bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of gastro‐oesophageal flap valve is useful for diagnosing gastro‐oesophageal reflux disease
Authors: IWAMOTO M. , KATO K. , MIZUNO S. , MIYAMOTO S. , TAKEUCHI R. , IWASAKI A. , ARAKAWA Y.
Published: June 2006

Background

Gastro‐oesophageal flap valve (GEFV) grade correlated with endoscopic reflux oesophagitis (RE) prevalence.

Aim

To investigate relationships among gastro‐oesophageal reflux disease (GERD) symptoms, RE and/or non‐erosive reflux disease (NERD) and GEFV grades in subjects undergoing endoscopy.

Methods

We enrolled 1305 subjects from whom endoscopic results and the results of a self‐administered questionnaire (QUEST) were available. Subjects were evaluated for GERD symptoms (QUEST score), GEFV grade, RE and gastric mucosal atrophy.

Results

Total GERD prevalence, including symptomatic GERD (QUEST score ≥ 4) and/or RE, was 27%. RE grade and prevalence increased with GEFV grade. QUEST scores and GEFV grades showed a positive correlation. NERD prevalence was 14% and increased with GEFV grade, but the relationship was weaker than that between RE and GEFV. Comparing RE‐negative subjects by GEFV grade, GERD symptoms were noted in 10%, 19%, 36% and 52% with GEFV grades I, II, III and IV, respectively. Neither type of gastric mucosal atrophy correlated with GEFV grade.

Conclusions

Total GERD, NERD and RE prevalences increased with GEFV grade. Subjects with high GEFV grades often complain of GERD symptoms, even without RE. Our findings suggest that endoscopic GEFV evaluation provides a useful clinical index for diagnosing GERD.
Review article: duodenal bicarbonate – mucosal protection, luminal chemosensing and acid–base balance
Authors: KAUNITZ J. D. , AKIBA Y.
Published: June 2006

The duodenum serves as a buffer zone between the stomach and the jejunum. Over a length of only 25 cm, large volumes of strong acid secreted by the stomach must be converted to the neutral–alkaline chyme of the hindgut lumen, generating large volumes of CO2.

The duodenal mucosa consists of epithelial cells connected by low‐resistance tight junctions, forming a leaky epithelial barrier. Despite this permeability, the epithelial cells, under intense stress from luminal mineral acid and highly elevated Pco2, maintain normal functioning.

Bicarbonate ion uniquely protects the duodenal epithelial cells from acid‐related injury. The specific protective mechanisms likely involve luminal bicarbonate secretion, intracellular pH buffering and interstitial buffering. Furthermore, the duodenum plays an active role in foregut acid–base homeostasis, absorbing large amounts of H+ and CO2.

We have studied mucosal protection and acid–base balance using live‐animal fluorescence ratio microimaging and by performing H+ and CO2 balance studies on duodenal perfusates. On the basis of these data, we have formulated novel hypotheses with regard to mucosal protection.
Evaluation of alcohol metabolism in humans using the non‐invasive [13C]‐ethanol breath test – influence of gender, Helicobacter pylori infection and polymorphism of alcohol‐oxidizing enzymes
Authors: SUZUKI M. , TANAKA S. , KOMATSU H. , NAKANE T. , SASAKI N. , MARUYAMA K. , SUZUKI H. , ISHII H. , SUEMATSU M. , HIBI T.
Published: June 2006

Background

The [13C]‐ethanol breath test (EBT) has been proposed as a novel non‐invasive laboratory test to detect the degradation of ethanol into CO2. However, this method has not yet been evaluated clinically.

Aim

To investigate the factors that influence [13C]‐EBT.

Methods

Twenty‐six healthy volunteers were instructed to drink 100 mL of beer (4 g ethanol) containing 100 μL of [13C]‐ethanol. Breath samples were collected every 15 min before and after the intake of ethanol solution and 13CO2‐enrichment was measured using mass spectrometry. CO2 excretion was then calculated, and the results were evaluated using kinetic parameters (Tmax, Cmax, AUC).

Results

T
max (min) was significantly shorter in men than in women but not Cmax and AUC. Infection with H. pylori had no impact on all kinetic parameters. Genetic alcohol dehydrogenase (ADH) polymorphisms did not affect 13CO2 excretion, but Cmax (11.1 ± 3.4% dose/h, n = 16) and AUC (10.5 ± 3.4% dose) were slightly increased in aldehyde dehydrogenase (ALDH)‐deficient individuals (heterozygote of ALDH2*2) (13.2 ± 3.2 and 12.9 ± 4.5, respectively; n = 10).

Conclusions

[13C]‐EBT is capable of assessing the metabolic processing of 100 mL beer in a non‐invasive way. Kinetic parameters are partially influenced by ALDH polymorphism but not by gender, H. pylori infection or ADH polymorphism.
Hypoxia‐inducible factor‐1 alpha and vascular endothelial growth factor expression in ischaemic colitis and ulcerative colitis
Authors: OKUDA T. , AZUMA T. , OHTANI M. , MATSUNAGA S. , MASAKI R. , SATOMI S. , INAGAKI T. , MURAMATSU A. , LEE S. , SUTO H. , ITO Y. , YAMAZAKI Y. , ITO S. , KURIYAMA M.
Published: June 2006

Background

Hypoxia‐inducible factor‐1 alpha (HIF‐1 alpha) is a transcriptional factor induced by ischaemic crisis in many tissues. Vascular endothelial growth factor (VEGF) is an important growth factor that plays a major role in angiogenesis.

Aim

We examined the aetiology and pathophysiology of human ischaemic colitis and ulcerative colitis from the viewpoint of the expression of these two ischaemic factors.

Methods

Thirty‐two patients with ischaemic colitis, 16 with ulcerative colitis and 25 normal controls underwent colonoscopy. Biopsy samples were taken from a colitis lesion and a normal region in the same patient. In the normal controls, four biopsy samples were obtained from each subject. Biopsy samples were subjected to real‐time polymerase chain reaction.

