[Huge right atrial myxoma]

Myxomas are account for approximately half of primary cardiac tumors, and 75% cases originate in left atrium. We report our experience of a right atrial myxoma. A 68-year-old woman was referred to us due to anorexia, general fatigue and facial edema. Echocardiogram, computed tomography (CT), magnetic resonance imaging (MRI), and catheter angiocardiogram revealed a huge tumor in right atrium. The tumor was resected completely with the attached right atrial free wall under cardiopulmonary bypass. Pathological examination showed myxomatous tissue. Postoperative course was uneventful. She discharged the hospital on the 37th day after the operation, and is now doing well without any symptoms.

[Double outlet right ventricle and pulmonary atresia with a birth weight of 1092 g]

A premature infant with double outlet right ventricle and pulmonary atresia with a birth weight of 1092 g is reported. He underwent right modified Blalock-Taussig (RMBT) shunt with an expand-polytetrafluoroethylene (ePTFE) tube of 3.0 mm in diameter between the right subclavian artery and the right pulmonary artery through right thoracotomy. Eleven days later, he had to undergo central shunt between the innominate artery and the main pulmonary trunk due to poor pulmonary blood flow. Soon after the central shunt, severe heart failure occurred due to excessive pulmonary blood flow. RMBT division was performed immediately. He finally attained definitive repair at 17 months of age. Postoperative course was uneventful and he was discharged on the 17th postoperative day.

[Severe tracheal compression resulting from atherosclerotic aortic arch aneurysm; report of a case]

A 70-year-old woman presented with severe respiratory insufficiency similar to an asthma attack. Computed tomography (CT) revealed an atherosclerotic aneurysm (maximum diameter 106 mm) on the aortic arch which resulted in a severe tracheal compression. We performed an aortic arch replacement. After the operation, we tried to manage breathing without a respirator twice without success. We then performed a tracheotomy on the 12th day after operation. The patient could breathe independently on the 19th day after the first operation. Peri-and postoperative respiratory management was difficult but the patient was discharged on the 86th day after operation without further complication.

Spontaneous reactivation of Shiga toxins in Escherichia coli O157:H7 cells caused by transposon excision

IS1203v is an insertion sequence which has been found in inactivated Shiga toxin 2 genes (stx2) of Escherichia coli O157:H7. Using PCR amplification, we detected the wild-type stx2 genes in colonies of E. coli O157:H7 which possessed stx2 genes inactivated by insertion of IS1203v. This suggests that IS1203v is excised from the inactivated stx2 genes in E. coli O157:H7. We isolated the cells possessing the wild-type stx2 genes, and confirmed Stx2 productivities by reversed passive latex agglutination. We also analyzed the frequency of the appearance of the Stx2-producing cells using a quantitative PCR method. As a result, the frequency was 3.00 x 10(-6) with culturing for 24 h at 37 degrees C, and this increased to 8.83 x 10(-5) when E. coli O157:H7 possessing the inactivated stx2 genes was transformed by an expression plasmid harboring the IS1203v transposase. These results showed that some Stx2-nonproducing E. coli O157:H7 strains could be spontaneously changed into Stx2-producing cells.

[De Bakey type I aortic dissection complicating systemic lupus erythematosus; report of a case]

We report a 43-year-old patient of De Bakey type I aortic dissection [DA (I)] with a 2-year-history of systemic lupus erythematosus (SLE). He had had no treatment for SLE before the onset of dissection. Computed tomography (CT) on admission revealed DA (I), and he underwent emergency operation. Since the aortic valve and the left main coronary artery were severely damaged, aortic root replacement was performed. Coronary buttons were prepared in Carrel method and coronary reconstruction was performed in Piehler modification. After surgery, he suffered from repetitive hemolytic anemia. Corticosteroid therapy and rinsed blood transfusion were very effective for anemia. The combination with SLE and DA (I) was rare and this report of successful aortic root replacement is the second literature among English and Japanese papers.

