Nanocarrier based active targeting strategies against erythrocytic stage of malaria

The Global Technical Strategy for Malaria 2016-2030 aims to achieve a 90% reduction in malaria cases, and strategic planning and execution are crucial for accomplishing this target. This review aims to understand the complex interaction between erythrocytic receptors and parasites and to use this knowledge to actively target the erythrocytic stage of malaria. The review provides insight into the malaria life cycle, which involves various receptors such as glycophorin A, B, C, and D (GPA/B/C/D), complement receptor 1, basigin, semaphorin 7a, Band 3/ GPA, Kx, and heparan sulfate proteoglycan for parasite cellular binding and ingress in the erythrocytic and exo-erythrocytic stages. Synthetic peptides mimicking P. falciparum receptor binding ligands, human serum albumin, chondroitin sulfate, synthetic polymers, and lipids have been utilized as ligands and decorated onto nanocarriers for specific targeting to parasite-infected erythrocytes. The need of the hour for treatment and prophylaxis against malaria is a broadened horizon that includes multiple targeting strategies against the entry, proliferation, and transmission stages of the parasite. Platform technologies with established pre-clinical safety and efficacy should be translated into clinical evaluation and formulation scale-up. Future development should be directed towards nanovaccines as proactive tools against malaria infection.

Quantitative assessment of infusion pump-mediated haemolysis in feline packed red blood cell transfusions

OBJECTIVES

Haemolysis caused by the use of peristaltic infusion pumps (PIPs) has been described in human and canine packed red blood cells (pRBCs). The aim of this study was to evaluate the effects of two different linear PIPs on the haemolysis of feline pRBC units stored for a long time.

METHODS

Feline pRBC units stored with adenine, dextrose, mannitol and sodium chloride (SAGM) were manufactured. After 35-42 days of storage at 2-4°C, a line administration system with a 180 µm filter was attached to every pRBC bag, the system was drained by gravity alone (8 drops/min) and a 1.3 ml sample was collected (G). A NIKI V4 pump was then used at a flow rate of 25 ml/h, the flow was stopped when the infusion system was filled with blood coming from the infusion pump and another 1.3 ml sample was collected (NK). Finally, an Infusomat FmS pump was evaluated, collecting another 1.3 ml sample (IM). Packed cell volume (PCV) was measured in all samples by microhaematocrit centrifugation, total haemoglobin (HGB) was measured using a specific haemoglobin analyser and, after centrifugation, free HGB was determined by spectrophotometry. The percentage of haemolysis was calculated. Friedman's test was used to compare the samples.

RESULTS

Fifteen feline pRBC units were evaluated. The average degree of haemolysis for sample G (gravity-assisted) was 1.12%. Comparison of the degree of gravity-assisted haemolysis with haemolysis in PIP NK (1.13%) and IM (1.14%) samples revealed no significant differences, with differences of only 0.01% and 0.02%, respectively.

CONCLUSIONS AND RELEVANCE

The results of this study demonstrate that the use of two common PIPs in veterinary hospitals does not produce levels of haemolysis that are significantly different than that caused by gravity alone during transfusion of feline pRBCs at a rate of 25 ml/h.

Performance of a Nageotte hemocytometer method and a flow cytometric assay for residual leukocyte quantification in leukoreduced canine packed red blood cells

OBJECTIVE

To evaluate the performances of a manual Nageotte hemocytometer method and commercial fluorescent bead-based flow cytometric assay for quantifying [rWBC] in leukoreduced canine packed red blood cell (pRBC) units.

DESIGN

Prospective study. Five, commercially purchased, double leukoreduced canine pRBC units were spiked with canine leukocytes to create 6 pRBC standards with the following [rWBC]: < 0.1, 0.375, 1.5, 3.0, 6.0, and 24.0 WBC/µL. [rWBC] of each pRBC standard was measured with the Nageotte hemocytometer and flow cytometric techniques. Limit of detection (LoD), linearity, and bias were determined for each method. For each standard, accuracy and precision were calculated; the cumulative accuracy and mean precision for measurements between the LoD and 24.0 WBC/µL were also determined.

SETTING

University veterinary blood bank and clinical pathology laboratory.

MEASUREMENTS AND MAIN RESULTS

The Nageotte hemocytometer method had an LoD = 1.48 WBC/µL, inadequate linearity (R²  = 0.92), and a significant negative proportional bias (slope best-fit line = 0.52 ± 0.03). Between [rWBC] 1.5-24 WBC/µL, the technique demonstrated poor cumulative accuracy (6.7%) but acceptable mean precision (17.3%). Relative to a 2 rWBC/µL threshold, at 1.5 WBC/µL the method was inaccurate (6.7%) with acceptable precision (16.6%). The flow cytometric assay had an LoD = 1.3 WBC/µL, acceptable linearity (R²  = 0.99), and a mild positive proportional bias (slope best-fit line = 1.11 ± 0.01). The technique had acceptable cumulative accuracy (80%) and mean precision (10.7%) for measuring [rWBC] between 1.5 and 24 WBC/µL. At 1.5 WBC/µL, this method was acceptably accurate (86.7%) and precise (16.0%).