Results

Hypoxia‐inducible factor and VEGF were overexpressed in ischaemic colitis lesions and quickly decreased to normal levels in the healing phase. In contrast, HIF but not VEGF was overexpressed in active ulcerative colitis lesions. In the remission phase of ulcerative colitis, VEGF decreased to low levels, although HIF was continuously overexpressed.

Conclusions

Overexpression of HIF and VEGF contribute to the tolerance of ischaemia in patients with active ischaemic colitis. The inconsistency in their expression might be associated with the chronic intestinal damage characteristic of ulcerative colitis.
Effect of eradication of Helicobacter pylori on genetic instabilities in gastric intestinal metaplasia
Authors: TANAKA A. , WATARI J. , TANABE H. , MAEMOTO A. , FUJIYA M. , ASHIDA T. , DAS K. M. , KOHGO Y.
Published: June 2006

Background

There is little evidence of changes in genetic variations in gastric intestinal metaplasia (GIM) after the eradication of Helicobacter pylori (H. pylori).

Aim

To investigate the effects of H. pylori eradication on genetic GIM variability in patients with and without gastric cancer in a one‐year prospective study.

Methods

We analysed microsatellite instability (MSI) and loss of heterozygosity (LOH) in GIM. Subjects included Gr. A (n = 39): chronic gastritis, and Gr. B (n = 53): intestinal‐type early gastric cancer patients who underwent endoscopic mucosal resection (n = 25) and surgical resection (n = 28).

Results

The frequency of incidence of MSI in GIM was 10.3% and 28.3% for Gr. A and Gr. B, respectively. Gr. B showed a significantly (p = 0.03) higher incidence rate than Gr. A for MSI, but not for LOH. The frequency of MSI declined in both groups post‐eradication, and patients that were positive for MSI before treatment were negative after H. pylori eradication. Unfortunately, however, GIM scores did not decline significantly post‐treatment for either group.

Conclusions

MSI in GIM may be associated with gastric carcinogenesis. H. pylori eradication reduced MSI during the one‐year post‐treatment period, although no histological improvement in GIM was observed. These changes in MSI may explain the decrease in gastric cancer incidence after the eradication of H. pylori.
Coinfection of Helicobacter pylori and Neisseria subflava is closely associated with lymph follicle formation in human stomach
Authors: NAKAMURA M. , MATSUI H. , SERIZAWA H. , MURAYAMA S. Y. , YAMAGUCHI T. , TAKAHASHI T. , MATSUMOTO T. , YAMADA H. , HIBI T. , TSUCHIMOTO K.
Published: June 2006

Background

Many reports have described coinfection of Helicobacter pylori and other bacteria in the gastric mucosa in humans. However, relatively few have reported the relation of coinfection with pathological characteristics.

Aim

To culture and identify bacteria other than H. pylori from the gastric mucosa of 64 patients undergoing scheduled gastric biopsy for various gastric conditions. The relation of coinfection with the pathological changes was also investigated.

Methods

From colonies showing characteristics different to those of H. pylori, bacteria were identified by the 16S rRNA gene sequence using FASTA. Cluster analysis was performed using GENETYX‐MAC and a phylogenetic tree was constructed using the UPGMA method. The correlation of pathological observation and the existence of identified bacteria and H. pylori were also analysed.

Results

Forty‐eight per cent of patients were positive to H. pylori, and 27% were positive to Neisseria species. Coinfection of the two bacterial existences was significantly linked. DNA sequencing studies revealed these Neisseria strains to coincide mostly with Neisseria subflava. With regard to the interaction of pathological characteristics, Neisseria and H. pylori coinfection was closely related to lymph follicle formation.

Conclusions

Coinfection of H. pylori and N. subflava was found to be closely related to lymph follicle formation.
Molecular mechanisms involved in interleukin‐8 production by normal human oesophageal epithelial cells
Authors: YOSHIDA N. , IMAMOTO E. , UCHIYAMA K. , KURODA M. , NAITO Y. , MUKAIDA N. , KAWABE A. , SHIMADA Y. , YOSHIKAWA T. , OKANOUE T.
Published: June 2006

Background

Increase in interleukin‐8 in the oesophageal mucosa has been associated with the pathogenesis of reflux oesophagitis.

Aim

To assess the effect of bile acids on the interleukin‐8 expression in normal human oesophageal epithelial cells and to determine its molecular mechanisms.

Methods

Human oesophageal epithelial cells were stimulated with unconjugated bile acids, conjugated bile acids and inflammatory cytokines. Protein and mRNA of interleukin‐8 were measured by enzyme‐linked immunosorbent assay and quantitative real‐time polymerase chain reaction, respectively. In addition, we examined protein kinases and transcription factors involved in interleukin‐8 synthetic pathways using protein kinase inhibitors and luciferase expression vectors, respectively.

Results

Unconjugated bile acids induced interleukin‐8 production from human oesophageal epithelial cells stronger than conjugated bile acids. However, conjugated bile acids in acidic media resulted in remarkable increase of interleukin‐8 production compared with those in neutral‐pH media. Mutation of the binding site of NF‐kB, AP‐1 and NF‐IL6 abrogated the induction of luciferase activities by 100%, 70% and 30%, respectively. Inhibitor of protein kinase A, protein kinase C or p38 mitogen‐activated protein kinase attenuated the production of interleukin‐8 by cholic acid.

Conclusions

These results indicate that bile acids induce interleukin‐8 expression from oesophageal epithelial cells mainly via the activation of NF‐kB as well as AP‐1.
Review article: anti‐tryptase therapy in inflammatory bowel disease
Authors: YOSHIDA N. , ISOZAKI Y. , TAKAGI T. , TAKENAKA S. , UCHIKAWA R. , ARIZONO N. , YOSHIKAWA T. , OKANOUE T.
Published: June 2006

A number of studies have shown that activated mast cells are involved in the pathogenesis of inflammatory and allergic diseases.

