Photodynamic antibacterial effect of graphene quantum dots

Synthesis of new antibacterial agents is becoming increasingly important in light of the emerging antibiotic resistance. In the present study we report that electrochemically produced graphene quantum dots (GQD), a new class of carbon nanoparticles, generate reactive oxygen species when photoexcited (470 nm, 1 W), and kill two strains of pathogenic bacteria, methicillin-resistant Staphylococcus aureus and Escherichia coli. Bacterial killing was demonstrated by the reduction in number of bacterial colonies in a standard plate count method, the increase in propidium iodide uptake confirming the cell membrane damage, as well as by morphological defects visualized by atomic force microscopy. The induction of oxidative stress in bacteria exposed to photoexcited GQD was confirmed by staining with a redox-sensitive fluorochrome dihydrorhodamine 123. Neither GQD nor light exposure alone were able to cause oxidative stress and reduce the viability of bacteria. Importantly, mouse spleen cells were markedly less sensitive in the same experimental conditions, thus indicating a fairly selective antibacterial photodynamic action of GQD.     

All near-infrared multiparametric luminescence thermometry using Er3+, Yb3+-doped YAG nanoparticles

This paper presents four new temperature readout approaches to luminescence nanothermometry in spectral regions of biological transparency demonstrated on Yb³⁺/Er³⁺-doped yttrium aluminum garnet nanoparticles. Under the 10 638 cm⁻¹ excitation, down-shifting near infrared emissions (>10 000 cm⁻¹) are identified as those originating from Yb³⁺ ions'' ²F_5/2 → ²F_7/2 (∼9709 cm⁻¹) and Er³⁺ ions'' ⁴I_13/2 → ⁴I_15/2 (∼6494 cm⁻¹) electronic transitions and used for 4 conceptually different luminescence thermometry approaches. Observed variations in luminescence parameters with temperature offered an exceptional base for studying multiparametric temperature readouts. These include the temperature-dependence of: (i) intensity ratio between emissions from Stark components of Er^{3+ 4}I_13/2 level; (ii) intensity ratio between emissions of Yb³⁺ (²F_5/2 → ²F_7/2 transition) and Er³⁺ (⁴I_13/2 → ⁴I_15/2 transition); (iii) band shift and bandwidth and (iv) lifetime of the Yb³⁺ emission (²F_5/2 → ²F_7/2 transition) with maximal sensitivities of 1% K⁻¹, 0.8% K⁻¹, 0.09 cm⁻¹ K⁻¹, 0.46% K⁻¹ and 0.86% K⁻¹, respectively. The multimodal temperature readout provided by this material enables its application in different luminescence thermometry setups as well as improved the reliability of the temperature sensing by the cross-validation between measurements.

Four completely new NIR luminescence temperature readouts in the second and third biological windows are demonstrated with YAG:Er³⁺, Yb³⁺ nanoparticles.     

Plasmafiltration as an effective method in the removal of circulating pegylated liposomal doxorubicin (PLD) and the reduction of mucocutaneous toxicity during the treatment of advanced platinum-resistant ovarian cancer

Cancer Chemotherapy and Pharmacology - The present study evaluates the safety and efficacy of double-plasma filtration (PF) to remove the exceeding pegylated liposomal doxorubicin (PLD) in...     

Heat Source Modeling and Residual Stress Analysis for Metal Directed Energy Deposition Additive Manufacturing

The advancement in additive manufacturing encourages the development of simplified tools for deep and swift research of the technology. Several approaches were developed to reduce the complexity of multi-track modeling for additive manufacturing. In the present work, a simple heat source model called concentrated heat source was evaluated for single- and multi-track deposition for directed energy deposition. The concentrated heat source model was compared with the widely accepted Goldak heat source model. The concentrated heat source does not require melt pool dimension measurement for thermal model simulation. Thus, it reduces the considerable time for preprocessing. The shape of the melt pool and temperature contour around the heat source was analyzed for single-track deposition. A good agreement was noticed for the concentrated heat source model melt pool, with an experimentally determined melt pool, using an optical microscope. Two heat source models were applied to multi-track 3D solid structure thermo-mechanical simulation. The results of the two models, for thermal history and residual stress, were compared with experimentally determined data. A good agreement was found for both models. The concentrated heat source model reported less than the half the computational time required for the Goldak model. The validated model, for 3D solid structure thermo-mechanical simulation, was used to analyze thermal stress evolution during the deposition process. The material deposition on the base plate at room temperature results in lower peak temperatures in the layers near the base plate. Consequently, the higher thermal stress in the layers near the base plate was found, compared to the upper layers during the deposition process.     

