Inhibitory protein-protein interactions of the SIRT1 deacetylase are choreographed by post-translational modification.

Regulation of SIRT1 activity is vital to energy homeostasis and plays important roles in many diseases. We previously showed that insulin triggers the epigenetic regulator DBC1 to prime SIRT1 for repression by the multifunctional trafficking protein PACS-2. Here, we show that liver DBC1/PACS-2 regulates the diurnal inhibition of SIRT1, which is critically important for insulin-dependent switch in fuel metabolism from fat to glucose oxidation. We present the x-ray structure of the DBC1 S1-like domain that binds SIRT1 and an NMR characterization of how the SIRT1 N-terminal region engages DBC1. This interaction is inhibited by acetylation of K112 of DBC1 and stimulated by the insulin-dependent phosphorylation of human SIRT1 at S162 and S172, catalyzed sequentially by CK2 and GSK3, resulting in the PACS-2-dependent inhibition of nuclear SIRT1 enzymatic activity and translocation of the deacetylase in the cytoplasm. Finally, we discuss how defects in the DBC1/PACS-2-controlled SIRT1 inhibitory pathway are associated with disease, including obesity and non-alcoholic fatty liver disease.

Vascularized 3D Human Skin Models in the Forefront of Dermatological Research.

In vitro engineered skin models are emerging as an alternative platform to reduce and replace animal testing in dermatological research. Despite the progress made in recent years, considerable challenges still exist for the inclusion of diverse cell types within skin models. Blood vessels, in particular, are essential in maintaining tissue homeostasis and are one of many primary contributors to skin disease inception and progression. Substantial efforts in the past have allowed the successful fabrication of vascularized skin models that are currently utilized for disease modeling and drugs/cosmetics testing. This review first discusses the need for vascularization within tissue-engineered skin models, highlighting their role in skin grafting and disease pathophysiology. Second, the review spotlights the milestones and recent progress in the fabrication and utilization of vascularized skin models. Additionally, advances including the use of bioreactors, organ-on-a-chip devices, and organoid systems are briefly explored. Finally, the challenges and future outlook for vascularized skin models are addressed.

Viable cryopreserved human bone graft exhibit superior osteogenic properties in mandibular lateral augmentation.

Lack of bone volume to place dental implants is frequently a problem in the reconstruction of edentulous patients. Even though autografts are the gold standard for jaw regeneration, morbidity associated with the harvesting site stimulates the demand for other substitutes. The aim of this study is to characterize the incorporation and the osteogenic ability of a viable cryopreserved human bone graft (VC-HBG) in the mandibular augmentation in rats. Bone chips from fresh human vertebrae cadaveric donors were processed, cryoprotected and deep-frozen at - 80 °C maintaining its cell viability. A jaw augmentation model was used in 20 athymic nude rats allocated into 2 groups to either receive the VC-HBG or an acellular graft as control (A-HBG). The assessment of the grafts' incorporation was performed at 4 and 8 weeks by micro-CT, histomorphometry and immunohistochemistry. Bone volume gain was significantly higher for the VC-HBG group at both time points. At 4 weeks, the A-HBG group presented significantly higher mineral density, but at 8 weeks, the VC-HBG group showed significantly higher values than the A-HBG. There was no statistical difference between VC-HBG and A-HBG groups at 4-weeks for remaining graft particles, while at 8 weeks, the VC-HBG group showed significantly less graft remnants. Collagen I, osteopontin and tartrate-resistant acid phosphatase expression were significantly higher in the VC-HBG group at both time points, while osteocalcin expression was significantly higher in the VC-HBG group at 8-weeks compared to the A-HBG group. This experimental research demonstrated that the VC-HBG shows positive osteogenic properties, greater bone formation, higher rate of bone remodeling and a better overall incorporation in rats' mandibles compared to the A-HBG.

PCSK9 Imperceptibly Affects Chemokine Receptor Expression In Vitro and In Vivo.

