Enhanced emission of ultra-small-sized LaF3:RE3+ (RE = Eu, Tb) nanoparticles through 1,2,4,5-benzenetetracarboxylic acid sensitization

Uniform, ultra-small-sized and well-water-dispersible LaF(3) nanoparticles doped with trivalent rare earth (RE) ions (Eu(3+) or Tb(3+)) have been synthesized by a simple, low temperature synthesis route. The nanoparticles, with sizes of about 3.2 nm (for those doped with Eu(3+)) and 3.0 nm (for those doped with Tb(3+)), are roughly spherical and monodisperse. 1,2,4,5-Benzenetetracarboxylic acid (labeled as BA) as sensitizer has been bonded to the surface of the nanoparticles, which can sensitize the emission of RE(3+) in the LaF(3) nanoparticles. The BA-LaF(3):RE(3+) (RE = Eu or Tb) nanoparticles have a broad absorption band in the UV domain, and show enhanced luminescence of RE(3+) based on an energy transfer from BA ligands to RE(3+) ions (i.e. the so-called "antenna effect"). Due to the dual protection of organic ligands (BA) and inorganic matrices (LaF(3)), BA-LaF(3):RE(3+) (RE = Eu or Tb) nanoparticles have longer excited state lifetimes than LaF(3):RE(3+) (RE = Eu or Tb) nanoparticles as well as lanthanide coordination polymers of BA.

Doxorubicin conjugated NaYF(4):Yb(3+)/Tm(3+) nanoparticles for therapy and sensing of drug delivery by luminescence resonance energy transfer

In this study, we report an anticancer drug delivery system based on doxorubicin (DOX)-conjugated NaYF(4):Yb(3+)/Tm(3+) nanoparticles. The as-synthesized nanoparticles consist of uniform spherical nanoparticles with an average diameter of 25 nm. The drug delivery system demonstrates the ability to release DOX by cleavage of the hydrazone bond in mildly acidic environments. The spectra overlap between emission of donor NaYF(4):Yb(3+)/Tm(3+) nanoparticles at 452 nm ((1)D(2)→(3)F(4)) and 477 nm ((1)G(4)→(3)H(6)) and the broad absorbance of acceptor DOX centered at around 480 nm enables energy transfer to occur between the nanoparticles and DOX. The quenching and recovery of the up-conversion luminescence of NaYF(4):Yb(3+)/Tm(3+) by DOX due to luminescence resonance energy transfer (LRET) mechanism are applied as optical probe to confirm the DOX conjunction and monitor the release of DOX. The DOX-conjugated NaYF(4):Yb(3+)/Tm(3+) nanoparticles exhibit an obvious cytotoxic effect on SKOV3 ovarian cancer cells via MTT assay. Meanwhile, the endocytosis process of DOX-conjugated NaYF(4):Yb(3+)/Tm(3+) nanoparticles by SKVO3 cells was demonstrated through confocal laser scanning microscopy (CLSM), flow cytometry and ICP-OES. Such drug delivery system, which combines pH-triggered drug-release and up-converting nanoparticles-based LRET property, has excellent potential applications in cancer therapy and smart imaging.

Application of prospective ECG-triggered dual-source CT coronary angiography for infants and children with coronary artery aneurysms due to Kawasaki disease

OBJECTIVES

The aim of this study was to prospectively evaluate the initial application and value of prospective electrocardiogram (ECG)-triggered dual-source CT coronary angiography (DSCTCA) in the diagnosis of infants and children with coronary artery aneurysms due to Kawasaki disease.

METHODS

19 children [12 males; mean age 13.47 months, range 3 months to 5 years; mean heart rate 112 beats per minute (bpm), range 83-141 bpm] underwent prospective ECG-triggered DSCTCA with free breathing. Subjective image quality was assessed on a five-point scale (1, excellent; 5, non-diagnostic) by two blinded observers. The location, number and size of each aneurysm were observed and compared with those of transthoracic echocardiography (TTE) performed within 1 week. Interobserver agreement concerning the subjective image quality was evaluated with Cohen's κ-test. Bland-Altman analysis was used to evaluate the agreement on measurements (diameter and length of aneurysms) between DSCTCA and TTE. The average effective dose required for DSCTCA was calculated for all children.

