Nanoscale Dynamics of Streptococcal Adhesion to AGE-Modified Collagen.

The adhesion of initial colonizers such as Streptococcus mutans to collagen is critical for dentinal and root caries progression. One of the most described pathological and aging-associated changes in collagen-including dentinal collagen-is the generation of advanced glycation end-products (AGEs) such as methylglyoxal (MGO)-derived AGEs. Despite previous reports suggesting that AGEs alter bacterial adhesion to collagen, the biophysics driving oral streptococcal attachment to MGO-modified collagen remains largely understudied. Thus, the aim of this work was to unravel the dynamics of the initial adhesion of S. mutans to type I collagen in the presence and absence of MGO-derived AGEs by employing bacterial cell force spectroscopy with atomic force microscopy (AFM). Type I collagen gels were treated with 10 mM MGO to induce AGE formation, which was characterized with microscopy and enzyme-linked immunosorbent assay. Subsequently, AFM cantilevers were functionalized with living S. mutans UA 159 or Streptococcus sanguinis SK 36 cells and probed against collagen surfaces to obtain force curves displaying bacterial attachment in real time, from which the adhesion force, number of events, Poisson analysis, and contour and rupture lengths for each individual detachment event were computed. Furthermore, in silico computer simulation docking studies between the relevant S. mutans UA 159 collagen-binding protein SpaP and collagen were computed, in the presence and absence of MGO. Overall, results showed that MGO modification increased both the number and adhesion force of single-unbinding events between S. mutans and collagen, without altering the contour or rupture lengths. Both experimental and in silico simulations suggest that this effect is due to increased specific and nonspecific forces and interactions between S. mutans UA 159 and MGO-modified collagen substrates. In summary, these results suggest that collagen alterations due to aging and glycation may play a role in early bacterial adherence to oral tissues, associated with conditions such as aging or chronic hyperglycemia, among others.

Nanomechanical and Molecular Characterization of Aging in Dentinal Collagen.

Methylglyoxal (MGO) is an important molecule derived from glucose metabolism with the capacity of attaching to collagen and generating advanced glycation end products (AGEs), which accumulate in tissues over time and are associated with aging and diseases. However, the accumulation of MGO-derived AGEs in dentin and their effect on the nanomechanical properties of dentinal collagen remain unknown. Thus, the aim of the present study was to quantify MGO-based AGEs in the organic matrix of human dentin as a function of age and associate these changes with alterations in the nanomechanical and ultrastructural properties of dentinal collagen. For this, 12 healthy teeth from <26-y-old and >50-y-old patients were collected and prepared to obtain crown and root dentin discs. Following demineralization, MGO-derived AGEs were quantified with a competitive ELISA. In addition, atomic force microscopy nanoindentation was utilized to measure changes in elastic modulus in peritubular and intertubular collagen fibrils. Finally, principal component analysis was carried out to determine aging profiles for crown and root dentin. Results showed an increased presence of MGO AGEs in the organic matrix of dentin in the >50-y-old specimens as compared with the <26-y-old specimens in crown and root. Furthermore, an increase in peritubular and intertubular collagen elasticity was observed in the >50-y-old group associated with ultrastructural changes in the organic matrix as determined by atomic force microscopy analysis. Furthermore, principal component analysis loading plots suggested different "aging profiles" in crown and root dentin, which could have important therapeutic implications in restorative and adhesive dentistry approaches. Overall, these results demonstrate that the organic matrix of human dentin undergoes aging-related changes due to MGO-derived AGEs with important changes in the nanomechanical behavior of collagen that may affect diagnostic and restorative procedures in older people.

Dependency of hydration and growth conditions on the mechanical properties of oral biofilms.

