Evaluation of mTHPC-loaded PLGA nanoparticles for in vitro photodynamic therapy on C6 glioma cell line

Photodynamic therapy (PDT) is a very attractive strategy to complement or replace common cancer treatments such as radiotherapy, surgery, and chemotherapy. Some molecules have shown their efficiency as photosensitizers (PS), still many issues have to be solved such as the inherent cytotoxicity of the PS or its hydrophobic properties causing limitation in their solubility, leading to side effects. In this study, the encapsulation of an approved PS, the meso-tetra hydroxyphenylchlorine (mTHPC, Foscan®) within biocompatible and biodegradable poly(D, l-lactide-co-glycolide) acid (PLGA) NPs prepared by the nanoprecipitation method was studied. The mTHPC-loaded NPs (mTHPC ⊂ PLGA NPs) were analyzed by UV-vis spectroscopy to determine the efficiency of mTHPC encapsulation, and by dynamic light scattering (DLS) and atomic force microscopy (AFM) to determine mTHPC ⊂ PLGA NPs sizes, morphologies and surface charges. The longitudinal follow-up of mTHPC release from the NPs indicated that 50% of the encapsulated PS was retained within the NP matrix after a period of five days. Finally, the cytotoxicity and the phototoxicity of the mTHPC ⊂ PLGA NPs were determined in murine C6 glioma cell lines and compared to the ones of mTHPC alone. The studies showed a strong decrease of mTHPC cytotoxicity and an increase of mTHPC photo-cytotoxicity when mTHPC was encapsulated. In order to have a better insight of the underlying cellular mechanisms that governed cell death after mTHPC ⊂ PLGA NPs incubation and irradiation, annexin V staining tests were performed. The results indicated that apoptosis was the main cell death mechanism.

Characterization of Gd loaded chitosan-TPP nanohydrogels by a multi-technique approach combining dynamic light scattering (DLS), asymetrical flow-field-flow-fractionation (AF4) and atomic force microscopy (AFM) and design of positive contrast agents for molecular resonance imaging (MRI)

Chitosan CS-tripolyphosphate TPP/hyaluronic acid HA nanohydrogels loaded with gadolinium chelates (GdDOTA ⊂ CS-TPP/HA NGs) synthesized by ionic gelation were designed for lymph node (LN) MRI. In order to be efficiently drained to LNs, nanogels (NGs) needed to exhibit a diameter ϕ < 100 nm. For that, formulation parameters were tuned, using (i) CS of two different molecular weights (51 and 37 kDa) and (ii) variable CS/TPP ratio (2 < CS/TPP < 8). Characterization of NG size distribution by dynamic light scattering (DLS) and asymetrical flow-field-flow-fractionation (AF4) showed discrepancies since DLS diameters were consistently above 200 nm while AF4 showed individual nano-objects with ϕ < 100 nm. Such a difference could be correlated to the presence of aggregates inherent to ionic gelation. This point was clarified by atomic force microscopy (AFM) in liquid mode which highlighted the main presence of individual nano-objects in nanosuspensions. Thus, combination of DLS, AF4 and AFM provided a more precise characterization of GdDOTA ⊂ CS-TPP/HA nanohydrogels which, in turn, allowed to select formulations leading to NGs of suitable mean sizes showing good MRI efficiency and negligible toxicity.

Quadriceps muscle fatigue in trained and untrained boys

This study aimed to explore muscle oxygen extraction and muscle activation pattern during bilateral intermittent submaximal isometric knee-extensions by combining Near-infrared Spectroscopy (NIRS) and Electromyography (EMG) measurements from the M. Vastus Lateralis. A group of highly specifically trained boys (youth sailors) (n=10) and untrained matched controls (n=10) performed 12 bouts of 90 s bilateral submaximal (30-40% MVC) isometric knee-extension interspersed with 6 s recovery-periods. Patterns of deoxygenated haemoglobin and myoglobin concentration (Deoxy[Hb+Mb]) were observed during each bout and the entire protocol. Reoxygenation Index (RI) was assessed for each recovery period as the amplitude of Deoxy[Hb+Mb]-decrease relative to amplitude of Deoxy[Hb+Mb]-increase during each bout. Root Mean Square (RMS) and Mean Power Frequency (MPF) were calculated for each bout as an average of the final 60 s. Deoxy[Hb+Mb], RI, RMS and MPF were analyzed by repeated-measures ANOVA. Results indicated significantly higher Deoxy[Hb+Mb]-increase and lower RI in specifically trained boys compared to untrained controls. These differences are presumably related to the differences in EMG-measurements which demonstrated lower RMS-increase and MPF-decrease for trained compared to untrained boys. In conclusion, specifically trained boys indicate delayed onset of muscle fatigue in comparison to untrained controls, which might be associated with the different pattern of muscle O2-extraction or muscle activation pattern (i. e., a more accurate recruitment of slow-twitch fibres).

