The Experts below are selected from a list of 14034975 Experts worldwide ranked by ideXlab platform

Masroor Ikram - One of the best experts on this subject based on the ideXlab platform.

  • in vitro study of 5 aminolevulinic acid based photodynamic therapy for apoptosis in human cervical hela cell line
    Laser Physics Letters, 2009
    Co-Authors: Muhammad Atif, S. Firdous, Ahmat Khurshid, L. Noreen, Syed Sohail Zahoor Zaidi, Masroor Ikram
    Abstract:

    5-aminolevulanic acid (ALA), belonging among the promising second generation of sensitizers, was evaluated as an inducer of photodamage on HeLa (human cervical adenocarcinoma) cell line. A diode laser (635 nm) was used as a source for initiation of the photodynamic effect. We studied the influence of different incubation times, various concentrations of sensitizer, different irradiation doses and various combinations of sensitizer and light doses on the photodamage of HeLa cells. Viability of cells was determined by means of neutral red assay. The quantitative cellular uptake of ALA sensitizer was done by spectrophotometric measurements. No prominent cytotoxic or phototoxic effects on HeLa were observed due to sensitizer or light doses when studied independently of each other. However phototoxicity evoked by laser irradiated sensitizer was detected in HeLa cell line.

  • In vitro study of 5‐aminolevulinic acid‐based photodynamic therapy for apoptosis in human cervical HeLa cell line
    Laser Physics Letters, 2009
    Co-Authors: Muhammad Atif, S. Firdous, Ahmat Khurshid, L. Noreen, Syed Sohail Zahoor Zaidi, Masroor Ikram
    Abstract:

    5-aminolevulanic acid (ALA), belonging among the promising second generation of sensitizers, was evaluated as an inducer of photodamage on HeLa (human cervical adenocarcinoma) cell line. A diode laser (635 nm) was used as a source for initiation of the photodynamic effect. We studied the influence of different incubation times, various concentrations of sensitizer, different irradiation doses and various combinations of sensitizer and light doses on the photodamage of HeLa cells. Viability of cells was determined by means of neutral red assay. The quantitative cellular uptake of ALA sensitizer was done by spectrophotometric measurements. No prominent cytotoxic or phototoxic effects on HeLa were observed due to sensitizer or light doses when studied independently of each other. However phototoxicity evoked by laser irradiated sensitizer was detected in HeLa cell line.

Jacques Thibodeau - One of the best experts on this subject based on the ideXlab platform.

  • HLA-DO increases bacterial superantigen binding to human MHC molecules by inhibiting dissociation of class II-associated invariant chain peptides
    Human Immunology, 2013
    Co-Authors: Abdul Mohammad Pezeshki, Georges A. Azar, Walid Mourad, Mohamed Rachid Boulassel, Lisa K Denzin, Jean-pierre Routy, Jacques Thibodeau
    Abstract:

    Abstract HLA-DO (H2-O in mice) is an intracellular non-classical MHC class II molecule (MHCII). It forms a stable complex with HLA-DM (H2-M in mice) and shapes the MHC class II-associated peptide repertoire. Here, we tested the impact of HLA-DO and H2-O on the binding of superantigens (SAgs), which has been shown previously to be sensitive to the structural nature of the class II-bound peptides. We found that the binding of staphylococcal enterotoxin (SE) A and B, as well as toxic shock syndrome toxin 1 (TSST-1), was similar on the HLA-DO + human B cell lines 721.45 and its HLA-DO − counterpart. However, overexpressing HLA-DO in MHC class II + HeLa cells (HeLa-CIITA-DO) improved binding of SEA and TSST-1. Accordingly, knocking down HLA-DO expression using specific siRNAs decreased SEA and TSST-1 binding. We tested directly the impact of the class II-associated invariant chain peptide (CLIP), which dissociation from MHC class II molecules is inhibited by overexpressed HLA-DO. Loading of synthetic CLIP on HLA-DR + cells increased SEA and TSST-1 binding. Accordingly, knocking down HLA-DM had a similar effect. In mice, H2-O deficiency had no impact on SAgs binding to isolated splenocytes. Altogether, our results demonstrate that the sensitivity of SAgs to the MHCII–associated peptide has physiological basis and that the effect of HLA-DO on SEA and TSST-1 is mediated through the inhibition of CLIP release.