Within the oral cavity, dental biofilms experience dynamic environments, in part due to changes in dietary content, frequency of intake and health conditions. This can impact bacterial diversity and morpho-mechanical properties. While phenotypic properties of oral biofilms are closely related to their composition, these can readily change according to dynamic variations in the growth environment and nutrient availability. Understanding the interlink between phenotypic properties, variable growth conditions, and community characterization is an essential requirement to develop structure-property relationships in oral-biofilms. In this study, the impact of two distinct growth media types with increasing richness on the properties of oral biofilms was assessed through a new combination of in-vitro time-lapse biophysical methods with microbiological assays. Oral biofilms grown in the enriched media composition presented a decrease in their pH, an increase in soluble EPS production, and a severe reduction in bacterial diversity. Additionally, enriched media conditions presented an increase in biofilm volumetric changes (upon hydration) as well as a reduction in elastic modulus upon indentation. With hydration time considered a major factor contributing to changes in biofilm mechanical properties, we have shown that it is less associated than media richness. Future investigations can now use this time-lapse approach, with a clearer focus on the extracellular matrix of oral biofilms dictating their morpho-mechanical properties.

Modulatory Effect of Glycated Collagen on Oral Streptococcal Nanoadhesion.

Biofilm-mediated oral diseases such as dental caries and periodontal disease remain highly prevalent in populations worldwide. Biofilm formation initiates with the attachment of primary colonizers onto surfaces, and in the context of caries, the adhesion of oral streptococci to dentinal collagen is crucial for biofilm progression. It is known that dentinal collagen suffers from glucose-associated crosslinking as a function of aging or disease; however, the effect of collagen crosslinking on the early adhesion and subsequent biofilm formation of relevant oral streptococci remains unknown. Therefore, the aim of this work was to determine the impact of collagen glycation on the initial adhesion of primary colonizers such as Streptococcus mutans UA159 and Streptococcus sanguinis SK 36, as well as its effect on the early stages of streptococcal biofilm formation in vitro. Type I collagen matrices were crosslinked with either glucose or methylglyoxal. Atomic force microscopy nanocharacterization revealed morphologic and mechanical changes within the collagen matrix as a function of crosslinking, such as a significantly increased elastic modulus in crosslinked fibrils. Increased nanoadhesion forces were observed for S. mutans on crosslinked collagen surfaces as compared with the control, and retraction curves obtained for both streptococcal strains demonstrated nanoscale unbinding behavior consistent with bacterial adhesin-substrate coupling. Overall, glucose-crosslinked substrates specifically promoted the initial adhesion, biofilm formation, and insoluble extracellular polysaccharide production of S. mutans, while methylglyoxal treatment reduced biofilm formation for both strains. Changes in the adhesion behavior and biofilm formation of oral streptococci as a function of collagen glycation could help explain the biofilm dysbiosis seen in older people and patients with diabetes. Further studies are necessary to determine the influence of collagen crosslinking on the balance between acidogenic and nonacidogenic streptococci to aid in the development of novel preventive and therapeutic treatment against dental caries in these patients.

A Multi-scale Biophysical Approach to Develop Structure-Property Relationships in Oral Biofilms.

Over the last 5-10 years, optical coherence tomography (OCT) and atomic force microscopy (AFM) have been individually applied to monitor the morphological and mechanical properties of various single-species biofilms respectively. This investigation looked to combine OCT and AFM as a multi-scale approach to understand the role sucrose concentration and age play in the morphological and mechanical properties of oral, microcosm biofilms, in-vitro. Biofilms with low (0.1% w/v) and high (5% w/v) sucrose concentrations were grown on hydroxyapatite (HAP) discs from pooled human saliva and incubated for 3 and 5 days. Distinct mesoscale features of biofilms such as regions of low and high extracellular polymeric substances (EPS) were identified through observations made by OCT. Mechanical analysis revealed increasing sucrose concentration decreased Young's modulus and increased cantilever adhesion (p < 0.0001), relative to the biofilm. Increasing age was found to decrease adhesion only (p < 0.0001). This was due to mechanical interactions between the indenter and the biofilm increasing as a function of increased EPS content, due to increasing sucrose. An expected decrease in EPS cantilever contact decreased adhesion due to bacteria proliferation with biofilm age. The application OCT and AFM revealed new structure-property relationships in oral biofilms, unattainable if the techniques were used independently.

