Technical and Comparative Aspects of Brain Glycogen Metabolism.

It has been known for over 50 years that brain has significant glycogen stores, but the physiological function of this energy reserve remains uncertain. This uncertainty stems in part from several technical challenges inherent in the study of brain glycogen metabolism, and may also stem from some conceptual limitations. Factors presenting technical challenges include low glycogen content in brain, non-homogenous labeling of glycogen by radiotracers, rapid glycogenolysis during postmortem tissue handling, and effects of the stress response on brain glycogen turnover. Here, we briefly review aspects of glycogen structure and metabolism that bear on these technical challenges, and discuss ways these can be overcome. We also highlight physiological aspects of glycogen metabolism that limit the conditions under which glycogen metabolism can be useful or advantageous over glucose metabolism. Comparisons with glycogen metabolism in skeletal muscle provide an additional perspective on potential functions of glycogen in brain

Metabotropic Glutamate Receptors Protect Oligodendrocytes from Acute Ischemia in the Mouse Optic Nerve.

Studies by Bruce Ransom and colleagues have made a major contribution to show that white matter is susceptible to ischemia/hypoxia. White matter contains axons and the glia that support them, notably myelinating oligodendrocytes, which are highly vulnerable to ischemic-hypoxic damage. Previous studies have shown that metabotropic GluRs (mGluRs) are cytoprotective for oligodendrocyte precursor cells and immature oligodendrocytes, but their potential role in adult white matter was unresolved. Here, we report that group 1 mGluR1/5 and group 2 mGluR3 subunits are expressed in optic nerves from mice aged postnatal day (P)8-12 and P30-35. We demonstrate that activation of group 1 mGluR protects oligodendrocytes against oxygen-glucose deprivation (OGD) in developing and young adult optic nerves. In contrast, group 2 mGluR are shown to be protective for oligodendrocytes against OGD in postnatal but not young adult optic nerves. The cytoprotective effect of group 1 mGluR requires activation of PKC, whilst group 2 mGluR are dependent on negatively regulating adenylyl cyclase and cAMP. Our results identify a role for mGluR in limiting injury of oligodendrocytes in developing and young adult white matter, which may be useful for protecting oligodendrocytes in neuropathologies involving excitoxicity and ischemia/hypoxia

Streptococcus Pneumoniae Meningo-Encephalitis after Trans-Sphenoidal Surgery : a Case Report

WOS: 000272184800017PubMed: 19994813Although meningismus or meningitis are known to occur after pituitary surgery; meningo-encephalitis caused by Streptococcus pneumoniae following a trans-sphenoidal approach has not been previously reported. A 56-year-old man presented with blurred vision. Two days after uneventful surgery, the patient became hyperpyrexic which progressed to confusion and lethargy within 48 hours. Spinal fluid cultures revealed Streptococcus pneumoniae. The patient was treated appropriately and made an uneventful recovery. MR images showed persistent changes within both frontal lobes. This case further suggests that peri-operative antimicrobial chemoprophylaxis may not save the patient from serious surgical infections

Giant chordoid meningioma symptomatic immediately after pregnancy: report of a rare case

sav, aydin/0000-0002-7326-7801WOS: 000278332700009PubMed: 20423691Background: Chordoid meningioma is a very rare subtype of meningioma with less than 90 cases reported in the literature. Meningiomas related with a pregnancy are also very rare. Herein, we present a pregnancy-associated case of a chordoid meningioma and briefly discuss possible mechanisms. Case History: Approximately 10 hours after a Caesarean section, a 37-year-old woman became stuporous with a Glasgow coma scale score of 9 - 10 and the right pupil became dilated without reaction to light. An emergency computed tomography scan showed a right frontotemporal lesion measuring 8 x 7 x 6 cm which enhanced moderately and homogenously after intravenous contrast injection. The patient's hemoglobin level was slightly lower than normal level but there was no dysgammaglobulinemia or lymphoid hyperplasia. The patient was immediately taken to the operating theater and the tumor was gross totally removed. The postoperative period was uneventful; and histopathological diagnosis was chordoid meningioma. Conclusion: The exact mechanism causing a pregnancy-associated increase in the size of meningiomas and the amount of peritumoral edema has not been clearly elucidated. As for this case of chordoid meningioma associated with pregnancy, we think mucin accumulation in tumor could be involved in an increase in the tumor size while delivery procedures with the common anaesthetic and sedative drugs may also have enhanced the peritumoral edema by causing a relative decrease in the cerebral blood flow

An extreme lateral lumbar disc herniation mimicking L4 schwannoma

WOS: 000268312600014PubMed: 19681451Objective: We herein describe a case with an extraspinal mass distorting the right L4 dorsal root ganglion. Initially presumed to be a nerve root schwannoma, the lesion turned out to be a free disc fragment. Methods and Results: A 46-year-old woman presented with a history of mild low back and intense right leg pain. The leg pain was like electrical discharges. Right knee extension was weak together with hyperalgesia and loss of heat sensation in the right L4 dermatome. The right patellar reflex was absent. Electromyography showed acute and chronic denervation of muscles innervated by the right L4 nerve root. MR scan showed a right L4-5 extraforaminal mass distorting the L4 dorsal root ganglion. The mass enhanced homogeneously after gadolinium injection and was thought to be a tumor It was surgically removed using a midline incision and intraspinal, followed by extraspinal dissection. Under the operating microscope, the mass extended between an intact lateral longitudinal ligament and a swollen dorsal root ganglion. Histopathologic examination ruled out a tumor and showed that the mass consisted of degenerated disc material surrounded by a large peripheral zone of neovascularization. Conclusion: Extraforaminal periganglionic free, encapsulated disc fragments may mimic tumoral masses, from which they may not be distinguished on MRI

Neuroscience: a mechanism for myelin injury

The cells that insulate neuronal processes with a myelin membrane sheath are damaged during stroke. Data now show that an influx of calcium ions mediated by the TRPA1 protein contributes to myelin injury