Pharmacokinetics of controlled-release polymers in the subarachnoid space after subarachnoid hemorrhage in rabbits

2004 ◽  
Vol 101 (1) ◽  
pp. 99-103 ◽  
Author(s):  
Gustavo Pradilla ◽  
Paul P. Wang ◽  
Federico G. Legnani ◽  
James L. Frazier ◽  
Rafael J. Tamargo
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Controlled Release ◽  
Evans Blue ◽  
Subarachnoid Space ◽  
Blue Dye ◽  
Content Type ◽  
Cisterna Magna ◽  
Pharmacokinetic Properties ◽  
Fine Print

Object. Implantation of controlled-release polymers into the subarachnoid space to deliver drugs for treatment of vasospasm after subarachnoid hemorrhage (SAH) is currently of interest. Among the issues regarding local delivery of drugs in the subarachnoid space, however, are the extent of diffusion and the rate of release of the loaded agents. In this study Evans blue dye (EBD) was loaded into controlled-release polymers and its pharmacokinetic properties were determined in vitro and in vivo by using a rabbit model of SAH. Methods. Ethylene—vinyl acetate copolymer (EVAc) was loaded 40% (w:w) with EBD and its pharmacokinetics were spectrophotometrically determined in vitro by examining three EBD—EVAc polymers. Additional polymers were implanted either into the frontal lobe or into the cisterna magna of 16 New Zealand White rabbits. Subarachnoid hemorrhage was induced in eight of the animals by an injection of 1.5 ml of arterial blood into the cisterna magna. The animals were killed 3 or 14 days postoperatively, their brains and spinal cords were harvested, and samples of each were placed in formamide for dye extraction and quantification. Specimens were examined macroscopically and the concentrations of EBD were determined with the aid of a spectrophotometer. The EBD—EVAc polymers continuously released EBD over a 133-day period. The controlled release of the dye into the subarachnoid space in either location resulted in staining of the entire central nervous system (CNS) in rabbits when the polymers were placed either on the frontal lobe or in the cisterna magna. The EBD diffusion covered a distance of at least 40 cm. The presence of blood in the subarachnoid space did not interfere with the diffusion. Conclusions. In this study the authors define the rate and extent of diffusion of EBD from controlled-release polymers placed in the subarachnoid space under conditions of SAH. Evans blue dye diffused through the entire rabbit CNS, covering a distance greater than that of the longest dimension of the hemicircumference of the subarachnoid space around the human brain. The pharmacokinetic properties of EBD—EVAc polymers are comparable to those of antivasospasm agents that are successfully used in animal models of SAH.

Time course of vasospasm in man

1978 ◽  
Vol 48 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Bryce Weir ◽  
Michael Grace ◽  
John Hansen ◽  
Charles Rothberg
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Subarachnoid Space ◽  
Time Course ◽  
Content Type ◽  
Base Of Skull ◽  
Fine Print

✓ Measurements were made at eight predetermined positions on 627 sets of angiograms from 293 patients with aneurysms. A ratio between the sum of the vessel diameters in the subarachnoid space to the sum in the base of skull and neck was calculated and plotted against time. Vasospasm has its onset in man about Day 3 after subarachnoid hemorrhage, is maximal at Days 6 to 8, and is gone by Day 12. There is a tendency for patients in poor clinical grades to have more vasospasm. The patients with most vasospasm have a significantly higher mortality than those with the least.

Interstitial delivery of dexamethasone in the brain for the reduction of peritumoral edema

1991 ◽  
Vol 74 (6) ◽  
pp. 956-961 ◽  
Author(s):  
Rafael J. Tamargo ◽  
Allen K. Sills ◽  
Carla S. Reinhard ◽  
Michael L. Pinn ◽  
Donlin M. Long ◽  
...  
Keyword(s):  
Controlled Release ◽  
Plasma Concentrations ◽  
Ethylene Vinyl Acetate ◽  
Peritumoral Edema ◽  
Content Type ◽  
9L Gliosarcoma ◽  
Dexamethasone Group ◽  
The Brain ◽  
Fine Print

