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Biomedical subjects

J M Butler

Publications and source records attributed to J M Butler.

At least 73 records · Page 4Linked to original sources
PubMed2001

Capillary electrophoresis as a tool for optimization of multiplex PCR reactions.

Copying multiple regions of a DNA molecule is routinely performed today using the polymerase chain reaction (PCR) in a process commonly referred to as multiplex PCR. The development of a multiplex PCR reaction involves designing primer sets and examining various combinations of those primer sets and different reaction components and/or thermal cycling conditions. The process of optimizing a multiplex PCR reaction in order to obtain a well-balanced set of amplicons can be time-consuming and labor-intensive. The rapid separation and quantitation capabilities of capillary electrophoresis make it an efficient technique to help in the multiplex PCR optimization process.

Alleles↗
PubMed2001

An observational survey of emergency department rapid sequence intubation.

OBJECTIVES: To study the current practice of rapid sequence intubations (RSIs) in four different emergency medicine training programmes in the UK. METHODS: Observational study design involving four regional training programmes (Wessex, North West, Yorkshire, Avon). Data were collected in real time using a previously piloted survey tool. Data were collected by specialist registrars in emergency medicine over a continuous 28 day period. Data collected included: indications for RSI; key timings of RSI procedures; details of RSI practitioner; complications and outcome of procedure. RESULTS: Data from 60 RSIs were recorded and collected. The majority of decisions to perform RSIs were made by emergency physicians (74% cases). Over 50% of the RSIs occurred after 4 pm. Emergency physicians performed 26% of RSIs although the majority were performed by anaesthetists. Most of the given indications for RSIs were based on an assessment of airway protection. Hypoxia was an uncommon reason for RSI in this study (5%). In two thirds of cases the time taken from the decision being made to perform an RSI, to the achievement of successful intubation, was greater than 20 minutes. No failed intubations were recorded, although six other complications (all minor problems) were recorded. There was no significant difference in the response times between anaesthetists and emergency physicians. CONCLUSIONS: This study shows that emergency physicians are currently performing RSIs in emergency departments in the UK. It also suggests improvements could be made to patient care. In particular, standards of care should be agreed for the provision of RSI in the emergency department, including the personnel involved and the appropriate training of individuals. RSI activity in emergency departments in the UK should be audited nationally using an agreed audit tool.

Adolescent↗
PubMed2000

Measurement of the W-->taunu production cross section in pp collisions at square root s=1.8 TeV.

We report on a measurement of sigma(pp-->W+X)B(W-->taunu) in pp collisions at sqrt[s]=1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of 18 pb-1 of data collected with the D0 detector during 1994-1995. We find that sigma(pp-->W+X)B(W-->taunu)=2.22+/-0.09 (stat)+/-0. 10 (syst)+/-0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, gWtau/gWe, be unity. We find gWtau/gWe=0.980+/-0.031, in agreement with lepton universality.

Journal Article↗
PubMed2000

Probing Balitsky-Fadin-Kuraev-Lipatov dynamics in the dijet cross section at large rapidity intervals in pp collisions at sqrt[s]=1800 and 630 GeV.

Inclusive dijet production at large pseudorapidity intervals (Deltaeta) between the two jets has been suggested as a regime for observing Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. We have measured the dijet cross section for large Deltaeta in pp collisions at sqrt[s]=1800 and 630 GeV using the D0 detector. The partonic cross section increases strongly with the size of Deltaeta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of alphaBFKL(20 GeV)=1.65+/-0.07.

Journal Article↗
PubMed2000

Brugada syndrome--the missed epidemic.

About 10-20% of patients dying suddenly or resuscitated from ventricular fibrillation do not have demonstrable heart disease. These people are often young and tragically in some cases sudden death is the first and only clinical event. One of the three main electrophysiological diagnoses to be considered in these situations is the Brugada syndrome. A case of Brugada syndrome is described, together with an example of the classic electrocardiographic manifestations and a discussion of the possible aetiology, diagnosis and management of this condition.

Adult↗
PubMed1999

Thermodynamic comparison of PNA/DNA and DNA/DNA hybridization reactions at ambient temperature.

