Biomedical subjects

M Chopp

Publications and source records attributed to M Chopp.

At least 19 recordsLinked to original sources

PubMed1998

Preliminary clinical-radiological assessment of a MR tissue signature model in human stroke.

We evaluated the ability of an MR signature model (SM) of cerebral ischemic injury to stage the evolution of cellular damage in human stroke. In 19 patients with ischemic stroke of presumed embolic or non-embolic cause we carried out diffusion-weighted and T2-weighted MR imaging within 48 h of onset, and obtained apparent diffusion coefficient of water (ADCw), and T2 weighted images. We used the signatures obtained from these ADCw/T2 maps to formulate two patterns of damage signifying accelerated or non-accelerated progression of cellular death after stroke onset. Those patients with the accelerated pattern corresponded to those with the neuroradiological (NRC) and clinical diagnosis (TOAST.1 and TOAST.2) of presumed embolic stroke, with clinical diagnosis performed blinded both to NRC and to SM. Agreement between the SM and NRC was substantial (kappa=0.62), moderate (0.60<kappa<0.40) between the SM or NRC and TOAST.2, and fair (0.40<kappa<0.20) among the SM or NRC and TOAST.1. We believe these results constitute a preliminary validation of the MR tissue signature modeling in clinical stroke assessment.

Adult↗

PubMed1998

Intact, injured, necrotic and apoptotic cells after focal cerebral ischemia in the rat.

Middle cerebral artery occlusion (MCAo) leads to brain cell death. However, quantitation of injured brain cells and inflammatory cells after MCAo has not been determined in the rat. Transient (2 h) MCAo was therefore induced in male Wistar rats by means of an intraluminal monofilament. Immunohistochemical and histochemical procedures performed at 46 h after MCAo were used to identify specific cellular populations in ischemic and control rats (n = 11). In the ischemic core of the lesion, approximately 24.7% of cells disappeared. Forty-four point eight percent of parenchymal cells consisted of intact (13.0%) or reversibly injured swollen (7.6%) and scalloped/shrunken dark (24.2%) cells. The percentage of irreversibly damaged cells was 55.2%, and included 49.9% necrotic cells (10.5% red and 39.4% ghost) and 5.4% apoptotic cells. In the inner boundary zone of the lesion, 15.9% of cells disappeared. Viable cells constituted 62.0% of all remaining cells. Neutrophils and macrophages were localized to this area. In the outer boundary zone of the lesion, 9.0% of cells disappeared. Viable cells constituted 91.6% of all remaining cells. The ratio of apoptotic to necrotic cells was 1:9, 1:6, 1:13 in the ischemic core, inner and outer boundary zones, respectively. Our data suggest the presence of three zones within the ischemic lesion: the core, and inner and outer boundaries. At 46 h after 2 h of MCAo the ischemic lesion is highly heterogeneous containing relatively large percentages of morphologically intact cells, suggesting the possibility of an extended window of therapeutic opportunity.

Animals↗

PubMed1998

Neutrophil inhibitory factor treatment of focal cerebral ischemia in the rat.

The present study was designed to determine whether a hookworm-derived recombinant neutrophil inhibitory factor (rNIF) is neuroprotective when administered after initiation of focal cerebral ischemia in the rat. We measured the rNIF dose-response on cerebral infarct volume, the therapeutic time window, the therapeutic response to permanent ischemia, and whether rNIF treatment delays the maturation of the ischemic lesion (2 days), or reduces cerebral infarct volume at 7 days after middle cerebral artery occlusion (MCAO). MCAO was induced by an insertion of intraluminal 4-0 monofilament nylon suture into internal carotid artery (n=195). We demonstrate a significant neuroprotective effect of rNIF administration 48 h after MCAO in a dose-dependent fashion when treatment was initiated upon reperfusion after 2 h MCAO and maintained until 48 h after MCAO. The beneficial effect was lost under conditions of permanent MCAO. The therapeutic time window is 4 h after MCAO. Brief treatment (6 h) is not sufficient to provide protection for the final ischemic damage. Continuous treatment with a high dose of rNIF for a long duration (7 days) is necessary to achieve maximum neuroprotection.

