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Biomedical subjects

G Potron

Publications and source records attributed to G Potron.

105 records · Page 6Linked to original sources
PubMedDate not supplied

Intranuclear concentration measurements of doxorubicin in living leucocytes from patients treated for a lympho-proliferative disorder.

The accumulation of doxorubicin (DOX) in white blood cells of treated patients has been studied by quantitative microspectrofluorometry. From blood samples of treated patients, leucocyte subpopulations were separated by the gradient method. Emission fluorescence spectra from a microvolume of a single living cell nucleus were analysed in terms of spectral shape and fluorescence yield between free and DNA-bound doxorubicin. With this non-destructive analysis technique, intranuclear doxorubicin concentrations were determined within +/- 10%. Doxorubicin concentrations were measured in patients treated with bolus injection. After an accumulation of DOX in leucocytes during the first 30 min, intranuclear doxorubicin concentration did not vary significantly for 24 h, whereas its concentration in plasma decreased. Despite large differences between patients, monocytes accumulated significantly more doxorubicin than granulocytes or lymphocytes did.

Aged↗
PubMedDate not supplied

Human platelets frozen with glycerol in liquid nitrogen: biological and clinical aspects.

Platelets were frozen using glycerol (3% in plasma) as a cryoprotective agent, a rapid cooling rate, and liquid nitrogen for storage. The cryopreserved platelets were thawed at 42 C and infused without washing. The results indicate that the quality of the thawed platelets is equivalent to platelets stored for 24 to 48 hours at room temperature. The availability of HLA phenotyped leukocyte poor platelets can reduce the frequency of sensitization to strong antigens and provide clinically effective platelets for alloimmunized patients.

Blood Platelets↗
PubMedDate not supplied

Comparative inhibition of LPS-activated human monocyte-induced thrombin generation by unfractionated heparin and low molecular weight heparins.

Monocyte tissue factor may play a role in the physiological or pathological triggering of blood coagulation. It is well known that unfractionated heparin and low molecular weight heparins inhibit extrinsic thrombin generation. However, this notion has never been confirmed in a physiological model using tissue factor obtained from stimulated human monocytes. This is the purpose of this study. It was important to obtain a pure preparation of monocytes with no platelet contamination. This was possible by leukapheresis and elutriation. Under sterile and endotoxin-free conditions, the process does not activate tissue factor expression by monocytes. We adapted the technique of thrombin generation on an automatic analyzer and used human monocyte tissue factor to trigger thrombin generation. Our results show that unfractionated and low molecular weight heparins potently inhibit monocytic tissue factor induced thrombin generation. The comparison of low molecular weight heparins suggests that molecules with higher anti-IIa/anti-Xa ratios exert a stronger inhibitory effect. These data may be relevant to explain the therapeutic effects of unfractionated and low molecular weight heparins in cardiovascular disorders such as unstable angina.

Cell Culture Techniques↗
PubMedDate not supplied

Multicenter study of an erythro-aggregometer: quality control and standardization.

There is a need for quality assurance procedures in hemorheology, especially for clinical and pharmacological studies, which require reliable and well-calibrated instruments to be interpretable and comparable. Preliminary investigations allowed preparation of standardized SM (normal NS and hyperaggregable HS), and checking of storage conditions (in accordance with the guidelines of the SSC of ISTH) of RBC in nutritive SAG mannitol for at least 2 or 3 weeks with subsequent washings and resuspension in SM. In our study, we compared erythro-aggregometers of the same brand in 6 laboratories, using the same red blood cells (RBC) and suspending media (SM) for each series of tests. EA was measured by laser backscattering with determination of aggregation time (AT), partial dissociation threshold (PDT) and aggregation index (AI). Prior to the study, devices were set up on the same day with the same standardized blood, and calibration data were then analyzed. Within-assay precision (WAP) was assessed on 3 days for the 2 types of SM (n = 18 x 2). Between-assay precision (BAP) was assessed on 6 occasions, once every month (n = 6 x 2 x 6). Accuracy was studied with 3 series of RBC resuspended in 10 SM of "unknown" aggregability. Good agreement was observed between 5/6 centers for the 3 parameters of EA. WEP was good: CV of AT ranging from 1.4 to 2.5% for the NS and from 1.4 to 2.4% for the HS. In each center, BAP was slightly lower than WEP (CV: 8-11.8% for the NS and 3.8-4.7% for the HS over the 6-month study), with no drift, except for one center. Precision was always better with the HS than with the NS which seemed a better tool to assess it. As to accuracy, non-significant differences were generally found between centers, with similar data to the reference values. This work also stressed the importance of the RBC parameter itself in rheological data. For the first time, a protocol for standardization of EA has been developed and evaluated, permitting the Quality Control of this technique.

Analysis of Variance↗