Clinical Neuroscience

[CHARACTERIZATION OF SPECIFIC SUCCINATE BINDING SITE IN BRAIN SYNAPTIC MEMBRANES]

MOLNÁR Tünde1, FEKETE Kútiné Erzsébet1, KARDOS Julianna1, PALKOVITS Miklós2

MARCH 20, 2007

Clinical Neuroscience - 2007;60(03-04)

[A synaptic receptor for gamma-hydroxybutyric acid (GHB) - a naturally occuring metabolite of succinic acid1 - interacting succinate has been disclosed in rat and human nucleus accumbens (NA) subcellular fractions2, but the molecular properties of this recognition site were not characterised. To address the presumed recognition site for succinate, the pharmacological profile of [3H]succinate binding to synaptic membranes prepared from rat forebrain and human NA samples has been investigated. Specific [3H]succinate binding sites in the human NA synaptic membrane fraction showed a strong pH-dependence and were characterized by binding of succinate (IC50,SUCC=2.9±0.6 µM), GHB (IC50,GHB=2.1±1.3 µM) and gap junction blocker carbenoxolone (IC50,CBX=7.1±5.8 µM). A similar [3H]succinate binding profile was found in rat forebrain synaptic membrane fractions. We conclude the existence of a pHo-dependent synaptic membrane binding site for the intermediary metabolite succinate. The pharmacological properties of this recognition site may possibly suggest the existence of a hemichannel-like target protein for succinate.]

AFFILIATIONS

  1. Department of Neurochemistry, Institute of Biomolecular Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Budapest
  2. Neuromorphological and Neuroendocrine Research Laboratory, Hungarian Academy of Sciences and Semmelweis University, Budapest

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[BRAIN INSULIN SIGNALLING IN THE REGULATION OF ENERGY BALANCE AND PERIPHERAL METABOLISM]

MICHAELA Diamant

[The unparalleled global rates of obesity and type 2 diabetes, together with the associated cardiovascular morbidity and mortality, are referred to as the "diabesity pandemic". Changes in lifestyle occurring worldwide, including the increased consumption of high-caloric foods and reduced exercise, are regarded as the main causal factors. Central obesity and insulin resistance have emerged as important linking components. Understanding the aetiology of the cluster of pathologies that leads to the increased risk is instrumental in the development of preventive and therapeutic strategies. Historically, skeletal muscle, adipose tissue and liver were regarded as key insulin target organs involved in insulinmediated regulation of peripheral carbohydrate, lipid and protein metabolism. The consequences of impaired insulin action in these organs were deemed to explain the functional and structural abnormalities associated with insulin resistance. The discovery of insulin receptors in the central nervous system, the detection of insulin in the cerebrospinal fluid after peripheral insulin administration and the well-documented effects of intracerebroventricularly injected insulin on energy homeostasis, have identified the brain as an important target for insulin action. In addition to its critical role as a peripheral signal integrating the complex network of hypothalamic neuropeptides and neurotransmitters that influence parameters of energy balance, central nervous insulin signalling is also implicated in the regulation of peripheral glucose metabolism. This review summarizes the evidence of insulin action in the brain as part of the multifaceted circuit involved in the central regulation of energy and glucose homeostasis, and discuss the role of impaired central nervous insulin signalling as a pathogenic factor in the obesity and type 2 diabetes epidemic.]

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[OPTIMAL ALIGNMENT®. NOVEL SOFTWARE PROCEDURE FOR 3D RECONSTRUCTION OF ELECTRONMICROSCOPIC SERIAL SECTIONS]

SIMON László, GARAB Sándor, NOSZEK Annamária, ELIZABETH Römmer, ZÁBORSZKY László

[3D reconstruction from electronmicroscopic (EM) serial sections substantially differs from modeling body parts by linking convoluted planes delivered by CT and NMR. Namely, variations both in relative X-Y position and rotation of the target elements between the adjacent images and also additional problems caused by deformed, deteriorated or missing sections can only be overruled by an aligning paradigm, which exploits all the pixel-level information, and results in an optimal fitting with selected precision. This paper presents a complex computer program called Optimal Alignment®, which performs the precise elaboration of X-Y shift and relative rotation of two consecutive images. The required searching process will be customized by setting four independent parameters which relate the span and density of the pixel-scanning basic process. Optimalization of fitting accuracy versus running time can be achieved by a rather short training period. The potential precision of Optimal Alignment based on complex algorythms is far superior to manual aligning of EM photographs with the eye-wrist-mouse facility. The resulted database of alignment orientation parameters can serve as an advanced source for the 3D reconstructing programs. Optimal Alignment® software tool (supported by Hungarian Space Office grant TP 138) will be demonstrated on a basal forebrain NPY+ axonal reconstruction, performed in L. Záborszky’s laboratory (supported by NIH grant NSO23945).]

