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M J Pippard

Publications and source records attributed to M J Pippard.

At least 19 recordsLinked to original sources
PubMed2002

Functional disturbance of marrow stromal microenvironment in the myelodysplastic syndromes.

The potential contribution of abnormal marrow stromal function to ineffective haemopoiesis in the myelodysplastic syndromes is unclear. We have compared the ability of stromal layers from normal (n = 7) and myelodysplastic (n = 9) marrow to alter proliferation and survival of the granulocyte-macrophage colony-stimulating factor/interleukin-3-dependent cell line F-36P. Co-cultures for 72 h in the absence of exogenous cytokines were either in direct contact with stroma or separated by transwell inserts. On normal stromal layers, the ratio of adherent F-36P cells relative to stromal cells increased from a mean of 0.2 +/- 0.01 (s.d.) at 4 h of co-culture to 0.34 +/- 0.08 after 72 h (n = 7). Corresponding values on myelodysplastic stroma (0.2 +/- 0.02 at 4 h and 0.35 +/- 0.05 at 72 h; n = 9) indicated that the ability of myelodysplastic stromal layers to regulate short-term proliferation of F-36P cells may be similar to normal. Apoptosis of F-36P cells was quantified after co-culture with normal or myelodysplastic stroma: results from myelodysplastic co-cultures were standardized as a fraction of values from co-cultures with paired normal stroma (apoptotic ratio). Augmented apoptosis of F-36P cells was detected in 8/9 co-cultures with myelodysplastic stroma (mean = 15.7 +/- 9.7%, n = 9), compared with corresponding normal stroma (mean = 12.4 +/- 4.6%, n = 7, P < 0.05) with a mean apoptotic ratio of 1.4 +/- 0.5 (P < 0.05). There was no correlation between stroma-related apoptosis and FAB type, tumour necrosis factor-alpha concentrations in the culture supernatant or numbers of stromal macrophages, and no evidence of involvement of the Fas pathway. Increased apoptosis was detected in cells grown in transwell inserts over stroma (23.8 +/- 3%, n = 5) compared to adherent cells in cultures with normal stromal layers, but this survival difference was not observed in co-cultures with myelodysplastic stroma. These results suggest that abnormal stromal function in patients with myelodysplastic syndromes may contribute to increased apoptosis of haemopoietic cells within the marrow microenvironment. The effect appears to be dependent on close cellular contact, rather than the release of soluble factors, but the exact mechanism remains unclear.

Aged↗
PubMed2001

Timing of the appearance of multipotential and committed haemopoietic progenitors in peripheral blood after mobilization in patients with lymphoma.

The pattern of emergence of multipotential (CFU-A) and committed (CFU-GM and BFU-E) progenitor cells in peripheral blood has been examined in patients with Hodgkin's disease and non-Hodgkin's lymphoma. Mobilization protocols used chemotherapy with or without granulocyte colony-stimulating factor (n=8 and n=5, respectively). In all patients, the numbers of CFU-A, CFU-GM and BFU-E peaked simultaneously, rather than sequentially, suggesting that marrow regeneration after these mobilization protocols occurred from progenitors at all stages of differentiation. We conclude that peripheral blood stem cell harvest strategies based on peak values for total progenitor numbers will also capture maximum numbers of multipotential progenitors. However, the variable relationship between CFU-A and CFU-GM numbers suggests that overall progenitor cell numbers can give only a broad estimate of the absolute numbers of multipotential progenitors in an individual harvest.

Adult↗
PubMed2001

Assessment of stromal function, and its potential contribution to deregulation of hematopoiesis in the myelodysplastic syndromes.

