447 research outputs found
Impaired Intracellular Transport and Cell Surface Expression of Nonpolymorphic HLA-E
The assembly of the classical, polymorphic major histocompatibility complex class I molecules
in the endoplasmic reticulum requires the presence of peptide ligands and ~2-microglobulin
(~2m). Formation of this trimolecular complex is a prerequisite for e~cient transport to the
cell surface, where presented peptides are scanned by T lymphocytes. The function of the other
class I molecules is in dispute. The human, nonclassical class I gene, HLA-E, was found to be
ubiquitously transcribed, whereas cell surface expression was dif~cult to detect upon transfection.
Pulse chase experiments revealed that the HLA-E heavy chain in transfectants, obtained with
the murine myeloma cell line P3X63-Ag8.653 (X63), displays a significant reduction in
oligosaccharide maturation and intracellular transport compared with HLA-B27 in corresponding
transfectants. The accordingly low HLA-E cell surface expression could be significantly enhanced
by either reducing the culture temperature or by supplementing the medium with human ~2m,
suggesting inefficient binding of endogenous peptides to HLA-E. To analyze whether HLA-E
binds peptides and to identify the corresponding ligands, fractions of acid-extracted material from
HLA-E/X63 transfectants were separated by reverse phase HPLC and were tested for their ability
to enhance HLA-E cell surface expression. Two fractions specifically increased the HLA class
I expression on the HLA-E transfectant clone
Long-term use of motion-based video games in care home settings
Recent research suggests that motion-based video games have the potential to provide both mental and physical stimulation for older adults in residential care. However, little research has explored the practical challenges and opportunities that arise from integrating these games within existing schedules of activities in these contexts. In our work, we report on a qualitative enquiry that was conducted over a three month period at two long-term care facilities. Findings suggest that older adults enjoyed playing video games, and that games can be a valuable means of re-introducing challenge in late life, but that the impact of age-related changes and impairment can influence people’s ability to engage with games in a group setting. We outline core challenges in the design for care context and discuss implications of our work regarding the suitability of games as a self-directed leisure activity
The HLA-E Gene encodes two differentially regulated Transcripts and a Cell Surface Protein
An HLA-E-specific oligonucleotide probe was used
to study the expressioonf HLA-E. This probed etects
two HLA-E transcripts, 1.8 and 2.7 kb in size, which
are present in varying ratios in allt issues and cell
lines investigated. We demonstrate that alternative
poly(A) site usage accounts for the differential regulation
of the two HLA-E mRNA species. Sequence
analysis of three cDNA clones, representing the two
transcripts of HLA-E, and of anH LA-E gene encoded
by cosmid cd3.14, revealed identity of gene and
cDNA in the 3’ untranslated region. S1 nuclease
protection assays confirmed that the two HLA-E
transcripts are not alternative splicing products.
Introduction of cd3.14, together with human ,&m
into the murine myeloma cell line P3X63-Ag8.653,
resulted in a cell surface expresosf ioan HLA-class
I heavy chain detectablbey indirect immunofluorescence
whereas transfection into the humBaznr n expressing
mouse L cell line, 527 was negative with
regard to cell surface expressionC. ell surface labeling
of transfectants and immunoprecipitation with
a monomorphic HLA class I-specific antibodyo r an
antibody against human &m confirmed the presence
of an HLA-E H chain on the cell surface. These
results indicate that the HLA-E gene codes for a
class I H chain that can be expressed on the cell
surface
HLA-G: expression in human keratinocytes in vitro and in human skin in vivo
Classical, polymorphic major histocompatibility complex class I molecules are
expressed on most nucleated cells.They present peptides at the cell surface and,
thus, enable the immune system to scan peptides for their antigenicity. The
function of the other, nonclassical class I molecules in man is controversial.
HLA-G which has been shown by transfection experiments to be expressed at the
cell surface, is only transcribed in placental tissue and in the fetal eye.Therefore, a
role of HLA-G in the control of rejection of the allogeneic fetus has been
discussed. We found that HLA-G expression is induced in keratinocytes by
culture in vitro. Three different alternative splicing products of HLA-G can be
detected: a full length transcript, an mRNA lacking exon 3 and a transcript devoid
of exon 3 and 4. Reverse transcription followed by polymerase chain reaction also
revealed the presence of HLA-G mRNA in vivo in biopsies of either diseased or
healthy skin
Rotational viscoelastic laminar boundary layer flow around a rotating disc
The equations of motion for the laminar boundary layer flow over a rotating disc have been derived for a fluid which obeys a Rivlin-Ericksen type of constitutive equation and whose material parameters are assumed to be arbitrary functions of the second invariant of the rate of deformation tensor. The analysis establishes the conditions under which a true similarity solution is possible. An inspectional analysis yields a relationship between the moment coefficient, a generalized Reynolds number and a modified Weissenberg number which incorporates a variable relaxation time with a process time characteristic of the boundary layer flow on the disc. Experimental data obtained are analysed in terms of the derived relationship and the agreement between the two, after the determination of the unknown constants, is found to be quite sound. A brief discussion follows which emphasizes the role of geometry, regime of flow and viscoelastic material parameters in giving a wide variety of flow phenomena
An approximate theoretical analysis and experimental verification of turbulent entrance region flow of drag reducing fluids
Entry lengths for pipe flows of moderately drag reducing fluids are determined using momentum integral technique. It is shown theoretically that the entry lengths for drag reducing fluids could be significantly larger than the Newtonian fluids flowing turbulently under otherwise identical conditions. The experimental data from the literature bear out the theoretical calculations
- …