Influence of biomaterial nanotopography on the adhesive and elastic properties of Staphylococcus aureus cells

Despite the well-known beneficial effects of biomaterial nanopatterning on host tissue integration, the influence of controlled nanoscale topography on bacterial colonisation and infection remains unknown. Therefore, the aim of the present study was to determine the nanoscale effect of surface nanopatterning on biomaterial colonisation by S. aureus, utilising AFM nanomechanics and single-cell force spectroscopy (SCFS). Nanoindentation of S. aureus bound to planar (PL) and nanopatterned (SQ) polycarbonate (PC) surfaces suggested two distinct areas of mechanical properties, consistent with a central bacterial cell surrounded by a capsullar component. Nevertheless, no differences in elastic moduli were found between bacteria bound to PL and SQ, suggesting a minor role of nanopatterning in bacterial cell elasticity. Furthermore, SCFS demonstrated increased adhesion forces and work between S. aureus and SQ surfaces at 0 s and 1 s contact times. Although WLC modelling showed similarities in contour lengths for attachment to both surfaces, Poisson analysis suggests increased short-range forces for the S. aureus–SQ interactions. In the case of S. aureus–PL, long-range forces were found to not only be dominant but also repulsive in nature, which may help explain the reduced adhesion forces observed during AFM probing. In conclusion, although surface nanopatterning does not significantly influence the elasticity of attached bacterial cells, it was found to promote the early-adhesion of S. aureus cells to the biomaterial surface

Probing the nanoadhesion of Streptococcus sanguinis to titanium implant surfaces by atomic force microscopy

The authors would kindly like to thank the BecasChile PhD Scholarship Programme for funding this research

Influence of biomaterial nanotopography on the adhesive and elastic properties of Staphylococcus aureus cells

Despite the well-known beneficial effects of biomaterial nanopatterning on host tissue integration, the influence of controlled nanoscale topography on bacterial colonisation and infection remains unknown. Therefore, the aim of the present study was to determine the nanoscale effect of surface nanopatterning on biomaterial colonisation by S. aureus, utilising AFM nanomechanics and single-cell force spectroscopy (SCFS). Nanoindentation of S. aureus bound to planar (PL) and nanopatterned (SQ) polycarbonate (PC) surfaces suggested two distinct areas of mechanical properties, consistent with a central bacterial cell surrounded by a capsullar component. Nevertheless, no differences in elastic moduli were found between bacteria bound to PL and SQ, suggesting a minor role of nanopatterning in bacterial cell elasticity. Furthermore, SCFS demonstrated increased adhesion forces and work between S. aureus and SQ surfaces at 0 s and 1 s contact times. Although WLC modelling showed similarities in contour lengths for attachment to both surfaces, Poisson analysis suggests increased short-range forces for the S. aureus–SQ interactions. In the case of S. aureus–PL, long-range forces were found to not only be dominant but also repulsive in nature, which may help explain the reduced adhesion forces observed during AFM probing. In conclusion, although surface nanopatterning does not significantly influence the elasticity of attached bacterial cells, it was found to promote the early-adhesion of S. aureus cells to the biomaterial surface

The Effect of City Conditions on Youth Violence in Mexico A Spatial Econometric Analysis by Metropolitan Area

Using Mexico s Social Cohesion Survey for the Prevention of Violence and Crime ECOPRED 2014 and the Mexican Intercensal Population Survey CONTEO 2015 this paper analyses the characteristics and environment factors that influence the violent behavior of young people aged 14 to 24 years within the 47 largest Mexican cities The existence of spatial correlation between Mexican cities is corroborated and after controlling for it it is found that factors related to addictions drug use by young people and their families and a violent environment around the young being bullied robbed or having violent friends neighbors coworkers or classmates are positively related to the percentage of young people who shout hit objects hit people carry weapons or have been arrested Public policies to reduce the use of drugs and to improve the environment where young people live mainly in their neighborhoods schools and jobs will have a direct effect on reducing the violent behavior of young people And given the confirmed existence of spatial effects coordinated efforts between nearby cities could multiply the impact of such public policie

The ROCK inhibitor Fasudil prevents chronic restraint stress-induced depressive-like behaviors and dendritic spine loss in rat hippocampus