BACKGROUND AND OBJECTIVES: The regulation of hematopoiesis by marrow stroma in vitro, has been shown to be abnormal in some patients with myelodysplastic syndromes (MDS). This study was performed to assess whether a range of mechanisms may be altered within the MDS microenvironment. DESIGN AND METHODS: The effects of diffusible factors produced by normal or MDS stromal layers on hematopoietic cells were studied by comparing the ability of media conditioned (CM) by normal or MDS stroma to regulate migration of target normal marrow CD34+ cells across 5 microm transmembranes. The ability of CM to stimulate hematopoietic cells was also assessed: changes in membrane polarity of KG-1a cells on exposure to stroma CM were compared. Subsequently, contact-mediated interactions between normal marrow CD34+ cells and normal and MDS stroma were studied: survival of allogeneic normal marrow CD34+ cells on live and glutaraldehyde-fixed normal and myelodysplastic stroma after 24h of co-culture was measured using 7-aminoactinomycin D staining. To determine whether hematopoietic cell survival on normal and MDS stroma was related to oxidative stress within the stromal microenvironment, intracellular superoxide levels, both constitutively and induced by tumor necrosis factor-a were measured within live stromal cells by FACScan analysis of ethidium bromide stained cells. RESULTS: The ability of CM from normal and MDS stroma to regulate short-term migration and activation of hematopoietic cells was similar. The mean percentage of apoptotic CD34+ cells (13+/-11%) adherent to glutaraldehyde-fixed myelodysplastic stroma was higher than on paired fixed normal stroma (11+/-10%) (n=6, p=0.056). Constitutive mean levels of superoxide in myelodysplastic cultures (9.5+/-2.1) were greater than in normal stromal cultures (4.9+/-0.6; n=6). However, following treatment with tumor necrosis factor-a, the mean value for superoxide in myelodysplastic stromal cultures was unchanged (fractional change=0.99+/-0.56), compared with an increase in normal stroma (fractional change=1.6+/-0.1, p<0.05). No correlation was observed between superoxide levels, proportion of apoptotic CD34+ cells and percentage of CD14+ stromal cells [mean 8%, range 0-37% (myelodysplastic); mean 1.3%, range 0-5% (normal)]. INTERPRETATION AND CONCLUSIONS: Abnormalities of stromal function in myelodysplastic syndromes are likely to be heterogeneous in origin: altered matrix molecules and changes in superoxide within stromal cells may contribute to abnormal survival and development of hematopoietic cells within the myelodysplastic marrow microenvironment

Aged↗
PubMed1998

Development of a multiplex ARMS test for mutations in the HFE gene associated with hereditary haemochromatosis.

Genetic testing for hereditary haemochromatosis is likely to be a significant workload for diagnostic laboratories. The C282Y and H63D mutations in the HFE gene associated with hereditary haemochromatosis have previously been detected using a number of methods including alterations in the restriction digest pattern of polymerase chain reaction (PCR) amplified products. An amplification refractory mutation system (ARMS) has been developed that will simultaneously detect both hereditary haemochromatosis mutations. Comparison of the results obtained from the analysis of 46 samples referred for hereditary haemochromatosis testing showed no discrepancies between ARMS and restriction enzyme digestion. Furthermore, consistent results were obtained by ARMS from both blood and buccal mouthwash samples. The ARMS test is quicker and less expensive in terms of consumables and scientist time than restriction enzyme analysis, and is therefore suited to the routine diagnostic analysis of hereditary haemochromatosis.

Cheek↗
PubMed1997

Management of iron deficiency in renal anemia: guidelines for the optimal therapeutic approach in erythropoietin-treated patients.

Much progress has been made in recent years in the management of anemia associated with chronic and renal failure with recombinant human erythropoietin (r-Hu EPO). However, there remains much debate surrounding the diagnosis and treatment of iron deficiency. To ensure that full benefit from erythropoietin therapy is received, most patients require iron supplement during treatment. There are, however, few guidelines for the use of iron therapy. Iron deficiency results in an inadequate response to r-Hu EPO and is the main cause of resistance to this treatment. Oral iron therapy is of limited value in patients receiving r-Hu EPO. Thus, intravenous iron supplementation should be administered only in patients who do not tolerate available intravenous iron preparations or who are on continuous ambulatory peritoneal dialysis with no evidence of functional iron deficiency. This article provides guidelines for the diagnosis of absolute or functional iron deficiency in patients with renal anemia and suggests treatment schedules for intravenous iron supplementation. We hope that all dialysis patients will be able on this basis to achieve a satisfactory iron status and benefit fully from r-Hu EPO therapy.

Anemia↗
PubMed1992

Regulation of iron absorption in iron loaded subjects with end stage renal disease: effects of treatment with recombinant human erythropoietin and reduction of iron stores.

The effects on iron absorption of variation in erythroid activity, haemoglobin and iron stores were studied in six anaemic dialysis-dependent subjects in whom iron stores were increased from previous red cell transfusions. Gastrointestinal mucosal uptake and whole body retention of oral iron were measured at the beginning of the study, after starting treatment with recombinant erythropoietin (but before significant increase in haemoglobin), after partial correction of anaemia, after further reduction of iron stores by repeated phlebotomy, and when erythropoiesis decreased from the discontinuation of treatment with erythropoietin. Between successive measurements, valid comparisons were made in five subjects. Correction of anaemia decreased whole body retention of iron through decreased mucosal uptake (P = 0.032). Further reduction in iron stores through repeated phlebotomy whilst the increase in haemoglobin was maintained by treatment with erythropoietin, tended to increase whole body retention of iron through an increase in mucosal transfer (P = 0.010). With initial enhancement of erythropoiesis in anaemic iron-loaded subjects there was no change in any measured component of iron absorption. However, after correction of anaemia and reduction of iron stores, a decrease in erythropoiesis was associated with decreased whole body iron retention in all subjects through decreased mucosal transfer (P = 0.028). The data suggest that anaemia upregulates mucosal iron uptake, and that erythroid activity upregulates mucosal transfer but that this latter effect may be counter-balanced by iron overload which downregulates mucosal transfer.

