[Planned sedation with dexmedetomidine hydrochloride after pediatric cardiac surgery; an institutional experience].

Dexmedetomidine hydrochloride (DEX) is a newly developed alpha-2 adrenergic agonist sedative and has been shown to be effective in post-surgical patients, providing not only unique sedation but also stabilization of hemodynamic and respiratory function. We investigated the hemodynamic and respiratory effects and efficacy of DEX in 84 consecutive patients (age <6 months: 18, 6-12 months: 13, 1-3 years: 29, 4-9 years: 18, >10 years: 5, male:female = 44:40) who were sedated by DEX in combination with a small dose of midazolam and morphine. DEX was commenced at an initial dose of 0.7 microg/kg/hr during surgery, approximately 1 hour prior to transfer to the intensive care unit (ICU). DEX infusion was maintained at a rate of 0.2-0.7 microg/kg/hr after ICU admission throughout weaning from mechanical ventilation and extubation. The dose of the sedatives was optimized by scoring on Ramsay's sedative scale. There were no undesirable hemodynamic changes throughout the DEX infusion. Respiration was maintained and all patients were extubated uneventfully. Optimal level of sedation was achieved in all patients. There were no adverse events related to DEX administration. Moreover, junctional ectopic tachycardia (JET) and severe pulmonary hypertension (PH) leading to clinical deterioration, which are the major causes of postoperative morbidity in pediatric cardiac surgery, occurred at a low incidence in this series. Our DEX protocol provided 1) satisfactory postoperative sedation without compromising hemodynamics and respiration, and 2) prevention and amelioration of postoperative morbidity caused by sympathomimetic stimulation, in pediatric cardiac surgery.

Implications of sphingosine kinase 1 expression level for the cellular sphingolipid rheostat: relevance as a marker for daunorubicin sensitivity of leukemia cells.

We recently reported increased sphingosine kinase 1 (SPHK1) and decreased neutral sphingomyelinase 2 (NSMase2) gene expression in myelodysplastic syndromes and acute leukemia. This alteration is supposed to change the cellular sphingolipid metabolites; however, positive correlations were observed between daunorubicin (DA)-IC50 and the SPHK1 message but not between DA-IC50 and NSMase2 messages, when 16 different leukemia cell lines were used to analyze the relationship between gene expressions and chemosensitivity against DA. Using two cell lines with either the highest or lowest SPHK1 expression, cellular ceramides and sphingosine 1-phosphate (S1P) were quantified by liquid chromatography/mass spectrometry. Increased ceramide was observed in DA-sensitive, but not in DA-resistant cell lines treated with low doses of DA. Upon DA treatment, S1P decreased more in the sensitive cell lines than in resistant cell lines. A SPHK inhibitor recovered the DA sensitivity of DA-resistant cells. The modulation of SPHK1 gene expression by either overexpression or using siRNA affected the DA sensitivity of representative cell lines. Results clearly show that SPHK1 is both a good marker to predict the DA sensitivity of leukemia cells and a potential therapeutic target for leukemia with high SPHK1 expression, and suggest that the sphingolipid rheostat plays a significant role in DA-induced cytotoxicity.

Coordinate regulation of IkappaB kinases by mitogen-activated protein kinase kinase kinase 1 and NF-kappaB-inducing kinase.

IkappaB kinases (IKKalpha and IKKbeta) are key components of the IKK complex that mediates activation of the transcription factor NF-kappaB in response to extracellular stimuli such as inflammatory cytokines, viral and bacterial infection, and UV irradiation. Although NF-kappaB-inducing kinase (NIK) interacts with and activates the IKKs, the upstream kinases for the IKKs still remain obscure. We identified mitogen-activated protein kinase kinase kinase 1 (MEKK1) as an immediate upstream kinase of the IKK complex. MEKK1 is activated by tumor necrosis factor alpha (TNF-alpha) and interleukin-1 and can potentiate the stimulatory effect of TNF-alpha on IKK and NF-kappaB activation. The dominant negative mutant of MEKK1, on the other hand, partially blocks activation of IKK by TNF-alpha. MEKK1 interacts with and stimulates the activities of both IKKalpha and IKKbeta in transfected HeLa and COS-1 cells and directly phosphorylates the IKKs in vitro. Furthermore, MEKK1 appears to act in parallel to NIK, leading to synergistic activation of the IKK complex. The formation of the MEKK1-IKK complex versus the NIK-IKK complex may provide a molecular basis for regulation of the IKK complex by various extracellular signals.

