The plasma levels of phenol, p-cresol, and indican are markedly increased in uremic patients, and cannot be efficiently reduced by hemodialysis. Such uremic toxins, which are produced in the intestine as bacterial putrefactive metabolites, accumulate to a great degree in the feces of hemodialysis patients. Oral administration of Lebenin®, a preparation consisting of antibiotic-resistant lactic acid bacteria, reduced the levels of fecal putrefactive metabolites to levels comparable with those of healthy subjects. Moreover, the plasma level of indican also significantly decreased in these Lebenin-treated patients. An analysis of the fecal microflora revealed that a disturbed composition of the microflora characterized by an overgrowth of aerobic bacteria is restored to normal by oral administration of Lebenin in hemodialysis patients. These results thus demonstate that oral administration of lactic acid bacteria in uremic patients is effective in reducing the levels of uremic toxins, especially that of indican, in the blood by inhibiting bacterial production by means of correcting the intestinal microflora.

SUMMARYIn order to elucidate the ecological role of bacteriophages in the human intestine, we analysed the numbers of coliphages and of coliphage strains present in faecal samples collected from healthy individuals and from patients with certain intestinal diseases. The isolated phages were grouped according to their serological properties. The samples with low phage titres, observed in both healthy subjects and patients, contained mainly temperate phages (many were related to ~b80 and 2), and those with higher titres, observed in patients, contained virulent phages. From successive surveys of coliphages and their host, Escherichia coli, in faecal samples of each subject, it was concluded that temperate phages are maintained in the human intestine through spontaneous induction of lysogenic bacteria. Qualitative and quantitative differences existed between phages isolated from faecal samples from healthy subjects and from patients. Simultaneous changes in the distribution patterns of coliphages and of the clinical symptoms were observed in a continuous survey of a leukaemic patient in a protective environmental ward.

Whether or not NO plays a critical role in murine CMV (MCMV) infection has yet to be elucidated. In this study, we examined the role of NO in acute infection with MCMV using NO synthase type 2 (NOS2)-deficient mice. NOS2−/− mice were more susceptible to lethal infection with MCMV than NOS2+/+ mice and generated a much higher peak virus titer in the salivary gland after acute infection. A moderate increase in the MCMV titer was also observed in other organs of NOS2−/− mice such as the spleen, lung, and liver. The immune responses to MCMV infection including NK cell cytotoxicity and CTL response in NOS2−/− mice were comparable with those of NOS2+/+ mice. Moreover, the ability to produce IFN-γ is not impaired in NOS2−/− mice after MCMV infection. The peritoneal macrophages from NOS2−/− mice, however, exhibited a lower antiviral activity than those from NOS2+/+ mice, resulting in an enhanced viral replication in macrophages themselves. Treatment of these cells from NOS2+/+ mice with a selective NOS2 inhibitor decreased the antiviral activity to a level below that obtained with NOS2−/− mice. In addition, the absence of NOS2 and NOS2-mediated antiviral activity of macrophages resulted in not only an enhanced MCMV replication and a high mortality but also a consequent risk of the latency. It was thus concluded that the NOS2-mediated antiviral activity of macrophages via NO plays a protective role against MCMV infection at an early and late stage of the infection.

The potent role of indigenous microbiota in maintaining murine CMV (MCMV)-specific memory T cells, which were measured by multimer staining, was investigated using germfree (GF) mice. When the BALB/c mice bred under specific pathogen-free (SPF) conditions were i.p. infected with 0.2 LD50 of MCMV, high frequencies of CD69+/CD44+ MCMV-specific CD8 T cells were noted in the lungs even at 6–12 mo after infection (11.1 ± 3.2 and 9.8 ± 0.9%, respectively). In contrast, even though the viral load and expression levels of mRNA of such cytokines as IL-2, IL-7, IL-15, and IFN-γ in the lungs of MCMV-infected GF mice were comparable to those of infected SPF mice, the frequencies of MCMV-specific CD8 T cells in the lungs of infected GF mice were kept lower than 1% at 6–12 mo after infection. In addition, the reconstitution of microbiota of MCMV-infected GF mice by orally administering a fecal suspension prepared from SPF mice restored the frequencies of both CD8+/multimer+ and CD8+/multimer− T cells to levels similar to those found in SPF mice. These results suggested the indigenous microbiota to play a crucial role in the expansion and maintenance of viral-specific CD8 memory T cells, probably by cross-reactivity between the antigenic epitope of the MCMV-specific memory T cells and the variety of peptides derived from the members of the microbiota. Such cross-reactivity may thus be a major feature of those cells.

Intolerable malodor emanating from ulcerated tumors as a result of anaerobic infection is a serious problem in the management of advanced and recurrent breast cancer. Metronidazole can control this malodor, but its oral use may cause adverse reactions. We therefore formulated a metronidazole gel, since no equivalent preparation is commercially available in Japan, and used it in five female patients (four with advanced cancer and one with recurrent cancer) admitted to our hospital between March 1994 and July 1995. The patients were aged between 47 and 71 (median: 59) years, and the duration of morbidity in the four patients with advanced cancer ranged from 10 months to four years. In three patients, the tumors were larger than 10 cm x 10 cm. Metronidazole gel was applied to the surface of ulcerated tumors once or twice daily. Independent assessments by the patient, doctor and nurse were unanimous, and revealed that the malodor was alleviated in one patient after three days, and removed in four patients after two to five (median: four) days of metronidazole gel treatment. Culture of swabs showed a decrease or disappearance of anaerobic colonies. Adverse reactions characteristic of metronidazole did not occur. The topical use of metronidazole in a gel form will improve the quality of life for patients with malodorous ulcerated tumors and facilitate intensive treatment of the underlying disease.

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Summary. Growth of Clostridium dzficile was inhibited more strongly in continuous flow (CF) culture with C. dzficile-negative faeces of infants than with C. dificile-positive faeces. Culture of faecal flora of infants yielded a greater variety of bacterial species in C. dzficilenegative than in C. dzficile-positive faeces. In the mixed CF culture of C. dzficile with Enterococcus avium, Bacteroides distasonis, Eubacterium lentum, C. ramosum, C. perfringens and either Escherichia coli or Klebsiella pneumoniae isolated from C. dzficile-negative faeces, inhibition of growth of C. dzficile was demonstrated when the pH of the culture medium was decreased. Amino-acid analysis of CF cultures showed considerable utilisation of aspartic acid, serine, threonine, arginine and asparagine. A marked increase in concentrations of citrulline and ornithine was found in the culture that inhibited growth of C. dzficile. The addition of citrulline and ornithine into a Gifu anaerobic medium (GAM) broth produced no inhibition of growth of C. dzficile. The addition of the mixture of the depleted amino acids (aspartic acid, serine, threonine, arginine and asparagine) to the culture filtrate or adjustment of the pH of the culture filtrate induced considerable growth of C. dzficile. These results suggest that the inhibition of growth of C. dzficile may be due to consumption of amino acids by intestinal flora, and not to the presence of inhibitors produced by the intestinal flora.

iNOS induction does not affect the development of atherosclerosis in mice fed an atherogenic diet, but the resulting lesions show decreased levels of extracellular collagen and may be more fragile.