Tryptase is one of the serine proteases that stored almost exclusively in the secretory granules of mast cells. It acts to induce microvascular leakage, the chemotaxis of inflammatory cells, and stimulates the release of inflammatory cytokines through the mitogen‐activated protein kinase /activator protein‐1 pathway and protease‐activated receptor (PAR) nuclear factor‐κB pathway.

Recent studies have strongly indicated that tryptase and PAR are implicated in the pathogenesis of inflammatory bowel disease and experimental colitis.

The effect of anti‐tryptase therapy on human inflammatory bowel disease and experimental colitis has been demonstrated. The result of a pilot study has revealed that systemic administration of a specific tryptase inhibitor is safe and there is evidence of activity in the treatment of ulcerative colitis. Recently, we found that nafamostat mesilate, which selectively inhibits tryptase activity at low concentration, could reduce intestinal inflammation in rats. In addition, nafamostat mesilate enema improved clinical and endoscopic findings in ulcerative colitis patients, resistant to conventional therapy such as corticosteroids and sulfasalazine/5‐aminosalicylic acid.

These studies suggest that anti‐tryptase therapy may represent a new therapeutic strategy for human inflammatory bowel disease.
Gene expression clusters of a lipopolysaccharide‐stimulated pathway in peripheral blood monocytes of Japanese patients with Crohn's disease
Authors: NAITO Y. , TAKAGI T. , MIZUSHIMA K. , UETA M. , KINOSHITA S. , HANDA O. , KOKURA S. , ICHIKAWA H. , YOSHIDA N. , YOSHIKAWA T.
Published: June 2006

Background

Recent reports support the notion that patients with Crohn's disease have a dysregulated innate immune response to endogenous flora.

Aim

To reveal the distinct gene expression clusters of a lipopolysaccharide‐stimulated pathway in the peripheral blood monocytes of Japanese patients with Crohn's disease.

Materials and methods

Total RNA was extracted from peripheral blood monocytes of four patients in the remission stage of Crohn's disease as well as four controls, and gene expression profiles before and after lipopolysaccharide stimulation were investigated using a high‐density oligonucleotide probe array. To focus on innate immunity, the expression of genes to be studied was narrowed down to 118 probe sets which were selected using the following keywords: lipopolysaccharide, toll, myd and tir along with a software of NetAffx Analysis Center.

Results

Using hierarchical clustering analysis, we picked up to 44 and 36 probe sets for which expression had decreased before and after lipopolysaccharide stimulation, respectively, in patients with Crohn's disease compared with healthy volunteers. The expression of TLR5, 7, MyD88, SIGIRR, and Tollip was decreased both before and after lipopolysaccharide stimulation in patients with Crohn's disease.

Conclusion

We found several interesting clusters in monocytes before and after stimulation with lipopolysaccharide. These genes may have been responsible for the immunological differences between the Crohn's disease and control patients.
Phase I study of paclitaxel plus irinotecan combination therapy for patients with refractory and advanced gastric cancer
Authors: KOBAYASHI T. , SAKAGAMI T. , KOIZUKA H. , YAMAMOTO N. , SASAKI T. , MAEDA Y. , OMURO Y. , OKAMOTO R. , MIKOSHIBA M. , SASAKI E. , MATSUMOTO T. , MIWA H.
Published: June 2006

Background

No adequate second‐line chemotherapy regimen for advanced gastric cancer is available.

Aims

To determine the safety and optimal dose of paclitaxel/irinotecan as a second‐line chemotherapy for patients with advanced and recurrent gastric cancer.

Patients and methods

Sixteen patients with refractory and advanced measurable gastric cancer who were resistant to 5‐FU plus cis‐diamminedichloroplatinum (CDDP) therapy (FP) were enrolled. Paclitaxel/irinotecan was given intravenously on days 1, 8, and 15 in repeated 4‐week cycles. Paclitaxel/irinotecan doses were escalated in a stepwise fashion as follows: 50/40 mg/m2, 50/50 mg/m2, 50/60 mg/m2, 60/60 mg/m2, 60/70 mg/m2 in levels I, II, III, IV and V, respectively.

Results

Because of one patient with Grade 3 febrile neutropenia at level I, three more patients were enrolled in level I. Doses were consequently escalated, and in level IV, Grade 3 febrile neutropenia occurred in one patient. Since an additional patient in level IV had grade 4 neutropenia, Level IV was judged as the maximum tolerated dose (MTD). The recommended dose and schedule for phase II study is paclitaxel 50 mg/m2 and irinotecan 60 mg/m2 on days 1, 8, and 15 every 4 weeks. Partial response was observed in 4 of 16 patients.

Conclusion

Paclitaxel/irinotecan combination regimen at the level III dosage was safe and well tolerated.
Discrimination between gastric ectopic pancreas and mesenchymal tumours, including GIST – from 12 years‘ surgical experience in one institute
Authors: OTANI Y. , YOSHIDA M. , SAIKAWA Y. , WADA N. , KUBOTA T. , KUMAI K. , SUGINO Y. , MUKAI M. , KAMEYAMA K. , KITAJIMA M.
Published: June 2006

Background

Although recent immunochemical analysis enabled the discrimination of gastrointestinal stromal tumour (GIST) to other mesenchymal tumours, preoperative diagnosis of these tumours is not always easy.

Aim

To discriminate between ectopic pancreas (EP) and mesenchymal tumours, including GIST, 12 years surgical experience at Keio University Hospital was reviewed.

Methods

Clinicopathological findings were analysed for 131 patients with gastric submucosal tumours (SMT), including GIST (67 cases), myogenic tumour (21 cases), Schwannoma (11 cases), EP (12 cases) and others (20 cases) surgically treated at Keio University Hospital since 1993.

Results

Analysis of clinicopathological findings of these tumours showed that GIST, myogenic tumour and Schwannoma mimic each other from the standpoint of size and location of the tumour. In contrast, comparison of mesenchymal tumours showed that, compared with gastrointestinal mesenchymal tumour, EP tends to exist at middle or lower third of the stomach (P = 0.004), and the tumour size was smaller than 3 cm (P = 0.0006). All EPs were laparoscopically resected and no malignant features were evident.

