Apicotomy: a root apical fracture for surgical treatment of impacted upper canines

Impacted canines, due to systemic or local factors, represent a frequent problem in most populations. Surgical intervention usually involves exposure for spontaneous eruption, exposure for orthodontic traction or extraction. The author presents the apicotomy technique, which has been successfully used during the past twenty years for conservative intervention in cases of impacted upper canines with dilaceration or apical root-ankylosis. This original method involves surgical fracture of the root apex, followed by orthodontic traction of the corono-radicular region

Analysis of weed community changes and their determining factors in no-tillage systems

El sistema de siembra directa implica el uso conjunto de una serie de prácticas de manejo que determinan cambios adaptativos en la comunidad de malezas. Distintos sistemas de laboreo del suelo generan diferentes condiciones de luz, temperatura y humedad suficientes para alterar la emergencia y establecimiento de numerosas especies de malezas. El sistema de siembra directa requiere un empleo diferente de herbicidas y puede disminuir la eficiencia de los mismos. Estos cambios en el control químico pueden contribuir a explicar modificaciones en la composición de la flora. El impacto de los sistemas de siembra directa varía marcadamente según regiones y especies de malezas consideradas y en Argentina en particular, la información sobre el comportamiento de las comunidades de malezas en distintos sistemas de labranza es reducida. Si bien esta revisión está centrada en las principales prácticas agrícolas y especies de malezas comunes en la pampa húmeda argentina, debido a la falta de información específica en muchos aspectos, se ha recurrido también a investigaciones relevantes en otras áreas. La siembra directa contínua conduce en la mayoría de los casos revisados a reducciones en la abundancia de muchas malezas latifoliadas anuales en el largo plazo. La excepción son las especies cuyos propágulos son transportados por el viento. Las poblaciones de gramíneas anuales, en cambio, son más abundantes en siembra directa con respecto a sistemas de laboreo convencional. Las malezas perennes como grupo no están asociadas a ningún sistema de labranza. El conocimiento de la influencia de la siembra directa sobre la flora de malezas contribuirá a lograr un control más confiable y un adecuado manejo del ambiente en la región.No-tillage systems imply a series of agricultural practices acting together with significant consequences on weed flora adaptations. Absence of tillage produces fundamental habitat changes commonly causing shifts in composition and abundance of weeds. Type of tillage alters light, temperature and moisture conditions sufficiently to modify emergence and establishment of many weeds species. No-tillage systems leads to different herbicide use and reductions in their performance and may result in shifts in species composition. The impact of no-tillage systems on weed communities varies greatly among regions and weed species. While the focus of this review is on the principal agricultural practices and weeds common in the Humid Pampa (Argentina), much especific research is lacking in the country, thus, this paper also draws information from relevant research elsewhere. In most papers reviewed, annual broadleaf weeds are more abundant in no-tillage systems, the exception being wind-disseminated species. Grassy weeds show greater populations in no-till while perennials are not associated to any tillage system. Better knowledge of no-tillage influence on weed flora will contribute to more reliable weed control and adequate environmental management in the region.Facultad de Ciencias Agrarias y Forestale

Analysis of weed community changes and their determining factors in no-tillage systems

El sistema de siembra directa implica el uso conjunto de una serie de prácticas de manejo que determinan cambios adaptativos en la comunidad de malezas. Distintos sistemas de laboreo del suelo generan diferentes condiciones de luz, temperatura y humedad suficientes para alterar la emergencia y establecimiento de numerosas especies de malezas. El sistema de siembra directa requiere un empleo diferente de herbicidas y puede disminuir la eficiencia de los mismos. Estos cambios en el control químico pueden contribuir a explicar modificaciones en la composición de la flora. El impacto de los sistemas de siembra directa varía marcadamente según regiones y especies de malezas consideradas y en Argentina en particular, la información sobre el comportamiento de las comunidades de malezas en distintos sistemas de labranza es reducida. Si bien esta revisión está centrada en las principales prácticas agrícolas y especies de malezas comunes en la pampa húmeda argentina, debido a la falta de información específica en muchos aspectos, se ha recurrido también a investigaciones relevantes en otras áreas. La siembra directa contínua conduce en la mayoría de los casos revisados a reducciones en la abundancia de muchas malezas latifoliadas anuales en el largo plazo. La excepción son las especies cuyos propágulos son transportados por el viento. Las poblaciones de gramíneas anuales, en cambio, son más abundantes en siembra directa con respecto a sistemas de laboreo convencional. Las malezas perennes como grupo no están asociadas a ningún sistema de labranza. El conocimiento de la influencia de la siembra directa sobre la flora de malezas contribuirá a lograr un control más confiable y un adecuado manejo del ambiente en la región.No-tillage systems imply a series of agricultural practices acting together with significant consequences on weed flora adaptations. Absence of tillage produces fundamental habitat changes commonly causing shifts in composition and abundance of weeds. Type of tillage alters light, temperature and moisture conditions sufficiently to modify emergence and establishment of many weeds species. No-tillage systems leads to different herbicide use and reductions in their performance and may result in shifts in species composition. The impact of no-tillage systems on weed communities varies greatly among regions and weed species. While the focus of this review is on the principal agricultural practices and weeds common in the Humid Pampa (Argentina), much especific research is lacking in the country, thus, this paper also draws information from relevant research elsewhere. In most papers reviewed, annual broadleaf weeds are more abundant in no-tillage systems, the exception being wind-disseminated species. Grassy weeds show greater populations in no-till while perennials are not associated to any tillage system. Better knowledge of no-tillage influence on weed flora will contribute to more reliable weed control and adequate environmental management in the region.Facultad de Ciencias Agrarias y Forestale

