Characterization of the intrinsic fibrinolytic properties of pro-urokinase through a study of plasmin-resistant mutant forms produced by site-specific mutagenesis of lysine(158).

Two plasmin-resistant mutant forms of pro-urokinase (pro-UK) constructed by site-directed mutagenesis of Lys158 to Val158 and Met158 were used to evaluate the intrinsic enzymatic and fibrinolytic properties of pro-UK as distinct from those of its two-chain UK (TC-UK) derivative. Both mutants, while resistant to plasmin activation, were as sensitive as pro-UK to degradation by thrombin. Since thrombin cleaves a peptide bond only two residues from the activation site, the integrity of this loop was maintained in the two mutants.

Cell attachment to thrombospondin: the role of ARG-GLY-ASP, calcium, and integrin receptors.

Thrombospondin is a 420,000-D glycoprotein that has recently been shown to have several properties in common with the members of a class of adhesive proteins. To characterize further the adhesive properties of thrombospondin, we have studied its ability to support cell attachment. Thrombospondin adsorbed to plastic dishes supports the attachment of human endothelial and smooth muscle cells and the monocyte-like cell line (U937) as well as normal rat kidney cells.

Guidewire catheter exchange with triple culture technique in the management of catheter sepsis.

We report 70 total parenteral nutrition (TPN) patients who received guidewire catheter exchange for suspected sepsis during their hospitalization. To diagnose catheter-related sepsis (CRS) and catheter infection (CI), we used a system of pre- and postexchange catheter blood cultures and a catheter tip culture. There were 27 catheter exchanges with positive cultures.

Spectrin-alpha I/61: a new structural variant of alpha-spectrin in a double-heterozygous form of hereditary pyropoikilocytosis.

Recent biochemical studies have led to the identification of abnormal spectrins in the erythrocytes of patients with hereditary pyropoikilocytosis (HPP) and hereditary elliptocytosis (HE). In this report we describe the biochemical characterization of the erythrocytes from a proband with severe HPP who is doubly heterozygous for two mutant spectrins (Sp): Sp alpha I/74 and a new, previously undetected, mutant of alpha-spectrin designated Sp alpha I/61. The proband's erythrocytes are unstable when exposed to 45 degrees C, and her membrane skeletons exhibit instability to shear stress.

A monoclonal antibody to exfoliated surface vesicles that recognizes a membrane-associated erythroid burst-promoting activity.

A monoclonal antibody (MoAb) recognizing a membrane-associated erythroid burst-promoting factor was prepared by immunizing BALB/c mice with plasma membrane-derived vesicles exfoliated from lymphocytes under serum-free conditions. Hybrids secreting antibody reactive with lymphocyte plasma membranes were formally cloned and IgG was purified from monoclonal supernatants or from BALB/c mouse ascites fluid. Two clones (D3-E4 and D3-G9) were found to suppress burst forming unit-erythroid (BFU-E) proliferation when added directly to serum-free human marrow culture.

Laser therapy in the treatment of cardiovascular disease.

Percutaneous laser angioplasty has now become a clinical reality, consisting chiefly of applications of thermal angioplasty in conjunction with balloon angioplasty for the recanalization of peripheral vascular obstructions. In conjunction with this development, various aspects of laser-tissue interactions, fibreoptic transmission and delivery catheter design pertinent to the cardiovascular system have come under closer scrutiny, resulting in the emergence of both noteworthy concepts and clinical achievements.

Associations of human erythrocyte band 4.2. Binding to ankyrin and to the cytoplasmic domain of band 3.

We have examined the associations of purified red cell band 4.2 with red cell membrane and membrane skeletal proteins using in vitro binding assays. Band 4.

Fibrin activatable urokinase (FA-UK): a latent form of UK found in urine related to a complex with an inhibitor/fibrin-interacting cofactor.

In order to investigate the binding of pro-urokinase (pro-UK) in urine to fibrin/Celite, the property which led to its discovery, the effect of fibrin on the plasminogen activator activity of urine was studied. The plasminogen activator activity in urine was found to be consistently about 2-fold higher when measured by fibrin plate assay than by amidolytic substrate (S-2444), when normalized against the UK reference standard. When the amidolytic activity measurement was preceded by incubation of urine with soluble fibrin, a 2-fold increase in amidolytic activity was also found.

Contractile proteins participate in release of erythroid growth regulators from mononuclear cells.

We have investigated the role of contractile proteins of circulating mononuclear cells in generation of membrane-associated, erythroid growth regulatory molecules. Lymphocytes and monocytes were incubated under serum-free conditions without and with cytochalasin B, cytochalasin D, or colchicine, and effects on positive and negative erythropoietic activities were determined in cell membranes and in surface membrane vesicle-rich pellets and supernatants of dialyzed medium conditioned by the cells. In serum-free cultures of human bone marrow, plasma membranes and exfoliated membrane-derived vesicles from cytochalasin-treated lymphocytes lost their capacity to support the formation of erythroid bursts, while monocyte membrane-associated inhibitory activity was abolished by preincubation with cytochalasin.

3'-Azido-3'-deoxythymidine (AZT) inhibits proliferation in vitro of human haematopoietic progenitor cells.

Peripheral blood cytopenias are a serious, dose-limiting toxicity of AZT therapy in patients infected by HIV. To evaluate the mechanism by which cytopenias develop, AZT effects of haematopoietic differentiation and growth were measured in serum-free, nucleoside-depleted cultures of normal human bone marrow. In contrast to native thymidine, AZT suppressed the proliferation of erythroid, granulocyte/macrophage and primitive haematopoietic stem cells in a dose-related and time-dependent fashion.