✓ Controlled-release polymers have facilitated the interstitial delivery of drugs within the central nervous system. In the present study, dexamethasone was incorporated into ethylene-vinyl acetate polymers, which were then implanted adjacent to a 9L gliosarcoma in the brain of Fischer 344 rats. The effect of interstitial delivery of dexamethasone on peritumoral edema was assessed and compared to the effect of dexamethasone delivered systemically. Eighty-five rats underwent intracranial implantation of the 9L gliosarcoma. Five days later, the animals were randomly assigned to one of four treatment groups: Group 1 received intracranial implantation of controlled-release polymers containing dexamethasone; Group 2 received intraperitoneal implantation of controlled-release polymers containing dexamethasone; Group 3 received serial intraperitoneal injections of dexamethasone; and Group 4 received sham treatment. The animals were sacrificed 3 days after initiation of therapy and their brains were removed for measurement of the water content (edema) in the tumor-bearing and contralateral hemispheres. Brain and plasma samples were analyzed by reverse-phase high-performance liquid chromatography to determine the tissue and plasma concentrations of dexamethasone. Measurement of the release kinetics of dexamethasone from the ethylene-vinyl acetate polymers in an in vitro system showed that the drug was released in a controlled, tapering fashion. During the first 3 days of controlled release in vitro, 330 µg of a total content of 7.5 mg of dexamethasone was released into the medium. Analysis of tissue for drug levels demonstrated, however, that the interstitial delivery of this fractional amount of dexamethasone within the brain resulted in levels 19 times higher than those achieved by administering the full dose of 7.5 mg systemically over a 3-day period. Conversely, the systemic administration of dexamethasone resulted in plasma levels 16 times higher than those measured in the interstitial delivery of dexamethasone in the brain. Brain-water content determinations showed that the interstitial controlled release of the fractional amount of dexamethasone within the brain was as effective in controlling peritumoral edema as systemic administration of the full dose by serial intraperitoneal injections. The study demonstrates the following: 1) controlled-release polymeric carriers deliver biologically active dexamethasone in a sustained fashion; 2) very high concentrations of dexamethasone in brain tissue can be achieved using interstitial polymer-mediated drug delivery while minimizing plasma concentrations of this drug which are sometimes associated with serious systemic side effects; and 3) peritumoral brain edema can be effectively treated by the interstitial delivery of dexamethasone directly within the tumor bed.

Focal brain edema associated with acute arterial hypertension

1986 ◽  
Vol 64 (4) ◽  
pp. 643-649 ◽  
Author(s):  
Shizuo Hatashita ◽  
Julian T. Hoff ◽  
Shozo Ishii
Keyword(s):  
Blood Pressure ◽  
Arterial Hypertension ◽  
Water Content ◽  
Brain Edema ◽  
Evans Blue ◽  
Blue Dye ◽  
Boundary Zone ◽  
Tissue Pressure ◽  
Content Type ◽  
Fine Print

✓ Acute arterial hypertension was studied in normal cats to determine its role in the formation of brain edema. Arterial hypertension was induced for 30 minutes by inflation of a balloon catheter situated in the descending aorta. Cerebral edema was evaluated by gross and microscopic observations, tissue water content by wet/dry weights, and blood-brain barrier (BBB) permeability by extravasation of horseradish peroxidase (HRP) and Evans blue dye. For 1 hour after the hypertensive insult, tissue pressure and regional cerebral blood flow (rCBF) were measured from the arterial boundary zone and from a non-boundary region, and intracranial pressure was recorded from the lateral ventricle as ventricular fluid pressure. Focal lesions with increased BBB permeability to Evans blue dye or HRP were usually located symmetrically in the cortex, corresponding to the occipitoparietal parts of the arterial boundary zones. The increase in water content was found only in areas of increased permeability. Tissue pressure increased simultaneously with the abrupt rise in blood pressure, and an increase in rCBF paralleled the elevation of blood pressure. Tissue pressure and rCBF returned to a steady state when blood pressure returned to normal. There were no differences in tissue pressure or rCBF between the arterial boundary zone and the non-boundary zone, even during arterial hypertension. In cerebral hemispheres examined 48 hours after the hypertensive challenge, brain edema had not continued to develop. The data indicate that acute arterial hypertension may produce focal brain edema with increased permeability of the BBB in the cortex of normal brain, particularly in the arterial boundary zones. The authors postulate that increased cerebral blood volume, high intraluminal pressure, and breakthrough of autoregulation play an important role in the formation of hypertensive brain edema.