Animals↗

PubMed1998

Diffusion, perfusion, and T2 magnetic resonance imaging of anti-intercellular adhesion molecule 1 antibody treatment of transient middle cerebral artery occlusion in rat.

The effect of anti-intercellular adhesion molecule-1 (anti-ICAM-1) antibody treatment of transient (2 h) middle cerebral artery (MCA) occlusion in the rat was measured using diffusion (DWI)-, T2 (T2I)- and perfusion (PWI)-weighted magnetic resonance imaging. Rats were treated upon reperfusion with an anti-ICAM-1 monoclonal antibody (n=11) or a control antibody (n=7). DWI, T2I and PWI were performed before, during, and after induction of focal cerebral ischemia from 1 h to 7 days. In both groups, the apparent diffusion coefficient of water (ADCw) and cerebral blood flow (CBF) values in the ischemic region significantly declined from the preischemic ADCw values (p<0. 05). The post ischemic increase in T2 of the control group was significantly higher at 48 h than in the anti-ICAM-1 treated group (p<0.05). CBF was not significantly different between the two groups. The temporal profiles of MRI cluster analysis, which combines ADCw and T2 maps into a single image, was significantly different between groups. These data suggest that the neuroprotective effect of anti-ICAM-1 antibody treatment is reflected in reductions of T2 and lesion growth during reperfusion and may not be associated with increased cerebral perfusion.

Animals↗

PubMed1998

The expression of P- and E-selectins in three models of middle cerebral artery occlusion.

The expression and localization of P- and E-selectins in rat brain (n=126) were examined using immunohistochemical techniques at various time points after induction of middle cerebral artery (MCA) occlusion in the suture, thrombotic and embolic models of stroke. Expression of P- or E-selectin was not observed in brain tissue of sham operated control rats (n=9). P-selectin immunoreactivity was detected as early as 15 min and decreased to control level at 1 h after the onset of the MCA occlusion in all three models. P-selectin then slightly increased at 2 h and peaked at 6 h after MCA occlusion. E-selectin immunoreactivity was first observed at 2 h and peaked at 6 h and 12 h of after MCA occlusion in all three models. P- and E-selectin immunoreactivity was colocalized with von Willebrand factor immunoreactive microvessels. 90.4+/-2.0% of all vessels expressing P-selectin immunoreactivity were 7.5 to 30.0 micron in diameter; 3.6+/-1.4% were contained in vessels smaller than 7.5 micron, and 6.0+/-1.8% were localized in vessels greater than 30.0 micron in diameter. The percent distribution of E-selectin immunoreactive vessels were 75.9+/-2.1% in vessels 7.5 to 30.0 micron in diameter; 23.6+/-2.2% were in vessels smaller than 7.5 micron, and 0.6+/-0.4% were localized in vessels greater than 30.0 micron in diameter. These findings indicate that the temporal profiles of P- and E-selectin expression are independent of these models of MCA occlusion and are consistent with the time course of selectin mediated leukocyte infiltration after focal cerebral ischemia in the rat.

Analysis of Variance↗

PubMed1998

Cerebral vessels express interleukin 1beta after focal cerebral ischemia.

