The effect of enterohemorrhagic Escherichia coli O157:H7 on intestinal structure and solute transport in rabbits

BACKGROUND

The effect of enterohemorrhagic Escherichia coli O157:H7 infection on intestinal morphology and solute transport was examined.

METHODS

New Zealand white rabbits, aged 10 days, were infected with E. coli strain EDL933 (O157:H7 containing the 60-megadalton plasmid-encoding adhesion factors VT1 and VT2) and compared with controls. Small and large intestinal histology and solute transport were studied 5 days after inoculation. Ion transport in the distal colon was also examined in animals infected with different strains encoding a combination of pathogenic factors.

RESULTS

Infection with EDL933 induced diarrhea and mucosal disease in the colon, inhibited colonic Na+ absorption, and stimulated of Cl- secretion, but had no impact on the small intestine. Infection with strains A7785-C3A (O157:H7, plasmid-, VT1+, VT2+) and 85-170 (O157:H7, plasmid+, VT-) induced similar transport changes to EDL933. C600/1 (E. coli K-12, plasmid+, VT1+) decreased Na+ and Cl- absorption only.

CONCLUSIONS

Abnormalities of colonic structure and ion transport could account for diarrhea production, but pathogenic factors other than the 60-megadalton plasmid-encoding adhesion factor and verotoxins appear to be involved in enterohemorrhagic E. coli infection.

Identification of a negative element in the human vimentin promoter: modulation by the human T-cell leukemia virus type I Tax protein

The vimentin gene is a member of the intermediate filament multigene family and encodes a protein expressed, in vivo, in all mesenchymal derivatives and, in vitro, in cell types of various origin. We have previously demonstrated that the expression of this growth-regulated gene could be trans activated by the 40-kDa Tax protein of HTLV-I (human T-cell leukemia virus type I) and that responsiveness to this viral protein was mediated by the presence of an NF-kappa B binding site located between -241 and -210 bp upstream of the mRNA cap site (A. Lilienbaum, M. Duc Dodon, C. Alexandre, L. Gazzolo, and D. Paulin, J. Virol. 64:256-263, 1990). These previous assays, performed with deletion mutants of the vimentin promoter linked to the chloramphenicol acetyltransferase gene, also revealed the presence of an upstream negative region between -529 and -241 bp. Interestingly, the inhibitory activity exerted by this negative region was overcome after cotransfection of a Tax-expressing plasmid. In this study, we further characterize the vimentin negative element and define the effect of the Tax protein on the inhibitory activity of this element. We first demonstrate that a 187-bp domain (-424 to -237 bp) behaves as a negative region when placed upstream either of the NF-kappa B binding site of vimentin or of a heterologous enhancer such as that present in the desmin gene promoter. The negative effect can be further assigned to a 32-bp element which is indeed shown to repress the basal or induced activity of the NF-kappa B binding site.(ABSTRACT TRUNCATED AT 250 WORDS)

Catalysis of the hydrolysis of ethyl mandelate and esterification of alpha-bromopropionic acid by lipase in microemulsions

Candida cyclindracea lipase (CCL) was added to "sodium dodecyl sulfonate (AS)/n-butanol/n-octane/n-octane" water-in-oil microemulsion to catalyze the hydrolysis of ethyl mandelate and the esterification of alpha-bromopropionic acid with n-butanol, respectively. The catalytic activity of CCL in the above microemulsions was higher than that in the traditional oil/water biphasic systems. After hydrolysis for 48 h, the conversion rate of the reaction reached 90% and S-mandelic acid, [alpha]D20-149.8 (C10; H2O), optical purity ca. 97%, was isolated. While after esterification for 6 h, the conversion rate of the reaction reached 45%, and butyl-(R)-alpha-bromopropionate, [alpha]D20 18.2 (Cl; CHCl3), optical purity ca. 99%, was obtained.

Flavone acetic acid and 5,6-dimethylxanthenone-4-acetic acid: relationship between plasma nitrate elevation and the induction of tumour necrosis

Antitumour agents such as flavone acetic acid, xanthenone acetic acid (XAA), 5,6-dimethylxanthenone-4-acetic acid and tumour necrosis factor-alpha, following single dose administration to mice with colon 38 adenocarcinomas, induce tumour haemorrhagic necrosis and an elevation in plasma nitrate. The relationship between these two effects has been studied using firstly a series of methyl-substituted XAA derivatives with varying antitumour activity, and secondly the inhibitors NG-monomethyl-L-arginine (NMMA), N-nitro-L-arginine (NNA) and canavanine, which affect nitric oxide synthesis. Elevation of plasma nitrate resulting from the oxidation of L-arginine by nitric oxide synthase is inhibited by NNA rather than by NMMA or canavanine. The results demonstrate that tumour necrosis can be induced in the absence of a significant elevation of plasma nitrate.

