Specific properties of enteropathogenic Escherichia coli isolates from diarrheal patients and comparison to strains from foods and fecal specimens from cattle, swine, and healthy carriers in Osaka City, Japan.

For exhaustive detection of diarrheagenic Escherichia coli, we previously developed a colony-hybridization method using hydrophobic grid-membrane filters in combination with multiplex real-time PCR. To assess the role of domestic animals as the source of atypical enteropathogenic E. coli (aEPEC), a total of 679 samples (333 from foods, fecal samples from 227 domestic animals, and 119 from healthy people) were examined. Combining 48 strains previously isolated from patients and carriers, 159 aEPEC strains were classified by phylogroup, virulence profile, and intimin typing. Phylogroup B1 was significantly more prevalent among aEPEC from patients (50%) and bovine samples (79%) than from healthy carriers (16%) and swine strains (23%), respectively. Intimin type ß1 was predominant in phylogroup B1; B1-ß1 strains comprised 26% of bovine strains and 25% of patient strains. The virulence profile groups Ia and Ib were also observed more frequently among bovine strains than among porcine strains. Similarly, virulence group Ia was detected more frequently among patient strains than strains of healthy carriers. A total of 85 strains belonged to virulence group I, and 63 of these strains (74%) belonged to phylogroup B1. The present study suggests that the etiologically important aEPEC in diarrheal patients could be distinguished from aEPEC strains indigenous to humans based on type, such as B1, Ia, and ß1/γ1, which are shared with bovine strains, while the aEPEC strains in healthy humans are different, and some of these were also present in porcine samples.

Coprological survey of parasitic infections in pigs and cattle in slaughterhouse in Osaka, Japan.

A coprological survey was performed at a slaughterhouse in Osaka, Japan, from 2004 to 2007 on 129 pigs reared in 8 prefectures, and on 213 cattle reared in 21 prefectures. Eimeria spp., Trichuris suis, Ascaris suum and Metastrongylus spp. infections were found in 52 (40.3%), 32 (24.8%), 19 (14.7%) and 3 pigs (2.3%), respectively, while Eimeria spp., Capillaria bovis and Trichuris sp. infections were detected in 163 (76.5%), 15 (7.0%) and 8 cattle (3.8%), respectively. Our results suggest that environmentally resistant oocysts and eggs of parasites could be widespread at the farms examined.

Genetical survey of novel type of Cryptosporidium andersoni in cattle in Japan.

Previously, we reported that an isolate of novel type of Cryptosporidium andersoni detected in cattle in Japan contained Type A (identical to C. andersoni reported previously) and Type B (having a thymine nucleotide insertion unlike the Type A) genotypes in the 18S rRNA gene. Here, we conducted an extensive investigation of Cryptosporidium infections in adult cattle in Japan from 2004 to 2007. Consequently, Cryptosporidium sp. were detected in 12 of the 205 cattle examined (5.9%), and partial sequences of the Cryptosporidium oocyst wall protein (COWP) gene in all isolates were identical to those of the previously reported data for C. andersoni whereas two signals were observed in the sequence of the partial 18S rRNA gene in all the isolates. In transmission studies using five of the isolates, they all infected SCID mice. Modified multiplex PCR using DNA of a single oocyst isolated from the infected SCID mice revealed that the partial sequences in the 18S rRNA gene of 40-80% of 10 isolates were identical to the Type A genotype of C. andersoni and those of other samples were identical to the Type B genotype. These results suggested that the C. andersoni novel type is widespread in cattle throughout Japan, and have multiple copies (Types A and B) in the 18S rRNA gene.

Detection of a mixed infection of a novel Cryptosporidium andersoni and its subgenotype in Japanese cattle.

Cryptosporidium oocysts were detected in the feces of cattle in Saga, Japan. Isolates were morphologically large. We attempted to identify the species or genotypes of the isolates by analyzing the partial sequences of the 18S rRNA and Cryptosporidium oocyst wall protein (COWP) genes, and measuring the infectivity in mice. The isolates showed 100% homology with Cryptosporidium andersoni in the COWP gene sequence and it could be transmitted to mice, but in the 18S rRNA gene, there was an additional signal in the ABI sequence chromatogram. To examine the additional signal, we analyzed both the 18S rRNA and the COWP gene sequences of a single oocyst passaged from mice using a modified multiplex PCR that was able to amplify both genes. As a result, it was revealed that two distinct genotypes (Types A and B) of a novel C. andersoni type existed in the 18S rRNA gene, whereas the COWP gene sequences of both oocysts were identical to C. andersoni. Although the sequence of the 18S rRNA gene of Type A was identical to that of C. andersoni, that of Type B had a thymine insertion and was not identical to any sequence registered with GenBank. Here we report that this is a new type of C. andersoni.

