NMDA receptor blockade alters the intracellular distribution of neuronal nitric oxide synthase in the superficial layers of the rat superior colliculus.

Nitric oxide (NO) is a molecular messenger involved in several events of synaptic plasticity in the central nervous system. Ca2+ influx through the N-methyl-D-aspartate receptor (NMDAR) triggers the synthesis of NO by activating the enzyme neuronal nitric oxide synthase (nNOS) in postsynaptic densities. Therefore, NMDAR and nNOS are part of the intricate scenario of postsynaptic densities. In the present study, we hypothesized that the intracellular distribution of nNOS in the neurons of superior colliculus (SC) superficial layers is an NMDAR activity-dependent process. We used osmotic minipumps to promote chronic blockade of the receptors with the pharmacological agent MK-801 in the SC of 7 adult rats. The effective blockade of NMDAR was assessed by changes in the protein level of the immediate early gene NGFI-A, which is a well-known NMDAR activity-dependent expressing transcription factor. Upon chronic infusion of MK-801, a decrease of 47% in the number of cells expressing NGFI-A was observed in the SC of treated animals. Additionally, the filled dendritic extent by the histochemical product of nicotinamide adenine di-nucleotide phosphate diaphorase was reduced by 45% when compared to the contralateral SC of the same animals and by 64% when compared to the SC of control animals. We conclude that the proper intracellular localization of nNOS in the retinorecipient layers of SC depends on NMDAR activation. These results are consistent with the view that the participation of NO in the physiological and plastic events of the central nervous system might be closely related to an NMDAR activity-dependent function.

NMDA receptor blockade alters the intracellular distribution of neuronal nitric oxide synthase in the superficial layers of the rat superior colliculus

Nitric oxide (NO) is a molecular messenger involved in several events of synaptic plasticity in the central nervous system. Ca2+ influx through the N-methyl-D-aspartate receptor (NMDAR) triggers the synthesis of NO by activating the enzyme neuronal nitric oxide synthase (nNOS) in postsynaptic densities. Therefore, NMDAR and nNOS are part of the intricate scenario of postsynaptic densities. In the present study, we hypothesized that the intracellular distribution of nNOS in the neurons of superior colliculus (SC) superficial layers is an NMDAR activity-dependent process. We used osmotic minipumps to promote chronic blockade of the receptors with the pharmacological agent MK-801 in the SC of 7 adult rats. The effective blockade of NMDAR was assessed by changes in the protein level of the immediate early gene NGFI-A, which is a well-known NMDAR activity-dependent expressing transcription factor. Upon chronic infusion of MK-801, a decrease of 47 percent in the number of cells expressing NGFI-A was observed in the SC of treated animals. Additionally, the filled dendritic extent by the histochemical product of nicotinamide adenine di-nucleotide phosphate diaphorase was reduced by 45 percent when compared to the contralateral SC of the same animals and by 64 percent when compared to the SC of control animals. We conclude that the proper intracellular localization of nNOS in the retinorecipient layers of SC depends on NMDAR activation. These results are consistent with the view that the participation of NO in the physiological and plastic events of the central nervous system might be closely related to an NMDAR activity-dependent function.

Diversity among satellite glial cells in dorsal root ganglia of the rat.

