Complete nucleotide sequence of the prophage VT2-Sakai carrying the verotoxin 2 genes of the enterohemorrhagic Escherichia coli O157:H7 derived from the Sakai outbreak

The enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain RIMD 0509952, derived from an outbreak in Sakai city, Japan, in 1996, produces two kinds of verotoxins, VT1 and VT2, encoded by the stx1 and stx2 genes. In the EHEC strains, as well as in other VT-producing E. coli strains, the toxins are encoded by lysogenic bacteriophages. The EHEC O157:H7 strain RIMD 0509952 did not produce plaque-forming phage particles upon inducing treatments. We have determined the complete nucleotide sequence of a prophage, VT2-Sakai, carrying the stx2A and stx2B genes on the chromosome, and presumed the putative functions of the encoded proteins and the cis-acting DNA elements based on sequence homology data. To our surprise, the sequences in the regions of VT2-Sakai corresponding to the early gene regulators and replication proteins, and the DNA sequences recognized by the regulators share very limited homology to those of the VT2-encoding 933W phage carried by the EHEC O157:H7 strain EDL933 reported by Plunkett et al. (J. Bacteriol., p1767-1778, 181, 1999), although the sequences corresponding to the structural components are almost identical. These data suggest that these two phages were derived from a common ancestral phage and that either or both of them underwent multiple genetic rearrangements. An IS629 insertion was found downstream of the stx2B gene and upstream of the lysis gene S, and this might be responsible for the absence of plaque-forming activity in the lysate obtained after inducing treatments.

Anti-HIV-1 activity of an ionically modified porous polypropylene membrane determined by filtration of a viral suspension

We describe here a unique anti-HIV-1 membrane, derived from a chemically modified porous polypropylene (PP) membrane, which lowers viral infectivity upon the filtration of HIV-1 suspension. A cationic polymer, polyethyleneimine (PEI) was graft-polymerized onto the PP filter membrane (PP-PEI), and infectious HIV-1(HTLV-IIIB) derived from MOLT-4/HIV-1(HTLV-IIIB) cells (HIV-1(HTLV-IIIB(MOLT-4)) was applied. When a viral suspension of high titer (10(3.93) TCID50 ml(-1) was filtered, efficient reduction (>99%) of gag p24 antigen levels and infectious titer resulted. In a viral suspension of medium titer (10(2.37) TCID50 ml(-1), a significant decrease in the p24 antigen did not occur, although the titer was markedly reduced (>95%). Electron microscopic observation suggested that PEI induced viral aggregations under high titer conditions, and under medium titer conditions, PEI deprived HIV-1(HTLV-IIIB(MOLT-4)) of its infectivity alone to avoid virus adsorption. In contrast, HIV-1 propagated in human peripheral blood mononuclear cells (PBMC) such as HIV-1(HTLV-III(PBMC)) was more efficiently trapped by PP-PEI at lower titers as compared with HIV-1(HTLV-IIIB(MOLT-4)) from MOLT-4/HIV-1(HTLV-IIIB) cells. These data suggest host cell modification in the interactions between PP-PEI and HIV-1 strains. Since HIV-1(HTLV-IIIB(MOLT-4)) and HIV-1(HTLV-IIIB(PBMC)) were almost electrically neutral and negative, respectively, we concluded that the divergent effect of PEI on each HIV-1(HTLV-IIIB) resulted from their different electrical characteristics.

[Serum amyloid A (SAA) 1, SAA 2 and apolipoprotein E isotype frequencies in rheumatoid arthritis patients with AA amyloidosis]

OBJECTIVES

To examine the relationship between polymorphism of serum amyloid A (SAA) 1, SAA 2 and Apolipoprotein E (Apo E) and susceptibility to AA amyloidosis (AA) in rheumatoid arthritis (RA).

METHODS

We compared the frequencies of SAA 1 alleles (alpha, beta, gamma), SAA 2 alleles (alpha, beta) and apo E alleles (epsilon 2, epsilon 3, epsilon 4) in AA-positive RA with those in AA-negative RA. Each isotype was analyzed by the following method: SAA 1 and SAA 2 by PCR-RFLP and Apo E by Western blotting method. Blood samples were obtained from 50 AA-positive RA patients with SAA 1 isotype, 50 AA-negative RA patients with SAA 1 isotype, 27 AA-positive RA patients with SAA 2 isotype, and 26 AA-negative RA patients with SAA 2 isotype, respectively. Likewise, Apo E isotype was determined by withdrawing blood samples from 61 AA-positive RA cases and 51 AA-negative RA cases.

