Mechanism of plasma electrolytic oxidation in Mg3ZnCa implants: a study of double-layer formation and properties through nanoindentation.

Plasma electrolytic oxidation (PEO), applied to light metals such as titanium, aluminum, and magnesium, creates a two-layer coating and has become increasingly important in metal coatings. However, due to the high voltage and temperature of the process, no online instrument could monitor the underlying mechanism. This paper presents a new image proving that the surface of PEO-coated Mg3ZnCa boiled during the process and argues that three hypotheses are involved in the PEO mechanism based on boiling caused by tolerating high voltage during the PEO process, which could explain the current‒voltage diagram of the process. Finally, nanoindentation was used to measure the elastic module and hardness of the PEO layers. The nanoindentation test results revealed the similarity of the elastic module of the outer porous layer and the primary alloy, with values of 40.25 GPa and 41.47 GPa, respectively, confirming that the outer porous layer corresponds to the cold plasma-gas phase formed during the PEO process.

Safety and efficacy of low-dose PI3K inhibitor taselisib in adult patients with CLOVES and Klippel-Trenaunay syndrome (KTS): the TOTEM trial, a phase 1/2 multicenter, open-label, single-arm study.

PURPOSE: PIK3CA pathogenic variants in the PIK3CA-related overgrowth spectrum (PROS) activate phosphoinositide 3-kinase signaling, providing a rationale for targeted therapy, but no drug has proven efficacy and safety in this population. Our aim was to establish the six-month tolerability and efficacy of low-dose taselisib, a selective class I PI3K inhibitor, in PROS patients. METHODS: Patients over 16 years with PROS and PIK3CA pathogenic variants were included in a phase IB/IIA multicenter, open-label single-arm trial (six patients at 1 mg/day of taselisib, then 24 at 2 mg/day). The primary outcome was the occurrence of dose limiting toxicity (DLT). Efficacy outcomes were the relative changes after treatment of (1) tissue volume at affected and unaffected sites, both clinically and on imaging; (2) cutaneous vascular outcomes when relevant; (3) biologic parameters; (4) quality of life; and (5) patient-reported outcomes. RESULTS: Among 19 enrolled patients, 2 experienced a DLT (enteritis and pachymeningitis) leading to early trial termination (17 treated, 10 completed the study). No serious adverse reaction occurred in the 1 mg cohort (n = 6). No significant reduction in affected tissue volume was observed (mean -4.2%; p = 0.81; SD 14.01). Thirteen (76.4%) participants reported clinical improvement (pain reduction, chronic bleeding resolution, functional improvement). CONCLUSION: Despite functional improvement, the safety profile of low-dose taselisib precludes its long-term use.

Model reduction of genome-scale metabolic models as a basis for targeted kinetic models.

Constraint-based, genome-scale metabolic models are an essential tool to guide metabolic engineering. However, they lack the detail and time dimension that kinetic models with enzyme dynamics offer. Model reduction can be used to bridge the gap between the two methods and allow for the integration of kinetic models into the Design-Built-Test-Learn cycle. Here we show that these reduced size models can be representative of the dynamics of the original model and demonstrate the automated generation and parameterisation of such models. Using these minimal models of metabolism could allow for further exploration of dynamic responses in metabolic networks.

Mesocarp of Brazil nut (Bertholletia excelsa) as inspiration for new impact resistant materials.

Aiming to produce bioinspired impact and puncture resistant materials, the mesocarp of the Brazil nut (Bertholletia excelsa) was characterized. The mesocarp composition was investigated by chemical extraction and its microstructure was analyzed by optical microscopy and microtomography (microCT). A compression test evaluated the force needed to open the mesocarp shell. Shore D hardness testing and nanoindentation measured the local mechanical properties at different length scales. Brazil nut mesocarp has a higher content of lignin (56%) than other nutshells and is mainly composed of sclereids and fibers cells arranged together and not in separated layers as usually found in nature. The mesocarp has an internal and external layer with fibers oriented from peduncle to opercular opening and a middle layer where entangled fibers are latitudinally oriented. To open a Brazil nut mesocarp, compression forces of 10 079 ± 1460 N (parallel to latitudinal section) and 14 785 ± 4050 N (perpendicular to latitudinal section) are needed. Such forces are higher than the forces needed to open most nutshells, if fracture force is normalized by shell thickness. The Shore D hardness test showed that hardness is uniform in the mesocarp, although it is higher in the center of the thickness than close to the inner or outer surface. The cell wall of fibers has a higher reduced modulus than the cell wall of sclereids although they have a similar hardness. These microstructural and mechanical results indicate that Brazil nutshell has great potential as a source for bioinspiration and motivates further studies.

