Broad-spectrum and selective serine protease inhibitors prevent expression of platelet-derived growth factor-BB and cerebral vasospasm after subarachnoid hemorrhage: vasospasm caused by cisternal injection of recombinant platelet-derived growth factor-BB

BACKGROUND AND PURPOSE

Plasma serine protease cascade, including the complement system and thrombin, is activated in the subarachnoid space during the acute phase after subarachnoid hemorrhage (SAH). To examine the effect of protease cascade-based inflammation and subsequent vascular repair in the development of cerebral vasospasm, we examined the effect of 2 synthetic serine protease inhibitors-FUT-175, an inhibitor of thrombin and the complement system, and argatroban, a selective inhibitor of thrombin-on the development of cerebral vasospasm in a rabbit SAH model.

METHODS

One hundred Japanese White male rabbits were used in the study. The SAH was simulated by a single injection of autologous arterial blood into the cisterna magna. To evaluate the development of cerebral vasospasm, the caliber of the basilar artery was measured on x-ray film before and at 2 days after SAH. Nine groups of rabbits (n=6 each) were treated with continuous intravenous injection of FUT-175 (2.5, 5, 10, or 20 mg/d), argatroban (1.25, 2.5, or 5 mg/d), or the same amount of saline (vehicle) for 48 hours, starting 40 minutes after SAH. Two days after SAH, the expression of homodimer of platelet-derived growth factor-BB (PDGF-BB) in the basilar artery was examined with immunohistochemical techniques. In 20 normal rabbits, 5 microg of recombinant PDGF-BB or vehicle was injected into the cisterna magna, and the basilar arteries were examined on angiograms for 48 hours.

RESULTS

Significant differences were observed in the caliber of the basilar arteries between the vehicle group and the groups with the 3 larger doses of FUT-175 (vehicle, 52+/-5.0%; 5 mg, 79+/-5.7%; 10 mg, 80+/-2.5%; 20 mg, 80+/-3.7%) and between the vehicle group and the groups with the 2 larger doses of argatroban (vehicle, 52+/-6.4%; 2.5 mg, 81+/-9.0%; 5 mg, 85+/-4.1%) (P<0.05). In the histological examination, administration of effective doses of FUT-175 or argatroban suppressed the expression of PDGF-BB in the endothelial and medial smooth muscle cell layers. Exogenous PDGF-BB caused delayed and prolonged vasoconstriction on normal basilar arteries.

CONCLUSIONS

Activation of the serine protease cascade and/or thrombin after SAH was demonstrated to play an essential role in the development of cerebral vasospasm. The expression of PDGF-BB-like protein in the arterial walls correlated with the development of cerebral vasospasm. Elevated PDGF-BB level in the subarachnoid space was found to induce delayed and chronic vasoconstriction.

Prolonged mild hypothermia therapy protects the brain against permanent focal ischemia

BACKGROUND AND PURPOSE

The efficacy of hypothermic intervention for permanent focal ischemia has yet to be clarified. This study investigated the effect of a prolonged moderate or mild hypothermia on permanent focal ischemia in rats.

METHODS

Two permanent focal ischemia models in male Sprague-Dawley rats were used. Moderate (30 degrees C, in experiment 1) or mild (33 degrees C, in experiment 2) hypothermia was achieved at the time of the induction of focal ischemia and was maintained for 2 hours under general anesthesia. Thereafter, the hypothermic condition was maintained by means of a cold room for a total of 24 hours. The infarct volume and neurological function were analyzed for a maximum of 21 days and compared with that of the normothermia group. Regional cerebral blood flow was monitored for 6 hours in the ischemic core and penumbra region.

RESULTS

In experiment 1, the total infarct volume in the normothermic group was 368+/-59 mm(3); in contrast, it was significantly smaller in the hypothermia group: 169+/-33 mm(3) at 48 hours (mean+/-SEM, P:<0.05). In experiment 2, the infarct volume was 211+/-19 mm(3) in the normothermia group and 88+/-15 mm(3) in the hypothermia group at 21 days (P:<0.05). There were significant differences in neurological function from days 2 through 21 between the two groups. Mean regional cerebral blood flow in the penumbra region increased to a level >50% of baseline.

CONCLUSIONS

Prolonged mild hypothermia suppressed the development of cerebral infarct and neurological deficit chronically after the induction of permanent focal ischemia.