  • Cutting Edge: HLA-DO Impairs the Incorporation of HLA-DM into Exosomes
    Journal of Immunology, 2011
    Co-Authors: Marie-hélène Côté, Marie-claude Bourgeois-daigneault, Marie-Élaine Gauvreau, Andrew D Shaw, Alexandre Brunet, Jacques Thibodeau
    Abstract:

    In multivesicular bodies, HLA-DM (DM) assists the loading of antigenic peptides on classical MHC class II molecules such as HLA-DR. In cells expressing HLA-DO (DO), DM is redistributed from the internal vesicles to the limiting membrane of these organelles. This suggests that DO might reduce DM incorporation into exosomes, which are shed upon fusion of multivesicular bodies with the plasma membrane. To test this hypothesis, we used the 721.45 B lymphoblastoid cell line and different HeLa cell transfectants. We demonstrate that the poor recovery of DM in exosomes as compared with HLA-DR is not the mere reflection of differences in protein expression. Indeed, we found that DO contributes to the inefficient transfer of DM to exosomes. This negative regulation requires an intact di-leucine endosomal sorting motif in the cytoplasmic tail of HLA-DOβ. These results demonstrate that canonical sorting signals and protein–protein interactions modulate the selection of MHC protein cargos.

  • Class II transactivator-induced expression of HLA-DOβ in HeLa cells
    Tissue Antigens, 2002
    Co-Authors: Hayssam Khalil, Georges A. Azar, Francis Deshaies, A. Faubert, Alexandre Brunet, Angelique Bellemare-pelletier, Jacques Thibodeau
    Abstract:

    : HLA-DO is an intracellular nonclassical MHC class II molecule expressed in the endocytic pathway of B lymphocytes. It shapes the repertoire of peptides bound to classical class II molecules such as HLA-DR by regulating the activity of HLA-DM. Using a peptide corresponding to the cytoplasmic tail of HLA-DOβ, we have developed a mouse monoclonal antibody, HKC5. Immunofluorescence microscopy revealed that HKC5 recognizes HLA-DO molecules present in the endoplasmic reticulum as well as those in vesicular compartments of the endocytic pathway. In addition, the antibody detects the isolated β chain on Western blots. Using mutants of the DOβ cytoplasmic tail fused to a reporter molecule and expressed in epithelial cells, we showed by flow cytometry that the antibody epitope includes one or both of the leucine residues forming the lysosomal sorting signal. Finally, we have used HKC5 to evaluate the presence of the HLA-DOβ chain in HeLa cells expressing the class II transactivator protein CIITA. Our flow cytometry and confocal microscopy analyses showed a marked expression of DOβ suggesting that HLA-DO could accumulate under the influence of CIITA in non-B cells.

  • Functional Characterization of a Lysosomal Sorting Motif in the Cytoplasmic Tail of HLA-DOβ
    Journal of Biological Chemistry, 2000
    Co-Authors: Alexandre Brunet, Angela Samaan, Francis Deshaies, Thomas J. Kindt, Jacques Thibodeau
    Abstract:

    Abstract HLA-DO is an intracellular non-classical class II major histocompatibility complex molecule expressed in the endocytic pathway of B lymphocytes, which regulates the loading of antigenic peptides onto classical class II molecules such as HLA-DR. The activity of HLA-DO is mediated through its interaction with the peptide editor HLA-DM. Here, our results demonstrate that although HLA-DO is absolutely dependent on its association with DM to egress the endoplasmic reticulum, the cytoplasmic portion of its β chain encodes a functional lysosomal sorting signal. By confocal microscopy and flow cytometry analysis, we show that reporter transmembrane molecules fused to the cytoplasmic tail of HLA-DOβ accumulated in Lamp-1+ vesicles of transfected HeLa cells. Mutagenesis of a leucine-leucine motif abrogated lysosomal accumulation and resulted in cell surface redistribution of reporter molecules. Finally, we show that mutation of the di-leucine sequence in DOβ did not alter its lysosomal sorting when associated with DM molecules. Taken together, these results demonstrate that lysosomal expression of the DO-DM complex is mediated primarily by the tyrosine-based motif of HLA-DM and suggest that the DOβ-encoded motif is involved in the fine-tuning of the intracellular sorting.

