Age and sex effects on paired-pulse suppression and prepulse inhibition of auditory evoked potentials

Responses to a sensory stimulus are inhibited by a preceding stimulus; if the two stimuli are identical, paired-pulse suppression (PPS) occurs; if the preceding stimulus is too weak to reliably elicit the target response, prepulse inhibition (PPI) occurs. PPS and PPI represent excitability changes in neural circuits induced by the first stimulus, but involve different mechanisms and are impaired in different diseases, e.g., impaired PPS in schizophrenia and Alzheimer's disease and impaired PPI in schizophrenia and movement disorders. Therefore, these measures provide information on several inhibitory mechanisms that may have roles in clinical conditions. In the present study, PPS and PPI of the auditory change-related cortical response were examined to establish normative data on healthy subjects (35 females and 32 males, aged 19-70 years). We also investigated the effects of age and sex on PPS and PPI to clarify whether these variables need to be considered as biases. The test response was elicited by an abrupt increase in sound pressure in a continuous sound and was recorded by electroencephalography. In the PPS experiment, the two change stimuli to elicit the cortical response were a 15-dB increase from the background of 65 dB separated by 600 ms. In the PPI experiment, the prepulse and test stimuli were 2- and 10-dB increases, respectively, with an interval of 50 ms. The results obtained showed that sex exerted similar effects on the two measures, with females having stronger test responses and weaker inhibition. On the other hand, age exerted different effects: aging correlated with stronger test responses and weaker inhibition in the PPS experiment, but had no effects in the PPI experiment. The present results suggest age and sex biases in addition to normative data on PPS and PPI of auditory change-related potentials. PPS and PPI, as well as other similar paradigms, such as P50 gating, may have different and common mechanisms. Collectively, they may provide insights into the pathophysiologies of diseases with impaired inhibitory function.

[Volume reduction surgery for giant coronary sinus with valvular heart disease; report of a case]

A 64-year-old male with giant left atrium and giant coronary sinus, who had aortic valve regurgitation, prosthesis valve paravalvular leakage in mitral position and prosthesis valve malfunction in tricuspid valve position, was successfully treated with double valve replacement, paravalvular leakage repair and volume reduction of left atrium and coronary sinus. Giant coronary sinus was about 70 mm in diameter and was thought to be induced by persistent left superior vena cava, high right atrium pressure and prosthesis valve malfunction in tricuspid valve position. Lung volume was so much increased by volume reduction of left atrium and coronary sinus and patient's symptoms were much improved.

[Full-thickness resection of the focus site for adolescent idiopathic ventricular tachycardia]

We present a case of a 14-year-old male with incessant idiopathic ventricular tachycardia for which both pharmacological and catheter ablation treatments failed. Curative surgery was performed on this patient. By intraoperative epicardial isochronous mapping, arrhythmogenic focus was identified in the right ventricular infundibulum between the large conus branch and the proximal right ventricular coronary branch. After cryoablation both from the epi- and endo-cardial sides failed to terminate the arrhythmia, subsequent full-thickness resection of the identified focus was performed. There was no postoperative recurrence of tachyarrhythmia In idiopathic ventricular tachycardia, arrhythmogenic focus is not always situated on the endo- or epicardial side. Full-thickness resection of the focus site might be necessary in such patients as we experienced this time.

[Off-pump coronary artery bypass and right ventricular branch translocation for coronary aneurysm; report of a case]

The successful surgical treatment for a coronary artery aneurysm was reported. A 38-year-old female presented with angina pectoris due to right coronary artery stenosis. Angiography revealed a right coronary artery aneurysm and 90% stenosis at a site just proximal to the aneurysm, accompanied by the relatively large right ventricular (RV) branch originating from a mid portion of the aneurysm. Off-pump coronary artery bypass grafting (CABG) to the right coronary artery (RCA) #3, translocation of RV branch to RCA #3, and ligation of RCA proximal and distal to the aneurysm were successfully performed. Post-operative course had been uneventful with satisfactory angiographic results. Coronary translocation with CABG could be a treatment option for coronary artery aneurysms.

