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J Seghatchian

Publications and source records attributed to J Seghatchian.

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

A case of leucodepletion failure in Cobe spectra plateletpheresis: further studies on the identification of the potential cause.

A 54-year-old double dose donor failed leucodepletion by Cobe LRS for five sequential donations, without triggering the "machine failure alarm". All collections were uneventful but final products appeared lipaemic. The last two donations were studied: (i) by collecting the first half of each donation into one bag and the other half into a second bag. In both cases, the product in bag one was leucodepleted and that in bag two "failed" leucodepletion. (ii) By examining the filterability of the final products using an LRF6 filter. Leucodepletion was satisfactory but showed a slightly higher level of leucocytes as compared to control or lipaemic donations, possibly due to the presence of an interfering substance in the platelet product. (iii) By examining the cellular content of the LRS cone and comparing it with those obtained from lipaemic donations from other donors. Only the test cone contained a large mass of waxy white material. It is postulated that this material was gradually filling the cone and increasingly interfering with its leucodepleting function as the donation progressed. (iv) To monitor pre/post whole blood as well as the products for the presence of abnormal leucocyte subsets. The only difference was the presence of some extra abnormal dot plot. The intensity of these extra events which was reduced both upon donation and filtration. We conclude that, in this case, failure of leucodepletion was clearly donor rather than machine or process related. The implementation of this investigative study may help in the characterisation of the potential cause of leucodepletion failures.

Blood Donors↗
PubMed2000

UK strategy for process qualification/validation: from concept to practical implementation.

In this communication, after a brief review of current requirements of various stages of leucodepletion qualification/validation processes, we provide some practical examples for the usefulness of long term validation programme for process improvement. It is hoped that the experience gained from this process qualification/validation enhances the awareness to key variables that can influence the overall outcome of filtration programme.

Biomedical Technology↗
PubMed2000

The role of in process qualification in quality improvement of the haemonetics MCS plus leucodepleted platelet concentrate.

With the implementation of universal leucodepletion in UK all leucodepletion processes have gone through a standard process qualification and quality improvement. The Haemonetics MCS system is a well established automated platelet collection system for the production of double dose leucoreduced platelet concentrate (WBC approximately 70x10(6)/dose). Recently an automated post collection filtration harness system has been introduced (MCS plus LDP) in which platelets are filtered, using an in-line PALL polyester filter (LRFH6 PALL) to reduce the WBC level to below 5x10(6) WBC/dose. This system passed our Phase I evaluation process based on 20-40 runs. However, some changes in the final volume of the products were needed to conform to national guidelines. Large scale trials using the new volume adjusted protocol revealed occasional failure in the leucocyte content. Therefore, 100% testing had to be implemented on all products. A national evaluation was carried out to determine whether changing the filter to a more efficacious one, the LRFXL (PALL) or slowing the filtration flow rate can influence the overall outcome. To reduce donor variability, known donor population were used with identical apheresis conditions. A more consistent and systematic drop in leucocyte content was observed by reducing the flow rate whereas a similar failure (i.e. 1-3%) rate was found both in controls and LRFXL when using the standard head pressure, which is recommended by the manufacturer. A similar failure rate was found using three different low leucocyte counting technologies (Nageotte, flow cytometry and Imagn 2000). It is recommended that a process qualification/validation program should be implemented when even a small modification in the collection system is introduced.

Automation↗
PubMed2000

Leucodepletion process performance variation: is it dependent on the batch of filters, the processing centre or the counting technology?

The aim of this retrospective study was to determine whether variations in the enumerated white cell contamination of leucocyte-depleted products was caused by the filter batch, the processing centre or by counting technology related issues. The influence of donor variation is also considered. The results suggest that for some red cell processes, variation is mainly the result of counting technology differences. Other products do not display similar trends though all leucodepletion processes may give rare high white count failures due to donor related issues, though defective filter batch cannot be excluded requiring continual review.

Adult↗
PubMed2000

Coagulation factor content of cryoprecipitate prepared from methylene blue plus light virus-inactivated plasma.

Levels of factor VIII (FVIII) and fibrinogen were assessed in control cryoprecipitate and cryoprecipitate prepared in two centres from plasma subjected to methylene blue (MB) photochemical virus inactivation. The level of coagulation FVIII activity was reduced in plasma by approximately 30% after MB photoinactivation, with only 44% (centre A) and 31% (centre B) of units meeting the current UK specification of 0.7 iu/ml. A revised specification of 0.5 iu/ml is suggested. Losses of less than 11% were seen for von Willebrand factor (VWF)-related activities. Cryoprecipitate prepared from group O or group A MB-treated plasma contained 27-40% less FVIII than control units. This reflected the lower levels in MB-treated plasma. The concentrating power of the cryoprecipitation process was not reduced for FVIII or fibrinogen in MB-treated units. MB cryoprecipitate from centre A still met the UK guideline specification for FVIII and fibrinogen content, whereas at centre B only 62.5% of the group O cryoprecipitates contained > 70 iu FVIII/unit. This may reflect the lower product volume and lower FVIII content of group O plasma used at centre B and suggests that maintenance of total coagulation factor recovery in MB-treated cryoprecipitate will require the higher product volume.

Antigens↗
PubMed2000

Preparation and storage characteristics of white cell-reduced high-concentration platelet concentrates collected by anapheresis system for transfusions in utero.

