Cholangiohydatidosis. Clinical features, postoperative complications and hospital mortality. A systematic review

BACKGROUND

Cholangiohydatidosis (CH) is an evolutionary complication of hepatic cystic echinococcosis, associated with increased morbidity and mortality. The aim of this study was to describe the available evidence regarding clinical characteristics of CH, postoperative complications and hospital mortality.

METHODOLOGY/PRINCIPAL FINDINGS

Systematic review. Studies related to CH with no language or publication restriction were included. Sensitive searches were performed in Trip Database, SciELO, BIREME-BVS, WoS, PubMed, EMBASE and SCOPUS. MeSH and free terms were used, including articles up to April 2023. The main outcome variables were postoperative complications and hospital mortality; the secondary ones were publication year, origin and design of primary studies, main clinical manifestation, anatomical location and type of cysts, hospital stay, surgical procedure performed, reinterventions; and methodological quality of primary studies, which was assessed using MInCir-T and MInCir-P scales. Descriptive statistics, calculation of weighted averages and their comparison by least squares logistic regression were applied. 446 studies were retrieved from the searches performed, 102 of which met the inclusion and exclusion criteria. The studies analyzed represent 1241 patients. The highest proportion of articles was published in the last decade (39.2%). Reports are mainly from Turkey (28.4%), Greece (9.8%), Morocco and Spain (8.8% each). With a weighted mean of 14.3 days of hospital stance; it was verified that 26.2% of patients developed postoperative complications (74,3% Clavien y Dindo III y IV), 6.7% needed re-interventions, and 3.7% died. When comparing the variables age, postoperative complications, hospital mortality, and reinterventions in two periods of time (1982-2006 vs. 2007-2023), no statistically significant differences were found. When applying the MInCir-T and MInCir-P scales, the methodological quality of the primary studies was 9.6±1.1 and 14.5±4.3 points, respectively.

CONCLUSION/SIGNIFICANCE

CH is associated with severe postoperative complications and significant hospital mortality, independent of the development of therapeutic support associated with the passage of time.

Human papillomavirus infection and lung adenocarcinoma: special benefit is observed in patients treated with immune checkpoint inhibitors

BACKGROUND

Human papilloma virus (HPV) has been associated with the development and modulation of response in a series of neoplasms. In the case of lung adenocarcinoma, its role in etiology and pathogenesis is still controversial. Considering that this infection brings foreign epitopes, it could be of prognostic significance in patients with lung adenocarcinoma treated with immunotherapy.

METHODS

In a retrospective cohort study we evaluated the presence of HPV genomic material in lung adenocarcinoma primary lesions with the INNO-LiPA platform. Viral replication was also evaluated by detecting the presence of oncoprotein E6/E7 messenger RNA (mRNA) by quantitative RT-PCR. To confirm possible hypotheses regarding viral oncogenesis, vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1 (HIF1) were evaluated with stromal fibrosis and immunoscore.

RESULTS

A total of 133 patients were included in the analysis, of whom 34 tested positive for HPV, reaching an estimated prevalence of 25.6% [95% confidence interval (CI) 18.2% to 32.9%]. E6/7 mRNA was identified in 28 out of the 34 previously positive cases (82.3%). In immune checkpoint inhibitor (ICI)-treated patients, the median overall survival reached 22.3 months [95% CI 19.4 months- not reached (NR)] for HPV-negative and was not reached in HPV-positive (HPV+) ones (95% CI 27.7-NR; P = 0.008). With regard to progression-free survival, HPV- patients reached a median of 9.2 months (95% CI 7.9-11.2 months) compared to 14.3 months (95% CI 13.8-16.4 months) when HPV was positive (P = 0.001). The overall response rate for HPV+ patients yielded 82.4% compared to 47.1% in negative ones. No differences regarding programmed death-ligand 1, VEGF, HIF1, stromal fibrosis, or immunoscore were identified.

CONCLUSIONS

In patients with HPV+ lung adenocarcinoma, a significant benefit in overall response and survival outcomes is observed.

Klf9 is necessary and sufficient for Purkinje cell survival in organotypic culture

During their phase of developmental programmed cell death (PCD), neurons depend on target-released trophic factors for survival. After this period, however, they critically change as their survival becomes target-independent. The molecular mechanisms underlying this major transition remain poorly understood. Here, we investigated, which transcription factors (TFs) might be responsible for the closure of PCD. We used Purkinje cells as a model since their PCD is restricted to the first postnatal week in the mouse cerebellum. Transcriptome analysis of Purkinje cells during or after PCD allowed the identification of Krüppel like factor 9 (Klf9) as a candidate for PCD closure, given its high increase of expression at the end of the 1st postnatal week. Klf9 function was tested in organotypic cultures, through lentiviral vector-mediated manipulation of Klf9 expression. In absence of trophic factors, the Purkinje cell survival rate is of 40%. Overexpression of Klf9 during PCD dramatically increases the Purkinje cell survival rate from 40% to 88%, whereas its down-regulation decreases it to 14%. Accordingly, in organotypic cultures of Klf9 knockout animals, Purkinje cell survival rate is reduced by half as compared to wild-type mice. Furthermore, the absence of Klf9 could be rescued by Purkinje cell trophic factors, Insulin growth factor-1 and Neurotrophin3. Altogether, our results ascribe a clear role of Klf9 in Purkinje cell survival. Thus, we propose that Klf9 might be a key molecule involved in turning off the phase of Purkinje PCD.