Biomimetic cellular metals-using hierarchical structuring for energy absorption.

Fruit walls as well as nut and seed shells typically perform a multitude of functions. One of the biologically most important functions consists in the direct or indirect protection of the seeds from mechanical damage or other negative environmental influences. This qualifies such biological structures as role models for the development of new materials and components that protect commodities and/or persons from damage caused for example by impacts due to rough handling or crashes. We were able to show how the mechanical properties of metal foam based components can be improved by altering their structure on various hierarchical levels inspired by features and principles important for the impact and/or puncture resistance of the biological role models, rather than by tuning the properties of the bulk material. For this various investigation methods have been established which combine mechanical testing with different imaging methods, as well as with in situ and ex situ mechanical testing methods. Different structural hierarchies especially important for the mechanical deformation and failure behaviour of the biological role models, pomelo fruit (Citrus maxima) and Macadamia integrifolia, were identified. They were abstracted and transferred into corresponding structural principles and thus hierarchically structured bio-inspired metal foams have been designed. A production route for metal based bio-inspired structures by investment casting was successfully established. This allows the production of complex and reliable structures, by implementing and combining different hierarchical structural elements found in the biological concept generators, such as strut design and integration of fibres, as well as by minimising casting defects. To evaluate the structural effects, similar investigation methods and mechanical tests were applied to both the biological role models and the metallic foams. As a result an even deeper quantitative understanding of the form-structure-function relationship of the biological concept generators as well as the bio-inspired metal foams was achieved, on deeper hierarchical levels and overarching different levels.

Characterizing the transformation near indents and cracks in clinically used dental yttria-stabilized zirconium oxide constructs.

OBJECTIVES: Tetragonal zirconia polycrystal (TZP) materials are widely used for full ceramic partial dentures, even though their mechanical properties might change during service. A key property for the durability of the constructs is thought to be an inhibition of crack propagation by phase transformation toughening. Because dental prosthesis are ground and polished for adjustment purposes, it is important to understand the effects of mechanical surface treatments, on localized transformation and around the propagating cracks. METHODS: Sintered samples of commercially available 3 mol-% Yittria-doped TZP were ground and polished and the surface structure and phase composition were compared with those of re-transformed annealed samples. Microindentation was used to induce cracks and nanoindentation was performed to determine the local variety of hardness and indentation modulus, coupled with XRD and SEM investigations. RESULTS: Y-TZP polished surfaces exhibited 9% monoclinic phase content and have reduced hardness and indentation modulus amounting 16.3 GPa and 210.6 GPa, respectively. Y-TZP re-transformed annealed sample revealed 19.4 GPa and 242.3 GPa, respectively. A localized reduction of the stiffness around the crack tips on the annealed surface reveals an irregular arrangement of t-m-transformed grains. Electron micrographs show more damage on the transformed surface following microindentation than on indented annealed surfaces. SIGNIFICANCE: Y-TZP prostheses are adapted and roughened by clinicians prior to bonding to teeth. Annealing recovers properties and microstructure that is changed by the adaptation of the outer layer. This might be important to ensure long-term toughening functionality of the dentures and optimal comfort for the patients.

Influence of cell-to-cell variability on spatial pattern formation.

Many spatial patterns in biology arise through differentiation of selected cells within a tissue, which is regulated by a genetic network. This is specified by its structure, parameterisation and the noise on its components and reactions. The latter, in particular, is not well examined because it is rather difficult to trace. The authors use suitable local mathematical measures based on the Voronoi diagram of experimentally determined positions of epidermal plant hairs (trichomes) to examine the variability or noise in pattern formation. Although trichome initiation is a highly regulated process, the authors show that the experimentally observed trichome pattern is substantially disturbed by cell-to-cell variations. Using computer simulations, they find that the rates concerning the availability of the protein complex that triggers trichome formation plays a significant role in noise-induced variations of the pattern. The focus on the effects of cell noise yields further insights into pattern formation of trichomes. The authors expect that similar strategies can contribute to the understanding of other differentiation processes by elucidating the role of naturally occurring fluctuations in the concentration of cellular components or their properties.