Clinical Neuroscience

[In memoriam Mariann Fodor]

Clinical Neuroscience

[PROTECTIVE ACTION OF SNAKE VENOM NAJA NAJA OXIANA AT SPINAL CORD HEMISECTION]

ABRAHAMYAN S. Silva, MELIKSETYAN B. Irina, CHAVUSHYAN A. Vergine, ALOYAN L. Mery, SARKISSIAN S. John

[Based on data accumulated regarding the neuroprotective action of Proline-Rich-Peptide-1 (PRP-1, a fragment of neurophysin vasopressin associated hypothalamic glycoprotein consisting of 15 amino acid residues) on neurons survival and axons regeneration and taking into the account that LVV-Hemorphin-7 (LVV-H7, an opioid peptide, widely distributed in different cell types of various tissues of intact rats, including those of the nervous and immune systems) derived from the proteolitic processing of hemoglobin in response to adverse environmental and physiological conditions, possesses the anti-stressor properties, we used histochemistry, immunohistochemistry and electrophysiology to investigate the putative neuroprotective action of Central Asian Cobra Naja naja oxiana snake venom (NOX) on trauma-injured rats. ABC immunohistochemical method and histochemical method on detection of Ca2+- dependent acid phosphatase activity were used for the morpho-functional study. By recording the electrical activity of the signals from the single neurons in and below the SC injury place, NOX venom has been shown to result in the complete restoration of hypothalamic-spinal projections originated from ipsi- and contra-lateral PVN and SON to neurons of SC lumbar part. NOX prevented the scar formation, well observed two months after SC injury in the control rats, resulted in the regeneration of nerve fibers growing through the trauma region, survival of the PRP-1- and LVV-H7-immunoreactive (Ir) neurons, and increase of the PRP-1- and LVV-H7-Ir nerve fibers and astrocytes in the SC lesion region. NOX was suggested to exert the neuroprotective effect, involving the PRP-1 and LVV-H7 in the underlying mechanism of neuronal recovery.]

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[POSTNATAL EXPRESSION PATTERN OF DOUBLECORTIN (DCX) IN SOME AREAS OF THE DEVELOPING BRAIN OF MOUSE]

TAKÁCS József, ROBERTA Zaninetti, VÍG Julianna, VASTAGH Csaba, HÁMORI József

[We have investigated the spatio-temporal expression pattern of doublecortin (DCX) protein from postnatal day (P) 2 to postnatal day (P) 22 in the brain of developing mouse. We compared the expression of DCX in the rostral migratory stream (RMS) and dentate gyrus of the hippocampus (DG). Weak expression of DCX was detected in the RMS at P5, it became gradually stronger during the second postnatal week and reached its strongest expression by P18-P22. Moderate DCX immunostaining was present in the DG at P11, its marked expression - characteristic of newly generated neurons in the adult DG - appeared only after P22. Morphological and functional maturation was different in the RMS and DG, continuous neurogenesis appeared earlier in the RMS than in the DG.]

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Late simultaneous carcinomatous meningitis, temporal bone infiltrating macro-metastasis and disseminated multi-organ micro-metastases presenting with mono-symptomatic vertigo – a clinico-pathological case reporT

JARABIN András János, KLIVÉNYI Péter, TISZLAVICZ László, MOLNÁR Anna Fiona, GION Katalin, FÖLDESI Imre, KISS Geza Jozsef, ROVÓ László, BELLA Zsolt

Although vertigo is one of the most common complaints, intracranial malignant tumors rarely cause sudden asymmetry between the tone of the vestibular peripheries masquerading as a peripheral-like disorder. Here we report a case of simultaneous temporal bone infiltrating macro-metastasis and disseminated multi-organ micro-metastases presenting as acute unilateral vestibular syndrome, due to the reawakening of a primary gastric signet ring cell carcinoma. Purpose – Our objective was to identify those pathophysiological steps that may explain the complex process of tumor reawakening, dissemination. The possible causes of vestibular asymmetry were also traced. A 56-year-old male patient’s interdisciplinary medical data had been retrospectively analyzed. Original clinical and pathological results have been collected and thoroughly reevaluated, then new histological staining and immunohistochemistry methods have been added to the diagnostic pool. During the autopsy the cerebrum and cerebellum was edematous. The apex of the left petrous bone was infiltrated and destructed by a tumor mass of 2x2 cm in size. Histological reexamination of the original gastric resection specimen slides revealed focal submucosal tumorous infiltration with a vascular invasion. By immunohistochemistry mainly single infiltrating tumor cells were observed with Cytokeratin 7 and Vimentin positivity and partial loss of E-cadherin staining. The subsequent histological examination of necropsy tissue specimens confirmed the disseminated, multi-organ microscopic tumorous invasion. Discussion – It has been recently reported that the expression of Vimentin and the loss of E-cadherin is significantly associated with advanced stage, lymph node metastasis, vascular and neural invasion and undifferentiated type with p<0.05 significance. As our patient was middle aged and had no immune-deficiency, the promoting factor of the reawakening of the primary GC malignant disease after a 9-year-long period of dormancy remained undiscovered. The organ-specific tropism explained by the “seed and soil” theory was unexpected, due to rare occurrence of gastric cancer to metastasize in the meninges given that only a minority of these cells would be capable of crossing the blood brain barrier. Patients with past malignancies and new onset of neurological symptoms should alert the physician to central nervous system involvement, and the appropriate, targeted diagnostic and therapeutic work-up should be established immediately. Targeted staining with specific antibodies is recommended. Recent studies on cell lines indicate that metformin strongly inhibits epithelial-mesenchymal transition of gastric cancer cells. Therefore, further studies need to be performed on cases positive for epithelial-mesenchymal transition.