Adsorption of poly(N-isopropylacrylamide) on glass substrata

The adsorption of poly(N-isopropylacrylamide) (PNIPAAM), a well known thermosensitive polymer, on glass was investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The polymer was dissolved in water at low (0.02 g/L) and high (2 g/L) concentration and the tested temperatures were below (25 degrees C) and above (50 degrees C) the lower critical solubility temperature (LCST). Whatever the conditions, a smooth layer of adsorbed molecules spread along the surface was observed. The thickness was about twice higher for high concentration compared to low concentration. The cohesion in the adsorbed layer, as revealed by scraping tests performed by AFM, was higher above the LCST than below the LCST. On top of this adsorbed layer, single-chain coils, globules, or aggregates were present, depending on concentration and temperature. The observation of these additional adsorbed entities was poorly reproducible, presumably due to the lack of shear control upon rinsing. These results emphasize the importance of the characterization of surface morphology to interpret amounts of adsorbed polymers.

Serum inhibin B in normal term-born male and female neonates during the first week of life

Inhibin B, a gonadal peptide regulating follicle stimulating hormone (FSH) secretion in adults, has been found during gestation in amniotic fluid, but at birth only in term cord blood of male babies. Since no data are available on the evolution of serum inhibin B during the 1st week of life, we studied changes in inhibin B using a specific and sensitive immunoassay in male and female neonates during the 1st week of life in relation to FSH and to evaluate the possible effect of perinatal factors on inhibin B production. Inhibin B was measured by a specific monoclonal enzyme-linked immunosorbent assay. Inhibin B was detectable in cord blood of all eight longitudinally studied male newborns, correlated negatively with the ponderal index and increased significantly on day 5 (from 54.2 +/- 18.5 to 100.4 +/- 34.8 ng/l, P < 0.005). Cord blood inhibin B was detected in only 1 out of 13 screened female neonates. In 48 at term-born females in whom inhibin B was measured on the 5th day of life, only 20 cases had a detectable level (between 8 and 68.6 ng/l). Inhibin B concentrations in cord blood and on day 5 were independent of duration of pregnancy, type of delivery, Apgar score and FSH concentration.

CONCLUSION

A sexual difference in serum inhibin B is already present at the end of gestation and changes in inhibin B during the 1st week of life are independent of follicle stimulating hormone changes and perinatal factors in both sexes. Our data suggest that neonatal inhibin B could be used to study whether the newborn has functional testes, i.e. in babies with ambiguous genitalia and/or bilateral cryptorchidism.

Four radioisotopic immunoassays of free thyroxine compared

The analytical and clinical performance of three radioisotopic methods for the measurement of free thyroxine-Gamma Coat (125I) Free T4, RIA-gnost FT4 and Amerlex-MAB* FT4-were assessed in comparison with the Scalvo two-step chromatographic method. The analytical evaluation indicated excellent performance of Amerlex-MAB FT4. For the other methods, precision and sensitivity were comparable and acceptable for routine use. Only Gamma Coat FT4 showed a significant positive intra-assay drift. None of the methods showed a significant correlation with thyroxine-binding globulin. Amerlex-MAB FT4 results were weakly positively correlated with albumin. Sclavo, RIA-gnost and particularly GammaCoat FT4 results were affected by the presence of increased concentrations of free fatty acids. All methods classified hyperthyroid patients correctly. Slight overlaps existed between the hypothyroid and euthyroid populations. Significant decreases in free thyroxine (FT4) during the third trimester of pregnancy were detected by all assays. In patients with chronic renal failure, serum FT4 was within reference limits more often when measured by Sclavo or Amerlex-MAB methods than by RIA-gnost or GammaCoat techniques. In conclusion, all assays performed well from both technical and diagnostic points of view.