Relationship between Shear Stiffness Measured by MR Elastography and Perfusion Metrics Measured by Perfusion CT of Meningiomas

BACKGROUND AND PURPOSE

When managing meningiomas, intraoperative tumor consistency and histologic subtype are indispensable factors influencing operative strategy. The purposes of this study were the following: 1) to investigate the correlation between stiffness assessed with MR elastography and perfusion metrics from perfusion CT, 2) to evaluate whether MR elastography and perfusion CT could predict intraoperative tumor consistency, and 3) to explore the predictive value of stiffness and perfusion metrics in distinguishing among histologic subtypes of meningioma.

MATERIALS AND METHODS

Mean tumor stiffness and relative perfusion metrics (blood flow, blood volume, and MTT) were calculated (relative to normal brain tissue) for 14 patients with meningiomas who underwent MR elastography and perfusion CT before surgery (cohort 1). Intraoperative tumor consistency was graded by a neurosurgeon in 18 patients (cohort 2, comprising the 14 patients from cohort 1 plus 4 additional patients). The correlation between tumor stiffness and perfusion metrics was evaluated in cohort 1, as was the ability of perfusion metrics to predict intraoperative tumor consistency and discriminate histologic subtypes. Cohort 2 was analyzed for the ability of stiffness to determine intraoperative tumor consistency and histologic subtypes.

RESULTS

The relative MTT was inversely correlated with stiffness (P = .006). Tumor stiffness was positively correlated with intraoperative tumor consistency (P = .01), while perfusion metrics were not. Relative MTT significantly discriminated transitional meningioma from meningothelial meningioma (P = .04), while stiffness did not significantly differentiate any histologic subtypes.

CONCLUSIONS

In meningioma, tumor stiffness may be useful to predict intraoperative tumor consistency, while relative MTT may potentially correlate with tumor stiffness and differentiate transitional meningioma from meningothelial meningioma.

Influence of Oral Anaerobic Bacteria on Hematopoietic Stem Cell Transplantation Patients: Oral Mucositis and General Condition

OBJECTIVE

Oral mucositis (OM) caused by infection facilitated by myelosuppression and immunosuppression can be controlled through oral care. We investigated changes in oral anaerobic bacterial flora during the onset of OM with hematopoietic stem cell transplantation (HSCT).

METHODS

This study included 19 patients who underwent HSCT. All received professional oral care before initiating the preparative regimen. We assessed OM, oral health and obtained microbial samples from the oral cavity during 5 assessment points: before initiating the preparative regimen; the day before HSCT (day 1); and at 7, 14, and 30 days after HSCT. Microbial species were identified by using a mass spectrometer.

RESULTS

The number of patients with serious OM increased initially after HSCT and decreased thereafter. Many Streptococcus species were identified before HSCT, but these gradually decreased and were replaced by coagulase-negative staphylococci. An increase in Candida species after HSCT and the identification of Enterococcus species were significantly associated with OM. Nutritional status recovery and prognosis were significantly worse in patients who developed OM.

CONCLUSIONS

To the best of our knowledge, this study is the first which shows that anaerobic bacteria were identified in patients' oral flora before and after HSCT by using a mass spectrometer. These results indicate that Enterococcus species and Candida species may have been associated with OM. OM affected the patients' improvement in nutritional status and their prognosis. We concluded that it is important to provide more complete oral care instructions and interventions to prevent these bacterial infections.

High-Tc nodeless s±-wave superconductivity in (Y,La)FeAsO(1-y) with Tc=50 K:75As-NMR study

We report on an (75)As-NMR study on the Fe-pnictide high-T(c) superconductor Y(0.95)La(0.05)FeAsO(1-y) (Y(0.95)La(0.05)1111) with T(c)=50 K that includes no magnetic rare-earth elements. The measurement of the nuclear-spin lattice-relaxation rate (75)(1/T(1)) has revealed that the nodeless bulk superconductivity takes place at T(c)=50 K while antiferromagnetic spin fluctuations develop moderately in the normal state. These features are consistently described by the multiple fully gapped s(±)-wave model based on the Fermi-surface nesting. Incorporating the theory based on band calculations, we propose that the reason that T(c)=50 K in Y(0.95)La(0.05)1111 is larger than T(c)=28 K in La1111 is that the Fermi-surface multiplicity is maximized, and hence the Fermi-surface nesting condition is better than that in La1111.

Evaluation of cervical myelopathy using apparent diffusion coefficient measured by diffusion-weighted imaging

BACKGROUND AND PURPOSE

Intramedullary high signal intensity on T2-weighted imaging was frequently observed in patients with CSM, although this finding does not well correlate with severity or prognosis of CSM. Instead of this nonquantitative information, another measure for CSM is desired. The work was focused primarily on assessing the relationships between ADC values and clinical and radiologic severity for the diagnosis of CSM.

MATERIALS AND METHODS

The relationship between ADC values measured in the spinal cord at 322 intervertebral levels of 66 patients and clinical factors were analyzed.

RESULTS

ADC values in the spinal cord significantly increased with the degree of spinal cord compression and decreased with time after decompression surgery. Patients with higher ADC values had lower preoperative JOA scores and tended to show poorer clinical recovery.

CONCLUSIONS

ADC values appear to indicate the severity of spinal cord compression and clinical recovery after decompression surgery, so spondylotic myelopathy may partly be predicted preoperatively by using ADC values.

Antiferromagnetic spin fluctuations and unconventional nodeless superconductivity in an iron-based new superconductor (Ca4Al2O(6-y))(Fe2As2): 75As nuclear quadrupole resonance study

We report 75As nuclear quadrupole resonance studies on (Ca4Al2O(6-y))(Fe2As2) with T(c) = 27  K. Measurement of nuclear-spin-relaxation rate 1/T1 has revealed a significant development of two-dimensional antiferromagnetic spin fluctuations down to T(c) in association with the smallest As-Fe-As bond angle. Below T(c), the temperature dependence of 1/T1 without any trace of the coherence peak is well accounted for by a nodeless s(±)-wave multiple-gaps model. From the fact that its T(c) is comparable to T(c) = 28  K in the optimally doped LaFeAsO(1-y) in which antiferromagnetic spin fluctuations are not dominant, we remark that antiferromagnetic spin fluctuations are not a unique factor for enhancing T(c) among Fe-based superconductors, but a condition for optimizing superconductivity should be addressed from the lattice structure point of view.

