Experimental pitting rate in isolated-perfused spleens compared with published data in artesunate-treated patients16
. | Experiment 1 . | Experiment 2 . | DHA-treated patients data from Newton et al16 . |
|---|---|---|---|
| Total volume of red blood cells (RBCs) in IP-spleen perfusate or in patient blood, mL | 13 | 10 | 1500-2000 |
| iRBCs in IP-spleen perfusate or in patient blood | |||
| Initial concentration, % of RBCs | 2.6 | 5.63 | 7.63 |
| Total volume, mL* | 0.338 | 0.563 | > 100 |
| Total no. | 3.38 × 109 | 5.63 × 109 | > 1012 |
| Parasite clearance time (corrected value), h† | ≥ 2 (≥40) | ≥2 (≥40) | 60 |
| Peak concentration of once-infected RBCs (O-iRBCs), % of RBCs‡ | 0.31 | 1.19 | 1.8 (0.8-8.8) |
| Estimated global proportion of Art-iRBCs pitted during the experiment, %§ | 11.9 | 21.1 | NA |
| Estimated cumulative no. Art-iRBCs pitted|| | 4.03 × 108 | 11.33 × 108 | NA |
| Time to peak of O-iRBCs (corrected value), h† | 1 (20) | 1.5 (30) | 45 |
| Calculated no. of Art-iRBCs pitted per h, × 108 | 4.03 | 7.55 | 21 (5-126) |
| Estimated amount of Art-iRBCs pitted per spleen transit¶, × 106 | 6.71 | 12.59 | 26 (6-177) |
| Pitting rate per body transit, % of iRBCs | NA | NA | 0.003 (0.001-0.05) |
| Calculated pitting rate per spleen transit, % of iRBCs** | 0.2 | 0.23 | 0.06 (0.02-1)†† |
. | Experiment 1 . | Experiment 2 . | DHA-treated patients data from Newton et al16 . |
|---|---|---|---|
| Total volume of red blood cells (RBCs) in IP-spleen perfusate or in patient blood, mL | 13 | 10 | 1500-2000 |
| iRBCs in IP-spleen perfusate or in patient blood | |||
| Initial concentration, % of RBCs | 2.6 | 5.63 | 7.63 |
| Total volume, mL* | 0.338 | 0.563 | > 100 |
| Total no. | 3.38 × 109 | 5.63 × 109 | > 1012 |
| Parasite clearance time (corrected value), h† | ≥ 2 (≥40) | ≥2 (≥40) | 60 |
| Peak concentration of once-infected RBCs (O-iRBCs), % of RBCs‡ | 0.31 | 1.19 | 1.8 (0.8-8.8) |
| Estimated global proportion of Art-iRBCs pitted during the experiment, %§ | 11.9 | 21.1 | NA |
| Estimated cumulative no. Art-iRBCs pitted|| | 4.03 × 108 | 11.33 × 108 | NA |
| Time to peak of O-iRBCs (corrected value), h† | 1 (20) | 1.5 (30) | 45 |
| Calculated no. of Art-iRBCs pitted per h, × 108 | 4.03 | 7.55 | 21 (5-126) |
| Estimated amount of Art-iRBCs pitted per spleen transit¶, × 106 | 6.71 | 12.59 | 26 (6-177) |
| Pitting rate per body transit, % of iRBCs | NA | NA | 0.003 (0.001-0.05) |
| Calculated pitting rate per spleen transit, % of iRBCs** | 0.2 | 0.23 | 0.06 (0.02-1)†† |
NA indicates not assessed.
Number calculated assuming an RBC concentration of 1010/mL (10–3/L)
Observed parasite clearance time and time to peak of O-iRBCs were multiplied by 20 [corrected time] to take into account the fact that a given iRBC crosses patient spleen every 20 minutes, but does so every minute through isolated perfused spleens
The concentration of O-iRBCs at any time point was calculated using the following formula: concentration of O-iRBCs in the perfusate = % of iRBCs on Giemsa-stained smears: [number O-iRBCs/number of iRBCs] on EMIF- and Hoechst-stained slides. The peak concentration was the highest observed value in each experiment. Because the peak concentration of O-iRBCs depends on parasitemia on Giemsa smears, it may not be perfectly synchronous with the peak proportion of O-iRBCs among EMIF-positive cells. This occurred during experiment 1
The estimated pitting rate was calculated by dividing the peak concentration of O-iRBCs by the initial iRBC concentration, an acceptable assumption since the hematocrit level remained stable during experiments
Indicates number of O-irBCs produced. This minimal value was estimated under the hypothesis that no O-iRBC clearance occurred before the peak O-iRBC concentration was reached
Assuming that the whole RBC pool crossed IP-spleens once per minute
Pitting rate per spleen transit = number of Art-iRBCs pitted during the experiment: number of spleen transits to reach the peak (ie, 60 for experiment 1 and 90 for experiment 2)
Pitting rate was calculated per body transit in patients.16 It takes approximately 20 body transits for a given iRBC to cross the spleen once