A Deep Learning Approach to Diagnostic Classification of Prostate Cancer Using Pathology-Radiology Fusion

BACKGROUND

A definitive diagnosis of prostate cancer requires a biopsy to obtain tissue for pathologic analysis, but this is an invasive procedure and is associated with complications.

PURPOSE

To develop an artificial intelligence (AI)-based model (named AI-biopsy) for the early diagnosis of prostate cancer using magnetic resonance (MR) images labeled with histopathology information.

STUDY TYPE

Retrospective.

POPULATION

Magnetic resonance imaging (MRI) data sets from 400 patients with suspected prostate cancer and with histological data (228 acquired in-house and 172 from external publicly available databases).

FIELD STRENGTH/SEQUENCE

1.5 to 3.0 Tesla, T2-weighted image pulse sequences.

ASSESSMENT

MR images reviewed and selected by two radiologists (with 6 and 17 years of experience). The patient images were labeled with prostate biopsy including Gleason Score (6 to 10) or Grade Group (1 to 5) and reviewed by one pathologist (with 15 years of experience). Deep learning models were developed to distinguish 1) benign from cancerous tumor and 2) high-risk tumor from low-risk tumor.

STATISTICAL TESTS

To evaluate our models, we calculated negative predictive value, positive predictive value, specificity, sensitivity, and accuracy. We also calculated areas under the receiver operating characteristic (ROC) curves (AUCs) and Cohen's kappa.

RESULTS

Our computational method (https://github.com/ih-lab/AI-biopsy) achieved AUCs of 0.89 (95% confidence interval [CI]: [0.86-0.92]) and 0.78 (95% CI: [0.74-0.82]) to classify cancer vs. benign and high- vs. low-risk of prostate disease, respectively.

DATA CONCLUSION

AI-biopsy provided a data-driven and reproducible way to assess cancer risk from MR images and a personalized strategy to potentially reduce the number of unnecessary biopsies. AI-biopsy highlighted the regions of MR images that contained the predictive features the algorithm used for diagnosis using the class activation map method. It is a fully automatic method with a drag-and-drop web interface (https://ai-biopsy.eipm-research.org) that allows radiologists to review AI-assessed MR images in real time.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY STAGE: 2.

Inferring cancer progression from Single-Cell Sequencing while allowing mutation losses

Motivation

In recent years, the well-known Infinite Sites Assumption has been a fundamental feature of computational methods devised for reconstructing tumor phylogenies and inferring cancer progressions. However, recent studies leveraging single-cell sequencing (SCS) techniques have shown evidence of the widespread recurrence and, especially, loss of mutations in several tumor samples. While there exist established computational methods that infer phylogenies with mutation losses, there remain some advancements to be made.

Results

We present Simulated Annealing Single-Cell inference (SASC): a new and robust approach based on simulated annealing for the inference of cancer progression from SCS datasets. In particular, we introduce an extension of the model of evolution where mutations are only accumulated, by allowing also a limited amount of mutation loss in the evolutionary history of the tumor: the Dollo-k model. We demonstrate that SASC achieves high levels of accuracy when tested on both simulated and real datasets and in comparison with some other available methods.

Availability and implementation

The SASC tool is open source and available at https://github.com/sciccolella/sasc.

Supplementary information

Supplementary data are available at Bioinformatics online.

VALOR2: characterization of large-scale structural variants using linked-reads

Most existing methods for structural variant detection focus on discovery and genotyping of deletions, insertions, and mobile elements. Detection of balanced structural variants with no gain or loss of genomic segments, for example, inversions and translocations, is a particularly challenging task. Furthermore, there are very few algorithms to predict the insertion locus of large interspersed segmental duplications and characterize translocations. Here, we propose novel algorithms to characterize large interspersed segmental duplications, inversions, deletions, and translocations using linked-read sequencing data. We redesign our earlier algorithm, VALOR, and implement our new algorithms in a new software package, called VALOR2.