Opposing effects of Jun kinase and p38 mitogen-activated protein kinases on cardiomyocyte hypertrophy.

c-Jun N-terminal protein kinase (JNK) and p38, two distinct members of the mitogen-activated protein (MAP) kinase family, regulate gene expression in response to various extracellular stimuli, yet their physiological functions are not completely understood. In this report we show that JNK and p38 exerted opposing effects on the development of myocyte hypertrophy, which is an adaptive physiological process characterized by expression of embryonic genes and unique morphological changes. In rat neonatal ventricular myocytes, both JNK and p38 were stimulated by hypertrophic agonists like endothelin-1, phenylephrine, and leukemia inhibitory factor. Expression of MAP kinase kinase 6b (EE), a constitutive activator of p38, stimulated the expression of atrial natriuretic factor (ANF), which is a genetic marker of in vivo cardiac hypertrophy. Activation of p38 was required for ANF expression induced by the hypertrophic agonists. Furthermore, a specific p38 inhibitor, SB202190, significantly changed hypertrophic morphology induced by the agonists. Surprisingly, activation of JNK led to inhibition of ANF expression induced by MEK kinase 1 (MEKK1) and the hypertrophic agonists. MEKK1-induced ANF expression was also negatively regulated by expression of c-Jun. Our results demonstrate that p38 mediates, but JNK suppresses, the development of myocyte hypertrophy.

Role for mitochondrial oxidants as regulators of cellular metabolism.

Leakage of mitochondrial oxidants contributes to a variety of harmful conditions ranging from neurodegenerative diseases to cellular senescence. We describe here, however, a physiological and heretofore unrecognized role for mitochondrial oxidant release. Mitochondrial metabolism of pyruvate is demonstrated to activate the c-Jun N-terminal kinase (JNK). This metabolite-induced rise in cytosolic JNK1 activity is shown to be triggered by increased release of mitochondrial H(2)O(2). We further demonstrate that in turn, the redox-dependent activation of JNK1 feeds back and inhibits the activity of the metabolic enzymes glycogen synthase kinase 3beta and glycogen synthase. As such, these results demonstrate a novel metabolic regulatory pathway activated by mitochondrial oxidants. In addition, they suggest that although chronic oxidant production may have deleterious effects, mitochondrial oxidants can also function acutely as signaling molecules to provide communication between the mitochondria and the cytosol.

[Successful administration of nifekalant hydrochloride for postoperative junctional ectopic tachycardia in congenital cardiac surgery].

Two episode of junctional ectopic tachycardia (JET) caused hemodynamic deterioration early after tetralogy of Fallot repair in an 8-month-old infant. Sinus rhythm resumed in each of the episodes immediately after intravenous administration of nifekalant hydrochloride (NIF), a newly developed Vaughan-Williams class III antiarrhythmic drug in Japan. Although QT interval was modestly prolonged with NIF, no life-threatening ventricular arrhythmia (i.e., torsades de pointes) occurred. NIF might be an effective alternative in the treatment of postoperative JET in congenital cardiac surgery.

[Bidirectional Glenn shunt without cardiopulmonary bypass].

