Localization and transient emission properties in InGaN/GaN quantum wells of different polarities within core-shell nanorods

Transient photoluminescence (PL) characteristics and localization phenomena in InGaN/GaN core-shell nanorods (NRs) were investigated from 6 K up to 285 K. The NRs exhibit three well-defined PL bands in the near-UV, blue, and green range ascribed to the emission of quantum well (QW) areas situated at the (1.00) sidewalls, (10.1) top facets, and (00.1) tip, respectively. At low temperature, time-resolved PL shows a fast decay time of about 0.5 ns for the semi- and non-polar QWs, while the polar QWs exhibit at least a twice-longer time. Rapid delocalization of carriers above 50 K indicates shallow potential fluctuations in the QWs. At room temperature, the characteristic fast PL decay time of the three QW bands stabilizes around 300 ps. The slow decaying PL components have different characteristic decay times that are explained by additional localization at basal stacking faults (BSFs), taking into account the quantum confined Stark effect. In addition, narrow excitonic luminescence lines are observed in the BSF-enriched polar QWs, providing direct evidence of the impact of the BSF/QW crossings on the optical properties of the NRs. A PL rise time of about 100 ps does not show any deviation between bands. These findings are suggestive of similar transport mechanisms in temperature equilibrium without inter-facet transport between different QWs. We believe that predictable transient characteristics can play a key role in creating uniform NR ensembles for device applications.

Effect of Left Ventricular Assistance on Sympathetic Tone

To determine the effect of left ventricular assist device (LVAD) pumping on sympathetic tone, renal sympathetic nerve activity (RSNA) was detected in acute animal experiments.

Our TH-7B pneumatically driven, sac-type ventricular assist device was used in 7 adult mongrel dogs. RSNA was detected by the use of bipolar electrodes attached to the left renal sympathetic nerve. RSNA was amplified and integrated by use of an R-C integrator circuit. The area of the integrated nerve discharge per unit time was calculated in the computer system and expressed as RSNA per unit time.

During LVAD pumping, RSNA decreased with increase in blood pressure, with an increase in pulmonary artery flow, and with a decrease in left atrial pressure. These data suggest that LVAD has an effect on the sympathetic nervous system which is mediated by the aortic and cardiopulmonary baroreflex system.

Estimation of the following Cardiac Output Using Sympathetic Tone and Hemodynamics for the Control of a Total Artificial Heart

A sympathetic neurogram is potentially useful for the development of a real time total artificial heart (TAH) control system. We used sympathetic tone and hemodynamic derivatives to estimate the following cardiac output in acute animal experiments using adult mongrel dogs. Moving averages of the mean left atrial pressure and mean aortic pressure were used as parameters of the preload and afterload, respectively. Renal sympathetic nerve activity (RSNA) was employed as a parameter of sympathetic tone. Equations for the following cardiac output were calculated using multiple linear regression analysis of the time series data. A significant correlation was observed between the estimated and following measured cardiac output. These results suggest the potential usefulness of the sympathetic neurogram for the real time TAH automatic control system.

Vagal Nerve Activity and the High Frequency Peak of the Heart Rate Variability

For the Quality of life (QOL) of patients with an artificial heart system, monitoring an information of the cardiovascular control system may be important. We have been evaluating the autonomic nervous system for that purpose. Recently, fluctuations in hemodynamic parameters including heart rate variability (HRV) were evaluated by means of spectral analysis and nonlinear mathematical analysis. Respiratory wavers in HRV were thought ro reflect ongoing information of the parasympathetic nerve activity. Is it true? In order to confirm this hypothesis, we recorded vagal nerve activity directly in the chronic animal experiments. Six healthy adult goats were anesthetized with Halothene inhalation and thoracotomy were performed by the fourth lib resection during mechanical ventilation. Arterial blood pressure, right and left atrial pressures were continuously monitored with the catheter insertion. Cardiac output was measured by the electromagnetic flowmeter attached to the ascending aorta. After the chest was closed, incision was made to the left neck and left vagal nerve was separated. Stainless steel electrodes were inserted into the vagal nerve and fixed by the plasticizer. After the incision was closed, the goats were transferred to the cage and extubated after waking. Hemodynamic parameters and vagal nerve activity were measured in the awake condition. The results showed that clear observation of the autonomic nerve discharges were embodied by this experimental system. The vagal nerve discharges were synchronized with heart beat and respiration. The vagal nerve tonus was significantly influenced by the hemodynamic alteration. However in some condition, the respiratory wave was not always consistent with tonus of the vagal nerve activity, thus suggesting that we should check another information to evaluate the parasympathetic tone. We must continue this study to evaluate an autonomic nerve during artifical heart circulation.

Mayer Waves in Dogs with Total Artificial Heart

To assess the effect of a total artificial heart (TAH) on the autonomic nervous system a power spectral analysis of the hemodynamics in a TAH animal was done by the maximum entropy method. Two pneumatically driven sac-type ventricular assist devices were implanted as total biventricular bypass (BVB) in adult mongrel dogs to compare the differences between natural heart and TAH. Once the BVB was pumping, the natural heart was electrically fibrillated to constitute the BVB-type TAH model. In the arterial pressure waveform in animals with TAH, respiratory waves were not changed (97.7±24.6%) though Mayer waves were significantly decreased (47.5 ± 22.6%) compared with the animal with a natural heart. These results suggest that prosthetic hemodynamics in the TAH animal affect fluctuations in the cardiovascular system.

