The role of calcium ion in anoxia/reoxygenation damage of cultured brain capillary endothelial cells

Capillary endothelial cells are critical targets in both ischemia and reperfusion of the brain. Arachidonic acids and oxygen free radicals have been shown to cause disruption of blood-brain barrier (BBB) by destruction of capillary endothelial cell membrane. However, the exact mechanism of BBB breakdown by cerebral ischemia/reperfusion remains undetermined. The aim of the present study is to clarify the mechanism of intracellular calcium ion ([Ca2+]i) change in brain capillary endothelial cells under anoxia/reoxygenation. Brains capillary endothelial cells were isolated from ten male Sprague-Dawley rats by a two step enzymatic process. [Ca2+]i was measured by means of a confocal laser scanning microscope using Indo 1-A/M as a calcium indicator. The endothelial cells were subjected to anoxia and reoxygenization under different conditions. [Ca2+]i increased gradually during anoxia and slightly decreased after reoxygenation. Indomethacin and SOD suppressed the elevation of [Ca2+]i during anoxia. NG-nitro-L-arginine methyl ester and catalase moderately suppressed the elevation, however nifedipine did not suppress it at all. In this model, rapid [Ca2+]i change was not observed during the reoxygenation phase. The results indicate that the anoxia induced elevation of [Ca2+]i in the brain capillary endothelial cells depends on superoxide and peroxynitrite generation.

The mechanism of reversible osmotic opening of the blood-brain barrier: role of intracellular calcium ion in capillary endothelial cells

Despite clinical and experimental interest in the osmotic opening of the blood-brain barrier (BBB), the mechanism underlying the phenomenon remain undetermined. The aim of this study is to investigate the mechanism of intracellular Ca2+ change in brain microvascular endothelial cells subjected to hyperosmotic stress. Cultured rat brain capillary endothelial cells were obtained by two-step enzymatic purification. Intracellular Ca2+ was measured by a confocal laser scanning microscope. After exposing the endothelial cells to 1.4 M mannitol for 30 seconds, the change of intracellular Ca2+ concentration was monitored. Intracellular Ca2+ concentration increased rapidly and reached its peak value within 10 seconds after the application of mannitol. The Ca2+ concentration returned to the basal level within 200 seconds. A calcium channel blocker nifedipine (100 microM, 10 microM) did not block the increase. A specific blocker (KB-R7943) of Na+/Ca2+ exchange did not affect the rapid elevation of intracellular Ca2+. However, it blocked the return phase almost completely. The results indicated that the Na+/Ca2+ exchanger pumped out the increased intracellular Ca2+ during the return phase. Reversible osmotic disruption and reconstruction of the BBB is not due to simple mechanical shrinkage of the endothelial cells but is due to the intracellular Ca(2+)-activated complex mechanism. The manipulation of the reconstruction phase, which depends on Na+/Ca2+ exchanger, may have clinical implications.

Impaired learning of active avoidance in water-intoxicated rats

Brain edema is an important clinical condition. Pathophysiological findings on behavioral changes may be helpful for a comprehensive understanding of brain edema. However, only few reports on behavioral studies of brain edema have so far appeared. Experiments using psychological techniques on animals are rather time-consuming and may not be suitable for the study of transient conditions, as brain edema caused by trauma, vascular accidents, or others. We have developed a method for avoidance learning of rats using a running wheel apparatus with computer assistance. This model was employed in studies on brain edema from water introxication in rats. As a result, avoidance learning was significantly impaired by water intoxication. Either direct overhydration of the brain or indirect effects, as a decrease in cerebral blood flow, or both, are suggested as mechanisms underlying the impairment of behavior.

