Shear Stiffness of 4 Common Intracranial Tumors Measured Using MR Elastography: Comparison with Intraoperative Consistency Grading.

BACKGROUND AND PURPOSE: The stiffness of intracranial tumors affects the outcome of tumor removal. We evaluated the stiffness of 4 common intracranial tumors by using MR elastography and tested whether MR elastography had the potential to discriminate firm tumors preoperatively. MATERIALS AND METHODS: Thirty-four patients with meningiomas, pituitary adenomas, vestibular schwannomas, and gliomas scheduled for resection were recruited for MR elastography. On the elastogram, the mean and the maximum shear stiffnesses were measured by placing an ROI on the tumor. Blinded to the MR elastography findings, surgeons conducted qualitative intraoperative assessment of tumor consistency by using a 5-point scale. Histopathologic diagnosis was confirmed by using the resected specimens. The mean and maximum shear stiffnesses were compared with histopathologic subtypes, and the intraoperative tumor consistency was graded by the surgeons. RESULTS: The mean and maximum shear stiffnesses were the following: 1.9 ± 0.8 kPa and 3.4 ± 1.5 kPa for meningiomas, 1.2 ± 0.3 kPa and 1.8 ± 0.5 kPa for pituitary adenomas, 2.0 ± 0.4 kPa and 2.7 ± 0.8 kPa for vestibular schwannomas, and 1.5 ± 0.2 kPa and 2.7 ± 0.8 kPa for gliomas. The mean and maximum shear stiffnesses for meningiomas were higher than those of pituitary adenomas (P < .05). The mean and maximum shear stiffnesses were significantly correlated with the surgeon's qualitative assessment of tumor consistency (P < .05). The maximum shear stiffness for 5 firm tumors was higher than that of nonfirm tumors (P < .05). CONCLUSIONS: MR elastography could evaluate intracranial tumors on the basis of their physical property of shear stiffness. MR elastography may be useful in discriminating firm tumors preoperatively.

Neurobehavioral Differences Between Mice Receiving Distinct Neuregulin Variants as Neonates; Impact on Sensitivity to MK-801.

Neuregulin-1 (NRG1) is a well-recognized risk gene for schizophrenia and is often implicated in the neurodevelopmental hypothesis of this illness. Alternative splicing and proteolytic processing of the NRG1 gene produce more than 30 structural variants; however, the neuropathological roles of individual variants remain to be characterized. On the basis of the neurodevelopmental hypothesis of schizophrenia, we administered eNRG1 (0.1~1.0 µg/g), a core epidermal growth factor-like (EGF) domain common for all splicing NRG1 variants, to neonatal mice and compared their behavioral performance with mice challenged with a full mature form of type 1 NRG1 variant. During the neonatal stage, recombinant eNRG1 protein administrated from the periphery passed the blood-brain barrier and activated its receptor (ErbB4) in the brain. In adults, the mice receiving the highest dose exhibited lower locomotor activity and deficits in prepulse inhibition and tonedependent fear learning, although the hearing reduction of the eNRG1-treated mice may explain these behavioral deficits. Neonatal eNRG1 treatment also significantly potentiated MK-801-driven locomotor activity in an eNRG1 dose-dependent manner. In parallel eNRG1 treatment enhanced MK-801-driven c-Fos induction and decreased immunoreactivity for NMDA receptor subunits in adult brain. In contrast, mice that had been treated with the same molar dose of a full mature form of type 1 NRG1 as neonates did not exhibit hypersensitivity to MK-801. However, both animal models exhibited similar hypersensitivity to methamphetamine. Collectively, our findings suggest that aberrant peripheral NRG1 signals during neurodevelopment alter later behavioral traits and auditory functions in the NRG1 subtype-dependent manner.

Arterial spin-labeled perfusion imaging reflects vascular density in nonfunctioning pituitary macroadenomas.

