Aim A recent Australian warfarin reversal guideline recommended dosing 3F-PCC according to patients' pre-INR. Our study examines factors impacting on warfarin reversal, including pre-INR, 3F-PCC dose and use of vitamin-K and FFP. Methods A retrospective analysis was conducted on 88 patients receiving 3F-PCC between June to October 2014. Successful warfarin reversal is defined as post-treatment INR < 1.5. Chi-square and Mann-Whitney tests were used to compare differences between groups. Results 87 of 88 patients received 3F-PCC for warfarin reversal; 53% for bleeding and 42% prior to urgent surgery. Median time to post-INR was 3 hours. Seventy-six percent of patients achieved post-INR < 1.5 with median pre-INR of 2.5 (1.5–20) and median 3F-PCC dose of 34 (7–65) IU/kg; 23% of these patients also received FFP. In the patients who had post-INR ≥ 1.5 (24%), no statistically significant differences were observed in median pre-INR [2.9 (1.9–17.3), p = 0.1], 3F-PCC dose [25 (13–67) IU/kg, p = 0.07] and proportion of patient who received FFP (31%, p = 0.47) compared to those with INR < 1.5. Most patients received vitamin K in both groups. Conclusion In 3F-PCC use for warfarin reversal, pre-INR, 3F-PCC dose and FFP do not appear to significantly impact post-INR correction. Larger studies are required to explore the feasibility of a fixed 3F-PCC dose to simplify the current guideline. A recent Australian warfarin reversal guideline recommended dosing 3F-PCC according to patients' pre-INR. Our study examines factors impacting on warfarin reversal, including pre-INR, 3F-PCC dose and use of vitamin-K and FFP. A retrospective analysis was conducted on 88 patients receiving 3F-PCC between June to October 2014. Successful warfarin reversal is defined as post-treatment INR < 1.5. Chi-square and Mann-Whitney tests were used to compare differences between groups. 87 of 88 patients received 3F-PCC for warfarin reversal; 53% for bleeding and 42% prior to urgent surgery. Median time to post-INR was 3 hours. Seventy-six percent of patients achieved post-INR < 1.5 with median pre-INR of 2.5 (1.5–20) and median 3F-PCC dose of 34 (7–65) IU/kg; 23% of these patients also received FFP. In the patients who had post-INR ≥ 1.5 (24%), no statistically significant differences were observed in median pre-INR [2.9 (1.9–17.3), p = 0.1], 3F-PCC dose [25 (13–67) IU/kg, p = 0.07] and proportion of patient who received FFP (31%, p = 0.47) compared to those with INR < 1.5. Most patients received vitamin K in both groups. In 3F-PCC use for warfarin reversal, pre-INR, 3F-PCC dose and FFP do not appear to significantly impact post-INR correction. Larger studies are required to explore the feasibility of a fixed 3F-PCC dose to simplify the current guideline.

The venom of R. oxyrhynchus, a member of the psammophiine subfamily of the colubrid assemblage, was examined for biological activity using biochemical and pharmacological techniques. Venom displayed a high protein content, a complex electrophorectic profile and PLA2 activity but no detectable proteolytic or haematological activities. In the chick biventer cervicis nerve muscle preparation, venom (1-10 microg/ml) displayed postsynaptic neurotoxic activity as evidenced by inhibition of indirect (0.1 Hz, 0.2 ms, supramaximal V) twitches and responses to exogenous acetylcholine (1 mM) and carbachol (20 microM). This inhibitory effect was poorly reversible by washing. Venom (30-50 microg/ml) caused a rapid and readily reversible inhibition of direct (0.1 Hz, 2 ms, supramaximal V) twitches of the chick biventer cervicis nerve muscle preparation without morphological changes to the muscle fibers. Venom (30-100 microg/ml) inhibited electrically-evoked (0.2 Hz, 0.3 ms, 70-100 V) twitches of the prostatic segment of the rat vas deferens. This inhibitory effect was not significantly attenuated by 8-phenyltheophylline (8-PT; 20 microM), idazoxan (1 microM), a combination of ranitidine (0.2 microM) and thioperamide (10 microM) or capsazepine (10 microM). Venom (5 mg/kg) induced hypotension with subsequent cardiovascular collapse in the anaesthetised rat. The cardiovascular collapse was prevented by artificial respiration of the animals prior to venom administration. The biological activities demonstrated by R. oxyrhynchus venom may aid in prey envenomation strategies such as prey immobilisation. This study provides further evidence that colubrid venoms are comprised of multiple components which can display a variety of actions, some of which may be novel, therefore reinforcing the largely untapped potential of colubrid venoms.