Early Adhesion of Candida albicans onto Dental Acrylic Surfaces.

Denture-associated stomatitis is a common candidal infection that may give rise to painful oral symptoms, as well as be a reservoir for infection at other sites of the body. As poly (methyl methacrylate) (PMMA) remains the main material employed in the fabrication of dentures, the aim of this research was to evaluate the adhesion of Candida albicans cells onto PMMA surfaces by employing an atomic force microscopy (AFM) single-cell force spectroscopy (SCFS) technique. For experiments, tipless AFM cantilevers were functionalized with PMMA microspheres and probed against C. albicans cells immobilized onto biopolymer-coated substrates. Both a laboratory strain and a clinical isolate of C. albicans were used for SCFS experiments. Scanning electron microscopy (SEM) and AFM imaging of C. albicans confirmed the polymorphic behavior of both strains, which was dependent on growth culture conditions. AFM force-spectroscopy results showed that the adhesion of C. albicans to PMMA is morphology dependent, as hyphal tubes had increased adhesion compared with yeast cells ( P < 0.05). C. albicans budding mother cells were found to be nonadherent, which contrasts with the increased adhesion observed in the tube region. Comparison between strains demonstrated increased adhesion forces for a clinical isolate compared with the lab strain. The clinical isolate also had increased survival in blood and reduced sensitivity to complement opsonization, providing additional evidence of strain-dependent differences in Candida-host interactions that may affect virulence. In conclusion, PMMA-modified AFM probes have shown to be a reliable technique to characterize the adhesion of C. albicans to acrylic surfaces.

Nanoadhesion of Staphylococcus aureus onto Titanium Implant Surfaces.

Adhesion of bacteria to dental implant surfaces is the critical initial step in the process of biofilm colonization; however, the specific nanoadhesive interactions occurring during the first contact between bacterial cells and biomaterial substrates remain poorly understood. In this report, we utilize single-cell force spectroscopy to characterize the dynamics of the initial interaction between living Staphylococcus aureus cells and machined titanium surfaces at the nanoscale. Values for maximum adhesion force were found to increase from 0-s (-0.27 ± 0.30 nN) to 60-s (-9.15 ± 0.78 nN) surface delays, with similar results observed for total adhesion work (7.39 ± 2.38 and 988.06 ± 117.08 aJ, respectively). Single unbinding events observed at higher surface delays were modeled according to the wormlike chain model, obtaining molecular contour-length predictions of 314.06 ± 9.27 nm. Average single-bond rupture forces of -0.95 ± 0.04 nN were observed at increased contact times. Short- and long-range force components of bacterial adhesion were obtained by Poisson analysis of single unbinding event peaks, yielding values of -0.75 ± 0.04 and -0.58 ± 0.15 nN, respectively. Addition of 2-mg/mL chlorhexidine to the buffer solution resulted in the inhibition of specific adhesive events but an increased overall adhesion force and work. These results suggest that initial attachment of S. aureus to smooth titanium is mostly mediated by short-range attractive forces observed at higher surface delays.

Single-bacterium nanomechanics in biomedicine: unravelling the dynamics of bacterial cells.

The use of the atomic force microscope (AFM) in microbiology has progressed significantly throughout the years since its first application as a high-resolution imaging instrument. Modern AFM setups are capable of characterizing the nanomechanical behaviour of bacterial cells at both the cellular and molecular levels, where elastic properties and adhesion forces of single bacterium cells can be examined under different experimental conditions. Considering that bacterial and biofilm-mediated infections continue to challenge the biomedical field, it is important to understand the biophysical events leading towards bacterial adhesion and colonization on both biological and non-biological substrates. The purpose of this review is to present the latest findings concerning the field of single-bacterium nanomechanics, and discuss future trends and applications of nanoindentation and single-cell force spectroscopy techniques in biomedicine.

