Potentially clinically important inaccuracies in testing for the lupus anticoagulant: an analysis of results from three surveys of the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation

The identification of the presence of antiphospholipid in plasma is recognised to be of diagnostic and prognostic importance in subjects with thrombotic disease, recurrent miscarriage or collagen vascular disorders. A number of coagulation assays are currently employed for the detection of lupus anticoagulant (LA), many of which are influenced by reagent dependent and methodological variables. In the present study lyophilised plasma samples from three subjects with "strong", "weak" and "absent" LA were tested in 220 centres. The most commonly used tests for LA were Activated Partial Thromboplastin Time (APTT), Dilute Russell Viper Venom Time (DRVVT) and Kaolin CLotting Time (KCT). Median DRVVT ratios were 1.75, 1.17 and 1.10 for the three samples. The presence of a strong LA was not detected by 4% of laboratories. The correct diagnosis was made by 94% of users of DRVVT and 85% of users of KCT. A weak LA was not detected by over half of centres. Correction was observed on addition of plasma and also in platelet neutralisation. The correct diagnosis was made by 37% of users of DRVVT and 27% of users of KCT. Lupus Anticoagulant was falsely considered to be present in a Factor IX deficient plasma by approximately one quarter of laboratories. Amongst users of DRVVT and KCT absence of LA in this sample was correctly reported by 73% and 69% of centres respectively. The accuracy of testing for LA in the present study is suboptimal and this is likely to have important clinical consequences. There is clearly a need for greater conformity in the selection and performance of LA tests to facilitate accurate diagnosis of this important group of disorders.

Multilineage gene expression precedes commitment in the hemopoietic system

We have tested the hypothesis that multipotential hemopoietic stem and progenitor cells prime several different lineage-affiliated programs of gene activity prior to unilineage commitment and differentiation. Using single cell RT-PCR we show that erythroid (beta-globin) and myeloid (myeloperoxidase) gene expression programs can be initiated by the same cell prior to exclusive commitment to the erythroid or granulocytic lineages. Furthermore, the multipotential state is characterized by the coexpression of several lineage-affiliated cytokine receptors. These data support a model of hemopoietic lineage specification in which unilineage commitment is prefaced by a "promiscuous" phase of multilineage locus activation.

Potentially prothrombotic abnormalities of coagulation in benign intracranial hypertension

OBJECTIVE

Benign intracranial hypertension (BIH) may be caused by intracranial venous sinus thrombosis. Cerebral angiograms may, however, be normal in patients with BIH that are associated with conditions with an increased risk of venous thrombosis. This raises the possibility that unrecognised non-occlusive venous thrombus might impede CSF drainage. This study therefore examined the strength of the association between risk factors for thrombosis and BIH.

METHODS

The incidence of prothrombotic abnormalities among a mixed prospectively and retrospectively investigated cohort of 38 patients with BIH, was compared with healthy obese subjects, and patients with other neurological diseases. Prothrombotic abnormalities investigated included anticardiolipin antibodies, lupus anticoagulant, antithrombin III, proteins C and S, plasma fibrinogen, kaolin cephalin clotting time, prothrombin time, and full blood counts.

RESULTS

Evidence for the presence of an antiphospholipid antibody was found in 32% of cases. Cases of familial deficiency of antithrombin III, thrombocytosis, and polycythaemia were also noted. Additionally, an increased concentration of plasma fibrinogen was found in 26%. A coagulation abnormality was more often detectable in those subjects with normal or low body mass index and in those tested within six months of onset.

CONCLUSION

There is a thrombotic pathogenesis in some cases of BIH.

Emergency oral anticoagulant reversal: the relative efficacy of infusions of fresh frozen plasma and clotting factor concentrate on correction of the coagulopathy