CONCLUSIONS

The flow cytometric assay demonstrated acceptable performance for quantification of [rWBC] in leukoreduced canine pRBC units. The Nageotte hemocytometer method should be used cautiously due to poor accuracy and significant negative bias.

In vitro quality control analysis after processing and during storage of feline packed red blood cells units

BACKGROUND

During the storage of packed red blood cells (pRBC), packed cell volume (PCV), bacterial contamination and percentage of haemolysis [percentage of free haemoglobin (HGB) in relation to the total HGB] are important quality parameters. Both PCV and haemolysis are indicators of the cellular integrity of stored units. There are no published experimental studies that evaluated these parameters during storage of feline pRBC using SAGM (adenine, dextrose, mannitol and sodium chloride) as the additive solution. The present study aims to (1) evaluate the quality of feline pRBCs stored in SAGM; (2) test for the semi-closed system's suitability for use and risk of bacterial contamination; (3) establish the maximum storage time that may be appropriate to meet the criteria established by the United States Food and Drug Administration (US-FDA) guidelines for human blood banking; and (4) evaluate the need to calculate the percentage of haemolysis prior to the administration of units stored for more than 4 weeks. Four hundred eighty nine feline pRBC units were analyzed. Bacterial culture, PCV and percentage of haemolysis were determined within 6 h after processing (t0). One hundred and eighty units were re-tested for haemolysis and PCV after 29-35 days of storage (t1) and 118 units after 36-42 days (t2).

RESULTS

Bacterial contamination was not detected in any pRBC unit. Mean PCV at t0 was 52.25% (SD: ±5.27) and decreased significantly (p < 0.001) during storage to 48.15% (SD: ±3.79) at t1 and to 49.34% (SD: ±4.45) at t2. Mean percentage of haemolysis at t0 was 0.07% (SD: ±0.06) and increased significantly (p < 0.001) to 0.69% (SD: ±0.40) at t1 and to 0.81% (SD: ±0.47) at t2. In addition, 13.88% and 19.49% of pRBC units exceeded 1% haemolysis at t1 and t2, respectively.

CONCLUSIONS

According to the US-FDA guidelines for human blood banking that recommend a maximum of 1% haemolysis, the results of this study show that all feline pRBC units with less than 24 h of shelf life have low levels of haemolysis. However, units preserved up to 28 days can only be administered if tested for haemolysis before use, since 13.88% units exceeded the 1% limit. The semi-closed system was considered safe for use as bacterial contamination was not detected in any pRBC unit.

Development of anemia, phlebotomy practices, and blood transfusion requirements in 45 critically ill cats (2009-2011)

OBJECTIVE

To describe the incidence of the development of anemia, the number of phlebotomies performed daily, the approximate volume of blood withdrawn, the transfusion requirements and their association with duration of hospitalization and survival to discharge in critically ill cats.

DESIGN

Retrospective study from January 2009 to January 2011.

SETTING

University teaching hospital.

ANIMALS

Cats hospitalized in the intensive care unit (ICU) for >48 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records of cats hospitalized for >48 hours in the ICU were examined. Of the 45 cats included, 60% (27/45) were not anemic upon admission to the ICU. Of these, 74.1% (20/27) developed anemia during their ICU stay. Development of anemia was associated with a longer duration of hospitalization (P = 0.002) but not with survival (P = 0.46). Fourteen cats (31.1%; 14/45) received one or more packed red blood cell transfusions and had significantly longer ICU stays (P < 0.001). Transfusion requirements were not associated with survival (P = 0.66). The median number of phlebotomies per day for all cats in the ICU was 3 (range 1-6). This was significantly associated with the development of anemia (P = 0.0011) and higher transfusion requirements (P = 0.16) in the 14 cats that received a transfusion. The estimated volume phlebotomized was significantly (P < 0.001) greater in cats that required a transfusion (median volume 3.32 mL/kg/ICU stay) compared to cats that did not require a transfusion (median volume 1.11 mL/kg/ICU stay) but was not associated with survival to discharge (P = 0.84).

CONCLUSIONS

Development of anemia necessitating blood transfusions is common in critically ill cats and leads to significantly longer duration of ICU hospitalization. Iatrogenic anemia from frequent phlebotomies is an important cause for increased transfusion requirement. Fewer phlebotomies and other blood conserving strategies in these patients may help reduce the incidence of anemia and decrease transfusion requirements, as well as result in shorter hospital stays.

