Effect of sterilization on 3-point dynamic response to in vitro bending of an Mg implant

Abstract Background The aim of the study is to characterize a biomedical magnesium alloy and highlighting the loss of mechanical integrity due to the sterilization method. Ideally, when using these alloys is to delay the onset of degradation so that the implant can support body loads and avoid toxicological effects due to the release of metal ions into the body. Methods Standardized procedures according to ASTM F-1264 and ISO-10993-5 were used, respecting detailed methodological controls to ensure accuracy and reproducibility of the results, this testing methodology is carried out in accordance with the monographs of the Pharmacopoeia for the approval of medical devices and obtaining a health registration. An intramedullary implant (IIM) manufactured in magnesium (Mg) WE43 can support loads of the body in the initial period of bone consolidation without compromising the integrity of the fractured area. A system with these characteristics would improve morbidity and health costs by avoiding secondary surgical interventions. Results As a property, the fatigue resistance of Mg in aggressive environments such as the body environment undergoes progressive degradation, however, the autoclave sterilization method drastically affects fatigue resistance, as demonstrated in tests carried out under in vitro conditions. Coupled with this phenomenon, the relatively poor biocompatibility of Mg WE43 alloys has limited applications where they can be used due to low acceptance rates from agencies such as the FDA. However, Mg alloy with elements such as yttrium and rare earth elements (REEs) have been shown to delay biodegradation depending on the method of sterilization and the physiological solution used. With different sterilization techniques, it may be possible to keep toxicological effects to a minimum while still ensuring a balance between the integrity of fractured bone and implant degradation time. Therefore, the evaluation of fatigue resistance of WE43 specimens sterilized and tested in immersion conditions (enriched Hank’s solution) and according to ASTM F-1264, along with the morphological, crystallinity, and biocompatibility characterization of the WE43 alloy allows for a comprehensive evaluation of the mechanical and biological properties of WE43. Conclusions These results will support decision-making to generate a change in the current perspective of biomaterials utilized in medical devices (MDs), to be considered by manufacturers and health regulatory agencies. An implant manufactured in WE43 alloy can be used as an intramedullary implant, considering keeping elements such as yttrium-REEs below as specified in its designation and with the help of a coating that allows increasing the life of the implant in vivo

Association of immune responses of Zebu and Holstein-Friesian cattle and resistance to mycobacteria in a BCG challenge model

Mycobacterium bovis is the main cause of bovine tuberculosis (BTB) in cattle and can also infect humans. Zebu cattle are considered more resistant to some infectious diseases compared with Holstein‐Friesian (HF) cattle, including BTB. However, epidemiological studies may not take into account usage differences of the two types of cattle. HF cattle may suffer greater metabolic stress due to their more or less exclusive dairy use, whereas Zebu cattle are mainly used for beef production. In experiments conducted so far, the number of animals has been too small to draw statistically robust conclusions on the resistance differences between these cattle breeds. Here, we used a BCG challenge model to compare the ability of naïve and vaccinated Zebu and HF cattle to control/kill mycobacteria. Young cattle of both breeds with similar ages were housed in the same accommodation for the duration of the experiment. After correcting for multiple comparisons, we found no difference between naïve HF and Zebu (ρ = 0.862) cattle. However, there was a trend for vaccinated HF cattle to have lower cfu numbers than non‐vaccinated HF cattle (ρ = 0.057); no such trend was observed between vaccinated and non‐vaccinated Zebu cattle (ρ = 0.560). Evaluation of antigen‐specific IFNγ secretion by PBMC indicated that Zebu and HF cattle differed in their response to mycobacteria. Thus, whilst there may be difference in immune responses, our data indicate that with the number of animals included in the study and under the conditions used in this work, we were unable to measure any differences between Zebu and HF cattle in the overall control of mycobacteria. Whilst determination of different susceptibilities between Zebu and HF cattle using the BCG challenge model will require larger numbers of animals than the number of animals used in this experiment, these data should inform future experiments

Nitric Oxide Not Apoptosis Mediates Differential Killing of Mycobacterium bovis in Bovine Macrophages

