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Biomedical subjects

P Davis

Publications and source records attributed to P Davis.

At least 397 records · Page 22Linked to original sources
PubMed1980

Inhibition of nerve-mediated contractions in isolated guinea-pig ileum by 1-methylisoguanosine, a novel purine from a sponge.

1-Methylisoguanosine, a novel purine isolated from the sponge Tedania digitata (Schmidt) selectively inhibited contractions produced by nerve stimulation in the guinea-pig ileum but was without effect on contractions produced by acetylcholine or histamine. The ED50 for inhibition of nicotine responses or responses to submaximal transmural stimulation was 1.1 mumoles/l. The inhibition of nerve-mediated contractions appeared to be due to inhibition of transmitter release from nerve endings in the ileum, as has been suggested for the action of adenosine. Theophylline antagonized the action of 1-methylisoguanosine and overall the results suggest that 1-methyl-isoguanosine acts at an adenosine receptor in the guinea-pig ileum, but is approximately ten times more potent than adenosine itself. A series of related purines which were resistant to the action of adenosine deaminase were also tested for their effect on the nerve-mediated contractions of guinea-pig ileum and the results compared with the in vivo effect on muscle relaxation in mice. All active purines tested produced results qualitatively similar to those of 1-methylisoguanosine itself.

Adenosine↗
PubMed1980

A controlled study of plasma exchange in the treatment of severe rheumatoid arthritis.

To learn whether the removal of immune complexes from the circulation by plasma exchange could effect an improvement in disease activity in rheumatoid arthritis (RA) patients, we performed a controlled study of 20 patients, we performed a controlled study of 20 patients with severe progressive disease which had not responded to previous therapy. Ten patients (Group 1) were hospitalized, continued on their regular anti-inflammatory medication, and given a graded course of physiotherapy. A further 10 patients (Group 2) received the same treatment as the first group with the addition of a concurrent course of plasmapheresis. Clinical measurement of disease activity after treatment revealed little difference between the two groups with a statistically significant improvement in four measures in Group 1 and in five in Group 2. Laboratory studies suggested that the intensity of plasma exchange was sufficient to remove circulating immune complexes in these patients. Our results confirm that hospitalization in itself is of benefit in the treatment of acute exacerbations of rheumatoid arthritis. The marginal improvement achieved by the addition of plasma exchange in the management of these patients (despite the removal of circulating immune complexes) makes its short-term use of questionable value in the treatment of severe rheumatoid arthritis.

Adult↗
PubMed1980

Angioimmunoblastic lymphadenopathy associated with polyarthritis.

A patient with angioimmunoblastic lymphadenopathy with dysproteinaemia is described. The patient had a severe clinical illness with a pronounced haemolytic anaemia, which followed well-established polyarthritis and gold therapy. It was accompanied by in-vitro evidence of suppressed cell-mediated immune responses and by development of serum antismooth muscle antibodies. These features are unusual and support theories that this disease has an immunological basis. Improvement occurred with prednisone and azathioprine therapy, suggesting that combined use of these agents is useful in some patients with AILD. The patient subsequently developed a lymphoma.

Anemia, Hemolytic↗
PubMed1980

Seronegative chronic polyarthritis: clinical and serological correlates.

Twenty-seven patients with chronic, active, seronegative polyarthritis were assessed clinically and serologically by accepted criteria for evidence of connective tissue diseases. The patients were divided into 2 groups, 13 positive for fluorescent antinuclear antibody (FANA) and 14 that were negative. All but 1 patient fulfilled the clinical criteria for the diagnosis of definite rheumatoid arthritis. Four patients (2 in each group) fulfilled the preliminary criteria for the classification of systemic lupus erythematosus. Antiperinuclear factor was positive in 5 of the FANA-negative patients, consistent with a diagnosis of rheumatoid arthritis. By contrast, this factor was absent in all the FANA-positive patients. Positive DNA binding was found in 7 of the FANA-positive patients, in high titre in 4, consistent with a diagnosis of 'minimal lupus' with predominantly 'unisystem' disease. DNA binding was positive in low titre in 2 of the FANA-negative patients. Antibodies to extractable nuclear antigens (ENA) were found in 4 patients with a positive FANA and in only 1 FANA-negative patient. The current clinical criteria showed poor discriminatory value in classifying cases of seronegative polyarthritis, which may represent mild cases of other connective tissue disease presenting with synovitis in the absence of extra-articular disease manifestations.

Antibodies, Antinuclear↗
PubMed1980

Antibody to synthetic poly dAT: correlation with antibody to native DNA and specificity for SLE.