Conclusion

To avoid unnecessary surgery for EP, SMT smaller than 3 cm occurring in the middle or lower third of the stomach should be carefully selected as a candidate of surgical resection.
Twelve years’ progress in surgery for perforated gastric and duodenal ulcers: a retrospective study of indications for laparoscopic surgery, post‐operative course and the influence of Candida infection
Authors: NAKAMURA T. , YOSHIDA M. , OTANI Y. , KAMEYAMA K. , ISHIKAWA H. , KUMAI K. , KUBOTA T. , SAIKAWA Y. , KITAJIMA M.
Published: June 2006

Background

Twelve years has passed since we introduced laparoscopic surgery for gastroduodenal perforation.

Aim

To list problems and to investigate the feasibility of our clinical protocol for treatment of gastroduodenal ulcer perforation.

Methods

Case records of 62 patients and histology samples of 9 patients undergoing surgery for gastroduodenal perforation were retrospectively reviewed.

Results

Laparoscopic omental implantation is feasible for some cases of perforated peptic ulcer in patients who have either stenosis or massive perforations. In patients undergoing laparoscopic omental implantation, oral ingestion of water was started at 3.3 ± 0.5 post‐operative days. Helicobacter pylori was positive in 27 of 35 patients (77%). Of 22 cases in whom intraoperative ascitic culture was taken, Candida was positive in nine (41%), and in six of eight cases involving wound infection or intraperitoneal abscess. Histological examination of resected stomach revealed the fungi with hypha formation at the base of the ulcer in 44% of patients.

Conclusions

Laparoscopic omental implantation was more feasible than in the past. The possibility of Candida infection and subsequent abscess formation must be considered in patients with gastroduodenal ulcer perforation.
Endoscopic classifications as diagnostic factors of peptic ulcer and early gastric cancer – a possible reason why Helicobacter pylori infection causes gastric ulcers along lesser curvature
Authors: YOSHIDA M. , SAIKAWA Y. , HOSODA S. , KUMAI K. , KUBOTA T. , ISHIKAWA H. , NAKAMURA T. , NAKAMURA R. , KAMEYAMA K. , TAKAHASHI S. , KURIHARA N. , KITAJIMA M.
Published: June 2006

Background

Endoscopic classifications were reported to reflect the pathophysiology of gastric mucosa. However, relationship between gastric lesions and classifications has not been examined well.

Aim

To investigate the relationship between endoscopic classifications and cancers or ulcers.

Methods

In this study, 487 patients undergoing upper gastrointestinal endoscopy in Takahashi Clinic and 257 patients with early gastric cancer in Keio University Hospital were enrolled.

Results

Incidence of reflux oesophagitis was higher in Helicobacter pylori‐negative patients. K‐form was better in the H. pylori‐positive patients. Most cancers in the patients with the closed‐type or reflux oesophagitis were of undifferentiated types. Incidences of ulcers were highest in C‐2 and C‐3 in which the borders of atrophy cross the medial oblique muscle bundle, the border circular muscle bundle or both, and 94% of ulcers in C‐2 and C‐3 stomach were located along the lesser curvature.

Conclusion

The predominant existence of undifferentiated types in patients with reflux oesophagitis or closed‐type stomach can be useful information for early diagnosis of cancers. The relationship between the Kimura–Takemoto classification and ulcer location may explain why H. pylori infection is related to ulcer formation along the lesser curvature.
Review article: comparative pharmacodynamic review of rabeprazole – focus on day 1 data
Authors: ROBINSON M. , BARONE J.
Published: June 2006

Proton pump inhibitors have become the preferred therapy for gastro‐oesophageal reflux disease and other acid‐related disorders. Without clear‐cut clinical data to help clinicians differentiate the impact of the five currently available proton pump inhibitors on early symptom relief and health‐related quality of life, we can explore potentially relevant differences in pharmacodynamic profiles of these proton pump inhibitors.

In general, rabeprazole 10 and 20 mg achieve greater gastric pH >4 and >3 holding times and area under gastric pH–time curves on day 1 of treatment compared with other proton pump inhibitors.

Superiority in day 1 pharmacodynamic measures corroborates fast antisecretory onset, and supports the premise that rabeprazole will be especially suitable for on‐demand use. In particular, comparisons with omeprazole and esomeprazole suggest better day 1 nocturnal acid control with rabeprazole.
Review article: understanding the pharmacodynamic and pharmacokinetic differences between proton pump inhibitors – focus on pKa and metabolism
Authors: HORN J.
Published: June 2006

Proton pump inhibitors (PPIs) have been shown to be clinically more effective than other antisecretory agents, including H2‐receptor antagonists, in the treatment of acid‐related disorders and are recognized as the treatment of choice in gastro‐oesophageal reflux disease (GERD).1

Five PPIs are currently available in the United States: omeprazole, its S‐enantiomer esomeprazole, lansoprazole, pantoprazole and rabeprazole. PPIs are effective in suppressing gastric acid, controlling GERD symptoms and healing erosive oesophagitis and ulcers.

There are differences in pharmacodynamic and pharmacokinetic profiles among PPIs, including the onset of gastric acid suppression, routes of metabolism and specific drug–drug interactions. Some of these differences may affect the clinical utility of these agents, at least in certain clinical settings. Using rabeprazole as an example, this article investigates some of the pharmacodynamic and pharmacokinetic properties among PPIs, specifically pKa, routes of metabolism and the effect of food.