The mechanism of free radical generation in brain capillary endothelial cells after anoxia and reoxygenation

We studied the mechanism of reoxygenation injury of cerebral microvessels in cultured rat brain capillary endothelial cells (BCECs). BCECs were isolated from rat cerebral cortices by a two step enzymatic treatment. The monolayers of BCECs were subjected to anoxia for 20 minutes followed by reoxygenation for 3 hours. Cell damage was assessed by measuring the leakage of intracellular lactic dehydrogenase (LDH). The control group was anoxia/reoxygenated BCECs without any protective reagents. To study the protective effect of free radical scavengers and antioxidants, superoxide dismutase, catalase, deferoxamine, oxypurinol, indomethacin, or NG-nitro-L-arginine methyl ester (L-NAME) was applied during anoxia/reoxygenation. Thus 7 experimental conditions were established. Lactic dehydrogenase (LDH) leaked from reoxygenated BCECs due to cell membrane damage. This leakage was almost totally suppressed by superoxide dismutase, indicating that reoxygenation injury of BCECs is mediated by superoxide generation. The other scavengers and antioxidants partially suppressed LDH leakage. Reduction of Ca2+ in the culture medium from 1.6 mM to 0.016 mM also suppressed LDH leakage. These results indicate that BCECs subjected to anoxia/reoxygenation become potent generators of superoxide anion, which is thought to be responsible for reoxygenation injury. The superoxide generation partially depends on the xanthine oxidase and cyclooxygenase pathways. As L-NAME partially suppressed LDH leakage peroxynitrite may contribute to reoxygenation injury of BCECs. The extracellular Ca2+ concentration also plays a critical role in the reoxygenation injury of BCECs.

A new compound heterozygous mutation (W17X, 436 + 5G --> T) in the cytochrome P450c17 gene causes 17 alpha-hydroxylase/17,20-lyase deficiency

A genetic disorder in cytochrome P450c17 results in 17 alpha-hydroxylase/17,20-lyase deficiency. In the present study, a Japanese patient with 17 alpha-hydroxylase/17,20-lyase deficiency underwent molecular analysis. The patient presented with complete female genitalia with a 46,XY karyotype, absent pubertal development, and hypertension. the exons and exon-intron boundaries of P450c17 genetic region were amplified and sequenced. DNA sequencing revealed a compound heterozygous mutation. One allele showed a G to A transition corresponding to a premature termination codon at tryptophane in codon 17 (W17X). The other allele showed a G to T substitution at the fifth nucleotide from the splice donor site in intron 2 (436 + 5G --> T). W17X was found in one allele of the father, and 436 + 5G --> T was found in one allele of the mother. A previous report presented a patient with 17 alpha-hydroxylase/17,20-lyase deficiency who was homozygous for W17X. However, the present case is a novel 436 + 5G --> T mutation. Reverse transcription-PCR analysis using total ribonucleic acid isolated from the testes of the patient revealed that an intron 2 donor site mutation caused abnormal splicing, such that exon 2 was spliced with intron 2. Skipping the exon alters the translational reading frame of exon 3 and introduces a premature termination codon. In semiquantitative analysis, the majority of the transcript for 436 + 5G --> T skips exon 2. The present findings indicate that in this patient, 17 alpha-hydroxylase/17,20-lyase deficiency was caused by the compound heterozygous mutation of exon and splice site mutation in cytochrome P450c17 gene.

Cerebral ischemia affects glucose transporter kinetics across rat brain microvascular endothelium: quantitative analysis by an in situ brain perfusion method

BACKGROUND

It has been reported that cerebral ischemia induces a dissociation between cerebral blood flow and blood-brain barrier glucose transport, but mechanisms of the dissociation are not yet clearly understood. Recent immunohistochemical studies reveal discrepancies of the results between physiologic and immunochemical studies. The purpose of this study was to quantify changes of the blood-brain barrier glucose transporter kinetics following cerebral ischemia by an in situ brain perfusion technique.

