Wideband infrared trap detector based upon doped silicon photocurrent devices

We have designed, fabricated, and measured infrared trap detectors made from arsenic-doped silicon (Si:As) blocked impurity band (BIB) photodetectors. These trap detectors are composed of two detectors in a wedge geometry, with an entrance aperture diameter of either 1 or 3 mm. The detectors were calibrated for quantum efficiency against a pyroelectric reference detector using a Fourier transform spectral comparator system, and etalon effects and spatial uniformity of the traps were also quantified. Measurements of the traps at a temperature of 10 K show that nearly ideal external quantum efficiency (>90%) can be attained over much of the range from 4 to 24 μm, with significant responsivity from 2 to 30 μm. The traps exhibited maximum etalon oscillations of only 2%, which is about 10 times smaller amplitude than those of the single Si:As BIB detectors measured under similar conditions. Spatial nonuniformity across the entrance apertures of the traps was about 1%. The combination of high detectivity, wideband wavelength coverage, spectral flatness, and spatial uniformity make these trap detectors an excellent reference detector for spectrally resolved measurements and radiometric calibrations over the near- to far-infrared wavelength range.

GSK-J4 a potent and selective inhibitor of the H3K27 demethylase JMJD3/UTX limits acute colitis by de novo synthesis Retinoic Acid in dendritic cells

JMJD3 a demethylase of lysine 27 of histone H3 (H3K27) plays an important role in immune cells and inflammatory responses, and thus appears as an attractive target for the treatment of inflammatory diseases. Recently, GSK-J4, a selective and potent JMJD3 inhibitor was synthesized. We previously showed that GSK-J4 induced a tolerogenic phenotype on dendritic cells (DCs) promoting the generation and stability of induced Tregs as well as enhancing their suppressive function. However, the underlying mechanisms remain unclear.

Because GSK-J4 acts upon DCs, we evaluated RA synthesis as underlying pro-tolerogenic mechanisms affected by this drug.

Here we report that GSK-J4 treatment promoted RALDH activity on DCs and induced the expression of RALDH1 and RALDH3 enzymes in DCs, resulting in an increase in the expression of Foxp3, CCR9 and α4β7 in CD4+ T cells.

The increased RALDH1 and RALDH3 expression correlated with changes on the ratio of repressive (H3K27me3) versus active marks (H3K4me3) on RALDH1 and RALDH3 promoters in GSK-J4-treated DCs. Moreover, we demonstrated that systemic administration of GSK-J4 ameliorates the severity of DSS-induced acute colitis in mice.

Collectively this study demonstrates that GSK-J4 attenuates DSS-induced acute colitis, an effect that may be attributed to the de novo RA synthesis on DCs.

This drug may be a promising approach for the treatment of inflammatory diseases.

Purinergic Signaling as a Regulator of Th17 Cell Plasticity

T helper type 17 (Th17) lymphocytes, characterized by the production of interleukin-17 and other pro-inflammatory cytokines, are present in intestinal lamina propria and have been described as important players driving intestinal inflammation. Recent evidence, supporting the notion of a functional and phenotypic instability of Th17 cells, has shown that Th17 differentiate into type 1 regulatory (Tr1) T cells during the resolution of intestinal inflammation. Moreover, it has been suggested that the expression of CD39 ectonucleotidase endows Th17 cells with immunosuppressive properties. However, the exact role of CD39 ectonucleotidase in Th17 cells has not been studied in the context of intestinal inflammation. Here we show that Th17 cells expressing CD39 ectonucleotidase can hydrolyze ATP and survive to ATP-induced cell death. Moreover, in vitro-generated Th17 cells expressing the CD39 ectonucleotidase produce IL-10 and are less pathogenic than CD39 negative Th17 cells in a model of experimental colitis in Rag-/- mice. Remarkably, we show that CD39 activity regulates the conversion of Th17 cells to IL-10-producing cells in vitro, which is abrogated in the presence of ATP and the CD39-specific inhibitor ARL67156. All these data suggest that CD39 expression by Th17 cells allows the depletion of ATP and is crucial for IL-10 production and survival during the resolution of intestinal inflammation.