Disorganization of microfilaments and intermediate filaments interferes with the assembly and stability of desmosomes in MDCK epithelial cells

To investigate the possible role(s) of cytoskeletal elements in desmosome assembly we have studied the effects of cytostatic drugs on the assembly of desmosomes in MDCK epithelial cells. We showed previously [Pasdar et al.: Cell Motil. Cytoskeleton 23:201-213, 1992] that selective disruption of microtubules has no effect on desmosome assembly. Here, we have treated MDCK cells with cytochalasin B and a combination of cytochalasin B and nocodazole and analysed the effects of desmosome assembly. Immunofluorescence analysis of MDCK cultures following drug treatment indicated complete disruption of actin microfilaments and disorganization of cytokeratin intermediate filaments. Biochemical analysis of newly synthesized desmosomal membrane core glycoproteins as well as the cell adhesion protein E-cadherin revealed no effect of these drugs on the kinetics of synthesis, intracellular processing, or transport to the plasma membrane either in the presence or absence of cell-cell contact. However, morphological analyses revealed a significant disruption in the spatial organization of desmosomal proteins and E-cadherin. Drug treatment in the absence of cell-cell contact resulted in the disruption of the normally observed homogeneous punctate staining pattern and appearance of aggregate staining. Induction of cell-cell contact in these cultures resulted in redistribution of some of the aggregate staining to the plasma membrane. In contrast to control cultures, significant amount of intracellular staining was retained for all desmosomal proteins. Biochemical analyses of turnover rates of newly synthesized desmosomal proteins indicated a significant decrease in metabolic stability of these proteins while the turnover rate of E-cadherin was not significantly different among control and drug-treated cultures. Taken together, these results suggest that intact actin and cytokeratin filaments are necessary for the stability, efficient assembly, and spatial organization of the junctional components at the membrane. The regulatory role of cytokeratins and actin filaments in assembly and stability of desmosomes on the plasma membrane is discussed.

What does post-adaptation color appearance reveal about cortical color representation?

We examine the implications of the hypothesis that color information in the cortex is adaptively coded into a factorial (statistically independent) and gain-controlled representation. We show that this hypothesis explains the results of the recent experiments by Webster and Mollon [(1991) Nature, 349, 235-238] on changes in color appearance following post-receptoral adaptation. We also give a neural network with a deterministically convergent, unsupervised learning algorithm that reproduces the adaptation observed.

One-dimensional scatter-subtraction method for brachytherapy dose calculation near bounded heterogeneities

Neglect of tissue and applicator heterogeneities in brachytherapy treatment planning is due in part to lack of accurate, general, and fast three-dimensional (3D) dose-computation algorithms. A novel dose-calculation algorithm that accounts for the lateral dimensions and location of the heterogeneity as well as its thickness has been developed. For simple 2D, water-equivalent density heterogeneities, the algorithm is shown to be applicable to a wide range of photon energies and is 500-1000 times more efficient than Monte Carlo photon-transport calculations. The model is based upon reducing the bounded 2D heterogeneity problem to two 1D problems by dividing the scattering volume into two regions: A cone-shaped region that subtends the heterogeneity with its apex at the source and the complementary cone that contributes scatter dose by diffusion around the heterogeneity. The input data consist of precalculated scatter-to-primary ratios (SPRs) for collimated isotropic point sources. The central-axis "mini-beam" problem for a slab heterogeneity is solved by a simple 1D scatter integration model that accounts for both the thickness of the heterogeneity and its location relative to the point of interest. The scatter contribution arising outside the mini-beam is modeled as the difference in SPRs corrected for transmission through the heterogeneity. The algorithm agrees, on average, with sample Monte Carlo calculations within 1% to 7% for 125I, 192Ir, and 100 keV point sources along the axes of water-equivalent cylindrical heterogeneities (rho = 0-12.6 g/cm3, 3.6, and 24 mm diameters, and dose-perturbation factors of 0.44-1.33 relative to the homogeneous case). The potential of generalizing the scatter-subtraction approach to encompass 3D heterogeneities, those consisting of high-atomic number media, and those of irregular shape, is discussed.