Infarct tolerance accompanied enhanced BDNF-like immunoreactivity in neuronal nuclei

A prolonged period (48 h) of cortical spreading depression (CSD) induced resistance against severe focal cerebral ischemia (infarct tolerance), however, the mechanism behind this is unknown. The infarct tolerance was a transient phenomenon; the resistance increased linearly for the initial 12 days, peaking from 12 to 15 days after a preconditioning of CSD, and was decreased thereafter. This study examined the time course of brain-derived neurotrophic factor (BDNF), heat shock protein (hsp)27 and 70, and glial fibrillary acidic protein (GFAP) expressions after CSD in the brain. Immunohistochemical expression of BDNF, hsp27, hsp70, or GFAP following a prolonged period of CSD induced by KCl-infusion, or following NaCl-infusion was analyzed by regional densitometry for 24 days in the rat neocortex. In addition, BDNF protein was measured quantitatively by two-site ELISA assay in the neocortex (n=6 at each time point). The GFAP expression was elevated in astrocytes (compared to the normal level of immunodensity) during the period peaking on day 3-6 following the CSD. The hsp27 immunoreactivity was also elevated in astrocytes from day 1 to 12 peaking on day 1 and 6, but there was no expression of hsp70 during the period following CSD. The immunoreactivity for BDNF was elevated in neurons from day 0 to 18 peaking on day 1 and 6. The protein levels of BDNF in the neocortex were significantly elevated from day 0 to 12 peaking on days 0 and 6 (compared to the normal level) (P<0.05). Using a laser-scanning confocal imaging system, the BDNF-like immunoreactivity in neuronal nuclei was found to increase linearly peaking on day 12, which correlated well with the development of infarct tolerance. The intranuclear increase in BDNF-like protein might contribute to the induction of infarct tolerance in the brain.

Adenoviral gene transfer of basic fibroblast growth factor promotes angiogenesis in rat brain

Cerebral ischemic disease often causes morbidity and mortality, while the induction of new blood vessels is expected to provide a therapeutic effect in this occlusive cerebrovascular disease. In this study, we utilized two replication-deficient adenoviral vectors containing cDNA from basic fibroblast growth factor (bFGF), a well-known angiogenic factor, and examined whether biological angiogenic activity of adenovirally gene-transferred bFGF could be observed in the rat brain. One vector contained native cDNA from bFGF without the secretory signal sequence and the other contained the same cDNA fused with an interleukin-2 secretory signal sequence. After ventricular administration of these viral vectors, gene-transferred cells demonstrated a high immunoreactivity against the anti-bFGF antibody and a remarkably high concentration of bFGF was detected in the cerebrospinal fluid. A semiquantitative analysis of angiogenic activity revealed that bFGF gene transfer induced angiogenesis in normal rat brains, with a more pronounced angiogenic effect seen with the vector of a secreted form than with the vector without a secretory signal sequence. These results suggest that bFGF gene transfer using these adenoviral vectors might be useful for the treatment of ischemic cerebrovascular disease.

Infarct tolerance induced by intra-cerebral infusion of recombinant brain-derived neurotrophic factor

Neuronal expression of brain-derived neurotrophic factor (BDNF) has been implicated in the mechanism of infarct tolerance (resistance to stroke) (H. Yanamoto et al., Infarct tolerance accompanied enhanced BDNF-like immunoreactivity in neuronal nuclei, submitted to Brain Res.), a process that takes more than 7 days following a preconditioning of repetitive cortical spreading depression (CSD). To investigate whether an elevated level of BDNF protein in the brain solely protects neurons against temporary focal ischemia, recombinant (r)BDNF was infused into the rat neocortex. Recombinant BDNF (or vehicle: saline) was administered into the left neocortex via an implanted osmotic minipump for 2.5, 7, 10 or 14 days pre-ischemia, during ischemia and for 2 days post-ischemia (8 microgram in total) in male Sprague-Dawley rats (n=6 each). Temporary focal ischemia was induced in the left middle cerebral artery (MCA) territory by three-vessel occlusion of bilateral common carotid arteries (CCAs) and MCA for 2 h, and the cerebral infarct volume was analyzed 2 days after ischemia using TTC staining. Regional cerebral blood flow (rCBF) of the left neocortex was monitored after 14 days of intracerebral administration of BDNF or vehicle (n=10 each). The distribution of BDNF following different periods of rBDNF or vehicle-infusion was analyzed using immunohistochemical techniques (n=5 each). In the groups treated with 8 microgram of rhBDNF for 7, 10, or 14 days pre-ischemia, there were significant reductions of neocortical infarct volume compared to in the control or vehicle-treated groups (p<0.05). In the rCBF study, there was no significant change after the infusion of 8 microgram rhBDNF for 14 days. In the histological study, a wide distribution of BDNF-like immunoreactivity in the neuronal nuclei in the ipsilateral neocortex was demonstrated after the infusion of 8 microgram rhBDNF for 14 days. The BDNF-like immunoreactivity in the neuronal nuclei was enhanced at the time that the resistance to stroke was achieved by direct intra-cerebral infusion of exogenous rBDNF. Elucidating the function of the BDNF-like protein located in the neuronal nuclei should reveal a new strategy for neuroprotection against ischemic brain attack in humans.