BACKGROUND AND PURPOSE: Angiogenesis is very important in clinical features of pituitary adenomas. We investigated the relationship between the blood flow of nonfunctioning pituitary macroadenomas measured by arterial spin-labeled perfusion imaging and the microvessel attenuation of the tissue. MATERIALS AND METHODS: Conventional MR imaging with contrast-enhanced T1WI and arterial spin-labeled perfusion imaging were performed before surgery in 11 consecutive patients with nonfunctioning pituitary macroadenomas. ROIs were drawn on the tumors, and the degrees of enhancement were calculated by dividing the signal intensity on the contrast-enhanced T1WI by that on the nonenhanced TIWI. As an index of tumor perfusion, a quantitative analysis was performed by using normalized tumor blood flow values calculated by dividing the mean value of the tumor region of interest by the mean region of interest values in the 2 cerebellar hemispheres. The relative microvessel attenuation was determined as the total microvessel wall area divided by the entire tissue area on CD-31-stained specimens. The degree of enhancement and the normalized tumor blood flow values were compared with relative microvessel attenuation. Additionally, intra- and postoperative tumor hemorrhages were visually graded. RESULTS: The degree of enhancement was not correlated with relative microvessel attenuation. Statistically significant correlations were observed between normalized tumor blood flow values and relative microvessel attenuation (P < .05). At surgery, 3 cases were visually determined to be hypervascular tumors, and 1 of these cases had symptomatic postoperative hemorrhage. A statistically significant difference in normalized tumor blood flow values was observed visually between the intraoperative hypovascular and hypervascular groups (P < .05). CONCLUSIONS: Arterial spin-labeled perfusion imaging reflects the vascular density of nonfunctioning pituitary macroadenomas, which may be useful in the preoperative prediction of intra- and postoperative tumor hemorrhage.

ErbB inhibitors ameliorate behavioral impairments of an animal model for schizophrenia: implication of their dopamine-modulatory actions.

Ligands for ErbB receptors, including epidermal growth factor (EGF) and neuregulin-1, have a neurotrophic activity on midbrain dopaminergic neurons and are implicated in the pathophysiology of schizophrenia. Although ErbB kinase inhibitors ameliorate behavioral deficits of the schizophrenia model that was established by hippocampal lesioning of rat pups, the antipsychotic action of ErbB kinase inhibitors and its general applicability to other models are not fully characterized. Using a different animal model, here, we examined whether and how ErbB kinase inhibitors ameliorate the behavioral endophenotypes relevant to schizophrenia. The animal model for schizophrenia was prepared by exposing neonatal rats to the cytokine EGF. Intraventricular infusion of the ErbB1 inhibitors ZD1839 and PD153035 in these animals ameliorated the deficits in startle response and prepulse inhibition in a dose-dependent manner. The deficits of latent inhibition of fear learning were also alleviated by ZD1839 with its limited effects on body weight gain or locomotor activity. ZD1839 infusion also decreased the busting activity of nigral dopamine (DA) neurons and reduced pallidal DA metabolism, a result that mimics the anti-dopaminergic profile of risperidone and haloperidol in this brain region. ErbB inhibitors appear to have anti-dopaminergic actions to alleviate some of the behavioral deficits common to animal models for schizophrenia.

Imaging mass spectrometry revealed the production of lyso-phosphatidylcholine in the injured ischemic rat brain.

To develop an effective neuroprotective strategy against ischemic injury, it is important to identify the key molecules involved in the progression of injury. Direct molecular analysis of tissue using mass spectrometry (MS) is a subject of much interest in the field of metabolomics. Most notably, imaging mass spectrometry (IMS) allows visualization of molecular distributions on the tissue surface. To understand lipid dynamics during ischemic injury, we performed IMS analysis on rat brain tissue sections with focal cerebral ischemia. Sprague-Dawley rats were sacrificed at 24 h after middle cerebral artery occlusion, and brain sections were prepared. IMS analyses were conducted using matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS) in positive ion mode. To determine the molecular structures, the detected ions were subjected to tandem MS. The intensity counts of the ion signals of m/z 798.5 and m/z 760.5 that are revealed to be a phosphatidylcholine, PC (16:0/18:1) are reduced in the area of focal cerebral ischemia as compared to the normal cerebral area. In contrast, the signal of m/z 496.3, identified as a lyso-phosphatidylcholine, LPC (16:0), was clearly increased in the area of focal cerebral ischemia. In IMS analyses, changes of PC (16:0/18:1) and LPC (16:0) are observed beyond the border of the injured area. Together with previous reports--that PCs are hydrolyzed by phospholipase A(2) (PLA(2)) and produce LPCs,--our present results suggest that LPC (16:0) is generated during the injury process after cerebral ischemia, presumably via PLA(2) activation, and that PC (16:0/18:1) is one of its precursor molecules.

