Liposomal 1,25 (OH)2 vitamin D3 compounds block proliferation and induce differentiation in myelomonocytic leukaemia cells

The vitamin D₃ derived hormone 1,25 (OH)₂ vitamin D₃ (1,25 D₃) is able to induce growth arrest and differentiation in myelomonocytic leukaemia cells. In order to allow for specific delivery to leukaemic cells the lipophilic compound was incorporated into the lipid membranes of liposomes. Liposomal 1,25 D₃ reduced proliferation as measured by ³H-thymidine incorporation in HL60 leukaemia cells by up to 60%. When liposomes were prepared at different concentrations of 1,25 D₃ 65% inhibition was achieved at 48 n M . The MC 1288 stereoisomer of 1,25 D₃ was more potent and had the same activity at 48 n M .
The effect of the liposomal compounds was specific to myeloid cells as they reduced proliferation in myelomonocytic HL60, monoblastic U937 and monocytic Mono Mac 6 cells but not in the T-cell lines Jurkat and Molt 4.
The antiproliferative effect of liposomal 1,25 D₃ was associated with an induction of differentiation since treated HL60 cells showed a monocytic morphology, increased expression of CD14 and decreased expression of CD33.
When peripheral blood leukaemic cells from M4 and M5 acute myeloid leukaemia (AML) patients were admixed with liposomal compounds an antiproliferative effect was seen in all five cases, including the two cases where free compounds led to enhanced growth. Liposomal delivery of 1,25 (OH)₂ vitamin D₃ may offer a novel approach to treatment of myelomonocytic leukaemia.     

Chronic venous abnormalities in symptomatic and asymptomatic protein C deficiency

BACKGROUND: Thrombophilia is a frequent medical condition associated with symptomatic deep vein thrombosis (DVT). Unlike other clinical risk factors associated with DVT, such as surgery, thrombophilia has not been demonstrated to be associated with asymptomatic venous thrombotic events. Our aim was to search for asymptomatic sequelae of DVT in a protein C (PC)-deficient family. METHODS: We studied 228 individuals from a large kindred with PC deficiency and performed a systematic ultrasound examination. RESULTS: Among the 203 patients without a known history of venous thrombosis we found seven patients with abnormalities indicative of prior asymptomatic thrombosis: six (7.4%) in the PC-deficient group (n = 81) and only one (0.8%) in the non-deficient group (n = 122). The relative risk for these sequelae associated with PC deficiency was 9.0 (95% CI: 1.1-73.7). CONCLUSIONS: These data suggest that chronic venous abnormalities are frequently present and that thrombotic events in asymptomatic individuals with familial PC deficiency may be underestimated.     

Indicators of lifetime endogenous estrogen exposure and risk of venous thromboembolism

BACKGROUND: Lifetime estrogen exposure has been related to breast cancer risk, osteoporosis, and cardiovascular disease but data on venous thromboembolism (VTE) risk are limited. METHODS: Data from a hospital-based case-control study among 608 postmenopausal women (191 with a first episode of idiopathic VTE and 417 age-matched controls) were used to determine whether estrogen exposure, as assessed by age at menopause [classified as early (< or = 45 years), normal (46-54 years) and late menopause (> or = 55 years)] and parity, was associated with the risk of VTE. RESULTS: After adjustment for potential confounding variables, the risk of VTE was increased with each year's delay in the menopause [odds ratio (OR) = 1.06, 95% confidence interval (CI) = 1.02-1.10, P < 0.0075]. When compared with women with normal menopause used as a reference, the adjusted OR for VTE was 0.59 (95% CI = 0.36-0.97) and 2.53 (95% CI = 1.28-4.99) for women with early menopause and late menopause, respectively (P = 0.001). Adjusted OR for VTE was also higher for women with more than two children when compared with those with less than or equal to two children (1.56, 95% CI = 1.03-2.34, P = 0.03). The lowest risk of VTE was observed in women with early menopause and lower parity (adjusted OR = 0.60, 95% CI = 0.30-1.24), the highest risk was among women with late menopause who have had more than two children (adjusted OR = 3.41, 95% CI = 1.46-9.25). CONCLUSION: These results show that the longer exposure to endogenous estrogen is associated with an increased VTE risk.     

Therapeutic effect of fucoidan‐stimulated endothelial colony‐forming cells in peripheral ischemia

Summary. Background: Fucoidan, an antithrombotic polysaccharide, can induce endothelial colony‐forming cells (ECFC) to adopt an angiogenic phenotype in vitro. Objectives: We evaluated the effect of fucoidan on vasculogenesis induced by ECFC in vivo. Methods: We used a murine hindlimb ischemia model to probe the synergic role of fucoidan‐treatment and ECFC infusion during tissue repair. Results: We found that exposure of ECFC to fucoidan prior to their intravenous injection improved residual muscle blood flow and increased collateral vessel formation. Necrosis of ischemic tissue was significantly reduced on day 14, to 12.1% of the gastronecmius cross‐sectional surface area compared with 40.1% in animals injected with untreated‐ECFC. ECFC stimulation with fucoidan caused a rapid increase in cell adhesion to activated endothelium in flow conditions, and enhanced transendothelial extravasation. Fucoidan‐stimulated ECFC were resistant to shear stresses of up to 21 dyn cm^?2. Direct binding assays showed strong interaction of fucoidan with displaceable binding sites on the ECFC membrane. Bolus intramuscular administration of fucoidan 1 day after surgery reduces rhabdomyolysis. Mice injected with fucoidan (15 mg kg^?1) had significantly lower mean serum creatine phosphokinase (CPK) activity than control animals. This CPK reduction was correlated with muscle preservation against necrosis (P < 0.001). Conclusions: Fucoidan greatly increases ECFC‐mediated angiogenesis in vivo. Its angiogenic effect would be due in part to its transportation to the ischemic site and its release after displacement by proteoglycans present in the extracellular matrix. The use of ECFC and fucoidan together, will be an efficient angiogenesis strategy to provide therapeutic neovascularization.     

