c-Abl tyrosine kinase down-regulation as target for memory improvement in Alzheimer's disease.

Background: Growing evidence suggests that the non-receptor tyrosine kinase, c-Abl, plays a significant role in the pathogenesis of Alzheimer's disease (AD). Here, we analyzed the effect of c-Abl on the cognitive performance decline of APPSwe/PSEN1ΔE9 (APP/PS1) mouse model for AD. Methods: We used the conditional genetic ablation of c-Abl in the brain (c-Abl-KO) and pharmacological treatment with neurotinib, a novel allosteric c-Abl inhibitor with high brain penetrance, imbued in rodent's chow. Results: We found that APP/PS1/c-Abl-KO mice and APP/PS1 neurotinib-fed mice had improved performance in hippocampus-dependent tasks. In the object location and Barnes-maze tests, they recognized the displaced object and learned the location of the escape hole faster than APP/PS1 mice. Also, APP/PS1 neurotinib-fed mice required fewer trials to reach the learning criterion in the memory flexibility test. Accordingly, c-Abl absence and inhibition caused fewer amyloid plaques, reduced astrogliosis, and preserved neurons in the hippocampus. Discussion: Our results further validate c-Abl as a target for AD, and the neurotinib, a novel c-Abl inhibitor, as a suitable preclinical candidate for AD therapies.

Competencias sobre geriatría, modalidad de enseñanza y ageísmo en estudiantes de medicina en el contexto de la pandemia por COVID-19

Introducción. La pandemia por COVID-19 forzó a cambiar la educación médica a una modalidad virtual. Esta puede influenciar sobre la calidad de la enseñanza y la percepción que tienen los alumnos sobre los adultos mayores. Objetivo. Evaluar la percepción del auto reporte de cumplimiento de las competencias sobre geriatría (ACCG) y ageísmo, en estudiantes de medicina de universidades de Lima que llevaron el curso de geriatría en modalidad presencial y virtual. Métodos. Estudio transversal en estudiantes de 3 universidades de Lima, Perú que llevaron el curso de geriatría de forma presencial o virtual. El auto reporte de cumplimiento de competencias en geriatría fue medido mediante un puntaje y el ageísmo fue medido con la escala UCLA-GAS. Se realizó el análisis bivariado entre ACCG y el resto de las variables, finalmente se construyó un modelo de regresión lineal. Resultados. Se encontraron las medias del puntaje para ACCG fue de 0,72 (DE = 0,22) para la modalidad presencial y 0,75 (DE = 0,23) para la enseñanza virtual. No encontramos asociación estadística entre las variables de estudio (p = 0,39). La regresión lineal de auto reporte de cumplimiento de competencias en geriatría y ageísmo, fue ajustado por año de la carrera en que cursó geriatría y existencia de otro curso que aborde temas de geriatría, y se encontró que a mayor ACCG, mayor ageísmo. Conclusiones. Hasta el momento, no se puede afirmar que la educación virtual sea inferior a la presencial en lo que respecta generar al cumplimiento auto reportado de competencias en geriatría.

Introduction. The current COVID-19 pandemic has forced medical education to change to a virtual modality. This can influence the quality of teaching and the perception that students have about older adults. Objective. Our objective is to evaluate the perception of the self-report fulfillment of geriatric competencies (SRFGC) in medical students from universities in Lima-Peru, comparing face-to-face and virtual techniques. Methods. A cross-sectional study was designed including students from 3 universities in Lima, Peru who have taken the geriatrics course in person or virtually, measuring the main variables such as ACCG according to the recommendations of the pogoe web portal and ageing the UCLA-GAS scale. Averages and standard deviations were calculated for numerical variables and frequency for categorical variables. Bivariate analysis was also performed between ACCG and the rest of the variables measured. Results. Means 0.72 (SD=0.22) were found for the face-to-face modality and 0.75 (SD=0.23) for virtual teaching. We found no statistical association between the study variables (p value = 0.39), so there is no difference between the SRFGC between the virtual and face-to-face modalities. Through a linear regression model of SRFGC and ageism adjusted to statistically significant variables of the study, it was found that the greater the SRFGC, the greater the ageism. Conclusions. So far, it cannot be said that virtual education is inferior to face-to-face education with regard to the SRFGC.