RESULTS

All interobserver agreement for subjective image quality assessment was excellent (κ=0.87). The mean ± standard deviation (SD) aneurysm diameter with DSCTCA was 0.76 ± 0.36 cm and with TTE was 0.76 ± 0.39 cm. The mean ± SD aneurysm length with DSCTCA was 2.06 ± 1.35 cm and with TTE was 2.00 ± 1.22 cm. The Bland-Altman plot for agreement between DSCTCA and TTE measurements showed good agreement. The mean effective dose was 0.36 ± 0.06 mSv.

CONCLUSION

As an alternative diagnostic modality, prospective ECG-triggered DSCTCA with excellent image quality and low radiation exposure has been proved useful for diagnosing infants and children with coronary artery aneurysms due to Kawasaki disease.

ADVANCES IN KNOWLEDGE

Prospective ECG-triggered DSCTCA for infants and children allows rapid, accurate assessment of coronary aneurysms due to Kawasaki diseases, compared with TTE.

Influence of oxytetracycline on carprofen pharmacodynamics and pharmacokinetics in calves

A tissue cage model of inflammation in calves was used to determine the pharmacokinetic and pharmacodynamic properties of individual carprofen enantiomers, following the administration of the racemate. RS(±) carprofen was administered subcutaneously both alone and in combination with intramuscularly administered oxytetracycline in a four-period crossover study. Oxytetracycline did not influence the pharmacokinetics of R(-) and S(+) carprofen enantiomers, except for a lower maximum concentration (Cmax ) of S(+) carprofen in serum after co-administration with oxytetracycline. S(+) enantiomer means for area under the serum concentration-time curve (AUC0-96 h were 136.9 and 128.3 μg·h/mL and means for the terminal half-life (T(1/2) k10 ) were = 12.9 and 17.3 h for carprofen alone and in combination with oxytetracycline, respectively. S(+) carprofen AUC0-96 h in both carprofen treatments and T(1/2) k10 for carprofen alone were lower (P < 0.05) than R(-) carprofen values, indicating a small degree of enantioselectivity in the disposition of the enantiomers. Carprofen inhibition of serum thromboxane B2 ex vivo was small and significant only at a few sampling times, whereas in vivo exudate prostaglandin (PG)E2 synthesis inhibition was greater and achieved overall significance between 36 and 72 h (P < 0.05). Inhibition of PGE2 correlated with mean time to achieve maximum concentrations in exudate of 54 and 42 h for both carprofen treatments for R(-) and S(+) enantiomers, respectively. Carprofen reduction of zymosan-induced intradermal swelling was not statistically significant. These data provide a basis for the rational use of carprofen with oxytetracycline in calves and indicate that no alteration to carprofen dosage is required when the drugs are co-administered.

Room temperature synthesis of hydrophilic Ln(3+)-doped KGdF4 (Ln = Ce, Eu, Tb, Dy) nanoparticles with controllable size: energy transfer, size-dependent and color-tunable luminescence properties

In this paper, we demonstrate a simple, template-free, reproducible and one-step synthesis of hydrophilic KGdF(4): Ln(3+) (Ln = Ce, Eu, Tb and Dy) nanoparticles (NPs) via a solution-based route at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and cathodoluminescence (CL) spectra are used to characterize the samples. The results indicate that the use of water-diethyleneglycol (DEG) solvent mixture as the reaction medium not only allows facile particle size control but also endows the as-prepared samples with good water-solubility. In particular, the mean size of NPs is monotonously reduced with the increase of DEG content, from 215 to 40 nm. The luminescence intensity and absolute quantum yields for KGdF(4): Ce(3+), Tb(3+) NPs increase remarkably with particle sizes ranging from 40 to 215 nm. Additionally, we systematically investigate the magnetic and luminescence properties of KGdF(4): Ln(3+) (Ln = Ce, Eu, Tb and Dy) NPs. They display paramagnetic and superparamagnetic properties with mass magnetic susceptibility values of 1.03 × 10(-4) emu g(-1)·Oe and 3.09 × 10(-3) emu g(-1)·Oe at 300 K and 2 K, respectively, and multicolor emissions due to the energy transfer (ET) process Ce(3+)→ Gd(3+)→ (Gd(3+))(n)→ Ln(3+), in which Gd(3+) ions play an intermediate role in this process. Representatively, it is shown that the energy transfer from Ce(3+) to Tb(3+) occurs mainly via the dipole-quadrupole interaction by comparison of the theoretical calculation and experimental results. This kind of magnetic/luminescent dual-function materials may have promising applications in multiple biolabels and MR imaging.