Inverse correlation of HER2 with MHC class I expression on oesophageal squamous cell carcinoma

BACKGROUND

As HER2 is expressed in 30% of oesophageal squamous cell carcinomas (ESCCs), T-cell-based immunotherapy and monoclonal antibodies targeted against HER2 are attractive, novel approaches for ESCCs. However, it was shown that there is an inverse correlation between HER2 and MHC class I expression on tumours. Thus, the correlation between HER2 and MHC class I expressions on ESCC was evaluated.

METHODS

Expressions of MHC class I and HER2 in ESCC tissues (n=80) and cell lines were assessed by immunohistochemistry, fluorescence in situ hybridisation (FISH), and flow cytometry. We investigated whether HER2 downregulation with small interfering RNA (siRNA) in ESCC cell lines could upregulate the expression of MHC class I and the antigen presentation machinery components, and could increase their sensitivity for tumour antigen-specific CTLs.

RESULTS

There was an inverse correlation between HER2 and MHC class I expressions in both tumour tissues and cell lines. Downregulation of HER2 with siRNA resulted in the upregulation of MHC class I expression, leading to increased CTL recognition by tumour antigen-specific CTLs.

CONCLUSION

HER2-overexpressing ESCC tumour cells showed a reduced sensitivity for CTLs through the downregulation of MHC class I.

Diagnostic value of spinal MR imaging in spontaneous intracranial hypotension syndrome

BACKGROUND AND PURPOSE

Spontaneous intracranial hypotension (SIH) presents with orthostatic headache, and the diagnosis is made on the basis of low CSF pressure and brain MR imaging findings characteristic of the disorder. However, a broad spectrum of symptoms and MR imaging findings of SIH is recognized, and some cases have no typical MR imaging abnormalities. SIH is believed to be caused by CSF leakage from the spinal dural sac, whereas the usefulness of MR imaging of the spine remains unclear. Our aim was to elucidate the diagnostic value of brain and spinal MR imaging

MATERIALS AND METHODS

The sensitivities for the detection of SIH were retrospectively evaluated in 18 patients with SIH treated in our institutions between January 1998 and August 2007.

RESULTS

Brain MR imaging detected abnormalities in 15 of the 18 patients (83%): diffuse pachymeningeal enhancement in 15 (83%), descent of the cerebellar tonsil in 13 (72%), brain stem sagging in 13 (72%), enlargement of the pituitary gland in 12 (67%), and subdural fluid collection in 13 (72%). Spinal MR imaging detected abnormalities in 17 of the 18 patients (94%): distention of the epidural veins in 14 (78%), epidural fluid collection on fat-saturated T2-weighted images in 16 (89%), and abnormal visualization of the nerve root sleeve in only 1 (6%). The sensitivity for SIH was 83% for brain MR imaging and 94% for spinal MR imaging.

CONCLUSIONS

Spinal MR imaging is useful for the diagnosis of SIH, especially in the early stage.

Decreased diameter of the optic nerve sheath associated with CSF hypovolemia

The subarachnoid space around the optic nerve can be detected by fat-saturated T2-weighted MR imaging of the orbit, and dilation of this space reflects increased intracranial pressure. We examined 3 patients with CSF hypovolemia with MR imaging of the orbit and measured the optic nerve sheath diameter before and after treatment. We showed that the subarachnoid space is decreased in patients with CSF hypovolemia and the usefulness of this finding.

Dural arteriovenous fistulas of the cavernous sinus with onset of intracerebral haemorrhage mimicking hypertensive putaminal hemorrhage

We describe a patient with dural arteriovenous fistulas of the cavernous sinus (CS-dAVFs) who developed an intracerebral haemorrhage (ICH) mimicking hypertensive putaminal haemorrhage. Drainage into the superior ophthalmic vein (SOV) and inferior petrosal sinus (IPS) was not demonstrated on cerebral angiography, and only cortical venous reflux into the Sylvian vein was observed. In cases of venous drainage concentrated on the Sylvian vein, CS-dAVFs could indicate ICH with radiological appearance resembling putaminal haemorrhage.

Postoperative three-dimensional CT angiography after cerebral aneurysm clipping with titanium clips: detection with single detector CT. Comparison with intra-arterial digital subtraction angiography

AIM

To assess the significance of three-dimensional computed tomography angiography (3D-CTA) in detecting remnant necks after cerebral aneurysm clipping.

MATERIALS AND METHODS

A total of 59 patients (77 aneurysms) underwent surgery using titanium clips. Two blinded observers independently evaluated the presence of neck remnants on shaded-surface display (SSD) imaging, volume rendered (VR) imaging, and intra-arterial digital subtraction angiography (IADSA).

RESULTS

Mean sensitivity and specificity for detecting neck remnants were 50.0 and 74.2% for SSD imaging, 61.5 and 82.8% for VR imaging, and 92.3 and 92.2% for IADSA, respectively. Receiver operating characteristic (ROC) analysis revealed excellent diagnostic performance for IADSA [mean area under ROC curve (Az)=0.97], and good diagnostic performance for 3D-CTA (Az=0.70 and 0.76 for SSD and VR, respectively). Specificity of VR was better than that SSD (p=0.082), however, there was no significant difference between them.

CONCLUSION

Use of 3D-CTA techniques can facilitate postoperative evaluation.

Carotid-cavernous fistula associated with an intracranial lesion caused by cortical venous reflux

SUMMARY

Digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) findings in 20 patients with carotid-cavernous fistula (CCF; 3 direct CCFs and 17 indirect CCFs) were retrospectively reviewed to evaluate venous drainage patterns that may cause intracerebral haemorrhage or venous congestion of the brain parenchyma. We evaluated the relationship between cortical venous reflux and abnormal signal intensity of the brain parenchyma on MRI. Cortical venous reflux was identified on DSA in 12 of 20 patients (60.0%) into the superficial middle cerebral vein (SMCV; n=4), the uncal vein (n=2), the petrosal vein (n=2), the lateral mesencephalic vein (LMCV; n=1), the anterior pontomesencephalic vein (APMV; n=1), both the APMV and the petrosal vein (n=1) and both the uncal vein and the SMCV (n=1). Features of venous congestion, such as tortuous and engorged veins, focal staining and delayed appearance of the veins, were demonstrated along the region of cortical venous reflux in the venous phase of internal carotid or vertebral arteriography in six of 20 patients (30.0%). These findings were not observed in the eight CCF patients who did not demonstrate cortical venous reflux. MRI revealed abnormal signal intensity of the brain parenchyma along the region with cortical venous reflux in four of 20 indirect CCF patients (20%). Of these four patients, one presented with putaminal haemorrhage, while the other three presented with hyperintensity of the pons, the middle cerebellar peduncle or both on T2- weighted images, reflecting venous congestion. The venous drainage routes were obliterated except for cortical venous reflux in these four patients and the patients without abnormal signal intensity on MRI had other patent venous outlets in addition to cortical venous reflux. CCF is commonly associated with cortical venous reflux. The obliteration or stenosis of venous drainage routes causes a converging venous outflow that develops into cortical venous reflux and results in venous congestion of the brain parenchyma or intracerebral haemorrhage. Hyperintensity of brain parenchyma along the region of cortical venous reflux on T2-weighted images reflects venous congestion and is the crucial finding that indicates concentration of venous drainage into cortical venous reflux.