Combination of intraischemic and postischemic hypothermia provides potent and persistent neuroprotection against temporary focal ischemia in rats

BACKGROUND AND PURPOSE

It is not known whether a combination of intraischemic and postischemic mild hypothermia provides extra neuroprotection and if so, whether the neuroprotection is persistent.

METHODS

Sixty-eight Sprague-Dawley rats were used. In group 1, ischemia and reperfusion were performed under normothermic (N) conditions (control, N-N). In group 2, ischemia was induced and maintained under hypothermic conditions (33 degrees C for 2 hours) and reperfusion was performed under normothermic conditions, H-N. In group 3, both ischemia and reperfusion were performed under hypothermic conditions for an additional 21 hours after the surgery, H-22H. In group 4, ischemia was induced and maintained under hypothermic conditions and reperfusion was performed under hypothermic conditions only for the initial 3 hours (H-3H). In group 5, ischemia was induced and maintained under normothermic conditions and reperfusion was performed under hypothermic conditions (33 degrees C) (N-22H). All rats were perfused 48 hours after the induction of ischemia. In addition, the normothermic or hypothermic therapy used for groups 1, 3, and 4 was performed again, and these rats were killed 30 days after the induction of ischemia. Furthermore, neurological deficits were monitored in groups N-N and H-22H for 4 weeks.

RESULTS

In the H-3H and H-22H groups, the total infarct volume was significantly reduced by 41% or 66%, respectively, assessed 48 hours after ischemia. The significant reduction in group H-22H was again confirmed 30 days after ischemia, ie, 50% reduction was observed. In contrast, the reduction in group H-3H (31%) was not significant. The neurological deficits were significantly more severe in the N-N group than in the H-22H group during week 4.

CONCLUSIONS

The neuroprotective effects against temporary focal ischemia evaluated by infarct volume and neurological functions by the combination therapy with intraischemic and prolonged postischemic mild hypothermia were persistent in rats. Appropriate design of mild hypothermia therapy extending into the late reperfusion period is important to maximize the neuroprotective effects of hypothermia.

[Endovascular surgery for untreated ruptured aneurysm with symptomatic vasospasm]

It is difficult to treat ruptured aneurysms with symptomatic vasospasm. Although direct surgery for such cases is associated with poor outcomes, conservative therapy has the risk of both rerupture and infarction. In two cases of ruptured aneurysms with symptomatic vasospasm, we performed aneurysmal coil embolization with Guglielmi electrodetatchable coils (GDC). At the same time we performed percutaneous transluminal angioplasty (PTA) with papaverine infusion. In both cases, rerupture did not occur and PTA was effective angiographically. A good outcome was achieved in case 1. However, broad cerebral infarction occurred in case 2, in which the patient had shown severe symptomatic vasospasm on admission. In advanced cases, such as in case 2, the outcome is poor. The aneurysm may not be able to be approached before PTA because of severe vasospasm. In such cases, PTA must be performed carefully to avoid aneurysmal rerupture. Intraarterial papaverine infusion is safer than PTA for severe spasm in distal vessels. However the efficacy of papaverine is known to be transient in many cases. It is often difficult to determine the exact relationship between branches and the aneurysm in the presence of vasospasm. In such cases, we recommend that the rupture point be packed and that the aneurysmal neck remain unpacked. After vasospasm is cured and good general condition has been recovered, direct surgery can be performed. In summary, endovascular surgery is an effective option for treatment of ruptured aneurysm with symptomatic vasospasm.

Prevention of neointimal formation by a serine protease inhibitor, FUT-175, after carotid balloon injury in rats

BACKGROUND AND PURPOSE

In vivo and vitro studies revealed the activation of thrombin and the complement system in vascular lesion formation during the process of atherosclerosis, along with pathological proliferation of smooth muscle cells. We examined the effect of the synthetic serine protease inhibitor FUT-175 (developed as a potent inhibitor of thrombin and the complement system) on vascular lesions using balloon dilatation-induced neointimal formation in the carotid artery of rats.