Chemical modification of biopolymers--mechanism of model graft copolymerization of chitosan

Mechanism of graft copolymerization of vinyl monomers onto chitosan initiated by Ce(IV) ion, one of the important ways of chemical modification of chitosan, has been investigated by means of kinetics measurement and polymer chain structure analysis. It is found that when Ce(IV) ions reacts with adjacent hydroxylamine structure in chitosan, a chelate complex is first formed and then it disproportionates to radical for initiation of graft copolymerization. There exist two ways for such initiation depending upon the reaction temperature. For a reaction temperature lower than 40 degrees C, a -CHO group and a -C = NH group are introduced, and the aldehyde group reacts with Ce(IV) ions to form an acyl radical which initiates a graft polymer chain in this saccharide unit. For temperatures higher than 90 degrees C, the -C = NH group hydrolyzes to form an amine and an aldehyde group which also reacts with Ce(IV) ions. In this case there should be two aldehyde groups, i.e. two initiation sites, in one adjacent hydroxyl-amine structure. That means that the initial radical in the chitosan/Ce(IV) system is similar to that in the cellulose/Ce(IV) one, but the former usually gives a lower grafting reactivity than the latter due to the higher stability of the chelate.

Comparison of calculated and measured heterogeneity correction factors for 125I, 137Cs, and 192Ir brachytherapy sources near localized heterogeneities

The influence of tissue and applicator heterogeneities on brachytherapy dose distributions is not well understood, despite widespread use of shielded applicators in intracavitary therapy. Heterogeneity correction factors (HCF) have been measured using a silicon diode detector arising from bounded heterogeneities consisting of lead, steel, titanium, silver, aluminum, and air cylinders near brachytherapy sources of 125I, 137Cs, and 192Ir. In addition, transverse-axis dose distributions for the three sources in homogeneous water were measured for distances of 0.2 to 16.0 cm. For each point of measurement, relative diode readings were simulated by a Monte Carlo photon transport code utilizing accurate models of the source internal structure, the experimental measure geometry and the source-strength calibration geometry. Comparison of measured and calculated HCF's reveals excellent agreement (1%-3% average) over a wide range of materials, diameters, and thicknesses. In addition, Monte Carlo simulation not only accurately reproduced the relative transverse-axis dose distributions in homogeneous medium, but was able to predict the variation of diode response with photon energy with an accuracy of 3% over the range of 30-662 keV. Our measurements demonstrate that HCF's vary by as much as 60%-100% with distance and heterogeneity diameter for a fixed thickness. Finally, silicon diode measurements of HCF (denied as reading with heterogeneity/reading in homogeneous medium) is shown to lead to errors of 5%-30% for 137Cs and 192Ir sources in the presence of high-atomic number shielding materials. This paper concludes, that Monte Carlo simulation is a powerful, convenient and accurate tool for investigating the long-neglected area of brachytherapy heterogeneity corrections.

Functional evidence that the angiotensin antagonist losartan crosses the blood-brain barrier in the rat

Losartan is a novel nonpeptidergic antagonist of angiotensin (ANG) II subtype 1 (AT1) receptors, which effectively lowers blood pressure in high-renin hypertensive rat and blocks the pressor response to systemic ANG II. It is well known that high densities of ANG II receptors exist in the hypothalamic paraventricular nucleus (PVN). In addition, activation of putative angiotensinergic afferents to the PVN originating in subfornical organ (SFO) elevates blood pressure and facilitates the activity of PVN neurons. We report here that systemic administration of losartan (3 mg/kg) significantly attenuates the pressor response to electrical stimulation of SFO. The excitatory responses of PVN neurons to SFO stimulation or local pressure microinjection of ANG II were also significantly inhibited in 58.8% and 88.9% of PVN cells, respectively, by intravenous administration of losartan. These pharmacological effects were rapid and reversible, and were accompanied by little change of basal arterial blood pressure or spontaneous neuronal activity. These observations suggest that systemic losartan crosses the blood-brain barrier (BBB) and acts at AT1 receptors within the PVN.

