Frequency of BRAF V600E immunoexpression in ameloblastomas: a multi-institutional analysis of 86 cases in Latin America and comprehensive review of the literature.

BACKGROUND: Paracoccidioidomycosis (PCM) is the leading cause of death among systemic mycoses in Brazil. On the other hand, oral squamous cell carcinoma (OSCC) is the most prevalent malignant neoplasm of the mouth. Both lesions rarely affect the tongue dorsum and may share similar clinical characteristics. This study aimed to retrieve cases of single oral ulcers diagnosed as PCM or OSCC. MATERIAL AND METHODS: A cross-sectional retrospective study was conducted. All patients who had a single ulcer on dorsum of the tongue and confirmed diagnosis of PCM or OSCC were evaluated. RESULTS: A total of 9 patients (5 women and 4 men) were evaluated, 5 patients had OSCCs (mean age = 69,8 years old), and 4 patients PCM (mean age = 51 years old). Most of the lesions were infiltrated and indurated in the palpation exam. Duration ranged from 1 to 12 months (mean time of 5.2 months and 4.7 months for OSCC and PCM, respectively). OSCC was the main clinical diagnosis hypothesis. CONCLUSIONS: Although uncommon, PCM and OSCC should be considered as a differential diagnosis hypothesis in infiltrated ulcers on the tongue dorsum. Incisional biopsy is mandatory to confirm the diagnosis and indicate the appropriate treatment.

Ep-CAM (MOC-31) expression in tooth germ and ameloblastoma.

BACKGROUND: Ep-CAM, a transmembrane glycoprotein expressed in most epithelium in normal conditions, has diverse roles in these tissues, including in cell adhesion, proliferation, differentiation, cell cycle regulation, migration and intracellular signaling. It is also over-expressed in most malignant neoplasia, participating in the initiation, progression, and metastatic dissemination of the tumor. The expression and roles of this protein in oral neoplasia, particularly in odontogenic tumors, remain unestablished. The objective of this study consisted in analyzing the expression of this protein in ameloblastoma and tooth germ. MATERIAL AND METHODS: Ep-CAM (MOC-31) expression was evaluated by immunohistochemistry in tooth germs (TG) (n = 16) ameloblastomas (AM) (n = 60) and 2 ameloblastic carcinomas. Sections were visualized in their totality with an optical microscope, and positivity observed in cell membrane and cytoplasm was graded according to the following semi-quantitative scale: Neg, "essentially unstained", for negative sections or staining <5% of cells; + for staining of 5-50% of cells; ++ for staining >50% of cells. RESULTS: Most tooth germs expressed MOC-31 (81.3%), strong staining was observed both in the inner epithelium of the enamel organ and in the adjacent stellate reticulum. 16.7% of the AM cases showed MOC-31 expression, the immunoexpression expression was diffuse at the cytoplasmic and membrane level. The only two cases of ameloblastic carcinoma included were strong positive to MOC-31. No correlation was observed between protein expression and gender, age, clinical variants, or histological subtypes. CONCLUSIONS: Overexpression was found in TG and ameloblastic carcinoma compared to AM; further studies with different experimental strategies are suggested to clarify the biological significance of this finding.

Expression of caveolin-1 in tooth germ, ameloblastoma and ameloblastic carcinoma.

BACKGROUND: The caveolin-1 protein (structural component of membrane caveolae) plays important roles in several biological functions, such as endocytosis, cell adhesion, and cell signaling. However, this protein has been associated with mechanisms of tumorigenesis in several neoplasms. The expression patterns and roles of caveolin-1 in the oral epithelium and in embryonic and odontogenic tumor tissues are still unclear. MATERIAL AND METHODS: The expression of caveolin-1 was evaluated in samples of the normal gingival epithelium (n=7), human tooth germ (TG) (n=12), ameloblastoma (AM) (n=83), and ameloblastic carcinoma (AC) (n=9) by immunohistochemistry. Additionally, AM samples were analyzed by qRT-PCR and Western blot. RESULTS: Most TG (91.7%), AM (73.5%) and AC (100%) samples showed diverse patterns of immunohistochemical positivity for caveolin-1, while only one gingival sample was positive. The transcript levels of cav-1 were significantly upregulated by 14.9-fold in AM tissue (P = 0.0014) compared to those in normal gingival epithelial tissue, as shown by qRT-PCR. Presence of caveolin-1 protein was confirmed by Western blot analysis. The caveolin-1 immunoexpression patterns throughout the stages of TG show its importance during odontogenesis. CONCLUSIONS: The overexpression of caveolin-1 in AM and AC compared to its expression in normal gingival epithelium (adult tissue) suggests a possible role of caveolin-1 in protumoral events, but due to the similar immunoexpression observed in AM and AC, caveolin-1 may not necessarily participate in the malignant transformation process. However, future studies are needed to clarify and confirm these hypotheses.