Multiple spinal dural arteriovenous fistulas

Multiple spinal dural arteriovenous fistulas (DAVFs) have been rarely reported and only two such cases are found in the literature. A 71-year-old man complained of muscle weakness and hypesthesia in both legs and angiographically diagnosed as thoracic DAVF. The fistula was surgically treated, however, the symptoms recurred 14 months after the first treatment. Angiography revealed a new fistula in the lumbar region and this was also treated surgically. In the previously reported cases of multiple spinal DAVFs, the second fistulas were also diagnosed after the initial treatment. Symptomatic patients after the initial treatment of DAVF should be re-examined angiographically.

Extradural neuromas at the petrous apex: report of two cases

OBJECTIVE AND IMPORTANCE

Two rare cases of middle cranial fossa neuroma located in the epidural space at the petrous apex are reported.

CLINICAL PRESENTATION

Two women, aged 58 and 49 years, were admitted to our hospital with diagnoses of cavernous sinus tumor. Analysis of preoperative computed tomography scans showed bone erosion of the petrous apex, and magnetic resonance imaging demonstrated the presence of an extradural mass located along the course of the petrous internal carotid artery in both patients.

INTERVENTION

The tumor was completely removed in one patient and partially removed in the other by use of the epidural middle cranial fossa transpetrosal approach. In both patients, histological examination of tumor specimens revealed neuroma.

CONCLUSION

Because surgical exploration revealed that these epidural tumors adhered tightly to the internal carotid artery, and because they had no relationship to the trigeminal nerve, facial nerve, or proximal greater superficial petrosal nerve, in our opinion, these tumors originated from the distal portion of the greater superficial petrosal nerve or the deep petrosal nerve. These neuromas were mainly found in a site under the cavernous sinus at the petrous apex, a location not previously reported.

Induction of mitochondrial heat shock protein 60 and 10 mRNAs following transient focal cerebral ischemia in the rat

Heat shock proteins (HSPs) 60 and 10 are stress-inducible mitochondrial matrix proteins that form a chaperonin complex that is important for mitochondrial protein folding and function. The effect of cerebral ischemia on mitochondrial HSPs is unclear. The topographical and chronological patterns of HSP60 and HSP10 messenger ribonucleic acid (mRNA) expression and induction were investigated in the rat focal cerebral ischemia model. Focal cerebral ischemia was produced by transient middle cerebral artery occlusion for 30 or 90 min. Expression of mRNAs was analyzed using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. RT-PCR analysis showed that both HSP60 and HSP10 mRNA levels increased significantly in the ischemic cortex from 4 to 24 h of reperfusion after 30 min of occlusion. In situ hybridization analysis demonstrated significant induction of both mRNAs in the whole ischemic cortex after 30 min of occlusion and in the dorsomedial border (penumbra) of the ischemic cortex and ipsilateral hippocampus after 90 min of occlusion. Expression patterns and the timing of the induction of both HSP60 and HSP10 mRNAs were identical throughout the experiments. Simultaneous induction of the mRNAs for the mitochondrial chaperonins, HSP60 and HSP10, in various regions in focal cerebral ischemia demonstrates that mitochondrial stress conditions persist concomitantly with cytosolic stress conditions in focal cerebral ischemia.

Simultaneous induction of mitochondrial heat shock protein mRNAs in rat forebrain ischemia

Several investigations have postulated evidence of the involvement of apoptosis in delayed neuronal death following brief periods of global cerebral ischemia. Apoptosis may be closely linked to mitochondrial dysfunction. Heat shock protein (HSP) 60 and HSP10 are mitochondrial matrix proteins induced by stress and form the chaperonin complex that is implicated in protein folding and assembly within the mitochondria. This study investigated the induction of these mitochondrial stress protein genes in the hippocampal CA1 region and less vulnerable regions following transient forebrain ischemia. In situ hybridization analysis revealed that the induction pattern of HSP60 mRNA was identical to that of HSP10 mRNA throughout the entire ischemic course. No changes occurred in the expression of both mRNAs after 2 min ischemia. Strong induction of both mRNAs occurred in the CA1 region after 10 min ischemia and persisted until 1 d after reperfusion. In contrast, induction of both mRNAs in the less vulnerable regions was terminated by 1 d after reperfusion. These results demonstrate that mitochondrial stress conditions persist concomitantly with cytosolic stress conditions in regions vulnerable to transient forebrain ischemia.

High uptake of 123I-metaiodobenzylguanidine related to olfactory neuroblastoma revealed by single-photon emission CT

We studied a case of olfactory neuroblastoma by noting 123I-metaiodobenzylguanidine (MIBG) uptake revealed by single-photon emission CT (SPECT). MR imaging revealed an enhancing tumor extending from the left nasal cavity to the bilateral anterior frontal cranial fossae. SPECT revealed high 123I-MIBG uptake in the enhancing tumor. SPECT-revealed 123I-MIBG uptake appears to be clinically useful for distinguishing olfactory neuroblastomas from other tumors, especially suprasellar meningiomas.

Induction of cyclooxygenase-2 messenger RNA after transient and permanent middle cerebral artery occlusion in rats: comparison with c-fos messenger RNA by using in situ hybridization

OBJECT

Recently, two different cyclooxygenase (COX) genes, COX-1 and -2, were identified. In this study, topographic and chronological profiles of COX-2 messenger (m)RNA and c-fos mRNA expression were investigated using in situ hybridization after focal cerebral ischemia.