Proteoglycan synthesis by the neointimal smooth muscle cells cultured from rabbit aortic explants following de-endothelialization

Proteoglycans (PGs), the essential component of the extracellular matrix, are implicated in the pathogenesis of atherosclerosis. In an experimental model of injury, PGs accumulate in the neointimal tissue parallel with lipid deposition. However, it is still not clear whether the PG accumulation is from active smooth muscle cell (SMC) production or is a consequence of trapping within neointima covered by endothelium. To study the effect of endothelial injury on PG synthesis, SMCs were cultured from normal aorta (N-SMC), neointima covered by regenerated endothelium (W-SMC) and neointima without endothelium (B-SMC). Using [35S]-Na2SO4, as a precursor in an in vitro incubation, the kinetics of PG synthesis were determined. PG synthesis by all three cell types increases as a function of time. It is significantly higher in the SMCs cultured from endothelium-denuded aortic explants (W- and B-SMC) than N-SMC. This finding indicates that endothelial injury stimulates PG synthesis by SMCs.

Serotonin involvement in the antitumour and host effects of flavone-8-acetic acid and 5,6-dimethylxanthenone-4-acetic acid

The relationship of serotonin (5-HT) receptors to the action of the experimental antitumour drugs flavone-8-acetic acid (FAA) and 5,6-dimethylxanthenone-4-acetic acid (5,6-MeXAA) was studied. Both FAA and 5,6-MeXAA are known to induce the synthesis of tumour necrosis factor-alpha (TNF) and to stimulate nitric oxide synthesis in vivo, as measured by elevation of plasma nitrate. Serotonin potentiated the effect of a subtherapeutic dose of 5,6-MeXAA (20 mg/kg) as measured both by plasma nitrate increase and by growth delay of s.c. implanted colon 38 tumours. On the other hand, administration of the serotonin 5-hydroxytryptamine-2 (5-HT2) antagonist cyproheptadine (20 mg/kg) inhibited both the plasma nitrate response and, to a lesser extent, the induction of tumour haemorrhagic necrosis by 5,6-MeXAA, FAA and TNF. Reduction of circulating plasma serotonin by pre-treatment with p-chlorophenylalanine and reserpine reduced the plasma nitrate response, but not the tumour necrosis response, to 5,6-MeXAA (30 mg/kg). It is suggested that serotonin is necessary for the induction of nitric oxide synthases and acts, either directly or indirectly, in concert with TNF. Serotonin agonists may have utility in increasing nitric oxide synthesis in response to TNF or to agents that induce TNF as part of their antitumour action.

In vitro biosynthesis of GbOse4Cer (globoside) and GM2 ganglioside by the (1-->3) and (1-->4)-N-acetyl beta-D-galactosaminyltransferases from embryonic chicken brain. Solubilization, purification, and characterization of the transferases

(1-->4)-N-Acetyl-beta-D-galactosaminyltransferase (GalNAcT-1) and (1-->3)-N-acetyl-beta-D-galactosaminyltransferase (GalNAcT-2), which are involved in the in vitro biosynthesis of GM2 and GbOse4Cer glycosphingolipids, respectively, have been solubilized and separated by differential detergent extraction from a membrane preparation of 19-day-old embryonic chicken brain. The separated GalNAcT-1 activity had a pH optima of 7.8-8.0, and the separated GalNAcT-2 activity a single pH optimum of 7.2. Furthermore, the partially purified GalNAcT-2 preparation catalyzed the transfer of N-acetylgalactosamine from UDP-D-[3H]GalNAc to only GbOse3Cer and nLcOse5Cer. Both GalNAcT-1 and GalNAcT-2 activities were purified to approximately 316- and 428-fold, respectively, by use of UDP-hexanolamine-Sepharose 4B affinity-column chromatography. However, the partially purified GalNAcT-1 preparation appeared to be active only with GM3, lactosylceramide, and lactotriaosylceramide. The proposed linkage of the N-acetylgalactosamine unit incorporated into GM3 is beta-D-GalpNAc-(1-->4)-GM3 from the isolation of [3H]threitol after hydrolysis of the desialylated, lead tetraacetate-treated, enzymic product, beta-D-GalpNAc-(1-->4)-beta-D-[6-3H]Galp-(1-->4)-beta-D-Glcp-(1-->1)-Cer . In addition, beta-D-GalpNAc-(1-->3)-GbOse3Cer was produced, as shown by the identification of 2,4,6-tri-O-methyl-galactose after permethylation and hydrolysis of the GalNAcT-2 enzymic product, GalpNAc-[6-3H]Galp--->Gal-->Glc-->Cer.

