Considerations for Antiplatelet Management of Carotid Stenting in the Setting of Mechanical Thrombectomy: A Delphi Consensus Statement

BACKGROUND AND PURPOSE

There are only few data and lack of consensus regarding antiplatelet management for carotid stent placement in the setting of endovascular stroke treatment. We aimed to develop a consensus-based algorithm for antiplatelet management in acute ischemic stroke patients undergoing endovascular treatment and simultaneous emergent carotid stent placement.

MATERIALS AND METHODS

We performed a literature search and a modified Delphi approach used Web-based questionnaires that were sent in several iterations to an international multidisciplinary panel of 19 neurointerventionalists from 7 countries. The first round included open-ended questions and formed the basis for subsequent rounds, in which closed-ended questions were used. Participants continuously received feedback on the results from previous rounds. Consensus was defined as agreement of ≥70% for binary questions and agreement of ≥50% for questions with >2 answer options. The results of the Delphi process were then summarized in a draft manuscript that was circulated among the panel members for feedback.

RESULTS

A total of 5 Delphi rounds were performed. Panel members preferred a single intravenous aspirin bolus or, in jurisdictions in which intravenous aspirin is not available, a glycoprotein IIb/IIIa receptor inhibitor as intraprocedural antiplatelet regimen and a combination therapy of oral aspirin and a P2Y12 inhibitor in the postprocedural period. There was no consensus on the role of platelet function testing in the postprocedural period.

CONCLUSIONS

More and better data on antiplatelet management for carotid stent placement in the setting of endovascular treatment are urgently needed. Panel members preferred intravenous aspirin or, alternatively, a glycoprotein IIb/IIIa receptor inhibitor as an intraprocedural antiplatelet agent, followed by a dual oral regimen of aspirin and a P2Y12 inhibitor in the postprocedural period.

Antiplatelet Management for Stent-Assisted Coiling and Flow Diversion of Ruptured Intracranial Aneurysms: A DELPHI Consensus Statement

BACKGROUND AND PURPOSE

There is a paucity of data regarding antiplatelet management strategies in the setting of stent-assisted coiling/flow diversion for ruptured intracranial aneurysms. This study aimed to identify current challenges in antiplatelet management during stent-assisted coiling/flow diversion for ruptured intracranial aneurysms and to outline possible antiplatelet management strategies.

MATERIALS AND METHODS

The modified DELPHI approach with an on-line questionnaire was sent in several iterations to an international, multidisciplinary panel of 15 neurointerventionalists. The first round consisted of open-ended questions, followed by closed-ended questions in the subsequent rounds. Responses were analyzed in an anonymous fashion and summarized in the final manuscript draft. The statement received endorsement from the World Federation of Interventional and Therapeutic Neuroradiology, the Japanese Society for Neuroendovascular Therapy, and the Chinese Neurosurgical Society.

RESULTS

Data were collected from December 9, 2019, to March 13, 2020. Panel members achieved consensus that platelet function testing may not be necessary and that antiplatelet management for stent-assisted coiling and flow diversion of ruptured intracranial aneurysms can follow the same principles. Preprocedural placement of a ventricular drain was thought to be beneficial in cases with a high risk of hydrocephalus. A periprocedural dual, intravenous, antiplatelet regimen with aspirin and a glycoprotein IIb/IIIa inhibitor was preferred as a standard approach. The panel agreed that intravenous medication can be converted to oral aspirin and an oral P2Y12 inhibitor within 24 hours after the procedure.

CONCLUSIONS

More and better data on antiplatelet management of patients with ruptured intracranial aneurysms undergoing stent-assisted coiling or flow diversion are urgently needed. Panel members in this DELPHI consensus study preferred a periprocedural dual-antiplatelet regimen with aspirin and a glycoprotein IIb/IIIa inhibitor.

Rhesus D Antigenic Determinants on Residual Red Blood Cells in Apheresis and Buffy Coat Platelet Concentrates

Background

The level of residual red blood cells (RBCs) in platelet concentrates (PCs) is of interest because of clinical concerns related to alloimmunization to RBC antigens in transfused patients. This work aims at characterizing and quantifying the levels of intact and fragmented RBCs in apheresis (AP-PCs) and buffy coat PCs (BC-PCs) to assess their potential risk for RhD antigen alloimmunization.

Methods

After staining with anti-CD41 (platelets) and anti-CD235a (RBCs) antibodies, the size and density of RhD antigen on intact and fragmented RBCs were analyzed by flow cytometry.

Results

Residual RBC counts were 29 ± 22 × 10⁶/unit in AP-PCs and 121 ± 54 × 10⁶/unit in BC-PCs, which correspond to about 3 and 11 µL of RBCs by product, respectively. RhD expression was about 4 times higher on RBC particles in AP-PCs, and these particles contribute to 66 and 75% of the total antigenic load in BC-PCs and AP-PCs, respectively.

Conclusions

Processing methods influence the quantity and nature of contaminating residual RBCs and RBC-derived particles in PCs. The estimation of residual RBCs in these blood products is generally based on measurements of intact RBCs, which might underestimate the risk for alloim-munization in transfused patients. The question of whether these RBC-derived particles can produce an immune response and, thus, should then be taken into consideration for Rh immune prophylactic treatments, remains to be clarified.