Rapid and marked increased levels of expression of interleukin 1beta (IL-1beta) mRNA have been detected in animal models of cerebral ischemia. However, the protein production of IL-1beta and the cellular sources of IL-1beta are largely undefined after cerebral ischemia. In the present study, we have measured the cellular localization of IL-1beta protein in brain tissue from non-ischemic and ischemic mice using immunohistochemistry. Male C57B/6J (n=45) mice were subjected to middle cerebral artery (MCA) occlusion by a clot or a suture. The mice were sacrificed at time points spanning the period from 15 min to 24 h after onset of the MCA occlusion. Non-operated and sham-operated mice were used as control groups. A monoclonal anti-IL-1beta antibody was used to detect IL-1beta. In the non-operated and sham-operated mice, a few IL-1beta immunoreactive cells were detected scattered throughout both hemispheres. IL-1beta immunoreactive cells increased in the ischemic lesion as early as 15 min and peaked at 1 h to 2 h after MCA occlusion. IL-1beta immunoreactivity was detected in the cortex of the contralateral hemisphere 1 h after ischemia. By 24 h after onset of ischemia, IL-1beta immunoreactivity was mainly present adjacent to the ischemic lesion and in the non-ischemic cortex. IL-1beta immunoreactivity was found on endothelial cells and microglia. This study demonstrates an early bilateral expression of IL-1beta on endothelium after MCA occlusion in mice.

Animals↗

PubMed1998

Photodynamic therapy of U87 human glioma in nude rat using liposome-delivered photofrin.

BACKGROUND AND OBJECTIVE: Liposomes as photosensitizer carriers may enhance the photodynamic effect on tumors. STUDY DESIGN/MATERIALS AND METHODS: To test this hypothesis, we treated U87 human glioma in rat brain with photodynamic therapy (PDT) using Photofrin encapsulated in a liposome carrier or Photofrin in dextrose. Nontumored brain was also treated and Photofrin content ratios were measured in tumor and nontumored brain. RESULTS: PDT using the liposome encapsulated photosensitizer significantly increased tumor destruction compared to PDT with Photofrin in dextrose (P = 0.007), whereas no difference in tissue damage was detected in nontumored brain with or without liposome carrier. Photofrin uptake was also significantly elevated in the liposome vehicle group compared to the dextrose (P < 0.05) group. CONCLUSIONS: Our data suggest that Photofrin encapsulated in a liposome may enhance the PDT treatment of human brain tumors.

Animals↗

PubMed1997

Granule cell apoptosis and protein expression in hippocampal dentate gyrus after forebrain ischemia in the rat.

We investigated the relationship between apoptosis and selective protein expression in brain from rats subjected to 8 (n=10) or 12 min (n=10) of forebrain ischemia and 48 h of reperfusion, and control sham operated (n=2) and normal (n=2). Coronal sections were processed for double staining with DNA fragmentation detection and immunohistochemical staining. In five of ten 8-min ischemic and three of ten 12-min ischemic animals, nearly all dead granule cells within the dentate gyrus exhibited apoptotic morphology. In the remaining animals, no granule cell death was evident. In the pyramidal regions (CA1/2), nearly all dead cells were necrotic with only scattered apoptotic cells present. The immunoreactive expression of wt-p53, p53-response proteins (WAF1, Bax and Gadd45), and a cell cycle protein (cyclin D) were detected and preferentially localized to nuclei of apoptotic granule cells, and were weakly expressed in nuclei of necrotic pyramidal CA1/2 cells. Thus, 48 h after 8 or 12 min of forebrain ischemia in the rat, most pyramidal cells and dentate granule cells undergo distinct cell death pathways of necrosis or apoptosis, respectively. In addition, the selective expression of proteins associated with DNA damage and cell cycle in apoptotic dentate granule cells suggests a role for these proteins in the induction of apoptosis.

Animals↗

PubMed1997

A rat model of focal embolic cerebral ischemia.

