The 3 Minute Step Test is a validated field test to evaluate the functional exercise capacity in children aged 6 to 12.

BACKGROUND: Field tests are useful to assess the functional exercise capacity. The 6minute walking test (6MWT) is the most common field test even if alternatives are needed. The main aim of the study was to verify if the 3minute step test (3MST) is a valid tool to measure the functional exercise capacity and can surrogate the 6MWT in healthy children from 6- to 12-years-old. METHODS: This randomized cross-over trial recruited 30 healthy children from 6 to 12 years. One 6MWT and two 3MST (3MST1 and 3MST2) were performed randomly on 3 consecutive days. The variables were the distance (6MWT), the number of steps (3MST) and the cardiorespiratory parameters. RESULTS: The distance walked during 6MWT was very strongly correlated to the number of steps during the 3MST (3MST1: rho=0.833; P<0.001 and 3MST2: rho=0.868; P<0.001). Heart rate (HR) was lower than the theoretical maximal HR at the end of both tests. The change in HR and perceived fatigue were significantly higher after the 3MST. A learning effect was observed in the 3MST (+8 steps; P<0.001). CONCLUSIONS: The 3MST is validated and can be a surrogate for the 6MWT in healthy children population between 6 and 12 years old. A training test is required in these children.

Experiencias docentes en el cambio curricular vivido en la carrera de enfermería de la FES, Iztacala / Teaching experiences in the curricular change experienced in the nursing career of the FES Iztacala

Introducción: la calidad educativa en las IES (Instituciones de Educación Superior) ha sido avalada por procesos de evaluación y acreditación a nivel institucional y curricular, llevando a cabo un proceso de mejora continua, mediante recomendaciones sugeridas por los evaluadores, lo anterior garantizará la calidad institucional ante la formación de futuros profesionales. Objetivo: analizar las experiencias del profesorado de la carrera de enfermería de la Facultad de Estudios Superiores Iztacala, sobre el cambio curricular vivido. Material y métodos: estudio cualitativo con enfoque fenomenológico, mediante entrevista a profundidad a doce profesores de enfermería. Muestreo por conveniencia de acuerdo a la saturación de datos. En aspectos éticos y legales, se realizó carta de consentimiento informado. El análisis de datos fue basado en Miles y Huberman, con abordaje teórico según Van Manen. Resultados: surgieron dos categorías: 1. Sentimientos y afectaciones emocionales respecto al cambio curricular y laborales; 2. impacto del cambio curricular en los aprendizajes de los estudiantes, las cuales evidenciaron cómo el profesorado ha vivido los cambios curriculares en los 17 años desde que fue implementada la licenciatura. Conclusiones: los informantes narraron que en cada cambio curricular surgen emociones diferentes, entre incertidumbre, compromiso, responsabilidad y asumir empoderamiento para implementar la curricula, con ello, lograr los objetivos esperados por la misma, considerando perfil de egreso y rendimiento académico de los estudiantes.

Introduction: the educational quality at the higher level in schools and faculties has been endorsed by evaluation and accreditation processes at the institutional and curricular level, carrying out an improvement process, through the recommendations suggested by the evaluators, thus covering them in a certain time. The foregoing will guarantee the institutional quality before the training of future professionals. Objective: to analyze experiences of the teaching staff of the nursing career of the Iztacala Faculty of Higher Studies, on the curricular change experienced. Material and methods: Qualitative study with a phenomenological approach, through an in-depth interview with twelve nursing professors. Convenience sampling according to data saturation. In ethical and legal aspects, an informed consent letter was drawn up. The data analysis was through Miles and Huberman, with a theoretical approach based on Van Manen. Results: two categories emerged: 1. Feelings and emotional affectations regarding the curricular and work change; 2. impact of curricular change on student learning, which showed how teachers have experienced curricular changes in the 17 years since the degree was implemented. Conclusions: the informants narrated that in each curricular change different emotions arise, between uncertainty, commitment, responsibility and assuming empowerment to implement the curriculum, thereby achieving the objectives expected by it, considering the graduation profile and the academic performance of the students.