Análisis clínico-tomográfico en obstrucción de intestino delgado por adherencias según el sitio de obstrucción en la tomografía / Clinical-tomographic analysis in adhesive small bowel obstruction according to obstruction site in the tomography

Introducción. Las adherencias postoperatorias son la causa más frecuente de obstrucción de intestino delgado. La clínica sugiere el diagnóstico, pero de manera poco precisa la causa y el sitio de la obstrucción. La tomografía computarizada contrastada es el estudio óptimo y permite identificar de manera oportuna a los pacientes que requieren intervención quirúrgica. El objetivo de este estudio fue analizar la correlación entre la clínica y el sitio de obstrucción detectado en la tomografía computarizada contrastada de abdomen, en pacientes con sospecha diagnóstica de obstrucción de intestino delgado por adherencias. Métodos. Estudio prospectivo, transversal y analítico de pacientes con sospecha clínica de obstrucción de intestino delgado por adherencias y antecedentes quirúrgicos y su correlación con el sitio de obstrucción detectado en la tomografía computarizada de abdomen contrastada, de pacientes atendidos entre marzo de 2016 y febrero de 2019 en un hospital de segundo nivel. Resultados. Se incluyeron 41 pacientes, la media de edad fue de 59 años y el género masculino el más comprometido (68,3 %, n=28); la ausencia de evacuaciones estuvo presente en 97,5 % (p=0,026). La tomografía computarizada contrastada mostró el sitio de obstrucción en 73 % de los pacientes y la localización de la obstrucción más prevalente fue en íleon distal (31,7 %, n=13). Se asoció a leucocitosis (p=0,041) y a dolor más intenso (p=0,049), sin presentar irritación peritoneal. Conclusión. La obstrucción localizada en el íleon distal se caracterizó por presentar más dolor y mayor recuento leucocitario, sin correlación como factor de riesgo para requerir tratamiento quirúrgico.

Introduction. Postoperative adhesions are the most common cause of small bowel obstruction. The clinical presentation suggests the diagnosis, but imprecisely the cause and the site of the obstruction. Contrast computed tomography is the optimal study and allows the timely identification of patients requiring surgical intervention. The objective of this study was to analyze the correlation between the symptoms and the obstruction site detected in the abdominal contrasted computed tomography in patients with suspected diagnosis of small bowel obstruction due to adhesions. Methods. Prospective, cross-sectional and analytical study of patients with clinical suspicion of small bowel obstruction due to adhesions and surgical history, and its correlation with the obstruction site detected in the abdominal contrasted computed tomography, during March 2016 to February 2019 in a secondary level hospital. Results. Forty-one patients were included, the mean age was 59 years and the male gender was the most frequent (68.3%, n=28); the absence of evacuations was present in 97.5% (p=0.026). Contrast computed tomography showed the obstruction site in 73% of the patients. The most prevalent location of the obstruction was in the distal ileum (31.7%, n=13). It was associated with leukocytosis (p=0.041) and more intense pain (p=0.049), without presenting peritoneal irritation. Conclusion. The obstruction located in the distal ileum was characterized by more pain and a higher white blood cell count, without correlation as a risk factor for requiring surgical treatment

c-Abl regulates a synaptic plasticity-related transcriptional program involved in memory and learning.

Memory consolidation requires activation of a gene expression program that allows de novo protein synthesis. But the molecular mechanisms that favour or restrict that program are poorly understood. The kinase c-Abl can modulate gene expression through transcription factors and chromatin modifiers. Here, we show that c-Abl ablation in the brain improves learning acquisition and memory consolidation in mice. Its absence also affects gene expression profiles in the mouse hippocampus. We found that genes involved in synaptic plasticity and actin cytoskeleton dynamics, such as Arp2 and Thorase, are up-regulated at the mRNA and protein levels in trained c-Abl KO mice and by a chemical-LTP stimulus. Trained c-Abl KO mice also show that dendritic spines are larger than in wild-type mice and present at a higher density. These results indicate that c-Abl kinase is an important part of the mechanism that limits or restricts signalling of relevant gene programs involved in morphological and functional spine changes upon neuronal stimulation.

Induced Changes in Aroma Compounds of Foods Treated with High Hydrostatic Pressure: A Review.

