Impact of brain tumor location on morbidity and mortality: a retrospective functional MR imaging study

BACKGROUND AND PURPOSE

fMRI is increasingly used in neurosurgery to preoperatively identify areas of eloquent cortex. Our study evaluated the efficacy of clinical fMRI by analyzing the relationship between the distance from the tumor border to the area of functional activation (LAD) and patient pre- and postoperative morbidity and mortality.

MATERIALS AND METHODS

The study included patients with diagnosis of primary or metastatic brain tumor who underwent preoperative fMRI-based motor mapping (n=74) and/or language mapping (n=77). The impact of LAD and other variables collected from patient records was analyzed with respect to functional deficits in terms of morbidity (paresis and aphasia) and mortality.

RESULTS

Significant relationships were found between motor and language LAD and the existence of either pre- or postoperative motor (P < .001) and language deficits (P=.009). Increasing age was associated with motor and language deficits (P=.02 and P=.04 respectively). Right-handedness was related to language deficits (P=.05). Survival analysis revealed that pre- and postoperative deficits, grade, tumor location, and LAD predicted mortality. Motor deficits increased linearly as the distance from the tumor to the primary sensorimotor cortex decreased. Language deficits increased exponentially as the distance from the tumor to the language areas decreased below 1 cm. Postoperative mortality analysis showed an interaction effect between motor or language LAD and mortality predictors (grade and tumor location, respectively).

CONCLUSIONS

These findings indicate that tumors may affect language and motor function differently depending on tumor LAD. Overall, the data support the use of fMRI as a tool to evaluate patient prognosis and are directly applicable to neurosurgical planning.

Axo-axonal interaction in autonomic regulation of the cerebral circulation

Noradrenaline (NE) and acetylcholine (ACh) released from the sympathetic and parasympathetic neurones in cerebral blood vessels were suggested initially to be the respective vasoconstricting and dilating transmitters. Both substances, however, are extremely weak post-synaptic transmitters. Compelling evidence indicates that nitric oxide (NO) which is co-released with ACh from same parasympathetic nerves is the major transmitter for cerebral vasodilation, and its release is inhibited by ACh. NE released from the sympathetic nerve, acting on presynaptic β2-adrenoceptors located on the neighbouring parasympathetic nitrergic nerves, however, facilitates NO release with enhanced vasodilation. This axo-axonal interaction mediating NE transmission is supported by close apposition between sympathetic and parasympathetic nerve terminals, and has been shown in vivo at the base of the brain and the cortical cerebral circulation. This result reveals the physiological need for increased regional cerebral blood flow in 'fight-or-flight response' during acute stress. Furthermore, α7- and α3β2-nicotinic ACh receptors (nAChRs) on sympathetic nerve terminals mediate release of NE, leading to cerebral nitrergic vasodilation. α7-nAChR-mediated but not α3β2-nAChR-mediated cerebral nitrergic vasodilation is blocked by β-amyloid peptides (Aβs). This may provide an explanation for cerebral hypoperfusion seen in patients with Alzheimer's disease. α7- and α3β2-nAChR-mediated nitrergic vasodilation is blocked by cholinesterase inhibitors (ChEIs) which are widely used for treating Alzheimer's disease, leading to possible cerebral hypoperfusion. This may contribute to the limitation of clinical use of ChEIs. ChEI blockade of nAChR-mediated dilation like that by Aβs is prevented by statins pretreatment, suggesting that efficacy of ChEIs may be improved by concurrent use of statins.

Advances in the treatment of pediatric brain tumors

Brain tumors are a heterogeneous group of neoplasms with different origins, pathobiologies, treatments and prognoses. The collective contributions from the fields of neuro-oncology, neurosurgery, radiation oncology, neurology, neuropathology, neuroradiology and molecular biology have all led to significant advances in the treatment of certain brain tumors. Ideas from these fields, under the cooperative umbrella of clinical cancer trial consortia, have been tested in large-scale studies. As a result, patient survivals have increased markedly for these tumor types. Unfortunately, there are certain brain tumors in childhood, such as the diffuse intrinsic pontine glioma and atypical teratoid rhabdoid tumor, for which survival advantages have not been found. This review will discuss the current and possible future therapies of the most common pediatric brain tumors and highlight some of the novel imaging modalities that are used pre- and intraoperatively.

The involvement of glutamate in recall of the conditioned NK cell response

The molecular mechanisms responsible for the conditioned enhancement of natural killer (NK) cell activity were investigated. The primary goal of the study was to examine the roles of glutamate and gamma-aminobutyric acid (GABA) in recall of the conditioned NK cell response. Both neurochemical blocking assay and high performance liquid chromatography (HPLC) technique were used in the study. Results from the neurochemical blocking assay demonstrated that glutamate but not GABA was required in recall of the conditioned NK cell response. NMDA but not the kainate/AMPA receptors, are believed to be involved. The levels of glutamate that were released and/or taken up also appeared to be critical in that interruption of glutamate release and/or uptake blocked the conditioned NK cell response. Results from the HPLC analysis, however, did not show any significant difference in the glutamate content between the conditioned and control brains.

Nitric oxide produces different actions in different areas of the periaqueductal grey in cats

In 20 urethane-anaesthetised cats, microinjection of N-methyl-D-aspartate (NMDA) into the intermediate-lateral (IL-) or the dorsolateral (DL-) periaqueductal grey areas (PAG) of the midbrain elicited similar patterns of cardiovascular responses: increases in mean systemic arterial pressure (MSAP), heart rate (HR) and mean blood flows (F) of the common carotid and femoral arteries, accompanied with a 'hissing-howling' response. Similar increases in MSAP and Fs were induced by microinjections of S-nitroso-N-acetylpenicillamine (SNAP), a potent nitric oxide (NO) donor, on the IL-PAG (A2.5-A0.5). In contrast, microinjections of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, in the same area elicited a decrease in MSAP and Fs. On the other hand, microinjections of either SNAP or L-NAME reversed the original IL-PAG responses when injected into the DL-PAG. Pretreatments with SNAP significantly inhibited NMDA-induced responses in the DL-PAG but potentiated such responses in the IL-PAG. In contrast, pretreatments with L-NAME potentiated the NMDA-induced responses in the DL-PAG but inhibited such responses in the IL-PAG. These data suggest that NO may be a neurotransmitter or neuromodulator that exerts differential function in different defense areas, namely the IL- and the DL-PAG.

Simultaneous monitoring of extracellular glucose, pyruvate, and lactate in rat testies during ischemia: a microdialysis study

A dual-probe microdialysis technique was developed for the simultaneous monitoring of glucose and related metabolite levels during testicular ischemia in rats. The determinations of lactate and pyruvate were achieved by liquid chromatography within 5 min. Glucose was determined by a microdialysis analyzer. A unilateral ligation was produced by occlusion of the right artery for 2 or 4 h in anesthetized rats. Microdialysis probes were inserted in both sides of the testis to simultaneously monitor glucose, lactate and pyruvate during basal, ischemia and reperfusion periods. Dynamic and comparative changes in these analytes in ipsilateral and contralateral testes were demonstrated. The present technique can be used as a tool for exploring energy related metabolites and their relationships in testicular ischemia.