Intrinsic versus extrinsic determinants during the development of Purkinje cell dendrites

The peculiar shape and disposition of Purkinje cell (PC) dendrites, planar and highly branched, offers an optimal model to analyze cellular and molecular regulators for the acquisition of neuronal dendritic trees. During the first 2 weeks after the end of the proliferation period, PCs undergo a 2-phase remodeling process of their dendrites. The first phase consists in the complete retraction of the primitive but extensive dendritic tree, together with the formation of multiple filopodia-like processes arising from the cell body. In the second phase, there is a progressive disappearance of the somatic processes along with rapid growth and branching of the mature dendrite. Mature Purkinje cell dendrites bear two types of spiny protrusions, named spine and thorn. The spines are numerous, elongated, located at the distal dendritic compartment and form synapses with parallel fibers, whereas the thorns are shorter, rounded, emerge from the proximal compartment and synapse with climbing fibers. Different culture models and mutant mice analyses suggest the identification of intrinsic versus extrinsic determinants of the Purkinje cell dendritic development. The early phase of dendritic remodeling might be cell autonomous and regulated by specific transcription factors such as retinoid-related orphan receptor alpha (RORalpha). Afferent fibers, trophic factors and hormones regulate the orientation and growth of the mature dendritic tree contributing, with still unknown intrinsic factors, to sculpt its general architecture. The formation of spines appears as an intrinsic phenomenon independent of their presynaptic partner, the parallel fibers, and confined to the distal compartment by inhibitory influences of the climbing fibers along the proximal compartment.

Expression of X-chromosome linked inhibitor of apoptosis protein in mature Purkinje cells and in retinal bipolar cells in transgenic mice induces neurodegeneration

Transgenic mice with overexpression of the caspase-inhibitor, X-chromosome-linked inhibitor of apoptosis protein (XIAP) in Purkinje cell (PC) and in retinal bipolar cells (RBCs) were produced to study the regulation of cell death. Unexpectedly, an increased neurodegeneration was observed in the PCs in these L7-XIAP mice after the third postnatal week with the mice exhibiting severe ataxia. The loss of PCs was independent of Bax as shown by crossing the L7-XIAP mice with Bax gene-deleted mice. Electron microscopy revealed intact organelles in PCs but with the stacking of ER cisterns indicative of cell stress. Immunostaining for cell death proteins showed an increased phosphorylation of c-Jun in the PCs, suggesting an involvement in cell degeneration. Apart from PCs, the number of RBCs was decreased in adult retina in line with the expression pattern for the L7 promoter. The data show that overexpression of the anti-apoptotic protein XIAP in vulnerable neurons leads to enhanced cell death. The mechanisms underlying this neurodegeneration can be related to the effects of XIAP on cell stress and altered cell signaling.

Cell death and axon regeneration of Purkinje cells after axotomy: challenges of classical hypotheses of axon regeneration

Although adult mammalian neurons are able to regenerate their axons in the peripheral nervous system under certain conditions, they are not able to do it in the central nervous system. The environment surrounding the severed axons appears to be a key factor for axon regeneration. Many studies aiming to enhance axon regeneration in the CNS of adult mammals have successfully manipulated this environment by adding growth permissive molecules and/or neutralizing growth inhibitory molecules. In both cases, the number of axons able to regenerate was low and the different neuronal populations were not equal in their regenerative response, suggesting that manipulation of the environment is not always sufficient. This is particularly well illustrated in the cerebellar system, in which axotomized inferior olivary neurons regenerate when confronted with a permissive environment, whereas mature Purkinje cells do not. The intrinsic ability of a neuron to regenerate its axon is generally correlated with the intensity of its reaction to axotomy (expression of molecules, probability to die). Furthermore, molecules such as GAP-43 (growth-associated molecule) and c-Jun are involved in both axon regeneration and cell death suggesting that these two processes are linked. Surprisingly, Purkinje cells lose their capacity to regenerate their axon (even in the absence of myelin) during development before losing their capacity to react to an axotomy by cell death. These results emphasize the different reactions to axotomy between neuron types and underline that in Purkinje cells, the two cell decisions (axon regeneration and cell death) are differently regulated and therefore not part of the same signaling pathway.

Adult neural stem cells from the mouse subventricular zone are limited in migratory ability compared to progenitor cells of similar origin

The subventricular zone (SVZ) in the forebrain is the largest source of neural stem cells and progenitor cells in the adult CNS. To assess the ability of adult neural stem cells to survive, differentiate and migrate, we have compared the behavior of dissociated, neurosphere-derived stem cells with that of progenitor cells in transplantation experiments. This ability was first tested in vivo, offering the stem cells the possibility to migrate along the rostral migratory stream (RMS), their specific pathway. In addition, the differential behaviors of the two classes of cells were also compared in vitro by grafting them into organotypic slice cultures containing either tangential (embryonic cerebral cortex) or radial (early postnatal cerebellar cortex) migratory routes. Most of the grafted adult neurosphere-derived stem cells survived and integrated in vivo, and a proportion of them differentiate into neurons, oligodendrocytes or astrocytes. However, they were unable to migrate along the RMS and remained in the vicinity of the injection site. In contrast, SVZ progenitor cells were able to migrate toward the olfactory bulb and, once there, to acquire the phenotype of granule cells, as previously reported. In vitro, neural stem cells exhibited a better migratory ability, although they only migrated for short distances, particularly, in forebrain slices. Nevertheless, the average distance covered by progenitor cells was a two-fold longer than that covered by neural stem cells, corroborating that this class of more specified cells has higher migratory ability. These results suggest that the in vitro conditions of expanding SVZ-derived stem cells, required to maintain them in an immature stage might modify their intrinsic properties, preventing their differentiation into neuroblasts and their subsequent migration.