We developed a new model of embolic cerebral ischemia in the rat which provides a reproducible and predictable infarct volume within the territory supplied by the middle cerebral artery (MCA). The MCA was occluded by an embolus in Wistar rats (n = 71). An additional three non-embolized rats were used as a control. Cerebral blood flow (CBF) was measured by means of laser Doppler flowmetry (LDF) and perfusion weighted imaging (PWI) before and after embolization. The evolution of the lesion was monitored by diffusion weighted imaging (DWI). Cerebral vascular perfusion patterns were examined using laser scanning confocal microscopy. Infarct volumes were measured on hematoxylin and eosin (H&E) stained coronal sections. The lodgment of the clot at the origin of the MCA and the ischemic cell damage were examined using light microscopy. Regional CBF in the ipsilateral parietal cortex decreased to 43 +/- 4.1% (P < 0.05) of preischemic levels (n = 10). Confocal microscopic examination revealed a reduction of cerebral plasma perfusion in the ipsilateral MCA territory (n = 6). MRI measurements showed a reduction in CBF and a hyperintensity DWI encompassing the territory supplied by the MCA (n = 4). An embolus was found in all rats at 24 h after embolization. The infarct volume as a percentage of the contralateral hemisphere was 32.5 +/- 3.31% at 24 h (n = 20), 33.0 +/- 3.6% at 48 h (n = 13), and 34.5 +/- 4.74% at 168 h (n = 12) after embolization. This model of embolic focal cerebral ischemia results in ischemic cell damage and provides a reproducible and predictable infarct volume. This model is relevant to thromboembolic stroke in humans and may be useful in documenting the safety and efficacy of fibrinolytic intervention and in investigating therapies complementary to antithrombotic therapy.

Animals↗

PubMed1997

Apoptosis and protein expression after focal cerebral ischemia in rat.

We used double staining histochemistry to investigate the relationship between apoptotic cell death and selective protein expression associated with DNA damage (p53, Bax, MDM2, Gadd45), DNA repair (PCNA) and cell cycle proteins (cyclin A, cyclin D, cdk2, cdk4) in rats (n = 6; control rats, n = 5) subjected to transient (2 h) middle cerebral artery occlusion (MCAo) and 46 h of reperfusion. Few apoptotic cells were detected in the non-ischemic hemisphere of control rats. In ischemic animals, scattered apoptotic cells were present in the ischemic core and clustered apoptotic cells were present and localized to the inner boundary zone of the ischemic core. Proteins were preferentially localized to the cellular cytoplasm of control rats and in the non-ischemic hemisphere of rats subjected to MCAo. However, after MCAo these proteins were expressed and were preferentially localized to nuclei within the ischemic lesion. DNA damage induced proteins (wt-p53 and p53-response proteins) were preferentially expressed within apoptotic cells after ischemia. DNA repair proteins and cell cycle proteins were preferentially expressed within morphologically intact cells and in reversibly damaged cells in the ischemic areas. The selective expression of proteins associated with DNA damage, DNA repair and cell cycle observed in morphologically intact cells, ischemic injured cells and apoptotic cells suggests a differential role for these proteins in cell survival and apoptosis after stroke.

Animals↗

PubMed1997

Adenosine kinase inhibition protects brain against transient focal ischemia in rats.

Endogenous adenosine released locally during cerebral ischemia is neuroprotective, and agents which decrease adenosine inactivation may potentiate its protective effects. The effects of 5'-deoxy-5-iodotubercidin (5'd-5IT), an inhibitor of the adenosine-catabolizing enzyme, adenosine kinase, were studied in male Wistar rats subjected to 2 h of transient middle cerebral artery occlusion. 5'd-5IT or the vehicle (10% DMSO in saline) was administered i.p. 30 min before, and 2 h and 6 h after the induction of middle cerebral artery occlusion. The infarct volume was determine using 2,3,5-triphenyltetrazolium chloride staining 48 h after middle cerebral artery occlusion. The infarct volume was significantly reduced in rats treated with 1.85 mg/kg x 3 (57% reduction, P < 0.001) or 1.0 mg/kg x 3 (34% reduction, P < 0.05), but not 0.3 mg/kg x 3 5'd-5IT compared to vehicle-treated rats. The reduction of infarct volume was accompanied by a significant improvement in behavioral measures of neurological deficit. These data further support a role of adenosine in neuroprotection and suggest that adenosine kinase inhibition may be a useful approach to the treatment of focal cerebral ischemia.

Adenosine Kinase↗

PubMed1997

Temporal profile of microglial response following transient (2 h) middle cerebral artery occlusion.