PhISCS: a combinatorial approach for subperfect tumor phylogeny reconstruction via integrative use of single-cell and bulk sequencing data

Available computational methods for tumor phylogeny inference via single-cell sequencing (SCS) data typically aim to identify the most likely perfect phylogeny tree satisfying the infinite sites assumption (ISA). However, the limitations of SCS technologies including frequent allele dropout and variable sequence coverage may prohibit a perfect phylogeny. In addition, ISA violations are commonly observed in tumor phylogenies due to the loss of heterozygosity, deletions, and convergent evolution. In order to address such limitations, we introduce the optimal subperfect phylogeny problem which asks to integrate SCS data with matching bulk sequencing data by minimizing a linear combination of potential false negatives (due to allele dropout or variance in sequence coverage), false positives (due to read errors) among mutation calls, and the number of mutations that violate ISA (real or because of incorrect copy number estimation). We then describe a combinatorial formulation to solve this problem which ensures that several lineage constraints imposed by the use of variant allele frequencies (VAFs, derived from bulk sequence data) are satisfied. We express our formulation both in the form of an integer linear program (ILP) and—as a first in tumor phylogeny reconstruction—a Boolean constraint satisfaction problem (CSP) and solve them by leveraging state-of-the-art ILP/CSP solvers. The resulting method, which we name PhISCS, is the first to integrate SCS and bulk sequencing data while accounting for ISA violating mutations. In contrast to the alternative methods, typically based on probabilistic approaches, PhISCS provides a guarantee of optimality in reported solutions. Using simulated and real data sets, we demonstrate that PhISCS is more general and accurate than all available approaches.

Meltos: multi-sample tumor phylogeny reconstruction for structural variants

MOTIVATION

We propose Meltos, a novel computational framework to address the challenging problem of building tumor phylogeny trees using somatic structural variants (SVs) among multiple samples. Meltos leverages the tumor phylogeny tree built on somatic single nucleotide variants (SNVs) to identify high confidence SVs and produce a comprehensive tumor lineage tree, using a novel optimization formulation. While we do not assume the evolutionary progression of SVs is necessarily the same as SNVs, we show that a tumor phylogeny tree using high-quality somatic SNVs can act as a guide for calling and assigning somatic SVs on a tree. Meltos utilizes multiple genomic read signals for potential SV breakpoints in whole genome sequencing data and proposes a probabilistic formulation for estimating variant allele fractions (VAFs) of SV events.

RESULTS

In order to assess the ability of Meltos to correctly refine SNV trees with SV information, we tested Meltos on two simulated datasets with five genomes in both. We also assessed Meltos on two real cancer datasets. We tested Meltos on multiple samples from a liposarcoma tumor and on a multi-sample breast cancer data (Yates et al., 2015), where the authors provide validated structural variation events together with deep, targeted sequencing for a collection of somatic SNVs. We show Meltos has the ability to place high confidence validated SV calls on a refined tumor phylogeny tree. We also showed the flexibility of Meltos to either estimate VAFs directly from genomic data or to use copy number corrected estimates.

AVAILABILITY AND IMPLEMENTATION

Meltos is available at https://github.com/ih-lab/Meltos.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Using LICHeE and BAMSE for Reconstructing Cancer Phylogenetic Trees

The reconstruction of cancer phylogeny trees and quantifying the evolution of the disease is a challenging task. LICHeE and BAMSE are two computational tools designed and implemented recently for this purpose. They both utilize estimated variant allele fraction of somatic mutations across multiple samples to infer the most likely cancer phylogenies. This unit provides extensive guidelines for installing and running both LICHeE and BAMSE. © 2018 by John Wiley & Sons, Inc.

Progress testing in undergraduate dental education: the Peninsula experience and future opportunities

BACKGROUND

Progress testing is well established as a longitudinal form of assessment in undergraduate medical programmes to measure growth in knowledge. Peninsula Dental School is the first school to use progress testing and remains the only one to do so.