From April 2002 to March 2005, 18 patients having undergone bidirectional Glenn shunt (BDG) without cardiopulmonary bypass (CPB) [off-pump BDG] were retrospectively reviewed. During BDG anastomosis, a temporary bypass was established between superior vena cava (15) or innominate vein (3) and main pulmonary artery (16) or right atrium (2). Hemodynamics and oxygenation were maintained well throughout the temporary bypass time. There was no emergent use of CPB. Mean transpulmonary pressure gradient immediately after and 24 hours after the BDG were 6.7 and 5.6 mmHg, respectively. Echocardiography showed mild flow turbulence at the anastomosis in 1 case. This simple and inexpensive technique provided good surgical view with stable hemodynamics enabling satisfactory BDG in selected cases. Furthermore, it could avoid adverse effects of CPB such as lung injury and possible blood transfusion. This experience would encourage off-pump BDG combined with more challenging procedures.

Interactions of the F1-ATPase subunits from Escherichia coli detected by the yeast two-hybrid system.

Subunit interactions among the F1-ATPase subunits were studied by the yeast two-hybrid system. Various pairwise combinations of genes encoding alpha, beta, gamma, delta and epsilon subunits of Escherichia coli H+-ATPase fused to the DNA-binding or activation domain of the yeast GAL4 gene were introduced into yeast and expression of a reporter gene encoding beta-galactosidase was detected. Combinations of the alpha and beta subunit genes, and of the epsilon and gamma subunit genes showed high levels of reporter gene expression, while those of alpha and delta, beta and delta, gamma and delta, and delta and epsilon demonstrated weak but significant reporter gene expression. However, combinations of alpha and gamma, beta and gamma, alpha and epsilon, and beta and epsilon did not induce reporter expression. None of the fused genes alone induced reporter gene expression. These results suggested that specific and strong interactions between the alpha and beta, gamma and epsilon, and weak interactions between the alpha and delta, beta and delta, and gamma and delta subunits occurred in yeast cells in the two-hybrid system. Effects of previously identified mutant beta subunits with Leu-40 to Pro. Glu-41 to Lys or Pro-332 to Gln substitutions which caused defects in molecular assembly of F1-ATPase were analyzed with regard to alpha-beta interactions. No interaction of the alpha and beta subunits was observed in this system using the beta subunit with mutation of Pro-332 to Gln. However, for the other two mutations, alpha-beta interactions were observed. This system may be useful for isolating mutants which have defects in interaction of F1-ATPase subunits.

Microtubule depolymerization normalizes in vivo myocardial contractile function in dogs with pressure-overload left ventricular hypertrophy.

BACKGROUND: Because initially compensatory myocardial hypertrophy in response to pressure overloading may eventually decompensate to myocardial failure, mechanisms responsible for this transition have long been sought. One such mechanism established in vitro is densification of the cellular microtubule network, which imposes a viscous load that inhibits cardiocyte contraction. METHODS AND RESULTS: In the present study, we extended this in vitro finding to the in vivo level and tested the hypothesis that this cytoskeletal abnormality is important in the in vivo contractile dysfunction that occurs in experimental aortic stenosis in the adult dog. In 8 dogs in which gradual stenosis of the ascending aorta had caused severe left ventricular (LV) pressure overloading (gradient, 152+/-16 mm Hg) with contractile dysfunction, LV function was measured at baseline and 1 hour after the intravenous administration of colchicine. Cardiocytes obtained by biopsy before and after in vivo colchicine administration were examined in tandem. Microtubule depolymerization restored LV contractile function both in vivo and in vitro. CONCLUSIONS: These and additional corroborative data show that increased cardiocyte microtubule network density is an important mechanism for the ventricular contractile dysfunction that develops in large mammals with adult-onset pressure-overload-induced cardiac hypertrophy.

Phase I trial of oral 2'-deoxy-2'-methylidenecytidine: on a daily x 14-day schedule.

