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Biomedical subjects

R J Powell

Publications and source records attributed to R J Powell.

At least 163 records · Page 9Linked to original sources
PubMed1990

Dermatomyositis following chronic staphylococcal joint sepsis.

A young man is reported with recurrent Staphylococcus aureus joint sepsis associated with dermatomyositis. His dermatomyositis failed to resolve on treatment with antimicrobial agents alone, indicating that if staphylococcal infection was the triggering event for the dermatomyositis then the subsequent process was apparently self perpetuating, requiring cytotoxic agents for its control. This case can be interpreted as possible further evidence for the triggering of autoimmune disease by infective agents.

Adolescent↗
PubMed1990

Developmental expression and cDNA cloning of globin genes from the brine shrimp, Artemia.

The brine shrimp, Artemia, is unusual in having large (130 kD) extracellular hemoglobins composed of two globin chains, each of which is a polymer of at least eight myoglobin-like domains. Hemoglobin first appears at the time of naupliar hatching apparently as a result of a physiological switch. Globin gene expression is induced at this time, indicating transcriptional control of hemoglobin synthesis during early development. From a globin partial cDNA clone constructed by a primer extension strategy, we have derived the amino acid sequence of a region that links two of the myoglobin-like domains together. The post H region of the myoglobin-like domain has adapted to accommodate the fusion of these domains. We used the partial cDNA to isolate two classes of large clones containing globin cDNA, and thus established that there are at least two distinct hemoglobin genes in Artemia.

Amino Acid Sequence↗
PubMed1989

The incidence of decreased red blood cell deformability in sepsis and the association with oxygen free radical damage and multiple-system organ failure.

We studied the incidence of decreased red blood cell deformability (RBCD) in sepsis and the association between decreased RBCD and oxygen free radical generation (as measured by malonyldialdehyde) and the occurrence of multiple-system organ failure (MSOF). Patients were divided into three groups: septic (n = 28), nonseptic (n = 15), and control (n = 5). Serial measurements of deformability index, malonyldialdehyde, and MSOF were made. The deformability index for the septic group (0.23 +/- 0.17) was significantly less than that for the nonseptic (1.12 +/- 0.48) and control (1.11 +/- 0.25) groups. The malonyldialdehyde levels for the septic group (4.5 +/- 1.0 nmol/mL) were significantly greater than those for the nonseptic (2.7 +/- 0.9 nmol/mL) and control (2.6 +/- 0.8 nmol/mL) groups. The MSOF index for the septic group (10.1 +/- 2.5) was significantly greater than that for the nonseptic (7.6 +/- 1.7) and control (6.0 +/- 0.0) groups. An inverse correlation existed between malonyldialdehyde and deformability index ( = .501, less than .001, n = 40) and between deformability index and MSOF index (= .350, less than .05, n = 61). We conclude that RBCD is decreased during human sepsis; free radicals generated during sepsis may play a role in the decrease in RBCD. Decreased RBCD may contribute to the MSOF that occurs during sepsis.

Adult↗
PubMed1989

Defective fibrinolysis in Behçet's syndrome: significance and possible mechanisms.

Reduced fibrinolytic activity has frequently been reported in Behcet's syndrome, but both the underlying mechanism and its relation to the development of thrombosis are unclear. The fibrinolytic activity was studied in seven patients with Behçet's syndrome and 12 patients with idiopathic oral ulceration. The patients with Behçet's disease had significantly reduced resting tissue plasminogen activator(t-PA) both by euglobulin fibrin plate lysis and enzyme linked immunosorbent assay (ELISA), but the tissue plasminogen activator inhibitor(t-PAI) was not significantly different from the control value. After stimulation by venous occlusion the euglobulin fibrin plate lysis results showed three good responders and four poor responders, but neither t-PA antigen nor t-PAI concentrations showed any clear difference between the two groups. Interestingly, three out of the four patients with a history of thrombosis were good responders. The group with oral ulceration showed no significant difference from the controls for any of these measurements. These findings suggest that the reduced resting fibrinolytic activity is usually due to decreased production of t-PA, but that the defective response to stimulation may be multifactorial in origin. The fibrinolytic abnormalities appear unrelated to the development of thrombosis.

Adult↗
PubMed1989

Frequency-resolving ability in systemic lupus erythematosus.