Molecular combination of the dopamine and serotonin scaffolds yield in novel antipsychotic drug candidates - characterization by in vivo experiments.

Serotonin and dopamine play an important role in the aetiology of schizophrenia. Combination of the structural scaffolds of both neurotransmitters in a single molecule lead to aromatic [d,g]-bisannelated azecine derivatives, which have been shown to be nanomolar to subnanomolar dopamine D1-D5 receptor antagonists with a preference for the D1 family. In this work the potential antipsychotic activity of some azecine derivatives was predicted by their dopamine receptor affinities obtained in vitro from radioligand binding experiments and conclusively confirmed in vivo (rats) by applying a conditioned avoidance model. Furthermore, the compounds were tested in vivo for the development of catalepsy, which is a predictive parameter for extra-pyramidal side-effects caused by many antipsychotics. The investigated azecines displayed low cytotoxicity, and the affinities for human dopamine D1-D5 and serotonin 5-HT2 A receptors were in a nanomolar range. In vivo, their antipsychotic activities in the rat model were comparable with those of haloperidol and risperidone, but revealed a 2-5 times better therapeutic range with regard to catalepsy. Preliminary tests for oral bioavailability also revealed promising results for this new class of potential antipsychotic compounds. In conclusion, our in vivo experiments show that aromatic [d,g]-annelated azecines represent a novel and advantageous class of potential atypical neuroleptics.

Slow magnetic order-order transition in the spin chain antiferromagnet Ca3Co2O6.

Using powder neutron diffraction, we have discovered an unusual magnetic order-order transition in the Ising spin chain compound Ca3Co2O6. On lowering the temperature, an antiferromagnetic phase with a propagation vector k=(0.5,-0.5,1) emerges from a higher temperature spin density wave structure with k=(0,0,1.01). This transition occurs over an unprecedented time scale of several hours and is never complete.

Monoclinic phase transformations of zirconia-based dental prostheses, induced by clinically practised surface manipulations.

Full-ceramic zirconia crowns and bridges have become very popular with dentists and patients because of their excellent esthetics and mechanical properties. We studied phase transformations within the outermost surface layer of 3 mol.% yttria-stabilized zirconia (Y-TZP) samples of small, clinically relevant thicknesses, manipulated by polishing, grinding and fracture as might be encountered in everyday clinical practice. Stress-induced transformations of the tetragonal phase were studied in three dimensions in order to better understand the organization and extent of the monoclinically transformed phase. By means of laboratory- and synchrotron-based X-ray diffraction measurements, coupled with electron microscopy and multimodal tomography, it was possible for the first time to visualize and quantify the phase distributions non-destructively and in three dimensions. Highly variable degrees of local transformation result in ragged transformed zones of very inhomogeneous thickness. The overall thickness of the transformation layers strongly depends on the severity and rate of loading. Gentle diamond cutting resulted in surprisingly low transformation ratios of less than 0.1%. When Y-TZP constructions are manipulated before bonding, toughness of the outer layers is reduced and they may become brittle with important implications for the stability of the bond: dental practitioners thus need to be cautious when altering the surfaces of these materials after sintering.

Modelling polar auxin transport in developmental patterning.

Auxin interacts with its own polar transport to influence cell polarity and tissue patterning. Research over the past decade has started to deliver new insights into the molecular mechanisms that drive and regulate polar auxin transport. The most prominent auxin efflux protein, PIN1, has subsequently become a crucial component of auxin transport models because it is now known to direct auxin flow and maintain local auxin gradients. Recent molecular and genetic experiments have allowed the formulation of conceptual models that are able to interpret the role of (i) auxin, (ii) its transport, and (iii) the dynamics of PIN1 in generating temporal and spatial patterns. Here we review the current mathematical models of patterning in two specific developmental contexts: lateral shoot and vein formation, focusing on how these models can help to untangle the details of auxin transport-mediated patterning.