Optimization of cord blood unit sterility testing: impact of dilution, analysis delay, and inhibitory substances

BACKGROUND

Different methods are used by cord blood banks to prepare samples for sterility testing. Suboptimal methods can result in the release of contaminated products. In our organization, samples are prepared by diluting the final product in RPMI-1640 medium. In this work, we have compared our method with different approaches to verify whether optimization should be sought.

STUDY DESIGN AND METHODS

Cord blood units (n = 6 units per bacterial strain) characterized to contain inhibitory substances or not were inoculated (10 colony-forming units/mL) with Streptococcus agalactiae, Staphylococcus epidermidis, Klebsiella pneumoniae, Escherichia coli, or Bacteroides fragilis. After plasma and red blood cell removal, stem cell concentrates were diluted in RPMI-1640, thioglycollate, or the unit's plasma. These products, as well as final product, plasma, and red blood cell fractions, were held from 0 to 72 hours at 20 to 24°C before inoculation in culture bottles and detection using the BacT/ALERT 3D system.

RESULTS

Dilution of cell concentrates in RPMI-1640 allowed bacterial detection in 93.3% of noninhibitory cord blood samples after a 24-hour storage period. Thioglycollate medium better promoted bacterial growth in inhibitory cord blood samples that were held for 72 hours before testing (66.7%) compared with RPMI-1640 (45.0%). Less than 33% of all spiked plasma samples were detected by the BacT/ALERT 3D system.

CONCLUSION

Diluting cord blood samples in culture medium containing bacterial growth promoting substances is a suitable option for sterility testing, whereas the use of plasma should be proscribed, because it might lead to false-negative results. Because inhibitory substances affect bacterial growth, inoculation of culture bottles should be done rapidly after sample preparation.

Changing the 30-min Rule in Canada: The Effect of Room Temperature on Bacterial Growth in Red Blood Cells

BACKGROUND

To maintain product quality and safety, the '30-min rule' requires the discard of red blood cells (RBCs) that are exposed to uncontrolled temperatures for more than 30 min. Recent studies suggest this rule may safely be extended to a 60-min rule.

METHODS

A pool-and-split design study (N = 4) was run in parallel at Canadian Blood Services (SAGM RBCs) and Héma-Québec (AS-3 RBCs). RBCs were spiked with ∼1 colony-forming unit/ml of mesophilic and psychrophilic bacteria. Control units remained in storage at 1-6 °C for 42 days. Test 30 (T30) and T60 units were exposed to room temperature (RT) six times during storage, each time for 30 and 60 min, respectively. Bacterial proliferation was monitored.

RESULTS

Mesophilic bacteria do not proliferate in RBCs. The growth of psychrophilic bacteria is not significantly different in RBCs exposed for 30 or 60 min to RT (p < 0.05).

CONCLUSION

The study findings were the final evidence to support extension from a 30-min rule to a 60-min rule in Canada.

Pressure Infusion Cuff and Blood Warmer during Massive Transfusion: An Experimental Study About Hemolysis and Hypothermia

Background

Blood warmers were developed to reduce the risk of hypothermia associated with the infusion of cold blood products. During massive transfusion, these devices are used with compression sleeve, which induce a major stress to red blood cells. In this setting, the combination of blood warmer and compression sleeve could generate hemolysis and harm the patient. We conducted this study to compare the impact of different pressure rates on the hemolysis of packed red blood cells and on the outlet temperature when a blood warmer set at 41.5°C is used.

Methods

Pressure rates tested were 150 and 300 mmHg. Ten packed red blood cells units were provided by Héma-Québec and each unit was sequentially tested.

Results

We found no increase in hemolysis either at 150 or 300 mmHg. By cons, we found that the blood warmer was not effective at warming the red blood cells at the specified temperature. At 150 mmHg, the outlet temperature reached 37.1°C and at 300 mmHg, the temperature was 33.7°C.

Conclusion

To use a blood warmer set at 41.5°C in conjunction with a compression sleeve at 150 or 300 mmHg does not generate hemolysis. At 300 mmHg a blood warmer set at 41.5°C does not totally avoid a risk of hypothermia.

Retrospective Attention Gates Discrete Conscious Access to Past Sensory Stimuli

Cueing attention after the disappearance of visual stimuli biases which items will be remembered best. This observation has historically been attributed to the influence of attention on memory as opposed to subjective visual experience. We recently challenged this view by showing that cueing attention after the stimulus can improve the perception of a single Gabor patch at threshold levels of contrast. Here, we test whether this retro-perception actually increases the frequency of consciously perceiving the stimulus, or simply allows for a more precise recall of its features. We used retro-cues in an orientation-matching task and performed mixture-model analysis to independently estimate the proportion of guesses and the precision of non-guess responses. We find that the improvements in performance conferred by retrospective attention are overwhelmingly determined by a reduction in the proportion of guesses, providing strong evidence that attracting attention to the target’s location after its disappearance increases the likelihood of perceiving it consciously.

