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Biomedical subjects

G Gallacher

Publications and source records attributed to G Gallacher.

At least 37 records · Page 2Linked to original sources
PubMed1990

Gonococcal infection within Scotland: antigenic heterogeneity and antibiotic susceptibility of infecting strains.

Two panels of monoclonal antibody reagents were used to serotype all strains of Neisseria gonorrhoeae isolated from four separate geographical areas serving two million of the five million Scottish population. Serotype 1B isolates accounted for 60% of the 869 strains examined and were more prevalent than 1A isolates in each geographical area. A total of 11 1A serovars and 47 1B serovars were recognised. Only two of the 11 1A serovars (Aedgkih/Arost and Aedih/Arst) were found in every centre but these accounted for over 90% of the 1A isolates. Although there was a total of 47 different 1B serovars over 80% of the isolates were accounted for by the ten most commonly encountered serovars. There were, however, marked geographical differences within both major and minor serovars. There was a highly significant difference (P less than 0.001) between protein 1A and 1B serovars with respect to their susceptibility to penicillin. Within each protein 1 type there were also differences in antibiotic susceptibility. Penicillinase-producing N. gonorrhoeae (PPNG) were found in all centres and accounted for 24 (2.8%) of the 869 isolates. The majority of the PPNG (71%) were serotype 1A and with one exception were serovar Aedih/Arst. PPNG strains accounted for 37% (16) of the 43 Aedih/Arst isolates. Epidemiological, diagnostic and therapeutic implications arising from the distinct geographical differences in the pool of circulating gonococci are discussed.

Antibodies, Monoclonal↗
PubMed1990

Development of a radioimmunoassay for idazoxan hydrochloride.

To facilitate the measurement of idazoxan in clinical trials an immunoassay capable of detecting low ng ml-1 concentrations was required. A stable derivative was prepared which, after linking to keyhole limpet hemocyanin (KLH), was subsequently immunized into sheep. Early assay development was carried out with both fluorescent (1-FITC) and iodinated (I-125) labels. The assay methodology was the same in both cases, using magnetizable solid-phase particles to which the antibody was linked. The sensitivity of the assay was such that a large sample volume was required, which in turn, led to problems of increased protein interference. The use of pepsin to digest the protein was used effectively after several blocking agents were unsuccessfully used. The limit of detection was in the region of 3 ng ml-1. Cross-reactivity studies showed that the antibody was specific for idazoxan. Intra- and inter-assay precision was 7 and 12%, respectively. Correlation with the analytical GC-MSD method was in the order of 0.90.

Antibody Specificity↗
PubMed1990

Fluorescence polarization immunoassay of urinary vanillylmandelic acid.

This rapid fluorescence polarization immunoassay for urinary vanillylmandelic acid (VMA) involves use of our previously described antiserum and label and the program for 5-hydroxyindoleacetic acid in the Abbott TDx fluorimeter. Urine samples were measured directly, without pretreatment. The minimum detectable concentration was 0.3 mg/L, and the range of the standard curve was 0.3-200.0 mg/L. Precision, analytical recovery, and correlation of results with those by the Pisano method (Clin Chim Acta 1962;7:285-91) were all satisfactory. With this procedure one can determine the VMA concentration in 10 urine sample in 22 min. This is the first report of a clinical immunoassay for VMA and should greatly simplify screening for neural crest tumors.

Fluorescence Polarization↗
PubMed1989

Production and characterisation of antibodies to vanillylmandelic acid.

Antibodies were raised to the catecholamine metabolite vanillylmandelic acid (VMA). The side chain was protected and, after derivatisation through the 4-phenolic hydroxyl group, the hapten was coupled to KLH and the resultant conjugate deprotected. Sheep immunised with this immunogen responded with specific, high titre antibodies to VMA as assessed using a fluorescent label. Cross-reaction of the antiserum from one of the sheep was minimal, being under 1% with all naturally occurring related compounds tested. This report is the first to describe an effective antiserum for VMA which will permit measurement over the normal range in urine.

Animals↗
PubMed1989

An improved label for amphetamine fluoroimmunoassay.

This paper describes the synthesis of amphetamine derivatives, functionalized at the para-position of the phenyl ring of the drug. These derivatives were used to prepare fluorescein-labelled amphetamine to replace the label in a previously described polarisation fluoroimmunoassay that is highly specific for amphetamine. The original label was obtained using material donated by industrial sources and therefore not generally available. When the new label was used in the immunoassay, specificity was similar but the sensitivity was improved by a factor of four. This increase in sensitivity is explained by elimination of bridge-binding effects.