Peripheral glial cells consist of satellite, enteric glial, and Schwann cells. In dorsal root ganglia, besides pseudo-unipolar neurons, myelinated and nonmyelinated fibers, macrophages, and fibroblasts, satellite cells also constitute the resident components. Information on satellite cells is not abundant; however, they appear to provide mechanical and metabolic support for neurons by forming an envelope surrounding their cell bodies. Although there is a heterogeneous population of neurons in the dorsal root ganglia, satellite cells have been described to be a homogeneous group of perineuronal cells. Our objective was to characterize the ultrastructure, immunohistochemistry, and histochemistry of the satellite cells of the dorsal root ganglia of 17 adult 3-4-month-old Wistar rats of both genders. Ultrastructurally, the nuclei of some satellite cells are heterochromatic, whereas others are euchromatic, which may result from different amounts of nuclear activity. We observed positive immunoreactivity for S-100 and vimentin in the cytoplasm of satellite cells. The intensity of S-100 protein varied according to the size of the enveloped neuron. We also noted that vimentin expression assumed a ring-like pattern and was preferentially located in the cytoplasm around the areas stained for S-100. In addition, we observed nitric oxide synthase-positive small-sized neurons and negative large-sized neurons equal to that described in the literature. Satellite cells were also positive for NADPH-diaphorase, particularly those associated with small-sized neurons. We conclude that all satellite cells are not identical as previously thought because they have different patterns of glial marker expression and these differences may be correlated with the size and function of the neuron they envelope.

Diversity among satellite glial cells in dorsal root ganglia of the rat

Peripheral glial cells consist of satellite, enteric glial, and Schwann cells. In dorsal root ganglia, besides pseudo-unipolar neurons, myelinated and nonmyelinated fibers, macrophages, and fibroblasts, satellite cells also constitute the resident components. Information on satellite cells is not abundant; however, they appear to provide mechanical and metabolic support for neurons by forming an envelope surrounding their cell bodies. Although there is a heterogeneous population of neurons in the dorsal root ganglia, satellite cells have been described to be a homogeneous group of perineuronal cells. Our objective was to characterize the ultrastructure, immunohistochemistry, and histochemistry of the satellite cells of the dorsal root ganglia of 17 adult 3-4-month-old Wistar rats of both genders. Ultrastructurally, the nuclei of some satellite cells are heterochromatic, whereas others are euchromatic, which may result from different amounts of nuclear activity. We observed positive immunoreactivity for S-100 and vimentin in the cytoplasm of satellite cells. The intensity of S-100 protein varied according to the size of the enveloped neuron. We also noted that vimentin expression assumed a ring-like pattern and was preferentially located in the cytoplasm around the areas stained for S-100. In addition, we observed nitric oxide synthase-positive small-sized neurons and negative large-sized neurons equal to that described in the literature. Satellite cells were also positive for NADPH-diaphorase, particularly those associated with small-sized neurons. We conclude that all satellite cells are not identical as previously thought because they have different patterns of glial marker expression and these differences may be correlated with the size and function of the neuron they envelope.

Polyphosphate polymers during early embryogenesis of Periplaneta americana.

Inorganic polyphosphates (PolyP) are linear polymers of phosphate (Pi) residues linked by high-energy phosphoanhydride bonds. Despite a wide distribution, their role during insect embryogenesis has not been examined so far. In this study, we show the mobilization of PolyP polymers during the embryogenesis of the cockroach Periplaneta americana. PolyP was detected by enzymatic and fluorimetric assays and found to accumulate in two main sizes by agarose gel electrophoresis. Confocal microscopy showed their presence in small vesicles. In addition, X-ray microanalysis of small vesicles showed considerable amounts of calcium, sodium and magnesium, suggesting an association of PolyP with these elements. Variations of the free Ca+2, Pi and PolyP levels were observed during the first days of embryogenesis. Our results are consistent with the hypothesis that phosphate ions modulate PolyP variation and that PolyP hydrolysis result in increasing free Ca+2 levels. This is the first investigation of PolyP metabolism during embryogenesis of an insect and might shed light on the mechanisms involving Pi storage and homeostasis during this period. We suggest that PolyP, mainly stored in small vesicles, might be involved in the functional control of Ca+2 and Pi homeostasis during early embryogenesis of P. Americana.

Ganglioside 9-O-acetyl GD3 expression is upregulated in the regenerating peripheral nerve.