METHODS

Rats undergoing permanent ischemia were decapitated at 30 and 90 minutes and at 2, 4, 8, and 24 hours after middle cerebral artery (MCA) occlusion, and rats undergoing transient ischemia were decapitated at 4, 8, and 24 hours after MCA occlusion that lasted for either 30 or 90 minutes. After brief transient MCA occlusion, c-fos mRNA was induced in the whole MCA territory, adjacent cortex (cingulate cortex), and distant brain regions such as the hippocampus and substantia nigra. In contrast, COX-2 mRNA was not induced in the ischemic core (lateral striatum) but only in the penumbral area (MCA cortex). Long transient and permanent MCA occlusion did not induce c-fos and COX-2 mRNAs in the ischemic core but strongly induced both mRNAs in the penumbral area (medial striatum and periphery of MCA cortex) and adjacent cortex (cingulate cortex). In brain regions distant from the ischemic territory, although c-fos mRNA was induced in the thalamus, substantia nigra, and hippocampus after extended transient and permanent occlusion, COX-2 mRNA was only induced in the bilateral hippocampi. The induction of COX-2 mRNA persisted in all locations even at 24 hours after MCA occlusion.

CONCLUSIONS

The distribution of COX-2 mRNA induction was apparently different from that of c-fos mRNA after MCA occlusion. These results pertaining to COX-2 mRNA agree well with the previous observations of changes in prostaglandin metabolism induced by focal cerebral ischemia. However, whether this induction of the COX-2 gene contributes to the histopathological outcome of cerebral ischemia remains to be elucidated.

Distant metastasis of liposarcoma to the dura and skull: a case report

A case of metastatic liposarcoma of both skull and brain originating from the lower extremity is described. A 44-year-old male underwent removal of a myxoid type liposarcoma in his left upper thigh and a second operation for local recurrence. A metastatic liposarcoma was also discovered in the mediastinum and treated by radiotherapy. Six years after the initial onset, he presented with progressive consciousness disturbance, motor aphasia, right hemiparesis and subcutaneous swelling in the left frontal region. Neuroimaging showed a large tumour extending both intracranially and extracranially across the eroded skull. The intracranial portion of the tumour had invaded the frontal lobe. The tumour was subtotally removed. The operative findings suggested that the tumour had metastasized to the dura mater or the skull initially, and invaded the surrounding tissues. The histological appearance was the same as those of the previous tumours.

Activation of Arc gene, a dendritic immediate early gene, by middle cerebral artery occlusion in rat brain

The effect of middle cerebral artery (MCA) occlusion on the activity-regulated cytoskeleton-associated protein (Arc) mRNA expression has been investigated using in situ hybridization. It was induced in the extensive regions of cerebral cortex, medial striatum, and distant areas such as the ipsilateral lateral septal nucleus, bilateral hippocampal formation and contralateral amygdala following MCA occlusion. In the hippocampal formation, it was induced in the granule cell layer and the stratum pyramidale at 1 h and in the molecular layer and in the stratum oriens and stratum radiatum bilaterally at 4 h. MK-801 pretreatment strongly attenuated the induction of Arc mRNA. The present results suggest that Arc may play an important role in the neuronal plasticity through NMDA activation following focal cerebral ischemia.

Multimodality treatment for large and critically located arteriovenous malformations

To define the current status of the multimodality treatment for large and critically located arteriovenous malformations (AVMs), we have made a retrospective review of 54 consecutive patients with Spetzler-Martin grade IV and V AVMs. The size of nidus is larger than 3 cm in diameter in all cases. Initially, all but one were treated by nidus embolization with the aim of size reduction. Only one patient had complete nidus occlusion by embolization alone. In 52 patients, the obliteration rate of nidus volume averaged 60% after embolization. Ten patients underwent complete surgical resection of AVMs following embolization with no postoperative neurological deterioration. Thirty-one patients underwent stereotactic radiosurgery following embolization. At the time of this analysis, 30 patients underwent follow-up angiography 2-3 years after radiosurgery. The results of radiosurgery correlated well with the preradiosurgical AVM volume. Of 16 patients with small residual AVMs (< 10 cm3, a mean volume of 4.7 cm3), nine (56%) had complete obliteration, and six (38%) had near-total or subtotal obliteration by 3 years after radiosurgery. In contrast, of 14 patients with large residual AVMs (> or = 10 cm3, a mean volume of 17.9 cm3), only two (14%) had complete obliteration, and eight (57%) had near-total or subtotal obliteration. Repeat radiosurgery was performed for the patients with remaining AVMs at 3-year follow-up review. This study indicates that a certain number of large and critically located AVMs can be safely treated by either microsurgery or radiosurgery following a significant volume reduction by nidus embolization. The present data also suggest the need and possible role of repeat radiosurgery in improving complete obliteration rate of large difficult AVMs, since many of those AVMs have significantly responded to initial radiosurgery.

Induction of Rheb mRNA following middle cerebral artery occlusion in the rat

Rheb is a recently identified member of the Ras super-family and is an immediate early gene that is rapidly and transiently induced in the hippocampal granule cells by NMDA-dependent synaptic activity in the long term potentiation paradigm. The close homologies with Ras and its rapid inducibility strongly suggest that Rheb shares many biochemical and signaling properties with Ras. The present study investigated the effect of middle cerebral artery (MCA) occlusion on the expression of Rheb mRNA in the rat brain. In situ hybridization autoradiography showed that Rheb mRNA was induced in the extensive regions of cerebral cortex and medial striatum surrounding the ischemic region and bilateral hippocampal formation following MCA occlusion. The induction of Rheb mRNA in the cingulate cortex persisted prominently at 24 h of MCA occlusion. Although the Rheb mRNA induction in the medial striatum and hippocampal formation decreased after 8h of occlusion, it still remained significant at 24h of occlusion. The data suggest the possibility that Ras signaling pathways can be implicated in the cerebral ischemia-elicited events through NMDA receptor activation.

Amelioration of vasospasm after subarachnoid hemorrhage in transgenic mice overexpressing CuZn-superoxide dismutase

BACKGROUND AND PURPOSE

To clarify the effect of superoxide dismutase (SOD) on vasospasm after subarachnoid hemorrhage (SAH), we investigated sequential changes in arterial diameter after SAH in transgenic mice overexpressing CuZn-SOD (SOD-1).

METHODS

SOD-transgenic mice and nontransgenic littermates (35 to 40 g) were subjected to SAH produced by endovascular perforation of left anterior cerebral artery. At 4 hours and 1, 3, 7, and 14 days after SAH, the mice were perfused with 10% formalin and consequently with a mixture of carbon black and 10% gelatin to cast all vessels. Vasospasm was evaluated by measuring the diameter of the left middle cerebral artery (MCA) with a microscope.