Early development of the human dentition revisited

In this review, classical data on the early steps in human odontogenesis are summarized and updated with specific insights into the development of the upper and lower embryonic jaws to help in understanding some oral pathologies. The initial step of human odontogenesis is classically characterized by two parallel horseshoe‐shaped epithelial laminae. These originate from the oral epithelium and an ingrowth into the jaw mesenchyme: the internal dental lamina gives rise to deciduous tooth primordia, while the external vestibular lamina represents the developmental base of the oral vestibule. However, a more complex situation was revealed by recent studies combining analyses of the dental and adjacent oral epithelia on histological sections and computer‐aided three‐dimensional (3D) reconstructions during the 2nd month of human embryonic development. The dental epithelium forms a mound, where swellings appear later, corresponding to the individual primordia of deciduous teeth. External to the developing deciduous dentition, the 3D reconstructions do not show any continuous vestibular lamina but instead a complex of discontinuous epithelial bulges and ridges. The patterns of these epithelial structures and their relationship to the dental epithelium differ not only between the upper and lower jaws but also between the lip and cheek segments in each jaw. Knowledge of early odontogenesis may help in understanding some oral pathologies. For example, the human lateral incisor has a dual origin: it arises in the area of fusion between the medial nasal and maxillary facial processes and involves material from these two regions. Such a dual origin at the site of fusion of facial processes represents a predisposition to developmental vulnerability for the upper lateral incisor, resulting in its frequent anomalies (absence, hypoplasia, duplication), especially in patients with a cleft lip and/or jaw. Other pathologies, such as a minute supernumerary tooth, desmoplastic ameloblastoma or extraosseous odontogenic cysts are located external to the upper or lower dentition, and might be derived from structures that transiently appear during early development of the oral vestibule in humans.     

A radiofrequency-assisted minimal blood loss liver parenchyma dissection technique

BACKGROUND/AIMS: Intraoperative blood loss is still a major concern for surgeons operating on the liver since it is associated with a significantly higher rate of postoperative complications and shorter long-term survival. An original radiofrequency (RF)-assisted minimal blood loss technique for transecting liver parenchyma is presented. METHODS: In a prospective study, starting November 2001 and ending December 2005, a total of 90 RF-assisted liver resections were done. Pre-cut coagulative desiccation was produced by the Cool-tip (Valleylab, Tyco) water-cooled, single, RF tumor ablation electrode connected to a 480-kHz 200 W generator (Valleylab Cool-tip RF System). Vascular occlusion techniques and low central venous pressure anesthesia were not used. RESULTS: Only 14 (15.5%) patients received blood transfusion (mean transfused blood volume 397 ml; mode 310 ml) and 10 of 14 patients received <310 ml of blood. There was no statistical difference between the patients who underwent major and minor liver resection in frequency of blood transfusion. Blood loss was associated with dense adhesions and difficult liver mobilization and not with liver transection. CONCLUSION: The 'sequential coagulate-cut' RF-assisted liver resection technique is a safe liver transection technique associated with minimal blood loss and it has facilitated tissue-sparing liver resection.     

Prevention of congenital toxoplasmosis in Slovenia by serological screening of pregnant women

A programme for the prevention of congenital toxoplasmosis in Slovenia involving the screening of pregnant women for Toxoplasma infection is presented. Of 21,270 pregnant women screened for toxoplasmosis between, 1996 and the end of 1999, 13,987 (66%) were seronegative, 7,151 (34%) seropositive and 132 had primary infection; approximately 9/1,000 women were at risk of acquiring the primary infection. One hundred live-born infants of primary infected women were available for follow-up. Nine infected but asymptomatic children were born to mothers who were screened and treated in time and two congenitally infected babies were born to mothers in whom infection was detected too late in pregnancy and who therefore received no adequate treatment. It is suggested that the results obtained in this study outweigh the cost of screening for toxoplasmosis in pregnancy. Pregnant women should always be tested at the beginning of pregnancy and, in cases of seronegativity, should be re-tested in the second and third trimesters of the pregnancy. Toxoplasma primary infected pregnant women and neonates should be treated as soon as possible. However, long-term follow-up of children born to primary infected women would be necessary for an accurate evaluation of the effectiveness of the screening because of the possibility of late onset of symptoms.