Interleukin 7-dependent B lymphocyte precursor cells are ultrasensitive to apoptosis

We have compared the sensitivity of clonogenic interleukin 7 (IL-7)-dependent murine B cell precursors with that of clonogenic mature B cells and myeloid precursors to alpha-particles from plutonium-238 and X radiation. All three populations are relatively sensitive, but B cell precursors are ultrasensitive. This differential sensitivity is also observed with corticosteroid, etoposide, and cisplatin, all apoptosis-inducing drugs used in the treatment of leukemia and other cancers. Further, we show that x-rays and drugs induce the bulk of the B cell precursor population to undergo rapid apoptosis, despite the continued presence of IL-7. B cell precursors were found to express very low levels of BCL-2 protein compared with mature splenic B cells and their resistance to x-rays and corticosteroid could be enhanced by expression of a BCL-2 transgene. These data have important implications for normal lymphopoiesis and for the behavior of leukemic lymphoid precursor cells.

Reversal of diabetes associated with escape of myeloma: evidence for inappropriate IGF-II secretion

We report the sudden and dramatic reversal of maturity onset diabetes in a 57-year-old woman in association with relapse of IgA myeloma diagnosed 3 years earlier. Prior to the relapse of the myeloma, twice daily insulin had been administered at a dose which had been stable for 3 years. However, the same dose produced hypoglycaemic coma at the time of relapse and, subsequently, blood glucose was controlled by diet alone. There had been no significant change in weight or renal function prior to the hypoglycaemic episode. Investigations showed a suppressed fasting serum insulin level in association with an inappropriately high serum level of IGF-II compared with IGF-I and a 'big' IGF-II concentration at the upper end of the normal range. Pituitary, adrenal and liver disease, as well as the autoimmune insulin syndrome, were excluded. The findings are consistent with the hypothesis that the plasma cell tumour was associated with excessive production of insulin-like peptides with consequent reduction in the blood glucose level.

High resolution computed tomography of the lungs in patients with rheumatoid arthritis and interstitial lung disease

We performed high resolution computed tomography (HRCT) on the lungs of 20 patients with RA and clinical and radiological evidence of interstitial lung disease (ILD). A case control group of patients with RA but without evidence of ILD were similarly studied and all patients underwent detailed pulmonary function testing. Clinical findings, drug therapy, smoking status, the presence/absence of SS and disease activity were also assessed. HRCT showed a range of abnormalities among patients thought to have ILD. Interstitial fibrosis was confirmed in 16 but was frequently associated with emphysema. Ground glass opacification was present in seven, while basal honey-combing was also evident in seven patients. Both these features were present in two patients with ILD. Bronchiectasis was identified in six patients and was the predominant finding in two patients previously thought to have ILD. Among the control patients, HRCT was normal in only five. Clinically unsuspected ILD was present in four patients, while a further four had bronchiectasis. Pleural disease was identified in seven controls. Pulmonary function tests were generally poor predictors of HRCT findings, although a reduced residual volume (RV) [> 1 S.D.] was 83% specific for the presence of ILD and a raised RV [> 1 S.D.] was 64% specific for emphysema. Smoking did not correlate with the presence of either ILD or emphysema and there were no correlations between disease activity and HRCT findings. RA patients with evidence of ILD have abnormalities on HRCT which cannot be confidently predicted on any other non-invasive test.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of prostacyclin release by endothelial binding anticardiolipin antibodies in thrombosis-prone patients with systemic lupus erythematosus and the antiphospholipid syndrome

IgG from 18 patients with SLE, eight with the primary antiphospholipid syndrome and 19 controls was examined for its effect on thrombin-induced prostacyclin (PGI2) release from human umbilical vein endothelial cells in relation to both the titre of anticardiolipin (ACA) and antiendothelial activity (AEA) and clinical thrombotic events. Although no significant inhibition of PGI2 release was found overall, examination of subgroups revealed that IgG from patients with ACA produced significant inhibition of PGI2 release (mean stimulation index IgGM, 0.74 +/- 0.12, P = 0.02) when compared with patients without ACA (1.18 +/- 0.12). Further analysis revealed a significant positive correlation between ACA and AEA (r = 0.52, P = 0.006) in the total patient group which was reflected in significant negative correlations between inhibition of PGI2 release and increasing titre of both ACA (r = -0.42, P = 0.032) and AEA (r = -0.57, P = 0.002). However, only increasing titre of AEA showed a significant negative correlation with inhibition of PGI2 release when patients with (r = -0.74, P = 0.0005) and without (r = 0.23, N.S.) thromboses were compared. The titre of ACA failed to show any significant correlation with inhibition of PGI2 release in either patients with (r = -0.42, N.S.) or without (r = -0.16, N.S.) thromboses. These findings suggest that previous, sometimes conflicting, reports of an association between inhibition of PGI2 release and ACA may be explained by the co-incidence of AEA with ACA.

