Roles of the functional loss of p53 and other genes in astrocytoma tumorigenesis and progression

Loss of function of the p53 tumor suppressor gene due to mutation occurs early in astrocytoma tumorigenesis in about 30-40% of cases. This is believed to confer a growth advantage to the cells, allowing them to clonally expand due to loss of the p53-controlled G1 checkpoint and apoptosis. Genetic instability due to the impaired ability of p53 to mediate DNA damage repair further facilitates the acquisition of new genetic abnormalities, leading to malignant progression of an astrocytoma into anaplastic astrocytoma. This is reflected by a high rate of p53 mutation (60-70%) in anaplastic astrocytomas. The cell cycle control gets further compromised in astrocytoma by alterations in one of the G1/S transition control genes, either loss of the p16/CDKN2 or RB genes or amplification of the cyclin D gene. The final progression process leading to glioblastoma multiforme seems to need additional genetic abnormalities in the long arm of chromosome 10; one of which is deletion and/or functional loss of the PTEN/MMAC1 gene. Glioblastomas also occur as primary (de novo) lesions in patients of older age, without p53 gene loss but with amplification of the epidermal growth factor receptor (EGFR) genes. In contrast to the secondary glioblastomas that evolve from astrocytoma cells with p53 mutations in younger patients, primary glioblastomas seem to be resistant to radiation therapy and thus show a poorer prognosis. The evaluation and design of therapeutic modalities aimed at preventing malignant progression of astrocytomas and glioblastomas should now be based on stratifying patients with astrocytic tumors according to their genetic diagnosis.

MR imaging of the brain in lymphomatoid granulomatosis

BACKGROUND AND PURPOSE

Clinical diagnosis of lymphomatoid granulomatosis (LG) of the brain, in patients without skin or chest lesions, usually is difficult because of the nonspecific neurologic manifestations, laboratory data, and CT appearance. Our aim was to characterize the MR appearance of LG of the brain.

METHODS

We retrospectively reviewed the MR images in four patients (35 to 72 years old) with histologically confirmed LG of the brain.

RESULTS

On T2-weighted images, we noted diffuse hyperintense lesions in the cerebral white matter bilaterally (n = 3), in the brain stem and cerebellar hemisphere (n = 1), and patchy hyperintense lesions the brain stem (n = 2). On contrast-enhanced T1-weighted images, we observed multiple punctate or linear enhancements residing along the perivascular space (n = 4), nodular enhancements (n = 2), ringlike enhancements (n = 1), and a large, enhanced mass (n = 1). All patients had multifocal lesions.

CONCLUSION

Although the MR appearance of LG of the brain varies, multiple punctate or linear enhancements that reside along the perivascular space suggest LG.

JC virus large T protein transforms rodent cells but is not involved in human medulloblastoma

JC virus (JCV) together with Simian virus 40 (SV40) and BK virus (BKV), belong to the polyomavirus group and these viruses are neuro-oncogenic to rodents by expression of large T antigen (LT), which binds to cellular p53 and pRB thus reducing the anticancer potential of the cell. The function of LT has not been clarified because small t antigen (st) is transcribed from the same start codon as the overlapping reading frame of LT, and is translated as a different protein with the same N-terminal residues (1-81 amino acids) by a splice-site variant of mRNA. To elucidate the function of LT without st, we constructed plasmids that express LT only by deleting the splicing region including the C-terminus of st, and consequently stable cell lines were established that express only JCLT, SV40LT and BKLT. The growth rates of these cells were examined in colonies on soft agar and it was found that LT alone has a transforming capacity; the order of efficiency being SV40LT, BKLT and JCLT. In addition, to verify the involvement of JCV in human medulloblastoma, eight cases of medulloblastoma, six cases of frozen material and five cases of paraffin-embedded tissues which included three cases of frozen tissues, were examined. PCR assay, genomic Southern blotting, and in situ hybridization were applied to detect the JCV genome, and LT and st were examined by immunohistochemistry; the results were compared with JCV-infected tissues as a positive control. All methods failed to detect not only JCV genome but also LT protein in medulloblastoma and it was concluded that JCV LT has transforming activities in rodent cells, but is not related to human medulloblastoma.

A clinical study of urine basic fetoprotein and urine polyamine as tumor markers in epithelial cancer of the urinary tract

BACKGROUND

The reliability of a new screening test for epithelial cancer of the urinary tract was evaluated and the results were compared with those obtained employing urinary cytology in routine use.

METHODS

The subjects consisted of 187 cases selected randomly from among the patients who attended Toho University Ohashi Hospital during a period of 1 year from January 1998. The values for urine basic fetoprotein (BFP) and polyamine and urinary cytology were examined.

