AF5q31, a newly identified AF4-related gene, is fused to MLL in infant acute lymphoblastic leukemia with ins(5;11)(q31;q13q23)

Infant acute lymphoblastic leukemia (ALL) with MLL gene rearrangements is characterized by early pre-B phenotype (CD10(-)/CD19(+)) and poor treatment outcome. The t(4;11), creating MLL-AF4 chimeric transcripts, is the predominant 11q23 chromosome translocation in infant ALL and is associated with extremely poor prognosis as compared with other 11q23 translocations. We analyzed an infant early preB ALL with ins(5;11)(q31;q13q23) and identified the AF5q31 gene on chromosome 5q31 as a fusion partner of the MLL gene. The AF5q31 gene, which encoded a protein of 1,163 aa, was located in the vicinity of the cytokine cluster region of chromosome 5q31 and contained at least 16 exons. The AF5q31 gene was expressed in fetal heart, lung, and brain at relatively high levels and fetal liver at a low level, but the expression in these tissues decreased in adults. The AF5q31 protein was homologous to AF4-related proteins, including AF4, LAF4, and FMR2. The AF5q31 and AF4 proteins had three homologous regions, including the transactivation domain of AF4, and the breakpoint of AF5q31 was located within the region homologous to the transactivation domain of AF4. Furthermore, the clinical features of this patient with the MLL-AF5q31 fusion transcript, characterized by the early pre-B phenotype (CD10(-)/CD19(+)) and poor outcome, were similar to those of patients having MLL-AF4 chimeric transcripts. These findings suggest that AF5q31 and AF4 might define a new family particularly involved in the pathogenesis of 11q23-associated-ALL.

Endothelium-dependent relaxation of rabbit atherosclerotic aorta was not restored by control of hyperlipidemia: the possible role of peroxynitrite (ONOO(-))

We determined the role of ONOO(-) in nitric oxide (NO) mediated vascular response in atherosclerosis and regression following removal of dietary cholesterol. The effect of ONOO(-) on NO-mediated vascular responses was examined in vitro. Basal and stimulated NO release was estimated by an NO-selective electrode as well as vascular response and the plasma NO metabolites. An immunohistochemical study was also carried out. Responses were compared in normal controls, atherosclerotic rabbits fed 1% cholesterol diet for 6 or 9 weeks (atherosclerotic group) and animals fed a normal diet for 6-36 weeks after the high cholesterol diet for 6 or 9 weeks (regression group). ONOO(-) impaired the basal and acetylcholine-stimulated NO release, but did not affect endothelium-independent relaxation. After 15 weeks on a normal diet, the acetylcholine-stimulated and basal NO-mediated relaxation, which was diminished in the aorta induced by 6 weeks high cholesterol diet, became restored. However, the vascular response in the 9 weeks high cholesterol diet group did not return to normal after 36 weeks on a normal diet. iNOS was observed in atherosclerotic plaques in atherosclerotic and regression groups along with ONOO(-) in the 9 weeks high cholesterol diet group, but not in the 6 weeks group. Conclusively, ONOO(-) can play a role in impairment of NO-mediated vascular response during the regression of dietary cholesterol-induced atherosclerosis, not in the initiation of atherosclerosis.

Regulation of rat mesangial cell migration by platelet-derived growth factor, angiotensin II, and adrenomedullin

This study sought to determine whether platelet-derived growth factor (PDGF) and angiotensin II (AngII) stimulate migration of cultured rat glomerular mesangial cells. After finding that this was so, the effects of adrenomedullin (ADM) and cAMP-elevating agents on basal and stimulated mesangial cell migration were examined. Two isoforms of PDGF, AB and BB, stimulated migration in a concentration-dependent manner between 1 and 50 ng/ml, while the AA isoform lacked significant effect. AngII modestly but significantly stimulated migration in a concentration-dependent manner between 10(-7) and 10(-6) mol/L. Rat ADM significantly inhibited the PDGF BB- and AngII-stimulated migration in a concentration-dependent manner between 10(-8) and 10(-7) mol/L. Inhibition by rat ADM was accompanied by an increase in cellular cAMP. cAMP agonists or inducers such as 8-bromo cAMP, forskolin, and prostaglandin I2 also significantly reduced the stimulated migration. H 89, a protein kinase A (PKA) inhibitor, attenuated the inhibitory effect of ADM, and a calcitonin gene-related peptide (CGRP) receptor antagonist, human CGRP (8-37), abolished the inhibitory effects of rat ADM. These results suggest that PDGF AB and BB as well as AngII stimulate rat mesangial cell migration and that ADM can inhibit PDGF BB- and AngII-stimulated migration, at least in part through cAMP-dependent mechanisms likely to involve specific ADM receptors with which CGRP interacts. The adenylate cyclase/cAMP/PKA system may be involved in the migration-inhibitory effect of ADM in these cells.

