Single, high-dose intraspinal injection of chondroitinase reduces glycosaminoglycans in injured spinal cord and promotes corticospinal axonal regrowth after hemisection but not contusion.

Chondroitin sulfate proteoglycans (CSPGs) inhibit axonal growth, and treatment with chondroitinase ABC promotes axonal regeneration in some models of central nervous system (CNS) injury. The aims of this study were (1) to compare the spatiotemporal appearance of CSPG expression between spinal cord contusion and hemisection models, and (2) to evaluate chondroitinase treatment effects on axonal regrowth in the two injury models. After hemisection, CSPG-immunoreactivity (IR) in the injury site rose to peak levels at 18 days but then decreased dramatically by 49 days; in contrast, CSPG-IR remained high for at least 49 days after contusion. After hemisection, many anterogradely labeled corticospinal tract (CST) axons remained close to CSPG-rich lesion sites, but after contusion, most CST axons retracted by approximately 1 mm rostral from the rostral-most CSPG-rich cyst. Intraspinal injection of chondroitinase at 0, 1, 2, and 4 weeks following injury dramatically reduced CSPG-IR in both injury models within 4 days, and CSPG-IR remained low for at least 3 weeks. After the chondroitinase treatment, many axons grew around the lesion site in hemisected spinal cords but not in contused spinal cords. We propose that improved axonal growth in hemisected spinal cords is due to decreased inhibition resulting from degradation of CSPGs located adjacent to severed CST axons. However, in spinal cord contusions, retracted CST axons fail to grow across gliotic regions that surround CSPG-rich injury sites despite efficient degradation with chondroitinase, suggesting that other inhibitors of axonal growth persist in the gliotic regions.

Runx3 controls the axonal projection of proprioceptive dorsal root ganglion neurons.

Dorsal root ganglion (DRG) neurons specifically project axons to central and peripheral targets according to their sensory modality. The Runt-related genes Runx1 and Runx3 are expressed in DRG neuronal subpopulations, suggesting that they may regulate the trajectories of specific axons. Here we report that Runx3-deficient (Runx3(-/-)) mice displayed severe motor uncoordination and that few DRG neurons synthesized the proprioceptive neuronal marker parvalbumin. Proprioceptive afferent axons failed to project to their targets in the spinal cord as well as those in the muscle. NT-3-responsive Runx3(-/-) DRG neurons showed less neurite outgrowth in vitro. However, we found no changes in the fate specification of Runx3(-/-) DRG neurons or in the number of DRG neurons that expressed trkC. Our data demonstrate that Runx3 is critical in regulating the axonal projections of a specific subpopulation of DRG neurons.

Direct percutaneous transluminal angioplasty for acute middle cerebral artery trunk occlusion: an alternative option to intra-arterial thrombolysis.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the safety and efficacy of direct percutaneous transluminal angioplasty (PTA) for patients with acute middle cerebral artery (MCA) trunk occlusion. METHODS: Over the past 9 years, a total of 70 patients with acute MCA trunk occlusion were treated with intra-arterial reperfusion therapy. In the last 5 years, 34 patients were treated with direct PTA, and subsequent thrombolytic therapy was added if necessary for distal embolization. The other 36 patients, mainly in the first 4 years, were treated with thrombolytic therapy alone and were used as controls. Pretherapeutic neurological status was evaluated with National Institutes of Health Stroke Scale scores. The modified Rankin Scale (mRS) was used to assess clinical outcome at 90 days. RESULTS: There were no significant differences in pretherapeutic National Institutes of Health Stroke Scale score and duration of ischemia between the 2 groups. The rate of partial or complete recanalization in the PTA group was 91.2%, whereas that in the thrombolysis-alone group was 63.9% (P<0.01). The incidence of large parenchymal hematoma with neurological deterioration in the PTA group was 2.9%, while that in the thrombolysis-alone group was 19.4% (P=0.03). Although direct PTA did not improve the rate of favorable outcome (mRS score 0 or 1; 41.7% for the thrombolysis-alone group versus 52.9% for the PTA group; P=0.48), outcome in terms of independence (mRS score 0, 1, 2) was significantly better in the PTA group (73.5%) than in the thrombolysis-alone group (50.0%; P=0.04). CONCLUSIONS: Although definitive conclusions on the comparative merits of these 2 therapies cannot be drawn because of an open trial, direct PTA may be an effective alternative option to intra-arterial thrombolysis for acute MCA trunk occlusion.