RESULTS

Urine BFP is considered useful for screening and monitoring urinary tract epithelial cancer as is urinary cytology. Urine BFP showed a statistically significant difference (P < 0.05) for G1 compared with urinary cytology and a significantly high level compared with urinary cytology as to the positive rate in the low stage group (P < 0.05). The positive rate of urine BFP was high in patients with urinary tract infection.

CONCLUSION

Determining urine BFP, when combined with urinary cytology, is considered very useful for diagnosing patients with urinary tract epithelial cancer. This study suggests the possibility of urine BFP being superior to urinary cytology for screening early cancer and also as an indicator for observations on the clinical course.

[Minimally invasive stereotactic functional surgery using an intravenous anesthetic propofol and applying Image Fusion and AtlasPlan]

Image-guided stereotactic surgery of the ventralis intermedius nucleus of the thalamus, globus pallidus, and subthalamic nucleus is a prevailing modality as a treatment of movement disorders. This technical note describes a method of minimally-invasive stereotactic functional surgery for patients with parkinsonian symptom or various tremors. Patients were administered propofol, an intravenous anesthetic, during placement of a burr hole and a stereotactic frame, but not the period when the patients were necessary to be awake. The intravenous anesthesia was very beneficial to relieve local pain and mental stress of the patients. Radionics ImageFusion and AtlasPlan were used for defining the target localization without an intraoperative ventriculography. ImageFusion efficiently fused high-resolution MR images on CT images. AtlasPlan accurately corrected the localization of the tentative target point after measurements from the midpoint of the anterior commissure-posterior commissure line on the modified MRI, and enabled us to reduce the degree of an intraoperative correction to fix a final target. Stereotactic functional surgery has been thought to be less-invasive, however further modifications of surgical procedure and intraoperative medication can make this type of surgery much more less-invasive.

Alternative EWS-FLI1 fusion gene and MIC2 expression in peripheral and central primitive neuroectodermal tumors

Primitive neuroectodermal tumors (PNET) occur either in the central nervous system (CNS; central PNET, cPNET) or in the peripheral sites (peripheral PNET, pPNET). Recent molecular approaches have been defining a new concept of PNET, that is, the pPNET including Ewing's sarcoma (ES) which expresses MIC2 glycoprotein and shows the specific chimeric gene of EWS-FLI1. The expression of MIC2 and the genetic rearrangement of EWS-FLI1 are considered to be highly specific to the pPNET/ES. This study examined the expression of MIC2 and EWS-FLI1 gene by means of immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) on various small round cell tumors originating in the CNS or non-CNS organs. All peripheral PNET tested expressed MIC2 and were positive for EWS-FLI1 (11/11). In contrast, all cPNET and other blastic CNS tumors were negative for MIC2: medulloblastoma (0/3), cerebral PNET (0/2), spinal PNET (0/2), glioblastoma (0/2), retinoblastoma (0/3), and pineoblastoma (0/2). These MIC2-negative tumors were also negative for the chimeric gene product of EWS-FLI1. Interestingly, one PNET originating in the intracranial dura mater was positive for both MIC2 and EWS-FLI1 fusion gene. The results indicate that cPNET lacks any genetic or protein markers, except for a meningeal PNET which falls into the same phenotypic spectrum of pPNET.

Penile schwannoma

Schwannoma of the penis is extremely rare. A 65-year-old man presented with a subcutaneous tumor of penile shaft without any other symptoms. Histopathologic examination of the excised tumor revealed benign schwannoma. No recurrence has been observed over the 6 months since the surgery.

[Production and clinical application of fibrin sealant with high concentrated fibrin (fibrin patch)]

OBJECT

The sealing properties of fibrin sealant with high concentrated fibrin (fibrin patch) were examined.

MATERIAL AND METHODS

A commercial fibrin sealant (Bolheal) produced from pooled human plasma was utilized for this study. The fibrin sealant made of fibrinogen and thrombin solutions mixed in a volume ratio 5:1 was applied as the fibrin sealant with high concentrated fibrin (fibrin patch). The burst pressure of the fibrin clots of either 1:1 or 5:1 mixing ratio, which sealed the small holes, was measured by a water-leak preventing model. The tensile strength of the fibrin patch was measured by the breaking pressure of the fibrin clot. The burst pressure of the fibrin patch, which sealed the dural defect with a diameter of 15 mm, was compared with that of expanded polytetrafluoroethylene (ePTFE).

RESULTS

The burst pressure was elevated from 287 +/- 23.1 to 445 +/- 30.5 mmHg by changing the mixing ratio from 1:1 to 5:1. The breaking pressure of the fibrin patch showed 131 +/- 25.4 mmHg and that of the patch mixed at the ratio of 1:1 showed 46.6 +/- 9.9 mmHg. The result of dural repair with the fibrin patch revealed higher sealing effectiveness than that of ePTFE. The burst pressure averaged 70.5 +/- 21.4 mmHg in the fibrin patch samples and 51.4 +/- 13 mmHg in the ePTFE samples.

