Prasanna Karki

Attenuation of inflammatory and neuropathic pain behaviors in mice through activation of free fatty acid receptor GPR40

BackgroundThe G-protein-coupled receptor 40 (GPR40) is suggested to function as a transmembrane receptor for medium- to long-chain free fatty acids and is implicated to play a role in free fatty acids-mediated enhancement of glucose-stimulated insulin secretion from pancreas. However, the functional role of GPR40 in nervous system including somatosensory pain signaling has not been fully examined yet.ResultsIntrathecal injection of GPR40 agonist (MEDICA16 or GW9508) dose-dependently reduced ipsilateral mechanical allodynia in CFA and SNL models and thermal hyperalgesia in carrageenan model. These anti-allodynic and anti-hyperalgesic effects were almost completely reversed by a GPR40 antagonist, GW1100. Immunohistochemical analysis revealed that GPR40 is expressed in spinal dorsal horn and dorsal root ganglion neurons, and immunoblot analysis showed that carrageenan or CFA inflammation or spinal nerve injury resulted in increased expression of GPR40 in these areas. Patch-clamp recordings from spinal cord slices exhibited that bath-application of either MEDICA16 or GW9508 significantly decreased the frequency of spontaneous excitatory postsynaptic currents in the substantia gelatinosa neurons of the three pain models.ConclusionsOur results indicate that GPR40 signaling pathway plays an important suppressive role in spinal nociceptive processing after inflammation or nerve injury, and that GPR40 agonists might serve as a new class of analgesics for treating inflammatory and neuropathic pain.

Mature posterior fossa teratoma mimicking dermoid cyst

We describe a very rare case of mature posterior fossa teratoma in an adult who presented with clinico-radiological findings consistent with a dermoid cyst. A computed tomography scan showed a hypodense mass in the cistern magna with calcification and a sinus tract in the occipital bone. Magnetic resonance imaging revealed a hypo- to hyperintense mass without contrast enhancement. The intraoperative picture showed a dermal sinus and a cyst containing lipid, keratin and hair. Histopathological examination showed a tumor with components of all the three germ layers; thereby, a diagnosis of mature teratoma was made. The histopathological differentiation between teratoma and dermoid cyst is very valuable for ruling out the presence of immature/malignant or germinomatous components that would require further adjuvant therapies. Thus, we here present a rare case of posterior fossa teratoma mimicking dermoid cyst and emphasize the importance of histopathological differentiation between these entities.

Choroid Plexus Tumors: Experience of 10 Cases with Special References to Adult Cases

Choroid plexus tumors (CPTs) are rare intraventricular neoplasms accounting for about 0.3–0.6% of all intracranial tumors. This retrospective study on CPTs presents clinico-pathological features and management strategies based on a 20-year single-institutional experience. This series included 10 consecutive patients with pathologically proven CPTs; 5 choroid plexus papillomas (CPPs), 3 atypical CPPs (ACPPs), and 2 choroid plexus carcinomas (CPCs). Their clinical, radiological, and histopathological features as well as management including follow-up studies were reviewed. The patients included five males and five females, aging from 0 years to 61 years with median of 28 years. The affected site was lateral ventricle in two adults and fourth ventricle in eight patients; four children and four adults. The most common symptoms were gait disturbance and memory disturbance. All the patients underwent craniotomy with total, subtotal, and partial removals achieved in 50%, 40%, and 10% of the patients, respectively. The occurrence of the high grade subtypes was 50% in both the adult and pediatric groups. The Ki-67/MIB-1 index increased across the three histological subtypes, from CPP to ACPP and then to CPC. Adjuvant therapy was administered in three patients. The two patients (one adult and one child) with CPC died of whole central nervous system dissemination. At a median of 62-month follow-up, the other eight patients were alive, with only one patient having recurrence and reoperation. The results demonstrate that gross total resection is usually curative for CPP and ACPP, and adjuvant chemoradiotherapy would be required for CPC and incompletely resected ACPP.