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Biomedical subjects

T Mokoena

Publications and source records attributed to T Mokoena.

23 records · Page 2Linked to original sources

Surgical management of mycotic aneurysms.

Mycotic aneurysms not associated with trauma or atherosclerosis are uncommon. Their clinical presentation is insidious and lacks definite diagnostic criteria. This retrospective study of 14 patients treated over a period of 9 years confirms this, and shows that half are associated with a predisposing infected focus and that the main presenting clinical feature is that of a painful mass (64%) which is often mistaken for some other diagnosis. The main extracranial, extrathoracic site of predilection was the iliofemoral segment (65%). The main diagnostic investigation was angiography, which was also used to uncover silent aneurysms elsewhere in the arterial tree. Urgent surgical treatment is mandatory since complications may occur at any time and these may include life-threatening bleeding. Two of our patients experienced life-threatening gastro-intestinal bleeding while in hospital. The mainstay of treatment was surgical resection and reconstruction using an autologous vein or artery if possible. The more serious complication of graft failure was encountered mainly in patients who underwent prosthetic graft repair. It is in this group that 2 of the 3 early postoperative deaths occurred, from graft thrombosis and mesenteric infarction. Overall, surgical repair was attended with good outcome (77%).

Adolescent↗

Interferon gamma induces synthesis of complement alternative pathway proteins by human endothelial cells in culture.

Human umbilical vein endothelial cells grown in vitro under standard conditions contain a high level of mRNA specific for the complement regulatory factors H and I. An additional 1.8-kb mRNA encoding a truncated form of factor H is also present. IFN-gamma stimulation of the cells causes a 6-7 fold increase in both factor H mRNA species, and a greater than 10-fold increase in factor I mRNA. IL-1 and LPS slightly suppressed factor H mRNA, while TNF had no effect. mRNA for factor B is also detectable in IFN-gamma-stimulated cells, but messengers for C1q, C4bp, and CR3 beta chain were not found. Secretion of factor H protein was also stimulated by IFN-gamma. The presence of mRNA for factors H, B, and I, together with C3 secretion, demonstrated by others, suggests that endothelial cells can assemble the complete alternative complement pathway. Endothelial cell complement may be involved in leukocyte-endothelium interactions mediated by leukocyte C3 receptors.

Blotting, Northern↗

Human macrophage activation. Modulation of mannosyl, fucosyl receptor activity in vitro by lymphokines, gamma and alpha interferons, and dexamethasone.

We describe a sensitive assay to measure immune activation of human macrophages in cell culture. Freshly isolated blood monocytes from normal subjects lack the ability to endocytose and degrade mannosyl-terminated glycoconjugates via specific receptors, but acquired this activity after cultivation in autologous serum for approximately 3 d. Addition of specific antigen, purified protein derivative, or T cell mitogens to mononuclear cells prevented the appearance of macrophage mannosyl receptor activity and lymphokine, gamma-, and alpha-interferons selectively down-regulated receptor activity in monocyte-macrophage targets. The effects of antigen challenge and gamma-interferon on mannosyl receptors can be prevented by 10(-8) M dexamethasone. Dexamethasone also inhibited release of another macrophage activation marker, plasminogen activator, which was increased by both gamma- and alpha-interferons. These studies show that activation of human macrophages is regulated by opposing actions of lymphokines and glucocorticoids.

Adult↗