We measured the time-dependent morphological changes of microglial cells reacting to ischemic cell damage after transient (2 h) middle cerebral artery occlusion in the rat by means of lectin histochemistry with the B4-isolectin from Griffonia simplicifolia as well as immunohistochemistry with monoclonal antibodies directed against monocyte/microphage (ED1) and major histocompatibility complex (MHC) class II (OX-6) antigens. As early as 1 h after onset of reperfusion, microglia were absent in the severely neuronal damaged preoptic area. However, ameboid-like microglia were evident in an adjacent area containing scattered shrunken neurons. Rod, round and ameboid-like microglia were present in the ischemic lesion between 2 to 10 h of reperfusion. Round and ameboid cells became predominant in the ischemic core lesion and were mingled with highly ramified microglia to the boundary at 22 h of reperfusion. Highly ramified microglia were found in an adjacent area containing morphologically intact neurons. Round and ameboid cells were localized to the inner boundary of the ischemic lesion surrounding the infarct zone at 46 of reperfusion. Round and ameboid cells were present throughout the entire ischemic lesion in the infarct zone from 70-166 h of reperfusion. A marked increase in number and in intensity of highly ramified microglial cells were present in the outer boundary of the lesion during this period. In addition, a significant increase in both ED1- and OX-6-immunoreactive cells in the ischemic region was detected after 10 h of reperfusion and persisted up to 166 h of reperfusion. These data demonstrate that microglia exhibit a time dependent change in morphology after reperfusion and that the severity of injury may be reflected in the state of microglial activation.

Animals↗

PubMed1997

The temporal evolution of MRI tissue signatures after transient middle cerebral artery occlusion in rat.

We have developed a multiparameter magnetic resonance imaging (MRI) cluster analysis model of acute ischemic stroke using T2 relaxation times and the diffusion coefficient of water (ADCw). To test the ability of this model to predict cerebral infarction, male Wistar rats (n = 7) were subjected to 2 h of transient middle cerebral artery (MCA) occlusion, and diffusion and T2 weighted MRI were performed on these rats before, during and up to 7 days after MCA occlusion. MRI tissue signatures, specified by values of ADCw and T2 were assigned to tissue histopathology. Significant correlations were obtained between MRI signatures at different time points and histopathologic measurements of lesion area obtained at 1 week. In addition, we compared the temporal evolution of MRI tissue signatures to a separate population of animals at which histological data were obtained at select times of reperfusion. A significant shift (p < or = 0.05) within signatures reflecting tissue histopathology was demonstrated as the ischemic lesion evolved over time. Our data suggest, that the MRI signatures are associated with the degree of ischemic cell damage. Thus, the tissue signature model may provide a noninvasive means to monitor the evolution of ischemic cell damage and to predict final outcome of ischemic cell damage.

Animals↗

PubMed1997

A new rat model of thrombotic focal cerebral ischemia.

We developed a fibrin-rich thrombotic focal cerebral ischemic model with reproducible and predictable infarct volume in rats. In male Wistar rats (n = 77), a thrombus was induced at the origin of the middle cerebral artery (MCA) by injection of thrombin via an intraluminal catheter placed in the intracranial segment of the internal carotid artery (ICA). Thrombus induction and consequent ischemic cell damage were examined by histopathological analysis and neurological deficit scoring, and by measuring changes in cerebral blood flow (CBF) using laser-Doppler flowmetery (LDF), perfusion-weighted imaging (PWI), and by diffusion weighted imaging (DWI). Histopathology revealed that a fibrin-rich thrombus localized to the origin of the right MCA. Regional cerebral blood flow (rCBF) in the right parietal cortex was reduced by 34-58% of preinjection levels after injection of thrombin in rats administered 30 U of thrombin (n = 10). Magnetic resonance imaging (MRI) showed a reduction in CBF and a hyperintensity DWI encompassing the territory supplied by the right MCA. The infarct volume in rats administered 80 U of thrombin was 31.29 +/- 12.9% of the contralateral hemisphere at 24 h (n = 13), and 34.7 +/- 16.4% of the contralateral hemisphere at 168 h (n = 6). Rats administered 30 U of thrombin exhibited a hemispheric infarct volume of 34.0 +/- 14.5% (n = 9) at 24 h and 29.7 +/- 13.9% (n = 8) at 168 h. In addition, thrombotic rats (n = 3) treated with recombinant tissue plasminogen activator (rt-PA) (10 mg/kg) 2 h after thrombosis showed that CBF rapidly returned towards preischemic values as measured by PWI. This model of thrombotic ischemia is relevant to thromboembolic stroke in humans and may be useful in documenting the safety and efficacy of thrombolytic intervention as well as for investigating therapies complementary to antithrombotic therapy.