RESULTS

In nontransgenic mice, the diameter of the MCA on day 3 after SAH (110.5+/-20.5 microm [mean+/-SD]; n=16) was significantly reduced compared with that without SAH (138.5+/-14.5 microm; n=12) (P<0.01). Moreover, on day 3 after SAH, the diameter of the MCA in SOD-transgenic mice (127. 9+/-20.2 microm; n=20) was significantly larger than that in nontransgenic mice (110.5+/-20.5 microm; n=16) (P<0.05).

CONCLUSIONS

These results suggest that SOD is effective on the amelioration of vasospasm after SAH and that oxygen free radicals, particularly superoxide, play an important role in the pathogenesis of vasospasm after SAH.

Role of superoxide dismutase in ischemic brain injury: a study using SOD-1 transgenic mice

1. Nitric oxide radicals (NO) play an important role in the pathophysiology of focal cerebral ischemia. 2. Vascular NO can reduce ischemic brain injury by increasing CBF, whereas neuronal NO may mediate neurotoxicity following brain ischemia, mainly by its reaction with superoxide to generate peroxynitrite. 3. These findings could contribute to a strategy for the treatment of cerebral ischemia.

Dural arteriovenous shunts at the craniocervical junction

OBJECT

A retrospective analysis was conducted of 10 patients (three women and seven men) who were treated for spinal dural arteriovenous shunts (AVSs) located at the craniocervical junction. This analysis was performed to evaluate the characteristics of this unusual location in contrast with those of the more common thoracic and lumbar AVSs.

METHODS

Seven patients presented with subarachnoid hemorrhage (SAH) and one with slowly progressive quadriparesis and dyspnea due to myelopathy. The other two cases were detected incidentally and included a transverse-sigmoid dural AVS and a cerebellar arteriovenous malformation. Angiographic studies revealed that the spinal dural AVSs at the C-1 and/or C-2 levels were fed by the dural branches of the radicular arteries that coursed from the vertebral artery and drained into the medullary veins. Venous drainage was caudally directed in the patient with myelopathy. In contrast, the shunt flow drained mainly into the intracranial venous system in patients with SAH. Furthermore, in four of these patients a varix was found on the draining vein. In all patients, the draining vein was interrupted surgically at the point at which this vessel entered the intradural space, using intraoperative digital subtraction angiography to monitor flow. The postoperative course was uneventful in all patients and no recurrence was confirmed on follow-up angiographic studies obtained in seven patients at 6 months after discharge.

CONCLUSIONS

If computerized tomography scanning shows SAH predominantly in the posterior fossa and no abnormalities are found on intracranial four-vessel angiographic study, proximal vertebral angiography should be performed to detect dural AVS at the craniocervical junction. The results of surgical intervention for this disease are quite satisfactory.

[Differential diagnosis of hyponatremia following subarachnoid hemorrhage]

Hyponatremia is a common complication after subarachnoid hemorrhage (SAH). Although the mechanism of hyponatremia is still controversial, cerebral salt-wasting syndrome (CSNS) is currently regarded as being more responsible than the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). The aim of our study was to assess the plasma volume status of a patient with hyponatremia following subarachnoid hemorrhage. In doing this it may be possible to indirectly differentiate its pathogenesis. Fifty patients with SAH were studied. Twenty patients demonstrated hyponatremia (serum sodium < 135 mEq/L) during day 7 to 13 after subarachnoid hemorrhage. Patients with hyponatremia were categorized on the basis of their daily body weight, and central venous pressure. Group A consisted of patients with hypovolemia (16 patients), with the onset time of hyponatremia being day 7 to 9. Group B included those with hypervolemia (4 patients); hyponatremia was observed during day 10 to 11 and was corrected in all patients within 72 hours after induction of fluid restriction. Our findings suggest that hyponatremia following subarachnoid hemorrhage usually occurs due to CSWS, although SIADH remains as a minor pathogenesis. We conclude that the combination of daily body weight and CVP measurements is a simple and practical method to distinguish promptly SIADH from CSWS.

[Anesthesia in two patients with essential thrombocythemia]

Case 1. The patient was a 69-year-old man with essential thrombocythemia (ET), who underwent urgent laparotomy. On admission he was dehydrated and the platelet count was more than 160 x 10(4).microliter-1, with hematocrit of 50%. Anesthesia was induced with ketamine i.v. and maintained with nitrous oxide and sevoflurane in oxygen. Postoperative care included the administration of gabexate mesilate (GM) which is an antiplatelet agent. Case 2. An 84-year-old woman with ET was diagnosed as gastric cancer and elective gastrectomy was scheduled. The platelet count was more than 100 x 10(4).microliter-1. The patient was anesthetized with nitrous oxide and oxygen supplemented with fentanyl and mepivacaine via epidural catheter. Intravenous infusion of GM was performed at a rate of 1 mg.kg-1.hr-1 during surgery. PF-4 and beta-TG were measured. These are platelet releasing factors. The level of PF-4 decreased to normal level during this procedure. In conclusions, it will be important to use GM during anesthesia in order to avoid the complications such as myocardial or pulmonary infarction caused by thrombocythemia.

Probable brain abscess presenting as a high uptake lesion on thallium-201 single photon emission computed tomography--case report

A 61-year-old male presented with a brain abscess manifesting as high fever and generalized convulsion attacks. Magnetic resonance (MR) imaging disclosed a ring-like enhanced lesion in the parietal lobe. Thallium-201 single photon emission computed tomography (201Tl SPECT) images demonstrated a high uptake lesion with a 201Tl uptake index on the early image of 2.21, which suggested malignant disease. The washout ratio was 0.73. His symptoms and the ring-like enhanced lesion on MR images disappeared after 2 months of antibiotic treatment. The final diagnosis was brain abscess, despite the 201Tl SPECT findings. 201Tl SPECT washout ratio may be a better indicator of brain abscess than uptake index.

[The use of low dose midazolam for the management of spinal anesthesia]

The purpose of this study was to evaluate the effects of low dose midazolam (MZ) on memories and ease of management of spinal anesthesia. The low doses of MZ were administered to 70 patients (ASA 1-2), of whom 37 patients were premedicated with atropine sulfate 0.5 mg and pethidine hydrochloride (group P), with 33 patients receiving no premedication (group N). Double blind randomized trials were conducted with the doses of MZ (0, 0.03, 0.06 mg.kg-1), and MZ was administered i.v. to patients just prior to spinal puncture. The short-term and long-term memories were impaired after administration of MZ in both groups. We conclude that MZ appears to be a suitable replacement for other benzodiazepines for relieving anxiety of patients during surgery.