Reinforcement learning accounts for moody conditional cooperation behavior: experimental results.

In social dilemma games, human participants often show conditional cooperation (CC) behavior or its variant called moody conditional cooperation (MCC), with which they basically tend to cooperate when many other peers have previously cooperated. Recent computational studies showed that CC and MCC behavioral patterns could be explained by reinforcement learning. In the present study, we use a repeated multiplayer prisoner's dilemma game and the repeated public goods game played by human participants to examine whether MCC is observed across different types of game and the possibility that reinforcement learning explains observed behavior. We observed MCC behavior in both games, but the MCC that we observed was different from that observed in the past experiments. In the present study, whether or not a focal participant cooperated previously affected the overall level of cooperation, instead of changing the tendency of cooperation in response to cooperation of other participants in the previous time step. We found that, across different conditions, reinforcement learning models were approximately as accurate as a MCC model in describing the experimental results. Consistent with the previous computational studies, the present results suggest that reinforcement learning may be a major proximate mechanism governing MCC behavior.

Atrial fibrillation and atrial vulnerability in patients with Brugada syndrome.

OBJECTIVES: We sought to study atrial vulnerability in patients with Brugada syndrome. BACKGROUND: Atrial fibrillation (AF) often occurs in patients with Brugada syndrome, but atrial vulnerability in Brugada syndrome has not been evaluated. METHODS: The patient group consisted of 18 patients with Brugada syndrome. The control group consisted of 12 age- and gender-matched subjects who had neither organic heart disease nor AF episodes. The incidence and clinical characteristics of AF were evaluated in all 18 patients with Brugada syndrome, and an electrophysiologic study was performed in all 12 control subjects and in 14 of the 18 patients with Brugada syndrome. The atrial effective refractory period of the right atrium (RA-ERP), intra-atrial conduction time (conduction time from the stimulus at the right atrium to atrial deflection at the distal portion of the coronary sinus), duration of local atrial potential, and repetitive atrial firing (occurrence of two or more premature atrial complexes after atrial stimulation) were studied. RESULTS: Spontaneous AF occurred in 7 of the 18 patients with Brugada syndrome but in none of the control subjects. The RA-ERP was not different between the two groups. The intra-atrial conduction time was increased in the Brugada syndrome group versus the control group (168.4 +/- 17.5 vs. 131.8 +/- 13.0 ms, p < 0.001). The duration of atrial potential at the RA-ERP was prolonged in the Brugada syndrome group versus the control group (80.3 +/- 18.0 vs. 59.3 +/- 9.2 ms, p < 0.001). Repetitive atrial firing was induced in nine patients with Brugada syndrome and in six control subjects. Atrial fibrillation was induced in eight patients with Brugada syndrome but in none of the control subjects. In patients with Brugada syndrome without spontaneous AF, the intra-atrial conduction time and duration of atrial potential were also increased. CONCLUSIONS: Atrial vulnerability is increased in patients with Brugada syndrome. Abnormal atrial conduction may be an electrophysiologic basis for induction of AF in patients with Brugada syndrome.

Ventricular arrhythmia induced by sodium channel blocker in patients with Brugada syndrome.

OBJECTIVES: We administered pilsicainide chloride, a class Ic pure sodium channel blocker, to patients with Brugada syndrome (BS) and evaluated the occurrence of ventricular arrhythmia (VA) and T-wave alternans (TWA). BACKGROUND: Ventricular arrhythmia and TWA are sometimes induced by a sodium channel blocker challenge test in BS patients, but the significance of the induced VA and TWA is not known. METHODS: Pilsicainide was administered to 65 patients with BS (10 symptomatic and 55 asymptomatic patients), and the occurrence of VA, TWA, and change of electrocardiogram were evaluated. Electrophysiologic study was performed in 57 patients, and the induction of VA by programmed electrical stimulation (PES) was evaluated. RESULTS: Ventricular arrhythmia was not induced by administration of pilsicainide in 55 patients (no-VA group). Administration of pilsicainide-induced VA in 10 patients (Pil-VA group) and polymorphic ventricular tachycardia in four patients. Pilsicainide-induced VA in 60% of the symptomatic patients but in only 7% of asymptomatic patients (p < 0.01). ST level, QTc, and indexes of cardiac conduction in the Pil-VA group were not different from those in the no-VA group. Ventricular fibrillation was induced by PES in 67% of the patients in the Pil-VA group and in 33% of the patients in the no-VA group. In six cases, macroscopic TWA occurred in association with pilsicainide-induced VA, but TWA occurred in only one patient without pilsicainide-induced arrhythmia. CONCLUSIONS: Administration of a sodium channel blocker results in induction of not only ST-elevation but also VA and TWA in patients with BS.