The thermodynamics of 13 hybridization reactions between 10 base DNA sequences of design 5'-ATGCXYATGC-3' with X, Y = A, C, G, T and their complementary PNA and DNA sequences were determined from isothermal titration calorimetry (ITC) measurements at ambient temperature. For the PNA/DNA hybridization reactions, the binding constants range from 1.8 x 10(6)M(-1)for PNA(TT)/DNA to 4.15 x 10(7)M(-1)for PNA(GA)/DNA and the binding enthalpies range from -194 kJ mol(-1)for PNA(CG)/DNA to -77 kJ mol(-1)for PNA(GT)/DNA. For the corresponding DNA/DNA binding reactions, the binding constants range from 2.9 x 10(5)M(-1)for DNA(GT)/DNA to 1.9 x 10(7)M(-1)for DNA(CC)/DNA and the binding enthalpies range from -223 kJ mol(-1)for DNA(CG)/DNA to -124 kJ mol(-1)for DNA(TT)/DNA. Most of the PNA sequences exhibited tighter binding affinities than their corresponding DNA sequences resulting from smaller entropy changes in the PNA/DNA hybridization reactions. van't Hoff enthalpies and extrapolated Delta G values determined from UV melting studies on the duplexes exhibited closer agreement with the ITC binding enthalpies and Delta G values for the DNA/DNA duplexes than for the PNA/DNA duplexes.

Base Sequence↗
PubMed1999

Single nucleotide polymorphism determination using primer extension and time-of-flight mass spectrometry.

The high frequency of single nucleotide polymorphisms (SNPs) in the human genome makes them a valuable source of genetic markers for identity testing, genome mapping, and medical diagnostics. Conventional technologies for detecting SNPs are laborious and time-consuming, often prohibiting large-scale analysis. A rapid, accurate, and cost-effective method is needed to meet the demands of a high-throughput DNA assay. We demonstrate here that analysis of these genetic markers can now be performed routinely in a rapid, automated, and high-throughput fashion using time-of-flight mass spectrometry and a primer extension assay with a novel cleavable primer. SNP genotyping by mass spectrometry involves detection of single-base extension products of a primer immediately adjacent to the SNP site. Measurement of the mass difference between the SNP primer and the extension peak reveals which nucleotide is present at the polymorphic site. The primer is designed such that its extension products can be purified and chemically released from the primer in an automated format. The reduction in size of the products as a result of this chemical cleavage allows more accurate identification of the polymorphic base, especially in samples from a heterozygotic population. All six possible heterozygotes are resolved unambiguously, including an A/T heterozygote with extension products differing by only 9 Da. Multiplex SNP determination is demonstrated by simultaneously probing multiple SNP sites from a single polymerase chain reaction (PCR) product as well as from multiplexed PCR amplicons. Samples are processed in parallel on a robotic workstation, and analyzed serially in an automated mass spectrometer with analysis times of only a few seconds per sample, making it possible to process thousands of samples per day.

DNA Primers↗
PubMed1999

Dose titration of an injectable formulation of lufenuron in cats experimentally infested with fleas.

OBJECTIVES: To identify the lowest single dose of lufenuron injected s.c. that results in a 90% disruption of the flea (Ctenocephalides felis) life cycle for 6 months in cats. ANIMALS: 40 domestic shorthair cats (20 males, 20 females) between 5 and 7 months old. PROCEDURE: Cats were randomly assigned to 1 of 5 eight-cat groups and experimentally infested with C. felis on days -8, -7, -6, and -4. On day 0, cats in the 4 treatment groups were treated with an injectable formulation of lufenuron at doses of 2.5, 5, 10, or 20 mg/kg of body weight, respectively. Control cats received the injectable formulation without lufenuron. Experimental infestations were repeated and flea eggs collected at various intervals for 196 days after treatment. Eggs were placed in media and incubated in an insectary for 28 days to determine effects of injectable lufenuron on egg and larval development. Number of adults that emerged from eggs were compared among groups. RESULTS: Lufenuron injected once at a dose of 10 or 20 mg/kg, but not at 2.5 or 5 mg/kg, resulted in a 90% decrease in number of adult fleas emerging from eggs for 196 days after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that control of flea egg and larval development for at least 6 months can be achieved in cats with a single s.c. injection of lufenuron (10 mg/kg). The injectable formulation may provide veterinarians and cat owners an alternative to the tablet formulation of lufenuron.

Animals↗
PubMed1998

Rapid mitochondrial DNA typing using restriction enzyme digestion of polymerase chain reaction amplicons followed by capillary electrophoresis separation with laser-induced fluorescence detection.

The polymorphic control region of mitochondrial DNA (mtDNA) is becoming more commonly used in forensic applications to differentiate among individuals in a population. Two hypervariable regions (HV1 and HV2) are often sequenced following amplification of the mtDNA via the polymerase chain reaction (PCR). More rapid screening assays would reduce both the effort and the expense of comparing two samples. A methodology has been developed that first uses restriction endonuclease digestion of the PCR-amplified mtDNA using RsaI and MnlI and then capillary electrophoresis (CE) to separate and size the PCR-RFLP fragments. This rapid procedure offers an alternative method for screening of polymorphisms in amplified mtDNA samples. In addition, the presence of a T-->C transition at position 16189, which gives rise to the so-called "C-stretch" in HV1, may be predicted from the presence of nonspecific PCR products in the CE results.