Association of immune responses and ischemic brain infarction in rat

Inflammation plays an important role in the pathogenesis of neurodegenerative diseases including ischemia. Occlusion of common carotid artery and middle cerebral artery has been used to produce focal ischemic lesions in the rat. Here, we examined the associations between immune reactions and postischemic brain infarction. Ischemia/reperfusion time-dependently caused brain infarction. The kinetics of inflammatory reactions in rat brain including inflammatory cell infiltration, edema formation, cytokines/chemokines and adhesion molecules production and matrix metalloproteinase activation were relevant to the progression of ischemic infarction. Differential induction profile after ischemia suggests that this activation might contribute to secondary brain damage in ischemic tissues. On the other hand, another possibility of this response is to trigger processes that mediate the neural regeneration after ischemic injury.

Cerebral ischemia/reperfusion injury in rat brain: effects of naloxone

The pathogenesis of cerebral ischemia/reperfusion (I/R) involves cytokine/chemokine production, inflammatory cell influx, astrogliosis, cytoskeletal protein degradation and breakdown of the blood-brain barrier. (-)-Naloxone is able to reduce infarct volume and has been used as a therapeutic agent for cerebral I/R injuries. However, its effects on the mentioned pathophysiologic changes have scarcely been addressed. Cerebral I/R was produced by occluding and opening bilateral common carotid artery and unilateral middle cerebral artery in Sprague-Dawley rats. After cerebral I/R, the degradation of neuronal microtubule-associated protein-2 (MAP-2) was strongly associated with astrogliosis, inflammatory cell infiltration, cytokine/chemokine overproduction, and matrix metalloproteinase-9 activation. (-)-Naloxone pretreatment suppresses post-ischemic activation and preserves more MAP-2 protein. Therefore, (-)-naloxone administration might be an effective therapeutic intervention for reducing ischemic injuries.

Dehydroepiandrosterone inhibits lipopolysaccharide-induced nitric oxide production in BV-2 microglia

Levels of dehydroepiandrosterone (DHEA) and its sulfated derivative (DHEAS) decline during aging and reach even lower levels in Alzheimer's disease (AD). DHEA is known to exhibit a variety of functional activities in the CNS, including an increase of memory and learning, neurotrophic and neuroprotective effects, and the reduction of risk of age-related neurodegenerative disorders. However, the influence of DHEA on the immune functions of glial cells is poorly understood. In this study, we investigated the effect of DHEA on activated glia. The production of inducible nitric oxide synthase (iNOS) was studied in lipopolysaccharide (LPS)-stimulated BV-2 microglia, as a model of glial activation. The results showed that DHEA but not DHEAS significantly inhibited the production of nitrite in the LPS-stimulated BV-2 cell cultures. Pretreatment of BV-2 cells with DHEA reduced the LPS-induced iNOS mRNA and protein levels in a dose-dependent manner. The LPS-induced iNOS activity in BV-2 cells was decreased by the exposure of 100 microM DHEA. Moreover, DHEA suppressed iNOS gene expression in LPS-stimulated BV-2 cells did not require de novo synthesis of new proteins or destabilize of iNOS mRNA. Since DHEA is biosynthesized by astrocytes and neurons, our findings suggest that it might have an important regulatory function on microglia.

On-line, continuous and automatic monitoring of extracellular malondialdehyde concentration in anesthetized rat brain cortex

An assay for in vivo, continuous and automatic monitoring of extracellular malondialdehyde concentrations in anesthetized rat brain cortex was developed. This method involved the use of microdialysis perfusion, on-line derivatization and on-line high-performance liquid chromatographic analysis. Microdialysate from an implanted microdialysis probe was on-line reacted with thiobarbituric acid at 80 degrees C for 10 min prior to on-line collection and automatic injection into a HPLC system equipped with a fluorescence detector. This method gave a linear response between the concentrations of the malondialdehyde in the microdialysates and the TEP solution where the microdialysis probe was placed. This method was used to observe the increased extracellular malondialdehyde production following elevated extracellular glutamate levels, which were achieved by perfusion of L-trans-pyrrolidine-2,4-dicarboxylate, a competitive inhibitor of glutamate uptake transporter.

Expression of neural cell adhesion molecule in spinal cords following a complete transection

Neural cell adhesion molecule (NCAM) regulates tissue organization during development and in the adult. NCAM upregulation occurs after an injury to brains and sciatic nerves. However, little is known about NCAM expression after spinal cord injury (SCI). By using a complete spinal cord transection with a 5 mm tissue removal, an increase in the NCAM level is detected in spinal cord stumps proximal and distal to the transection site at 1 d and 3 d post injury, while its expression at 8 d is declined to a lower level than that observed in sham-operated spinal cords. The strong NCAM expression is present in motor neurons at 3 d post transection whereas the intensive NCAM immunostaining is localized in dorsal sensory and corticospinal fiber tracts at 8 d following injury. Collectively, NCAM level is elevated and strongly expressed in dorsal fiber tracts after SCI, implying that the endogenous process for spinal cord regeneration may take place after SCI.

Resveratrol inhibits interleukin-6 production in cortical mixed glial cells under hypoxia/hypoglycemia followed by reoxygenation

Reactive oxygen intermediates (ROIs) are important mediators of a variety of pathological processes, including inflammation and ischemia/reperfusion injury. Cytokines and chemokines are detected at mRNA level in human and animal ischemic brains. This suggests that hypoxia/reoxygenation may induce cytokine production through generation of ROIs. In this study, we investigated the cytokine induction and inhibition by antioxidants in rat cortical mixed glial cells exposed to in vitro ischemia-like insults (hypoxia plus glucose deprivation). The results showed that interleukin-6 (IL-6) mRNA and protein, but not tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), were induced during hypoxia/hypoglycemia followed by reoxygenation in the mixed glial cells. The accumulation of IL-6 mRNA was induced as early as 15 min after hypoxia/hypoglycemia and its level was further increased after subsequent reoxygenation. Among the antioxidants studied, only resveratrol suppressed IL-6 gene expression and protein secretion in mixed glial cultures under hypoxia/hypoglycemia followed by reoxygenation. These findings suggest that resveratrol might be useful in treating ischemic-induced inflammatory processes in stroke.