[Ascending aortic dissection associated with pulmonary contusion caused by blunt trauma]

A 77-year-old female tumbled and struck her front chest wall twice. After the event, hemosputum was observed and she complained of slight chest discomfort. As chest pain continued to worsen a week after the event, she was transferred to our hospital. The computed tomography (CT) revealed an ascending aortic dissection and bilateral pulmonary contusion. In the intensive care unit (ICU), antihypertensive therapy was given immediately and delayed surgical repair was planned because of pulmonary contusion. Twenty days after the event, proximal hemiarch replacement was performed. Postoperative course was uneventful without any complication. She was discharged on the 23rd day after the operation.

[A study on the appropriate time point for the assessment of Helicobacter pylori eradication--evaluation from the re-positive rate of H. pylori after successful eradication and delayed decrease of 13C-urea breath test levels]

We attempted to evaluate the appropriate time point for the assessment of Helicobacter pylori eradication after treatment. One hundred and nine patients with gastroduodenal diseases were enrolled this study. All of them were received proton pomp inhibitor based triple therapy and diagnosed as eradication of H. pylori infection at initial assessment. They were followed up over six months. The diagnosis of H. pylori eradication was determined by rapid urease test, culture, histology and 13C-urea breath test (UBT), and the initial assessment of the eradication was performed on 31-90 days after finishing eradication therapy. Re-appearance rate of H. pylori after initial diagnosis of eradication was 4.6% (5/109), and the mean follow-up period of them was 16.3 months. The time period of initial assessment of eradication in these 5 patients were 35, 37, 42, 49 and 60 days after treatment, respectively. On the other hand, there were 6 patients who were diagnosed as failed of eradication therapy by 13C-UBT, and being success at following period. All of the 13C-UBT levels of these 6 patients were less than 10/1000 and were decreased within negative range subsequently. The time periods of initial diagnosis of these patients except one were within 2 months after treatment. It was concluded that the assessment time of H. pylori eradication should be performed over 2 months after eradication therapy.

Relationship between eradication therapy and clarithromycin-resistant Helicobacter pylori in Japan

Since clarithromycin is expected to be widely used to treat Helicobacter pylori infection in the near future, it is important to investigate the relationship between resistance to clarithromycin and the regimens of eradication therapy. We investigated: (1) the usefulness of susceptibility tests prior to eradication therapy, and (2) the rate of acquisition of H. pylori resistance to clarithromycin after treatment failure. Drug susceptibility tests to clarithromycin and amoxicillin were conducted by Dry Plate Test or E-test. The subjects in the first part of this study included 112 patients with H. pylori infection who received triple therapy with various combinations of drugs, including clarithromycin. The eradication rate in patients with clarithromycin-susceptible H. pylori was significantly higher than that in patients with clarithromycin-resistant H. pylori. The second part of this study included 21 patients in whom H. pylori was not eradicated by triple therapy and 12 patients in whom H. pylori was not eradicated with dual therapy including clarithromycin. Of the 33 patients showing non-eradication. 90.9% of those treated with dual therapy and 35.7% of those treated with triple therapy acquired secondary resistance of H. pylori to clarithromycin. We conclude that it is important to conduct drug susceptibility tests prior to treatment of H. pylori infection. Since the incidence of acquiring clarithromycin resistance was significantly higher in the patients showing non-eradication, it is important to choose a regimen with a higher eradication rate, such as triple therapy.

