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D C Linch

Publications and source records attributed to D C Linch.

At least 37 records · Page 2Linked to original sources
PubMed2001

Activation and priming of neutrophil nicotinamide adenine dinucleotide phosphate oxidase and phospholipase A(2) are dissociated by inhibitors of the kinases p42(ERK2) and p38(SAPK) and by methyl arachidonyl fluorophosphonate, the dual inhibitor of cytosolic and calcium-independent phospholipase A(2).

Arachidonic acid (AA) generated by phospholipase A(2) (PLA(2)) is thought to be an essential cofactor for phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Both enzymes are simultaneously primed by cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-alpha). The possibility that either unprimed or cytokine-primed responses of PLA(2) or NADPH oxidase to the chemotactic agents formyl-methionyl-leucyl-phenylalanine (FMLP) and complement factor 5a (C5a) could be differentially inhibited by inhibitors of the mitogen-activated protein (MAP) kinase family members p42(ERK2) (PD98059) and p38(SAPK) (SB203580) was investigated. PD98059 inhibited the activation of p42(ERK2) by GM-CSF, TNF-alpha, and FMLP, but it did not inhibit FMLP-stimulated superoxide production in either unprimed or primed neutrophils. There was no significant arachidonate release from unprimed neutrophils stimulated by FMLP, and arachidonate release stimulated by calcium ionophore A23187 was not inhibited by PD98059. In contrast, PD98059 inhibited both TNF-alpha- and GM-CSF-primed PLA(2) responses stimulated by FMLP. On the other hand, SB203580 inhibited FMLP-superoxide responses in unprimed as well as TNF-alpha- and GM-CSF-primed neutrophils, but failed to inhibit TNF-alpha- and GM-CSF-primed PLA(2) responses stimulated by FMLP, and additionally enhanced A23187-stimulated arachidonate release, showing that priming and activation of PLA(2) and NADPH oxidase are differentially dependent on both the p38(SAPK) and p42(ERK2) pathways. Studies using C5a as an agonist gave similar results and confirmed the findings with FMLP. In addition, methyl arachidonyl fluorophosphonate (MAFP), the dual inhibitor of c and iPLA(2) enzymes, failed to inhibit superoxide production in primed cells at concentrations that inhibited arachidonate release. These data demonstrate that NADPH oxidase activity can be dissociated from AA generation and indicate a more complex role for arachidonate in neutrophil superoxide production.

Arachidonic Acid↗
PubMed2001

Lung cancer after Hodgkin's disease: a nested case-control study of the relation to treatment.

PURPOSE: To investigate the causes of the raised risk of lung cancer in patients who have had Hodgkin's disease, and in particular the relationship to treatment. PATIENTS AND METHODS: A nested case-control study was conducted within a cohort of 5,519 patients with Hodgkin's disease treated in Britain during 1963 through 1993. For 88 cases of lung cancer and 176 matched control subjects, information on treatment and other risk factors was extracted from hospital case-notes, and odds ratios for lung cancer in relation to these factors were calculated. RESULTS: Risk of lung cancer was borderline significantly greater in patients treated with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) chemotherapy than those who did not receive this treatment (relative risk [RR] = 1.66; 95% confidence interval [CI], 0.99 to 2.82), and increased with number of cycles of MOPP (P =.07). Exclusion of lung cancers for which histologic confirmation was not available strengthened these associations (RR = 2.41; 95% CI, 1.33 to 4.51; P =.004 for any MOPP and P =.007 for trend with number of cycles of MOPP). Risks were not raised, however, after chlorambucil, vinblastine, procarbazine, and prednisone treatment. There was evidence that the raised risk of lung cancer occurring in relation to radiotherapy was restricted to histologies other than adenocarcinoma. CONCLUSION: The results suggest that MOPP chemotherapy may lead to elevated risk of lung cancer, at least in certain subgroups of patients. The role of chemotherapy in the etiology of lung cancer after Hodgkin's disease deserves further investigation.

Adult↗
PubMed2001

Lack of pathogenic mutations in the 5'-untranslated region of the thrombopoietin gene in patients with non-familial essential thrombocythaemia.