2'-deoxy-2'-methylidenecytidine (DMDC) is a potent deoxycytidine analogue. Preclinical studies of DMDC demonstrated activity against a variety of murine and human tumors in cell cultures and murine models and indicate enhanced antitumor activity of DMDC when it was administered in a manner that provided prolonged systemic exposure. In view of this observation, this study was designed to determine the toxicities, maximum-tolerated dose, and pharmacokinetic profile of DMDC. DMDC was given p.o. under fasting conditions for 14 consecutive days every 4 weeks in patients with advanced solid tumors. The starting dose was 12 mg/m2/day. Pharmacokinetic studies were carried out on days 1 and 14 of the first cycle. Fourteen patients received 22 courses of DMDC. The dose-limiting toxicities were anorexia, leukopenia, thrombocytopenia, and anemia. General fatigue was the common nonhematological toxicity. The maximum-tolerated dose was 18 mg/m2/day, at which two of six patients developed grade 3 toxicities. This dose level could also be considered for Phase II testing with this schedule. At the 18-mg/m2/day dose level, the mean terminal half-life, maximum plasma concentration (Cmax), the area under the plasma drug concentration-time curve (AUC(0-infinity)) on day 1 were 1.7496 h, 112.9 ng/ml, and 399.8 ng x h/ml, respectively. Forty to 50% of the administered dose was recovered in the urine, indicating a good bioavailability and resulting significant systemic exposure to the drug, which may enable chronic oral treatment.

[Prophylactic treatment of oral sildenafil citrate for pulmonary hypertension in an infant treated with inhaled nitric oxide after open-heart surgery].

A 3-month-old boy with coarctation of the aorta (CoA), ventricular septal defect (VSD), atrial septal defect, and severe pulmonary hypertension (PH) underwent one-stage repair consisting of patch closure of VSD and coarctation repair. Inhalation of nitric oxide (iNO) was commenced to treat residual severe PH on the day of the operation. Oral sildenafil citrate was commenced on the day 1 and iNO was gradually weaned off on the day 3. There was no "rebound", severe increase in pulmonary artery pressure, which commonly occurs after discontinuation of iNO. Then the patient was extubated without any difficulties or recurrent PH. The oral sildenafil citrate therapy was ceased on the day 8. Prophylactic use of oral sildenafil citrate for PH might be an useful alternative to shorten the duration of iNO therapy and intensive care unit (ICU) stay in the selected patients after congenital open heart surgery.

[Successful resection of left ventricular myxoma in a toddler; report of a case].

A 4-year-old girl was found to have large left ventricular myxoma without any tumor-related symptoms. She underwent an urgent surgery and the myxoma was successfully removed through a left ventriculectomy. Great care was taken to prevent tumor-embolization during surgery, and to resect the endocardium attaching directly to the tumor. Future surveillance of this case warrants our operative technique described in this report.

[Successful implantation of a metal coronary angioplasty stent for bronchomalacia of the right tracheal bronchus associated with right isomerism complex in an early infant].

One-month-old boy had severe emphysema of the right upper lobe due to the stenotic tracheal bronchus compressed between the distorted right patent ductus arteriosus (PDA) and the right aortic arch associated with right isomerism complex. He underwent a left modified Blalock-Taussig shunt and a division of the PDA on cardiopulmonary bypass. Extracorporeal lung support (ECLS) was introduced because of severe hypoxemia caused by remaining bronchomalacia of the tracheal bronchus. On postoperative day 3, a metal coronary angioplasty stent was implanted at the stenotic lesion under fluoroscopic and bronchoscopic guidance. He was successfully weaned from ECLS and then respirator after the implantation. This simple stenting procedure might be an effective alternate in the treatment of bronchomalacia or bronchial stenosis in early infancy.

Selective venous sampling directly from cavernous sinus in Cushing's syndrome.