[Detection of pyrazinamidase activity for differentiation of Campylobacter, Arcobacter, and Helicobacter spp. by using a high-performance liquid chromatography method]

A high-performance liquid chromatography method was investigated for the detection pyrazinamidase activity by Campylobacter, Arcobacter, and Helicobacter spp. Pyrazine carboxilic acid, one of the end products of pyrazinamide hydrolysis by microorganisms, was detected by using a high-performance liquid chromatography (HPLC). A loopful of organism colonies was emulsified in 0.5 ml of a 0.5% pyrazinamide solution. The suspens on was incubated in a 37 degrees C water bath for 18-20 hr. After centrifugation, the supernatant was analyzed by HPLC. This HPLC method does not require microaerobic incubation and was easy to interpret for strains with weak enzymatic activity. By this method, we tested 111 clinical isolates, type and reference strains of Campylobacter spp., Arcobacter spp., and Helicobacter spp. , C. jejuni, C. jejuni subsp. doylei, C. coli, C. upsaliensis, C. lari, C. lari (urease+), C. helveticus, C. hyolei, C. sputorum subsp. fecalis, C. gracilis, C. concisus, C. curvus were positive for pyrazinamidase. C. fetus subsp. fetus, C. hyointestinalis, C. sputorum subsp. sputorum, C. sputorum subsp. bubulus, C. mucosalis, A. butzleri, A. skirrowii, A. cryaerophilus, H. pylori, H. cinaedi, H. fennelliae, H. mustelae, H. felis, H. muridarum, H. canis, H. nemestrinae, H. pamentensis, H. pullourum were negative.

[Evaluation of CO2 condition for antibiotic susceptibility test of Helicobacter pylori on microdilution broth]

We determined the MICs of clarithromycin for 32 Helicobacter pylori strains isolated from gastric mucosa of patients, by using microdilution broth method under different microaerobic conditions (CO2: 5% and 15%). The pH of broth was more acidic at 15% CO2 than that of at 5% CO2. The MICs of clarithromycin for all H. pylori strains at 15% CO2 condition were higher than that of clarithromycin at 5% CO2 condition. Comparing the MICs with the results of eradication therapy, we concluded that the measurement of MIC under 5%CO2 condition is more useful for expecting the clinical outcome.

[Biochemical and molecular characterization of Salmonella ser. enteritidis phage type 1 isolated from food poisoning outbreaks in Tokyo]

Since the first outbreak in 1990, the incidence of Salmonella ser. Enteritidis (S. Enteritidis) phage type (PT) 1 food poisoning has gradually increased in Tokyo and has reached approximately 30% of the total S. Enteritidis outbreaks reported. To characterise these S. Enteritidis PT1 food poisoning, a total of 198 strains obtained from 44 outbreaks between 1990 and 1996 were examined for antimicrobial resistance, acid producibility from glycols (propylene and ethylene glycol) and plasmid DNA profiles. The 44 PT1 outbreaks analysed were further subdivided into 11 types by epidemiological markers. The most common patterns were type A (plasmid profile carrying only one plasmid (60 kb). SM and TC resistance and non producibility from glycols), and type B (plasmid profile carrying two plasmids (60 and 20 kb), SM resistance and no producibility from glycols) and were responsible for 21 (47.7%) and 15 (34.1%) outbreaks, respectively. In 11 of 44 outbreaks, strains carrying identical epidemiological markers were isolated both from patients and vehicle foods, environments, and/or food-handlers. Similar to PT4 and PT34 outbreaks reported in Japan, egg and egg-related foods were also suspected in 8 of these 11 outbreaks. Of interest, chicken which were not pointed out in PT4 and PT 34 outbreaks was also suspected as a vehicle of transmission in two outbreaks.

[Biochemical and molecular characterization of Salmonella serovar enteritidis phage type 4 isolated from food poisoning outbreaks in Tokyo]

