Effects of chaetoglobosin J on the G-F transformation of actin.

It was shown that substoichiometric concentrations of chaetoglobosin J, one of the fungal metabolites belonging to cytochalasins, inhibited the elongation at the barbed end of an actin filament. Stoichiometric concentrations of chaetoglobosin J decreased both the rate and the extent of actin polymerization in the presence of 75 mM KCl, 0.2 mM ATP and 10 mM Tris-HCl buffer at pH 8.0 and 25 degrees C. In contrast, stoichiometric concentrations of cytochalasin D accelerated actin polymerization. Chaetoglobosin J slowly depolymerized F-actin to G-actin until an equilibrium was reached. Analyses by a number of different methods showed the increase of monomer concentration at equilibrium to depend on chaetoglobosin J concentrations. F-actin under the influence of stoichiometric concentrations of chaetoglobosin J only slightly activated the Mg2+-enhanced ATPase activity of myosin at low ionic strength. It is suggested that when the structure of the chaetoglobosin-affected actin filaments is modified, the equilibrium is shifted to the monomer side, and the interaction with myosin is weakened.

Reannealing of phalloidin-treated actin filaments during recovery after sonication and its inhibition by beta-actinin.

Phalloidin (2 mol per mol actin)-treated pyrenyl F-actin showed a critical concentration of 1.8 microM in the presence of 10 mM KCl, 0.2 mM ADP, and 5 mM Tris-HCl buffer, pH 8.0 at 25 degrees C. The filament weight concentration did not change at all during and after sonication, yet degrees of flow birefringence increased and the filament number concentration decreased after the termination of sonication. The latter changes were not affected by EDTA, but inhibited by beta-actinin. These observations suggest that reannealing of short pieces of phalloidin-treated actin filaments fragmented during sonication takes place during recovery after sonication.

Imaging of a vortex lattice transition in YNi2B2C by scanning tunneling spectroscopy

The vortex lattices in YNi2B2C under the magnetic fields H up to 3 T applied along both the a and the c axes have been studied by scanning tunneling spectroscopy at 4.2 K. The vortex lattice transition has been found to occur in different manners for H parallela and H parallelc; in H parallela a slightly distorted hexagonal vortex lattice has been found to transform to a nearly square one above 1.0 T with increasing H, while in H parallelc the transition occurs at a much lower field around 0.1 T. The unconventional steep increase of the quasiparticle density of states outside the vortex core has also been found well below H(c2).

An intermediate state of G-actin between native and denatured: polymerization rate decreases but extent of polymerization remains unchanged.

The rate of actin polymerization gradually decreased without changing the final level of polymerization, when incubated in the presence of 0.2 mM ATP at pH 8.0 and 25 degrees C. This change was much faster in Mg2+-actin than Ca2+-actin, and Mg2+-actin became denatured and unpolymerizable on prolonged incubation. The drop in the polymerization rate was due both to weakened nucleation and a slowed elongation rate in the incubated actin. The change in the polymerization rate was partially reversible by storing the sample at 0 degrees C. When the rate of polymerization dropped markedly on prolonged incubation, a gel filtration profile showed that Ca2+-actin existed as monomer not as oligomer. On the other hand, Mg2+-actin formed dimers, and other oligomers, as revealed by crosslinking analysis. There were changes in fluorescence intensities due to tyrosine and/or tryptophan residues of the actin molecule, and in difference absorption spectra, suggesting that conformational changes intermediate between native and denatured states occurred during incubation.

Physarum myosin light chain interacts with actin in a Ca2+-dependent manner.

Actin-modulating activity was analysed with the 16,131-dalton calcium-binding light chain (CaLc, Kobayashi et al. (1988) J. Biol. Chem. 263, 305-313) of Physarum myosin, which is under an inhibitory Ca-control (Kohama and Kendrick-Jones (1986) J. Biochem. 99, 1433-1446). When skeletal muscle actin was polymerized in the presence of CaLc and Ca2+, increases in both viscosity and birefringence were reduced under high shear conditions. However, CaLc did not inhibit actin polymerization under no or low shearing forces, which was demonstrated by a variety of methods including fluorescence intensity measurements using pyrenyl actin. We propose that actin polymerized in the presence of CaLc and Ca2+ is easily fragmented under high shearing forces to produce the changes in viscosity and birefringence.

Beta-actinin is not distinguishable from an actin barbed-end capping protein in chicken breast muscle.

beta-Actinin is an actin-pointed end capping protein in skeletal muscle. Casella et al. have reported that a protein isolated from muscle acetone powder by procedures similar to those used for beta-actinin purification caps the barbed end of an actin filament (J. Biol. Chem. 261, 10915-10921 (1986)). We have confirmed the above results. However, it turned out that the two proteins were identical as to subunit sizes, peptide maps, and cross-reactivities with anti-beta-actinin IgG. The binding of the two proteins to opposite ends of an actin filament remains unexplained.