Chromoblastomycosis in the cisterna magna and the spinal subarachnoid space

1973 ◽  
Vol 38 (4) ◽  
pp. 506-509 ◽  
Author(s):  
Hiroshi Takahashi ◽  
Akira Sasaki ◽  
Toshimoto Arai ◽  
Yasushi Tsukamoto ◽  
Osamu Sato ◽  
...  
Keyword(s):  
Subarachnoid Space ◽  
Content Type ◽  
Cisterna Magna ◽  
Suboccipital Craniectomy ◽  
First Case ◽  
Spinal Subarachnoid Space ◽  
Fine Print

✓ This paper reports the first case of chromoblastomycosis affecting the cisterna magna and the spinal subarachnoid space. Suboccipital craniectomy and laminectomy of T-8, 9, and 10 revealed arachnoiditis and multiple granulomas caused by Hormodendrum pedrosi.

Prevention of cerebral vasospasm by a humanized anti-CD11/CD18 monoclonal antibody administered after experimental subarachnoid hemorrhage in nonhuman primates

2003 ◽  
Vol 99 (2) ◽  
pp. 376-382 ◽  
Author(s):  
Richard E. Clatterbuck ◽  
Philippe Gailloud ◽  
Lynn Ogata ◽  
Abeyu Gebremariam ◽  
Gregory N. Dietsch ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Subarachnoid Hemorrhage ◽  
Cerebral Vasospasm ◽  
Subarachnoid Space ◽  
Nonhuman Primates ◽  
Leukocyte Migration ◽  
Content Type ◽  
Areal Fraction ◽  
Chronic Vasospasm ◽  
Fine Print

Object. Leukocyte—endothelial cell interactions occurring in the first hours after subarachnoid hemorrhage (SAH) initiate changes in the endothelium and vessel wall that lead to an influx of leukocytes and the development of chronic vasospasm days later. Upregulation of intercellular adhesion molecule—1 (ICAM-1), also called CD54, appears to be a crucial step in this process. There is increasing experimental evidence that blocking the interaction between ICAM-1, which is expressed on endothelium, and integrins such as lymphocyte function—associated antigen—1 (CD11a/CD18) and macrophage antigen—1 (complement receptor 3, CD11b/CD18), which are expressed on the surface of leukocytes, prevents not only inflammation of vessel walls but also chronic vasospasm. The authors extend their previous work with monoclonal antibody (mAb) blockade of leukocyte migration to a nonhuman primate model of chronic, posthemorrhagic cerebral vasospasm. Methods. Before surgery was performed, six young adult male cynomolgus monkeys underwent baseline selective biplane common carotid and vertebrobasilar artery cerebral angiography via a transfemoral route. On Day 0, a right frontosphenotemporal craniectomy was performed with arachnoid microdissection and placement of 2 to 3 ml of clotted autologous blood in the ipsilateral basal cisterns. The animals were given daily intravenous infusions of 2 mg/kg of either a humanized anti-CD11/CD18 or a placebo mAb beginning 30 to 60 minutes postoperatively. The monkeys were killed on Day 7 after a repeated selective cerebral angiogram was obtained. The area of contrast-containing vessels observed in each hemisphere on anteroposterior angiographic views was calculated for the angiograms obtained on Day 7 and expressed as a percentage of the area on baseline angiograms (percent control areal fraction). Review of flow cytometry and enzyme immunoassay data confirmed the presence of the anti-CD11/CD18 antibody in the serum and bound to leukocytes in the peripheral blood of treated animals. Comparisons of the groups revealed 53 ± 4.8% control vascular areal fraction in the placebo group (two animals) and 95.8 ± 9.4% in the anti-CD11/CD18—treated group (three animals), a statistically significant difference (p = 0.043, t-test). Conclusions. These results show that blockade of leukocyte migration into the subarachnoid space by an anti-CD11/CD18 mAb is effective in preventing experimental cerebral vasospasm in nonhuman primates, despite the unaltered presence of hemoglobin in the subarachnoid space. These experimental data support the hypothesis that inflammation plays a role in cerebral vasospasm after SAH.

CSF leukotriene C4 following subarachnoid hemorrhage

1988 ◽  
Vol 69 (4) ◽  
pp. 488-493 ◽  
Author(s):  
Pietro Paoletti ◽  
Paolo Gaetani ◽  
Guido Grignani ◽  
Lucia Pacchiarini ◽  
Vittorio Silvani ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Subarachnoid Hemorrhage ◽  
Arterial Spasm ◽  
Lipoxygenase Pathway ◽  
Content Type ◽  
Symptomatic Vasospasm ◽  
Csf Levels ◽  
Fine Print