Cycloprodigiosin hydrochloride, a new H(+)/Cl(-) symporter, induces apoptosis in human and rat hepatocellular cancer cell lines in vitro and inhibits the growth of hepatocellular carcinoma xenografts in nude mice

The effects of cycloprodigiosin hydrochloride (cPrG-HCl), a new H(+)/Cl(-) symporter, were examined in liver cancer cell lines in vitro and in vivo. In the in vitro MTT assay, cPrG-HCl inhibited the growth of 6 liver cancer cell lines (Huh-7, HCC-M, HCC-T, dRLh-84, and H-35, hepatocellular carcinoma; HepG2, hepatoblastoma) in a dose- and time-dependent manner. The 50% inhibitory concentrations (IC(50)) at 72 hours' treatment for liver cancer cell lines were 276 to 592 nmol/L, while that for isolated normal rat hepatocyte was 8.4 micromol/L. The cPrG-HCl treatment of Huh-7 cells induced apoptosis as confirmed by the appearance of a subG(1) population, intranucleosomal DNA fragmentation, and chromatin condensation. cPrG-HCl raised the pH of acidic organelles and lowered pHi (below pH 6.8). In addition, the apoptosis in Huh-7 cells induced by cPrG-HCl was strongly suppressed when the cells were cultured with imidazole, a cell-permeable base. In the in vivo assay, nude mice bearing subcutaneous xenografted Huh-7 cells received 2 weeks of treatment with cPrG-HCl (1 or 10 mg/kg/d) subcutaneously. This treatment significantly inhibited tumor growth compared with the control after 8 days. The control mice were treated with 1% dimethylsulfoxide (DMSO) in saline (vehicle). A histopathological examination using the terminal deoxynucleotidyl transferase mediated dUTP biotin nick end labeling (TUNEL) method showed apoptosis in the treated tumor cells. No pathological changes were observed in any organs, and the serum alanine transaminase levels remained within normal limits. These results suggest that cPrG-HCl may be useful for the treatment of hepatocellular carcinoma.

Mechanism of overshoot in cardiac function during recovery from submaximal exercise in man

BACKGROUND

A sudden increase (overshoot) in the left ventricular ejection fraction during the recovery from maximal exercise has been reported in patients with coronary artery disease, but its mechanism has not been fully clarified. We investigated whether this phenomenon may occur in normal subjects, and whether it depends on the intensity of exercise.

METHODS

Thirteen normal subjects (mean [+/- SD] age, 59 +/- 8 years old) performed two levels (25 W and 50 W) of mild-intensity, constant-work-rate exercise for 6 min on a cycle ergometer. Left ventricular function was monitored continuously during the recovery from exercise using a computerized cadmium telluride detector.

RESULTS

An overshoot was observed in the ejection fraction during the first minute of recovery compared with the end-exercise value. The overshoot in the ejection fraction during recovery after the 50-W exercise was greater than that seen after the 25-W exercise. An overshoot phenomenon in stroke volume was also observed during the recovery from 50-W exercise.

CONCLUSIONS

The overshoot in cardiac function observed during the early phase of recovery, which was caused mainly by an immediate decrease in end-systolic volume, occurred even after exercise of mild intensity. This phenomenon appears to suggest the existence of a transient mismatch between cardiac contractility and afterload reduction during the recovery from mild-intensity exercise, even in normal subjects.