Mifepristone (RU486) protects Purkinje cells from cell death in organotypic slice cultures of postnatal rat and mouse cerebellum

Mifepristone (RU486), which binds with high affinity to both progesterone and glucocorticosteroid receptors (PR and GR), is well known for its use in the termination of unwanted pregnancy, but other activities including neuroprotection have been suggested. Cerebellar organotypic cultures from 3 to 7 postnatal day rat (P3-P7) were studied to examine the neuroprotective potential of RU486. In such cultures, Purkinje cells enter a process of apoptosis with a maximum at P3. This study shows that RU486 (20 microM) can protect Purkinje cells from this apoptotic process. The neuroprotective effect did involve neither PR nor GR, because it could not be mimicked or inhibited by other ligands of these receptors, and because it still took place in PR mutant (PR-KO) mice and in brain-specific GR mutant mice (GRNes/Cre). Potent antioxidant agents did not prevent Purkinje cells from this developmental cell death. The neuroprotective effect of RU486 could also be observed in pathological Purkinje cell death. Indeed, this steroid is able to prevent Purkinje cells from death in organotypic cultures of cerebellar slices from Purkinje cell degeneration (pcd) mutant mice, a murine model of hereditary neurodegenerative ataxia. In P0 cerebellar slices treated with RU486 for 6 days and further kept in culture up to 21 days, the synthetic steroid increased by 16.2-fold the survival of pcd/pcd Purkinje cells. Our results show that RU486 may act through a new mechanism, not yet elucidated, to protect Purkinje cells from death.

Nr-CAM and TAG-1 are expressed in distinct populations of developing precerebellar and cerebellar neurons

Nr-CAM and TAG-1 interact at the floor-plate during the formation of spinal cord commissural projections [Stoeckli, E.T., Landmesser, L.T., Sci. 274 (1995) 1123-1133; Fitzli, D., Stoeckli, E.T., Kunz, S., Siribour, K., Rader, C., Kunz, B., Kozlov, S.V., Buchstaller, A., Lane, R.P., Suter, D.M., Dreyer, W.J., Sonderegger, P., J. Cell. Biol. 149 (2000) 951-968]. We report here the spatio-temporal patterns of expression of these two adhesion molecules during the development of the lower brainstem (medulla and pons) and cerebellum. Nr-CAM and Tag-1 label distinct populations of precerebellar neurons at key steps of their development. Nr-CAM expression starts at E11.5-E12 in the floor-plate, that constitutes an intermediate target during axon outgrowth and nuclear migration of precerebellar neurons. At E13-E14, it is expressed in both floor-plate and inferior olivary nuclei (ION) neurons before being strictly restricted to ION neurons from E15 onwards. Furthermore Nr-CAM, which is widely expressed in the cerebellum during embryonic development, becomes strictly confined to Purkinje and Golgi cells in postnatal cerebellum, suggesting a possible role of Nr-CAM for the maturation or stabilization of the synaptic contacts, in particular between climbing fibers and Purkinje cells. On the other hand, Tag-1 is expressed by migrating neurons that will form the lateral reticular and basilar pontine nuclei. These results emphasize the possibility that TAG-1/Nr-CAM interactions are also involved in the development of the cerebellar system (precerebellar and cerebellar neurons). However, the pattern of cerebellar expression of TAG-1--early migrating Purkinje cells up to E14 and external granular cells--prevents the implication of this adhesion molecule in the organization of extracerebellar projections.

Axotomy does not up-regulate expression of sodium channel Na(v)1.8 in Purkinje cells

Aberrant expression of the sensory neuron specific (SNS) sodium channel Na(v)1.8 has been demonstrated in cerebellar Purkinje cells in experimental models of multiple sclerosis (MS) and in human MS. The aberrant expression of Na(v)1.8, which is normally present in primary sensory neurons but not in the CNS, may perturb cerebellar function, but the mechanisms that trigger it are not understood. Because axotomy can provoke changes in Na(v)1.8 expression in dorsal root ganglion (DRG) neurons, we tested the hypothesis that axotomy can provoke an up-regulation of Na(v)1.8 expression in Purkinje cells, using a surgical model that transects axons of Purkinje cells in lobules IIIb-VII in the rat. In situ hybridization and immunocytochemistry did not reveal an up-regulation of Na(v)1.8 mRNA or protein in axotomized Purkinje cells. Hybridization and immunostaining signals for the sodium channel Na(v)1.6 were clearly present, demonstrating that sodium channel transcripts and protein were present in experimental cerebella. These results demonstrate that axotomy does not trigger the expression of Na(v)1.8 in Purkinje cells.