Since conventional thermal processing can have detrimental consequences on aroma compounds, non-thermal technologies such as high hydrostatic pressure (HHP) have been explored. HHP may alter the weak chemical bonds of enzymes. These changes can modify the secondary, tertiary, and quaternary structures of key enzymes in the production of aroma compounds. This can result in either an increase or decrease in their content, along with reactions or physical processes associated with a reduction of molecular volume. This article provides a comprehensive review of HHP treatment's effects on the content of lipid-derived aroma compounds, aldehydes, alcohols, ketones, esters, lactones, terpenes, and phenols, on various food matrices of vegetable and animal origin. The content of aldehydes and ketones in food samples increased when subjected to HHP, while the content of alcohols and phenols decreased, probably due to oxidative processes. Both ester and lactone concentrations appeared to decline due to hydrolysis reactions. There is no clear tendency regarding terpenes concentration when subjected to HHP treatments. Because of the various effects of HHP on aroma compounds, an area of opportunity arises to carry out future studies that allow optimizing and controlling the effect.

c-Abl Kinase Is Required for Satellite Cell Function Through Pax7 Regulation.

Satellite cells (SCs) are tissue-specific stem cells responsible for adult skeletal muscle regeneration and maintenance. SCs function is critically dependent on two families of transcription factors: the paired box (Pax) involved in specification and maintenance and the Muscle Regulatory Factors (MRFs), which orchestrate myogenic commitment and differentiation. In turn, signaling events triggered by extrinsic and intrinsic stimuli control their function via post-translational modifications, including ubiquitination and phosphorylation. In this context, the Abelson non-receptor tyrosine kinase (c-Abl) mediates the activation of the p38 α/ß MAPK pathway, promoting myogenesis. c-Abl also regulates the activity of the transcription factor MyoD during DNA-damage stress response, pausing differentiation. However, it is not clear if c-Abl modulates other key transcription factors controlling SC function. This work aims to determine the role of c-Abl in SCs myogenic capacity via loss of function approaches in vitro and in vivo. Here we show that c-Abl inhibition or deletion results in a down-regulation of Pax7 mRNA and protein levels, accompanied by decreased Pax7 transcriptional activity, without a significant effect on MRF expression. Additionally, we provide data indicating that Pax7 is directly phosphorylated by c-Abl. Finally, SC-specific c-Abl ablation impairs muscle regeneration upon acute injury. Our results indicate that c-Abl regulates myogenic progression in activated SCs by controlling Pax7 function and expression.

Colecistitis hemorrágica: reporte de caso y revisión de la literatura / Hemorrhagic cholecystitis: case report and literature review

Resumen Introducción: La colecistitis hemorrágica es una complicación poco frecuente de la colecistitis aguda con una alta mortalidad. Materiales y Método: Paciente con dolor abdominal en hipocondrio derecho e ictericia. Los exámenes de laboratorio y ultrasonido hepatobiliar mostraron datos sugestivos de colecistitis aguda; durante su estancia hospitalaria presenta deterioro de su estado general, realizándose tomografía computarizada mostrando imágenes sugestivas de colecistitis hemorrágica y hemoperitoneo. Resultados: Laparotomía de urgencia, corroborando los hallazgos tomográficos y resolviéndose satisfactoriamente con la colecistectomía. Discusión: El diagnóstico de colecistitis hemorrágica es difícil ya que sus manifestaciones clínicas de inicio no difieren de la colecistitis aguda, por lo que la sospecha clínica y el adecuado estudio de imagen son importantes para su detección. Conclusión: A pesar que la colecistitis hemorrágica con perforación y hemoperitoneo es una patología muy poco común, de diagnóstico confuso, es importante establecer la realización de una tomografía computarizada abdominal con contraste endovenoso en pacientes con sospecha de colecistitis aguda grave.

Introduction: Hemorrhagic cholecystitis is a rare complication of acute cholecystitis with a high mortality. Materials and Method: Patient with abdominal pain in right hypochondrium and jaundice. Laboratory analyses and hepatobiliary ultrasound suggested acute cholecystitis, however, general worsening during hospital stay was observed and a computed tomography was performed, revealing hemorrhagic cholecystitis and hemoperitoneum. Results: Urgent laparotomy which confirmed tomographic results, successfully solved with cholecystectomy. Discussion: Hemorrhagic cholecystitis diagnosis is difficult as symptoms at the beginning do not differ from acute cholecystitis, then, clinical suspicion and a correct image analysis is crucial for its detection. Conclusion: Although, perforated hemorrhagic cholecystitis with hemoperitoneum is a very rare entity with confused diagnosis, an abdominal computed tomography with intravenous contrast is very important in any patient with severe acute cholecystitis suspicion.