Proprotein convertase subtilin/kexin type 9 (PCSK9) is a protease secreted mainly by hepatocytes and in lesser quantities by intestines, pancreas, and vascular cells. Over the years, this protease has gained importance in the field of cardiovascular biology due to its regulatory action on the low-density lipoprotein receptor (LDLR). However, recently, it has also been shown that PCSK9 acts independent of LDLR to cause vascular inflammation and increase the severity of several cardiovascular disorders. We hypothesized that PCSK9 affects the expression of chemokine receptors, major mediators of inflammation, to influence cardiovascular health. However, using overexpression of PCSK9 in murine models in vivo and PCSK9 stimulation of myeloid and vascular cells in vitro did not reveal influences of PCSK9 on the expression of certain chemokine receptors that are known to be involved in the development and progression of atherosclerosis and vascular inflammation. Hence, we conclude that the inflammatory effects of PCSK9 are not associated with the here investigated chemokine receptors and additional research is required to elucidate which mechanisms mediate PCSK9 effects independent of LDLR.

3-D vascularized breast cancer model to study the role of osteoblast in formation of a pre-metastatic niche.

Breast cancer cells (BCCs) preferentially metastasize to bone. It is known that BCCs remotely primes the distant bone site prior to metastasis. However, the reciprocal influence of bone cells on the primary tumor is relatively overlooked. Here, to study the bone-tumor paracrine influence, a tri-cellular 3-D vascularized breast cancer tissue (VBCTs) model is engineered which comprised MDA-MB231, a triple-negative breast cancer cells (TNBC), fibroblasts, and endothelial cells. This is indirectly co-cultured with osteoblasts (OBs), thereby constituting a complex quad-cellular tumor progression model. VBCTs alone and in conjunction with OBs led to abnormal vasculature and reduced vessel density but enhanced VEGF production. A total of 1476 significantly upregulated and 775 downregulated genes are identified in the VBCTs exposed to OBs. HSP90N, CYCS, RPS27A, and EGFR are recognized as upregulated hub-genes. Kaplan Meier plot shows HSP90N to have a significant outcome in TNBC patient survivability. Furthermore, compared to cancer tissues without vessels, gene analysis recognized 1278 significantly upregulated and 566 downregulated genes in VBCTs. DKK1, CXCL13, C3 protein and BMP4 are identified to be downregulated hub genes in VBCTs. Together, a multi-cellular breast cancer model and culture protocols are established to study pre-metastatic events in the presence of OBs.

Key Chemokine Pathways in Atherosclerosis and Their Therapeutic Potential.

The search to improve therapies to prevent or treat cardiovascular diseases (CVDs) rages on, as CVDs remain a leading cause of death worldwide. Here, the main cause of CVDs, atherosclerosis, and its prevention, take center stage. Chemokines and their receptors have long been known to play an important role in the pathophysiological development of atherosclerosis. Their role extends from the initiation to the progression, and even the potential regression of atherosclerotic lesions. These important regulators in atherosclerosis are therefore an obvious target in the development of therapeutic strategies. A plethora of preclinical studies have assessed various possibilities for targeting chemokine signaling via various approaches, including competitive ligands and microRNAs, which have shown promising results in ameliorating atherosclerosis. Developments in the field also include detailed imaging with tracers that target specific chemokine receptors. Lastly, clinical trials revealed the potential of various therapies but still require further investigation before commencing clinical use. Although there is still a lot to be learned and investigated, it is clear that chemokines and their receptors present attractive yet extremely complex therapeutic targets. Therefore, this review will serve to provide a general overview of the connection between various chemokines and their receptors with atherosclerosis. The different developments, including mouse models and clinical trials that tackle this complex interplay will also be explored.

Adipocyte calcium sensing receptor is not involved in visceral adipose tissue inflammation or atherosclerosis development in hyperlipidemic Apoe-/- mice.

The calcium sensing receptor (CaSR) is a G-protein coupled receptor that especially plays an important role in the sensing of extracellular calcium to maintain its homeostasis. Several in-vitro studies demonstrated that CaSR plays a role in adipose tissue metabolism and inflammation, resulting in systemic inflammation and contributing to atherosclerosis development. The aim of this study was to investigate whether adipocyte CaSR plays a role in adipose tissue inflammation in-vivo and atherosclerosis development. By using a newly established conditional mature adipocyte specific CaSR deficient mouse on a hyperlipidemic and atherosclerosis prone Apoe-/- background it could be shown that CaSR deficiency in adipocytes does neither contribute to initiation nor to progression of atherosclerotic plaques as judged by the unchanged lesion size or composition. Additionally, CaSR deficiency did not influence gonadal visceral adipose tissue (vAT) inflammation in-vivo, although a small decrease in gonadal visceral adipose cholesterol content could be observed. In conclusion, adipocyte CaSR seems not to be involved in vAT inflammation in-vivo and does not influence atherosclerosis development in hyperlipidemic Apoe-/- mice.