Thrombopoietin (TPO) is thought to be the major physiological regulator of thrombopoiesis, and, in general, circulating levels are inversely proportional to megakaryocyte and platelet mass. However, normal or elevated TPO levels are found in patients with essential thrombocythaemia (ET) and the reason for this is not fully understood. Recent studies have shown that four kindreds with hereditary thrombocythaemia (HT) have point mutations in the 5'-untranslated region (UTR) of the TPO gene which lead to increased TPO translation. In order to determine whether similar mutations are present in apparently acquired ET, in particular in those patients with polyclonal myelopoiesis, we have studied this region in 50 ET patients using neutrophil DNA. The known HT mutations were investigated using polymerase chain reaction with mismatch primers and restriction enzyme digestion; only wild-type alleles were detected. Single-stranded conformation polymorphism (SSCP) analysis of exons 1-4 identified a C-->T substitution at nucleotide 3767. However, this appears to be a common polymorphism, as it was present at the same frequency in haematologically normal controls and is unlikely to be of pathological significance. These results demonstrate that mutations in the 5' UTR of the TPO gene are not the cause of the normal or elevated TPO levels in acquired ET.

5' Untranslated Regions↗
PubMed2001

Excessive T cell depletion of peripheral blood stem cells has an adverse effect upon outcome following allogeneic stem cell transplantation.

We evaluated the outcome of two modes of T cell depletion for HLA-identical sibling stem cell transplants in 34 consecutive adult patients: group A (n = 11) received PBSC post CliniMACs immuno-magnetic enrichment of CD34(+) cells and group B (n = 23) received bone marrow following in vitro incubation with CAMPATH-1M and complement. All patients received an identical conditioning regimen which consisted of in vivoCAMPATH-1H 20 mg over 5 days, thiotepa 10 mg/kg, cyclophosphamide 120 mg/kg and 14.4 Gy TBI. No additional graft-versus-host disease prophylaxis was given. The mean T cell dose administered was 0.02 +/- 0.05 x 10(6)/kg for group A and 2.8 +/- 2.8 10(6)/kg for group B (P < 0.001). With a median follow-up of 28 months overall survival was 36.4% for group A at 12 months compared to 78.3% for group B (P = 0.001). Transplant-related mortality in group A at 12 months was 63.6% as compared to 18.0% in group B (P = 0.003). Most of the procedure-related deaths in group A occurred secondary to infection. These results suggest that extensive in vitro T cell depletion of peripheral blood stem cells in combination with in vivo T cell depletion may have profound effects upon the incidence of infections following allogeneic stem cell transplantation and this may adversely effect transplant-related mortality.

Adult↗
PubMed2001

Gynaecomastia with hypergonadotrophic hypogonadism and Leydig cell insufficiency in recipients of high-dose chemotherapy or chemo-radiotherapy.

Late side-effects of stem cell transplantation include hypogonadism with infertility and sexual dysfunction, but gynaecomastia is less well recognised. We report five cases of gynaecomastia with features of hypergonadotrophic hypogonadism (primary testicular failure), who received either a TBI/cyclophosphamide conditioned allograft (n = 3) or a BEAM autograft (n = 2). Patients receiving an allograft had gynaecomastia, Leydig cell insufficiency (LCI) diminished libido and erectile dysfunction. Surgery was required in one case, while in two cases the gynaecomastia resolved spontaneously after 6 months. Two patients also had gynaecomastia and sexual dysfunction, severe hypogonadism, very low testosterone levels and marked hyperprolactinaemia following autoBMT. Both responded well to testosterone replacement therapy (TRT). As a group, all patients had primary testicular failure and all except one, had LCI (compensated or frank). However, there was no correlation between the severity of gynaecomastia and the degree of endocrine dysfunction. This preliminary study is the first to suggest that gynaecomastia, due to primary hypogonadism and LCI, may be a significant complication of myeloablative conditioning therapy. Therefore gynaecomastia in BMT recipients must always be treated as a pathological entity as it may be the external manifestation of a complex endocrine pathology. It is a potentially treatable condition. Although spontaneously reversible, some patients may require TRT or even surgery. We recommend comprehensive endocrine testing in conjunction with a reproductive endocrinologist and prompt intervention to alleviate embarrassment and anxiety in afflicted BMT recipients.