AIMS

To share the experience of developing progress testing in an undergraduate dental programme as a major summative assessment tool at a newly established dental school in the United Kingdom.

METHODS

Data were collected for progress tests conducted from 2007 to 14. The tests were formative in the first 2 years of the programme and summative in subsequent years. Each test was based on 100 single best answer multiple-choice items with an appropriate vignette. The students chose their answer from 5 options. A score 1 mark is awarded for each correct answer, minus 0.25 for an incorrect answer and 0 for 'don't know' (DK). The standard setting for each sitting was carried out using Angoff and Hofstee methods.

RESULTS

There were two tests per year with each cohort undertaking eight tests in their 4 years of study providing a total 14 test occasions. The reliability of each test for each student cohort tests was measured using Cronbach's alpha. The average reliability over 42 test/cohort combinations was 0.753 (±SD 0.08). Data analyses show growth in knowledge of dental students across successive years with the largest increase in knowledge observed between tests 1 and 5 and concomitant reduction in DK responses.

CONCLUSION

This is the first study to report the establishment and use of progress testing as the principle form of written summative testing in an undergraduate dental curriculum. Progress testing is a valid and reliable tool to assess growth in knowledge longitudinally over the duration of a dental programme. Although a labour-intensive process, progress testing merits more widespread use in dental programmes.

Variability of serum ferritin concentration in normal subjects

Serum ferritin concentrations were measured in normal subjects over periods of 1 day, 1 week and 7 weeks. The variation of the results was compared with variation of control of control sera. In most of the subjects the variation in the results could be attributed to the variation in the method of measurement. No diurnal variation in serum ferritin concentration was observed.

Tear lipid layer thickness and ocular comfort with a novel device in dry eye patients with and without Sjögren's syndrome

BACKGROUND

To measure changes in tear-film lipid-layer thickness (LLT) and symptoms in patients with dry eye symptoms with and without Sjögren's syndrome after using a novel device. The device is designed to promote release of meibomian sebum into the tear film by delivering latent heat to the eyelids.

STUDY DESIGN

Two prospective, controlled, randomised, observer-masked, single-intervention studies.

METHODS

Two independent studies were conducted in a major university hospital in the South West of England. The first study involved 24 patients with dry eye symptoms without Sjögren's [the PDE study] and the second study involved 31 patients with dry eye symptoms and Sjögren's syndrome (the SS study). The PDE study was randomised into two groups. Group I (12 patients) underwent 10 min of treatment with the activated device and Group II (12 patients) had no treatment. The SS study was similarly randomised into Group I (17 patients) and Group II (14 patients). The LLT and subjective alterations in ocular comfort of each subject were assessed prior and immediately after 5 and 30 min subsequent to the 10-min period. In the SS study, a further assessment was carried out at 60 min.

RESULTS

In the PDE study, treated patients exhibited a bilateral increase of LLT at 5 min (right eyes, 1.2 levels, p<0.0005; left eyes, 1.0 levels, p<0.0005, Mann-Whitney) and at 30 min (right eyes, 0.7 levels, p<0.005; left eyes, 0.6 levels, p<0.005). Mean symptom scores improved in the treated group compared with the control group at 5 min (treatment group, +2.0; control group, +0.2; p<0.05) and 30 min (treatment group, +2.8; control group, +0.4; p<0.015). In the SS study, treated patients exhibited a bilateral increase of LLT, 5 min (right eyes, 0.5 levels, p<0.009; left eyes, 0.5 levels, p<0.005, Monte Carlo 2-tailed), 30 min (right eyes, 0.5 levels, p<0.007; left eyes 0.5 levels, p<0.002) and 60 min (right eyes, 0.3 levels, p<0.1; left eyes, 0.3 levels, p<0.05). There was no change in any of the control patients in any of the assessments. With regard to symptom scores, the mean change at 5 min measured +0.8 in the treatment group and remained relatively unchanged at +0.1 in the control group (p<0.1). At 30 min, this change measured +1.3 in the treatment group and +0.1 in the control group (p<0.03) and at 60 min, the change measured +1.5 in the treatment group and remained at +0.1 in the control group (p<0.02).