Clinical characteristics and location of lesions in patients with deep infiltrating endometriosis using the revised Enzian classification

Objective: To describe the clinical characteristics and location of lesions in patients with deeply infiltrating endometriosis using the revised Enzian (rEnzian) classification. Material and Methods: The clinical records of 60 patients undergoing laparoscopy for deeply infiltrating endometriosis at Hospital Civil de Culiacán, Sinaloa and Hospital San Javier, Jalisco, Mexico, were reviewed. Age, body mass index (BMI), number of pregnancies, childbearing, previous abortions, laparoscopic suggestion (pelvic pain, bleeding, infertility), and size and location of the lesions were assessed according to the rEnzian classification. Results: The mean age of the patients was 30.5 years. The mean BMI was 25.6 kg/m2. Sixty-eight percent were nulliparous and 13% had at least one birth. Eighty-five percent had pelvic pain and 8.3% had infertility. Seventy percent (n=42) of the women had ovarian endometriomas (middle compartment); uterosacral and the torus uterinus ligaments were affected in 23.3%, rectum and sigmoid colon in 35% (posterior compartment), and the appendix and small intestine in 3.3%. According to the rEnzian classification, the most affected compartment was C2 (rectum and sigmoid colon with 1-3 cm lesions). Conclusion: Pelvic pain was the main symptom of patients with deeply infiltrating endometriosis, mainly in nulliparous women. According to the rEnzian classification, the C2 compartment was the most affected (rectum and sigmoid colon).

Surgical outcome of jejunum-jejunum intussusception secondary to Rapunzel syndrome: a case report.

BACKGROUND: Adult intestinal intussusception is a rare condition caused by the mechanical disruption of bowel motility. A bezoar is defined as indigestible material inside the gastrointestinal tract that develops into a trapped mass; the most frequent bezoar is a trichobezoar. When a trichobezoar extends into the small intestine it is defined as Rapunzel's syndrome. Literature describing complications related to this pathology remains scarce. CASE PRESENTATION: A 16-year-old Mexican girl presented to our emergency room with acute abdomen and a presumptive diagnosis of intestinal obstruction. Computed tomography was suggestive of intussusception. Surgery confirmed a jejunal-jejunal intussusception with a mass within the gastric cavity extending into her small intestine, corresponding to a trichobezoar. A manual intussusception reduction and a gastrotomy with extraction of the trichobezoar were performed. CONCLUSIONS: We present a case of a jejunum intussusception as a complication of Rapunzel syndrome. Our patient had a favorable outcome after surgical intervention with a manual intussusception reduction, with retrograde displacement of the trichobezoar into the gastric lumen, and a complete extraction through a gastrostomy. Follow-up included psychiatric evaluation.

PGC-1α-Dependent Mitochondrial Adaptation Is Necessary to Sustain IL-2-Induced Activities in Human NK Cells.

Human Natural Killer (NK) cells are a specialized heterogeneous subpopulation of lymphocytes involved in antitumor defense reactions. NK cell effector functions are critically dependent on cytokines and metabolic activity. Among various cytokines modulating NK cell function, interleukin-2 (IL-2) can induce a more potent cytotoxic activity defined as lymphokine activated killer activity (LAK). Our aim was to determine if IL-2 induces changes at the mitochondrial level in NK cells to support the bioenergetic demand for performing this enhanced cytotoxic activity more efficiently. Purified human NK cells were cultured with high IL-2 concentrations to develop LAK activity, which was assessed by the ability of NK cells to lyse NK-resistant Daudi cells. Here we show that, after 72 h of culture of purified human NK cells with enough IL-2 to induce LAK activity, both the mitochondrial mass and the mitochondrial membrane potential increased in a PGC-1α-dependent manner. In addition, oligomycin, an inhibitor of ATP synthase, inhibited IL-2-induced LAK activity at 48 and 72 h of culture. Moreover, the secretion of IFN-γ from NK cells with LAK activity was also partially dependent on PGC-1α expression. These results indicate that PGC-1α plays a crucial role in regulating mitochondrial function involved in the maintenance of LAK activity in human NK cells stimulated with IL-2.

[Infected jejunal mesenteric pseudocyst: A case report]. / Pseudoquiste mesentérico infectado en yeyuno: reporte de un caso.