METHODS

Sprague-Dawley (SD) rats underwent balloon dilatation injury of the left carotid artery to induce neointimal formation. Three groups of these rats (n=8, each) were treated with daily intraperitoneal injections of 1 of the following doses of FUT-175: 0.5, 1.0, or 2.0 mg/d in 1 mL of saline for 7 consecutive days. The control group (n=8) was similarly treated with 1 mL of saline for 7 days. The injections were started immediately after balloon injury. Two weeks after the injury, the left carotid arteries were perfusion-fixed, and the areas of the neointimal and medial layer were analyzed under a microscope.

RESULTS

A morphometric analysis revealed that there were significant differences in the intima-media ratio between the 4 groups treated with vehicle (saline) or a low, medium, or high dose of FUT-175 (1.45+/-0.11, 1.08+/-0.06, 0.71+/-0.04, or 0.32+/-0.04, respectively). This suppression was achieved in a dose-dependent manner by the administration of FUT-175 after balloon injury. In the histological study, it was demonstrated that FUT-175 suppresses the production of platelet-derived growth factor (PDGF)-BB in the neointima and the medial smooth muscle cell layer.

CONCLUSIONS

After balloon injury activated proteases that were inhibited by FUT-175 were demonstrated to have an essential role in the development of the pathological thickening of the arterial wall.

Gene transfer of human prostacyclin synthase prevents neointimal formation after carotid balloon injury in rats

BACKGROUND AND PURPOSE

A disordered proliferative process in the vascular wall is thought to underlie the pathogenesis of restenosis after percutaneous transluminal angioplasty and carotid endarterectomy. A growth inhibitory property of overexpressed prostacyclin (PGI2) synthase (PGIS) was recently implicated in the pathological proliferation of vascular smooth muscle cells (VSMC) in vitro. Here, we investigated the effects of increased PGI2 synthesis on the pathological proliferation of VSMCs.

METHODS

The cDNA encoding human PGIS was transfected into endothelium-denuded rat carotid arteries after arterial balloon injury with the use of hemagglutinating virus Japan (HVJ). HVJ liposome vector complex without PGIS cDNA was used for vehicle control. The level of 6-keto PGF1alpha, a stable hydrolyzed metabolite of PGI2, the histological distribution of the immunoreactivity for human PGIS and the ratio of neointimal/medial area were analyzed.

RESULTS

In the analyses of 6-keto PGF1alpha, the level in the carotid arteries was significantly elevated 3 days after PGIS expression-vector transfection compared with that in the arteries after vehicle transfection. Seven days after human PGIS expression-vector transfection, the PGIS cDNA-transfected neointimal cells were strongly positive for human PGIS immunoreactivity in 81% sections examined. Fourteen days after the injury, the ratio of neointimal/medial area was 1.2+/-0.4 in the PGIS expression-vector transfected group, which was significantly smaller than that of the vehicle control group, 1.7+/-0.5; P<0.01.

CONCLUSIONS

It was thus demonstrated that the gene transfer of human PGIS expression-vector into rat carotid arteries resulted in the increased production of human PGI2 in the vascular wall, the expression of human PGIS in the developing neointima and significantly inhibited the neointimal formation generated after balloon injury.

Endosaccular embolization for internal carotid artery aneurysms at the c3 portion

SUMMARY

Direct surgery for the aneurysms at the C3 portion of the internal carotid artery (ICA) requires relatively complicated procedures. We present three patients with this aneurysm who underwent endovascular embolization. The remodelling technique was utilized in two of these patients with unruptured aneurysms. Sufficient obliteration was achieved in every case. Endovascular embolization may be an important alternative for ICA C3 aneurysms.

Three-vessel occlusion using a micro-clip for the proximal left middle cerebral artery produces a reliable neocortical infarct in rats

We demonstrate a new three-vessel occlusion model of temporary focal ischemia in Sprague-Dawley rats (n=13). Under a surgical microscope, bilateral carotid arteries and the left middle cerebral artery (MCA) were occluded for 2 h using a snare for the neck and a micro-clip for the MCA. The reduction of regional cerebral blood flow (rCBF) monitored by laser Doppler flowmetry was 28% on average compared to the preischemic control value (100%) during ischemia. At that level of CBF reduction, there was no thrombus formation in the proximal MCA trunk, and a full recovery of rCBF was confirmed in the ischemic core within 5 min of reflow. Two days later, the cerebral infarct was limited to the neocortex, and the size and variability of the infarct are considered feasible for the assessment of any therapeutic challenge against the ischemic damage due to temporary focal ischemia in this model.

