The peculiar size and temperature dependence of water diffusion in carbon nanotubes studied with 2D NMR diffusion-relaxation D -T 2eff spectroscopy.

It is well known that water inside hydrophobic nano-channels diffuses faster than bulk water. Recent theoretical studies have shown that this enhancement depends on the size of the hydrophobic nanochannels. However, experimental evidence of this dependence is lacking. Here, by combining two-dimensional nuclear magnetic resonance diffusion-relaxation ( D - T 2 e f f ) spectroscopy in the stray field of a superconducting magnet and molecular dynamics simulations, we analyze the size dependence of water dynamics inside Carbon Nanotubes (CNTs) of different diameters ( 1.1 - 6.0 nm), in the temperature range of 265 - 305 K. Depending on the CNT diameter, the nanotube water is shown to resolve in two or more tubular components acquiring different self-diffusion coefficients. Most notably, a favorable CNT diameter range ( 3.0 - 4.5 nm) is experimentally verified for the first time, in which water molecule dynamics at the center of the CNTs exhibits distinctly non-Arrhenius behavior, characterized by ultrafast diffusion and extraordinary fragility, a result of significant importance in the efforts to understand water behavior in hydrophobic nanochannels.

Antibacterial properties and regenerative potential of Sr2+ and Ce3+ doped fluorapatites; a potential solution for peri-implantitis.

Scaffolds and implants in orthopaedics and regenerative dentistry usually fail because of bacterial infections. A promising solution would be the development of biomaterials with both significant regenerative potential and enhanced antibacterial activity. Working towards this direction, fluorapatite was synthesised and doped with Sr2+ and Ce3+ ions in order to tailor its properties. After experiments with four common bacteria (i.e. E. Coli, S. Aureus, B. Subtilis, B. Cereus), it was found that the undoped and the Ce3+ doped fluorapatites present better antibacterial response than the Sr2+ doped material. The synthesised minerals were incorporated into chitosan scaffolds and tested with Dental Pulp Stem Cells (DPSCs) to check their regenerative potential. As was expected, the scaffolds containing Sr2+-doped fluorapatite, presented high osteoconductivity leading to the differentiation of the DPSCs into osteoblasts. Similar results were obtained for the Ce3+-doped material, since both the concentration of osteocalcin and the RUNX2 gene expression were considerably higher than that for the un-doped mineral. Overall, it was shown that doping with Ce3+ retains the good antibacterial profile of fluorapatite and enhances its regenerative potential, which makes it a promising option for dealing with conditions where healing of hard tissues is compromised by bacterial contamination.

Human Leukocyte Antigen Compatibility and De Novo Donor-Specific Antibodies in Long-term Renal Transplant Patients With Stable Graft Function.

PURPOSE: De novo donor-specific antibodies (DSA) are associated with antibody-mediated rejection leading to late renal transplant failure. The aim of this study was to evaluate whether HLA compatibility is associated with sensitization along with other risk factors. METHODS: Eighty-nine stable renal transplant recipients (47 men) were studied. Patients were classified into 2 groups according to HLA compatibility between donor and recipient, group A (1-4/8 matches) and group B (5-8/8 matches). Cold ischemia time (CIT) and delayed graft function (DGF) were recorded along with time with a functional graft. Anti-HLA antibodies were detected using a Luminex single-antigen bead assay and were further classified into DSA and non-DSA. RESULTS: HLA group A consisted of 49 (56%) transplant recipients while 38 (44%) were classified to group B, with functional grafts for 10.9 ± 6.7 and 14.8 ± 8.5 years, respectively (P = .019). Group A patients had more anti-HLA antibodies than group Β (P = .001) and this correlation was retained for DSA patients. De novo anti-HLA were detected in 40 patients; DSA were detected in 19 (21.8%). DSA (+) patients had recorded with functional renal grafts for 11 ± 5 years, compared to 14.4 ± 8.6 years (P = .048) for anti-HLA negative patients. Increased CIT and DGF were associated with anti-HLA antibodies detection but no with DSA. CONCLUSION: HLA compatibility is probably correlated with DSA in a context of a more general anti-HLA sensitization, and both have a negative effect on long-term renal graft outcome.