✓ Leukotrienes derive from arachidonic acid metabolism via the lipoxygenase pathway and modulate several cellular events. In the central nervous system, leukotrienes are mainly synthesized in the gray matter and in vascular tissues. Their production is enhanced in ischemic conditions and in experimental subarachnoid hemorrhage (SAH). Previous studies have indicated the ability of the leukotrienes C4 and D4 to constrict arterial vessels in vivo and in vitro and have suggested their involvement in the pathogenesis of cerebral arterial spasm. In the present study, the authors measured lumbar and cisternal cerebrospinal fluid (CSF) levels of leukotriene C4 in 48 patients who had suffered aneurysmal SAH. In 12 of the cases, symptomatic and radiological spasm was evident. The mean lumbar CSF level of immunoreactive-like activity of leukotriene C4 (i-LTC4) was significantly higher (p < 0.005) than in control cases, while the cisternal CSF level was higher than the lumbar mean concentration (p < 0.005). Patients presenting with vasospasm had significantly higher levels of i-LTC4 compared to patients without symptomatic vasospasm. This is the first report concerning monitoring of i-LTC4 levels in the CSF after SAH. The results of this study suggest that: 1) metabolism of arachidonic acid via the lipoxygenase pathway is enhanced after SAH; 2) the higher cisternal CSF levels of i-LTC4 may be part of the biological response in the perianeurysmal subarachnoid cisterns after the hemorrhage; and 3) the higher CSF levels of i-LTC4 in patients presenting with vasospasm suggest that a relationship exists between this compound and arterial spasm and/or reflect the development of cerebral ischemic damage.

An in vitro comparative study of conducting vessels and penetrating arterioles after experimental subarachnoid hemorrhage in the rabbit

1992 ◽  
Vol 77 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Dennis G. Vollmer ◽  
Masakazu Takayasu ◽  
Ralph G. Dacey
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Basilar Artery ◽  
Isometric Tension ◽  
Channel Blockers ◽  
Cerebral Microvessels ◽  
Content Type ◽  
Large Arteries ◽  
Experimental Subarachnoid Hemorrhage ◽  
Fine Print

✓ The reactivity of rabbit basilar artery and penetrating arteriolar microvessels was studied in vitro using an isometric-tension measurement technique and an isolated perfused arteriole preparation, respectively. Comparisons were made between reactivities of normal vessels and those obtained from animals subjected to experimental subarachnoid hemorrhage (SAH) 3 days prior to examination. Subarachnoid hemorrhage produced significant increases in basilar artery contraction in response to increasing concentrations of serotonin (5-hydroxytryptamine) (10−9 to 10−5 M) and prostaglandin F2α (10−9 to 10−5 M) when compared to normal arteries. In addition, SAH attenuated the relaxing effect of acetylcholine following serotonin-induced contraction and of adenosine triphosphate after KCl-induced basilar artery contractions. In contrast to the changes observed in large arteries, cerebral microvessels did not demonstrate significant differences in spontaneous tone or in reactivity to a number of vasoactive stimuli including application of calcium, serotonin, and acetylcholine. On the other hand, small but significant changes in arteriolar responsiveness to changes in extraluminal pH and to application of KCl were noted. Findings from this study suggest that intracerebral resistance vessels of the cerebral microcirculation are not greatly affected by the presence of subarachnoid clot, in contrast to the large arteries in the basal subarachnoid space. The small changes that do occur are qualitatively different from those observed for large arteries. These findings are consistent with the observation of significant therapeutic benefit with the use of calcium channel blockers without changes in angiographically visible vasospasm in large vessels. It is likely, therefore, that calcium antagonists may act to decrease total cerebrovascular resistance at the level of the relatively unaffected microcirculation after SAH without changing large vessel diameter.

The subarachnoid space in congenital obstructive hydrocephalus

1971 ◽  
Vol 35 (1) ◽  
pp. 7-15 ◽  
Author(s):  
Thomas H. Milhorat ◽  
Mary K. Hammock ◽  
Roma S. Chandra
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Surgical Management ◽  
Subarachnoid Space ◽  
Obstructive Hydrocephalus ◽  
Pathological Findings ◽  
Past Infection ◽  
Content Type ◽  
Fine Print

✓ The leptomeninges of 52 patients who died with a diagnosis of congenital or early acquired obstructive hydrocephalus were examined microscopically. In each case a well-developed subarachnoid space was present and in no cases were the leptomeninges congenitally absent. Thus, the commonly held belief that the subarachnoid space may fail to develop in congenital obstructive hydrocephalus was not supported by this study. Pathological findings in the leptomeninges were common, however, and were generally related to the following factors: the severity of the hydrocephalus, the duration of the hydrocephalus, the success or failure of surgical management, past infection (both intrauterine and postnatal), and subarachnoid hemorrhage. The type of ventricular obstruction did not seem to be a significant factor. Certain embryological considerations raised by the current findings are discussed.

