Development of a portable blood salvage and autotransfusion technology to enhance survivability of personnel requiring major medical interventions in austere or military environments

Introduction

Uncontrolled haemorrhage is the leading cause of death on the battlefield, and two-thirds of these deaths result from non-compressible haemorrhage. Blood salvage and autotransfusion represent an alternative to conventional blood transfusion techniques for austere environments, potentially providing blood to the casualty at point of injury. The aim of this paper is to describe the design, development and initial proof-of-concept testing of a portable blood salvage and autotransfusion technology to enhance survivability of personnel requiring major medical interventions in austere or military environments.

Method

A manually operable, dual-headed pump was developed that removes blood from site of injury to a collection reservoir (upper pump) and back to casualty (lower pump). Theoretical flow rate calculations determined pump configuration and a three-dimensionally printed peristaltic pump was manufactured. Flow rates were tested with fresh bovine blood under laboratory conditions representative of the predicted clinical environment.

Results

Mathematical modelling suggested flow rates of 3.6 L/min and 0.57 L/min for upper and lower pumps. Using fresh bovine blood, flow rates produced were 2.67 L/min and 0.43 L/min. To mimic expected battlefield conditions, upper suction pump flow rate was calculated using a blood/air mixture.

Conclusion

The authors believe that this technology can potentially enhance survivability for casualties in austere and deployed military settings through autotransfusion and cell concentration. It reduces negative effects of blood donation on the conventional donor pool, and potentially negates the logistical constraints associated with allogenic transfusions.

Development of a diagnostic sensor for measuring blood cell concentrations during haemoconcentration

Background:

HemoSep^® is a commercial ultrafiltration and haemoconcentration device for the concentration of residual bypass blood following surgery. This technology is capable of reducing blood loss in cardiac and other types of “clean site” procedures, including paediatric surgery. Clinical feedback suggested that the device would be enhanced by including a sensor technology capable of discerning the concentration level of the processed blood product. We sought to develop a novel sensor that can, using light absorption, give an accurate estimate of packed cell volume (PCV).

Materials and methods:

A sensor-housing unit was 3D printed and the factors influencing the sensor’s effectiveness – supply voltage, sensitivity and emitter intensity - were optimised. We developed a smart system, using comparator circuitry capable of visually informing the user when adequate PCV levels (⩾35%) are attained by HemoSep^® blood processing, which ultimately indicates that the blood is ready for autotransfusion.

Results:

Our data demonstrated that the device was capable of identifying blood concentration at and beyond the 35% PCV level. The device was found to be 100% accurate at identifying concentration levels of 35% from a starting level of 20%.

Discussion:

The sensory capability was integrated into HemoSep’s^® current device and is designed to enhance the user’s clinical experience and to optimise the benefits of HemoSep^® therapy. The present study focused on laboratory studies using bovine blood. Further studies are now planned in the clinical setting to confirm the efficacy of the device.

Detection of ischemic penumbra using combined perfusion and T2* oxygen challenge imaging

Background

Acute ischemic stroke is common and disabling, but there remains a paucity of acute treatment options and available treatment (thrombolysis) is underutilized. Advanced brain imaging, designed to identify viable hypoperfused tissue (penumbra), could target treatment to a wider population. Existing magnetic resonance imaging and computed tomography-based technologies are not widely used pending validation in ongoing clinical trials. T2* oxygen challenge magnetic resonance imaging, by providing a more direct readout of tissue viability, has the potential to identify more patients likely to benefit from thrombolysis – irrespective of time from stroke onset – and patients within and beyond the 4·5 h thrombolysis treatment window who are unlikely to benefit and are at an increased risk of hemorrhage.

Aims

This study employs serial multimodal imaging and voxel-based analysis to develop optimal data processing for T2* oxygen challenge penumbra assessment. Tissue in the ischemic hemisphere is compartmentalized into penumbra, ischemic core, or normal using T2* oxygen challenge (single threshold) or T2* oxygen challenge plus cerebral blood flow (dual threshold) data. Penumbra defined by perfusion imaging/apparent diffusion coefficient mismatch (dual threshold) is included for comparison.

Methods

Permanent middle cerebral artery occlusion was induced in male Sprague-Dawley rats (n = 6) prior to serial multimodal imaging: T2* oxygen challenge, diffusion-weighted and perfusion imaging (cerebral blood flow using arterial spin labeling).