Detection of hemin release during hemoglobin S denaturation.

Sickle hemoglobin is relatively unstable upon oxidation or mechanical shaking. During denaturation, it generates oxygen radicals and hemichromes and ultimately precipitates in the form of micro-Heinz bodies. It is not clear, however, whether the degradation product hemin, which is a potent hemolytic agent and a potential perturbant to protein-protein interactions in the red cell membrane skeleton, is also generated during sickle hemoglobin denaturation.

Safety of iron dextran in total parenteral nutrition: a case report.

Parenteral iron, in the form of intramuscular injection or intravenous infusion of iron dextran, is commonly used to treat iron deficiency. Constitutional symptoms, anaphylaxis, and rarely death are risks associated with the use of iron dextran for this purpose. However, iron supplementation of TPN solutions to meet daily requirements can be accomplished safely.

Diadenosine 5',5'''-P1,P4-tetraphosphate, a potential antithrombotic agent.

Diadenosine tetraphosphate (AP4A), a competitive inhibitor of ADP-induced platelet aggregation, was tested as an antithrombotic agent in a rabbit intracarotid thrombosis model previously shown to be sensitive to antiplatelet agents. Eighty-four percent of control rabbits formed clots. The infusion of AP4A at a dose of 50 mg/kg over 2 hours reduced the incidence of thrombosis to 56% (p less than 0.

Delayed common bile duct obstruction in acute pancreatitis.

Common bile duct obstruction during acute pancreatitis usually occurs in the early symptomatic phase of the illness, involves only the distal portion of the common bile duct, and subsides with clinical improvement. We present two cases of persistent common bile duct obstruction that developed 2-3 months after complete clinical subsidence of the initial episode of severe acute pancreatitis and involved a long segment of the common bile duct. After surgical decompression, there was no recurrence of common bile duct obstruction or pancreatitis.

Acetylated lipoproteins impair erythroid growth factor release from endothelial cells.

Endothelial cells are a known source of hematopoietic growth-enhancing factors, including platelet-derived growth factor (PDGF). In addition, endothelium interacts directly with plasma lipoproteins which have been shown to modulate hematopoiesis. To determine the relationship of these properties, we measured the release of an erythroid growth-enhancing factor from bovine endothelial cells under lipid-loaded and control conditions.

Complementary modes of action of tissue-type plasminogen activator and pro-urokinase by which their synergistic effect on clot lysis may be explained.

Tissue plasminogen activator (t-PA) and/or pro-urokinase (pro-UK) induced lysis of standard 125I-fibrin clots suspended in plasma was studied. Doses were kept below the concentration at which a nonspecific effect was seen, i.e.

Modulation of red cell band 4.1 function by cAMP-dependent kinase and protein kinase C phosphorylation.

Human erythrocyte protein 4.1 is phosphorylated in vivo by several protein kinases including protein kinase C and cAMP-dependent kinase. We have used cAMP-dependent kinase purified from red cells and protein kinase C purified from brain to test the effects of phosphorylation on band 4.

The iminodipropionitrile (IDPN)-induced dyskinetic syndrome in mice: antagonism by the calcium channel antagonist nifedipine.

Chronic administration of IDPN leads to the development of a persistent syndrome which is characterized by lateral and vertical neck dyskinesias, random circling behaviors, and locomotor hyperactivity. Although the dihydropyridine (DHP) calcium channel antagonist nifedipine inhibited all aspects of the syndrome, lateral head dyskinesias (laterocollis) and circling abnormalities were the most significantly affected signs. Dysregulation of calcium-dependent processes might be involved in the pathogenesis of the IDPN-induced dyskinetic abnormalities and clinical disorders of movement in humans.

Identification of the protein 4.1 binding site to phosphatidylserine vesicles.

Previous studies have shown that protein 4.1 is a multifunctional protein that binds to spectrin, actin, glycophorins, the anion channel protein, and phosphatidylserine (PS). In this report, we have characterized the binding of protein 4.

Central and peripheral effects of iminodipropionitrile on catecholamine metabolism in rats.

Chronic treatment with iminodipropionitrile (IDPN) causes a behavioral syndrome characterized by lateral and vertical neck dyskinesias, hyperactivity, random circling, and increased startle response (the "ECC syndrome"). The effects of the neurotoxin on norepinephrine (NE), dopamine (DA), and their metabolites were evaluated in the hypothalamus and the striatum of IDPN-treated animals. Urinary excretion of the amines was also measured.

Central cavitary necrosis: differentiation from pancreatic pseudocyst on CT scan.

Central cavitary necrosis of the pancreas has a computed tomography CT appearance of a well-defined sausage-shaped mass with a low-density center and convex margins, usually conforming to the pancreatic contour. Several other entities, including pancreatic pseudocyst, may have a similar appearance. Since the treatment of central cavitary necrosis differs considerably from that of these other entities, it is important to differentiate them.

Mechanism of laser ablation in an absorbing fluid field.

Selection of a laser source for intravascular applications has frequently been predicated upon assumptions involving transmissibility in blood of the wavelength of light emitted by a given laser. Standard absorption curves for ultraviolet radiation in blood and infrared radiation in water would suggest that transmission of ultraviolet radiation through a blood field and infrared radiation through any aqueous fluid field would be insufficient for tissue ablation. The present series of experiments was undertaken to determine whether these theoretical predictions would in fact obviate the use of these wavelengths in a blood field.