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D R Norfolk

Publications and source records attributed to D R Norfolk.

At least 19 recordsLinked to original sources
PubMed2005

American fresh frozen plasma for neonates and children.

From the spring of 2004 the United Kingdom Blood Services have been importing fresh frozen plasma from United States donors for all neonates and children born after 1 January 1996. The decision to mandate the use of American plasma in this age group was taken by the Department of Health in 2002 as part of its precautionary approach to the risk of transfusion transmitted variant Creutzfeldt-Jakob disease. In this article we explain the background to this decision and explore some of the implications it raises for clinical practice.

Blood Component Transfusion↗
PubMed2002

A modified Kleihauer technique for the quantification of foetomaternal haemorrhage.

The Kleihauer technique, based on acid elution of maternal red cells, is the mostly widely used technique in the UK to screen for, and estimate the volume of, foetomaternal haemorrhage (FMH) and for determining the need for additional doses of anti-D immunoglobulin to prevent maternal alloimmunization. However, technicians often report difficulties in identifying and accurately counting maternal red cells in the blood film, leading to imprecision in the calculated FMH. In this report, we describe a simple modification of the standard Kleihauer technique, based on performing acid elution of only half of the film. Compared to the standard method, the modified technique showed improved accuracy and reduced interobserver variability across a range of simulated FMH volumes. There was a high degree of correlation between the new technique and FMH estimated by flow cytometry (r2 = 0.916, P < 0.001). Technicians found the new technique easy to incorporate into routine practice in a busy teaching hospital laboratory and were impressed by the relative ease of counting maternal ghost cells. The modified technique has been used routinely in our laboratory for 3 years, during which time our performance in the UK National External Quality Assurance Scheme for FMH has been uniformly satisfactory.

Clinical Laboratory Techniques↗
PubMed1999

Haemochromatosis: a time for guidelines?

Hereditary haemochromatosis is an autosomal recessive metabolic abnormality which causes excessive absorption of dietary iron. Iron accumulation leads to potentially fatal damage to organs such as the heart, liver and pancreas. Normal life expectancy can be restored simply by therapeutic venesection. Discovery of the gene, HFE, has rekindled interest in pathogenesis, management and screening strategies.

Clinical Protocols↗
PubMed1998

Lymphocyte subset analysis and glycosylphosphatidylinositol phenotype in patients with paroxysmal nocturnal hemoglobinuria.

Using multicolor flow-cytometry we have examined 19 patients with paroxysmal nocturnal hemoglobinuria (PNH) (18 with active disease and 1 spontaneous remitter) to determine absolute numbers of lymphocyte subsets and the proportion of glycosylphosphatidylinositol (GPI)-deficient clones amongst these subpopulations. Lymphocyte subsets were abnormal in all patients; the most frequent findings were low absolute numbers of natural killer (NK) cells (median, 0.08 x 10(9)/L; normal range, 0.2 to 0.4 x 10(9)/L) and low absolute numbers of B cells (median, 0.05 x 10(9)/L; normal range, 0.06 to 0.65 x 10(9)/L). GPI-deficient B, T, and NK cells were identified in 88%, 84%, and 89% of patients, respectively. The proportion of GPI-deficient cells within individual lymphoid lineages was highly variable, though in most patients the percentage of GPI-deficient NK cells was considerably higher than B or T cells. These observations can be explained when mechanisms of normal lymphopoiesis are considered. Despite these quantitative and qualitative abnormalities, no patients suffered an excessive number or severity of infections. The detection of PNH clones amongst all lymphocyte lineages may provide important information regarding the natural history of the disease and additional insights into kinetics of adult lymphopoiesis.