BACKGROUND: Mesenteric cysts are very rare abdominal growths, generally asymptomatic, and which are usually detected incidentally while performing a physical examination or an imaging test. Complications such as infections, haemorrhage, torsion, rupture, or bowel obstruction, are seldom found in this pathology, but they can be a cause of acute abdomen. The purpose of this report is to describe the characteristics and the clinical outcome of a male patient with an infected mesenteric pseudocyst of the jejunum. CLINICAL CASE: A 49 year-old male was admitted to the emergency department with 6-day onset of abdominal pain, bowel obstruction signs, palpable tumour located in the upper hemi-abdomen, systemic inflammatory response syndrome, 36,100/mm(3) white cells, 4.21 ng/ml procalcitonin, abdominal computed tomography scan with evidence of a mesenteric cystic tumour. An exploratory laparotomy was performed, finding the presence of a mesenteric pseudocyst of the jejunum with infection signs, extirpated and sent for histopathological examination. The clinical progress of the patient was satisfactory with the discharge of the patient 7 days after the surgical intervention. CONCLUSION: These cysts can debut as an acute abdomen due to haemorrhage, infection, obstruction and/or bowel perforation, complications can be life threatening if not detected and surgically treated at an early stage by performing a resection of the pseudocysts, with or without bowel resection, depending on the location and the size of the cyst.

[Acute appendicitis during pregnancy: report of 4 cases]. / Apendicitis aguda durante el embarazo: reporte de 4 casos.

BACKGROUND: Acute appendicitis is the more frequent no obstetric surgical emergency during pregnancy with an incidence of 1 in 1500 pregnancies. The clinical diagnosis is difficult because of the physiological changes of pregnancy itself. If not treated early increases the risk of maternal and fetal morbidity. OBJECTIVE: To describe the diagnosis and treatment of four cases of acute appendicitis during pregnancy. CLINICAL CASE: Four cases of acute appendicitis during pregnancy diagnosed in the period of a month. Gestational age at diagnosis of appendicitis was between 8 and 13 week. All patients underwent laparotomy; three cases were appendicitis phase II and one phase III. The preoperative was managed with indomethacin and ceftriaxone. There were no maternal or obstetric complications. CONCLUSIONS: An early diagnosis and treatment of acute appendicitis during pregnancy, and a multidisciplinary approach between surgeon, obstetrician and anesthesiologist is the basis for success in the management of these patients.

Facial development disorders due to inhibition to endochondral ossification of mandibular condyle process caused by malnutrition.

OBJECTIVE: To analyze the effect of protein restriction on histomorphometric parameters of bone remodeling in mandibular condyle process and its possible influence in facial development in growing rats. MATERIALS AND METHODS: Wistar rats weaned at the age of 21 days were assigned to one of the following groups: control (fed a regular hard diet ad libitum) and protein restricted (PR) (fed a hard diet lacking in protein ad libitum). The animals were euthanized on day 35 after the onset of the experiment. Mandibles were resected, fixed in 10% formalin, hemisected at the symphysis, and then radiographed in order to perform cephalometric studies of the condylar process length and the height of the lower alveolar process. Mandibles were then processed for light microscopy, and histomorphometric determinations were performed on histologic sections of the condylar process subchondral bone. RESULTS: The PR group showed a significantly lower body weight than control group at the end of the experiment. The length of the condylar process was lower in the PR group; however, the diet used in this study did not affect the height of the lower alveolar process. The histomorphometric analysis showed that the PR group exhibited a statistically significant decrease in bone formation and bone volume in condylar process subchondral bone. CONCLUSION: Protein restriction inhibits bone formation and longitudinal growth in the mandibular condylar process. This result suggest that protein restriction can alter normal facial development.

Orthodontic implications of protein undernutrition in mandibular growth. A cephalometric study in growing rats.

The present experimental work analyzes the development of different mandibular units and its likely impact on the direction of mandibular displacement during facial development, and the relation between the mesiodistal dimension of the first, second, and third molars and the length of the mandibular corpus in a model of protein undernutrition with muscular atrophy in growing rats. Sixteen Wistar rats weaned at the age of 21 days were assigned to one of the following groups: control (fed a regular hard diet ad libitum) and experimental (fed a diet lacking in protein, corn flour, ad libitum). All the animals were euthanized five weeks after the onset of the experiment. Following resection of the mandibles, the mandibles were hemisected at the symphysis and fixed in 10% formalin. Remaining soft tissue was removed. Metallic landmarks were placed in the mental and mandibular foramens of one hemimandible of each rat. The hemimandibles were radiographed. The cephalometric study was performed on paper tracings of the projected image of the radiographs. Both groups exhibited a slight increase in body weight (b.w) throughout the first ten days of the experiment. After this point, the undernourished group showed no further increase in b.w., and exhibited significantly lower b.w. than controls at the end of the experiment. The cephalometric study showed that the length of the mandible as a whole, and of the condylar and angular processes was significantly lower in the undernourished group. In addition, significant differences in the vertical relation between the angular process to the mandibular corpus, the convexity of the angular process, and the ratio between total molar width (from the first to the third molar) and the length of the mandibular corpus were observed.