In addition to reviewing the results of studies with PPIs concerning these factors, this article will define and more fully describe these measures/mechanisms to further our understanding of their impact. Finally, this article discusses the potential clinical significance of these pharmacological properties.
Low-Level Resistance of
Staphylococcus aureus
to Thrombin-Induced Platelet Microbicidal Protein 1 In Vitro Associated with
qacA
Gene Carriage Is Independent of Multidrug Efflux Pump Activity
Authors: Bayer A. S. , Kupferwasser L. I. , Brown M. H. , Skurray R. A. , Grkovic S. , Jones T. , Mukhopadhay K. , Yeaman M. R.
Published: June 2006

Thrombin-induced platelet microbial protein 1 (tPMP-1), a cationic antimicrobial polypeptide released from thrombin-stimulated rabbit platelets, targets the
Staphylococcus aureus
cytoplasmic membrane to initiate its microbicidal effects. In vitro resistance to tPMP-1 correlates with survival advantages in vivo. In
S. aureus
, the plasmid-carried
qacA
gene encodes a multidrug transporter, conferring resistance to organic cations (e.g., ethidium [Et]) via proton motive force (PMF)-energized export. We previously showed that
qacA
also confers a tPMP-1-resistant (tPMP-1
r
) phenotype in vitro. The current study evaluated whether (i) transporters encoded by the
qacB
and
qacC
multidrug resistance genes also confer tPMP-1
r
and (ii) tPMP-1
r
mediated by
qacA
is dependent on efflux pump activity. In contrast to tPMP-1
r
qacA-
bearing strains, the parental strain and its isogenic
qacB
- and
qacC
-containing strains were tPMP-1 susceptible (tPMP-1
s
). Efflux pump inhibition by cyanide
m
-chlorophenylhydrazone abrogated Et
r
, but not tPMP-1
r
, in the
qacA-
bearing strain. In synergy assays, exposure of the
qacA
-bearing strain to tPMP-1 did not affect the susceptibility of Et (ruling out Et-tPMP-1 cotransport). The following cytoplasmic membrane parameters did not differ significantly between the
qacA
-bearing and parental strains: contents of the major phospholipids; asymmetric distributions of the positively charged species, lysyl-phosphotidylglycerol; fatty acid composition; and relative surface charge. Of note, the
qacA
-bearing strain exhibited greater membrane fluidity than that of the parental,
qacB
-, or
qacC
-bearing strain. In conclusion, among these families of efflux pumps, only the multidrug transporter encoded by
qacA
conferred a tPMP-1
r
phenotype. These data suggest that
qacA
-encoded tPMP-1
r
results from the impact of a specific transporter upon membrane structure or function unrelated to PMF-dependent peptide efflux.
Risk Factors for Selection of the L74I Reverse Transcriptase Mutation in Human Immunodeficiency Virus Type 1-Infected Patients
Authors: Wirden Marc , Roquebert Bénédicte , Derache Anne , Simon Anne , Duvivier Claudine , Ghosn Jade , Dominguez Stephanie , Boutonnet Véronique , Ait-Arkoub Zaina , Katlama Christine , Calvez Vincent , Marcelin Anne-Genevieve
Published: June 2006

We analyzed 3,475 human immunodeficiency virus sequences and 241 therapeutic histories. The L74I mutation was carried by 7% of viruses. L74I was strongly associated with T215F, K70R, and V75M/S/T/A mutations and increased with the number of thymidine analog mutations. It seemed to be linked to the use of abacavir or efavirenz.
Intracellular Metabolism and In Vitro Activity of Tenofovir against Hepatitis B Virus
Authors: Delaney William E. , Ray Adrian S. , Yang Huiling , Qi Xiaoping , Xiong Shelly , Zhu Yuao , Miller Michael D.
Published: June 2006

Tenofovir is an acyclic nucleotide analog with activity against human immunodeficiency virus (HIV) and hepatitis B virus (HBV). Tenofovir disoproxil fumarate (tenofovir DF), a bis-alkoxyester prodrug of tenofovir, is approved for the treatment of HIV and is currently being developed to treat chronic hepatitis B. In this report, we further characterize the in vitro activity of tenofovir against HBV as well as its metabolism in hepatic cells. We show that tenofovir is efficiently phosphorylated to tenofovir diphosphate (TFV-DP) in both HepG2 cells and primary human hepatocytes. TFV-DP has a long intracellular half-life (95 h) and is a potent and competitive inhibitor of HBV polymerase (Ki= 0.18 μM). Tenofovir has a 50% effective concentration of 1.1 μM against HBV in cell-based assays, and potency is improved >50-fold by the addition of bis-isoproxil progroups. Tenofovir has previously demonstrated full activity against lamivudine-resistant HBV in vitro and clinically. Here we show that the major adefovir resistance mutation, rtN236T, confers three- to fourfold-reduced susceptibility to tenofovir in cell culture; the clinical significance of this susceptibility shift has not yet been determined. The rtA194T HBV polymerase mutation recently identified in tenofovir DF-treated HIV/HBV-coinfected patients did not confer in vitro resistance to tenofovir as a single mutation or in a lamivudine-resistant viral background. Overall, the antiviral and metabolic profile of tenofovir supports its development for the treatment of chronic hepatitis B.
Emergence of a
Candida krusei
Isolate with Reduced Susceptibility to Caspofungin during Therapy
Authors: Hakki Morgan , Staab Janet F. , Marr Kieren A.
Published: June 2006

Clinical failure associated with reduced susceptibility to caspofungin has been described in
Candida albicans
and
C. parapsilosis
. We report a case of
Candida krusei
infection that progressed despite caspofungin therapy. Reduced microbial susceptibility to all three echinocandins (caspofungin, anidulafungin, and micafungin) was noted but was not associated with mutations in
FKS1
.
Multiple
cis
-Acting Sequences Mediate Upregulation of the
MDR1
Efflux Pump in a Fluconazole-Resistant Clinical
Candida albicans
Isolate
Authors: Hiller Davina , Stahl Stephanie , Morschhäuser Joachim
Published: June 2006

