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Biomedical subjects

D C Linch

Publications and source records attributed to D C Linch.

At least 127 records · Page 7Linked to original sources
PubMed1994

Differentiation-linked changes in tyrosine phosphorylation, functional activity, and gene expression downstream from the granulocyte-macrophage colony-stimulating factor receptor.

The HL-60 model of myeloid maturation was used to test whether changes in signaling from the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor accompany maturation-related changes in cellular responses to GM-CSF. Receptor expression, tyrosine phosphorylation, functional activity, and c-fos gene expression were measured. Functional GM-CSF receptors were present throughout differentiation as both uninduced and dimethyl sulfoxide (DMSO)-induced HL-60 cells responded to GM-CSF, albeit in different ways. Uninduced promyelocytes proliferated in response to GM-CSF, whereas DMSO-induced cells lost the capacity to proliferate but did respond with increased expression of beta 2-integrins, enhanced respiratory burst activity, and metabolism of arachidonic acid. GM-CSF-stimulated upregulation of c-fos mRNA expression was not detected in immature cells but developed after 2 to 4 days with DMSO in line with a marked increase in responsiveness to stimulation with phorbol ester, showing that increased expression of c-fos is predominantly a feature of mature phagocytes. GM-CSF stimulated the tyrosine phosphorylation of a broadly similar range of proteins in both uninduced and DMSO-treated HL-60 cells, but protein bands were more heavily phosphorylated in DMSO-induced cells. Phosphorylation was rapid in onset and very transient in immature cells. Phosphorylation of several proteins, in particular a 130-kD band, was more sustained in DMSO-induced cells. These differences in signaling were not because of numerical differences in receptors, because reduction of GM-CSF concentration to trigger equivalent numbers of high-affinity receptors delayed the onset of phosphorylation in DMSO-induced cells. We conclude that there are maturation-related changes in signaling downstream from the GM-CSF receptor.

Arachidonic Acid↗
PubMed1994

Tissue specificity of X-chromosome inactivation patterns.

The analysis of X-chromosome inactivation patterns has been used in a number of clinical situations such as the identification of carrier status in X-linked genetic disorders and the establishment of the monoclonal origin of tumors. Interpretation of the result obtained requires comparison with the constitutive pattern for the individual, and for hematopoietic malignancies, skin biopsies or cultured fibroblasts have often been used as the control tissue because normal cells of the same lineage as the malignancy are not generally available. However, this assumes that patterns in the different tissues are constitutionally the same. We have therefore compared X-chromosome inactivation patterns from peripheral blood (granulocytes, E- cells, and T cells), skin, and muscle from 20 hematologically normal females, and colonic mucosa from 9 individuals. In 11 patients (55%), the results obtained were similar for all tissues of an individual, but in 9 patients, significant differences were observed between tissues. The most consistent feature was a skewing in peripheral blood (> 75% expression of one allele) but not skin and/or muscle. These studies suggest that skin cannot be used as a control tissue for the interpretation of X-chromosome inactivation patterns in hematopoietic cells.

Adolescent↗
PubMed1994

Placebo-controlled phase III trial of lenograstim in bone-marrow transplantation.

Haemopoietic growth factors are accepted as accelerating haemopoietic recovery after bone-marrow grafting, yet no large randomised trials have been published that convincingly show benefit. Lenograstim (glycosylated recombinant human granulocyte colony-stimulating factor) was given to 315 patients after bone-marrow transplantation in a prospective randomised placebo-controlled multicentre trial. 1 day after bone-marrow infusion, 163 patients received lenograstim 5 micrograms/kg per day by 30-min infusion, and 152 patients received placebo daily for 28 days or until neutrophil recovery. 137 patients had lymphoma, 35 myeloma, 85 acute lymphoblastic leukaemia, and 58 a solid tumour. Patients were stratified by age and by type of bone-marrow transplantation (BMT). Neutrophil recovery to above 10(9)/L for 3 consecutive days was seen earlier in lenograstim-treated patients (16 vs 27 days, p < 0.001). Time to neutrophil recovery above 0.5 x 10(9)/L was reduced (14 vs 20 days, p < 0.001). The difference was significant both in autograft (20 vs 14 days, p < 0.001) and allograft (20 vs 14 days, p < 0.01) patients, in children (20 vs 13 days, p < 0.001), and adults. Lenograstim-treated patients had fewer days of infection, and of antibiotic administration, and also spent less time in hospital. However, clinical and microbiological sepsis was similar in both groups. There was no significant toxicity ascribed to lenograstim. Survival was the same at days 100 and 365. In patients undergoing autologous or allogeneic BMT for neoplastic disease, lenograstim significantly reduced duration of neutropenia and led to earlier hospital discharge.