Neurobiological effects of a null mutation depend on genetic context: comparison between two hotfoot alleles of the delta-2 ionotropic glutamate receptor

Hotfoot is a mutant mouse with an ataxic phenotype which has been shown to be due to a mutation in the Grid2 gene. In this paper, we compare molecular, morphological, electrophysiological and behavioral features of two Grid2 alleles: Grid2(ho-4J) and Grid2(ho-Nancy). We first show that these two mutations are deletions in the open reading frame of the gene and that no GRID2 protein is detectable in extracts of mutant cerebella, suggesting that the two alleles are null-like mutations. Morphological and electrophysiological analyses reveal no obvious differences between the two strains: both strains showed the naked Purkinje dendritic spines and mismatch between the length of the presynaptic active zone and postsynaptic differentiation characteristic of the hotfoot mutation; and the same low level (20%) of multiple climbing fiber innervation of Purkinje cells was found in both strains. Only differences in motor behavior were found between the two strains. The Grid2(ho-4J) mouse shows more severe ataxia that the Grid2(ho-Nancy) mouse and, although both strains show a clear capacity to improve their performance of a motor task with training, the Grid2(ho-4J) performance remains very poor whereas Grid2(ho-Nancy) mice approach control levels. The only difference between the two strains is their genetic background. Our results show that the genetic background must be taken into account when analyzing sensorimotor performances of mutant mice.

Neuronal promoter of human aromatic L-amino acid decarboxylase gene directs transgene expression to the adult floor plate and aminergic nuclei induced by the isthmus

In order to analyze the regulatory sequences involved in the neuronal expression of aromatic L-amino acid decarboxylase (AADC), we have generated transgenic mice carrying the LacZ gene under the control of a 3.6-kb human aadc genomic fragment flanking the neuronal alternative first exon. A series of double labeling experiments were performed to compare the pattern of transgene expression to that of specific markers for catecholaminergic and serotonergic neurons. In the adult brain parenchyma, transgene expression was observed in the substantia nigra (SN), the ventral tegmental area (VTA) and the dorsal, medial and pontine raphe nuclei. A large degree of co-expression was observed with tyrosine-hydroxylase (TH) in the SN and VTA, and with serotonin (5-HT) in the dorsal raphe nucleus. Moreover, expression was observed in cells that were both TH- and 5-HT-negative, in particular in the ventral tegmental decussation and the dorsal tip of the VTA. Transgene expression was also observed in the walls of central cavities. Cells positive for both beta-gal and PSA-NCAM were localized in the ventral ependyma of the third and fourth ventricle, and of the central canal of the spinal cord, in what appears to be the adult floor plate. Transgene expressing, PSA-NCAM negative, cells located along the ventral midline of the spinal cord seemed to have migrated out of the ependyma. Our data thus reveal the complexity of aadc gene regulation. The present transgene provides a unique marker for monoaminergic nuclei induced by the isthmus and for the adult floor plate.

Age-dependent effects of secreted Semaphorins 3A, 3F, and 3E on developing hippocampal axons: in vitro effects and phenotype of Semaphorin 3A (-/-) mice

We studied the role of Semaphorins in the formation of hippocampal connections at embryonic and early postnatal stages. We show that the embryonic entorhinal cortex has a repulsive effect on embryonic hippocampal axons that disappears gradually at postnatal stages. Such chemorepulsion is blocked by Neuropilin-1 and -2 blocking antibodies. However, at perinatal stages, the inner layers of the entorhinal cortex attract CA1 axons. At these stages, Sema3A and Sema3F bind commissural and entorhinal axons. Sema3A and Sema3F repel hippocampal axons at E14-P2, but not at E13. A similar spatiotemporal pattern of chemorepulsion is observed for Sema3A on entorhinal axons, in contrast to Sema3F, which repels these axons only at postnatal ages. Sema3E also repels hippocampal axons but exclusively at E14. We show that Sema3A and Sema3F can induce the collapse of hippocampal growth cones and that membrane-bound Sema3A and Sema3F can guide hippocampal axons in the stripe assay. In sema3A (-/-) mice, the entorhinohippocampal projection is largely normal although single axons innervate aberrantly the stratum radiatum and the hilus. Thus, the chemorepulsion evoked by Sema3A, Sema3E, and Sema3F is dynamically regulated in the developing hippocampal formation.

Diversity and specificity of actions of Slit2 proteolytic fragments in axon guidance

The Slits are secreted proteins that bind to Robo receptors and play a role in axon guidance and neuronal migration. In vertebrates, Slit2 is a major chemorepellent for developing axons and is involved in the control of midline crossing. In vivo, Slit2 is cleaved into 140 kDa N-terminal (Slit2-N) and 55-60 kDa C-terminal (Slit2-C) fragments, although the uncleaved/full-length form can also be isolated from brain extract. We explored the functional activities of Slit2 fragments by engineering mutant and truncated versions of Slit2 representing the N-, C-, and full/uncleavable (Slit2-U) fragments. Only Slit2-N and Slit2-U bind the Robo proteins. We found that in collagen gel, olfactory bulb (OB) but not dorsal root ganglia (DRG) axons are repelled by Slit2-N and Slit2-U. Moreover, only Slit2-N membranes or purified protein-induced OB growth cones collapse. Finally, we found that only recombinant Slit2-N could induce branching of DRG axons and that this effect was antagonized by Slit2-U. Therefore, different axons have distinct responses to Slit2 fragments, and these proteins have different growth-promoting capacities.

