Effect of diaspirin cross-linked hemoglobin and norepinephrine on systemic hemodynamics and regional circulation in rats

Diaspirin cross-linked hemoglobin (DCLHb) (400 mg/kg, i.v.) produced a pressor effect that was equal to that produced by norepinephrine (NE) (25 micrograms/kg/min i.v. infusion). Total peripheral resistance was increased by DCLHb and more significantly by NE. Heart rate was not affected by DCLHb but was significantly increased by NE. The cardiac output and stroke volume were insignificantly increased by DCLHb but were significantly decreased by NE. DCLHb and NE produced a significant increase in blood flow to the heart. The vascular resistance in the heart was not affected by DCLHb but was decreased by NE. DCLHb did not affect the renal and brain circulation, but NE in kidneys decreased the blood flow and increased the vascular resistance, whereas in the brain it increased the blood flow and decreased the vascular resistance. DCLHb increased the blood flow to the stomach and small intestine. The vascular resistance was not affected by DCLHb in the gastrointestinal tract. NE did not affect the blood circulation in the gastrointestinal tract. Blood flow to the spleen was increased by DCLHb, and there was no change in the vascular resistance. NE insignificantly decreased the blood flow to the spleen and significantly increased the vascular resistance. The blood circulation to the mesentery and pancreas was not affected by DCLHb, whereas NE increased the blood flow without affecting the vascular resistance. DCLHb produced a significant increase in the blood flow to the skin without affecting the vascular resistance, whereas NE did not affect the blood flow but increased the vascular resistance. DCLHb did not affect the blood flow to the musculo-skeletal system but increased the vascular resistance, whereas NE decreased the blood flow and increased the vascular resistance. In summary, although the pressor effect of DCLHb and NE at the doses studied is equal, DCLHb did not decrease the blood flow to any organ, whereas NE produced significant decreases in blood flow to several organs. It is concluded that the blood flow to most of the organs is either increased or not affected by DCLHb.     

Resuscitation from hemorrhagic shock with diaspirin cross-linked hemoglobin, blood, or hetastarch

BACKGROUND: An oxygen-transporting hemoglobin solution should be more effective than a nonhemoglobin solution for resuscitation from hemorrhagic shock. A way to evaluate this effectiveness is to determine whether a hemoglobin solution can reverse the base deficit accumulated during hemorrhage at a faster rate than a nonhemoglobin solution. Using this criterion, we compared the resuscitative powers of autologous blood, hetastarch (Het), and diaspirin cross-linked hemoglobin (DCLHb). METHODS: Fifteen sedated, spontaneously breathing sheep (37.5 +/- 10.2 kg) were bled until base deficits fell to -5 to -10 mEq/L, and plasma lactate concentrations rose to 6 to 9 mg/L. The animals were resuscitated with autologous blood (n = 5), Het (n = 5), or DCLHb (n = 5) (3.5-4.0 mL/kg every 15 minutes) until base deficits returned to prehemorrhage baseline. RESULTS: Exsanguination to target base deficits required removal of an average of 41.4 +/- 5.5 mL blood/kg (estimated total blood volume, 80 mL/kg). Resuscitation required 18 +/- 3, 38 +/- 2 (different from blood), and 35 +/- 1 (different from blood) mL/kg of autologous blood, Het and DCLHb, respectively, over periods of 78 +/- 8, 163 +/- 10 (different from blood), and 129 +/- 9 minutes (different from blood and different from Het (p < or = 0.05)). Based on regression analysis, autologous blood, Het, and DCLHb corrected the base deficit at rates of, respectively, 0.074 (different from Het (p < or = 0.05)), 0.016, and 0.056 (different from Het (P < or = 0.05)) mEq/L/min. CONCLUSIONS: Based on the rate of base deficit correction and the volume of solution required, autologous blood was the most effective resuscitation solution. However, DCLHb was more effective than Het. DCLHb may be an attractive alternative to blood for resuscitation from hemorrhagic shock.     