Since 1989, outbreaks of Salmonella ser. Enteritidis (S. Enteritidis) food poisoning have dramatically increased in Tokyo, and a total of 31 outbreaks has been reported in 1989. Twenty-one of these 31 outbreaks were caused by S. Enteritidis PT34, but 8 outbreaks were caused by S. Enteritidis PT4. After 1990 instead of SE PT34, food poisoning due to PT4, which was a very common phage type in the UK, has increased in Tokyo. Between 1989 and 1995, there were 144 food poisoning outbreaks caused by S. Enteritidis, and 64 of these outbreaks were by due to S. Enteritidis PT4, which was one of the main phage types in Tokyo. To characterize these strains of phage type (PT) 4,293 isolates from patients, and vehicle foods, eggs and environment in Tokyo were examined for plasmid DNA profiles, acid productivity from glycols (propylene and ethylene) and antimicrobial resistance patterns. Plasmid DNA was extracted by Kado's method, and analyzed by agarose gel electrophoresis. The acid productivity from propylene glycol or ethylene glycol were tested using Barsicow medium with 1% propylene glycol or ethylene glycol. Antimicrobial susceptibility to AM, CP, TC, SM, KM, NA, ST, FOM and NFLX was tested by the K-B disc method. The strains of PT4 were further subdivided into 9 types by those epidemiologic marker analysis. The prevalent pattern of PT4 strains was type A plasmid profile carrying only one plasmid (60 kb) and there were 2 kinds of antibiograms. One was SM resistant, while the other was susceptible. A total of 56 (87.5%) of 64 outbreaks was found to have been caused by these types of S. Enteritidis. Several kinds of egg-related foods were suspected as the vehicles of transmission among 24 outbreaks. Especially, in 5 outbreaks, S. Enteritidis strains were isolated both from patients and suspected food which were cooked with egg. This strongly suggests that these foods may be the potential source of infection in S. Enteritidis PT4 outbreaks.

[Evolution of susceptibilities of Campylobacter jejuni isolated from diarrhoeal cases to fluoroquinolones in Tokyo]

Recently, the increase in the number of resistant strains of Campylobacter jejuni to fluoroquinolone has been reported in European countries. We also studied antimicrobial susceptibilities of 600 clinical isolates of Campylobacter jejuni isolated during a 6 year period from 1989 through 1994 in four Tokyo Metropolitan Hospitals. The susceptibility to 6 antimicrobial agents, norfloxacin (NFLX), ofloxacin (OFLX), ciprofloxacin (CPFX), nalidixic acid (NA), erythromycin (EM) and tetracycline (TC) were examined. The overall resistant rates were as follows: NFLX, 45 strains (7.5%); OFLX, 45 strains (7.5%); CPFX, 44 strains (7.3%); NA, 62 strains (10.3%); EM, 4 strains (0.6%) and TC, 259 strains (43.2%). The number of resistant strains to fluoroquinolones and NA has increased significantly since 1993 in Japan, but the susceptibility to erythromycin has still remained the same level during the past 6 years. The susceptibility to TC was variable, and MICs gave a bimobal distribution, as pointed out previously. The resistance pattern of NFLX, OFLX, CPFX and NA were observed most frequently in those isolates.

[Characterization of Salmonella ser. enteritidis phage type 34 isolated from food poisoning outbreaks in Tokyo by epidemiological makers]

Since 1989, outbreaks of Salmonella ser. Enteritidis food poisoning has dramatically increased in Tokyo, and a total of 95 outbreaks has been reported between 1989 and 1993. As the results of examination of phage type by the method of Ward, et al., strains isolated from 31 (32.6%) of 95 outbreaks were phage type 34 which is a very rare type in Europe and America. To characterize these unique strains of phage type (PT) 34, 302 isolates obtained from patients and vehicle foods of the outbreaks, eggs and environments in Tokyo were examined for plasmid DNA profiles and antimicrobial resistance patterns. Plasmid DNA was extracted by the Kado's method, and analysed by agalose gel electrophoresis. Antimicrobial susceptibility was tested for CP, TC, SM, KM, ABPC, NA, SXT, FOM and NFLX by the K-B disc method. The strains of PT 34 were further subdivided to 4 types by plasmid profile and antibiogram. The prevalent pattern of PT 34 strains was type plasmid profile which carried 2 different plasmids (> 250 and 60 kb) and was streptomysin-resistant. A total of 28 (90.3%) of 31 outbreaks were found to be caused by this specific type of Salmonella ser. Enteritidis. Several kinds of egg-related foods were suspected for the vehicles of transmission among 12 outbreaks. Especially, in 5 outbreaks, this specific type (type B plasmid profile and streptomysin resistant) of Salmonella ser. Enteritidis strains were isolated both from patients and incriminated food which were cooked with eggs. The phase type of Salmonella ser. Enteritidis strains isolated from raw egg and poultry or environmental specimens from poultry farm showed that the prevailing phage types were almost the same as those of foods poisoning outbreaks. This strongly suggests that these foods may be considered as a source of infection in Salmonella ser. Enteritidis outbreaks.