Partial maxillary osteotomy following an unsuccessful forced eruption of an impacted maxillary canine: 10 year follow-up. Review and case report

The maxillary canines are amongst the most frequently impacted teeth, second only to the third molars. Several conservative orthodontic and surgical techniques are available to position the teeth properly in the dental arch, even in severe cases. However, when an extraction is necessary, it often leaves a critical alveolar defect of difficult management. The authors present the technique of Partial Maxillary Osteotomy, in which a dento-alveolar segment is moved mesially, hence closing the remaining space, allowing for the formation of healthy periodontium and resulting in an adequate functional and aesthetic outcome. A case report is presented with a 10 year follow-up, proving the technique's stability in the long term

Characterization of bone repair in rat femur after treatment with calcium phosphate cement and autogenous bone graft

<p>Abstract</p> <p>Background</p> <p>In this study, the biocompatibility, stability and osteotransductivity of a new cement based on alpha-tricalcium phosphate (alpha-TCP) were investigated in a bone repair model using a rat model.</p> <p>Methods</p> <p>The potential of alpha-TCP on bone repair was compared to autogenous bone grafting, and unfilled cavities were used as negative control. Surgical cavities were prepared and designated as test (T), implanted with alpha-TCP blocks; negative control (C - ), unfilled; and positive control (C + ), implanted with autogenous bone graft. Results were analyzed on postoperative days three, seven, 14, 21 and 60.</p> <p>Results</p> <p>The histological analyses showed the following results. Postoperative day three: presence of inflammatory infiltrate, erythrocytes and proliferating fibroblasts in T, C - and C + samples. Day seven: extensive bone neoformation in groups T and C + , and beginning of alpha-TCP resorption by phagocytic cells. Days 14 and 21: osteoblastic activity in the three types of cavities. Day 60: In all samples, neoformed bone similar to surrounding bone. Moderate interruption on the ostectomized cortical bone.</p> <p>Conclusions</p> <p>Bone neoformation is seen seven days after implantation of alpha-TCP and autogenous bone. Comparison of C - with T and C + samples showed that repair is faster in implanted cavities; on day 60, control groups presented almost complete bone repair. Alpha-TCP cement presents biocompatibility and osteotransductivity, besides stability, but 60 days after surgery the cavities were not closed.</p

Panorametry: suggestion of a method for mandibular measurements on panoramic radiographs

<p>Abstract</p> <p>Background</p> <p>Orthopantomography (panoramic radiography) has been used for the study of measurements involving particularly the prediction of the eruption of impacted lower third molars and analyses of measurements of the ramus and head of mandible. The discrepancies involved with the projection of this radiographic image has stimulated the search for further ways to use it, particularly in orthodontic treatments and oral and maxillofacial surgeries. The author proposes a graphimetric method for the mandible, based on panoramic radiography. The results are expressed in linear and angular measurements, aiming at bilateral comparisons as well as the determination of the proportion of skeletal and dental structures, individually and among themselves as a whole. The method has been named Panorametry, and allows measurement of the mandible (Mandibular Panorametry) or the posterior mandibular teeth (Dental Panorametry). When combining mandible and maxilla, it should be referred to as Total Panorametry. It may also be used, in the future, with Cone Beam computed tomography (CT) images, and in this case it may be mentioned as CT Panorametry.</p