Inducible nitric oxide synthase following hypoxia in rat cultured glial cells

Nitric oxide (NO) produced by inducible nitric oxide (iNOS) exerts inhibitory and cytotoxic effects on various cells including neuronal cells. In the present study, we examined the ability of rat glial cells to produce NO following hypoxia/reoxygenation in vitro by measuring nitrite. The levels of nitrite produced in the cultured media of glial cells significantly increased after 12-h hypoxia but not after 0- and 6-h hypoxia. The NOS inhibitor, NG-monomethyl-L-arginine, decreased hypoxia-induced nitrite formation. In glial cells after hypoxia/reoxygenation, the iNOS and mRNA and protein expressions were detected by reverse-transcription polymerase chain reaction and by immunocytochemical analysis, respectively. The present study provides the first evidence that hypoxia induces NO production from glial cells. This hypoxia-induced, glial cell-derived NO may play a critical role in the pathogenesis of cerebral ischemia in vivo.

Attenuation of acute and chronic damage following traumatic brain injury in copper, zinc-superoxide dismutase transgenic mice

To elucidate the role of oxygen-derived free radicals and superoxide dismutase in traumatic brain injury (TBI), blood-brain barrier (BBB) permeability, brain edema, behavioral function, and necrotic cavity volume (CV) were evaluated after TBI using nontransgenic (nTg) mice and heterozygous and homozygous transgenic (Tg) mice with a 1.5- (Tg 1.5x), 3.1-(Tg3.1x) and five- (Tg5x) fold increase in human copper, zinc-superoxide dismutase (CuZn-SOD) activity. Traumatic brain injury was produced by the weight-drop method. Evans blue dye leakage 4 hours after injury was attenuated in a CuZn-SOD dose-dependent manner with decreases of 18.6%, 40.9%, and 48.8%, in the Tg1.5x, Tg3.1x, and Tg5x groups, respectively. The water content 6 hours after injury in the Tg3.1x (79.64%) and Tg5x (79.45%) groups was significantly lower than in nTg mice (81.37%). There was an initial decrease in body weight and in motor performance, as measured by beam walk and beam balance tasks undertaken 1 day after TBI. However, the average reduction in beam balance and beam walk performance deficits and changes in body weight postinjury were significantly ameliorated in Tg mice. The CV was significantly smaller in Tg mice than in nTg mice (p < 0.01). These results indicate that superoxide radicals play a deleterious role following TBI. Furthermore, Tg mice provide a useful model for demonstrating the beneficial role of an antioxidant enzyme in TBI without the confounding effect of pharmacokinetics, toxicity, and BBB permeability associated with exogenous agents.

Effects of nitric oxide synthase inhibition on brain infarction in SOD-1-transgenic mice following transient focal cerebral ischemia

To investigate the role of superoxide in the toxicity of nitric oxide (NO), we examined the effect of nitric oxide synthase (NOS) inhibition on brain infarction in transgenic mice overexpressing CuZn-superoxide dismutase (SOD-1). Male SOD-transgenic mice and non-transgenic littermates (30-35 g) were subjected to 60 min of middle cerebral artery occlusion followed by 24 h of reperfusion. Either NG-nitro-L-arginine methyl ester (L-NAME; 3 mg/kg), a mixed neuronal and endothelial NOS inhibitor, or 7-nitroindazole (7-NI; 25 mg/kg), a selective neuronal NOS inhibitor, was administered intraperitoneally 5 min after the onset of ischemia. At 24 h of reperfusion, the mice were decapitated and the infarct volume was evaluated in each group. In the nontransgenic mice, L-NAME significantly increased the infarct volume as compared with the vehicle, while 7-NI significantly decreased it. In the SOD-transgenic mice, L-NAME-treated animals showed a significantly larger infarct volume than vehicle-treated ones, whereas there were no significant differences between 7-NI- and vehicle-treated mice. Our findings suggest that selective inhibition of neuronal NOS ameliorates ischemic brain injury and that both neuronal and endothelial NOS inhibition may result in the deterioration of ischemic injury due to vasoconstriction of the brain. Since L-NAME increased infarct volume even in SOD-transgenic mice, the protective effect of SOD could result from the vasodilation by increased endothelial NO as well as the reduction of neuronal injury due to less production of peroxynitrite compared to wild-type mice. Moreover, the neurotoxic role of NO might not be dependent on NO itself, but the reaction with superoxide to form peroxynitrite, because of no additive effects of SOD and a neuronal NOS inhibitor.

Differential response in the release of hydrogen peroxide between astroglial cells and endothelial cells following hypoxia/reoxygenation

Hydrogen peroxide (H2O2) and lactate dehydrogenase (LDH) released from cultured astroglial cells (AGs) and brain endothelial cells (BECs) were measured following hypoxia/reoxygenation. AGs released H2O2 to the extracellular space from 8 h of hypoxia with the cellular injury indicated by LDH increase. In contrast, BECs released H2O2 at 4 h of hypoxia, prior to the LDH increase. These results suggest that AGs and BECs play different roles in production and metabolism of oxygen free radicals in the blood-brain barrier (BBB), and AGs may protect the BBB disruption from oxidative stress after hypoxia/reoxygenation.

Induction of brain-derived neurotrophic factor (BDNF) and the receptor trk B mRNA following middle cerebral artery occlusion in rat

Middle cerebral artery (MCA) occlusion in halothane-anesthetized rats induced brain-derived neurotrophic factor (BDNF) and the receptor, trk B mRNA, in brain. In situ hybridization studies showed that BDNF and trk B mRNAs were induced in a widespread region of the ipsilateral cortex outside the infarct at 4 h following MCA occlusion. They were also induced in the bilateral hippocampi which are remote from the ischemic MCA region. These data show that changes in neurotrophic factor and receptor gene expressions can occur in the areas outside the infarct which could survive.

Astroglial cells inhibit the increasing permeability of brain endothelial cell monolayer following hypoxia/reoxygenation

Blood-brain barrier (BBB) is known to be structured with astroglial cells (AGs) and brain endothelial cells (BECs), and it has been proposed that these cells play different roles in the BBB. We cultivated AGs and BECs from infant rats (2-week-old), and these cells were cultured on the opposing side of collagen membrane to produce a co-culture model of the BBB in vitro. Permeability of the cell layer was evaluated by the electrical resistance through the membrane. To clarify the role of AGs in the BBB disruption following ischemia/reperfusion, electrical resistance of the co-culture model was compared to that of BEC monolayer following hypoxia/reoxygenation. The electrical resistance through BEC monolayer showed 55.5 +/- 15.1 percent reduction at 4 h of hypoxia, and 93.3 +/- 5.4 percent reduction at 8 h of hypoxia (n = 8). However, the co-culture model showed attenuation of the reduction (24.8 +/- 14.2 percent) at 4 h of hypoxia (n = 8, P < 0.01), but not at 8 h of hypoxia (95.3 +/- 5.0 percent). These results indicate that AGs reduce the increasing permeability of the BEC monolayer following short duration of hypoxia/reoxygenation. It is suggested that AGs may have a protective effect to the BBB disruption following ischemia/reperfusion.