Delayed-onset bleb-related endophthalmitis caused by Moraxella nonliquefaciens. / Endoftalmitis de inicio tardío asociada a ampolla de filtración por Moraxella nonliquefaciens.

Bleb-related endophthalmitis is rare and appears months or years after surgery. The causative agents are usually streptococci or gram-negative bacteria. There are few cases in the literature of endophthalmitis caused by Moraxella nonliquefaciens, and most are delayed-onset associated with blebitis after glaucoma filtration surgery. The case is presented of a 90-year-old patient with endophthalmitis in the right eye due to Moraxella nonliquefaciens associated with blebitis 10 years after glaucoma surgery. After treatment, disappearance of blebitis is observed 2weeks later and resolution of vitritis 29 days later, with recovery of vision to previous values (20/200). Endophthalmitis due to Moraxella nonliquefaciens is rare, and is associated with late onset blebitis after glaucoma filtration surgery. Despite the virulence of the clinical symptoms, the visual prognosis is usually favourable.

Bacterial keratitis due to Moraxella nonliquefaciens. / Queratitis bacteriana por Moraxella nonliquefaciens.

Moraxella keratitis can lead to important complications. Moraxella nonliquefaciens(M. nonliquefaciens) has the worst prognosis. Only three cases of corneal infections due to M. nonliquefaciens have been published. The case is presented of a 79-year-old man with bullous keratopathy, recently affected with severe infectious keratitis. Dense, deep, and central stromal infiltrates and hyphaema were detected. After the identification of M. nonliquefaciens in the culture, and given the progression of the condition, the initial empirical treatment was modified to topical ciprofloxacin and ceftazidime in accordance with the antibiogram, combining oral ciprofloxacin and amoxicillin-clavulanate. After 27 days, there was total resolution of the lesion, with central residual leucoma. Keratitis caused by M. nonliquefaciens is rare and must be suspected in elderly patients with local predisposing factors, such as corneal damage or previous eye surgery. Early antibiogram-guided treatment and close monitoring are important to avoid complications and poor compliance.

Saving Lives with Tourniquets: A Review of Penetrating Injury Medical Examiner Cases.

Background: After numerous recent mass casualty events, civilian hemorrhage control has taken a militaristic approach with aggressive and early use of tourniquets. While military literature has demonstrated the utility of tourniquets in preventing battlefield deaths from extremity injuries, there is limited understanding of their role in civilian penetrating trauma deaths. The purpose of this study is to review medical examiner (ME) autopsy records in a defined population to determine the incidence of preventable deaths from extremity wounds amenable to tourniquet placement. Methods: This is a retrospective review of ME cases from one urban county with a descriptive analysis of the demographics, mechanisms of injuries, and causes of death of homicide cases from 2003 to 2017. Mechanism of injury and wound patterns were reviewed to determine the overall occurrence of extremity injuries and amenability of tourniquet placement. Results: A total of 1,804 homicide cases were reviewed with 1,521 (84.3%) resulting from penetrating trauma. Isolated extremity injuries were present in 22 (1.45%) of the penetrating cases, all of which were amenable to tourniquet placement. There were 409 (26.9%) concurrent extremity and central penetrating injuries. The vast majority of extremity wounds were amenable to tourniquet placement (92.1%). Extrapolating nationally to 16,187 annual penetrating injury related homicides in 2016, an estimated 235 (1.45%) isolated extremity injury related deaths could be prevented and an additional estimated 4,354 (26.9%) concurrent extremity and central injury related deaths could potentially receive enhanced care with early tourniquet placement. Conclusion: Among urban ME cases, both isolated extremity cases and concurrent extremity-central injuries exist that may be amenable to life-saving tourniquet use. Extrapolating our findings nationwide suggests that many lives could be saved with early tourniquet use. Considering these findings, tourniquet availability and early placement may have a prominent role in reducing injury deaths from penetrating trauma.