In vivo investigations on the cholinesterase-inhibiting effects of tricyclic quinazolinimines: scopolamine-induced cognitive impairments in rats are attenuated at low dosage and reinforced at higher dosage.

Tricyclic quinazolinimines as a novel class of potent inhibitors of cholinesterases in vitro are micro- and sub-micromolar inhibitors with activities at both acetyl- (AChE) and butyrylcholinesterase (BChE) or at BChE only. To further establish the antiamnesic properties of this class of compounds, an in vivo test system has been established. Cognitive impairment in rats was reversibly induced by scopolamine (0.05 mg/100 g body weight) and evaluated in an eight-arm radial maze. A representative quinazolinimine (MD212) showed attenuation of cognitive deficits at a low dosage (0.01 mg/100 g body weight), whereas at a high dosage (>0.1 mg/100 g body weight) the effect of scopolamine is markedly reinforced. As MD212 applied alone does not influence rat's cognition at all, the reinforcement of scopolamine effect has to be due to the amplification of scopolamine action possibly by (1) inhibition of scopolamine metabolism, (2) influence of scopolamine on MD212 metabolism or (3) allosteric modulation of mACh receptors. Receptor-binding studies proved hypothesis (3): MD212 stabilizes [3H]N-methylscopolamine binding to muscarinic receptors allosterically.

Surfaces with quenched and annealed disordered charge distributions.

We consider surfaces with disordered charge distribution. The disorder can be caused by mobile charges, as for example in mixed lipid bilayers, or by weakly charged surfaces where charge regulation takes place (e.g. carboxyl groups). Using Monte-Carlo simulation methods we find for quenched as well as annealed disordered charge distributions counterion densities close to the surface that are significantly larger than for ordered regularly spaced surface ions. Our field-theoretic results agree well with results obtained from Monte-Carlo simulations of the system. Furthermore, we obtain expressions for the effective interaction between charged colloids and charged rods close to a charged surface and discuss the effect of the surface-ion mobility and polarization charges on the interaction. In general, polarization effects as well as surface-ion mobility lead to a weakening of the effective interaction between charged objects.

Efforts to establish an animal model of Fanconi syndrome after ifosfamide administration to rats.

About 10% of children develop Fanconi syndrome (FS) a few months after ifosfamide (IFO) treatment. To establish an animal model, IFO was injected as 4 or 5 treatment courses (TCs, once daily for 3 consecutive days), to adult female rats (AF, 8 mg 100 g(-1) body wt, 4 TCs), to young female rats (YF, 8 mg 100 g(-1) body wt, 5 TCs) and to male rats (M, 6 mg 100 g(-1) body wt, 4 TCs). In the adult female rats, polyuria with electrolyte and albumin wasting occurred acutely, 2 days after the first treatment course. After the third treatment course, 30% of the rats died, but survivors showed a reduced excretion of electrolytes and glucose. The body weight increase was significantly diminished in adult female and male rats by about 25% or 70%, respectively. Up to 5 months after 5 TCs in young female rats, 15% of the animals died but the survivors did not show any sign of renal failure. In males, 28% of the rats died and in surviving animals the excretion of electrolytes, proteins and glucose as well as GFR were reduced 7 weeks after the last treatment course. There were no pathomorphological changes in kidney and liver. Determination of renal and hepatic cytochrome P450 activities indicated that results of adult female and male rats could be caused by starving, known as a common side effect of IFO, and not by its nephrotoxicity. Altogether, it was not possible to establish a model of a Fanconi syndrome persisting after cessation of IFO treatment in our rat strain, whereas acute, FS-like IFO effects on the kidney could be shown.

[In vitro investigations of phase I metabolism of the fomocaine derivative Oe 9000 with pig liver homogenates]. / In-vitro-Untersuchungen zum Phase-1-Metabolismus des Fomocain-Derivats Oe 9000 mit Schweineleberhomogenaten.