Sensory axon response to substrate-bound Slit2 is modulated by laminin and cyclic GMP

In vertebrates, Slit2 is a chemorepellent for some developing axons but stimulates axonal elongation and branching of sensory axons. In vivo, Slit2 is cleaved into 140-kDa N-terminal (Slit2-N) and 55- to 60-kDa C-terminal fragments, but the uncleaved/full-length form can also be isolated from brain extracts. As Slit2-N and full-length Slit2 bind tightly to cell membranes, we decided to explore the response of rat dorsal root ganglia (DRG) axons to substrate-bound Slit2 fragments in the stripe assay. Slit2 fragments were avoided by DRG axons when expressed on membranes or coated as stripes on laminin. However, when the Slit2 stripes were coated on fibronectin, DRG axons still avoided full-length Slit2 but grew preferentially on Slit2-N. DRG axon response to Slit2 fragments could be modulated by cGMP and by a laminin-1 peptide. These results strongly support the idea that extracellular matrix proteins modulate the response of growth cones to chemotropic molecules by modulating cyclic nucleotide levels.

Role of GAP-43 in mediating the responsiveness of cerebellar and precerebellar neurons to axotomy

To determine whether the competence for axonal sprouting and/or regeneration in the cerebellar system correlates with GAP-43 expression, we have studied GAP-43 mRNA and protein expression in the postlesioned cerebellum and inferior olive. Purkinje cells transiently express GAP-43 during their developmental phase (from E15 to P5 in the rat) which consists of fast axonal growth and the formation of the corticonuclear projection. Adult Purkinje cells, which in control adult rats do not express GAP-43, are extremely resistant to the effects of axotomy but cannot regenerate axons. However, a late and protracted sprouting of axotomized Purkinje cells occurs spontaneously and correlates with a mild expression of GAP-43 mRNA. In contrast, inferior olivary neurons, despite their high constitutive expression of GAP-43, do not sprout but retract their axons and die after axotomy. Furthermore, mature Purkinje cells in cerebellar explants of transgenic mice that overexpress GAP-43 do not regenerate after axotomy, even in the presence of a permissive substrate (cerebellar embryonic tissue) and, contrary to the case in wild-type mice, they do not survive in the in vitro conditions and undergo massive cell death. These results show that the expression of GAP-43 is not only associated with axonal growth, but also with neuronal death.

Influence of adynamic bone disease on responsiveness to recombinant human erythropoietin in peritoneal dialysis patients

Adynamic bone disease (ABD) has an increasing prevalence in the dialysis population, more so in peritoneal dialysis patients. Anemia in patients with high turnover bone disease and high intact parathyroid hormone (iPTH) tends to be resistant to recombinant human erythropoietin (rHuEPO). The same problem may occur in patients with ABD; however, data are scarce. This study evaluates the effectiveness of rHuEPO in 32 chronic peritoneal dialysis patients, 9 with iPTH levels below 100 pg/mL for more than 6 months (group A, with ABD) and 23 with iPTH levels above 100 pg/mL (group B, without ABD). In group A and group B respectively, the dosage of rHuEPO was 141.8 +/- 59 U/kg/week and 144.8 +/- 77 U/kg/week, and hematocrit was 33.2% +/- 4.3% and 31.7% +/- 4.5% (p > 0.05). Iron indices, nutritional parameters, and bone indices were similar, except that group A had lower alkaline phosphatase and serum ferritin levels. The data suggest that patients with ABD may not be resistant to rHuEPO, but may even have a slightly better hematocrit at a similar rHuEPO dosage. Further studies in a larger number of patients are needed to confirm these findings.

Evidence for intrinsic development of olfactory structures in Pax-6 mutant mice

It has been reported that the arrival of primary olfactory axons is required to induce the development of the olfactory bulb (OB). On the other hand, the Sey(Neu)/Sey(Neu) mutant mouse (Small eye) has been previously described as a model for the absence of olfactory bulbs, owing to the lack of olfactory epithelium (OE). In the present report, we take advantage of this mutant and study a neural structure in the rostral pole of the telencephalon that phenotypically resembles the prospective OB. We named this formation olfactory bulb-like structure (OBLS). We also report the occurrence, in the mutants, of small epithelial vesicles in the malformed craneofacial pits, resembling an atrophic OE, although a mature olfactory nerve was not identified. Axonal tracing, birthdating, immunohistochemistry, and in situ hybridization using antibodies and probes expressed in the olfactory system, indicated that two distinct structures observed in the OBLS correspond to the main and accessory olfactory bulbs of the control mouse. We propose that the OBLS has developed independently of the external influences exerted by the olfactory nerve. The presence of a prospective OB in the mutants, without intervening olfactory fibers, suggests that intrinsic factors could define brain territories even in absence of the proper afferent innervation. The intrinsic mechanisms and environmental cues in the telencephalon could be sufficient to promote axonogenesis in the projection neurons of the OB and guide their axons in a lateral prospective tract, in the absence of olfactory axons.