Dorsomedial medulla is more susceptible than rostral ventrolateral medulla to hypoxic insult in cats

We investigated the responses of systemic arterial pressure and vertebral sympathetic nerve activity to glutamate microinjections (0. 1 M, 70 nl) in the dorsomedial (DM) and the rostral ventrolateral medulla (RVLM) before hypoxia and after reoxygenation (posthypoxia) after various degrees of hypoxia in anesthetized cats. Hypoxia was produced by ventilating 5% O(2) and 95% N(2) for different durations (hypoxia I-III). In intact cats, the glutamate-induced systemic arterial pressure and vertebral nerve activity responses of the DM were depressed after all degrees of hypoxia. Posthypoxic depression in the RVLM, however, was not observed until hypoxia II and III. Precollicular decerebration prevented depression in the RVLM, but, for the DM, it was effective only for hypoxia I. Baro- and chemoreceptor denervation abolished all posthypoxic depression in both the DM and the RVLM. Pressor responses to tyramine (100-400 microg/kg iv) remained unchanged after all degrees of hypoxia. These results suggest that the DM is more susceptible to hypoxia than the RVLM. The peripheral baro- and chemoreceptors and the suprapontine structures apparently play an important role in posthypoxic depression. Moreover, the depression is not due to the postganglionic norepinephrine depletion.

Production of macrophage inflammatory protein-2 following hypoxia/reoxygenation in glial cells

Polymorphonuclear neutrophils (PMNs) are known to mediate brain inflammation following hypoxia/reoxygenation (H/R), but the precise mechanisms leading to PMN recruitment are undefined. The alpha-chemokine macrophage inflammatory protein-2 (MIP-2) has specificity for the recruitment of PMNs. In this study, we found that 8 or 12 h of hypoxia followed by 24-h reoxygenation (H8/R24 or H12/R24) induced MIP-2 secretion in cultures of enriched microglia or mixed glia, respectively. Microglia, however, could not survive longer duration (>12 h) of hypoxia. Astrocytes did not produce any significant amount of MIP-2 even though astrocytes maintained 98-99% viability following H12/R24. We also found that microglia survived the H/R treatment better (following H24) in the presence of astrocytes (mixed glial culture) than in microglia-enriched culture. Reoxygenation for prolonged periods (3 and 5 days) following H24 resulted in progressively larger increases in MIP-2 production (20- and 60-fold, respectively) in mixed glial cultures. Immunocytochemical staining revealed that the cells expressing MIP-2 in response to H/R were microglia rather than astrocytes in mixed glial cultures. Examination of MIP-2 mRNA expression showed that H/R upregulated MIP-2 gene expression. Taken together, our data suggest that microglial cells are an important source of MIP-2 production and suggest a potential injury mechanism involving brain-derived production of MIP-2 in H/R.

Tumor necrosis factor-alpha modulates the proliferation of neural progenitors in the subventricular/ventricular zone of adult rat brain

Little is known about the response of neural progenitors to inflammation following injuries of the central nervous system. In combination with bromodeoxyuridine (BrdU) intraperitoneally (i.p.) injected, tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine that increased ED1+ activated microglia/macrophage population at injured sites, was administrated into adult rat brains. No difference in the immunostaining for proliferating cell nuclear antigen (PCNA) was observed in the subventricular/ventricular zone (SVZ/VZ) between TNF-alpha injected sites and controls. However, BrdU+ cells were apparently observed in the SVZ/VZ proximal to TNF-alpha injected site, and the number of BrdU+ cells increased at 6 and 24 h post injection. Since cell apoptosis was rarely found in the SVZ/VZ after TNF-alpha injection, these observations suggest that the diffusible TNF-alpha may directly and/or indirectly modulate the proliferation of neural progenitors.

Gliotoxic action of glutamate on cultured astrocytes

Because of the well-documented importance of glutamate clearance by astrocytes in protecting neurons against excitotoxicity, it was interesting to examine whether L-glutamate exerts a toxic action on cultured astrocytes. Cell damage was evaluated by measuring activity of lactate dehydrogenase (LDH) released into the culture medium. Exposure of astrocyte cultures of the neonatal rat cerebral cortex to L-glutamate resulted in a concentration- and time-dependent increase in the release of LDH. L-Glutamate-induced gliotoxicity appeared to be mediated predominantly by the increase of oxidative stress because the reduced glutathione content and its effects were almost completely blocked by vitamin E and pyrrolidinedithiocarbamate. To support this notion further, the supplementation or depletion of intracellular reduced glutathione content attenuated or worsened L-glutamate toxicity, respectively. Activation of the glutamate transporter mimicked the action of L-glutamate on astrocytes. In addition, degrees of cell damage were not directly correlated to the levels of glutamate uptake. Moreover, the mechanism of this toxicity required energy and macromolecular synthesis. Taken together, brief exposure to L-glutamate resulted in glutamate uptake and cell swelling, whereas sustained exposure injured astrocytes via oxidative stress instead of the excitatory mechanism.

Induction of cytokine genes and IL-1alpha by chemical hypoxia in PC12 cells

The role of cytokine in neuronal injury was examined in rat pheochromocytoma (PC12) cells under chemical hypoxia (i.e. KCN) and glucose deprivation. The mRNA levels of interleukin-1alpha (IL-1alpha), IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured by reverse transcription-polymerase chain reaction (RT-PCR) in PC12 cells exposed to 0.5 mM KCN for various time intervals. Cytokine mRNA levels expressed to peak levels 30 minutes after KCN treatment and declined gradually until 240 min. The IL-1alpha activity reached the highest levels 2 hr after the same KCN treatment. Under parallel conditions, KCN increased cytosolic free calcium concentration ([Ca2+]i) in the absence of glucose. However, IL-1alpha mRNA induction by KCN was not altered under calcium-free conditions in PC12 cells, indicating its induction was Ca2+-independent. However, the phosphatidylcholine (PC)-specific phospholipase C (PLC) inhibitor D609 decreased the KCN-induced IL-1alpha mRNA and protein in PC12 cells suggests that PC-PLC might play a role in cytokine induction during hypoxia.

Differential alteration of catecholamine release during chemical hypoxia is correlated with cell toxicity and is blocked by protein kinase C inhibitors in PC12 cells

Release of neurotransmitters, including dopamine and glutamate, has been implicated in hypoxia/ischemia-induced alterations in neuronal function and in subsequent tissue damage. Although extensive studies have been done on the mechanism underlying the changes in glutamate release, few have examined the mechanism that is responsible for the changes in catecholamines. Rat pheochromocytoma-12 (PC12) cells synthesize, store, and release catecholamines including DA and NE. Therefore, we used HPLC and ED to evaluate extracellular DA and NE concentrations in a medium during chemical hypoxia in PC12 cells. Chemical hypoxia produced by KCN induced differential release of DA and NE. Under normal glucose conditions, KCN induced release of NE, but not DA. Under glucose-free conditions, KCN-induced release of DA was elevated transiently, whereas the release of NE increased progressively. Under parallel conditions, KCN biphasically elevated the level of cytosolic free calcium ([CA(2+)](i)) in glucose-free DMEM, peaking at 95 +/- 18 nM at 1,107 +/- 151 s, followed by a new plateau level at 249 +/- 24 nM sustained from 4,243 +/- 466 to 5,263 +/- 440 s. Cell toxicity, as measured by LDH release, was increased significantly by KCN in glucose-free DMEM but was diminished in the presence of glucose, and was correlated with DA release by chemical hypoxia. The protein kinase C (PKC) inhibitor GO6976 or staurosporine inhibited KCN-induced LDH release as well as the release of NE and DA. Taken together, selective activation of DA but not NE was correlated with the LDH release by chemical hypoxia, and was diminished with GO6976 or staurosporine. These results suggest that selective activation of PKC isoforms is involved in the chemical hypoxia-induced DA release, which may lead to neuronal cell toxicity.

