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Biomedical subjects

H W Reesink

Publications and source records attributed to H W Reesink.

At least 55 records · Page 3Linked to original sources
PubMed2001

Sustained virological response in chronic hepatitis C patients after a 6- and a 36-month interferon-alpha2b treatment schedule: a multicenter, randomized, controlled study.

BACKGROUND: In patients with chronic hepatitis C (HCV) Interferon-alpha (IFN) treatment for 12-18 months is more effective than 6 months in inducing a sustained virological response. METHODS: In a multicenter, randomized, controlled trial, 88 patients with chronic HCV were enrolled (47 treated with IFN-alpha2b and 41 constituted an untreated control group). Treatment consisted of 5 million units (MU) IFN thrice a week (tiw) for 8 weeks and subsequently 2.5 MU IFN tiw for 16 weeks ('standard treatment'). After week 24 ('long-term treatment'), in virological non-responders treatment was continued using 5 MU IFN tiw for up to week 156, whereas in virological responders IFN was discontinued. In case of a virological relapse, treatment with 5 MU IFN tiw was restarted and continued up to week 156. RESULTS: Sustained virological response rate was 6/47 (13%) after standard treatment and increased to 19/47 (40%) after long-term treatment (McNemar paired test; P = 0.002). Of the 18 patients with a breakthrough or relapse during or after standard treatment, 14 (78%) became sustained virological responders upon long-term treatment. Of the 4 patients who did not have a sustained virological response after long-term treatment, 3 did not receive complete treatment due to side effects and/or non-compliance. In patients who failed to respond to standard treatment, no virological response was observed during long-term treatment. In the control group, no spontaneous clearance of HCV was observed. CONCLUSIONS: Long-term IFN (re)treatment enhanced the virological sustained response rate significantly and was particularly effective in patients with a breakthrough or relapse following standard treatment.

Adult↗
PubMed2000

Evaluation of automated RNA-extraction technology and a qualitative HCV assay for sensitivity and detection of HCV RNA in pool-screening systems.

BACKGROUND: The objective of this study was the evaluation of NAT technology for the detection of HCV RNA in plasma pools according to the recommendations of the Paul Ehrlich Institute (5000 IU/mL/donation) and the Committee for Proprietary Medical Products (100 IU/mL/manufacturing pool). STUDY DESIGN AND METHODS: Serial dilutions of both the EUROHEP standard (3,800 genome equivalents [geq]/mL; HCV genotype 1) and the World Health Organization (WHO) international standard (100,000 IU/mL; HCV genotype 1) were made in S/D plasma (ESPEP plasma, OctaPharma), which was nonreactive in serologic tests. Serial dilutions of plasma (2 mL) were used for extraction of HCV RNA with an automated version of a nucleic acid isolation method (NucliSens Extractor, Organon Teknika). HCV RNA was co-extracted from 2 mL of plasma, together with 84 copies of an in vitro-synthesized single-strand RNA serving as internal extraction control (IC) to monitor the efficiency of extraction and PCR. Amplification and detection of both HCV RNA and IC RNA were performed with an automated PCR system and a qualitative HCV assay (COBAS Amplicor 2.0 HCV, Roche Diagnostics). RESULTS: A cutoff value of 16 geq per mL (10/10 runs [100% hit rate]) was found by using the EUROHEP standard, whereas the WHO international standard had a cutoff value of approximately 12 IU per mL (10/10 runs [100% hit rate]). The IC had a cutoff value of approximately 17.5 copies per mL (6/6 runs [100% hit rate]). Forty-two copies per mL of IC RNA were found in 282 of 284 runs (99% hit rate). The negative controls (ESDEP plasma) were negative in all experiments. Experiments with pool sizes of 12, 24, 48, and 96 using serial dilutions of the WHO international standard revealed a cutoff value of 8 IU per mL (100% hit rate). The EUROHEP standard and the WHO international standard were detected with a 50 percent detection endpoint of 5.2 geq per mL and 1.5 IU per mL, respectively. CONCLUSION: This test system (NucliSens Extractor, and the COBAS Amplicor 2.0 HCV assay) revealed a high sensitivity for HCV RNA; considering the proposed requirements for sensitivity of NAT assays for the detection of HCV RNA in donor plasma, pool sizes of about 400 donors are possible. These endpoint results indicated that 1 IU is equal to about 3.4 geq.

Autoanalysis↗
PubMed2000

Compodock, a new device for sterile docking.