Adult↗
PubMed2001

EVI1 expression in acute myeloid leukaemia.

Acute myeloid leukaemia (AML) with 3q26 cytogenetic abnormalities is associated with overexpression of EVI1, dysmegakaryopoiesis and poor prognosis. Screening for EVI1 transcripts was performed in 336 cases of AML, including 139 patients with acute promyelocytic leukaemia (APL). Expression was detected in 7 out of 10 cases with and 23 out of 326 without 3q26 abnormalities including one APL case. Among cases lacking 3q abnormalities, detection of EVI1 transcripts was neither associated with characteristic dysmegakaryopoietic features, nor predictive of a poor outcome, indicating that screening will probably not assist in treatment stratification. This study nevertheless demonstrates that deregulation of EVI1, although rare in APL, is a relatively frequent event in AML.

Acute Disease↗
PubMed2001

In vivo CAMPATH-1H prevents GvHD following nonmyeloablative stem-cell transplantation.

BACKGROUND: We have investigated a novel nonmyeloablative conditioning regimen in 44 patients with hematological malignancies. The median patient age was 41 years. Many of the patients had high-risk features, including 19 patients with a previous failed transplant. METHODS: Recipient conditioning consisted of CAMPATH-1H 20 mg/day on Days -8 to -4, fludarabine 30 mg/m(2) on Days -7 to -3 and melphalan 140 mg/m(2) on Day -2. Thirty-six recipients received unmanipulated G-CSF mobilized PBSC from HLA identical siblings and eight received unmanipulated BM from MUD. GvHD prophylaxis was with CYA alone for 38 patients and CYA plus MTX for six sibling recipients. RESULTS: Forty-two of the 43 evaluable patients had sustained engraftment. Results of chimerism analysis using microsatellite PCR indicate that 18 of 31 patients studied were full donor chimeras, while the other patients were mixed chimeras in one or more lineages. At a median follow-up of 9 months (range, 3-29 months) 33 patients remain alive in CR, or with no evidence of disease progression. Seven patients relapsed or progressed post-transplant and four of them subsequently died. Four patients died from regimen-related complications. There were no cases of Grades III-IV acute GvHD. Only two patients developed Grade II acute GvHD and only one had chronic GvHD. The estimated probability of non-relapse mortality at 1 year was 11%.Results: Although longer follow-up is needed to establish the long-term remission rates, this study demonstrates that this nonmyeloablative preparative regimen is associated with durable engraftment, minimal toxicity and low incidence of GvHD.

Adolescent↗
PubMed2000

In vivo CAMPATH-1H prevents graft-versus-host disease following nonmyeloablative stem cell transplantation.

A novel nonmyeloablative conditioning regimen was investigated in 44 patients with hematologic malignancies. The median patient age was 41 years. Many of the patients had high-risk features, including 19 patients with a previous failed transplant. Recipient conditioning consisted of CAMPATH-1H, 20 mg/day on days -8 to -4; fludarabine, 30 mg/m(2) on days -7 to -3; and melphalan, 140 mg/m(2) on day -2. Thirty-six recipients received unmanipulated granculocyte colony-stimulating factor-mobilized peripheral blood stem cells from HLA-identical siblings, and 8 received unmanipulated marrow from matched unrelated donors. GVHD prophylaxis was with cyclosporine A alone for 38 patients and cyclosporine A plus methotrexate for 6 sibling recipients. Forty-two of the 43 evaluable patients had sustained engraftment. Results of chimerism analysis using microsatellite polymerase chain reaction indicate that 18 of 31 patients studied were full-donor chimeras while the other patients were mixed chimeras in one or more lineages. At a median follow-up of 9 months (range 3 to 29 months), 33 patients remain alive in complete remission or with no evidence of disease progression. Seven patients relapsed or progressed post-transplantation, and 4 of them subsequently died. Four patients died of regimen-related complications. There were no cases of grades III-IV acute GVHD. Only 2 patients developed grade II acute GVHD, and only 1 had chronic GVHD. The estimated probability of nonrelapse mortality was 11%. Although longer follow-up is needed to establish the long-term remission rates, this study demonstrates that this nonmyeloablative preparative regimen is associated with durable engraftment, minimal toxicity, and low incidence of GVHD.

