Coronary artery bypass grafting in patients with dialysis-dependent renal failure.

The aim of this study was to define short- and long-term results of coronary artery bypass grafting (CABG) in dialysis patients. A retrospective review was carried out on 73 consecutive patients dependent on chronic dialysis who underwent CABG. In 63 isolated CABGs, 9 operations were performed under normal beating heart because of severe atherosclerotic changes in the ascending aorta or carotid arteries. The operative mortality (30 days' mortality) was 4.1%, and causes of death were closely related to cardiopulmonary bypass use. In the last 29 operations after introduction of the beating heart bypass, no hospital deaths occurred. The actual survival rates dropped to 45% at 70 months mainly for noncardiac late death. CABG for dialysis patients as undertaken with an acceptable operative risk. Extended application of beating heart bypass to these patients may produce further positive early results.

Inhibitory effect of a synthetic prostacyclin analogue, beraprost, on urokinase-type plasminogen activator expression in RC-K8 human lymphoma cells.

Plasminogen activation by urokinase-type plasminogen activator (uPA) is implicated in tumor invasion and metastasis by the breakdown of extracellular matrix. We have recently demonstrated the inhibitory effect of cAMP on uPA gene transcription in RC-K8 human lymphoma cells (Biochim Biophys Acta 1268: 293-9, 1995). Prostacyclin produced by endothelial cells is shown to increase cellular cAMP levels by activating adenylate cyclase. We, therefore, examined the effect of a stable analogue of prostacyclin, Beraprost, on uPA production in RC-K8 cells. uPA activity gradually increased in the conditioned medium with time. Beraprost (0.1 nM-1.0 microM) inhibited uPA accumulation in a dose-dependent manner without affecting cell viability. Fibrinzymography demonstrated that high and low molecular forms of uPA were present in the conditioned medium and that after Beraprost-treatment all forms of uPA decreased and no PA/PA inhibitor complex was present. Northern blot analysis revealed that after exposure to Beraprost, uPA mRNA levels increased transiently and then rapidly decreased to below control levels. Treatment with Beraprost resulted in a rapid activation of cellular cyclic AMP-dependent protein kinase (PKA). Beraprost completely negated uPA gene expression induced by phorbol myristate acetate, an activator of protein kinase C (PKC). These results suggest that Beraprost inhibits uPA production by suppressing uPA gene expression through the PKA pathway and that PKA-mediated signals are dominant in uPA gene expression as compared to those medicated by PKC. This inhibition of uPA expression by a prostacyclin analogue may be an important fact to explain the mechanism of anti-metastatic effects of prostacyclin.

Modulation of urokinase-type plasminogen activator gene expression by inflammatory cytokines in human pre-B lymphoma cell line RC-K8.

We examined the effects of inflammatory cytokines, such as interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF alpha), transforming growth factor-beta (TGF beta) and lipopolysaccharide (LPS), on the urokinase-type plasminogen activator (uPA) gene expression in RC-K8 human pre-B lymphoma cells. Recombinant IL-1 alpha, recombinant IL-1 beta and LPS but not recombinant IL-6, recombinant TNF alpha and TGF beta dose-dependently increased uPA accumulation in the conditioned medium. Northern blot analysis revealed that uPA mRNA levels rapidly increased with a peak induction at 2 h after stimulation with IL-1 alpha and IL- 1 beta, but uPA mRNA increase by LPS began at 9 h after stimulation and the increase was maintained until the experiment ended at 24 h. These responses were independent of de novo synthesis, rather amplified in the presence of a protein synthesis inhibitor. The effects by IL-1 alpha and Il-1 beta were prevented by addition of anti-IL-1 alpha and anti-IL-1 beta neutralizing antibodies, respectively. In contrast, both antibodies did not prevent LPS-induced uPA gene expression. Therefore, it is unlikely that the effect by LPS is through induction of IL-1. Both IL-1 alpha and IL- 1 beta rapidly activated uPA gene transcription, but not increased stability of uPA mRNA. These results suggest that both IL-1 alpha and IL-1 beta cause a rapid activation of uPA gene transcription in which de novo protein synthesis is not required and that LPS induces uPA gene expression independently of the IL-1 pathway. These modulations of uPA production by inflammatory mediators may be implicated in tumor growth and metastasis.