Plasma levels of nitric oxide and related vasoactive factors following long-term treatment with angiotensin-converting enzyme inhibitor in patients with essential hypertension

Several mechanisms other than the inhibition of systemic and local formation of angiotensin II (Ang II) have been proposed to play a role in mediating the hypotensive effects of angiotensin-converting enzyme (ACE) inhibitors. In the present study, we measured plasma levels of nitric oxide (NO) and the related vasoactive factors bradykinin, 6-keto prostaglandin F1alpha (6-keto PGF1alpha) a stable metabolite of prostacyclin, and cyclic guanosine-3',5'-monophosphate (cGMP) before and after a 4-week treatment with the ACE inhibitor lisinopril in 17 patients with essential hypertension. Plasma NO levels were measured by the Griess method after conversion of nitrate to nitrite. Long-term lisinopril treatment significantly reduced blood pressure and increased plasma NO and 6-keto PGF1alpha. The treatment also tended to increase plasma levels of bradykinin and cGMP, but not to a significant extent. The posttreatment NO level was inversely correlated with posttreatment systolic, diastolic, and mean blood pressure (n = 17, r= -.68, P< .01, n = 17, r= -.54, P < .05, and n = 17, r= -.66, P< .01, respectively). The posttreatment bradykinin level was also modestly correlated with posttreatment systolic and mean blood pressure (n = 17, r = -.51, P < .05 and n = 17, r = -.55, P < .05, respectively). In contrast, posttreatment 6-keto PGF1alpha and cGMP levels were not correlated with posttreatment systolic, diastolic, or mean blood pressure. These findings raise the possibility that increased formation of NO and bradykinin, as well as inhibition of the renin-angiotensin system, contribute to the hypotensive effect of the ACE inhibitor observed in our hypertensive patients.

A HMG-CoA reductase inhibitor improved regression of atherosclerosis in the rabbit aorta without affecting serum lipid levels: possible relevance of up-regulation of endothelial NO synthase mRNA

We determined the role of Fluvastatin: HMG-CoA reductase inhibitor on the regression of atherosclerosis following removal of dietary cholesterol. Male rabbits fed a 0.5% cholesterol diet for 12 weeks were divided into three groups: A1, hypercholesterolemic; A2, fed a regular diet for an 12 additional weeks; and A3, fed a regular diet with fluvastatin (2 mg/kg/day). Fluvastatin treatment (A3) did not affect serum lipid levels compared with A2. However, it decreased the atherosclerotic area in the aortic arch and decreased total and esterified cholesterol concentrations in the descending aorta. Tone-related basal NO release in the thoracic aorta was larger in A3 than in A2. eNOS mRNA in vessel was determined by competitive RT-PCR assay. It increased in A1, compared with normal aorta and decreased in A2; however, it did not decrease in A3. This is the first report of a decrease in eNOS mRNA in atherosclerosis after removal of dietary cholesterol and a reversal of it by a HMG-CoA reductase inhibitor, which may contribute to the regression of atherosclerosis.

Crystal structure of coagulation factor IX-binding protein from habu snake venom at 2.6 A: implication of central loop swapping based on deletion in the linker region

Coagulation factor IX-binding protein (IX-bp) isolated from the venom of the habu snake (Trimeresurus flavoviridis) is a disulfide-linked heterodimer consisting of homologous subunits A and B. The structure of IX-bp has been solved by X-ray crystallography at 2.6 A resolution to a crystallographic R -value of 0.181. The main-chain fold of each subunit is homologous to the carbohydrate-recognition domain of C-type lectins (C-type CRDs) except for the extended central loop. The structure is almost identical with that of factors IX and X-binding protein (IX/X-bp) as expected from the high level of amino acid sequence homology. The functional difference in ligand recognition from IX/X-bp must reside in the amino acid differences. A continuity of different amino acid residues located from the C-terminal of the second alpha-helix to the following loop forms the local conformational difference in this region between the two proteins. This loop participates in the formation of the concave surface between the two subunits, the putative binding site for the Gla-domain (gamma-carboxyglutamic acid-containing domain) of the coagulation factors. Another difference between the two proteins is in the relative disposition of subunits A and B. When the B subunits are superimposed, about a 6 degrees rotation is required for the superposition of the A subunits. A calcium ion links the second alpha-helix region to the C-terminal tail in each subunit and helps to stabilize the structure for Gla-domain binding. The interface created by the central loop swapping in the dimer IX-bp is almost identical with that seen within the monomeric C-type CRDs. This dimer forms as the result of the amino acid deletion in the linker region of the central loop of the original C-type lectins. Such a dimerization disrupts the lectin active site and creates a Gla-domain binding site, imparting functional diversity.

Association between angiotensin-converting enzyme gene polymorphisms and regression of left ventricular hypertrophy in patients treated with angiotensin-converting enzyme inhibitors

PURPOSE

An insertion/deletion (ID) polymorphism of the angiotensin-converting enzyme (ACE) gene is associated with left ventricular hypertrophy. The present study examined polymorphisms of the ACE gene in patients with essential hypertension and left ventricular hypertrophy who were participants in a long-term trial of therapy with an ACE inhibitor.