Prevalence and Impact of Reformed and De Novo Anti-HLA Donor-Specific Antibodies in Liver Transplantation.

INTRODUCTION: The prevalence and impact of pre-existing and de novo anti-HLA donor-specific antibodies (DSAs) after orthotopic liver transplantation (OLT) is still controversial. We investigated the prevalence of DSAs and their implication in the development of allograft dysfunction after OLT. PATIENTS AND METHODS: A total of 65 liver transplant patients were tested for anti-HLA antibodies, with single antigen bead technology, before, 1, 3, 6, and 12 months after transplantation, and thereafter annually, along with other risk factors. Sixteen out of 65 patients (24.6%) had circulating pre-existing anti-HLA antibodies, and 4 of them (25%) had DSAs. All patients positive for anti-HLA antibodies (100%) presented allograft dysfunction. Fourteen out of 65 patients (21.5%) had circulating de novo DSAs, and 12 out of 14 (85.7%) presented allograft dysfunction. The investigated risk factors for allograft dysfunction were: recipient and donor age, time on the waiting list, cold ischemia time, cytomegalovirus infection, immunosuppression regimen, de novo DSAs, Model for End-Stage Liver Disease, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase (GGT), direct bilirubin and total bilirubin peak post-transplant, and alkaline phosphatase. The multivariate analysis showed that de novo DSAs and time on the waiting list were independent risk factors for allograft dysfunction. CONCLUSION: Our results show that de novo DSAs are an independent risk factor for allograft dysfunction, along with time on the waiting list.

Posterior reversible encephalopathy syndrome as a complication of bacterial meningitis.

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is a clinical-radiological syndrome, which is presented with headache, seizures, altered mental consciousness, and visual disturbances, and is characterized by white matter vasogenic edema, predominantly affecting the posterior occipital and parietal lobes of the brain. This clinical syndrome is increasingly recognized due to the improvement and availability of brain imaging and, more specifically, magnetic resonance imaging. CASE REPORT: We report the case of an otherwise healthy 20-year-old female who presented with fever, headache, and generalized arthralgia, raising the suspicion of Neisseria meningitidis serotype B meningitis, which was later complicated by PRES. The patient was treated with the antiepileptic drug levetiracetam, mannitol, and dexamethasone. Her mental status was completely restored in 3-4 days after the initiation of the treatment for PRES and was characterized by rapid clinical recovery. CONCLUSION: PRES is a neurotoxic state characterized by a unique brain imaging pattern typically associated with a number of complex clinical conditions including infection, sepsis, and shock. The syndrome should be promptly recognized since it is reversible and treatable. HIPPOKRATIA 2019, 23(2): 131-134.

Gravity as Gauge Theory Squared: A Ghost Story.

The Becchi-Rouet-Stora-Tyutin (BRST) transformations and equations of motion of a gravity-two-form-dilaton system are derived from the product of two Yang-Mills theories in a BRST covariant form, to linear approximation. The inclusion of ghost fields facilitates the separation of the graviton and dilaton. The gravitational gauge fixing term is uniquely determined by those of the Yang-Mills factors which can be freely chosen. Moreover, the resulting gravity-two-form-dilaton Lagrangian is anti-BRST invariant and the BRST and anti-BRST charges anticommute as a direct consequence of the formalism.

Exogenous mineralization of hard tissues using photo-absorptive minerals and femto-second lasers; the case of dental enamel.