CONCLUSION

The fibrin patch revealed higher performance as a sealant and has the potential to be a candidate for acceptance as the new dural repair material.

Fractionated stereotactic radiotherapy for vestibular schwannoma (VS): comparison between cystic-type and solid-type VS

PURPOSE

To compare the effectiveness and complications of fractionated stereotactic radiotherapy (SRT) for cystic-type vestibular schwannoma (VS) with those of solid-type VS.

METHODS AND MATERIALS

In 65 patients treated with fractionated SRT between 1991 and 1999, 20 were diagnosed with cystic VS, in which at least one-third of the tumor volume was a cystic component on magnetic resonance imaging (MRI), and 45 were diagnosed with solid VS. Thirty-six Gy to 50 Gy in 20-25 fractions was administered to the isocenter and approximately 80% of the periphery of the tumor. All cystic and solid components were included in the gross tumor volume. The mean follow-up period was 37 months, ranging from 6 to 97 months.

RESULTS

The actuarial 3-year rate of no episode of enlargement greater than 2.0 mm was 55% for cystic-type and 75% for solid-type VS; the difference was statistically significant (p = 0.023). The actuarial 3-year tumor-reduction (reduction in tumor size greater than 2.0 mm) rates were 93% and 31%, respectively (p = 0.0006). The overall actuarial tumor control rate (no tumor growth greater than 2. 0 mm after 2 years or no requirement of salvage surgery) was 92% at 5 years in 44 patients with a follow-up period of 2 or more years. There was no difference in the class hearing preservation rate between cystic VS and solid VS. No permanent trigeminal or facial nerve palsy was observed in either group.

CONCLUSION

Transient tumor enlargement occurs in cystic VS more frequently than in solid-type VS, but the subsequent tumor-reduction rate in cystic VS is better.

Minimally invasive surgical exposure of the extreme high cervical internal carotid artery: anatomical study

The purpose of this study is to investigate a minimally invasive access to a high cervical lesion involving the internal carotid artery. Using 13 fixed cadaveric preparations, we sought to design a surgical approach that would cause minimal involvement of the surrounding structures and maximal exposure to the extreme high cervical area. This technique preserves the function and integrity of the mandible, sternocleidomastoid, posterior belly of digastric and styloid process muscles. The method uses retraction and mobilisation of those muscles, as well as decompression of the facial from the stylomastoid foramen. The internal carotid artery is exposed up to the entry point into the carotid canal. The cranial nerves IX, X, XI and XII are kept in sight up to the jugular foramen. This approach creates a wide corridor into the deep high cervical and inferior cranial base area and can be utilised for high cervical carotid lesions and tumours related to the artery.

Asymptomatic schwannoma of the oculomotor nerve: case report

Intracranial oculomotor schwannoma without neurofibromatosis is rare and is usually symptomatic. Only one case of asymptomatic oculomotor schwannoma has been previously reported. We present a case of intracranial oculomotor schwannoma which caused no signs or symptoms. Microsurgical resection of this tumour resulted in oculomotor palsy. We reviewed 7 reported cases and the findings indicated that radical removal of the tumour invariably caused or worsened the oculomotor palsy. The reason why the tumour caused no symptoms in this case was unclear. However, improvements in diagnostic methods such as magnetic resonance imaging (MRI) may increase the detection of such asymptomatic cases. Indications for surgical treatment should be established.

[Two cases of the epidermoid on the petrous bone]

Epidermoids known as cholesteatomas, are congenital benign tumors and originate in the embryonic ectoderm. They account for 1.3% of all intracranial tumors. They are often found in the cerebellopontine angle and the paraseller region, but rarely in the petrous portion of the temporal bone. Epidermoids of the petrous bone tend to slowly present progressive facial palsy and hearing disturbance. In this article, two cases of epidermoids involving the petrous bone are reported. A 55-year-old male presented left facial palsy, left hearing disturbance and decreased gustation in the left side of the tongue. MRI revealed a non-enhanced mass on the petrous portion of the left temporal bone, and bone-window CT showed bone destruction in the same region (Case 1). A 71-year-old female was aware of left facial palsy and left hearing loss for 15 years. MRI showed a non-enhanced mass on the petrous bone, and bone-window CT demonstrated extensive bone erosion of the petrous bone and the middle cranial fossa (Case 2). In both cases, total removal was performed via the middle cranial fossa approach. Both tumors existed extradurally and had pressed against the genicurate ganglion of the facial nerve. The facial palsy of the former case recovered 12 months after surgery. We discuss the problems of diagnosis and treatment of epidermoids of the petrous bone.

