| 45151. |
- Li, Aihong, et al.
(författare)
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Clonal rearrangements in childhood and adult precursor B acute lymphoblastic leukemia : a comparative polymerase chain reaction study using multiple sets of primers.
- 1999
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Ingår i: European Journal of Haematology. - 0902-4441 .- 1600-0609. ; 63:4, s. 211-8
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Tidskriftsartikel (refereegranskat)abstract
- Ig heavy chain (IgH) and T-cell receptor (TCR) gene rearrangements were investigated by polymerase chain reaction (PCR) amplification of diagnostic tumour samples from 91 patients (57 children and 34 adults, with cut-off at age 16) with precursor B acute lymphoblastic leukemia (ALL). Using primers directed to the framework regions (FR) 1, 2 and 3 of the IgH gene, clonal IgH rearrangements were observed in 82, 58 and 58%, respectively, whereas clonality was presented in 45 and 27% using primers hybridising to the TCR delta and gamma genes. A combination of all five primer sets used resulted in 96% positive cases (children 100%, adults 88%). The frequency of clonal IgH rearrangements correlated to patient age with a significantly lower fraction of positive cases in the adult group. The concomitant usage of more than one V(H) family gene was similar for childhood and adult ALL, and an over-representation of V(H)6 rearrangements was found in childhood ALL. Twenty-five out of 91 cases (27%) displayed an oligoclonal pattern for either IgH or TCR gene rearrangements (children 37%, adults 12%). A comparative analysis of samples from different compartments was performed in 23 patients, and differences between two or three compartments were observed in seven cases. Unexpectedly large, clonally appearing PCR products of 540-715 bp were found in three leukemias and sequence analysis verified their clonal nature. In summary, using multiple sets of primers clonal rearrangements of IgH and TCR genes can be detected in a very high frequency, including previously neglected large size PCR products. A common heterogeneity was demonstrated in different compartments reflecting ongoing clonal evolution, which can make detection of minimal residual disease (MRD) in ALL troublesome. Therefore, we suggest that a minimum of three targets should be used to minimise false-negative results.
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| 45152. |
- Li, Aihong, et al.
(författare)
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Detailed clonality analysis of relapsing precursor B acute lymphoblastic leukemia : implications for minimal residual disease detection.
- 2001
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Ingår i: Leukemia Research. - 0145-2126 .- 1873-5835. ; 25:12, s. 1033-45
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Tidskriftsartikel (refereegranskat)abstract
- Genetic instability has important implications for detection of minimal residual disease (MRD) when the target is a clonal genetic marker revealed at diagnosis. A successful MRD detection approach requires a stable marker and for lymphoid leukemias clonal rearrangements of immunoglobulin (Ig) and T cell receptor (TCR) genes are commonly used. In the present study, Ig heavy chain (IgH) and TCR (gamma and delta) genes were studied in 18 consecutive, relapsing precursor-B ALL patients. At least one clonal rearrangement was found in all cases at presentation (IgH 94%, TCRgamma 39% and TCRdelta 28%). An altered rearrangement pattern between diagnosis and relapse was demonstrated in 14 patients (78%). At least one stable molecular target was found in 13 out of 18 cases (72%). Clonal differences between diagnostic and relapse samples were explained by: (1) loss of original rearrangements; (2) V(H) to DJ(H) joining; (3) V(H) gene replacement; (4) appearance of new rearrangements. In two cases with apparently new IgH gene rearrangements at relapse extended sequencing of the diagnostic samples revealed minor clonal rearrangements identical to the relapse clones. Interestingly, one patient displayed instability on both the IgH and TCR gene loci, whereas a stable Igkappa rearrangement was found at presentation and relapse. These data show that clonal diversity is common in precursor-B ALL and strongly suggest that MRD detection should include multiple gene targets to minimize false-negative samples. Even so, five of our 18 relapse cases (28%) lacked stable clonal markers and should have been unsuitable for MRD detection.
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| 45153. |
- Li, Aihong, et al.
(författare)
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Distinctive IGH gene segment usage and minimal residual disease detection in infant acute lymphoblastic leukaemias.