Induction of infarct tolerance by platelet-derived growth factor against reversible focal ischemia

Nerve growth factor, brain-derived neurotrophic factor, and other neurotrophic factors have been reported to have neuroprotective effects against global ischemia. To investigate whether the homodimer of platelet-derived growth factor B-chain (PDGF-BB) can protect neurons against focal temporary ischemia, PDGF-BB was administered to the rat brain for a prolonged period prior to, during, and after ischemia, since PDGF-BB protected rat neurons from global ischemia in our previous study. A total of 82 male Sprague-Dawley rats were used. Recombinant PDGF-BB, or saline was administered into the left neocortex via an implanted osmotic pump for 3 days (1.2 microg in total), 7 days (2 microgram or 4 microgram in total), or 14 days (4 microgram in total) pre-ischemia and 2 days post-ischemia. In an additional group, PDGF-BB (4 microgram in total) was administered for 14 days by osmotic pump and focal ischemia was induced after an additional 7-day interval following removal of the pump. Focal temporary ischemia was induced in the left MCA territory by bilateral CCA and MCA occlusion for 2 h. All rats were sacrificed 2 days after ischemia and the volume of cerebral infarct was analyzed using TTC staining. In a separate set of animals, regional cerebral blood flow (rCBF) was monitored by the hydrogen clearance method and laser Doppler flowmetry (LDF) of the neocortex after 14 days of intracerebral administration of PDGF-BB or saline. In the group receiving PDGF-BB (4 microgram in total) for 7 or 14 days pre-ischemia, there was a significant reduction of neocortical infarction compared to that in the control or saline-infused group. The size of cerebral infarct was smallest in the group that received PDGF-BB for 14 days, when ischemia was induced 7 days after removal of the pump. Regarding rCBF measurement, there were no significant differences in groups receiving PDGF-BB or saline infusion for 14 days. The potent neuroprotective effect of PDGF-BB on global ischemia was also demonstrated in the focal ischemia model. However, prolonged intracerebral infusion for 7 to 14 days was necessary to achieve a significant reduction of infarct volume. Neuroprotection was not due to increased collateral flow during ischemia.

Infarct tolerance against temporary focal ischemia following spreading depression in rat brain

A rat model of ischemic tolerance is useful for studying the intrinsic cellular mechanism of resistance to cerebral ischemia. Many types of preconditioning in the brain have been reported to induce ischemic tolerance; however, evaluation of their neuroprotective effect is primarily limited to differences in counts of surviving cells. A lesser but still large number of neurons die in the neocortex after global ischemia following ischemic tolerance. This study addressed the issue of whether any type of preconditioning could elicit a tolerance that limited the size of cerebral infarct against temporary focal ischemia. Cortical spreading depression was induced for a prolonged period and, after various intervals, the stress of temporary focal ischemia was evaluated in rats. Ten groups of male rats (n=8 each) were studied. In the first group, temporary focal ischemia was induced by occlusion of three vessels (bilateral carotid arteries and left middle cerebral artery, MCA) for 2 h (control). In the second to seventh groups, cortical spreading depression was generated by continuously infusing 4 M potassium chloride (KCl)(1.0 microliter l/h for 2 days) into the left neocortex via an osmotic pump. On days 6, 9, 12, 15, 21 and 24 (day 0=day of pump removal), temporary focal ischemia was induced in one of these groups. In the other three groups, saline was infused instead of KCl, and on day 6, 12 or 21, temporary focal ischemia was induced. All rats were sacrificed 2 days after the ischemia and the infarct volume was analyzed using TTC staining of brain slices. In a separate group of animals, regional cerebral blood flow (rCBF) at the periinfarct area (penumbra) was monitored before and during the ischemia with a laser-Doppler flowmetry (LDF) system on day 12 following saline (n=5) or KCl infusion (n=5) for 48 h. To obtain the absolute rCBF value before ischemia following saline (n=5) or KCl infusion (n=5), hydrogen clearance was examined in the same cortex under the same anesthesia. The cerebral infarct volume was gradually reduced as the interval between the induction of the spreading depression and the induction of temporary focal ischemia was extended. There was a significant reduction in infarct size between the control and the groups in which ischemia was induced on day 12 or 15. There was no significant difference in the preischemic or intraischemic rCBF between the saline and KCl-infused groups. The preconditioning method was demonstrated to limit the size of cerebral infarct after temporary focal cerebral ischemia; tolerance for cerebral infarct developed after an extended interval following a long period of spreading depression.