Determination of Cd and Pb at microg/L levels by HHPN-beam injection flame furnace-AAS

Flame-heated tubes are widespread in flame-AAS, mainly for the determination of hydride-forming elements. Instead of the introduction of gaseous compounds liquids can also be introduced continuously in such an absorption cell. With the aid of an HPLC pump the liquid is forced through a very fine nozzle, generating an aerosol beam less than 0.5 mm in diameter. This beam travels a distance of 10cm as a "free-flying aerosol jet" into the sample introduction hole of a metal tube furnace placed in the flame. Both introduction of the entire sample and the long residence time lead to a considerable improvement in power of detection. The detection limit for 100 microL samples amounts to 7 microg/L (Pb) and to 0.2 microg/L (Cd), which means an increase in power of detection of between one and two orders of magnitude compared to conventional flame-AAS. The relative standard deviation (100 microL sample volume, N = 10) was found to be 1.3% (signal area) for 600 microg/L Pb and to be 1.5% (signal-area) for 15 microg/L Cd. RSD values from measurements in peak-height amounted to 2.2% (Pb) and to 1.7% (Cd).

[Congenital defects of antithrombin III and proteins C and S during pregnancy]

We report 10 patients with congenital deficiencies of the natural anticoagulant proteins S, C and antithrombin III. Thirteen of a total of 30 pregnancies were managed at the perinatal branch of our department. We discuss the mechanism of action of these proteins and their role in thrombotic events. We analyze the most frequent thrombotic complications and we discuss the general guidelines for the investigation of a patient with a suspected congenital thrombophilia with special regard to its management during pregnancy, delivery and perinatal outcome.

[Seroepidemiological investigation of various tissue helminthiasis, by means of indirect hemagglutination test, in Lonquimay County, Chile]

In order to have a present perspective on the prevalence on the epidemiology of some tissue helminthiasis in Lonquimay County, southern Chile, in 1993 a seroepidemiological survey, by means of an indirect hemagglutination test (IHAT) for hydatidosis, cysticercosis and trichinosis was undertaken. In 11 (1.2%), 10 (1.1%) and 6 (0.6%) out of 945 examined persons, most of them from rural areas, the corresponding IHAT resulted positive. Additionally, radiographic and ecotomographical studies for thorax and abdomen respectively were performed to the 11 individuals with serology positive for hydatidosis: whereas all the thoracic radiographies resulted negative, liver hydatic cysts were detected in five persons, who latter on were submitted to surgery. Prevalence rates of hydatidosis in Lonquimay are among the highest regional and national values.

Post-partum cervical mucus: biological and rheological properties

In this study we have evaluated the score, sperm migration and ultrastructural characteristics of cervical mucus present in amenorrhoeic women under exclusive breastfeeding at 30, 60, 90, 120, 150 and 180 days post-partum. Periovulatory mucus samples from seven normally cycling women were used as a control. The average scores of post-partum and periovulatory mucus were 4.6 +/- 0.4 and 14.1 +/- 0.5 respectively. Twenty-one (39%) of the 54 post-partum cervical mucus samples and all (100%) periovulatory mucus samples allowed sperm migration. Positive sperm migration into post-partum mucus was observed at all time intervals studied. The only parameter that correlated with sperm migration into post-partum mucus was ferning formation. Sperm migration was obtained in all post-partum mucus samples with a score greater than 8, but samples with scores between 2 and 7 also showed sperm penetration. Scanning electron microscopic studies showed the characteristic spongy appearance of periovulatory mucus. Post-partum mucus was formed by a dense mesh (rocky appearance), when samples were generally unable to sustain sperm migration, but samples where sperm migration occurred showed small areas of spongy mucus mixed with areas in which a dense mesh and high cellularity was observed.

Evaluation of secretory IgA childhood respiratory diseases

Secretory IgA salivary concentration was studied, in order to investigate its influence as a possible causative role in groups of children affected by different respiratory diseases. Allergic bronchial asthma (n = 37), recurrent pneumonias (n = 11), recurrent upper airway infectious (n = 12) and a control group of healthy children (n = 25) were included. The sIgA mean concentration plus S.D. were: 26.0 +/- 11.5, 15.5 +/- 16.7, 21.2 +/- 15.6, 16.2 +/- 12.7 and 30.8 +/- 10.1, respectively. A statistically significant association between decreased or absent levels of sIgA and disease was found, but no correlation between alterations in sIgA concentrations and any class of serum immunoglobulin levels, or with any other analyzed variables could be established. Among the group of diseases studied, a statistically significant difference (p less than 0.01) was found between infectious asthma and controls, recurrent upper airway infections and controls, and between allergic and infectious asthma. These findings support the conclusion that a decrease or absence of sIgA is an important factor to be considered in infectious asthma, as well as in recurrent upper airway infectious diseases affecting children.