RESULTS

In AA-positive RA, each frequency of three different alleles of SAA 1, i.e., alpha, beta and gamma was 15%, 32% and 53%, while it was 32%, 28% and 40% in AA-negative RA. The allelic distribution between AA-positive RA group and AA-negative RA group was significantly different (P = 0.00163) with a lower frequency of alpha allele and a higher gamma allele frequency observed in AA-positive RA group. The frequency of each SAA 2 alleles (alpha & beta) was almost identical: 88.9% and 11.1% in AA-positive RA versus 90.4% and 9.6% in AA-negative RA with p value of 0.8007. Each frequency of three different Apo E alleles (epsilon 2, epsilon 3 & epsilon 4) was 4.9%, 85.2% and 9.8% in AA-positive RA, while in AA-negative RA it was 7.8%, 86.3% and 5.9%, respectively. The AA-positive RA group showed a slightly higher prevalence of epsilon 4 allele than the AA-negative RA group, yet the difference did not reach statistical significance (P = 0.3969).

CONCLUSIONS

These results suggest the possibilities that SAA 1 alpha may be working protectively against and SAA 1 gamma provocatively for the development of AA amyloidosis in RA. However, there was no significant association between SAA 2 isotype patterns and the development of AA amyloidosis in RA. Furthermore, there was no discernible association between AA amyloidosis in RA and Apo E 4 isotype.

Clinical electroencephalographic study of nine pediatric patients with convulsion induced by the TV animation, Pocket Monster

BACKGROUND

To determine the usefulness of a few types of photic stimulation in patients with photo-convulsive response.

METHODS

A clinical electroencephalographic study was conducted in nine children who developed convulsions and other symptoms while they watched the TV animation and were subsequently treated at the hospital. Photic stimulation was applied with their eyes open or closed. Another photic stimulation was applied with the video tape of the animation.

RESULTS

A photoparoxysmal response (PPR) was never seen in the electroencephalographs (EEG) in any of these patients when photic stimulation was applied with their eyes closed, while PPR was seen in three of seven patients when photic stimulation was applied with their eyes open. Two patients (siblings) showed no specific abnormality when photic stimulation was applied with their eyes either open or closed. However, myoclonus and PPR appeared when the EEG was conducted while they watched the video tape of the animation under supervised conditions.

CONCLUSIONS

In a society where people are exposed to abundant TV games, TV animation or videos, self-restraint or regulations of frequent use of flickering scenes is thought to be necessary. However, it is also thought to be necessary to conduct EEG by applying photic stimulation, not only with the eyes closed, but also with the eyes opened or by applying flickering red light stimulation, which is emitted from a strong light source, or a combination of two colors, such as red and blue or red and green, in patients with suspected photosensitivity.

Anticoagulant and antiprotease activities of a heparinoid sulfated glucoside-bearing polymer

We studied anticoagulant and antiprotease activities of the poly(glucosyloxyethyl methacrylate) sulfate [poly(GEMA)-sulfate] in plasma and purified enzyme systems in order to evaluate the anticoagulant behavior of a heparin-like sulfated glucoside-bearing polymer. As a result, we found that poly(GEMA)-sulfate can inhibit some coagulation proteases, although its antiprotease behavior differed from those of heparin and dextran sulfate. Poly(GEMA)-sulfate could not enhance antithrombin activity; therefore, we did not observe any significant inhibition of Factor Xa via antithrombin. However, we found that poly(GEMA)-sulfate was able to inhibit thrombin through the activation of heparin cofactor II. In addition, poly(GEMA)-sulfate was able to inhibit Tenase. In our previous research. we found that the anticoagulant activity of poly(GEMA)-sulfate is due primarily to the formation of an insoluble complex with fibrinogen. This paper showed that the antiprotease activities of poly(GEMA)-sulfate contribute to some extent to its anticoagulant activity.

Cytokine receptors: structures and signal transduction

The characteristic features of cytokines are functional pleiotropy and redundancy. Each cytokine is produced by a variety of cell types and acts on a wide range of target cells and tissues. Many cytokines have overlapping biological activities in the same cells. It was originally thought that each cytokine has a specific receptor and a unique signal transduction system. However, extensive studies on cytokines and their receptors revealed that many cytokines share receptor subunits and signal transduction system, and that biological functions of a single cytokine can vary depending on the status of the cells. Therefore, it is important to know the structure and function of cytokine receptors to understand the pleiotropy and redundancy as well as specificity of cytokines. Among signal transduction pathways, recently identified Jak/STAT pathway, which connects activation of the receptor complexes and transcription of various genes directly, would give us further insights in the mechanisms of cytokine action.