Giant extracardiac unruptured aneurysm of the sinus of Valsalva: a case report

Extracardiac unruptured aneurysm of the sinus of Valsalva (ASV) is rare and difficult to diagnose accurately by echocardiography or cardiac catheterization preoperatively. A 63-year-old woman, with dyspnea and palpitations, diagnosed with aortic regurgitation (AR) with congestive heart failure and extracardiac unruptured ASV, was referred to our hospital for surgical repair. The unruptured ASV was well visualized by magnetic resonance imaging (MRI), and diagnosed as an extracardiac type. Surgical repair was performed by aortic valve replacement and aneurysmectomy. It was concluded that early surgical repair of extracardiac ASV should be considered to prevent sudden death, and MRI is an accurate and useful method for preoperative diagnosis.

Successful surgical treatment of ventricular tachycardia that induced left ventricular aneurysm in 12-year-old boy

A surgical treatment of ventricular tachycardia (VT) that induced a congenital left ventricular aneurysm (LVA) in a 12-year-old boy was performed. The VT disappeared after epicardial cryoablation and a reinforcement of LVA with a composite patch. Epicardial cryoablation, based on an intraoperative electrophysiologic study (EPS), is effective in treating VT resistant to antiarrhythmia drugs.

Identification of shiga toxin-producing Escherichia coli possessing insertionally inactivated Shiga toxin gene

We have investigated the Shiga toxin genes of Shiga toxin-producing Escherichia coli (STEC) strains, using polymerase chain reaction (PCR) amplifying the full lengths of these genes. As a result, we found the Shiga toxin 2 gene which was insertionally inactivated by an insertion sequence (IS). This IS element was identical to IS1203v which has been also found in inactivated Shiga toxin 2 genes, and was inserted at the same site as in the previous paper. On the other hand, both Shiga toxin 2 genes were different (98.3% identity). These suggested that IS1203v independently inserted into each Shiga toxin 2 genes, and STEC strains possessing the insertionally inactivated Shiga toxin genes are most likely to have a wide distribution. Amplification of the full length of the Shiga toxin gene is one of the effective methods to detect the gene no matter where the IS element is included, i.e., the insertion can be reflected in the size of amplicon.

A potent 1,4-dihydropyridine L-type calcium channel blocker, benidipine, promotes osteoblast differentiation

During their differentiation, osteoblasts sequentially express type I collagen, alkaline phosphatase (ALP), and osteocalcin, and then undergo mineral deposition. Among dihydropyridine-type calcium channel blockers, only benidipine stimulated ALP activity of osteoblastic cells derived from neonatal mouse calvaria. To identify the molecular target of benidipine and elucidate the mechanism of action of the drug in osteoblasts, the mouse osteoblastic cell line MC3T3-E1 was used. Benidipine prompted ALP activity and ALP transcription induced by ascorbic acid, and mineral deposition by ascorbic acid and b-glycerophosphate. Benidipine, however, did not change collagen accumulation. MC3T3-E1 cells expressed the L-type Ca channel a1C subunit throughout the differentiation process, and Ca influx by potassium ions and Bay K 8644, an agonist, was strongly attenuated by benidipine. Each one of three structurally different classes of Ca channel blockers, nifedipine, verapamil, and diltiazem stimulated ALP activity, although at much higher concentrations of ca. 100 nM than benidipine, 1 pM. These results suggest that benidipine directly exerts its effect on osteoblasts and promotes osteoblast differentiation after the step of collagen accumulation by blocking the L-type Ca channel. Since benidipine blocked Ca influx more potently than the three other Ca channel blockers, the unique and potent osteoblast differentiating ability of benidipine may be due to its high affinity for Ca channel together with its high membrane retaining ability, as has been previously reported.

Predicting blood transfusion factors in coronary artery bypass surgery

OBJECTIVE

Blood conservation has become one of the most important issues in cardiac surgery. We clarified preoperative predictors of the need for blood transfusions during coronary artery bypass graft surgery.

