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Biomedical subjects

A M Sadler

Publications and source records attributed to A M Sadler.

At least 19 recordsLinked to original sources
PubMed1994

Low-resolution DNA typing for HLA-B using sequence-specific primers in allele- or group-specific ARMS/PCR.

The products of the human major histocompatibility complex (HLA Class I and II) have historically been detected using serological or cellular assays. With the availability of DNA sequence information for alleles of the HLA system, and with the development of molecular biological techniques it has become possible to tissue type for allelic differences in the HLA genes themselves. We describe here a polymerase chain reaction (PCR) system, based on the principle of the amplification refractory mutation system (ARMS), for low-resolution DNA typing of the HLA-B gene. The technique involves a one-step PCR from genomic DNA using sequence-specific primers in particular combinations that determine the specificity of each reaction. A low-resolution primer panel has been designed, based on published HLA-B gene nucleotide sequences, consisting of 34 sequence-specific primers (SSP) in 24 PCR reactions which cover all known HLA-B alleles, to give allele-specific or group-specific amplification of DNA fragments of defined size (344-784bp). Advantages of the system are that it can be performed in under 4 hours including DNA extraction, results are easy to interpret and it does not require viable cells.

Base Sequence↗
PubMed1993

The monoclonal antibody TAL16.1 recognizes the aspartic acid residue at position 70 in DRB gene products.

A polymorphic monoclonal antibody (TAL16.1), raised against a mouse L-cell transfectant expressing the human DRB5*0101 gene from the HLA-DR15(2) Dw2 DR51 haplotype was shown to have a complex pattern of reactivity to DRB gene products. The antibody bound to a transfectant expressing the DRB5*0101 allele against which it was produced but not to a transfectant expressing the DRB1*1501 allele. These alleles of the DRB1 and DRB5 genes are usually coexpressed on DR15(2) Dw2 DR51 cells. A comparison of the HLA-DRB amino acid sequences of reactive and non-reactive cells identified an aspartic acid residue at position 70, conserved in all antibody-positive cells and absent in antibody-negative cells, which was postulated as being responsible for conferring the specificity of the antibody. The aspartic acid residue at position 70 is present in DRB5*0101 and DRB5*0102 alleles but absent in DRB5*0201 and DRB5*0202 alleles, allowing the antibody to distinguish between these splits of the DR51 serological specificity. TAL16.1 also binds to the product of the DRB1*0103 allele and discriminates between cells with a DR103 specificity and the other DR1 subtypes, DRB1*0101 and DRB1*0102. In this report the value of transfectants as immunogens for use in the production of monoclonal antibodies of predetermined specificity and as tools for the fine mapping of antibody specificity is discussed.

Amino Acid Sequence↗
PubMed1992

A microELISA assay for detection of anti-HLA activity of mouse monoclonal antibodies using an Astroscan 2100 automated plate reader.

A microenzyme-linked immunosorbent assay (microELISA) method has been developed using an Astroscan 2100 system automated plate reader which was initially designed for tissue typing by a two colour fluorescent microcytotoxicity assay. A 96-well plate ELISA used for screening mouse monoclonal antibodies raised against surface HLA antigens has been modified for use with the Astroscan plate reader and 72-well typing trays. The existing substrate 4-methylumbelliferyl-beta-D-galactoside (4MUG) has been replaced with fluorescein-di-beta-D-galactopyranoside (FDG), to provide a wavelength (530 nm) detectable by the Astroscan or other automated plate readers designed for reading microcytotoxicity assay plates. The assay volumes have also been reduced tenfold for use with Terasaki microtest plates. The assay now has the major advantage of requiring only 5 microliters of test supernatant allowing hybridomas to be screened earlier during a fusion and on a wider cell panel. The use of the large panel which includes B lymphoblastoid cell lines (B-LCL) and mouse L cell transfectants expressing HLA genes, reduces the length of time the hybridomas need to be kept in tissue culture before selection. Other advantages include the reduction in the number of target cells required, smaller volumes of reagents throughout the assay and the ability to screen cytotoxic as well as non-cytotoxic monoclonal antibodies. The sensitivity of this microELISA proved to be comparable with the original assay and so provides an efficient screening method for monoclonal antibodies.

Animals↗
PubMed1989

The acute effects of intravenous xamoterol ('Corwin', I.C.I. 118, 587) on resting and exercise haemodynamics in patients with mild to moderate heart failure.

The known properties of xamoterol, a partial beta 1-agonist, provide a basis to pharmacologically modulate cardiac responses to variations in sympathetic tone. Haemodynamic variables were assessed at rest and on exercise before and after intravenous xamoterol (0.2 mg kg-1), in 30 patients with mild to moderate cardiac failure. Xamoterol produced significant improvements in resting cardiac index (2.51 +/- 0.15 to 2.80 +/- 0.14 l min-1 m-2; P less than 0.001), stroke volume (62 +/- 4 to 75 +/- 5 mljbeat-1; P less than 0.001) and stroke work index (42.4 +/- 3.6 to 47.7 +/- 3.9 gm beat-1 m-2; P less than 0.01). This occurred despite a significant reduction in heart rate (78 +/- 3 to 74 +/- 2 beats min-1; P less than 0.05). There were also significant reductions in systemic vascular resistance (1990 +/- 141 to 1669 +/- 112 dynes s-1 cm-5; P less than 0.01) and double product (1146 +/- 46 to 1051 +/- 41 mmHg min-1 x 10(-1); P less than 0.05), with no significant changes in systolic blood pressure, pulmonary wedge pressure or ejection fraction. Xamoterol significantly attenuated the heart rate response to exercise (112 +/- 4 to 97 +/- 3 beats min-1; P less than 0.001), with no impairment in the expected exercise induced increase in cardiac index. This was due to the significant increase in stroke volume from 81 +/- 6 to 95 +/- 7 ml beat-1 (P less than 0.001). There were no significant changes in resting or exercise noradrenaline levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1975

Resources utilized for the care of surgical patients in the emergency department.

A classification system for surgical patients and a quantitative index of services have been developed to determine the resources utilized for medical care in an urban hospital emergency department. Five classes of surgical patients based on patient management reflect, the amount of diagnostic and therapeutic work performed. Quantitative estimates of workload and rates at which services are delivered to each patient class are included. This classification of patients which is derived from a natural grouping of common patient problems with common patterns of management, can be an important aid to effective analysis and planning of medical care in outpatient settings.

Abdomen↗