Influence of sepsis on the plasma elimination pharmacokinetics of diaspirin crosslinked hemoglobin in rats

Septic shock is characterized by abnormalities in microcirculatory O2 delivery (QO2) and profound tissue O2 debt. Administration of crosslinked hemoglobin may be a means of augmenting the QO2 and tissue O2 availability. Sepsis is associated with hemodynamic and metabolic alterations which may affect the pharmacokinetics of crosslinked hemoglobin. The objective of this study was to determine the effect of sepsis on the plasma elimination of diaspirin crosslinked hemoglobin (DCLHb). Twenty-four hours after the induction of sepsis by cecal ligation and perforation, septic (n = 9) and sham rats (n = 8) received an intravenous infusion of 300 mg of DCLHb and arterial blood samples were taken at regular intervals to determine free plasma hemoglobin concentration. DCLHb elimination in septic and sham rats was consistent with first-order elimination kinetics. The half life (t1/2) for septic rats was 4.2 +/- 0.7 h and was significantly shorter than the t1/2 of non-septic rats (5.4 +/- 0.9 h). In all rats, free plasma hemoglobin returned to basal levels by 24 hours after DCLHb administration. The volume of distribution for DCLHb in the septic and non-septic rats was not significantly different and suggests that DCLHb is not influenced by altered gut permeability. Despite significant changes in some elimination parameters the differences were small. Consequently, dosing regimens for this compound may not need to be altered in sepsis.

Hepatic inflammatory responses to alphaalpha-cross-linked hemoglobin infusion in rats

Cross-linked hemoglobin (alphaalpha-Hb) may be a useful red blood cell substitute if it can be administered safely. However, cell-free hemoglobin has inherent properties that may cause oxidant-mediated toxicity. We investigated whether alphaalpha-Hb induces oxidative or inflammatory responses that lead to liver damage. alphaalpha-Hb (0.5 or 1.0 gm/kg) was infused into rats, and indices of liver injury, inflammation, and oxidative stress were examined. Although focal hepatic necrosis was noted at 24 hours, plasma alanine aminotransferase activity was not increased and lesions were resolved by 48 hours. Modest neutrophil accumulation in hepatic vessels, but not sinusoids, occurred at 24 hours. Heme oxygenase-1 (HO-1) protein and activity were induced in a dose- and time-dependent manner, with maximal induction at 24 hours. Plasma tumor necrosis factor-alpha levels were not significantly increased. Additional cytokine- and oxidant-mediated events such as nuclear transcription factor-kappaB activation and nitric oxide synthase induction were not observed. These results suggest that alphaalpha-Hb-derived products such as heme and ferric iron (Fe3+), potent inducers of HO-1, are responsible for increasing HO-1. HO-1 induction may be a protective response by the liver to metabolize excess heme and Fe3+, thereby providing antioxidative products to counter the potentially damaging oxidants produced by Fe3+-catalyzed reactions.

Nasal provocation test with lysine-aspirin for diagnosis of aspirin-sensitive asthma

Nasal provocation tests (NPTs) with lysine-aspirin (L-ASA) have been recently introduced for assessment of aspirin-induced asthma (AIA). They differ in dose and means of aspirin instillation, duration of observation period, and criteria for positivity. Thus far they have not become a routine part of clinical diagnosis. Fifty-one patients with AIA, confirmed by oral challenge test, were recruited to undergo diagnostic NPTs with L-ASA. In 10 of these patients (19.6%), NPTs could not be performed because of total obstruction of at least one nostril or marked fluctuations in nasal flows, leaving 41 patients with AIA for the study. Control groups consisted of 13 aspirin-tolerant asthmatic patients and 10 healthy subjects. L-ASA at a total dose of 16 mg of acetylsalicylic acid applied bilaterally into the inferior nasal conchae caused significant fall in inspiratory nasal flow in at least one nostril (>40%), which was measured by anterior rhinomanometry, and clinical symptoms of watery discharge and nasal blockage in 35 of 41 patients with AIA, one of 10 healthy subjects, and none of 13 aspirin-tolerant asthmatic patients. No relationship was found between the baseline nasal flow values and the intensity of response to L-ASA. No systemic reactions, including bronchospasm, were noticed, even in patients whose initial FEV1 was lower than 70% of predicted value. This test is highly specific (95.7%) and sensitive (86.7%), but negative results do not exclude possible intolerance to aspirin (predictive value of a negative result 78.6%). In conclusion, the NPT described is a simple, safe, and quick test for diagnosis of AIA. It can be used in patients with unstable asthma. It may be a method of choice to confirm hypersensitivity to aspirin manifested only by symptoms from the upper respiratory tract. Patients suspected of aspirin intolerance who have negative NPT results should undergo bronchial or oral challenge tests with aspirin.