Cáncer de mama en Chile: mortalidades comparada: niveles nacional, regional y comunal, 1990-2011: análisis programático / National and regional mortality rates due to breast cancer in Chile from 1990 to 2011

Introducción: Son habituales las variaciones de frecuencia geográfico-poblacionales en muchas enfermedades y países o regiones, diferencias que pueden orientar sobre sus causas. En Chile faltan estudios recientes sobre cáncer de mama con esta perspectiva. Material y Método: Estudio descriptivo-analítico de mortalidad para niveles nacional: 2011 (8.711.546 mujeres), regional o Servicio de Salud Sur-Oriente (SSM-SO) (800.341) y dos comunas, Puente Alto y La Florida (374.886 y 199.243). Se analizaron tasas crudas, ajustadas y específicas por grupos quinquenales de edad, últimos 22 años (1990-2011). Resultados: Tasa cruda de mortalidad nacional sube en forma constante e importante (20 por ciento), de 12-13 por 100.000 hasta 15,7 por 100.000 mujeres (2009). Tasas crudas del SSMSO son más bajas. Mortalidad por cáncer mamario está disminuyendo en las mujeres jóvenes (30-34; 35-39; 40-44; 45-49), excepto las muy jóvenes (25-29) en ambos niveles: nacional y regional. Mortalidad comunal es más alta en comuna de La Florida. Estadíos avanzados III y IV que habían descendido en el SSMSO hasta bajo 20% del total de pacientes han ido subiendo hasta 28,3 por ciento (22,4+5,9) el 2009, cercano al nivel nacional estable del 29-30 por ciento. Esto coincide con alza de su mortalidad, además de hacerse próxima a la del país, comprobando hipótesis. Conclusiones: La creciente mortalidad por cáncer de mama en Chile derivaría de alta frecuencia mantenida de estadíos avanzados y del envejecimiento poblacional. Sin embargo, las mujeres senescentes no están consideradas en el programa nacional. Debería ampliarse pesquisa de este cáncer elevando edad a través de las enfermeras en la atención primaria y estudiar causas del aumento de estadíos avanzados en el SSMSO y sus diferencias comunales.

Background: Population or geographical differences in prevalence are observed for many diseases. These variations may give clues about the causes of the diseases. Aim: To study the geographical distribution of mortality for breast cancer in Chile. Material and Methods: Information was obtained from databases available at the Chilean Ministry of Health and the National Institute of Statistics. Crude and adjusted mortality rates during the period 1990-2011 were calculated according to quinquennial age groups, for two municipalities of Metropolitan Santiago. Results: In the study period, the crude mortality rates increased by 20%, from 12-13/100,000 women in 1990 to 15.7/100,000 women in 2009. Mortality is decreasing in women aged 30 to 49 years. This is not the case for women aged 25 to 29 years. Mortality is higher in La Florida Municipality. In South-Oriental Santiago, the frequency of advanced stages of the disease (III or IV), which initially were reduced to 20%, have steadily increased to 28.3% in 2009, a figure similar to the national frequency of 29 to 30%. This higher frequency of advanced stages coincides with the rise in mortality. Conclusions: The increasing mortality due to breast cancer would be secondary to the high frequency of advanced stages and population aging. However, older women are not considered in the national breast cancer program. Their inclusion should be considered.