Immunoexpression of galectin-3 and its potential relation to hypoxia-inducible factor-1α in ameloblastomas.

In tumor biology, hypoxia triggers signaling pathways that induce transcription of genes related to angiogenesis, metastasis, glucose metabolism and apoptosis. We investigated the expression of hypoxia related proteins, galectin-3 (Gal-3) and hypoxia-inducible factor-1α (HIF-1α), in conventional (CA) and unicystic ameloblastomas (UA). We applied immunohistochemistry for Gal-3 and HIF-1α to 72 cases of ameloblastoma: 59 cases of CA and 13 cases of unicystic UA. Immunoexpression was evaluated semiquantitatively. Gal-3 expression was observed in 40% of the cases: 23/59 CA and 6/13 UA. HIF-1α immunostaining was observed in 55% of cases: 36/59 CA and 4/13 UA. 19 CA and 2 UA were positive for both markers. Immunostaining was evident in the center of the tumor islands, which exhibited squamous metaplasia or cystic degeneration. The expression of Gal-3 and HIF-1α in ameloblastomas could be interpreted as a response to hypoxic stress. Co-expression of both proteins in CA may suggest a potential interaction that participates in the biological behavior of this ameloblastoma variant.

Primordial odontogenic tumor: A systematic review.

BACKGROUND: The primordial odontogenic tumor (POT) is a recently described benign entity with histopathological and immunohistochemical features suggesting its origin during early odontogenesis. AIM: To integrate the available data published on POT into a comprehensive analysis to better define its clinicopathological and molecular features. MATERIAL AND METHODS: An electronic systematic review was performed up to September 2019 in multiple databases. RESULTS: A total of 13 publications were included, representing 16 reported cases and 3 molecular studies. The mean age of the affected patients was 11.6 years (range 2-19), with a slight predominance in males (56.25%). The posterior mandible was the main location (87.5%), with only two cases affecting the posterior maxilla. All cases appeared as a radiolucent lesion in close relationship to an unerupted tooth. Recurrences have not been reported to date. Microscopically, POT comprises fibromyxoid tissue with variable cellularity surrounded by a cuboidal to columnar odontogenic epithelium but without unequivocal dental hard tissue formation. A delicate fibrous capsule surrounds (at least partially) the tumor. The epithelial component shows immunohistochemical positivity for amelogenin, CK19, and CK14, and variable expression of Glut-1, Galectin-3 and Caveolin-1, Vimentin, p-53, PITX2, Bcl-2, Bax and Survivin; the mesenchymal tissue is positive for Vimentin, CD90, p-53, PITX2, Bcl-2, Bax, and Survivin, and the subepithelial region exhibits the strong expression of Syndecan-1 and CD34. The Ki-67 index is low (<5%). The negative or weak expression of dentinogenesis-associated genes could explain the inhibition of dentin and subsequent enamel formation in this neoplasm. CONCLUSION: POT is an entity with a well-defined clinicopathological, immunohistochemical and molecular profile that must be properly diagnosed and differentiated from other odontogenic lesions and treated consequently.

Expression of hMLH1 and hMSH2 proteins in ameloblastomas and tooth germs.

