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Y Kohli

Publications and source records attributed to Y Kohli.

At least 37 records · Page 2Linked to original sources
PubMed1998

Random association among alleles in clonal populations of Sclerotinia sclerotiorum.

Multiple loci identified in DNA fingerprints were used to test for random association in two agricultural populations of S. sclerotiorum. In linkage disequilibrium tests among pairs of loci with frequencies between 0.1 and 0.9, 44.5 and 80.5% of pairs of loci were consistent with random association in the clone-corrected samples of the Canadian canola and the North Carolina cabbage populations, respectively. In estimates of corrected (Bonferroni) P value, 70.66 and 98.89% of pairs of loci were in random association. All four possible genotypes for each pair of loci were observed in the Canadian canola sample, consistent with random association among loci. In multilocus association tests across all loci, however, significant association was observed in both populations. In the Canadian canola population, 40 possible heterokaryons were identified. Our data suggest that populations of S. sclerotiorum are predominantly clonal and that occasional genetic exchange and recombination, and not mutation alone, may be a source of new genotypes.

Alleles↗
PubMed1998

Full-length sequence analysis of the vacA gene from cytotoxic and noncytotoxic Helicobacter pylori.

Some clinical isolates of Helicobacter pylori fail to express vacuolating cytotoxin, despite possessing a copy of the vacA gene on the chromosome. To gain insight into the differences between vacA from cytotoxic and noncytotoxic strains, the vacA open-reading frames from 16 cytotoxic and 22 noncytotoxic strains were sequenced. Mutations that cause truncation of VacA in 11 of 22 noncytotoxic strains were identified, including internal duplication, large deletion, 1-bp insertion, and non-sense mutations. In contrast, none of the 16 cytotoxic strains had any truncation of VacA. Four cytotoxic strains had inserted sequences downstream of vacA. Three were mini-IS605, and the other was a putative rfaJ gene that encodes lipopolysaccharide glucosyltransferase. The rfaJ gene identified in this study had a poly(C) tract, resulting in premature termination of the gene product. The phylogenetic tree based on the vacA open-reading frame indicated that two different H. pylori lineages are circulating in Japan and the West.

Bacterial Proteins↗
PubMed1998

[Non-real-time computed tomography-guided percutaneous ethanol injection therapy for hepatocellular carcinoma undetectable by ultrasonography].

The purpose of this study was to evaluate the feasibility of non-real-time CT-guided percutaneous ethanol injection therapy (PEIT) for hepatocellular carcinoma (HCC, 37 lesions) untreatable by ultrasonography-guided (US)-PEIT. The HCC lesion was localized on the lipiodol CT image with a graduated grid system. We advanced a 21 G or 22 G needle in a stepwise fashion with intermittent localization scans using a tandem method to position the tip of the needle in the lesion. Ethanol containing contrast medium was injected with monitoring scans obtained after incremental volumes of injection, until perfusion of the lesion was judged to be complete. A total of 44 CT-PEIT procedures were performed. The average number of needle passes from the skin to the liver in each CT-PEIT procedure was 2.3, the average amount of ethanol injected was 14.4 ml, and the average time required was 49.3 minutes. Complete perfusion of the lesion by ethanol on monitoring CT images was achieved in all lesions with only a single or double CT-PEIT procedure without severe complication. Local recurrence was detected only in 5 lesions. At present, it is more time-consuming to perform CT-PEIT than US-PEIT because conventional CT guidance is not real-time imaging. However, it is expected that this limitation of CT-PEIT will be overcome in the near future with the introduction of CT fluoroscopy. In conclusion, CT-PEIT should prove to be a feasible, acceptable treatment for challenging cases of HCC undetectable by US.

Aged↗
PubMed1997

Susceptibility of Helicobacter pylori isolates to metronidazole, clarithromycin and amoxycillin in vitro and in clinical treatment in Japan.