Adolescent↗
PubMed2000

Effect of changes in expression of the amphotropic retroviral receptor PiT-2 on transduction efficiency and viral titer: implications for gene therapy.

The aim of this study was to quantify the impact of amphotropic retroviral receptor (PiT-2) levels on susceptibility to transduction and to determine whether the low level of PiT-2 found on CD34+ hematopoietic cells is within the range likely to compromise gene transfer. Receptor-deficient Chinese hamster ovary (CHO) cells were transfected with a PiT-2 construct that could be induced by the removal of tetracycline. The level of PiT-2 expression measured by virus binding in uninduced and in fully and partially induced transfectants correlated with the efficiency of transduction by an amphotropic retroviral reporter vector. Fully induced CHO-PiT-2 cells gave apparent viral titers similar to NIH 3T3 fibroblasts while addition of tetracycline reduced titers by up to 140-fold. Binding of the same vector preparation to purified CD34+ peripheral blood stem cells (PBSCs) was always less than to uninduced CHO-PiT-2 transfectants even after preincubation in 10-ng/ml concentrations of IL-3, IL-6, and stem cell factor, which increased retroviral binding by an average of 35%. The level of expression of the amphotropic retroviral receptor PiT-2 thus significantly limits transduction efficiency within the range observed in target cells of importance in human gene therapy.

3T3 Cells↗
PubMed2000

Monocyte-derived dendritic cells do not proliferate and are not susceptible to retroviral transduction.

Dendritic cells may be generated ex vivo from CD34+ progenitor cells or peripheral blood mononuclear cells. Initial reports suggested that monocyte-derived dendritic cells (MoDCs) arise from a proliferating precursor and several groups subsequently reported successful retroviral transduction of these cells, again implying that cell division occurs. As this is of importance in the development of immunotherapy protocols, we investigated whether monocytes proliferate as they differentiate into MoDCs and also their susceptibility to retroviral transduction. During MoDC differentiation, there was a 51 +/- 12% reduction in cell number, 98% of cells were in G0/G1, no DNA synthesis was detectable and the cell cycle regulatory proteins pRb and p130 were in the hypophosphorylated forms observed in non-cycling cells. As expected from these results, MoDCs were refractory to transduction with a GALV1 pseudotyped Moloney murine leukaemia virus (MoMLV)-based retroviral vector. In contrast, generation of DCs from purified CD34 progenitors was accompanied by rapid entry into the cell cycle and a 41.1-fold cell expansion at the end of 14 d culture.

Antigens, CD34↗
PubMed2000

Dynamics of telomere shortening in neutrophils and T lymphocytes during ageing and the relationship to skewed X chromosome inactivation patterns.

Human haemopoiesis undergoes profound changes throughout life, resulting in compromised regenerative capacity of haemopoietic stem cells. It has been suggested that telomere shortening results in senescence of haemopoietic stem cell subsets and may influence the balance between stem cell renewal and proliferation. Telomere length and telomerase activity was measured in whole blood leucocytes, neutrophils and T cells from cord blood and individuals aged from 1 year to 96 years. Rapid telomere shortening [700 base pairs (bp)] was demonstrated in the first year of life, followed by a gradual decline of 31 bp/year. T cells were shown to have longer telomeres than neutrophils (mean difference 372 bp, P = < 0.001) but demonstrated similar rates of shortening (20 +/- 0.3 bp/year vs. 22 +/- 0.3 bp/year). Telomerase was detectable in T cells but not in neutrophils, suggesting that telomerase is not the rate-limiting step for regulation of telomere length in haemopoietic cells. Stem cell utilization as measured by X chromosome inactivation patterns was found to be independent of telomere length. This supports the concept that age-dependent skewed haemopoiesis is the result of random stem cell loss or X-allelic exclusion rather than telomeric senescence. These studies provide insight into the ageing process and a reference point for evaluating replicative stress in individuals of different age groups.