The cytotoxic activities of human hemoglobin and diaspirin crosslinked hemoglobin

It is well known that hemoglobin (Hb) possesses many oxidative enzyme activities, including a pseudo-peroxidase activity. It has also been shown by many investigators that various peroxidases in the presence of hydrogen peroxide and a halide ion exert a potent cytotoxic activity toward various mammalian cell types. It has further been observed by various investigators that the administration of relatively large amounts of purified Hb or a Hb derivative to a host animal during resuscitation experiments leads to a number of unrelated types of tissue damage and cell damage in the host. The first objective of this investigation was to determine if the observed tissue and cell damage may be due to a cytotoxic activity that Hb may exert in vivo analogous to that of the peroxidases. We also showed some time ago that peroxidases are able to activate peritoneal macrophages to the cytocidal state. Hence, we also addressed the question whether or not Hb is able to activate macrophages in a similar manner. Our results were negative with regard to both questions. Further investigations indicated that, unlike the peroxidases, ferryl-Hb is unable to oxidize iodide to iodine at a measurable rate, which appears to be the reason for the lack of cytotoxic activity.     

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

Although intracellular pH (pHi), is a regulator of numerous biological processes, it has received relatively little attention with regard to the physiology of the mammalian preimplantation embryo. Interestingly, there is some controversy as to whether the early embryo can recover from an acid load. The significance of this is that two constituents of mouse embryo culture media are pyruvate and lactate. These carboxylic acids are utilised by the early mouse embryo for energy production. However, as weak acids, pyruvate and lactate may induce perturbations in the pHi and thus alter the physiology of the embryo. The aims of this study were therefore to measure the pHi of the mouse preimplantation embryo and to determine the effect of lactate on pHi at different developmental stages. The pHi was measured using the ratio-metric fluorophore carboxy-seminaphthorhodafluor-1-acetoxymethylester (SNARF-1) in conjunction with confocal microscopy. The pHi increased significantly with development from the zygote to the morula stage. Furthermore, at concentrations greater than 5 mM, lactate caused the pHi of the zygote to become significantly more acidic. It was demonstrated that facilitative transport in association with a smaller passive component was responsible for the movement of lactate into the zygote. Metabolic studies revealed that, through their acidifying effect, weak acids caused a reduction in glycolytic activity in the early embryo. In contrast, the pHi of the compacted embryo remained unchanged by the presence of lactate in the external media. Furthermore, incubation with weak acids did not affect the rate of glycolysis in the morula. These data suggest that, by the generation of a transporting epithelium at compaction, the embryo develops the ability to regulate pHi against an acid load.     

Observations on isovolemic hemodilution in acute ischemic stroke

The reduction of blood viscosity is an alternative of the improvement of the cerebral flow during an acute ischemic stroke (AIS). We studied 18 patients with AIS, ranging in age from 44 to 72 years (mean age 57 years), 11 females and 7 males. We applied an isovolemic hemodilution for 2 days starting with an emission of 250 or 500 ml blood, followed by the infusion of an equal amount of 6% HAES-steryl solution. We made determination of hematocrit, plasma density, plasma viscosity 1, 3 and 6 hours before and after the infusion; a decrease was noted in all the studied hemorheologic parameters, and the short term clinical course was an improvement. In conclusion, the isovolemic hemodilution using 6% HAES solution reduced hematocrit, plasma density, plasma viscosity but no changes were noted in the hemodynamic parameters; isovolemic hemodilution as the single therapeutic method in AIS does not solve the therapy, involving only one pathogenetic link, i.e., the microcirculation.     