Prognostic factors for survival of patients with bidimensionally measurable metastatic hormone-refractory prostatic cancer treated with single-agent chemotherapy

BACKGROUND

A range of response proportions have been reported using the same single-agent inpatients with hormone refractory prostatic cancer. To assess whether these results were due to imbalances in prognostic factors, the authors evaluated a series of prognostic factors for survival in patients with prostatic cancer treated with chemotherapy.

METHODS

Complete data sets were available in 146 patients, in whom 27 individual variables were considered in univariate analysis. Significant factors (P < 0.05) were then evaluated using regression analysis along with transformations of the data to obtain a Cox and exponential model. The derived model was then evaluated on an independent data set from the National Cancer Institute treated with suramin.

RESULTS

In univariate analysis in order of significance, the serum alkaline phosphate (0.0018), serum lactic dehydrogenase (0.006), prior radiation therapy (0.007), serum aspartate amino transferase (0.02), presence of liver disease (0.033), and pretreatment Karnofsky performance status (0.04) were associated with survival. In the regression analysis, only the log-transformed lactic dehydrogenase (LDH) and normal versus abnormal alkaline phosphatase were significant. This model was confirmed with an independent data set from patients treated with the putative growth factor inhibitor suramin.

CONCLUSIONS

This analysis emphasizes important factors that can be used to stratify patients in future phase II and III trials.

The effect of multi-glycosides of Tripterygium wilfordii Hook f. (GTW) on the survival time of cardiac allografts in rats

Heterotopic heart transplantation was carried out in rats and the influence of multi-glycosides of Tripterygium wilfordii Hook f. (GTW) and a subtherapeutic dose of cyclosporine A (CsA) on the mean survival time (MST) of the cardiac allografts was investigated. The results showed that the MSTs of cardiac allografts in both the GTW and CsA-treated groups were significantly prolonged (P < 0.01 vs control). The rate of allograft rejection in the drug-treated groups was much lower than that in the control group.

Effect of an anti-Mo1 MAb on ozone-induced airway inflammation and airway hyperresponsiveness in dogs

Ozone inhalation causes neutrophil migration into the airway and airway hyperresponsiveness in dogs. The leukocyte adhesion molecule Mo1 (CD11b/CD18) is a heterodimeric glycoprotein the expression of which is necessary for neutrophil adhesion to endothelium. To evaluate the contribution of Mo1 to ozone-induced neutrophil influx and airway hyperresponsiveness, six dogs were treated intravenously with an Anti-Mo1 monoclonal antibody (3.75 mg/kg in normal saline) that binds to both human and canine Mo1, or the diluent alone, 1.5 h before inhaling ozone (3 ppm for 30 min), or dry air. Airway responses to doubling doses of inhaled acetylcholine (ACh) were measured before and after inhalation of ozone. Neutrophil influx was assessed by bronchoalveolar lavage (BAL) performed after the second ACh inhalation. Treatment with anti-Mo1 prevented the ozone-induced influx of neutrophils into BAL. After diluent and inhaled dry air, the neutrophil count in BAL was 1.49 +/- 1.26 (SE) x 10(4) (5.0% of total cells). After diluent and inhaled ozone, the neutrophil count increased to 7.27 +/- 3.22 (SE) x 10(4) (22.6% of total cells) (P < 0.05). After anti-Mo1 and inhaled ozone, the neutrophil count was 1.48 +/- 0.62 (SE) x 10(4) (8.5% of total cells). Treatment with anti-Mo1 also significantly reduced the number of eosinophils in BAL after ozone. Ozone-induced ACh airway hyperresponsiveness was not prevented by treatment with anti-Mo1. These results indicate that expression of Mo1 is necessary for ozone-induced neutrophil migration into the airway lumen.

[Effects of Salvia miltiorrhiza Bunge on isolated perfused liver and portal vein of rats]

The experiment results showed that Salvia miltiorrhiza (SMB) had a protective effect on the isolated perfused liver injured by CCl4 of rats, made the activity of GPT in perfusate of SMB group lower than that of intoxicated groups and relieved the hepato-pathohistologic lesions of SMB group as compared to the intoxicated group. SMB had no significant effects on both the activities of SGPT in vitro and the portal vein of rats.

