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Biomedical subjects

A J Barrett

Publications and source records attributed to A J Barrett.

At least 19 recordsLinked to original sources
PubMed1992

Simultaneous genotypic and immunophenotypic analysis of interphase cells using dual-color fluorescence: a demonstration of lineage involvement in polycythemia vera.

Fluorescent in situ hybridization has become a useful technique by which chromosomal abnormalities may be shown in interphase cells. We present a dual-fluorescence method whereby a chromosomal and immunophenotypic marker can be visualized simultaneously in the same interphase cell. Two patients with the myeloproliferative disorder polycythemia vera and trisomy for chromosome 8 have been studied using this technique and selective involvement of the myeloid and erythrocyte lineages has been shown by the detection of the trisomy in immunophenotyped cells. Simultaneous analysis of genotype and immunophenotype in individual cells from patients with myeloproliferative disorders or leukemia may help identify the developmental and lineage status of cells in which molecular alterations have resulted in clonal advantage.

Aged↗
PubMed1992

Changing trends in allogeneic bone marrow transplantation for leukemia in the 1980s.

OBJECTIVE: To identify changes in practice and outcome of bone marrow transplants for leukemia in the 1980s. DESIGN: Comparison of key explanatory and outcome variables in five 2-year cohorts, from 1980 through 1981 to 1988 through 1989, using a large database of detailed clinical information. PATIENTS: Recipients (7788) of bone marrow transplants for acute lymphoblastic, acute myelogenous, or chronic myelogenous leukemia reported to the International Bone Marrow Transplant Registry, Milwaukee, Wis, by 185 transplant teams worldwide. RESULTS: Linear increases occurred during the periods 1980 through 1981 to 1988 through 1989 as follows with 95% confidence intervals: (1) transplants for chronic myelogenous leukemia from 14% +/- 2% to 35% +/- 2%; (2) transplants from unrelated donors from 1% +/- 1% to 7% +/- 1%; (3) preparative regimens without radiation from 3% +/- 1% to 30% +/- 2%; and (4) use of methotrexate plus cyclosporine to prevent graft-vs-host disease from 2% +/- 1% to 55% +/- 2%. Among recipients of human lymphocyte antigen-identical sibling bone marrow, the 2-year probability of treatment-related mortality decreased by 6% to 22%. The probability of relapse decreased from 46% +/- 6% to 38% +/- 6% in intermediate leukemia but did not change appreciably in early or advanced leukemia. Probabilities of leukemia-free survival improved from 51% +/- 4% to 57% +/- 3% in early leukemia, from 28% +/- 4% to 36% +/- 5% in intermediate leukemia, and from 12% +/- 4% to 18% +/- 5% in advanced leukemia. A separate analysis of a homogenous population of patients indicated that improvements in outcome in the 1980s were due to improvements in transplant practice rather than improved patient selection. CONCLUSIONS: Modest increases in leukemia-free survival rates occurred after human lymphocyte antigen-identical sibling bone marrow transplants in the 1980s. Improvements were due primarily to reductions in treatment-related mortality with little or no change in relapse risk. More effective antileukemia strategies and continued reductions in treatment-related toxic effects are needed.

Adult↗
PubMed1992

Quantification of peptide aldehyde ligands immobilized for the affinity chromatography of endopeptidases.

A method is described for quantification of aldehyde and aldehyde semicarbazone groups attached to an insoluble matrix. Semicarbazones are converted to aldehydes, and the aldehydes are coupled with 4-phenylazoaniline. The excess reagent is washed off, and the remainder then displaced with salicylaldehyde. The quantity of the phenylazoaniline/salicylaldehyde adduct is determined spectrophotometrically, allowing the calculation of the amount of aldehyde or semicarbazone per unit volume of the matrix. Analyses by the new method show that four matrices offered commercially for this type of immobilization differ greatly in coupling capacity and stability of the conjugate under conditions of affinity chromatography.