A radical new methodology for the exogenous mineralization of hard tissues is demonstrated in the context of laser-biomaterials interaction. The proposed approach is based on the use of femtosecond pulsed lasers (fs) and Fe3+-doped calcium phosphate minerals (specifically in this work fluorapatite powder containing Fe2O3 nanoparticles (NP)). A layer of the synthetic powder is applied to the surface of eroded bovine enamel and is irradiated with a fs laser (1040 nm wavelength, 1 GHz repetition rate, 150 fs pulse duration and 0.4 W average power). The Fe2O3 NPs absorb the light and may act as thermal antennae, dissipating energy to the vicinal mineral phase. Such a photothermal process triggers the sintering and densification of the surrounding calcium phosphate crystals thereby forming a new, dense layer of typically ∼20 µm in thickness, which is bonded to the underlying surface of the natural enamel. The dispersed iron oxide NPs, ensure the localization of temperature excursion, minimizing collateral thermal damage to the surrounding natural tissue during laser irradiation. Simulated brushing trials (pH cycle and mechanical force) on the synthetic layer show that the sintered material is more acid resistant than the natural mineral of enamel. Furthermore, nano-indentation confirms that the hardness and Young's modulus of the new layers are significantly more closely matched to enamel than current restorative materials used in clinical dentistry. Although the results presented herein are exemplified in the context of bovine enamel restoration, the methodology may be more widely applicable to human enamel and other hard-tissue regenerative engineering. STATEMENT OF SIGNIFICANCE: In this work we provide a new methodology for the mineralisation of dental hard tissues using femtosecond lasers and iron doped biomaterials. In particular, we demonstrate selective laser sintering of an iron doped fluorapatite on the surface of eroded enamel under low average power and mid-IR wavelength and the formation of a new layer to substitute the removed material. The new layer is evaluated through simulated brushing trials and nano-indentation. From the results we can conclude that is more acid resistant than natural enamel while, its mechanical properties are superior to that of current restorative materials. To the best of our knowledge this is the first time that someone demonstrated, laser sintering and bonding of calcium phosphate biomaterials on hard tissues. Although we here we discuss the case of dental enamel, similar approach can be adopted for other hard tissues, leading to new strategies for the fixation of bone/tooth defects.

ß-pyrophosphate: A potential biomaterial for dental applications.

Tooth hypersensitivity is a growing problem affecting both the young and ageing population worldwide. Since an effective and permanent solution is not yet available, we propose a new methodology for the restoration of dental enamel using femtosecond lasers and novel calcium phosphate biomaterials. During this procedure the irradiated mineral transforms into a densified layer of acid resistant iron doped ß-pyrophosphate, bonded with the surface of eroded enamel. Our aim therefore is to evaluate this densified mineral as a potential replacement material for dental hard tissue. To this end, we have tested the hardness of ß-pyrophosphate pellets (sintered at 1000°C) and its mineral precursor (brushite), the wear rate during simulated tooth-brushing trials and the cytocompatibility of these minerals in powder form. It was found that the hardness of the ß-pyrophosphate pellets is comparable with that of dental enamel and significantly higher than dentine while, the brushing trials prove that the wear rate of ß-pyrophosphate is much slower than that of natural enamel. Finally, cytotoxicity and genotoxicity tests suggest that iron doped ß-pyrophosphate is cytocompatible and therefore could be used in dental applications. Taken together and with the previously reported results on laser irradiation of these materials we conclude that iron doped ß-pyrophosphate may be a promising material for restoring acid eroded and worn enamel.

Ultraviolet radiation and effects on humans: the paradigm of maternal vitamin D production during pregnancy.

Current evidence indicates that neonates born of mothers with vitamin D deficiency during pregnancy have greater risk for developing hypocalcemia, rickets and extra-skeletal disorders. Despite the classic knowledge that ultraviolet-B (UVB) exposure is the most efficient way for a future mother to obtain optimal vitamin D concentrations, no current consensus or clinical recommendations exist regarding the duration and timing of UVB exposure for pregnant women. This article offers a narrative review of available data regarding how UVB exposure affects maternal vitamin D production during pregnancy, along with a discourse on clinical implications of this public health issue. Future studies would benefit from adopting UVB exposure estimates to recommend appropriate UVB exposure to pregnant women. Doing so could provide a more holistic and practical approach in managing maternal hypovitaminosis D during pregnancy.