Envejecimiento y alta prevalencia de estadios avanzados determinan la creciente mortalidad por cáncer mamario en Chile / Aging and high prevalence of advanced stages determine the increasing breast cancer mortality in Chile

Aims: To test the hypothesis that ages above 54 years not included in the national program and a greater proportion of advanced stages in the public health sector that attends 75 percent of the population, could explain the increasing high mortality rate for this cancer in Chile. Methods: Incidence data provided by the 29 public health services (SNSS) in the country and mortality data from the Ministry of Health were used to analyse the epidemiological situation at the biggest health service (SSMSO), 1.6 million of people, compared with the country, 16 million. Results: Breast cancer was in 2009, last year with information, the first cause of oncologic death in Chilean women with 1,338 deaths and an actual mortality rate of 15.7 per 100,000 women. Deaths for gallbladder and gastric cancers were 1,295 and 1,150 respectively. Mortality for breast cancer in 2009 was 10.4 in the SSMSO. Less advanced stages with a proportion of about 20 percent compared with the country (30 percent) and more prevalent older ages were observed in this health service. Conclusions: Hypothesis is true. Targets of extended age and decreasing of less advanced stages for the country emerge from this study. To integrate levels of medical care in the SNSS and to include examination of breasts jointly with free diagnostic mammographies in women above 54 years old ordered by the nurses responsibles at the national programs of diabetes mellitus and arterial hypertension are recommended aiming to increase compliance of secondary prevention in breast cancer.

Objetivos: Es un estudio retrospectivo, descriptivo y analítico sobre cáncer de mama comparando incidencia nacional, sector público (SNSS) y mortalidad (Chile), últimas dos décadas, con la del Servicio de Salud Sur Oriente de Santiago (SSMSO). La hipótesis de mayores edades y menor frecuencia de estadíos avanzados en el SSMSO explicaría su menor mortalidad. Material y Método: Se utilizan datos de mortalidad del Ministerio de Salud y de incidencia aportados por los 29 Servicios de Salud del país. Resultados: Cáncer de mama aparece el 2009 como primera causa de mortalidad oncológica en la mujer chilena, con 1.338 muertes y tasa de 15,7 por 100.000 mujeres, superando al vesicular con 1.295 y al gástrico con 1.115. Las tasas de mortalidad por cáncer mamario en Chile fueron 12,1; 13,2 y 15,7, años 1991, 2000 y 2009 mientras en el SSMSO fueron más bajas: 11,4; 12,7 y 10,4 en esos años. Entre 30 y 34 por ciento de las pacientes diagnosticadas del SNSS tenía más de 64 años comparado con el SSMSO, donde predominaron con más del 40 por ciento sobre 60 años, entre 1999 y 2009. Los estadíos avanzados, III y IV, presentaron una proporción estable 2001-2009, promedio 29,4 por ciento en el SNSS, mientras bajó progresivamente en el SSMSO hasta 18,3 por ciento el 2007. Discusión y Conclusiones: Se comprueba hipótesis ya que puede atribuirse la menor mortalidad por este cáncer en el SSMSO a menores tasas de estadíos avanzados. Este estudio permite proponer edades sobre 54 años para la pesquisa con mamografía diagnóstica. Además, integrar los niveles de atención médica: primario, secundario, terciario y extender pesquisa a mujeres mayores en programas de hipertensión arterial y diabetes mellitus, incorporando a sus enfermeras.

¿Es posible disminuir la mortalidad por cáncer de mama en Chile?: análisis epidemiológico y programático en la región metropolitana, 2000-2007 / Is it possible to decrease breast cancer mortality in Chile?: an analytical study

This analytical study is aimed to analyze breast cancer mortality in the metropohtan región of Santiago serving something more than 6,000,000 people. The hypothesis is that it is possible to decrease breast cancer mortality in Chile (16 million inhabitants) based on the experience of the metropohtan south orient health service (SSMSO) that represents 10 percent of the Chilean population. A comparative analysis of crude and age-adjusted mortality rates for breast cancer in the six metropolitan health services is produced showing the lowest crude and age-adjusted mortality rate in the SSMSO besides to be lower than the mortality rate for Chile. Furthermore the annual proportions of advanced (III and IV) and incipient breast cancers (in situ and I) are established for the SSMSO showing a proportional decrease of advanced stages and a relevant increase of the incipient ones between 1994 and 2007. The authors think that since the population of the metropolitan región represents more than 40 percent of the Chilean population and includes all the socio economic strata the results observed in the SSMSO, the biggest health service in the region besides having both rural and urban districts, may be considered representative for the country as a whole. The original hypothesis has been thus confirmed: it is possible to decrease breast cancer mortality in Chile.