Aldehydes↗
PubMed1992

Bone marrow transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia.

Philadelphia chromosome (Ph1)-positive acute lymphoblastic leukemia (ALL) has a poor prognosis when treated with conventional chemotherapy. We analyzed the outcome of 67 HLA-identical sibling bone marrow transplants (BMTs) for Ph1-positive ALL reported to the International Bone Marrow Transplant Registry (IBMTR). Twenty-one of 67 (31%) transplant recipients survived in continuous complete remission more than 2 years after transplant. Two-year actuarial probabilities (95% confidence interval) of leukemia-free survival were 38% (23% to 55%) for 33 patients transplanted in first remission, 41% (23% to 61%) for 22 patients transplanted after relapse, and 25% (9% to 53%) for 12 patients failing to achieve remission with conventional chemotherapy. These data indicate that transplants are effective treatment for Ph1-positive ALL.

Adolescent↗
PubMed1992

The effects of selective matrix degradation on the short-term compressive properties of adult human articular cartilage.

The effects of proteoglycan and collagen digestion on the transient response of human articular cartilage when tested in unconfined compression were determined. Small cylindrical specimens of cartilage, isolated from the femoral head of the hip joint and from the femoral condyles of the knee joint, were subjected to a suddenly applied compressive load using a test apparatus designed to yield a transient oscillatory response. From this response values of the elastic stiffness and the viscous damping coefficient were determined. Cathepsin D and cathepsin B1 were used to digest the proteoglycan in some specimens, while in other specimens leukocyte elastase was used to attack the non-helical terminal regions of the Type II tropocollagen molecules and possibly the Type IX collagen molecule and thereby disturb the integrity of the collagen mesh. The results showed that proteoglycan digestion alone reduced the viscous damping coefficient but it did not significantly alter the elastic stiffness as determined from the oscillatory response. In contrast, the action of elastase reduced both the damping coefficient and the elastic stiffness of the cartilage. The results demonstrated the role of proteoglycans in regulating fluid transport in cartilage and hence controlling the time-dependent viscous properties. The elastic stiffness was shown to be dependent on the integrity of the collagen fibre network and not on the proteoglycans.

Aged↗
PubMed1992

CA074 methyl ester: a proinhibitor for intracellular cathepsin B.

The specificity of compound CA074 [N-(L-3-trans-propylcarbamoyloxirane-2-carbonyl)-L-isoleucyl-L-pro line] for the inactivation of cathepsin B was quantified in in vitro measurements with cysteine endopeptidases from cattle, it being found that the compound is a very rapid inactivator of cathepsin B (rate constant 112,000 M-1.s-1), with barely detectable action on cathepsins H, L, and S or m-calpain. Conversion of the proline carboxyl group of the inhibitor to the methyl ester virtually abolished the effect on cathepsin B, and a possible explanation for the importance of the carboxyl is presented on the basis of the tertiary structure of cathepsin B. It was found that CA074 methyl ester (1 microM, 3 h) caused selective inactivation of the intracellular cathepsin B of human gingival fibroblasts in culture, in contrast to other available agents, and we suggest that CA074 methyl ester will be of value in the elucidation of the biological functions of cathepsin B.

Binding Sites↗
PubMed1992

Graft vs. leukaemia reactions in chronic myeloid leukaemia.

A 39-year-old female relapsed 36 months after allogeneic bone marrow transplantation for chronic myeloid leukaemia. Infusion of peripheral blood leucocytes from her bone marrow donor resulted in complete remission, and she remains leukaemia-free 18 months later. This case provides direct evidence for a 'graft vs. leukaemia' (GVL) effect contributing to the eradication of leukaemia after marrow transplantation. Existing evidence for GVL and its possible mechanisms are reviewed.

Adult↗
PubMed1992

The ENZYMEBA test: detection of intestinal Entamoeba histolytica infection by immuno-enzymatic detection of histolysain.