BACKGROUND: Primary and acquired resistance to antibiotics is an important factor in determining the reason for treatment failure in Helicobacter pylori infection. We examined the relationship between the susceptibility of H. pylori isolates and the efficacy of chemotherapy. METHODS: The minimal inhibitory concentrations (MICs) of metronidazole (MNZ), clarithromycin (CLAR) and amoxycillin (AMOX) of 320 H. pylori pre-treatment isolates were determined by the agar dilution method. In 290 patients with peptic ulcers. H. pylori infection was treated by dual or triple combination therapies for 2 weeks: one proton pump inhibitor (30 mg/day lansoprazole or 20 mg/day omeprazole) and one or two antibiotics (500 mg AMOX, 200 mg CLAR or 250 mg MNZ twice a day). MICs were also determined after the treatment failure. RESULTS: Among the drugs tested, for MNZ and CLAR, 8.1% and 9.1% of the isolates, respectively, were resistant, while no isolate was resistant to AMOX. After unsuccessful treatment using MNZ and CLAR, 66.7% and 70.61% of the isolates changed from sensitive to resistant, respectively. All isolates were sensitive to AMOX after treatment failure. CONCLUSIONS: The failure of the H. pylori treatment results in the induction of resistance to CLAR and/or MNZ. Regimens with a high cure rate should be used in order to prevent the generation of acquired resistance to antibiotics.

Adolescent↗
PubMed1997

Analysis and typing of the vacA gene from cagA-positive strains of Helicobacter pylori isolated in Japan.

Approximately 50% of Helicobacter pylori strains produce a cytotoxin that is encoded by vacA and that induces vacuolation of eukaryotic cells. Mosaicism in vacA alleles was reported, and there are three different families of vacA signal sequences (s1a, s1b, and s2) and two different families of middle-region alleles (m1 and m2). In addition, the vacA genotype of a strain is associated with its cytotoxin phenotype and its capacity to induce peptic ulceration. To clarify the strain diversity of H. pylori in Japan, 87 Japanese clinical isolates of H. pylori (40 from patients with chronic atrophic gastritis, 25 from patients with duodenal ulcer, 16 from patients with gastric ulcer, 3 from patients with both duodenal and gastric ulcers, and 3 from patients with intestinal type gastric cancer) were characterized by vacA typing by PCR and DNA sequencing. Eighty-four of the 87 isolates were s1a/m1, one was s1b/m1, and two could not be typed. Moreover, all isolates in this study were cagA positive. There were no distinct differences between the cytotoxin-producing strains and cytotoxin-nonproducing strains within the 0.73-kb middle region. Japanese strains were highly homologous, with more than 96% identity in this region, in which maximum divergence has been reported. In addition, there were no associations between the specific vacA types and the level of in vitro cytotoxin activity or the clinical consequences. These results indicate that the cagA-positive, s1a/m1-type strains are common in Japan, regardless of the vacA phenotype or clinical outcome.

Antigens, Bacterial↗
PubMed1997

Effects of Helicobacter pylori eradication therapy on hyperammonaemia in patients with liver cirrhosis.

BACKGROUND AND AIMS: Helicobacter pylori has strong urease activity. Ammonia produced by H pylori in the stomach can be a source of systemic ammonia in patients with hepatic dysfunction. The effect of the eradication of H pylori on hyperammonaemia was examined in patients with liver cirrhosis. SUBJECTS AND METHODS: Ammonia concentrations in blood and gastric juice were analysed in 50 patients with liver cirrhosis and hyperammonaemia. All patients were first treated with a low protein diet, kanamycin, lactulose, and branched chain enriched amino acid solution. Hyperammonaemia remained in 18 patients. These 18 patients were divided into three groups according to the status of H pylori infection; those with a diffuse distribution of H pylori in the stomach (group I), those with a regional distribution (group II), and those without H pylori (group III). These patients were given 30 mg iansoprazole, 1000 mg amoxicillin, and 400 mg clarithromycin or 500 mg metronidazole for two weeks to eradicate H pylori. RESULTS: In group I ammonia concentrations in blood and gastric juice were significantly reduced after H pylori eradication. The blood ammonia concentration at 12 weeks after the eradication was still significantly lower than that before eradication. In groups II and III the ammonia concentrations in blood and gastric juice were not significantly reduced after eradication therapy. CONCLUSIONS: The diffuse distribution of H-pylori in the stomach contributes partly to hyperammonaemia in patients with liver cirrhosis, and the eradication of H pylori is effective in patients with hyperammonaemia with diffuse H pylori infection in the stomach.