PATIENTS AND METHODS

ACE inhibitor therapy was administered for >2 years to 54 patients with hypertension who had moderate or severe left ventricular hypertrophy. Cardiac dimensions were monitored by echocardiography before the initiation of therapy and after 1 and 2 years of treatment. Serum ACE activity and plasma concentrations of brain natriuretic peptide, a marker for left ventricular hypertrophy, were also monitored.

RESULTS

Eighteen patients had the II genotype for the angiotensin-converting enzyme gene, 19 had the ID genotype, and 17 had the DD genotype. Baseline (mean +/- SD) serum ACE activity was significantly greater (P <0.05) in the DD (18 +/- 7 IU/L) group than in the II (7 +/- 4 IU/L) or ID (12 +/- 6 IU/L) groups. ACE inhibitor therapy was effective in controlling blood pressure, and it reduced posterior and septal wall thickness, left ventricular mass index, and plasma brain natriuretic peptide concentration in all three groups. Despite similar blood pressure reductions, after 2 years, mean (+/- SD) regression in posterior wall thickness was significantly less (P <0.05) in the DD group (-9% +/- 5%) than in the ID (-21% +/- 7%) and II (-21% +/- 9%) groups. Similar results were seen for the reductions in brain natriuretic peptide levels. The magnitudes of regression of septal wall thickness and left ventricular mass index during therapy were less in the DD group than the II group (P <0.05).

CONCLUSION

Hypertensive patients with the DD genotype are less likely to have regression of left ventricular hypertrophy when treated with ACE inhibitors than are patients with other ACE genotypes.

Anti-atherosclerotic action of vascular D1 receptors

1. Vascular smooth muscle cell (VSMC) migration and proliferation are believed to play key roles in atherosclerosis. To elucidate the role of vascular dopamine D1-like (D1 and D5) receptors in atherosclerosis, the effects of dopamine and the specific D1-like receptor agonists SKF 38393 and YM 435 on platelet-derived growth factor (PDGF)-BB-mediated VSMC migration, proliferation and hypertrophy were investigated. 2. We observed that cell stimulated by 5 ng/mL PDGF-BB showed increased migration, proliferation and hypertrophy. These effects were prevented by co-incubation with dopamine, SKF 38393 or YM 435 at 1-10 mumol/L and this prevention was reversed by Sch 23390 (1-10 mumol/L), a specific D1-like receptor antagonist. These actions of D1-like receptor agonists were mimicked by 1-10 mumol/L forskolin, a direct activator of adenylate cyclase, and 0.1-1 mmol/L 8-bromo-cAMP. The actions were blocked by the specific protein kinase A (PKA) inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline-sulphonamide (H 89), but were not blocked by its negative control N-[2-(N-formyl-p-chlorocinnamylamino) ethyl]-5-isoquinoline sulphonamide (H 85). Platelet-derived growth factor-BB (5 ng/mL)-mediated activation of phospholipase D (PLD), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activity was significantly suppressed by co-incubation with dopamine. 3. These results suggest that vascular D1-like receptor agonists inhibit migration, proliferation and hypertrophy of VSMC, possibly through the activation of PKA and the suppression of activated PLD, PKC and MAPK activity.

Moyamoya disease showing atypical angiographic findings--two case reports

A 7-year-old boy and a 10-year-old girl presented with moyamoya disease showing atypical angiographic findings. In these cases, the internal carotid artery (ICA) had a tapering occlusion just distal to the origin of the ophthalmic artery, whereas the top of the ICA was not occluded and was retrogradely supplied through the posterior communicating artery from the posterior circulation. Surgical treatment resolved the symptoms in both patients. Moyamoya disease may include a number of variant types not showing all the characteristic angiographic findings of moyamoya disease.

Antioxidants improve impaired insulin-mediated glucose uptake and prevent migration and proliferation of cultured rabbit coronary smooth muscle cells induced by high glucose

BACKGROUND

To explore the role of intracellular oxidative stress in high glucose-induced atherogenesis, we examined the effect of probucol and/or alpha-tocopherol on the migration and growth characteristics of cultured rabbit coronary vascular smooth muscle cells (VSMCs).