To identify the resistance phenotype against Mycobacterium bovis in cattle, we used a bactericidal assay that has been considered a marker of this trait. Three of 24 cows (12.5%) were phenotyped as resistant and 21 as susceptible. Resistance of bovine macrophages (MΦ) to BCG challenge was evaluated for its association with SLC11A1 GT microsatellite polymorphisms within 3′UTR region. Twenty-three cows (95.8%) had a GT(13) genotype, reported as resistant, consequently the SLC11A1polymorphism was not in agreement with our bactericidal assay results. MΦ of cows with resistant or susceptible phenotype were challenged in vitro with virulent M. bovis field strain or BCG, and nitric oxide production, bacterial killing and apoptosis induction were measured in resting and LPS-primed states. M. bovis field strain induced more apoptosis than BCG, although the difference was not significant. Resistant MΦ controlled better the replication of M. bovis (P<0.01), produced more nitric oxide (P<0.05) and were slightly more prone to undergo apoptosis than susceptible cells. LPS pretreatment of MΦ enhanced all the functional parameters analyzed. Inhibition of nitric oxide production with n (G)-monomethyl-L-arginine monoacetate enhanced replication of M. bovis but did not modify apoptosis rates in both resistant and susceptible MΦ. We conclude that nitric oxide production not apoptosis is a major determinant of macrophage resistance to M. bovis infection in cattle and that the influence of SLC11A1 gene 3′UTR polymorphism is not associated with this event

Ciencia Odontológica 2.0

Libro que muestra avances de la Investigación Odontológica en MéxicoEs para los integrantes de la Red de Investigación en Estomatología (RIE) una enorme alegría presentar el segundo de una serie de 6 libros sobre casos clínicos, revisiones de la literatura e investigaciones. La RIE está integrada por cuerpos académicos de la UAEH, UAEM, UAC y UdeG

Mis casos clínicos de especialidades odontológicas

Libro que muestra la atención de casos clínicos particulares referente a las diferentes especialidades odontológicasLibro que muestra la atención de casos clínicos particulares referente a las diferentes especialidades odontológicasUniversidad Autónoma de Campeche Universidad Autónoma del Estado de Hidalgo Universidad Autónoma del Estado de Méxic

Genetically Related Mycobacterium bovis Strains Displayed Differential Intracellular Growth in Bovine Macrophages

Molecular typing of bacterial isolates provides a powerful approach for distinguishing Mycobacterium bovis (M. bovis) genotypes. It is known that M. bovis strain virulence plays a role in prevalence and spread of the disease, suggesting that strain virulence and prevailing genotypes are associated. However, it is not well understood whether strain virulence correlates with particular genotypes. In this study, we assessed the in vitro intracellular growth of 18 M. bovis isolates in bovine macrophages as an indicator of bacterial virulence and sought a relationship with the genotype identified by spoligotyping. We found 14 different spoligotypes&mdash;11 were already known and three spoligotypes had never been reported before. We identified 2 clusters that were phylogenetically related, containing 10 and 6 strains, respectively, and 2 orphan strains. Intracellular growth and phagocytic rates of 18 M. bovis strains were heterogeneous. Our results suggest that M. bovis intracellular growth and phagocytosis are independent of the bacterial lineage identified by spoligotyping

Screening of Gastrointestinal Lipase Inhibitors Produced by Microorganisms Isolated from Soil and Lake Sediments

International audienceGastrointestinal lipase inhibitors are molecules of pharmaceutical interest due to theiruse as anti-obesity drugs. In this study, forty strains isolated from soil and sedimentswere identified with the ability to produce inhibition of gastrointestinal lipase activity.The biomass extract of these strains showed at least 50% inhibition in the hydrolysis oftributyrin by recombinant Human Pancreatic Lipase (rHPL) or Rabbit Gastric Lipase(RGL) by in vitro assays. Based on gene sequencing, the isolates were identifiedmainly as Streptomycetes. Moreover, none of the identified strains have been reportedto be lipase inhibitor producers, so they can be viewed as potential sources forobtaining new drugs. IC50 values of the three best inhibitor extracts showed thatAC104-10 was the most promising strain for production of gastrointestinal lipaseinhibitors. AC104-10 shows 99% homology (16S rRNA gene fragment) toStreptomyces cinereoruber strain NBRC 12756. An inhibitory study over trypsin activityrevealed that AC104-10 extract, as well as THL, had no significant effect on the activityof this protease, showing its specificity for lipases. In addition, analyzes by MALDI-TOFMass Spectrometry of the enzyme-inhibitor complex revealed that there is a covalentinteraction of the AC104-10 inhibitor with the catalytic serine of the pancreatic lipase,and that the molecular weight of the inhibitor is approximately 686.19 Da

Apoptosis induction in <i>Mycobacterium bovis</i>-infected bovine macrophages.

<p>Uninfected macrophages (A), macrophages treated with camptothecin (10 µg/mL for 48 h) (C) and macrophages infected with <i>Mycobacterium bovis</i> field strain 9926 (B, D and E), were washed at 4 h and cultured again for 24 h. Then cells were processed by TUNEL in presence (E) or absence (D) of TdT enzyme. Chromatin condensation was present in no-infected (arrows) and infected cells (arrowheads). TUNEL-positive cells show a green-yellow mark in panel E (BrdUTP-FITC). Magnification for A to C is 63X and for D and E is 40X with a scale bar of 50 µm each.</p