Adjuvants, Immunologic↗
PubMed1994

Clinical stage 1 non-Hodgkin's lymphoma: long-term follow-up of patients treated by the British National Lymphoma Investigation with radiotherapy alone as initial therapy.

A retrospective analysis was performed of 451 adult patients with clinical stage 1/1E non-Hodgkin's lymphoma treated initially with radiotherapy alone. Histopathologically 208 patients had low-grade disease and 243 patients high-grade disease. The complete remission (CR) rate was higher in patients with low-grade disease (98%) than in those with high-grade disease (84%) (P < 0.0001). The relapse rate was similar in both histological categories, and relapse usually occurred within 5 years. The resulting overall actuarial percentage of patients achieving CR and remaining disease free (at 10 years) was 47% in patients with low-grade disease and 45% for those with high-grade disease. Salvage therapy was frequently successful in younger patients, and the overall cause-specific survival at 10 years was 71% for low-grade disease and 67% for high-grade disease. In those patients under 60 years of age at diagnosis, the overall cause-specific survival at 10 years was 84% and 80% for those with low-grade and high-grade disease respectively. These long-term results in young patients with clinical stage 1 disease are encouraging, and it will be difficult to demonstrate improved survival with initial chemotherapy either with or without radiotherapy, until new prognostic factors are found to identify poor-risk patients.

Adult↗
PubMed1994

Hybrid LOPP/EVA is not better than LOPP alternating with EVAP: a prematurely terminated British National Lymphoma Investigation randomized trial.

In a British National Lymphoma Investigation (BNLI) trial, patients with advanced Hodgkin's disease (stages IB, IIB, III, and IV) were randomized between initial treatment with a LOPP alternating with EVAP regimen and a LOPP/EVA hybrid regimen. The two regimens contained identical drug dosages and varied only in their scheduling. The complete remission (CR) rate in the hybrid regimen was significantly less than that in the alternating regimen, and the trial was terminated after approximately 18 months since there appeared to be no chance of the hybrid regimen ever proving superior to the alternating regimen. A total of 160 patients were entered into the trial before recruitment was terminated, 86 being randomized to the alternating regimen and 83 to the hybrid regimen. The CR rates for the alternating and hybrid arms were 65% and 40%, respectively (p < 0.002). The CR relapse-free survivals at 2 years in these two arms were 85% and 79%, respectively (p = 0.7); the overall disease-free survivals at 2 years were 57% and 32%; and the overall survivals at 2 years were 88% and 78% (p = 0.5). This trial emphasizes the impact of drug scheduling, which should be taken into account in the design of future hybrid regimens.

Adolescent↗
PubMed1994

Late mortality in young BNLI patients cured of Hodgkin's disease.

A retrospective analysis was made of 1057 young patients (aged 15-29) with Hodgkin's disease (HD) who were entered into British National Lymphoma Investigation (BNLI) trials and studies between 1970 and 1992, and who had attained complete remission and remained disease-free thereafter from either their first-line (n = 774) or second-line (n = 283) treatment. Overall survivals at 20 years for those remaining disease-free from first-line and second-line treatment were 93% and 84%, respectively, compared to a survival of approximately 98.5% in the general population. In young patients cured by modern first-line therapeutic techniques, long-term survival should in future be only a little below that expected in the general population, and the emphasis of future trials should be directed towards the improvement of the efficacy of first-line treatment.

Adolescent↗
PubMed1994

Liposomal amphotericin B in the treatment of fungal infections in neutropenic patients: a single-centre experience of 133 episodes in 116 patients.

Liposomal amphotericin B (AmBisome) was used for suspected or confirmed fungal infection complicating 133 neutropenic episodes in 116 patients not tolerating, or not responding to, conventional amphotericin. Adverse effects were infrequent and no significant renal impairment resulted. Acute reactions occurred in five patients, reversible hepatic dysfunction in 23, and hypernatraemia in 17. The putative mycosis resolved with AmBisome treatment in 81 episodes (61%) and progressed with fatal outcome in 25 (19%), but the diagnosis was equivocal in most, and in 27 episodes (20%) evidence indicating nonfungal pathogenesis emerged. Treatment efficacy is, however, evaluable in those with proven aspergillosis. 13/17 patients with confirmed invasive aspergillosis responded to AmBisome (77%), conventional amphotericin having failed in 11. Treatment was successfully discontinued when the neutrophil count was < 1 x 10(9)/l in eight responders (61%). In four further patients treated for suspected aspergillosis, disseminated infection was documented at post-mortem, but the true incidence is unknown. This analysis confirms that AmBisome is well tolerated and effective against invasive mycoses in neutropenic patients, and may salvage patients when conventional amphotericin proves excessively toxic or ineffective.