Using superselective catheterization technique, venous sampling directly from the cavernous sinus was performed in seven patients with Cushing's disease and one patient with ectopic ACTH secreting tumor. In Cushing's disease the central/peripheral (c/p) gradients of ACTH in the cavernous sinus (11.9-111.1; mean, 49.6) were much greater than those in the inferior petrosal sinus (1.0-52.0; mean, 14.0). The intercavernous gradients of ACTH provided correct lateralization in all patients but one who had a midline tumor. A patient with ectopic ACTH secreting tumor showed no gradients of ACTH both in the cavernous sinus and in the inferior petrosal sinus. The c/p gradients of PRL were smaller than those of ACTH in the cavernous sinus, inferior petrosal sinus, and jugular vein. The gradients of ACTH and PRL essentially indicated the same laterality in Cushing's disease, whereas the intersinus gradient of PRL provided a false laterality in two patients with a midline tumor. No complications have been observed during and after the sampling procedure. Thus, we conclude that 1) the selective sampling directly from the cavernous sinus offers sufficient c/p gradients (more than 10) for the reliable diagnosis of Cushing's disease, 2) CRH stimulation during the sampling and the simultaneous measurement of PRL are not necessary in this method, 3) the high concentration of pituitary hormones obtained by this sampling may be useful for other clinical investigations.

Myocardial adaptive changes and damage in ischemic heart disease.

Changes in two of the elements of myocardial subcellular organelles relating to cardiac energetics, ventricular myosin isozymes and mitochondrial DNA mutations, were examined using left ventricular tissue samples obtained at autopsy from patients with ischemic heart disease. Myosin isozymes were examined in tissues from nine patients with ischemic heart disease and 12 control patients with cancer but no heart disease. Extracted myosin was separated by pyrophosphate gel electrophoresis. The relative concentration of each component was determined by densitometry. Mitochondrial DNA mutations were evaluated in tissues from ten patients with myocardial infarction and 11 control patients with cancer but no heart disease. DNA was extracted and mitochondrial DNA mutations were detected by the polymerase chain reaction. Two bands were revealed by pyrophosphate gel electrophoresis. These contained VM-A, which exhibited faster electrophoretic mobility and was present in lower concentrations, and VM-B, which had a lower mobility and a higher concentration, respectively. SDS polyacrylamide gel electrophoresis showed that these two components contained the heavy chain and light chains 1 and 2 of myosin. VM-A concentrations tended to be higher in patients with ischemic heart disease than in controls. A 7.4-kb deletion was detected between the D-loop and the ATPase 6 genes of mitochondrial DNA from the myocardium of 6 out of 10 patients with myocardial infarction. The relative amounts of the two myosin isozymes could be altered by ischemic heart disease, although the functional significance of these components is unclear. The changes in the two myosin isozymes might be an adaptive change to disordered energy metabolism, but this change was small. The myocardial mitochondrial DNA deletions in patients with myocardial infarction were thought to result from ischemic damage.

Carnitine affects fatty acid metabolism after cardioplegic arrest in neonatal rabbit hearts.

BACKGROUND: Fatty acid (FA) metabolism and the contribution of carnitine to metabolism after cardioplegic arrest still remain unclear, especially in the neonatal heart where beta-oxidation is not a predominant source of adenosine triphosphate. METHODS: FA metabolism and the effects of carnitine administration were evaluated using a newborn (7-day-old) rabbit blood-perfused Langendorff model subjected to cold cardioplegic arrest. The hearts were divided into five groups; (1) perfused with unmodified diluted blood (n = 9), (2) subjected to 180 minutes of cold cardioplegic arrest and reperfused with the blood (n = 9), (3) subjected to the same ischemia and reperfused with the blood containing 40 microM/L (n = 9), (4) 0.5 mM/L (n = 5), and (5) 5 mM/L of carnitine (n = 5). During reperfusion, FA metabolism was assessed by iodine-123-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid, a fatty acid. The myocardial time-radioactivity curve was then determined and a mathematical compartment analysis of the external detection was used to elucidate FA metabolism in the cardiac myocyte. RESULTS: Cold cardioplegic arrest resulted in significantly impaired FA metabolism following reperfusion. Compartment analysis suggested that FA activation in the cytosol and beta-oxidation were impaired. Carnitine supplementation in groups 3 and 4 improved FA metabolism during reperfusion. In contrast, supplementation in group 5 had no beneficial effect on FA metabolism. CONCLUSIONS: These results suggest that FA metabolism is impaired after cold cardioplegic arrest and that carnitine supplementation may improve aerobic metabolism in neonates after open heart surgery.

