Erythroid marrow function in anemic patients

Erythropoietic activity is known to be closely associated with marrow iron uptake. A modification of the standard measure of plasma iron turnover has been developed in which erythron transferrin uptake (ETU) rather than iron uptake has been calculated. The ETU has the advantage of providing a parameter of erythroid marrow activity independent of change produced by plasma iron and transferrin saturation. Measurements in 80 patients with anemia were compared to the normal value of 60 +/- 12 mumol/L whole blood/d. The mean ETU for ten patients with severe aplastic anemia and for six patients with pure red-cell aplasia were 12 +/- 8 and 12 +/- 11 mumol/L whole blood/d, respectively. In ten transfusion-dependent patients with renal failure under dialysis therapy, the mean value was 35 +/- 11, while ten other dialyzed patients who were transfusion independent had a mean ETU of 73 +/- 21 mumol/L whole blood/d. Sixteen patients with hemolytic anemia had an average ETU of 400 +/- 130, while 28 patients with ineffective erythropoiesis had a mean value of 474 +/- 147 mumol/L whole blood/d. While patients with hypoproliferative anemia showed no relation between the severity of anemia and ETU, those with hyperproliferative erythroid marrow showed increasing values as the anemia became more severe. Sequential measurements in patients with aplastic anemia under treatment and in thalassemic patients under transfusion therapy showed the value of this measurement in monitoring the effects of treatment on erythroid marrow activity. It is concluded that the measurement of ETU provides a more direct ferrokinetic evaluation of erythroid activity in anemic states.     

Role of plasminogen activator inhibitor-1 in promoting fibrin deposition in rabbits infused with ancrod or thrombin

The role of defective fibrinolysis caused by elevated activity of plasminogen activator inhibitor-1 (PAI-1) in promoting fibrin deposition in vivo has not been well established. The present study compared the efficacy of thrombin or ancrod, a venom-derived enzyme that clots fibrinogen, to induce fibrin formation in rabbits with elevated PAI-1 levels. One set of male New Zealand rabbits received intravenous endotoxin to increase endogenous PAI-1 activity followed by a 1-hour infusion of ancrod or thrombin; another set of normal rabbits received intravenous human recombinant PAI-1 (rPAI-1) during an infusion of ancrod or thrombin. Thirty minutes after the end of the infusion, renal fibrin deposition was assessed by histopathology. Animals receiving endotoxin, rPAI-1, ancrod, or thrombin alone did not develop renal thrombi. All endotoxin-treated rabbits developed fibrin deposition when infused with ancrod (n = 4) or thrombin (n = 6). Fibrin deposition occurred in 7 of 7 rabbits receiving both rPAI-1 and ancrod and in only 1 of 6 receiving rPAI-1 and thrombin (P < .01). In vitro, thrombin but not ancrod was inactivated by normal rabbit plasma and by purified antithrombin III or thrombomodulin. The data indicate that elevated levels of PAI-1 promote fibrin deposition in rabbits infused with ancrod but not with thrombin. In endotoxin-treated rabbits, fibrin deposition that occurs with thrombin infusion may be caused by decreased inhibition of procoagulant activity and not increased PAI-1 activity.     

Identification of T lymphocytes in human mixed hemopoietic colonies

The addition of a T-cell growth-promoting medium (PHA-TCM) to culture conditions that support growth of multi-lineage hemopoietic colonies enhances the proliferation of cells with lymphoid morphology within these colonies. These cells were identified as T lymphocytes by their ability to form rosettes with SRBC and their reaction with monoclonal antibodies (OKT3, OKT4) directed against T-cell-specific surface components. They continue to proliferate extensively under the influence of PHA-TCM after transfer of mixed colonies into liquid suspension culture. Supportive evidence for a common progenitor of myeloid and lymphoid cells within single mixed colonies is provided by Y-chromatin body analysis of E-rosette positive and negative cells in colonies grown in cocultures of male and female bone marrow cells.     