Incidence of hypotension and acute hypotensive transfusion reactions following platelet concentrate transfusions

BACKGROUND AND OBJECTIVES

Platelet concentrates (PCs) are associated with transfusion reactions involving hypotension, particularly bradykinin-mediated acute hypotensive transfusion reactions. This study aims to determine the incidence of hypotensive events and more specifically acute hypotensive transfusion reaction associated with PC transfusions. We also sought to ascertain whether these reactions are associated with elevated bradykinin levels.

MATERIALS AND METHODS

This is a prospective descriptive study of PCs administered at Sainte-Justine Hospital over 28 months. All PCs administered during this period were screened for hypotension through review of all transfusion-associated reaction reports (TARRs) sent to the blood bank. All residual PC bags were returned to the blood bank. TARRs associated with hypotension were reviewed by adjudicators that established the imputability of the PC transfusion to the reaction. Bradykinin levels were sampled in the first 168 PC bags returned to the blood bank. Levels were compared between PCs associated with hypotension and control PCs not associated with hypotension.

RESULTS

A total of 3672 PC bags were returned to the blood bank; 25 PCs were associated with hypotension. Adjudicators ascertained that five hypotensive events were imputable to PCs of which one was an acute hypotensive transfusion reaction (incidence: 0·03%). Bradykinin level in the latter PC was 10 pg/ml, whereas levels were 226·2 ± 1252 pg/ml in the 143 control PCs.

CONCLUSION

Our results show a low incidence of hypotension after PC transfusion. We identified only one acute hypotensive transfusion reaction. No correlation between bradykinin level and the occurrence of acute hypotensive reactions could be observed given that only one event was identified.

How does the extraction of local and global auditory regularities vary with context?

How does the human brain extract regularities from its environment? There is evidence that short range or ‘local’ regularities (within seconds) are automatically detected by the brain while long range or ‘global’ regularities (over tens of seconds or more) require conscious awareness. In the present experiment, we asked whether participants' attention was needed to acquire such auditory regularities, to detect their violation or both. We designed a paradigm in which participants listened to predictable sounds. Subjects could be distracted by a visual task at two moments: when they were first exposed to a regularity or when they detected violations of this regularity. MEG recordings revealed that early brain responses (100–130 ms) to violations of short range regularities were unaffected by visual distraction and driven essentially by local transitional probabilities. Based on global workspace theory and prior results, we expected that visual distraction would eliminate the long range global effect, but unexpectedly, we found the contrary, i.e. late brain responses (300–600 ms) to violations of long range regularities on audio-visual trials but not on auditory only trials. Further analyses showed that, in fact, visual distraction was incomplete and that auditory and visual stimuli interfered in both directions. Our results show that conscious, attentive subjects can learn the long range dependencies present in auditory stimuli even while performing a visual task on synchronous visual stimuli. Furthermore, they acquire a complex regularity and end up making different predictions for the very same stimulus depending on the context (i.e. absence or presence of visual stimuli). These results suggest that while short-range regularity detection is driven by local transitional probabilities between stimuli, the human brain detects and stores long-range regularities in a highly flexible, context dependent manner.

Antimicrobial activity in cord blood units: occurrence and levels of antibiotics

BACKGROUND

Antibiotic prophylaxis treatment at delivery is highly recommended for reducing the risk of infection for mothers positive for group B streptococcus. It is therefore expected that some cord blood (CB) products will contain residual antibiotics. This study aimed to determine the incidence and level of β-lactam antibiotics in CB products.

STUDY DESIGN AND METHODS

The antimicrobial activity of 60 CB plasma by-products was evaluated using disk diffusion assays on 10 bacteria species. Plasma samples showing antimicrobial activity were either treated with β-lactamase enzyme to inhibit β-lactam antibiotics or heated to 56°C for 30 minutes to inhibit complement proteins. β-Lactam antibiotic concentrations were determined by comparison with a standard curve obtained with known concentrations of antibiotics.

RESULTS

Antimicrobial activity against mostly Gram-positive microorganisms was observed in 33% of CB units. The β-lactamase enzyme abolished the antimicrobial activity in the majority of these CB products. Up to 5 μg/mL penicillin and 14 μg/mL ampicillin were measured in these products.

CONCLUSION

Approximately one-third of CB products contain significant amounts of plasma with residual antibiotics, which can affect the survival and growth of bacterial contaminants when performing the sterility test and potentially lead to false-negative results. Additional work is required to better understand whether residual antibiotics in CB affect penicillin-allergic patients.

Quality and safety of red blood cells stored in two additive solutions subjected to multiple room temperature exposures

BACKGROUND AND OBJECTIVES

Many international standards state that red blood cell (RBC) products should be discarded if left out of controlled temperature storage for longer than 30 min to reduce the risk of bacterial growth and RBC loss of viability. This study aimed to verify whether repeated short-time exposures to room temperature (RT) influence RBCs quality and bacterial proliferation.