BACKGROUND: A new device for sterile docking, the Compodock (Fresenius NPBI Transfusion Technology), was developed for connecting PVC tubing for medical use while maintaining sterility. STUDY DESIGN AND METHODS: Sterility of the connections was assessed by welding tubing with a heavy exterior contamination with Bacillus subtilis spores and also by welding in an environment contaminated with aerosols of B. subtilis. Tubing was either dry or liquid-filled ("wet") and had various diameters. Bacterial culture medium was flushed through the welded area and subsequently cultured. Tensile strength was measured, and, under semi-routine conditions, Compodock was tested for user friendliness and speed. RESULTS: None of the cultures of welded tubing with exterior contamination showed growth, neither the dry-dry (n = 434) nor the wet-wet connections (n = 622). Cultures were also negative for welds made in the contaminated environment (dry-dry, 67; wet-wet, 55). Tensile strength complied fully with ISO 3826 standards (that is, a force of 20 newtons [N] for 15 sec), with a mean maximal strength ranging from 73 to 100 N, depending on diameter and content of the tubing. The semi-routine handling was regarded as good: welds were easily opened; there were clear instructions and error warnings; and the processing time averaged 52 seconds. CONCLUSION: The Compodock is able to maintain a functionally closed system, with maintenance of sterility, despite heavy exterior bacterial contamination; tensile strength conformed to ISO standards. Compodock is suitable for routine implementation in the blood bank.

Bacillus subtilis↗
PubMed2000

Leukoreduction of platelet concentrates using a 'polishing' filter.

BACKGROUND AND OBJECTIVES: Filters for removal of leukocytes from platelet concentrates (PCs) usually have a large volume to guarantee sufficient leukoreduction. In this study, a small filter, with a volume of only 8 ml and therefore minimal platelet loss, for leukoreduction of PCs was investigated. This filter has a 'limited' leukoreducing capacity, hence the filter is called a 'polishing' filter. MATERIALS AND METHODS: PCs were made from 5 pooled buffy coats in either plasma or additive solution (PAS-II). After centrifugation, the platelet-rich supernatant was expressed on an automated separator (Compomat G4) to an empty transfer bag. The content of this transfer bag was filtered into the platelet storage bag, either by expression by lowering the top press of the Compomat G4, or by gravity by hanging it on a filtration rack. RESULTS: Leukocyte counts before and after filtration revealed a mean leukoreducing capacity for the filter of 2.67 log(10) and a platelet loss of only 2% for PCs in PAS-II (n = 50), and for PCs in plasma a 3.43 log(10) leukoreduction with 3% platelet loss (n = 30). Expression of the PCs both in plasma and PAS-II through the filter using the Compomat G4 resulted in 10/10 units containing <5x10(6) leukocytes, but 1/10 PCs contained >1x10(6) leukocytes for both solutions. Filtration by gravity resultet in 40/40 units with <1x10(6) leukocytes for PCs in plasma, and 60/60 units with <1x10(6) for PCs in PAS-II. CONCLUSION: The 'polishing' filter allows reliable, standardized and automated production of PCs, both in plasma and additive solution with minimal platelet loss, and containing uniformly <1x10(6) leukocytes, provided the filtration procedure is performed by gravity.

Filtration↗
PubMed1999

Six filters for the removal of white cells from red cell concentrates, evaluated at 4 degrees C and/or at room temperature.

BACKGROUND: Six filters were tested for their ability to remove white cells from buffy coat-depleted red cell concentrates at various temperatures. STUDY DESIGN AND METHODS: Cellselect FR, BPF4, and Sepacell filters were tested at both room temperature (RT) and 4 degrees C. The Leucoflex filter was tested only at 4 degrees C, while the Cellselect Optima Plus and Imugard filters were tested only at RT. Donor-dependent differences were excluded by pooling and subsequently dividing 9 red cell concentrates; 12 sets of experiments were performed. RESULTS: With all filters, red cell concentrates containing <5 x 10(6) white cells per unit were obtained. The lowest numbers of residual white cells were achieved with the Leucoflex (at 4 degrees C, 0.15 +/- 0.11 x 10(6), the Sepacell (at 4 degrees C, 0.23 +/- 0.14 x 10(6), the Imugard (at RT, 0.24 +/- 0.14 x 10(6), and the BPF4 (at 4 degrees C, 0.25 +/- 0.24 x 10(6); differences not significant). With the Cellselect FR, filtration at 4 degrees C resulted in 0.86 +/- 0.37 x 10(6) white cells per unit, a level not significantly different from that obtained with the BPF4 and Sepacell filters at RT (1.16 +/- 0.43 x 10(6) and 0.80 +/- 0.36 x 10(6) white cells, respectively). Filtration at RT with the Cellselect FR and Cellselect Optima Plus resulted in red cell concentrates with 1.79 +/- 0.69 x 10(6) and 2.29 +/- 0.69 x 10(6) white cells, respectively (p<0.01). CONCLUSION: All filters conformed to the current standards for white cell reduction; the process was less efficient at RT than at 4 degrees C. For routine application, the composition of the red cell concentrate, the temperature, and logistic preferences should be taken into account in the final choice of filter; before implementation, the chosen filter must be validated under routine conditions.

