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Biomedical subjects

M Corbett

Publications and source records attributed to M Corbett.

At least 19 recordsLinked to original sources
PubMed1995

A computer tomographic classification system for the displaced intraarticular fracture of the os calcis.

The treatment of the displaced intraarticular fracture of the os calcis continues to be controversial. One of the reasons for this is the lack of a workable classification system which would allow comparison among different treatment modalities. Plain radiographs are unable to depict the complex three-dimensional pathology of this fracture. Computed tomography (CT) scanning, however, has the potential to quite accurately depict all components of this injury. At our hospital, a five-part, CT-based classification system has been utilized. This system suggests which fractures will do well with conservative care, and which fractures are amenable to operative stabilization.

Ankle Injuries↗
PubMed1994

Nystagmus and joint position sensation: their importance in posterior occipitocervical fusion in rheumatoid arthritis.

It is widely believed that brain stem dysfunction and cranial nerve palsies in patients with rheumatoid arthritis (RA) are common and related to the vertical translocation of the odontoid process. In our database of 235 patients with seropositive RA and craniocervical junction involvement, we have found a very low incidence of such problems. Long tract signs were common, but loss of proprioception (joint position sensation) as the sole neurologic deficit was rare. Nystagmus was found to be associated with the tonsillar herniation of a Chiari 1 malformation and loss of joint position sensation with severe compression of the posterior aspect of the spinal cord at the craniocervical junction. The implications for posterior occipitocervical fusion, particularly by sublaminar wiring, are discussed.

Adolescent↗
PubMed1994

Polymorphic light eruption: prevalence in Australia and England.

The prevalence and clinical characteristics of polymorphic light eruption were assessed by a questionnaire survey of 172, 196 and 182 subjects in Perth, Ballarat and London, respectively. The prevalence was 5.2% in Perth (latitude 32 degrees), 3.6% in Ballarat (37.5 degrees) and 14.8% in London (51.5 degrees). The age distribution (mostly first three decades) and male:female ratio (1:3) was similar for affected individuals in all three areas. Development of tolerance during the summer was more common in Perth (66.7%) and Ballarat (71.4%) than in London (40.7%).

Adolescent↗
PubMed1994

Anti-myeloperoxidase antibodies in patients with rheumatoid arthritis: prevalence, clinical correlates, and IgG subclass.

OBJECTIVES: To determine the prevalence and clinical associations of autoantibodies to myeloperoxidase (MPO) in an unselected series of well-characterised outpatients with rheumatoid arthritis (RA) and to compare the distribution of IgG subclasses of anti-MPO antibodies in these patients with that in patients with systemic vasculitis. PATIENTS AND METHODS: A study was made of 97 patients with RA, who have been seen regularly in this department for up to 20 years, and 29 patients with anti-neutrophil cytoplasmic antibody (ANCA) positive systemic vasculitis. Anti-MPO antibodies were detected using a direct-binding enzyme-linked immunosorbent assay (ELISA) with MPO from human granulocytes as antigen. The IgG subclass of anti-MPO antibodies was determined by ELISA using isotype specific monoclonal antibodies. RESULTS: Anti-MPO antibodies were detected in 12% of patients with RA. Six sera contained IgG anti-MPO antibodies only, 1 IgM only and 5 antibodies of both classes. In the patients with RA the predominant subclasses were IgG1 and IgG3: only 2 sera contained detectable IgG4 antibodies. This was in contrast to patients with vasculitis, in whom most sera contained IgG1, IgG3 and IgG4 anti-MPO antibodies. Anti-MPO antibodies in sera from both patient groups bound only to the native protein. None of the patients studied with RA had evidence of vasculitis affecting the nerves or kidney: three patients (1 positive for anti-MPO antibodies and 2 negative) had cutaneous vasculitis. In the patients with RA, positivity for anti-MPO antibodies was associated with nodules and number of active joints. Three patients with anti-MPO antibodies, and none without, had pulmonary fibrosis. CONCLUSIONS: Twelve per cent of a group of unselected outpatients with RA, but without evidence of major systemic vasculitis, had anti-MPO antibodies in their serum. Positivity for anti-MPO antibodies was more common in patients with nodular disease and lung involvement but not in patients with cutaneous vasculitis. IgG4 sub-class anti-MPO antibodies were present in 90% of sera from patients with ANCA-positive vasculitis and only 2/11 (18%) of anti-MPO antibody containing sera from patients with RA.

Adult↗
PubMed1993

Purification and partial amino acid sequence of a mu opioid receptor from rat brain.

