Impact of different storage times at room temperature of unspun citrated blood samples on routine coagulation tests results. Results of a bicenter study and review of the literature.

INTRODUCTION: A maximum delay between blood collection and coagulation testing of 4 hours is recommended by most guidelines. As information on optimal storage times is limited, we investigated the potential effect of different storage times of unspun tubes, that is, ≤2, 4, 6, and 8 hours, on routine coagulation test results. METHODS: Four evacuated polymer tubes containing 0.109 mol/L tri-Na citrate were drawn from 144 patients, including 39 patients on vitamin K-antagonists. Except for storage time, all tubes underwent the same preanalytical process. Prothrombin time (PT)/international normalized ratio (INR), activated partial thromboplastin time (aPTT), fibrinogen, factor V (FV), FVIII, and D-dimer were evaluated in two centers using the same technical conditions. RESULTS: Analytical comparison of aPTT, fibrinogen, FV, and FVIII results evaluated after prolonged storage times vs a <2-hours storage demonstrated significant difference, whereas PT/INR and D-dimer remained unchanged up to 8 hours. Mean bias between test results obtained after prolonged storage times remained below the desirable values for all studied parameters except for FVIII evaluated after 6- and 8-hours storages, but only in patients with FVIII above 100 IU/dL. Even though the corresponding bias of -5.2% and -8.5%, respectively, remained within the GEHT recommended limits of variation, its evaluation after an 8-hours storage could lead to significant underestimation of FVIII. CONCLUSION: These results suggest that, in the studied technical conditions, PT/INR, aPTT, fibrinogen, FV, and D-dimer can be reliably evaluated in tubes stored unspun at room temperature for up to 8 hours after blood collection. That optimal delay should be of 6 hours for FVIII.

Pharmacokinetic profile and in vitro selective cyclooxygenase-2 inhibition by nimesulide in the dog.

The pharmacokinetic properties and in vitro potency of nimesulide, a nonsteroidal anti-inflammatory drug (NSAID) were investigated in 8 or 10 dogs after intravenous (i.v.), intramuscular (i.m.) and oral (single and multiple dose) administrations at the nominal dose of 5 mg/kg. After i.v. administration, the plasma clearance was 15.3 +/- 4.2 mL/kg/h, the steady-state volume of distribution was low (0.18 +/- 0.011 L/kg) and the elimination half-life was 8.5 +/- 2.1 h. After i.m. administration, the terminal half-life was 14.0 +/- 5.3 h indicating a slow process of absorption with a maximum plasma concentration (6.1 +/- 1.5 microg/mL) at 10.9 +/- 2.1 h postadministration and the systemic bioavailability was 69 +/- 22%. After oral administration in fasted dogs, the maximal plasma concentration (10.1 +/- 2.7 microg/mL) was observed 6.1 +/- 1.6 h after drug administration, the plasma half-life was 6.2 +/- 1.9 h and the mean bioavailability was 47 +/- 12%. After daily oral administrations for 5 days, the average plasma concentration during the fifth dosage interval was 8.1 +/- 2.9 microg/mL and the overall bioavailability was 58 +/- 16%. The mean accumulation ratio was 1.27 +/- 0.4. In vitro nimesulide inhibitory potencies for cyclooxygenase (COX)-1 and COX-2 isoenzymes were determined using a whole blood assay. Canine clotting blood was used to test for inhibition of COX-1 activity and whole blood stimulated by lipopolysaccharide (LPS) was used to test for inhibition of COX-2 activity. The inhibitory concentration (IC50) for inhibition of COX-2 and COX-1 were 1.6 +/- 0.4 microM (0.49 +/- 0.12 microg/mL) and 20.3 +/- 2.8 microM (6.3 +/- 0.86 microg/mL) giving a nimesulide COX-1/COX-2 ratio of 12.99 +/- 3.41. It was concluded that at the currently recommended dosage regimen (5 mg/kg), the plasma concentration totally inhibits COX-2 and partly inhibits COX-1 isoenzyme.

A case of Enterocytozoon bieneusi infection in an HIV-negative renal transplant recipient.

Reported here is a case of microsporidiosis that occurred in an HIV-negative renal transplant recipient. The patient developed protracted diarrhea 18 months following transplant surgery. Many spores of Enterocytozoon bieneusi were detected in stool smears using a modified trichrome staining method. Identification was confirmed using the polymerase chain reaction. Histological examination of duodenal biopsies revealed numerous spores in the cytoplasm of enterocytes. Tacrolimus and steroid regimens were decreased, treatment with mycophenolate mofetil was discontinued, and the patient was given albendazole and metronidazole for 2 weeks. The diarrhea resolved after 15 days of treatment; 2 months later the patient had recovered completely. A more systematic search for microsporidia using specific staining procedures should be performed in transplant recipients who develop severe diarrhea.