2,2'-[4-(4-Phenoxymethylphenyl)butylimino]diethanol (Oe 9000) is a new, highly potent local anaesthetic related to fomocaine. It displays a long duration of action, low toxicity and is superior to fomocaine with regard to aqueous solubility and efficacy. In view of the development of new application forms, e.g. for the treatment of postoperative pain, the elucidation of the biotransformation of the drug is required. Therefore, experiments with 10000 x g supernatants and microsomes from pig liver homogenates were conducted. Using specifically synthesized reference compounds six phase I metabolites could be identified by LC-MS. Apart from the predominating oxidative desamination of the compound, that led after redox reactions to the corresponding butyric acid and butanol derivatives, oxygenation of the exocycle, oxidative N-desalkylation, and N-oxidation were observed. Thus, with the exception of one compound only metabolites are generated, that are expected to have no local anaesthetic activity due to their reduced basicity.

Asymmetrical (ADMA) and symmetrical dimethylarginine (SDMA) as potential risk factors for cardiovascular and renal outcome in chronic kidney disease - possible candidates for paradoxical epidemiology?

BACKGROUND: Asymmetrical dimethylarginine (ADMA) is an inhibitor of nitric-oxide synthase. It has been linked to atherosclerotic risk in the general population as well as in end-stage renal disease patients (ESRD), whereas symmetrical dimethylarginine (SDMA) is thought to be biological inactive. Prospective data concerning the role of both dimethylarginines are rare in patients with chronic kidney disease. METHODS: 200 Patients with chronic kidney disease (mean age 57.6 +/- 13.0 years, 69 female, 131 male); 82 with chronic renal failure (CRF), 81 on maintenance haemodialysis (HD) and 37 renal transplant recipients (RTR) were prospectively followed for 24 months. ADMA and SDMA were measured by HPLC. The relation of plasma levels of ADMA and SDMA together with conventional risk factors for the cardiovascular and renal outcome was investigated with Cox proportional hazards model. RESULTS: Mean serum levels of SDMA were significantly increased in all groups compared to the control group (P

In vitro investigations on the differential pro-oxidant and/or antioxidant properties of cyclosporin A and tacrolimus in human and rat liver microsomes.

OBJECTIVE: The use of cyclosporin A (CSA) and tacrolimus (TAC) in organ transplantation and in the therapy of immune disorders is often hampered by adverse effects, mainly nephro-, hepato- and neurotoxicity. For the development of these side effects, among others, an increased formation of reactive oxygen species, probably generated by the cytochrome P450 (CYP) system, has been accused. Since in this respect literature data are inconsistent, in the present study possible pro- and/or antioxidant effects of CSA and TAC and the involvement of the CYP system were re-evaluated in vitro. METHODS: Effects of CSA and TAC were examined on CYP mediated oxidase functions by stimulated lipid peroxidation (LPO), H2O2 production, and lucigenin (LC) or luminol (LM) amplified chemiluminescence (CL) in liver microsomes of either untreated rats or of rats treated with beta-naphthoflavone (BNF), phenobarbital (PB) or dexamethasone (DEX) and in human liver microsomes. RESULTS: In rat liver microsomes, CSA displayed pro-oxidant properties (though only very slightly), whereas in human liver microsomes small antioxidant effects were seen. With TAC in both species the antioxidant capacity prevailed. Treatment of rats with BNF or DEX caused an increase in the pro-oxidant effects of CSA with respect to LPO or LM-CL, whereas in liver microsomes of DEX-treated rats H2O2 production and LC-CL were diminished. CONCLUSIONS: CSA seems to have both pro-oxidant and antioxidant properties, whereas with TAC mainly an antioxidant capacity was seen. The CYP system seems to be involved in the pro-oxidant influence of CSA. Whether pro-oxidant or antioxidant effects predominate may depend on the antioxidant capacity of a tissue and on the CYP isoforms mainly present.

Effect of stress ratio on the fatigue behaviour of compact bone.

During the fatigue process of bone, cracks generally initiate from the inherent defects existing in the bone. The fatigue lives of bone specimens at different stress levels as well as at different stress ratios R were evaluated using a computer simulation in which the crack propagation behaviour initiated from the inherent defects in the bone are herein considered. The S-N curves as well as the distributions of fatigue lives obtained by the simulations accurately conform with the experimental results. With the strain threshold epsilon(max) representing fatigue failure of the bone specimen, the values of 1500 microepsilon for R = -1, 2500 microepsilon for R = 0.1 and 4000 microepsilon for R = 10 were extrapolated from the simulations. These values conform with experimental values reported in the literature. Such conformity indicates that the strain threshold for fatigue failure is associated with the threshold value for crack propagation.

