Microchip PCR.

Miniaturization of genetic tests has become an important goal. This review surveys the current progress towards the miniaturization of tests based on the polymerase chain reaction (PCR). It examines the different types of PCR microchip designs, fabrication methods,and the components of a microchip PCR device. It also discusses the problems attributable to surface chemistry of microchip components (inhibition of PCR), and the static and dynamic surface passivation strategies developed for the solution of these difficulties

Microchip module for blood sample preparation and nucleic acid amplification reactions.

A computer numerical control-machined plexiglas-based microchip module was designed and constructed for the integration of blood sample preparation and nucleic acid amplification reactions. The microchip module is comprised of a custom-made heater-cooler for thermal cycling, a series of 254 microm x 254 microm microchannels for transporting human whole blood and reagents in and out of an 8--9 microL dual-purpose (cell isolation and PCR) glass-silicon microchip. White blood cells were first isolated from a small volume of human whole blood (<3 microL) in an integrated cell isolation--PCR microchip containing a series of 3.5-microm feature-sized "weir-type" filters, formed by an etched silicon dam spanning the flow chamber. A genomic target, a region in the human coagulation Factor V gene (226-bp), was subsequently directly amplified by microchip-based PCR on DNA released from white blood cells isolated on the filter section of the microchip mounted onto the microchip module. The microchip module provides a convenient means to simplify nucleic acid analyses by integrating two key steps in genetic testing procedures, cell isolation and PCR and promises to be adaptable for additional types of integrated assays.

Agilent 2100 bioanalyzer for restriction fragment length polymorphism analysis of the Campylobacter jejuni flagellin gene.

The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electrophoresis on a microchip device (LabChip 7500; Caliper Technologies, Mountain View, Calif.) that is capable of rapidly sizing small DNA fragments. To determine whether the system could replace conventional restriction fragment length polymorphism (RFLP) typing by agarose gel electrophoresis, we compared the analyzer with conventional flagellin RFLP for typing Campylobacter jejuni. Ninety-seven isolates representing 46 Fla types were initially analyzed. Correct Fla types were detected in 59% of the isolates. The major problem with the system was in resolving samples containing multiple DNA fragments differing from 8 to 20 bp. Overall, the bioanalyzer has the potential to replace conventional RFLP analysis by gel electrophoresis, but improvements in the chip separation are needed.

Randomised placebo controlled trial of beta agonist dose reduction in asthma.

BACKGROUND: Many patients continue to take regular beta agonists, often at high doses, contrary to national and international guidelines. Some studies have suggested that this can worsen asthma control, but whether such patients can reduce their dose of beta agonist and whether they would benefit from this has not been determined. Reduction of beta agonist dose was studied in a placebo controlled parallel group study. METHODS: Following a run in period, 33 subjects with asthma taking regular beta agonists were converted to an equivalent dose of terbutaline via a Turbohaler. Two weeks later terbutaline was continued at the same dose or changed to placebo in two stages a week apart. The change over period was covered by an increased dose of inhaled steroid to attenuate any immediate effects of the change in dose. Subjects then attended weekly for six weeks for measurement of forced expiratory volume in one second (FEV1) and the dose of methacholine that produced a 20% fall in FEV1 (PD20). Peak expiratory flow (PEF) and symptom scores were recorded twice daily throughout the study. Exacerbations, lung function, bronchial responsiveness, bronchodilator response, beta agonist use, and symptoms were compared before and six weeks after reduction in the dose of beta agonist. RESULTS: Twenty five of the 33 subjects completed the study; three patients in each group withdrew due to an asthma exacerbation. The median terbutaline dose fell from 2500 to 500 micrograms/day in the beta agonist reduction group and from 3000 to 2250 micrograms/day in the control group. There were small non-significant changes in FEV1, PEF, symptom scores and PD20 methacholine over the course of the study. The FEV1 response to a beta agonist was greater in those who reduced their beta agonist dose than in the control group although the final FEV1 achieved was the same. CONCLUSIONS: Patients with asthma taking high doses of beta agonists can reduce the amount of beta agonist they use without a significant change in their asthma control. There was no evidence of improved asthma control with beta agonist dose reduction.