MATERIALS AND METHODS

Saline-adenine-glucose-mannitol (SAGM) and AS-3 RBC units were split and exposed to RT for 30 or 60 min on day 2, 7, 14, 21, and 42 of storage while reference units remained stored at 1-6°C. Red blood cell in vitro quality parameters were evaluated after each exposure. In a second experiment, SAGM and AS-3 RBC units were split and inoculated with Staphylococcus epidermidis (5 CFU/ml), Serratia marcescens (1 CFU/ml), and Serratia liquefaciens (1 CFU/ml). Reference units remained in storage while test units were exposed as described previously. Bacterial concentrations were investigated after each exposure.

RESULTS

No differences were noticed between reference and test units in any of the in vitro parameters investigated. S. epidermidis did not grow in either reference or exposed RBCs. While S. marcescens did not grow in AS-3, bacterial growth was observed in RT-exposed SAGM RBCs on day 42. Similar growth was obtained for S. liquefaciens in the two additive solutions for both reference and test units.

CONCLUSION

Short-time exposures to RT do not affect RBC quality and do not significantly influence bacterial growth. An expansion of the '30-minute' rule to 60 min should be considered by regulatory agencies.

[Chikungunya outbreak on Reunion Island in 2005/2006: role of hospital physicians in raising alert]

The epidemic of chikungunya (CHIK) that swept through Reunion Island from late 2005 to mid 2006 affected 38.2% of the population, i.e., 300000 people. Although this outbreak took place in a French overseas department with high public health standards, failure to anticipate a large-scale epidemic associated with unprecedented severity and unexpectedly high mortality led to a major public health crisis. The purpose of this report is to provide a complete account of the experience of hospital intensive care physicians in addressing problems ranging from discovery of severe forms to management of a major health crisis. This report underlines the role of the head hospital physician and the necessity of mutual trust and collaboration with supervisory authorities.

Heart valve allograft decontamination with antibiotics: impact of the temperature of incubation on efficacy

Heart valve allografts are typically processed at 4°C in North America, including the step of antibiotic decontamination. In our own experience with heart valve banking, we often observe persistent positive cultures following decontamination at wet ice temperature. We hypothesized that warmer temperatures of incubation might increase the efficacy of the decontamination procedure. In a first series of experiments, 12 different bacterial species were grown overnight, frozen in standardized aliquots and used directly to inoculate antibiotic cocktail aliquots at 10⁵ colony-forming units (CFU)/ml. The antibiotic cocktail contains vancomycin (50 μg/ml), gentamicin (80 μg/ml) and cefoxitin (240 μg/ml) in Dulbecco's Modified Eagle's Medium. Inoculated aliquots were incubated at 4, 22 and 37°C and CFUs were determined at regular intervals up to 24 h post-inoculation. In a second set of experiments, 10 heart valves were spiked with 5000 CFU/ml and incubated with antibiotics at 4 and 37°C for 24 h. The final rinse solutions of these heart valves were filtered and tested for bacterial growth. After 24 h of incubation, CFUs of all 12 bacterial species were reduced by a factor of only one to two logs at 4°C whereas log reductions of 3.7 and 5.0 or higher were obtained at 22 and 37°C, respectively. Most microorganisms, including Staphylococcus epidermidis, Lactococcus lactis lactis and Propionibacterium acnes survived well the 24-h antibiotic treatment at 4°C (< 1 Log reduction). All 10 heart valves that were spiked with microorganisms had positive final rinse solutions after antibiotic soaking at 4°C, whereas 8 out of 10 cultures were negative when antibiotic decontamination was done at 37°C. These experiments show that a wet ice temperature greatly reduces the efficacy of the allograft decontamination process as microorganisms survived well to a 24-h 4°C antibiotic treatment. This could explain the high rate of positive post-processing cultures obtained with our routine tissue decontamination procedure. Increasing the decontamination temperature from 4 to 37°C may significantly reduce the incidence of post-disinfection bacterial contamination of heart valves.

[Outbreak of influenza A(H1N1)/2009: description of cases and crisis management in a ICU in Reunion Island]

OBJECTIVES

to describe the characteristics, treatment and outcome of critically ill patients with influenza A(H1N1) infection at St Pierre Hospital in Reunion Island during the 2009 outbreak, as well as the measures of care reorganization implemented to face them.

PATIENTS AND METHODS

prospective observational study of probable and confirmed cases of influenza A (H1N1)/2009 infection concerning hospitalized patients in a polyvalent intensive care unit (ICU).

RESULTS

thirteen patients have been included between August and September 2009. Three (23 %) didn't have any medical history. The median age was 42 [22-69]. Eleven have required pulmonary ventilation for 10.3 days (± 8). Three (23 %) have developed an ARDS. Three patients (23 %) died. To cope with the influx of cases and considering our situation of geographic isolation, it has been needed to totally rework the organization of care: set-up of a specific welcoming channel, division into sectors of the department, opening of additional beds, new on-duty assignment, inter and intra hospital cooperation.

CONCLUSION

reunion Island has been an experimental lab of crisis management during the H1N1/2009 epidemic, several months ahead of the mother country. To anticipate the reorganization of care in intensive care units during an outbreak period, particularly in small units or units isolated like ours, looks to us a must so to quietly face a sharp influx of patients.