Monitoring System for the Totally Implantable Ventricular Assist System by Use of Sensors for Virtual Reality

For the development of the totally implantable artificial organs, it is an important problem to monitor the conditions of the implantable devices, especially when used in clinical cases. In this study, we used position sensors for the 3-dimensional (3-D) virtual reality (VR) system monitor an implantable artificial heart. The sensors used in the experiments were 3-space Fastrak (Polhemus, USA). The position sensors using electro-magnetic forces were attached to the inner actuating zone. Sensitivity of the position sensors was in the order of around 0.8 mm. By use of these VR position sensors, we could easily detect the six degrees of freedom as x,y,z, and pitch, yaw, roll of these sensors. Experimental evaluation using a model circulation loop and healthy adult goats was performed. Experimental results suggest that our newly developed implantable sensors for monitoring the implantable artificial heart system were useful for sensing driving condition, thus possibly useful for the implantable devices for clinical usage.

Development of Total Artificial Heart with Economical and Durability Advantages

To develop a total artificial heart (TAH) pump system, we created a design paying particular attention to durability and cost. We adopted a pneumatically driven sac type artificial heart, where the configuration of the sac was decided according to the methodology of flow visualization. Its configuration is almost round to achieve as little stagnation as possible and a low turbulent flow. The main body of the sac was made using polyvinyl chloride (PVC) paste. The paste was poured into an external mold, and heated in a hot air drying oven. Coating was performed using polyurethane. The basic performance of this pump system was tested using a model circulation circuit, and a fitting study through acute animal experiment, using a healthy adult goat, was carried out. As for the TAH produced experimentally, a pump output exceeding 5.0 l/min in the model circulation circuit was provided. Implantation in the internal pleural cavity of a healthy adult goat, 55 kg in weight, proved possible and quite easy in comparison. It is thought that a more refined design in the connector part is desirable. Furthermore, a chronic experiment with the TAH will be carried out, and examination will need to be repeated in the future.

Can the Artificial Heart Make the Circulation Become Fractal?

In order to analyze the hemodynamic parameters in prosthetic circulation as an entity and not as decomposed parts, non linear mathematical analyzing techniques, including the fractal dimension analyzing theory, were utilized. Two pneumatically actuated ventricular assist devices were implanted, as biventricular bypasses (BVB), in chronic animal experiments, using four healthy adult goats. For the comparison between the natural and prosthetic circulation in the same animals, the BVB type complete prosthetic circulation model with ventricular fibrillation, was adopted. All hemodynamic parameters with natural and prosthetic circulation were recorded under awake conditions, and calculated with a personal computer system. Using the non-linear mathematical technique, the arterial blood pressure waveform was embedded into the return map as the beat-to-beat time series data and fractal dimension analysis were performed to analyze the reconstructed attractor. By the use of the Box counting method, fractal dimension analysis of the hemodynamics was performed. Return map of the hemodynamics during natural and artificial circulation showed fractal characteristics, and fractal dimension analysis of the arterial blood pressure revealed the fact that lower dimensional fractal dynamics were evident during prosthetic circulation. Fractal time series data is suggested to have robustness and error resistance, thus our results suggest that the circulatory regulatory system with an artificial heart may have these desired characteristics.

Strange Hemodynamic Attractor Parameter with 1/R Total Artificial Heart Automatic Control Algorithm

To evaluate the automatic control algorithm of the total artificial heart (TAH) as an entity, and not just as parts, a non-linear mathematical analyzing technique including chaos theory was utilized. Chronic experiments on the biventricular bypass type artificial heart implantation were performed in healthy adult goats after the natural ventricles were removed. Hemodynamic time series data were recorded under the awake standing condition with TAH 1/R and fixed driving. Time series data were recorded on a magnetic tape and analyzed on a personal computer system with an A-D converter. Using the nonlinear mathematical technique, the time series data were embedded into the phase space and the Lyapunov numerical method was carried out for the quantitative evaluation of the sensitive dependence on the initial condition of the reconstructed attractor. Calculation of the largest Lyapunov exponents suggested that the reconstructed attractor of the left pump output during TAH 1/R control was a larger dimensional strange attractor, a characteristic pattern of deterministic chaos. A total system indicating chaotic dynamics was thought to be a flexible and intelligent control system. Thus, our results suggest that 1/R TAH control may be suitable for the biventricular assist type total artificial heart.