METHODS

Fifty-six adult male Sprague-Dawley rats were divided into control and ischemia groups, and four-vessel occlusion was done as an ischemic insult. To obtain regional capillary permeability surface area products of glucose and regional perfusion fluid flow rates, the perfusion fluid (HCO3-buffered saline) was dually labeled with [14C]-2-Deoxyglucose and [3H]-Diazepam, and the brain was perfused at a constant rate via the external carotid artery. After sampling tissues from three regions (frontal, frontoparietal lobe, and caudoputamen), dual scintillation counting was performed. From the results, we determined kinetic parameters, including Vmax, Km, and Kd as described in the Michaelis-Menten equation, by weighted nonlinear least squares method.

RESULTS

In the ischemia group, the affinity (1/Km) and the maximum glucose transport rate (Vmax) decreased significantly.

CONCLUSIONS

The results suggest that severe cerebral ischemia down-regulates the blood-brain barrier glucose transporter kinetics, and the discrepancies between physiologic and immunohistochemical studies may be derived from redistribution of transporters, some deformation of transporters, production of some inhibitors, recruitment of capillaries with different types of transporters, and/or the effect of surrounding glial reaction.

Sensitive high-performance liquid chromatographic method with fluorometric detection for the determination of heparin and heparan sulfate in biological samples: application to human urinary heparan sulfate

A sensitive high-performance liquid chromatographic method for the determination of unsaturated disaccharides produced from heparin and heparan sulfate is described. Heparan sulfate was depolymerized using a combination of heparin lyase I (EC 4.2.2.7), heparin lyase II and heparin lyase III (EC 4.2.2.8). Seven unsaturated disaccharides were separated under isocratic conditions within 25 min using acetonitrile-H2O-0.2 M sodium phosphate buffer (pH 7.0)-3.0 M ammonium chloride (32:10:1:1) and were monitored by fluorescence detection using 2-cyanoacetamide as a post-column derivatizing reagent. As little as 2 pmol of a disaccharide could be detected with excitation at 346 nm and emission at 410 nm. This method was applied to the analysis of normal human urine. It was revealed that the concentration of normal human urinary heparan sulfate is 1.53+/-0.36 mg/mg creatinine (n=4).

Impact velocities of the teeth after a sudden unloading at various initial bite forces, degrees of mouth opening, and distances of travel

A potentially dangerous situation arises when an individual bites on hard and brittle food which suddenly breaks, since the impact velocity of the lower teeth onto the upper teeth after the food is broken can be high and may cause dental damage. The present experiments were designed to study the magnitude of the impact velocity after a sudden unloading at various initial bite forces, degrees of mouth opening, and distances of travel. Subjects were asked to perform a static biting task during which the resistance to the bite was suddenly removed. The upward mandible movement was arrested after a certain distance. The velocity of the lower teeth at impact was calculated just before the mandible came to a standstill in combinations of 4 different bite forces (100, 80, 60, and 40 N), 4 different initial degrees of mouth opening (33.5, 30.5, 27.5, and 24.5 mm), and 3 different distances of travel of the mandible (4.5, 3.0, and 1.5 mm). We found that the bite force rapidly declined after the unloading, resulting in a small impact velocity of the lower front teeth. This impact velocity largely depended on the magnitude of the initial bite force and the distance traveled; it was barely sensitive to variations in degree of initial mouth opening. The maximal velocity of the lower teeth was 0.43 m/s (at an initial bite force of 100 N). This maximum was reached after a distance of travel of about 4 mm in 12 ms. The data suggest that the rapid decline in bite force coupled with a limitation of impact velocity is due to the force-velocity properties of the active jaw muscles and is not caused by neural control.