Results

Across the different methods evaluated, T2* oxygen challenge combined with perfusion imaging most closely predicted 24 h infarct volume. Penumbra volume declined from one to four-hours post-stroke: mean ± SD, 77 ± 44 to 49 ± 37 mm³ (single T2* oxygen challenge-based threshold); 55 ± 41 to 37 ± 12 mm³ (dual T2* oxygen challenge/cerebral blood flow); 84 ± 64 to 42 ± 18 mm³ (dual cerebral blood flow/apparent diffusion coefficient), as ischemic core grew: 155 ± 37 to 211 ± 36 mm³ (single apparent diffusion coefficient threshold); 178 ± 56 to 205 ± 33 mm³ (dual T2* oxygen challenge/cerebral blood flow); 139 ± 30 to 168 ± 38 mm³ (dual cerebral blood flow/apparent diffusion coefficient). There was evidence of further lesion growth beyond four-hours (T2-defined edema-corrected infarct, 231 ± 19 mm³).

Conclusions

In conclusion, T2* oxygen challenge combined with perfusion imaging has advantages over alternative magnetic resonance imaging techniques for penumbra detection by providing serial assessment of available penumbra based on tissue viability.

Stroke penumbra defined by an MRI-based oxygen challenge technique: 1. Validation using [14C]2-deoxyglucose autoradiography

Accurate identification of ischemic penumbra will improve stroke patient selection for reperfusion therapies and clinical trials. Current magnetic resonance imaging (MRI) techniques have limitations and lack validation. Oxygen challenge T(2)(*) MRI (T(2)(*) OC) uses oxygen as a biotracer to detect tissue metabolism, with penumbra displaying the greatest T(2)(*) signal change during OC. [(14)C]2-deoxyglucose (2-DG) autoradiography was combined with T(2)(*) OC to determine metabolic status of T(2)(*)-defined penumbra. Permanent middle cerebral artery occlusion was induced in anesthetized male Sprague-Dawley rats (n=6). Ischemic injury and perfusion deficit were determined by diffusion- and perfusion-weighted imaging, respectively. At 147 ± 32 minutes after stroke, T(2)(*) signal change was measured during a 5-minute 100% OC, immediately followed by 125 μCi/kg 2-DG, intravenously. Magnetic resonance images were coregistered with the corresponding autoradiograms. Regions of interest were located within ischemic core, T(2)(*)-defined penumbra, equivalent contralateral structures, and a region of hyperglycolysis. A T(2)(*) signal increase of 9.22% ± 3.9% (mean ± s.d.) was recorded in presumed penumbra, which displayed local cerebral glucose utilization values equivalent to contralateral cortex. T(2)(*) signal change was negligible in ischemic core, 3.2% ± 0.78% in contralateral regions, and 1.41% ± 0.62% in hyperglycolytic tissue, located outside OC-defined penumbra and within the diffusion abnormality. The results support the utility of OC-MRI to detect viable penumbral tissue following stroke.

The in vitro PDT efficacy of a novel metallophthalocyanine (MPc) derivative and established 5-ALA photosensitizing dyes against human metastatic melanoma cells

BACKGROUND AND OBJECTIVE

Numerous worldwide clinical trials have shown that photodynamic therapy (PDT) represents an effective and safe modality for various skin disorders, but little research has been done in terms of its effect on malignant melanomas (MM). Thus, the aim of this study was to compare the effect of both established porphyrin photosensitizer 5-aminolevulinic acid (5-ALA) and novel metallophthalocyanine (MPc) photosensitizer on human metastatic skin cells which produce a MM.

MATERIALS AND METHODS

The cellular responses following PDT were assessed using changes in cell morphology, cell viability, cytotoxicity, apoptosis, and proliferation.

RESULTS

Findings reported that in vitro human MM cell line A375 (EACC no: 88113005) are highly sensitive to growth inhibition and apoptosis induction by the cytotoxic side-effects induced by MPc and 5-ALA photosensitizing treatments post-laser irradiation at 680 and 636 nm, respectively. The decrease of cell viability accompanied by an increased cytotoxicity and apoptotic and necrotic levels, with a time-dependant decrease in cellular proliferation was found to be far more significant for MPc-treated cells than 5-ALA-treated cells, since MPc was applied in far lower concentrations and exhibited far less photoxicity to control cells.

