Diabetes is a risk factor for the development of atherothrombosis and venous thromboembolism (VTE). We investigated whether plasma from patients with type 2 diabetes has an imbalance of pro- versus anti-coagulation resulting in hypercoagulability despite normal conventional coagulation tests. We analyzed blood samples from 60 patients with type 2 diabetes and 60 gender- and age-matched healthy subjects (controls) for the levels of pro- and anti-coagulant factors, for thrombin generation and for the numbers of cell-derived circulating microparticles bearing such pro-coagulant triggers as tissue factor and negatively charged phospholipids. The levels of pro- or anti-coagulants as measured with conventional coagulation tests or single factor measurements were similar to those of the control population. In contrast, the median (range) of the height of the thrombin peak (taken as an index of thrombin generation) was higher in patients [205 nM (126-352)] than controls [151 nM (41-289)], P < 0.001. The median numbers of circulating microparticles were higher for patients [5,041/μl (1,821-13,132)] than for controls [1,753/μl (554-13,308)], P < 0.001 and their values were correlated with the height of the thrombin peak (ρ = 0.66, P < 0.001). In conclusion, plasma from patients with type 2 diabetes possesses an imbalance of pro- versus anti-coagulation resulting in hypercoagulability that can be detected by thrombin generation tests, but not by the measurement of the single pro- or anti-coagulant factors. This hypercoagulability is associated with increased numbers of circulating microparticles bearing endogenous pro-coagulant triggers. These findings might explain the relatively high risk of atherothrombosis and VTE described in these patients.
Total and segmental body composition (fat mass, FM; fat-free mass, FFM; bone mineral density, BMD) were evaluated in 13 sedentary spinal cord injury (SCI) subjects and in 13 able-bodied healthy males (control, C) using dual X-ray absorptiometry (DXA) and skinfold methods. In the SCI group, total FM was significantly higher (31.1+/-8.2 vs. 20.8+/-6.9%) and total FFM was significantly lower (62.2+/-8.9 vs. 73.5+/-6.4%) than in C subjects. Total BMD did not differ between the SCI and C groups (1.20+/-0.11 vs. 1.30+/-0.11 g/cm(2)). In the SCI group, segmental FM was higher in the legs and trunk, whereas BMD was lower in legs only. The skinfold method significantly underestimated FM in the SCI group. Body composition is severely modified in paralyzed segments. The predictive equations developed for healthy populations appear to be inapplicable to SCI subjects.
Ferredoxin has been effectively cross-linked to photosystem I complex by treatment of purified particles or thylakoids with N-ethyl-3-(3-dimethylaminopropyl)carbodiimide, a zero-length cross-linker which stabilizes protein-protein electrostatic interactions. Analysis of photosystem I polypeptide composition after such a treatment showed a specific decrease of the 20-kDa subunit and the appearance of a new component of about 42 kDa which was recognized by the anti-ferredoxin antibody. Cross-linking of ferredoxin to thylakoids allowed the membrane preparation to photoreduce cytochrome c without requiring exogenous ferredoxin, whereas photosystem I particles purified from treated thylakoids were inactivated in the NADP' photoreduction activity. From these results, it can be inferred that the polypeptide of 20 kDa is the photosystem I subunit which interacts with ferredoxin during the photosynthetic electron transport.Electron transfer between photosystem I and NADP' in the photosynthetic chain, is mediated by ferredoxin and ferredoxin -NADPt reductase. Much is known on the interactions between the latter proteins [l -31, considerably less on the interactions between ferredoxin and PS I. Photosystem I is a membrane-spanning protein complex containing several polypeptides as well as six redox centers (P700, Ao, Al, X, A, B) (for recent reviews, see [4, 51). It has been suggested by Malkin [4, 61 that the electron donor of PS I to ferredoxin is the [4Fe-4S] iron-sulfur center A which seems closely associated with the [4Fe-4S] center B, possibly on the same polypeptide [7]. Association of such centers with specific PS
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