Plasma vitamin K concentrations depend on CYP4F2 polymorphism and influence on anticoagulation in Japanese patients with warfarin therapy.

INTRODUCTION: Warfarin is characterized by a large inter-individual variability in dosage requirement. This study aimed to analyze the contribution of the CYP4F2 genetic polymorphism and plasma vitamin K concentration on the warfarin pharmacodynamics in patients and to clarify the plasma vitamin K concentration affecting warfarin sensitivity index in rats. MATERIALS AND METHODS: Genetic analyses of selected genes were performed and plasma concentrations of warfarin, vitamin K1 (VK1) and menaquinone-4 (MK-4) were measured in 217 Japanese patients. We also assessed the association of plasma VK1 and MK-4 concentrations with the warfarin sensitivity index (INR/Cp) in rats. RESULTS: Patients with the CYP4F2 (rs2108622) TT genotype had significantly higher plasma VK1 and MK-4 concentrations than those with CC and CT genotypes. The multiple linear regression model including VKORC1, CYP4F2, and CYP2C9 genetic variants, age, and weight could explain 42% of the variability in warfarin dosage. The contribution of CYP4F2 polymorphism was estimated to be 2.2%. In contrast, plasma VK1 and MK-4 concentrations were not significantly associated with warfarin dosage in patients. Nevertheless, we were able to demonstrate that the warfarin sensitivity index was attenuated and negatively correlated with plasma VK1 concentration by the oral administration of VK1 in rats, as it resulted in a higher VK1 concentration than that in patients. CONCLUSIONS: The plasma VK1 and MK-4 concentrations are significantly influenced by CYP4F2 genetic polymorphism but not associated with warfarin therapy at the observed concentration in Japanese patients. The CYP4F2 polymorphism is poorly associated with inter-individual variability of warfarin dosage requirement.

Lysocin E is a new antibiotic that targets menaquinone in the bacterial membrane.

To obtain therapeutically effective new antibiotics, we first searched for bacterial culture supernatants with antimicrobial activity in vitro and then performed a secondary screening using the silkworm infection model. Through further purification of the in vivo activity, we obtained a compound with a previously uncharacterized structure and named it 'lysocin E'. Lysocin E interacted with menaquinone in the bacterial membrane to achieve its potent bactericidal activity, a mode of action distinct from that of any other known antibiotic, indicating that lysocin E comprises a new class of antibiotic. This is to our knowledge the first report of a direct interaction between a small chemical compound and menaquinone that leads to bacterial killing. Furthermore, lysocin E decreased the mortality of infected mice. To our knowledge, lysocin E is the first compound identified and purified by quantitative measurement of therapeutic effects in an invertebrate infection model that exhibits robust in vivo effects in mammals.

Deuterium-labeled phylloquinone fed to α-tocopherol-injected rats demonstrates sensitivity of low phylloquinone-containing tissues to menaquinone-4 depletion.

SCOPE: The influence of excess α-tocopherol (α-T) on tissue depletion of phylloquinone (PK) and menaquinone-4 (MK-4) was evaluated. METHODS AND RESULTS: Rats (n = 5 per group) were fed deuterium-labeled PK (2 µmol/kg diet) for 17 days, thereby labeling the conversion from deuterium-labeled PK to d4-MK-4. Then they were injected subcutaneously daily for the last 7 days with saline, vehicle, or α-T (100 mg/kg body weight). α-T injections (i) increased α-T concentrations by tenfold in liver, doubled them in plasma and most tissues, but they were unchanged in brain; (ii) increased the α-T metabolite, carboxyethyl hydroxychromanol (α-CEHC) concentrations: >25-fold in liver and kidney, tenfold in plasma and lung, and 50-fold in heart; brain contained detectable α-CEHC (0.26 ± 0.03 nmol/g) only in α-T-injected animals; and (iii) depleted most tissues' vitamin K. Compared with vehicle-injected rats, brains from α-T rats contained half the total vitamin K (10.3 ± 0.5 versus 21 ± 2 pmol/g, p = 0.0002) and one-third the d4-MK-4 (5.8 ± 0.5 versus 14.6 ± 1.7 pmol/g, p = 0.0002). Tissues with high PK concentrations (liver, 21-30 pmol/g and heart, 28-50 pmol/g) were resistant to K depletion. CONCLUSION: We propose that α-T-dependent vitamin K depletion is likely mediated at an intermediate step in MK-4 production; thus, tissues with high PK are unaffected.

Response to an adequate dietary intake of vitamin D3 modulates the effect of estrogen therapy on bone density.

INTRODUCTION: This study analyzed associations between plasma vitamin D(3) (25OHD(3)) and bone mineral density (BMD) and whether the effects of conjugated equine estrogens (CEE) on BMD are modulated by 25OHD(3). METHODS: Fifty cynomolgus monkeys were fed a diet containing 25OHD(3) (providing a woman's equivalent of 1000 IU/day of 25OHD3). The monkeys underwent bilateral oophorectomy and were randomized to either CEE (equivalent of 0.45 mg/day) (n=25) or placebo (n=25) and continued receiving the same diet. 25OHD(3) and BMD were measured at randomization and after 6 months. BMD also was measured after 20 months (equivalent to 6 human years). Associations between 25OHD(3) and BMD were subsequently analyzed. RESULTS: Baseline 25OHD(3) plasma concentrations varied from 26 to 95 ng/mL (mean±standard deviation [SD] 54 ± 15 ng/mL). Higher plasma concentrations of 25OHD(3) were associated with a significantly increased BMD. Monkeys on both CEE and placebo had increased BMD over 20 months; however, the increase was not significantly different (0.034 g/cm(2) vs. 0.020 g/cm(2), respectively; p=0.064). The 20-month BMD increased significantly with CEE treatment in those with higher vs. lower 25OHD(3) concentrations (p=0.027). The percent change in BMD over 20 months also increased significantly with CEE treatment in those with higher vs. lower 25OHD(3) concentrations (p=0.018). A higher 25OHD(3) concentration had no significant effect on BMD in those receiving placebo. CONCLUSIONS: Monkeys fed a diet containing 1000 IU/day equivalent of 25OHD(3) have a wide range of plasma 25OHD(3) concentrations. Those receiving CEE with higher 25OHD(3) concentrations had higher BMDs, suggesting 25OHD(3) and CEE have synergistic effects on BMD.