In situ hybridization reveals developmental regulation of ErbB1-4 mRNA expression in mouse midbrain: implication of ErbB receptors for dopaminergic neurons.

Although epidermal growth factor (EGF) and neuregulin-1 are neurotrophic factors for mesencephalic dopaminergic neurons and implicated in schizophrenia, the cellular localization and developmental regulation of their receptors (ErbB1-4) remain to be characterized. Here we investigated the distributions of mRNA for ErbB1-4 in the midbrain of the developing mouse with in situ hybridization and immunohistochemistry. The expression of ErbB1 and ErbB2 mRNAs was relatively high at the perinatal stage and frequently colocalized with mRNA for S100beta and Olig2, markers for immature astrocytes or oligodendrocyte precursors. Modest signal for ErbB1 mRNA was also detected in a subset of dopaminergic neurons. ErbB3 mRNA was detectable at postnatal day 10, peaked at postnatal day 18, and colocalized with 2',3'-cyclic nucleotide 3'-phosphodiesterase, a marker for oligodendrocytes. In contrast, ErbB4 mRNA was exclusively localized in neurons throughout development. Almost all of ErbB4 mRNA-expressing cells (94%-96%) were positive for tyrosine hydroxylase in the substantia nigra pars compacta but 66%-78% in the ventral tegmental area and substantia nigra pars lateralis. Conversely, 92%-99% of tyrosine hydroxylase-positive cells expressed ErbB4 mRNA. The robust and restricted expression of ErbB4 mRNA in the midbrain dopaminergic neurons suggests that ErbB4 ligands, neuregulin-1 and other EGF-related molecules, contribute to development or maintenance of this neuronal population.

Epidermal growth factor administered in the periphery influences excitatory synaptic inputs onto midbrain dopaminergic neurons in postnatal mice.

Epidermal growth factor (EGF) has a neurotrophic activity on developing midbrain dopaminergic neurons. We investigated developmental effects of peripheral EGF administration on dopaminergic neurons in midbrain slice preparations containing ventral tegmental area (VTA). Subcutaneous EGF administration to mouse neonates triggered phosphorylation of EGF receptors (ErbB1 and ErbB2) in the midbrain region, suggesting its penetration through the blood-brain barrier. We repeated EGF administration in postnatal mice and examined synaptic transmission in the VTA with electrophysiological recordings. Subchronic EGF treatment increased the amplitude of field excitatory postsynaptic potentials evoked by stimulation of the anterior VTA. To analyze the EGF effect at a single cell level, dopaminergic neurons were identified by their characteristic hyperpolarizing activated currents in whole cell recording. In these dopaminergic neurons, EGF effects the amplitude of spontaneous miniature excitatory postsynaptic currents (mEPSCs) without affecting their frequency. In agreement, EGF also enhanced the AMPA/NMDA ratio of evoked EPSCs in the dopaminergic neurons. In contrast, EGF effects on mEPSCs of neighboring neurons not exhibiting hyperpolarizing activated currents were modest or insignificant. Thus, these results suggest that circulating EGF substantially influences the physiological properties of developing midbrain dopaminergic neurons in perinatal and postnatal mice.

Inhibition of ABL tyrosine kinase potentiates radiation-induced terminal growth arrest in anaplastic thyroid cancer cells.