Diethylmaleate decreased ascorbic acid release induced by cerebral ischemia in cerebral cortex of the anesthetized rat

The effect of diethylmaleate administration on ascorbic acid release following cerebral ischemia was investigated in anesthetized rat brain cortex. Cerebral ischemia, induced by ligating bilateral common carotid arteries and unilateral middle cerebral artery, significantly increased the extracellular ascorbic acid levels. Diethylmaleate (4 mmoles/kg, i.p.), which has been shown in earlier studies to decrease the ischemia-induced glutamate release, significantly reduced the ischemia-induced ascorbic acid release. The ischemia-induced ascorbic acid release was unaffected by perfusing NMDA receptor antagonist MK 801 (75 microM). Additionally, elevated extracellular glutamate levels, achieved by either externally applied glutamate solutions or by perfusing L-trans-pyrrolidine-2,4-dicarboxylate (PDC) (31.4 mM and 15.7 mM) to inhibit the glutamate uptake transporter, also significantly increased the extracellular ascorbic acid levels. These results suggested that ascorbic acid release in cerebral ischemia might be related to the elevated extracellular glutamate levels, which occurs following cerebral ischemia.

Anti-inflammatory and neuroprotective effects of magnolol in chemical hypoxia in rat cultured cortical cells in hypoglycemic media

Our previous studies demonstrated that magnolol protects neurons against chemical hypoxia by KCN in cortical neuron-astrocyte mixed cultures (14). In the present study, we examined whether the neuroprotective effect of magnolol involve modulating inflammatory mediators, prostaglandin E2 (PGE2) and nitric oxide (NO), induced by KCN (hypoxia) or KCN plus lipopolysaccharide (LPS). In glucose-absent (hypoglycemia) media, KCN or KCN plus LPS induced increases in lactate dehydrogenase (LDH) activity by 32% and 34%, and PGE2 production by 12% and 32%, respectively. Both LDH and PGE2 increases were suppressed by 100 microM magnolol. In addition, although KCN or LPS alone did not increase NO generation, KCN plus LPS increased NO generation. This increase was reduced by 100 microM magnolol or 10 microM L-NAME, but the LDH increase and PGE2 production were not reduced by L-NAME. These findings suggest that the protective effects of magnolol against brain damage by KCN or KCN plus LPS in hypoglycemic media may involve inhibition of PGE2 production, but inhibition of NO generation may not be important.

Effects of naloxone on lactate, pyruvate metabolism and antioxidant enzyme activity in rat cerebral ischemia/reperfusion

Whether naloxone may modulate energy metabolism and endogenous antioxidant enzyme activities in ischemic cortex was studied. Cerebral ischemia/reperfusion (I/R) was produced by occluding two common carotid arteries and the right middle cerebral artery for 90 min followed by reperfusion in anesthetized Sprague-Dawley rats. Both pre-treatment (0.03 or 0.3 mg) and post-treatment (0.3 mg) of naloxone by intracerebroventricular infusion significantly reduced cortical infarct volumes. Pre-treatment with 0.03 mg reduced ischemia-induced suppression of extracellular pyruvate level and enhancement of lactate/pyruvate ratio as well as cerebral I/R-induced increases of endogenous catalase, glutathione peroxidase, and manganese superoxide dismutase activities. In conclusion, neuroprotective effects of naloxone in terms of reducing brain infarction involve attenuation of the disturbance of cellular functions following cerebral I/R via restoration of mitochondrial activities or energy metabolism.

ATP-stimulated c-fos and zif268 mRNA expression is inhibited by chemical hypoxia in a rat brain-derived type 2 astrocyte cell line, RBA-2

The stimulus-transcriptional coupling during ischemia/hypoxia was examined for ATP-stimulated expression of immediate early genes (IEGs; c-fos, zif268, c-myc and nur77) in a rat brain-derived type 2 astrocyte cell line, RBA-2. Incubation of cells with 1 mM of extracellular ATP stimulated time-dependent expression of c-fos and zif268. ATP induced the largest increases in zif268 mRNA and a lesser one in c-fos mRNA. ATP also induced a slight increase in nur77 mRNA but was ineffective in inducing c-myc expression in these cells. Brief exposure of cells to potassium cyanide to simulate chemical hypoxia induced 9-fold and 7-fold transient increases in c-fos and zif268 expression, respectively, but did not affect c-myc or nur77 expression. When cyanide and ATP were added together, the expression of c-fos and zif268 expression was inhibited, and the effect was mimicked by simulating chemical hypoxia with sodium azide. To elucidate the mechanism involved, the effect of cyanide on ATP-stimulated increases in intracellular Ca(2+) concentrations, [Ca(2+)](i), and phospholipase D (PLD) activities were measured. Cyanide induced an increase in [Ca(2&plus);](i) and further enhanced the ATP-stimulated increases in [Ca(2+)](i) and PLD activities. Nevertheless, metabolic inhibitor, iodoacetate, blocked the ATP-induced c-fos and partially inhibited zif268 expression, and deprivation of cells with glucose also inhibited the ATP-induced c-fos expression. Taken together, these results demonstrate that both extracellular ATP and chemical hypoxia induce c-fos and zif268 expression in RBA-2 type 2 astrocytes. The chemical hypoxia inhibited ATP-stimulated c-fos and zif268 expression is not due to alterations in Ca(2+) and PLD signaling, and is at least partially related to metabolic disturbance in these cells.

Determination of catecholamines in pheochromocytoma cell (PC-12) culture medium by microdialysis-microbore liquid chromatography

An in vitro microdialysis system was constructed for the measurement of catecholamines in pheochromocytoma cell culture medium. The novel microdialysis device is composed of a petri dish, a dialysis membrane and two transmission tubes. The dialysis membrane is located in the space of a petri dish such that it is immersed in the culture medium. Catecholamines contained in the culture medium diffused into a designed dialysis membrane with sufficient recovery (about 60%). Dialysates were collected by a sampling loop and introduced by an on-line injector to a microbore liquid chromatographic system for analysis of catecholamines. This assay yielded a detection limit of 0.2-0.5 pg/injection with acceptable intra- and inter-assay reproducibilities in 5 microl of dialysates. To evaluate the on-line microdialysis system, PC-12 cells were cultured in a petri dish within an incubator. The baseline concentration of dopamine in PC-12 cell culture medium was about 0.29 ng/ml which was elevated to 2.43 ng/ml after treatment with 0.5 mM potassium cyanide. In conclusion, the present microassay provides for the sensitive, direct measurement of catecholamines in culture medium while minimizing pretreatment procedures for sample preparation.