Neuronal activity and brain-derived neurotrophic factor regulate the density of inhibitory synapses in organotypic slice cultures of postnatal hippocampus

Hippocampal interneurons inhibit pyramidal neurons through the release of the neurotransmitter GABA. Given the importance of this inhibition for the proper functioning of the hippocampus, the development of inhibitory synapses must be tightly regulated. In this study, the possibility that neuronal activity and neurotrophins regulate the density of GABAergic inhibitory synapses was investigated in organotypic slice cultures taken from postnatal day 7 rats. In hippocampal slices cultured for 13 d in the presence of the GABA(A) receptor antagonist bicuculline, the density of glutamic acid decarboxylase (GAD) 65-immunoreactive terminals was increased in the CA1 area when compared with control slices. Treatment with the glutamate receptor antagonist 6,7-dinitroquinoxaline-2,3-dione decreased the density of GAD65-immunoreactive terminals in the stratum oriens of CA1. These treatments had parallel effects on the density of GABA-immunoreactive processes. Electron microscopic analysis after postembedding immunogold labeling with antibodies against GABA indicated that bicuculline treatment increased the density of inhibitory but not excitatory synapses. Application of exogenous BDNF partly mimicked the stimulatory effect of bicuculline on GAD65-immunoreactive terminals. Finally, antibodies against BDNF, but not antibodies against nerve growth factor, decrease the density of GAD65-immunoreactive terminals in bicuculline-treated slices. Thus, neuronal activity regulates the density of inhibitory synapses made by postnatal hippocampal interneurons, and BDNF could mediate part of this regulation. This regulation of the density of inhibitory synapses could represent a feedback mechanism aimed at maintaining an appropriate level of activity in the developing hippocampal networks.

Ultrastructural analysis of catecholaminergic innervation in weaver and normal mouse cerebellar cortices

The noradrenergic innervation of the mouse cerebellum, which is known for its important modulatory function, was analyzed immunocytochemically with an antibody against tyrosine hydroxylase, the rate-limiting enzyme in catecholamine biosynthesis. In control mice, the labeled afferent fibers belong to fine, beaded axons diffusely distributed throughout the cerebellar cortex. None of the 160 analyzed axon terminals established synaptic junctions with apposed neuronal elements. Thus, the cerebellar noradrenergic innervation is of the nonjunctional modality. Seventy-five percent of the labeled varicosities were apposed to dendritic profiles belonging to Purkinje, granule, stellate, and basket cells, although Purkinje cell dendrites, including spines, were the most frequently found. These observations suggest that the modulatory function of noradrenergic afferent fibers is exerted through paracrine interactions. In the agranular cerebellar cortex of the weaver mutant mouse, the density of labeled fibers is greatly increased. However, despite the presence of innumerable free postsynaptic differentiations (mainly Purkinje cell dendritic spines), only 2 of 188 observed varicosities established synaptic junctions. Thus, in the absence of granule cells, the noradrenergic innervation does not evolve from nonjunctional to junctional innervation, as was the case for the cerebellar serotonergic system (Beaudet and Sotelo [1981] Brain Res. 206:305-329). This finding indicates that the axonal remodeling in granuloprival cerebella does not affect the noradrenergic afferent system. Therefore, the authors conclude that there is some degree of specificity in the formation of heterologous synapses during the axon remodeling process occurring in all agranular cerebella.

Implication of Bcl-2 and Caspase-3 in age-related Purkinje cell death in murine organotypic culture: an in vitro model to study apoptosis

Neuronal cell death is an essential feature of nervous system development and neurodegenerative diseases. Most Purkinje cells in murine cerebellar organotypic culture die when taken from 1-5-day-old mice (P1-P5), whereas they survive when taken before or after these ages. Using DNA gel electrophoresis, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) and electron microscopic analyses, we were able to show that this massive Purkinje cell death is apoptotic in nature and reaches a peak at P3. From the several endogenous genes known to be involved in the apoptotic process, we have focused on two: the bcl-2 and the caspase-3 that encode for anti-apoptotic and pro-apoptotic proteins, respectively. Immunostaining for activated Caspase-3 correlated with Purkinje cell death. A better survival of Purkinje cells was observed in P3 slices taken from hu-bcl-2 transgenic mice, and in slices treated with z-DEVD.fmk (an inhibitor of numerous caspases). Thus, these two genes are implicated in the age-related Purkinje cell apoptosis in organotypic culture. As Purkinje cell death in vitro takes place at the same age as Purkinje cells engaged in intense synaptogenesis and dendritic remodeling in vivo, we propose that this apoptosis reflects a naturally occurring Purkinje cell death during this critical period.

Netrin 1 acts as an attractive or as a repulsive cue for distinct migrating neurons during the development of the cerebellar system

Netrin 1 is a long-range diffusible factor that exerts chemoattractive or chemorepulsive effects on developing axons growing to or away from the neural midline. Here we used tissue explants to study the action of netrin 1 in the migration of several cerebellar and precerebellar cell progenitors. We show that netrin 1 exerts a strong chemoattractive effect on migrating neurons from the embryonic lower rhombic lip at E12-E14, which give rise to precerebellar nuclei. Netrin 1 promotes the exit of postmitotic migrating neurons from the embryonic lower rhombic lip and upregulates the expression of TAG-1 in these neurons. In addition, in the presence of netrin 1, the migrating neurons are not isolated but are associated with thick fascicles of neurites, typical of the neurophilic way of migration. In contrast, the embryonic upper rhombic lip, which contains tangentially migrating granule cell progenitors, did not respond to netrin 1. Finally, in the postnatal cerebellum, netrin 1 repels both the parallel fibres and migrating granule cells growing out from explants taken from the external germinal layer. The developmental patterns of expression in vivo of netrin 1 and its receptors are consistent with the notion that netrin 1 secreted in the midline acts as chemoattractive cue for precerebellar neurons migrating circumferentially along the extramural stream. Similarly, the pattern of expression in the postnatal cerebellum suggests that netrin 1 could regulate the tangential migration of postmitotic premigratory granule cells. Thus, molecular mechanisms considered as primarily involved in axonal guidance appear also to steer neuronal cell migration.