METHODS AND RESULTS

Chronic high-glucose-medium (22. 2 mmol/L) treatment increased platelet-derived growth factor (PDGF)-BB-mediated VSMC migration, [3H]thymidine incorporation, and cell number compared with VSMCs treated with normal-glucose medium (5.6 mmol/L+16.6 mmol/L mannose). Probucol and alpha-tocopherol significantly suppressed high glucose-induced increase in VSMC migration, cell number, and [3H]thymidine incorporation. Probucol and alpha-tocopherol suppressed high glucose-induced elevation of the cytosolic ratio of NADH/NAD+, phospholipase D, and membrane-bound protein kinase C activation. Probucol, alpha-tocopherol, and calphostin C improved the high glucose-induced suppression of insulin-mediated [3H]deoxyglucose uptake. Chronic high-glucose treatment increased the oxidative stress, which was significantly suppressed by probucol, alpha-tocopherol, suramin, and calphostin C.

CONCLUSIONS

These findings suggest that probucol and alpha-tocopherol may suppress high glucose-induced VSMC migration and proliferation via suppression of increases in the cytosolic ratio of free NADH/NAD+, phospholipase D, and protein kinase C activation induced by high glucose, which result in reduction in intracellular oxidative stress.

Effect of electric field on physical states of cell-associated water in germinating morning glory seeds observed by 1H-NMR

Morning glory seeds in dry conditions (0.099 g H2O/dry wt.) were exposed to electric fields and germinated. The physical state of water in the germinating seeds of both control and exposed groups were examined using 1H-NMR spectroscopy and NMR microscopy. Three water fractions were observed which were characterized by different relaxation times (T1) and chemical shifts. The average region containing long T1 fractions was approximately 50 micrometer in diameter and consisted of half-permeable barriers. The maximum intracellular water transport rate was 2.3x10-5 cm2/s. The treatment with electric field (500 kV/m for 60 min) increased the fraction with the shortest T1 and decreased that with the longest T1. Because the total water content in the treated seeds (3.4 g H2O/dry wt.) was similar to that in the untreated seeds (3.9 g H2O/dry wt.), the treated seeds held more water in a condition in restricted motion than the untreated seeds. It is thought that the membrane systems were affected by the electric polarization which led to an unusual accumulation of water and the hydration of stored macromolecules during the imbibition process. This set of events led to excessive swelling of stored macromolecules, resulting in the disruption of membrane systems and irregular organization of tissue structures.

A low-resolution structure of rice dwarf virus determined by ab initio phasing

Rice dwarf virus crystals belong to space group I222 with cell parameters a = 770 (2), b = 795 (5), c = 814 (5) A and alpha = beta = gamma = 90 degrees. The unit cell of the crystal contains two viruses at the origin and body-centred positions. Using data synthesized from a rice dwarf virus model crystal in the space group I222, the possibility of ab initio phasing was thoroughly examined. The centric nature of the initial phases was unexpectedly broken by extensive iteration of the non-crystallographic symmetry averaging. The structure of rice dwarf virus was then solved with ab initio phasing up to 20 A resolution. The triangulation number determined by the present study is T = 13, which is different from the triangulation number, T = 9, previously determined by electron microscopy [Uyeda & Shikata (1982). Ann. Phytopathol. Soc. Jpn, 48, 295-300].

[Effectiveness of hypoallergenic rice-by cast analysis]

Rice is the main food taken every day in Japan. We introduced hypoallergenic rice (95% of albumin and globulin were taken off by hyperpressure method) for 4 weeks to 7 atopic dermatitis patients (m 3, f 4), 11 mo-4 y 8 m (mean 3 y 2 m) who showed the RAST score of rice 1 or more. Stimulation Index by CAST (cellular antigen stimulation test) were compared before and after taking the rice (50-100 g). By albumin (0.1-100 micrograms/ml), maximum decreases of S.I. were 22.4-96.5% (mean 70.9) and by globulin maximum decreases of S.I. were (0.1-100 micrograms/ml) 33.3-97.0% (mean 72.9). In all the patients the skin conditions were improved.