[A case report of a successful surgery for thoracoabdominal aortic aneurysm under partial cardiopulmonary bypass with selective perfusion of major abdominal branches].

A 69-year-old man showed gradually developing thoracoabdominal aortic aneurysm (TAAA) after coronary artery bypass grafting. The patient underwent graft replacement of TAAA uneventfully under partial cardiopulmonary bypass with selective perfusion of major abdominal branches. The major abdominal branches and two pairs of intercostal arteries were reconstructed. The patient showed no organ failure or spinal damage postoperatively. Partial cardiopulmonary bypass with selective perfusion of abdominal branches successfully protected both the visceral organs and the spinal cord from ischemia in a TAAA surgery.

[Mitral and aortic valve replacement associated with aortitis syndrome: a case report].

A case of aortic and mitral regurgitation associated with aortitis syndrome was presented. The patient was a 36-year-old female who admitted for palpitation and dyspnea. Left ventriculography showed moderate MR. Aortography showed moderate AR and multiple occlusive lesion of the aortic arch branches. After the inflammation was controlled, aortic and mitral valve replacement was performed. Postoperative course was uneventful. Histologically, aortic and mitral valve showed capillary increase and infiltration of inflammatory cells, mainly lymphocytes.

[Surgical experience with a case of subaortic stenosis previously treated by patch closure of ventricular septal defect].

A patient who developed subaortic stenosis ten years after patch closure of perimembranous VSD was surgically treated. The subaortic obstruction could not relief sufficiently by the conventional transaortic maneuver. In this surgery, additional ventriculo-septoplasty (modified Konno's operation or Cooley's operation) was performed, preserving the patient's own aortic valve, because of the valve and the valvular ring diameter were almost normal. The postoperative course was uneventful. In this case, a posterior deviation of the infundibular septum and the ventricular septal patch seemed to have played an important role in the pathogenesis of the development of subaortic stenosis.

[A case of congenital absence of the right coronary aortic cusp].

A 12-year-old boy with absence of the right coronary cusp underwent aortic valve replacement with a 21 mm St. Jude Medical prosthetic valve. He was known to have noncyanotic congenital heart disease at the age of 2 months. The diagnosis of aortic insufficiency was first made when he was 1 1/4 years old. Intensive medical treatment was continued while he was growing up. Cardiac catheterization was performed repeatedly at ages 3 1/2 and 7. The findings on the fourth cardiac catheterization at 12 years of age were pulmonary arterial pressure of 90/60 mmHg, left ventricular end-diastolic pressure of 25 mmHg and poor contraction of the left ventricle. Although IABP support was necessary for treatment of severe low cardiac output state in the early postoperative period, he was discharged at 1 month after operation, Now, he goes to school under anticoagulant therapy. Intensive medical care followed by elective aortic valve replacement may be a useful treatment for isolated congenital absence of the aortic valve cusp.

[A case report of aortic valve stenosis combined with complete A-V block during chronic hemodialysis].

A 52-year-old man treated by hemodialysis under the diagnosis of chronic renal failure admitted to our hospital due to aortic valve stenosis and complete A-V block. Aortic valve was severely calcified, and the cause of complete A-V block was considered caused by the progressive calcification invasing to conduction system. The aortic valve replacement and pacemaker implantation using myocardial lead were simultaneously. Postoperative course was uneventful. The efficacy of simultaneous operation of aortic valve and pacemaker implantation was emphasized. However the generator implantation was recommended to perform in the several days after the operation because of destruction of the pacemaker function by counter shock for arrhythmia in the early post operative period.

[Mitral valve replacement through a right thoracotomy, with intact coronary artery bypass grafts].

A 68-year-old male who had previously undergone aorto-coronary artery bypass grafting was admitted for mitral valve surgery. Because of the presence of anteriorly placed intact coronary artery bypass grafts, we used right thoracotomy to replace the mitral valve. Cardiopulmonary bypass was established after cannulation of the femoral artery and bicaval cannulation, and continuous retorograde cardioplegia with cold blood was infused. Residual air was evacuated through left ventricular vent catheter and aortic air vent hole. Post operative course was uneventful.

[Repeat open heart surgery in a case associated with persistent left superior vena cava: a method of simple occlusion of L-SVC using an alternative extra-pericardial approach and retrograde cardioplegia].