B-lymphocyte aggregates in alveoli from a child with hypersensitivity pneumonitis (bird breeders lung)

BACKGROUND

Hypersensitivity pneumonitis is an interstitial lung disease mediated through a patient's immunologic response to a variety of inhaled organic dusts. Studies of the cellular components of lavage fluid from patients with this disease show marked increases of CD8+ suppressor/cytotoxic T-lymphocytes.

OBJECTIVE

In this study, we identified, in addition to the expected suppressor T-cells and natural killer cells, follicle-like aggregates of B-cells in the lung interstitium of an affected patient.

METHODS

The patient was an 11-year-old non-asthmatic, Caucasian male who presented with a 4-month history of progressive dyspnea, cough, and fever. The home contained nine cockatiel and two doves. Admission pulmonary functions revealed a restrictive pattern with diminished diffusion capacity. Prior to a diagnosis, the patient underwent bronchoalveolar lavage and transbronchial biopsy. Serum precipitins were eventually positive to pigeon (which cross-reacts with dove) droppings. The symptoms resolved after a prolonged course of prednisone.

RESULTS

Analysis of bronchoalveolar lavage lymphocyte population revealed a predominance of CD8+ cells (50%) with 85% expressing the activation marker HLA-DR. The percentage of CD4+ and CD56+ were 32% and 16%, respectively. The transbronchial biopsy revealed CD20+ follicle-like aggregates within the lung interstitium.

CONCLUSIONS

The histopathologic findings confirm that in hypersensitivity pneumonitis, the predominant immune response is an infiltrate of CD8+ T cells. The presence of B cell aggregates, however, may indicate that the local synthesis of antibody may be involved in an antibody-dependent cellular cytotoxic mechanism.

Late axonal sprouting of injured Purkinje cells and its temporal correlation with permissive changes in the glial scar

Purkinje cells can survive axotomy for as long as 18 months without retracting their severed axons. During this period of time, the fate of the terminal bulbs of axotomized Purkinje cell axons and their relationship with the glial scar were determined. Terminal axonal sprouting begins three months after the lesion and continuously increases up to 18 months (the longest survival time studied), when the sprouts establish synaptic contacts, mainly on granule cell dendrites at the glomeruli. Cellular changes in the glial scar were analyzed to determine whether the late onset and continuous increase of axonal sprouting could be correlated with an increase of permissive factors and/or a decrease of inhibitory factors for axonal growth. Activated macrophages disappeared much earlier than did the initiation of sprouting. Myelin and its associated neurite growth inhibitory molecules began to decrease from three months after the lesion. This decrease was uneven and not correlated spatially with the sprouting. Reactive astrogliosis was heterogeneous: only some of the reactive astrocytes expressed PSA-NCAM, the embryonic form of the neural cell adhesion molecule, a permissive substratum for neurite outgrowth. The expression of PSA-NCAM occurred concurrently with sprouting in the area of gliosis containing Purkinje cell sprouts. Moreover, the ultrastructural study showed that the majority of sprouts (75%) were totally ensheathed by astrocytic processes. Thus, long-term glial scars are permissive to axonal sprouting, suggesting that reactive astrocytes, either through the expression of permissive molecules or by preventing direct contact between axonal elements and myelin inhibitory molecules, regulate the sprouting.

Chemoattraction and chemorepulsion of olfactory bulb axons by different secreted semaphorins

During development, growth cones can be guided at a distance by diffusible factors, which are attractants and/or repellents. The semaphorins are the largest family of repulsive axon guidance molecules. Secreted semaphorins bind neuropilin receptors and repel sensory, sympathetic, motor, and forebrain axons. We found that in rat embryos, the olfactory epithelium releases a diffusible factor that repels olfactory bulb axons. In addition, Sema A and Sema IV, but not Sema III, Sema E, or Sema H, are able to orient in vitro the growth of olfactory bulb axons; Sema IV has a strong repulsive action, whereas Sema A appears to attract those axons. The expression patterns of sema A and sema IV in the developing olfactory system confirm that they may play a cooperative role in the formation of the lateral olfactory tract. This also represents a further evidence for a chemoattractive function of secreted semaphorins.

Floor plate and netrin-1 are involved in the migration and survival of inferior olivary neurons

During their circumferential migration, the nuclei of inferior olivary neurons translocate within their axons until they reach the floor plate where they stop, although their axons have already crossed the midline to project to the contralateral cerebellum. Signals released by the floor plate, including netrin-1, have been implicated in promoting axonal growth and chemoattraction during axonal pathfinding in different midline crossing systems. In the present study, we report experiments that strongly suggest that the floor plate could also be involved in the migration of inferior olivary neurons. First, we show that the pattern of expression of netrin receptors DCC (for deleted in colorectal cancer), neogenin (a DCC-related protein), and members of the Unc5 family in wild-type mice is consistent with a possible role of netrins in directing the migration of precerebellar neurons from the rhombic lips. Second, we have studied mice deficient in netrin-1 production. In these mice, the number of inferior olivary neurons is remarkably decreased. Some of them are located ectopically along the migration stream, whereas the others are located medioventrally and form an atrophic inferior olivary complex: most subnuclei are missing. However, axons of the remaining olivary cell bodies located in the vicinity of the floor plate still succeed in entering their target, the cerebellum, but they establish an ipsilateral projection instead of the normal contralateral projection. In vitro experiments involving ablations of the midline show a fusion of the two olivary masses normally located on either side of the ventral midline, suggesting that the floor plate may function as a specific stop signal for inferior olivary neurons. These results establish a requirement for netrin-1 in the migration of inferior olivary neurons and suggest that it may function as a specific guidance cue for the initial steps of the migration from the rhombic lips and then later in the development of the normal crossed projection of the inferior olivary neurons. They also establish a requirement for netrin-1, either directly or indirectly, for the survival of inferior olivary neurons.