Overexpression of the
MDR1
gene, which encodes a multidrug efflux pump of the major facilitator superfamily, is a frequent cause of resistance to the antimycotic agent fluconazole and other metabolic inhibitors in clinical
Candida albicans
strains. Constitutive
MDR1
overexpression in such strains is caused by mutations in as yet unknown
trans
-regulatory factors. In order to identify the
cis
-acting sequences in the
MDR1
regulatory region that mediate constitutive
MDR1
upregulation, we performed a promoter deletion analysis in the genetic background of an
MDR1
-overexpressing clinical
C. albicans
isolate. We found that several different regions in the
MDR1
promoter can mediate
MDR1
overexpression in this isolate. In contrast, deletion of one of these regions abolished benomyl-induced
MDR1
expression in a
C. albicans
laboratory strain. These results suggest that multiple transcription factors control expression of the
MDR1
efflux pump in
C. albicans
and that the mutation(s) that causes constitutive
MDR1
overexpression and drug resistance in clinical
C. albicans
isolates affects the activities of several of these transcription factors.
Risk Factors for Isolation of Strains Susceptible Only to Polymyxin among Patients with
Pseudomonas aeruginosa
Bacteremia
Authors: Falagas Matthew E. , Koletsi Patra K. , Kopterides Petros , Michalopoulos Argyris
Published: June 2006

We conducted a case-control study to identify risk factors associated with the isolation of
Pseudomonas aeruginosa
strains susceptible only to polymyxin from blood by comparing data between 16 patients with blood isolates that were susceptible only to polymyxins and 40 patients with blood isolates that were susceptible to carbapenems. The multivariable analysis showed that exposure to carbapenems was associated with the development of
P. aeruginosa
bacteremia susceptible only to polymyxin (odds ratio, 9.0; 95% confidence interval, 2.4 to 34.3;
P
= 0.001).
Intrinsic Macrolide Resistance of the
Mycobacterium tuberculosis
Complex Is Inducible
Authors: Andini Nadya , Nash Kevin A.
Published: June 2006

Mycobacterium tuberculosis
is intrinsically resistant to macrolides, a characteristic associated with expression of the
erm
(37) gene. This intrinsic resistance was found to be inducible with clarithromycin and the ketolide HMR3004. Furthermore, underlying the phenotypic induction was an increase in
erm
(37) mRNA levels.
Characterizing the Effects of Caspofungin on
Candida albicans
,
Candida parapsilosis
, and
Candida glabrata
Isolates by Simultaneous Time-Kill and Postantifungal-Effect Experiments
Authors: Clancy Cornelius J. , Huang Hong , Cheng Shaoji , Derendorf Hartmut , Nguyen M. Hong
Published: June 2006

We measured time-kills and postantifungal effects (PAFEs) of caspofungin against
Candida albicans
,
C. parapsilosis
, and
C. glabrata
isolates. One-hour exposure to caspofungin during PAFE experiments accounted for the majority of killing during time-kill experiments. Regrowth of all isolates was inhibited for at least 24 h following drug washout.
Common Region CR1 for Expression of Antibiotic Resistance Genes
Authors: Rodriguez-Martinez Jose-Manuel , Poirel Laurent , Canton Rafael , Nordmann Patrice
Published: June 2006

The CR1 element defined by an
orf513
gene encoding a putative recombinase and a recombination crossover site has been identified upstream of several antibiotic resistance genes in
Enterobacteriaceae
. This CR1 element was shown to bring promoter sequences that play a role in the expression of unrelated antibiotic resistance genes.
Absence of Cochleotoxicity Measured by Standard and High-Frequency Pure Tone Audiometry in a Trial of Once- versus Three-Times-Daily Tobramycin in Cystic Fibrosis Patients
Authors: Mulheran Michael , Hyman-Taylor Pauline , Tan Kelvin H.-V. , Lewis Sarah , Stableforth David , Knox Alan , Smyth Alan
Published: June 2006

We undertook assessment of hearing in patients with cystic fibrosis who were taking part in a large randomized controlled trial of once- versus three-times-daily tobramycin for pulmonary exacerbations of cystic fibrosis (the TOPIC study). All patients were eligible to have standard pure tone audiometry performed across the frequency range of 0.25 to 8 kHz. High-frequency pure tone audiometry over 10 to 16 kHz was also performed with a subset of patients. Audiometry was undertaken at the start of tobramycin treatment, at the end of a 14-day course of treatment, and at follow-up 6 to 8 weeks later. We enrolled 244 patients, of whom 219 (125 children and 94 adults) completed treatment. Nineteen patients were excluded from analysis due to abnormal baseline audiometry. Complete pre- and posttreatment standard audiological data were obtained for 168/219 patients. We found no significant differences in hearing thresholds when they were assessed at the baseline, at the end of treatment, and at follow-up 6 to 8 weeks later were compared. In addition, no significant differences in hearing thresholds were detected between treatment regimens. Similar results were obtained for the subset of 63/168 patients who underwent high-frequency audiometry. We conclude that for a single 14-day course of tobramycin treatment in patients with cystic fibrosis with no preexisiting auditory deficit, no measurable effect on hearing was apparent with either once- or three-times-daily treatment. Estimation of the cumulative cochleotoxic risk in cystic fibrosis patients due to repeated aminoglycoside therapy, as evidenced by the patients excluded from this study due to hearing loss, also requires further characterization.
Polyphenols Reduce Gastritis Induced by
Helicobacter pylori
Infection or VacA Toxin Administration in Mice
Authors: Ruggiero P. , Tombola F. , Rossi G. , Pancotto L. , Lauretti L. , Del Giudice G. , Zoratti M.
Published: June 2006

Helicobacter pylori
colonizes the human gastric mucosa, causing inflammation that leads to atrophic gastritis, and it can cause peptic ulcer and gastric cancer. We show that polyphenol administration to mice experimentally infected by
H. pylori
or treated with VacA toxin can limit gastric epithelium damage, an effect that may be linked to VacA inhibition.
The Antimalarial Artemisinin Synergizes with Antibiotics To Protect against Lethal LiveEscherichia coliChallenge by Decreasing Proinflammatory Cytokine Release
Authors: Wang Jun , Zhou Hong , Zheng Jiang , Cheng Juan , Liu Wei , Ding Guofu , Wang Liangxi , Luo Ping , Lu Yongling , Cao Hongwei , Yu Shuangjiang , Li Bin , Zhang Lezhi
Published: June 2006