Orthodontic implications of protein undernutrition in mandibular growth: a cephalometric study in growing rats

Se presenta un trabajo experimental en el que se analiza el desarrollo de diferentes unidades mandibulares y su probable impacto en: la dirección del desplazamiento mandibular durante el desarrollo facial y en la relación entre las dimensiones mesiodistales de primero a tercer molar con la longituddel cuerpo mandibular en un modelo de desnutrición proteica y atrofia muscular de ratas en crecimiento. Se utilizaron ratas Wistar destetadas a los 21 días de edad y separadas en dos grupos denominados control (alimentado conuna dieta dura convencional ad libitum) y experimental (alimentado con una dieta deficiente en proteínas, harina de maíz, administrada ad libitum). A las cinco semanas de experiencia todos los animales fueron sacrificados, se disecaron las mandíbulas y se separaron a nivel de la línea media, se fijaronen formol al 10 por ciento y se removieron los tejidos blandos. A unahemimandíbula de cada animal se le realizaron marcas metálicas a nivel del agujero mentoniano y del agujero mandibular, posteriormente fueron radiografiadas. A partir de proyeccionesde las radiografías se obtuvieron trazados sobre los que se realizóel estudio cefalométrico. El peso corporal aumentó levemente en los primeros diez días de experiencia en ambos grupos. A partir de ese punto en el grupo desnutrido no se incrementó y fue significativamente menor que el grupo control al final del período experimental. El estudio cefalométrico mostró que las longitudes mandibular,del proceso condilar y del proceso angular fueron significativamente menores en el grupo desnutrido. Se encontraron además diferencias significativas en los valores quedefinen la relación vertical del proceso angular al cuerpo de la mandíbula, en la convexidad del proceso angular y en larelación entre la longitud mesiodistal total de primero a tercer molar con la longitud del cuerpo mandibular.

Caracterización de un modelo de regeneración de los tejidos periodontales luego de una periodontitis inducida experimentalmente en ratas. Estudio histomorfométrico

Introducción - La regeneración de los tejidos periodontales luego de una periodontitis experimental inducida por una ligadura cervical, colocada en molares inferiores de rata durante cinco días, fue analizada por métodos histomorfométricos aIos cero, cinco, siete y diez días del retiro de Ia ligadura cervical. Métodos - En cortes orientados y coloreados con hematoxilina y eosina, los siguientes parámetros morfométricos fueron evaluados según los principios de Ia estereología: volumen óseo total en el espacio interradicular (VOT) y volumen de los tejidos blandos remanentes (VTBR). Resultados - Cinco días luego del retiro de Ia ligadura cervical, ambos parámetros disrninuyen. AIos siete días ambos parámetros incrementaron su valor, siendo mucho mas marcado el aumento de VTBR, el cual registró el 92 por ciento de su valor normal aIos diez días de retirada Ia ligadura cervical. Conclusión -La caracterización de este modelo experimental provee Ia base para estudios comparativos bajo diferentes condiciones experimentales.

Effect of orthodontic forces on root resorption in molars submitted to experimental periodontitis.

The present experimental study addresses the issue of the development and size of root resorption areas in molars of rats submitted to orthodontic forces of 51 or 75 g and the induction of periodontal disease by placing a cotton ligature around the cervix of the first upper molars for 48 hours. Immediately on removal of the ligature or 48 hs later we put an orthodontic device in place. The device comprised two steel bands. The arms of a helicoidal spring that exerted force towards palatine passed through the palatine tubes welded to the bands. The number of odontoclasts and the percentage of root resorption areas were determined histomorphometrically on bucco-palatine sections obtained at the level of the central roots. The data showed an increase in root resorption areas when the orthodontic forces were applied to molars of rats following the induction of periodontitis. The magnitude of the force was proportional to the size of the resorption areas and to the number of odontoclasts. Both these end-points exhibited smaller values when the forces were applied once the inflammatory reaction had subsided. The present study shows that the risk of development of root resorption areas in patients with periodontal disease submitted to orthodontic treatment would be lower if lighter forces were applied and treatment were delayed until the inflammatory signs have subsided.