- 2005
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Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 131:2, s. 185-92
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Tidskriftsartikel (refereegranskat)abstract
- Infant acute lymphoblastic leukaemia (ALL) represents a rare but unique subset with poor prognosis. We analysed mixed-lineage leukaemia (MLL) gene rearrangements and the sequences of complete and incomplete immunoglobulin heavy chain gene rearrangements (IGH) in 14 infants (age < or = 12 months at diagnosis) enrolled on Dana-Farber Cancer Institute ALL Consortium Protocol 95-01. The dynamics of the leukaemic clone were followed during the course of the disease by quantitative real-time polymerase chain reaction of IGH rearrangements. Sixteen sequences were obtained from 13 (93%) of these infants. There was marked over usage of the V(H)6.1 gene segment (64%) in infants compared with older children with ALL (8%), (P < 0.001) and overusage of D(H)6 (P = 0.004) and J(H)1 (P = 0.004). Poor outcome was associated with MLL gene rearrangements rather than any specific V(H)D(H)J(H) gene usage patterns. Levels of minimal residual disease (MRD) at the end of induction appeared to be high in infants with ALL compared with older children, and although the number of infant cases studied was small, there were no differences in MRD levels after induction therapy in infant ALL with or without MLL gene rearrangements (P = 0.41) and quantitative MRD assessment at the early time points may not be predictive of outcome. Novel treatment strategies are required to improve the outcome in this poor prognosis subset of children with ALL.
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| 45154. |
- Li, Aihong, et al.
(författare)
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Minimal residual disease quantification in childhood acute lymphoblastic leukemia by real-time polymerase chain reaction using the SYBR green dye.
- 2002
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Ingår i: Experimental Hematology. - 0301-472X .- 1873-2399. ; 30:10, s. 1170-1177
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Clone specific immunoglobulin (Ig) and T-cell receptor (TCR) gene sequences can be used as molecular targets for detection of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL). Real-time quantitative PCR (RQ-PCR) with no need for post-PCR processing is an attractive approach for detection and quantification of specific DNA or RNA sequences. In the present study we evaluated a real-time PCR-based technology for MRD quantification in children with precursor-B ALL. MATERIALS AND METHODS: DNA samples from 36 children with newly diagnosed precursor-B ALL were available for molecular analysis. All patients were uniformly treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) protocols from 1992. A real-time PCR assay was applied for MRD quantification using LightCycler technology and the SYBR green fluorescent dye for detection of clone-specific Ig and TCR gene rearrangements as target sequences. The specificity of the PCR products was verified by melting curve analysis. RESULTS: Thirty-four of the 36 children with precursor-B ALL (94%) displayed at least one clonal Ig heavy chain (IgH) or TCR gene sequence useful as a molecular target. These clone-specific targets were successfully applied for real-time PCR quantification in all but one patient. Melting curve analysis was important for identifying all specific PCR products. In 32 pediatric precursor-B-ALL patients an MRD level >/=10(-3) at day 29 during induction treatment was significantly correlated with later bone marrow relapse (p = 0.0025). CONCLUSIONS: Real-time PCR using clone-specific primers and the SYBR green dye for detection is a feasible technique for identifying patients at risk for relapse. This approach provides an easily applicable tool for detection of IgH/TCR gene rearrangements in the routine setting. Melting curve analysis allowed clear distinction between specific rearrangements and unspecific background signals.
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| 45155. |
- Li, Aihong, et al.
(författare)
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Sequence analysis of clonal immunoglobulin and T-cell receptor gene rearrangements in children with acute lymphoblastic leukemia at diagnosis and at relapse : implications for pathogenesis and for the clinical utility of PCR-based methods of minimal residual disease detection.
- 2003
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 102:13, s. 4520-4526
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Tidskriftsartikel (refereegranskat)abstract
- Immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements provide clonal markers useful for diagnosis and measurement of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL). We analyzed the sequences of Ig and TCR gene rearrangements obtained at presentation and relapse in 41 children with ALL to study clonal stability, which has important implications for monitoring MRD, during the course of the disease. In 42%, all original Ig and/or TCR sequences were conserved. In 24%, one original sequence was preserved but the other lost, and in 14% the original sequences were conserved with new sequences identified at relapse. In 20% only new sequences were found at relapse. Using primers designed from the novel relapse sequences, the relapse clone could be identified as subdominant clones in the diagnostic sample in 8 of 14 patients. Alteration of these clonal gene rearrangements is a common feature in childhood ALL. MRD detection should include multiple gene targets to minimize false-negative samples or include also multicolor flow cytometry. In some cases the leukemic progenitor cell might arise earlier in lineage before DHJH recombination but retain the capacity to further differentiate into cells capable of altering the pattern of Ig and/or TCR rearrangements.
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| 45156. |
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| 45157. |
- Li, Aihong, et al.
(författare)
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Utilization of Ig heavy chain variable, diversity, and joining gene segments in children with B-lineage acute lymphoblastic leukemia : implications for the mechanisms of VDJ recombination and for pathogenesis.