Effects of diaspirin cross-linked haemoglobin on post-traumatic cerebral perfusion pressure and blood flow in a rodent model of diffuse brain injury

Diaspirin cross-linked haemoglobin (DCLHb) is a new oxygen carrying blood substitute with vasoactive properties. Vasoactive properties may be mediated via high affinity binding of nitric oxide by the haem moiety. Using a rodent model of head injury combined with ischaemia, we studied the effects of DCLHb on cerebral blood flow (CBF) and intracranial pressure (ICP). Twenty anaesthetized rats were allocated randomly to receive treatment with DCLHb 400 mg kg-1 i.v. or placebo (oncotically matched plasma protein substitute 4.5% i.v.). To produce diffusely increased ICP, after a severe weight drop injury, all animals underwent a 30-min period of bilateral carotid ligation combined with a period of induced hypotension. After reperfusion, DCLHb or placebo was infused and the animals instrumented for measurement of intraventricular ICP and CBF in the region of the sensorimotor cortex using the hydrogen clearance technique. Mean arterial pressure (MAP), ICP, cerebral perfusion pressure (CPP) (CPP = MAP - ICP) and CBF were measured 4 h after injury in all animals. DCLHb significantly reduced ICP from mean 13 (SEM 2) to 3 (1) mm Hg (P < 0.001), increased CPP from 52 (8) to 95 (6) mm Hg (P < 0.001) and increased CBF from 21 (2) to 29 (2) ml 100 g-1 min-1 (P = 0.032). We conclude that DCLHb improved CPP without a reduction in CBF in a rodent model of post-traumatic brain swelling.

Mechanism of the acute pressor effect and bradycardia elicited by diaspirin crosslinked hemoglobin in anesthetized rats

Diaspirin crosslinked hemoglobin (DCLHb) is a chemically stabilized hemoglobin (Hb) that induces an increase in blood pressure and a decrease of heart rate when injected intravenously in some animals. The mechanism by which DCLHb elicits these hemodynamic effects was studied in pentobarbital-anesthetized, vagotomized rats using a variety of drugs known for their inhibitory action towards endogenous hemodynamically active systems. The hypertensive episode elicited by DCLHb (100 or 400 mg.kg-1) was attenuated in animals pretreated with NG-nitro-L-arginine (inhibitor of nitric oxide synthases) throughout the 30-min period of observation, but it was not reduced in those pretreated with a variety of sympatholytic drugs (e.g., prazosin), atropine, BIBP-3226 (neuropeptide Y antagonist), indomethacin, [1-(beta-mercapto-beta,beta-cyclopentanemethylene propionic acid), 2-(0-methyl) tyrosine]-Arg8 vasopressin (vasopressin antagonist), losartan (angiotensin antagonist), bosentan (endothelin antagonist), or L-arginine-(nitric oxide precursor), compared with control animals. With the exception of propranolol and BIBP-3226, none of the aforenamed inhibitors reduced the amplitude of the bradycardia associated with the pressor effect of DCLHb. These results suggest that: (i) the acute (< 30 min) pressor activity of DCLHb in our animal model requires the presence of an endogenous nitric oxide generating system to be expressed; (ii) the bradycardia elicited by DCLHb might involve the participation of neuropeptide Y and (or) its NPY-1 receptors, but it is unlikely to involve a baroreceptor-mediated vagal reflex, at least in our animal model.