Amphetamines↗
PubMed1988

Development of a simple, fluoroimmunoassay for paraquat.

High affinity populations of antibodies to paraquat were produced in high concentrations in the sera of immunised sheep. A simple fluoroimmunoassay was developed for rapid measurement of plasma paraquat. Fluorescein-labelled paraquat was added to sample or standard (20 microliter) followed by premixed first and second antisera. Equilibrium was reached within 2 min and results were available within 20 min. Correlation with weighed-in paraquat gave a regression line (r) of 0.997. All reagents proved stable and are suitable for general distribution.

Animals↗
PubMed1988

Development of fluoroimmunoassays for the specific detection of morphine in urine.

Two fluoroimmunoassays for the specific detection of morphine in urine are described based on the use of ovine antibodies and fluorescein-labelled normorphine. The first, a polarisation fluoroimmunoassay, is performed by adding 10 microliter of urine to 1.5 ml of a single-reagent, comprising premixed antiserum and tracer, incubation for a few minutes at ambient temperature and measurement of fluorescence polarisation. The assay gives results which compare well with those by thin-layer chromatography, EMIT d.a.u., and the Boehringer opiate drug test. Although adequate for routine screening for drug abuse, the technique is not as sensitive as some radioimmunoassays. Therefore, a second fluoroimmunoassay was developed based on the use of the same antibodies covalently coupled to magnetisable particles to facilitate both the separation of the bound and free fractions and the removal of non-specific interfering substances. Thus, larger sample volumes could be employed and greater sensitivity achieved.

Chromatography, Thin Layer↗
PubMed1988

Development of a single reagent polarisation fluoroimmunoassay for the detection of opiates in urine.

The design, development, and optimisation of a simple polarisation fluoroimmunoassay to detect the opiate group of drugs, in urine, is described. Urine (10 microL) is added to 1.5 mL of a single reagent, prepared by mixing ovine anti-opiate serum with fluorescein-labelled morphine. After incubation for 30 min at 30 degrees C, or 60 min at room temperature, fluorescence polarisation is measured. The assay can be used as a "stat" test or automated for large batch screening and detects the commonly abused opiates, heroin (through its metabolite morphine), codeine, and dihydrocodeine.

Antibody Specificity↗
PubMed1988

Development of separation fluoroimmunoassays for bendazac and 5-hydroxy bendazac.

Two distinct separation fluoroimmunoassays were developed to determine serum levels of bendazac and its main metabolite 5-hydroxy bendazac for use in early pharmacokinetic studies and for long-term therapeutic drug monitoring should this prove necessary. In both assays fluorescein-labeled analyte was used as tracer and the antibodies were coupled to magnetizable particles. The use of a magnetizable solid phase enabled a simple and rapid separation step and thus a high sample throughput. There was no crossreactivity between the drug and its metabolite in either assay, indicating that highly specific antibodies had been produced. The results from both assays correlated well with serum levels determined by a high performance liquid chromatography method.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Design of the immunogen and label for use in a fluoroimmunoassay for paracetamol.

The design of immunogens for raising antisera containing antibodies specifically directed against paracetamol is discussed. A derivative of the drug with minimal structural alteration was synthesised, coupled to the carrier protein key-hole limpet haemocyanin, and used to immunise sheep. The evaluation of the resulting antisera is described. Preparation of a fluorescent label with reduced bridge-binding then allowed the development of a polarisation fluoroimmunoassay for paracetamol in buffer, suitable for conversion to a direct serum assay.

Acetaminophen↗
PubMed1988

Development of a specific polarisation fluoroimmunoassay for paracetamol in serum.

A specific polarisation fluoroimmunoassay for the measurement of paracetamol levels in serum has been developed for use in emergency toxicological screening. It is based on the use of a fluorescein-labelled analogue and a sheep antiserum and exploits the rapid dissociation kinetics of the hapten-antibody complex to enable the label and antiserum to be combined as a single reagent. Paracetamol levels are determined by adding 5 microL of serum to 1.5 mL of the single reagent, incubation at ambient temperature for a few minutes and measurement of fluorescence polarisation. In addition to its speed and simplicity, the assay is both accurate and precise and the results obtained correlate closely with those from the commonly used chemical and enzymatic techniques.

Acetaminophen↗
PubMed1987

The production and characterisation of antisera to 17-hydroxyprogesterone.