Application of advances in molecular biology to the treatment of brain tumors

Recent advances in molecular biology have substantially improved our understanding of the molecular genetics of primary brain neoplasms. Soon each histopathologic category of glioma will be further divided into subgroups according to similar genetic background, gene expression profile, and similarity of biologic responses to radiotherapy or chemotherapy. Identification of key molecules that are specifically altered in neoplastic cells will provide candidate molecular targets for tumor treatment. Novel therapeutic tools for targeting tumor cells, such as viral vectors for gene therapy, have been created. In the near future, the accumulation of new knowledge in brain tumor biology and genetics, combined with rational drug design, will revolutionize the treatment of malignant gliomas, which are among the most lethal human cancers.

Spinal intramedullary ependymomas: surgical results and immunohistochemical analysis of tumour proliferation activity

This study analysed the outcome of 35 consecutive patients with intramedullary ependymoma who underwent a radical surgical resection between 1983 and 1996. The median age of patients was 47 years. Tumour location was cervical in 22 patients, cerviothoracic in eight and thoraco lumber in five. The proliferative activity of 24 spinal and 14 intracranial ependymomas were determined by MIB-1 immunolabelling. Total removal of tumour was achieved in 26 patients and subtotal removal was performed in nine patients of whom six received postsurgical radiation therapy. Twenty-nine patients out of 35 could be followed over 3 years (follow-up periods: 168-36 months: mean 70). Moreover many patients could be followed over 4 years. In 27 of those 29 patients, the neurological symptom was stabilized or improved. The proliferation indices of spinal ependymomas were significantly lower than those of intracranial ependymomas. Tumour regrowth occurred only in a young patient 29 months after a subtotal removal of the tumour which was not treated with irradiation and showed a high proliferation index on the second operation.

Surgical approaches for the treatment of aneurysms on the P2 segment of the posterior cerebral artery

OBJECTIVE

The P2 segment of the posterior cerebral artery has remained a challenging region to expose surgically. We establish a surgical strategy for P2-segment aneurysms.

METHODS

Each segment of the posterior cerebral artery was classified according to Zeal and Rhoton's classification. Fourteen of 18 P2-segment aneurysms were surgically treated. The patient's outcome, the aneurysm location, and the surgical procedures were evaluated. A cadaveric study was performed to clarify the surgical view obtained via three different surgical approaches.

RESULTS

Nine aneurysms were clipped, two were trapped, one was coated, and one was excised with parent artery reconstruction. Cerebral revascularization techniques were used for three patients. The pterional approach exposed the anterior half of the P2a segment. The subtemporal approach revealed the P2a segment, but its exposure was restricted by its localization in the ambient cistern. Via the occipital interhemispheric transtentorial approach, the P2p segment was visible and could be manipulated. When the posterior half of P2a segment was high on a coronal view of magnetic resonance imaging, it was extremely hard to access via any approach.

CONCLUSION

A surgical strategy for the P2 aneurysm can be planned with accurate prediction of the aneurysm location. When the localization of an aneurysm on the posterior half of P2a segment is high, a resection of brain tissue may be required.

Deep brain stimulation of subthalamic area for severe proximal tremor

Proximal tremors are often refractory to nucleus ventrointermedius thalami thalamotomy. Subthalamotomy has been suggested to be effective for treatment of tremor, although this procedure is associated with considerable adverse effects, and has rarely been considered a suitable treatment modality. The authors demonstrate the efficacy and safety of subthalamic deep brain stimulation in two patients, one with a severe, refractory proximal essential tremor and one with tremor with dystonia.

Topography of the vestibulocochlear nerve

OBJECTIVE

The terms superior vestibular nerve and inferior vestibular nerve have been used in the field of neurosurgery to indicate anatomically the two respective vestibular components of the vestibulocochlear nerve. To reappraise the aptness of this terminology, fascicular patterns and the anatomic relationship of the vestibular and cochlear components were examined.

METHODS

Twenty vestibulocochlear nerve specimens were obtained from cadavers. The nerves were excised, with care taken to sustain their spatial relationships, then embedded in paraffin blocks and cross sectioned in 10-microm-thick slices. Serial cross sections were stained and examined with a light microscope.

RESULTS

The vestibular component was separated into two parts only at the lateral fundus of the internal auditory canal, lateral to the vestibular ganglion. In the internal auditory canal of all specimens, the vestibular component was represented by numerous fascicles. Around the porus acusticus, the fascicular pattern among the specimens was diverse: 13 of the 20 specimens were still polyfascicular, 4 specimens consisted of two large, distinct fascicles, and, in the remaining 3 specimens, a portion of the vestibular fascicles had fused with the cochlear component. Near the root entry zone, all vestibular fascicles fused and merged with the cochlear nerve to form a single trunk.

CONCLUSION

There was no evidence to support the anatomic correctness of specifying the superior and inferior vestibular nerves, except in the lateral fundus of the internal auditory canal.