CONCLUSION

Meibomian therapy with this novel device increases LLT and ocular comfort in patients with dry eye symptoms with and without Sjögren's syndrome.

Common variations in the ALMS1 gene do not contribute to susceptibility to type 2 diabetes in a large white UK population

AIMS/HYPOTHESIS

Alström syndrome is a rare monogenic disorder characterised by retinal dystrophy, deafness and obesity. Patients also have insulin resistance, central obesity and dyslipidaemia, thus showing similarities with type 2 diabetes. Rare mutations in the ALMS1 gene cause severe gene disruption in Alström patients; however, ALMS1 gene polymorphisms are common in the general population. The aim of our study was to determine whether common variants in ALMS1 contribute to susceptibility to type 2 diabetes in the UK population.

METHODS

Direct sequencing was performed on coding regions and intron/exon boundaries of the ALMS1 gene in 30 unrelated probands with type 2 diabetes. The linkage disequilibrium (LD; D' and r2) and haplotype structure were examined for the identified variants. The common (minor allele frequency [MAF] >5%) single-nucleotide polymorphisms tagging the common haplotypes (tagged SNPs [tSNPs]) were identified and genotyped in 1985 subjects with type 2 diabetes, 2,047 control subjects and 521 families.

RESULTS

We identified 18 variants with MAF between 6 and 38%. Three SNPs efficiently tagged three common haplotypes (rs1881245, rs3820700 and rs1320374). There was no association (all p > 0.05) between the tSNPs and type 2 diabetes in the case-control study and minor alleles of the tSNPs were not overtransmitted to probands with type 2 diabetes in the family study.

CONCLUSIONS/INTERPRETATION

Common variations in the ALMS1 gene were not associated with type 2 diabetes in a large study of a white UK population.

Tear film lipid layer thickness and ocular comfort after meibomian therapy via latent heat with a novel device in normal subjects

AIM

This study measures changes in tear film lipid layer thickness (LLT) and ocular comfort in normal subjects after 10 min use of a novel device, which delivers meibomian therapy with latent heat. The device is designed to promote the release of meibomian sebum into the tear film by delivering latent heat to the eyelids, thus thickening the lipid layer. Normal lid movements are maintained, facilitating resurfacing of the tear film.

METHOD

A prospective, controlled, observer masked, single intervention trial in which 24 normal subjects were randomised into three groups. Group I underwent 10 min treatment with the activated device, Group II used the inactivated device for the same duration of time, and Group III had no intervention. The LLT of each subject was measured with a Keeler Tearscope prior and subsequent to the 10-min period. Subjective alteration in ocular comfort was also assessed.

RESULTS

Seven of eight subjects (87.5%) in Group I exhibited an increase in LLT. The mean LLT in this group showed a statistically significant increase (left eyes 1.0 levels, P<0.001, right eyes 0.9 levels, P<0.003) compared to Groups II and III. Six of eight subjects (75%) using the activated device experienced subjective improvement in ocular comfort.

CONCLUSION

Meibomian therapy with this device increases LLT in normal individuals. This implies a more stable tear film, reflected in subjective improvement in ocular comfort.

The Effect of Reporting Speed on Plain Film Reporting Errors

AIM

To determine whether reporting plain films at faster rates lead to a deterioration in accuracy.

METHODS

Fourteen consultant radiologists were asked to report a total of 90 radiographs in three sets of 30. They reported the first set at the rate they would report normally and the subsequent two sets in two thirds and one half of the original time. The 90 radiographs were the same for each radiologist, however, the order was randomly generated for each.

