Successful surgical repair of left atrial dissection after mitral valve replacement

A rare case of left atrial dissection after mitral valve replacement is reported. Low output syndrome developed in the immediate postoperative period. Cardiac catheterization showed marked elevation of the pulmonary wedge pressure, and left ventriculography revealed massive paraprosthetic leakage with left atrial dissection. At the reoperation, the dissecting cavity was successfully closed from inside the left atrium under cardiopulmonary bypass. We consider this complication another variation of an atrioventricular discontinuity after mitral valve replacement.     

Diel rhythms of calling behavior and pheromone production of oriental tobacco budworm moth,Helicoverpa assulta (Lepidoptera: Noctuidae)

Both calling behavior and titer of (Z)-9-hexadecenal (Z9-16: Al), the major sex pheromone component ofHelicoverpa assulta, in pheromone glands showed distinct diel periodicity, and these two were synchronous. Calling was most actively performed and the pheromone titer reached a maximum from 2 to 6 h after lights-off. During photophase, no calling was shown and only a relatively small amount of Z9-16:A1 was detected. However, there was a time lag of a few days between peak calling activity and maximum pheromone titer. The pheromone titer was maximal from age 1 day to age 5 days and thereafter decreased while calling was most actively performed after age 3 days. Titers of three minor components, hexadecenal, (Z)-11-hexadecenal, and (Z)-9-hexadecenyl acetate, showed similar daily fluctuation patterns to that of Z9-16:Al, but relative to the titer of Z9-16:Al, the titer of the two aldehyde components remained relatively constant whereas that ofZ9-16:Ac increased in the late scotophase.     

Wear resistant coating of cemented carbides and high speed steels by chemical vapour deposition

Ti(N, C, O), which has been chosen as a coating material for cutting tool inserts, was prepared on cemented carbides and high speed steels by chemical vapour deposition via a gas mixture of TiCl₄, H₂, N₂, CH₄ and CO₂ under reduced pressure. This coating layer is characterized by fine grain size and freedom from porosity. The coated tool inserts show excellent cutting performance.     

REFLICS: Real-time flow imaging and classification system

An accurate analysis of a large dynamic system like our oceans requires spatially fine and temporally matched data collection methods. Current methods to estimate fish stock size from pelagic (marine) fish egg abundance by using ships to take point samples of fish eggs have large margins of error due to spatial and temporal undersampling. The real-time flow imaging and classification system (REFLICS) enhances fish egg sampling by obtaining continuous, accurate information on fish egg abundance as the ship cruises along in the area of interest. REFLICS images the dynamic flow with a progressive-scan area camera (60 frames/s) and a synchronized strobe in backlighting configuration. Digitization and processing occur on a dual-processor Pentium II PC and a pipeline-based image-processing board. REFLICS uses a segmentation algorithm to locate fish-egg-like objects in the image and then a classifier to determine fish egg, species, and development stage (age). We present an integrated system design of REFLICS and performance results. REFLICS can perform in real time (60 Hz), classify fish eggs with low false negative rates on real data collected from a cruise, and work in harsh conditions aboard ships at sea. REFLICS enables cost-effective, real-time assessment of pelagic fish eggs for research and management. Received: 12 April 2000 / Accepted: 6 July 2000     

Nanocrystallization of Fe73.5Si13.5B9Nb3Cu1 soft-magnetic alloy from amorphous precursor in a magnetic field

The effect of a magnetic field on the nature of nanocrystallization from a melt-spun Fe_73.5Si_13.5B₉Nb₃Cu₁ amorphous precursor has been studied with the aim of controlling microstructures and magnetic properties. Annealing for magnetic crystallization was carried out at temperatures between the Curie temperature of the amorphous phase (586 K) and that of the crystalline phase (920 K). It was found that the {110} texture component in crystallized α-Fe(Si) phase increased in importance with increasing magnetic-field strength. An X-ray diffraction analysis based on the Shultz method revealed that the magnetic field caused preferential formation of {110}-oriented nuclei. In addition, the applied field enhanced crystallization kinetics, particularly the nucleation rate. No significant difference in grain growth behavior was observed as a result of applying a magnetic field. We therefore conclude that the development of the {110} texture by magnetic crystallization is predominantly attributable to preferential nucleation, rather than preferential growth, of {110}-oriented nuclei. The saturation magnetization of nanocrystallized specimens, evaluated using a vibrating sample magnetometer (VSM), was increased by the application of a magnetic field up to 4T during nanocrystallization.     