METHODS

Subjects were 89 patients--66 men (74%) and 23 women (26%) 40 to 84 years old (mean: 66.2 +/- 8.3 years)--undergoing isolated coronary artery bypass surgery from September 1997 to December 1999. Of these, 66 patients (74%) received transfusion during hospitalization and 23 (26%) did not. Nine risk factors detected by univariate study were entered in a multivariate logistic regression model of the relationship between preoperative variables and blood transfusion.

RESULTS

Independent predictors were emergency surgery (P = .0023), lower hematocrit (P = .0027), older age (P = .0043), and the presence of peripheral vascular disease (P = .0070). Optimal cutoff of hematocrit for blood transfusion was 39% and age 64 years via receiver-operating characteristics curves based on the relation between sensitivity and specificity.

CONCLUSION

Patients older than 64 years with hematocrit less than 39% and/or peripheral vascular disease should be treated routinely using preoperative storage of autologous blood whenever the patient's condition permits. For patients undergoing emergency surgery, further studies are required, including lowering transfusion threshold and using determinants other than hematocrit.

Effects of various antihypertensive drugs on the function of osteoblast

Several studies have suggested that high blood pressure is associated with the risk of bone loss. Since various antihypertensive drugs are in wide use for the treatment of hypertension, it is important to investigate the influences of these drugs on bone metabolism. Osteoblasts play a pivotal role in the regulation of bone formation. During differentiation, they sequentially express type I collagen, alkaline phosphatase (ALP), other bone matrix proteins, and finally undergo mineral deposition. In this study, we examined the effects of various antihypertensive drugs on the function of osteoblast using clonal MC3T3-E1 cells. Drugs examined include dihydropyridine-type calcium channel blockers (benidipine, amlodipine, and nifedipine), angiotensin-converting enzyme (ACE) inhibitors (captopril, lisinopril, and enalapril), and angiotensin II receptor type1 (AT1) antagonists (TCV-116 and KW-3433). None of the ACE inhibitors or AT1 antagonists affected ALP activity or cellular DNA content significantly. In contrast, benidipine, amlodipine, and nifedipine increased ALP activity when used in amounts 1 pM, 100 nM, and 100 nM, respectively. Benidipine blocked calcium influx through the L-type voltage dependent calcium channel of MC3T3-E1 more potently than amlodipine or nifedipine. These calcium channel blockers did not change collagen accumulation. Benidipine significantly increased in vitro mineralization at a concentration of 1 nM and higher, while amlodipine did so at 1 microM and nifedipine did not. Comparison of the effective concentration of each calcium channel blocker in our study with the reported maximum serum concentration of each drug suggests that benidipine, but not amlodipine or nifedipine, promotes mineral deposition in human.

[Experiences of minimally invasive great saphenous vein graft harvest using with endopath]

We have experienced 20 cases of minimally invasive great saphenous vein graft harvest using with endoscopy, Endopath, from March 1999. As we experienced cases, we can harvest great saphenous vein graft, about 30-40 cm in size, from only two 4-cm incisions for about 50 minutes. There are no wound infection, pain, and edema. Great saphenous vein graft harvesting with Endopath is less invasive, painless after surgery and makes patients satisfied about cosmetic problem.

A mutant sarcosine oxidase in which activity depends on flavin adenine dinucleotide

The covalent flavin attachment site in the Arthrobacter sarcosine oxidase (cysteine at position 318) was replaced with serine, and the mutational effect of C318S was analyzed. Wild type and C318S with a C-terminal 6-histidine tag were constructed and homogeneously purified by the single step. The covalently binding to flavin was not essential to the enzyme activity because the C318S mutant exhibited extremely weak activity. Moreover, the activity of the mutant was recovered in the presence of flavin adenine dinucleotide (FAD), and significantly increased as the concentration of FAD increased. This dependence of the mutant on FAD indicates that the noncovalent binding of free FAD to the mutant enzyme is reversible.

