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M A Whelan

Publications and source records attributed to M A Whelan.

At least 19 recordsLinked to original sources
PubMed1993

Chemical reactivity of an HLA-B27 thiol group.

Techniques have been developed to measure the reactivity of free thiols in the HLA class I antigen-binding cleft. HLA-B27, which sequencing predicts has a free cysteine at position 67, reacts rapidly with the positively charged thiol reagent monobromotrimethyl-ammoniobimane bromide (qBBr) to give products which are identifiable by isoelectric focusing. HLA-B38, B39, B64 and B65, all of which have a similar Cys 67, react less strongly. Several other class I molecules, notably HLA-C antigens, are reactive in this system, and it may be capable of recognizing subtypes such as A*0207 which also carry free cysteine. The accessibility of thiol to qBBr depends both on the chemistry of the class I molecule and other factors in the cell. Two human cell lines which are known to carry identical B27 genes but do not present the same peptides, differ considerably in the accessibility of their B27 thiol. Evidence from mouse cells transfected with mutant B27 genes suggests that a unique lysine at position 70 in the wild-type molecule increases reactivity to thiol-reactive metabolites. The failure of B27 to give a complete reaction with qBBr in our model systems suggests that it can exist in more than one chemical form. This may leave the molecule susceptible to oxidation, causing errors in T cell recognition and an exaggerated inflammatory response.

3T3 Cells↗
PubMed1991

HLA-B27 subtypes.

Explore the source record for details and available documents.

Epitopes↗
PubMed1990

Widespread tissue distribution of mitochondrial DNA deletions in Kearns-Sayre syndrome.

We performed Southern analysis of mitochondrial DNA (mtDNA) in 6 tissues from a patient with Kearns-Sayre syndrome and found a single deletion of 4.9 kb in all tissues. The percentage of deleted mtDNAs varied widely between tissues, from only 4% in smooth muscle to approximately 50% in skeletal muscle. Samples of DNA obtained from 3 different skeletal muscles and from separate areas of individual tissues showed little variation in percentage of deleted mtDNA. Biochemical analysis showed no clear correlation between mitochondrial enzyme activity and deleted mtDNAs.

Blotting, Southern↗
PubMed1990

Effect of a free sulphydryl group on expression of HLA-B27 specificity.

Sequence studies indicate that the alpha-1 domain of the HLA-B27 molecule has a characteristic unpaired cysteine residue at position 67, adjacent, because of secondary structure, to a lysine at position 70. Simple chemical considerations predict that this cysteine should have an exceptionally reactive sulphydryl group. We have shown by ELISA and flow cytometry that the binding of some monoclonal antibodies to B27 on lymphoid cell lines can be inhibited by reagents which react with sulphydryl groups. However this inhibition is never complete: the evidence suggests 2 forms of B27 molecule, one of which is already blocked. We propose that some HLA molecules with oxidised sulphydryls are recognised as different from the reduced forms. Whether they are also recognised as foreign will depend on an individual's history of thymic learning. Oxidation to 'foreign' HLA in the adult is likely to predispose to inflammatory reactions.

Antibodies, Monoclonal↗
PubMed1984

The innominate line.

High-resolution CT scan is used to clearly identify the components of the innominate line. Fourteen patients with abnormal innominate lines are then examined and used to illustrate the three pathological processes affecting the innominate line, namely, destruction, hyperostosis and expansion.

Humans↗
PubMed1984

CT of the base of the skull.

This article emphasizes the value of high-resolution CT scanning in evaluating the skull base. The use of axial and coronal sections, imaged at both bone and soft tissue windows, is emphasized, and a systematic approach to analysis of lesions of the skull base is offered.

Bacterial Infections↗
PubMed1984

CT of the soft tissue structures of the neck.

CT is an excellent means of evaluating patients with neck masses. It has the capability of defining the precise location of a mass and its effect on adjacent structures. The information obtained on CT may be used to determine the best possible approach for biopsy or surgery and to determine radiation therapy ports.

Bacterial Infections↗
PubMed1983

Computed tomography of spinal tuberculosis.

The computed tomographic (CT) features of nine documented cases of spinal tuberculosis are analyzed. The mechanisms of vertebral involvement are reviewed. The ability of CT to facilitate the diagnosis as well as to delineate the extent of soft tissue involvement is emphasized. The need for increased alertness to the diagnosis of tuberculosis is stressed.

Adult↗
PubMed1983

Acquired immunodeficiency syndrome: cerebral computed tomographic manifestations.

CT examination of the central nervous system was performed in 19 patients with acquired immunodeficiency syndrome (AIDS). Eighteen patients were homosexuals, and five drug abusers. Parenchymal and meningeal inflammations were seen in patients with intracranial manifestations of the disease. The most common demonstrable lesion in the parenchyma was toxoplasmosis, which produced ring enhancement, solid enhancement, and nonenhancing focal edema. The most common meningeal inflammation was cryptococcosis, which was diagnosed by examination of the cerebrospinal fluid and did not show specific CT changes. It is concluded that toxoplasmosis and cryptococcosis should be the first diagnostic consideration in patients with neurologic findings who have a history of homosexuality and/or intravenous drug abuse and previous unusual infections or anergy. A delayed contrast scan, single or double dose, appears to be the most accurate method of outlining the total extent of disease thereby helping to locate the best biopsy site for pretreatment diagnosis. Empirical institution of toxoplasmosis therapy is recommended in those cases in which CT findings are consistent with toxoplasmosis and the biopsy shows only nonspecific encephalitis. A biopsy of every parenchymal lesion is not considered necessary.

Acquired Immunodeficiency Syndrome↗
PubMed1982

The variant lumbar pedicle.

Three cases of aplastic and/or hypoplastic lumbar pedicle are presented and discussed. The importance of plain films, especially the 45 degrees posterior oblique, for making the diagnosis is emphasized. The incidence and embryology of abnormalities of the pedicle are reviewed and the radiological features used to differentiate these congenital abnormalities from neoplasm and trauma are described.

Adult↗