  • Cellular distribution of a mixed MHC class II heterodimer between DRα and a chimeric DOβ chain
    International Immunology, 1999
    Co-Authors: Angela Samaan, Flora Castellino, Wahib Mahana, Jacques Thibodeau, Pierre-andré Cazenave, Thomas J. Kindt
    Abstract:

    Human MHC class II antigens include HLA-DR, -DQ, and -DP molecules that present antigens to CD4 1 T cells, as well as the non-classical molecules HLA-DM and -DO. HLA-DM promotes peptide binding to class II molecules in endocytic compartments and HLA-DO, which is physically associated with HLA-DM in B lymphocytes, regulates HLA-DM function. Antibodies specific for the DOb chain were obtained by immunization of mice with a heterodimer consisting of a chimeric DOb chain (DR/DOβ), containing 18 N-terminal residues of DRb, paired with the DRα chain and isolated from transfected murine fibroblasts. The specificity of this serum for the DOb chain and the lysosomal expression of the HLA-DO protein was confirmed using mutant human B cell lines lacking DR or DO molecules. The lysosomal localization of HLA-DO in human B cells contrasts with the cell surface expression of the mixed pair in transfected murine fibroblasts and raises questions concerning the role of the putative targeting motifs in HLA-DO. Transfection of the chimeric DR/DOb chain along with DRa into human epithelial HeLa cells resulted in high levels of expression of the mixed isotypic pair at the surface of transfectants as well as in lysosomes. The same pattern was observed in HeLa cells transfected with the DOb chimera and a DRa chain lacking the cytoplasmic tail. Taken together, these results suggest that functional sorting motifs exist in the DOb chain but that the tight compartmentalization of HLA-DO observed inside B lymphocytes is controlled by the HLA-DOa chain and HLA-DM.

Hidetoshi Inoko - One of the best experts on this subject based on the ideXlab platform.

  • identification of hla a 02 06 01 as the primary disease susceptibility hla allele in cold medicine related stevens johnson syndrome with severe ocular complications by high resolution ngs based hla typing
    Scientific Reports, 2019
    Co-Authors: Ken Nakatani, Mayumi Ueta, Seiksoon Khor, Yuki Hitomi, Yuko Okudaira, Anri Masuya, Yuki Wada, Chie Sotozono, Shigeru Kinoshita, Hidetoshi Inoko
    Abstract:

    Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening acute inflammatory vesiculobullous reactions of the skin and mucous membranes. These severe cutaneous drug reactions are known to be caused by inciting drugs and infectious agents. Previously, we have reported the association of HLA-A*02:06 and HLA-B*44:03 with cold medicine (CM)-related SJS/TEN with severe ocular complications (SOCs) in the Japanese population. However, the conventional HLA typing method (PCR-SSOP) sometimes has ambiguity in the final HLA allele determination. In this study, we performed HLA-disease association studies in CM-SJS/TEN with SOCs at 3- or 4-field level. 120 CM-SJS/TEN patients with SOCs and 817 Japanese healthy controls are HLA genotyped using the high-resolution next-generation sequencing (NGS)-based HLA typing of HLA class I genes, including HLA-A, HLA-B, and HLA-C. Among the alleles of HLA class I genes, HLA-A*02:06:01 was strongly associated with susceptibility to CM-SJS/TEN (p = 1.15 × 10−18, odds ratio = 5.46). Four other alleles (HLA-A*24:02:01, HLA-B*52:01:01, HLA-B*46:01:01, and HLA-C*12:02:02) also demonstrated significant associations. HLA haplotype analyses indicated that HLA-A*02:06:01 is primarily associated with susceptibility to CM-SJS/TEN with SOCs. Notably, there were no specific disease-causing rare variants among the high-risk HLA alleles. This study highlights the importance of higher resolution HLA typing in the study of disease susceptibility, which may help to elucidate the pathogenesis of CM-SJS/TEN with SOCs.