Allergic transfusion reactions from blood components donated by IgA-deficient donors with and without anti-IgA: a comparative retrospective study

BACKGROUND AND OBJECTIVES

IgA deficiency is common (1/500) and up to 40% of affected individuals will develop anti-IgA. A few studies suggested that passive transfusion of anti-IgA was not associated with an increased risk of allergic reactions. This study was designed to assess the safety of transfusing blood components containing anti-IgA.

MATERIALS AND METHODS

IgA-deficient blood donors with and without anti-IgA were identified from Héma-Québec's (HQ) computerized database. IgA deficiency was confirmed by an ELISA method and the presence of anti-IgA by a passive hemagglutination assay. Blood donations from IgA-deficient donors issued to hospitals between March 1999 and December 2004 were retrieved. Medical charts of recipients were reviewed for the occurrence of a suspected transfusion reaction. Presence and nature of transfusion reactions were assessed blindly by an adjudicating committee.

RESULTS

A total of 323 IgA-deficient blood products were issued by HQ to 55 hospitals. Of these, 48 agreed to participate [315 blood products (97.5%)]. A total of 272 products were transfused: 174 contained anti-IgA, and 98 did not. Only two minor allergic reactions occurred in each group. Incidence of allergic reactions was 1.15% in the anti-IgA group and 2.04% in the group without anti-IgA (P = 0.91). There was no anaphylactic reaction in either group.

CONCLUSIONS

This study indicates that the proportion of allergic reactions does not appear to be greater in recipients of blood components containing anti-IgA compared to recipients of non-anti-IgA-containing components. Allowing donations from IgA-deficient donors with anti-IgA may therefore be contemplated.

Length of storage and in vitro immunomodulation induced by prestorage leukoreduced red blood cells

BACKGROUND

The relationship between length of storage of red blood cell (RBC) units and biochemical changes has been well studied, but little is known about the progression of cellular immunomodulative properties in blood recipients. This study aims to quantify in vitro T-cell activation and cytokine release by white blood cells, after incubation with supernatants from leukoreduced RBCs.

STUDY DESIGN AND METHODS

Whole blood cultures were incubated with supernatant from five leukoreduced RBC units stored for 1, 6, 10, 15, 24, and 42 days. Supernatant-induced T-cell activation was evaluated by quantifying CD25 expression. Supernatant-induced cytokine production was determined by measuring interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha levels.

RESULTS

No cytokines were detected in RBC supernatants even after 42 days of storage. However, IL-6 levels in whole blood culture increased significantly when incubated with supernatant from RBC units stored for 1, 6, and 15 days, by factors of 1.7 +/- 0.3, 1.7 +/- 0.3, and 1.4 +/- 0.3, respectively. TNF-alpha levels were significantly decreased on Days 24 and 42 of storage by factors of 0.50 +/- 0.42 and 0.33 +/- 0.21, respectively. IL-10 levels were significantly increased on Days 1 and 42 of storage by factors of 2.3 +/- 1.3 and 3.2 +/- 2.8, respectively. After an initial increase in IL-6 and TNF-alpha production, there was a significant linear decrease in their levels measured from units stored for longer times. No significant changes in CD25 expression were observed over time.

CONCLUSION

Although no cytokines were measured in the supernatants from leukoreduced RBCs, these supernatants exhibited variable immunomodulatory effects related to their length of storage.

Influence of Feeding Paradigm in Rats on Temporal Pattern of: II. Brain Serotoninergic and Catecholaminergic Systems

The relationship between the feeding paradigm (single diet versus food selection) and central idoleamines and catecholamines was studied. Temporal patterns of the brain parameters in response to presentation of a single diet of fixed composition (20% casein) or a choice between two isocaloric diets (0% and 60% casein) for 2 weeks under 8-h feeding cycles during the dark phase were measured in adult Sprague-Dawley rats. Groups of animals were then killed at the beginning and at 2-h intervals throughout the feeding period. The distribution and the temporal pattern of variation of the serotoninergic and the catecholaminergic parameters studied were significantly affected by the diet paradigms used. A different neurochemical equilibrium was observed before food intake and was characterized by a central serotoninergic predominance in subjects having a dietary selection experience but a central catecholaminergic predominance in animals adapted to a single diet. Hypothalamic and extrahypothalamic serotoninergic and catecholaminergic systems were found to intervene in an interdependent way, sometimes antagonistic according to the feeding paradigm and the related temporal changes in energy intake and macronutrient selection. These results suggest that central serotoninergic and catecholaminergic systems are influenced by the diet paradigm and display characteristic patterns of temporal variations during the feeding cycle. The feeding paradigm, per se, should then be considered as a potential synchronizer of central biological rhythms of monoamines, which in turn may affect food intake and appetite for macronutrients.