Drosophila divalent metal ion transporter Malvolio is required in dopaminergic neurons for feeding decisions.

Members of the natural resistance-associated macrophage protein (NRAMP) family are evolutionarily conserved metal ion transporters that play an essential role in regulating intracellular divalent cation homeostasis in both prokaryotes and eukaryotes. Malvolio (Mvl), the sole NRAMP family member in insects, plays a role in food choice behaviors in Drosophila and other species. However, the specific physiological and cellular processes that require the action of Mvl for appropriate feeding decisions remain elusive. Here, we show that normal food choice requires Mvl function specifically in the dopaminergic system, and can be rescued by supplementing food with manganese. Collectively, our data indicate that the action of the Mvl transporter affects food choice behavior via the regulation of dopaminergic innervation of the mushroom bodies, a principle brain region associated with decision-making in insects. Our studies suggest that the homeostatic regulation of the intraneuronal levels of divalent cations plays an important role in the development and function of the dopaminergic system and associated behaviors.

Neurosteroidogenesis Today: Novel Targets for Neuroactive Steroid Synthesis and Action and Their Relevance for Translational Research.

Neuroactive steroids are endogenous neuromodulators synthesised in the brain that rapidly alter neuronal excitability by binding to membrane receptors, in addition to the regulation of gene expression via intracellular steroid receptors. Neuroactive steroids induce potent anxiolytic, antidepressant, anticonvulsant, sedative, analgesic and amnesic effects, mainly through interaction with the GABAA receptor. They also exert neuroprotective, neurotrophic and antiapoptotic effects in several animal models of neurodegenerative diseases. Neuroactive steroids regulate many physiological functions, such as the stress response, puberty, the ovarian cycle, pregnancy and reward. Their levels are altered in several neuropsychiatric and neurological diseases and both preclinical and clinical studies emphasise a therapeutic potential of neuroactive steroids for these diseases, whereby symptomatology ameliorates upon restoration of neuroactive steroid concentrations. However, direct administration of neuroactive steroids has several challenges, including pharmacokinetics, low bioavailability, addiction potential, safety and tolerability, which limit its therapeutic use. Therefore, modulation of neurosteroidogenesis to restore the altered endogenous neuroactive steroid tone may represent a better therapeutic approach. This review summarises recent approaches that target the neuroactive steroid biosynthetic pathway at different levels aiming to promote neurosteroidogenesis. These include modulation of neurosteroidogenesis through ligands of the translocator protein 18 kDa and the pregnane xenobiotic receptor, as well as targeting of specific neurosteroidogenic enzymes such as 17ß-hydroxysteroid dehydrogenase type 10 or P450 side chain cleavage. Enhanced neurosteroidogenesis through these targets may be beneficial not only for neurodegenerative diseases, such as Alzheimer's disease and age-related dementia, but also for neuropsychiatric diseases, including alcohol use disorders.

No evidence of pathogenic involvement of cathelicidins in patient cohorts and mouse models of lupus and arthritis.