Adult↗
PubMed1996

Cytotoxin and urease activities of Helicobacter pylori isolates from Japanese patients with atrophic gastritis or duodenal ulcer.

The vacuolating cytotoxin and urease secreted by Helicobacter pylori are thought to be virulent factors. Because vacuolation is potentiated by the presence of ammonium ion, which is produced by urease in vitro, it is of interest to examine whether cytotoxin and urease work reciprocally in the development of atrophic gastritis or duodenal ulcer. In the present study, patients (all H. pylori-positive) were divided into four groups: mild atrophic gastritis (group 1; nine patients), severe atrophic gastritis (group 2; 36 patients), duodenal ulcer with mild atrophic gastritis (group 3; 19 patients) and duodenal ulcer with severe atrophic gastritis (group 4; 12 patients). Cytotoxin production and urease activity of H. pylori isolated from these patients were analysed. Cytotoxin production was observed in four of nine (44.4%), 28 of 36 (77.8%), 11 of 19 (57.9%) and eight of 12 (66.7%) isolates from groups 1, 2, 3 and 4, respectively. Cytotoxin-producing H. pylori isolates were found significantly more in patients with severe atrophy than in patients with mild atrophy (P = 0.048). The mean of relative activity of cytotoxin in H. pylori isolate was 1.6 +/- 2.3, 7.9 +/- 7.4, 5.8 +/- 6.0 and 9.0 +/- 9.1 in groups 1, 2, 3 and 4, respectively. Helicobacter pylori isolates from severe atrophy or duodenal ulcer patients in groups 2 or 4 possessed significantly higher activity than those from non-ulcer patients in group 1 (P = 0.017 and 0.030, respectively). The mean of urease activity was 8.6 +/- 4.6, 10.0 +/- 5.9, 10.0 +/- 8.5 and 11.2 +/- 7.7 IU/mg in groups 1, 2, 3 and 4, respectively. These differences indicated no statistical significance. In each H. pylori isolate, the production of cytotoxin and urease were independent, which indicated that there was no reciprocal effect between them in vivo. Thus, cytotoxin-producing H. pylori isolates were more prevalent in patients with severe atrophic gastritis and the cytotoxin activities of H. pylori isolates from the patients with severe atrophic gastritis or duodenal ulcer were much higher than those from the patients with mild atrophic gastritis, which suggested that vacuolating cytotoxin may be a disease-inducing factor.

Bacterial Proteins↗
PubMed1996

Diagnosis of Helicobacter pylori infection.

A number of diagnostic tests have been developed for the detection of H. pylori. Diagnostic techniques can be divided into invasive and noninvasive methods. The invasive methods require upper gastrointestinal endoscopy and involve culture of gastric biopsy specimens, examination of stained biopsies and detection of urease activity in the biopsies themselves. In addition, we have developed endoscopic diagnosis of H. pylori infection in gastric mucosa using phenol red dye-spraying. The noninvasive methods include urea breath test and serological techniques. Although there has been considerable improvement in the techniques, a combination of at least two different techniques should be used in order to optimize the diagnostic yield. We recommend the use of one rapid test in the combination. The rapid urease test, cytology and the phenol red dye-spraying endoscopy give results available before the patient leaves the endoscopy suite.

Helicobacter Infections↗
PubMed1996

Profile of Helicobacter pylori cytotoxin derived from two areas of Japan with different prevalence of atrophic gastritis.