RESULTS

There was no significant difference in overall accuracy for each of the three film sets (p=0.74). Additionally no significant difference in the total number of false-negatives for each film set was detected (p=0.14). However, there was a significant decrease in the number of false-positive reports when the radiologists were asked to report at higher speeds (p=0.003).

CONCLUSIONS

When reporting accident and emergency radiographs increasing reporting speed has no overall effect upon accuracy, however, it does lead to less false-positive reports.

Age-related temporal processing speed deterioration in auditory cortex

A common problem among the elderly is a difficulty in discriminating speech sounds. One factor that may contribute to this is a deterioration in the ability to process dynamic aspects of speech such as formant transitions. For the aging auditory system, this deterioration in temporal processing speed may be manifest as a deficit in encoding time-varying sounds that contain rapidly changing frequencies such as formant transitions. The primary goal of this study was to explore the neural basis of the effects of aging on temporal processing speed. To this end, single units were recorded from the auditory cortex of young and aged rats in response to frequency-modulated (FM) sweeps that changed from trial to trial in both direction and speed. Results showed that the majority of cells recorded from young rats responded most vigorously to fast and medium speeds. By contrast, the majority of units recorded from aged animals responded best to slow speeds. For preferred direction of FM sweep, similar results were observed for both age groups, namely, approximately half of the units exhibited a direction-selective response. The results of the present study demonstrate an age-related decrease in the rate of change of frequency that can be processed by the auditory cortex.

Pre-registration diploma students: a quantitative study of entry characteristics and course outcomes

Nurse education has been transformed over the last decade and continuing change is likely. Nurse educators are responsible for meeting the quality assurance standards of local stakeholders and student retention and progress are important aspects of this process. As part of a monitoring exercise, an enquiry was set up to review pre-registration selection and recruitment strategies and to establish if there were any significant relationships between the characteristics of pre-registration diploma entrants and their academic achievement or completion rates. A multi-factorial tree-based technique was used for this purpose. This is one of the first British studies to consider both academic performance and completion rates for pre-registration diploma students. Four cohorts (N = 355) were studied. There was marked heterogeneity in student characteristics with a wide age distribution, a significant proportion of mature entrants with previous care experience, and considerable diversity in terms of education. Education and age were significant predictors of academic achievement: entrants with a minimum of two A levels and mature women with recent study experience did particularly well. Younger recruits with modest educational qualifications on entry performed less well in their assessments of theoretical knowledge. Younger students tended to leave more regularly, and well-qualified entrants showed a greater tendency to complete, although these relationships were not statistically significant. Multi-factorial analysis demonstrated that organisational and course characteristics have a conjoint influence on course outcomes. Although the study is concerned with Project 2000 in the United Kingdom, there are lessons to be drawn concerning the selection and support of non-traditional recruits into nursing.

Responses to time-varying stimuli in rat auditory cortex

Responses to frequency modulated (FM) sweeps were recorded in rat primary auditory cortex. Forty-four percent of the cells were direction-selective. For speed selectivity, the majority of the cells preferred faster sweeps. The results suggest that rat auditory cortex may be used for processing communication signals of their predators or for detecting spectral changes in acoustic signals.

The distribution of leukaemia in association with domestic water quality in south west England

This study assessed whether there is any variation in the incidence of haematological malignancies between geographical areas of differing water supplies in the South West peninsula of the United Kingdom (1984 to 1988 inclusive). The possibility of correlations existing between variation in water quality and variation in the incidence of haematological malignancies was examined. Haematological incidence data, taken from the Leukaemia Research Fund's Data Collection Study, were mapped into 46 geographical areas of differing water supply. The distribution of the mapped cases was then tested for homogeneity using the Potthoff and Whittinghill (1966) test score. The age-adjusted incidence ratios calculated during the heterogeneity testing were examined for correlations with water quality indicators using correlation and stepwise regression. Significant heterogeneity in the incidence rates among water supply areas was observed for two groups of disease-acute leukaemias and myeloproliferative disorders. Three water quality indicators-pH, nitrate concentration and aluminium concentration-varied considerably over the study period. Significant correlations were observed between the standardized incidence ratios of five disease categories and some water quality indicators, especially aluminium and trihalomethane concentrations. The standardized incidence ratios of some haematological malignancies differed between geographical areas of water supply in South West England, and the evidence suggests that this variation may be associated with variation in water quality indicators. Although this lends support to similar findings in the United States of America, the pattern of correlations are affected by disease latency and statistical methodology.