Apart from their role in the immune defence against pathogens evidence of a role of antimicrobial peptides (AMPs) in autoimmune diseases has accumulated in the past years. The aim of this project was to examine the functional impact of the human cathelicidin LL-37 and the mouse cathelicidin-related AMP (CRAMP) on the pathogenesis of lupus and arthritis. Serum LL-37 and anti-LL-37 levels were measured by ELISA in healthy donors and patients with Systemic Lupus Erythematosus (SLE) and Rheumatoid arthritis (RA). Pristane-induced lupus was induced in female wild type (WT) and cathelicidin-deficient (CRAMP-/-) mice. Serum levels of anti-Sm/RNP, anti-dsDNA, and anti-histone were determined via ELISA, cytokines in sera and peritoneal lavages were measured via Multiplex. Expression of Interferon I stimulated genes (ISG) was determined by real-time PCR. Collagen-induced arthritis (CIA) was induced in male WT and CRAMP-/- mice and arthritis severity was visually scored and analysed histomorphometrically by OsteoMeasure software. Serum levels of anti-LL-37 were higher in SLE-patients compared to healthy donors or patients with RA. However, no correlation to markers of disease activity or organ involvement was observed. No significant differences of autoantibody or cytokine/chemokine levels, or of expression of ISGs were observed between WT and CRAMP-/- mice after pristane-injection. Furthermore, lung and kidney pathology did not differ in the absence of CRAMP. Incidence and severity of CIA and histological parameters (inflammation, cartilage degradation, and bone erosion) were not different in WT and CRAMP-/- mice. Although cathelicidins are upregulated in mouse models of lupus and arthritis, cathelicidin-deficiency did not persistently affect the diseases. Also in patients with SLE, autoantibodies against cathelicidins did not correlate with disease manifestation. Reactivity against cathelicidins in lupus and arthritis could thus be an epiphenomenon caused by extensive overexpression in blood and affected tissues. In addition, other cationic AMPs could functionally compensate for the deficiency of cathelicidins.

Vipericidins: a novel family of cathelicidin-related peptides from the venom gland of South American pit vipers.

Cathelicidins are phylogenetically ancient, pleiotropic host defense peptides-also called antimicrobial peptides (AMPs)-expressed in numerous life forms for innate immunity. Since even the jawless hagfish expresses cathelicidins, these genetically encoded host defense peptides are at least 400 million years old. More recently, cathelicidins with varying antipathogenic activities and cytotoxicities were discovered in the venoms of poisonous snakes; for these creatures, cathelicidins may also serve as weapons against prey and predators, as well as for innate immunity. We report herein the expression of orthologous cathelicidin genes in the venoms of four different South American pit vipers (Bothrops atrox, Bothrops lutzi, Crotalus durissus terrificus, and Lachesis muta rhombeata)-distant relatives of Asian cobras and kraits, previously shown to express cathelicidins-and an elapid, Pseudonaja textilis. We identified six novel, genetically encoded peptides: four from pit vipers, collectively named vipericidins, and two from the elapid. These new venom-derived cathelicidins exhibited potent killing activity against a number of bacterial strains (S. pyogenes, A. baumannii, E. faecalis, S. aureus, E. coli, K. pneumoniae, and P. aeruginosa), mostly with relatively less potent hemolysis, indicating their possible usefulness as lead structures for the development of new anti-infective agents. It is worth noting that these South American snake venom peptides are comparable in cytotoxicity (e.g., hemolysis) to human cathelicidin LL-37, and much lower than other membrane-active peptides such as mastoparan 7 and melittin from bee venom. Overall, the excellent bactericidal profile of vipericidins suggests they are a promising template for the development of broad-spectrum peptide antibiotics.

Perfil de ingreso de los alumnos de Enfermería, Facultades de Estudios Superiores Iztacala y Zaragoza, UNAM / Nursing student's enrollment profile, Iztacala and Zaragoza Superior Studies Faculties, UNAM