BACKGROUND AND AIM: To clarify the roles of Helicobacter pylori cytotoxin in gastric atrophy, the cytotoxin positive rate and cytotoxin activity in Fukui and Okinawa, where the prevalence of atrophic gastritis and gastric cancer risk are quite different, were studied. MATERIALS: Seventy three strains from Fukui and 51 from Okinawa were examined. METHODS: The validation of atrophy was done by endoscopy, being confirmed with histology. The supernatant of liquid H pylori culture media was concentrated 20-fold, serially diluted, using doubling dilutions, and scored from 1 to 8. The semi-quantitated cytotoxin activity was expressed as the maximum dilution score yielding > 50% A431 cell vacuolation, being standardised with bacterial density. RESULTS: The cytotoxin activity of the strains from Fukui was highly diverse compared with that from Okinawa, although the cytotoxin positive rate was not different. In Fukui strains, the grade of atrophy and the cytotoxin activity were correlated (p < 0.05). In addition, the cytotoxin activity of the strains from all patients in Okinawa, most of whom showed closed-type/mild atrophy, was significantly lower than that of the strains from the patients with open-type/severe atrophy in Fukui (6.46 (5.53) v 9.76 (8.80), p < 0.05), (mean (SEM)). CONCLUSION: The difference in profile of the cytotoxin activity in the two areas was related to the difference in the prevalence of atrophic gastritis.

Adult↗
PubMed1995

Electron microscopic study of endogenous peroxidase activity in human liver macrophages.

We evaluated the conditions of fixation for ultrastructurally demonstrating the endogenous peroxidase (PO) activity of macrophages in biopsied human liver. The application of microwaving and immersion fixation with tannic acid and aldehydes allowed excellent visualization of PO activity in the nuclear envelope (NE), rough endoplasmic reticulum (rER), and cytoplasmic granules (CG), with good preservation of cellular ultrastructures. The macrophages with PO activity showed one of the following five patterns of PO localization: positive in both the NE and rER but negative in the CG (type 1); negative in both the NE and rER but positive in the CG (type 2); negative in the NE but positive in both the rER and CG (type 3); positive in all three (type 4); PO negative (type 5). The type 1 cells resembled typical Kupffer cells, type 2 cells monocytes, and type 3 and 4 cells the exudate-resident macrophages considered to be a transitional form between exudate and resident macrophages. Type 5 cells may also be a transitional form between the exudate and resident macrophage, or an end-stage macrophage derived from exudate macrophages which have lost their PO activity. Tannic-acid-aldehyde immersion fixation with microwaving may be a useful method in the study of the PO activities of macrophages in biopsied human liver specimens.

Cell Nucleus↗
PubMed1995

A proton pump inhibitor, E3810, has antibacterial activity through binding to Helicobacter pylori.

Helicobacter pylori infection is causally related to atrophic gastritis, and it may also be associated with peptic ulcer and gastric carcinoma. Eradication of H.pylori is recommended in patients with such diseases, especially in those with peptic ulcer. A new potent proton pump inhibitor, E3810, had an antibacterial effect on H. pylori, as has been reported for omeprazole and lansoprazole, two other proton pump inhibitors. The minimum inhibitory concentration of E3810 was 1.57-3.13 micrograms/ml, lower than that of omeprazole or lansoprazole. To clarify the mechanism of the antibacterial effect of E3810, we analyzed the characteristics of E3810 binding to H. pylori. Scatchard plot analysis of this binding showed a curvilinear profile, indicating the presence of several molecules with different affinities to E3810 on H. pylori. The binding capacity of E3810 to H. pylori was calculated to be about 2 x 10(6) sites/cell. These results suggested that E3810 has an antibacterial effect against H. pylori and that the effect may be mediated through direct binding to H. pylori.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Lansoprazole treatment of Helicobacter pylori-positive peptic ulcers.

Forty-nine patients with Helicobacter pylori (Hp)-positive gastric ulcer (GU) and 39 patients with Hp-positive duodenal ulcer (DU) were studied. Before the trial and every 3 or 4 weeks, phenol red dye spraying endoscopy, the rapid urease test, biopsy specimen histology, and culture were performed to assess the ulcer stage and to detect Hp. Patients were divided into three groups: group I received lansoprazole 30 mg/d; Group II received dual therapy of lansoprazole 30 mg/day and amoxicillin (AMPC) 1 g/day or clarithromycin (CAM) 400 mg/day; and Group III received combination therapy of lansoprazole 30 mg/day, AMPC 1 g/day, or CAM 400 mg/day, and metronidazole 500 mg/day. Patients with GU received lansoprazole for 8 weeks and patients with DU received lansoprazole for 6 weeks. The other agents were administered for 2 weeks at the beginning of the trial. There were no differences in ulcer healing among the three treatment groups in patients with GU or DU, but there were significant differences in the eradication of Hp. No side effects were observed in any of the patients. We conclude that combination therapy is likely to be most effective and is harmless for Hp-persistent patients with peptic ulcer.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Fulminant Mycoplasma pneumoniae pneumonia with marked elevation of serum soluble interleukin-2 receptor.