Use of granulocyte colony-stimulating factor (G-CSF) for mobilizing peripheral blood stem cells: risk of mobilizing clonal myeloma cells in patients with bone marrow infiltration

Peripheral blood stem cells have been used for autologous reconstitution of haemopoiesis after high dose cytotoxic therapy and produce similar disease response rates as autologous bone marrow transplants. Peripheral blood stem cell transplants are an especially attractive option for patients in whom marrow harvest is not feasible due to bone marrow damage or infiltration. Recombinant growth factors mobilize adequate numbers of stem cells from the marrow but their effect on tumour cell circulation kinetics is not known. We report a patient with multiple myeloma and bone marrow infiltration in whom the use of G-CSF for stem cell mobilization led to release of plasma cells into the peripheral circulation and contamination of the stem cell harvest.

Thromboxane and prostacyclin synthesis in experimental pancreas transplantation. Changes in parenchymal and vascular prostanoids

The principal causes of failure of a pancreas transplant are rejection and vascular thrombosis. There is an unusually high attrition rate for pancreas transplants, but study models have been difficult to develop. In a rat model that allows study of acute rejection to the exclusion of nonspecific effects of transplant surgery on the pancreas, in vitro synthesis of prostacyclin (PGI2) and thromboxane A2 (TXA2) by transplanted pancreas and the blood vessels transplanted with it was measured using an RIA for their stable hydrolysis products 6-keto-prostaglandin F1 alpha and thromboxane B2 (TXB2). TXB2 synthesis was significantly greater in allotransplanted pancreas than isotransplanted pancreas from the 5th day after transplantation. Rejection was complete in the allografted group 7-9 days after transplantation. 6-Keto-prostaglandin F1 alpha synthesis was similar in the pancreas for both allografts and isografts. Similar changes were seen in aorta, celiac artery, superior mesenteric artery, and portal vein transplanted with the pancreas. In the transplanted aorta, TXB2 was significantly greater in the allograft group from the third posttransplant day. A group of CsA-treated allografts sampled after 9 days had transplanted pancreatic parenchymal and vascular prostanoid synthesis in the isograft range. The changes in PGI2 and TXA2 synthesis that accompany cellular rejection may mediate vascular failure in rejecting pancreas transplants, and changes in PGI2 and TXA2 synthesis in blood vessels transplanted with the pancreas could promote early vascular thrombosis.

The fate of circulating megakaryocytes during cardiopulmonary bypass

Megakaryocytes with intact cytoplasm normally leave the bone marrow, enter central venous blood, and are filtered in the lungs. During cardiopulmonary bypass, large megakaryocytes are not filtered by the lungs and may not be removed in the extracorporeal circuit by arterial line filters. In such circumstances, they could enter the systemic circulation and block smaller cerebral vessels, resulting in neurologic impairment. To investigate the fate of circulating megakaryocytes during cardiopulmonary bypass, central venous blood and oxygenated blood samples before and after arterial line filtration (40 microns polyester screen filter) were obtained from 10 patients undergoing cardiopulmonary bypass. Megakaryocytes were isolated by whole blood filtration and identified by their characteristic structure after May-Grunwald-Giemsa staining. In preliminary studies, megakaryocyte identification was verified by immunolabeling. All samples contained megakaryocytes with copious cytoplasm. Their frequencies in central venous blood and oxygenated blood before and after the arterial line filtration (corrected for hemodilution) were 23.4 +/- 9.3 per milliliter (mean +/- standard error of the mean, range 3.1 to 89.7 per milliliter), 21.0 +/- 8.2 per milliliter (2.0 to 84.2 per milliliter) and 17.1 +/- 7.4 per milliliter (3.1 to 80.4 per milliliter), respectively. Megakaryocytes with scant or no visible cytoplasm were also observed. The results confirm that circulating megakaryocytes are a normal physiologic component. During cardiopulmonary bypass, megakaryocytes with copious cytoplasm (mean diameter 42.7 microns, range 22 to 78 microns) can pass through the extracorporeal circuit. In the absence of filtration by the lungs, these large cells have access to the systemic circulation. This study supports a possible role for circulating megakaryocytes in the development of cerebral dysfunction after cardiopulmonary bypass.