In the present study artemisinin (ART) was found to have potent anti-inflammatory effects in animal models of sepsis induced by CpG-containing oligodeoxy-nucleotides (CpG ODN), lipopolysaccharide (LPS), heat-killedEscherichia coli35218 or liveE. coli. Furthermore, we found that ART protected mice from a lethal challenge by CpG ODN, LPS, or heat-killedE. coliin a dose-dependent manner and that the protection was related to a reduction in serum tumor necrosis factor alpha (TNF-α). More significantly, the administration of ART together with ampicillin or unasyn (a complex of ampicillin and sulbactam) decreased mortality from 100 to 66.7% or 33.3%, respectively, in mice subjected to a lethal liveE. colichallenge. Together with the observation that ART alone does not inhibit bacterial growth, this result suggests that ART protection is achieved as a result of its anti-inflammatory activity rather than an antimicrobial effect. In RAW264.7 cells, pretreatment with ART potently inhibited TNF-α and interleukin-6 release induced by CpG ODN, LPS, or heat-killedE. coliin a dose- and time-dependent manner. Experiments utilizing affinity sensor technology revealed no direct binding of ART with CpG ODN or LPS. Flow cytometry further showed that ART did not alter binding of CpG ODN to cell surfaces or the internalization of CpG ODN. In addition, upregulated levels of TLR9 and TLR4 mRNA were not attenuated by ART treatment. ART treatment did, however, block the NF-κB activation induced by CpG ODN, LPS, or heat-killedE. coli. These findings provide compelling evidence that ART may be an important potential drug for sepsis treatment.
Prospective Determination of Plasma Imipenem Concentrations in Critically Ill Children
Authors: Giannoni Eric , Moreillon Philippe , Cotting Jacques , Moessinger Adrien , Bille Jacques , Décosterd Laurent , Zanetti Giorgio , Majcherczyk Paul , Bugnon Denis
Published: June 2006

Plasma imipenem concentrations were measured in 19 critically ill children (median age, 0.8 year; range, 0.02 to 12.9 years). Wide interindividual variations (2 to 4× at peak and >10× at trough concentrations) resulted in unpredictable plasma levels in several children. To avoid subtherapeutic drug levels, we recommend treatment with at least 100 mg/kg of body weight/day of imipenem-cilastatin for critically ill children requiring such therapy.
New Cluster of Plasmid-Located Class 1 Integrons in
Vibrio cholerae
O1 and a
dfrA15
Cassette-Containing Integron in
Vibrio parahaemolyticus
Isolated in Angola
Authors: Ceccarelli Daniela , Salvia Anna Maria , Sami Joana , Cappuccinelli Piero , Colombo Mauro Maria
Published: June 2006

The resistance profile and its correlation with mobile genetic elements were investigated in 11
Vibrio cholerae
O1 and 2
Vibrio parahaemolyticus
clinical isolates, as well as in 1
V. cholerae
O1 and 1
V. cholerae
non-O1 environmental isolate, isolated between 1991 and 1996 in different provinces of Angola. All clinical isolates of
V. cholerae
O1 were resistant to ampicillin, chloramphenicol, trimethoprim, sulfamethoxazole, and tetracycline. They also contained a large conjugative plasmid (p3iANG) with a set of three class 1 integrons harboring
dfrA15
,
blaP1
, and
qacH-aadA8
cassettes, which code for resistance to trimethoprim, beta-lactams, quaternary ammonium compounds, and aminoglycosides, clustered in a 19-kb region. Chloramphenicol (
cat1
), kanamycin (
aph
), sulfonamide (
sul2
), and tetracycline (
tetG
) resistance genes were also carried on the plasmid within the same 19-kb region. A chromosomal integron containing the
dfrA15
cassette was also revealed in
V. parahaemolyticus
strains. SXT integrase genes were present in six
V. cholerae
isolates but apparently were not associated with known SXT-associated resistance genes. This study indicates that plasmids and integrons contributed mainly to the circulation of multiple-drug resistance determinants in
Vibrio
strains from Angola.
Detection of Influenza Viruses Resistant to Neuraminidase Inhibitors in Global Surveillance during the First 3 Years of Their Use
Authors: Monto Arnold S. , McKimm-Breschkin Jennifer L. , Macken Catherine , Hampson Alan W. , Hay Alan , Klimov Alexander , Tashiro Masato , Webster Robert G. , Aymard Michelle , Hayden Frederick G. , Zambon Maria
Published: June 2006

Emergence of influenza viruses with reduced susceptibility to neuraminidase inhibitors (NAIs) develops at a low level following drug treatment, and person-to-person transmission of resistant virus has not been recognized to date. The Neuraminidase Inhibitor Susceptibility Network (NISN) was established to follow susceptibility of isolates and occurrence of NAI resistance at a population level in various parts of the world. Isolates from the WHO influenza collaborating centers were screened for susceptibilities to oseltamivir and zanamivir by a chemiluminescent enzyme inhibition assay, and those considered potentially resistant were analyzed by sequence analysis of the neuraminidase genes. During the first 3 years of NAI use (1999 to 2002), 2,287 isolates were tested. Among them, eight (0.33%) viruses had a >10-fold decrease in susceptibility to oseltamivir, one (0.22%) in 1999 to 2000, three (0.36%) in 2000 to 2001, and four (0.41%) in 2001 to 2002. Six had unique changes in the neuraminidase gene compared to neuraminidases of the same subtype in the influenza sequence database. Although only one of the mutations had previously been recognized in persons receiving NAIs, none were from patients who were known to have received the drugs. During the 3 years preceding NAI use, no resistant variants were detected among 1,054 viruses. Drug use was relatively stable during the period, except for an approximate 10-fold increase in oseltamivir use in Japan during the third year. The frequency of variants with decreased sensitivity to the NAIs did not increase significantly during this period, but continued surveillance is required, especially in regions with higher NAI use.
Use of Probabilistic Modeling within a Physiologically BasedPharmacokinetic Model To Predict Sulfamethazine Residue Withdrawal Times in Edible Tissues in Swine
Authors: Buur Jennifer , Baynes Ronald , Smith Geof , Riviere Jim
Published: June 2006