Haemorrhage, including intracranial bleeding, is a common, potentially lethal complication of warfarin therapy and rapid and complete reversal of anticoagulation may be life-saving. Fresh frozen plasma (FFP) and vitamin K are most frequently administered. Because of the variable content of vitamin K-dependent clotting factors in FFP, and the effects of dilution, the efficacy of this approach is open to doubt. We have therefore compared the effects of FFP and clotting factor concentrates on the INRs and clotting factor levels of orally anticoagulated subjects requiring rapid correction of their haemostatic defect. In many, the pre-treatment INR was considered to be dangerously above the target therapeutic range. In the 12 patients given FFP, the INR did not completely correct (range 1.6-3.8, mean 2.3) indicating an ongoing anticoagulated state in all. In contrast, the INR in 29 subjects given clotting factor concentrates was completely corrected in 28 (range 0.9-3.8, mean 1.3). Following treatment, marked differences were observed in clotting factor IX levels between the two groups. The median factor IX level was 19 u/dl (range 10-63) following FFP infusion and 68.5 u/dl (range 31-111) following concentrate. In FFP treated patients, poorer responses were also observed for each of the other vitamin K-dependent clotting factors but these were less marked than for factor IX, which was present in low concentrations in some batches of FFP. Thus, haemostatically effective levels of factor IX cannot be achieved, in most instances, by the conventional use of FFP in patients requiring reversal of their anticoagulant therapy. Clotting factor concentrates are the only effective option where complete and immediate correction of the coagulation defect is indicated in orally anticoagulated patients with life or limb-threatening haemorrhage.

Absence of p53 permits propagation of mutant cells following genotoxic damage

Much evidence has been gathered in support of a critical role for p53 in the cellular response to DNA damage. p53 dysfunction is associated with progression and poor prognosis of many human cancers and with a high incidence of tumours in p53 knockout mice. The absence of a p53-dependent G1 arrest that facilitates DNA repair or apoptosis might impact critically on clinical cancer in two ways. First, by abrogating the impact on therapy that operates via genotoxic damage and apoptosis; and second, by encouraging progression either by inducing genomic instability and DNA mis-repair or by permitting survival of mutants. However, experiments examining the relationship between p53 deficiency and mutation frequency have so far failed to confirm these predictions. The precise role played by p53 is therefore unclear. We now report use of a short term in vitro approach to assess the influence of p53 on radiation-induced mutations at the hprt locus in murine B cell precursors that are normally radiation ultrasensitive. We find a high number of hprt mutants among X-irradiated p53 null cells, which results from preferential survival as clonogenic mutants rather than from a p53-dependent increase in mutation rate. This result has important implications for genotoxic cancer therapy.

An evaluation and improvement program for inpatient anticoagulant control

To improve the management and therapeutic control of inpatients on anticoagulant drugs, combined prescription and monitoring charts have been developed for both heparin and warfarin which incorporate clinical guidelines. These have been introduced throughout a 700-bedded acute teaching hospital via a structured program of change management. We have demonstrated improvements in the quality of anticoagulant control (assessed with a custom-written computer program), adherence to clinical guidelines and quality of monitoring and prescribing of anticoagulants in inpatients. The percentage time spent under-anticoagulated with heparin (activated partial thromboplastin time ratio < 1.5) fell from 32.7% to 18.5% (p < 0.0001), whereas there was no change in percentage time over-anticoagulated (5.1% vs. 5.8%; p = ns). The percentage time spent under-anticoagulated with warfarin was unaltered (26.3% vs. 29.8%; p = ns) but the percentage time spent over-anticoagulated (International Normalised Ratio > 4.5) was halved from 5.4% to 2.7% (p < 0.001). We conclude that the introduction of the charts led to significant improvements in anticoagulant control.

Monoclonal origin of concordant T-cell malignancy in identical twins

Acute leukemia has a high concordance rate in young identical twins and in infants this is known, from molecular analysis, to reflect an in utero origin in one twin followed by prenatal metastasis to the other twin via intraplacental anastomoses. The situation in older twins with leukemia has been less clear. We describe a pair of identical twins who were diagnosed with a T-cell malignancy at 9 and 11 years of age, one with T-cell non-Hodgkin's lymphoma and the other with T-cell acute lymphoblastic leukemia. Leukemic cells from the twins shared the same TCR beta gene rearrangement with an identical 11 bp N region. The most plausible interpretation of this result is that these malignancies were initiated in one twin fetus in utero, in a single T-lineage cell that had stable bi-allelic TCR beta rearrangements. Progeny of this cell then spread to the other twin before birth via shared placental vasculature. This was then followed by a 9- and 11-year preleukemic latent period before clinical disease manifestation as leukemia or lymphoma. This result has considerable implications for the etiology and natural history of pediatric leukemia.