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Neuroscience highlights: Main cell types underlying memory and spatial navigation

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Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called “Brain GPS”. The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.

Clinical Neuroscience

Simultaneous subdural, subarachnoideal and intracerebral haemorrhage after rupture of a peripheral middle cerebral artery aneurysm

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The cause of intracerebral, subarachnoid and subdural haemorrhage is different, and the simultaneous appearance in the same case is extremely rare. We describe the case of a patient with a ruptured aneurysm on the distal segment of the middle cerebral artery, with a concomitant subdural and intracerebral haemorrhage, and a subsequent secondary brainstem (Duret) haemorrhage. The 59-year-old woman had hypertension and diabetes in her medical history. She experienced anomic aphasia and left-sided headache starting one day before admission. She had no trauma. A few minutes after admission she suddenly became comatose, her breathing became superficial. Non-contrast CT revealed left sided fronto-parietal subdural and subarachnoid and intracerebral haemorrhage, and bleeding was also observed in the right pontine region. The patient had leucocytosis and hyperglycemia but normal hemostasis. After the subdural haemorrhage had been evacuated, the patient was transferred to intensive care unit. Sepsis developed. Echocardiography did not detect endocarditis. Neurological status, vigilance gradually improved. The rehabilitation process was interrupted by epileptic status. Control CT and CT angiography proved an aneurysm in the peripheral part of the left middle cerebral artery, which was later clipped. Histolo­gical examination excluded mycotic etiology of the aneu­rysm and “normal aneurysm wall” was described. The brain stem haemorrhage – Duret bleeding – was presumably caused by a sudden increase in intracranial pressure due to the supratentorial space occupying process and consequential trans-tentorial herniation. This case is a rarity, as the patient not only survived, but lives an active life with some residual symptoms.

Clinical Neuroscience

Delirium due to the use of topical cyclopentolate hydrochloride

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Introduction - Our aim is to present a rare case where a child had delirium manifestation after instillation of cyclopentolate. Case presentation - A 7-year old patient was seen in our outpatient clinic, and cyclopentolate was dropped three times at 10 minutes intervals in both eyes. The patient suddenly developed behavioral disorders along with gait disturbance, and complained of visual hallucinations 20-25 minutes after the last drop. The patient was transferred to intensive care unit and 0.02 mg/kg IV. physostigmine was administered. The patient improved after minutes of onset of physostigmine, and was discharged with total recovery after 30 minutes. Conclusion - Delirium is a rare systemic side effect of cyclopentolate. The specific antidote is physostigmine, which can be used in severely agitated patients who are not responding to other therapies.

Clinical Neuroscience

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Background and aims – Description of two cases of rare intravascular large B-cell lymphoma and secondary T-cell lymphoma diagnosed postmortem, that manifested clinically as longitudinally extensive transverse myelitis (LETM). We discuss causes of diagnostic difficulties, deceptive radiological and histological investigations, and outline diagnostic procedures based on our and previously reported cases. Case reports – Our first case, a 48-year-old female was admitted to the neurological department due to paraparesis. MRI suggested LETM, but the treatments were ineffective. She died after four weeks because of pneumonia and untreatable polyserositis. Pathological examination revealed intravascular large B-cell lymphoma (IVL). Our second case, a 61-year-old man presented with headache and paraparesis. MRI showed small bitemporal lesions and lesions suggesting LETM. Diagnostic investigations were unsuccessful, including tests for possible lymphoma (CSF flow cytometry and muscle biopsy for suspected IVL). Chest CT showed focal inflammation in a small area of the lung, and adrenal adenoma. Brain biopsy sample from the affected temporal area suggested T-cell mediated lymphocytic (paraneoplastic or viral) meningoencephalitis and excluded diffuse large B-cell lymphoma. The symptoms worsened, and the patient died in the sixth week of disease. The pathological examination of the presumed adenoma in the adrenal gland, the pancreatic tail and the lung lesions revealed peripheral T-cell lymphoma, as did the brain and spinal cord lesions. Even at histological examination, the T-cell lymphoma had the misleading appearance of inflammatory condition as did the MRI. Conclusion – Lymphoma can manifest as LETM. In cases of etiologically unclear atypical LETM in patients older than 40 years, a random skin biopsy (with subcutaneous adipose tissue) from the thigh and from the abdomen is strongly recommended as soon as possible. This may detect IVL and provide the possibility of prompt chemotherapy. In case of suspicion of lymphoma, parallel examination of the CSF by flow cytometry is also recommended. If skin biopsy is negative but lymphoma suspicion remains high, biopsy from other sites (bone marrow, lymph nodes or adrenal gland lesion) or from a simultaneously existing cerebral lesion is suggested, to exclude or prove diffuse large B-cell lymphoma, IVL, or a rare T-cell lymphoma.