Anticoagulants in pregnancy

Pregnancy is associated with a prethrombotic state. Pulmonary embolism is the major cause of maternal mortality. Anticoagulant prophylaxis and therapy are therefore commonplace in pregnant women. Those with inherited and acquired thrombophilic conditions are at increased risk and special considerations arise in management. Heparin has recently become the favoured anticoagulant drug in pregnancy. Its use carries risks of osteopaenia and thrombocytopaenia, as well as haemorrhage, in the mother. Warfarin is teratogenic and may also cause haemorrhagic complications in mother and fetus. Few clinical trial data exists for guidance on optimal anticoagulant regimes during pregnancy and the puerperium and details of management will depend upon the personal preferences of patient and clinician, after due consideration of the perceived risks and benefits in the individual clinical situation.

In utero rearrangements in the trithorax-related oncogene in infant leukaemias

The majority (approximately 75%) of infant acute leukaemias have a reciprocal translocation between chromosome 11q23 and one of several partner chromosomes. The gene at 11q23 (named MLL, ALL-1, HRX or HTRX-1; refs 2-6) has been cloned and shares homology with the Drosophila developmental gene trithorax. Rearrangements of this gene (called HRX here) occur in introns and cluster in a region of approximately 10 kb; individual patients have different breakpoints. Here we describe three pairs of infant twins with concordant leukaemia who each share unique (clonal) but non-constitutive HRX rearrangements in their leukaemic cells, providing evidence that the leukaemogenic event originates in utero and unequivocal support for the intra-placental 'metastasis' hypothesis for leukaemia concordance in twins.

Coagulation abnormalities and cerebral infarction

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Horizontal Producer Wells In In Situ Combustion (ISC) Processes

Abstract

A simple 3-D physical model has been developed to investigate the use of horizontal producer wells in in situ combustion processes. The semi-scaled 3-D model was a rectangular box with 40 cm by 40 cm by 10 cm dimensions. Dry in situ combustion experiments were conducted with three different well configurations (1) a vertical injector and horizontal producer; (2) a vertical injector and two horizontal producers; and (3) injector and producer, both vertical. A matrix of 60 thermocouples was used to obtain temperature profile information, ill the vertical and horizontal mid-planes. Most experiments were conducted with sandpacks containing a high saturation of heavy crude oil SOi ≈ 0.80. For each horizontal well configuration, the effect of oxygen flux and oxygen enrichment (21% and 35% oxygen) was investigated.

Combustion peak temperatures up to 400 ºC were recorded, with oil recoveries exceeding 66% OOIP for the single horizontal producer well case. The recovery using two horizontal producer wells was 71.5% OOIP, higher than both the vertical producer and horizontal producer well cases. Generally, a much more stable propagation of the combustion front was observed for the single horizontal well vs single vertical well configuration. The vertical sweep especially was noticeably stabilized compared to the progressive tendency for gas override developing along the mid-plane of the vertical well experiment. Both single and double horizontal wells gave an earlier commencement of oil production and at a higher rate subsequently. However, the additional incremental oil recovery achieved by the double horizontal well was proportionately lower than indicated by theperformance of the single horizontal well, owing to interference between wells. At increased injected oxygen flux, the oil recovery reduced due to oxygen channelling through to the production end, causing higher rates of low-temperature oxidation ahead of the combustion from. Significant improvement of the combustion efficiency occurred with enriched air, but the oil recovery was lower due to higher fuel consumption. Overall, there was a very significant improvement in the quality of the produced oil using the horizontal well arrangement, Compared to that achieved with the single vertical well.

Introduction

The demand for crude oil and the increasing difficulty of discovering new large reservoirs, as well as the decrease in Conventional oil reserves, has generated special interest in heavy oil and tar sands. The high viscosities of heavy oils at reservoir conditions is the predominant factor limiting economic recovery. Any reduction in the oil viscosity will create an increase in oil mobility and therefore improve production. The most effective method of lowering the viscosity is by the application of heat to the reservoir. Heat may be introduced into the reservoir in the form of hot water, gases or steam lt may also be generated in situ by burning part of the oil in the reservoir, This process is known as in situ combustion or ISC.