BACKGROUND: Mismatch repair proteins (MMRPs) are a group of nuclear enzymes that participate in the repair of base mismatches that occur during DNA replication in all proliferating cells. The most studied MMRPs are hMSH2 and hMLH1, which are known to be highly expressed in normal tissues. A loss of MMRPs leads to the accumulation of DNA replication errors in proliferating cells. Ki-67 is a biomarker regarded to be the gold-standard tool for determining cell proliferation by immunohistochemical methods. The aim of this study was to investigate the immunohistochemical expression of hMLH1, hMSH2 and Ki-67 proteins in ameloblastomas and tooth germs, to contribute to the understanding of the development of this odontogenic neoplasm. MATERIAL AND METHODS: Immunohistochemical assays to determine the presence of proteins hMSH2, hMLH1 and Ki-67 were performed in 80 ameloblastomas (40 solid and 40 unicystic) and five tooth germs. RESULTS: Unicystic ameloblastomas showed higher MMRP expression (hMLH1: 62.5 ± 43.4; hMSH2: 83.3 ± 47.8) than did solid ameloblastomas (hMLH1: 59.4 ± 13.5; hMSH2: 75.8 ± 40.2). Additionally, the cell proliferation index assessed by Ki-67 was inversely proportional to the expression of MMRP. Comparison between tooth germs and ameloblastoma revealed significantly higher expression of hMLH1, hMSH2 and Ki-67 in tooth germs (p=0.02). CONCLUSIONS: The differences of MMRP and Ki-67 immunoexpression between ameloblastomas and tooth germ suggest that alterations in the MMRP mechanisms could participate in the biological behavior of ameloblastomas.

Primordial odontogenic tumor: Subepithelial expression of Syndecan-1 and Ki-67 suggests origin during early odontogenesis.

Primordial odontogenic tumor (POT) is composed of variably cellular myxoid connective tissue, surrounded by cuboidal to columnar odontogenic epithelium resembling the inner epithelium of the enamel organ, which often invaginates into the underlying connective tissue. The tumor is delimited at least partially by a thin fibrous capsule. It derives from the early stages of tooth development. Syndecan-1 is a heparan sulfate proteoglycan that has a physiological role in several cellular functions, including maintenance of the epithelial architecture, cell-to-cell adhesion and interaction of cells with extracellular matrix, and with diverse growth factors, stimulating cell proliferation. Ki-67 is considered the gold standard as a cell proliferation marker. The aim of this study was to examine the expression of Syndecan-1 and Ki-67 proliferation index in POT and normal tooth germs to better understand the biological behavior of this tumor. Results showed that Syndecan-1 was more intensely expressed in subepithelial mesenchymal areas of POT, in a pattern that resembles the early stages of tooth development. The cell proliferation index (4.1%) suggests that POT is a slow growing tumor. Syndecan-1 expression in tooth germs in late cap and early bell stages was similar to POT, showing immunopositivity in subepithelial mesenchymal condensed areas. The immunohistochemical findings showed a pattern in which the population of subepithelial mesenchymal cells exhibited greater proliferative activity than the central portion of the dental papilla.

Primordial odontogenic tumor: An immunohistochemical profile.

BACKGROUND: Primordial Odontogenic Tumor (POT) is a recently described odontogenic tumor characterized by a variably cellular loose fibrous tissue with areas similar to the dental papilla, covered by cuboidal to columnar epithelium that resembles the internal epithelium of the enamel organ, surrounded at least partly by a delicate fibrous capsule. The purpose of this study was to investigate the possible histogenesis and biological behavior of this rare tumor by means of a wide immunohistochemical analysis of its epithelial and mesenchymal components. MATERIAL AND METHODS: The immunoexpression of twenty-three different antibodies were evaluated in four cases of POT. RESULTS: The epithelial cells that cover the periphery of the tumor showed immunopositivity for Cytokeratins 14 and 19, while Amelogenin, Glut-1, MOC-31, Caveolin-1. Galectin-3, PITX2, p53, Bax, Bcl-2, Survivin and PTEN were variably expressed in focal areas. The mesenchymal component of the tumor was positive for Vimentin, Syndecan-1, PITX2, Endoglin (CD105), CD 34, Cyclin D1, Bax, Bcl-2, Survivin and p53. PTEN and CD 90 showed a moderate positivity. BRAF V600E and Calretinin were negative in all samples. Cell proliferation markers (Ki-67, MCM-7) were expressed in <5% of the tumor cells. CONCLUSIONS: According to these immunohistochemical findings, we may conclude that POT is a benign odontogenic tumor in which there is both epithelial and mesenchymal activity during its histogenesis, as there is expression of certain components in particular zones in both tissues that suggests this tumor develops during the immature (primordial) stage of tooth development, leading to its inclusion within the group of benign mixed epithelial and mesenchymal odontogenic tumours in the current World Health Organization classification of these lesions.