Effects of a 99mTc-labeled murine immunoglobulin M antibody to CD15 antigens on human granulocyte membranes in healthy volunteers.

UNLABELLED: An injectible, 99mTc-labeled, murine immunoglobulin M antibody to stage-specific embryonic antigen-1 has been developed that can localize infections by binding to CD15 glycoproteins expressed on the cell membranes of human granulocytes in vivo after systemic administration. The purpose of this study was to measure its clinical effects on healthy people. METHODS: Multiple blood samples were aspirated before and after the intravenous administration of about 125 microg antibody labeled with approximately 370 MBq (10.0 mCi) 99mTc in 10 healthy human volunteers. Complete blood cell counts were performed at each time point. Whole-body scans were acquired contemporaneously with a dual-head gamma camera. The fraction of the administered dose at each time point was quantified in 18 regions of interest. Statistical analyses included paired t tests. RESULTS: Administration was associated with a transient decrease in the concentration of red and white blood cells in the whole blood. The effect always began within 3 min of administration. Its nadir was always reached 15-20 min after administration. There was full recovery with mild overcompensation in about an hour. The hematocrit dropped by a mean of 3.8% (P<0.002), whereas the total white blood cell count fell 44.0%+/-3.1% (P<0.001). The effect was most pronounced on the number of circulating granulocytes, which fell from 5.7+/-2.1 to 3.2+/-1.3x10(3)/microL blood. The drop paralleled a decrease in the percentage of whole blood radioactivity bound to the white blood cell membranes, which peaked at 50.4%+/-7.6% at 3 min after injection and then fell to 26.1%+/-9.3% over the next 30+/-13.4 min before recovering to 40.7%+/-8.2% at 2 h. Image analysis showed that the effect was temporally associated with an increase in the amount of radioactivity within the liver and the spleen. Recovery was associated with a decrease in hepatosplenic radioactivity. No evidence of cell destruction or agglutination could be detected. CONCLUSION: This study confirmed that administration of this radiolabeled antibody is associated with a transient decrease in the number of circulating granulocytes. However, there also seems to be a secondary hemodilutionlike effect on all blood components that has not been reported previously. The effect appears to be clinically silent and very short-lived.

The airway effects of stopping regular oral theophylline in patients with asthma.

AIMS: We investigated whether the deterioration in asthma control reported following cessation of theophylline was due to tolerance to theophylline. METHODS: Eighteen subjects with mild stable asthma were given oral theophylline 10 mg kg(-1) day(-1) or placebo for 2 weeks in a double-blind crossover study. FEV1 and PD20 histamine were measured before and 8 h after the first dose of treatment and 8, 32 and 56 h after the final dose. PD20 AMP was measured before treatment and 9 h after the final dose. RESULTS: Six patients did not tolerate theophylline. In the other 12 subjects there were no differences between treatments in daily PEF, symptom scores, rescue bronchodilator use, PD20 histamine or FEV1 up to 8 h post treatment. Following withdrawal of theophylline there were significantly lower values for mean FEV1 (mean difference 0.151, 95% CI 0.03, 026) and PD20 AMP compared to placebo but no difference in other end points. CONCLUSIONS: The small rebound deterioration in lung function following regular treatment with therapeutic doses of oral theophylline is consistent with the development of tolerance.

Integrated cell isolation and polymerase chain reaction analysis using silicon microfilter chambers.

White blood cells are isolated from whole blood in silicon-glass 4.5-microliter microchips containing a series of 3.5-micron feature-sized 'weir-type' filters, formed by an etched silicon dam spanning the flow chamber. Genomic DNA targets, e.g., dystrophin gene, can be directly amplified using the polymerase chain reaction (PCR) from the white cells isolated on the filters. This dual function microchip provides a means to simplify nucleic acid analyses by integrating in a single device two key steps in the analytical procedure, namely, cell isolation and PCR.

Degenerate oligonucleotide primed-polymerase chain reaction and capillary electrophoretic analysis of human DNA on microchip-based devices.