Fumarate hydration test for differentiation of Campylobacter and Helicobacter species

A total of 65 Campylobacter and Helicobacter strains comprising 15 species were tested for fumarate hydration by using a rapid high-performance liquid chromatographic (HPLC) method. All strains of C. jejuni, C. coli, C. jejuni subsp. doylei, C. fetus, C. hyointestinalis, C. lari, "C. lari variant", C. upsaliensis, H. fennelliae and H. pylori hydrated fumarate, whereas no strains of C. sputorum (all three biovars), H. cinaedi or H. mustelae did. L-malic acid was detected in the supernatant of the cultures of all strains that hydrated fumarate, but not in the culture supernatant of any of the strains that failed to hydrate fumarate. These findings show that all Campylobacter and Helicobacter strains that hydrated fumarate were able to form L-malic acid from fumarate. HPLC determination of organic acid is a rapid method that requires no chemical treatment before analysis. Because it is reproducible, the HPLC fumarate hydration test should be useful as conventional method for identification of Campylobacter and Helicobacter spp.

Immunological specificity of Helicobacter pylori urease and identification by immunological detection of its specific urease

Helicobacter pylori urease was recovered as a single peak by DEAE-Sepharose column chromatography and Sephacryl S-200 gel filtration. The purified urease was obtained by fast protein liquid chromatography using a Mono Q column. The purified urease preparation gave a single band in polyacrylamide gel disc electrophoresis. Latex particles were sensitized with anti-urease immunoglobulin. The sensitized latex particles were agglutinated with the purified urease and by cell sonicates obtained from 55 strains of H. pylori which were isolated from the gastric mucosa of patients with gastric and duodenal disorders, while they did not react with those obtained from related bacteria known to be urease producers, such as Helicobacter mustelae and urease- positive "Campylobacter lari variants", or by urease of some strains of Enterobacteriae. We have developed a specific and sensitive method for detecting the urease by using the reversed passive latex agglutination technique, in order to identify of the organism.

[An outbreak of gastroenteritis due to group C rotavirus in Tokyo]

In April 1991, an outbreak of acute gastroenteritis due to group C rotavirus occurred at an elementary school in Tokyo. Fifty-one (13%) of 393 students became ill. The main clinical symptoms were diarrhea (100%), abdominal pain (68%) and vomiting (56%). No enteropathogenic bacteria were found in the fecal specimens. However, the virus particles morphologically indistinguishable from conventional rotavirus were detected in 6 of 11 fecal specimens by electron microscopy. Immune electron microscopy showed that these virions aggregated with anti-group C rotavirus serum. The RNA pattern of the virus particles involved in this outbreak showed a pattern similar to that of typical group C rotavirus on polyacrylamide gel electrophoresis.