A rat brain opioid receptor protein was isolated by binding [epsilon-biotinyl-Lys32] beta-endorphin to membranes, solubilizing the receptor-ligand (R.L) complex with deoxycholate-lysophosphatidylcholine and purifying on immobilized streptavidin and wheat germ agglutinin. The purified glycoprotein had a molecular mass of 60-70 kDa. Recovery of this protein was blocked by the nonselective opioid antagonist naloxone and the highly mu-selective agonist [D-Ala2,N-methyl-Phe4,Glyol5]-enkephalin but not by the highly delta-selective agonist [D-Pen2,4'-Cl-Phe4,D-Pen5]enkephalin when these compounds were added as competitors at the binding step. The 60-70-kDa receptor protein co-purified through the streptavidin column with 40-kDa protein recognized by anti-Gi alpha antibodies. GTP and Na+ influenced dissociation of the solubilized R.125I-L complex and elution of the receptor and G protein from streptavidin in fashions consistent with the pharmacology of mu-opioid receptors. A 23-amino acid residue sequence from the purified receptor differs at 4 positions from a similar sequence in the murine delta-opioid receptor and is encoded within a novel rat brain cDNA isolated by polymerase chain reaction with oligonucleotide primers related to the murine delta-opioid receptor gene.

Amino Acid Sequence↗
PubMed1993

The rat SSTR2 somatostatin receptor subtype is coupled to inhibition of cyclic AMP accumulation.

The rat somatostatin receptor SSTR2 subtype has been cloned and expressed in Chinese Hamster Ovary (CHO) cells. Four different radioligands were used to determine the pharmacological properties of this somatostatin receptor subtype. [125ITyr11]S-14, [125ITyr25]S-28, and cyclo (D-Trp-Lys-Abu-Phe-MeAla-[125ITyr]) displayed comparable affinities for the SSTR2 subtype (approximately 100 pM). The affinity of a fourth radioligand, D-beta Nal-cyclo (Cys-[125ITyr]-DTrp-Lys-Val-Cys)-Thr-H2N, was approximately 10-fold lower (approximately 1000 pM) than the three other radioligands. Competition of [125I]S-14 with either S-14 or S-28 also revealed comparable IC50 values (250 pM). In CHO cells transfected with the SSTR2 cDNA, S-14 inhibited forskolin-stimulated cAMP accumulation by 75% in a dose-dependent fashion (EC50 = 350 pM).

Animals↗
PubMed1993

Factors predicting death, survival and functional outcome in a prospective study of early rheumatoid disease over fifteen years.

Sixty-four survivors from a prospective study of early rheumatoid disease were assessed again at a mean of 15.2 years from presentation and their status compared with 29 patients who had died. Eleven of the dead and only two of the survivors had been treated with steroids. There was a small increase in mortality due to the disease itself but only one death was directly caused by it. As might be expected, those who died were older. In the first year of disease, they had lower haemoglobin levels, a lower body mass, higher sedimentation rates and higher levels of blood urea. One-fifth at entry to the study and two-fifths by the time of death, had poor functional capacity. Of 64 survivors, six had poor functional capacity at entry and nine after 15 years. Discriminant analysis was performed to identify the most powerful combination of early features predicting a poor functional outcome. A combination including early erosive change, seropositivity, poor grip strength and cervical subluxation predicted the outcome correctly in 73% of survivors. Almost 60% of survivors remained with or improved to normal function at 15 years suggesting that morbidity is not as bad as has been suggested in the past.

Adult↗
PubMed1993

Radiological progression in rheumatoid arthritis: how many patients are required in a treatment trial to test disease modification?

OBJECTIVE: To determine whether the number of patients required in a therapeutic trial that uses progression of radiological abnormalities as the outcome measure would be similar for multiple centres. METHODS: The progression of radiological damage to the fingers and wrists of patients with rheumatoid arthritis in five centres, three in North America and two in Europe, was examined. The reproducibility of repeated readings by the same and multiple observers was examined. The number of patients required in a two group trial was calculated for several combinations of power and significance. RESULTS: Scoring progression of radiological abnormalities in sequential films taken between 0.5 and 2.1 years was found to be highly reproducible. When the scores of a single reader were used the rate of change of radiological scores was similar in all centres. Based on the mean progression rate for all centres it was estimated that 153 patients in each group would be required to assure 90% power for detecting a 50% slowing of radiological progression at a significance of 0.05. Review of the experience in three trials showed a large variability in the radiological progression rates. CONCLUSION: The progression of scores for radiological damage in rheumatoid arthritis is relatively uniform in North America and Europe and thus the number of patients required in a trial would be similar. Experience in three trials showed that patient selection is of paramount importance in setting up a successful study.

Adult↗
PubMed1992

Purification of a pituitary receptor for somatostatin. The utility of biotinylated somatostatin analogs.