Random amplification of the human genome using the degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR) was performed in a silicon-glass chip. An aliquot of the DOP-PCR amplified genomic DNA was then introduced into another silicon-glass chip for a locus-specific, multiplex PCR of the dystrophin gene exons in order to detect deletions causing Duchenne/Becker muscular dystrophy. Amplicons were analyzed by both conventional capillary electrophoresis and microchip electrophoresis and results were compared to those obtained using standard non-chip-based PCR assays. Results from microchip electrophoresis were consistent with those from conventional capillary electrophoresis. Whole genome amplification products obtained by DOP-PCR proved to be a suitable template for multiplex PCR as long as amplicon size was < 250 bp. Successful detection and resolution of all PCR products from the multiplex PCR clearly shows the feasibility of performing complex PCR assays using microfabricated devices.

Micromachined analytical devices: microchips for semen testing.

Micromachined devices (microchips) have been designed and tested for a range of clinically important assays. In this study we compare sperm motility determined using disposable glass microchips and a conventional Makler chamber. The 17 x 14 mm glass microchips contained three etched test structures each comprising either duplicate or quadruplicate analytical microchannels. Semen samples with sperm counts ranging from 21 to 78 million sperm per ml and forward progression scores of from 1+ to 3+ were evaluated and swimming times ranging from 360 s (3.3+ progression) to 770 s (1+,2 forward progression) observed in the microchips. Motility determined by the time taken for sperm to swim to the end of a microchannel (100 microns wide x 40 microns deep x 10 mm long) in the microchip correlated with forward progression of the sperm determined by the conventional Makler chamber method. This study demonstrates the feasibility of microchips for sperm motility testing and suggests that this technique would be applicable to the study of other types of motile cells.

Diagnosis of Duchenne/Becker muscular dystrophy and quantitative identification of carrier status by use of entangled solution capillary electrophoresis.

Use of capillary electrophoresis, a new and useful analytical tool, offers a variety of advantages for nucleic acid analyses, including rapid analysis, automation, high resolution, qualitative and quantitative results, and low consumption of both sample and reagents. We report the first example of the use of entangled solution capillary electrophoresis (ESCE) and laser-induced fluorescence detection (LIF) for separation-based diagnostics in the quantitative analysis of multiplex PCR products for determination of carrier status of Duchenne/ Becker muscular dystrophy (DMD/BMD). This approach greatly improved the speed, resolution, and sensitivity of information needed for the diagnosis of DMD/BMD compared with that from conventional diagnostic methods, and is of general utility for diagnosis of genetic diseases.

Effect of long-term treatment with salmeterol on asthma control: a double blind, randomised crossover study.

OBJECTIVES: To determine the effect of adding salmeterol 50 micrograms twice daily for six months to current treatment in subjects with asthma who control their inhaled corticosteroid dose according to a management plan. DESIGN: A double blind, randomised crossover study. SETTING: Nottingham. SUBJECTS: 101 subjects with mild or moderate asthma taking at least 200 micrograms twice daily of beclomethasone dipropionate or budesonide. INTERVENTIONS: Salmeterol 50 micrograms twice daily and placebo for six months each, with a one month washout. Subjects adjusted inhaled steroid dose according to guidelines. MAIN OUTCOME MEASURE: Reduction in inhaled steroid use, exacerbations of asthma, and use of oral steroids. RESULTS: Data were available for 87 subjects. When compared with placebo salmeterol treatment was associated with a 17% reduction in inhaled steroid use (95% confidence interval 12% to 22%) with no significant difference in the number of subjects who had an exacerbation (placebo 25%, salmeterol 16%) or use of oral steroids. For secondary end points salmeterol treatment was associated with higher morning and evening peak expiratory flow and forced expiratory volume in one second; a reduction in symptoms, bronchodilator use and airway responsiveness to methacholine; and no effect on serum potassium concentration, 24 hour heart rate, or the final forced expiratory volume in one second achieved during a salbutamol dose-response study. CONCLUSIONS: In subjects who adjusted their inhaled steroid treatment according to guidelines the addition of salmeterol 50 micrograms twice daily was associated with a reduction in inhaled steroid use and improved lung function and symptom control.

Adenosine monophosphate and histamine induced bronchoconstriction: repeatability and protection by terbutaline.