Characterization of mononuclear cells remaining in the leukoreduction system chambers of apheresis instruments after routine platelet collection: a new source of viable human blood cells

BACKGROUND

The yield of white blood cells (WBCs) extracted from whole-blood leukoreduction filters can be affected by the storage conditions and delay before filtration. Platelets (PLTs) collected with apheresis instruments (Trima Accel, Gambro BCT) are leukoreduced during the procedure on a fluidized particle bed in a leukoreduction chamber (LRS chamber). In this report, the residual cell content of these LRS chambers was characterized to determine whether it would be a valuable source of viable human blood cells.

STUDY DESIGN AND METHODS

The content of LRS chambers was eluted by gravity, and peripheral blood mononuclear cells (PBMNCs) were purified on a Ficoll-Paque gradient. Analyses were performed before and after freezing. Proportions of CD3+, CD14+, CD16+, CD19+, CD34+, and CD45+ cells were determined by flow cytometry. The frequency of T cells expressing CD4, CD8, and CD27 and of B cells expressing immunoglobulin G (IgG), IgM, and CD27 was also determined.

RESULTS

LRS chambers held approximately 10(9) CD45+ cells representing the normal proportions of CD3+, CD14+, CD16+, and CD19+ cell populations of PBMNCs. A small fraction of these CD45+ cells were CD34+CD38+ cells (0.3 +/- 0.2%). The viability of these cells, measured before and after freezing, was more than 95 percent.

CONCLUSION

The residual cell content of Trima Accel LRS chambers recovered after PLT collection is a good source of viable monocytes and lymphocytes. These PBMNCs, containing CD3+, CD14+, CD16+, CD19+, and CD34+ cells can be frozen to prepare cell banks, which opens new avenues for utilization in several physiologic studies or even in cellular therapy applications.

Dietary protein level alters gentamicin-induced nephrotoxicity in rats

Aminoglycosides (AG) such as gentamicin are antimicrobial drugs widely used in the hospital setting due to their efficacy in the treatment of severe gram-negative bacterial infections. However, all AG have the potential to cause nephrotoxicity. Two studies have been conducted (1) to assess the protein level of a diet that would give the best renal outcome with gentamicin administration, and (2) to get a better idea about the rhythms of food ingestion associated with the different protein levels. Adult female Sprague-Dawley rats fully adapted to a standard chow diet, the standard chow with 20% or 55% added casein were chronically treated for 10 days with a nephrotoxic dose of gentamicin sulfate (40 mg/kg/day, i.p.) or a saline solution. Food ingestion patterns of rats were recorded every hour using a Diet Scan system and gentamicin nephrotoxicity indices were measured. The second study used rats that were fed the same diets and given a sham injection. Corticosterone was assayed to quantify the stress of the animals. Results showed that chronic gentamicin treatment leads to a decrease in food intake and flattening of the rhythms of food ingestion. Also, chow feeding and the 20% casein diet were found to be more protective against gentamicin-induced nephrotoxicity than the 55% casein diet. Therefore, while a protein-rich diet can be protective against gentamicin-induced nephrotoxicity, the present study demonstrates that a diet too high in protein might rather be harmful to the kidneys.

Generation of kinins during preparation and storage of whole blood?derived platelet concentrates

BACKGROUND

Leukoreduction of platelet (PLT) concentrates (PCs) may be associated with hypotension in recipients, and a role for bradykinin (BK)-related peptides has been proposed for this side effect.

STUDY DESIGN AND METHODS

The concentration of BK and one of its vasoactive metabolites, des-arginine(9)-BK (des-Arg(9)-BK), was measured in a large number of PCs as a function of leukoreduction and storage duration with specific enzyme immunoassays and complementary techniques.

RESULTS

On Day 0 of storage, kinins were detected in leukoreduced and unfiltered PCs at a concentration lower than 100 pg per mL. During storage, both kinin levels peaked on Day 5 of storage, with a concentration higher than 1 ng per mL in 22 percent of PCs whether filtered on Day 0 or not. Physicochemical and pharmacologic characterizations of immunoreactive kinins confirm their nature. In vitro activation of the contact system of the corresponding PLT-poor plasma showed that a high kinin concentration on Day 5 of the storage corresponded with a low kinin-forming capacity of plasma. On Day 7, BK was no longer elevated presumably due to its degradation and the depletion of kinin-forming capacity of the plasma in stored PCs. The activities of metallopeptidases that metabolize BK-related peptides in plasma from PCs were at levels similar to those recorded in the plasma of a normal reference population and were unaffected by storage.

CONCLUSION

Storage of PCs contributes to the hydrolysis of high-molecular-weight kininogen and generation of pharmacologically relevant BK levels that might pose a hazard in susceptible patients.

Establishment of an immunoglobulin�A?deficient blood donor registry with a simple in-house screening enzyme-linked immunosorbent assay

BACKGROUND

Transfusion of blood products to immunoglobulin A (IgA)-deficient patients who have developed IgA antibodies can result in serious adverse reactions. To prepare compatible blood components for these patients, blood centers usually maintain a list of IgA-deficient blood donors. An in-house enzyme-linked immunosorbent assay (ELISA) was used to identify new IgA-deficient blood donors.