Evidence accumulates suggesting that 9-O-acetylated gangliosides, recognized by a specific monoclonal antibody (Jones monoclonal antibody), are involved in neuronal migration and axonal growth. These molecules are expressed in rodent embryos during the period of axon extension of peripheral nerves and are absent in adulthood. We therefore aimed at verifying if these molecules are re-expressed in adult rats during peripheral nerve regeneration. In this work we studied the time course of ganglioside 9-O-acetyl GD3 expression during regeneration of the crushed sciatic nerve and correlated this expression with the time course of axonal regeneration as visualized by immunohistochemistry for neurofilament 200 in the nerve. We have found that the ganglioside 9-O-acetyl GD3 is re-expressed during the period of regeneration and this expression correlates spatio-temporally with the arrival of axons to the lesion site. Confocal analysis of double and triple labeling experiments allowed the localization of this ganglioside to Schwann cells encircling growing axons in the sciatic nerve. Explant cultures of peripheral nerves also revealed ganglioside expressing reactive Schwann cells migrating from the normal and previously crushed nerve. Ganglioside 9-O-acetyl GD3 is also upregulated in DRG neurons and motoneurons of the ventral horn of spinal cord showing that the reexpression of this molecule is not restricted to Schwann cells. These results suggest that ganglioside 9-O-acetyl GD3 may be involved in the regrowth of sciatic nerve axons after crush being upregulated in both neurons and glia.

Regulation and function of neurogenesis in the adult vertebrate brain

Most adult tissues retain a reservoir of self-renewing, multipotent stem cells that can generate differentiated tissue components. Until recently, the brain was thought to be an exception to this rule and for many years the pervasive dogma of neurobiology relegated neurogenesis to the embryonic and earlier postnatal stages of development. The discovery of constant neuronal replacement in the adult brain has changed the way we think about neurological diseases and about the exploration of new strategies for brain repair. In this review we will explore the potential of adult neural stem cells and we will present some of our own work on this subject. We will also discuss the possibility that adult neurogenesis and neuronal replacement may also play a role in therapies aimed at restoring impaired brain function. A better understanding of the various aspects of spontaneous neuronal replacement may also be used to increase the success of procedures with cell therapies.

Regulation and function of neurogenesis in the adult vertebrate brain.

Most adult tissues retain a reservoir of self-renewing, multipotent stem cells that can generate differentiated tissue components. Until recently, the brain was thought to be an exception to this rule and for many years the pervasive dogma of neurobiology relegated neurogenesis to the embryonic and earlier postnatal stages of development. The discovery of constant neuronal replacement in the adult brain has changed the way we think about neurological diseases and about the exploration of new strategies for brain repair. In this review we will explore the potential of adult neural stem cells and we will present some of our own work on this subject. We will also discuss the possibility that adult neurogenesis and neuronal replacement may also play a role in therapies aimed at restoring impaired brain function. A better understanding of the various aspects of spontaneous neuronal replacement may also be used to increase the success of procedures with cell therapies.

Functional role of a specific ganglioside in neuronal migration and neurite outgrowth

Cell migration occurs extensively during mammalian brain development and persists in a few regions in the adult brain. Defective migratory behavior of neurons is thought to be the underlying cause of several congenital disorders. Knowledge of the dynamics and molecular mechanisms of neuronal movement could expand our understanding of the normal development of the nervous system as well as help decipher the pathogenesis of neurological developmental disorders. In our studies we have identified and characterized a specific ganglioside (9-O-acetyl GD3) localized to the membrane of neurons and glial cells that is expressed in regions of cell migration and neurite outgrowth in the developing and adult rat nervous system. In the present article we review our findings that demonstrate the functional role of this molecule in neuronal motility

Functional role of a specific ganglioside in neuronal migration and neurite outgrowth.

Cell migration occurs extensively during mammalian brain development and persists in a few regions in the adult brain. Defective migratory behavior of neurons is thought to be the underlying cause of several congenital disorders. Knowledge of the dynamics and molecular mechanisms of neuronal movement could expand our understanding of the normal development of the nervous system as well as help decipher the pathogenesis of neurological developmental disorders. In our studies we have identified and characterized a specific ganglioside (9-O-acetyl GD3) localized to the membrane of neurons and glial cells that is expressed in regions of cell migration and neurite outgrowth in the developing and adult rat nervous system. In the present article we review our findings that demonstrate the functional role of this molecule in neuronal motility.