Neuroradiological, neurophysiological and molecular findings in infantile Krabbe disease: two case reports.

Krabbe disease is an autosomal recessive neurodegenerative disorder due to a defect of the lysosomal enzyme ß-galactocerebrosidase (ß-GALC). Depending on the age of onset, the disease is classified into infantile and later-onset forms. We report neuroradiological, neurophysiological and molecular findings in two Greek patients with the infantile form of Krabbe disease. The index patients presented at the age of 3.5 and 6 months, respectively, due to developmental delay. Magnetic resonance imaging (MRI) of the first patient's brain demonstrated signs of leukodystrophy, while nerve conduction velocities (NCVs) were significantly decreased. The second patient's MRI at the age of 4 months was initially normal, but at 18 months demonstrated leukodystrophic alterations as well, whereas NCVs were also significantly delayed. In both patients, a severe decrease in ß-GALC, activity supported the diagnosis of Krabbe disease, while the final diagnosis was confirmed by molecular genetic testing. Two homozygous mutations of the GALC gene, the c.411_413delTAA [p.K139del] mutation in the first patient, and the c.749T>C [p.I250T] mutation in the second patient, were identified. At their last follow-up visit at the age of 4 and 6 years, respectively, both patients were bedridden and quadri-plegic, suffering from frequent respiratory tract infections and fed through a gastrostomy. Both mutations found in homozygosity in these two unrelated patients of Greek ancestry, could pinpoint a common origin. Genotyping of patients with Krabbe disease is important, in order to contribute to the creation of a European mutation database and to further study possible genotype-phenotype correlations of the disease.

Monitoring of compliance on an individual treatment through mobile innovations.

The present work examines the potential of smartphone usage for offering health services to elderly patients. The purpose of this work is the design, development, and implementation of a telemedicine application. This application aims to improve the monitoring mode and increase patient adherence to the instructions assigned by the medical staff. It consists of three parts: the doctor's application (Web Application), the patient's application (Android Application) and the Web Server of the platform, where the database is stored necessary for the smooth operation of the platform. Also the Web Server hosts the doctor's Web Application. The Web Application is based on web front-end technologies, providing the medical personnel with a variety of features and useful actions. These actions and capabilities are mainly relevant to the assignment of instructions to patients and the monitoring of their health progress. The Android Application has been implemented and validated for the Android-based mobile devices operating system and consists of a handy and user-friendly environment, equipped with the right tools so that the patient has the ability to update the system on the progress of his/her health by storing the appropriate measurements. Both applications also provide customization capabilities in regards to the patients' and doctors' profile.

Yang-Mills origin of gravitational symmetries.

By regarding gravity as the convolution of left and right Yang-Mills theories together with a spectator scalar field in the biadjoint representation, we derive in linearized approximation, the gravitational symmetries of general covariance, p-form gauge invariance, local Lorentz invariance, and local supersymmetry from the flat space Yang-Mills symmetries of local gauge invariance and global super-Poincaré symmetry. As a concrete example, we focus on the new minimal (12+12) off shell version of simple four-dimensional supergravity obtained by tensoring the off shell Yang-Mills multiplets (4+4, N_{L}=1) and (3+0, N_{R}=0).

Incidence of pituitary incidentalomas in patients with adrenal adenomas.