Heparin inhibits human coronary artery smooth muscle cell migration

Heparin, an anticoagulant, has been shown to reduce neointimal proliferation and restenosis following vascular injury in experimental studies, but the clinical trials of heparin in coronary balloon angioplasty have been negative. The current study, therefore, examined the effect of heparin on basal or stimulated migration by serum and platelet-derived growth factor (PDGF)-BB in cultured human coronary artery smooth muscle cells (SMCs) by Boyden's chamber method. In addition, the reversibility of the heparin effect on human coronary artery SMC migration was examined. Fetal calf serum (FCS) and PDGF-BB stimulated SMC migration in a concentration-dependent manner. Heparin in moderate to high concentration (10 to 100 U/mL) exhibited concentration-related inhibition of FCS- and PDGF-BB-stimulated SMC migration; however, a low concentration (1 U/mL) of heparin had no inhibitory effects. Heparin also had weak inhibitory effects on nonstimulated SMC migration. The SMCs that were exposed to a high concentration (100 U/mL) of heparin for 6 hours were capable of migrating after a short lag period of removal of heparin from the culture medium. These SMCs also showed recovery of responses to FCS and PDGF-BB by migrating significantly greater than the nonstimulated level. Furthermore, heparin-containing medium did not contain detached cells. These results indicate that heparin inhibits human coronary artery SMC migration, especially when stimulated by FCS or PDGF-BB, and that this inhibitory effect of heparin is reversible and not simply a function of killing cells.

Induction by lysophosphatidylcholine, a major phospholipid component of atherogenic lipoproteins, of human coronary artery smooth muscle cell migration

BACKGROUND

The objectives of the present study were (1) to determine whether lysophosphatidylcholine (lyso-PC), a prominent component of oxidatively modified LDL, induces migration of human coronary artery smooth muscle cells (SMCs) and, if so, to clarify the mechanism, and (2) to investigate the possible interactions of lyso-PC and platelet-derived growth factor (PDGF)-BB, endothelin- (ET-1), adrenomedullin (AM), or vitamin E on SMC migration by the Boyden's chamber method.

METHODS AND RESULTS

Lyso-PC induced SMC migration in a concentration-dependent manner between 10(-6) and 5 x 10(-5) mol/L. By contrast, phosphatidylcholine was without significant activity, and lysophosphatidylinositol and lysophosphatidylserine were much less effective than lyso-PC. Lyso-PC increased basic fibroblast growth factor (bFGF) production in a concentration-dependent manner between 10(-6) and 5 x 10(-5) mol/L in these cells. Furthermore, lyso-PC-induced SMC migration was inhibited by neutralizing antibody to bFGF but not by neutralizing antibody to transforming growth factor-beta1. Lyso-PC-induced migration was significantly enhanced by PDGF-BB or ET-1 but was clearly inhibited by human AM and vitamin E.

CONCLUSIONS

These results indicate that (1) lyso-PC induces human coronary artery SMC migration at least in part through release of endogenous bFGF and (2) this lyso-PC-induced migration can be further induced by PDGF-BB and ET-1 and can be inhibited by human AM and vitamin E. Lyso-PC may recruit medial SMCs during the process of coronary atherosclerosis in part by releasing bFGF in concert with PDGF-BB or ET-1 in vascular tissues. This lyso-PC-induced SMC migration may be suppressed by AM and vitamin E under certain pathological conditions.

Vascular dopamine-I receptors and atherosclerosis

Vascular smooth muscle cell (VSMC) migration and proliferation are believed to play key roles in atherosclerosis. To elucidate the role of vascular dopamine D1-like receptors in atherosclerosis, the effects of dopamine, specific D1-like agonists SKF 38,393, and YM 435 on platelet-derived growth factor (PDGF) BB-mediated VSMC migration, proliferation, and hypertrophy were studied. We observed that cells stimulated by 5 ng/ml PDGF BB showed increased migration, proliferation and hypertrophy. These effects were prevented by coincubation with dopamine, SKF 38,393, or YM 435 at 1-10 mumol/l, and this prevention was reversed by Sch 23,390 (1-10 mumol/l), a specific D1-like antagonist. These actions are mimicked by 1-10 mumol/l forskolin, a direct activator of adenylate cyclase and 8-bromocyclic AMP at 0.1-1 mmol/l. The actions are blocked by a specific protein kinase A (PKA) inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline-sulfonamide (H 89), but are not blocked by its negative control, N-[2-(N-formyl-p-chlorocinnamylamino) ethyl]-5-isoquinoline sulfonamide (H 85). PDGF-BB (5 ng/ml)-mediated activation of phospholipase D (PLD), protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activity were significantly suppressed by coincubation with dopamine. These results suggest that vascular D1-like receptor agonists inhibit migration, proliferation and hypertrophy of VSMC, possibly through PKA activation and suppression of activated PLD, PKC and MAPK activity.