Reversal of granulocyte adherence to nylon fibers using local anesthetic agents: possible application to filtration leukapheresis

The effects of the cationic anesthetic agents tetracaine and lidocaine on granulocyte function, morphology, and adherence to nylon fibers were studied in an attempt to improve current methods of granulocyte collection by filtration leukapheresis (FL). When dissolved in acid- citrate-dextrose (ACD) plasma, these drugs significantly increased granulocyte elution from the fibers in a dose-related fashion. Granulocytes exposed to tetracaine and lidocaine remained more than 95% viable, retained normal bactericidal capacity after the drugs were washed from the cells, and had preserved membrane integrity, as evidenced by the normal ultrastructural appearance of tetracaine- exposed cells and an absence of leakage of lysozyme or lactic dehydrogenase. Granulocytes eluted with the anesthetic agents were rounded in shape with a reduction in the number of filopodial cytoplasmic projections and a relative absence of cytoplasmic vacuolization when compared to granulocytes eluted with ACD plasma alone. Dose-related inhibition of phagocytosis and adherence, which was largely reversible after washing the granulocytes, was noted. Greater than 95% of the lidocaine could be removed from the eluate with a single centrifugation and resuspension, indicating that granulocytes prepared by FL with anesthetic-enhanced elution could be potentially transfusable.     

Determination of Acoustic Cavitation Probabilities and Thresholds Using a Single Focusing Transducer to Induce and Detect Acoustic Cavitation Events: II. Systematic Investigation in an Agar Material

In the accompanying article (Part I), a method is described to determine acoustic cavitation probabilities in tissue-mimicking materials (TMMs) using a high-intensity focused ultrasound (HIFU) transducer for both inducing and detecting the acoustic cavitation events, and its suitability for different sonication modes like continuous wave, single pulses (with pulse lengths from microseconds to milliseconds) and repeated burst signals is discussed. In Part II, the use of the method for a systematic study of the dependence of the acoustic cavitation thresholds in 3% (by weight) agar phantoms on the temporal sonication parameters is discussed. The values obtained at a frequency of 1.06?MHz, ranging from (0.58?±?0.12)?MPa for a 3-s continuous wave mode sonication to (5.2?±?1.0)?MPa for single shots with a length of 10 wave cycles, are discussed and interpreted on the basis of literature values and their self-consistency.     

Effect of angiotensin II on plasma ACTH in patients with Addison's disease

Short-term angiotensin II (AII) infusions (3 ng/kg/min) were performed in 5 patients with Addison's disease in order to assess the effect of AII on ACTH secretion. Base line ACTH levels were elevated due to a 9-h time lag between hydrocortisone administration and onset of the study. In 2 separate infusion periods of 30-min duration, AII had no unidirectional effect on plasma ACTH. Mean ACTH increased slightly but insignificantly. Mean blood pressure rose by about 10 mmHg. The degree of angiotensinaemia induced is probably similar to the state of moderate to severe sodium deficiency. Short-term changes of AII in this order of magnitude have obviously no major effect on ACTH secretion.     

Long term survival after pancreatic resection for pancreatic adenocarcinoma

OBJECTIVE: The aim of this study was to determine the long term survival of patients with pancreatic adenocarcinoma who underwent surgical resection and to assess the association of clinical, pathological, and treatment features with survival. METHODS: Between January, 1990, and December, 1998, 125 patients underwent a pancreaticoduodenal or partial pancreatic resection for pancreatic ductal adenocarcinoma at our institution. The records of these patients were reviewed for demographics, tumor characteristics including size, histological grade, margin status, lymph node status, surgical TNM staging, and postoperative adjuvant therapy. The primary outcome variable analyzed was survival. RESULTS: A total of 116 patients had complete follow-up and were included in the final analysis. The median survival after surgery was 16 months. The 1-, 3-, 5-, and 7-yr survival rates for all 116 patients were 60%, 23%, 19%, and 11%, respectively. The 1-, 3-, 5-, and 7-yr survival rates for patients who received adjuvant therapy were 69%, 28%, 23%, and 18% compared with 20% and 0% in patients who did not receive adjuvant therapy (p < 0.0001). The 1-, 3-, 5-, and 7-yr survival rates for patients with negative lymph nodes were 73%, 38%, 26%, and 22% compared with survival rates of 52%, 14%, 14%, and 9% in patients with positive lymph nodes (p = 0.01). In multivariate analyses, adjuvant therapy was the only feature found to be strongly associated with survival (hazards ratio = 0.26, 95% CI = 0.15-0.44). CONCLUSIONS: The overall 5- and 7-yr survival rates of 19% and 11% in our study further validate that surgical resection in patients with pancreatic adenocarcinoma can result in long term survival, particularly when performed in association with adjuvant chemoradiation.     