Adult↗
PubMed1998

Circulating primitive stem cells in paroxysmal nocturnal hemoglobinuria (PNH) are predominantly normal in phenotype but granulocyte colony-stimulating factor treatment mobilizes mainly PNH stem cells.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia resulting from a somatic mutation in a hemopoietic stem cell. In most cases of hemolytic PNH, the majority of the marrow cells are derived from the PNH clone. Recent evidence has indicated, however, that the majority of the most primitive peripheral blood stem cells (PBSCs) in PNH appear to be of normal phenotype. This has led to tentative suggestions that normal PBSCs could be collected and used for autologous transplantation. We have investigated this possibility in four PNH patients by treating them with granulocyte colony-stimulating factor (G-CSF) in an attempt to mobilize normal progenitors. The expression of glycosylphosphatidylinositol (GPI)-linked proteins was analyzed by flow cytometry on mature neutrophils, late stem cells (CD34+/CD38+), and primitive stem cells (CD34+/CD38-). The phenotyping and stem cell quantitation was performed in steady-state blood and post-G-CSF administration. The most primitive PBSCs (CD34+/CD38-) were almost all normal before G-CSF treatment, even when the patients' neutrophils were mainly PNH. However, after G-CSF, the cells that were mobilized into the peripheral blood were of a similar phenotype to the mature neutrophils, ie, mainly PNH. It is possible that PNH-stem cells are preferentially destroyed by complement in the peripheral blood leaving only normal cells in the circulation. After G-CSF, the PNH cells in the marrow are released into the blood. Our findings suggest that it would be difficult to collect sufficient numbers of normal stem cells for autologous transplantation.

Adult↗
PubMed1997

Detection and quantitation of the CBFbeta/MYH11 transcripts associated with the inv(16) in presentation and follow-up samples from patients with AML.

We have developed a competitor-based RT-PCR technique which will detect and quantitate the CBFbeta/MYH11 transcripts associated with inv(16)(q22;p13) and have used it to study presentation and follow-up samples of acute myeloid leukaemia (AML). The levels of the leukaemia-specific transcripts are expressed as a ratio to a ubiquitously expressed mRNA species (Abl) which controls for RNA degradation. This technique has been applied to 75 consecutive patients presenting with either de novo AML or tMDS; 6/75 patients analysed were positive for the inv(16), all were confirmed by conventional cytogenetics. The inv(16) has a strong association with M4Eo, but we found only 2/6-positive patients to have this diagnosis (two patients with M2, one patient M1 and one patient had MDS). At presentation the levels of CBFbeta/MYH11 transcripts were 0.1-10/Abl transcript (mean 3.3/Abl transcript). Seventeen follow-up samples were available on 5/6 of these patients, and on two further patients in whom stored material was available. Following the first cycle of chemotherapy the level of transcripts was at least 10(-2) lower (0.1-10 x 10(-2)/abl transcript) than their presentation sample. Subsequent samples on these patients when in remission gave transcript levels in the range (1.0 x 10(-4) - 2 x 10(-3)/abl transcript), and three long-term follow-up samples were negative. We have developed a quantitative test which opens the possibility of predicting relapse by detecting changes in the numbers of leukaemia-specific transcripts.

Acute Disease↗
PubMed1997

Red cell ferritin, a marker of iron deficiency in hemodialysis patients.

Estimation of red cell ferritin (RCFer) may give a good indication of iron supply to the erythron and it may therefore be clinically useful for the detection of functional iron deficiency. In a cross-sectional study of hemodialysis patients on erythropoietin (EPO) therapy and regular oral iron we have compared the RCFer levels with conventional indicators of iron status. The patients studied, 19 female, 48 male, mean age 62 +/- 3.6 years (range 20-83 years) were characterized by the following mean parameters: aluminum 1.24 +/- 0.12 mumol/L, PTH 115.7 +/- 39 pg/mL, vitamin B12 626 +/- 71.2 ng/L, serum folate 18.8 +/- 2.2 micrograms/L, and hemoglobin 9.8 +/- 0.3 g/dL (range 7.3-12.4). The median serum ferritin (SF), RCFer, total iron binding capacity (TIBC), transferrin saturation (TS), and serum iron were 68 micrograms/L, 14.1 ag ferritin/red cell, 57 mumol/L, 20% and 11.5 mumol/L, respectively. Eleven patients had a reduced RCFer (< 7 ag ferritin/red cell), 5 had a SF of < 15 micrograms/L and 22 a TS of < 16%. The occurrence of functional iron deficiency was suggested by the presence of 10 subjects with reduced RCFer despite normal SF levels (15-240 micrograms/L). Four patients with reduced SF showed acceptable levels of RCFer, suggesting that some patients may maintain an adequate iron supply despite diminished iron stores. Despite oral iron therapy, a significant number of patients (63%) on regular hemodialysis remain relatively iron deficient with a serum ferritin of less than 100 micrograms/L. It has previously been proposed that oral iron provides adequate supplementation during increased demand caused by EPO stimulation. The present study has demonstrated overt iron deficiency in five subjects and suggests functional iron deficiency in a further seven (22% of total patients). We therefore conclude that oral iron therapy cannot maximize the response to EPO.