Effect of premedication and other factors on the occurrence of acute transfusion reactions in dogs

OBJECTIVE

To evaluate the effect of premedication on transfusion reactions (TRs) within 24 hours after blood product transfusions in dogs.

DESIGN

Retrospective study between 2008 and 2011.

SETTING

Private veterinary referral hospital.

ANIMALS

Nine hundred and thirty-five transfusion events in 558 dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Medical records of dogs receiving blood product transfusions were reviewed. Information collected included signalment, weight, transfusion product type, reason for transfusion, first or subsequent transfusion, whether an acute reaction occurred, type of reaction, whether the reaction was treated, premedication prior to the transfusion and the premedication used, other medications the animal was given, whether the animal had an immune-mediated process, and whether the transfusion was administered in the perioperative period. A total of 144 (15%) acute TRs were documented in 136 dogs. The most common TRs were fever alone (77/144 [53%]) and vomiting alone (26/144 [18%]). Six dogs died due to the TR (4%). TR was not associated with age (P = 0.257), sex (P = 0.754), weight (P = 0.829), or premedication (P = 0.312). The type of blood product transfused (P < 0.001) was significantly associated with TRs, with packed RBCs most likely associated with a TR, and plasma least likely. Immune disease (P = 0.015) was significantly associated with occurrence of a TR. Significantly fewer reactions were documented following transfusions given in the perioperative period (P = 0.023).

CONCLUSIONS

While most TRs were mild, there were some serious reactions observed including hemolysis, dyspnea, and 6 deaths. Immune-mediated disease was associated with development of a TR, while transfusion during the perioperative period was associated with lower likelihood of reaction. Packed RBC transfusions were associated with development of acute TRs. Overall occurrence of TR was not significantly altered with premedication; however, when evaluated alone, antihistamines decreased the incidence of acute allergic reactions.

Utilization management in the blood transfusion service

The scope of activity of the Blood Transfusion Service (BTS) makes it unique among the clinical laboratories. The combination of therapeutic and diagnostic roles necessitates a multi-faceted approach to utilization management in the BTS. We present our experience in utilization management in large academic medical center.

Comparison of three methods for measuring thiopurine methyltransferase activity in red blood cells and human leukemia cells

Thiopurine efficacy is partly reflected by the genetic polymorphism of the thiopurine methyltransferase (TPMT) enzyme, which is responsible for variation in the metabolism, toxicity and therapeutic efficacy of the thiopurines azathioprine (AZA), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). Determination of TPMT activity before administration of thiopurines is thus crucial for individualized dosing in order to prevent toxicity in TPMT deficient individuals. These individuals must be treated with markedly lower (eg, 5-10% of the standard) doses of the prescribed medications. This paper describes a comparison of three different methods for the quantification of TPMT activity in red blood cells (RBC) and cultured human cell lines. We succeeded to perform the measurement of TPMT activity in a minimum amount of 1×10(6) cultured cells with an HPLC-UV system modified and optimized in our laboratory. The TPMT activity was linearly correlated with the cell concentration of the cultured cell line in a range of 1-10×10(6) cells. A significant correlation of determination of TPMT activity in RBC between radiometric detection by HPLC, classic radiochemical detection and UV detection by HPLC, was observed, correlation coefficient (r) were 0.72 and 0.73, respectively. The within-day and day-to-day coefficients of variation of the HPLC-UV-based method were 8% and 16%, respectively. The evaluation of the methods was demonstrated by studying the TPMT activity in RBC isolated from 198 patients, as well as in MOLT4 leukemic cell line and its sub-cell lines with acquired resistance to 6-MP and 6-TG.

Primary prevention of pediatric lead exposure requires new approaches to transfusion screening

OBJECTIVE

To facilitate further assessment of transfusion-associated lead exposure by designing a procedure to test packed red blood cells (pRBCs) prepared for transfusion.

STUDY DESIGN

The relationship between pRBCs and whole blood lead concentration was investigated in 27 samples using a modified clinical assay. Lead concentrations were measured in 100 pRBC units.

RESULTS

Our sample preparation method demonstrated a correlation between whole blood lead and pRBC lead concentrations (R(2) = 0.82). In addition, all 100 pRBC units tested had detectable lead levels. The median pRBC lead concentration was 0.8 μg/dL, with an SD of 0.8 μg/dL and a range of 0.2-4.1 μg/dL. In addition, after only a few days of storage, approximately 25% of whole blood lead was found in the supernatant plasma.

CONCLUSION

Transfusion of pRBCs is a source of lead exposure. Here we report the quantification of lead concentration in pRBCs. We found a >20-fold range of lead concentrations in the samples tested. Pretransfusion testing of pRBC units according to our proposed approach or donor screening of whole blood lead and selection of below-average units for transfusion to children would diminish an easily overlooked source of pediatric lead exposure.