Appearance of early venous filling during intra-arterial reperfusion therapy for acute middle cerebral artery occlusion: a predictive sign for hemorrhagic complications.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the correlation between appearance of angiographic early venous filling during intra-arterial reperfusion therapy and posttherapeutic hemorrhagic complications. METHODS: For the past 7 years, 104 patients prospectively underwent superselective local angiography via a microcatheter before and during intra-arterial reperfusion therapy for acute middle cerebral artery occlusion to evaluate the presence or absence of early venous filling. In principle, reperfusion therapy was discontinued just after appearance of early venous filling for fear of hemorrhage. There were 2 types of early venous filling: early filling of the thalamostriate vein from the lenticulostriate arteries and that of the cortical vein from the cortical arteries. RESULTS: Among these 104 patients, 31 (29.8%) had early venous filling: 19 had early filling of the thalamostriate vein, and the other 12 had early filling of the cortical vein. Eight of the 19 patients (42.1%) and 2 of the 12 patients (16.7%) had massive hematoma with neurological worsening, whereas only 1 of the 73 patients (1.4%) without early venous filling had massive hematoma. There was a significant correlation between early venous filling and massive hematoma in both the deep (P<0.0001) and superficial (P=0.0019) middle cerebral artery territories. The sensitivity and specificity of the presence of early venous filling as an indicator of parenchymal hematoma were 71% and 83%, respectively. None of the 31 ischemic areas with early venous filling could escape cerebral infarction. CONCLUSIONS: Appearance of early venous filling may indicate irreversible brain damage and may be a predictive sign for parenchymal hematoma.

Spontaneous regeneration of the corticospinal tract after transection in young rats: collagen type IV deposition and astrocytic scar in the lesion site are not the cause but the effect of failure of regeneration.

In young rats the corticospinal tract regenerated after a single transection of the spinal cord with a sharp blade, but regeneration failed if the transection was repeated to make a more traumatic injury. To identify cells and associated molecules that promote or impede regeneration, we compared expression of collagen type IV, glial fibrillary acidic protein (GFAP), and vimentin immunoreactivity (IR) at the lesion sites in combination with anterograde axonal tracing between animals with two types of transection. Axonal regeneration occurred as early as 18 hours after transection; regenerating axons penetrated vessel-like structures with collagen type IV-IR at the lesion site, while reactive astrocytes coexpressing GFAP- and vimentin-IR appeared in the lesioned white matter. In contrast, when regeneration failed astrocytes were absent near the lesion. By 7 days sheet-like structures with collagen type IV-IR and astrocytic scar appeared in the lesioned white matter and persisted until the end of the observation period (31 days). On the basis of their spatiotemporal appearance, collagen type IV-IR sheet-like structures and the astrocytic scar follow, rather than cause, the failure of regeneration. The major sign, and perhaps cause, of failure of axonal regeneration is likely the prolonged disappearance of astrocytes around the lesion site in the early postinjury period.

Effects of an embryonic repair graft on recovery from spinal cord injury.

It is widely believed that mammalian CNS axons have little regenerative capacity because their environment is non-permissive to regrowth. This viewpoint is based, in large part, on the fact that in virtually all previous studies on regeneration following spinal cord injury, regenerated axonal projections have been few in number, quite short, and considered to be mostly aberrant. As a result, motor recovery has been very limited in both experimental preparations and the human. In this chapter, we describe use of a neonatal, spinally transected animal model in which selected spinal cord segments were carefully replaced with equivalent tissue from embryonic tissue of the same species. We demonstrate that the new spinal environment is indeed permissive, and reconstruction is possible of neural connections, which are similar to the pre-injury, normal projections. Moreover, the distribution and number of regenerated axons are closely related to the extent of functional motor recovery. Our results suggest that contrary to doctrinaire thought, the mammalian CNS possesses a remarkable capacity for regrowth. For this to be efficacious, however, regenerating axons must contact the inherent, pre-injury guidance system, whose cues were used for establishing appropriate neural connections in the developing animal, and are retained in the adult. It is argued that by use of these guidance cues, regenerating axons that traverse the site of a spinal cord injury, can project on to locate their pre-injury pathways and targets, and thereby restore function.