We describe a new, improved test for the detection of intestinal infection by Entamoeba histolytica. The test depends upon immunoadsorption of the E. histolytica cysteine proteinase, histolysain, from faecal samples, and subsequent visual detection of the enzyme by a colour reaction. With samples from 200 volunteers, results agreed closely with those obtained by the conventional microscopic technique, and there were no false positive reactions with samples containing other parasites. The test is suitable for use either in the laboratory or in the field.

Amebicides↗
PubMed1992

Relapse into blast crisis following bone marrow transplantation for chronic phase chronic myeloid leukaemia: a report of five cases.

A proportion of patients receiving allogeneic bone marrow transplants (BMT) for chronic myeloid leukaemia (CML) in first chronic phase relapse; most of these relapses show features of chronic phase disease. We report here a series of five patients seen at a single institution over a 10 year period who developed blast crisis as the first sign of relapse after BMT for CML in chronic phase. The blast cells were myeloid in three cases and lymphoid in two. In one case the relapse may have occurred in cells of donor origin. The possible explanations for this unusual sequence of events include incipient transformation that was not detected before BMT, undetected relapse into chronic phase proceeding into transformation post-BMT, and transformation occurring de novo post-BMT in small numbers of residual leukaemic stem cells.

Adult↗
PubMed1992

HLA-identical sibling donor bone marrow transplantation for chronic myeloid leukaemia in first chronic phase: influence of GVHD prophylaxis on outcome.

We have analysed the results of treating 140 consecutive patients with chronic myeloid leukaemia (CML) in chronic phase by bone marrow transplantation (BMT) using marrow from HLA-identical siblings performed between February 1981 and July 1991. Three different regimens were used sequentially to prevent graft-versus-host disease (GVHD): cyclosporin A (CsA) alone (n = 39), T-cell depletion of donor marrow (n = 51) and CsA with methotrexate (MTX) (n = 50). Eighty-four patients (61%) survive at a median of 49 months from BMT (range 3-120). The actuarial overall and leukaemia-free survivals at 5 years were 52% and 41% respectively. The actuarial probabilities of leukaemia-free survival and haematological relapse at 2 years for the CsA only group were 65% and 4%, for the T-cell depletion group 40% and 41% and for the CsA/MTX group 68% and 6% respectively. For the T-cell depletion group the probability of leukaemia-free survival was significantly lower (P less than 0.001) and the probability of relapse significantly higher (P less than 0.001) than for other methods of GVHD prophylaxis; differences between the other two groups were not significant. Previous reports that T-cell depletion with Campath-1M results in a high rate of relapse are confirmed. Patients in the CsA/MTX group have been monitored with cytogenetic and polymerase chain reaction studies for residual BCR/ABL transcripts. We conclude that the combination of CsA/MTX is currently the best available approach to prevention of GVHD after BMT for CML and in our hands it is not associated with a major risk of relapse.

Adolescent↗
PubMed1992

Oligopeptidases, and the emergence of the prolyl oligopeptidase family.

Oligopeptidases are endopeptidases that are not proteinases in the strict sense, since they do not hydrolyse peptide bonds in proteins, but act only on smaller polypeptides or oligopeptides. These enzymes apparently perform important, specialized biological functions that include the modification or destruction of peptide messenger molecules. Oligopeptidases have few naturally occurring inhibitors, and their distinctive specificity prevents them from interacting with alpha 2-macroglobulin, unlike the great majority of endopeptidases. The specificity of these specialized endopeptidases doubtless depends upon the three-dimensional structure of the active site, but no crystallographic structure is yet available for an oligopeptidase. Study of the primary structure of prolyl oligopeptidase has recently shown that it is a member of a new family of serine-type peptidases most of which are exopeptidases. The alignment of the sequences leads to the identification of some catalytic triad residues that have not yet been elucidated experimentally.

Amino Acid Sequence↗
PubMed1992

Transplants in ALL.

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Bone Marrow Transplantation↗