Detection of skewed X-inactivation in two female carriers of vasopressin type 2 receptor gene mutation

Most cases of congenital nephrogenic diabetes insipidus (NDI) are inherited in an X-linked manner, which is due to the mutations of the vasopressin type 2 receptor (V2R) gene. However, recent reports have presented female NDI patients with heterozygote V2R gene mutations. The mechanism of inheritance was thought to be skewed X-inactivation. We present a family with congenital NDI. Three male members were diagnosed with NDI, and examination of their V2R gene revealed a G inserted at nucleotide 804 of the open reading frame. Three female individuals display different degrees of symptoms of NDI, and all of them possess both the normal and abnormal genes. The X-inactivation patterns of the female members were investigated via the detection of methylated trinucleotide repeat in the human androgen receptor gene. The grandmother showed extremely skewed methylation of one X chromosome, and the mother revealed moderately skewed methylation. The daughter of the grandmother's sister, who has no symptoms of NDI, showed random methylation. The highly skewed X-inactivation pattern of the grandmother suggests that her NDI phenotype is caused by dominant methylation of the normal allele of V2R gene.

A novel point mutation of thyroid hormone receptor beta gene in a family with resistance to thyroid hormone

Resistance to thyroid hormone (RTH) is characterized by variable tissue hyporesponsiveness to thyroid hormone caused by mutations of thyroid hormone receptor beta (TRbeta) gene. We found a novel point mutation of the TRbeta gene in a family (F123) with RTH, a transition of a guanine to adenine at nucleotide 1215, which replaced the normal Met-310 with Ile. This substitution was found in only one allele of affected family members. In vitro transcription and translation of this mutant TRbeta demonstrated a 12-fold reduction of the affinity for triiodothyronine (T3) compared with the wild type TRbeta. Thyroid function tests were similar to a previously reported RTH family (F99) who had a different mutation in the same codon (Thr 310).

Method for detection of epsilon-secondary structure in the precore region of human hepatitis B virus DNA using a fluorescence-based polymerase chain reaction-single-strand-conformation polymorphism technique with capillary electrophoresis

A portion of the precore region of the human hepatitis B virus (HBV) genome is the signal sequence with an epsilon secondary structure, which plays a role in the encapsidation of HBV pregenome RNA. To determine the genetic mutations which occur in the precore region of HBV, we have devised a typing method using a fluorescence-based polymerase-chain-reaction-single-strand conformation polymorphism technique with automated capillary electrophoresis (CE-FSSCP). Using the cloning sequencing method, we analyzed serum samples from 10 patients with hepatitis B, and detected three types of HBV-DNA including two mutants which are crucial to the function of the encapsidation sequence: position 1896 G (guanine) to A (adenine, stop codon), position 1899 G to A, and wild-type. We performed CE-FSSCP analysis of these three types of HBV-DNA and described conditions for determination of the mutations which play roles in the encapsidation of the HBV pregenome. The two types of epsilon mutants and wild-type DNA were identified as separate individual peaks respectively. The observed migration times of the three types of DNAs agreed fairly well with estimates obtained from total RNA secondary structure energy.

Effect of glucocorticoid receptor antagonist RU 38486 on acute glucocorticoid-induced insulin resistance in rat adipocytes

We examined the mechanism of acute glucocorticoid-induced insulin resistance in rat adipocytes using the glucocorticoid receptor antagonist RU 38486. Pretreatment with dexamethasone (DEX) and prednisolone for 60 minutes resulted in 50% inhibition of insulin-induced [3H]2-deoxyglucose (DOG) uptake at 10(-8) and 10(-7) mol/L, respectively, in rat adipocytes and 20% and 25% inhibition of insulin-induced [3H]2-DOG uptake, respectively, in soleus muscles. Our previous experiments indicated that DEX and prednisolone alone stimulate protein kinase C (PKC) in rat adipocytes. Accordingly, we examined [3H]DEX binding to PKC from MonoQ column-purified rat brain cytosol. Specific [3H]DEX binding to MonoQ column-purified PKC was observed (kd, 56.8 nmol/L; Bmax, 725 fmol/mg protein). Thus, insulin-induced PKC translocation from the cytosol to the membrane was suppressed by pretreatment with 10(-7) mol/L DEX and 10(-6) mol/L prednisolone for 80 minutes. During treatment with RU 38486 for 60 minutes, there was no change in the glucocorticoid-induced inhibitory effect on insulin-induced [3H]2-DOG uptake and PKC translocation from the cytosol to the membrane. Moreover, pretreatment with RU 38486 for 120 minutes slightly prevented the DEX-mediated inhibition of insulin-induced glucose uptake. These results suggest that acute glucocorticoid-induced insulin resistance may be mainly mediated through the other non-glucocorticoid receptor pathway.