The absence of VGLUT3 predisposes to cocaine abuse by increasing dopamine and glutamate signaling in the nucleus accumbens.

Tonically active cholinergic interneurons (TANs) from the nucleus accumbens (NAc) are centrally involved in reward behavior. TANs express a vesicular glutamate transporter referred to as VGLUT3 and thus use both acetylcholine and glutamate as neurotransmitters. The respective roles of each transmitter in the regulation of reward and addiction are still unknown. In this study, we showed that disruption of the gene that encodes VGLUT3 (Slc17a8) markedly increased cocaine self-administration in mice. Concomitantly, the amount of dopamine (DA) release was strongly augmented in the NAc of VGLUT3(-/-) mice because of a lack of signaling by metabotropic glutamate receptors. Furthermore, dendritic spines and glutamatergic synaptic transmission on medium spiny neurons were increased in the NAc of VGLUT3(-/-) mice. Increased DA and glutamate signaling in the NAc are hallmarks of addiction. Our study shows that TANs use glutamate to reduce DA release and decrease reinforcing properties of cocaine in mice. Interestingly, we also observed an increased frequency of rare variations in SLC17A8 in a cohort of severe drug abusers compared with controls. Our findings identify VGLUT3 as an unexpected regulator of drug abuse.

Sleep pattern and learning in knockdown mice with reduced cholinergic neurotransmission.

Impaired cholinergic neurotransmission can affect memory formation and influence sleep-wake cycles (SWC). In the present study, we describe the SWC in mice with a deficient vesicular acetylcholine transporter (VAChT) system, previously characterized as presenting reduced acetylcholine release and cognitive and behavioral dysfunctions. Continuous, chronic ECoG and EMG recordings were used to evaluate the SWC pattern during light and dark phases in VAChT knockdown heterozygous (VAChT-KDHET, n=7) and wild-type (WT, n=7) mice. SWC were evaluated for sleep efficiency, total amount and mean duration of slow-wave, intermediate and paradoxical sleep, as well as the number of awakenings from sleep. After recording SWC, contextual fear-conditioning tests were used as an acetylcholine-dependent learning paradigm. The results showed that sleep efficiency in VAChT-KDHET animals was similar to that of WT mice, but that the SWC was more fragmented. Fragmentation was characterized by an increase in the number of awakenings, mainly during intermediate sleep. VAChT-KDHET animals performed poorly in the contextual fear-conditioning paradigm (mean freezing time: 34.4±3.1 and 44.5±3.3 s for WT and VAChT-KDHET animals, respectively), which was followed by a 45% reduction in the number of paradoxical sleep episodes after the training session. Taken together, the results show that reduced cholinergic transmission led to sleep fragmentation and learning impairment. We discuss the results on the basis of cholinergic plasticity and its relevance to sleep homeostasis. We suggest that VAChT-KDHET mice could be a useful model to test cholinergic drugs used to treat sleep dysfunction in neurodegenerative disorders.