Twelve years ago, we reported a method of extrapericardial approach to the L-SVC. Since then we have used this approach and performed simple occlusion of L-SVC during cardiopulmonary bypass without any cerebral complications. We have been expecting for a long time and have believed that this method will be very valuable especially in repeat open heart surgery. A case of 49-year-old man successfully underwent a redo operation for mitral and tricuspid valve replacement using extrapericardial occlusion of the L-SVC and retrograde cardioplegia. Although there was a pitfall for retrograde cardioplegia in the persistent L-SVC and a possibility of steal of cardioplegic fluid through a branch of the accessory hemiazygos vein during retrograde cardioplegia for a case with persistent L-SVC, sufficient cardiac protection was obtained in the case presented.

[Subdural hematoma complicated after open heart surgery: a report of two cases with successful treatment].

Two cases of subdural hematoma complicated after open heart surgery were successfully treated during thirty years history of the department. A 45 year-old woman underwent tricuspid valve replacement due to isolated congenital tricuspid insufficiency. On the 27th postoperative day, she was suddenly attacked by headache, and disturbance of consciousness was recognized with gradual deterioration. Brain CT scan showed a subdural hematoma on the right frontal region. Immediate irrigation of the hematoma was performed. Postoperative course was uneventful, and she was discharged without any complications. A 59 year-old woman underwent mitral valve replacement due to mitral re-stenosis. On the 3rd postoperative day, disturbance of consciousness was seen suddenly. Brain CT scan showed a subdural hematoma in the bilateral posterior cranial fossa. Immediate GL-YCEOL drip infusion was started. On the next day consciousness returned without operation and she was discharged without any neurological complications. Both patients did not have head trauma during pre and post operative period. It was important to consider the possibility of a intracranial hematoma, when the disturbance of consciousness was recognized after open heart surgery and/or during anticoagulant therapy.

[Two cases of left atrial myxoma originating from mitral annulus].

We experienced two cases of left atrial myxoma originating from mitral annulus. Mitral valve replacement and mitral valvulo-annuloplasty were performed in each case, because of the presence of mitral leaflet defect due to removal of the myxoma. Two dimensional echocardiography was a useful method to confirm the location and decide the surgical approach.

[Stenosis of Carpentier-Edwards pericardial bioprosthesis in the tricuspid position caused by adhesion of native valve cusps to the bioprosthesis].

We experienced a case of dysfunction of Carpentier-Edwards pericardial bioprosthesis in the tricuspid position. Explanted bioprosthesis showed overgrowth of neointima from ring to cusps and adhesion to remnants of native cusps. This restricted the motion of the pericardial leaflets resulting in orifice stenosis. Care must be taken in such valve replacement by this prosthesis leaving native valve tissue.

[A case of successful operation of acute pulmonary embolism due to right ventricular thrombus detected by two-dimensional echocardiography].

A 44-year-old woman suddenly developed dyspnea and loss of consciousness four days after cholecystectomy. Under the diagnosis of acute pulmonary embolism, the patient was treated with anticoagulant with temporary relief of her symptoms. But emergency embolectomy was performed because of large right ventricular thrombus detected by two-dimensional echocardiography. Many reports suggest a relationship between pulmonary embolism and right-sided cardiac thrombi. We consider that two-dimensional echocardiography is essential in case of acute pulmonary embolism.

[Surgical experience with an infant with discrete subaortic stenosis successfully treated by aortoventriculoplasty].

A 3-year-old female with discrete subaortic stenosis is presented. Angiocardiographic studies showed a long segmental narrowing below the aortic valve. Although membranectomy and myectomy were selected as a surgical treatment, a longitudinal aortotomy was performed in order to extend the operation to ventriculoseptoplasty. During the operation, the right coronary cusp was seriously damaged and therefore aortoventriculoplasty was applied. The aortic valve was replaced with a 21 mm St. Jude Medical mechanical prosthesis. The left ventricular outflow tract was adequately enlarged, and postoperative course was uneventful.

[Abdominal arteriovenous fistula due to rupture of aorto-iliac aneurysm with multivarious clinical manifestations. Report of a case with successful repair].

We present a 63-year old man with the arteriovenous fistula caused by the rupture of the aneurysm which extended from the abdominal aorta to the bilateral internal iliac arteries. The clinical manifestations included edema of the left lower extremity, pulmonary embolism, high-output congestive heart failure, origulia, azotemia, liver dysfunction and unstable angina. Because of the variety of the clinical symptoms and the lack of the awareness of this rare complication (arteriovenous fistula), we missed the prompt detection of the entity of the abdominal arteriovenous fistula. We finally succeeded the surgical closure of the fistula and the aortic reconstruction with a woven Dacron bifarcation graft. Problems of diagnosis and operative management are discussed.