High-Density Lipoprotein Modifications: A Pathological Consequence or Cause of Disease Progression?

High-density lipoprotein (HDL) is well-known for its cardioprotective effects, as it possesses anti-inflammatory, anti-oxidative, anti-thrombotic, and cytoprotective properties. Traditionally, studies and therapeutic approaches have focused on raising HDL cholesterol levels. Recently, it became evident that, not HDL cholesterol, but HDL composition and functionality, is probably a more fruitful target. In disorders, such as chronic kidney disease or cardiovascular diseases, it has been observed that HDL is modified and becomes dysfunctional. There are different modification that can occur, such as serum amyloid, an enrichment and oxidation, carbamylation, and glycation of key proteins. Additionally, the composition of HDL can be affected by changes to enzymes such as cholesterol ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), and phospholipid transfer protein (PLTP) or by modification to other important components. This review will highlight some main modifications to HDL and discuss whether these modifications are purely a consequential result of pathology or are actually involved in the pathology itself and have a causal role. Therefore, HDL composition may present a molecular target for the amelioration of certain diseases, but more information is needed to determine to what extent HDL modifications play a causal role in disease development.

Human Bone Marrow-Derived Mesenchymal Stromal Cell-Seeded Bone Biomaterial Directs Fast and Superior Mandibular Bone Augmentation in Rats.

Atrophic maxillary ridges present a challenge in the field of oral implantology. Autologous bone is still considered the gold standard grafting material, but the increased morbidity and surgical complications represent a major drawback for its use. The aim of this study was to assess the efficacy of an off-the-shelf cell-seeded bone biomaterial for mandibular bone augmentation, compared to its acellular counterpart. We used a rat model to test the osteogenic properties of bone marrow-derived mesenchymal stromal cells (MSCs)-seeded bone microparticles compared to acellular bone microparticles alone. Rats were euthanized at 4 and 8 weeks, and results analyzed using micro-CT imaging, histology (H&E, Masson's Trichrome), histomorphometry and immunohistology (Tartrate-Resistant Acid Phosphatase-TRAP, Osteocalcin and human specific anti-mitochondria antibodies). Micro-CT analysis demonstrated that the cell-seeded biomaterial achieved significantly more bone volume formation at 4 weeks (22.75 ± 2.25 mm3 vs 12.34 ± 2.91 mm3, p = 0.016) and at 8 weeks (64.95 ± 5.41 mm3 vs 42.73 ± 10.58 mm3, p = 0.029), compared to the acellular bone microparticles. Histology confirmed that the cell-seeded biomaterial was almost completely substituted at 8 weeks, in opposition to the acellular biomaterial group. Immunohistochemical analysis showed a significantly higher number of TRAP and Osteocalcin positive cells at 4 weeks in the cell-seeded group compared to the acellular group, thereby demonstrating a higher rate of bone remodeling in the presence of MSCs. The grafted human cells remained viable and were detected up to at least 8 weeks, as observed using the human specific anti-mitochondria antibody. This off-the-shelf material available in unlimited quantities could therefore represent a significant advance in the field of mandibular bone augmentation by providing a larger volume of new bone formation in a shorter time.

Exploring Cancer Cell Behavior In Vitro in Three-Dimensional Multicellular Bioprintable Collagen-Based Hydrogels.

