Maura Castagna

Distribution and cellular localization of the serotonin type 2C receptor messenger RNA in human brain

The regional and cellular distribution of serotonin type 2C receptor messenger RNA was investigated in autopsy samples of human brain by in situ hybridization histochemistry. The main sites of serotonin receptor type 2C messenger RNA expression were the choroid plexus, cerebral cortex, hippocampus, amygdala, some components of the basal ganglia, the substantia nigra, the substantia innominata and the ventromedial hypothalamus, suggesting that this receptor might be involved in the regulation of different brain functions. Interestingly, in all regions examined, the serotonin type 2C receptor messenger RNA was always restricted to subpopulations of cells, suggesting a specific role, perhaps determined by regionality. A comparison of the in situ hybridization results with those previously obtained by means of radioligand binding experiments suggested that in most of the areas analysed the serotonin type 2C receptors were located at axon terminals.

Expression of calcium-binding proteins and selected neuropeptides in the human, chimpanzee, and crab-eating macaque claustrum

The claustrum is present in all mammalian species examined so far and its morphology, chemoarchitecture, physiology, phylogenesis and ontogenesis are still a matter of debate. Several morphologically distinct types of immunostained cells were described in different mammalian species. To date, a comparative study on the neurochemical organization of the human and non-human primates claustrum has not been fully described yet, partially due to technical reasons linked to the postmortem sampling interval. The present study analyze the localization and morphology of neurons expressing parvalbumin (PV), calretinin (CR), NPY, and somatostatin (SOM) in the claustrum of man (# 5), chimpanzee (# 1) and crab-eating monkey (# 3). Immunoreactivity for the used markers was observed in neuronal cell bodies and processes distributed throughout the anterior-posterior extent of human, chimpanzee and macaque claustrum. Both CR- and PV-immunoreactive (ir) neurons were mostly localized in the central and ventral region of the claustrum of the three species while SOM- and NPY-ir neurons seemed to be equally distributed throughout the ventral-dorsal extent. In the chimpanzee claustrum SOM-ir elements were not observed. No co-localization of PV with CR was found, thus suggesting the existence of two non-overlapping populations of PV and CR-ir interneurons. The expression of most proteins (CR, PV, NPY), was similar in all species. The only exception was the absence of SOM-ir elements in the claustrum of the chimpanzee, likely due to species specific variability. Our data suggest a possible common structural organization shared with the adjacent insular region, a further element that emphasizes a possible common ontogeny of the claustrum and the neocortex.

Distribution of the 5-HT5A serotonin receptor mRNA in the human brain

The 5-HT5A receptor is a member of a new subfamily of serotonin [5-hydroxytryptamine (5-HT)] receptors recently cloned from the human and rodent brain. The role of this receptor in normal brain functions as well as its possible involvement in pathological states is still to be determined. We therefore studied the regional distribution and cellular localization of 5-HT5A receptor mRNA in human brain sections from autopsy samples by in situ hybridization histochemistry, in order to obtain anatomical information which might be useful in formulating hypotheses on possible functions subserved by this receptor in the central nervous system (CNS). Our results showed that the main sites of 5-HT5A mRNA expression were the cerebral cortex, hippocampus and cerebellum. In the neocortical regions, the 5-HT5A receptor mRNA was mainly distributed in the layers II-III and V-VI. In the hippocampus, the dentate gyrus and the pyramidal cell layer of the CA1 and CA3 fields expressed 5-HT5A mRNA at high levels. The broad distribution in the neocortex and hippocampus supports the view that the 5-HT5A receptor in these areas might be implicated in high cortical and limbic functions. The 5-HT5A mRNA was widely distributed in the cerebellum where it was highly expressed in the Purkinje cells, in the dentate nucleus and, at a lower level, in the granule cells. Since the cerebellum receives diffuse serotonergic afferents, this finding suggests that the 5-HT5A receptor may have an important role in mediating the effects of 5-HT on cerebellar functions.

Immunohistochemical analysis of myenteric ganglia and interstitial cells of Cajal in ulcerative colitis.

