁ residues in 58 commercial milk powder samples was carried out using an enzyme‐linked immunosorbent assay (ELISA) based on a monoclonal antibody against aflatoxin M₁ (AFM₁). The samples were collected from the USA (10), China (28), Italy (14), New Zealand (3) and Poland (3). The ELISA was performed without the need for clean‐up procedures. The data revealed that 4 (US), 21 (Chinese) and 1 (Polish) samples were positive for AFM₁, with an average of 95.5, 102.8 and 85.0 pg g^‐1 of the AFM₁respectively.     

Requirement of the initial production of gamma interferon in the generation of protective immunity of mice against Listeria monocytogenes.

Protective immunity of mice against Listeria monocytogenes, which is mediated mainly by gamma interferon (IFN-gamma)-producing T cells, was induced by immunization with viable bacteria but not with killed bacteria. By comparing mice immunized with either viable or killed L. monocytogenes, it was found that IFN-gamma was produced at the initial stage only after immunization with viable bacteria. This finding prompted us to investigate the effect of neutralizing the IFN-gamma on the final generation of protective T cells against L. monocytogenes. When endogenous IFN-gamma was neutralized by administration of anti-IFN-gamma monoclonal antibody for the initial 2 days in mice immunized with viable bacteria, the generation of protective T cells on day 6 was completely blocked, as revealed by T-cell adoptive transfer. The generation of listeria-specific IFN-gamma-producing T cells was also abolished. These results clearly demonstrated that endogenous IFN-gamma, which is produced at the initial stage of immunization, actually plays a critical role in the generation of protective T cells against L. monocytogenes in vivo. Moreover, this study suggested that the lack of IFN-gamma-inducing ability is responsible for the inability of killed L. monocytogenes to induce protective T cells in mice.     

Liver metastasis from rectal cancer with prominent intrabile duct growth

Intrabiliary growth of liver metastases from colorectal cancer has rarely been studied. A surgically resected case of a metastatic liver tumor with prominent intrabiliary growth derived from rectal cancer is reported. The patient was a 62-year-old man who had received a low anterior resection for rectal cancer in March 2000. He was re-admitted due to obstructive jaundice in January 2003, and was diagnosed with hepatic malignancy in segment II of the liver with an intrabiliary tumor extending from the intrahepatic bile duct of segment II to the common hepatic duct. He underwent a left hepatectomy, a partial resection of segment VI, and an extrahepatic bile duct resection with reconstruction of the biliary tract. In the resected specimen, there were whitish tumors of 3 cm and 1.5 cm in diameter in segments II and VI, respectively, and an intrabiliary tumor originating from the main tumor in segment II extended to the common hepatic duct. Both the liver tumors and the intrabiliary tumor consisted of a well- to moderately differentiated adenocarcinoma, which showed the same histological features as the rectal cancer. The immunohistochemical findings strongly supported that these tumors, including the intrabiliary growth, were liver metastasis from the rectal cancer. The intrabiliary invasion and growth of metastatic liver tumors has generally been overlooked, notwithstanding their frequently observed biological behavior. The present case is informative, and further investigation into this type of metastatic liver tumor may be warranted.