In vitro cancer 3D models are valuable tools to provide mechanistic insight into solid tumor growth, invasion, and drug delivery. The 3D spheroid model of solid tumors has been the most popular cancer model in use until now. However, previous studies have shown that these spheroid models lack sufficient morphological parameters, which may affect their response to chemicals. In this work, we proposed the fabrication of miniaturized 3D cancer models using collagen type I-based bioprintable bioinks. In the context of a mimicking model for advanced neuroblastoma studies, we showed that cancer cells contained in bioprintable bioinks formed Homer Wright-like rosettes, maintained their proliferative capacities and produced an equivalent Vimentin-rich matrix unlike that of non-bioprintable bioinks which made for poorer models. In addition, bioprintable bioinks were successfully bioprinted as compartmentalized 3D models in the centimeter scale, which was not feasible using non-bioprintable bioinks. In contrast to non-bioprintable hydrogels, we did not observe contraction in their bioprintable counterparts, which is an advantage for prospective 3D bioprinted models that should attain stable rheological and mechanical properties after bioprinting. By adopting this proposed system for the use of patient-derived primary tumor cells, the approach could be introduced as a first line strategy in precision medicine for testing the response of neuroblastoma cells to drugs, especially when disease progresses rapidly or patients do not respond to actual therapy regimens.

Bartonella quintana and Typhus Group Rickettsiae Exposure among Homeless Persons, Bogotá, Colombia.

In 2015, we investigated Bartonella quintana and typhus group rickettsiae in body lice from homeless persons in Bogotá, Colombia. We found B. quintana-infected body lice and seroprevalence of this microorganism in 19% of homeless persons and typhus group rickettsiae in 56%. Public health professionals should start preemptive measures and active vector control.

Marrow-isolated adult multilineage inducible cells embedded within a biologically-inspired construct promote recovery in a mouse model of peripheral vascular disease.

Peripheral vascular disease is one of the major vascular complications in individuals suffering from diabetes and in the elderly that is associated with significant burden in terms of morbidity and mortality. Stem cell therapy is being tested as an attractive alternative to traditional surgery to prevent and treat this disorder. The goal of this study was to enhance the protective and reparative potential of marrow-isolated adult multilineage inducible (MIAMI) cells by incorporating them within a bio-inspired construct (BIC) made of two layers of gelatin B electrospun nanofibers. We hypothesized that the BIC would enhance MIAMI cell survival and engraftment, ultimately leading to a better functional recovery of the injured limb in our mouse model of critical limb ischemia compared to MIAMI cells used alone. Our study demonstrated that MIAMI cell-seeded BIC resulted in a wide range of positive outcomes with an almost full recovery of blood flow in the injured limb, thereby limiting the extent of ischemia and necrosis. Functional recovery was also the greatest when MIAMI cells were combined with BICs, compared to MIAMI cells alone or BICs in the absence of cells. Histology was performed 28 days after grafting the animals to explore the mechanisms at the source of these positive outcomes. We observed that our critical limb ischemia model induces an extensive loss of muscular fibers that are replaced by intermuscular adipose tissue (IMAT), together with a highly disorganized vascular structure. The use of MIAMI cells-seeded BIC prevented IMAT infiltration with some clear evidence of muscular fibers regeneration.

Effect of postharvest UV-C treatment on the bacterial diversity of Ataulfo mangoes by PCR-DGGE, survival of E. coli and antimicrobial activity.

Since Mexico is the second largest exporter of mangoes, its safety assurance is essential. Research in microbial ecology and knowledge of complex interactions among microbes must be better understood to achieve maximal control of pathogens. Therefore, we investigated the effect of UV-C treatments on bacterial diversity of the Ataulfo mangoes surface using PCR-DGGE analysis of variable region V3 of 16S rRNA genes, and the survival of E. coli, by plate counting. The UV-C irradiation reduced the microbial load on the surface of mangoes immediately after treatment and the structure of bacterial communities was modified during storage. We identified the key members of the bacterial communities on the surface of fruits, predominating Enterobacter genus. Genera as Lactococcus and Pantoea were only detected on the surface of non-treated (control) mangoes. This could indicate that these genera were affected by the UV-C treatment. On the other hand, the treatment did not have a significant effect on survival of E. coli. However, genera that have been recognized as antagonists against foodborne pathogens were identified in the bands patterns. Also, phenolic compounds were determined by HPLC and antimicrobial activity was assayed according to the agar diffusion method. The main phenolic compounds were chlorogenic, gallic, and caffeic acids. Mango peel methanol extracts (UV-C treated and control mangoes) showed antimicrobial activity against strains previously isolated from mango, detecting significant differences (P < 0.05) among treated and control mangoes after 4 and 12 days of storage. Ps. fluorescens and Ps. stutszeri were the most sensitive.