Adolescent↗
PubMed1994

Interleukin-3 administration enhances human monocyte function in vivo.

In addition to its haemopoietic effects, interleukin-3 (IL-3) enhances leucocyte function in vitro. In this study we examined the effects on haematological variables and monocyte function of a single IL-3 infusion in five haematologically normal individuals. There was a rapid fall in circulating monocyte (to 24 +/- 6% of pre-infusion value) and eosinophil numbers (to 3 +/- 2%) with a nadir at 30 min and gradual return to baseline over 6 h. No significant changes in monocyte expression of the adhesion molecules CD11b or L-selectin or of monocyte respiratory burst activity were detected. There was a significant increase in monocyte phagocytosis and killing of Candida after IL-3 infusion: the percentage of monocytes which had ingested Candida increased from 39 +/- 10% to 62 +/- 12% and the total number of Candida killed per 100 monocytes increased from 63 +/- 34 to 210 +/- 59 (P < 0.05 and P < 0.01 respectively). There was no inhibition of neutrophil migration into a 'skin window' site and monocyte migration was moderately enhanced (peak increase of 260 +/- 47%). These results show that IL-3 has significant effects on monocyte function in vivo and could be of use in augmenting host defence mechanisms in immunocompromised patients.

CD11 Antigens↗
PubMed1994

The effects of gestation on circulating progenitor cells.

The frequency of BFU-E in second-trimester fetal blood (484 +/- 104/10(5)) falls progressively during gestation to a value of 69 +/- 41/10(5) in cord bloods of 36 weeks gestation and beyond, but this is still significantly greater than adult blood values of 14 +/- 8 (P < 0.01). BFU-E obtained from unfractionated peripheral blood mononuclear cells from fetuses/neonates less than 36 weeks gestation were more sensitive to erythropoietin than adult BFU-E, but the sensitivity of highly purified BFU-E obtained from second-trimester fetal liver was similar to that in adult cells. Almost maximal growth of BFU-E from purified fetal progenitor cells could be achieved with erythropoietin alone, whereas adult cells required the presence of other factors with 'burst-promoting activity'.

Cell Division↗
PubMed1994

Detection and significance of bone marrow infiltration at the time of autologous bone marrow transplantation in Hodgkin's disease.

Bilateral iliac crest biopsies were performed at the time of bone marrow (BM) harvest in patients with poor-risk Hodgkin's disease (HD) undergoing autologous bone marrow transplantation (ABMT). 67 consecutive patients with normal trephine biopsies (58 unilateral; nine bilateral) taken 2 weeks prior to harvest were studied. Nine (13%) of patients had BM infiltration with HD on the harvest biopsies. These patients had all previously had only unilateral biopsies. Three patients did not proceed to ABMT because disease progression became clinically apparent, but the remaining six patients were infused with involved marrow. One patient died 6 weeks post ABMT, with no evidence of disease at post-mortem. One patient showed no response to ABMT and four patients either had a partial or complete response to ABMT. Of the responders, three patients are now in complete remission at 53, 39 and 33 months past ABMT.

Adolescent↗
PubMed1994

Development of a simplified single-apheresis approach for peripheral-blood progenitor-cell transplantation in previously treated patients with lymphoma.

PURPOSE: The aims of this study were to develop a simplified, safe, and cost-effective peripheral-blood progenitor-cell (PBPC) mobilization protocol. PATIENTS AND METHODS: Twenty-six patients with relapsed or resistant lymphomas were entered onto a sequential cohort study in which schedules of various granulocyte colony-stimulating factor (G-CSF) were administered after cyclophosphamide 1.5 g/m2. Hematologic recovery after high-dose carmustine (BCNU) etoposide, cytarabine, and melphalan (BEAM) chemotherapy was compared with that of 46 patients who received autologous bone marrow transplantation (ABMT) without growth factors and 28 patients who received ABMT followed by G-CSF. RESULTS: When G-CSF (10 micrograms/kg/d) was administered from the day after the cyclophosphamide, neutropenia developed on day 8 followed by an abrupt increase in the WBC count. The optimal time for PBPC harvesting was the day on which the postnadir WBC count was greater than 8.0 x 10(9)/L, as shown by CD34+ cell counts and granulocytic-macrophage colony-forming cell (GM-CFC) assays. The reproducibility of the response was such that routine monitoring of CD34+ cell counts and GM-CFC was not necessary. A single leukapheresis on this day was adequate for prompt hematologic engraftment, and posttransplant G-CSF made little further impact on the rapid recovery. Compared with both control groups, the use of PBPC led to more rapid neutrophil recovery, markedly accelerated platelet recovery, less use of antimicrobial agents and parenteral nutrition, and more than 10 days earlier discharge from hospital. All of these differences were highly significant (P < .01). CONCLUSION: A simplified mobilization protocol is described that requires only one apheresis to achieve rapid hematologic engraftment.