Systemic administration of the potassium channel activator cromakalim attenuates cerebral vasospasm after experimental subarachnoid hemorrhage

OBJECTIVE

Cerebral vasospasm is a primary complication after aneurysmal subarachnoid hemorrhage (SAH). Recent evidence indicates that the activation of potassium (K+) channels may be of benefit in relieving spastic constriction. The present study examined the effects of systemic administration of a K+ channel activator, cromakalim, on cerebral vasospasm after experimental SAH.

METHODS

Experimental SAH was performed in rabbits by injecting autologous blood into the cisterna magna. Intravenous injections of cromakalim or vehicle were administered twice daily with the first injection administered 1 hour after induction of SAH. Animals were killed by perfusion-fixation 48 hours after SAH. Basilar arteries were removed and sectioned, and the luminal cross-sectional areas were measured.

RESULTS

Experimental SAH induced cerebral vasospasm in untreated and vehicle-treated animals. Cromakalim attenuated cerebral vasospasm in a dose-dependent manner. This effect achieved statistical significance at doses of 0.1 and 0.3 mg/kg.

CONCLUSION

These results support the concept that targeting vascular K+ channels can be of benefit in preventing the development of cerebral vasospasm. The findings also indicate that cromakalim represents a potential therapeutic agent for the treatment of cerebrovascular pathophysiology after SAH.

Differential hydroxylation of salicylate in core and penumbra regions during focal reversible cerebral ischemia

BACKGROUND AND PURPOSE

Free radical-mediated damage during and/or after cerebral ischemia is thought to participate in the elaboration of stroke-related injury. To elucidate the role of this mechanism in cerebral damage, the study presented herein sought to clarify the spatial and temporal features of the free radical response to transient ischemia. With use of a reproducible model of in vivo focal ischemia/reperfusion, the time course of salicylate hydroxylation was measured in ischemic core and penumbra regions.

METHODS

Transient focal cerebral ischemia was produced in Sprague-Dawley rats by occluding both carotid arteries and one middle cerebral artery for 3 hours, followed by reperfusion. Cerebral reperfusion was confirmed by visual inspection and iodo[14C]antipyrine autoradiography. A microdialysis probe was placed stereotactically in either the ischemic core or ischemic penumbra of the frontoparietal cortex; the probe was perfused with salicylate, and dialysate samples were analyzed by high-performance liquid chromatography for salicylate hydroxylation products.

RESULTS

Salicylate hydroxylation was significantly increased during ischemia and was further increased during 6 hours of reperfusion in the penumbra compared with sham controls. In comparison, a delayed increase in hydroxylation was observed within the ischemic core region only after 3 hours of reperfusion.

CONCLUSION

A differential generation of salicylate hydroxylation occurs in core and penumbra regions in association with focal ischemia/reperfusion of the rat neocortex. The early and progressive response in the penumbra suggests that free radical mechanisms may be continuously active in the aggravation of injury in the ischemic penumbra during ischemia and reperfusion. In contrast, the relatively delayed onset of hydroxylation in the core region indicates that this mechanism participates primarily in the late stages of ischemic injury in densely ischemic tissue. These findings are consistent with the concept that the role of free radicals in cerebral injury may differ qualitatively and/or quantitatively in areas of total and partial cerebral perfusion.

Platelet-derived growth factor-BB, but not -AA, prevents delayed neuronal death after forebrain ischemia in rats

Our previous studies demonstrated coordinate expression of platelet-derived growth factor (PDGF) -B chain and beta-receptor in neurons at risk in the rat brain with focal ischemia. To clarify a role of the -B chain in the brain further, we examined whether PDGF-A or -B chain protects CA1 pyramidal neurons from delayed neuronal death after forebrain ischemia in rats. Pretreatment with PDGF-BB, but not -AA, at 120 ng/d for 2 days until forebrain ischemia was performed markedly ameliorated delayed neuronal death in CA1 pyramidal neurons on day 7 after ischemia. This neuroprotective effect of PDGF-BB was dose-dependent, and pretreatment with PDGF-BB at 240 ng/d showed almost complete inhibition of delayed neuronal death. In contrast, posttreatment with PDGF-BB at 120 ng/d starting 20 minutes after ischemia demonstrated no significant neuroprotective effect. The current study established marked neuroprotective actions of PDGF-BB in ischemic neuronal damage.