Changes in the level of glial fibrillary acidic protein (GFAP) after mild and severe focal cerebral ischemia

In the present study, we examined the temporal and spatial expression profiles of GFAP mRNA and protein in a focal cerebral ischemia model with ischemic injury confined to the cerebral cortex in the right middle cerebral artery (MCA) territory. Northern blot analysis showed a respective 5.5-fold and 7.2-fold increase in the GFAP mRNA in the ischemic right MCA cortex in rats subjected to 30-min (mild) or 60-min (severe) ischemia followed by 72-hr reperfusion. The GFAP mRNA signal remained elevated up to 2-week reperfusion. Interestingly, increased GFAP mRNA signal was clearly demonstrated for the first time in the left MCA cortex. A significant 1.5-fold and 5-fold increase was observed after 72-hr reperfusion following mild and severe ischemia, respectively. However, unlike the ischemic right MCA cortex, this induction was transient in the non-ischemic left MCA counterpart. In situ hybridization studies further revealed characteristic spatial induction profile following mild vs. severe ischemia. In mild ischemia, following 24-hr reperfusion, increase in GFAP mRNA was observed mainly within the ischemic right MCA cortex. Following 72-hr reperfusion, GFAP mRNA signal was observed in virtually the entire ischemic cortex, particularly the amygdala region, then gradually reduced and restricted to right MCA territory and subcortical thalamic nucleus following 2-week reperfusion. On the other hand, in severe ischemia, following 24-hr reperfusion increased GFAP mRNA signal was observed in area surrounding right MCA territory (infarct region) and outer cortical layers within the right MCA territory. Following 72-hr reperfusion, no signal was detected within right MCA cortex; however, increased GFAP signal was detected throughout the remaining ipsilateral cortex and subcortical region, as well as the contralateral cerebral cortex. GFAP mRNA signals then gradually reduced its intensity and was restricted to area surrounding necrosis and ipsilateral thalamic nucleus following 2-week reperfusion. GFAP-like immunoreactivity was also detected in area expressing GFAP mRNA. It is very likely that de novo synthesis was responsible for this increase. In summary, increased GFAP signal was noted in both ipsilateral and contralateral cerebral following mild and severe ischemia. Although the temporal induction profile for mild vs. severe ischemia was similar, the spatial induction profile was different. The mechanism leading to this differential induction and their physiological and functional significance are not clear at present. It is very likely that some local factors may involve, nevertheless, the detailed mechanisms remain to be fully explored.

Superoxide dismutase gene expression and activity in the brain of spontaneously hypertensive rats and normotensive rats

OBJECTIVE

To determine if changes in superoxide dismutase (SOD) in the brain occur in the hypertensive state.

METHODS

We compared the levels of the two main subtypes of this enzyme in spontaneously hypertensive rats (SHR) with age-matched normotensive Wistar Kyoto (WKY) rats using enzyme activity estimation, Western blotting for enzyme contents, and Northern blotting of mRNA level. Five discrete brain regions, cerebrocortex, hypothalamus, hippocampus, the remaining non-cortex cerebrum (NCC area), and cerebellum, were employed for comparison in 30-31 weeks old rats.

RESULTS

A lower level of both Mn-SOD activity and Mn-SOD mRNA expression was found in all areas of the brain of SHR as compared with WKY rats. Also, the mRNA levels of Cu, Zn-SOD in the brain of SHR differed from WKY rats in parallel to the enzyme activities. The activity and mRNA expression of Cu, Zn-SOD were lower in the hypothalamus and cerebellum of SHR but the mRNA level and the activity in hippocampus were significantly higher in the SHR compared to WKY rats. No differences for Cu, Zn-SOD were observed in cerebrocortex or NCC area in the two species. However, the amount of SOD enzyme subtypes, determined by Western blotting analysis, was not different between SHR and WKY rats.

CONCLUSIONS

The results indicate a lower gene expression and less activity of Mn-SOD in SHR brain. This alternation of SOD may be one of the important factors for the vulnerability of the brain from oxygen free radicals or may be related to the pathogenesis of hypertension in this species.

Pallister-Hall syndrome: clinical and MR features

A 4-month-old boy with polydactyly and bifid epiglottis was found to have a large sellar and suprasellar mass. When the diagnosis of Pallister-Hall syndrome was made, conservative management was elected. When the patient was 2 years old, the tumor had grown proportionally with the patient, and he was developing appropriately. Although rare, this entity is important to recognize not only for clinical diagnosis but also for appropriate management and genetic counseling.

On-line derivatization for continuous and automatic monitoring of brain extracellular glutamate levels in anesthetized rats: a microdialysis study

Glutamate is an important excitatory amino acid in central nervous system. We developed a method for in vivo, continuous and automatic monitoring of brain extracellular glutamate, as well as other amino acids in anesthetized rat. This method involves the use of microdialysis perfusion technique and a high-performance liquid chromatography system equipped with a fluorescence detector. The microdialysate (perfused at a flow-rate of 1 microl/min) was on-line derivatized with o-phthaldehyde (perfused at 2 microl/min) through a mixing tee prior to the injection onto the HPLC column. The efficiency of this on-line derivatization was equivalent to that performed with an off-line manner. The effect of cerebral ischemia (2 h) and reperfusion (2 h) in brain cortex of anesthetized rats was monitored using this method. In addition to glutamate, extracellular concentrations of other amino acids, such as aspartate, glutamine, glycine, taurine and gamma-aminobutyric acid, were also simultaneously monitored with this on-line method. Since monitoring of extracellular amino acids by microdialysis perfusion is intensively used in neuroscience investigations, this simple and convenient method would be useful in the future applications.

Alpha-tocopherol acetate significantly suppressed the increase in heart interstitial 8-hydroxydeoxyguanosine following myocardial ischemia and reperfusion in anesthetized rats

The effect of alpha-tocopherol acetate, an aqueous form of alpha-tocopherol, on the increase in heart interstitial 8-hydroxydeoxyguanosine (8-OH-dG) levels following myocardial ischemia/reperfusion was investigated. A microdialysis probe was implanted in the left ventricular interstitial space of anesthetized rat hearts. Myocardial ischemia was induced by ligating the left anterior descending coronary artery. Levels of 8-OH-dG in microdialysates were analyzed via an on-line high-performance liquid chromatography system equipped with an electrochemical detector. The 8-OH-dG levels significantly increased (maximum 3.6-fold of increase relative to basal value) during the 60-min reperfusion stage following a 20 min ischemia. Administration of alpha-tocopherol acetate (20 mg/kg, intravenous, bolus) at 3 min prior to onset of reperfusion, significantly suppressed the reperfusion-induced increase in 8-OH-dG levels. These results suggested that one of the possible protective effect of alpha-tocopherol acetate was to reduce oxidative DNA damage during in myocardial ischemia and reperfusion.