STUDY DESIGN AND METHODS

An in-house ELISA was used to screen blood samples. IgA-deficient samples, defined as an IgA level below 0.05 mg per dL, were sent to the American Red Cross for confirmatory testing.

RESULTS

Seventy-three confirmed IgA-deficient blood donors were identified among 38,759 screened blood donor samples (frequency, 1:531). IgA antibodies were found in 39 of these 73 blood donors (53%), although only 9 donors had a history of adult IgA exposure (transfusion or pregnancy).

CONCLUSIONS

With a simple in-house ELISA, 73 blood donors were identified as IgA-deficient. From this number, 34 donors, without detectable anti-IgA in their plasma, were added to our IgA-deficient blood donor panel to maximize the management of our inventory of IgA-deficient frozen blood components.

Characterization of blood components prepared from whole-blood donations after a 24-hour hold with the platelet-rich plasma method

BACKGROUND

The preparation of platelet (PLT) concentrates (PCs) from PLT-rich plasma (PRP) requires that whole blood (WB) be processed within 8 hours of collection. Increasing WB storage time to 24 hours would be logistically attractive. This study compares the in vitro quality of blood components prepared from WB stored for 8 and 24 hours at room temperature before processing with the PRP method.

STUDY DESIGN AND METHODS

WB units were collected from ABO-matched blood donors. To reduce individual variations, paired donations were drawn in parallel, pooled, and split back in the collection bag. One unit was held for 6 to 8 hours and the other for 22 to 24 hours at 20 to 24 degrees C. Prestorage leukoreduced components were prepared with the PRP as intermediate product and analyzed during storage.

RESULTS

RBC units prepared after an 8- or 24-hour hold were comparable in terms of hemolysis, sodium, pH, and ATP levels. RBC 2,3- diphosphoglycerate (2,3-DPG) was significantly lower in RBCs prepared from 24-hour hold donations immediately after processing but not after 20 days of storage. Residual white blood cells were approximately fivefold higher (p < 0.05) in 24-hour RBC units. For PCs, measurements for glucose, ATP, lactate, pH, extent of shape change, hypotonic shock response, and CD62p activation were similar. No differences were observed in the von Willebrand factor, factor (F)V, FVIII, and fibrinogen content of fresh-frozen plasma.

CONCLUSIONS

The decrease in FVIII and RBC 2,3-DPG can be acceptable as a compromise to improve blood component logistics, but leukoreduction efficiency must be improved before considering the adoption of an overnight storage of WB before PRP processing.

Effect of sibutramine on macronutrient selection in male and female rats

Sibutramine, a serotonin-noradrenaline reuptake inhibitor (SNRI), has been shown to be a safe and effective weight-loss drug. The purpose of the present study was to examine whether sibutramine has an effect on macronutrient selection in both female and male rats in addition to total food intake. Wistar rats of both sexes were divided into three groups, and each group was offered a different set of three sensorily contrasting macronutrient-specific diets, each set including carbohydrate-, protein-, and fat-rich diets. Sibutramine (10 mg/kg) was shown to consistently decrease carbohydrate and fat intake at all data points regardless of gender and diet. Intake of carbohydrate differed between male and female rats at 2 h post administration with 2.5 and 5 mg/kg of sibutramine. The effect of sibutramine on protein intake was diet- and gender-specific. All doses of sibutramine decreased total food intake regardless of gender and diet group beginning at 6 h post administration. In conclusion, sibutramine affected macronutrient selection and emphasis on dietary recommendations, as well as appropriate dosage according to gender should be considered during therapy.

Effect of melatonin on total food intake and macronutrient choice in rats

Melatonin, a hormone secreted in a rhythmic manner over 24 h mainly by the pineal gland, is used to alleviate the symptoms of jetlag and treat sleeping problems. The objective of the present study was to examine the effects of a 7-h phase-shift from the natural peak of melatonin secretion on total food intake and macronutrient selection. Forty-eight adult Wistar rats of both sexes were divided in three dietary groups, each group offered a simultaneous and different choice of a carbohydrate- and a protein-rich diet. Macronutrient intakes following intraperitoneal administration of four doses of melatonin (3000, 6000, 10000 and 15000 pg/ml blood) at dark onset were examined. Melatonin increased short- (4 h postinjection) and long-term (12 h postinjection) nocturnal total food intake in both male and female rats, mainly with the two highest doses. This effect of melatonin was mainly due to a short-term increase of intake across all carbohydrate-rich diet preparations (dextrin/cornstarch, cornstarch, and sucrose/cornstarch) and across genders. This consistent effect of melatonin on the intake of carbohydrate-rich diets with contrasting sensory attributes rules out the possibility that melatonin acts on sensorymotor pathways, thus suggesting that melatonin's effect on food intake is controlled by the carbohydrate content of the diet. In contrast, melatonin could be affecting some sensory or motor processes peculiar to the ingestion of protein since it increased protein-rich diet intake inconsistently across the various preparations (casein, soy isolate, and egg protein) as well as genders. This evidence supports the view that melatonin acts as a time indicator, reinforcing the animals with a "night cue", and favors predominant carbohydrate intake normally occurring at the beginning of the activity period.