Adolescent↗
PubMed2000

Remobilization of patients who fail to achieve minimal progenitor thresholds at the first attempt is clinically worthwhile.

A significant proportion of previously treated patients fail to mobilize sufficient stem/progenitor cells to enable high-dose therapy and peripheral blood stem cell transplantation to be performed. In this study, the value of remobilizing such patients has been evaluated in 20 patients who all failed to achieve progenitor yields of 1 x 10(6)/kg CD34+ cells and 1 x 10(5)/kg granulocyte-monocyte colony-forming units (GM-CFCs) at the first attempt. Most patients remained relatively poor mobilizers at the second mobilization, but the yield of CD34+ cells and GM-CFCs on the first apheresis was significantly greater with the second mobilization than the first. A total yield (all aphereses from both mobilizations) of > 1 x 10(6)/kg CD34+ cells and > 1 x 10(5)/kg GM-CFCs was achieved in 14 out of 20 patients. Seven patients have received high-dose therapy with stem cell infusion; neutrophil recovery was rapid in all patients and platelet independence occurred in < 21 d in five out of seven patients. We conclude that remobilization is worth considering in those patients in whom a chemotherapy-free interval of several months is possible.

Blood Component Removal↗
PubMed2000

ESHAP and G-CSF is a superior blood stem cell mobilizing regimen compared to cyclophosphamide 1.5 g m(-2) and G-CSF for pre-treated lymphoma patients: a matched pairs analysis of 78 patients.

Cyclophosphamide 1.5 g m(-2) followed by granulocyte colony-stimulating factor (G-CSF) is an effective peripheral blood stem cell (PBSC) mobilizing regimen, but has limited anti-lymphoma activity. We therefore assessed the mobilizing potential of ESHAP (etoposide, ara-C, methylprednisolone and cisplatin), a potent second-line lymphoma regimen followed by G-CSF. The results were compared in 78 patients with relapsed or resistant lymphomas with the use of cyclophosphamide 1.5 g m(-2) followed by G-CSF in a matched pairs analysis, matching the ESHAP recipients (for predetermined prognostic factors) from a cohort of 178 lymphoma patients mobilized with cyclophosphamide and G-CSF. The total numbers of mononuclear cells collected at apheresis was similar with both regimens but ESHAP plus G-CSF resulted in a significantly higher percentage of CD34+ cells, absolute number of CD34+ cells and GM-CFC (all with P-values < 0.001). The number of patients requiring only one apheresis harvest to achieve a CD34+ cell yield of > 2.0 x 10(6) kg(-1) was greatly increased in the ESHAP recipients (56/78 vs 17/78, P < 0.001). The total number of progenitor cells collected was not significantly different with the two mobilization regimens because of this higher number of apheresis in the cyclophosphamide group. The proportion of patients who failed to achieve a minimum CD34+ cell target of 1 x 10(6) kg(-1) with the pooled harvests was less in the ESHAP arm (four patients vs nine patients) despite an increased number of aphereses in the cyclophosphamide recipients. ESHAP plus G-CSF is well tolerated and is an excellent mobilization regimen in patients with pre treated lymphoma.

Adult↗
PubMed2000

A clinically applicable method for the ex vivo generation of antigen-presenting cells from CD34+ progenitors.

BACKGROUND AND OBJECTIVES: Dendritic cells (DCs), the most potent of antigen-presenting cells, can be generated in vitro from bone marrow or blood progenitor cells. We have developed a method for producing such cells from mobilised peripheral blood CD34+ cells in the absence of bovine products. METHODS: The culture system developed used X-Vivo 10 culture medium with 10% autologous serum, rhGM-CSF, rhTNF-alpha and rhIL-4. Large-scale cultures were performed in Stericell 12 inch x 15 inch culture bags. RESULTS: In 12-small-scale experiments, over 14 days, there was a median 38-fold increase in cell numbers of which 12.8% were DCs as defined by immunophenotyping. These cells had potent DC activity in functional assays. In two clinical-scale experiments, a 5.7- and 10-fold expansion of total cell numbers was obtained, with 8.2 and 18% of the final population being DCs, respectively. CONCLUSION: This system is suitable for clinical application.