- 2004
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 103:12, s. 4602-9
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Tidskriftsartikel (refereegranskat)abstract
- Sequence analysis of the immunoglobulin heavy chain genes (IgH) has demonstrated preferential usage of specific variable (V), diversity (D), and joining (J) genes at different stages of B-cell development and in B-cell malignancies, and this has provided insight into B-cell maturation and selection. Knowledge of the association between rearrangement patterns based on updated databases and clinical characteristics of pediatric acute lymphoblastic leukemia (ALL) is limited. We analyzed 381 IgH sequences identified at presentation in 317 children with B-lineage ALL and assessed the V(H)D(H)J(H) gene utilization profiles. The D(H)J(H)-proximal V(H) segments and the D(H)2 gene family were significantly overrepresented. Only 21% of V(H)-J(H) joinings were potentially productive, a finding associated with a trend toward an increased risk of relapse. These results suggest that physical location at the V(H) locus is involved in preferential usage of D(H)J(H)-proximal V(H) segments whereas D(H) and J(H) segment usage is governed by position-independent molecular mechanisms. Molecular pathophysiology appears relevant to clinical outcome in patients who have only productive rearrangements, and specific rearrangement patterns are associated with differences in the tumor biology of childhood ALL.
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| 45158. |
- Li, Angui, et al.
(författare)
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Ventilation and environmental control of underground spaces : a short review
- 2019
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Ingår i: E3S Web of Conferences. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- More and more underground spaces were used in 21st century because of rapid urbanization, traffic problems, etc. Underground city, metro, tunnel, mine, industrial and agriculture engineering, civil air defence engineering need large underground spaces. Underground spaces with different thermal, ventilation and lighting environments may cause comfort, health and safety problems. Concrete problems include excessive humidity, heat transfer specialty, excessive CO caused by blockage in long distance traffic tunnels, difficulty in smoke exhaust and evacuation during fire, harmful microorganism, radioactivity pollutants, psychological problems, and so forth. Air quality control technologies for underground spaces, including ventilation technology, dehumidification technology, natural energy utilization technology, smoke extraction technology and ventilation resistance reduction technology, will be reviewed. Ventilation for smoke-proof/evacuation and ventilation will also be reviewed.
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| 45159. |
- Li, Bo, 1982-, et al.
(författare)
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Distinctive curve features
- 2016
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Ingår i: Electronics Letters. - : John Wiley & Sons. - 0013-5194 .- 1350-911X. ; 52:3, s. 197-198
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Tidskriftsartikel (refereegranskat)abstract
- Curves and lines are geometrical, abstract features of an image. Whereas interest points are more limited, curves and lines provide much more information of the image structure. However, the research done in curve and line detection is very fragmented. The concept of scale space is not yet fused very well into curve and line detection. Keypoint (e.g. SIFT, SURF, ORB) is a successful concept which represent features (e.g. blob, corner etc.) in scale space. Stimulated by the keypoint concept, a method which extracts distinctive curves (DICU) in scale space, including lines as a special form of curve features is proposed. A curve feature can be represented by three keypoints (two end points, and one middle point). A good way to test the quality of detected curves is to analyse the repeatability under various image transformations. DICU using the standard Oxford benchmark is evaluated. The overlap error is calculated by averaging the overlap error of three keypoints on the curve. Experiment results show that DICU achieves good repeatability comparing with other state-of-the-art methods. To match curve features, a relatively uncomplicated way is to combine local descriptors of three keypoints on each curve.
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| 45160. |
- Li, Bo, 1982-, et al.
(författare)
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Distinctive curves : unified scale-invariant detection of edges, corners, lines and curves
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper aims to broaden the scope of shape related features including edges, corners, lines and curves: 1) Edges, corners, lines, curves are all shape related features. In the past, the detection of each type of feature is usually solved independently under certain hypotheses. Our proposed distinctive curve detection method (DICU) solves the detection of all these type of features together. 2) Compared to the development in scale-invariant interest point detectors which have adopted more objective robustness measures using repeatability score, the research in line and curve features is still limited to “true/false positive” measures. DICU detection utilizes the scale-space concept and proves that curve features can be as robust as scale-invariant interest points. DICU has three advantages: 1) DICU outputs multi-type features which can benefit future computer vision applications. At the same time, the computational efficiency is unaffected, after detecting edges, only 5% additional computation is needed to detect corners, lines, and curves. 2) It is robust under various image perturbations and transformations and outperforms state-of-the-art interest point detectors and line detectors. At the same time, all types of detected features are robust. 3) Curve features contains more geometric information than points. Our curve matching test shows that curve matching can outperform interest point matching.
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