CONCLUSION

Hence, novel MPc proved to be the better photosensitizing dye for metastatic melanoma tumor destruction in combination with laser irradiation and is a particularly attractive photosensitizer since it exhibits so many ideal properties of a photosensitizing agent, thus further research of this possible anticancer agent could contribute to its potential application in PDT cancer treatment of MMs.

Photodynamic therapy (PDT): a short review on cellular mechanisms and cancer research applications for PDT

Photodynamic therapy (PDT) has been used for many years, but it is only now becoming widely accepted and utilized. Originally it was developed as a tumor therapy and some of its most successful applications are for non-malignant diseases. This article provides a broad review of different parameters used and mechanisms instituted in PDT such as photosensitizers (PS), photochemistry and photophysics, cellular localization, cellular signaling, cell metabolism and modes of cell death that operate on a cellular level, as well as photosensitizer pharmacokinetics, biodistribution, tumor localization and modes of tumor destruction. These specific cellular mechanisms are most commonly applied in PDT and for the most part are often researched and exploited. If the combination of these specific parameters and mechanisms can be optimized within PDT it could possibly be used as a suitable alternative for the treatment and management of specific cancers.

Pathways for repair of topoisomerase I covalent complexes in Saccharomyces cerevisiae

BACKGROUND

The covalent linkage between DNA and the active site tyrosine of topoisomerase I can be stabilized by chemotherapeutic agents, adjacent DNA lesions, or mutational defects in the topoisomerase itself. Following collision with a replication fork, the covalent complex can be converted to a double-strand break. Tdp1, an enzyme that can hydrolyse the bond between topoisomerase I and DNA, is thought to be involved in the repair of these lesions, but little is known about how such repair is accomplished.

RESULTS

Reaction kinetics with model substrates reveal that the catalytic efficiency of Saccharomyces cerevisiae Tdp1 is relatively poor when the scissile bond is located in the middle of a duplex, but much better when it is located at the end of a structure. Survival of yeast after induction of a toxic topoisomerase is substantially reduced by inactivation of the TDP1 gene. Comparison of survival of single and double mutants places TDP1 and RAD52 in the same epistasis group but TDP1 and RAD9 in different epistasis groups. In the absence of RAD9, inactivation of TDP1 has a significant effect on the survival of cells following exposure to camptothecin but is without consequence for the survival of agents that do not target topoisomerase I.

CONCLUSIONS

Tdp1 acts as a specific repair enzyme for topoisomerase I lesions. Rather than working at their earliest occurrence, the enzyme acts after covalent complexes have been converted to DSBs. A second repair pathway also exists that functions independently of Tdp1 but requires RAD9 function to efficiently repair topoisomerase I-linked DSBs. The efficiency of these pathways differs for complexes induced with the chemotherapeutic agent camptothecin vs. those accumulated by mutant forms of topoisomerase I.

Yeast gene for a Tyr-DNA phosphodiesterase that repairs topoisomerase I complexes

Covalent intermediates between topoisomerase I and DNA can become dead-end complexes that lead to cell death. Here, the isolation of the gene for an enzyme that can hydrolyze the bond between this protein and DNA is described. Enzyme-defective mutants of yeast are hypersensitive to treatments that increase the amount of covalent complexes, indicative of enzyme involvement in repair. The gene is conserved in eukaryotes and identifies a family of enzymes that has not been previously recognized. The presence of this gene in humans may have implications for the effectiveness of topoisomerase I poisons, such as the camptothecins, in chemotherapy.

A eukaryotic enzyme that can disjoin dead-end covalent complexes between DNA and type I topoisomerases

The covalent joining of topoisomerases to DNA is normally a transient step in the reaction cycle of these important enzymes. However, under a variety of circumstances, the covalent complex is converted to a long-lived or dead-end product that can result in chromosome breakage and cell death. We have discovered and partially purified an enzyme that specifically cleaves the chemical bond that joins the active site tyrosine of topoisomerases to the 3' end of DNA. The reaction products made by the purified enzyme on a variety of model substrates indicate that the enzyme cleanly hydrolyzes the tyrosine-DNA phosphodiester linkage, thereby liberating a DNA terminated with a 3' phosphate. The wide distribution of this phosphodiesterase in eukaryotes and its specificity for tyrosine linked to the 3' end but not the 5' end of DNA suggest that it plays a role in the repair of DNA trapped in complexes involving eukaryotic topoisomerase I.