A somatostatin (SRIF) receptor and its associated Gi regulatory proteins was purified from GH4C1 rat pituitary cells by: 1) saturation of the membrane-bound receptor with biotinyl-NH-[Leu8,D-Trp22,Tyr25] SRIF28 (bio-S28); 2) solubilization of receptor-ligand (R.L) complex with deoxycholate-lysophosphatidylcholine (D.L); 3) adsorption of solubilized receptor-ligand complex to immobilized streptavidin; and 4) elution of receptor and G-protein by GTP. The receptor, a glycoprotein with an average M(r) of 85,000, was then purified to substantial homogeneity on immobilized wheat germ agglutinin. The 85-kDa glycoprotein was identified as a SRIF receptor by several criteria. (a) It had the same size as the chemically cross-linked R.[125I]L complex. (b) Yield of the purified protein increased and plateaued in the same range of bio-S28 concentrations where specific high affinity binding reached saturation. (c) It was copurified with appropriate G-protein subunits. The 85-kDa receptor and two other proteins with M(r) values of 35,000 and 40,000, the sizes of G beta and G alpha, did not appear in eluates from control streptavidin columns done with SRIF receptors loaded with nonbiotinylated S14. The 40-kDa protein was identified as a Gi alpha by ADP-ribosylation from [32P]NAD catalyzed by pertussis toxin. (d) Both the chemically cross-linked R.[125I]L complex and SRIF receptor purified from [35S]methionine-labeled GH4C1 cells were reduced in size to about 38 kDa by endoglycosidase F. (e) Amino acid sequence from the purified receptor was nearly identical with that of a recently cloned SRIF receptor subtype.

Adenosine Diphosphate Ribose↗
PubMed1992

Partial amino acid sequence of a somatostatin receptor isolated from GH4C1 pituitary cells.

A somatostatin receptor isolated from GH4C1 rat pituitary tumor-derived cells was cleaved with cyanogen bromide or cyanogen bromide+trypsin to obtain sequenceable fragments. Five unique amino acid sequences ranging from 6 to 27 amino acid residues were obtained. The sequence was identical to sequence recently reported for one of two somatostatin receptors cloned from human pancreas [Yamada et al., (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 251-255] except for a single valine to isoleucine substitution. This is the first report of amino acid sequence from a purified somatostatin receptor.

Amino Acid Sequence↗
PubMed1992

Magnetic resonance imaging evaluation of calcaneal fat pads in patients with os calcis fractures.

Destruction of the calcaneal fat pad has been implicated as a source of chronic pain following fractures of the os calcis. Several investigators postulate that the initial trauma that produces a calcaneal fracture also results in destruction of the U-shaped fibrous septa that maintain the piston-like organization of the fat columns. Fibrosis and loss of the protective cushioning provided by the fat pad may eventually occur. The authors report on the largest series of magnetic resonance images of the calcaneal fat pad in the heels of patients with calcaneal fractures. A prospective consecutive study utilizing magnetic resonance imaging was performed on 22 heels with calcaneal fractures. Ten contralateral heels without calcaneal fracture and the heels of five normal subjects were scanned as controls. No signal changes suggestive of increased fat pad edema, fibrosis, or fatty release were detected. In addition, the vertical septa were well visualized and found to be intact in all cases. The height of the fat pad was measured, with no changes noted as compared with the contralateral heel. In those patients with acute fractures, signal changes suggestive of hematoma were well visualized in the soft tissue surrounding the calcaneus. In two of these cases, there was extension beneath the plantar fascia, but no penetration into the fat columns. Magnetic resonance imaging allows excellent detailed visualization of the calcaneal fat pad and surrounding structures. No evidence is found to support the hypothesis that marked damage to the gross structure of the fat pad occurs at the time of injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1992

Impact of short-term oral steroid use upon children's school achievement and behavior.

Physicians need clarification of whether the temporary use of adrenal corticosteroids to abort acute asthma can adversely effect school achievement and behavior problems. Nineteen nonsteroid-dependent asthmatic children were given prednisone orally while all other medications were kept constant. Five days later, when they were seen in the physician's office, an academic achievement test was administered to the child; and the child, a parent, and a teacher completed behavior rating surveys. After 2 weeks off the steroids the child returned to the physician's office and the achievement test and rating scales were completed again. There was no significant difference between the achievement test scores and behavior ratings in school or at home under the two conditions. Short-term use of oral steroids does not impair children's basic academic skills nor their behavior at school or home.

Administration, Oral↗
PubMed1988

A prognostic index for erosive changes in the hands, feet, and cervical spines in early rheumatoid arthritis.