Secretion of tenascin-C by cultured astrocytes: regulation of cell proliferation and process elongation.

Tenascin-C (TNC), an extracellular matrix glycoprotein, is involved in tissue morphogenesis like embryogenesis, wound healing or tumorigenesis. Quiescent astroglia in long-term primary cultures are known to show rapid morphological changes after subculture and serum deprivation/re-addition (SSDR). To elucidate roles of TNC in the morphogenetic processes of cultured astrocytes, we have revealed morphological changes in association with soluble TNC contents in the medium and expression of TNC mRNA, TNC, glial fibrillary acidic protein (GFAP) and integrin beta1, one of its cell surface receptors, in glial cells after SSDR. Soluble TNC in the medium rapidly increased in amount at 4 h when GFAP-positive cells expressed TNC mRNA, TNC and integrin beta1. Cellular proliferation and growth occurred in colonies expressing TNC mRNA, TNC and integrin beta1 during the first 24 h. During the next 24 h, process elongation and cell migration occurred in association with increased GFAP expression and re-elevation of soluble TNC in the medium. Cell bodies became flat and larger with increased GFAP and reduced TNC expression at 72 h, while cultures became confluent with reduced GFAP and TNC expression at 96 h after SSDR. Functional blocking with anti-TNC antibody reduced cell proliferation and induced morphological change from a process-bearing slender shape to a flat and wide shape presumably due to increased cell adhesion. These findings strongly support the idea that endogenous TNC produced and released by astrocytes in response to serum stimulation induces their proliferation and process elongation through a paracrine/autocrine mechanism.

Time-threshold curve determined by single photon emission CT in patients with acute middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: In patients with ischemic stroke, not only the degree of ischemia but also its duration are key determinants of tissue survival. The purpose of this study was to show the synergistic effects of these two factors on tissue survival in humans. METHODS: We retrospectively reviewed findings in 19 patients with middle cerebral artery occlusion who had clearly defined ischemic duration from onset to angiographic complete recanalization and who underwent pretreatment single photon emission CT. Pretreatment single photon emission CT and final CT scans were compared, and hypoperfusion cortices were divided into reversible and irreversible ischemia. Regions of interest were placed in both irreversible and reversible ischemic cortices, and the residual cerebral blood flow was analyzed by side-to-side comparison with a calculated asymmetry index. To show the relationship between the reversibility of ischemia and the ischemic duration/severity, discriminant analyses were conducted. The analyses were conducted separately using data obtained within 3 hours of ischemic duration and data obtained more than 3 hours after ischemic duration. RESULTS: Within 3 hours of ischemic duration, analysis revealed a discriminant line of asymmetry index (%) = 21.53 time (h) - 19.15. After more than 3 hours of ischemic duration, it revealed a discriminant line of asymmetry index = 0.50 time + 48.27. These discriminant lines rose rapidly within the first 3 hours after stroke onset and thereafter reached almost a plateau level. CONCLUSION: These pilot data suggest urgency for treatment, less need for triage based on cerebral blood flow measurement during the first few hours, and more time to triage based on cerebral blood flow measurement for patients with later presentations.

Combined direct percutaneous transluminal angioplasty and low-dose native tissue plasminogen activator therapy for acute embolic middle cerebral artery trunk occlusion.