Variables sociodemográficas relacionadas al síndrome de Burnout en docentes de colegios distritales / Demographic variables related to teacher Burnout syndrome in school district

La presente investigación tuvo como finalidad identificar las variables sociodemográficas relacionadas al Síndrome de Burnout (BO) en docentes de colegios distritales de la localidad de Usaquén, Bogotá. Es una investigación descriptiva con un diseño correlacional-comparativo; se contó con la participación de 251 docentes, seleccionados por muestreo aleatorio simple, quienes respondieron el Inventario de Burnout de Maslach (MBI) y un cuestionario de datos sociodemográficos. Dentro de los resultados se identificó que las variables estrato socioeconómico, horas de trabajo, número de estudiantes, tiempo en el cargo y sección, muestran asociación significativa con las dimensiones de agotamiento emocional y realización personal.

The objective of this research was to identify the levels of BO and demographic variables related with the syndrome in teachers of district schools in Bogota. Therefore, this research was descriptive and used a correlational-comparative design, just as with the participation of 251 teachers who were selected through simple random sampling. Then they responded to the Maslach Burnout Inventory (MBI) and a demographic questionnaire. With respect to the results achieved show that there is a significant association between the three dimensions of BO, especially in the emotional exhaustion and in the personal and the socio-demographic variables are associated with the same socioeconomic status, hours of work, the number of students, time in office and the section in which they work.

Sepsis peritoneal: características del paciente relaparotomizado. Incidencia-oportunidad-factores pronósticos / Peritoneal sepsis: characteristics of relaparotomy patients. Incidence-opportunity-factors involved

Los pacientes con sepsis severa de origen abdomino-peritoneal requieren frecuentemente reintervenciones, persistiendo con una elevada morbimortalidad. Su manejo terapéutico es dificultoso y controvertido, con estudios que consideran poblaciones poco homogéneas. Se realizó un análisis retrospectivo durante un período de cinco años. Se estudiaron un total de 55 pacientes con sepsis abdominal severa que requirieron al menos una relaparotomia. Analizamos la incidencia, las manifestaciones clínicas que orientan a una relaparotomía positiva, la mortalidad y los factores pronósticos. La ausencia de disfunción multiorgánica (DMO) constituyó un criterio de exclusión. Se realizaron un total de 121 relaparotomías, de las cuales 17 (14 por ciento) fueron en blanco. La presencia de síntomas prolongados, la realización de anastomosis gastrointestinal y/o la presencia de DMO al momento de relaparotomizar al paciente, se asociaron menos frecuentemente a relaparotomías en blanco (p<0,05). Los signos locales no resultaron buenos indicadores de la oportunidad de reintervenir. Al comparar relaparotomía programada vs. a demanda no encontramos diferencias en cuanto al número de relaparotomías, estancia media de los pacientes y mortalidad. La mortalidad cruda fue de 76 por ciento y la relacionada fue de 55 por ciento. La edad mayor de 70 años, la puntuación A.P.A.C.H.E. II mayor de 17 y la presencia de 3 o más disfunciones se asociaron significativamente a una mayor mortalidad cercana al 90 por ciento. Concluimos que dada la alta mortalidad de los pacientes con 3 o más disfunciones, una estrategia para mejorar la mortalidad es reoperar en forma precoz a los pacientes con 1 ó 2 disfunciones, en particular los que presentan síntomas prolongados y/o anastomosis gastrointestinal.

¿Cuál es la duración adecuada del tratamiento antimicrobiano en la neumonía asociada a la ventilación? / Which is the adecuate duration of treatment of ventilator associated pneumonia?