Functional role of a glycolipid in directional movements of neurons.

Migration of neurons from their site of origin to their final destination is a critical and universal step in the formation of the complex structure of the nervous system. The migratory process is thought to be governed in part by genetically and epigenetically defined sequences of signals which are interpreted by migrating cells. The molecular mechanisms that underlie neuronal migration have been the subject of intense investigation. As in other developmental processes, many molecules must participate in neuronal migration. Some molecules, such as cell adhesion molecules and motor proteins, may contribute to discrete steps in the migration act; others, like extracellular signaling molecules, may regulate the activation and/or termination of the migration program. In this article we review findings from our group that demonstrate the functional role(s) of a specific glycolipid in neuronal migration and neurite outgrowth in the developing and adult nervous system.

Expression and function of ganglioside 9-O-acetyl GD3 in postmitotic granule cell development.

We have shown previously that the Jones monoclonal antibody (Jones mAb) recognizes 9-O-acetyl GD3 expressed during periods of neuronal migration and neurite outgrowth in the developing rat nervous system. In the present study we investigated the expression of this ganglioside in the developing cerebellum and correlated this expression with granule cell migration. Electron microscopic immunocytochemistry revealed that around the peak of cerebellar neuronal migration (7-day-old rat), 9-O-acetyl GD3 was localized at the contact sites between migrating granule cells and radial glia in the external granular layer and prospective molecular layer. In addition, using microexplant and slice cultures of the postnatal rat cerebellum, we tested whether the ganglioside detected by our antibody contribute to the regulation of neuronal migration in the cerebellar cortex. We have shown that the Jones mAb blocks the migration of neurons in a dose-dependent manner. These findings suggest strongly that 9-O-acetyl GD3 is involved in granule cell migration in the developing cerebellum.

Redistribution of cPLA(2) in rat renal tubular cell cultures in response to PCBs.

The influence of different polychlorinated biphenyls (PCBs) upon the cytosolic phospholipase A(2) (cPLA(2)) redistribution to the particulate fraction has been investigated in rat renal proximal tubule culture cells. Treatment with Aroclor 1248 increased PLA(2) activity in the particulate fraction in a concentration-dependent manner using two radioactive substrates. However, the activity of PLA(2) in the cytosolic fraction decreased. This work also shows that 2,2',4,4',5,5'-hexachlorobiphenyl (HCB) (a di-ortho-substituted nonplanar congener) can increase the activity of PLA(2) in the particulate fraction and decrease the enzyme activity in the cytosolic fraction. The exposure of cell cultures to 3,3',4,4'-tetrachlorobiphenyl (TCB) (a non-ortho-subtituted planar congener) does not alter PLA(2) activity. These results suggest that PCBs, depending on their planar or nonplanar structures, cause a translocation of the enzyme from the cytosol to membranes. To evaluate this possibility, the contents of immunoreactive cPLA(2) were examined by immunoblot analysis in the high-speed supernatant and the particulate fraction of treated cell cultures. The increases/decreases in the amounts of cPLA(2) protein agree with the increases/decreases of PLA(2) activity previously cited. These data demonstrate that the PCB-stimulated redistribution of cPLA(2) to membranes is associated, at least in part, with the changes detected in the activity of the enzyme.

Migrating neurons cross a reelin-rich territory to form an organized tissue out of embryonic cortical slices.