Gleevec, a selective tyrosine kinase inhibitor, retarded the growth of anaplastic thyroid cancer cell lines in vitro and in vivo through selective inhibition of ABL tyrosine kinase activity. In the present study, we investigated the ability of Gleevec to modulate the in vitro and in vivo radiation response of anaplastic thyroid cancer cells. Cell growth assays, colony formation assays and xenograft models were used to quantify the radiosensitizing effect of Gleevec in cells of the anaplastic thyroid cancer cell lines ARO and FRO. FACS, Western blotting and histochemical techniques were employed to study the mechanisms of radiation response after exposure to Gleevec. Gleevec (7.0 microM) increased the anti-proliferative effect of radiation on the growth ARO and FRO cells in vitro. Clonogenic analysis demonstrated that Gleevec reduced cell survival after irradiation. Gleevec combined with radiation produced an increase in tumor growth inhibition compared to treatment with either modality alone in mice bearing anaplastic thyroid cancer xenografts. The drug suppressed radiation-induced ABL activation and promoted CDKN1A (p21(cip1)) accumulation in irradiated anaplastic thyroid cancer cells. Gleevec had an additional effect on radiation-induced apoptosis in cells of both cell lines and potentiated the induction of terminal growth arrest accompanied by the expression of senescence-associated beta-galactosidase. The antitumor effect of Gleevec is potentiated in adjunctive therapy with radiation not only due to inhibition of proliferative cell growth with transient cell cycle arrest and apoptosis, but also due to the terminal growth arrest associated with senescence, suggesting that tumor cell senescence is a mechanism for tumor targeting therapy in combination with ionizing radiation.

Cyclin D1 overexpression in thyroid papillary microcarcinoma: its association with tumour size and aberrant beta-catenin expression.

AIMS: Cyclin D1 is a target molecule transcriptionally activated by aberrant beta-catenin in Wnt signalling. Thyroid papillary microcarcinoma (PMC) may be considered a precursor of papillary thyroid cancer (PTC). Ki67 is widely used as a proliferation marker. The aim of this study was to determine whether cyclin D1 overexpression is involved in early thyroid carcinogenesis. METHODS AND RESULTS: Thirty-five cases of PMC were examined immunohistochemically, including 11 cases less than 5 mm (PMC < 5) and 24 cases more than 5 mm (PMC > 5), and 18 PTC cases (size 11-15 mm). Cyclin D1 expression was significantly lower in PMC < 5 than in PMC > 5, while there was no significant difference between PMC > 5 and PTC. Statistical analysis revealed significant correlations between cyclin D1 labelling index (LI) and Ki67 LI (P = 0.0272)/cytoplasmic beta-catenin expression (P < 0.001) in PMC and PTC. Four of five PMC > 5 cases with lymph node (LN) metastases displayed a high cyclin D1 LI and strong cytoplasmic beta-catenin expression. CONCLUSIONS: Cyclin D1 overexpression and correlation with aberrant beta-catenin expression were demonstrated in PMC. Cyclin D1 expression was significantly associated with tumour size and LN metastases in PMC. Cyclin D1 may be up-regulated at an early stage of thyroid carcinogenesis and promote tumour growth and metastatic potency in PMC through activation of the Wnt/beta-catenin pathway.

Echocardiographic and Doppler diagnosis: first case of atrial septal aneurysm in a cat.

A 6-year-old female cat developed pleural and abdominal effusion. Cardiac ultrasound and 2D color tissue Doppler imaging revealed restrictive cardiomyopathy with severe biatrial dilatation and hypertension. This cardiomyopathy was associated with atrial septal aneurysm and a patent foramen ovale. The atrial septal aneurysm involved the entire atrial septum. Necropsy and histological examination confirmed all these findings. ASA is a rare malformation and, as in this cat, it generally occurs concomitantly with congenital or acquired heart disease and may be explained by greater pressure in one atrium, leading to controlateral protrusion of the atrial septum.

Synaptic interactions between nonspiking local interneurones in the terminal abdominal ganglion of the crayfish.

Nonspiking local interneurones are the important premotor elements in arthropod motor control systems. We have analyzed the synaptic interactions between nonspiking interneurones in the crayfish terminal (6th) abdominal ganglion using simultaneous intracellular recordings. Only 15% of nonspiking interneurones formed bi-directional excitatory connections. In 77% of connections, however, the nonspiking interneurones showed a one-way inhibitory interaction. In these cases, the presynaptic nonspiking interneurones received excitatory synaptic inputs from the sensory afferents innervating hairs on the surface of the uropods and the postsynaptic nonspiking interneurones received inhibitory synaptic inputs that were partly mediated by the inputs to the presynaptic nonspiking interneurones. The membrane hyperpolarization of the postsynaptic nonspiking interneurones mediated by the presynaptic nonspiking interneurones was reduced in amplitude when the hyperpolarizing current was injected into the postsynaptic interneurones, or when the external bathing solution was replaced with one containing low calcium and high magnesium concentrations. The role of these interactions in the circuits controlling the movements of the terminal appendages is discussed.