Acute effects of phorbol ester and insulin on insulin-induced glucose uptake and protein kinase C activation in rat adipocytes

We examined the acute effect of pretreatment with phorbol ester and insulin on insulin-induced glucose uptake and protein kinase C (PKC) translocation from cytosol to the membrane in rat adipocytes. Adipocytes were preincubated with 1 microM tetradecanoylphorbol 13-acetate (TPA) and 10 nM insulin for 60 min and then stimulated with 10 nM insulin for 10 and 30 min to measure PKC activity in cytosol and membrane fractions using a Mono Q column connected onto an HPLC system and [3H]2-deoxyglucose (DOG) uptake, respectively. Pretreatment with 1 microM TPA and 10 nM insulin for 60 min resulted in the marked decreases of insulin-induced [3H]2-DOG uptake. Translocation of Mono Q column-purified cytosolic PKC enzyme activity and PKC beta immunoreactivity from cytosol to the membrane was suppressed by pretreatment with TPA and insulin for 60 min. These results indicate that acute treatment with TPA and insulin which are PKC activators suppress translocation/activation of PKC, and accordingly inhibit insulin-induced glucose uptake. We suggest that a decrease of cytosolic PKC activity may mainly-contribute to the impaired responsiveness of the glucose transport system after acute TPA and insulin treatment.

Two unusual cases of multiple dural arteriovenous fistulas

OBJECTIVE AND IMPORTANCE

Two patients with dural arteriovenous fistulas involving the transverse sinus and superior sagittal sinus are described, with a focus on the unique type of venous drainage of the fistula.

CLINICAL PRESENTATION

Both patients presented with papilledema and progressive visual disturbance. Angiography and magnetic resonance imaging showed that the fistulas involving the superior sagittal sinus had a dilated venous channel, separate from the sinus lumen, located within the wall of the sinus.

INTERVENTION

Transvenous embolization of the venous channel of the fistula, proximal to its drainage into the superior sagittal sinus, resulted in closure of the fistula and restoration of the superior sagittal sinus function. The clinical symptoms were reversed; the symptoms are believed to have reflected venous hypertension in the superior sagittal sinus, resulting from the shunted flow and interfering with normal venous drainage.

CONCLUSION

This unique type of dural arteriovenous fistula may be a variant, occurring in the developmental process of the fistula. It is significant clinically because transvenous embolization can be used to close the fistula and restore sinus function.

Molecular basis of nonclassical steroid 21-hydroxylase deficiency detected by neonatal mass screening in Japan

Since 1989, neonatal mass screening for congenital adrenal hyperplasia (CAH) has been performed in Japan, and the frequency of the classical form of 21-hydroxylase deficiency was found to be nearly identical to that in other countries. However, it has not yet been determined whether our mass screening program can detect the nonclassical (NC) form. From 1991 to 1994, about 4,500,000 infants underwent CAH mass screening in Japan. During this period, we identified by screening 2 siblings and 2 unrelated patients who had mild elevation of serum 17-hydroxyprogesterone levels at 5 days of age, but who revealed no symptoms of CAH. They were diagnosed as having probable NC steroid 21-hydroxylase deficiency. To clarify the molecular basis of NC CAH detectable by neonatal screening in Japan, the steroid 21-hydroxylase (CYP21) genes from these cases were analyzed. The 2 siblings (patients 1 and 2) had I172N and R356W mutations in 1 allele and in the other allele had local gene conversion, including the P30L mutation in exon 1. Patient 3, who was unrelated, had gene conversion encoding the same P30L mutation in 1 allele and in the other allele had an intron 2 mutation (668-12 A-->G), causing aberrant ribonucleic acid splicing, and the R356W mutation. Patient 4, also a compound heterozygote, had the R356W and 707del8 mutations. The estimated rate of detection of the NC form by mass screening (1:1,100,000) seemed low compare to the established detection rate for the classical form (1:18,000). As all of our 4 patients were compound heterozygotes with at least 1 allele bearing 1 or more mutations associated with classic CAH, it may be difficult to detect NC cases carrying only NC-associated alleles using our current neonatal mass screening methods.