In this study we show that the radial migration of neuronal precursors out of cerebral cortex of embryonic brain slices cultured for 4-7 days gives rise to an organized tissue that forms de novo off developing slices. In our in vitro preparations, migrating neuronal precursors overshot the marginal zone, as did the elongation of radial glial processes out of the slices. These cells detached from radial glia at a distance from the cortex and differentiated into pyramidal and nonpyramidal profiles that expressed different neuronal markers. Glial precursors were shown to proliferate in the slice and in the neotissue, and to differentiate into astrocytes. We show that cells expressing reelin in the marginal zone of embryonic cortical slices persist after a week in culture, which implies that neuronal migration is not necessarily hindered by the presumed stop signals provided by reelin in the marginal zone. Furthermore, our results provide a new model for in vitro studies of migration and differentiation during cortical development.

Trisomy/ tetrasomy of chromosome 8 and +i(8q) as the sole chromosome abnormality in three adult patients with myelomonocytic leukemia.

We report three cases of tetrasomy 8 associated with myeloid disease. Two patients had chronic myelomonocytic leukemia (CMMoL) and the other had acute monocytic leukemia (AML M5 FAB). Two patients had trisomy/tetrasomy chromosome 8 as the sole abnormality. The other patient with CMMoL had two normal 8 chromosomes plus one isochromosome 8q; this is the first case of long arm chromosome 8 tetrasomy without short arm 8 monosomy. This cytogenetic finding suggests the importance of the genes located in the long arms of chromosome 8.

Hydroxamate iron complex with phenoloxidase activity acting on lignin and chlorolignins.

The properties of a siderophore model, acetohydroxamic acid (AHA), of desferral were studied. The pH, ionic strength, and AHA/Fe(III) ratios for o-dianisidine oxidation were optimized. Phenoloxidase activity of hydroxamates/Fe(III) acting on o-dianisidine at pH 7.0 and pH 3.0 was observed. Under these conditions, AHA was able to reduce Fe(III) to Fe(II) followed by ferrozine complexation. AHA/Fe(III) complex degraded lignin and chlorolignins from kraft effluent E1 65% and 85%, respectively, after 24 h.

[Cerebrospinal fluid changes in multiple myeloma. Review of the literature and report of a case]. / Alterações do liquido cefalorraqueano no mieloma multiplo. Revisão de literatura e registro de um caso.

The authors make a literature review about the meningeal involvement in MM and verified that the presence of myeloma cells in the CSF is rare. They report a case of cranial MM in which the atypical plasma cells (plasmoblasts) were present in CSF. The CSF examination was the principal finding to the diagnosis of this case; it was confirmed by IgG monoclonal "M" gamophaty present in serum, CSF and urine obtained through proteic electrophoresis profile and by necropsy that revealed mielomatous proliferation in skull base with subarachnoidal space infiltration.

Alteracoes do liquido cefalorraqueano no mieloma multiplo: revisao de literatura e registro de um caso. / Changes in the cerebrospinal fluid in multiple myeloma: review of the literature and report of a case

Os autores fazem uma revisao de literatura sobre o comprometimento do sistema nervoso central em casos de mieloma multiplo (MM) verificando que o aparecimento de celulas plasmaticas atipicas (plasmoblastos) no LCR e raro. E apresentado um caso MM tipo IgG de localizacao predominantemente nos ossos das base do cranio. O exame do LCR foi um dos principais para o diagnostico da neoplasia, cuja citomorfologia revelou exclusivamente a presenca de plasmoblastos. A confirmacao do diagnostico se fez pelo perfil eletroforetico das proteinas do soro, do LCR e da urina, que revelou uma gamopatia monoclonal "M" tipo IgG e, tambem pelos achados de necropsia que evidenciaramm proliferacao mielomatosa nos ossos da base do cranio com infiltracao do espaco subaracnoideo craniano

Infeccoes graves em recem-nascidos por bacterias do trato genital. / Severe infections in newborn infants due to bacteria of genital tract

Sao descritos dois casos de meningite bacteriana causada por Streptococcus sp tipo B-hemolitico do grupo B de Lancefield em recemnascidos. Sao discutidos aspectos clinicos, diagnostico laboratorial e etiologia