Antibodies to synthetic 3H-poly dAT have the advantage over antibody to native DNA in that they have a higher degree of specificity for systemic lupus erythematosus (SLE). This is because poly dAT eliminates the problem of measurement of single stranded antibodies that are not specific for any one condition but which may be detected by native DNA preparations which usually contain single stranded regions. The overall degree of correlation between the two antibodies is good in SLE. Antibodies to poly dAT correlate well with clinical evidence of disease activity but in this study were not particularly associated with the presence of renal disease.

Antibodies↗
PubMed1980

In vivo imaging of the rat anatomy with nuclear magnetic resonance.

Live rats were imaged by nuclear magnetic resonance (NMR). These images demonstrated fine detail and high object contrast. Motion artifacts are not apparent in 4-minute images, and major blood vessels are demonstrated as regions of low signal intensity because of blood flow. Selective contrast enhancement is possible by varying NMR imager accumulation parameters.

Animals↗
PubMed1980

Evaluating students in family medicine using simulated patients.

Various techniques have been used to evaluate students in family medicine clerkships and electives. Multiple choice or essay questions have been used extensively but are not satisfactory in testing some of the affective areas considered important for future family physicians. At Southern Illinois University School of Medicine, the Department of Family Practice has evolved an evaluation system using simulated patients as well as traditional methods. Simulated patients have proved to be an excellent means of evaluating affective skills which are not easily tested by other techniques.

Clinical Competence↗
PubMed1980

Antibodies to DNA in patients undergoing long-term hemodialysis.

It has been suggested that antibodies to native DNA occur with some frequency in patients treated by hemodialysis. This has been attributed to the use of the technique. We have investigated 48 patients on maintenance dialysis for the presence of antibodies to single stranded DNA (ss-DNA) and native DNA (n-DNA) compared to a control group of 25 nondialyzed patients with renal disease. In neither group of patients were antibodies to ss-DNA detected frequently. Antibodies to n-DNA were present in three of the dialyzed patients and in none of the control group. The frequency of antibodies in dialysis patients was insignificant in comparison to the same control group of non-dialyzed renal patients. There was no correlation between duration of dialysis and development of antibodies. A drug-induced lupus state is possible, but not established for two of the three patients on dialysis.

Adult↗
PubMed1979

Antibody dependent cell-mediated cytotoxicity to herpes simplex virus in man: the influence of drugs on polymorphonuclear leucocyte and mononuclear effector cells.

We have shown that the function of the effector cells in antibody mediated cell dependent cytotoxicity (ADCC) can be reduced by the use of a number of drugs and prostaglandins. Both polymorphonuclear leucocyte and mononuclear effector cells were studied. Aminophylline and isoproterenol markedly reduced this activity. All the prostaglandins tested--PGA1, A2, E1 and E2 had a similar but more profound effect. At a dose of 100 mg/ml hydrocortisone had relatively little influence and neither ASA nor indomethacin had any effect on the effector cells tested. It is suggested that the effect of PGE1 in stimulating a recrudescent herpes simplex infection may be by reducing the efficacy of ADCC in host defence.

Aminophylline↗
PubMed1979

Quantitative sacroiliac scintigraphy in ankylosing spondylitis and Crohn's disease: a single family study.

A single family is presented in which 2 of the 3 sibs and 3 of 9 first degree relatives had Crohn's disease. Two subjects with Crohn's disease had classical ankylosing spondylitis (AS), and HLA typing revealed HLA B27 in all 5 members of the immediate family. The value of quantitative sacroiliac scintigraphy (QSS) in clinical practice is demonstrated. Both patients with AS had evidence of currently active sacroiliac disease in association with radiological change. One symptomatic sib had QSS evidence of sacroiliitis without radiological abnormality.

Adolescent↗
PubMed1979

Sequential observations of in vitro responses of lymphocytes to phytohemagglutinin in patients receiving gold therapy for rheumatoid arthritis.

Forty-seven patients receiving gold therapy for rheumatoid arthritis were observed sequentially at 6-monthly intervals. When the disease was in remission, and remained so, the in vitro responses of lymphocytes to phylohemagglutinin stimulation tended to be normal. Improvement in the disease were associated with improvement in lymphocyte response and deterioration associated with depression of response. Our observations suggest that these changes are a reflection of disease activity and their relationship to gold therapy is indirect.

Arthritis, Rheumatoid↗
PubMed1979

In vitro binding and pharmacokinetics of gold salts in plasma proteins and chelating agents.

The binding of sodium aurothiomalate, sodium aurothiosulphate and aurothioglucose to plasma proteins has been investigated in vitro. All gold compounds were bound to protein at a similar rate and had similar apparent affinity constants and binding capacities. Penicillamine (10 or 100 microgram/ml) was unable to chelate significant amounts of bound gold from plasma protein.