Identification and characterization of a constitutively active STAT5 mutant that promotes cell proliferation

STAT (signal transducers and activators of transcription) proteins are transcription factors which are activated by phosphorylation on tyrosine residues upon stimulation by cytokines. Seven members of the STAT family are known, including the closely related STAT5A and STAT5B, which are activated by various cytokines. Except for prolactin-dependent beta-casein production in mammary gland cells, the biological consequences of STAT5 activation in various systems are not clear. We applied PCR-driven random mutagenesis and a retrovirus-mediated expression screening system to identify constitutively active forms of STAT5. By this strategy, we have identified a constitutively active STAT5 mutant which has two amino acid substitutions; one is located upstream of the putative DNA binding domain (H299R), and the other is located in the transactivation domain (S711F). The mutant STAT5 was constitutively phosphorylated on tyrosine residues, localized in the nucleus, and was transcriptionally active. Expression of the mutant STAT5 partially dispenses with interleukin 3 (IL-3) as a growth stimulant of IL-3-dependent cell lines. Further analyses of the mutant STAT5 have demonstrated that both of the mutations are required for nuclear localization, efficient transcriptional activation, and induction of IL-3-independent growth of an IL-3-dependent cell line, Ba/F3, and have indicated that a molecular basis for the constitutive activation is the stability of the phosphorylated form of the mutant STAT5.

A chemical modification of myeloperoxidase and lactoperoxidase with 2-(O-methoxypolyethylene glycol)-4, 6-dichloro-s-triazine (activated PEG1)

The modification of myeloperoxidase and lactoperoxidase with 2-(O-methoxypolethylene glycol)-4, 6-dichloro-s-triazine, an activated polyethylene glycol (PEG1), was investigated. The modification caused a shift of the Soret band in the light absorption spectrum, from 430 nm to 418 nm in the case of myeloperoxidase (native ferric form), and from 412 nm to 406 nm in the case of lactoperoxidase (native ferric form). PEG1-modified myeloperoxidase and PEG1-modified lactoperoxidase both failed to bind with antiserum to the respective native enzyme, but both retained respectively 4.5 +/- 0.3 per cent (mean +/- SE, n = 5) and 0.6 +/- 0.2 per cent (mean +/- SE, n = 5) of the activities of peroxidation of the hydrogen donor o-methoxyphenol in comparison with the native enzyme, and 1.5 +/- 0.2 per cent (mean +/- SE, n = 5) and 1.2 +/- 0.2 per cent (mean +/- SE, n = 5) of the activities of destruction of fuchsin basic in the presence of hydrogen peroxide and a halide, bromide. The pH dependencies of the peroxidating activities were almost the same as those of the corresponding native enzymes, but both the optimal pHs of the reactions involving the destruction of fuchsin basic were shifted by approximately 1.0 pH unit toward neutral pH compared with the respective native enzymes.

Inactivation of urate oxidase by a system composed of lactoperoxidase, hydrogen peroxide and bromide

Urate oxidase from Candida utilis, an enzyme containing an essential thiol, was examined for its sensitivity to lactoperoxidase, an oxidant present in breast milk. Upon exposure to a system composed of lactoperoxidase, hydrogen peroxide and bromide at moderately alkaline pH, the urate oxidase exhibited comparable activity to the untreated enzyme; but upon exposure at moderately acidic pH, it lost its activity completely. Thus the lactoperoxidase-H2O2-bromide system significantly inactivated urate oxidase only at moderately acidic pH. This inactivation was prevented by the presence of N-acetylmethionine, a methionine analogue, or glutathione, which is a thiol compound analogous to an amino acid, indicating that it was probably due to the oxidation and damage of the methionine residue and/or the thiol group in the urate oxidase by the lactoperoxidase system, that loss of catalytic activity of the urate oxidase occurred.