Mild postischemic hypothermia limits cerebral injury following transient focal ischemia in rat neocortex

Intraischemic mild hypothermia has been shown to attenuate cerebral infarction occurring after transient focal ischemia. In contrast, the capacity of mild hypothermia to provide a protective effect when administered postischemically has not been clearly defined for transient focal events such as occur in many types of stroke. The present study addressed this issue by investigating the influence of timing and duration of mild hypothermia on cerebral infarction in a rat model of reversible focal ischemia. Sprague-Dawley rats (n = 45) were subjected to 3 h of focal neocortical ischemia by occluding reversibly one middle cerebral artery and both carotid arteries. Mild hypothermia was established after reperfusion and maintained for brief (1 h) or prolonged (21 h) periods. Animals were sacrificed 24 or 48 h after ischemia. A significant reduction (32%) in the volume of infarction was obtained when hypothermia was established immediately after reperfusion and maintained for a prolonged (21 h) period. In contrast, immediate but brief (1 h) hypothermia did not reduce infarction volume. Delaying hypothermia until 30 min post reperfusion and maintaining it for 21 h reduced infarction volume by 22%; however, this effect did not achieve statistical significance. These findings demonstrate that mild postischemic hypothermia is capable of protecting against cerebral injury following transient focal ischemia but that prolonged hypothermia is required to achieve this effect. These findings are consistent with increasing evidence that the window of therapeutic opportunity after transient focal ischemia is rather brief and that critical mechanisms involved in this form of ischemic injury remain activated over a rather lengthy postischemic interval.

Effects of protease inhibitor and immunosuppressant on cerebral vasospasm after subarachnoid hemorrhage in rabbits

The possible role of the immune-defense system in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH) was investigated in rabbits. We used a synthetic serine protease inhibitor, gabexate mesilate (GM), a glucocorticoid, betamethasone sodium phosphate (B-P), and an immunosuppressant, ciclosporin (Cyclosporin A, CYA), to prevent cerebral vasospasm. These agents were administered intra-venously every 12 hours for three injections, starting 20 minutes after SAH. In the group treated with GM, B-P, or CYA, there were no statistically significant differences in arterial calibers between treated and untreated controls on day 2. The synthetic serine protease inhibitor, FUT-175 has been reported to prevent cerebral vasospasm when the treatment is started 20 minutes after SAH in rabbits [38]. In rabbits treated with FUT-175 at different starting times from 3 to 6 hours, reductions in arterial caliber on day 2 were significantly prevented in each group. The contrasting effects of the two serine protease inhibitors, GM and FUT-175, are discussed.

Cerebral vasospasm caused by cisternal injection of polystyrene latex beads in rabbits is inhibited by a serine protease inhibitor

During subarachnoid hemorrhage (SAH), coagulated blood in the subarachnoid space may be regarded as foreign by the immune system. To investigate how cerebral arteries are affected by activation of the host immune system, foreign body, polystyrene latex beads were injected into the cerebrospinal fluid (CSF) space of rabbits, and the caliber changes of the basilar arteries were studied for 7 days by angiography. Prolonged arterial narrowing peaking on day 2 was observed after cisternal injection of the beads. The increase in peak narrowing correlated with an increase in the number of beads injected. The course of the change in vessel caliber over 7 days was similar to that seen in cerebral vasospasm caused by SAH. Also investigated was the preventive effect of the synthetic serine protease inhibitor, FUT-175 on the arterial narrowing caused by the cisternal injection of the latex beads. The administration of FUT-175 significantly prevented latex beads-induced vasospasm (p < 0.01). The possible role of a non-specific immune response is discussed, and also the role of the serine protease cascades in the development of cerebral vasospasm.

Preventive effect of synthetic serine protease inhibitor, FUT-175, on cerebral vasospasm in rabbits

The effect of the synthetic multiserine protease inhibitor FUT-175 on cerebral vasospasm after subarachnoid hemorrhage (SAH) was investigated in rabbits. The SAH in rabbits was simulated by a single injection of autologous arterial blood into the cisterna magna, and, for 7 days, the caliber of each basilar artery was examined several times via angiogram. In 10 SAH rabbits, the peak of the arterial narrowing was observed on Day 2. In this model, the effect of intravenous administrations of FUT-175 was examined. Twenty-seven SAH rabbits were randomly divided into three groups, and 3 doses of 1, 2, or 3 mg of FUT-175 were administered intravenously. Angiographic arterial narrowing on Day 2 in nontreated SAH rabbits (Control) was 35% compared with 21, 5, and 14% in rabbits treated with a total of 3 (Group A; n = 9), 6 (Group B; n = 13), and 9 mg (Group C; n = 5) of FUT-175, respectively. There were statistically significant differences in the arterial calibers between Group A and the Control on Days 1 and 2, between Group B and the Control from days 1 to 4, and between Group C and the Control from days 1 to 4. In three other rabbits, after vasospasm reached its maximum on Day 2, no vasodilatory effect was observed when a total of 6 mg of FUT-175 was administered intravenously. The results indicate that the inhibition of the plasma serine protease cascades at an early stage of SAH prevents the development of cerebral vasospasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Therapeutic trial of cerebral vasospasm with the serine protease inhibitor, FUT-175, administered in the acute stage after subarachnoid hemorrhage