Molecular mechanisms of the effects of low concentrations of taxol in anaplastic thyroid cancer cells.

Understanding the detailed mechanisms of a chemotherapeutic agent action on cancer cells is essential for planning the clinical applications because drug effects are often tissue and cell type specific. This study set out to elucidate the molecular pathways of Taxol effects in human anaplastic thyroid cancer cells using as an experimental model four cell lines, ARO, KTC-2, KTC-3 (anaplastic thyroid cancer), and FRO (undifferentiated follicular cancer), and primary thyrocytes. All cell lines were sensitive to Taxol, although to different extent. In primary thyrocytes the drug displayed substantially lower cytotoxicity. In thyroid cancer cells, Taxol-induced changes characteristic to apoptosis such as poly (ADP-ribose) polymerase and procaspase cleavage and alteration of membrane asymmetry only within a narrow concentration range, from 6 to 50 nm. At higher concentration, other form(s) of cell death perhaps associated with mitochondrial collapse was observed. Low doses of Taxol enhanced Bcl2 phosphorylation and led to its degradation observed on the background of a sustained or increasing Bax level and accumulation of survivin and X-chromosome-linked inhibitor of apoptosis. c-jun-NH(2) terminal kinase activation was essential for the apoptosis in anaplastic thyroid cancer cells, whereas Raf/MAPK kinase/ERK and phosphatidylinositol-3-OH kinase/Akt were likely to comprise main survival mechanisms. Our results suggest an importance of cautious interpreting of biological effects of Taxol in laboratory studies and for determining optimal doses of Taxol to achieve the desired therapeutic effect in anaplastic thyroid cancers.

Promising survival for patients with glioblastoma multiforme treated with individualised chemotherapy based on in vitro drug sensitivity testing.

We retrospectively investigated the efficacy and feasibility of individualised chemotherapy based on in vitro drug sensitivity testing (DST) for patients with glioblastoma multiforme. A total of 40 consecutive patients with glioblastoma multiforme (GM) were enrolled into this study between January 1995 and December 2000. The flow cytometric (FCM) detection of apoptosis was used to determine the in vitro sensitivity of tumour cells obtained at surgery to 30 different kinds of anticancer agents. From the results of FCM assay, an in vitro best regimen was prospectively selected. All the patients concurrently received the individualised chemotherapy with the in vitro best regimen and 60 Gy of conventional radiation therapy. Of the 31 assessable patients, eight patients (26%) achieved partial response, and 20 patients (65%) had stable disease. The median survival time was 20.5 months. The individualised chemotherapy based on in vitro DST was associated with favourable survival time for the patients with GM compared with the reported results of conventional therapy regimens. The present result suggests that the currently available anticancer agents could be effective against GM when used in individualised chemotherapy.

Transforming growth factor-alpha changes firing properties of developing neocortical GABAergic neurons by down-regulation of voltage-gated potassium currents.

Transforming growth factor-alpha (TGFalpha), a member of the epidermal growth factor family, has neurotrophic actions on postmitotic neurons. We examined the chronic effects of TGFalpha on the electrophysiological properties of one type of GABAergic neuron, identified by its bipolar morphology, in neocortical primary culture. Approximately 85% of the bipolar neurons were GABA-immunoreactive. In response to depolarizing current injection, the bipolar neurons usually showed tonic firing of action potential under control conditions. After treatment with TGFalpha (20 ng/ml) for 2 days, these neurons failed to generate trains of action potentials. Furthermore, the treatment altered the action potential waveforms of the bipolar neurons, including the duration and amplitude of the fast after-hyperpolarization, which implies a reduction in voltage-gated potassium currents. In contrast, TGFalpha did not affect the firing properties of pyramidal-shaped non-GABAergic neurons. Voltage-clamp recordings from the bipolar neurons indicated that chronic treatment with TGFalpha markedly decreased the current densities of slow delayed rectifier (IK) and transient voltage-gated potassium currents, whereas the treatment had no effect on voltage-gated sodium current and fast delayed rectifier potassium current densities. Reverse transcription-polymerase chain reaction analysis of potassium channel mRNA in the bipolar neurons revealed that the reduction in the IK current density was caused by Kv2.2 mRNA down-regulation. Thus, chronic treatment with TGFalpha down-regulated slow delayed rectifier and transient voltage-gated potassium currents, and in parallel, suppressed repetitive generation of action potentials in the cortical GABAergic neurons.