The induction of low nocturnal secretion of melatonin caused by reverse feeding rhythms depends on availability of macronutrient diets

The present study investigated the effect of single chow diet and two-way dietary choice between a protein-rich and a carbohydrate-rich diet ingested during free access or daytime access (08.00-16.00 h) on the rhythms of ingestion and on nocturnal levels of serum melatonin and pineal N-acetyltransferase activity in rats. Animals with free access to the single or the choice diets displayed a circadian rhythmicity of total food intake with peaks at the beginning, the middle and the end of the dark phase. Rats fed the dietary choice displayed a preference for carbohydrate at the beginning, and a preference for protein at the middle and the end of the dark phase. Under daytime feeding access, both dietary conditions resulted in only one peak of total intake at the beginning of the access period. Rats fed the choice diets on the daytime feeding schedule initially preferred carbohydrate to protein but this preference disappeared subsequently. Nocturnal peaks of serum melatonin and pineal NAT activity were lower with daytime access to dietary choice compared to ad libitum access. The results suggest that in a two-way selection of macronutrients, feeding cycle can directly act on the rhythms expressed within the pineal gland.

Dietary composition alters gentamicin-induced nephrotoxicity in rats

Previous studies have shown temporal variations in gentamicin-induced renal toxicity characterized by a peak when administered during the resting period and a trough during the active period. This time-dependent toxicity was also altered according to the macronutrient composition of dietary regimens offered to female rats. In the present study, adult female Sprague-Dawley rats were adapted to semipurified isocaloric diets containing 20% casein or soy-protein (10% fat each) or to a standard chow diet (18.1% mixed proteins; 4.5% fat). The animals were then chronically treated for 10 days with a nephrotoxic dose of gentamicin sulfate (40 mg/kg/day ip) or a saline solution administered in the middle of their resting period (1200 h) or in the middle of their activity period (0000 h). Body weights of rats injected in the middle of their resting period decreased over the last 6 days of gentamicin treatment. Total 12-h light and 12-h dark food intakes were decreased in gentamicin-treated rats. Rats fed the standard chow diet had significantly lower corticocellular regeneration, serum creatinine and blood urea nitrogen compared to those fed the casein- and soy-containing diets. The present study demonstrates that chronic gentamicin-induced renal toxicity varies temporally according to the time of administration and that a mixed protein diet containing a lower fat level can protect against gentamicin-induced nephrotoxicity.

Biomechanics and neuropathology of adult and paediatric head injury

The objective of this study was to understand the biomechanics in age-related primary traumatic brain injuries (TBI) causing initial severity and secondary progressive damage and to develop strategy reducing TBI outcome variability using biomechanical reconstruction to identify types of causal mechanisms prior to clinical trials of neuro-protective treatment. The methods included the explanation of TBI biomechanics and physiopathological mechanisms from dual perspectives of neurosurgery and biomechanical engineering. Scaling of tolerances for skull failure and brain injuries in infants, children and adults are developed. Diagnostic assumptions without biomechanical considerations are critiqued. Methods for retrospective TBI reconstruction for prevention are summarized. Mechanisms of TBI are based on the differences between the mechanical properties of the head and neck related to age. Skull fracture levels correlate with increasing cranial bone thickness and in the development of the cranial sutures in infants and in adults. Head injury tolerance levels at three age categories for cerebral concussion, skull fracture and three grades of diffuse axonal injuries (DAI) are presented. Brain mass correlates inversely for TBI caused by angular head motions and locations of injurious stresses are predictable by centripetal theory. Improved quantitative diagnosis of TBI type and severity levels depend primarily on age and biomechanical mechanisms. Reconstruction of the biomechanics is feasible and enables quantitative stratification of TBI severity. Experimental treatment has succeeded in preventing progressive damage in animal TBI models. In humans this has failed, because the animal model received biomechanically controlled TBI and humans did not. Clinical similarities of human TBI patients do not necessarily predict equivalent biomechanics because such trauma can be produced in various ways. We recommend 'reverse engineering' for in-depth reconstruction of the TBI injury mechanism for qualitative diagnoses and reduction of outcome variability.

Food access schedule and diet composition alter rhythmicity of serum melatonin and pineal NAT activity

This study investigated the effect of dietary composition and food access schedule on the rhythmicity of serum melatonin and pineal N-acetyltransferase (NAT) activity. Wistar rats maintained on a 12:12 h light-dark cycle were assigned to two dietary groups: a group fed rat chow and a group fed a choice between a protein-rich and a carbohydrate-rich diet. Each dietary group was further divided based on feeding schedule, with food available between 0800 and 1600 h or ad lib access to food. Regardless of dietary condition, total food and carbohydrate intake of rats having free access to food was higher than under the restricted food access schedule. Protein intake of rats fed the dietary choice was lower with the restricted access than in the free access. In rats fed the dietary choice, melatonin levels and NAT activity were significantly decreased with restricted access compared to free access. Such results were not found in rats offered restricted chow. This study suggests that the rhythms of melatonin secretion and NAT activity can be altered by dietary composition.