Biomedical subjects

N Hashimoto

Publications and source records attributed to N Hashimoto.

777 records · Page 44Linked to original sources

PubMedDate not supplied

Intraarterial infusion of high-concentration papaverine damages cerebral arteries in rats.

PURPOSE: To determine the appropriate concentration of papaverine for therapeutic intraarterial infusion against cerebral vasospasm. METHODS: We investigated histopathologic changes in cerebral arteries and brain tissue of normal Wistar rats that had received infusions of papaverine via the carotid artery. Rats were infused with 0.20 mL papaverine (concentration, 0.4% to 4.0%) via the internal carotid artery. Injury to the vascular wall was evaluated by transmission electron microscopy; pathologic changes in cerebral tissue were studied by light microscopy. RESULTS: Neither brain necrosis nor brain edema was seen under light microscopy at any concentration. At 4.0% papaverine concentration, degeneration of endothelial cells and medial smooth muscle, including vacuole formation, was observed under electron microscopy. At 1.4% concentration, degeneration of endothelial cells was seen. Extravasation of Evans blue dye was noted when drug concentration exceeded 1.4%. At 0.8% concentration, no histopathologic change was noted. CONCLUSION: On the basis of these results, we recommend a papaverine concentration of 0.8% or less for intraarterial infusion.

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PubMedDate not supplied

Embolization with cellulose porous beads, I: An experimental study.

PURPOSE: To study the possibility of using cellulose porous beads (CPBs) as a solid embolic material for the permanent occlusion of blood vessels. METHODS: Unilateral renal arteries of 12 adult mongrel dogs were embolized with CPBs. Selective renal angiograms were obtained immediately, 1 hour, 4 weeks, and 12 weeks after the embolization. The dogs were killed 1 hour (n = 4), 4 weeks (n = 4), or 12 weeks (n = 4) after the procedure. The kidneys were removed en bloc and examined histologically. RESULTS: The CPBs were easily injected through a microcatheter, were readily controlled with radiodensity, and did not adhere to the catheter. Renal angiograms obtained after embolization disclosed complete occlusion of the renal artery. Microscopically, the CPBs traveled to vessels with approximately the same diameter size. Larger vessels were occluded by aggregations of particles that left no open spaces. We found no disruption of the vessel wall, no evidence of perivascular hemorrhage, and no inflammatory changes of the vessel wall or the surrounding tissues. CONCLUSION: The CPBs were easy to use; they reached distal sites and produced a homogeneous and permanent occlusion without specific inflammatory changes. The good results of this experimental study led to a clinical trial of CPBs.

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PubMedDate not supplied

Embolization with cellulose porous beads, II: Clinical trial.

PURPOSE: To evaluate the clinical applicability of cellulose porous beads (CPBs) as an embolic material for permanent vascular occlusion. METHODS: Embolization with CPBs was performed in 16 patients, six with meningioma of the sphenoid wing, two with meningioma of the falx, three with meningioma of the tentorium, two with dural arteriovenous fistula, one with paraganglioma, and two with spinal arteriovenous malformation. Surgical specimens were examined histologically. RESULTS: No complications were encountered in any of the 16 patients. Angiograms obtained after embolization showed satisfactory vascular stasis in all cases. Histologic examination of surgical specimens disclosed that vessels having approximately the same caliber as the CPB particles were occluded without stretching of the vessel wall. Larger vessels were occluded by aggregates of many particles, which left no open spaces. Although a few inflammatory cells were seen in the thrombosed vessels, inflammation evoked by CPB was mild and did not extend to either the vessel wall or to surrounding tissues. CONCLUSION: CPBs were easy to inject through microcatheters, traveled to distal sites, and produced homogeneous and peripheral embolization without inflammatory changes different from other embolic materials. CPBs are a good embolic material for permanent occlusion in the clinical setting.

Adolescent↗