  • the clinical significance of human leukocyte antigen hla allele compatibility in patients receiving a marrow transplant from serologically hla a hla b and hla dr matched unrelated donors
    Blood, 2002
    Co-Authors: Yasuo Morishima, Hiroshi Sao, Shunichi Kato, Hidetoshi Inoko, Ken Yamamoto, Takehiko Sasazuki, Yoshihide Ishikawa, Tatsuya Akaza, Takeo Juji, Hisashi Sakamaki
    Abstract:

    To improve the clinical outcome of allogeneic hematopoietic stem cell transplantation from an unrelated donor, the identification of human leukocyte antigen (HLA) alleles responsible for immunologic events such as graft-versus-host disease (GVHD), engraftment failure, and graft-versus-leukemia effect is essential. Genomic typing of HLA-A, -B, -C, -DRB1, and -DQB1 was retrospectively performed in 1298 donor-patient pairs in cases where marrow was donated from serologically HLA-A, -B, and -DR compatible donors. Single disparities of the HLA-A, -B, -C, or -DRB1 allele were independent risk factors for acute GVHD, and the synergistic effect of the HLA-C allele mismatch with other HLA allele mismatches on acute GVHD was remarkable. HLA-A and/or HLA-B allele mismatch was found to be a significant factor for the occurrence of chronic GVHD. HLA class I (A, B, and/or C) allele mismatch caused a significantly higher incidence of engraftment failure than HLA match. Significant association of HLA-C allele mismatch with leukemia relapse was not observed. As the result of these events, HLA-A and/or HLA-B allele mismatch reduced overall survival remarkably in both standard-risk and high-risk leukemia cases, whereas the HLA-C mismatch or HLA-class II (DRB1 and/or DQB1) mismatch did not. Furthermore, multiple mismatch of the HLA locus was found to reduce survival in leukemia cases. Thus, the role of the HLA class I allele in unrelated bone marrow transplantation was elucidated. Notably, HLA-C alleles had a different mode from HLA-A or -B alleles for acute GVHD and survival.

  • allele frequencies and haplotypic associations defined by allelic dna typing at hla class i and class ii loci in the japanese population
    Tissue Antigens, 2000
    Co-Authors: E Yamada, Satoshi Saito, Hidetoshi Inoko
    Abstract:

    HLA class I and class II allelic genotypes were determined in 371 unrelated individuals and 309 members of 81 families inhabiting the central Japan area. A total of 20 HLA-A alleles, 16 HLA-Cw alleles, 38 HLA-B alleles, 27 HLA-DRB1 alleles, 15 HLA-DQB1 alleles and 12 HLA-DPB1 alleles were detected. By the two-, three-, four-, five- and six-locus allelic association analyses extracted from the HLA-A to -DPB1 locus, 26 HLA-Cw-B haplotypes, 25 HLA-DRB1-DQB1 haplotypes, 42 HLA-Cw-B-DRB1 haplotypes, 37 HLA-Cw-B-DRB1-DQB1 haplotypes, 29 HLA-A-Cw-B-DRB1-DQB1 haplotypes and 21 HLA-A-Cw-B-DRB1-DQB1-DPB1 haplotypes with the frequencies of higher than 0.005 were recognized. Among 19 HLA-B alleles with the high allele frequencies (above 0.007), 9 HLA-B alleles, B*0702, B*1301, B*3701, B*3901, B*4006, B*4403, B*5201, B*5901 and B*6701 were found to be tightly associated with single HLA-Cw alleles. Most of HLA-DRB1 alleles showed strong associations with single HLA-DQB1 alleles, but DRB1*0802 and DRB1*1401 were associated with two different DQB1 alleles. Extended haplotypes carrying infrequent class I alleles with the allele frequencies of lower than 0.007 were defined by family studies. Gene frequencies and haplotypic associations within the entire HLA classical loci elucidated at the high resolution (four-digital) allelic level will provide useful information on anthropology, marrow donor registry, legal medicine and disease-association studies.

S S Rich - One of the best experts on this subject based on the ideXlab platform.