Bioequivalence in dogs of a meloxicam formulation administered as a transmucosal oral mist with an orally administered pioneer suspension product

A mucosal mist formulation of meloxicam, administered as a spray into the mouth (test article), was compared for bioequivalence to a pioneer meloxicam suspension for oral administration (reference article). Pharmacokinetic profiles and average bioequivalence were investigated in 20 dogs. The study design comprised a two-period, two-sequence, two-treatment cross-over design, with maximum concentration (C(max)) and area under plasma concentration-time curve to last sampling time (AUC(last)) used as pivotal bioequivalence variables. Bioequivalence of the products was confirmed, based on relative ratios of geometric mean concentrations (and 90% confidence intervals within the range 0.80-1.25) for C(max) of 101.9 (97.99-106.0) and for AUC(last) of 97.24 (94.44-100.1). The initial absorption of meloxicam was more rapid for the test article, despite virtually identical C(max) values for the two products. Mean elimination half-lives were 29.6 h (test article) and 30.0 h (reference article). The meloxicam plasma concentration-time profiles were considered in relation to published data on the inhibition of the cyclooxygenase-1 (COX-1) and COX-2 isoenzymes by meloxicam.

Up-conversion cell imaging and pH-induced thermally controlled drug release from NaYF4/Yb3+/Er3+@hydrogel core-shell hybrid microspheres

In this study, we report a new controlled release system based on up-conversion luminescent microspheres of NaYF(4):Yb(3+)/Er(3+) coated with the smart hydrogel poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAM-co-MAA)) (prepared using 5 mol % of MAA) shell. The hybrid microspheres show bright up-conversion fluorescence under 980 nm laser excitation, and turbidity measurements show that the low critical solution temperature of the polymer shell is thermo- and pH-dependent. We have exploited the hybrid microspheres as carriers for Doxorubicin hydrochloride (DOX) due to its stimuli-responsive property as well as good biocompatibility via MTT assay. It is found that the drug release behavior is pH-triggered thermally sensitive. Changing the pH to mildly acidic condition at physiological temperature deforms the structure of the shell, causing the release of a large number of DOX from the microspheres. The drug-loaded microspheres exhibit an obvious cytotoxic effect on SKOV3 ovarian cancer cells. The endocytosis process of drug-loaded microspheres is observed using confocal laser scanning microscopy and up-conversion luminescence microscopy. Meanwhile, the as-prepared NaYF(4):Yb(3+)/Er(3+)@SiO(2)@P(NIPAM-co-MAA) microspheres can be used as a luminescent probe for cell imaging. In addition, the extent of drug release can be monitored by the change of up-conversion emission intensity. These pH-induced thermally controlled drug release systems have potential to be used for in vivo bioimaging and cancer therapy by the pH of the microenvironment changing from 7.4 (normal physiological environment) to acidic microenvironments (such as endosome and lysosome compartments) owing to endocytosis.

Pathogenic role of mast cells in the development of diabetic nephropathy: a study of patients at different stages of the disease

AIMS/HYPOTHESIS

Increased renal mast cells have been detected in diabetic nephropathy. However, only a few patients have been examined. Evidence of the involvement of mast cells in diabetic nephropathy is still scarce, and no observation of mast cells during the development of diabetic nephropathy has yet been reported in humans. Here, we examined changes in renal mast cells in patients at different stages of diabetic nephropathy and related these to the development of the disease.

METHODS

Eighty patients at different clinical stages of diabetic nephropathy and 16 normal kidney donors were recruited. Immunohistochemical staining for tryptase, chymase, TGF-β1, renin and TNF-α was done on renal sections from patients and control participants. Changes in mast cell number, degranulation, subtype and phenotype were examined. Correlation between mast cells and patients' clinical and pathological indices was analysed.

RESULTS

With progression of diabetic nephropathy, the number and degranulation level of mast cells increased. Increase in mast cell number and degranulation level correlated significantly with tubular interstitial injury. Almost all renal mast cells in patients with diabetic nephropathy were found to produce chymase, renin, TGF-β1 and TNF-α. The level of TNF-α in mast cells increased with progression of diabetic nephropathy.

CONCLUSIONS/INTERPRETATION

This study suggests that mast cells are involved in development of diabetic nephropathy. Through release of bioactive substances, such as tryptase, chymase, TGF-β1, renin and TNF-α, into the tubular interstitium by degranulation, mast cells could promote renal inflammation and fibrosis, and thus contribute to diabetic nephropathy.