Adult↗
PubMed1991

Multiple myeloma and chronic myelomonocytic leukaemia developing in a patient with autoimmune disease.

A 64-year-old lady with a personal and family history of autoimmune disease developed chronic myelomonocytic leukaemia and multiple myeloma simultaneously. Her sister died of acute myelomonocytic leukaemia, but showed no evidence of autoimmune disease. It is possible that chronic immunological stimulation, perhaps by an autoantigen, may predispose toward malignant transformation in both plasma cell and monocyte series. However, the present observations raise the alternative possibility of a primary disorder of monocytes that predisposes toward both autoimmune disease and a clonal disorder of plasma cells.

Autoimmune Diseases↗
PubMed1991

Quantitative measurement of faecal blood loss: comparison of radioisotopic and chemical analyses.

Blood loss in faeces was assessed by three different methods in five patients with recurrent iron deficiency. In short term (12 day) studies chemical analysis of complete stool collections for haemderived porphyrins (HemoQuant) gave results closely correlated with those obtained by measuring stool loss of 51Cr-labelled red blood cells. Whole body counting for 59Fe was relatively insensitive to small blood losses but allowed losses to be followed up over longer periods. Chemical analysis of faecal porphyrins thus provides a satisfactory alternative to radioisotopic techniques in short term quantitation of faecal blood loss, while longer term whole body counting of 59Fe may still be appropriate in a few patients for the detection and quantification of intermittent blood losses.

Adult↗
PubMed1990

Subcutaneous administration of recombinant human erythropoietin to subjects on continuous ambulatory peritoneal dialysis: an erythrokinetic assessment.

Erythrokinetic studies were performed in subjects on continuous ambulatory peritoneal dialysis, during a trial examining the effectiveness of subcutaneous administration of recombinant human erythropoietin (r-HuEPO) in correcting the anaemia associated with end stage renal disease. 15 subjects (mean haemoglobin concentration 6.9 g/dl, SD 1.1) entered the study, and during treatment 9 were restudied at a haemoglobin concentration of 11-11.5 g/dl and six underwent a third study at haemoglobin 13-13.5 g/dl. By adjusting the dose of r-HuEPO, a stepwise increase in haemoglobin concentration was achieved, and this was accompanied by increases in total red cell volume and erythron transferrin uptake. Plasma volume decreased as red cell volume increased, leaving total blood volume essentially unchanged. Red cell survival, modestly reduced before treatment (mean 64, range 44-96 d, n = 6) tended to increase during treatment and when subjects were retested at a haemoglobin concentration of 13-13.5 g/dl (after 38-62 weeks treatment), the mean increase in red cell survival was 20 d (95% confidence interval 1-39 d). Thus subcutaneous r-HuEPO is effective in correcting the anaemia of end stage renal disease when administered thrice weekly to subjects on continuous ambulatory peritoneal dialysis. It produces an increase in haemoglobin concentration primarily by expanding the erythron, and may have a secondary effect, seen after several months of treatment, of increasing red cell survival.

Adult↗
PubMed1990

Microcytosis, iron deficiency, and thalassaemia in preschool children.

To investigate the possible causes of an increased incidence of red cell microcytosis in Asian children, 204 Gujarati Asian children and 88 European children attending community infant welfare clinics underwent initial screening tests for determination of red cell indices. Seventy six Asian (37%) and nine European (12%) children had microcytic red cells (mean corpuscular volume less than 74 fl). Further investigation showed that 16 of the Asian children (21%) with microcytosis had thalassaemia trait (eight were heterozygous for alpha thalassaemia and eight for beta thalassaemia), and 50 (66%) had suspected iron deficiency (confirmed by a response to oral iron in 41 cases): the remaining 'microcytic' children were aged less than 2 years, when mean corpuscular volume between 70 and 74 fl may be normal. Increased values for serum total iron binding capacity were more sensitive in detecting iron deficiency than reduced serum ferritin concentrations. Enthusiastic screening for microcytic anaemia in young children may mean that a substantial minority with thalassaemia genes are given unnecessary iron supplements. The response to a short course of oral iron should therefore be carefully monitored, and the possibility of thalassaemia trait as well as non-compliance with treatment should be reconsidered in all those in whom there is little or no response.

Asia↗