[Serological studies on Campylobacter jejuni/coli: establishment of national reference system for serological typing in Japan]

In order to establish a national reference system for Campylobacter serotyping in Japan, 7 local institutes of public health collaborated to prepare 30 serogrouping antisera including 26 antisera of Lior's serogrouping system and 4 antisera of TCK serogrouping system which was developed by the Tokyo Metropolitan Research Laboratory of Public Health. A total of 603 strains (92.2%) out of 654 isolates from 23 outbreaks of C. jejuni throughout Japan were serogrouped by the 30 antisera. Out of 1,198 strain isolated from sporadic cases of Camplyobacter gastroenteritis, 883 (73.7%) were typed and 298 strains (24.9%) were untypable. The remaining 17 strains belong to rough form were not used for serogrouping. A hundred thirteen out of 883 strains have reacted with more than one typing serum. Among C. jejuni isolated from 7 prefecture, Lior's serogroup 4 was most common followed by Lior's serogroup 4, 2, 11, 1 and TCK serogroup 1 and 12. We conclude from the experiment described above that this Lior's serogrouping system by combining with TCK serogroup for Campylobacter jejuni/coli is useful in epidemiological investigations in Japan.

[The serotype distribution of Campylobacter jejuni strains among gastroenteritis in hospitals over 7 year period in Tokyo]

Campylobacter jejuni strains isolated from gastroenteritis at 4 general hospitals of Tokyo Metropolitan during the period from 1981 to 1987 were serotype according to the slide agglutination test (TCK system) developed by the Tokyo Metropolitan Research Laboratory of Public Health. Two thousand four hundred seventy-nine strains isolated from sporadic cases among infants and children, 1,962 (78.5%) were typed by 33 typing sera numbered TCK 1 through TCK 33 and leaving 537 strains (21.5%) untypable. Out of the typable strains, 1,643 strains reacted with only single serum, while 319 strains reacted with 2 or more antisera. The most common serogroups included TCK 21, 20, 7, 1, 4, 23, 24, 10, 30 and 12. Out of the 1,250 strains isolated from sporadic cases among adults, 974 strains (77.9%) were typed and 276 strains were untypable. The most common serogroups were similar to those of infants and children. Serogroups TCK 1, 7, 4 and 21 were consistently the common serogroups every year during the 7 year study. Isolation frequency of serogroup TCK 30 have increased remarkably since 1986, while TCK 23, 14 and 9 have decreased.

Isolation of Campylobacter pyloridis from human gastric mucosa and characterization of the isolates

Biopsy specimens of human gastric mucosa of patients with gastric complaints and subjected to endoscopic examination were cultured microaerobically, and Campylobacter pyloridis was detected in 46 out of 80 cases (57.5%). The organism was found in 13 out of 22 patients with gastritis, 11 out of 16 with gastric ulcer scar, 7 out of 16 with gastric ulcer, 3 out of 9 with gastric polyp, 4 out of 5 with gastric carcinoma, 2 out of 2 with esophagus carcinoma, and 6 out of 9 with other gastric diseases. The isolates were identified as C. pyloridis, demonstrating its characteristic features such as positive for oxidase and catalase, negative for reduction of nitrite and nitrate, positive for urease, no growth at 25 C, growth at 37 C, not tolerant to 1% glycine, and resistant to nalidixic acid. Positive alkaline phosphatase activity was considered as an additional feature characteristic for the strains of C. pyloridis. The major cellular fatty acids were tetradecanoic acid and 19-carbon-cyclopropane acid. This pattern is unique among Campylobacter species. The survival of the organism for a longer period than 60 min at pH 2.5 indicates its significant resistance to acidic environment.

Latex agglutination test for staphylococcal toxic shock syndrome toxin 1

A reversed passive latex agglutination method, in which latex particles were sensitized with specific anti-toxic shock syndrome toxin-1 (TSST-1) immunoglobulin, was found to be a simple and sensitive method for the detection of TSST-1 production by Staphylococcus aureus strains. The minimum amount of TSST-1 detectable was approximately 1.0 ng/ml. Of 41 S. aureus isolates from toxic shock syndrome patients and controls, 23 were positive for TSST-1 production, whereas only 20 strains were positive for TSST-1 production by an Ouchterlony immunodiffusion method. The reversed passive latex agglutination method was used to examine S. aureus strains isolated in Japan from staphylococcal infections, feces from healthy individuals, food from poisoning outbreaks, and market food.