BACKGROUND: Inhaled adenosine monophosphate (AMP) is thought to cause bronchoconstriction in asthmatic patients indirectly through mast cell mediator release. It may therefore be a more sensitive marker of airway inflammation in asthma and hence more specific for epidemiological surveys of asthma than challenges that act directly on airway smooth muscle such as histamine. There is some uncertainty as to how repeatable the measurement is and this is important if it is to be used for epidemiological studies. METHODS: The response to histamine and AMP challenges and the protection afforded by terbutaline (500 micrograms) against these two challenges was measured on two occasions two weeks apart in 20 subjects with asthma (19 completed the study). The response to histamine and AMP was measured as the provocative dose causing a 20% fall in forced expiratory volume in one second (PD20) and the protection afforded by terbutaline in doubling doses (DD). Repeatability was assessed as the limits of agreement. RESULTS: Although terbutaline had a slightly greater protective effect against AMP than histamine on both the first (delta PD20 = 2.66 versus 2.11 DD) and second occasion (2.56 and 2.15 DD), the differences were not statistically significant. The limits of agreement for the two histamine and two AMP challenges after placebo were from 3.06 to -3.5 and from 3.78 to -4.54 DD respectively, and these values did not differ significantly. The agreement limits between the first PD20 histamine and PD20 AMP values after placebo were similar, being from 3.73 to -3.72 DD after allowing for the 17.8-fold higher PD20 values for AMP compared with histamine. CONCLUSIONS: Terbutaline caused a slightly greater inhibition of the bronchoconstrictor response to AMP than histamine but the differences were small and non-significant. Any differences in repeatability between AMP and histamine challenges are small and in this study were not significant. The fact that the agreement between histamine and AMP PD20 values was similar to the agreement between repeat histamine or repeat AMP PD20 values suggests that, within an asthmatic population, PD20 AMP may not be providing different information from that provided by PD20 histamine.

Effect of regular terbutaline on the airway response to inhaled budesonide.

BACKGROUND: The rebound increase in bronchial reactivity and fall in forced expiratory volume in one second (FEV1) following treatment with beta agonists seen in several studies has occurred regardless of concurrent steroid therapy. Little is known about the effect of adding beta agonists to corticosteroids, but in a recent study regular treatment with terbutaline appeared to reduce some of the beneficial effects of budesonide. The effects of budesonide alone and in combination with regular terbutaline treatment on lung function, symptom scores, and bronchial reactivity were therefore examined. METHODS: Sixteen subjects with mild stable asthma inhaled budesonide 800 micrograms twice daily for two periods of 14 days with terbutaline 1000 micrograms three times daily or placebo in a double blind crossover fashion. FEV1 and the dose of histamine or adenosine monophosphate (AMP) causing a 20% fall in FEV1 (PD20) were measured before and 12 hours after the final dose of treatment, and changes from baseline were compared. Seven day mean values for daily morning and evening peak expiratory flow (PEF) values, symptom scores, and rescue medication were compared before and during treatment. RESULTS: Morning and evening PEF rose more with budesonide plus terbutaline than with budesonide alone, with a mean difference of 19 l/min occurring in the evening (95% confidence interval (CI) 2 to 36). There was no difference in symptom scores during treatment. Following treatment the mean increase in FEV1 was 150 ml higher with budesonide alone (95% CI-10 to 300). There was no difference between treatments in change in histamine and AMP PD20. CONCLUSIONS: Evening PEF was greater when budesonide was combined with regular terbutaline. There was no evidence of a difference in bronchial reactivity following the two treatment regimens. The findings of a previous study were not confirmed as the reduction in FEV1 after budesonide and terbutaline was smaller and not statistically significant. Further work is needed to determine whether this disparity in findings in the two studies is due to a type 2 statistical error in this study or a spurious finding in the previous study.

Microchip-based Devices for Molecular Diagnosis of Genetic Diseases.