ATP-stimulated Ca2+ influx and phospholipase D activities of a rat brain-derived type-2 astrocyte cell line, RBA-2, are mediated through P2X7 receptors

This study characterizes and examines the P2 receptor-mediated signal transduction pathway of a rat brain-derived type 2 astrocyte cell line, RBA-2. ATP induced Ca2+ influx and activated phospholipase D (PLD). The ATP-stimulated Ca2+ influx was inhibited by pretreating cells with P2 receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), in a concentration-dependent manner. The agonist 2'- and 3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) stimulated the largest increases in intracellular Ca2+ concentrations ([Ca2+]i); ATP, 2-methylthioadenosine triphosphate tetrasodium, and ATPgammaS were much less effective, whereas UTP, ADP, alpha,beta-methylene-ATP, and beta,gamma-methylene-ATP were ineffective. Furthermore, removal of extracellular Mg2+ enhanced the ATP- and BzATP-stimulated increases in [Ca2+]i. BzATP stimulated PLD in a concentration- and time-dependent manner that could be abolished by removal of extracellular Ca2+ and was inhibited by suramin, PPADS, and oxidized ATP. In addition, PLD activities were activated by the Ca2+ mobilization agent, ionomycin, in an extracellular Ca2+ concentration-dependent manner. Both staurosporine and prolonged phorbol ester treatment inhibited BzATP-stimulated PLD activity. Taken together, these data indicate that activation of the P2X7 receptors induces Ca2+ influx and stimulates a Ca2+-dependent PLD in RBA-2 astrocytes. Furthermore, protein kinase C regulates this PLD.

Brainstem projections to the ventromedial medulla in cat: retrograde transport horseradish peroxidase and immunohistochemical studies

Stimulation of the nucleus magnocellularis (NMC) of the medulla produces changes in locomotion, muscle tone, heart rate, and blood pressure. Glutamatergic input has been found to modulate muscle tone, whereas cholinergic input has been found to mediate cardiovascular changes produced by stimulation of the NMC. The current study was designed to identify the brainstem afferents to NMC by using retrograde transport of wheat germ agglutinin and horseradish peroxidase (WGA-HRP) combined with glutamate and choline acetyltransferase (ChAT) immunohistochemical and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemical techniques. Fifty nanoliters of 2.5% WGA-HRP were microinjected into the NMC in the cat. A heavy density of WGA-HRP-labeled neurons was found in the ipsilateral mesencephalic reticular formation (MRF), periaqueductal gray, Kolliker-Fuse nucleus, and pontis centralis caudalis (PoC), in the contralateral pontis centralis oralis (PoO), and bilaterally in the nucleus paragigantocellularis lateralis. A moderate density of retrogradely labeled neurons was found in the ipsilateral side of the nuclei parvocellularis, retrorubral (RRN), PoO, and vestibular complex, in the contralateral PoC and nucleus gigantocellularis, and bilaterally in the inferior vestibular nucleus. Retrograde HRP/glutamate-positive cells could be found throughout the brainstem, with a high percentage in RRN, PoO, PoC, and MRF. Double-labeled WGA-HRP/ChAT neurons were found in the pedunculopontine nucleus. Double-labeled WGA-HRP/NADPH-d-positive neurons could be seen in many nuclei of the brainstem, although the number of labeled neurons was small. The dense glutamatergic projections to the NMC support the hypothesis that rostral brainstem glutamatergic mechanisms regulate muscle activity and locomotor coordination via the NMC, whereas the pontine cholinergic projections to the NMC participate in cardiovascular regulation.

Intrastriatal injection of 5,7-dihydroxytryptamine decreased 5-HT levels in the striatum and suppressed locomotor activity in C57BL/6 mice

Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 5,7-dihydroxytryptamine (5,7-DHT) on striatal levels of dopamine (DA), 5-hydroxytryptamine (5-HT), and their metabolites, as well as on locomotor activity were investigated in C57BL/6 mice. The results showed that MPTP significantly increased locomotor activity and decreased striatal DA levels. However, injection of the serotonergic neurotoxin 5,7-DHT in the striatum, either alone or following high doses of MPTP, significantly decreased locomotor activity, and concomitantly decreased striatal levels of 5-HT and 5-HIAA. This study suggests that the increased locomotor activity may be due to increased striatal serotonergic activity which overcompensates for the DA deficiency. The locomotor hypoactivity, induced by 5,7-DHT, might be due to the decreased striatal levels of 5-HT and 5-HIAA.

Dorsal facial area of cat medulla; 5-HT2 action on glutamate release in regulating common carotid blood flow

Serotonin (5-HT) may inhibit glutamate release in the dorsal facial area (DFA) of the medulla and decrease common carotid arterial (CCA) blood flow. We attempted to clarify which subtype(s) of 5-HT receptor was involved. A microdialysis probe was inserted in DFA. The concentration of glutamate in dialysates were determined by chromatography. Glutamate concentration was dose-dependently decreased by perfusion of 5-HT or DOI, a 5-HT2 agonist, but not by 5-CT, a 5-HT1 agonist. The 5-HT-induced decrease in glutamate was reversed by co-perfusion of ketanserin, a 5-HT2 antagonist, but not by propranolol, a 5-HT1 antagonist. CCA blood flow was decreased when 5-HT or DOI was perfused, and was reversed by co-perfusing ketanserin. In conclusion, 5-HT may inhibit glutamate release via 5-HT2 receptor in DFA, resulting in the reduction of CCA blood flow.

Neurotoxic N-methyl-D-aspartate lesion of the ventral midbrain and mesopontine junction alters sleep-wake organization

The dorsal regions of the midbrain and pons have been found to participate in sleep regulation. However, the physiological role of the ventral brainstem in sleep regulation remains unclear. We used N-methyl-D-aspartate-induced lesions of the ventral midbrain and pons to address this question. Unlike dorsal mesencephalic reticular formation lesions, which produce somnolence and electroencephalogram synchronization, we found that ventral midbrain lesions produce insomnia and hyperactivity. Marked increases in waking and decreases in slow wave sleep stage 1 (S1), stage 2 (S2) and rapid eye movement sleep were found immediately after the lesion. Sleep gradually increased, but never returned to baseline levels (baseline/month 1 post-lesion: waking, 30.6 +/- 4.58%/62.3 +/- 10.1%; S1, 5.1 +/- 0.74/3.9 +/- 1.91%; S2, 46.2 +/- 4.74%/23.1 +/- 5.47%; rapid eye movement sleep, 14.1 +/- 3.15%/7.2 +/- 5.42%). These changes are comparable in magnitude to those seen after basal forebrain lesions. Neuronal degeneration was found in the ventral rostral pons and midbrain, including the substantia nigra, ventral tegmental area, retrorubral nucleus, and ventral mesencephalic and rostroventral pontine reticular formation. We conclude that nuclei within the ventral mesencephalon and rostroventral pons play an important role in sleep regulation.