Effects of carnitine on cardiac function after cardioplegic ischemia in neonatal rabbit hearts.

BACKGROUND: Ischemia immediately impairs myocardial fatty acid metabolism and reduces the concentration of carnitine which is an essential cofactor for fatty acid metabolism in the mitochondria. The purpose of this study was to investigate the effects of carnitine administration on recovery of cardiac function after cardioplegic ischemia in the neonatal heart where fatty acid metabolism is not a predominant source of adenosine triphosphate. METHODS: Isolated blood-perfused neonatal rabbit hearts underwent 3 hours of cold cardioplegic ischemia. The control group (n = 10) was reperfused with unmodified diluted blood. The carnitine group (n = 10) was reperfused with the blood containing 5 mM/L of carnitine. Before ischemia (base line) and after 15 and 30 minutes reperfusion, left ventricular (LV) function and LV compliance were measured using a intraventricular conductance catheter combined with an isovolumic balloon. Coronary blood flow was measured and myocardial oxygen consumption was calculated. RESULTS: Carnitine significantly improved not only LV systolic function but also LV diastolic function (p < 0.05) as well as LV compliance after ischemia. Coronary blood flow and myocardial oxygen consumption were significantly improved after ischemia in the carnitine group compared with the control group (p < 0.05). CONCLUSIONS: These results suggest that carnitine strikingly improves LV functional recovery and aerobic metabolism after cold cardioplegic arrest, and may improve cardiac performance in neonates after open heart surgery.

Pathologic finding of restenosis in stent-implemented right ventricle-pulmonary artery extracardiac conduit.

We describe an excised specimen of a stent-implanted valved equine pericardial extracardiac conduit in the right heart. It appears from careful pathologic examination that the stent acted as a nidus for thrombus formation followed by thick neo-intimal development over the stent, which caused restenosis. Restenosis occurred despite anticoagulation.

Long-term intra-arterial infusion chemotherapy with adriamycin for advanced bladder cancer.

Long-term intra-arterial infusion chemotherapy with Adriamycin (ADM) was performed in cases of bladder cancer prior to total cystectomy. This report describes the effects in 13 cases evaluated more than 3 weeks after infusion of 10 mg ADM once or twice weekly. An oblique skin incision approximately 10 cm long was made in the gluteal region to expose the gluteus maximus muscle. A teflon catheter was then inserted into the gluteal artery and fixed; the distal end was brought out from under the skin in the precordial region. A similar procedure was performed on the contralateral side. The catheter was inserted through the superior and inferior gluteal arteries in five and eight cases, respectively. In the former group, partial response was obtained in two cases, minimal response in two and no response in one, so that primary tumor remission was evident in 40% of the cases. In the latter group, all cases but one attained partial response, i.e., remission was seen in 87.5% of cases treated by inferior gluteal infusion. Skin erosion of the gluteal, perineal, and anal regions and sciatica-like pain were observed in some cases; however neither myocardial effect nor bone marrow suppression, which have been reported as side-effects of ADM, were observed in any of the cases. These results suggest that this therapeutic modality could be effective in the preoperative work-up of candidates for total cystectomy, and also that it could be useful in the treatment of patients in whom total cystectomy is contraindicated.

Rupture of a cerebral aneurysm during embolization for a cerebral arteriovenous malformation.

An aneurysm ruptured during superselective catheterization into the posterior cerebral artery for a left temporal arteriovenous malformation. The rupture may have been caused by stretching and displacement of the basilar and posterior cerebral arteries while the microcatheter with guide wire was advanced.