Anne Marie Lane

Determinants of Plasminogen Activator Inhibitor 1 Activity in Treated NIDDM and Its Relation to a Polymorphism in the Plasminogen Activator Inhibitor 1 Gene

Plasminogen activator inhibitor 1 (PAI-1) activity is increased in patients with non-insulin-dependent diabetes mellitus (NIDDM) and may contribute to their excess risk of cardiovascular disease. We examined the determinants of PAI-1 activity in 146 NIDDM subjects by using specific assays of insulin and intact and des-31,32-proinsulin and measures of insulin resistance, relating these measurements to serum lipids, hypoglycemic therapy, and a common 4G/5G polymorphism in the promoter region of the PAI-1 gene. Subjects were treated with insulin, sulfonylurea, sulfonylurea plus metformin, metformin, and diet alone. In the whole group, PAI-1 activity correlated significantly with serum triglycerides (r = 0.39, P < 0.001), specific insulin (r = 0.29, P < 0.001), intact proinsulin (r = 0.24, P = 0.004), and des-31,32-proinsulin (r = 0.30, P < 0.001) and in subjects not on insulin (n = 110), with insulin sensitivity (r = −0.42, P < 0.001). There was a significant difference in PAI-1 activity among the three genotypic groups (P = 0.016); subjects with the genotype 4G/4G had PAI-1 levels one-third higher than those with the 5G/5G genotype. In the 4G/4G group, PAI-1 activity correlated significantly with triglyceride levels (r = 0.65, P < 0.0001). There was no significant difference in PAI-1 activity in the different treatment groups despite a significant difference in concentrations of intact and des-31,32-proinsulin. In a multiple regression model, insulin sensitivity and the interaction between PAI-1 4G/5G genotype and triglyceride were the strongest determinants of PAI-1 activity.In conclusion, in this sample of NIDDM subjects, the influence of triglyceride on PAI-1 seems to be genotype dependent, and this interaction is a major determinant of PAI-1 activity.

Cytokine production by cholesterol-loaded human peripheral monocyte-macrophages: the effect on fibrinogen mRNA levels in a hepatoma cell-line (HepG2)

Conditioned medium from human monocyte-macrophages incubated under various conditions was tested for its ability to stimulate fibrinogen mRNA levels in the hepatoma cell line HepG2. Recombinant human interleukin-6 (IL-6) stimulated fibrinogen mRNA levels 4.4-fold over control levels; this response was blocked by an anti-IL-6 antibody. Conditioned medium from 3-day-cultured monocyte-macrophages produced a slight stimulation of fibrinogen synthesis in HepG2 cells which was enhanced when the monocyte-macrophages had been treated with lipopolysaccharide (LPS). This stimulation was blocked by the anti IL-6 antibody. The cytokines, interleukin-1 (IL-1) and tumour necrosis factor (TNF) were also detected in the conditioned medium from the 3-day-cultured monocyte-macrophages. Monocyte-macrophages were cultured for 17 days and then incubated with acetylated low density lipoprotein (AcLDL) for 48 h. Such cells were foamy in appearance and showed a 4-fold increase in apoE mRNA and a 10 to 50-fold increase in apoE secretion. This increase in apoE production was suppressed by almost a third when cells were coincubated with AcLDL and LPS. Conditioned medium from these 17-day-cultured AcLDL-treated human monocyte-macrophages did not stimulate fibrinogen mRNA synthesis in HepG2 cells, nor did the conditioned medium contain detectable levels of cytokines. These results suggest that cytokine production from foam cells in the atherosclerotic lesion is unlikely to be a major contributing factor in determining the elevated fibrinogen levels seen in the plasma of patients with IHD.

Identification of genetic variation that determines levels of plasma triglycerides and hypercoagulability

For many years, there has been controversy about the relative importance of elevated plasma levels of triglycerides as a risk factor for ischaemic heart disease (IHD). Although showing a significant univariate association with IHD risk in many studies (Assmann & Schulte 1992, Manninen et a]. 1992), when variables such as obesity and particularly High Density Lipoprotein Cholesterol (HDL-C) are taken into account in multivariate analysis, the association of high plasma triglycerides with IHD is reduced and is often no longer statistically significant (Criqui et al. 1993). This observation has been interpreted by some workers to imply that low HDL-C levels must be of greater aetiological significance in the pathology of IHD than elevated levels of triglycerides, and this assumption has been the impetus for much research into the mechanism of HDL-mediated reverse cholesterol transport (Reichl et al. 1989). However, there are a number of factors which make unsafe the dismissal of high triglycerides as a contributing factor in its own right to the development of IHD. Within an individual and within the population, levels of triglycerides and HDL-C are negatively correlated as a Steve E. Humphries, Rachel Peacock, Alison Dunning, Anne Lane, Fiona Green and Anders Hamsten

Proton beam irradiation for non-AMD CNV: 2-year results of a randomised clinical trial

Aims To evaluate safety and visual outcomes after proton beam irradiation (PBI) therapy for subfoveal choroidal neovascularisation (CNV) secondary to causes other than age-related macular degeneration (AMD). Methods This study is a prospective, unmasked and randomised clinical trial using two dosage regimens, conducted in the Massachusetts Eye and Ear Infirmary. The study included 46 patients with CNV secondary to non-AMD and best-corrected visual acuity of 20/320 or better. Patients were randomly assigned to receive 16 or 24 cobalt gray equivalents (CGE) of PBI in two equal fractions. Complete ophthalmological examinations, fundus photography and fluorescein angiography were performed at baseline and 6, 12, 18 and 24u2005months after treatment. Results At 1u2005year after treatment, 82% and 72% lost fewer than 1.5 lines of vision in the 16 CGE and in 24 CGE groups, respectively. At 2u2005years after therapy, 77% in the lower dose group and 64% in the higher dose group lost fewer than 1.5 lines of vision. Mild radiation complications such as radiation vasculopathy developed in 17.6% of patients. Conclusions PBI is a safe and efficacious treatment for subfoveal CNV not due to AMD. The data with respect to visual outcomes and radiation complications trend in favour of the 16 CGE group, although differences do not reach statistical significance. PBI may be considered as an alternative to current therapies.