SUMMARY1. The effects of the ETA receptor antagonist BQ123 and dihydropyridine calcium antagonists on the vasoconstrictor effect of endothlin‐1 (ET‐1) were studied in human isolated internal mammary artery (IMA). The effect of the calcium antagonist, nisoldipine, on ET‐1 levels has also been examined in cultured IMA endothelial cells (IMAEC).2. The results showed that BQ123 and the calcium antagonists nisoldipine, isradipine, nitrendipine and nifedipine fully relaxed IMA precontracted with 3 nmol/L ET‐1 with the EC50 values of 7.18 ± 0.09 (‐log mol/L) for BQ123, and 7.68 ± 0.07, 7.02 ± 0.12, 6.96 ± 0.08 and 6.89 ± 0.09 for the calcium antagonists, respectively.3. Pretreatment of IMA with 10, 30, 100 and 300 nmol/L nisoldipine significantly depressed the maximal response (Max; 88.3 ± 5.1, 75.2 ± 4.9, 59.3 ± 5.6 and 56.2 ± 4.8% of maximal noradrenaline response versus 99.1 ± 13.2% in control, P<0.01) of IMA to ET‐1 without a significant change in the EC50 values.4. Pretreatment of IMA with 300 nmol/L BQ123 significantly increased both the EC50 (7.97 ± 0.09 vs 8.36 ± 0.08 in the control, P<0.05) and the Max (138.1 ± 10.2%vs the control, P< 0.01) of IMA to ET‐1.5. Incubation of IMAEC with nisoldipine for 7h resulted in a dose‐dependent (10−8–10−5 mol/L) reduction up to 93.1% in ET levels in the conditioned media.6. ET levels in the cell lysates were not detectable either in the absence or in the presence of nisoldipine, suggesting the reduction of ET levels in the media could be due to inhibition of ET synthesis.7. In conclusion, these studies demonstrate that: (i) both BQ123 and the calcium antagonists are potent relaxant agents of human IMA precontracted with ET‐1; (ii) BQ123 also increases the Max of IMA to ET‐1 and the mechanism is unknown; (iii) the calcium antagonist nisoldipine reduces ET levels in the cultured human IMAEC.

Objective: Endothelin is thought to be related to cardiovascular disease. The purpose of this study was to determine whether endothelin levels could be reduced by a calcium antagonist and a 'natural factor'.Design: Since calcium ionophores can induce endothelin-1 messenger RNA synthesis in cultured endothelial cells, the calcium antagonist nisoldipine was used in this study to determine whether it could reduce endothelin levels. It has been reported that coculture of endothelial cells and smooth muscle cells from different species and different parts of the body can reduce endothelin levels. This study was also designed to determine whether coculture of the two cell types from the same species and the same section of an artery could reduce endothelin levels.Methods: Cultured endothelial cells from human umbilical artery (HUAEC) and umbilical vein (HUVEC) were treated with increasing concentrations of nisoldipine. HUAEC were cocultured with human umbilical artery smooth muscle cells (HUASMC). Endothelin levels were measured by a radioimmunoassay.Results: Incubation of the HUAEC with nisoldipine for either 7 or 24 h resulted in a dose-dependent (10(-8)-10(-5) mol/l) reduction in endothelin levels in the conditioned media. Endothelin levels in cell lysates were not detectable in either the absence or the presence of nisoldipine. This suggests that the reduction of endothelin levels in the media could be due to inhibition of endothelin synthesis. Under the same conditions, incubation of HUVEC with the same concentrations of nisoldipine produced a similar concentration-dependent reduction in endothelin levels. Endothelin levels were undetectable in the conditioned media from HUASMC. Coculture of HUAEC with HUASMC significantly reduced endothelin levels (P < 0.01) compared with HUAEC cultured alone.Conclusions: Endothelin levels can be reduced by the calcium antagonist nisoldipine and a 'natural factor' associated with smooth muscle cells.