The race for the optimal antimicrobial surface: perspectives and challenges related to plasma electrolytic oxidation coating for titanium-based implants.

Plasma electrolytic oxidation (PEO) is a low-cost, structurally reliable, and environmentally friendly surface modification method for orthopedic and dental implants. This technique is successful for the formation of porous, corrosion-resistant, and bioactive coatings, besides introducing antimicrobial compounds easily. Given the increase in implant-related infections, antimicrobial PEO-treated surfaces have been widely proposed to surmount this public health concern. This review comprehensively discusses antimicrobial implant surfaces currently produced by PEO in terms of their in vitro and in vivo microbiological and biological properties. We present a critical [part I] and evidence-based [part II] review about the plethora of antimicrobial PEO-treated surfaces. The mechanism of microbial accumulation on implanted devices and the principles of PEO technology to ensure antimicrobial functionalization by one- or multi-step processes are outlined. Our systematic literature search showed that particular focus has been placed on the metallic and semi-metallic elements incorporated into PEO surfaces to facilitate antimicrobial properties, which are often dose-dependent, without leading to cytotoxicity in vitro. Meanwhile, there are concerns over the biocompatibility of PEO and its long-term antimicrobial effects in animal models. We clearly highlight the importance of using clinically relevant infection models and in vivo long-term assessments to guarantee the rational design of antimicrobial PEO-treated surfaces to identify the 'finish line' in the race for antimicrobial implant surfaces.

A Dual Ligand Sol⁻Gel Organic-Silica Hybrid Monolithic Capillary for In-Tube SPME-MS/MS to Determine Amino Acids in Plasma Samples.

This work describes the direct coupling of the in-tube solid-phase microextraction (in-tube SPME) technique to a tandem mass spectrometry system (MS/MS) to determine amino acids (AA) and neurotransmitters (NT) (alanine, serine, isoleucine, leucine, aspartic acid, glutamic acid, lysine, methionine, tyrosine, and tryptophan) in plasma samples from schizophrenic patients. An innovative organic-silica hybrid monolithic capillary with bifunctional groups (amino and cyano) was developed and evaluated as an extraction device for in-tube SPME. The morphological and structural aspects of the monolithic phase were evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen sorption experiments, X-ray diffraction (XRD) analyses, and adsorption experiments. In-tube SPME-MS/MS conditions were established to remove matrix, enrich analytes (monolithic capillary) and improve the sensitivity of the MS/MS system. The proposed method was linear from 45 to 360 ng mL-1 for alanine, from 15 to 300 ng mL-1 for leucine and isoleucine, from 12 to 102 ng mL-1 for methionine, from 10 to 102 ng mL-1 for tyrosine, from 9 to 96 ng mL-1 for tryptophan, from 12 to 210 ng mL-1 for serine, from 12 to 90 ng mL-1 for glutamic acid, from 12 to 102 ng mL-1 for lysine, and from 6 to 36 ng mL-1 for aspartic acid. The precision of intra-assays and inter-assays presented CV values ranged from 1.6% to 14.0%. The accuracy of intra-assays and inter-assays presented RSE values from -11.0% to 13.8%, with the exception of the lower limit of quantification (LLOQ) values. The in-tube SPME-MS/MS method was successfully applied to determine the target AA and NT in plasma samples from schizophrenic patients.

Butyl Methacrylate-Co-Ethylene Glycol Dimethacrylate Monolith for Online in-Tube SPME-UHPLC-MS/MS to Determine Chlopromazine, Clozapine, Quetiapine, Olanzapine, and Their Metabolites in Plasma Samples.

This manuscript describes a sensitive, selective, and online in-tube solid-phase microextraction coupled with an ultrahigh performance liquid chromatography-tandem mass spectrometry (in-tube SPME-UHPLC-MS/MS) method to determine chlopromazine, clozapine, quetiapine, olanzapine, and their metabolites in plasma samples from schizophrenic patients. Organic poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith was synthesized on the internal surface of a fused silica capillary (covalent bonds) for in-tube SPME. Analyte extraction and analysis was conducted by connecting the monolithic capillary to an UHPLC-MS/MS system. The monolith was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The developed method presented adequate linearity for all the target antipsychotics: R² was higher than 0.9975, lack-of-fit ranged from 0.115 to 0.955, precision had variation coefficients lower than 14.2%, and accuracy had relative standard error values ranging from -13.5% to 14.6%, with the exception of the lower limit of quantification (LLOQ). The LLOQ values in plasma samples were 10 ng mL-1 for all analytes. The developed method was successfully applied to determine antipsychotics and their metabolites in plasma samples from schizophrenic patients.

Clinical Response to Donepezil in Mild and Moderate Dementia: Relationship to Drug Plasma Concentration and CYP2D6 and APOE Genetic Polymorphisms.

The clinical response to donepezil in patients with mild and moderate dementia was investigated in relation to the drug plasma concentration and APOE and CYP2D6 polymorphisms. In a prospective naturalistic observational study, 42 patients with Alzheimer's disease (AD) and AD with cerebrovascular disease who took donepezil (10 mg) for 12 months were evaluated. Their DNA was genotyped, and the donepezil plasma concentrations were measured after 3, 6, and 12 months. Good responders scored ≥-1 on the Mini-Mental State Examination at 12 months in comparison to the baseline score. The study results indicated the good response pattern was influenced by the concentration of donepezil, but not by APOE and CYP2D6 polymorphisms.

Predictive factors of clinical response to cholinesterase inhibitors in mild and moderate Alzheimer's disease and mixed dementia: a one-year naturalistic study.

