Jo Haraoka

Aβ-degrading endopeptidase, neprilysin, in mouse brain: synaptic and axonal localization inversely correlating with Aβ pathology

Metabolism of amyloid-β peptide (Aβ) is closely associated with the pathology and etiology of Alzheimers disease (AD). Since neprilysin is the only rate-limiting catabolic peptidase proven by reverse genetics to participate in Aβ metabolism in vivo, we performed detailed immunohistochemical analysis of neprilysin in mouse brain using neprilysin-deficient mice as a negative control. The aim was to assess, at both the cellular and subcellular levels, where Aβ undergoes neprilysin-dependent degradation in the brain and how neprilysin localization relates to Aβ pathology in amyloid precursor protein (APP)-transgenic mice. In hippocampus, neprilysin was present in the stratum pyramidale and stratum lacunosum-moleculare of the CA1-3 fields and the molecular layer of the dentate gyrus. Confocal double immunofluorescence analyses revealed the subcellular localization of neprilysin along axons and at synapses. This observation suggests that after synthesis in the soma, neprilysin, a type II membrane-associated protein, is axonally transported to the terminals, where Aβ degradation is likely to take place. Among various cell types, GABAergic and metabotropic glutamate 2/3 receptor-positive neurons but not catecholaminergic or cholinergic neurons, expressed neprilysin in hippocampus and neocortex, implying the presence of a cell type-specific mechanism that regulates neprilysin gene expression. As expected, Aβ deposition correlated inversely with neprilysin expression in TgCRND8 APP-transgenic mice. These observations not only support the notion that neprilysin functions as a major Aβ-degrading enzyme in the brain but also suggest that down-regulation of neprilysin activity, which may be caused by aging, is likely to elevate local concentrations of Aβ at and around neuronal synapses.

Magnetic resonance imaging, clinical manifestations, and management of Rathke's cleft cyst

Objective  The management of Rathkes cleft cyst (RCC), particularly in patients with no symptoms or with only minor endocrinopathies, has not yet been established. We retrospectively analysed patients with RCC to elucidate correlations between the clinical manifestations, magnetic resonance imaging (MRI) findings, histology and therapeutic outcomes.

Preliminary clinical report on safety and efficacy of photodynamic therapy using talaporfin sodium for malignant gliomas.

OBJECTIVES To investigate the safety and efficacy of photodynamic therapy (PDT) using talaporfin sodium in patients with surgically, completely unresectable malignant gliomas with invasion into the eloquent areas of the brain associated with language and motor functions. MATERIALS AND METHODS Subjects consisted of consecutive 14 adult patients with malignant gliomas that were shown on preoperative diagnostic imaging to have invaded the eloquent areas of the brain. Of these, 6 patients had newly diagnosed tumors and 8 patients had recurrent tumors. In 15 craniotomy and tumor resection procedures, PDT was used as additional intraoperative treatment 24 h after 40 mg/m(2) of talaporfin sodium had been injected intravenously. After the tumor bulk had been resected as extensively as possible either 1 or 2 sites of probable tumor invasion in the bottom of resection cavity were irradiated superficially with a 664-nm diode laser for 180 s (27 J/cm(2)) at a power density of 150 mW/cm(2). RESULTS PDT achieved a response rate of 80% at the treated sites in the 6 patients with newly diagnosed malignant gliomas. In these patients, the median progression-free survival time was 23 months. The median survival time in 3 patients who died was 26 months, and the remaining 3 patients survived for more than 3 years with a good Karnofsky Performance Scale (KPS). In the 8 patients with recurrent tumors who received PDT, their response rate was low (25.0%), their gliomas recurred 3 months after PDT, and their survival time was only 9 months following PDT. No adverse events directly attributable to PDT occurred in any patients. Protection against light was only required for approximately 3 days after PDT. CONCLUSION We examined the safety and efficacy of PDT using talaporfin sodium as an additional intraoperative treatment for malignant glioma. PDT in addition to surgical resection achieved better therapeutic results than conventional protocols, especially in patients with newly diagnosed malignant gliomas. However, the current methodology has some limitations with respect to patients with recurrent tumors. Larger-scale studies are required to confirm the clinical feasibility of PDT plus surgery.