Se trata un estudio analítico sobre la mortalidad por cáncer de mama en la Región Metropolitana. La hipótesis, en base a la experiencia del Servicio de Salud Metropolitano Sur Oriente (SSMSO), señala que es posible disminuir la mortalidad por este cáncer en Chile, extrapolando la experiencia de este servicio de salud con 1,6 millones de población asignada y 1,1 millones de personas inscritas validadas. Ello significa el 10 por ciento de la población chilena. Se hace un análisis comparado de las mortalidades crudas y ajustadas por edad en los seis servicios de salud metropolitanos, período 2000-2007, además de establecer la proporción anual de cánceres de mama avanzados (III y IV) e incipientes (in situ y I) en el total de cánceres mamarios del SSMSO, período 1994-2007. Los seis servicios en conjunto atienden una población que significa algo más del 40 por ciento de la nacional, además de representar todos sus estratos socio-económicos y étnicos. En consecuencia, la comparación entre ellos puede considerarse válida para el país. Los resultados muestran que el SSMSO tiene la mortalidad por cáncer de mama, tasa cruda y ajustada, más baja de la Región Metropolitana, además de inferior a la nacional. Una razón importante es la disminución proporcional de cánceres avanzados y un aumento importante de los incipientes. El programa para cáncer de mama del SSMSO cumple entonces con su objetivo principal: disminuir la mortalidad por este cáncer, ratificando la hipótesis de este estudio. Además, cumple otros objetivos: eficiencia, buena opinión de usuarias y equidad.

Cáncer de mama en Chile: un aporte clínico y epidemiológico según un registro poblacional metropolitano: 1.485 pacientes / Analysis of 1.485 women treated for breast cancer in two public hospitals

Background: Breast cancer was included as a priority in the Chilean health reform, providing universal and guaranteed access to diagnosis and treatment to all women aged 15 years or more. Aim: To analyze the incidence, staging and survival of breast cancer in a cohort of women. Material and Methods: Retrospective analysis of medical records of women operated for breast cancer between 1994 and 2005 in two public hospitals of Metropolitan Santiago. Incidence rates were calculated using statistical information provided by the Ministry of Health. Results: The clinical records of 1.485 women aged 18 to 99 years (median 55 years), were analyzed. The number of lesions detected in early stages (Tl NO), increased progressively over time. The number of lesions in advanced stages was constant along time, but its proportion decreased progressively. The overall fifteen years survival of operated women was 64 percent. Survival was significantly better among women without lymph node involvement. The incidence rates of breast cancer increased steadily during the study period. Mortality slightly increased during the nineties but is decreasing during the present decade, reaching a rate of 12.2 per 100.000 women during 2005. Conclussion: In this series of patients, the diagnosis of breast cancer in early stages increased in the last decade, resulting in better survival rates.