Indexación: Web of Science; Scopus.Background: Dendritic arbor simplification and dendritic spine loss in the hippocampus, a limbic structure implicated in mood disorders, are assumed to contribute to symptoms of depression. These morphological changes imply modifications in dendritic cytoskeleton. Rho GTPases are regulators of actin dynamics through their effector Rho kinase. We have reported that chronic stress promotes depressive-like behaviors in rats along with dendritic spine loss in apical dendrites of hippocampal pyramidal neurons, changes associated with Rho kinase activation. The present study proposes that the Rho kinase inhibitor Fasudil may prevent the stress-induced behavior and dendritic spine loss. Methods: Adult male Sprague-Dawley rats were injected with saline or Fasudil (i.p., 10 mg/kg) starting 4 days prior to and maintained during the restraint stress procedure (2.5 h/d for 14 days). Nonstressed control animals were injected with saline or Fasudil for 18 days. At 24 hours after treatment, forced swimming test, Golgi-staining, and immuno-western blot were performed. Results: Fasudil prevented stress-induced immobility observed in the forced swimming test. On the other hand, Fasudiltreated control animals showed behavioral patterns similar to those of saline-treated controls. Furthermore, we observed that stress induced an increase in the phosphorylation of MYPT1 in the hippocampus, an exclusive target of Rho kinase. This change was accompanied by dendritic spine loss of apical dendrites of pyramidal hippocampal neurons. Interestingly, increased pMYPT1 levels and spine loss were both prevented by Fasudil administration. Conclusion: Our findings suggest that Fasudil may prevent the development of abnormal behavior and spine loss induced by chronic stress by blocking Rho kinase activity.https://academic.oup.com/ijnp/article/20/4/336/263217

Mineralizaciones de hierro en el travertino de Lanjarón (Granada)

Las mineralizaciones de hierro y manganeso del travertino de Lanjarón (Granada) están constituídas fundamentalmente por goethita y ferrihidrita, junto a hidróxidos amorfos de hierro y óxidos de manganeso. El travertino esencialmente calcítico contiene eventualmente aragonito.El depósito de estos materiales está relacionado con el quimismo de las aguas minero-medicinales de la zona; así como, con la presencia de bacterias de los géneros Gallionella y Leptothrix

Mineralizaciones de hierro en el travertino de Lanjarón (Granada)

[EN] The iron and manganese mineralizations in the travertine of Lanjarón (Granada province) fundarnentally consist of goethite and ferrihydrite together with amorphous iron hidroxides and manganese oxides. The travertine which basically calcitic ocasionally contains aragonite. Deposition of these matenals is related to the chemical characteristics of the mineralized spring waters of this area and with the presence of Gallionella and ieptothrix bacteria.[ES] Las mineralizaciones de hierro y manganeso del travertino de Lanjarón (Granada) están constituidas fundamentalmente por goethita y femhidrita, junto a hidróxidos amorfos de hierro y óxidos de manganeso. El travertino esenciak mente calcitico contiene eventualmente aragonito. El depósito de estos materiales está relacionado con el quimismo de las aguas mineremedicinales de la zona; así como, con la presencia de bacterias de los géneros Gallionella y Leptothrix.Peer reviewe

Overestimation of Vitamin a Supplementation Coverage from District Tally Sheets Demonstrates Importance of Population-Based Surveys for Program Improvement: Lessons from Tanzania.

Tanzania has conducted a national twice-yearly Vitamin A supplementation (VAS) campaign since 2001. Administrative coverage rates based on tally sheets consistently report >90% coverage; however the accuracy of these rates are uncertain due to potential errors in tally sheets and their aggregation, incomplete or inaccurate reporting from distribution sites, and underestimating the target population. The post event coverage survey in Mainland Tanzania sought to validate tally-sheet based national coverage estimates of VAS and deworming for the June 2010 mass distribution round, and to characterize children missed by the national campaign. WHO/EPI randomized cross-sectional cluster sampling methodology was adapted for this study, using 30 clusters by 40 individuals (n = 1200), in addition to key informant interviews. Households with children 6-59 months of age were included in the study (12-59 months for deworming analysis). Chi-squared tests and logistic regression analysis were used to test differences between children reached and not reached by VAS. Data was collected within six weeks of the June 2010 round. A total of 1203 children, 58 health workers, 30 village leaders and 45 community health workers were sampled. Preschool VAS coverage was 65% (95% CI: 62.7-68.1), approximately 30% lower than tally-sheet coverage estimates. Factors associated with not receiving VAS were urban residence [OR = 3.31; p = 0.01], caretakers who did not hear about the campaign [OR = 48.7; p<0.001], and Muslim households [OR<3.25; p<0.01]. There were no significant differences in VAS coverage by child sex or age, or maternal age or education. Coverage estimation for vitamin A supplementation programs is one of most powerful indicators of program success. National VAS coverage based on a tally-sheet system overestimated VAS coverage by ∼30%. There is a need for representative population-based coverage surveys to complement and validate tally-sheet estimates