Sleep pattern and learning in knockdown mice with reduced cholinergic neurotransmission

Impaired cholinergic neurotransmission can affect memory formation and influence sleep-wake cycles (SWC). In the present study, we describe the SWC in mice with a deficient vesicular acetylcholine transporter (VAChT) system, previously characterized as presenting reduced acetylcholine release and cognitive and behavioral dysfunctions. Continuous, chronic ECoG and EMG recordings were used to evaluate the SWC pattern during light and dark phases in VAChT knockdown heterozygous (VAChT-KDHET, n=7) and wild-type (WT, n=7) mice. SWC were evaluated for sleep efficiency, total amount and mean duration of slow-wave, intermediate and paradoxical sleep, as well as the number of awakenings from sleep. After recording SWC, contextual fear-conditioning tests were used as an acetylcholine-dependent learning paradigm. The results showed that sleep efficiency in VAChT-KDHET animals was similar to that of WT mice, but that the SWC was more fragmented. Fragmentation was characterized by an increase in the number of awakenings, mainly during intermediate sleep. VAChT-KDHET animals performed poorly in the contextual fear-conditioning paradigm (mean freezing time: 34.4±3.1 and 44.5±3.3 s for WT and VAChT-KDHET animals, respectively), which was followed by a 45% reduction in the number of paradoxical sleep episodes after the training session. Taken together, the results show that reduced cholinergic transmission led to sleep fragmentation and learning impairment. We discuss the results on the basis of cholinergic plasticity and its relevance to sleep homeostasis. We suggest that VAChT-KDHET mice could be a useful model to test cholinergic drugs used to treat sleep dysfunction in neurodegenerative disorders.

Vivienda social accesible: evaluación de costos / Accessible social home: cost evaluation

Introduction: Physical accessibility is considered a fundamental part in the exercise of rights and the development of independent living for people with a disability. One of the most important spaces where accessibility should be considered is the home. Accessibility is presumably associated to high construction cost therefore social homes do not incorporate this criteria. An evaluation is needed to verify this presumption. Objective: To evaluate the economic impact of incorporating physical accessibility in basic housing solutions, or type Solidarity Fund 1 (FSV1) homes. Method: Cost evaluation was performed on the basis of an academic comparison of direct construction cost of 15 built social homes (FSV1), versus 15 counterproposals with incorporated accessibility. Results: 13 of 15 cases increased costs between 1.27 percent and 6.11 percent of the basic construction cost. However, the unitary cost per constructed square meter did not increase. Conclusion: Limited cost variations was associated more to the surface increase needed to generate accessibility conditions, than to the incorporation of new elements o technical aids.

Introducción: La accesibilidad física es considerada como parte fundamental para el ejercicio de los derechos y el desarrollo de una vida independiente de las personas en situación de discapacidad. Uno de los espacios más importantes que debiera considerar accesibilidad es la vivienda, especialmente la vivienda social, siendo uno de los principales impedimentos a la hora de incorporar este criterio, el supuesto alto costo asociado; sin embargo, no existen evaluaciones que lo puedan objetivar. Objetivo: Evaluar el impacto económico que tendría incorporar accesibilidad física en soluciones habitacionales más básicas o tipo Fondo Solidario de Vivienda I (FSV1). Materiales y Método: La evaluación de costos se realizó sobre la base de un ejercicio académico de comparación de costos directos de construcción de 15 casos de viviendas sociales construidas (FSV1) con 15 contrapropuestas con accesibilidad incorporada. Resultados: Trece de 15 casos aumentaron sus costos de construcción, entre 1,27 por ciento y 6,11 por ciento del costo base de la vivienda construida. Sin embargo, el costo unitario por metro cuadrado construido no presenta incremento. Conclusiones: Las variaciones de costo fueron bastante acotadas y estuvieron relacionadas con el aumento de superficie necesario para generar condiciones de accesibilidad, más que en la incorporación de nuevos elementos o ayudas técnicas.