El objetivo de este estudio es entregar un aporte clínico y epidemiológico al relevante problema del cáncer de mama en Chile, en base al registro poblacional o casuística del Servicio de Salud Metropolitano Sur Oriente (SSMSO). Se analizan 1.485 mujeres atendidas entre 1994 y 2005 en el Hospital Sótero del Río y entre 2003 y 2005 en el Hospital Padre Hurtado. En los resultados se presenta la frecuencia de este cáncer en Chile y nuestro servicio, además de su comparación con otros países. En el SSMSO destaca el incremento progresivo, absoluto y relativo, de cánceres incipientes y la mantención absoluta con disminución relativa de cánceres avanzados. Esto es parecido en los dos hospitales pero inferior a lo observado en las pacientes semi-privadas del Sótero del Río, en las cuales predominan los incipientes. La sobrevida global a 15 años sobrepasa el 63 por ciento y es significativamente mayor en las enfermas sin compromiso linfonodal. La mortalidad por cáncer de mama en el SSMSO se elevó moderadamente durante los 90 pero ha bajado en forma moderada en esta década; actualmente es la más baja de la Región Metropolitana y bastante inferior al promedio nacional. Se plantea la hipótesis de que la razón que explica la baja mortalidad por cáncer de mama en el SSMSO, es su alta proporción de cánceres incipientes lo cual a su vez puede deberse a una buena coordinación con la atención primaria y al aumento de mamografías y ecografías mamarias. La principal conclusión es la utilidad de tener un registro de cáncer.

Detección de cianobacterias y sus toxinas. Una revisión / Cyanobacteria and toxins detection. A review

La creciente eutrofización de los ambientes acuáticos favorece el crecimiento masivo (blooms) de algas, y poblaciones de cianobacterias, capaces de producir potentes toxinas con graves repercusiones en la salud públicas y en la sanidad animal. Más del 50 por ciento de las proliferaciones masivas de cianobacterias son tóxicas. Dentro de una misma especie de cianobacteria, existen cepas que producen toxinas y otras que no las producen. Se hace necesario disponer de métodos que permitan detectar y cuantificar cianobacterias y sus toxinas. Los tradicionales bioensayos en ratón para conocer la toxicidad de una muestra sospechosa, se van sustituyendo por otros bioensayos y diversos métodos in vitro que están demostrando ser eficaces. El avance experimentado en las técnicas inmunológicas y enzimáticas ha facilitado la detección rápida de toxinas mediante el empleo de kits comerciales y no comerciales. Uno de los campos más prometedores de investigación, consiste en la determinación de las secuencias genéticas que diferencian géneros incluso cepas tóxicas, así como otras que codifican para la síntesis de toxinas; métodos que permitirán prever el desarrollo de cianobacterias o sus toxinas. El control y seguimiento de los desarrollos masivos de cianobacterias, es muy importante para gatantizar la calidad del agua. El reconocimiento de los factores ambientales que influyen o desencadenan la aparición de blooms, es otro factor fundamental para la prevención y el control (AU)

Ensayo de ecotoxicidad miniaturizado en Chlorella vulgaris utilizando diferentes parámetros de expresión / Miniaturized ecotoxicity assay with Chlorella vulgaris using differents endpoints

La exigencia actual de valoraciones medioambientales, requiere la utilización de métodos con relación coste/beneficio adecuado. En este trabajo presentamos el desarrollo y utilización de la Fluorescencia como medida de la inhibición del crecimiento, utilizando un monocultivo de Chlorella vulgaris var. Viridis. Se estimó las CI50 48 h de los siguientes compuestos: Glifosato, Amitrol, paraquat, Sulfato de Cobre, 3,4-Dicloroanilina y Cloruro de Cadmio, utilizando la Fluorescencia, la Densidad Celular y la Absorbancia, como parámetros de expresión. Los resultados aportan información sobre efectos fitotóxicos para los herbicidas Glifosato, Amitrol y Paraquat, con CI50 48 h de 100,85, 13, 82 y 0,04 mg/mL respectivamente, que ofrecen CI50 48 h en el mismo orden de magnitud, en cada uno de los compuestos ensayados para Densidad Celular, Absorbancia y Fluorescencia. Se discuten las ventajas que la Fluorescencia tendría frente a los otros parámetros de expresión, en ensayos de ecotoxicidad (AU)

Urinary bombesin-like peptide levels in infants and children with bronchopulmonary dysplasia and cystic fibrosis.