Growth inhibition of fibroblasts from nasal polyps and normal skin by lysine acetylsalicylate

Some authors have shown that lysine acetylsalicylate (LAS) may help prevent nasal polyp relapses. As some anti-inflammatory drugs have been found to regulate cell growth, we investigated the antiproliferative effect of LAS on fibroblasts derived from nasal polyps. Moreover, we studied the effect of LAS on the growth of fibroblasts derived from normal skin to determine whether the response was similar to that obtained in the above-mentioned cells. Fibroblasts were obtained from tissue samples of nasal polyps from two aspirin-tolerant and two aspirin-intolerant patients, and from the normal skin of a healthy donor. The cells were treated with LAS (20-2000 microg/ml of culture medium). Cell growth and viability were evaluated after 3 and 6 days of culture. LAS had a growth-inhibitory effect on cells independently of their derivation. A reduction in cell growth was seen at the concentrations of LAS tested, which correspond to those used in the local treatment of nasal polyposis.

Modulation of resuscitative effect of diaspirin cross-linked hemoglobin by L-NAME in rats

Diaspirin Cross-linked Hemoglobin (DCLHb), a hemoglobin-based oxygen carrier, improves regional blood circulation and systemic hemodynamics in normal and hemorrhaged rats. The action of DCLHb is partly mediated by its scavenging effect on nitric oxide. This study was undertaken to determine the effect of DCLHb on nitric oxide mechanism in hemorrhagic conditions. We studied the modulation of cardiovascular effects of DCLHb by a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) in hemorrhaged rats. The base deficit, survival time, oxygen consumption, and blood circulation to the brain, heart, gastrointestinal tract, and kidneys were determined in 1) DCLHb (100 mg/kg, intravenously (i.v.), 2) L-NAME (2 mg/kg, i.v.), 3) L-NAME (2 mg/kg, i.v.) + DCLHb (100 mg/kg, i.v.), and 4) L-arginine (100 mg/kg/h, i.v.) + DCLHb (100 mg/kg, i.v.) treated rats. Hemorrhage was induced in urethane-anesthetized male rats by bleeding them at a rate of approximately .5 to 1 mL/min, until a mean arterial pressure of 35-40 mmHg was achieved. This blood pressure was maintained for 30 min. Sham-operated nonhemorrhaged rats survived for >300 min, whereas hemorrhaged rats survived for only 85+/-31 min. Hemorrhage significantly increased base deficit and decreased oxygen consumption. A significant decrease in heart rate, mean arterial pressure, cardiac output, stroke volume, and in blood flow to the gastrointestinal tract and kidneys was observed after hemorrhage. Resuscitation with DCLHb produced a significant increase in survival time, oxygen consumption, heart rate, mean arterial pressure, cardiac output, total peripheral resistance, and blood flow to the brain, heart, and kidneys. In contrast, resuscitation with L-NAME did not improve base deficit, survival time, oxygen consumption, systemic hemodynamics, or regional blood flow. L-arginine pretreatment did not affect DCLHb-induced resuscitation of hemorrhaged rats. Furthermore, L-NAME (pretreated or co-administered) attenuated the resuscitative effect of DCLHb. These data suggest that nitric oxide mechanism may not be the only mechanism involved in the resuscitative effect of DCLHb.

[Use of antihypoxants in the acute period of myocardial infarction]

A total of 620 patients with acute myocardial infarction were followed up in order to assess the efficacy of antihypoxants as a component of intensive care. 385 of these patients, divided into groups of 20-40 subjects, were administered one of 12 antihypoxants or sessions of hyperbaric oxygenation during the acute period of the disease, the rest were treated traditionally. Analysis of clinical, laboratory, and prognostic values showed the highest protective effect of amtizol, lithium hydroxybutyrate, piracetam, and ubiquinone. Cytochrome C, riboxine, mildronate, and olifen were somewhat less active, and solcoseryl, bemitil, trimethasidine, and aspisol were the least effective. The protective potentialities of standard sessions of hyperbaric oxygenation were virtually null. The author proposes a parameter D, reflecting the difference between actual and predicted mortality, and the rating (score) system for assessing the routine laboratory diagnostic tests to be used together with the known criteria for evaluation of the protective effects of antihypoxants in patients with acute myocardial infarction.