Vivienda social accesible: un nuevo desafío para Chile / Accessible social homes: a new challenge for Chile

Introduction: Since 2004, Teleton´s Volunteer Corp through their Program“Abre” is working to eliminate architectural barriers in the homes of rehabilitation services users. Most of these homes are obtained by the families through State financial aid. This on site work has shown low levels of accessibility, thus a full and autonomous use of the home is restricted. Objective: To establish design criteria for social homes from the Solidary Fund 1 (FSV1), regarding unnoticed accessibility characteristics. Method: Sample gathering was obtained with the collaboration of the Housing and Town Planning Ministry (MINVU). Regions with greatest concentration of granted subsidies from FSV1 during the year 2011 were selected. Based on 15 counterproposals, the concept of unnoticed accessibility was implemented in the homes. Design criteria complied with current FSV1regulations. Results: The design process resulted in 15 cases of social homes with different degrees of accessibility. Discussion: The objective of this study allowed the accomplishment of accessibility solutions for social homes from FSV1, with marginal built surface increase. As a second gain, they allowed for the design of construction plants, which improve housing conditions for families, throughout their entire life cycle independent of health conditions. Conclusions: Accessible social home proposals were implemented with marginal increase.

Introducción: Desde el año 2004 el programa Abre del Voluntariado Teletón trabaja a través de la eliminación de barreras arquitectónicas en las viviendas de familias usuarias de Teletón, que en su mayoría acceden a viviendas sociales obtenidas mediante subsidios estatales. Esta realidad en terreno ha permitido visualizarlos bajos niveles de accesibilidad que estas viviendas poseen, dificultando el acceso, uso pleno y autónomo de los recintos. Objetivo: Establecer criterios de diseño que permitan que las viviendas sociales del fondo solidario 1 (FSV1) posean características de accesibilidad desapercibida. Material y Método: La recopilación de la muestra de tipos de vivienda social se realizó en colaboración con el Ministerio de Vivienda y Urbanismo (MINVU), trabajando con las Regiones de mayor concentración de subsidios del FSV1 asignados durante el año 2011.Se desarrollaron 15 contrapropuestas en las cuales se implementó el concepto de accesibilidad desapercibida. Los criterios de diseño se enmarcaron en el reglamento actual del FSV1. Resultados: El proceso de diseño culminó con la obtención de 15 casos de viviendas sociales con distintos grados de accesibilidad. Discusión: Desde los objetivos propuestos en este estudio, se ha podido brindar soluciones de accesibilidad para las viviendas sociales del FSV1, sin que ello implicase un aumento considerable de la superficie construida. De igual manera, se han podido diseñar plantas de edificación que permiten mejorar las condiciones de habitabilidad, independiente de la condición de salud del grupo familiar en todo su ciclo de vida. Conclusiones: Las propuestas de vivienda social accesible se lograron con un aumento marginal de superficie.

Expression of a recombinant Phoneutria toxin active in calcium channels.

PnTx3-4 is a toxin isolated from the venom of the spider Phoneutria nigriventer that blocks N-, P/Q-, and R-type voltage-gated calcium channels and has great potential for clinical applications. In this report we used the SUMO system to express large amounts of recombinant PnTx3-4 peptide, which was found in both soluble and insoluble fractions of bacterial extracts. We purified the recombinant toxin from both fractions and showed that the recombinant peptide showed biological activity similar to the native PnTx3-4. In silico analysis of the primary sequence of PnTx3-4 indicated that the peptide conforms to all the criteria of a knottin scaffold. Additionally, circular dichroism spectrum analysis of the recombinant PnTx3-4 predicted that the toxin structure is composed of approximately 53% turns/unordered, 31% α-helix and 16% ß-strand, which is consistent with predicted model of the PnTx3-4 knottin scaffold available at the knottin database (http://knottin.cbs.cnrs.fr). These studies provide the basis for future large scale production and structure-function investigation of PnTx3-4.

Avaliação do atendimento pelo programa Aprendendo com Saúde na Coordenadoria Regional de Saúde Sul da Secretaria Municipal de Saúde de São Paulo

O Programa Aprendendo com Saúde (APD) têm como objetivo a promoção, prevenção e a assistência à saúde do escolar, sendo normatizado em setembro de 2007 com o objetivo de ampliar e aperfeiçoar o Programa Municipal de Atenção á Saúde do Escolar

Avaliação do atendimento pelo programa Aprendendo com Saúde na Coordenadoria Regional de Saúde Sul da Secretaria Municipal de Saúde de São Paulo / Evaluation of the program by learning from the Health Regional Health South Municipal Health Secretariat of Sao Paulo

