Reduced deformability of stored red blood cells is associated with generation of extracellular vesicles.

Throughout storage, red blood cells (RBCs) undergo detrimental changes in viability and their ability to effectively transport oxygen. RBC storage lesions are mediated, in part, by a progressive loss of cell deformability, and associated with the release of extracellular vesicles (EVs). Accumulation of EVs during the storage of RBCs correlates with a decrease in RBC surface area to volume ratio. Similarly, the loss of RBC-deformability is associated with loss of RBC surface area to volume ratio. In this study we thus tested whether loss of RBC-deformability is associated with increased RBC-EV production during blood storage. EVs obtained by differential centrifugation of stored RBCs (non-leukoreduced non-irradiated or leukoreduced γ-irradiated RBCs stored 35 or 28 days respectively) were enumerated by high-sensitivity flow cytometry. RBC deformability was quantified, using a cell-flow-properties-analyzer, by measuring the median cell elongation ratio (MER) and percentage of low and high deformable cells in the population (%, LDFC, and HDFC, respectively). The number of EVs was inversely correlated with the MER and positively correlated with the %LDFC with both measures showing highly significant logarithmic dependence with EV levels in stored RBCs. Considering how highly deformable cells did not correlate with EV formation as compared with low deformable RBCs we propose that the formation of EVs is a key factor leading to increased RBC-rigidity.

Luke warm blood cardioplegia for CAB surgery in patients with severely impaired LV function. Improved results.

Ward blood cardioplegia (WBC) has recently been reported to improve myocardial protection in adult open heart surgery, especially in high risk cases. However, WBC has been reported to have some disadvantages including narrow safety margins concerning brain and kidney perfusion. We therefore modified our technique to utilize luke-warm blood cardioplegia (LWBC). We carried out 470 open heart procedures using luke-warm cardioplegia (anterograde + retrograde perfusion) from 1/2/1991 - 30/9/1992; 94 had LVEF < 30% and form the basis of this study. Other major risk factors in this group included: > 70 yrs - 26 patients, L main > 50% - 14 patients, emergencies - 11 patients, redo's - 3 patients. Eightyone patients underwent CAB only; 3 had additional MVR, 3 additional closure acute VSD of whom one underwent additional LV aneurysmectomy, one additional AVR; 4 patients underwent AVR only, and 2 MVR. Average number of grafts/patient for the 81 isolated CAB's was 4.5. IABP was necessary postbypass in 4 patients (9 emergencies were on IABP support at time of operation). Thirty day mortality was 3 patients (3.2%). Late mortality was 5 cases. These results are superior to those achieved using cold protection and warm blood cardioplegia. LWBC is a safe method for myocardial protection in patients undergoing CAB, particularly when LV function is severely compromised.

Hemolytic effect of polymeric nanoparticles: role of albumin.

Nanoparticles (NP) have drawn increasing interest from many fields in medicine and are a relatively new class of biomedical products. Because there are concerns about the health effects of nanoparticles, it is important to understand how nanoparticles interact specifically with red blood cells (RBC), a central object in the blood circulation. As numerous studies that have examined NP/RBC interaction concentrated on the hemolytic potential of nanoparticles, we describe an investigation of hemolytic activity of polystyrene nanoparticles (PS-NP) in protein free medium and its modulation by albumin. We found that treatment of RBCs with PS-NP induces hemolysis (dose and particle size dependent) in plasma free medium but not in full plasma or in buffer, which contain albumin. Critical albumin concentration is 0.05% wt. According to our results hemolytic effect of nanoparticles is strongly modulated by protein concentration in the medium.

Air encircling the intussusceptum on air enema for intussusception reduction: an indication for surgery?