Introducción: La Universidad tiene como una de sus tareas conocer a los estudiantes, ya que en la medida que nuestro sistema de educación logre tener mayor información sobre el perfil de éstos y sus trayectorias escolares, se podrán diseñar e implementar políticas novedosas y funcionales que atiendan las necesidades específicas de su población. Objetivo: Analizar el perfil de los estudiantes que ingresan a la Licenciatura en Enfermería de México. Las Facultades de Estudios Superiores (FES) Iztacala y Zaragoza. Método: Estudio descriptivo-transversal, con estudiantes de primer ingreso de la generación 2011-I de la FES Zaragoza e Iztacala. La población de estudio fueron 600 alumnos. La recolección de la información fue a través de un cuestionario. La confiabilidad del instrumento fue de 0.875 con la prueba de Alfa de Cronbach. Para el manejo de la información se elaboró una base de datos con el programa SPSS® y se utilizó estadística descriptiva. Resultados: El 49% de alumnos proviene de pase reglamentado, el promedio de ingreso es de 8.1 a 9.0; en el 61% Enfermería fue primera elección; el nivel socioeconómico de los alumnos es bajo; en el 74% el promedio durante el primer año fue de 8.0 a 10.0. Discusión: A diferencia de otras Carreras de la Universidad Nacional Autónoma de México (UNAM), la de Enfermería da cabida a casi el 50% de los aspirantes de escuelas externas a ella. Los alumnos aún cuando son de nivel socioeconómico bajo, reúnen características favorables para su trayectoria escolar, entre ellas, un buen promedio y que fueron admitidos en la Carrera que seleccionaron.

Introduction: The University has as one of its tasks to better know the profiles and trajectories of students, so that supporting innovative and functional policies can be designed and implemented. Objective: To analyze the profile of students enrolling into the Nursing Undergraduate System at the Iztacala and Zaragoza Superior Studies Faculty. Method: Basic-descriptive study with freshmen students of the 2011-I generation of the Nursing Bachelors Degree program at the FES Zaragoza and Iztacala. the population was 600 alumni. A questionnaire was used to gather data. the instrument reliability was equivalent to a 0.875 Cronbach Alpha score. A SPSS® database was created and data were analyzed through descriptive statistics. Results: The 49% of the students came from the "automatic pass" format. The enrollment grade point average went from 8.1 to 9.0. For the 61% of the students, nursing was their first choice of major. The socioeconomic level of the students was low. The 76% of the students obtained a grade point average between 8.0 and 10.0 during all their freshman year. Discussion: Unlike other careers at the Universidad Nacional Autónoma de México (UNAM), Nursing accepts almost 50% of the prospects from external schools, situation which does not occur in other careers. Although the majority of students who entered have a low social-economical level, they have other favorable characteristics for their school trajectory such as a good grade point average and that they were accepted in the career that they chose.

MicroCT-based virtual histology evaluation of preclinical medulloblastoma.

PURPOSE: The purpose of this paper is to validate a rapid and cost-effective ex vivo technique, microCT-based virtual histology, as an alternative to MRI imaging for assessing the therapeutic response in genetically engineered mouse models of cancer. PROCEDURES: All animal procedures were conducted in accordance with the Guidelines for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Texas Health Science Center at San Antonio. MRI imaging was performed on 6-week-old, bortezomib-treated genetically engineered Patched1, p53 mice that recapitulate the characteristics of human medulloblastoma. After MRI scans, the same mice were euthanized to collect brain or spine samples for virtual histology staining followed by microCT scanning. RESULTS: Nine-micrometer resolution ex vivo micro X-ray computed tomography (microCT)-based virtual histology images were qualitatively reflective of high-field live animal images obtained with magnetic resonance imaging (MRI) and histopathology. Cerebellar volumes on microCT-based virtual histology correlated closely with MRI cerebellar volumes (R = 0.998). MRI and microCT-based virtual histology both indicated a significant difference between cerebellar volumes of untreated and treated mice (p = 0.02 and p = 0.04, respectively). The ex vivo microCT method also allowed a 7,430-fold improvement in voxel resolution (voxel volume of 729 µm³ for 9-µm isometric resolution microCT vs. 5,416,800 µm³ for 400 × 111 × 122 µm resolution MRI) at a 28% cost savings ($400 vs. $555 per animal). CONCLUSION: The ex vivo, en bloc technique of microCT-based virtual histology matched MRI in reflecting histopathology. MicroCT-based virtual histology proved to be a more cost-effective technique and less labor-intensive. On the other hand, MRI provides ability to perform in vivo imaging, faster scanning and lower radiation dose by sacrificing the spatial resolution. Thus, both in vivo MRI and ex vivo microCT-based virtual histology are effective means of quantitatively evaluating therapeutic response in preclinical models of cerebellar tumors including the childhood cancer, medulloblastoma.