Animals↗

PubMed1997

Immunoreactivity of cyclin D1/cdk4 in neurons and oligodendrocytes after focal cerebral ischemia in rat.

We investigated the expression of cyclin D1 and its kinase, cdk4, after induction of focal cerebral ischemia in the rat. Brain from rats (n = 6) subjected to 2 hours of transient middle cerebral artery occlusion and 46 hours of reperfusion, and control sham-operated (n = 3) and normal (n = 2) rats were processed for dual label immunohistochemical study for cellular identification of the expression of these cell cycle proteins. Antibodies raised against microtubule-associated protein 2 and neuronal specific enolase for neurons, glial fibrillary acidic protein for astrocytes, myelin basic protein for oligodendrocytes and lectin histochemical study with the B4-isolectin for microglia were used for cell type identification. Double staining for DNA fragmentation detection (TUNEL) and expression of cyclin D1 and cdk4 also was performed. Cyclin D1 and cdk4 were selectively expressed in morphologically intact or altered neurons and oligodendrocytes localized to the ischemic tissue. Apoptotic cells were not immunoreactive to cyclin D1 and cdk4 at 46 hours after 2 hours of middle cerebral artery occlusion. The selective expression of cell cycle proteins observed in nonapoptotic ischemic postmitotic neurons and oligodendrocytes suggests a role for these proteins in cell survival after transient focal cerebral ischemia.

Animals↗

PubMed1997

A mouse model of embolic focal cerebral ischemia.

We developed a mouse model of embolic focal cerebral ischemia, in which a fibrin-rich clot was placed at the origin of the middle cerebral artery (MCA) in C57BL/6J mice (n = 31) and B6C3 mice (n = 10). An additional three non-embolized C57BL/6J mice were used as a control. Embolus induction, cerebral vascular perfusion deficit, and consequent ischemic cell damage were confirmed by histopathology, immunohistochemistry, laser confocal microscopy, and regional cerebral blood flow (rCBF) measurements. Reduction in rCBF and cerebral infarct were not detected in the control animals. An embolus was found in all C57BL/6J and B6C3 mice at 24 hours after injection of a clot. Regional CBF in the ipsilateral parietal cortex decreased to 23% (P < 0.05) and 17% (P < 0.05) of preembolization levels immediately and persisted for at least 1 hour in C57BL/6J mice (n = 6) and in B6C3 mice (n = 3), respectively. A significant decrease of rCBF was accompanied by a corresponding reduction of plasma perfusion in the ipsilateral MCA territory. Neurons exhibited marked reduction in microtubule-associated protein-2 immunostaining coincident with the area of perfusion deficit. The percent infarct volume was 30.3% +/- 13.4% for C57BL/6J mice (n = 17), and 38.3% +/- 15.3% for B6C3 mice (n = 7) at 24 hours after embolization. This model of embolic ischemia is relevant to thromboembolic stroke in humans and may be useful to investigate embolic cerebral ischemia in the genetically altered mouse and for evaluation of antiembolic therapies.

Animals↗

PubMed1997

Photodynamic therapy of 9L gliosarcoma with liposome-delivered photofrin.