BACKGROUND: Important concerns with regard to in utero platelet transfusions are avoidance of volume overload and the immunomodulatory effects of residual white cells (WBCs). This study evaluated a modification of a leukocyte-reduction system (LRS, Spectra, COBE BCT) for apheresis, which collects high-concentration WBC-reduced platelets (HCPs) for in utero transfusion. STUDY DESIGN AND METHODS: The LRS procedure was modified by running the platelet collection pump at specified low flow rates (Q(col)) for the first part of the procedure, collecting HCPs by gently purging them from the LRS chamber into a designated collection bag and then restoring the original LRS procedure settings to collect a second standard apheresis platelet concentrate (PC). Two centers carried out 32 procedures. Platelet yield, residual WBCs, and in vitro platelet function studies were evaluated. RESULTS: Platelet concentrations in 60 mL of HCPs were predictable according to Q(col) (r(2) = 0.735). HCP yields varied from 0.9 to 3.2 x 10(11), depending on the desired final platelet concentrations in 60 mL, with an overall average of 1. 92 x 10(11) (n = 32). Apheresis PCs had a mean platelet yield of 2.9 x 10(11) (1.3-4.4 x 10(11), n = 20) and 3.9 x 10(11) (2.2-5.8 x 10(11), n = 12) at concentrations of 1.3 x 10(12) per L for single-needle and dual- needle procedures, respectively. Median WBC counts were 5.6 x 10(3) for HCPs and 2.0 x 10(4) for apheresis PCs, with >99 percent expected to be less than 1 x 10(6). HCP in vitro characteristics were equivalent to those of apheresis PCs at 24 hours after collection. In vitro performance declined over storage as a function of HCP yield. HCP pH at 22(o)C was maintained at a level of >6.2 for more than 3 days for yields >1.6 x 10(11), less than 2 days for yields 1.6 to 2.2 x 10(11), and less than 24 hours for yields >2.2 x 10(11). HCPs showed good in vitro characteristics and could be stored for 1 to 3 days, depending on the total number of platelets collected. CONCLUSION: A standard apheresis PC and an HCP requiring no secondary processing can be collected with the Spectra LRS. The platelet concentration may be determined by clinical need. HCPs meet the requirements for components that are transfused in utero.

Blood Platelets↗
PubMed2000

Are all leucodepleted platelet concentrates equivalent? Comparison of Cobe LRS Turbo, Haemonetics MCS+ LD, and filtered pooled buffy-coat-derived platelets.

BACKGROUND AND OBJECTIVES: A number of technologies are available for the production of leucocyte-depleted platelet concentrates (PCs). This study compared the characteristics of PCs prepared by three commonly used techniques. MATERIALS AND METHODS: In total, fifteen units of leucocyte-depleted PCs prepared by the Cobe LRS Turbo apheresis system, Haemonetics MCS+ with in-line filter and filtration of PCs derived from pooled buffy coats (BCs) were transferred into the same standard container. Markers to assess status/activation and microvesiculation of platelets as well as platelet injury were measured. RESULTS: pH was well maintained in all types of PCs. The expression of CD62P was higher in Cobe LRS Turbo on day 1 but became equivalent between the three methods on day 5. A significant correlation was found between the expression of CD62P on platelet surface and soluble CD62P in the plasma. The degree of phosphatidylserine (PS) exposure was slightly higher in Cobe LRS Turbo and BC-PCs than Haemonetics MCS+ on day 1. However, on day 5 both apheresis PC values were higher than BC-PCs. A significant correlation was found between PS exposure and microvesiculation. CONCLUSION: Leucodepleted PCs prepared by the three methods were different in terms of storage lesion and microvesiculation. The clinical significance of these findings remains to be investigated.

Annexin A5↗
PubMed1999

The UK strategy for monitoring universal leucodepletion.

This summary manuscript deals with the NBS approach to quality monitoring of universal leucodepletion based on representative sampling. There is also a brief discussion on the failure rate and potential causes for the inter site variations in white cell enumeration by current methods.

Artifacts↗
PubMed1997

Current methods for the preparation of platelet concentrates: laboratory and clinical aspects.

Modern blood transfusion services are striving to attain the highest standards through continual quality improvement and ensure that a formalised quality system is in place in the organisation for time management and waste reduction. With respect to the production of platelet concentrates (PCs), semi-automated and automated procedures are now available which are convenient and allow the processing of multiple packs simultaneously or the production of multiple doses of PCs with low leucocyte content. Nevertheless, PCs are highly heterogeneous on the basis of cellular content and storage stability. Statistical process control (SPC) is essential to ensure that optimal quality is maintained. In the light of new developments in platelet production, their clinical effect should be reappraised. This article highlights some of the key features in the production of PCs, focusing on basic concepts and quality indicators which reflect in vivo functions. The potential for bacteriological contamination and future production strategies are briefly mentioned.

Blood Platelets↗
PubMed1997

Annexin V, a new marker of platelet storage lesion: correlation with dMPV.

Released annexin V, an intracellular platelets glycoprotein, was used to determine the cellular injury which occurred during storage of platelet concentrates. Twenty-eight units of leuco-reduced apheresis platelet concentrates, obtained without leucocyte filtration, were analysed. Released annexin V showed a significant correlation with EDTA-induced shape changes of platelet (r = 0.62, P < 0.01) while poor correlation was found between released annexin V and pH or MPV. The combination of released annexin V with dMPV provides excellent markers of the platelet storage lesion for quality monitoring, based on morphological/functional integrities and cellular injury, which are of direct relevance to clinical efficacy of platelet concentrates.

Annexin A5↗