Comparative effects of carbapenems on bacterial load and host immune response in a Klebsiella pneumoniae murine pneumonia model.

Doripenem is a carbapenem with potent broad-spectrum activity against Gram-negative pathogens, including antibiotic-resistant Enterobacteriaceae. As the incidence of extended-spectrum ß-lactamase (ESBL)-producing Gram-negative bacilli is increasing, it was of interest to examine the in vivo comparative efficacy of doripenem, imipenem, and meropenem against a Klebsiella pneumoniae isolate expressing the TEM-26 ESBL enzyme. In a murine lethal lower respiratory infection model, doripenem reduced the Klebsiella lung burden by 2 log(10) CFU/g lung tissue over the first 48 h of the infection. Treatment of mice with meropenem or imipenem yielded reductions of approximately 1.5 log(10) CFU/g during this time period. Seven days postinfection, Klebsiella titers in the lungs of treated mice decreased an additional 2 log(10) CFU/g relative to those in the lungs of untreated control animals. Lipopolysaccharide (LPS) endotoxin release assays indicated that 6 h postinfection, meropenem- and imipenem-treated animals had 10-fold more endotoxin in lung homogenates and sera than doripenem-treated mice. Following doripenem treatment, the maximum endotoxin release postinfection (6 h) was 53,000 endotoxin units (EU)/ml, which was 2.7- and 6-fold lower than imipenem or meropenem-treated animals, respectively. While the levels of several proinflammatory cytokines increased in both the lungs and sera following intranasal K. pneumoniae inoculation, doripenem treatment, but not meropenem or imipenem treatment, resulted in significantly increased interleukin 6 levels in lung homogenates relative to those in lung homogenates of untreated controls, which may contribute to enhanced neutrophil killing of bacteria in the lung. Histological examination of tissue sections indicated less overall inflammation and tissue damage in doripenem-treated mice, consistent with improved antibacterial efficacy, reduced LPS endotoxin release, and the observed cytokine induction profile.

Effect of chronic hCG administration on Alzheimer's-related cognition and A beta accumulation in PS1KI mice.

Age-associated changes in the reproductive hormones-the gonadal steroid hormones and the gonadotropins-have been identified as potential risk factors for Alzheimer's disease (AD). However, levels of gonadotropins and estrogens are closely linked in vivo, and it has proven difficult to separate the effects of gonadotropins from the well-documented estrogenic effects on AD-related neuropathology in experimental models of menopause. To assess the effects of gonadotropins on cognition and AD biochemical markers independent of estrogenic effects, a potent analog of luteinizing hormone [human chorionic gonadotropin (hCG)] was administered to ovariectomized presenilin1 knock-in mice (PS1KI). Gonadotropin administration was found to induce hyperactivity and anxiety (Open Field Maze and Taste Neophobia Task) and working memory dysfunction, without altering reference memory (Morris Water Maze). Although gonadotropin administration modestly altered ß amyloid (Aß40) levels, levels of the longer more toxic form (Aß42) were unaffected. Furthermore, altered Aß40 levels were not associated with observed behavioral and cognitive impairments. These findings provide proof, in principle, that the gonadotropin hormones play a role in the modulation of AD-related behavior, cognition, and neuropathology.