Absence of immunogenicity of diaspirin cross-linked hemoglobin in humans

Diaspirin cross-linked hemoglobin (DCLHb) is an intramolecularly cross-linked hemoglobin-based oxygen carrier being developed as a therapy for acute blood loss. We report here the absence of immunogenicity of DCLHb in patients enrolled in phase II and III clinical trials of DCLHb. Two very sensitive immunoassays, an enzyme-linked immunosorbent assay (ELISA) and a Western blot assay, were developed and validated for this assessment. The DCLHb-antibodies used in these assays were raised in monkeys, had similar affinities for DCLHb and native human hemoglobin (SFHb), and showed cross-reactivity for subunits of DCLHb and SFHb on the Western blot, suggesting that these antibodies were elicited as a xenogenic response to the protein. In the ELISA, the optical density of a patient sample exposed to DCLHb-coated wells was compared with that of the patient sample exposed to carbonate buffer-coated wells; an optical density ratio of 1.4 was established for discriminating between a positive (reactive) or negative DCLHb antibody response. To date, all of the more than 300 patient specimens (preinfusion and postinfusion) from clinical trials have exhibited a ratio of less than 1.4, confirming the lack of preexisting antibodies to DCLHb and clearly showing the absence of DCLHb antibodies after exposure to this new biologic entity. There has been no requirement for use of the confirmatory Western blot assay. Taken together, the results from this study indicate DCLHb is not immunogenic in humans at doses evaluated clinically.

Structural requirements and mechanism of the pressor activity of Leu-Val-Val-hemorphin-7, a fragment of hemoglobin beta-chain in rats

A rat blood pressure assay was used to perform a structure-activity relationship study (SAR) of Leu-Val-Val-hemorphin-7 (LVV-H7), a fragment of hemoglobin (Hb) beta-chain, elucidate the mechanisms of its cardiovascular effects, and test its potential involvement in the pressor activity of diaspirin crosslinked Hb (DCLHb), a recently developed Hb-based oxygen carrier. The SAR study revealed that the C-terminal-Arg-Phe-amino acid sequence of LVV-H7 contained the main determinants of the pressor activity of this peptide. Drug interaction studies using various inhibitory drugs (e.g., phentolamine, clonidine, etc.) and LVV-H7 showed that the pressor effect and tachycardia elicited by LVV-H7 involved the activation of the sympathetic nervous system (SNS). Additional studies using phenytoin (sodium channel blocker), [Tic7]H7(5-7)-NH2 (putative antagonist of receptors for LVV-H7) and H7(5-7)-NH2, an amidated C-terminal fragment of LVV-H7, suggested that LVV-H7 activated the SNS by interacting with specific receptors functionally coupled with phenytoin-sensitive sodium channels. The pressor effect and tachycardia caused by LVV-H7 were potentiated by captopril, suggesting that the angiotensin converting enzyme may contribute to the inactivation of LVV-H7 in rats. The pressor activity of DCLHb, in contrast to that elicited by LVV-H7, was not affected by animal pretreatment with LVV-H7 fragments shown to inhibit the pressor effect of LVV-H7. We conclude that: 1) LVV-H7 is unlikely to mediate the pressor activity of DCLHb in rats; 2) the pressor and tachycardic activities of LVV-H7 are mediated by the SNS; 3) the C-terminal-Arg-Phe-amino acid sequence of LVV-H7 contains the chemical groups responsible for the pressor effect of this peptide in rats; 4) LVV-H7 and FMRF amide-related peptides may share the same mechanism of pressor activity in rats.