Animals↗
PubMed2000

Risk of second malignancy after Hodgkin's disease in a collaborative British cohort: the relation to age at treatment.

PURPOSE: To assess long-term site-specific risks of second malignancy after Hodgkin's disease in relation to age at treatment and other factors. PATIENTS AND METHODS: A cohort of 5,519 British patients with Hodgkin's disease treated during 1963 through 1993 was assembled and followed-up for second malignancy and mortality. Follow-up was 97% complete. RESULTS: Three hundred twenty-two second malignancies occurred. Relative risks of gastrointestinal, lung, breast, and bone and soft tissue cancers, and of leukemia, increased significantly with younger age at first treatment. Absolute excess risks and cumulative risks of solid cancers and leukemia, however, were greater at older ages than at younger ages. Gastrointestinal cancer risk was greatest after mixed-modality treatment (relative risk [RR] = 3.3; 95% confidence interval [CI], 2.1 to 4.8); lung cancer risks were significantly increased after chemotherapy (RR = 3. 3; 95% CI, 2.4 to 4.7), mixed-modality treatment (RR = 4.3; 95% CI, 2.9 to 6.2), and radiotherapy (RR = 2.9; 95% CI, 1.9 to 4.1); breast cancer risk was increased only after radiotherapy without chemotherapy (RR = 2.5; 95% CI, 1.4 to 4.0); and leukemia risk was significantly increased after chemotherapy (RR = 31.6; 95% CI, 19.7 to 47.6) and mixed-modality treatment (RR = 38.1; 95% CI, 24.6 to 55. 9). These risks were generally greater after treatment at younger ages: for patients treated at ages younger than 25 years, there were RRs of 18.7 (95% CI, 5.8 to 43.5) for gastrointestinal cancer after mixed-modality treatment, 14.4 (95% CI, 5.7 to 29.3) for breast cancer after radiotherapy, and 85.2 (95% CI, 45.3 to 145.7) for leukemia after chemotherapy (with or without radiotherapy). CONCLUSION: Age at treatment has a major effect on risk of second malignancy after Hodgkin's disease. Although absolute excess risks are greater for older patients, RRs of several important malignancies are much greater for patients who are treated when young. The increased risk of gastrointestinal cancers may relate particularly to mixed-modality treatment, and that of lung cancer to chemotherapy as well as radiotherapy; there are also well-known increased risks of breast cancer from radiotherapy and leukemia from chemotherapy. The roles of specific chemotherapeutic agents in the etiology of solid cancers after Hodgkin's disease require detailed investigation.

Adolescent↗
PubMed2000

A randomized British National Lymphoma Investigation trial of CHOP vs. a weekly multi-agent regimen (PACEBOM) in patients with histologically aggressive non-Hodgkin's lymphoma.

BACKGROUND: Between 1987 and 1991, the British National Lymphoma Investigation randomized 459 patients with non-Hodgkin's lymphoma with a large-cell component to either CHOP or the PACEBOM regimen. PATIENTS AND METHODS: Four hundred fifty-nine eligible patients were included in this trial, four hundred one with diffuse large-cell lymphoma and fifty-eight with diffuse mixed-cell lymphoma according to the Working Formulation. Two hundred twenty-six patients were randomized to receive CHOP and two hundred thirty-three to receive PACEBOM. The two arms of the trial were well balanced for all potential prognostic factors. RESULTS: The complete remission rate with PACEBOM was 64% and with CHOP 57% (NS). At eight years, the actuarial cause specific survival (CSS) in the PACEBOM arm is 59% compared to 49% in the CHOP arm (P = 0.09). Patients < 50 years of age fared significantly better in the PACEBOM arm both for CSS and overall survival (P = 0.002) and the CSS was also significantly improved in stage IV disease (P = 0.02). CONCLUSIONS: The mature data from this trial suggest that an etoposide-containing multi-agent weekly regimen can be superior to CHOP.

Adolescent↗