Effect of smoking on risk factors for cardiovascular disease in patients with diabetes mellitus and renal insufficiency.

BACKGROUND: Many studies have been published demonstrating a strong correlation between smoking, renal lesions and cardiovascular morbidity and mortality. Possible contributing factors are elevated blood pressure values, changes in vascular reactivity, concentrations of lipids, fibrinogen and carboxyhemoglobin, in patients with diabetes mellitus, the quality of diabetes control and insulin resistance. Other possible risk factors may include advanced glycation end (AGE)-products, total plasma homocysteine and metabolites as well as symmetrical (SDMA) and asymmetrical (ADMA) dimethylarginine. It was the goal of the present trial to investigate the serum concentrations of these >new<, possible risk factors in a selection free population of patients with type 1 and insulin-treated type 2 diabetes mellitus, in patients with chronic renal insufficiency and in renal transplant recipients. The second aim was to analyse the effect of cigarette smoking on the levels of these laboratory parameters. PATIENTS AND METHODS: A total of 544 subjects (n = 98 patients with chronic renal insufficiency without hemodialysis, n = 84 patients with hemodialysis, n = 50 renal transplant recipients, n = 114 patients with type 1 and n = 147 patients with insulin treated type 2 diabetes mellitus, n = 51 healthy controls) participated in the trial. RESULTS: Patients with renal insufficiency had significantly higher concentrations of the AGE-products N-epsilon-Carboxymethyllysine (CML) and pentosidine compared with both groups of patients with insulin-treated diabetes mellitus and the healthy controls. In patients with type 1 diabetes there was a positive correlation between HbA1c and the concentration of CML (r = 0.405, p = 0.017) and between the pentosidine-concentration and the serum creatinine-level (r = 0.482, p = 0.001). In type 2 diabetes there was a correlation between CML and diastolic blood pressure (r = 0.239, p = 0.039). In comparison to the healthy controls, patients with renal diseases and patients after kidney transplantation had higher concentrations of total plasma homocysteine and its metabolites. Similar results were found for SDMA and ADMA: Patients with chronic renal insufficiency both with and without hemodialysis had significantly higher values than the renal transplant recipients and healthy controls. A clear influence of cigarette smoking on the levels of the laboratory parameters measured could not be determined in any group; neither in the patients with diabetes mellitus, nor in the patients with renal diseases, nor in the healthy controls. CONCLUSIONS: The present trial demonstrates an increase in the parameters linked to the development of cardiovascular diseases including total plasma homocysteine, its metabolites, the dimethylarginines SDMA and ADMA and advanced glycation end-products depending on the degree of renal insufficiency. Moreover, in patients with insulin-treated diabetes mellitus, the concentrations of the AGE-products CML and pentosidine seem to be strongly influenced by the quality of diabetes control and blood pressure levels. There was no influence of cigarette smoking on the levels of the laboratory parameters measured.

Regulation of renal amino acid (AA) transport by hormones, drugs and xenobiotics - a review.

Major advances have recently been made in our understanding of the mechanisms and functions of amino acid transport in mammalian cells: - from the whole organism to transporter molecular structure. In this article, we present a brief overview of current knowledge concerning amino acid transporters, followed by a detailed discussion of the relevance of this new information to our broader understanding of the physiological regulation of amino acid handling in the kidney. We focus especially on the influence of hormones and xenobiotics on renal amino acid transport systems. In a growing number of cases, it now seems possible to correlate the effects of hormones, drugs, and xenobiotics with the capacity of renal amino acid transporters. This topic is of clinical relevance for the treatment of many amino acid reabsorption disorders. For example, under suitable conditions glucocorticoids and thyroid hormones stimulate renal reabsorption of amino acids and might therefore be of benefit in the treatment of different kinds of aminoaciduria. Hormonal regulation also underlies the postnatal development of renal amino acid reabsorption capacity, which can be stimulated to mature earlier after exogenous administration of e.g. glucocorticoids. In contrast, many compounds (e.g. heavy metal complexes) selectively damage renal amino acid transporters resulting in urinary amino acid loss. These types of phenomena (stimulation or inhibition of amino acid transporters in the kidney) are reviewed from the perspectives of our new molecular understanding of transport processes and of clinical relevance.