Expression of c-fos and hsp70 mRNA after traumatic brain injury in transgenic mice overexpressing CuZn-superoxide dismutase

The aim of this study was to determine the role of oxidative stress on c-fos and hsp70 gene expression in transgenic (Tg) mice overexpressing CuZn-superoxide dismutase (SOD-1) following traumatic brain injury (TBI). hsp70 mRNA, as investigated using in situ hybridization, was induced around the lesion at 4 and 24 h, but not at 1 and 48 h, in both Tg and non-transgenic (nTg) mice littermates. The degree of hsp70 induction was somewhat greater in nTg than Tg mice at 4 and 24 h after TBI. c-fos mRNA was induced throughout cortex, hippocampus, caudate putamen and the ventricular wall in Tg and nTg mice. TBI induced c-fos bilaterally in the cortex in both animals. There was a time-dependent difference in cortical c-fos expression between nTg and Tg mice. The induction of c-fos mRNA in the striatum was greater in nTg at 24 h and decreased in both animals by 48 h. Edema of the injured cortex was significantly attenuated in Tg mice at all time points (1-48 h). These data show that the degree of hsp70 induction and the degree, extent, and duration of c-fos induction produced by TBI are affected by levels of superoxide dismutase activity. It is proposed that superoxide radicals affect spreading depression and brain edema produced by TBI and that this effect may either directly or indirectly modulate the expression of the c-fos and hsp70 genes after TBI.

Transgenic mice and knockout mutants in the study of oxidative stress in brain injury

A rapid increase in the need to explore the molecular basis of cellular function and injury in the central nervous system has led neuroscientists to employ transgenic mouse technology. The successful making of transgenic mice (Tg) overexpressing human CuZn-superoxide dismutase (SOD-1) activity has made it possible to investigate the role of oxygen free radicals in ischemic and traumatic brain injury in a molecular fashion. It has been demonstrated that the 3-fold increase in SOD-1 transgene activity in SOD-1 Tg mice offers protection against cerebral ischemia and reperfusion in two different models of focal cerebral ischemia, as compared to nontransgenic wild-type littermates. Studies involving traumatic brain injury have also demonstrated that acute injuries, including brain edema and blood-brain barrier permeability, are significantly reduced in SOD-1 Tg mice. Furthermore, chronic neurological deficits, such as beam walking, beam balance, and body weight, are significantly improved in these transgenic animals following traumatic brain injury. In addition to the SOD-1 Tg mice being a useful tool for the study of CNS injury, targeted disruption of the mouse gene for mitochondrial manganese SOD (SOD-2) has been successful. These SOD-2 knockout mutant mice, in addition to the recently developed knockout mutants of neuronal nitric oxide synthase (NOS), are believed to offer a unique opportunity to elucidate the oxidative mechanisms in brain injury following stroke and trauma.

Effect of phenytoin on cortical Na(+)-K(+)-ATPase activity in global ischemic rat brain

Na(+)K(+)-ATPase activity, water content, and Na+/K+ concentrations in the parietal cortex were measured in untreated and phenytoin-treated rats following global cerebral ischemia. Inhibitory effects of phenytoin treatment on brain edema and changes in Na(+)-K+ concentration with ischemia or ischemia followed by recirculation of varying intervals were assessed. The cortical Na(+)-K(+)-ATPase activity increased in the phenytoin-treated group during and after ischemia. Based on these results, we conclude that phenytoin provides ischemic brain protection by activating cortical Na(+)-K(+)-ATPase activity and by reducing intracellular Na+ and water content.

Expression of c-fos mRNA after a mild focal cerebral ischemia in SOD-1 transgenic mice

To clarify the role of oxygen free radicals in expression of the c-fos protooncogene, the distribution of c-fos mRNA was investigated in CuZn-superoxide dismutase (SOD-1) transgenic (Tg) mice compared to control nontransgenic (nTg) littermates after a mild (i.e. 10 min) focal cerebral ischemia. c-fos mRNA expression occurred at 1 to 6 h after reperfusion in the ipsilateral hippocampus and thalamus in Tg mice, whereas it did only at 1 h in the same regions in nTg mice. In the ipsilateral cortex, there were no significant differences in the pattern of the expression between nTg and Tg mice. These results suggest that oxygen radicals may suppress the expression of c-fos in the hippocampus and thalamus, the areas known to be without blood supply from the middle cerebral artery, following a mild focal cerebral ischemia and reperfusion.

MK-801 inhibits the induction of immediate early genes in cerebral cortex, thalamus, and hippocampus, but not in substantia nigra following middle cerebral artery occlusion

Middle cerebral artery (MCA) occlusion in rats induced c-fos and junB mRNA 4h later in all ipsilateral cortex outside the MCA distribution and in many subcortical structures: medial striatum; most of thalamus including medial and lateral geniculate nuclei: substantia nigra; and hippocampus. The N-methyl-D-aspartate (NMDA) antagonist, MK-801 (4 mg/kg, i.p.) inhibited c-fos and junB mRNA induction in the cortex, striatum, thalamus, and hippocampus but not in the substantia nigra. These data show that c-fos and junB mRNA induction in cortex, striatum, thalamus, hippocampus involves the activation of NMDA receptors whereas different receptors must be implicated in the induction in substantia nigra.

Induction of c-fos, junB, c-jun, and hsp70 mRNA in cortex, thalamus, basal ganglia, and hippocampus following middle cerebral artery occlusion

Middle cerebral artery (MCA) occlusion in halothane-anesthetized rats induced c-fos, junB, and c-jun immediate early gene mRNAs and hsp70 heat shock gene mRNA in brain. In situ hybridization studies showed that c-fos and junB were induced throughout all of the cortex at 1 and 4 h following MCA occlusion. hsp70 was induced in the core and margins of the MCA ischemia. By 24 h, there was little expression of c-fos, junB, c-jun, and hsp70 in the core of the MCA infarct; there was modest induction of hsp70 at the margins of the infarct; and there was diffuse induction of c-fos, junB, and c-jun in all of the cortex outside the infarct. MCA occlusion also induced these genes in subcortical structures. c-fos, junB, and hsp70 were induced in ipsilateral medial striatum, most of thalamus including medial and lateral geniculate nuclei, substantia nigra, and hippocampus. Most of these structures, except for the striatum, are not supplied by the MCA. These data show that changes in gene expression can occur in regions remote from an infarction.