Haemoglobin Hallamshire (beta146 HIS --> TYR): a new high oxygen affinity haemoglobin responsible for familial erythrocytosis

A new high oxygen affinity haemoglobin with the beta chain mutation beta146 HIS --> TYR is described. This variant was detected in a fit 34-year-old man with true erythrocytosis. The abnormal haemoglobin was identified as an extra band on cellulose acetate electrophoresis at pH 6.3 and was later confirmed by beta globin gene sequencing and oxygen dissociation studies. Whole blood containing Haemoglobin Hallamshire has a P50 of 18 mmHg. This newly described haemoglobin variant was also responsible for erythrocytosis in the mother and maternal half cousin of the index case. The identification of Haemoglobin Hallamshire provides confirmatory evidence of the important role of the C-terminal end of the chain in haemoglobin function.

The microvasculature in myeloproliferative disease. A study using retinal fluorescein angiography

Microvascular occlusion is known to be a feature of myeloproliferative diseases. Acute manifestations are well documented in individuals causing a variety of symptoms. However, it is not known whether ongoing microvascular changes are present in asymptomatic individuals. We investigated this further by using retinal intravenous fluorescein angiography to image the microvasculature in patients with myeloproliferative disease. In our group of patients fluorescein angiography did not show any ongoing microvascular damage. There appears to be no intrinsic retinal vasculopathy in patients with myeloproliferative disease, suggesting that acute symptomatic events are caused by microemboli in an otherwise normal vascular tree.

Antibodies to membranes of endothelial cells and fibroblasts in scleroderma

Anti-endothelial and other cell membrane-reactive antibodies in scleroderma were characterized by immunoblotting sera with membrane and cytosol preparations of human umbilical vein endothelial cells (HUVEC), dermal fibroblasts and a T cell lymphoma HUT78. Antibodies reactive with HUVEC membranes were found in 17 of 20 patients with scleroderma (33 bands) in contrast to only two of 20 controls (two bands; P < 0.01) and three of 11 patients with myocardial infarction (four bands). Eleven of the 20 patients possessed antibodies that were specific for HUVEC membrane and did not cross-react with other cell lines. Analysis of patient subgroups showed that HUVEC membrane antibodies were present in nine of 11 patients with systemic sclerosis and in all nine with the CREST syndrome, and were HUVEC-specific in five and six of these cases, respectively. Although considerable heterogeneity was seen, antibodies to an 18-19-kD membrane epitope were found in 11 of the 20 patients but in none of the controls (P < 0.01). This antibody which reacted particularly with HUVEC (n = 9) and HUT78 membranes (n = 9) was associated with CREST syndrome rather than systemic sclerosis (9/9 versus 1/11; P < 0.01), and after elution was shown to possess anticentromere activity. In addition, antibodies reactive with both fibroblast (n = 11; 18 bands) and HUT78 membranes (n = 18; 42 bands) were detected and were specific for either fibroblast or HUT78 membranes in nine and 14 patients, respectively. There was no significant difference in the incidence of these fibroblasts and HUT78 membrane antibodies in the two patient subgroups. These findings support the concept that membrane-reactive antibodies, including anticentromeric antibodies, may play a central role in the pathogenesis of scleroderma, through their ability to react with endothelial cells.

Further characterization of anti-endothelial cell antibodies in systemic lupus erythematosus by controlled immunoblotting

Anti-endothelial cell antibodies in systemic lupus erythematosus were further characterized by controlled immunoblotting studies with EN4 defined membrane and cytosol preparations of human umbilical vein endothelial cells. Antibodies to endothelial cell membranes, some of which reacted with the membranes of both dermal fibroblasts and T-cell lymphoma HUT78, were detected in 26/33 patients (78%), but in only 4/34 normal controls (P < 0.001) and 3/11 patients with a recent myocardial infarction. Although the antibody response was very heterogeneous against epitopes ranging from 17 to 205 kDa, there was a tendency to detect particular membrane epitopes at 31-33 kDa (15 cases), 72-78 kDa (eight cases), 66-68 kDa (seven cases) and 17-19 kDa (five cases). No correlations between antibodies to particular epitopes and disease manifestations were observed nor was a relationship to disease activity detected in a retrospective analysis. However, the possibility that anti-endothelial cell antibodies may be pathogenically important was supported by prospective serial studies in two cases with nephritis who showed diminution and disappearance of anti-endothelial cell antibodies as their active disease was treated into remission.