Fundamento: el empleo muy frecuente de antimicrobianos -especialmente de amplio espectro- en un área determinada incrementa sin duda alguna la emergencia de patógenos multirresistentes. Quizá el mayor factor de uso masivo de antibióticos de amplio espectro en una unidad de cuidados intensivos (UCI) sea su empleo para tratar la neumonía asociada a la ventilación (NAV). Sin embargo, no hay pautas claras en cuanto a la duración óptima del tratamiento en la NAV. Objetivo: identificar publicaciones en que se mencione la duración del tratamiento para la NAV, analizar los resultados obtenidos y los fundamentos de los autores para mantener los antibióticos durante el tiempo que se comunica. Identificar si en algún caso se concluye en forma valida que un período de tratamiento es superior a otro. Método: revisión de consensos y análisis de publicaciones en las que se estudió la duración del tratamiento en forma indirecta o más detalladamente. Resultados: en 10 publicaciones, que incluyeron 1.347 episodios de NAV, la duración del tratamiento antibiótico osciló entre 7 y 33 días. El período más frecuentemente encontrado osciló entre 9 y 12 días. En general, las NAV por Pseudomonas aeruginosa recibieron tratamiento más prologado. Los factores de riesgo para falla terapéutica y recurrencia fueron: NAV producidas por Pseudomonas aeruginosa, un puntaje APACHE II elevado, diferencia alvéolo-arterial de oxígeno aumentada, bacteriemia, desnutrición, presencia de síndrome de distrés respiratorio agudo y enfermedad pulmonar obstructiva crónica. Conclusiones: Un tratamiento de ocho días parece suficiente para microorganismos que no tengan o no se acompañen de factores de riesgo para falla terapéutica. Otro más prolongado -pero no mayor a 14 días- parecería adecuado en el resto de las NAV, incluyendo aquellas producidas por Pseudomonas aeruginosa

Neumonía asociada a la ventilación. Estrategia empírica precoz versus estrategia específica en el tratamiento antibiótico. Datos preliminares / Ventilator associated pneumonia. Early empirical strategy versus specific strategy in antibiotic therapy. Preliminary data

La mejor estrategia terapéutica para el manejo de la neumonía asociada a la ventilación (NAV) permanece controvertida. Los objetivos de este trabajo fueron: 1)comparar la estrategia empírica precoz (EEP) versus estrategia específica (EE); 2)identificar qué grupo de pacientes se beneficia con el inicio precoz de una terapia antimicrobiana y cuál grupo podría esperar un tratamiento específico. Material y método: el estudio fue realizado entre setiembre del año 2000 y enero del 2002 en la Unidad de Cuidados Intensivos (UCI) del Hospital Pasteur y la UCI del Hospital Policial. Se incluyeron todos los pacientes ventilados por un período 48 horas que tuvieron sospecha de estar desarrollando una NAV. Tipo de estudio: prospectivo, observacional.Resultados: 123 pacientes fueron enrolados por tener sospecha clínica de NAV; de éstos se analizaron finalmente 69 NAV confirmadas de las cuales 36 se manejaron con EEP y 33 con EE. Los dos grupos fueron comparados a través de 20 variables. La mortalidad atribuible con EEP fue de 17,5 por ciento y para la EE de 26,4 por ciento. La mortalidad cruda con EEP fue de 44 por ciento (n=16) y con EE 57 por ciento (n=19) (p=NS). No encontramos diferencias significativas con las dos estrategias al analizar estadía en la unidad, duración de la ARM, complicaciones, no curación y falla terapéutica. Se utilizaron 12 variables para un análisis univariado, valorando EEP y EE en dos grupos: los que presentaron buena evolución y mala evolución encontrando una asociación significativa entre el grupo con EE que tuvo mala evolución con la demora mayor a las 48 horas en iniciar un antibiótico (p=0,034). El shock séptico se asoció con mala evolución en ambos grupos, EE vs EEP (p=0,0036 y p= 0,046 respectivamente). El APACHE II mayor de 18 al diagnóstico de la neumonía, se asoció en el análisis de regresión logística con mayor mortalidad. Conclusiones: nuestros resultados sugieren que no hay diferencias entre EEP y EE en cuanto a mortalidad y resultados secundarios. Si se demora más de 48 horas en instaurar un tratamiento antibiótico los pacientes van a tener peor evolución. Pensamos que la EE puede ayudar a minimizar el uso innecesario de antimicrobianos sin agregar mortalidad al enfermo