Local intra-arterial thrombolysis in acute ischemic stroke

BACKGROUND AND PURPOSE: We performed a retrospective analysis of the prognostic factors in patients treated with local intra-arterial thrombolysis (LIT). The purpose of this study was to evaluate the safety and efficacy of LIT using urokinase in patients with acute ischemic stroke of the anterior or posterior circulation and to determine the influence of clinical and radiological parameters on outcome. METHODS: Forty-three patients were treated with LIT using urokinase (median dose, 0.75x10(6) IU). The median National Institutes of Health Stroke Scale (NIHSS) score at hospital admission was 18 (range, 9 to 36). Nine patients had occlusions of the internal carotid artery (ICA), 23 of the middle cerebral artery (MCA), 1 of the anterior cerebral artery, and 10 of the basilar artery (BA). Outcome was assessed after 3 months and classified as good for Rankin Scale (RS) scores of 0 to 3 and poor for RS scores of 4 or 5 and death. RESULTS: Nine patients (21%) recovered to RS scores 0 or 1, 17 (40%) to scores of 2 or 3, and 7 (16%) to scores of 4 or 5. Ten patients (23%) died. Outcome was good in 17 patients (80%) with MCA occlusions, in 3 patients (33%) with ICA, and in 5 patients (50%) with BA occlusions. Good outcome was associated with an initial NIHSS score of <20 (P<0.001), improvement by 4 or more points on NIHSS score within 24 hours (P=0.001), and vessel recanalization (P=0.02). Recanalization was more likely if LIT was started within 4 hours (P=0.01). Symptomatic cerebral hemorrhage occurred in 2 patients (4.7%). CONCLUSIONS: LIT was most efficacious in patients with MCA and BA occlusions when the initial NIHSS score was less than 20 and when treated within 4 hours. It is of limited value in patients with distal ICA occlusions.     

Filtration of diaspirin crosslinked hemoglobin into lung and soft tissue lymph

Diaspirin crosslinked hemoglobin (DCHb) is a new blood substitute manufactured from human blood. To evaluate its microvascular filtration properties, we infused DCLHb into unanesthetized sheep (10%, 20 ml/kg) and measured the flow and composition of lung and soft tissue lymph. For comparison, we also infused human serum albumin (HSA; 10%, 20 ml/kg). DCLHb raised systemic and pulmonary arterial pressures from baseline values of 83 +/- 7 and 13 +/- 2 mm Hg, respectively, to peak values of 113 +/- 9 and 26 +/- 3 mm Hg (p < 0.05 versus baseline). These increases were significantly greater than those associated with HSA, which raised systemic and pulmonary arterial pressures from baseline values of 86 +/- 4 and 13 +/- 2 mm Hg, respectively, to peak values of 97 +/- 3 and 21 +/- 7 mm Hg (p <= 0.05 versus baseline and versus DCLHb). These differences reflect the known pressor properties of DCLHb. Accordingly, DCLHb raised lung and soft tissue lymph flows to peak values of 12.2 +/- 3.8 and 1.6 +/- 0.7 ml/30 min, respectively, while HSA raised lung and soft tissue lymph flows to peak values of 7.5 +/- 4.8 and 4.6 +/- 1.9 ml/30 min, respectively (p <= 0.05 versus DCLHb). The half-times of DCLHb equilibration from plasma into lung and soft tissue lymph of 1. 0 +/- 0.3 and 2.1 +/- 1.1 h, respectively, were significantly faster than HSA equilibration half-times of 3.1 +/- 0.2 and 3.8 +/- 0.9 h. Filtration differences between DCLHb and HSA appear to be due to the pressor properties DCLHb.     

Emergency identification and treatment of acute ischemic stroke

In this review we describe the pathophysiology of cerebral ischemia and its implications for potential therapy. We summarize the results of recently completed trials of acute stroke intervention and explore some of the controversy surrounding thrombolysis for acute stroke. We also introduce the key concepts of neuroprotection and its therapeutic possibilities. Finally, we discuss the delays that may occur in the emergency evaluation and management of acute ischemic stroke and suggest some methods to expedite the process.     