Effect of nitric oxide synthase substrate analog inhibitors on rat liver arginase

Nitric oxide synthase (EC 1.14.23) substrate analog inhibitors NG-monomethyl-L-Arg, NG-nitro-L-Arg, NG-nitro-L-Arg methyl ester, and aminoguanidine were examined as potential inhibitors of rat liver arginase (EC 3.5.3.1). NG-nitro-L-Arg was found to inhibit arginase catalyzed conversion of L-Arg to L-Orn at pH 7.5 with an IC50 = 27.2 +/- 4.3 mM, compared to L-Val and L-Lys with IC50 values of 6.2 +/- 0.4 mM and 31.3 +/- 2.7 mM, respectively. Inhibition was stereospecific for the L-amino acid, not NG-nitro-D-Arg, and required a free alpha-carboxyl group. NG-nitro-L-Arg was not a substrate for rat liver arginase. These results suggest that arginase inhibition should also be evaluated when studying the effects of NOS substrate analog inhibitors in vivo.

Intraoperative ultrasound in the evaluation of tumor involvement of the inferior vena cava

The successful excision of genitourinary malignancies extending to the inferior vena cava relies heavily on accurate preoperative imaging. For the majority of these patients magnetic resonance imaging, inferior venacavography, abdominal ultrasound or abdominal computerized tomography will reliably predict the extent of inferior vena caval involvement by tumor. However, occasionally the results of these studies will conflict or be called into question intraoperatively. We report on 8 patients considered to be at risk for inferior vena caval involvement by tumor and for whom intraoperative ultrasound was obtained to clarify the presence or extent of thrombus. Five patients had renal cell carcinoma and 3 had adrenal carcinoma. In all patients concern as to the extent or presence of tumor was based on either inconclusive preoperative studies or unexpected intraoperative findings. In each case intraoperative ultrasound clearly visualized the inferior vena cava and established the presence or extent of tumor invasion. In 4 patients venacavotomy was avoided as a consequence of these findings. Intraoperative ultrasound is a useful tool that can accurately assess the inferior vena cava for possible tumor invasion, especially when the presence or extent of tumor involvement is not definitively established preoperatively.

Maternal antibodies to gp120 V3 sequence do not correlate with protection against vertical transmission of human immunodeficiency virus

A retrospective study of sera from mothers infected with human immunodeficiency virus (HIV-1) was undertaken to investigate whether the titers or affinities of antibodies against the third hypervariable region (V3 loop) of gp120 correlated with transmission of the virus from mother to child. The cohort comprised 7 mothers who transmitted HIV-1 to their children and 20 who did not. Sera were screened for reactivity against two synthetic peptides, one encompassing the entire V3 loop of gp120 (amino acids 297-330) and the other containing an immunodominant epitope from gp41 (amino acids 596-614). Doubling dilutions of sera were tested to obtain antibody titers against both peptides: Anti-gp41 titers were used to normalize the anti-V3 titers. Maternal sera were also screened for the presence of high-affinity antibodies against the V3 peptide. No differences were observed in either titers or affinities of maternal antibodies to the V3 sequence from transmitters and nontransmitters.

Advantages of branched peptides in serodiagnosis. Detection of HIV-specific antibodies and the use of glycine spacers to increase sensitivity

The reactivities of antibodies with branched and monomeric peptides were compared in ELISA assays. We found that lower amounts of antibodies could be detected with branched peptides than with monomeric peptides. This was observed with a monoclonal antibody and with antibodies in the sera of various HIV-positive individuals. To investigate the physical aspects of branched peptides important for the observed increase in sensitivity, glycine spacers of different lengths were introduced between the branched lysine core and the epitope reacting with the monoclonal antibody. The effect of the number of glycine residues, both on the sensitivity of antibody detection and on the amount of branched peptide needed to produce a given signal, was studied and the optimum was found at 4-5 residues. We discuss the basis for these findings and conclude that the routine use of branched peptides for serodiagnosis will give both greater sensitivity and appreciable cost savings.