Microchips, constructed with a variety of microfabrication technologies (photolithography, micropatterning, microjet printing, light-directed chemical synthesis, laser stereochemical etching, and microcontact printing) are being applied to molecular biology. The new microchip-based analytical devices promise to solve the analytical problems faced by many molecular biologists (eg, contamination, low throughput, and high cost). They may revolutionize molecular biology and its application in clinical medicine, forensic science, and environmental monitoring. A typical biochemical analysis involves three main steps: (1) sample preparation, (2) biochemical reaction, and (3) detection (either separation or hybridization may be involved) accompanied by data acquisition and interpretation. The construction of a miniturized analyzer will therefore necessarily entail the miniaturization and integration of all three of these processes. The literature related to the miniaturization of these three processes indicates that the greatest emphasis so far is on the investigation and development of methods for the detection of nucleic acid, followed by the optimization of a biochemical reaction, such as the polymerase chain reaction. The first step involving sample preparation has received little attention. In this review the state of the art of, microchip-based, miniaturized analytical processes (eg, sample preparation, biochemical reaction, and detection of products) are outlined and the applications of microchip-based devices in the molecular diagnosis of genetic diseases are discussed.

Effect of cessation of short-term therapy with ipratropium bromide on lung function and airway responsiveness.

Regular exposure to antimuscarinic drugs would be expected to upregulate airway muscarinic receptors and could cause a transient increase in airways obstruction if treatment was stopped or omitted. We have examined peak expiratory flow rate (PEFR) during treatment and forced expiratory flow in one second (FEV1) and airway responsiveness to three constrictor agonists (as the provocative dose of agonist causing a 20% fall in FEV1, (PD20)) following cessation of regular inhaled ipratropium bromide, in 13 subjects with mild stable asthma. Subjects inhaled placebo and ipratropium bromide, 80 microg q.i.d. for 14 days in a cross-over fashion with a 1 week run-in/wash-out period before and after each treatment period. Subjects recorded symptom scores and PEFR throughout the study, and FEV1 and PD20 to histamine, methacholine and metabisulphite were measured before and after cessation of treatment. When compared to baseline, FEV1 was lower after cessation of ipratropium than after placebo, with a significant difference 30 h after the last dose (difference 190 mL; 95% confidence interval (95% CI) 310-70 mL; p<0.02). FEV1 measured 6-10 days later, did not differ significantly. PEFR was significantly lower after cessation of ipratropium than after placebo on Day 15 (19-37 h after the last dose) (mean difference 4.6%; 95% CI 1.6-7.5%; p<0.01) but not on Day 16. There were no significant changes in PD20 histamine, methacholine and metabisulphite, symptom scores or rescue bronchodilator use after cessation of treatment. Thus, transient bronchoconstriction was found around 30 h after cessation of regular therapy with inhaled ipratropium for 2 weeks. The mechanism is unclear, as no evidence of muscarinic receptor upregulation was found. Although the changes were small and unlikely to be important for most patients, the results of this study indicate that the timing of lung function measurements relative to the last dose of ipratropium is important when interpreting the course of lung function in long-term studies.

Analysis of ligase chain reaction products amplified in a silicon-glass chip using capillary electrophoresis.

Ligase chain reaction (LCR) is a useful molecular technique for detecting known point mutations. We report the first example of the use of a disposable silicon-glass micro-chip for LCR and the first application of capillary electrophoresis (CE) to analyze samples amplified by LCR in a chip. Silicon-glass chips were manufactured using conventional photolithography and anodic bonding. The chips provide three distinct advantages for LCR: excellent thermal conductivity, a micro reaction volume ( < 10 microliters), and reproducible, low-cost manufacturing. Investigation and quantitation of amplification efficiency of LCR in a chip or in a tube requires an analytical technique that is faster and more convenient than the conventional slab gel methods. Slab gel electrophoresis uses relatively large amounts of sample and is labor-intensive and time-consuming, and thus is unsuitable for the separation and detection of LCR products. In contrast CE requires sample volume (original LCR products) of less than 1 microliter and is therefore well-suited to analysis of the micro-volume reaction mixture from chips. We combined CE with a sensitive laser induced fluorescence (LIF) detection system for the rapid separation and quantitative detection of LCR products amplified from the lacI gene in a silicon-glass chip. Comparative studies were made with LCR between tubes and silicon-glass chips. CE-LIF analysis is ideally suited to examination of micro-LCR amplification with high throughput. The technologies may find medical uses in disease diagnosis and research.