Administration, Oral↗
PubMed1996

Laparoscopic splenectomy. The suspended pedicle technique.

BACKGROUND: Elective splenectomy is often performed for hematological diseases, some of which cause only moderate enlargement of the spleen. The avoidance of an extensive upper abdominal incision is desirable in such cases and laparoscopic splenectomy offers significant potential advantages over the open operation if it can be performed safely and economically. METHODS: Eight consecutive patients underwent laparoscopic splenectomy. The operation was carried out with the patient at 40 degrees in the right lateral position so that rotating the operating table would make a full right lateral position possible. After fenestration of the gastrocolic omentum and division of the short gastric vessels, this position allowed the spleen to be pushed up under the diaphragm to facilitate access to the splenic vessels and the hilum. Vessels were divided individually between clips. RESULTS: All eight cases were completed laparoscopically. Mean length of operation was 259 min (range 230-285). Postoperative stay ranged from 2 to 7 days (median 4 days). There was no mortality, although minor complications did occur in three patients. CONCLUSIONS: We found laparoscopic splenectomy to be a safe and feasible procedure for the elective removal of the moderately enlarged spleen.

Adult↗
PubMed1995

Leucodepletion of blood products by filtration.

The leucocytes present in red cell and platelet components have been implicated in several important immunological and infective complications of blood transfusion. Recent developments in blood filtration technology allow the production of leucodepleted blood products (residual leucocytes < 5 x 10(6) per transfused unit) in the laboratory or at the bedside with the potential to prevent these adverse effects. Quality assurance remains an important problem, particularly for bedside filtration. Prestorage filtration may have significant advantages for red cell and platelet production. There is strong clinical evidence that 3 log10 leucodepletion prevents or delays febrile reactions in patients receiving multiple red cell transfusions and can reduce cytomegalovirus transmission. Leucodepletion to prevent HLA alloimmunisation, platelet refractoriness and febrile reactions in patients receiving red cell and platelet support remains controversial. Transfused leucocytes induce 'immunosuppressive' changes in the recipient, but recent studies cast doubt on the association with cancer recurrence after surgery. However, leucodepleted blood may reduce the incidence of postoperative infection. Leucodepletion by filtration is expensive and there is a requirement for well-designed prospective clinical studies focusing on appropriate filtration technology (and alternatives), clinical outcome and cost-effectiveness.

Animals↗
PubMed1995

Quantitative reticulocyte analysis may be of benefit in monitoring erythropoietin treatment in dialysis patients.

Reticulocyte responses to low-dose erythropoietin (EPO) were monitored using automated flow cytometric analysis. Sixteen adult dialysis patients were treated with 1,000 U of recombinant human EPO (rHuEPO), subcutaneously, thrice weekly (mean dose 15.7, SD 3.7 U/kg). The reticulocyte count (baseline 31.1, SD 19.1 x 10(9)/L) increased in 14 patients in the first week, with a peak response occurring at Week 2 (mean 57.3, SD 26.5 x 10(9)/L, p < 0.01). There was a wide spectrum of response, the maximal absolute increment ranging from 6.8-69.7 x 10(9)/L (maximal percentage increase 19-863%). Overall there was no relationship between the early increment in reticulocyte count and hemoglobin (Hb) response over the ensuing 4 months. Nine patients became transfusion independent (mean Hb increasing from 6.9, SD 0.8-9.2, SD 1.2 g/dl). Two patients had poor reticulocyte increments and no significant change in Hb. The remaining 5 patients responded partially with a brisk reticulocyte response and a marked reduction in transfusion dependency, but without a sustained increase in Hb. On investigation, all had gastrointestinal bleeding (melena in 1, commencing after initiation of treatment, positive fecal occult bloods in 4), whereas none of the other patients showed evidence of blood loss. It is notable that the erythron was sensitive to this modest dose of rHuEPO in the majority of patients as evidenced by the reticulocyte response. The results provide useful information in the management of patients on rHuEPO. A small or inapparent reticulocyte response suggests a confounding factor; a poor Hb response in the presence of active reticulocyte synthesis points to occult blood loss or hemolysis.