Ulcerative colitis (UC) is an inflammatory bowel disease with alterations of colonic motility, which influence clinical symptoms. Although morpho‐functional abnormalities in the enteric nervous system have been suggested, in UC patients scarce attention has been paid to possible changes in the cells that control colonic motility, including myenteric neurons, glial cells and interstitial cells of Cajal (ICC). This study evaluated the neural‐glial components of myenteric ganglia and ICC in the colonic neuromuscular compartment of UC patients by quantitative immunohistochemical analysis. Full‐thickness archival samples of the left colon were collected from 10 patients with UC (5 males, 5 females; age range 45–62 years) who underwent elective bowel resection. The colonic neuromuscular compartment was evaluated immunohistochemically in paraffin cross‐sections. The distribution and number of neurons, glial cells and ICC were assessed by anti‐HuC/D, ‐S100β and ‐c‐Kit antibodies, respectively. Data were compared with findings on archival samples of normal left colon from 10 sex‐ and age‐matched control patients, who underwent surgery for uncomplicated colon cancer. Compared to controls, patients with UC showed: (i) reduced density of myenteric HuC/D+ neurons and S100β+ glial cells, with a loss over 61% and 38%, respectively, and increased glial cell/neuron ratio; (ii) ICC decrease in the whole neuromuscular compartment. The quantitative variations of myenteric neuro‐glial cells and ICC indicate considerable alterations of the colonic neuromuscular compartment in the setting of mucosal inflammation associated with UC, and provide a morphological basis for better understanding the motor abnormalities often observed in UC patients.

Topography of Gng2- and NetrinG2-Expression Suggests an Insular Origin of the Human Claustrum

The claustrum has been described in the forebrain of all mammals studied so far. It has been suggested that the claustrum plays a role in the integration of multisensory information: however, its detailed structure and function remain enigmatic. The human claustrum is a thin, irregular, sheet of grey matter located between the inner surface of the insular cortex and the outer surface of the putamen. Recently, the G-protein gamma2 subunit (Gng2) was proposed as a specific claustrum marker in the rat, and used to better delineate its anatomical boundaries and connections. Additional claustral markers proposed in mammals include Netrin-G2 in the monkey and latexin in the cat. Here we report the expression and distribution of Gng2 and Netrin-G2 in human post-mortem samples of the claustrum and adjacent structures. Gng2 immunoreactivity was detected in the neuropil of the claustrum and of the insular cortex but not in the putamen. A faint labelling was present also in the external and extreme capsules. Double-labelling experiments indicate that Gng2 is also expressed in glial cells. Netrin-G2 labelling was seen in neuronal cell bodies throughout the claustrum and the insular cortex but not in the medially adjacent putamen. No latexin immunoreactive element was detected in the claustrum or adjacent structures. Our results confirm that both the Gng2 and the Netrin-G2 proteins show an affinity to the claustrum and related formations also in the human brain. The presence of Gng2 and Netrin-G2 immunoreactive elements in the insular cortex, but not in the putamen, suggests a possible common ontogeny of the claustrum and insula.

Constitutive expression of cyclooxygenase-2 in the neuromuscular compartment of normal human colon

Abstract  Prostaglandins regulate various functions throughout the gastrointestinal system. Their biosynthesis depends on cyclooxygenase isoforms, named COX‐1 and COX‐2. The initial hypothesis that COX‐2 is an inducible enzyme has been challenged and its constitutive expression in the stomach has been established. In this study, an immunohistochemical analysis was performed to evaluate the distribution and cellular localization of COX‐2 in normal human colon. Colonic surgical specimens were processed for COX‐2, protein HuC/HuD, neurofilament, S‐100 protein and CD117/c‐kit immunodetection. COX‐2 protein was found to be constitutively expressed in the colonic wall: detectable amounts were localized in mucosal, submucosal and muscular layers, mainly in the neuromuscular compartment. In particular, COX‐2 was expressed in muscularis mucosae, submucosal ganglia, longitudinal muscle layer and myenteric ganglia, the neurons of which displayed different degrees of immunostaining. Intramuscular interstitial cells of Cajal, regarded as important sites for the regulation of enteric neuromuscular activity, were also partly COX‐2 immunoreactive. This study provides a detailed mapping of COX‐2 expression in human colon, and allows better understanding of the roles played by this isoenzyme in gut physiology.