With the advent of modern imaging modalities, endocrine incidentalomas are increasingly being discovered. We aimed to investigate the presence of pituitary incidentalomas (PI) in patients with adrenal incidentalomas (AI), and identify potential metabolic correlates in this cohort. 26 patients (18 females) with AI discovered on abdominal computerized tomography were studied. All patients underwent pituitary magnetic resonance imaging (MRI) and endocrine investigations to evaluate functional adrenal pathology, anterior pituitary hormonal status, insulin-resistance indices and presence of metabolic syndrome. Pituitary MRI revealed a microadenoma and a 4×5 mm cyst in 1 patient respectively, and an empty sella in 4 (2 partial) patients. Overall, 6/26 (23%) patients with an AI had evidence of pituitary imaging pathology but only 8% had a PI; none had any evidence of abnormalities in pituitary function. Subclinical hypercortisolism was the only hyperfunctional status detected in 4 patients with AI but was unrelated to the pituitary findings. No abnormality of insulin secretion and action was found between patients with or without pituitary pathology. In the present study 23% of patients with AI had some alteration in pituitary morphology, and 2 a PI without accompanying pituitary hormonal deficit or metabolic derangement. Further studies are required to address this issue and identify a potential pathogenetic mechanism.

Experimental investigation of the flow of a blood analogue fluid in a replica of a bifurcated small artery.

The scope of this work is to study the pulsatile flow of a blood mimicking fluid in a micro channel that simulates a bifurcated small artery, in which the Fahraeus-Lindqvist effect is insignificant. An aqueous glycerol solution with small amounts of xanthan gum was used for simulating viscoelastic properties of blood and in vivo flow conditions were reproduced. Local flow velocities were measured using micro Particle Image Velocimetry (µ-PIV). From the measured velocity distributions, the wall shear stress (WSS) and its variation during a pulse were estimated. The Reynolds numbers employed are relatively low, i.e. similar to those prevailing during blood flow in small arteries. Experiments both with a Newtonian and a non-Newtonian fluid (having asymptotic viscosity equal to the viscosity of the Newtonian one) proved that the common assumption that blood behaves as a Newtonian fluid is not valid for blood flow in small arteries. It was also shown that the outer wall of the bifurcation, which is exposed to a lower WSS, is more predisposed to atherosclerotic plaque formation. Moreover, this region in small vessels is shorter than the one in large arteries, as the developed secondary flow decays faster. Finally, the WSS values in small arteries were found to be lower than those in large ones.

Cerebral amyloid angiopathy.

The aim of this report was to describe the case of an elderly patient with cerebral amyloid angiopathy and associated dementia who presented with new onset symptomatology compatible with an acute cerebrovascular event. Computed tomography scanning was suggestive of an incipient ischemic cerebrovascular event. Magnetic resonance imaging was requested due to the presence of small hyperdense lesions on CT, and revealed multiple diffuse hypodense parenchymal lesions with hemosiderin deposits, indicative of cerebral amyloid angiopathy. Diagnosis of the underlying pathology is of importance, as aspirin use, and antiplatelet use in general, may in these patients be associated with microbleed burden.

A patient with Lemierre syndrome.

Lemierre syndrome, also known as postanginal sepsis, is a severe complication of an acute oropharyngeal infection that results in septic thrombophlebitis of the ipsilateral internal jugular vein with subsequent septicemia, often complicated by metastatic infections (Syed et al., Laryngoscope 117:1605-1610, 2007). We present the case of a previously healthy 12-year-old boy with Lemierre syndrome, caused by streptococci (Abiotrophia defectiva), complicating a subcutaneous neck abscess. The patient had metastatic sequelae, was treated with antibiotics (clindamycin and vancomycin) and low molecular weight heparin, and had an uneventful outcome.

Prevalence and correlates of depression in late life: a population based study from a rural Greek town.