Protein kinase activity-dependent inhibition of urokinase-type plasminogen activator gene transcription by cyclic AMP in human pre-B lymphoma cell line RC-K8.

We investigated the effects of cAMP on the urokinase-type plasminogen activator (uPA) production in human pre-B lymphoma cell line RC-K8 that is consistently secreting uPA in the conditioned medium. Both Bt2cAMP and PGE1 inhibited the uPA accumulation in a dose-dependent manner. Northern blot analysis and nuclear run-on assay revealed that uPA gene transcription was repressed by Bt2cAMP and the repression was negated by inhibition of de novo protein synthesis by cycloheximide. Pretreatment with H89 (N-[2-(p-bromocinnamyl-amino) ethyl]-5-isoquinoline sulfonamide), a specific cAMP-dependent protein kinase (PKA) inhibitor, strongly inhibited both the PKA activation and the supression of uPA mRNA accumulation induced by cAMP. H85 (N-[2-(N-formyl-p-chlorocinnamyl-amino) ethyl]-5-isoquinoline sulfonamide), which closely resembles H89 in its chemical structure but is not a selective inhibitor of PKA, showed little effect on the regulation of uPA gene regulation by Bt2cAMP. These results suggest that cAMP represses uPA gene transcription in human pre-B lymphoma cells through PKA pathway and in which de novo protein synthesis is required.

Carbazochrome sodium sulphonate (AC-17) decreases the accumulation of tissue-type plasminogen activator in culture medium of human umbilical vein endothelial cells.

This study investigated the effect of carbazochrome sodium sulphonate (AC-17) on the accumulation of tissue-type plasminogen activator antigen (t-PA:Ag) and plasminogen activator inhibitor-1 antigen (PAI-1:Ag) in culture medium of human umbilical vein endothelial cells (HUVEC). HUVEC were cultured in the presence of AC-17, and the concentration of t-PA:Ag and PAI-1:Ag in the medium was measured by an enzyme-linked immunoassay. AC-17, after 48 and 72 h incubation, significantly decreased the t-PA:Ag in the culture medium, while it had no significant effect on the PAI-1:Ag. The result of fibrin zymography was consistent with the result obtained by ELISA. It also revealed that all of the t-PA present in the culture medium formed complexes with PAI-1, indicating that AC-17 did not interfere with t-PA/PAI-1 complex formation. Furthermore, AC-17 did not inhibit the activities of t-PA and plasmin when measured by a fibrin plate method. These results suggest that AC-17 may modulate the fibrinolytic balance of blood through changing the function of endothelial cells, a new aspect of action of AC-17 as a haemostatic drug.

Different regulation of plasminogen activator inhibitor 2 gene expression by phorbol ester and cAMP in human myeloid leukemia cell line PL-21.

Previous studies have shown that protein kinase C (PKC) activators and dibutyryl cyclic AMP (Bt2cAMP) synergistically increase the antigen level of plasminogen activator inhibitor type-2 (PAI-2) in a human myeloid leukemia cell line PL-21. To clarify the mechanism, PAI-2 gene expression induced by phorbol myristate acetate (PMA), a PKC activator, and Bt2cAMP was investigated by Northern blot hybridization using a PAI-2 cDNA probe cloned from a human placental library. The level of PAI-2 mRNA was markedly increased in response to PMA and reached a maximum 5-9 h after stimulation. Nuclear run-on assay revealed an increase in PAI-2 gene transcription in PMA-treated cells. The induction was inhibited by inhibiting de novo protein synthesis with cycloheximide (CHX). cAMP also increased PAI-2 mRNA level in a dose-dependent manner. The increase began within 2 hours and, contrary to the case of PMA, the mRNA levels were maintained. Moreover, cAMP-induced increase in PAI-2 mRNA was not inhibited by CHX, rather enhanced. PMA and cAMP synergistically induced PAI-2 gene expression, which was completely inhibited by CHX. The cells pretreated with PMA for 24 h did not any more respond to stimulation with PMA but responded to cAMP and PAI-2 mRNA level was increased. The apparent half-life of constitutive level PAI-2 mRNA in PL-21 cells, determined by actinomycin-D-decay experiments, was approximately 2 h. Those induced by PMA and cAMP were approximately 5 h and 2 h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and characterization of adenosine diphosphatase from human umbilical vessels.