Three-dimensional microsurgical anatomy of cerebellar peduncles

The microsurgical anatomy of cerebellar peduncles and their relationships with neighbouring fasciculi were investigated by using a fibre dissection technique. As the dissection progressed, photographs of each progressive layer were obtained and stereoscopic images were created using the 3D anaglyphic method. These findings provided the anatomical basis for a conceptual division of cerebellar peduncles into segments. The middle cerebellar peduncle (MCP) was divided into two segments: cisternal and intracerebellar segments. The inferior cerebellar peduncle (ICP) was divided into three segments: cisternal, ventricular and intracerebellar segments. The superior cerebellar peduncle (SCP) was divided into three segments: intracerebellar, intermediate and intrategmental segments. The fibre dissection technique disclosed a constant course of peduncular fibres inside the white core of the cerebellum. The pontocerebellar fibres of the MCP pass over and laterally to the bundles of the ICP and SCP. The centripetal fibres of the ICP wrap around the radiation of the SCP and the dentate nucleus, directed towards the cortex of the vermis. The centrifugal bundle of the SCP ascends towards the mesencephalon where it sinks passing below the fibres the lateral lemniscus. The knowledge gained by studying the intrinsic anatomy of the cerebellum is useful to accomplish appropriate surgical planning and, ultimately, to understand the repercussions of surgical procedures on the white matter tracts in this region.

Preoperative rectal cancer staging with phased-array MR

BackgroundWe retrospectively reviewed magnetic resonance (MR) images of 96 patients with diagnosis of rectal cancer to evaluate tumour stage (T stage), involvement of mesorectal fascia (MRF), and nodal metastasis (N stage).Our gold standard was histopathology.MethodsAll studies were performed with 1.5-T MR system (Symphony; Siemens Medical System, Erlangen, Germany) by using a phased-array coil. Our population was subdivided into two groups: the first one, formed by patients at T1-T2-T3, N0, M0 stage, whose underwent MR before surgery; the second group included patients at Tx N1 M0 and T3-T4 Nx M0 stage, whose underwent preoperative MR before neoadjuvant chemoradiation therapy and again 4-6 wks after the end of the treatment for the re-staging of disease.Our gold standard was histopathology.ResultsMR showed 81% overall agreement with histological findings for T and N stage prediction; for T stage, this rate increased up to 95% for pts of group I (48/96), while for group II (48/96) it decreased to 75%.Preoperative MR prediction of histologically involved MRF resulted very accurate (sensitivity 100%; specificity 100%) also after chemoradiation (sensitivity 100%; specificity 67%).ConclusionsPhased-array MRI was able to clearly estimate the entire mesorectal fat and surrounding pelvic structures resulting the ideal technique for local preoperative rectal cancer staging.

Malignant transformation of intramedullary melanocytoma: case report.

OBJECTIVEMeningeal melanocytomas are low-grade primary melanocytic tumors with benign histological features and a favorable clinical prognosis. Transition from meningeal melanocytoma to primary melanoma of the central nervous system is exceptionally rare, with only 5 cases having been previously reported. Here, we discuss a case of malignant transformation of an intramedullary melanocytoma to primary melanoma and review the pertinent literature. CLINICAL PRESENTATIONA 79-year-old woman presented with progressive paresis in the lower limbs followed by sphincter dysfunction. Magnetic resonance imaging scans disclosed an intramedullary lesion located at the T10–T11 level. INTERVENTIONThe patient underwent subtotal resection of an intermediate-grade melanocytoma. Two years later, the tumor recurred locally, and the patient underwent additional surgery to remove the intramedullary mass. The histological findings of the tumor were consistent with an intramedullary malignant melanoma. CONCLUSIONThe malignant transformation of melanocytic tumors of the central nervous system may occur years after surgical treatment, and its incidence remains unknown. Emphasis should be placed on the importance of careful and continued follow-up monitoring of the tumor.

Human brain tumors: multidrug-resistance P-glycoprotein expression in tumor cells and intratumoral capillary endothelial cells

Malignant brain tumor is a lethal disease with currently available treatment options having a limited impact on outcome. Nevertheless, novel therapeutic approaches combined with genetic prediction of chemosensitivity have, in the last decade, significantly improved clinical benefit for the treated patients. The fine characterization of the MDR1 gene encoding for P-glycoprotein (MDR1–Pgp) in brain tumors may be a crucial determinant for evaluating the long-term efficiency of specific anti-cancer compounds. By using a very high specific monoclonal antibody, the MDR1–Pgp was immunodetected in 34 out of 43 grade IV, 6 out of 10 grade III, 4 out of 7 grade II, and 1 out 3 grade I brain tumors. MDR1–Pgp resulted hyper-expressed, both in vessels and in neoplastic cells from the majority of tumors examined, compared to normal parenchyma. This study demonstrates that the MDR1 gene can be detected in all grade tumor brain malignancies and in endothelial cells of newly formed capillaries, thus, impairing drug access at the tumor cell level. Although the role of MDR1–Pgp in tumor blood vessels needs to be further examined and more clearly defined, drug resistance in malignant brain tumors may result from characteristics not only of tumor vasculature but also of neoplastic cells.