AC field effect flow control of EOF in complex microfluidic systems with integrated electrodes

In this work, we demonstrate that positive net flow can be induced and controlled with relatively low potential due to the parallel alignment of the integrated channel electrodes. Therefore, we present a novel method to exquisitely control Electro Osmotic Flow (EOF) by using integrated electrodes fabricated beneath a meandering channel geometry (Figure 1). Equation 1 describes EOF velocity for AC-driven flow, where εo and εr respectively are the permittivity of vacuum and that of water, ζ the zeta potential at the solid liquid interface, η the viscosity, Ex the electric field

Detection of Pathogens with Impedance Analysis in a Lab on a Chip

In this work, we demonstrate an impedance approach to detect pathogens bound to magnetic beads. The approach was demonstrated with C-Albicans. We show that when an appropriate frequency is applied to two electrodes present in a microfluidic channel the impedance change in the detection volume can be used to distinguish between unbound beads and beads bound to pathogens. Furthermore, we present a model to relate measured impedance changes to an effective particle diameter

Role of the rdxA and frxA genes in oxygen-dependent metronidazole resistance of Helicobacter pylori

Almost 50 % of all Helicobacter pylori isolates are resistant to metronidazole, which reduces the efficacy of metronidazole-containing regimens, but does not make them completely ineffective. This discrepancy between in vitro metronidazole resistance and treatment outcome may partially be explained by changes in oxygen pressure in the gastric environment, as metronidazole-resistant (MtzR) H. pylori isolates become metronidazole-susceptible (MtzS) under low oxygen conditions in vitro. In H. pylori the rdxA and frxA genes encode reductases which are required for the activation of metronidazole, and inactivation of these genes results in metronidazole resistance. Here the role of inactivating mutations in these genes on the reversibility of metronidazole resistance under low oxygen conditions is established. Clinical H. pylori isolates containing mutations resulting in a truncated RdxA and/or FrxA protein were selected and incubated under anaerobic conditions, and the effect of these conditions on the MICs of metronidazole, amoxycillin, clarithromycin and tetracycline, and cell viability were determined. While anaerobiosis had no effect on amoxycillin, clarithromycin and tetracycline resistance, all isolates lost their metronidazole resistance when cultured under anaerobic conditions. This loss of metronidazole resistance also occurred in the presence of the protein synthesis inhibitor chloramphenicol. Thus, factor(s) that activate metronidazole under low oxygen tension are not specifically induced by low oxygen conditions, but are already present under microaerophilic conditions. As there were no significant differences in cell viability between the clinical isolates, it is likely that neither the rdxA nor the frxA gene participates in the reversibility of metronidazole resistance

Equivalent Helicobacter pylori infection rates in Lynch syndrome mutation carriers with and without a first-degree relative with gastric cancer

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Effectiveness of endosponge therapy for the management of presacral abscesses following rectal surgery

Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Adverse events related to low dose corticosteroids in autoimmune hepatitis

Background: Autoimmune hepatitis requires long‐term therapy, and systemic cor‐ ticosteroids are the backbone of therapeutic management. Prolonged use of corti‐ costeroids may lead to adverse events but data from long‐term studies are mainly derived from studies in rheumatic diseases. Aim: To assess cataract, diabetes and fractures in relation to corticosteroid doses in the long‐term maintenance treatment of patients with autoimmune hepatitis. Methods: We retrospectively collected data on 476 patients (77% women) with an established diagnosis of autoimmune hepatitis. Binary logistic regression with a gen‐ eralised estimating equation was used to analyse the association between current corticosteroid use and the incidence of cataract, diabetes and fractures with onset after autoimmune hepatitis diagnosis. We corrected for sex, age, cirrhosis at diagno‐ sis and predniso(lo)ne use in the prior 3 years to account for possible ongoing effects. Results: A total of 6634 years, with a median of 13 (range 1‐40) per patient were recorded. The median age at diagnosis was 44 years (range 2‐88). Adverse events were documented in 120 (25%) patients. Low‐dose predniso(lo)ne (0.1‐5.0 mg/d) in‐ creased the odds of fractures whereas higher doses (>5.0 mg/d) increased the odds of cataracts and diabetes. Budesonide increased the odds of cataract and fractures; this effect was independent of predniso(lo)ne use in the prior 1, 2 or 3 years. Conclusions: Even low doses of corticosteroids frequently lead to substantial ad‐ verse events refuting the assumption that adverse events are prevented by adminis‐ tering low doses

Real-time composition determination of gas mixtures

In this paper we describe the development of a model and system to analyse the compositions of gas mixtures up to 4 components. We present measurements with binary and ternary mixtures, on compositions with components that range over an order of magnitude in the value for the measured physical properties. The system is consists of a coriolis, density, pressure and thermal flow sensor. With this system it is possible to measure the viscosity, density, heat capacity and flow rate of the medium. We demonstrate that if the properties of the individual components are known, binary mixtures can be analyzed within 1 % and ternary within 2 % accuracy

Six-year follow-up after successful triple therapy for Helicobacter pylori infection in patients with peptic ulcer disease

Objective & Design We question whether Helicobacter pylori eradication in peptic ulcer disease patients leads to a decrease in symptoms and reduced use of anti-dyspeptic drugs. Therefore, the recurrence rate of H. pylori, upper abdominal symptoms and the use of acid-suppressive drugs were determined 6 years after successful triple therapy. Methods Peptic ulcer disease patients successfully treated in 1990-1993 with 'classic' triple therapy were eligible. Patients were asked about symptoms and invited for a C-13-urea breath test or endoscopy in 1997-1998. Data on the use of anti-dyspeptic drugs were obtained from the pharmacy or general practitioner. Results Of the 113 eligible patients, 90 could be included in the study. The mean follow-up time was 6 years (range 4.6-7.6 years). H. pylori infection recurred in one patient (recurrence rate: 0.19% per patient-year; 95% confidence interval: 0.01-1.1%). Moderate or severe symptoms were experienced before therapy by 79% of the patients and after therapy by 18% of the patients (P <10-7). Before triple therapy, 98% of the patients used H-2-receptor antagonists and 54% were on maintenance treatment. 54% Conclusions Six years after successful triple therapy in peptic ulcer disease patients, the recurrence rate of H. pylori infection is low and both symptoms and the use of anti-dyspeptic drugs have decreased significantly. Eur J Gastroenterol Hepatol 13:1235-1239 (C) 2001 Lippincott Williams & Wilkins