Predicting outcome in severe ulcerative colitis

BACKGROUND

Simple criteria are needed to predict which patients with severe ulcerative colitis will respond poorly to intensive medical treatment and require colectomy.

AIMS

To find out if the early pattern of change in inflammatory markers or other variables could predict the need for surgery and to evaluate the outcome of medical treatment during one year follow up.

PATIENTS

51 consecutive episodes of severe colitis (Truelove and Witts criteria) affecting 49 patients admitted to John Radcliffe Hospital, Oxford.

METHODS

Prospective study monitoring 36 clinical, laboratory, and radiographic variables. All episodes treated with intravenous and rectal hydrocortisone and 14 of 51 with cyclosporine.

RESULTS

Complete response in 21 episodes (< or = 3 stools on day 7, without visible blood), incomplete response in 15 (> 3 stools or visible blood on day 7, but no colectomy), and colectomy on that admission in 15. During the first five days, stool frequency and C reactive protein (CRP) distinguished between outcomes (p < 0.00625, corrected for multiple comparisons) irrespective of whether patients or the number of episodes were analysed. It could be predicted on day 3, that 85% of patients with more than eight stools on that day, or a stool frequency between three and eight together with a CRP > 45 mg/l, would require colectomy. For patients given cyclosporine, four of 14 avoided colectomy but two continued to have symptoms. After admission, complete responders remained in remission for a median nine months and had a 5% chance of colectomy. Incomplete responders had a 60% chance of continuous symptoms and 40% chance of colectomy.

CONCLUSIONS

After three days intensive treatment, patients with frequent stools (> 8/day), or raised CRP (> 45 mg/l) need to be identified, as most will require colectomy on that admission. The role of cyclosporine for treating severe colitis has yet to be defined. After seven days' treatment, patients with > 3 stools/day of visible blood have a 60% chance of continuous symptoms and 40% chance of colectomy in the following months.

Benefits and weaknesses of a cardiac rehabilitation programme

The British Heart Foundation and the Chest, Heart and Stroke Association have allocated funds to develop cardiac rehabilitation programmes. We have recently completed and now evaluate an exercise-based rehabilitation course reinforced with advice about return to normal activity for 110 patients who had suffered acute myocardial infarction. Patients admitted to the Plymouth cardiac care unit were randomised into groups: a control group to receive standard hospital care, and a rehabilitation group who, in addition, received an exercise programme reinforced with advice. Patients were assessed at entry to the study and at intervals thereafter. Assessment was by questionnaire and objective tests consisting of a 12-minute walking test and weekly outpatient pedometry. In the rehabilitation group patients were able to walk further and faster, return to work earlier, undertake more housework, and resume normal sexual activity; they were less short of breath and did not experience more angina. However, the rehabilitation course brought little benefit to the patients' perception of well-being and their anxiety about health or their outlook on life. Exercise and advice are important components of a rehabilitation programme, but more attention needs to be given to the psychological aspects of recovery from a heart attack.