Blood Cell Count↗
PubMed1999

Preparation of leukodepleted platelet concentrates from pooled buffy coats: prestorage filtration with Autostop BC.

BACKGROUND AND OBJECTIVES: Our requirements for leukocyte-depleted platelet concentrates (LD-PC) for an adult patient are: platelets >240x10(9), leukocytes <5x10(6), volume of 150-400 ml; and at the end of storage a pH between 6.8 and 7.4 and presence of the swirling effect. Our aim was to develop a standardized, semiautomated method for the production of LD-PC, by pooling of buffy coats (BC), and prestorage leukoreduction by filtration. MATERIALS AND METHODS: Whole blood was collected in Top and Bottom systems, and separated automatically with the Compomattrade mark G3 equipment into a red cell concentrate, a plasma and a BC. Subsequently, a pool of 5 BC was made, and 200 g plasma from one of the donors was added. Then, after soft spin centrifugation, the platelet rich plasma was leukocyte depleted by filtration using the Autostoptrade markBC filter, and stored in a 1,000 ml polyolefin platelet storage bag. RESULTS: BC (n = 60) had a volume of 51+/-2 ml (mean +/- SD) with a hematocrit of 0.44+/-0.03 l/l and contained 80+/-5% of the platelets and 74+/-12% of the leukocytes of the whole blood. Routinely prepared LD-PC (n = 15,037) contained a median of 341x10(9) platelets (range 49-599x10(9)), with only 104/15,037 (0.7%) containing fewer than 240x10(9) platelets; the median volume was 263 ml (range 134-373 ml). In 118/917 (13%) LD-PC leukocytes were observed in the Nageotte hemocytometer, but only twice exceeding 1x10(6) leukocytes per unit, and none exceeding 5x10(6) (median <0. 6x10(6); range <0.6-1.41x10(6)). Storage experiments of the LD-PC (n = 12) revealed adequate oxygenation and maintenance of pH and swirling effect up to 9 days. CONCLUSIONS: This method warrants with 99% confidence that LD-PC contain more than 240x10(9) platelets; with 97.5% confidence that 100% of the LD-PC contain <5x10(6) leukocytes, and with 95% confidence that more than 99% of the LD-PC contain fewer than 1x10(6) leukocytes; these LD-PC can be stored satisfactorily for up to 9 days.

Automation↗
PubMed1999

Collection of heparinized plasma by plasmapheresis.

BACKGROUND AND OBJECTIVES: Heparinized plasma can be used for exchange transfusions in neonates and is usually collected by drawing whole blood using heparin as anticoagulant. The heparinized red blood cells and buffy coat cannot be used and are therefore discarded. To collect heparinized plasma more efficiently, a method was developed using an apheresis machine. MATERIALS AND METHODS: With an MCS3p apheresis machine (Haemonetics), plasma was collected from volunteer donors as anticoagulant, heparin in saline (30,000 IU/l) was added in a 1:9 ratio. The activated partial thromboplastin time (APTT) of the donors was measured before and immediately after the procedure, and various parameters were determined in the collected plasma. RESULTS: In 2 collection cycles, an average of 456+/-52 ml (mean +/- SD; n = 20) of heparinized plasma was collected, and 504+/-57 ml (n = 2; donors with a high hemoglobin level) when 3 cycles were performed. The leukocyte and platelet contamination in the plasma (n = 22) was 1.11+/-0.92x10(6) and 0. 05+/-0.22x10(9) per unit, respectively, which conformed to national specifications. Sodium levels were normal, but due to dilution of the plasma with heparin solution, potassium and calcium levels were about 20% lower than the serum levels in the donors. The donor APTT values were slightly longer after the procedure than before, but remained all within normal values. CONCLUSION: For the collection of heparinized plasma, apheresis has the advantage that (1) high-quality heparinized plasma can be harvested; (2) no blood components need to be discarded; (3) more plasma can be harvested with each donation, and (4) these procedures can be performed more often than whole blood donations.

Adult↗