Adenosine diphosphatase (ADPase) activity was solubilized with a non-ionic detergent, Tween 20, from human umbilical vessels and purified to homogeneity by diethylaminoethyl-Sepharose CL-6B, adenosine 5'-monophosphate-Sepharose 4B, and concanavalin A-Sepharose chromatography. The apparent molecular mass was 75 kDa. The purified enzyme hydrolyzed pyrophosphate bonds of nucleoside di- and triphosphates in the presence of calcium ion. It was insensitive to the adenosine triphosphatase (ATPase) inhibitors, oligomycin and ouabain, and sensitive to sodium azide. Therefore, we concluded that the ADPase activity in human umbilical vessels does not derive from ADPase degrading only ADP but from ATP diphosphohydrolase (EC 3.6.1.5). The broad substrate specificity and the sensitivity to various inhibitors and calcium ion are common to ATP diphosphohydrolase from bovine aorta. However, there might exist some structural difference around the active site, because the antiserum raised in rabbit against the bovine aorta enzyme scarcely inhibited the human umbilical enzyme.

ATP diphosphohydrolase is responsible for ecto-ATPase and ecto-ADPase activities in bovine aorta endothelial and smooth muscle cells.

An ATP diphosphohydrolase (EC 3.6.1.5) is an enzyme hydrolyzing pyrophosphate bonds in nucleoside di- and triphosphates with broad substrate specificity in the presence of divalent cations. The ATPase and ADPase activities in the enzyme purified to homogeneity from bovine aortic vessel wall were insensitive to oligomycin, ouabain, and various protease treatments, and sensitive to azide and Ap5A. Bovine aorta endothelial and smooth muscle cells were cultured separately to characterize the ectonucleotidase activities. The activities were dependent on the addition of divalent cations and had broad substrate specificity. The ecto-ATPase and -ADPase activities were insensitive to oligomycin, ouabain, and protease treatments, and sensitive to azide and Ap5A. No enzyme degrading only ADP was found in the aortic vessel wall. Moreover, antiserum raised against purified ATP diphosphohydrolase inhibited the ecto-ATPase and -ADPase activities. These results indicated that ecto-ATPase and ecto-ADPase are not separate enzymes but are expressed by one enzyme, ATP diphosphohydrolase.

The dependence of maximal expiratory flow on vital capacity: a theoretical analysis.

The decrease of maximal expiratory flow rates (Vmax) at the 50 or 25 per cent level of vital capacity (V50, V25) in idiopathic pulmonary fibrosis (IPF) has been reported by several investigators, and most of them simply concluded that small airway obstruction was associated with IPF. However, Jayamanne et al. (1978) stressed that the reduced airflow in this disease was due to the reduction of lung volume than to abnormally elevated resistance to airflow in small airways. Theoretical analysis on the influence of lung volume on Vmax using a mathematical model supported the opinion of Jayamanne et al.

Antimalarial phenanthrene amino alcohols. 3. Halogen-containing 9-phenanthrenemethanols.

A series of new 9-phenanthrene amino alcohols has been prepared in which each compound bears from one to five halogen or halogen-containing moieties. A number of these compounds are extremely active against Plasmodium berghei in the mouse. Some structural requirements for optimal efficacy are considered.