Computer Simulation↗
PubMed1998

Reliable genotyping of short tandem repeat loci without an allelic ladder using time-of-flight mass spectrometry.

DNA separations which traditionally have been performed by slab gel or capillary electrophoresis, may now be conducted via time-of-flight mass spectrometry (TOF-MS). The advantages of using a mass spectrometry approach for short tandem repeat (STR) characterization include a dramatic increase in both the speed of analysis and the accuracy of mass measurements. We report here typing of the STR loci TH01, TPOX, and CSF1PO as well as the sex-typing marker amelogenin using TOF-MS. Allelic ladders, which are typically used with electrophoretic separation systems to correct for mobility differences of DNA fragments under various conditions, are not needed for accurate genotyping with TOF-MS. A mass precision of 0.1% RSD, which corresponds to approximately 0.1 nucleotide, was routinely observed. Mass accuracies were better than a fraction of a single nucleotide when a daily mass calibration was used. STR microvariants, such as the TH01 allele 9.3, could be detected and resolved from alleles which differ by as little as a single base. In addition, the smaller PCR product sizes (55-125 bp) examined in this study have the potential advantage of being more successful when amplifying forensic samples with degraded DNA.

Alleles↗
PubMed1998

Forensic applications of mitochondrial DNA.

Human mitochondrial DNA has become a useful tool in forensic investigations. Its polymorphic nature and maternal inheritance are characteristics that have, combined with its sequence information, enabled investigators to identify missing persons, war casualties and individuals involved in mass disasters and criminal cases. Various screening procedures have been developed to reduce the need to sequence samples that do not match, but DNA-sequence information is still necessary to verify a match. Even though several challenges remain before mitochondrial-DNA-sequence information can be used unambiguously, comparative mitochondrial-DNA-sequence analysis appears to be a reliable and powerful means for human identification.

DNA, Mitochondrial↗
PubMed1998

Tensile properties of the neurorrhaphy site in the rat sciatic nerve.

Forty-three epineurial rat sciatic neurorrhaphies were performed to gain insight into the duration necessary to protect a nerve repair. By killing animals at varying intervals after neurorrhaphy and harvesting the sciatic nerves, we investigated the timing of neurorrhaphy site tensile property recovery. There were 9 normal control nerves. No nerves ruptured after repair, even though the operated legs were not immobilized. Ultimate and maximal simulated in situ loads and elongations were measured, and stresses and strains were calculated from mechanical testing. Sixty-four percent of normal ultimate stress was gained during the first week after neurorrhaphy, with no significant increase for 10 to 12 weeks. Ultimate strains for control and repaired nerves for all time intervals ranged from 14.2% +/- 1.8% to 26.0% +/- 3.9%. Maximal simulated in situ stress and strain remained in the toe region of the stress versus strain curve, implying that no nerves ruptured because ultimate stress and strain were never approached. Caution must be exercised in extrapolating these data to the human clinical situation.

Animals↗
PubMed1997

Mechanical transmission of Toxoplasma gondii oocysts by dogs.

Two experiments were conducted to determine if dogs could mechanically transmit Toxoplasma gondii after ingesting cat feces or by rolling in cat feces containing oocysts. In the first experiment, two dogs were fed sporulated T. gondii oocysts; viable sporulated oocysts were present in dog feces for up to 2 days postinoculation (PI). Both dogs seroconverted to T. gondii but did not develop clinical signs of toxoplasmosis. In the second experiment, nonsporulated oocysts were placed on dog skin and fur, and fur clippings were bioassayed for T. gondii in mice. Oocysts did not sporulate on dog fur. The results of this study support the hypothesis that dogs may be involved in the mechanical transmission of T. gondii to humans.

Animals↗
PubMed1997

Efficacy of decoquinate against Neospora caninum tachyzoites in cell cultures.

Neospora caninum is a major cause of abortion in dairy cattle in the United States and other countries. Abortions and neonatal mortality also occur in other ruminant species. Decoquinate is an anticoccidial that is approved for use in cattle and goats in the United States. We studied the efficacy of decoquinate against tachyzoites of N. caninum in a 5-day of treatment, cell culture flask lesion-based assay. Decoquinate killed tachyzoites at concentrations of 0.1 and 0.01 microgram ml-1. Decoquinate had little measurable effect on extracellular tachyzoites. Decoquinate acted quickly to kill intracellular stages at coccidiocidal concentrations; tachyzoites were killed within 5 min at 0.1 microgram ml-1 decoquinate.

Abortion, Veterinary↗