Configuration of sample points for the reduction of multicollinearity in regression models with distance variables

Regression models often suffer from multicollinearity that greatly reduces the reliability of estimated coefficients and hinders an appropriate understanding of the role of independent variables. It occurs in regional science especially when independent variables include the distances from urban facilities. This paper proposes a new method for deriving the configuration of sample points that reduces multicollinearity in regression models with distance variables. Multicollinearity is evaluated by the maximum absolute correlation coefficient between distance variables. A spatial optimization technique is utilized to calculate the optimal configuration of sample points. The method permits us not only to locate sample points appropriately but also to evaluate the location of facilities from which the distance is measured in terms of the correlation between distance variables in a systematic way. Numerical experiments and empirical applications are performed to test the validity of the method. The results support the technical soundness of the proposed method and provided some useful implications for the design of sample location.     

Brain damage after aortic arch repair using selective cerebral perfusion

BACKGROUND: Selective cerebral perfusion is one of the most popular methods for cerebral protection during aortic arch repair. However, causes of postoperative brain damage are not fully understood. We analyzed brain damage after aortic arch repair using selective cerebral perfusion for true aortic arch aneurysm in regard to preoperative cerebral infarction and intracranial and extracranial occlusive arterial disease. METHODS: Over a 9-year period, 60 patients with true aortic arch aneurysm underwent aortic arch repair using selective cerebral perfusion. Postoperative brain damage was evaluated in regard to preoperative cerebral infarction detected by computed tomography, magnetic resonance imaging, or both in 50 patients and intracranial and extracranial occlusive arterial disease detected by digital subtraction angiography, magnetic resonance angiography, or both in 35 patients. RESULTS: Seven (12%) of the 60 patients died within 30 days of operation. Postoperative brain damage occurred in 6 (10.5%) (3, coma, and 3, hemiplegia) of 57 patients; 3 patients who died without awakening were excluded. Preoperatively, old cerebral infarction was detected in 9 patients (18%), and silent cerebral infarction (lacunar infarction and leukoaraiosis) was diagnosed in 26 patients (52%). Postoperative brain damage occurred in 3 (33%) of the 9 patients with preoperative cerebral infarction and in 3 (23%) of 13 patients with negative preoperative brain findings; this excludes 2 patients who died without awakening. No patient with silent cerebral infarction had postoperative brain damage. Occlusive arterial disease was detected in 7 patients (20%). The incidence of brain damage in these patients was 71% (5/7), which was significantly greater than that of 4% (1/28) in patients without occlusive arterial disease (p < 0.001). CONCLUSIONS: Silent cerebral infarction may not be a risk factor for postoperative brain damage. Preoperative evaluation of intracranial and extracranial occlusive arterial disease provides important information as to whether a patient might sustain brain damage after aortic arch repair using selective cerebral perfusion.     

Delayed and selective motor neuron death after transient spinal cord ischemia: a role of apoptosis?

OBJECTIVE: The mechanism of spinal cord injury has been thought to be related to tissue ischemia, and spinal motor neuron cells are suggested to be vulnerable to ischemia. We hypothesized that delayed and selective motor neuron death is apoptosis. METHODS: Thirty-seven Japanese domesticated white rabbits weighing 2 to 3 kg were used in this study and were divided into two subgroups: a 15-minute ischemia group and a sham control group. Animals were allowed to recover at ambient temperature and were killed at 8 hours, and 1, 2, 4, and 7 days after reperfusion (n = 3 at each time point). By means of this model, cell damage was histologically analyzed. Detection of ladders of oligonucleosomal DNA fragment was investigated with gel electrophoresis up to 7 days of the reperfusion. Immunocytochemistry, in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling staining was also performed. RESULTS: After 15 minutes of ischemia, most of the motor neurons showed selective cell death at 7 days of reperfusion. Typical ladders of oligonucleosomal DNA fragments were detected at 2 days of reperfusion. Immunocytochemistry showed in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end staining was detected at 2 days of reperfusion selectively in the nuclei of motor neurons. CONCLUSION: These results suggest that delayed and selective death of the motor neuron cells after transient ischemia may not be necrotic but rather predominantly apoptotic.     

Surgical experience in patients with Marfan's syndrome and cardiovascular disease

10 patients with Marfan's syndrome and cardiovascular disease were operated at Tohoku University Hospital from 1971 to 1988. Surgery included composite valve graft replacement of ascending aortic aneurysm with aortic regurgitation in 5 patients and prosthetic mitral valve replacement in three patients; two had resection of aneurysm with Dacron tube replacement. Operative mortality was 10%. Two late death occurred (22%). It was suggested that regular follow-up examination is important in these patients to detect new lesions and to evaluate known lesion.