Maize‐ or potato‐derived hydroxyethyl starches: is there any thromboelastometric difference?

Background: Hydroxyethyl starches (HES) could differ with regard to the origin, and the influence on the coagulation of the raw material is unknown. This study compared the effects of a new potato‐derived HES with a maize‐derived HES and two crystalloid solutions. Methods: Whole blood from 10 healthy individuals was diluted by 20% and 40% using either non‐balanced potato‐derived HES 130/0.42/6 : 1, non‐balanced maize‐derived HES 130/0.4/9 : 1, isotonic saline or Ringer's lactate solution. Samples were analysed by thromboelastometry ROTEM^®: Coagulation was initiated by acid ellagic [intrinsic thromboelastometry (INTEM)] or tissue factor (extrinsic thromboelastometry) with and without cytochalasin to determine the functional component of fibrinogen [cytochalasin‐d ‐modified thromboelastometry (FIBTEM)]. Platelet count and fibrinogen activity were measured. Results: No effect of raw material was found as no difference was detected among the HES solutions. Whatever the solution, progressive haemodilution impaired haemostasis in a dose‐dependant manner: For INTEM, the clot formation time was increased up to 308% and the maximum clot firmness (MCF) was decreased down to 49%. As dilution increased, initiation of coagulation was also impaired. Thromboelastometric alterations were more severe with HES than with crystalloids, especially regarding fibrin polymerization explorations: MCF of FIBTEM was considerably reduced from 12[10–14] to 2[2–3] mm (P<0.05). Fibrinogen activity and platelet count were reduced by dilution in a dose‐dependant manner and decreased similarly in all groups. Conclusion: Maize‐ and potato‐derived HES have similar effects on coagulation. Both the starch preparations tested lead to more severe haemostatic defects than crystalloids, and impairment of fibrin polymerization appears to be a leading determinant of this coagulopathy.     

The minor allele of GP6 T13254C is associated with decreased platelet activation and a reduced risk of recurrent cardiovascular events and mortality: results from the SMILE–Platelets project

Summary. Background: Contradictory results have been published on the effects of T13254C (rs1613662), which distinguishes the two major isoforms of GP6, the gene encoding the platelet receptor glycoprotein VI, on platelet function and the risk of cardiovascular disease. Methods: We performed a population‐based case–control study, the Study of Myocardial Infarctions in Leiden, among 547 male patients with a first myocardial infarction (MI) and 646 control subjects, as well as a prospective cohort study in which the same MI patients were followed for recurrent events (fatal and non‐fatal MI and unstable angina) and mortality (median follow‐up of 12 years). P‐selectin expression by platelets induced by crosslinked collagen‐related peptide (CRP‐XL) was measured by whole blood flow cytometry in 274 MI patients. Results: T13254C was not associated with a first MI, but seemed to be associated with a reduced incidence of recurrent events [per‐allele hazard ratio 0.77, 95% confidence interval (CI) 0.56–1.06] and mortality (hazard ratio 0.57, 95% CI 0.37–0.89). Pooling with the Heart and Estrogen/Progestin Replacement Study revealed hazard ratios of 0.81 (95% CI 0.66–0.99) and 0.73 (95% CI 0.55–0.96). The minor C‐allele was also strongly associated with a reduced percentage of P‐selectin‐expressing platelets. The reduction per C‐allele was 23% (95% CI 18–28%). In an independent study of 219 healthy volunteers, the per‐allele reduction of CRP‐XL‐induced aggregation was 10% (95% CI 2–18%). Conclusion: The minor allele of GP6 T13254C that reduced platelet activation and aggregation also seemed to be associated with a reduced incidence of recurrent cardiovascular events and mortality, but was not associated with first MI.     

Diagnosis of coronary aneurysms in siblings: Treatment with a new surgical procedure

We report the cases of two brothers who simultaneously developedmyocardial infarction, and in whom we found coronary arteryaneurysms at echocardiography. In one case a new surgical procedurewas performed. The aneurysm was bypassed by an aorto-coronaryvein graft and the coronary ostium of the related coronary arterywas closed. Thus, perfusion of the dependent vessels of theaneurysm was maintained, and the risk of distal embolism wasprevented. The aetiologies of coronary artery aneurysms arediscussed. In our patients the aneurysms were probably congenital,but we cannot exclude the possibility of previously undiagnosedKawasaki's disease.