DOSE-DEPENDENT EFFECT OF DIASPIRIN CROSS-LINKED HEMOGLOBIN ON REGIONAL BLOOD CIRCULATION OF SEVERELY HEMORRHAGED RATS

Diaspirin cross-linked hemoglobin (DCLHb), a hemoglobin-based blood substitute, has been found to improve systemic hemodynamics, cutaneous oxygen tension, and normalization of blood lactate levels and acid-base equilibrium after hemorrhage in animals. The present study was conducted to determine the dose-dependent effect of a 10% solution of DCLHb (20, 50, and 100% of shed blood volume; SBV) on regional blood circulation in hemorrhaged rats. Hemorrhage was induced in urethane-anesthetized rats by bleeding them at a rate of approximately .5 to 1 mL/min until a mean arterial pressure of 35-40 mmHg was achieved. This was maintained for up to 90 min to reach a base deficit of more than -12 mmol/L. Hemorrhage significantly decreased oxygen consumption, mean arterial pressure, cardiac output, stroke volume, and regional blood circulation, but increased total peripheral resistance. The vehicle Ringer's lactate (RL at 20% of SBV, intravenously) did not produce any improvements in oxygen consumption, base deficit, systemic hemodynamics, and regional blood circulation. DCLHb increased oxygen consumption, decreased base deficit, and produced significant improvements in systemic hemodynamics and regional blood flow in a dose-dependent manner. The increase in blood flow was highly significant until 60 min, but was less marked at 120 min, after resuscitation with DCLHb. Resuscitation with RL (300% of SBV) significantly improved systemic and regional blood circulation. However, the improvement was greater after resuscitation with DCLHb (50 or 100% of SBV) as compared with RL at 300% SBV. DCLHb in the dose of 50% of SBV produced maximal resuscitative effects, which were comparable to a DCLHb dose of 100% of SBV. The effect of DCLHb at 50% of SBV on renal cortical blood perfusion, concentration of moving red blood cells (CMBC), and blood velocity was also studied using laser Doppler flowmetry. Hemorrhage produced a decrease in renal cortical blood perfusion (85.3%), which was due to a decrease in the CMBC (61.0%) and their velocity (64.2%). Resuscitation with the RL did not produce any improvement in renal cortical perfusion. However, resuscitation with DCLHb significantly increased renal cortical perfusion (364.7%) due to an increase in both CMBC (123.4%) and their velocity (109.9%). It is concluded that DCLHb in a dose of 50% of SBV produces maximal improvement in regional blood circulation of hemorrhaged rats.

Hemoglobin A0 and alpha-crosslinked hemoglobin (alpha-DBBF) potentiate agonist-induced platelet aggregation through the platelet thromboxane receptor

Chemically modified hemoglobins are potential oxygen-carrying blood substitutes, but their in vivo administration has been associated with a variety of unexpected side events, including increased platelet reactivity. We studied the effects of hemoglobin A0 (HbA0) and alpha-crosslinked hemoglobin (alpha-DBBF) on platelets in vitro. Neither hemoglobin A0 nor alpha-DBBF activated platelets when added alone, but both proteins potentiated submaximal agonist-induced platelet aggregation without increasing other markers of platelet activation such as serotonin secretion. Only agonists that are known to cause release of platelet arachidonic acid (AA) were potentiated while aggregation induced by ADP, which does not release AA, was not potentiated. Blockade of the thromboxane receptor with SQ-29,548 prevented the HbA0-induced and the alpha-DBBF-induced potentiation suggesting that the AA/thromboxane signaling pathway mediates the interaction of platelets with hemoglobin.

Aspalatone, a new antiplatelet agent, attenuates the neurotoxicity induced by kainic acid in the rat

The antioxidant efficacy of aspalatone (APT; acetyl salicylic acid maltol ester), a new antiplatelet agent, has been characterized in vivo as well as in vitro, and several observations indicated that the antioxidant could prevent the neuroexcitation caused by oxidative stress. In this report, the effect of APT was evaluated on kainic acid (KA)-induced neurotoxicity, since the neurotoxicity induced by KA is, at least in part, mediated via the formation of free radicals. The results showed that pretreatments with APT or maltol (MAL) significantly attenuated seizure activity, oxidative stress (lipid peroxidation and protein oxidation) and the loss of hippocampal neurons induced by KA. On the other hand, the pretreatments with aspirin (ASP), ASP together with MAL or vitamin E failed to protect against the toxicity produced by KA suggesting that the mechanism of action for APT on the KA-induced neurotoxicity is different from that of ASP. These finding raise the possibility that salicylmaltol, a metabolite of APT, plays a role in preventing the neurotoxicity evoked by KA. Therefore, our results suggest that an APT-related antioxidant mechanism, which is linked to the MAL moiety, is involved in the neuroprotective effect against KA.

Experimental subarachnoid hemorrhage in rats: effect of intravenous alpha-alpha diaspirin crosslinked hemoglobin on hypoperfusion and neuronal death

BACKGROUND

Hemodilution with diaspirin crosslinked hemoglobin (DCLHb) ameliorates occlusive cerebral ischemia. However, subarachnoid hemoglobin has been implicated as a cause of cerebral hypoperfusion. The effect of intravenous DCLHb on cerebral perfusion and neuronal death after experimental subarachnoid hemorrhage was evaluated.