O Programa Aprendendo com Saúde (APD) têm como objetivo a promoção, prevenção e a assistência à saúde do escolar, sendo normatizado em setembro de 2007 com o objetivo de ampliar e aperfeiçoar o Programa Municipal de Atenção á Saúde do Escolar(AU)

Avaliação do atendimento pelo programa aprendendo com saúde na coordenadoria regional de saúde sul da secretaria municipal de saúde de São Paulo / Evaluation of the program by learning from the health regional health south municipal health secretariat of Sao Paulo

O Programa Aprendendo com Saúde (APD) têm como objetivo a promoção, prevenção e a assistência à saúde do escolar, sendo normatizado em setembro de 2007 com o objetivo de ampliar e aperfeiçoar o Programa Municipal de Atenção á Saúde do Escolar.

VAChT knock-down mice show normal prepulse inhibition but disrupted long-term habituation.

The neurotransmitter acetylcholine (ACh) plays a crucial role in both the central and peripheral nervous system. Central cholinergic transmission is important for cognitive functions and cholinergic disruptions have been associated with different neural disorders. We here tested the role of cholinergic transmission in basic cognitive functions, i.e. in prepulse inhibition (PPI) and short-term habituation (STH) as well as long-term habituation (LTH) of startle using mice with a 65% knockdown (KD) of the vesicular ACh transporter (VAChT). These mice are slow in refilling cholinergic synaptic transmitter vesicles, leading to a reduced cholinergic tone. Prepulse inhibition has been assumed to be mediated by cholinergic projections from the midbrain to the reticular formation. Surprisingly, PPI and STH were normal in these mice, whereas LTH was disrupted. This disruption could be rescued by pre-testing injections of the ACh esterase inhibitor galantamine, but not by post-testing injections. The lack of a PPI deficit might be because of the fact that VAChT KD mice show disruptions mainly in prolonged cholinergic activity, therefore the transient activation by prepulse processing might not be sufficient to deplete synaptic vesicles. The disruption of LTH indicates that the latter depends on a tonic cholinergic inhibition. Future experiments will address which cholinergic cell group is responsible for this effect.

Reduced expression of the vesicular acetylcholine transporter causes learning deficits in mice.

Storage of acetylcholine in synaptic vesicles plays a key role in maintaining cholinergic function. Here we used mice with a targeted mutation in the vesicular acetylcholine transporter (VAChT) gene that reduces transporter expression by 40% to investigate cognitive processing under conditions of VAChT deficiency. Motor skill learning in the rotarod revealed that VAChT mutant mice were slower to learn this task, but once they reached maximum performance they were indistinguishable from wild-type mice. Interestingly, motor skill performance maintenance after 10 days was unaffected in these mutant mice. We also tested whether reduced VAChT levels affected learning in an object recognition memory task. We found that VAChT mutant mice presented a deficit in memory encoding necessary for the temporal order version of the object recognition memory, but showed no alteration in spatial working memory, or spatial memory in general when tested in the Morris water maze test. The memory deficit in object recognition memory observed in VAChT mutant mice could be reversed by cholinesterase inhibitors, suggesting that learning deficits caused by reduced VAChT expression can be ameliorated by restoring ACh levels in the synapse. These data indicate an important role for cholinergic tone in motor learning and object recognition memory.

Distribution of putative adhesins in Shiga toxin-producing Escherichia coli (STEC) strains isolated from different sources in Chile.

The distribution of three putative adhesin genes in 123 Shiga toxin-producing (STEC) strains was determined by PCR. The STEC strains were isolated from human patients (n=90) and food (n=33) and were characterized by serogroup, virulence markers (eae, stx(1), stx(2)) and adherence factors (efa1, lpfA(O157), saa) genes. Serogroups O157 (64.4%) and O26 (28.8%) were the most frequent among human strains and the majority (60.6%) of food strains were serologically non-typable. The adhesin genes efa1 (90%) and lpfA(O157) (73.3%) were the most common in humans strains and saa (45.5%) in food strains. The presence of these genes in addition to eae in STEC from different sources may suggest a relevant role in their pathogenesis.