Effect of endothelin-3 on blood pressure in conscious spontaneously hypertensive [SHR] and DOCA-salt hypertensive rats

The aim of the study was to investigate blood pressure responses and changes in heart rate after bolus administration of endothelin-3 [ET-3] in conscious, freely moving SHR and WKY rats and DOCA-salt hypertensive and normotensive Wistar rats. The effect of ET-3 on blood pressure and heart rats was investigated for four doses equal to 250 ng, 500 ng, 1000 ng and 2000 ng of ET-3. Our study shows that in experimental models of hypertension changes in blood pressure were predominantly characterized by the pronounced hypotensive phase with no significant raises in blood pressure. In normotensive animals cardiovascular responses to ET-3 were biphasic, with initial depressor phase followed by long-lasting, significant pressor effect.     

Altered influence of polymorphonuclear leukocytes on coagulation in acute ischemic stroke

A photoreactive alpha-D-glucose probe has been designed for the specific detection of carbohydrate binding proteins (CBPs). The probe consists of four parts: (i) an alpha-D-glucose moiety; (ii) the digoxigenin tag; (iii) the photoreactive cross-linker; and (iv) the lysyl-lysine backbone. After incubation with lectins in the dark, the probe is activated and cross-linked to the CBPs after being treated by several flashes. Using this method we have identified a new alpha-D-glucose CBP of M(r) = 33,000, termed CBP33, in the nuclei of rats exposed to transient immobilization stress. Monoclonal antibodies were raised against the partially purified protein and subsequently used to enrich CBP33. It was purified (> 2400-fold) to apparent homogeneity from a 0.6 M nuclear salt extract by two subsequent affinity chromatography steps (antibody-affinity as well as alpha-D-glucose affinity column).     

Reliability of hemorrhagic transformation diagnosis in acute ischemic stroke

Vascular malformations of the upper extremity continue to be a therapeutic challenge to the hand surgeon. In the past 22 years, the authors treated 17 patients with major vascular malformations of the upper extremity. The lesions were evaluated with the aid of plain radiographs, angiography, and histology. Thirteen of the patients were female and 4 were male. The average age at treatment was 18 years, ranging from birth to 64 years. The average follow-up period was 12 years, ranging from 4 months to 36 years. The main indications for surgery were pain, progressive enlargement, neurologic compromise, diminished function, or a combination of these. The progression of these lesions under observation led to surgical management in all cases. A total of 36 excisions, 3 embolizations, and 4 amputations were done. Postoperative angiograms were obtained in selected individuals. Diffuse lesions defied total surgical removal. Recurrence and persistence was evident in 12 of the 17 patients. A knowledge of the progressive nature of these lesions and the need for long-term observation are the keystones to the successful management of these challenging yet unresolved problems.     

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.     

Characterization of the hemodynamic response to intravenous diaspirin crosslinked hemoglobin solution in rats

Diaspirin crosslinked hemoglobin solution (DCLHB) has potential for clinical use as an oxygen-carrying solution because of its excellent oxygen transport properties and biochemical stability. The present study characterizes the effects of intravenous infusions of 0.625-40 mL/kg (62.5-4000 mg/kg) DCLHb on mean blood pressure (MAP) and heart rate (HR) in conscious rats. DCLHb at all doses tested except 62.5 mg/kg was associated with an immediate increase in MAP (25-30% above baseline) that peaked between 20-30 minutes after infusion and returned to baseline within 120-300 minutes in a dose-dependent manner. Maximum MAP achieved was in the range of 129 +/- 7 to 140 +/- 7 mm Hg and there was no statistically significant difference in the response between doses. HR responded in a reciprocal manner to changes in MAP. Volume- and oncotic-matched infusions of LR and albumin did not alter MAP or HR. Slow infusion (0.34 mL/min) of DCLHb appeared to blunt the magnitude of the pressor response when compared to bolus injection (< 10 sec). DCLHb administration is associated with a pressor response that is not due to volume load, oncotic pressure, or rate of infusion, suggesting that it is intrinsic to the modified hemoglobin molecule and pharmacologic in nature.