Pharmacokinetic and pharmacodynamic analyses of trazodone in rat striatum by in vivo microdialysis

The aim of this study was to investigate the brain pharmacokinetics and pharmacodynamics of trazodone. Sensitive microbore high-performance liquid chromatographic methods with electrochemical detection (LC-ED) were developed for the determination of trazodone, serotonin (5-HT), and their respective metabolites. The feasibility of microdialysis coupled with LC-ED system for direct analysis of these compounds in the rat striatum was investigated. Striatal dialysates were automatically injected onto a cyano microbore column, through an on-line injector, for the determination of trazodone and its metabolite or onto a reversed phase microbore column for the determination of 5-HT and its metabolite. A monophase phenomenon with a first-order elimination rate constant was observed for trazodone. The brain pharmacokinetics of trazodone appear to conform to a one-compartment model. Surprisingly, no significant changes in striatal 5-HT or its metabolite were observed following the same dosage and time course. The present results suggest that brain microdialysis methods may be applicable to pharmacokinetic and pharmacodynamic studies of psychotrophic agents.

Involvement of catecholamines in recall of the conditioned NK cell response

The primary goal of the study was to identify the types of catecholamines and the associated receptors which might be involved in the recall of the conditioned NK cell response. Specific catecholamine receptor antagonists were selected to block the conditioned NK cell response at the recall step. The regional contents of dopamine (DA), norepinephrine (NE), and epinephrine were determined in the brain of the conditioned animals by using the high performance liquid chromatography with electrochemical detection (HPLC/ED). Results showed that pre-disruption of the central alpha1-, alpha2-, beta1-, beta2-, D1-, or D2-receptors at the conditioned recall stage, interrupted the conditioned enhancement in NK cell activity. The NE contents at the cerebellum, and DA contents at the striatum and hippocampus, were significantly higher in the brain of the conditioned animals when compared to that of the control animals. These information indicated the possible roles of the central noradrenergic and dopaminergic systems in regulating the recall of the conditioned NK cell response.

Magnolol protects cortical neuronal cells from chemical hypoxia in rats

The protective effect of magnolol, a component of Magnolia officinalis, against hypoxia-induced cell injury in cortical neuron-astrocyte mixed cultures was examined. Exposure of the cells to chemical hypoxia (0.5 mM KCN) produced morphological changes in neurons but not in astrocytes. KCN induced dose- and time-dependent increases in release of LDH and decreases in viable cell number. Treatment with magnolol (10 and 100 microM) significantly reduced the KCN-induced LDH release in a concentration-dependent manner. A higher concentration (750 microM) magnolol was toxic. Nuclear condensation was not observed in KCN-treated cells, suggesting that chemical hypoxia-induced cell death was via necrosis, rather than via apoptosis. This is the first report demonstrating that magnolol protects neurons against chemical hypoxic damage or necrotic cell death in cortical neuron-astrocyte mixed cultures.

The effect of trigeminal neurotomy on the alteration of local cerebral blood flow of normotensive and hypertensive rats in acute cold stress

The cold season is reported to have the highest incidence of stroke in a year. Cold is usually detected by cold receptors in the face. The present studies were designed to test whether the trigeminal nerve plays a role in the regulation of local cerebral blood flow (LCBF) in animals exposed to a cold environment. Since hypertension affects the incidence of strokes, both Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were used. Each species was divided into four groups: trigeminal neurotomy (TNx) or control group at room temperature (20 degrees C) or cold environment (5 degrees C), respectively. LCBF in 14 brain structures was measured using the [14C] iodoantipyrine technique and tissue dissecting methods. Our results show that TNx did not alter physiological parameters and LCBFs in WKY and SHR kept either at 20 degrees C or at 5 degrees C for 30 min. However, a transient exposure (30 minutes) to cold caused concomitantly a significant decrease in core body temperature of both WKY and SHR groups (p<0.05, Student's paired t-test) and a significant decrease in LCBFs at the temporal cortex (TC), hypothalamus (HYP) and midbrain (MID) of WKY and TC of SHR (P<0.05, MANOVA). TNx did not alter LCBFs significantly following transient cold exposure in WKY and SHR. Our findings indicate that in the cold environment, the lowered LCBFs in some areas of the brain may relate to the decreased metabolic rate caused by decreased body temperature, and may partly contribute to the higher prevalence of stroke in winter. Our findings also suggest that trigeminal nerve do not exert tonic control of LCBFs and the cold afferents in trigeminal nerve are not important in modulation of the LCBFs.

Glial cell line-derived neurotrophic factor protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in C57BL/6 mice

To mimic chronic exposure to neurotoxins in inducing dopaminergic cell damage, multiple doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were injected in C57BL/6 mice. Effects of pre- and post-treatment with the glial cell line-derived neurotrophic factor (GDNF) by injections into the striatum were investigated. GDNF exerts protective and reverse effects on the dopaminergic damage, supporting the potential application of GDNF in prevention and treatment of Parkinson's disease.

Opl: a zinc finger protein that regulates neural determination and patterning in Xenopus

In order to study the mechanism of neural patterning in Xenopus, we used subtractive cloning to isolate genes activated early during this process. One gene isolated was opl, (odd-paired-like) that resembles the Drosophila pair-rule gene odd-paired and encodes a zinc finger protein that is a member of the Zic gene family. At the onset of gastrulation, opl is expressed throughout the presumptive neural plate, indicating that neural determination has begun at this stage while, by neurula, opl expression is restricted to the dorsal neural tube and neural crest. opl encodes a transcriptional activator, with a carboxy terminal regulatory domain, which when removed increases opl activity. opl both sensitizes animal cap ectoderm to the neural inducer noggin and alters the spectrum of genes induced by noggin, allowing activation of the midbrain marker engrailed. Consistent with the later dorsal neural expression of opl, the activated form of opl is able to induce neural crest and dorsal neural tube markers both in animal caps and whole embryos. In ventral ectoderm, opl induces formation of loose cell aggregates that may indicate neural crest precursor cells. Aggregates do not express an epidermal marker, indicating that opl suppresses ventral fates. Together, these data suggest that opl may mediate neural competence and may be involved in activation of midbrain, dorsal neural and neural crest fates.