METHODS

Rats (n = 48) were anesthetized with isoflurane and subarachnoid hemorrhage was induced by injecting 0.3 ml of autologous blood into the cistema magna. Each animal received one of the following regimens: Control, no hematocrit manipulation; DCLHb, hematocrit concentration decreased to 30% with DCLHb; or Alb, hematocrit concentration decreased to 30% with human serum albumin. The experiments had two parts, A and B. In part A, after 20 min, cerebral blood flow (CBF) was assessed with 14C-iodoantipyrine autoradiography. In part B, after 96 h, in separate animals, the number of dead neurons was determined in predetermined coronal sections by hematoxylin and eosin staining.

RESULTS

Cerebral blood flow was greater for the DCLHb group than for the control group; and CBF was greater for the Alb group than the other two groups (P < 0.05). In one section, CBF was 45.5 +/- 10.9 ml x 100 g(-1) x min(-1) (mean +/- SD) for the control group, 95.3 +/- 16.6 ml x 100 g(-1) x min(-1) for the DCLHb group, and 138.1 +/- 18.7 ml x 100 g(-1) x min(-1) for the Alb group. The number of dead neurons was less in the Alb group (611 +/- 84) than in the control group (1,097 +/- 211), and was less in the DCLHb group (305 +/- 38) than in the other two groups (P < 0.05).

CONCLUSIONS

These data support a hypothesis that hemodilution decreases hypoperfusion and neuronal death after subarachnoid hemorrhage. The data do not support the notion that intravascular molecular hemoglobin has an adverse effect on brain injury after subarachnoid hemorrhage.

Reduction of shock-induced gastric damage by a nitric oxide-releasing aspirin derivative: role of neutrophils

The gastric damage associated with hemorrhagic shock appears to occur, at least in part, through neutrophil-dependent mechanisms. Nitric oxide (NO)-releasing derivatives of aspirin have been shown to spare the gastrointestinal tract of injury. As NO can inhibit neutrophil adherence, it is possible that such a derivative of aspirin (NCX-4016) would exert inhibitory effects on neutrophil adherence and therefore be capable of protecting the stomach against shock-induced gastric damage. This hypothesis was tested in this study. Oral administration of NCX-4016 or glyceryl trinitrate or depletion of circulating neutrophils with antineutrophil serum significantly reduced the extent of gastric damage induced by hemorrhagic shock, whereas aspirin had no effect. NCX-4016 and antineutrophil serum pretreatment resulted in significant preservation of gastric blood flow during the shock period. Moreover, NCX-4016, but not aspirin, was capable of inhibiting N-formyl-Met-Leu-Phe-induced leukocyte adherence to postcapillary mesenteric venules. These results suggest that an NO-releasing aspirin derivative reduces the susceptibility of the stomach to shock-induced damage through inhibitory effects on neutrophil adherence to the vascular endothelium.

Structural characterization of human hemoglobin crosslinked by bis(3,5-dibromosalicyl) fumarate using mass spectrometric techniques

Diaspirin crosslinked hemoglobin (DCLHb) was analyzed by mass spectrometric-based techniques to identify the protein modifications effected by the crosslinking reaction with bis(3,5-dibromosalicyl) fumarate. DCLHb consists of two principal components. These components were isolated by size-exclusion chromatography and identified by measurement of their molecular weight using electrospray mass spectrometry and subsequent peptide mass mapping and mass spectrometric sequence analysis of their individual digests. Three major RP-HPLC fractions were observed from the major hemoglobin in DCLHb. Their MWs matched the MW of heme, intact hemoglobin beta-chain, and two hemoglobin alpha-chains crosslinked by a fumarate moiety, respectively. The minor HPLC peaks of DCLHb were also separated, and characterized by mass spectrometric methods. These minor components revealed additional details of the structural nature of covalent modification of DCLHb.

The effects of diaspirin-crosslinked hemoglobin on the assessment of immunohematology profiles

BACKGROUND

Extensive studies have been conducted on the in vitro effects of diaspirin-crosslinked hemoglobin (DCLHb) in biochemical, hematologic, hemostatic, and blood banking (immunohematologic) methods. The absence of red cell antigens or plasma and/or serum antibodies allows DCLHb to be used as "universal-donor" material. This study evaluates the effects of DCLHb on the accurate assessment of the immunohematologic profile (ABO and Rh blood grouping, antibody screen, and crossmatching).