Compared to normal infants and children, there are increased numbers of neuroendocrine cells with bombesin-like peptide (BLP) immunostaining in the lungs of infants and children with bronchopulmonary dysplasia (BPD) and cystic fibrosis (CF). However, there are no data documenting levels of urinary BLP in normal infants and children, or in children with lung disease. We therefore determined the normal developmental pattern for urinary BLP excretion in healthy infants and children, and in infants and children with BPD and CF, and correlated these findings with the subjects' clinical course. We measured urinary BLP levels in 110 subjects: 54 controls, 33 with BPD, and 23 with CF. An age-dependent decline in urinary bombesin levels was evident in the control and BPD subjects, but not in those with CF. There were no statistically significant differences in BLP levels between normal infants and those with BPD. Mean BLP levels were higher in the more immature preterm infants with BPD who required increased ventilatory support. The highest mean BLP levels were documented in BPD infants under age 3 months (882 fmol/mg creatinine), in controls between 3 and 12 months of age (625 fmol/mg creatinine), and in 12-60-month-old CF subjects (486 fmol/mg creatinine). Thus there is an age-dependent decline in BLP levels in controls and BPD, but not in CF. We speculate that the elevated urinary BLP levels in infants and children with BPD and CF may reflect increased pulmonary neuroendocrine cell activity in these conditions, due to the epithelial regenerative response to airway damage and repair.

Urinary levels of bombesin-related peptides in a population sample from northern Italy: potential role in the pathogenesis of chronic obstructive pulmonary disease.

Bombesin-related peptides (BRP) are present in the lung and have various biological functions, including modulation of lung maturation. Many recent studies have suggested that BRP have a pathogenic role in airway wall remodeling in chronic obstructive pulmonary disease. The aim of this cross-sectional survey was to evaluate the distribution of urinary BRP excretion as a indirect marker of pulmonary BRP production and to assess the prevalence of smoking, chronic respiratory symptoms, chronic obstructive pulmonary disease, and asthma in a population sample from northern Italy. Associations between urinary BRP excretion and several respiratory and nonrespiratory variables were also evaluated. The only variable tested that was significantly predictive of high urinary levels of BRP was the presence of respiratory symptoms. In contrast to previous studies, smoking per se was not significantly associated with urinary BRP levels.

Sarcoidosis: an overview for the primary care physician.

Sarcoidosis is a chronic, progressive, generalized granulomatous reticulosis of unknown etiology, involving almost any organ or tissue. This article gives the primary care physician a comprehensive review of sarcoidosis.

Nonconstitutive expression of the gastrin-releasing peptide autocrine growth system in human small cell lung carcinoma NCI-H345 cells.

Constitutive, unregulated autocrine growth is thought to be an important mechanism whereby cancer cells gain a proliferative advantage over nonmalignant cells. The question addressed here was whether the autocrine growth system for gastrin-releasing peptide (GRP) in human small cell lung carcinoma cells is, in fact, always expressed in a constitutive, unregulated fashion. Lag, rapid, and plateau growth states were defined for small cell lung carcinoma NCI-H345 cells based on periods during which they expressed different growth rates after plating as single cell suspensions. Immunoreactive GRP in the conditioned medium and in NCI-H345 cells harvested during each of these growth states, as well as cell DNA content, GRP mRNA expression, specific 125I-GRP uptake, specific 125I-GRP binding to solubilized membranes, and GRP and neuromedin B receptor mRNA expression by reverse transcription-PCR were analyzed. Maximal levels of GRP expression were observed during the lag growth state, with the highest concentration of immunoreactive GRP in the conditioned medium during the rapid growth state. Specific 125I-GRP uptake and binding were also highest during the lag growth state; however, GRP receptor mRNA did not significantly change. In contrast to prevailing concepts, these studies support the conclusion that the expression of the GRP autocrine growth system in NCI-H345 cells is indeed regulated. Furthermore, the components are maximally expressed before rapid growth begins, suggesting that other mechanisms are activated to support the actual proliferation.