Enhancement of human immunodeficiency virus type 1 (HIV-1) infection via increased membrane fluidity by a cationic polymer

Cationic polymers are known to have potent activity against bacteria, but their effects on viral activity have been little studied. We investigated the effect of one such polymer, polyethyleneimine (PEI), on HIV-1 infection. Although virus-cell binding was significantly inhibited by PEI, HIV-1 infection in human T-cell lines such as MT-4 and MOLT-4 was accelerated conversely when the drug treatment was carried out, after the virus had attached to the cells or PEI was simultaneously added to the virus and cell culture system. This paradoxical effect of PEI on HIV-1 infection was examined using HIV-1 chronically infected cells (MOLT-4/HIV-1). Dissociation of the glycoprotein gp120 (as revealed by exposure of transmembrane protein gp41) from MOLT-4/HIV-1 cells and the resultant fusion of these cells was shown to be induced by the addition of PEI. Accordingly, it was suggested that the binding inhibition of HIV-1 to CD4-positive cells by PEI was due to the shedding of gp120 from HIV-1 particles, and this PEI rather promoted membrane fusion between the virus and cells leading to the enhancement of HIV-1 infection. Similarly, dissociation of gp120 from MOLT-4/HIV-1 was also induced by sCD4. The effect of these reagents on changes in membrane fluidity was evaluated by polarization (p) measurements, and it was observed that the acceleration of membrane fluidity occurred only in the PEI system. Therefore, it is likely that PEI accelerates HIV-1 infection by facilitating virus entry into the host cells through an increase in membrane fluidity.

Usage of activating mutations in the analysis of cytokine signal transduction pathways

Cytokine signal transduction pathways are highly redundant and complex. The analysis of the structure and function of signal transduction molecules was conventionally done by using mutated or truncated receptors, dominant negative molecules, and knockout mice. These methods are designed to look at the result of a subtraction of a part of the whole signal transduction pathway. In contrast, analysis using activating mutations of a signal transduction molecule is designed to look at the downstream result of one pathway which originated from the pertinent molecule. This method is less influenced by other signal transduction molecules which may have an overlapping effect on the downstream molecules. By combining both the subtraction and activating methods, we can gain more insight into the complex interactions between signal transduction molecules. An activating mutation of a signal transduction molecule is usually found as an oncogene. However, known oncogenes are not always the molecules of interest. In this review, several methods to create activating mutations of a target molecule are discussed.

[Internalized norms and social norms relating to negative health behaviors. The relationship of sociodemographic characteristics and reference groups]

So-called "negative health behaviors" (e.g. smoking, excessive eating/drinking), which are related to morbidity and mortality, are generally well known to the public. However there are many who undertake negative health behaviors despite knowing of their negative health effects. Using a mail survey of subjects aged 25 to 54, we examined reasons and justifications for engaging in negative health behaviors and their related factors from the lay person's perspective. Concerning the reasons for negative health behaviors, we hypothesized seven concepts (work priority, group harmony priority, the contribution to relaxation, tools for communication, prior orientation focused on the present, individualistic priority, and appearance), and devised multiple questions for each concept. The results are as follows. 1. Compared to females, males tended to support of the five concepts about the internalized norms concerned with negative health behaviors (e.g. the tendency of each individual to approve or disapprove of the reasons for negative health behaviors). In females, the younger generation and those that were married expressed more support than the older and the unmarried. There were differences in males according to occupation. 2. Concerning which reference groups had the largest influence on the social norms concerned with negative health behaviors (e.g. the perceptions as to what degree a group regards the reasons about negative health behaviors as desirable), most perceived that the "office" and "friends" groups would be more supportive of reasons for negative health behaviors than the "family" groups. 3. The health behaviors, which correlated with the internalized norms or the social norms concerned with negative health behaviors, were eating breakfast, smoking, and drinking (frequency and amount). In particular, drinking behavior was influenced most by the internalized norms and the social norms.

Comparative blood compatibility of polyether vs polycarbonate urethanes by epifluorescent video microscopy