The therapeutic effect of the synthetic serine protease inhibitor, FUT-175, on cerebral vasospasm after subarachnoid hemorrhage (SAH) was investigated. Twenty-three patients with severe SAH who were admitted between February and July 1990 and who underwent surgery within 48 hours of the initial aneurysmal rupture were treated with an intravenous administration of FUT-175 soon after the operation. The patients were divided randomly into three groups, each receiving a different dose of FUT-175 (Group A, 20 mg every 12 hours for 4 days; Group B, 20 mg every 6 hours for 4 days, Group C, 40 mg every 6 hours for 4 days). The results were compared with another group of twenty-two patients with severe SAH who were admitted before February 1990 and received equivalent treatment, except they were not treated with FUT-175. In 64% of all the patients treated with FUT-175 (Groups A, B, C), and in 85% of those treated with higher doses of FUT-175 (Groups B and C), there was no spasm or only mild vasospasm on the angiogram. The incidence of a delayed ischemic neurological deficit significantly decreased from 55% in the control group to 13% in all patients treated with FUT-175 and to 7% in the patients treated with higher doses (P less than 0.05). The incidence of cerebral infarction resulting from vasospasm significantly decreased from 43% in the control group to 9% in patients treated with FUT-175. In the patients treated with higher doses of FUT-175 (Groups B and C), none developed cerebral infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of glycogen and ATP contents of the major cerebral arteries after experimentally produced subarachnoid haemorrhage in the dog

The contents of glycogen and ATP in the major cerebral arteries were examined in dogs undergoing subarachnoid haemorrhage (SAH). SAH was produced by a single injection of autologous arterial blood (1 ml/kg body weight) into the cisterna magna. Vertebral angiograms showed biphasic basilar arterial narrowings after the injection of blood: Early arterial narrowing occurred immediately after the injection and continued for a few hours. Late arterial narrowing occurred from Day 1 to Day 14 of post-SAH period, and recovered to the normal level on Day 21 of post-SAH period. The content of glycogen in the large pial arteries significantly decreased from Day 1 to Day 14 and returned to the control level on Day 21. The content of ATP in the large pial arteries also decreased from Day 1 to Day 7 and returned to the control level on Day 14. These results show that energy stores in the major cerebral arteries might be diminished during late arterial narrowing.

Red blood cells are essential for late vasospasm following experimentally induced subarachnoid hemorrhage in dogs

The in vivo spasmogenic activity of various blood components was examined in dogs. Each blood fraction was injected into the cisterna magna at 0.5 or 1.0 ml/kg body weight, after the removal of 0.5 ml/kg body weight of cerebrospinal fluid, and vertebral angiography was then performed. Whole blood induced both early and late arterial spasm. Platelet-rich and platelet-poor plasma produced only early spasm, and no arterial narrowing was observed on days 1, 3, and 7 after injection. On the contrary, intracisternal injection of washed red blood cells (0.5 ml/kg body weight) produced no arterial narrowing for 6 hours after injection and induced moderate arterial narrowing on days 1, 3, and 7 after injection. Hemolysate (a 10-gm/dl concentration of hemoglobin) produced prolonged monophasic arterial narrowing after injection. These results imply that red blood cells are required for late, prolonged arterial narrowing after experimental subarachnoid hemorrhage.

[Pineal metastasis--a case report and a review of literature]

This is a report of a rare case of pineal metastasis from gastric adenocarcinoma. A 75-year-old male with a previous medical history of subtotal gastrectomy for cancer of the cardia was diagnosed as having hydrocephalus 6 months later. After undergoing a V-P shunt operation, he was transferred to Kyoto First Red Cross Hospital. The patient had neurological abnormalities: bilateral paralysis of upward eye movement, and bilateral sluggish reflex to light. Ten days later the patient suddenly fell into a coma due to intratumoral hemorrhage. The patient soon regained consciousness and received Cobalt-therapy. However he died two months later of pulmonary malfunction due to pulmonary metastasis. An autopsy revealed a pineal tumor metastasized from gastric adenocarcinoma. The tumor involved the body of the pineal gland, and was expanded having a sharply defined margin which extended to the posterior portion of the third ventricle and the bilateral basal ganglia.