1,169 research outputs found
Pulse shape discrimination performance of Inverted Coaxial Ge detectors
We report on the characterization of two inverted coaxial Ge detectors in the
context of being employed in future Ge neutrinoless double beta
() decay experiments. It is an advantage that such detectors
can be produced with bigger Ge mass as compared to the planar Broad Energy Ge
detectors (BEGe) that are currently used in the GERDA decay
experiment. This will result in lower background for the search of
decay due to a reduction of cables, electronics and holders.
The measured resolution near the Ge Q-value at 2039 keV is 2.5 keV and
their pulse-shape characteristics are similar to BEGe-detectors. It is
concluded that this type of Ge-detector is suitable for usage in Ge
decay experiments
Flow cytometric evaluation of red blood cells transformed with variable amounts of synthetic A and B glycolipids
Background: According to national guidelines or directives, monoclonal
ABO reagents may be required to detect Ax and B weak subgroup red blood
cells (RBCs). Many routine laboratories do not have access to naturallyoccurring
ABO subgroups that can be used as weak controls for these
reagents. Group O RBCs modified with synthetic analogs of blood group A
and/or B glycolipids (KODE technology) to mimic weak ABO subgroups
could be used for quality control purposes.
Aim: Extensive serological testing of KODE RBCs has previously been
performed. An extended evaluation of KODE RBCs using flow cytometry
was performed to explore the correlation between the concentrations of
synthetic glycolipids and A/B site density of the resulting RBCs. The aim of
this study was to examine if KODE RBCs mimic the distinct flow cytometric
patterns of naturally-occurring ABO subgroups.
Material and Methods: KODE RBCs were prepared according to a previously
decribed procedure [Frame et al., Transfusion 2007; 47: 876–82].
RBCs were modified with 15 different concentrations of synthetic glycolipids,
ranging from 1 mg/mL to 60 ng/mL for KODE-A and 5 mg/mL to
0.3 lg/mL for KODE-B. The concentration was decreased by doubling
dilution steps. Sensitive and specific flow cytometry [Hult & Olsson.
Transfusion 2006; 9S: 32A] was used to characterize and semiquantify the
synthetic A and B antigen levels on RBCs. Relevant control RBCs (A1, A2,
Ax, B, Bweak and O) were included in each run. For both KODE-A and KODE-B RBCs, repeat samples were produced for four selected concentrations
and all KODE batches were tested in triplicate.
Results: Flow cytometric testing of KODE RBCs modified with high
concentrations of synthetic glycolipids revealed a uniform and even
distribution of antigens in the cell population as shown by a single
narrow peak in the FACS histograms. When lower concentrations were
used, peaks tended to broaden to a pattern found in Ax and most B
subgroups indicating a more variable antigen site density on the cells in
the population. The concentrations of synthetic glycolipids that produced
KODE cells that resembled the naturally-occurring subgroup control RBCs
used in this study are ~2–4 lg/mL for KODE-A and ~10 lg/mL for KODEB.
Repeat testing demonstrated good correlation between flow cytometric
runs.
Discussion and Conclusion: Using very low amounts of synthetic
glycolipids, KODE-A and KODE-B RBCs can be made to mimic Ax and
Bweak subgroup control RBCs, respectively, according to this flow
cytometry method. With higher concentrations of synthetic glycolipids, the
KODE RBCs demonstrated a more uniform and even distribution of antigens
among the cells. This is in contrast to naturally-occurring subgroups
in which some cells express almost no A or B antigen whilst others have
close to normal levels. The reason for this is unknown. KODE RBCs obviously
lack A carrying glycoproteins but it is not fully understood to what
extent glycolipid versus glycoprotein epitopes contribute to the phenotype
of weak subgroups.
This study indicates that KODE RBCs with weak expression of A and/or B
antigen have characteristics compatible with use as quality controls for
monoclonal ABO reagents and could be a valuable addition in the
serological laboratory
Tremorogeni učinci ekstrakata plijesni izoliranih iz prašine drveta u štakora
Among workers in the Swedish wood industry acute alveolitis, known as “woodtrimmer\u27s disease” has been recognized for some time. One of the signs in the acute phase of the disease is transitory tremor. The etiology of the disease is still not clearly understood, but it is assumed to be associated with wood dust containing fungal spores. One of the dominant fungal strains isolated from wood at the saw-mills was found to be Aspergillus fumigatus. As it is known that Aspergillus fumigatus has the ability to produce tremorgenic mycotoxins, the moulds from the working environment were isolated, cultivated and tested for the ability to produce mycotoxins, to estimate a possible relation between fungal spores and tremorgenic effects. Extracts of moulds were prepared and tested on rats after oral administration. The ability to induce tremors in rats was found in six out of nine extracts tested. A very good agreement was found between the results of the chemical analysis of extracts and those of the study in vivo. The results imply that woodtrimmer\u27s disease may at least partly, be mycotoxicosis.U Švedskoj, u radnika zaposlenih u drvnoj industriji, javlja se akutni alveolitis poznat i pod nazivom Woodtrimmer\u27s disease, popraćen prolaznim tremorom. Pojava je nepoznate etiologije ali se povezuje s izloženošću drvenoj prašini u kojoj se nalaze spore različitih plijesni. Aspergillus fumigatus je plijesan koja se najčešće izolira u sušarama drveta. Iz radne sredine izolirane su plijesni Aspergillus flavusa te je nakon kultivacije testirana njihova sposobnost stvaranja tremorogenih mikotoksina analitičkim metodama i u pokusima na štakorima. Ekstrakti plijesni aplicirani su pokusnim životinjama oralno.