Binding of serum ferritin to concanavalin A: patients with homozygous beta thalassaemia and transfusional iron overload

Serum ferritin concentrations have been measured in 124 patients with homozygous beta thalassaemia who were between 2 and 21 years old, had received 11--504 units of blood but had not undergone splenectomy. There were highly significant correlations between serum ferritin concentration and both the amount of blood transfused and alanine amino-transferase (ALT) activity. However, multivariate analysis showed that units of blood and ALT activity together only accounted for about 30% of the variation in serum ferritin concentration. Little of the remaining variation could be explained by other variables related to iron metabolism or liver damage. The concentration of concanavalin A binding ferritin increased rapidly with the number of units of blood up to 100 units but thereafter showed no further increase with number of transfusions. The concentration of non-binding ferritin was more closely related to transfusion load. These results suggest that the secretion of glycosylated ferritin from reticuloendothelial cells reaches a maximum with increasing iron accumulation, perhaps reflecting a maximum rate of synthesis. Ferritinaemia in patients with transfusional iron overload therefore seems to be the result of the combined effects of increased ferritin synthesis and the release of intracellular ferritin from damaged cells. A simple relationship between serum ferritin and iron stores cannot be assumed when ferritin concentrations exceed 4000 microgram/l or in patients who have received more than 100 units of transfused blood.

A method for the investigation of reticuloendothelial iron kinetics in man

A colloidal suspension of hydrolysed radio-iron of high specific activity has been developed for the investigation of reticuloendothelial (RE) iron kinetics in man. Following intravenous injection this material is cleared rapidly by the RE system and the iron released intn to the endogenous RE iron load, and it has proved possible to measure RE iron release without disturbing the normal iron flow.

Measurement of haemolysis in patients with prosthetic heart valves

Haemolysis following prosthetic heart valve insertion can be precisely and sensitively measured by means of a 59Fe ferrokinetic technique. Results obtained in a small series of patients with either Starr-Edwards or Brunwald-Cutter valve replacement are presented.

An evaluation of two methods of laboratory quality control

Two methods for quality control of automated blood counters have been compared: (1) monitoring results from patients' samples, and (2) analysis of results of a stable whole-blood control. The latter method proved better able to distinguish calibration changes from patient variation.

Erythropoiesis and iron metabolism in Hodgkin's disease

Recently developed techniques for the investigation of iron kinetics were used to study the disturbance of iron metabolism in 19 untreated patients with Hodgkin's diseases (HD). The erythroid abnormality in newly diagnosed HD appears to be confined to those patients with systemic symptoms of weight loss, night sweats and fever, and consists of depression of marrow erythroid activity. These patients had a significnatly lower haemoglobin and serum iron concentration and a higher serum ferritin concentration, both when compared to normal subjects and to those patients with HD who lacked systemic symptoms. Ineffective erythropoiesis and red-cell destruction were not significantly increased. The present findings, confirm that HD patients with systemic symptoms have a depression of erythropoiesis, and that in these patients the marrow fails to respond to the stimulus of mild anaemia.

Studies in desferrioxamine and ferrioxamine metabolism in normal and iron-loaded subjects

Plasma concentrations of desferrioxamine and ferrioxamine were measured following bolus injections of desferrioxamine and during 24 h infusions of the drug. [59Fe]ferrioxamine clearance and urinary iron excretion were also measured. Higher plasma ferrioxamine concentrations were found in iron loaded subjects and higher desferrioxamine concentrations in subjects with normal ironloads. There is a correlation between the circulating concentration of ferrioxamine during an infusion and the 48 h urinary iron excretion. The data suggests that the amount of iron chelated in vivo is related to an increase in the size of an intermediate chelatable pool rather than the total amount of the iron load. The well-recognized delay in urinary iron excretion appears to be related to active tubular reabsorption of ferrioxamine.

Erythropoiesis, iron stores and tissue iron exchange in man

1. The exchange of iron between plasma and erythroid and non-erythroid tissues was measured in 14 normal subjects, 17 iron-deficient patients, nine patients with primary idiopathic haemochromatosis and in 13 patients with haemolytic disorders. 2. The two main factors determining tissue iron turnover were shown to be the level of iron stores and the erythropoietic activity of the bone marrow.