OBJECTIVES: The prompt identification of children in whom enema reduction of intussusception might fail and surgery is necessary is crucial in order to avoid futile repeat attempts and untoward complications. The purpose of this retrospective review was to determine whether air encircling the intussusceptum in the small bowel during air enema for intussusception reduction could serve as an indication for operation rather than repeat attempts at radiological reduction. METHODS: Imaging studies of 83 children aged 4 to 40 months with idiopathic intussusception who had air enema for intussusception reduction were reviewed for the presence of air encircling the intussusceptum in the distal small bowel. Findings were correlated with clinical course and surgical findings. RESULTS: In 12 of 83 patients, air was seen encircling the intussusceptum in the small bowel, and in 11 of these (88%) air enema failed to reduce the intussusception. In 8 of the 11, delayed repeated attempts using air enema failed to reduce intussusception. Clinical signs and their duration did not differ between those children without and those with air encircling the intussusceptum. CONCLUSION: In the presence of air encircling the intussusceptum in the distal small bowel on air enema, delayed repeated attempts for intussusception reduction are unlikely to succeed, and surgery is indicated.

Premature red blood cells have decreased aggregation and enhanced aggregability.

Preterm infants are highly susceptible to ischemic damage. This damage is most obvious in the brain, retina, and gastrointestinal tract. Studies focusing on the rheological properties of premature red blood cells (pRBCs) have consistently shown minimal or no RBC aggregation. Previously, measurements of pRBC aggregation kinetics indicated that specific plasma properties are responsible for the decreased RBC aggregation observed in the neonates, but that their specific RBC properties do not affect it. However, the strength of interaction in the pRBC aggregates as a function of medium composition has not been tested. In our previous research, we described clinically relevant parameters, that is, the aggregate resistance to disaggregation by flow. With the help of a cell flow property analyzer (CFA), we can monitor RBC aggregation by direct visualization of its dynamics during flow. We used the CFA to examine pRBC (from 9 premature babies) in the natural plasma and in PBS buffer supplemented with dextran (500 kDa) to distinguish between RBC intrinsic-cellular and plasma factors. pRBCs suspended in the native plasma showed minimal or no aggregation in comparison to normal adult RBC. When we transferred pRBCs from the same sample to the dextran solution, enhanced resistance to disaggregation by flow was apparent.

Pilot study of new training model for laparoscopic surgery.

The aim of this study was to evaluate whether an assessment exercise performed on a laparoscopic trainer model reliably reflects previous laparoscopic experience and can therefore be used to accurately assess laparoscopic skills in surgical trainees. Subjects were recruited from a cross-section of surgical trainees and students at the Great Ormond Street Hospital for Children and the Institute of Child Health. Subjects were required to complete a baseline laparoscopic surgical skills questionnaire and an exercise on a new laparoscopic trainer model. Nine subjects completed both the baseline questionnaire and the exercise. These subjects exhibited a wide range of previous experience in laparoscopic surgery. Subjects with higher self-assessment scores had the lowest exercise scores (i.e. better scores; P=0.003). Furthermore, the exercise score was strongly negatively correlated with the baseline number of training modalities received (P=0.007) and the laparoscopic experience score (P=0.027). The assessment exercise on a novel laparoscopic trainer was capable of differentiating between subjects with little laparoscopic experience and those with more extensive previous laparoscopic training. The correlation between the exercise score and measured baseline variables suggests that the scoring system used in this model is sensitive and specific to measuring skills relevant to laparoscopic surgery.

Warm blood cardioplegia for patients undergoing revascularization for left main coronary artery disease.

Between February 1991 and June 1992, 62 patients (50 males) underwent coronary artery bypass (CAB) operation for significant left main coronary artery disease. Age varied between 47 and 81 years. 53 patients had unstable angina, 16 had recent myocardial infarction, and 16 had heart failure. 22 patients were in functional capacity class IV (Canadian Heart Association) and 2 patients were in unstable hemodynamical condition before the operation. Intraaortic balloon pump was inserted before the operation in 3 patients. Six patients had previous CAB surgery. All the patients were operated using myocardial protection with warm blood cardioplegia, given antegradely and retrogradely in 58 and only antegradely in 4 patients. Body temperature was maintained at 30 +/- 1.8 degrees C. Number of distal anastomoses averaged 4.3 +/- 0.9. One patient underwent additional resection of a left atrial myxoma and another aortic valve replacement. LIMA (left internal mammary artery) was used to bypass the LAD in 58 (94%) patients. Early mortality was 3 cases (4.8%). Major and minor postoperative complications occurred in 17 patients. These data suggest that warm blood cardioplegia provides superior myocardial protection in patients with left main coronary artery disease.