Subarachnoid hemorrhage inhibition of endothelium-derived relaxing factor in rabbit basilar artery

1988 ◽  
Vol 69 (2) ◽  
pp. 247-253 ◽  
Author(s):  
Kazuhiro Hongo ◽  
Neal F. Kassell ◽  
Tadayoshi Nakagomi ◽  
Tomio Sasaki ◽  
Tetsuya Tsukahara ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Basilar Artery ◽  
Selective Inhibitor ◽  
Isometric Tension ◽  
The Other ◽  
Content Type ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor ◽  
Fine Print

✓ Vascular contractions in response to KCl and serotonin (5-hydroxytryptamine, 5-HT) in rabbit basilar artery were studied in vitro using an isometric tension-measurement technique. Hemoglobin ( 10−5 M) markedly augmented contractions induced by 5-HT (10−9 to 10−6 M) and slightly augmented those induced by KCl (20 to 80 mM) in arteries with intact endothelium. On the other hand, the augmentation induced by hemoglobin was almost abolished in arteries that were chemically denuded of endothelial cells by pretreatment with saponin. Since hemoglobin is known to be a selective inhibitor of endothelium-derived relaxing factor (EDRF), it is possible that the augmentation of contraction by hemoglobin in endothelium-intact arteries was mediated via an inhibition of spontaneously released EDRF. The effect of subarachnoid hemorrhage (SAH) on spontaneously released EDRF was investigated by injecting 5 ml of blood into the cisterna magna and sacrificing the rabbits 2 days later. Arteries after SAH showed a significant reduction in hemoglobin-induced augmentation compared to that seen in control arteries with intact endothelium. This result suggests that spontaneously released EDRF is significantly reduced after SAH. It is concluded that EDRF is released spontaneously in the rabbit basilar artery and that inhibition of its release might be involved in pathogenesis of cerebral vasospasm.

Impaired capillary perfusion and brain edema following experimental subarachnoid hemorrhage: a morphometric study

1990 ◽  
Vol 73 (3) ◽  
pp. 410-417 ◽  
Author(s):  
Hiroo Johshita ◽  
Neal F. Kassell ◽  
Tomio Sasaki ◽  
Hisayuki Ogawa
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Brain Stem ◽  
Brain Edema ◽  
Blood Volume ◽  
Evans Blue ◽  
Piriform Cortex ◽  
Capillary Perfusion ◽  
Content Type ◽  
Intercapillary Distance ◽  
Fine Print

✓ To evaluate microcirculatory disturbance and cerebral edema associated with subarachnoid hemorrhage (SAH), both stereological morphometry on the intraparenchymal capillary network and microgravimetry were performed on a rabbit SAH model. Autologous arterial blood (5 ml) was injected into the cisterna magna, and the animals were sacrificed at intervals of 6 hours, 1 day, 2 days, or 6 days after SAH. Capillaries in the piriform cortex, parasagittal cortex, and ventral brain stem of the midline-hemisectioned brain were injected with Evans blue dye 1 minute before sacrifice, and were planimetrically evaluated under a fluorescence microscope connected to an image analysis system. Stereological and morphological parameters including the volume density, surface density, numerical density, minimum intercapillary distance, and the diameter of Evans blue-perfused capillaries were also computed. In the piriform cortex and ventral brain stem, the volume and surface densities were significantly reduced and the minimum intercapillary distance was significantly increased 1 to 2 days after SAH. In the parasagittal cortex far from the cisternal clot, changes in the parameters were minimal. Cerebral blood volume (CBV) in the normal condition and edema formation associated with SAH were studied by the microgravimetric technique. The mean CBV in the parasagittal cortex, piriform cortex, and brain stem was 6.9%, 6.8%, and 5.6%, respectively. Following SAH, specific gravity in the piriform cortex and the ventral brain stem of the other side of the hemisectioned brain was significantly decreased at 1 to 2 days, showing a change parallel to that of the stereological parameters. The results obtained from the morphometric technique indicated the occurrence of impaired capillary perfusion and reduced capillary blood volume following SAH, while microgravimetry suggested the formation of brain edema during this period. These changes in the intraparenchymal vessels may play an important role in the pathophysiology of SAH.

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