Change in LDL particle size is associated with change in plasma triglyceride concentration

Low density lipoprotein (LDL) particle size is inversely associated with plasma triglyceride concentration in cross-sectional analyses. In the present study, changes in the LDL particle size of 227 participants of the Framingham Offspring Study were analyzed longitudinally by nondenaturing gradient gel electrophoresis at two examinations that were separated by 3-4 years. All subjects had triglyceride concentrations < 400 mg/dl at both exams. Using laser scanning densitometry to assess mean LDL particle size, 56% of samples displayed a change in size: 41% had a one-band size change, 13% had a two-band change, and 2% had a three-band change. These changes in size corresponded to a 15% change in pattern type, based on pattern A and B terminology. There was a significant inverse association between change in LDL size and change in triglyceride (p < 0.0001) and glucose (p < 0.004) concentrations, body weight (p < 0.02), and age (p < 0.03). There was also a significant positive association with change in high density lipoprotein (HDL) cholesterol concentration (p < 0.0001). Change in LDL cholesterol concentration, as calculated by use of the Friedewald formula, however, showed no significant association with change in LDL size (p < 0.9). There was also no significant association with change in smoking or blood pressure, but there was a nonsignificant inverse trend associated with alcohol intake (p < 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

[Experimental infection with hepatitis E virus in rhesus monkeys]

An experimental model of hepatitis E was established in Rhesus Monkeys. Four animals were inoculated with stool suspensions that obtained from patients with hepatitis E. Two animals injected with PBS were taken as negative controls. After 4-6 weeks the ALT of the four animals infected HEV raised 3-4 times and the live biopsy showed acidophilic degeneration of hepatocytes and coagulative liver cell necrosis. Acidophilic bodies were frequently observed. Foci of lytic single-cell necrosis were also observed. Degenerative and microinflammatory changes in liver parenchyma in zones 1-2 of liver lobules were accompanied by inconspicuous infiltrations in portal tracts. 27-34 nm virus-like particles were recovered from the stools of infection animals by IEM.

Estimation of organ transport function: model-free deconvolution by recursive quadratic programming optimization

A model-free deconvolution method is proposed for evaluating the frequency distribution function of organ transit times. The deconvolution is treated as a nonlinear constrained optimization problem and it is solved by using a modified constrained variable metric approach. The only constraint implemented in the solution is that all the discrete transport function values are not allowed to become negative. The method is tested on model mathematical systems of known analytical transport functions. The tests are performed on systems that included noise in both the input and output functions. The criteria of successful deconvolution are the reconvolution error and, most importantly, the deviation of the computed transport function from the known analytical one. The proposed method is then applied, as a pilot experiment, to biological data obtained from an isolated, perfused rabbit lung preparation contained within a plethysmograph. The results indicate that this type of deconvolution produces stable estimates which faithfully follow the analytical function while negating the need to assume either any functional form for the behavior of the transport function or any educated initial guess of its values.

Molecular characterization of Serpulina (Treponema) hyodysenteriae isolates representing serotypes 8 and 9

The study described here was carried out to further characterize reference strains of Serpulina (Treponema) hyodysenteriae representing serotypes 8 and 9. Results obtained from restriction fragment length polymorphism analysis, enteropathogenicity testing, and endotoxin profiles confirmed their identifications. Electron microscopy indicated that both strains were covered with a thin layer of capsule-like material. Immunoblot analysis indicated that an antigen in the 19-kDa region of proteinase K-digested whole cells reacted only with homologous antiserum. The serotype-specific antigens were sensitive to periodate oxidation but resistant to proteinase K digestion and migrated in the same region as purified lipopolysaccharides. Immunoblotting with proteinase K-digested whole cells appeared as useful as immunodiffusion with extracted lipopolysaccharide for the serological classification of S. hyodysenteriae. Immunogold labeling of whole cells and purified periplasmic flagella showed strong cross-reactions between S. hyodysenteriae and Serpulina innocens. Outer membrane preparations of strains representing serotypes 8 and 9 contained four major proteins which reacted with antisera against both species, and one major protein with a molecular mass of 46 kDa which reacted only with antisera against S. hyodysenteriae, irrespective of the serotype. Our findings suggest that periplasmic flagella and some outer membrane proteins are antigens common to both S. hyodysenteriae and S. innocens, whereas a 46-kDa outer membrane protein may be a species-specific antigen of S. hyodysenteriae. Finally, we propose immunoblotting as an alternative method to immunodiffusion for the serotyping of S. hyodysenteriae.