Generation and characterization of human insulin-releasing cell lines

<p>Abstract</p> <p>Background</p> <p>The in vitro culture of insulinomas provides an attractive tool to study cell proliferation and insulin synthesis and secretion. However, only a few human beta cell lines have been described, with long-term passage resulting in loss of insulin secretion. Therefore, we set out to establish and characterize human insulin-releasing cell lines.</p> <p>Results</p> <p>We generated ex-vivo primary cultures from two independent human insulinomas and from a human nesidioblastosis, all of which were cultured up to passage number 20. All cell lines secreted human insulin and C-peptide. These cell lines expressed neuroendocrine and islets markers, confirming the expression profile found in the biopsies. Although all beta cell lineages survived an anchorage independent culture, none of them were able to invade an extracellular matrix substrate.</p> <p>Conclusion</p> <p>We have established three human insulin-releasing cell lines which maintain antigenic characteristics and insulin secretion profiles of the original tumors. These cell lines represent valuable tools for the study of molecular events underlying beta cell function and dysfunction.</p

Retención de glifosato y nutrientes en vías de flujo preferencial

Las franjas de vegetación ribereña (RVS) reducen el volumen del flujo de escorrentía superficial y retienen los sedimentos, los pesticidas y los nutrientes que esas aguas transportan desde los campos de cultivo (CF) adyacentes. La capacidad de estas franjas para retener el glifosato se demostró por medio de parcelas experimentales, aunque se desconoce la variabilidad espacial de ese proceso. En este trabajo se analizó la influencia de la microtopografía dentro de las RVS en la retención de glifosato (y su metabolito principal, AMPA), fósforo y nitrógeno dentro de las RVS de paisajes agropecuarios. Se compararon los niveles de retención dentro y fuera de las vías de flujo preferencial (PFP), en presencia y ausencia de un estrato arbóreo. La concentración de glifosato + AMPA en los suelos dentro de las PFP fue 88 veces mayor que fuera de la PFP. Las concentraciones de fósforo y nitrógeno, el contenido de arcilla y la densidad aparente también fueron más altos dentro que fuera de las PFP. La presencia del estrato arbóreo no modificó las concentraciones de glifosato + AMPA, ni de fósforo, ni de nitrógeno, ni el contenido de arcilla, como tampoco la morfometría de las PFP. La densidad aparente y el contenido de arcilla, registrados en los CF y en las PFP, junto con las concentraciones más altas de glifosato, fósforo y nitrógeno en los suelos de las PFP, son consistentes con una conexión hidráulica entre los CF y las PFP. Estos resultados contrastan con algunas conclusiones obtenidas a partir de estudios experimentales en parcelas uniformes y ponen en evidencia la importancia de tomar en cuenta génesis y estructura de las PFP en el diseño, evaluación y manejo de la función de filtrado de las RVS.Riparian vegetation strips (RVS) reduce surface runoff volume and retain sediments, pesticides and nutrients that are transported across them from adjacent crop-fields (CF). The ability of these strips to retain glyphosate has been demonstrated using experimental plots, but the spatial variability of that process is unknown. In this work, the influence of microtopography inside the RVS on the retention of glyphosate (and its major metabolite, AMPA), phosphorus and nitrogen were analyzed within a RVS of agricultural landscapes. Retention levels inside and outside preferential flow pathways (PFP) were compared under presence and absence of a tree stratum. Soil glyphosate + AMPA concentration within PFP was 88-fold higher than outside. Phosphorus and nitrogen soil concentrations, clay and bulk density were also higher inside than outside the PFP. The tree stratum did not modify soil concentration of glyphosate + AMPA, phosphorus, nitrogen, clay content, nor the morphometry of the PFP. Bulk density and clay content recorded in adjacent CF and in PFP, in addition to the high glyphosate, phosphorus and nitrogen concentrations in PFP soil, are consistent with a hydraulic connection between the CF and the PFP. These results contrast with some conclusions obtained from experimental studies under uniform plots and emphasize the importance of taking into account the genesis and structure of PFP in the design, evaluation and management of the filtering function of RVS.Fil: Giaccio, Gustavo C. M.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Barrow; ArgentinaFil: Laterra, Pedro. Fundacion Bariloche. Departamento de Energia.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Aparicio, Virginia Carolina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Costa, Jose Luis. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Balcarce; ArgentinaFil: Puricelli, Marino Marcelo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Balcarce; Argentin