The segmented polyether urethanes (PEUs) have been used in implantable medical devices due to excellent mechanical properties, acceptable blood compatibility, and good biostability. However, recent studies demonstrate that the polyether soft segment of PEU is susceptible to oxidative degradation in vivo due to scission of the polyether group. Recently, polycarbonate urethanes (PCUs) having no ether linkage in the soft segment have been developed, and show improved stability against oxidative degradation over PEUs. The current study evaluates blood compatibility of these PCUs in comparison with PEUs using epifluorescent video microscopy (EVM) combined with a parallel plate flow cell. The authors selected two PCUs, Corethane 80A (Corvita Corporation, Miami, FL) and PCU(1560), and two PEUs, Pellethene 2363-80AE (Dow Chemical Japan, Tokyo, Japan) and Tecoflex EG80A (Thermedics, Inc., Woburn, MA), all of which have similar hard segment compositions (MDI or HMDI:1,4-butanediol(BD)) and the same hardness of 80A. The EVM measured the amount of platelet coverage on the surfaces using human whole blood perfused at a wall shear rate of 100/sec for 20 min. Complement activation (C3a) also was measured. Both PEUs, especially Pellethane, showed significantly higher platelet adhesion than the PCUs (p < 0.05). There were no significant differences in platelet adhesion between the two PCUs. As for C3a measurements, Tecoflex showed higher complement activation than the others. Based on these results, it is recommended that PEUs should be replaced by ether free PCUs for use in implantable blood contacting devices such as artificial hearts and pacemaker lead insulators.

Cytolysis of B-16 melanoma tumor cells mediated by the myeloperoxidase and lactoperoxidase systems

Halide-dependent cytolysis of B-16 melanoma cells mediated by myeloperoxidase and lactoperoxidase systems was observed by turbidimetry. A significant decrease in turbidity, which is indicative of cytolysis, was found when a system consisting of myeloperoxidase, a source of hydrogen peroxide (glucose+glucose oxidase), and chloride or bromide were added to a B-16 melanoma cell suspension in the pH 4.7-6.0 region. The myeloperoxidase could be replaced by lactoperoxidase in the system containing bromide, but not that containing chloride. B-16 melanoma cells exposed to myeloperoxidase or lactoperoxidase systems at pH 5.5 or 7.0 were implanted by subcutaneous inoculation into C57BL/6CrSlc mice. After 14 days, a significant suppression of the growth of black tumors was detected in the groups of mice inoculated with melanoma cells exposed to the systems containing myeloperoxidase, glucose, glucose oxidase and chloride or bromide, or the system containing lactoperoxidase, glucose, glucose oxidase and bromide, at pH 5.5, but no significant suppression was observed at pH 7.0. From these findings, we concluded that the exposure of B-16 melanoma cells to a system consisting of myeloperoxidase, hydrogen peroxide (generated by the glucose+glucose oxidase system) and chloride or bromide, or of lactoperoxidase, the hydrogen peroxide and bromide, at moderately acidic pH, causes cytolysis is accompanied by cell death.

Identification of an oncogenic form of the thrombopoietin receptor MPL using retrovirus-mediated gene transfer

Thrombopoietin and its receptor (MPL) are important regulators of megakaryopoiesis. We have identified an activating mutation of MPL using a combination of a retrovirus-mediated gene transfer and polymerase chain reaction-driven random mutagenesis. This point mutation causes a single amino acid substitution from Ser498 to Asn498 in the transmembrane region and abrogates factor-dependency of all interleukin-3-dependent cell lines tested. Murine interleukin-3-dependent Ba/F3 cells expressing the mutated but not the normal form of MPL were tumorigenic when transduced into syngeneic mice. Analysis of intracellular signaling pathways indicated that the mutant MPL protein constitutively activated two distinct signaling pathways, SHC-Raf-MAPK and JAK2-STAT3/STAT5.

Applications of retrovirus-mediated expression cloning

We have recently established a novel expression cloning system using retroviral vectors. The system is based on a high-efficiency packaging cell line, BOSC23, and a simplified retroviral vector, pBabeX, carrying no selection marker. cDNA libraries, constructed in the pBabeX vector, are transiently transfected into BOSC23 cells. The supernatant contains more than 3X10(6)/mL, which would cover large complexities of cDNA libraries. The retrovirus stock gave 100% infection efficiency in NIH3T3 cells and 5-40% infection efficiency in various hematopoietic cell lines. In contrast to the conventional expression cloning system, in which it is necessary to transfect cDNA libraries transiently into particular cell types such as COS cells, retrovirus-mediated expression cloning allows us to transduce cDNAs into a wide variety of cell types. This method therefore makes it possible to select cells expressing a cDNA of interest by various functional assays. When combined with polymerase chain reaction (PCR)-driven random mutagenesis, this system is also useful in searching for mutations of various molecules that will result in alterations of their functions.