Immunohistochemical examination of proliferative potentials and the expression of cell cycle-related proteins of intracranial chordomas

The difference in biological features between recurrent and nonrecurrent intracranial chordomas has not been studied. In this study, proliferative potentials of chordomas were studied with an immunohistochemical staining method, mainly using anti-Ki-67 antibody, MIB-1, which is known to be available for archival paraffin sections, together with immunohistochemical studies on the expression of cell cycle or apoptosis-related proteins, including p53, cyclin D1, and bcl-2 proteins. The correlation among MIB-1 staining indices, the immunoreactivities of these proteins, and clinical courses of intracranial chordomas were analyzed retrospectively, and the statistically significant correlation between MIB-1 staining index (SI) and recurrence has been clarified. The mean MIB-1 SI of recurrent tumors was 10.2%, being shown to be higher than that of nonrecurrent tumors (2.8%). The immunohistochemically positive staining of cell cycle-related protein, especially p53 and cyclin D1 proteins, correlated well with recurrence and high MIB-1 SI. In conclusion, both the examination of proliferative potentials of chordomas using MIB-1 SI and the study of the immunoreactivity of p53 and cyclin D1 proteins are important for their biological and histopathological analyses and the prediction of future recurrence.

Modulation of protein kinases and microtubule-associated proteins and changes in ultrastructure in female rat pituitary cells: effects of estrogen and bromocriptine

This study focused on the intracellular signal transduction system and microtubule-associated proteins (MAPs), such as MAP-2 and Tau protein. The modulation of these proteins and their correlation with ultrastructural changes were investigated in rat pituitary prolactin (PRL) cells. Adult female Wistar rats were treated with estrogen and bromocriptine and their pituitary glands were removed for analysis of the expression of tubulin, MAP-2, Tau protein, protein kinase C (PKC), and calcium calmodulin (CaM) kinase. Western blot analysis showed that estrogen increased and bromocriptine decreased the expression of PKC alpha, beta 1, beta 2, CaM kinase alpha, beta, MAP-2, and Tau protein. MAP-2 and Tau protein, which are cytosolic proteins, being translated on free ribosomes, were associated with the membrane of whirling rough endoplasmic reticulum (RER) in estrogen-treated cells and dissociated with vesiculated RER induced by bromocriptine. These results suggested that the modulation of MAP-2 and Tau protein may reflect changes of PKC and CaM kinase, and that the quantitative changes and intracellular modulation of MAPs induced by estrogen and bromocriptine, i.e., estrogen-induced association and bromocriptine-induced dissociation of MAP-2 and Tau protein with membrane of RER, may reflect the dynamics of microtubules and are associated with structural changes in the RER and changes in the synthesis and intracellular transport of PRL.

Use of a split bone graft to correct the cosmetic deformity associated with the transpetrosal-transtentorial surgical approach: technical report

OBJECTIVE

Split bone graft reconstruction was performed after a standard transpetrosal-transtentorial approach to correct the cosmetic deformity in 18 patients.

TECHNIQUE

The split bone graft was made by dividing the inner table of the temporosuboccipital bone graft and covered the bone effect created by petrosectomy and mastoidectomy. The split bone graft was created and shaped during closure of the dura, so that the operation was not prolonged.

RESULTS

This technique produced excellent cosmetic results immediately after surgery; the results were maintained during the follow-up period of between 20 and 46 months. No complication associated with this technique was recognized.