Quantitative nanohistological investigation of scleroderma: An atomic force microscopy-based approach to disease characterization

Scleroderma (or systemic sclerosis, SSc) is a disease caused by excess crosslinking of collagen. The skin stiffens and becomes painful, while internally, organ function can be compromised by the less elastic collagen. Diagnosis of SSc is often only possible in advanced cases by which treatment time is limited. A more detailed analysis of SSc may provide better future treatment options and information of disease progression. Recently, the histological stain picrosirius red showing collagen register has been combined with atomic force microscopy (AFM) to study SSc. Skin from healthy individuals and SSc patients was biopsied, stained and studied using AFM. By investigating the crosslinking of collagen at a smaller hierarchical stage, the effects of SSc were more pronounced. Changes in morphology and Young’s elastic modulus were observed and quantified; giving rise to a novel technique, we have termed “quantitative nanohistology”. An increase in nanoscale stiffness in the collagen for SSc compared with healthy individuals was seen by a significant increase in the Young’s modulus profile for the collagen. These markers of stiffer collagen in SSc are similar to the symptoms experienced by patients, giving additional hope that in the future, nanohistology using AFM can be readily applied as a clinical tool, providing detailed information of the state of collagen

Phenotypic Properties of Collagen in Dentinogenesis Imperfecta Associated with Osteogenesis Imperfecta

Introduction: Dentinogenesis imperfecta type 1 (OIDI) is considered a relatively rare genetic disorder (1:5000 to 1:45,000) associated with osteogenesis imperfecta. OIDI impacts the formation of collagen fibrils in dentin, leading to morphological and structural changes that affect the strength and appearance of teeth. However, there is still a lack of understanding regarding the nanoscale characterization of the disease, in terms of collagen ultrastructure and mechanical properties. Therefore, this research presents a qualitative and quantitative report into the phenotype and characterization of OIDI in dentin, by using a combination of imaging, nanomechanical approaches. Methods: For this study, 8 primary molars from OIDI patients and 8 primary control molars were collected, embedded in acrylic resin and cut into longitudinal sections. Sections were then demineralized in 37% phosphoric acid using a protocol developed in-house. Initial experiments demonstrated the effectiveness of the demineralization protocol, as the ATR-FTIR spectral fingerprints showed an increase in the amide bands together with a decrease in phosphate content. Structural and mechanical analyses were performed directly on both the mineralized and demineralized samples using a combination of scanning electron microscopy, atomic force microscopy, and Wallace indentation. Results: Mesoscale imaging showed alterations in dentinal tubule morphology in OIDI patients, with a reduced number of tubules and a decreased tubule diameter compared to healthy controls. Nanoscale collagen ultrastructure presented a similar D-banding periodicity between OIDI and controls. Reduced collagen fibrils diameter was also recorded for the OIDI group. The hardness of the (mineralized) control dentin was found to be significantly higher (p<0.05) than that of the OIDI (mineralized) dentine. Both the exposed peri- and intratubular dentinal collagen presented bimodal elastic behaviors (Young's moduli). The control samples presented a stiffening of the intratubular collagen when compared to the peritubular collagen. In case of the OIDI, this stiffening in the collagen between peri- and intratubular dentinal collagen was not observed and the exposed collagen presented overall a lower elasticity than the control samples. Conclusion: This study presents a systematic approach to the characterization of collagen structure and properties in OIDI as diagnosed in dentin. Structural markers for OIDI at the mesoscale and nanoscale were found and correlated with an observed lack of increased elastic moduli of the collagen fibrils in the intratubular OIDI dentin. These findings offer an explanation of how structural changes in the dentin could be responsible for the failure of some adhesive restorative materials as observed in patients affected by OIDI