  • Frequent HLA Class I and DP Sequence Mismatches in Serologically (HLA-A, HLA-B, HLA-DR) and Molecularly (HLA-DRB1, HLA-DQA1, HLA-DQB1) HLA-Identical Unrelated Bone Marrow Transplant Pairs
    2016
    Co-Authors: Pere Santarnaria, M T Boyce-jacino, J J Barbosa, Philip B. Mcglave, Anthony J. Faras, Nancy L. Reinsrnoen, Alan L. Lindstrorn, S S Rich
    Abstract:

    The rates of graft-versus-host disease (GVHD) and rejec-tion are significantly higher among recipients of unrelated donor marrow (BM) than in recipients of marrow from HLA-identical siblings, even when donors and recipients are mixed lymphocyte culture (MLC) compatible and serologi-cally and Dw identical. It has been hypothesized that phe-notypically silent HLA class I and DP sequence mismatches might be associated with these differences, but little is known about their incidence. We have sequenced the HLA-A, HLA-B, HLA-C, HLA-DPA1, and HLA-DPB1 genes ex-pressed by 12 unrelated marrow transplant pairs, 11 of whom were molecularly matched at DRB, DQA1, and DQBl loci. Nine of these pairs were also HLA-A and HLA-B matched by serology. Six of these nine "HLA-identical" pairs were HLA-A (2 of 6). HLA-B (1 of 6). and HLA-C (

  • Frequent HLA class I and DP sequence mismatches in serologically (HLA-A, HLA-B, HLA-DR) and molecularly (HLA-DRB1, HLA-DQA1, HLA-DQB1) HLA-identical unrelated bone marrow transplant pairs
    Blood, 1994
    Co-Authors: Pietro Santamaria, A L Lindstrom, M T Boyce-jacino, J J Barbosa, Philip B. Mcglave, Anthony J. Faras, Nancy L Reinsmoen, S S Rich
    Abstract:

    The rates of graft-versus-host disease (GVHD) and reflection are significantly higher among recipients of unrelated donor marrow (BM) than in recipients of marrow from HLA-identical siblings, even when donors and recipients are mixed lymphocyte culture (MLC) compatible and serologically and Dw identical. It has been hypothesized that phenotypically silent HLA class I and DP sequence mismatches might be associated with these differences, but little is known about their incidence. We have sequenced the HLAA, HLA-B. HLA-C, HLA-DPA1, and HLA-DPB1 genes expressed by 12 unrelated marrow transplant pairs, 11 of whom were molecularly matched at DRB, DQA1, and DQB1 loci

  • Frequent HLA class I and DP sequence mismatches in serologically (HLA-A, HLA-B, HLA-DR) and molecularly (HLA-DRB1, HLA-DQA1, HLA-DQB1) HLA-identical unrelated bone marrow transplant pairs.
    Blood, 1994
    Co-Authors: Pietro Santamaria, A L Lindstrom, M T Boyce-jacino, J J Barbosa, Philip B. Mcglave, Anthony J. Faras, Nancy L Reinsmoen, S S Rich
    Abstract:

    The rates of graft-versus-host disease (GVHD) and rejection are significantly higher among recipients of unrelated donor marrow (BM) than in recipients of marrow from HLA-identical siblings, even when donors and recipients are mixed lymphocyte culture (MLC) compatible and serologically and Dw identical. It has been hypothesized that phenotypically silent HLA class I and DP sequence mismatches might be associated with these differences, but little is known about their incidence. We have sequenced the HLA-A, HLA-B, HLA-C, HLA-DPA1, and HLA-DPB1 genes expressed by 12 unrelated marrow transplant pairs, 11 of whom were molecularly matched at DRB, DQA1, and DQB1 loci. Nine of these pairs were also HLA-A and HLA-B matched by serology. Six of these nine "HLA-identical" pairs were HLA-A (2 of 6), HLA-B (1 of 6), and HLA-C (6 of 6) mismatched at the sequence level. The mismatched class I alleles of all these pairs had strikingly different sequence motifs in the six specificity pockets of their antigen recognition site, and in five pairs they also had sequence differences at positions implicated in T-cell receptor (TCR) binding. Two of the three pairs who were serologically mismatched for one HLA-A or HLA-B antigen were also sequence mismatched at HLA-C. Finally, 10 of 11 pairs tested expressed different DP sequences. These data indicate that HLA class I, especially HLA-C, and DP sequence mismatches are frequent among unrelated subjects defined as HLA identical by current typing methods. We speculate that these sequence differences may explain, at least in part, the higher incidence of acute GVHD and rejection in unrelated BM transplantation as opposed to transplantation between HLA-identical siblings. Because of their high frequency, the role of HLA-A, HLA-B, HLA-C, and HLA-DP mismatches in transplantation outcome is now amenable to direct study.