The relative affinity of recombinant dihydrolipoamide transacetylase for autoantibodies in primary biliary cirrhosis

In normal individuals there is an adaptive immune response to a foreign antigen in which antibodies of increasing affinity are produced with time. This is not always true of an autoimmune response. However, because only a limited number of autoantigens have been cloned or purified, this issue has not been studied well. In primary biliary cirrhosis the predominant manifestation of autoimmunity is antimitochondrial antibodies that react with dihydrolipoamide transacetylase. The availability of recombinant dihydrolipoamide transacetylase and the development of a rapid and reproducible enzyme-linked immunosorbent assay for autoantibodies has allowed us to address the affinity of autoantibodies using thiocyanate inhibition. Thiocyanate is a chaotropic compound known to inhibit antigen-antibody binding in a concentration-dependent manner. We used this property to inhibit the binding by enzyme-linked immunosorbent assay of human recombinant dihydrolipoamide transacetylase with serum autoantibodies from 55 patients with primary biliary cirrhosis. The relative affinity and serum autoantibody titers were then compared with the histological stage of the liver biopsy sample. Interestingly, we found a considerable heterogeneity of relative affinities. These relative affinities did not correlate with the histological stage or the serum titer of antimitochondrial antibodies. However, the ability of serum autoantibodies to inhibit intact primary biliary cirrhosis enzyme activity was found to correlate highly (R2 = 0.751) with the relative affinity. Thus there are profound differences between patients with respect to qualitative expression of autoantibodies. The significance of this data will be unclear until more is determined regarding the nature of the epitope that drives T cells and leads to B-cell responses.

Heteroduplex substrates for bacteriophage lambda site-specific recombination: cleavage and strand transfer products

Lambda's Int protein acts as a specific topoisomerase at attachment sites, the DNA segments that are required for site-specific recombination. Int cleaves each strand of an attachment site at a unique place and creates strand exchanges by joining broken ends from two different parents. To study the action of Int topoisomerase in more detail, heteroduplex attachment sites were made by annealing strands that are complementary except for a few base pairs that lie in the region between the points of top and bottom strand exchange in the attachment site core. These heteroduplexes appear to interact normally with Int and its accessory proteins IHF and Xis. Although the heteroduplex sites are specifically cleaved by Int topoisomerase, rejoining of the broken DNA is hindered by the lack of Watson--Crick complementarity adjacent to the break. Because of this, heteroduplexes accumulate broken intermediates which are then processed in novel ways. We have used this feature to provide new information about functional differences between attachment sites, to investigate the way Xis protein controls directionality of site-specific recombination, and to demonstrate that Int protein can join strands indiscriminately and can therefore generate recombinants with either of two genetic polarities.

Bending of the bacteriophage lambda attachment site by Escherichia coli integration host factor

Escherichia coli integration host factor (IHF) is a small basic protein that is required for efficient integrative recombination of bacteriophage lambda. IHF binds specifically to sequences within attP, the site in bacteriophage lambda that undergoes recombination. It has been suggested that the binding of IHF creates bends in DNA so as to help attP condense into a compact structure that is activated for recombination. In this work we show that IHF binding to either of two sites found within attP does indeed produce bending of DNA. In contrast, the other recombination protein needed for integrative recombination, Int, does not appreciably bend the DNA to which it is bound. In agreement with the proposal that IHF bending is important for creating a condensed attP, bending by IHF persists in the presence of bound Int. Our conclusions about protein-directed bends in DNA are based on the study of the electrophoretic mobility of a set of permuted DNA fragments in the presence or absence of IHF and/or Int. To facilitate this study, we have constructed a novel vector that simplifies the generation of permuted fragments. This vector should be useful in studying the bending of other DNA sequences by specific binding proteins.

Overproduction of Escherichia coli integration host factor, a protein with nonidentical subunits

Integration host factor (IHF) is a small, basic protein that is needed for efficient recombination of bacteriophage lambda, as well as for other host and viral functions. We have constructed strains in which the two subunits of IHF, encoded by the himA and hip genes of Escherichia coli, are expressed under the control of the lambda rho L promoter. Separate overexpression of himA and hip led to the production of unstable and insoluble peptides, respectively. In contrast, the overexpression of both genes conjointly led to the accumulation of large amounts of active IHF. Extracts of such cells provided the starting material for a rapid purification procedure that results in milligram quantities of apparently homogeneous IHF.