Šest od devet ekstrakata izazvalo je pojavu tremora u tretiranih životinja. Nađena je vrlo dobra korelacija rezultata kemijskih analiza i rezultata dobivenih u pokusima in vivo. Podaci upućuju na moguću vezu između Woodtrimmer\u27s disease i izloženosti radnika tremorogenim mikotoksinima
A and B antigen levels acquired by group O donor-derived erythrocytes following ABO-non-identical transfusion or minor ABO-incompatible haematopoietic stem cell transplantation
BACKGROUND AND OBJECTIVES: ABO-incompatible haematopoietic stem cell transplantation (HSCT) presents a challenge to blood component transfusion. The aim of this study was to investigate the weak blood group A or B antigen expression by donor-derived group O red blood cells (RBC) observed following transfusion or minor ABO-incompatible HSCT. In addition, in vitro experiments were performed to elucidate possible mechanisms underlying this phenomenon.MATERIALS AND METHODS: A sensitive flow cytometry assay for the semi-quantification of RBC A/B antigen levels was used to assess patient samples and evaluate in vitro experiments.RESULTS: Analysis of blood samples from patients, originally typed as A, B and AB but recently transplanted or transfused with cells from group O donors, revealed the A antigen expression on donor-derived RBC, ranging from very low levels in non-secretor individuals to almost subgroup Ax -like profiles in group A secretors. The B antigen expression was less readily detectable. In vitro experiments, in which group O donor RBC were incubated with (i) group A/B secretor/non-secretor donor plasma or (ii) group A/B donor RBC in the absence of plasma, supported the proposed adsorption of A/B antigen-bearing glycolipids from secretor plasma but also indicated a secretor-independent mechanism for A/B antigen acquisition as well as direct cell-to-cell transfer of ABO antigens.CONCLUSION: The in vivo conversion of donor-derived blood group O RBC to ABO subgroup-like RBC after transfusion or minor ABO-incompatible HSCT raises the question of appropriate component selection. Based on these data, AB plasma should be transfused following ABO-incompatible HSCT
A calibration method for broad-bandwidth cavity enhanced absorption spectroscopy performed with supercontinuum radiation
An efficient calibration method has been developed for broad-bandwidth cavity enhanced absorption spectroscopy. The calibration is performed using phase shift cavity ring-down spectroscopy, which is conveniently implemented through use of an acousto-optic tunable filter (AOTF). The AOTF permits a narrowband portion of the SC spectrum to be scanned over the full high-reflectivity bandwidth of the cavity mirrors. After calibration the AOTF is switched off and broad-bandwidth CEAS can be performed with the same light source without any loss of alignment to the set-up. We demonstrate the merits of the method by probing transitions of oxygen molecules O-2 and collisional pairs of oxygen molecules (O-2)(2) in the visible spectral range
Dicarboxylic esters : useful tools for the biocatalyzed synthesis of hybrid compounds and polymers
Dicarboxylic acids and their derivatives (esters and anhydrides) have been used as acylating agents in lipase-catalyzed reactions in organic solvents. The synthetic outcomes have been dimeric or hybrid derivatives of bioactive natural compounds as well as functionalized polyesters
Unified Treatment of Asymptotic van der Waals Forces
In a framework for long-range density-functional theory we present a unified
full-field treatment of the asymptotic van der Waals interaction for atoms,
molecules, surfaces, and other objects. The only input needed consists of the
electron densities of the interacting fragments and the static polarizability
or the static image plane, which can be easily evaluated in a ground-state
density-functional calculation for each fragment. Results for separated atoms,
molecules, and for atoms/molecules outside surfaces are in agreement with those
of other, more elaborate, calculations.Comment: 6 pages, 5 figure
Mode-hop-free tuning over 135 GHz of external cavity diode lasers without anti-reflection coating
We report an external cavity diode laser (ECDL), using a diode whose front
facet is not antireflection (AR) coated, that has a mode-hop-free (MHF) tuning
range greater than 135 GHz. We achieved this using a short external cavity and
by simultaneously tuning the internal and external modes of the laser. We find
that the precise location of the pivot point of the grating in our laser is
less critical than commonly believed. The general applicability of the method,
combined with the compact portable mechanical and electronic design, makes it
well suited for both research and industrial applications.Comment: 5 pages, 5 figure
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