Prolonged expression of hsp70 mRNA following transient focal cerebral ischemia in transgenic mice overexpressing CuZn-superoxide dismutase

The distribution of heat shock protein hsp70 mRNA after 10 min of middle cerebral artery (MCA) occlusion was investigated through in situ hybridization in transgenic (Tg) mice overexpressing CuZn-superoxide dismutase (CuZn-SOD) and in control nontransgenic (nTg) littermates. In the ischemic cortex of nTg mice, hsp70 mRNA was detected 1 h after reperfusion and was observed for up to 6 h. In Tg mice, however, it was still detectable within the cortex even at 24 h. In the caudate putamen, hsp70 mRNA appeared at 1 h and was present for up to 6 h in both nTg and Tg mice. Although hsp70 mRNA was detected in the thalamus only at 1 h in nTg mice, it was observed for up to 6 h in Tg mice. Similarly, hsp70 mRNA was detected in the hippocampus of nTg mice only at 1 h, whereas it was detected in Tg mice at 1 h and continued up to 24 h, with high intensity in the CA1 subfield. Despite the significant amounts of hsp70 mRNA in both Tg and nTg mice following ischemia, there was no observable neuronal necrosis (as assessed using hematoxylin and eosin staining) for up to 7 days. Cortical cerebral blood flow (CBF), measured by laser-Doppler flowmetry, did not differ between nTg and Tg mice during ischemia and reperfusion, despite exhibiting hyperemia following hypoperfusion. These results suggest that oxidative stress affects the expression of hsp70 following temporary focal ischemia. An alteration in oxidation stress, which resulted from reduced levels of superoxide radicals in the presence of the CuZn-SOD transgenes, may permit the prolonged expression of hsp70.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of NGFI-A mRNA following middle cerebral artery occlusion in rats: in situ hybridization study

Middle cerebral artery (MCA) occlusion in halothane-anesthetized rats induced the zinc finger gene, NGFI-A, in brain. In situ hybridization studies showed that NGFI-A was induced throughout all of the cortex following MCA occlusion. By 24 h after MCA occlusion there was little expression of NGFI-A mRNA in the core of the MCA infarct, but the mRNA was still induced in all of cortex outside the infarct. MCA occlusion also induced this gene in subcortical structures: ipsilateral medial striatum; most of thalamus including medial and lateral geniculate nuclei; substantia nigra; and hippocampus at 4 h of MCA occlusion which generally disappeared by 24 h of MCA occlusion. Most of these structures, except for the striatum, are not supplied by the MCA. These data show that changes in brain gene expression can occur in many regions remote from an infarction.

HSP70 heat shock gene regulation during ischemia

The hsp70 gene is induced by denatured protein in injured cells and is an extremely sensitive and reliable marker of cells injured by ischemia, seizures, and toxins. Normal brains have little detectable hsp70 mRNA or HSP70 protein. After status epilepticus produced by systemic injections of kainic acid, however, HSP70 protein is induced in neurons but not glia in brain regions known to be injured by kainic acid. Global and focal ischemia also induce the hsp70 gene in brain. The induction of HSP70 protein in hippocampus following increasing durations of global ischemia correlates with the regional and cellular vulnerability to ischemia: CA1 neurons express HSP70 after the briefest periods of ischemia followed by CA4, CA3, dentate granule neurons, glia, and lastly, endothelial cells. Moreover, as the severity of ischemia worsens, a transcriptional and/or translational blockade of the hsp70 gene occurs in the same order so that moderate degrees of ischemia induce HSP70 in CA3 neurons and dentate granule neurons but not necrotic CA1 neurons, and severe ischemia induces HSP70 in capillary endothelial cells of hippocampus but not in any infarcted neurons or glia throughout the hippocampus. Brief periods of focal ischemia induce HSP70 primarily in neurons, suggesting that even focal ischemia can produce selective neuronal injury without infarction. In some instances, HSP70 immunoreactive astrocytes surround the HSP70 immunostained neurons. Focal ischemia that produces infarction induces HSP70 primarily in endothelial cells of cerebral blood vessels in the regions of infarction and in neurons and astrocytes on the perimeter or the penumbral area of infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of heat shock hsp70 mRNA and HSP70 kDa protein in neurons in the 'penumbra' following focal cerebral ischemia in the rat

Induction of hsp70 heat shock protein (HSP70) and hsp70 mRNA was examined using adjacent sections in the same rat brain following permanent middle cerebral artery (MCA) occlusions, hsp70 mRNA was induced within 4 h of MCA occlusion and persisted for at least 24 h. Cellular resolution autoradiographs suggested that hsp70 mRNA was induced primarily in neurons in the periphery of ischemia both outside and inside of the infarction, with small amounts of hsp70 mRNA being induced in the core of the infarction. HSP70 protein was localized in neurons outside the infarction and in endothelial cells within the infarction at 24 h but not at 4 h following permanent MCA occlusions. It is proposed that the penumbra, one of the areas that can be rescued by pharmacological agents, can be defined anatomically as the volume of tissue outside the area of infarction in which HSP70 protein is expressed primarily in neurons.

Induction of 70-kDa heat shock protein and hsp70 mRNA following transient focal cerebral ischemia in the rat

Induction of the 70-kDa heat shock protein (HSP70) was demonstrated immunocytochemically in adult rats 4 h to 7 days following temporary middle cerebral artery (MCA) occlusions lasting 30, 60, or 90 min. Maximal HSP70 induction occurred approximately 24 h following ischemia. Thirty minutes of ischemia induced HSP70 in neurons throughout the cortex in the MCA distribution, whereas 90 min of ischemia induced HSP70 in neurons in the penumbra. HSP70 protein was induced in endothelial cells in infarcted neocortex following 60-90 min of MCA occlusion, and HSP70 was induced in endothelial cells in infarcted regions of lateral striatum following 30-90 min of MCA occlusion. hsp70 mRNA was induced in the MCA distribution in cortex and to a lesser extent in striatum at 2 h to 3 days following 60 min of ischemia. It is proposed that brief ischemia induces hsp70 mRNA and HSP70 protein in the cells most vulnerable to ischemia--the neurons. HSP70 protein is not induced in most neurons and glia following 60-90 min of ischemia in areas destined to infarct, whereas it is induced in vascular endothelial cells.