Cyclosphosphamide/prednisone for combination immunosuppression and therapy of lymphoproliferative disease

Post-transplant lymphoproliferative disease (PTLD) is a well-known complication of solid organ transplantation. While this disorder can often be controlled by decreasing immunosuppression, it is frequently difficult to control the resultant rejection. This case exemplifies this dilemma. To solve this problem, cyclosphosphamide (600 mg/m2) and prednisone (2 mg/kg times 5 days) were given every 3 weeks to simultaneously treat PTLD and provide immunosuppression.

An ultrastructural study of granule cell/Purkinje cell synapses in tottering (tg/tg), leaner (tg(la)/tg(la)) and compound heterozygous tottering/leaner (tg/tg(la)) mice

Homozygous tottering (tg/tg) and compound heterozygous tottering/leaner (tg/tg(la)) mutant mice exhibit juvenile onset of three abnormal neurological phenotypes: (i) petit mal-like epilepsy; (ii) ataxia; and (iii) an intermittent myoclonus-like movement disorder. Homozygous leaner mice (tg(la)/tg(la)) exhibit early onset of ataxia (postnatal days 10-12), and also exhibit the myoclonus-like movement disorder and evidence of absence seizure activity; the myoclonus-like disorder is most evident in the first month of life, then diminishes in severity and frequency. The ultrastructure of the cerebellar molecular layer was examined in adult (six to eight months) and juvenile (20-25 days) mice of all three mutant genotypes. In mice of all three genotypes and both ages, Purkinje cell dendritic spines were observed to make multiple contacts with individual parallel fiber varicosities in all sections analysed. These multiple synaptic units were observed in both anterior and posterior vermis and hemispheres of the cerebellum, and ranged from two to nine spines/parallel fiber varicosity. Occasionally, one of the postsynaptic spines belonged to an ectopic spine emerging from the proximal region of a Purkinje cell dendrite. This increase in the multiple synaptic index of some parallel fiber varicosities was observed in juvenile tottering mice before the onset of the symptoms of the neurological disorders. This is highly suggestive that the onset of the neurological phenotype is not a primary cause of multiple Purkinje cell dendritic spines synapsing with single parallel fiber varicosities in these mice, but on the contrary, that it could be the cause of the ataxic symptoms.

Slit2-Mediated chemorepulsion and collapse of developing forebrain axons

Diffusible chemorepellents play a major role in guiding developing axons toward their correct targets by preventing them from entering or steering them away from certain regions. Genetic studies in Drosophila revealed a novel repulsive guidance system that prevents inappropriate axons from crossing the CNS midline; this repulsive system is mediated by the Roundabout (Robo) receptor and its secreted ligand Slit. In rodents, Robo and Slit are expressed in the spinal cord and Slit can repel spinal motor axons in vitro. Here, we extend these findings into higher brain centers by showing that Robo1 and Robo2, as well as Slit1 and Slit2, are often expressed in complementary patterns in the developing forebrain. Furthermore, we show that human Slit2 can repel olfactory and hippocampal axons and collapse their growth cones.

Proliferation, migration and differentiation of neuronal progenitor cells in the adult mouse subventricular zone surgically separated from its olfactory bulb

The subventricular zone of the adult mammalian forebrain contains progenitor cells that, by migrating along a restricted pathway called the 'rostral migratory stream' (RMS), add new neurons to the olfactory bulb throughout life. To determine the influence of the olfactory bulb on the development of these progenitor cells, we performed lesions that interrupt this pathway and separate the olfactory bulb from the rest of the forebrain. By labelling cells born at several survival times after the lesions with the thymidine analogue bromodeoxyuridine (BrdU), we found that disconnection from the bulb influences the rate of BrdU incorporation by the progenitor cells. The number of labelled cells in lesioned mice was almost half that found in control mice. In the disconnected migratory pathway, the number of neurons expressing calretinin was increased indicating that neuronal differentiation was enhanced: newly born neurons occurred within and around the RMS, most of them expressed calretinin and left the pathway starting about 2 weeks after the lesion. Thereafter, these neurons preserving their phenotype, spread for long distances, and accumulated ectopically in dorsal regions of the anterior olfactory nucleus and the frontal cortex. Finally, transplantation of adult subventricular cells into the lesioned pathway showed that the lesion neither prevents neuronal migration nor alters its direction. Thus, although the olfactory bulb appears to regulate the pace of the developmental processes, its disconnection does not prevent the proliferation, migration and phenotypic acquisition of newly generated bulbar interneurons that, since they cannot reach their terminal domains, populate some precise regions of the lesioned adult forebrain.