Muhammad Atif - One of the best experts on this subject based on the ideXlab platform.

  • Photodynamic damage study of HeLa cell line using ALA
    Laser Physics, 2011
    Co-Authors: Mohamad S. Alsalhi, Muhammad Atif, A. A. Alobiadi, Abdullah S. Aldwayyan
    Abstract:

    The present study evaluates the photodynamic damage with 5-aminolevulinic acid (5-ALA) using HeLa as experimental model. HeLa cell line was irradiated with red light (He-Ne laser, λ = 632.8 CW nm). The influence of different incubation times and concentrations of 5-ALA, different irradiation doses and various combinations of photosensitizer and light doses on the cellular viability of HeLa cells were studied. The optimal uptake of photosensitizer ALA in HeLa cells was investigated by means of PpIX fluorescence intensity by exciting the HeLa cell suspension at 450 nm and a detection wavelength set at 690 nm. Cells viability was determined by means of trypan blue solution. The spectrometric measurements showed that the maximal cellular uptake of 5-ALA occurred after 4 h in vitro incubation. We found that the combination with 5-ALA and laser irradiation leads to time/concentration-dependent increase of cells death and also energy doses-dependent enlarge the cells death. The fluorescence intensity after PDD of carcinoma cells reduce when compared with the control group. The fluorescence emission spectral profiles after PDD of carcinoma cells showed a dip around 425–525 nm when compared with the control group. This may be due to the damage of mitochondria component of cells. The percentage of HeLa cells after PDD shows that the percentage of cells survival rate as function of laser dose (power). Hence it is clear that at 200 μg/ml ALA and 20 mW laser irradiation, more than 70% of HeLa cells were dead after 15 min.

  • in vitro study of 5 aminolevulinic acid based photodynamic therapy for apoptosis in human cervical hela cell line
    Laser Physics Letters, 2009
    Co-Authors: Muhammad Atif, S. Firdous, Ahmat Khurshid, L. Noreen, Syed Sohail Zahoor Zaidi, Masroor Ikram
    Abstract:

    5-aminolevulanic acid (ALA), belonging among the promising second generation of sensitizers, was evaluated as an inducer of photodamage on HeLa (human cervical adenocarcinoma) cell line. A diode laser (635 nm) was used as a source for initiation of the photodynamic effect. We studied the influence of different incubation times, various concentrations of sensitizer, different irradiation doses and various combinations of sensitizer and light doses on the photodamage of HeLa cells. Viability of cells was determined by means of neutral red assay. The quantitative cellular uptake of ALA sensitizer was done by spectrophotometric measurements. No prominent cytotoxic or phototoxic effects on HeLa were observed due to sensitizer or light doses when studied independently of each other. However phototoxicity evoked by laser irradiated sensitizer was detected in HeLa cell line.

  • In vitro study of 5‐aminolevulinic acid‐based photodynamic therapy for apoptosis in human cervical HeLa cell line
    Laser Physics Letters, 2009
    Co-Authors: Muhammad Atif, S. Firdous, Ahmat Khurshid, L. Noreen, Syed Sohail Zahoor Zaidi, Masroor Ikram
    Abstract:

    5-aminolevulanic acid (ALA), belonging among the promising second generation of sensitizers, was evaluated as an inducer of photodamage on HeLa (human cervical adenocarcinoma) cell line. A diode laser (635 nm) was used as a source for initiation of the photodynamic effect. We studied the influence of different incubation times, various concentrations of sensitizer, different irradiation doses and various combinations of sensitizer and light doses on the photodamage of HeLa cells. Viability of cells was determined by means of neutral red assay. The quantitative cellular uptake of ALA sensitizer was done by spectrophotometric measurements. No prominent cytotoxic or phototoxic effects on HeLa were observed due to sensitizer or light doses when studied independently of each other. However phototoxicity evoked by laser irradiated sensitizer was detected in HeLa cell line.