BACKGROUND AND PURPOSE: In embolic middle cerebral artery (MCA) trunk occlusion, recanalization with direct percutaneous transluminal angioplasty (PTA) may be preferable to time-consuming thrombolysis. However, distal embolization with small crushed fragments is a complication of direct PTA. We prospectively evaluated combined direct PTA and low-dose native tissue plasminogen activator (t-PA) therapy for acute embolic MCA trunk occlusion. METHODS: Fifteen patients underwent direct PTA. The embolus was successfully crushed in 12, who received subsequent native t-PA infusion. Direct PTA was performed with a balloon catheter, which was advanced into the occlusion site and inflated several times until recanalization was established. After PTA, 7.2 mg of native t-PA in 100 mL of isotonic sodium chloride solution was infused for 30 minutes. Neurologic status was evaluated at admission and immediately and 1 month after treatment. In all patients, follow-up CT was performed within 24 hours and 3-7 days after onset, and follow-up MR imaging, 1 month after onset. RESULTS: Direct PTA failed to crush the embolus in three of 15 patients; these three had no clinical improvement. In 11 of 12 patients, combined therapy was successful, with no technical complication. Although no symptomatic intracerebral hemorrhage occurred, one patient had a small hematoma. All patients with successful recanalization had marked clinical improvement. Although angiograms showed distal embolizations in 10, cortical infarctions were confirmed in only three at follow-up. CONCLUSION: Combined direct PTA and IV low-dose native t-PA therapy may be a safe alternative to thrombolytic therapy in some patients with embolic MCA trunk occlusion.

[Strategy for vascular reconstruction for failed indirect anastomosis in adult Moyamoya disease--a case report].

There exist moyamoya disease patients who require vascular reconstruction for failed indirect anastomosis. In the present study, a 36-year-old female required ipsilateral direct anastomosis for failed right fronto-temporo-parietal combined indirect bypass procedure. One of the frontal branches of the right superficial temporal artery (STA) was left intact between the other frontal branch and a parietal branch of the right STA, both of which had been used in the indirect anastomosis. The intact STA was used for direct anastomosis, and craniotomy was performed between the two craniotomy sites of the first operation. Methods of the direct anastomosis for the failed indirect anastomosis should be discussed in each patient who requires vascular reconstruction for failed indirect anastomosis.

[Nutritional assessment in the surgical treatment of childhood moyamoya disease].

Pre- and postoperative values of total protein (TP), total cholesterol (TCH), hemoglobin (HGB), red blood cell (RBC) and hematocrit (HCT) were measured in the surgical treatment of seventeen patients with childhood moyamoya disease. Six out of the 17 patients had bypass surgery twice, so twenty-three cases in total were included in the present study. The postoperative parameters were measured 7 days after each operation. The average of intraoperative blood loss was 103 ml. Decreases in TP, TCH, HGB, RBC, and HCT were 19.7%, 21.3%, 19.8%, 20.8%, and 20.2%, respectively (paired t-test, P < 0.000001). Age had a significantly negative correlation with blood loss rate (blood loss/total blood volume), decrease in HGB, decrease in RBC, and decrease in HCT, respectively. Body weight also had a significantly negative correlation with these values, respectively. In summary, the nutritional state in the postoperative periods of childhood moyamoya disease had not improved even seven days after operation, so special attention to the amount of intraoperative blood loss was needed in low age and low body weight-children with moyamoya disease.

Runx3 is essential for the target-specific axon pathfinding of trkc-expressing dorsal root ganglion neurons.

Dorsal root ganglion (DRG) neurons project their axons to specific target layers in the gray matter of the spinal cord, according to their sensory modality (Neuron 30 (2001), 707; Cell 101 (2000), 485; Neuron 31 (2001), 59; J. Comp. Neurol. 380 (1997), 215; Sensory Neurons, Oxford Univ. Press, New York, 1992, p. 131). Expression of runt-related Runx/AML genes (Mech. Dev. 109 (2001), 413) on subtypes of DRG neurons suggests their involvement in lamina-specific afferent differentiation and maturation. Here we show that Runx3-/- mice display severe limb ataxia and abnormal posture and that most of them die shortly after birth. They show that proprioceptive afferent axons fail to reach the ventral horn and have a smaller dorsal funiculus in their spinal cords. Despite the strong resemblance of this phenotype to that of knockout mice deficient in neurotrophin-3 (NT-3) (Cell 77 (1994), 503; Nature 369 (1994), 658) and its receptor, trkC, (Nature 368 (1994), 249), which show proprioceptive afferent loss through selective neuronal cell death, Runx3-/- mice maintain normal number of TrkC/trkC positive DRG neurons throughout development. Our results suggest that Runx3 controls the target-specific axon pathfinding of trkC-expressing DRG neurons in the spinal cord.