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Biomedical subjects

M Greaves

Publications and source records attributed to M Greaves.

268 records · Page 15Linked to original sources

Selective triggering of human T and B lymphocytes in vitro by polyclonal mitogens.

Human lymphocytes from spleen and tonsils have been cultured with a variety of polyclonal mitogens. Cultures consisted of either unseparated T and B cells or alternatively purified T or B lymphocytes. The purity of the starting cell populations and the origin of activated lymphoblasts was analyzed with a panel of seven markers which discriminate between T and B cells. The selectivity of the lymphocyte responses was influenced by cell populations in a given culture, the mitogen used, and to a limited extent on culture conditions. Purified T lymphocytes from tonsil and spleen responded to phytohemagglutinin (PHA), pokeweed mitogen (PWM), and staphylococcal enterotoxin B (SEB). Purified B cells from spleen responded well to PWM, weakly to SEB and lipopolysaccharide, but not at all to PHA. Tonsil B cells responded weakly to PWM and SEB but not to PHA. Some B lymphocytes do respond to PHA in the presence of activated T cells. These results are discussed in relation to previously reported selective responses of human cells and parallel studies in animal species.

B-Lymphocytes↗

Responses of skin blood vessels to bradykinin, histamine and 5-hydroxytryptamine.

1. The responses of human cutaneous blood vessels to intradermal injection of bradykinin, histamine and 5-hydroxytryptamine (serotonin) are studied in order to evaluate the ability of these agents to mediate the vascular changes of sustained acute inflammation in the skin.2. Bradykinin produces erythema, owing to a direct effect on blood vessels, and wealing. Dose-response studies indicate that bradykinin is more potent than serotonin or histamine in respect of wealing.3. The response to serotonin differs qualitatively as well as quantitatively according to dose. High doses cause wealing and erythema with the characteristics of an axon reflex flare, but low doses produce erythema by a local effect without wealing.4. Using the technique of arterial occlusion, the occurrence of tachyphylaxis in respect of wealing was demonstrated with histamine and serotonin, but not with bradykinin. This evidence suggests that of the three agents, only bradykinin can mediate increased vascular permeability in sustained acute inflammation.5. The specificity of tachyphylaxis and the failure of anti-histamine to antagonize bradykinin wealing suggest that bradykinin and histamine act on separate blood vessel receptors.6. Corticosteroids do not inhibit wealing due to a wide range of doses of bradykinin. The anti-inflammatory activity of corticosteroids may therefore be due to reduced formation of kinins.

Adult↗

No excess of factor V:Q506 genotype but high prevalence of anticardiolipin antibodies without antiendothelial cell antibodies in retinal vein occlusion in young patients.

Factor V:Q506 (factor V Leiden) is associated with venous thrombosis and has been reported to be a risk factor for retinal vein occlusion (RVO). Anticardiolipin antibodies (ACA), also associated with RVO, are a marker for the prothrombotic condition antiphospholipid syndrome, in which antiendothelial antibodies (AECA) are also frequently present. This study reviewed 45 younger patients 10 GPL units); in 6 of these, the titre was >20 GPL units (population reference range = 0-10 GPL units). No patient had antiendothelial cell reactivity. The low-titre ACA may therefore represent a non-specific response to vascular injury.

Activated Protein C Resistance↗

Thrombophilia.

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Humans↗

Clinical experience with the use of charcoal haemoperfusion: is prostacyclin required?

Twenty patients have undergone a total of 47 charcoal haemoperfusions without the use of prostacyclin. A fall in platelet numbers and evidence of platelet activation have been found during haemoperfusion but few clinical complications have been observed. Therefore, we believe that the clinical value of the addition of prostacyclin during charcoal haemoperfusion has not been proven. Nevertheless, its apparent protective effect on platelet numbers and activation indicates that further controlled trials of the use of prostacyclin during charcoal haemoperfusion are required.

Acetaminophen↗