STUDY DESIGN AND METHODS

DCLHb, 7.4 g per dL in an electrolyte solution, was mixed in vitro with human whole blood, representing the blood types A Rh-positive. A Rh-negative, B Rh-positive, B Rh-negative, O Rh-positive, O Rh-negative, and AB Rh-positive. Two concentrations of DCLHb were tested: 10-percent (0.74 g/dL) and 30-percent (2.22 g/dL). Controls were prepared by adding a 5-percent albumin solution to aliquots of whole blood in volumes equivalent to those used in preparing the DCLHb dilutions. Serum and/or red cell suspensions from these admixed samples were analyzed for their ABO and Rh blood groups, the presence of unexpected antibodies (antibody screen), and compatibility in crossmatch testing.

RESULTS

DCLHb added to whole blood in vitro had no effect on the accurate interpretation of the immunohematologic profile.

CONCLUSION

DCLHb does not appear to inhibit the true response or crossreact in the analysis of blood grouping, antibody screening, or crossmatching. In addition, the red color of DCLHb (up to 2.22 g/dL) did not obscure the visual reading for agglutination.

Validation of the heat treatment step used in the production of diaspirin crosslinked hemoglobin (DCLHb) for viral inactivation--effect of crosslinking

Two experiments were performed to assess viral inactivation during the crosslinking and heat treatment steps of the DCLHb manufacturing process. Stroma free hemoglobin (SFHb) collected from a large scale manufacturing lot was tested in a 1:680 scaled down system in which the key parameters used in the manufacturing process were replicated. In the first study Porcine Parvovirus (PPV), a non-enveloped virus, was used to assess inactivation, while in the second study Bovine Viral Diarrhea Virus (BVDV), an enveloped virus, was utilized. In both experiments, the SFHb solution was deoxygenated and an aliquot of virus suspension was added. To initiate the crosslinking reaction, a solution of bis (3,5-dibromosalicyl) fumarate (DBBF) in HEPES buffer was added to the test solution. In both experiments the reaction times and the degree of crosslinking were normal. After crosslinking, the reaction mixtures were heated to 74 +/- 1 degrees C over 30 minutes, held at 74 +/- 1 degrees C for 90 minutes, and cooled to less than 10 degrees C over 30 minutes. In each experiment the degree of crosslinking of final product was 100% and yield of hemoglobin recovery was normal. Samples were removed prior to crosslinking, after crosslinking and before, during and after heat treatment for determination of virus titer and evaluation of key process parameters. The results from these experiments were consistent with those obtained from the full scale manufacturing process for the deoxygenation, crosslinking and the heat treatment step during the production of DCLHb. The results of virus assays showed that crosslinking has no effect on viruses and their subsequent inactivation by heat treatment.

Diaspirin crosslinked hemoglobin improves systemic oxygen uptake in oxygen supply-dependent septic rats

Diaspirin crosslinked hemoglobin (DCLHb) is a cell-free hemoglobin derived from human erythrocytes. DCLHb has been shown to improve blood flow to vital organs in healthy and septic animals. In this study, we determined the efficacy of DCLHb by comparing its effect on systemic O2 uptake to freshly stored and aged red blood cells (RBCs) in septic rats. Twenty-four hours after induction of sepsis by cecal ligation and perforation, O2 supply dependency was created by isovolemic hemodilution with rat plasma. In O2 supply dependency, rats were randomized to receive an exchange transfusion of 7.5 ml "fresh" RBCs (stored < 6 d; Hct: 70%), "fresh" diluted RBCs (stored < 6 d; Hct: 30%), "old" RBCs (stored 28 to 35 d; Hct: 70%), or DCLHb (Hb: 100 g/L). We found, that survival following O2 supply dependency and transfusion with old RBCs was poor (33% versus 91.7% in the other groups; p < 0.01), precluding further analysis of post-transfusion data from this group. Systemic O2 uptake increased in all remaining groups (p < 0.001), while systemic O2 delivery increased with "fresh" RBCs (p < 0.0001) and "fresh" diluted RBCs (p < 0.05) but not with DCLHb. Systemic O2 extraction increased with DCLHb as compared to baseline (p < 0.05) and to the other groups (p < 0.0001). Improved tissue oxygenation was associated with an increase in blood pressure and a fall in arterial lactate in all groups. We conclude that transfusion of DCLHb or "fresh" RBCs was efficacious at increasing systemic O2 uptake in O2 supply-dependent, septic rats.