The presence of antimicrobial agents in edible tissues of food-producing animals remains a major public health concern. Probabilistic modeling techniques incorporated into a physiologically based pharmacokinetic (PBPK) model were used to predict the amounts of sulfamethazine residues in edible tissues in swine. A PBPK model for sulfamethazine in swine was adapted to include an oral dosing route. The distributions for sensitive parameters were determined and were used in a Monte Carlo analysis to predict tissue residue times. Validation of the distributions was done by comparison of the results of a Monte Carlo analysis to those obtained with an external data set from the literature and an in vivo pilot study. The model was used to predict the upper limit of the 95% confidence interval of the 99th percentile of the population, as recommended by the U.S. Food and Drug Administration (FDA). The external data set was used to calculate the withdrawal time by using the tolerance limit algorithm designed by FDA. The withdrawal times obtained by both methods were compared to the labeled withdrawal time for the same dose. The Monte Carlo method predicted a withdrawal time of 21 days, based on the amounts of residues in the kidneys. The tolerance limit method applied to the time-limited data set predicted a withdrawal time of 12 days. The existing FDA label withdrawal time is 15 days. PBPK models can incorporate probabilistic modeling techniques that make them useful for prediction of tissue residue times. These models can be used to calculate the parameters required by FDA and explore those conditions where the established withdrawal time may not be sufficient.
Activity of Retapamulin (SB-275833), a Novel Pleuromutilin, against Selected Resistant Gram-Positive Cocci
Authors: Jones Ronald N. , Fritsche Thomas R. , Sader Helio S. , Ross James E.
Published: June 2006

Retapamulin (SB-275833), the first pleuromutilin to be developed for human topical use, was tested against a selected population of staphylococci and β-hemolytic streptococci. The MIC
90
results for retapamulin were 0.12 μg/ml for
Staphylococcus aureus
and ≤0.03 μg/ml for
Streptococcus pyogenes
; no cross-resistance was observed for organism subsets resistant to oxacillin, erythromycin, or mupirocin.
Quinolones Sensitize Gram-Negative Bacteria to Antimicrobial Peptides
Authors: Campos Miguel A. , Morey Pau , Bengoechea José A.
Published: June 2006

The treatment of infections caused by bacteria resistant to the vast majority of antibiotics is a challenge worldwide. Antimicrobial peptides (APs) make up the front line of defense in those areas exposed to microorganisms, and there is intensive research to explore their use as new antibacterial agents. On the other hand, it is known that subinhibitory concentrations of antibiotics affect the expression of numerous bacterial traits. In this work we evaluated whether treatment of bacteria with subinhibitory concentrations of quinolones may alter the sensitivity to APs. A 1-h treatment of
Klebsiella pneumoniae
with 0.25× the MIC of ciprofloxacin rendered bacteria more sensitive to polymyxins B and E, human neutrophil defensin 1, and β-defensin 1. Levofloxacin and nalidixic acid at 0.25× the MICs also increased the sensitivity of
K. pneumoniae
to polymyxin B, whereas gentamicin and ceftazidime at 0.25× the MICs did not have such an effect. Ciprofloxacin also increased the sensitivities of
K. pneumoniae
ciprofloxacin-resistant strains to polymyxin B. Two other pathogens,
Pseudomonas aeruginosa
and
Haemophilus influenzae
, also became more sensitive to polymyxins B and E after treatment with 0.25× the MIC of ciprofloxacin. Incubation with ciprofloxacin did not alter the expression of the
K. pneumoniae
loci involved in resistance to APs. A 1-
N
-phenyl-naphthylamine assay showed that ciprofloxacin and levofloxacin increased the permeabilities of the
K. pneumoniae
and
P. aeruginosa
outer membranes, while divalent cations antagonized this action. Finally, we demonstrated that ciprofloxacin and levofloxacin increased the binding of APs to the outer membrane by using dansylated polymyxin B.
Pharmacokinetics of Unbound Linezolid in Plasma and Tissue Interstitium of Critically Ill Patients after Multiple Dosing Using Microdialysis
Authors: Buerger Cornelia , Plock Nele , Dehghanyar Pejman , Joukhadar Christian , Kloft Charlotte
Published: June 2006

The antimicrobial agent linezolid is approved for the treatment of severe infections caused by, e.g., methicillin-resistantStaphylococcusstrains. In order to evaluate the penetration of linezolid into the interstitial space fluid (ISF) of subcutaneous adipose tissue and skeletal muscle of the target population, a microdialysis study was performed with 12 patients with sepsis or septic shock after multiple intravenous infusions. Unbound linezolid concentrations were determined for plasma and microdialysates by use of a validated high-performance liquid chromatography method. Individual compartmental pharmacokinetic (PK) analysis was performed using WinNonlin. In vivo microdialysis was found to be feasible for the determination of unbound linezolid concentrations at steady state in the ISF of critically ill patients. On average, linezolid showed good distribution into ISF but with high interindividual variability. A two-compartment model was fitted to unbound concentrations in plasma with a geometric mean distribution volume of 62.9 liters and a mean clearance of 9.18 liters/h at steady state. However, disposition characteristics changed intraindividually within the time course. In addition, an integrated model for simultaneous prediction of concentrations in all matrices was developed and revealed similar results. Based on the model-predicted unbound concentrations in ISF, a scheme of more-frequent daily dosing of linezolid for some critically ill patients might be taken into consideration to avoid subinhibitory unbound concentrations in the infected tissue. The developed integrated model will be a valuable basis for further PK data analysis to explore refined dosing guidelines that achieve effective antimicrobial therapy in all patients by use of the population PK approach.