Incomplete reversal of enoxaparin-induced bleeding by protamine sulfate.

The neutralizing effect of protamine sulfate on enoxaparin-induced bleeding was compared in two rat models: one employing the gastric mucosa, and the other the tail skin, using a 2:1 ratio of protamine sulfate to enoxaparin on a weight basis. Whereas protamine sulfate reduced the median bleeding time (from 20 to 9.5 min) and blood loss (80%) in the gastric mucosa, and apparent 'all-or-none' response was seen in the tail skin, in agreement with a different hemostatic mechanism in the two bleeding models. In both models, protamine sulfate incompletely reversed the bleeding induced by enoxaparin.     

Molecular modelling of drug targets: the past, the present and the future

Most currently used therapeutic drugs have an enzyme or a membrane-bound receptor as site of action. The sequencing of the human and other genomes has provided a potential to identify many hitherto unknown proteins that might serve as new drug targets. To achieve this, knowledge about three-dimensional protein structures is crucial for the understanding of their functional mechanisms, and for a rational drug design. Over the last decade atomic resolution crystal structures of soluble proteins have been reported in a rapidly increasing number, but the detailed three-dimensional structures are still unknown for the majority of membrane proteins since their membrane association makes experimental structure determinations complicated. Computerized modelling of protein structures, based on experimentally determined structures of homologue proteins, may be a useful methodological alternative, especially for membrane proteins. In the past, molecular modelling of transporters and G-protein-coupled receptors was based on low-resolution structural data obtained by cryo-electron microscopy. Recent high-resolution crystal structure determinations of a G-protein-coupled receptor, rhodopsin, and several different transporter proteins and ion channels have enabled construction of more accurate receptor and transporter models. For the future, collaborative structural genomics initiatives aim at determining the three-dimensional structure of all known proteins, based on a combination of experimental structure determination and molecular modelling. Development of still more powerful computer hardware and software will enable extensive studies of the protein structure and dynamics of new potential drug targets, but raises a new challenge in the validation and calibration of computerized methods of biosimulations.     

Gastric mucosal bleeding after unfractionated and low molecular weight heparin in rats

The bleeding from an induced gastric mucosal lesion was monitored after intravenous administration of unfractionated heparin and enoxaparin, a low molecular weight heparin. The gastric mucosa was exposed in a chamber, which was superfused with saline and emptied at 1-min intervals for quantitation of bleeding. Both heparins prolonged the bleeding time and increased the blood loss dose-dependently. Five to ten times higher doses of enoxaparin (in terms of anti-Xa units) were required to achieve similar prolongation of the bleeding times as with unfractionated heparin. The results indicate a more favourable antihaemostatic effect of enoxaparin than of unfractionated heparin.     

Bolus therapy with mitoxantrone and vincristine in combination with high-dose prednisone (NOP-bolus) in resistant multiple myeloma. Nordic Myeloma Study Group (NMSG).

In a phase II study, 58 patients with resistant multiple myeloma (MM) were treated with a combination chemotherapy (NOP-bolus regimen) consisting of mitoxantrone (16 mg/m2 for the first 25 patients and 12 mg/m2 for the subsequent 33), vincristine (2 mg), both as bolus injections on day 1 and prednisone (250 mg/d on d 1-4 and 17-20). In patients greater than 70 years of age, the mitoxantrone dose was reduced to 12 mg/m2 or 8 mg/m2, respectively. The treatment was repeated every 4 weeks. A response (greater than 50% reduction in M component) was obtained in 26% of the patients and a minor response (clinical improvement but less than 50% reduction in M component) in another 21%. Median response duration was 27 wk and median survival for all patients was 25 wk. There were no differences in response rate or duration between patients receiving the high or low mitoxantrone dose, but patients in the low-dose group had fewer serious infections.     

Haemorrhagic effect of enoxaparin, a low molecular weight heparin. Comparison with unfractionated heparin in humans.

The haemorrhagic effects of unfractionated heparin (UFH) and the low molecular weight heparin (LMWH) enoxaparin were investigated and compared in the gastric mucosa (haemorrhage induced by biopsy) and skin (haemorrhage induced by Simplate) of 12 healthy volunteers. Administration of UFH and LMWH (given in a dose of 75 anti-Xa U/kg intravenously) increased median gastric bleeding time (3.5 min) and geometric mean blood loss (11.5 microliters) to 19 min (p = 0.00003) and 54.1 microliters (p = 0.0021) after UFH and to 13 min (p = 0.008) and 29.0 microliters (p = 0.275) after LMWH. Median skin bleeding time (4.25 min) increased to 6.0 min after UFH (p = 0.003) and to 6.75 min after LMWH (p = 0.0008). Mean heparin activity in plasma was 20% higher after LMWH than after UFH. The calculated gastric bleeding time to heparin activity ratio was significantly lower for LMWH than for UFH (p < 0.05).     

Simple Separation Technique of Peripheral Blood Cells: A New Method of Centrifugal Subfractionation

Addition and flotation methods for preparation of platelet- and leucocyte-rich plasma (PLRP) were compared: Addition methods were found preferable to flotation methods due to higher yield of leucocytes (p < 0.01) and simpler technique. Inappropriate preparation of PLRP might occur in addition methods, due to partial coagulation, and in flotation methods, due to marked mixing. A new centrifuge tube is described which simplified the separation of polymorphonuclear leucocytes, lymphocytes, erythrocytes, and platelets.     

Multiple myeloma treated with mitoxantrone in combination with vincristine and prednisolone (NOP regimen) versus melphalan and prednisolone: a phase III study

Abstract: One-hundred-and-fifty-one patients with previously untreated multiple myeloma were allocated to treatment with either NOP regimen (mitoxantrone 16 mg/m² and vincristine 2 mg day 1 and prednisolone 250 mg day 1–4 and 17–20) or M + P regimen (melphalan 0.25 mg/kg and prednisolone 100–200 mg/day day 1–4). Both regimens were repeated every 4 weeks and were scheduled for 1 year. Seventy-seven patients were treated with NOP and 74 patients with M + P. No major clinical differences were recorded between the groups before treatment. Sixty percent of the patients responded (CR + PR) to NOP versus 64% to M + P (NS). The time to progression was 16 months (95% C.L. 14–51) in the NOP group versus 21 months (95% C.L. 15–27) in the M + P group (NS). The median survival was 14 months (7–21) in the NOP group and 31 months (21–43) in the M + P group (p = 0.02). NOP was significantly more toxic than M + P. Seven patients treated with NOP died due to infection and neutropenia and 1 patient died of cardiac toxicity, in contrast to 1 death due to infection and neutropenia in the M + P group. Gastrointestinal toxicity was acceptable in both groups. In conclusion, NOP was inferior to M + P as primary treatment of multiple myeloma.     

Problems in Microscopic and Automatic Cell Differentiation of Blood and Cell Suspensions

Problems in microscopic and electronic differential cell-counting of blood and cell suspensions were studied. Smears made from peripheral blood by the spreading technique or by the spin-slide technique did not show skewed cell distribution. The automatic differential cell counter Hemalog D was better than microscopy for basophils and showed satisfactory results compared with microscopy for polymorphonuclear neutrophil granulocytes, lymphocytes and eosinophils, while there was some disagreement for monocytes. Hemalog D, which includes blasts in large unstained cells (LUC), showed LUC in 95 % of our patients, while blasts were found only in 4% by microscopy. The commonly used methods for preparing smears from cell suspensions showed markedly skewed cell distribution, which was avoided by an improved technique for cytocentrifugation, by a spin-slide technique and by a spreading technique resembling that used for blood.