In Situ Combustion Isc Process Using Horizontal Wells

Abstract

A series of dry in situ combustion experiments, and a single wet combustion experiment, have been carried out on heavy Wolf Lake crude oil using a rectangular 3D combustion cell measuring DAD m by DAD m by 0.10 m deep. Three different well configurations were used: (1) VIHP-a vertical injector with horizontal producer; (2) HIHP-a horizontal injector placed normal to a horizontal producer; and (3) parallel HIHP-a horizontal injector parallel with a horizontal producer. AIl of the horizontal producer wells were placed in a line drive arrangement. A matrix of 60 thermocouples was used to obtain temperature profile information, in the vertical mid-plane and horizontal top, bottom and mid-planes of the oil layer. The experiments used sandpacks containing a high saturation of heavy crude oil, 80%. The injected gas was either air, or enriched air containing 35% oxygen.

Combustion peak temperatures up to 747 °C were recorded for the dry combustion tests, and up to 531 °C for the wet combustion test. High oil recoveries were achieved duririg dry combustion, ranging from 64.3 to 72.3% oorP, and 78.8% OOIP during wet combustion. The type of injection well, and its placement with respect to the horizontal producer well, had a very significant influence on the width of the combustion front formed initially, following ignition. This subsequently also had a significant effect on the propagation of the combustion front. In the case when the horizontal injector was placed normal to the horizontal producer (HIHP), the combustion front was formed across the entire width of the sandpack.

During the dry combustion tests it was noticeable that the size of the high temperature region tended to diminish with an increase in combustion time, regardless of the extent of the combustion formed initially. However, no reduction in size of the high temperature region occurred during wet combustion, which exhibited an almost total ‘sweep-out’ of the stored heat behind the combustion front.

Gas override condition was not a major problem using the horizontal producer well in direct line drive. The volumetric sweep efficiencies calculated from the vertical and horizontal temperature profiles were generally in good agreement with the measured oil recovery values, indicating almost complete recovery of oil from the swept regions of the sandpack.

The oil produced by in situ combustion was substantially upgraded, with the API gravity increasing in the range 17.3 to 20.5 °API compared to 10.95 °API for Wolf Lake crude.

Introduction

There are three major reasons why over half the oil in place in the average reservoir is unrecoverable by conventional production methods. First, only a portion of any reservoir can be contacted by the displacing fluid due to the geophysical and hydrodynamical complexity of the reservoir formation. Second, not all of the oil can be displaced from the reservoir rock that is contacted by the displacing fluid because of the physicochemical ‘trapping’ forces. Third, heavier, low gravity oils are frequently too viscous to move to the production well at rates sufficient to support an economic operation.

Discordant clinical presentation and outcome in infant twins sharing a common clonal leukaemia

We report the different presentation features and clinical outcome between two identical infant twins with acute lymphoblastic leukaemia with a shared clonal disease and MLL gene rearrangement. One twin relapsed and died, but the other is in complete remission > 4 years after diagnosis. These data, and similar observations on other twin infants with leukaemia, suggest that despite a common clonal in utero, post-natally these leukaemias can evolve independently, at different rates, in the twinned individuals, and that the usually fatal leukaemia associated with t(4;11) MLL gene rearrangement can be effectively treated when the leukaemic burden is small.

A concept-based retrieval system for thoracic radiology

Current digital information systems in radiology are insufficient to accommodate the retrieval needs of academicians. Significant efforts are required in retrieving clinical cases for teaching and research. We describe a prototype system that supports intelligent case retrieval based on a combined specification of patient demographics, radiologic findings, and pathologic diagnoses. The documents for these cases can be distributed among multiple heterogeneous data bases. The system features automatic indexing of radiology and pathology reports, a comprehensive lexicon for thoracic radiology, an interface to a hospital information system, radiology information system, and picture archiving and communication systems, and a graphical user interface for query formulation and results visualization. The prototype system was developed within the domain of thoracic radiology involving patients with lung cancer.