Serum 2-hydroxybutyrate dehydrogenase activity and ineffective erythropoiesis

Images

Ferrokinetics: methods and interpretation

The measurement of erythroid activity is based on the study of plasma iron kinetics. The radioiron injected should be bound specifically to transferrin, and the measurement of plasma 59Fe activity should be corrected for variation in plasma iron concentration. In addition, 59Fe-transferrin activity should be measured free of 59Fe-haemoglobin contamination. Analysis of the plasma 59Fe clearance curve over 14 days can give measures of total, effective and ineffective erythropoiesis, together with the red cell lifespan. Simpler ferrokinetic studies cannot be reliably used to assess erythropoiesis.

Erythropoiesis in the anaemia of chronic disease

The amount and effectiveness of erythropoiesis was measured using 59Fe in 10 patients with the anaemia of chronic disease and in 10 iron deficient patients with a comparable degree of anaemia. In both conditions the anaemia was the result of the failure of the marrow to compensate for a modest degree of peripheral haemolysis but ineffective erythropoiesis was significantly greater in iron deficiency than in chronic disease. The results suggest that although the peripheral blood picture is similar in both conditions the anaemia of chronic disease cannot be attributed simply to iron deficient erythropoiesis.

The measurement of red cell lifespan using 59Fe

Red cell lifespan has been measured using 51Cr and 59Fe in 19 patients. 59Fe can be used to give results which agree closely with those obtained using 51Cr provided that the plasma 59Fe clearance curve is properly defined and the data analysed correctly. In some patients elution of 51Cr may be more than three times the normal level and the use of 59Fe may provide the only reliable estimate of red cell lifespan.

Radioiron and erythropoiesis: methods, interpretation and clinical application

Ferrokinetic studies have fallen somewhat out of fashion and this is probably because T 1/2, PIT and percentage utilization give a poor reflection of the state of erythropoiesis. Recent advances have, however, enabled total, effective and ineffective erythropoiesis to be measured. The technique is simple but time-consuming, and analysis of the data requires access to computing facilities. Nevertheless, when bone marrow erythroid activity must be assessed these radioiron methods offer a rational approach.

Ferrokinetics and erythropoiesis in man: red-cell production and destruction in normal and anaemic subjects

Recent advances in the analysis of plasma 59Fe clearance have produced a unified method for measuring effective and ineffective erythropoiesis (Ricketts et al, 1975). We have used this method to investigate the balance between red-cell production and destruction in normal subjects and in patients with megaloblastic anaemia, iron deficiency anaemia, and refractory hypoplastic anaemia. The results show that the normal marrow can maintain an appropriate red-cell mass by altering red-cell production to match destruction. In the anaemias we have studied there is an increased rate of either intra- or extra-medullary red-cell destruction. The response of the marrow may be limited by iron supply, by defective nuclear maturation or by some intrinsic marrow defect.

Ferrokinetics and erythropoiesis in man: an evaluation of ferrokinetic measurements

The plasma iron clearance half-time and plasma iron turnover have usually been interpreted as measures of total erythroid activity and the red-cell utilization of 59Fe has been equated with effective red-cell production. Erythrocyte iron turnover has sometimes been calculated as the product of plasma iron turnover and percentage utilization. We have assessed these measurements as estimates of erythroid activity by comparing them with total marrow iron turnover and red-cell iron turnover determined by the method of Ricketts et al (1975) in 10 normal subjects and 51 patients with an uncomplicated haematological disorder. The results show that the plasma iron clearance half-time does not reflect erythroid activity and that plasma iron turnover can be particularly misleading in patients with reduced marrow activity. Red-cell utilization and erythrocyte iron turnover give a distorted reflection of effective erythropoiesis except in patients with erythroid hypoplasia. Marrow iron turnover and red-cell iron turnover provide more realistic and generally applicable assessments of the degree and effectiveness of erythroid activity.