CONCLUSION

Split bone graft reconstruction is a simple and safe technique for preventing the cosmetic deformity associated with a transpetrosal-transtentorial approach.

Cytologic morphometric approach for the prediction of lymph node involvement in papillary thyroid cancer

OBJECTIVE

Papillary thyroid cancer frequently metastasizes to lymph nodes; however, it is generally difficult to make a precise diagnosis preoperatively. The present study was carried out to evaluate lymph node status preoperatively by using quantitative estimations of various cytologic features obtained by fine needle aspiration biopsy from 110 patients with papillary thyroid cancer.

STUDY DESIGN

Using a microscope connected to a computerized video system, mean nuclear area (NA) mean circumferential length of nuclei (CL), circular rate (CR), largest to smallest diameter ratio of nuclei (LS), coefficient of variation of NA (NACV), and rates of intranuclear cytoplasmic inclusions (CIs) and nuclear grooves (NG) were calculated and analyzed.

RESULTS

LS, NACV and NG were significantly higher in cases with metastasized lymph nodes than node-negative cases (P < .05, P < .0001, P < .05, respectively). Furthermore, all parameters except CR and LS correlated exactly with the histopathologic features (P < .0001). The number of positive lymph nodes correlated well with the value of NACV, and all cases with recurrences proved to have NACV > 22%.

CONCLUSION

Preoperative quantitative estimations of cytologic features are useful parameters for the prediction of lymph node metastases in papillary thyroid cancers.

A case of bilateral reversible thalamic lesions

We describe a case of bilateral reversible thalamic lesions with no neurological deficits and a good prognosis. The lesions appeared as low-density areas on CT and high-intensity areas on T2-weighted MR imaging, and resolved within 1 month, suggesting that the cause was edema.

Significance of tubal resection in surgical treatment of middle ear carcinoma

We successfully carried out total en bloc resection of squamous cell carcinoma of the middle ear in two patients. Both patients have been free of the disease for 32-39 months. In one of the cases, the eustachian tube was resected totally with the temporal bone. Postoperative histopathological examination proved tumor invasion into the cartilaginous part of the tube. We would like to emphasize the significance of total resection of the eustachian tube when neoplastic invasion into the tube is highly suspected. Axial computed tomography is of great value for preoperative evaluation of such invasion. Anterior mobilization of the carotid artery from the carotid canal facilitates resection of the petrous apex and should be done after management of the eustachian tube. The carotid canal is best exposed ventrally, since lateral exposure is at high risk for injuring the bony part of the eustachian tube and may possibly disseminate tumor cells.

Correlation between MIB-1 staining index and the immunoreactivity of p53 protein in recurrent and non-recurrent meningiomas

Wild type p53 protein has been shown by recent investigations to be involved in the negative regulation of cell proliferation, whereas aberrant p53 protein has lost this negative regulation of cell growth. Wild type p53 protein, which has a very short half-life, has generally been considered to be undetectable using immunohistochemical methods; however, according to a recent report, wild type p53 protein may accumulate in the nuclei because of a defective ubiquitin pathway. Aberrant p53 protein has a longer half-life, and thus is visible using immunohistochemical methods. In this study, both the proliferative potential represented by the MIB-1 staining index (SI) and the immunoreactivity of p53 protein in 51 intracranial meningiomas were studied applying immunohistochemical staining methods to archival paraffin sections. The correlation among MIB-1 SI, p53 immunoreactivity, histopathologic findings and the clinical course of the meningiomas was also analyzed retrospectively. Although it is not possible with available reagents to distinguish between aberrant p53 protein and wild type p53 protein, statistical analyses show that p53 protein was immunostained both in meningiomas with high MIB-1 SI and in recurrent meningiomas. This demonstrates the close relationship among p53 immunoreactivity, MIB-1 SI, and recurrence; therefore, the presence of p53 protein by immunohistochemical examination may suggest the proliferative activity of meningioma and is capable of serving as a predictor of future recurrence.