Sheep were immunised with 11-deoxycortisol-21-hemisuccinate-bovine serum albumin (11-deoxycortisol-21-HS-BSA) or with 17-hydroxyprogesterone-7 alpha-carboxyethyl thioether-keyhole limpet haemocyanin (17-OHP-7 alpha-CETE-KLH) or with 17-OHP-3-(O-carboxymethyl)oxime-KLH (17-OHP-3-CMO-KLH). The resultant antisera were assessed using [3H]17-OHP and dextran-coated charcoal to separate the antibody bound and free fractions. All sheep produced antisera with an apparent affinity constant of from 1.4 to 6.6 X 10(9) 1/mol. Those raised against 11-deoxycortisol-21-HS-BSA had titres ranging from 1:12,000 to 1:78,000 but showed significant cross-reactivity with many of the steroids tested. Sheep immunised with 17-OHP-7 alpha-CETE-KLH had antisera titres of from 1:102,000 to 1:180,000 and only 17-hydroxypregnenolone cross-reacted significantly (10-20%). The best antisera were raised in sheep immunised with 17-OHP-3-CMO-KLH. Titres ranged from 1:168,000 to 1:390,000 and there were about 8 g/l of specific antibodies which cross-reacted 5.7% or less with 17-hydroxypregnenolone, and less than 0.5% with progesterone, 11-deoxycortisol and the other steroids studied. The antisera to 17-OHP-3-CMO-KLH were further assessed using [125I]17-OHP; titres ranged from 1:5,700,000 to 1:18,000,000 with affinity constants of from 1.67 to 2.5 X 10(10) 1/mol. They showed minimal or no cross-reactivity with the steroids studied. Reimmunisation after an 8-month interval produced antisera with a higher affinity constant and even lower cross-reactivity with other steroids.

17-alpha-Hydroxyprogesterone↗
PubMed1987

Development of fluoroimmunoassays for flecainide.

Antibodies raised in sheep against a flecainide:protein conjugate and fluorescein-labeled drug were used to develop simple fluoroimmunoassays for the measurement of flecainide acetate in serum or plasma. A rapid, nonseparation assay, based on fluorescence polarization was optimized for therapeutic drug monitoring. A separation fluoroimmunoassay, using antibodies covalently linked to magnetizable particles to avoid the need for centrifugation, was also optimized and validated for monitoring flecainide therapy. It is applicable to lipemic, hemolyzed or icteric samples unsuitable for the nonseparation approach and for laboratories with access only to a simple fluorimeter. Finally, the separation fluoroimmunoassay was modified slightly to improve markedly sensitivity for use in pharmacokinetic studies.

Flecainide↗
PubMed1987

The raising and characterisation of antibodies to salicylate.

Polarisation fluorescence was used to assess the antibody response in sheep immunised with 4-aminosalicylic acid coupled to keyhole limpet haemocyanin and to develop a polarisation fluoroimmunoassay for subsequent clinical use. The fluorescent label was prepared by coupling 4-aminosalicylic acid to fluorescein isothiocyanate. All immunised sheep produced antibodies and a simple assay was developed using salicylic acid as the standard. The simple fluorescence polarisation approach enabled the rapid and direct study of the immuno-reactivity of a large number of pure chemical analogues of salicylic acid. Each was assessed for its ability to compete with the fluorophore-labelled analyte for antibody-binding sites, relative to salicylate, thereby enabling investigation of the steric and chemical characteristics important in the recognition and binding of a hapten to antibodies.

Aminosalicylic Acid↗
PubMed1987

Single-reagent polarization fluoroimmunoassay of methamphetamine in urine.

We developed a polarization fluoroimmunoassay for the specific detection of methamphetamine in urine. Sheep antiserum raised against methamphetamine was premixed with a fluorescein-labeled amphetamine tracer in a single reagent. The use of labeled amphetamine gave a more sensitive and more specific assay than did the use of a labeled methamphetamine tracer. The assay system had equal sensitivity for the d- and l-isomers of methamphetamine while the cross reactivity of amphetamine and other structurally related compounds was 3% or less. With a positive/negative cutoff concentration set at 1 mg/L, the polarization fluoroimmunoassay reliably identified human urines that had been reported positive for methamphetamine by an established gas-liquid chromatographic method.

Animals↗
PubMed1986

Augmentin (amoxycillin-clavulanic acid) compared with amoxycillin alone in the treatment of urinary tract infections in the elderly.

Sixty-seven patients (mean age 82 years) with urinary tract infection were treated with either Augmentin or amoxycillin in a double-blind randomised trial. Of the 52 patients who completed 5 days treatment, 21/24 (87.5%) responded to Augmentin but only 12/28 (43%) responded to amoxycillin. Five of eight patients who had failed to respond to amoxycillin responded to Augmentin.

Aged↗