Aurothioglucose↗
PubMed1979

Effect of gold salts on adherent mononuclear cells in tissue culture.

Adherent mononuclear cells from normals and patients with rheumatoid arthritis (RA) were isolated and effects of gold salts on cell cultures assessed in vitro. Phagocytic function of adherent mononuclear cells was assessed by the injestion of opsonized chicken red blood cells. Absolute numbers of phagocytic cells were higher in the RA patients than normals. Gold salts in concentrations 0.5-5.0 microgram/ml significantly reduced the numbers of both adherent and phagocytic cells when compared to control cultures. This suppression was particularily marked in the RA patients and was dose and time dependent. However, mononuclear cells surviving incubation with gold salts appeared to maintain phagocytic function in similar proportions to control cultures.

Arthritis, Rheumatoid↗
PubMed1979

Undesirable effects of gold salts.

A review of recent studies of undesirable effects of gold salts is presented. Marrow aplasia is potentially the most serious side effect with a poor prognosis. Its prevalence is undetermined but may have been overestimated. Gold nephropathy and thrombocytopenia although more common usually have a good prognosis. Both can be satisfactorily treated without prolonged morbidity or mortality. Mucocutaneous reactions although more common are rarely of serious importance and need not necessarily prevent completion of a therapeutic course of gold salts. When indicated the side effects of gold salts can be adequately treated by cessation of therapy and use of corticosteroids. The value of chelating agents is desirable.

Anemia, Aplastic↗
PubMed1979

In vitro testing of immunoresponsiveness in patients with inflammatory bowel disease: prevalence and relationship to disease activity immunoresponsiveness in IBD.

Abnormalities in the numbers and function of thymus and function of thymus-derived and bone marrow-derived lymphocytes (T and B cells) and K cells were determined in sixty-nine consecutive patients with Crohn's disease or ulcerative colitis. Rosetting techniques to identify subpopulations of lymphocytes showed a significant decrease in E-rosettes (T cells) and significant increase in EA- and EAC-rosettes (B cells) in patients with inflammatory bowel disease when compared to normals. In vitro lymphocyte transformation responses to mitogens and antigens were depressed to a variable degree. Mean levels of K cell activity were not significantly different from normal controls. A considerable degree of individual variation was noted in all groups. When the results of each groups were considered, none of the laboratory variables correlated with the site, duration or activity of disease, therapy, presence of iron deficiency anemia, weight loss or hypoalbuminaemia. Thus, in vitro evidence of abnormal immune responses in patients with inflammatory bowel disease cannot be directly related to clinical or laboratory variables and probably reflects a multi-factorial aetiology.

Adolescent↗
PubMed1979

Evidence for a therapeutic effect of plasmapheresis in patients with systemic lupus erythematosus.

Fourteen patients with active systemic lupus erythematosus (SLE) have been treated with plasmapheresis at a rate of two litres daily on three to four days per week, over a period of two to three weeks. Plasma was replaced isovolemically with either fresh frozen plasma or with human plasma protein fractions. Ten patients were receiving treatment with prednisone at the time of plasmapheresis, and four had received no prior treatment. Eight patients showed evidence of either clinical improvement or clinical and immunochemical improvement, at the time of plasmapheresis. In the three patients who showed high levels of circulating complexes before treatment, there was a sudden fall in the level of circulating immune complexes, which was quantitatively greater than could be explained by the amount removed. This suggests that in some patients with SLE, clearance of complexes by the mononuclear phagocytic system is initially blocked by high levels of circulating complexes and that one effect of plasmapheresis may be to relieve this blockade. Five patients showed a clinical response to plasmapheresis despite the fact that tests for immune complexes were negative. Three patients showed no response to plasmapheresis, and three were regarded as unevaluable. In a limited number of patients, who show a high level of circulating immune complexes, and whose condition is deteriorating despite treatment with corticosteroids, there may be an important therapeutic role for plasmapheresis.

Adolescent↗
PubMed1978

Evidence for sacroiliac disease as a common cause of low backache in women.

99M Tc stannous pyrophosphate bone scanning with quantitative sacroiliac scintigraphy (Q.S.S.) has been used in 50 females with low backache and in 66 symptomless female controls. Mean uptake of radionuclide at the sacroiliac joints was significantly increased in the patients when compared with controls. Q.S.S. gave objective evidence of unilateral sacroiliac disease in 2 of the 66 controls compared with that of unilateral and bilateral sacroiliac disease in 8 and 14 of the 50 patients respectively. Of the 22 patients with abnormal scans, 20 had normal radiographs. An abnormal scan did not correlate with the presence of HLA B27. It is concluded that sacroiliac disease is a common cause of low backache in women, and that it can be objectively diagnosed by Q.S.S. when radiographs are normal.

Adult↗