Influence of intercellular junctions on endothelin secretion of human umbilical vein endothelial cells in vitro

The endothelium plays a pivotal role in the theological regulation of blood flow by the secretion of vasoactive factors. The interaction between shear forces and the endothelium is determined by the mechanical properties of the endothelial cell layer which are associated with intercellular junctions. Cell-cell contacts could therefore modulate the secretion of vasocative factors in response to theological stimuli. We investigated the relationship between intercellular junctions and the secretion of the vasoconstrictor peptide endothelin and the coagulation co-factor von Willebrand factor (vWF). Human umbilical vein endothelial cells (HUVECs) were used as in vitro endothelial model system. Intercellular junctions were reversibly disrupted by calcium chelation or hypertonic stress; alternatively, the formation of intercellular junctions was inhibited by culturing the cells in suspension or by plating them in the presence of an inhibitory anti-VE-cadherin antibody. The opening of intercellular junctions was verified by assessing transmonolayer electrical resistance (TMR) and immunofluorescence morphology. The concentration of endothelin and vWF was measured in the cell culture supernatants using specific ELISAs. The secretion of endothelin was inhibited by EGTA (5 mM) and stimulated by incubation with tumor necrosis factor α (TNFα, 40 ng/ml). Treatment with hypertonic medium (glycerol, 1200 mosmol/l) for 10 minutes opened intercellular junctions and markedly reduced the secretion of endothelin. HUVECs in suspension culture did not secrete endothelin and failed to respond to TNFα, but readily resumed these functions upon forming a new monolayer on plastic. The reconstitution of intercellular junctions after suspension culture could be inhibited using a specific anti-VE-cadherin antibody. This antibody, but not a non-specific anti-humanIgG antibody reduced endothelin secretion. The secretion of von Willebrand Factor was less dependent on intercellular junctions. The opening of intercellular junctions did not induce cell death, since the cells continued to exclude trypan blue. The results of this study suggest a novel and potentially pathophysiologically/clinically relevant correlation between intercellular junctions and the secretion of endothelin in endothelial cells. Received: 17 December 1999, Returned for revision: 20 January 2000, Revision received: 14 February 2000, Accepted: 2 March 2000     

Low Muscle Levels of Pyridoxine in McArdle's Syndrome

Pyridoxal phosphate is a covalently bound cofactor of glycogen phosphorylase. Phosphorylase is a major muscle protein and therefore represents a significant pool of pyridoxal phosphate. Muscle pyridoxine content was measured in three patients with myophosphorylase deficiency (McArdle's syndrome) in whom there was a marked diminution or absence of phosphorylase protein as determined by acrylamide gel electrophoresis. Total muscle pyridoxine in the patients with McArdle's syndrome (0.55 ± 0.08 μg/g wet weight, mean ± SD) was markedly reduced compared with 11 human control subjects who had normal levels of muscle phosphorylase (total muscle B₆ = 2.49 ± 0.47). Despite such drastically low levels of muscle pyridoxine, these patients had no evidence of pyridoxine “deficiency.” These results suggest that low muscle B₆ in McArdle's syndrome represents the specific loss of pyridoxal phosphate normally bound to phosphorylase apoenzyme and imply that phosphorylase pyridoxal phosphate accounts for 75 to 80 percent of the total pyridoxine in normal human muscle.