The effect of Photofrin encapsulated in a liposome delivery vehicle for photodynamic therapy (PDT) of the 9L gliosarcoma and normal rat brain was tested. We hypothesized that the liposome vehicle enhances therapeutic efficacy, possibly by increasing tumor tissue concentration of Photofrin. Male Fisher rats bearing a 9L gliosarcoma were treated 16 days after intracerebral tumor implantation with either Photofrin in dextrose (n = 5) or Photofrin in liposome (n = 6). Nontumor-bearing animals were treated with Photofrin delivered either in dextrose (n = 4) or liposome (n = 4) vehicle. Tissue concentrations of Photofrin delivered either in dextrose (n = 4) or liposome (n = 4) vehicle were measured in tumor, brain adjacent to tumor and in normal brain tissue. Photofrin was administered (intraperitoneally) at a dose of 12.5 mg/kg and PDT (17 J/cm2 of 632 nm light at 100 mW/cm2) was performed 24 h after Photofrin administration. Brains were removed 24 h after PDT and stained with hematoxylin and eosin for analysis of cellular damage. The PDT using Photofrin in the liposome vehicle caused significantly more damage to the tumor (P < 0.001) than did PDT with Photofrin in dextrose. The PDT of tumor with Photofrin delivered in liposomes caused a 22% volume of cellular necrosis, while PDT of tumor with Photofrin delivered in dextrose caused only scattered cellular damage. Photofrin concentration in tumors was significantly higher (P = 0.021) using liposome (33.8 +/- 18.9 micrograms/g) compared to dextrose delivery (5.5 +/- 1.5 micrograms/g). Normal brain was affected similarly in both groups, with only scattered cellular necrosis. Our data suggest that the liposome vehicle enhances the therapeutic efficacy of PDT treatment of 9L tumors.

Animals↗

PubMed1997

Cathepsin B and middle cerebral artery occlusion in the rat.

Lysosomal proteases, although tightly regulated under physiological conditions, are known to contribute to cell injury after various forms of tissue ischemia have occurred. Because cathepsin B is a prominent lysosomal protease found in brain parenchyma, the authors hypothesized that it may contribute to neuronal cell death after focal cerebral ischemia. The authors measured the expression and spatial distribution of cathepsin B within the ischemic brain in 43 animals by means of immunohistochemical analysis in a rat model of transient middle cerebral artery (MCA) occlusion. Cathepsin B activity was also measured within specific ischemic brain regions by using an in vitro assay (22 animals). In addition, the authors tested the therapeutic effect of preischemic intraventricular administration of stefin A, a cysteine protease inhibitor, on the volume of cerebral infarction after transient MCA occlusion (15 animals). Increased cathepsin B immunoreactivity was detected exclusively within the ischemic neurons after 2 hours of reperfusion following a 2-hour MCA occlusion. Cathepsin B immunolocalization in the ischemic region decreased by 24 hours of reperfusion, but then increased by 48 hours of reperfusion because the infarct was infiltrated by inflammatory cells. Increased immunolocalization of cathepsin B in the inflammatory cells located in the necrotic infarct core continued through 7 days of reperfusion. Cathepsin B enzymatic activity was significantly increased in the ischemic tissue at 2, 8, and 48 hours, but not at 24 hours of reperfusion after 2 hours of MCA occlusion. Continuous intraventricular infusion of stefin A, before 2 hours of MCA occlusion (15 animals), significantly reduced infarct volume compared with control animals (12 animals): the percentage of hemispheric infarct volume was 20+/-3.9 compared with 33+/-3.5 (standard error of the mean; p = 0.025). These data indicate that neuronal cathepsin B undergoes increased expression and activation within 2 hours of reperfusion after a 2-hour MCA occlusion and may be a mechanism contributing to neuronal cell death. Intraventricular infusion of stefin A, an inhibitor of cathepsin B, significantly reduces cerebral infarct volume in rats.

Animals↗