Regression of left main coronary ostium stenosis after surgical revascularization and steroid therapy

We describe a patient in whom stenosis of the left main coronary ostium completely regressed after steroid treatment following surgical revascularization. A 46-year-old woman with unstable angina underwent double coronary artery bypass grafting. Although she did not fulfill diagnostic criteria for Takayasu's disease, we began postoperative steroid therapy on postoperative day 14 based on clinical manifestations and histological findings. Coronary angiography 33 days after surgery showed the ostial stenosis of the left main coronary artery had disappeared. Steroid therapy for suspected Takayasu's disease should be considered even after surgical revascularization.

The guanosine binding mechanism of the Tetrahymena group I intron

The Tetrahymena group I intron catalyzes self-splicing through two consecutive transesterification reactions, using a single guanosine-binding site (GBS). In this study, we constructed a model RNA that contains the GBS and a conserved guanosine nucleotide at the 3'-terminus of the intron (omegaG). We determined by NMR the solution structure of this model RNA, and revealed the guanosine binding mechanism of the group I intron. The G22 residue, corresponding to omegaG, participates in a base triple, G22 xx G3 x C12, hydrogen-bonding to the major groove edge of the Watson-Crick G3 x C12 pair. The G22 residue also interacts with A2, which is semi-conserved in all sequenced group I introns.

[A case of acute pulmonary embolism fourteen days after hysterectomy]

We describe a 54-year-old female with acute pulmonary embolism. She showed a syncope attack and hypotension fourteen days after hysterectomy for uterine cancer. Preoperative echocardiogram revealed that thrombus in the right atrium was coming and going through the tricuspid valve. Emergent pulmonary embolectomy through the sternotomy under cardiopulmonary bypass was performed 4.5 hours after the diagnosis without homologous blood transfusion. Postoperative perfusion scintigram 20 days after the operation showed normal filling of the both lungs except for the localized defect at the distal portion of the right middle lobe. The patient was discharged on the 22nd postoperative day and she has been followed up with anticoagulation therapy. It is essential that we have the opportunity to salvage an otherwise helpless situation by a high index of suspicion and a prompt surgical intervention.

Reactivation of insertionally inactivated Shiga toxin 2 genes of Escherichia coli O157:H7 caused by nonreplicative transposition of the insertion sequence

IS1203v is an insertion sequence which has been found in inactivated Shiga toxin 2 genes of Escherichia coli O157:H7. We analyzed the transpositional mechanism of IS1203v in order to investigate whether the Shiga toxin 2 genes inactivated by IS1203v could revert to the wild type. When the transposase activity of IS1203v was enhanced by artificial frameshifting, IS1203v was obviously excised from the Shiga toxin 2 gene in a circular form. The IS1203v circle consisted of the entire IS1203v, but an extra 3-bp sequence (ATC) intervened between the 5' and 3' ends of IS1203v. The extra 3-bp sequence was identical to a direct repeat which was probably generated upon insertion. Moreover, we detected the Shiga toxin 2 gene with a precise excision of IS1203v. In the wild-type situation, the transposition products of IS1203v could be observed by PCR amplification. These results show that IS1203v can transpose in a nonreplicative manner and that the Shiga toxin gene inactivated by this insertion sequence can revert to the wild type.

A new method for right ventricular endomyocardial biopsy via the femoral veins: a novel approach employing a right ventriculography catheter (Nishiya type)

We have devised a new method for right ventricular endomyocardial biopsy, in which the use of a right ventriculography catheter (Nishiya Type) allows us to ensure the introduction of a guiding sheath (Cordis, right-angled long sheath) to the apical portion of the right ventricle by way of the femoral vein. With this method, we have biopsied the endomyocardium in 52 patients during the last 4 years. In each case, it only took us several minutes to complete the biopsy procedure. Neither failed applications nor significant complications were seen. We believe that this technique provides a clinically beneficial means as it enables us to readily and safely achieve right ventricular endomyocardial biopsy.