Clinical and laboratory measurements taken at the onset of rheumatoid arthritis in 149 patients were compared with the severity of radiological changes seen at 3 years in the hands and feet, and cervical spine. The strongest association with the severity of peripheral radiological damage was rheumatoid factor (p less than 0.0001 for both the latex titre and RAHA titre). Subluxation of the cervical spine was associated only with the presence of HLA-Dw2 (p less than 0.02) and HLA-B7 cross-reacting group (p less than 0.02). Discriminant function analysis utilizing latex titre, RAHA titre, haemoglobin level, and platelet count predicted the development of erosive or nonerosive disease in 79%. This method was less successful in predicting the actual severity of erosive damage and was not improved by the addition of HLA data. Radiological outcome in the cervical spine was successfully predicted in 82% using HLA-Dw2, HLA-B27 and age of onset of disease. It is concluded that the best predictors of erosive disease were standard laboratory features measured at onset, but that more powerful discriminant factors are needed if these are to influence clinical practice. Further prospective studies will establish whether rheumatoid involvement of the cervical spine is an expression of the influence of HLA determinants in this disease.

Adult↗
PubMed1988

Antibodies to Klebsiella and Proteus microorganisms in ankylosing spondylitis and rheumatoid arthritis patients measured by ELISA.

Antibodies to Klebsiella oxytoca and Proteus mirabilis in 21 active ankylosing spondylitis (AS), 13 active rheumatoid arthritis (RA), 19 inactive RA patients and 18 healthy controls were measured using enzyme-linked immunosorbent assay (ELISA). Elevated anti-Klebsiella antibodies were demonstrated in active AS patients compared to active RA (p less than 0.01), inactive RA patients (p less than 0.001) and controls (p less than 0.005). When measuring antibodies to Proteus, active RA patients showed higher levels of antibodies compared to active AS patients (p less than 0.005) and healthy controls (p less than 0.05). Further investigations are required to assess the role of Klebsiella and Proteus microorganisms in AS and RA respectively.

Adult↗
PubMed1988

IgA and IgM rheumatoid factors as markers of later erosive changes in rheumatoid arthritis (RA).

Stored samples from within the first year of disease of 119 patients with rheumatoid arthritis (RA) enrolled in a long-running prospective study have been studied for the presence of IgM and IgA rheumatoid factors (RF), using agglutination of rabbit IgG-coated red blood cells to detect IgMRF and an ELISA technique using rabbit IgG coated on the microtitre plates and labelled F(aB)2 fragment of goat anti-IgA. Outcome measures at a mean follow-up of 10.1 years (range 3-20) included the Steinbrocker functional grade and grading of erosive changes on hand and feet Xrays using a modification of Lawrence's method. Both IgA and IgG levels at presentation correlated significantly with outcome measured by erosive changes and functional grade at a mean of 10 years and with the time of first appearance of erosions. In patients who are IgMRF negative early in the disease, IgARF positivity indicates a greater chance of developing both erosions and impaired function than when both tests are negative. IgARF positivity seems to precede IgMRF.

Adult↗
PubMed1988

Dysgonic Fermenter-type 2: an emerging zoonosis. Report of two cases and review.

We report Dysgonic Fermenter-type 2 septicaemia presenting in two previously healthy individuals, and review 52 cases of infection with Dysgonic Fermenter-type 2 reported in the English language literature. This zoonosis is usually acquired through contact with dogs and cats. Infection often presents with little warning to patient or physician and carries a high mortality. The immunosuppressed patient, those without a spleen, alcoholics and those with chronic disease appear to be most susceptible, although the healthy individual is also prone to infection. The infection is probably underdiagnosed due to difficulties in isolating Dysgonic Fermenter-type 2 by conventional blood culture techniques. Clinical and microbiological awareness is of prime importance in the early diagnosis of this potentially lethal infection.

Animals↗
PubMed1987

A prospective study of early onset rheumatoid arthritis over fifteen years: prognostic features and outcome.

A total of 218 patients with early onset rheumatoid arthritis were entered into a prospective study over fifteen years. Of these, 151 remained in the study at three years (of whom 14 died), and a further 39 (23 deaths) defaulted after this time. The severity of disease was assessed by four different methods. Although persistently active joint disease was recorded in 26% of patients, only 13% had severe functional impairment, and only 14% developed severe erosions. An episode of RA lasting two to three years followed by complete remission with none or minimal sequelae ("non recurrent" RA) was present in 34%. Using discriminant analysis, which selected rheumatoid factor, haemoglobin level and platelet count from a number of clinical and laboratory variables measured at onset, it was possible to predict three mutually exclusive outcome categories correctly in 50-60% of patients depending on the method of assessment of outcome.

Adolescent↗