Strontium-Substituted α-TCP: Structure, Stability, and Reactivity in Solution

& alpha;-Tricalcium phosphate (& alpha;-TCP) is widelyused as acomponent of bone cements, and many efforts have been made to dopeit with strontium ion (Sr), which is known for its beneficial rolein bone tissue. However, the range of possible substitution of strontiumfor calcium (Ca) into & alpha;-TCP, as well as its effect on the & alpha;-TCPstructure, has not been clarified yet. Herein, we investigate thissubstitution through the examination of & alpha;-TCP synthesized athigh temperatures in the presence of increasing amounts of strontiumaccording to two different routes: 1-step and 2-steps. The results show that Sr can enter into an & alpha;-TCPstructure up to about 10 atom % and substitutes for calcium mostlyat specific cation sites, namely, M(5), M(11), and M(17), characterizedby relatively low bond valence sums and long mean Ca-O distance.Strontium presence stabilizes & alpha;-TCP delaying its transformationinto octacalcium phosphate and hydroxyapatite in H3PO4, as well as in physiological solution. Although the two methodsof synthesis provide similar structural results, the products of 1-step synthesis display a slightly smaller crystallitesize and greater solubility and, as a consequence, a faster hydrolysisreaction.& alpha;-Tricalcium phosphatepreparation through the solid-statereaction is described following two different procedures. The investigationof the range of possible substitution of strontium for calcium into & alpha;-TCP as well as its effect on the & alpha;-TCP structure ispresented. Furthermore, it is shown that strontium presence stabilizes & alpha;-TCP and delays its hydrolysis reaction into octacalcium phosphateand hydroxyapatite

Synthesis and Hydrolysis of Brushite (DCPD): The Role of Ionic Substitution

Brushite (dicalcium phosphate dihydrate, DCPD) is considered one of the possible precursors of the apatitic phase that constitutes the mineral component of bones, and it is often utilized in the preparation of biomaterials for hard tissue repair. In this work, we investigated the influence of ionic substitution on the synthesis, structure, and morphology of this calcium phosphate, as well as on its hydrolysis process. The results of structural refinements indicate that the range of possible substitution can reach values up to about 38 atom % for the big Sr ion, whereas it is quite limited for Zn, Co, and Mn. In particular, DCPD cannot be obtained as a single phase in the presence of zinc ions in solution. The kind and amount of substituent ions significantly influence the morphology of DCPD, promoting aggregation and crystal shape modifications, as well as its hydrolysis in solution. The results provide useful information for the understanding of the mineralization processes and for the design of new biomaterials

The assessment of dog welfare in the waiting room of a veterinary clinic

Veterinary visits are known to be stressful for many dogs. The aim of this study was to assess dog welfare in the waiting room of the veterinary clinic through a multi-modal, non-invasive approach. Forty-five dogs were each videoed for 3 min in the waiting room of a veterinary clinic where they went for a scheduled visit. The welfare of each dog was assessed using a thorough video analysis and two overall evaluations (low, medium and high stress); one performed by a veterinary behaviourist and one by the dog's owner. Two-thirds of dogs spent more than 20% of the time displaying at least one indicator of stress, and 53.3% showed four or more behavioural signs of stress. Assessments of stress by the behaviourist indicated that level of stress in the waiting room was high in 28.9% of cases. The agreement between owners' and behaviourist's overall evaluations was quite low. The behaviourist's evaluations were strongly correlated with the time spent by dogs showing signs of stress and moderately correlated with the number of displayed signs, whilst owners' evaluations were not closely correlated to those factors. Dogs rated as highly stressed by the behaviourist were more prone to display resistance (halting, refusing to budge) when moving from the waiting room to the consultation room. The results of this pilot study support the idea that the welfare of dogs in the veterinary waiting room is often impaired, and that owners are unable to accurately assess stress in their dogs in such situations

The impact of chronic inflammatory enteropathy on dogs’ quality of life and dog-owner relationship

This research was aimed at evaluating the impact of canine chronic enteropathies on dogs’ quality of life (QoL), their behavior, and owner–dog relationship. Forty-four dogs suffering from primary chronic enteropathies were assessed on the first visit with a veterinary gastroenterologist and on the first follow-up visit using a 1–10 visual scale to evaluate five features of QoL, the Canine Chronic Enteropathy Clinical Activity Index, the Lexington Attachment to Pet Scale, and the Canine Behavioral Assessment and Research Questionnaire. They were compared to a control group of 49 healthy dogs and to a group of 50 dogs suffering from cancer. QoL and severity of enteropathy were negatively associated; enteropathic dogs on the first visit had a lower QoL than healthy dogs for all features and a lower general QoL than cancer patients; enteropathic dogs on the follow-up visit improved significantly for general QoL, health QoL, and interaction QoL. Higher levels of attachment between the owner and the dog were obtained for dogs affected by chronic enteropathies. Finally, dogs showed higher scores for separation-related behaviors and contact/attention behaviors on the first visit than on the subsequent follow-up. As in human medicine, chronic enteropathies have a strong negative impact on dogs

Identification of redox-sensitive transcription factors as markers of malignant pleural mesothelioma.

Although asbestos has been banned in most countries around the world, malignant pleural mesothelioma (MPM) is a current problem. MPM is an aggressive tumor with a poor prognosis, so it is crucial to identify new markers in the preventive field. Asbestos exposure induces oxidative stress and its carcinogenesis has been linked to a strong oxidative damage, event counteracted by antioxidant systems at the pulmonary level. The present study has been focused on some redox-sensitive transcription factors that regulate cellular antioxidant defense and are overexpressed in many tumors, such as Nrf2 (Nuclear factor erythroid 2-related factor 2), Ref-1 (Redox effector factor 1), and FOXM1 (Forkhead box protein M1). The research was performed in human mesothelial and MPM cells. Our results have clearly demonstrated an overexpression of Nrf2, Ref-1, and FOXM1 in mesothelioma towards mesothelium, and a consequent activation of downstream genes controlled by these factors, which in turn regulates antioxidant defense. This event is mediated by oxidative free radicals produced when mesothelial cells are exposed to asbestos fibers. We observed an increased expression of Nrf2, Ref-1, and FOXM1 towards untreated cells, confirming asbestos as the mediator of oxidative stress evoked at the mesothelium level. These factors can therefore be considered predictive biomarkers of MPM and potential pharmacological targets in the treatment of this aggressive cancer

“Three-bullets” loaded mesoporous silica nanoparticles for combined photo/chemotherapy

This contribution reports the design, preparation, photophysical and photochemical characterization, as well as a preliminary biological evaluation of mesoporous silica nanoparticles (MSNs) covalently integrating a nitric oxide (NO) photodonor (NOPD) and a singlet oxygen (1O2) photosensitizer (PS) and encapsulating the anticancer doxorubicin (DOX) in a noncovalent fashion. These MSNs bind the NOPD mainly in their inner part and the PS in their outer part in order to judiciously exploit the different diffusion radius of the cytotoxic NO and 1O2. Furthermore this silica nanoconstruct has been devised in such a way to permit the selective excitation of the NOPD and the PS with light sources of different energy in the visible window. We demonstrate that the individual photochemical performances of the photoactive components of the MSNs are not mutually affected, and remain unaltered even in the presence of DOX. As a result, the complete nanoconstruct is able to deliver NO and 1O2 under blue and green light, respectively, and to release DOX under physiological conditions. Preliminary biological results performed using A375 cancer cells show a good tolerability of the functionalized MSNs in the dark and a potentiated activity of DOX upon irradiation, due to the effect of the NO photoreleased