The stem cell antigen CD34 functions as a regulator of hemopoietic cell adhesion

Although the CD34 antigen is widely used in the identification and purification of hemopoietic stem and progenitor cells, its function within hemopoiesis is unknown. We have investigated this issue by ectopically expressing human (hu) CD34 on the surface of murine hemopoietic cells. Forced expression of hu-CD34 in the thymocytes of transgenic mice did not appear to affect the development, maturation, or distribution of murine T cells but did significantly increase their ability to adhere to bone marrow stromal layers of human but not mouse origin. Ectopic expression of hu-CD34 on murine 416B cells, a multipotential progenitor that expresses murine CD34, yielded similar results. In both cases hu-CD34-dependent adhesion was enhanced by molecular engagement of the hu-CD34 protein using anti-CD34 antibodies. These results provide evidence that CD34 promotes the adhesive interactions of hemopoietic cells with the stromal microenvironment of the bone marrow thereby implicating CD34 in regulation and compartmentalization of stem cells. We propose that CD34 regulates these processes in part via an indirect mechanism, signaling changes in cellular adhesion in response to molecular recognition of an as yet unidentified stromal CD34 counterreceptor or ligand.

Characterization and specificity of anti-endothelial cell membrane antibodies and their relationship to thrombosis in primary antiphospholipid syndrome (APS)

Immunoblotting was used to detect antibodies reacting with membrane and cytosol preparations of human umbilical vein endothelial cells (HUVEC), fibroblasts and a T lymphoma line HUT78 in 18 patients with anticardiolipin antibodies (ACA) (14 of whom had had a thrombotic event), 11 patients with a recent myocardial infarction and 17 controls. Multiple membrane-specific antibodies to HUVEC were found in 10 of the patients with ACA (28 bands) and in nine of the patients with thromboses (27 bands) in contrast to only three of the patients with myocardial infarction (four bands) and one control (one band). The most frequently recognized HUVEC membrane epitopes were at 33 kD (four sera), 61-63 kD (five sera) and 76-79 kD (four sera). Although cross-reactivity with fibroblast and/or HUT78 membranes was seen at 33 kD, binding at 61-63 kD and 76-79 kD was specific for endothelial membranes. Although no correlations with the presence and titre of ACA were seen, HUVEC membrane-specific antibodies showed a correlation with venous thrombotic events.

A radiation hybrid panel for human chromosome 6q

A panel of 63 radiation-reduced hybrids has been derived from a mouse cell line containing a neo-marked human Chromosome (Chr) 6, primarily to provide a resource for higher resolution localization of new markers. Hybrids were generated with radiation doses of 40-400 Gy, selected in G418, and were shown by PCR to contain the neo gene. PCR was also used to score the retention of 15 loci that map from 6q13 to q25.2 of the current consensus map, plus six other loci assigned to 6q26-q27. An average retention frequency of 27.8% was observed, with the highest frequencies at D6S313 and D6S280 (63.5%) located near the centromere at 6q13, and at D6S283 (68.5%) at 6q16.3-q21, presumably close to the neo integration site. Lowest frequencies (4.8%) were observed for telomeric markers. All markers segregated independently except D6S297 and D6S193. Agreement and some improvement to the current consensus map of 6q was made by mapping 12 loci by the non-parametric statistical method of Falk. In addition, deletion mapping with informative hybrids allowed the ordering of six loci from 6q26 to q27 and permitted some integration of maps of this region.

Livedo reticularis associated with hereditary protein C deficiency and recurrent thromboembolism

We report the occurrence of livedo reticularis in a patient with symptomatic hereditary type 1 protein C deficiency. Antithrombin III deficiency and the antiphospholipid syndrome may also be associated with livedo reticularis, and we suggest that a thrombophilia screen may be a useful investigation in a patient with otherwise unexplained livedo, particularly if there is a personal or family history of thromboembolism.

The development of antiphospholipid antibodies in haemophilia is linked to infection with hepatitis C

In haemophilia the presence of antibodies to antiphospholipid has been linked with HIV infection, but other possibilities have not been fully explored and the specificity for various phospholipids not established. In order to investigate further the pathogenesis and clinical significance of these antibodies, we have determined IgG and IgM antibodies to a variety of phospholipids, including cardiolipin, in the serum of 52 haemophiliacs, and related our findings to the presence of antibodies to HIV and hepatitis C virus (HCV), as well as to clotting factor concentrate usage and blood markers of liver biochemistry. Our results demonstrate that the presence of infection with hepatitis C virus is strongly associated with raised serum levels of antiphospholipid antibody even in the absence of HIV infection. They suggest that earlier conclusions on the relationships of antiphospholipid to HIV infection in haemophilia should be revised and that chronic infection with the hepatitis C virus should be added to the list of infective causes for the development of antiphospholipid antibody.