BACKGROUND: Naturalistic studies evaluate individuals in their usual way of living, presenting more "real-life" data regarding patients and their diseases. OBJECTIVE: To investigate demographic, clinical, and genetic factors that could be predictive of good response to cholinesterase inhibitors (ChEI) treatment in Alzheimer's disease (AD) and AD + cerebrovascular disease (CVD). PATIENTS AND METHODS: A total of 129 patients were diagnosed with AD or AD + CVD and with mild-to-moderate dementia. After a 12-month treatment, 97 patients completed the study. They were evaluated at baseline and after three, six, and 12 months of ChEI (donepezil or rivastigmine or galantamine) use. APOE genotype and CYP2D6 polymorphisms were determined for all of the participants. In each visit, we used cognitive, functional, mood, and behavior scales. We classified patients according to their scores in the Mini-Mental State Examination (MMSE). Good responders were defined as those scoring ≥2 in the MMSE at 12 months. RESULTS: The rate of good clinical response was 27.8%. In a longitudinal analysis, the patients with mild AD and also good responders at three months were considered to be good responders at 12 months. There was no correlation between ChEI dose, APOE and CYP2D6 polymorphisms, and the pattern of clinical response. CONCLUSION: A higher rate of good response was observed in this study compared to that in previous investigations. The pharmacogenetic aspects do not seem to have an influence in the response.

Stem cell factor improves lung recovery in rats following neonatal hyperoxia-induced lung injury.

BACKGROUND: Stem cell factor (SCF) and its receptor, c-kit, are modulators of angiogenesis. Neonatal hyperoxia-induced lung injury (HILI) is characterized by disordered angiogenesis. The objective of this study was to determine whether exogenous SCF improves recovery from neonatal HILI by improving angiogenesis. METHODS: Newborn rats assigned to normoxia (RA: 20.9% O2) or hyperoxia (90% O2) from postnatal day (P) 2 to 15, received daily injections of SCF 100 µg/kg or placebo (PL) from P15 to P21. Lung morphometry was performed at P28. Capillary tube formation in SCF-treated hyperoxia-exposed pulmonary microvascular endothelial cells (HPMECs) was determined by Matrigel assay. RESULTS: As compared with RA, hyperoxic-PL pups had decrease in alveolarization and in lung vascular density, and this was associated with increased right ventricular systolic pressure (RVSP), right ventricular hypertrophy, and vascular remodeling. In contrast, SCF-treated hyperoxic pups had increased angiogenesis, improved alveolarization, and attenuation of pulmonary hypertension as evidenced by decreased RVSP, right ventricular hypertrophy, and vascular remodeling. Moreover, in an in vitro model, SCF increased capillary tube formation in hyperoxia-exposed HPMECs. CONCLUSION: Exogenous SCF restores alveolar and vascular structure in neonatal rats with HILI by promoting neoangiogenesis. These findings suggest a new strategy to treat lung diseases characterized by dysangiogenesis.

Mitochondria and hypoxia-induced gene expression mediated by hypoxia-inducible factors.

The influence of mitochondrial activity on gene expression programs, particularly those involved in neuroprotection and repair, is likely to play an important role in the pathophysiology of neurodegenerative diseases. One such gene expression program is activated by the cellular pathway that senses a decrease in optimal oxygen levels and leads to activation of a family of transcriptional activators called hypoxia-inducible factors (HIFs). HIFs are members of the bHLH-PAS family of transcription factors and are heterodimers composed of HIF-alpha and HIF-beta (also known as aryl hydrocarbon receptor nuclear translocator) subunits that bind to canonical DNA sequences (hypoxia-regulated elements) in the promoters or enhancers of target genes. HIFs activate the expression of more than a hundred genes encoding proteins that regulate cell metabolism, survival, angiogenesis, vascular tone, hematopoiesis, and other functions. There is considerable evidence showing a bidirectional crosstalk between mitochondrial signals and HIF activity. For instance, mitochondrial reactive oxygen species and metabolic substrates from the tricarboxylic acid cycle are implicated in the regulation of the HIF pathway. Conversely, HIF activity leads to the expression of target genes that influence mitochondrial function. In this chapter we will review the complex interactions between mitochondria and the HIF pathway and we will discuss the relevance of this interaction for metabolic adaptation to hypoxia.

Neuron-specific inactivation of the hypoxia inducible factor 1 alpha increases brain injury in a mouse model of transient focal cerebral ischemia.

In the present study, we show a biphasic activation of hypoxia inducible factor 1alpha (HIF-1) after stroke that lasts for up to 10 d, suggesting the involvement of the HIF pathway in several aspects of the pathophysiology of cerebral ischemia. We provide evidence that HIF-1-mediated responses have an overall beneficial role in the ischemic brain as indicated by increased tissue damage and reduced survival rate of mice with neuron-specific knockdown of HIF-1alpha that were subjected to transient focal cerebral ischemia. In addition, we demonstrated that drugs known to activate HIF-1 in cultured cells as well as in vivo had neuroprotective properties in this model of cerebral ischemia. This protective effect was significantly attenuated but not completely abolished in neuron-specific HIF-1alpha-deficient mice, suggesting that alternative mechanisms of neuroprotection are also implicated. Last, our study showed that hypoxia-induced tolerance to ischemia was preserved in neuron-specific HIF-1alpha-deficient mice, indicating that the neuroprotective effects of hypoxic preconditioning do not depend on neuronal HIF-1 activation.