Fireflooding or ISC is a thermal EOR method in which heat is generated within the reservoir by igniting the formation oil and then propagating a combustion front through the oil bearing media.

Stimulation of von Willebrand factor antigen release by immunoglobulin from thrombosis prone patients with systemic lupus erythematosus and the anti-phospholipid syndrome

The level of von Willebrand factor antigen (vWF) released by endothelial cells in response to IgG isolated from 18 patients with systemic lupus erythematosus (SLE), eight patients with the anti-phospholipid syndrome (APS) and 22 controls has been measured. Incubation with IgG from the combined patient group resulted in a significantly greater release of vWF (mean stimulation index +/- SEM, 4.57 +/- 0.78) when compared with controls (1.96 +/- 0.22, P = 0.003). Furthermore, IgG from 17 patients who had had a history of thrombosis induced higher levels of vWF release (5.33 +/- 1.09) when compared with the controls (P = 0.008). These findings suggest that IgG from patients with SLE or APS is capable of stimulating vWF release and that this ability may be implicated in the thrombotic events that are observed in these conditions.

Subcutaneous versus intravenous administration of heparin in the treatment of deep vein thrombosis; which do patients prefer? A randomized cross-over study

Patient preference for intravenous or subcutaneous heparin in the treatment of deep venous thrombosis was assessed in a randomized cross-over study. Twenty patients with venographically proven deep venous thrombosis were randomized to receive subcutaneous or intravenous heparin for 3 days followed by 3 days of the other treatment. Discomfort at the injection site, assessed by visual analogue scale, was significantly less for the subcutaneous than the intravenous administration route (P < 0.001), mobility was thought to be better when receiving subcutaneous heparin (P < 0.005) and patients' overall preference was for subcutaneous treatment (P < 0.001).

Relationships between haemostatic factors and capillary morphology in human diabetic neuropathy

We have examined haemostatic factors in 15 diabetic patients with peripheral neuropathy and 10 diabetic patients without clinical complications. Plasma and blood viscosity, fibrinogen, factor VIIIc, von Willebrand factor activity, spontaneous platelet aggregation and fibrinolytic activity were not significantly different between diabetic patients without clinical complications and diabetic patients with peripheral neuropathy. Platelet aggregation was enhanced in diabetic patients with neuropathy compared with those without complications. In the 15 patients with neuropathy and 3 without complications, who underwent biopsy of sural nerve, skin and muscle, associations were found between haemostatic variables and measures of nerve capillary pathology, notably: plasma fibrinogen and nerve capillary basement membrane thickness (r = 0.70, p < 0.001); thromboxane B2 production and nerve capillary basement membrane thickness (r = -0.61, p < 0.01); plasma fibrinolytic activity and endoneurial capillary lumen size (r = 0.60, p < 0.01) and endothelial cell outer perimeter (r = 0.65, p < 0.01). The main associations of skin and muscle capillary abnormalities were with measures of in vitro platelet aggregation, and the correlations found with nerve capillary measurements were not echoed in the overlying muscle and skin. The results are supportive of the involvement of haemostatic abnormalities in the pathogenesis of diabetic neuropathy.

Isolation of circulating megakaryocytes in man

Recovery of the small numbers of megakaryocytes (MKs) known to be present in normal blood is difficult because of their low frequency. Isolation of circulating MKs was achieved using a modified filtration system in which untreated blood was passed through 5 microns polycarbonate membranes. MKs were retained while most other blood cells passed through the membranes. Four groups of MKs were identified in May Grünwald-Giemsa stained filters of blood from peripheral, central and umbilical veins and umbilical arteries. Type 1 MKs were nuclei with no visible cytoplasm. Types 2, 3 and 4 were nuclei with increasing amounts of cytoplasm. Type 4 MKs, possessing copious cytoplasm, were rarely isolated from peripheral venous blood but were more regularly encountered in central venous and cord blood. Filtration of whole blood through polycarbonate membranes is a useful technique for the isolation of circulating MKs, which are a normal physiological occurrence. Their presence is consistent with the production of platelets in the placenta during intra-uterine life, and subsequently in the pulmonary circulation.