Effects of diaspirin-cross-linked hemoglobin (DCLHb) on local tissue oxygen tension in striated skin muscle: an efficacy study in the hamster

Using the dorsal skin fold chamber model in the hamster, we analyzed local tissue partial oxygen pressure (PO2) in the striated skin muscle under nonischemic and postischemic conditions with a Clark-type multiwire oxygen surface electrode. Hypervolemic infusion (500 mg x kg(-1) I.V.) or isovolemic exchange transfusion (3.3 gm x kg(-1) I.V.; hematocrit 30%) with diaspirin-cross-linked hemoglobin (DCLHb) resulted in a slight decrease of the mean value of the local tissue PO2 (mm Hg) 1 hour after administration. Concomitantly, the frequency distribution curves of local tissue PO2 values were found to be more narrow (fewer values > 25 mm Hg and < 10 mm Hg). Resuscitation from severe hemorrhagic shock (bleeding of 33 ml x kg(-1) at 0.4 ml x min(-1)) with autologous blood (AuB), Dx-60, or DCLHb led to an increase of mean tissue PO2 values by 4.2-fold (p < 0.05 versus Dx-60), 1.9-fold, and 3.7-fold (p < 0.05 versus Dx-60), respectively, 2 hours after resuscitation. The reduction of tissue hypoxia (0-5 mm Hg) was significant only in the AuB- and DCLHb-treated animals. This study indicates that DCLHb effectively reverses tissue hypoxia after resuscitation from severe hemorrhagic shock by inducing a more homogeneous distribution of the local tissue PO2 levels.

Nasal provocation tests in the diagnosis of urticaria induced by acetylsalicylic acid

Nasal provocation tests with lysine acetylsalicylic acid (ASA) have been used in the diagnosis of ASA-induced asthma and rhinitis. To establish its possible role in identifying aspirin sensitivity manifested by urticaria or angioedema, 18 patients suffering from chronic or acute recurring urticaria/angioedema (10 ASA-sensitive and 8 ASA-nonsensitive) were submitted to nasal provocation tests with freshly prepared solutions of lysine ASA. Clinical response and variation of nasal expiratory peak-flow were evaluated, classified according to previously defined scores, and compared. The results showed a significant difference between ASA-sensitive and ASA-nonsensitive patients, suggesting that this test can be an important diagnostic tool for ASA-induced urticaria/angioedema.

Effects of diaspirin-cross-linked hemoglobin (DCLHb) on the microcirculation of striated skin muscle in the hamster: a study on safety and toxicity

Hemoglobin-based oxygen-carrying solutions are reported to exert vasoconstrictor effects and to enhance oxygen radical formation, particularly during ischemia-reperfusion. This study investigates whether diaspirin-cross-linked hemoglobin (DCLHb) affects the microvascular integrity of striated skin muscle. The microcirculation model in the hamster and intravital fluorescence microscopy were applied for investigation of the microvascular changes in striated skin muscle. Hypervolemic infusion (500 mg x kg(-1), I.V.) and isovolemic exchange transfusion (3.3 gm x kg(-1) I.V.; hematocrit 30%) with DCLHb (1) led to a short-lasting (0 to 2 minutes) arteriolar constriction (approximately 20% reduction in baseline diameter), (2) significantly influenced arteriolar vasomotion, (3) increased venular red blood cell velocity by 1.5-fold (p < 0.05 vs dextran, Mr 60,000), and (4) did not enhance microvascular leukocyte-endothelium interaction or endothelial permeability. Resuscitation from severe hemorrhagic shock with autologous blood (AuB) or DCLHb (33 ml x kg(-1), I.V.) immediately restored mean arterial pressure and heart rate, whereas 6% dextran (60 kd)(Dx-60) did not return these parameters to baseline. Venular red blood cell velocity was restored to 110% of baseline after DCLHb, to 90% of baseline after AuB, and to 45% of baseline after Dx-60. Leukocyte-endothelium interaction was significantly enhanced after resuscitation with AuB and Dx-60, whereas this phenomenon was absent after DCLHb. These data demonstrate that DCLHb increases venular red blood cell velocity under both nonischemic and postischemic conditions without inducing enhanced leukocyte-endothelium interaction in the microcirculation of striated skin muscle.