Adult↗
PubMed1994

The effects of recombinant human granulocyte-macrophage colony stimulating factor on the neutrophil respiratory burst in the term and preterm infant when studied in whole blood.

To investigate further the susceptibility to infection of newborn infants, particularly those born prematurely, we have used a "whole blood" flow cytometric assay to compare the respiratory burst activity in recombinant human granulocyte-macrophage colony stimulating factor "primed" neutrophils obtained from healthy adults, term infants, and preterm newborn infants. The use of whole blood avoids prior cell separation procedures that may cause artifactual activation or priming. In healthy adults (n = 21), the bacterial cell wall peptide N-formyl-methionyl-leucyl-phenylalanine induced little neutrophil respiratory burst activity, suggesting that the circulating cell is relatively quiescent. Prior exposure to recombinant human granulocyte-macrophage colony stimulating factor augmented the median N-formyl-methionyl-leucyl-phenylalanine response by 425%. In cord blood from full-term neonates (n = 9), recombinant human granulocyte-macrophage colony stimulating factor produced less enhancement of the N-formyl-methionyl-leucyl-phenylalanine response (345%), but the absolute level of respiratory burst activity was at least as great as in adults, suggesting that the neutrophils are fully functional and partially primed after delivery. In preterm infants receiving intensive care (n = 10), the degree of priming was similar to that in neutrophils from term infants (344%), although the absolute level of respiratory burst activity was reduced (p = 0.0003). In response to stimulation with phorbol ester, 73.5% (18-99%) (median and range) of neutrophils obtained from adults and 77.6% (50-92%) from term babies exhibit respiratory burst activity detectable in the whole blood assay. However, in neutrophils obtained from preterm infants, there was a significant reduction in the phorbol ester-induced respiratory burst, with only 32.9% (21-61%) of cells responding (p = 0.0129).

Adult↗
PubMed1994

Analysis of mutations in the GM-CSF receptor alpha coding sequence in patients with acute myeloid leukaemia and haematologically normal individuals by RT-PCR-SSCP.

Mutations of signal transducing molecules such as Ras have been shown to confer a growth advantage in leukaemic blasts and contribute to the pathogenesis of the disease. Alterations of signal transducing molecules other than Ras may play a role in leukaemogenesis. Knowledge of such mutations could also further our understanding of the normal signalling processes. We have therefore studied the coding sequence of the GM-CSF receptor alpha chain (GM-CSFR alpha) in patients with acute myeloid leukaemia (AML) and non-AML controls using single strand conformation polymorphism (SSCP) analysis. Abnormalities were detected in 4/32 AML patients (13%) and 2/15 non-AML controls (13%). Direct sequencing of PCR products revealed five different base substitutions. Three were conservative, two caused amino acid changes. The base substitution leading to amino acid change alanine to glycine at position 17 was found in both an AML patient and a control. It lies in the signal sequence and does not affect the mature protein. The other base change altering arginine to glutamine at position 164 is unlikely to influence the receptor structure as this structural position in the chain is not well conserved in members of the cytokine receptor family. Both amino acid changes were constitutive alterations as they could be demonstrated in the patients' children. The base changes described in the AML patients thus represent polymorphisms and do not contribute to the pathogenesis of AML.

Adolescent↗
PubMed1994

Evaluation of haematopoietic growth factors: defining relevant clinical endpoints in growth factor trials.

Initial evaluation of the therapeutic efficacy of haemopoietic growth factors involves assessment of their effects on the blood count, in various clinical situations. However, hard clinical data are also needed. Microbiologically documented infection is the ideal parameter but is difficult to measure. Consequently, the surrogate parameters of duration of fever and antibiotic usage are used instead. Febrile neutropenia is not a clinical endpoint, but merely a useful indicator to begin antibiotic therapy. To date, cost evaluations of growth factor use have relied on retrospective analyses of relevant clinical data including antibiotic usage, parenteral nutrition requirements, and duration of hospitalisation. Growth factors can reduce all these parameters in selected situations. Clinical data also suggest that growth factors facilitate chemotherapy dose optimisation and intensification, although the degree of intensification appears limited (20-40%). Currently, it is unclear whether such therapy confers benefit in terms of remission rates and survival.

Antineoplastic Agents↗