Brain-derived neurotrophic factor upregulates and maintains AMPA receptor currents in neocortical GABAergic neurons.

The regulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors is implicated in synaptic plasticity. Although we have found that brain-derived neurotrophic factor (BDNF) triggers surface translocation of AMPA receptor proteins, the physiological significance of the BDNF effect remained to be determined. The present immunohistochemical studies revealed that cortical GABAergic neurons exhibited the most striking response to BDNF. Accordingly, we monitored AMPA-triggered currents through GABAergic neurons: Chronic BDNF treatment increased the AMPA-triggered currents but not NMDA-triggered currents in culture. In parallel, the amplitude, but not frequency, of spontaneous miniature excitatory postsynaptic currents (mEPSCs) was elevated in GABAergic neurons. In agreement, BDNF enhanced GABA release triggered by AMPA compared to the amount triggered by high potassium. Conversely, there was a significant decrease in the mEPSC amplitude of GABAergic neurons in heterozygous BDNF-knockout mice. These findings indicate that the neurotrophin enhances the input sensitivity of GABAergic neurons to facilitate their inhibitory function in the neocortex.

The amygdala and Alzheimer's disease: positron emission tomographic study of the cholinergic system.

The primary transmitter deficit is cholinergic in Alzheimer's disease (AD), and the amygdala receives a major cholinergic projection from the nucleus basalis of Meynert (Ch4), which may play an important role in the retention of affective conditioning and/or memory consolidation. We measured brain acetylcholinesterase (AChE) activity in 54 patients with AD and in 22 normal controls by positron emission tomography and N-[(11)C]methylpiperidin-4-yl acetate to characterize the cholinergic pathology in AD. The k(3) values were calculated as an index of AChE activity in a three-compartment model analysis using the metabolite-corrected arterial input function. The k(3) values were highly significantly reduced by 20% in the cerebral neocortex (P <0.0001 in the two-tailed t test), 14% in the hippocampus (P <0.001), and 33% in the amygdala (P <0.0001) in AD patients compared with normal controls. The k(3) values were significantly correlated with the Mini-Mental State Examination scores in both the cerebral cortex (P <0.001) and the amygdala (P <0.05) in AD patients, supporting the cholinergic hypothesis of cognitive dysfuncion in AD. Further studies are required, however, to elucidate the specific role of the cholinergic deficit in the amygdala in the emotional and behavioral symptoms in AD.

Neural activity of the globus pallidus interna and its anatomical relations to the optic tract in Parkinson's disease.

BACKGROUND: To reveal landmarks for placing the globus pallidus interna (GPi) target on MR images, visual evoked potentials (VEPs) of the optic tract (OT) and neural activities of the GPi were studied retrospectively. METHODS: The dorsal and lateral border of the OT were determined by VEPs of the OT, and neural activity in the pallidal region was recorded with a semimicro-electrode in 20 patients. The Unified Parkinson's Disease Rating Scale (UPDRS) was used to assess the condition of each patient before and 6 months and 12 months after surgery. FINDINGS: The location of trajectories relative to the lateral border of the OT were 3 mm medial (-3) in 6, 2 mm medial (-2) in 7, 1 mm medial (-1) in 8, at the lateral border (0) in 6, 1 mm lateral (+1) in 5, 2 mm lateral (+2) in 6, and 3 mm lateral (+3) in 5. The mean amplitudes along trajectories -3 and -2 mm were significantly higher than the others (post-hoc, p<0.01). In dorsoventral relations, the amplitudes from 5.1 mm to 6.8 mm of the medial trajectories (-3 to 0 mm) were significantly higher than others (post-hoc, p<0.01). The lesions placed medial to the lateral border of the OT located just above the lateral border of the OT on postoperative MR images (n=12) and brought better surgical benefits of total motor score, rigidity and bradykinesia than those placed lateral to the OT (n=8). INTERPRETATION: Our data indicate that hyperactive cells of the GPi are located medial to the lateral border of the OT and at least 5.1 mm above its dorsal surface, and this corresponds to the area just above the lateral border of the OT on MR images.