Risk factors of cerebrospinal fluid rhinorrhea following transsphenoidal surgery

SummaryObjective. Cerebrospinal fluid (CSF) rhinorrhea is a potentially life-threatening complication following transsphenoidal surgery (TSS). Methods. To elucidate the risk factors that may affect the incidence of postoperative CSF rhinorrhea, we retrospectively reviewed 200 consecutive cases of TSS performed by a single surgeon for 168 adenomas and 32 other sellar and parasellar lesions. Results. Intra-operative CSF leakage was encountered in 38 cases (19.0%). Its incidence did not correlate to tumor size. Among 4 microadenoma cases with CSF leak, 3 were ACTH adenomas. In contrast, postoperative CSF rhinorrhea was observed in 5 cases (2.5%), all following TSS for adenomas. It was frequently noted in cases with prior TSS (3/40, 7.5%, p = 0.0235) and prior radiotherapy (2/7, 28.6%, p<0.0001). Two cases who required surgical intervention had received TSS and radiotherapy previously. Conclusion. The risk of postoperative CSF rhinorrhea is significantly increased in cases with prior TSS or radiotherapy or both. In addition, these cases tended to show delayed CSF leaks and require sellar reconstruction for its treatment. When a CSF leak was encountered during TSS in these high-risk cases, thorough sellar reconstruction and long-term follow-up is necessary.

New technique for application of fibrin sealant: rubbing method devised to prevent cerebrospinal fluid leakage from dura mater sites repaired with expanded polytetrafluoroethylene surgical membranes.

OBJECTIVEThe effectiveness of a strong, pressure-tight method for fibrin sealant application was experimentally and clinically evaluated, using expanded polytetrafluoroethylene (ePTFE) surgical membranes. METHODSTwo application methods were examined in two groups. For Group 1, 1 ml each of Solutions A and B was simply sprayed over the surface (spray method). For Group 2, a small amount of Solution A was rubbed into the sutured site and then Solutions A and B were sprayed over the surface (rubbing method). In the experimental study, a moment pressure elevation test and a continuous stepwise pressure elevation test were performed for both groups. The clinical study was conducted using 350 patients undergoing craniotomies. The ePTFE surgical membrane was used for 180 patients but not the other 170 patients. RESULTSIn the experimental study, the bursting pressures were 51.4 ± 13.0 cm H2O for Group 1 and 129 ± 35.0 cm H2O for Group 2 in the moment pressure elevation test and 27.0 ± 6.7 cm H2O and 100 ± 31.9 cm H2O, respectively, in the continuous stepwise pressure elevation test. The sealing effect was significantly greater for Group 2 than for Group 1 in both tests (P < 0.001). In the clinical study using ePTFE surgical membranes, the rubbing method significantly reduced the incidence of postoperative cerebrospinal fluid leakage (1.4%), compared with the spray method (18.3%), when external decompression was not concomitantly used (P < 0.01). CONCLUSIONThe sealing effect of fibrin sealant on cerebrospinal fluid leakage was significantly greater with the rubbing method than with the spray method. The strong sealing effect obtained with the rubbing method is thought to result from firm linkage between the ePTFE surgical membrane and the fibrin sealant and also from fibrin being formed even in needle holes and spaces in the sutured site.

IN VIVO GLIOMA GROWTH REQUIRES HOST-DERIVED MATRIX METALLOPROTEINASE 2 FOR MAINTENANCE OF ANGIOARCHITECTURE

Glioma, the most common form of brain tumor, has been shown mostly by in vitro studies to utilize matrix metalloproteinase (MMP) for invasive growth through degradation of the extracellular matrix. In order to examine the in vivo role of MMP, we established a rodent model of glioma progression using C6 rat glioma cells and analyzed the effect of tissue inhibitors of metalloproteinases (TIMPs). TIMP-2 rather than TIMP-1 caused significant reduction of the tumor size accompanied by the presence of degenerated blood vessels and ischemic necrosis. Because TIMP-2 inhibits MMP-2 preferentially, we then examined glioma growth in MMP-2-deficient mice and observed essentially identical consequences. While MMP-2 activity was present in the tumor and adjacent tissues of the wild-type mice, no MMP-2 activity was detected even in the tumor of the null mice, although C6 cells are known to express MMP-2. These observations suggest that glioma induces MMP-2 and utilizes its activity in the host tissue to support angiogenesis and to maintain angioarchitecture.

Headaches Associated with Rathke's Cleft Cyst

Objective.—Headaches are common presentations in patients with Rathkes cleft cyst (RCC). This study was conducted to elucidate the characteristics and underlying mechanisms of the headache.