Efficient screening of retroviral cDNA expression libraries

Expression cloning of cDNAs was first described a decade ago and was based on transient expression of cDNA libraries in COS cells. In contrast to transient transfection of plasmids, retroviral gene transfer delivers genes stably into a wide range of target cells. We utilize a simple packaging system for production of high-titer retrovirus stock from cDNA libraries to establish a cDNA expression cloning system. In two model experiments, murine interleukin (IL)-3-dependent Ba/F3 cells were infected with libraries of retrovirally expressed cDNA derived from human T-cell mRNA or human IL-3-dependent TF-1 cell line mRNA. These infected Ba/F3 cells were selected for the expression of CD2 by flow cytometry or for the alpha subunit of the human IL-3 receptor (hIL-3R alpha) by factor-dependent growth. CD2 (frequency, 1 in 10(4)) and hIL-3R alpha (frequency, 1 in 1.5 x 10(5)) cDNAs were readily detected in small-scale experiments, indicating this retroviral expression cloning system is efficient enough to clone low-abundance cDNAs by their expression or function.

Analysis of antitumor properties of effector cells stimulated with a cell wall preparation (WPG) of Bifidobacterium infantis

Intestinal Bifidobacterium species are thought to be beneficial in animal and human intestines. We studied the mechanisms of Bifidobacteria in antitumor activity using a cell wall preparation (WPG) of B. infantis (Cancer Res., 45, 1300, (1985)). WPG enhanced the in vitro antitumor activities of mouse peritoneal exudate cells elicited with proteose-peptone (P-PEC) and thioglycollate broth (TG-PEC), determined by cytostatic ([3H]thymidine uptake inhibition) and cytolytic ([3H]uridine release) assays. Tumor necrosis factor-alpha (TNF-alpha) and reactive nitrogen intermediates (RNI) play a role in such augmented cytotoxicity, because anti-TNF-alpha antibody almost completely blocked the increased cytolytic activity of P-PEC in the presence of WPG. Moreover, WPG induced RNI in the supernatant of TG-PEC in a dose-dependent manner. The mRNA expression of several cytokines (IL-1 beta, IL-6, IL-10, IFN-alpha and TNF-alpha) was induced in BALB/c mouse peritoneal cells 3 h after an intraperitoneal injection of WPG (3 h WPG-PEC). However, this expression disappeared from 24 h WPG-PEC, except for that of IFN-alpha. IFN-gamma was not induced. Kinetic studies of the tumor neutralizing activities of the WPG-PECs by means of the in vivo Winn assay revealed that the activity emerged at 1.5 h, became maximal at 3 h and disappeared at 24h. These results indicated that Bifidobacterial WPG is a Biological Response Modifier (BRM) with characteristics similar to those of other bacterial BRMs.

Magnetic resonance imaging of subacute thyroiditis

Clinical, laboratory, and scintigraphic findings, and magnetic resonance (MR) images of three patients with subacute thyroiditis are presented in all three at the time of diagnosis. On T1-weighted images, regions of abnormality with irregular margins and slightly high intensity were demonstrated. On T2-weighted images, markedly increased intensity was shown in the same sites. On follow-up MRI in two patients after treatment, these findings had disappeared or become more normal.

[52-week oral toxicity study of lactitol (NS-4) in dogs followed by 9-week recovery test]

Five male and 5 female beagle dogs were orally given lactitol, a hepatic encephalopathy drug, for 52 weeks at doses of 0, 0.25, 1.25 or 6.25 g/kg/day. A 9 week recovery test was conducted after the discontinuation of the drug treatment. Soft stool, diarrhea, and vomiting were seen in the 1.25 and 6.25 g/kg groups. In the 6.25 g/kg group, bloody stool and increased water consumption were also observed. Urinalysis showed larger amount of the urine volume in the 6.25 g/kg group. The cecum weight of this group was increased without any morphological changes. There were no drug related effects on survival, body weight gain and food consumption. Electrocardiographic, ophthalmoscopic, hematologic and biochemical examinations failed to show any abnormalities related to the drug treatment. The above mentioned changes were satisfactorily reversible. Based on the results obtained, the NOAEL of this study was suggested to be 0.25 g/kg/day.

[Single dose toxicity study of lactitol (NS-4) in dogs]

Male beagle dogs were orally given lactitol, a hepatic encephalopathy drug, in a single dose of 7.5, 15.0 or 30.0 g/kg. Vomiting was seen within 30 minutes after dosing in all treated groups. Diarrhea was observed 3 or 5 hours after dosing in the 15.0 and 30.0 g/kg dose groups. There were no drug related effects on survival, food and water consumption, body weight gain or tissues and organs.