Magnetic Fe3O4@mesoporous silica composites for drug delivery and bioadsorption

Magnetic Fe(3)O(4)@mesoporous silica (MS) composites were synthesized by generating Fe(3)O(4) nanoparticles in the mesoporous silica matrix using the sol-gel method in nitrogen atmosphere. The mesoporous silica hosts include SBA-15 particles owning highly ordered p6mm mesostructure, siliceous mesostructured cellular foams (MCFs), and fiber-like mesoporous silica (FMS) with unique pore structures. The X-ray diffraction (XRD), transmission electron microscopy (TEM), and N(2) adsorption/desorption results show that Fe(3)O(4) functionalized MCFs and FMS possess suitable mesoporous structure for the adsorption of both small-molecular drug and large biomolecules. The biocompatibility tests on L929 fibroblast cells using MTT assay reveal low cytotoxicity of these systems. These Fe(3)O(4)@mesoporous silica composites show sustained release properties for aspirin in vitro. The release of the aspirin molecules from the pores of the Fe(3)O(4)@mesoporous silica composites is basically a diffusive process. Fe(3)O(4)@MCFs and Fe(3)O(4)@FMS owning larger pore size are good candidates for the adsorption of bovine serum albumin (BSA). These magnetic composites can be potential vectors for drug delivery and bioadsorption.

Reproductive performance and survival of Chinese Holstein dairy cows in central China

Fertility and longevity, major factors affecting the economic performance of dairy herds, are influenced by management and genetics. This study determined the reproductive performance and survival of Chinese Holstein cows in a large, modern dairy farm in central China using two complementary datasets. In Dataset 1, fertility and culling records were obtained from 1430 cows calving in 2008; in Dataset 2, all calving episodes during 2005 and 2006 were recorded (n = 1540) and the subsequent survival and reasons for death or culling of all female calves born during this period were monitored. In Dataset 1, the mean ages at first breeding and first calving for heifers were 18.7 ± 2.6 and 29.3 ± 3.6 months, respectively. Cows (lactations 1–10) were first inseminated at 110 ± 49 days after calving (mean ± s.d.), conceived at 185 ± 103 days and required 2.3 ± 1.6 services per conception with a first service conception rate of 34%. Reproduction performance was lower in the first lactation, with the best fertility in autumn-calving cows. In Dataset 2, 601 live-born heifers were monitored from birth until first calving. Of these, 521 (87%) were inseminated at least once and 502 (84%) calved once, but only 68% of the starting population calved successfully for a second time. The main reasons for culling in both datasets were poor fertility, disease and lameness. Improved management strategies to avoid calving cows in the spring and so offset the adverse effects of summer heat stress together with increased emphasis on selection for good fertility and conformation traits would increase future profitability.

Single-composition trichromatic white-emitting Ca4Y6(SiO4)6O: Ce3+/Mn2+/Tb3+ phosphor: luminescence and energy transfer

A series of Ca(4)Y(6)(SiO(4))(6)O (CYS): Ce(3+)/Mn(2+)/Tb(3+) oxyapatite phosphors were prepared via high-temperature solid-state reaction. Under UV excitation, there exist dual energy transfers (ET), i.e., Ce(3+)→Mn(2+) and Ce(3+)→Tb(3+) in the CYS: Ce(3+), Mn(2+), Tb(3+) system and their emitting colors can be adjusted from blue to orange-red via ET of Ce(3+)→Mn(2+) and from blue to green via ET of Ce(3+)→Tb(3+), respectively. Moreover, a wide-range-tunable white light emission with high quantum yields (13%-30%) were obtained by precisely controlling the contents of Ce(3+), Mn(2+) and Tb(3+) ions. On the other hand, the CL properties of CYS: Ce(3+), Mn(2+), Tb(3+) phosphors have been investigated in detail. The studied results indicate that the as-prepared CYS: Ce(3+), Mn(2+), Tb(3+) phosphors have good CL intensity and CIE color coordinate stability with a color-tunable emission crossing the whole white light region under low-voltage electron beam excitation. In general, the white light with varied hues has been obtained in Ce(3+), Mn(2+), and Tb(3+)-triactivated CYS phosphors by utilizing the principle of energy transfer and properly designed activator contents under UV (284, 358 nm) and low-voltage (1-5 kV) electron beam excitation, which make them as a potential single-composition trichromatic white-emitting phosphor.