An audiological investigation was performed of 20 patients suffering from the well characterized autoimmune disease systemic lupus erythematosus (SLE). In addition to threshold estimations, psychoacoustical tuning curves were measured to provide an indication of frequency-resolving ability. Comparison of these data with age, sex and socioeconomically matched controls did not show that the SLE group had significantly worse hearing.

Adolescent↗
PubMed1988

Abnormal fibrinolytic activity in systemic lupus erythematosus and possible mechanisms.

Plasma fibrinolytic activity was measured in 34 patients with systemic lupus erythematosus (SLE) and 12 normal subjects. Patients with SLE showed a significantly reduced resting level of plasma tissue plasminogen activator (t-PA) compared to normal. The reduction in t-PA was demonstrated both by a functional assay (fibrin-plate lysis, FP) and an immunochemical assay (ELISA). Measurement of the fibrinolytic response following venous occlusion allowed division of the patients into two groups. In the first (24 patients), there was a normal increase in t-PA response, demonstrated both by the functional and immunochemical assays. In the second (10 patients), there was a significantly reduced plasma t-PA response measured by FP. Seven of the patients in this second group, which included four patients with histological evidence of vasculitis, showed a similar failure of t-PA response (ELISA) after venous occlusion. These results suggest that their impaired fibrinolytic response may be related to defective t-PA release secondary to endothelial cell damage. The remaining three patients in the latter group had a normal t-PA (ELISA) response despite a reduced FP response, suggesting the presence of an inhibitor.

Adult↗
PubMed1988

Radioimmunoassay artifact associated with circulating anti-rabbit antibodies.

A 30 year old woman presenting with infertility was found to have elevated serum immunoreactive prolactin, TSH and total T3. These findings were eventually attributed to assay artifact when she was shown to have anti-rabbit antibodies in her serum. The possibility of laboratory artifact should be considered in clinical practice when abnormal immunoassay results are unsupported by clinical or radiographic data.

Adult↗
PubMed1987

C3 degradation products (C3d) in normal pregnancy.

Plasma C3 degradation products (C3d) were measured in 65 normal pregnancies and compared with those of non-pregnant women. No significant difference was detected between the two groups, although a difference had been previously reported. Plasma C3d estimations give an indication of complement activation and may be used as an indicator of disease activity in patients with systemic lupus erythematosus (SLE), irrespective of pregnancy.

Complement C3↗
PubMed1987

Novel C3 nephritic factor activity in the glomerulonephritis of staphylococcal endocarditis.

A case of glomerulonephritis complicating staphylococcal endocarditis is presented. Hypocomplementaemia and a C3-activating factor in the serum suggested that the patient might have mesangiocapillary glomerulonephritis in association with C3-nephritic factor. Renal biopsy showed that this was not so and further examination of the serum factor showed that it differed from classical C3-nephritic factor because it was not an immunoglobulin. It is postulated that complement activation and glomerulonephritis in staphylococcal endocarditis may be the direct result of a bacterial product. A substance in the serum which activates C3 should be confirmed to be an immunoglobulin before the presence of classical C3-nephritic factor is assumed.

Complement Activation↗
PubMed1986

Rheumatoid factor tests in the diagnosis and prediction of rheumatoid arthritis.

Four assays of rheumatoid factor (RF) have been measured on serum from 213 individuals from 13 families containing at least two sufferers from classical or definite rheumatoid arthritis (RA). Families were not uniformly RF positive or negative, and there was no evidence that non-RA RF positivity was inherited. Four individuals developed definite RA over a two year period, showing that the family members were at increased risk of RA. IgG RF and latex RF assays predicted the RA in the four cases. An association of RF positivity in RA with DR4 was observed, but this may be related to disease severity.

Arthritis, Rheumatoid↗
PubMed1985

Immunological tests and the diagnosis of dementia in elderly women.

Serum immunoglobulins and circulating antinuclear antibodies were assayed in 91 elderly female in-patients with dementia. Clinical criteria were used to distinguish a group with multi-infarct dementia from those with senile dementia of Alzheimer type and the results were compared with those of 19 age-matched controls. Dementia patients aged 85 and over had a higher prevalence of antinuclear antibodies (P less than 0.05) and those aged 90-95 had higher levels of IgA than younger age groups (P less than 0.025). IgG levels were higher than controls in the 'multi-infarct' group (P less than 0.025).

Aged↗