Histological changes in the pituitary gland and adenomas following radiotherapy

To elucidate histological changes in the pituitary gland and adenomas following radiotherapy, two irradiated pituitary glands and seven irradiated non‐functioning adenomas were studied. The latter included four cases with conventional radiation (CR) and three cases with radiosurgery: two with gamma knife radiosurgery (GKR) and one with stereotactic fractionated radiotherapy (SRT). The specimens were obtained 10 months to 10 years (mean 58 months) after the radiotherapy. Irradiated pituitary glands showed diffuse fibrosis in the adenohypophysis, whereas irradiated adenomas showed either mild or no fibrosis in five CR/SRT cases and diffuse thick hyaline deposits in two GKR cases. No necrosis was observed. Stellate‐shaped S‐100 protein‐positive cells were greater in number in the irradiated pituitary glands than in the normal glands. Pituitary cells with dense granular reactivity for mitochondrial protein, cytochrome oxidase, and Mn‐SOD, mimicking oncocytes, were greater in number in the irradiated adenohypophysis but did not show any change in cell size. Many irradiated pituitary cells and some irradiated adenoma cells were densely positive with anticytokeratin 1,5,10,14 antibody whereas non‐irradiated counterparts were negative. In adenomas, MIB‐1 labeling index remained unchanged after the radiation. The results may indicate that radiation‐induced fibrosis was associated with an increased number of folliculo‐stellate cells, mitochondrial dysfunction, and squamous metaplasia. These findings were prominent in irradiated pituitary cells and may participate in delayed pituitary hypofunction following radiotherapy. In irradiated adenoma cells, similar findings were observed but diffuse fibrosis was absent. The histological changes were more intensive in adenomas following GKR than those following CR.

Growth potential of prolactinomas in men: is it really different from women?

BACKGROUND In comparison to prolactinomas in women, those in men are usually large tumors and have been suggested to have a higher proliferation activity. To elucidate the reason for the predominance of large tumors in men, we investigated the gender-related difference of prolactinomas including growth potential. METHODS We conducted a retrospective study comparing unselected 16 men and 27 women with prolactinoma concerning clinical and endocrine findings, tumor volume, and the mean Ki-67 (MIB-1) positive cell index (PCI). RESULTS Prolactinomas in men were larger in size (p = 0.0090), higher in serum prolactin level (p = 0.0359), and exhibited higher PCI (p = 0.0138) than those in women. However, the three factors-tumor volume, prolactin level, and the PCI-showed positive correlations with each other. There was no gender-related difference in the PCI when small tumors (<1.0 cm3) were excluded. CONCLUSION High PCI is associated with large tumors in both men and women. Because large tumors predominate in men, this is in fact consistent with the view that the biologic behavior of prolactinomas is different between the sexes.

Photodynamic therapy of C6-implanted glioma cells in the rat brain employing second-generation photosensitizer talaporfin sodium

OBJECT The usefulness of photodynamic therapy (PDT) as a local therapy for malignant glioma was evaluated by investigating histological changes in a rat C6 glioma model treated with a combination of talaporfin sodium, a water-soluble photosensitizer derived from chlorophyll and exposure to a diode laser. METHODS Glioma cells (C6) at the confluence stage were transplanted stereotactically into the right frontal lobe of SD rats. Five days later, the rats underwent right frontal craniotomy and intravenous administration of talaporfin sodium. One hour after talaporfin sodium administration, each rat was irradiated by a 664 nm diode laser beam. The brain was removed 1, 3 or 6h after laser irradiation for histological examination of tumor-affected brain tissue and surrounding normal brain tissue. RESULTS In addition to the tumor mass, tumor cells invading surrounding edematous brain tissue were seen in untreated rats, ranging from the brain surface to a depth of 2mm. One hour after PDT, coagulation necrosis as well as disappearance of indication of cell viability such as disappearance of tumor cell processes and foamy changes of cytoplasm were noted in the tumor tissue at a depth of 0.5mm, accompanied by reduction of cytoplasmic glial fibrillary acidic protein (GFAP) expression and appearance of granular M30 cytodeath positivity. Three hours later, the cytoplasm of the residual tumor cells showed disappearance of GFAP expression and increased expression of M30 cytodeath. Six hours later, the foamy cytoplasm of swollen tumor cells demonstrated strong positivity for M30 cytodeath. CONCLUSION PDT using talaporfin sodium induced coagulation necrosis and apoptosis in rats with C6 glioma.