BACKGROUND: Depression in late life is common and has serious consequences on function, medical co-morbidity, quality of life, and use of medical services. OBJECTIVE: To estimate the age- and gender-specific prevalence of depression among people over 60 years of age, and to examine correlates of depression, in particular the relationship between depression and cognitive impairment. METHOD: From a total of 965 inhabitants, aged over 60 years, in Velestino, a rural town in central Greece, 608 were accessible and constituted the target population. During a five-month period in 2000, a trained health visitor interviewed all study participants. The interview covered socio-demographic characteristics, medical history, and administration of the 15-question Geriatric Depression Scale (GDS-15) and the Mini Mental Scale Examination instrument (MMSE). RESULTS: The prevalence of mild or more severe depression (GDS> or =7) was 27%, while the prevalence of moderate to severe depression (GDS> or =11) was 12%. Increasing age, female gender, lower education, and being currently unmarried were associated with higher risk of depression in univariate regression models, but these associations disappeared after controlling for cognitive function, except for the association with marital status. Cognitive impairment was strongly associated with increased risk for depression. The co-morbid presence of digestive, neurological and heart conditions was also associated with increased risk for depression, while cancer was not. CONCLUSION: In a rural Greek area, the prevalence of depression in late life is high. Depression was more common among unmarried individuals, those with significant cognitive impairment, and in association with specific medical conditions.

Ex vivo magnetic resonance imaging of the distal row of equine carpal bones: assessment of bone sclerosis and cartilage damage.

The distal row of carpal bones (C2, C3, and C4) from eight left intercarpal joints--four from Standardbred Trotters and four from Swedish Warmblood horses--were used to assess the potential of magnetic resonance (MR) imaging to detect cartilage and bone lesions. The joints used in the study were classified by macroscopic and radiographic examinations as having normal, mild, moderate, or severe articular cartilage lesions and bone sclerosis. Those classifications correlated well with the appearance of the MR images. Bone sclerosis in the MR images was observed as regions of decreased signal intensity. Upon quantitative analysis of the MR images there was a significant difference (p < 0.0001) in the MR signal intensity from areas where radiographic bone sclerosis was observed compared to areas of radiographic nonsclerotic bone. In addition, the MR images were used to pilot the location of histology slices through areas of interest that were then examined microscopically; hence, the lesions found from the MR imaging examination were verified microscopically. It was concluded that cartilage lesions and cartilage loss are related to the sclerotic state of the underlying bone. The MR protocols developed in this study were applied on five intact cadaveric carpal joints, and it was concluded that MR imaging could successfully be used in the intact joint to detect minor cartilage and bone lesions not visualized by either radiography or macroscopic examination. Hence, MR imaging can be used to delineate interactions between articular cartilage and subchondral bone over time and in vivo.

Pituitary abscess presenting with cranial nerve paresis. Case report and review of literature.

Non-adenomatosus lesions of the pituitary represent a small part of the intrasellar processes and they have heterogeneous presentation. Making a precise diagnosis is of great importance, as it may lead to more efficient management. A 65-year-old man was admitted to the hospital because of headache and right cranial nerve III palsy. Basic laboratory work-up was normal whereas endocrinological assessment revealed hypopituitarism without diabetes insipidus. Plain radiography showed an enlarged sella and frontal and paranasal sinusitis. Computed tomography (CT) and magnetic resonance imaging (MRI) of the sella revealed an intrasellar lesion with extension to the sphenoid and cavernous sinuses as well as the suprasellar region, exerting pressure on the optic chiasm. On T1-weighted images the mass had a low-intensity signal with a smooth enhancing rim with bright signal. Given the presence of multiple sinusitis and imaging characteristics a pre-operative diagnosis of pituitary abscess was made. The patient was operated via transphenoidal route and purulent material was drained out. Cultures of the material were positive for Staphylococcus aureus. Antibiotics as well as cortisol replacement therapy were given. Three months later hypopituitarism persisted but there was significant improvement in the neurological findings. We report a case of an unusual presentation of a pituitary abscess. High index of suspicion, the presence of associated conditions such as pituitary tumors, meningitis or sinusitis, as well as diabetes insipidus and specific imaging features are the main diagnostic clues. Pre-operative diagnosis, which will lead to prompt antibiotic therapy and transphenoidal drainage, can decrease high mortality and morbidity associated with this disease.