We treated a married couple who developed Mycoplasma pneumonia at the same time, and whose clinical courses and serum soluble interleukin-2 receptor (sIL-2R) levels were markedly different. The 30-year-old wife developed acute respiratory failure and her sIL-2R levels were extremely increased. After pulse therapy, her clinical state was improved, with a marked decrease in sIL-2R. In contrast, the 36-year-old husband, also suffered from the pneumonia with a moderate increase of sIL-2R, and recovered without any complications. The difference in their clinical states may be reflected in their serum sIL-2R levels, a marker of T cell activation in vivo.

Acute Disease↗
PubMed1995

Immunogenetic analysis of the human leukocyte antigen DQA1 locus in patients with duodenal ulcer or chronic atrophic gastritis harbouring Helicobacter pylori.

AIM: To examine the human leukocyte antigen (HLA)-DQA1 locus in patients harbouring Helicobacter pylori with chronic atrophic gastritis or duodenal ulcer as part of an investigation into immunogenetic differences in the host. SUBJECTS AND METHODS: We examined 116 patients harbouring H. pylori (55 patients with chronic atrophic gastritis, 61 with duodenal ulcers) and 28 H. pylori-negative healthy controls for HLA-DQA1 genotypes. H. pylori infection was determined by culturing biopsy samples from the gastric body and antrum and by enzyme-linked immunosorbent assay. HLA-DQA1 typing was carried out by the polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: The allele frequency of DQA1*0102 was significantly higher in H. pylori-negative controls (0.250) than in H. pylori-positive duodenal ulcer patients (0.090). In contrast, the allele frequency of DQA1*0301 was significantly lower in H. pylori-negative controls (0.214) than in H. pylori-positive duodenal ulcer patients (0.418). CONCLUSION: These results suggest that there are genetic differences in the HLA-DQA1 locus between H. pylori-positive duodenal ulcer patients and H. pylori-negative healthy controls.

Adult↗
PubMed1995

Differences in urease activity in live Helicobacter pylori cultured from patients with gastroduodenal diseases.

AIM: To develop a reliable method for measuring urease activity in live bacteria, and to determine whether there are any differences in urease activity among the Helicobacter pylori strains involved in gastroduodenal disease. DESIGN: The stability of the method was examined in the first phase of the study, and in a second phase the mean urease activity in clinical isolates from different groups of patients was compared. MATERIALS AND METHODS: To assess the stability and reliability of the method, we assessed the relationship between bacterial proliferation and urease activity, the relationship between the number of bacteria and the optical density, and differences in urease activity among bacterial generations. Ten of the 3-day-old colonies in the third generation were suspended in phosphate-buffered saline, and urease activity was measured as 10(5) colony-forming units/ml bacteria. RESULTS: The assay system appeared to be effective, because the urease activity of live bacteria in the logarithmic growth period was constant, the number of bacteria and the optical density showed a linear correlation on a bilogarithmic graph and there was no significant difference in urease activity over three generations. With this method, urease activity varied from 0.192 to 80.42 mIU/10(5) colony-forming units of bacteria/ml. There was no significant difference in the mean urease activity of live bacteria from controls, gastric ulcer patients and duodenal ulcer patients. However, the mean urease activity in bacteria from cancer patients was significantly higher than that of controls or duodenal ulcer patients. CONCLUSIONS: H. pylori strains derived from cancer patients, which have relatively high levels of urease activity, might easily colonize the stomach and lead to much mucosal damage during the long course of H. pylori infection.

Adult↗