Translucencia nucal aumentada y cariotipo normal / Increased nuchal translucency and normal kariotype

Antecedentes: La exploración ecográfica entre las semanas 11 y 14 tiene un papel fundamental en el cribado de anomalías cromosómicas, siendo la medida de la translucencia nucal un método bien establecido y ampliamente aceptado para este fin. Objetivo: Evaluar retrospectivamente la evolución de los fetos con translucencia nucal aumentada y cariotipo normal. Método: Se recogieron los datos de 104 fetos con TN >percentil 95 (p95) entre las semanas 11 y 14, evaluados en nuestro centro. En los 61 que resultaron eu-ploides, se estudió la incidencia de anomalías estructurales diagnosticadas tanto prenatalmente como tras el nacimiento, así como las pérdidas fetales anteparto. De estos fetos, nacieron sanos el 80 por ciento cuando la TN estaba entre p95 y 3,4 mm, el 50 por ciento con TN entre 3,5 y 4,4 mm, el 30 por ciento con TN entre 4,5 y 5,4 mm, y el 18 por ciento con TN > 5,5 mm. Entre los 4 recién nacidos euploides con patología, hubo 3 con cardiopatía. Conclusión: La presencia de TN aumentada entre las 11 -14 semanas en fetos euploides se asocia a un incremento del riesgo de anomalías estructurales mayores, principalmente cardiacas. La prevalencia de malformaciones aumenta significativamente con TN >3,5 mm, y el pronóstico gestacional adverso empeora conforme aumenta la medida de la TN.

Background: Ultrasound scan has a main role at the 11-14 weeks screening for chromosomal abnormalities. The measurement of nuchal translucency (NT) thickness is a widespread stablished method to achieve this target. Objective: To assess retrospectively the outcome of fetuses with increased nuchal translucency and normal karyotype. Method: Data were collected from 104 fetuses with NT > 95th percentile at 11 to 14 weeks of gestation, followed in our institution. The sixty one euploid fetuses were studied in order to determine the incidence of structural abnormalities, diagnosed either before or after delivery, as well as antenatal fetal loss. Among these fetuses, there were no malformations at birth in 80 percent for NT between the 95th percentile and 3.4 mm; 50 percent for NT between 3.5 and 4.4 mm; 30 percent for NT of 4.5-5.4 mm; and 18 percent for NT > 5.5 mm. There were 4 euploid newborns with some kind of structural defect at birth, 3 of them presented a cardiac malformation. Conclusion: The presence of increased NT at 11-14 weeks scan in euploid fetuses it's associated with a higher risk of major structural abnormalities, mainly cardiac ones. The prevalence of malformations is significantly increased for NT > 3.5 mm, and the adverse perinatal outcome is directly associated with the thickness of NT.

Ovariectomy and 17beta-estradiol replacement do not alter beta-amyloid levels in sheep brain.

The benefits of estrogen replacement as a preventative treatment for Alzheimer's disease (AD) are subject to debate. Because the effects of estrogen depletion and replacement on accumulation of the neurotoxic beta-amyloid (A beta) peptide in transgenic animal models of AD have been variable, we examined A beta levels and oxidative stress in a nontransgenic animal model. Sheep have traditionally been used as a model for human reproduction; however because they share 100% sequence homology with the human form of A beta, they may also have potential as a nontransgenic model for A beta biology. The effect of ovariectomy and estrogen replacement administered for 6 months via slow-release implant was examined in the brain of 4.5-yr-old sheep. A beta levels were measured by ELISA, and protein levels of the amyloid precursor protein (APP), APP C-terminal fragments (C100), and presenilin-1 were examined semiquantitatively by Western blot as markers of APP processing. Markers of oxidative stress were examined semiquantitatively by Western blot [4-hydroxy-2(E)-nonenal] and oxyblot (protein carbonyls). We found no effects of estrogen depletion and supplementation in terms of AD-related biochemical markers, including A beta levels, APP processing, and oxidative stress levels. Evidence of a trend toward increased P450 side-chain cleavage enzyme levels in the hippocampus of ovariectomized and estrogen supplemented sheep suggests that neurosteroidogenesis may compensate for gonadal estrogen depletion; however, these findings cannot explain the lack of effect of estrogen supplementation on APP processing. It is possible that supraphysiological doses of estrogen are necessary to yield antiamyloidogenic and antioxidative benefits in ovariectomized sheep.