Cocoa butter biosynthesis. Purification and characterization of a soluble sn-glycerol-3-phosphate acyltransferase from cocoa seeds

Glycerol-3-phosphate acyltransferase has been purified from the post-microsomal supernatant of cocoa seeds using differential ammonium sulfate solubility along with anion exchange and gel filtration chromatography. Chromatofocusing and isoelectric focusing revealed a series of proteins with acyltransferase activity having isoelectric points close to 5.2. Gel filtration on Sephacryl S-300 in 500 mM NaCl, along with polyacrylamide gel electrophoresis (denaturing and non-denaturing) and immunochemical analysis, gave evidence that the native enzyme has a molecular weight of 2 X 10(5) and consists of an aggregate of 10 Mr 20,000 subunits. The highly purified enzyme carries an acyl donor, probably acyl-CoA, although this is not firmly established. The hydrophobic nature of the purified enzyme was demonstrated by its firm binding to octyl-Sepharose. Mass spectrometric analysis of reaction products revealed the presence of both palmitic and stearic acids. Considering that 1) the fatty acids were derived from the purified enzyme; 2) they were found exclusively in the 1-position of glycerol 3-phosphate; 3) the fatty acid positioning and composition is consistent with that found in cocoa butter, the major storage product of cocoa seeds; and 4) the enzyme is found in the post-microsomal supernatant, it seems reasonable to conclude that the first step in cocoa butter biosynthesis is catalyzed by glycerol-3-phosphate acyltransferase in the cytoplasm of cocoa cotyledon cells.

Cyclosporine-induced adenosine triphosphate depletion in murine T and B lymphocytes

Adenosine metabolism in C57BL/6 mouse spleen cells was studied. Adenosine triphosphate (ATP) levels in resting T cells were 26.9 +/- 3.4 ng/10(5) cells compared with 16.5 +/- 3.1 ng/10(5) cells in resting B cells. Cyclosporine (CSA) caused a prompt and severe ATP depletion in both T and B cells, which could be mitigated by the addition of adenosine. B cell ATP levels were returned to normal while T cell levels were only partially restored. The adenosine deaminase inhibitor erythro-9-(2 hydroxy-3 nonyl) adenine (EHNA) also caused ATP depletion in T and B cells, which could similarly be prevented in part by the addition of adenosine. However, when CSA and EHNA were combined, adenosine could no longer protect ATP pools and severe ATP depletion in T and B cells occurred. This suggests that CSA and EHNA affect different steps in the conversion of adenosine to ATP. Although both T and B cell ATP levels were affected by CSA, the ability of supplementary substrate to restore ATP levels to normal in B cells but not in T cells may explain the apparent selective effect of CSA impairing T cell functions with sparing of B cell functions. Furthermore, if causing ATP depletion is associated with immunosuppressive activity, EHNA may be useful in potentiating the immunosuppressive effects of CSA.

Efficient estimation of allelic and genotypic proportions for electrophoretic loci

The efficiency of estimating allelic and genotypic frequencies at allozyme loci can often be increased by running more than one individual simultaneously in each sample slot in a gel. Increased precision in estimating allelic frequencies is always possible if Hardy-Weinberg proportions can be assumed. However, if Hardy-Weinberg cannot be assumed, estimates of both allelic and genotypic frequencies can be improved for loci with hybrid dimers, but not for loci without them. The efficiency of all estimators depends jointly on allele frequencies and the number of individuals run simultaneously.

Purification and properties of the Escherichia coli protein factor required for lambda integrative recombination

A purified preparation of the Escherichia coli integration host factor (IHF) displays two polypeptides of apparent molecular weight 11,000 and 9,500 when analyzed by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Under nondenaturing conditions, IHF appears to exist as a 1:1 complex of these two polypeptides. Integrative recombination takes place in vitro when purified IHF and purified Int, a product of a bacteriophage lambda gene, are the only proteins added to reaction mixtures. No recombination is detected in the absence of either protein. The characteristics of the recombination reaction carried out by these two purified proteins are described. Purified IHF binds to DNA; in the presence of Int, a ternary complex is formed at one of the specific recombination sites. IHF hs no detectable endonuclease or topoisomerase activity. Several possibilities for the role of IHF in recombination are considered.