The effect of sphenopalatine postganglionic neurotomy on the alteration of local cerebral blood flow of normotensive and hypertensive rats in acute cold stress

The cold season of a year has been reported to have the highest incidence of strokes. Present studies were designed to test whether the parasympathetic denervation plays any role in the regulation of local cerebral blood flow (LCBF) in anesthetized animals exposed to a cold environment. Each species of Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) was divided into four groups: sphenopalatine postganglionic neurotomy (SPNx) or a control group at room temperature (20 degrees C) or in a cold environment (5 degrees C), respectively. LCBF in 14 brain structures was measured using the [14C] iodoantipyrine technique and tissue dissecting methods. Our results show that SPNx did not significantly alter physiological parameters and LCBF in WKY and SHR kept at either 20 degrees C or 5 degrees C. However, 30 minutes of cold exposure caused a significant decrease in the core body temperature of both the WKY and SHR groups (P < 0.05, Student's paired t-test) and a significant decrease in LCBF in 3 of 14 brain areas: the temporal cortex (TC), inferior colliculus (IC) and vermis (VER) of both WKY and SHR (P < 0.05, MANOVA). The percentages of decrease were 24% (TC), 12% (IC), 12% (VER) and 19% (TC), 16% (IC), 15% (VER), respectively. Our findings indicate that in a cold environment, the lower LCBFs in some areas of the brain may be related to decreased body temperature. Whether they are related to the higher prevalence of stroke in winter needs further investigation.

Ferrous ion diminished the antiarrhythmic effect of naloxone in myocardial ischemia of isolated rat hearts

This investigation was to examine the effect of ferrous ion (a prooxidant) on the antiarrhythmic effect of naloxone (an endogenous opioid receptor antagonist) in isolated rat hearts. Isolated Sprague-Dawley rat hearts were perfused in the Langendorff mode and myocardial ischemia was performed by ligating the left descending coronary artery. Cardiac rhythm was recorded. Heart alpha-tocopherol concentrations were analyzed. Naloxone (1.2 micromol/heart) was effective in reducing the severity of arrhythmia (arrhythmia score; mean+/-S.E.M: 2.82+/-0.69 for naloxone vs. 5.18+/-0.38 for control, p<0.01). Fe2+ (100 nmol/heart) alone did not significantly affect the arrhythmia score (5.63+/-0.32) when compared with the control, however, Fe2+ administration did cause significant early onset of ventricular premature contraction and ventricular tachycardia. Additionally, Fe2+ administration diminished the naloxone's antiarrhythmic effect (arrhythmia score 4.12+/-0.40). Alpha-tocopherol, a major free radical scavenger that exerts protective functions on heart tissues during myocardial ischemia/reperfusion, was significantly higher in the naloxone-treated group (59.05+/-3.00 nmol/g wet wt) than in the control group (43.84+/-4.17 nmol/g wet wt, p<0.05). These results suggest that endogenous opioid peptides and reactive oxygen species might be related to ischemia-induced arrhythmia.

Axillary artery aneurysm in tuberous sclerosis: cross-sectional imaging findings

A 10-month-old boy with a known diagnosis of tuberous sclerosis presented with axillary and brachial masses. Cross-sectional imaging with computed tomography, magnetic resonance, and ultrasound demonstrated unsuspected aneurysms of the axillary and brachial arteries. The results of these studies significantly changed the preoperative planning for this patient, who was scheduled for a biopsy of a presumed soft-tissue tumor. To our knowledge, this is the first description of the cross-sectional imaging findings in the extremity peripheral vascular manifestation of tuberous sclerosis; it has only been previously described on angiography in one case. The rare association of peripheral arterial aneurysms with tuberous sclerosis is important to recognize not only for clinical diagnosis but also for appropriate surgical treatment and genetic counseling.

Elevated 5-S-cysteinyldopamine/homovanillic acid ratio and reduced homovanillic acid in cerebrospinal fluid: possible markers for and potential insights into the pathoetiology of Parkinson's disease

High-performance liquid chromatography with electrochemical detection has been employed to analyze ultrafiltrates of cerebrospinal fluid of Parkinson's Disease (PD) patients and age-matched controls for the dopamine (DA) metabolites homovanillic acid (HVA) and 5-S-cysteinyldopamine (5-S-CyS-DA). The mean level of HVA in the CSF of PD patients, measured 5 days after withdrawal from L-DOPA therapy, was significantly lower than that measured in controls. By contrast, mean levels of 5-S-CyS-DA were not significantly different in the CSF of PD patients taking L-DOPA (PD-LT patients) the same patients 5 days after discontinuing this drug (PD-LW patients) or controls. However, the mean 5-S-CyS-DA/HVA concentration ratio was significantly (p < 0.05) higher in the CSF of PD-LW patients compared to controls. Although the PD patient population employed in this study had been diagnosed with the disease several years previously and had been treated with L-DOPA for prolonged periods of time the results of this study suggest that low CSF levels of HVA and a high 5-S-CyS-DA/HVA ratio together might represent useful markers for early diagnosis of PD. The high 5-S-CyS-DA/HVA ratio observed in the CSF of PD-LW patients also provides support for the hypothesis that the translocation of glutathione or L-cysteine into neuromelanin-pigmented dopaminergic cell bodies in the substantia nigra might represent an early event in the pathogenesis of PD.

Differential regulation of ciliary neurotrophic factor (CNTF) and CNTF receptor alpha (CNTFR alpha) expression following focal cerebral ischemia

Ciliary neurotrophic factor (CNTF) is a member of cytokines, with trophic effects on ciliary, motor sympathetic, sensory, retinal and hippocampal neurons. In the present study, we examined the temporal and spatial expression profiles of CNTF and CNTF receptor alpha (CNTFR alpha) mRNAs in a focal cerebral ischemia model induced by transient occlusion of the right middle cerebral artery and both common carotid arteries. Northern blot analysis showed a slow and sustained increase in the 1.2 kb transcript of CNTF mRNA in the ischemic cortex of rats subjected to a transient 60 min ischemic insult. A delayed decrease in the 2.1 kb transcript of CNTFR alpha mRNA in the ischemic cortex was observed in rats subjected to 60 min ischemia followed by 72 h of reperfusion. In situ hybridization studies revealed constitutive expression of CNTFR alpha mRNA in the majority of neurons in the brain. Following 4 h of reperfusion, increased expression of CNTFR alpha mRNA was observed in the ipsilateral dentate gyrus, which is opposite to the down-regulation noted in the ischemic cortex. Within the infarct area CNTFR alpha mRNA had a marked increase in cortical layer II but a decrease in cortical layer V following 1 day of reperfusion. No signal of CNTFR alpha mRNA was detected within the infarct region following 3 days of reperfusion. Following 1 week of reperfusion, although no marked changes was observed in the level of CNTFR alpha mRNA in the area immediately surrounding the necrosis region where the reactive astrocytes were noted, a striking increase in the CNTF mRNA signal was noted. In summary, differential regulation of CNTF and CNTFR alpha mRNAs was noted in the ischemic cortex. Regional differences in CNTF receptor expression were noted between the ischemic cortex and ipsilateral dentate gyrus as well as between cortical layer II and V within the infarct region. CNTF mRNA, but not CNTFR alpha mRNA, had a marked increase in the area immediately adjacent to the necrosis. The mechanisms and patho-physiological significance for these differential regulation remain to be studied.