Effect of orthodontic forces on root resorption in molars submitted to experimental periodontitis

Se presenta un estudio experimental sobre la aparición y extensión de reabsorciones radiculares en molares de ratas sometidas a fuerzas ortodóncicas de 51 a 75 g y a las que se había inducido enfermedad periodontal por medio de la instalación de la instalación de una ligadura de algodón en el cuello de los primeros molares superiores que fue retirada a las 48 hs. A dicho tiempo o 48 horas después de retirada la ligadura se les instaló un aparato ortodóncico construido con dos bandas de acero por cuyos tubos palatinos pasan los brazos de un resorte helicoidal que ejerce fuerza hacia palatino. Sobre cortes histológicos bucopalatinos y a nivel de las raíces centrales se contó el númnero de odontoclastos y se determinó el porcentaje de áreas de reabsorción radicular por metodologías histomorfométricas. Los resultados obtenidos mostraron que esta última se incrementó cuando las fuerzas ortodóncicas se aplicaron a molares de ratas a las que se les había inducido periodontitis, que la magnitud de la fuerza empleada fue proporcional a la extensión de la reabsorción radicular y al número de odontoclastos y que ambos son menores cuando las fuerzas se aplican una vez reducidos los signos inflamatorios. Este estudio indica que el riesgo de aparición de reabsorciones radiculares en pacientes con enfermedad periodontal a los que se trata con ortodoncia sería menor si se aplicaran fuerzas de baja magnitud y si se esperara la remisión de los signos inflamatorios para la instalación de los aparatos.

Effect of orthodontic forces on root resorption in molars submitted to experimental periodontitis.

The present experimental study addresses the issue of the development and size of root resorption areas in molars of rats submitted to orthodontic forces of 51 or 75 g and the induction of periodontal disease by placing a cotton ligature around the cervix of the first upper molars for 48 hours. Immediately on removal of the ligature or 48 hs later we put an orthodontic device in place. The device comprised two steel bands. The arms of a helicoidal spring that exerted force towards palatine passed through the palatine tubes welded to the bands. The number of odontoclasts and the percentage of root resorption areas were determined histomorphometrically on bucco-palatine sections obtained at the level of the central roots. The data showed an increase in root resorption areas when the orthodontic forces were applied to molars of rats following the induction of periodontitis. The magnitude of the force was proportional to the size of the resorption areas and to the number of odontoclasts. Both these end-points exhibited smaller values when the forces were applied once the inflammatory reaction had subsided. The present study shows that the risk of development of root resorption areas in patients with periodontal disease submitted to orthodontic treatment would be lower if lighter forces were applied and treatment were delayed until the inflammatory signs have subsided.

Effect of orthodontic forces on root resorption in molars submitted to experimental periodontitis

Se presenta un estudio experimental sobre la aparición y extensión de reabsorciones radiculares en molares de ratas sometidas a fuerzas ortodóncicas de 51 a 75 g y a las que se había inducido enfermedad periodontal por medio de la instalación de la instalación de una ligadura de algodón en el cuello de los primeros molares superiores que fue retirada a las 48 hs. A dicho tiempo o 48 horas después de retirada la ligadura se les instaló un aparato ortodóncico construido con dos bandas de acero por cuyos tubos palatinos pasan los brazos de un resorte helicoidal que ejerce fuerza hacia palatino. Sobre cortes histológicos bucopalatinos y a nivel de las raíces centrales se contó el númnero de odontoclastos y se determinó el porcentaje de áreas de reabsorción radicular por metodologías histomorfométricas. Los resultados obtenidos mostraron que esta última se incrementó cuando las fuerzas ortodóncicas se aplicaron a molares de ratas a las que se les había inducido periodontitis, que la magnitud de la fuerza empleada fue proporcional a la extensión de la reabsorción radicular y al número de odontoclastos y que ambos son menores cuando las fuerzas se aplican una vez reducidos los signos inflamatorios. Este estudio indica que el riesgo de aparición de reabsorciones radiculares en pacientes con enfermedad periodontal a los que se trata con ortodoncia sería menor si se aplicaran fuerzas de baja magnitud y si se esperara la remisión de los signos inflamatorios para la instalación de los aparatos. (AU)