Effect of the endothelin family of peptides on human coronary artery smooth-muscle cell migration

The migration of coronary artery medial smooth-muscle cells (SMCs) is one of the key events in the process of intimal thickening in coronary atherosclerotic lesions. The objectives of the present study were to determine whether any of the three isoforms of endothelin (ET), ET-1, ET-2, and ET-3, or an intermediate form of ET, big ET-1, induces migration of human coronary artery SMCs, and to investigate the possible interaction of ET peptides and well-known migration-stimulatory factors, platelet-derived growth factor (PDGF)-BB and angiotensin II (Ang II), on SMC migration by the Boyden's chamber method. None of the ET peptides alone induced SMC migration between 10(-9) and 10(-7) mol/L. In contrast, ET-1 and ET-2 significantly induced SMC migration in the presence of low concentrations of PDGF-BB (0.5 ng/mL) or Ang II (10(-9) mol/L), although ET-3 was less active (ET-1 = ET-2 > ET-3). In contrast, big ET-1 was without significant activity on PDGF-BB-or Ang II-induced SMC migration. The potentiation of SMC migration by ET peptides was clearly inhibited by the ETA receptor antagonist BG-123 in a concentration-dependent manner. These results suggest that the ET family of peptides, especially ET-1 and ET-2, can induce human coronary artery SMC migration in combination with PDGF-BB or Ang II, probably via ETA receptors. Taken together with the finding that the concentrations of ET, PDGF-BB and Ang II are locally increased at sites of endothelial injury, this indicates that ET may be an initial stimulus for human coronary artery medial SMC recruitment during coronary atherosclerosis, possibly in combination with PDGF-BB or Ang II.

Expression of inducible nitric oxide synthase in T lymphocytes and macrophages in vessels with advanced atherosclerosis

While endothelial nitric oxide synthase is expressed in the endothelial cells of normal and atherosclerotic vessels, there are few reports about inducible nitric oxide synthase (iNOS) in atheroma. We investigated the expression of iNOS and its relation to inflammatory cells in atheroma. New Zealand White rabbits received a 1% cholesterol diet for 9 weeks (atherogenic diet) or a 1% cholesterol diet for 9 weeks then a normal diet for 36 weeks (reversible diet). The aortas were examined by immunohistochemical staining for anti-iNOS antibody, as well as antibodies for macrophages, T lymphocytes, and muscle actin. No iNOS was detected in normal aortas, intimal thickening, or fatty streaks. Although iNOS was detected in advanced plaques, it was not seen in smooth muscle-derived cells or endothelial cells, but was found in some macrophage-derived cells and in T lymphocytes. In regressive atherosclerotic aortas, iNOS was detected only in advanced plaques and not in macrophage-derived cells, but in T lymphocytes. These findings suggest that T lymphocytes and some macrophages induce iNOS through cytokine production in atheroma.

Effects of isosorbide dinitrate on oxygen uptake kinetics in cardiac patients

PURPOSE

Although nitrates are known to improve indices of exercise capacity in patients with coronary artery disease, their effects on oxygen uptake kinetics during the onset of exercise have not been clarified. We evaluated the acute effects of isosorbide dinitrate on the kinetics of oxygen uptake during the onset of exercise at a constant work rate in patients with coronary artery disease.

METHODS

We studied 14 patients with coronary artery disease who performed 6 min of low-intensity exercise at a constant work rate on a cycle ergometer 30 min after oral administration of 10 mg of isosorbide dinitrate or placebo in a double-blind, crossover manner. Oxygen uptake was calculated from breath-by-breath analysis of respired gases. The time constant of oxygen uptake kinetics during the onset of exercise was determined by fitting a single exponential function to the oxygen uptake response.

RESULTS

Heart rate was significantly increased at rest, and systolic blood pressure was significantly decreased both at rest and during exercise after administration of isosorbide dinitrate. The time constant of oxygen uptake was significantly shorter (the kinetics were faster) after administration of isosorbide dinitrate (39.4+/-10.1 vs 44.5+/-10.5 s, P = 0.038).

CONCLUSIONS

Isosorbide dinitrate was found to speed the kinetics of the increase in oxygen uptake during constant work-rate exercise. The time constant of oxygen uptake, which reflects the rapidity of cardiovascular adaptation at the onset of exercise, seems to be a useful parameter of the effectiveness of therapy in patients with coronary artery disease.