Adult↗
PubMed1995

Re-establishment of erythropoietin responsiveness in end-stage renal failure following renal transplantation.

Re-establishment of erythropoietin (EPO) secretion following renal transplantation is poorly understood. The development of sensitive EPO radioimmunoassay has enabled further study of this phenomenon. Forty-one adult patients were studied during the first 16 weeks following renal transplantation. Twenty six received cyclosporin monotherapy and 15 also received prednisolone and azathioprine. Serum creatinine, haemoglobin (Hb), ferritin and EPO were assayed pre-operatively, daily for 1 week, weekly for 1 month, and fortnightly to 16 weeks. An expected EPO value, for any Hb level, was derived by linear regression analysis in 144 patients with iron deficiency anemia. An observed to expected ratio (O/E) was calculated, a value of 1.0 implying appropriate responsiveness. Hb increased from 8.6 +/- 2.0 (SD) to 12.3 +/- 2.1 g/dl (p < 0.001) over 16 weeks, an increase unaffected by ferritin status. Mean EPO concentration increased during the first week with a peak at day 4 (22.1 +/- 13.3 to 44.6 +/- 40.0 mu/ml, p < 0.05), a change apparent only in patients with immediate graft function (24 cases). There was no correlation between EPO and Hb pre-operatively; however a significant inverse relationship was established by week 16 (r = -0.404, p < 0.02). The median O/E ratio (0.22) at baseline increased progressively to 1.0 at 16 weeks (p < 0.001); ratios were significantly greater in the immediate versus delayed function group throughout (p < 0.05). In the former group an O/E ratio of 1.0 was reached at 10 weeks when mean serum creatinine was 142 +/- 48 mumol/l. Patients with poor ongoing renal function (9 cases, serum creatinine > 250 mumol/l at 16 weeks) had impaired Hb recovery (10.1 +/- 1.6 vs 12.7 +/- 2.0 g/dl at 16 weeks, p < 0.05). EPO values were not different in those patients but median O/E ratios were significantly depressed (p < 0.05) throughout, the maximum O/E ratio being 0.75. Recovery of renal function is accompanied by a beneficial Hb response driven by EPO synthesis in the transplant. The O/E ratio provides a useful index to assess EPO responsiveness. Appropriate secretion was achieved during the first 4 months and optimized by immediate and satisfactory graft function.

Adult↗
PubMed1994

Bedside filtration of blood products in the prevention of HLA alloimmunization--a prospective randomized study. Alloimmunisation Study Group.

To test the efficacy of poststorage bedside leucodepletion of blood products in the prevention of primary HLA alloimmunization and its clinical sequelae, 172 patients with hematologic malignancy requiring intensive red blood cell and platelet support were randomized to receive either standard or filtered red blood cells and platelets. Quality control of bedside filtration was explored by sequential sampling downstream of the filter, but this did not predict the total number of leucocytes transfused. After exclusions, 123 evaluable patients were assessed every two weeks until the end of therapy. HLA antibodies developed in 21 of 56 (37.5%) nonfilter (NF) and 15 of 67 (22%) filter (F) patients (risk ratio estimate, 0.60 [95% confidence interval, 0.34 to 1.05]; P = .07). Patients with acute myeloid leukemia (AML; n = 53) had higher alloimmunization rates in both arms of the study, with a greater effect of filtration (62.5% NF and 31.0% F; P = .025). Bedside filtration did not affect the overall incidence of febrile transfusion reactions (FTRs; 37% NF and 34% F; P = .71) or of platelet refractoriness assessed in 50 patients (30% NF and 26% F), despite an association between broad HLA reactivity and both FTRs and refractoriness. However, FTRs were also seen in 28 patients without HLA antibodies. Five alloimmunized refractory patients (2 F and 3 NF) required HLA-selected platelets. This report, the first prospective study of bedside filtration, has failed to show clear clinical benefit. Methodological limitations may account in part for this failure, notably the difficulties in accurately assessing the number of leucocytes transfused.

Adolescent↗