Development of Intracoronary Local Adhesive Delivery Technique

Acute coronary occlusion may occur in weak coronary atherosclerotic lesions, including dissection, ulceration or thrombus. In some cases of occlusion “bail-out” is performed by using recently developed New Devices. However, these have not yet completely solved the problem to this end, we designed a new method of coronary revascularization, the Intracoronary Local Adhesive Delivery Technique, utilizing antithrombotic and absorbable adhesive injected locally into the fragile and morbid arterial wall using a drug delivery PTCA catheter more flexible than the existing New Devices. This adhesive strengthened and hardened the lesions. In this study, we examined the efficacy of making an adhesive cylinder in arteries of similar size to the coronary, through acute animal experiments using the existing clinical adhesives and drug delivery PTCA catheters and 12 femoral arteries of adult goats. We were successful in forming firm tunnels along the inside of six arteries, infused with approximately 0.04 ml Cyanoacrylate. These tunnels were observed with intravascular ultrasound (IVUS) imaging and evaluated microscopically. These results suggest the feasibility of this method as a new approach for making synthetic resinous stents.

Refinement of Plas Samples by Using Afm Image and First Observation of Plas Signals on Amorphous Carbon Nitridea-CNx Films

The shape of several waveguide end of samples for photoluminescence absorption spectroscopy (PLAS) was studied by atomic force microscope (AFM), because there was an experimental problem where some samples for PLAS did not work. Using the result of AFM, the waveguide end was reshaped by plasma dry etching. The shortening of the etching time was an effective method to improve the structure of the waveguide end. Secondly, the PLAS method was extended to the other materials from a-Si:H. The PLAS signal of amorphous carbon nitride a-CNx was detected for the first time. Amorphous carbon nitride a-CNx film itself and the interface between a-CNx and a-Si02 are found as good as a-Si:H and the interface between a-Si:H and a-Si 3N4+x:H, respectively.

Sensorless control for a sophisticated artificial myocardial contraction by using shape memory alloy fibre

The authors have been developing an artificial myocardium, which is capable of supporting natural contractile function from the outside of the ventricle. The system was originally designed by using sophisticated covalent shape memory alloy fibres, and the surface did not implicate blood compatibility. The purpose of our study on the development of artificial myocardium was to achieve the assistance of myocardial functional reproduction by the integrative small mechanical elements without sensors, so that the effective circulatory support could be accomplished. In this study, the authors fabricated the prototype artificial myocardial assist unit composed of the sophisticated shape memory alloy fibre (Biometal), the diameter of which was 100 microns, and examined the mechanical response by using pulse width modulation (PWM) control method in each unit. Prior to the evaluation of dynamic characteristics, the relationship between strain and electric resistance and also the initial response of each unit were obtained. The component for the PWM control was designed in order to regulate the myocardial contractile function, which consisted of an originally-designed RISC microcomputer with the input of displacement, and its output signal was controlled by pulse wave modulation method. As a result, the optimal PWM parameters were confirmed and the fibrous displacement was successfully regulated under the different heat transfer conditions simulating internal body temperature as well as bias tensile loading. Then it was indicated that this control theory might be applied for more sophisticated ventricular passive or active restraint by the artificial myocardium on physiological demand.

Development of an Artificial Myocardium using a Covalent Shape-memory Alloy Fiber and its Cardiovascular Diagnostic Response

The authors have been developing a newly-designed totally-implantable artificial myocardium using a covalent shape-memory alloy fibre (Biometal®, Toki Corporation), which is attached onto the ventricular wall and is also capable of supporting the natural ventricular contraction. This mechanical system consists of a contraction assistive device, which is made of Ti-Ni alloy. And the phenomenon of the martensitic transformation of the alloy was employed to achieve the physiologic motion of the device. The diameter of the alloy wire could be selected from 45 to 250μm. In this study, the basic characteristics of the fiber of 150μm was examined to design the sophisticated mechano-electric myocardium. The stress generated by the fiber was 400gf under the pulsatile driving condition (0.4W, 1Hz). Therefore it was indicated that the effective assistance might be achieved by using the Biometal shape-memory alloy fiber.

Dynamic response of the pulmonary circulation in continuous flow artificial heart systems

Pulmonary circulation dynamics is important when considering bi-ventricular assist devices (BiVAD) or total artificial heart (TAH) systems and in investigating the mechanism of atrial collapse in order to design better control algorithms. In this study, we investigated pulmonary circulation dynamics in a continuous flow artificial heart system by performing acute tests on a mature goat. By varying the right pump speed, we were able to observe the dynamic response of the left atrial pressure (LAP) and simulate conditions that result in atrial suction. The results showed a time constant characteristic of a compliance lag in LAP response to changes in right pump output in the TAH configuration. These results may prove useful in the design of a new mock circulatory system that incorporates the dynamics of the pulmonary circulation, and in the improvement of existing control algorithms that prevent atrial wall collapse.

Quantitative evaluation of the effect of visually-induced motion sickness using causal coherence function between blood pressure and heart rate

To evaluate the effect of visually-induced motion sickness on the human, blood pressure variability (BP) and heart rate variability (HR) of 51 normal subjects watching a 15min-long video image taken by a vibrating handy camera were analyzed. Not only coherence function (K/sup 2/) between BP and HR but also two causal coherence functions: K/sup 2//sub BP-->HR/ from BP to HR and K/sup 2//sub HR-->BP/ from HR to BP were introduced to divide causal linearity of the cardiovascular system regarded as a closed-loop system. K/sup 2/ represents total linearity of the system. K/sup 2//sub BP-->HR/ and K/sup 2//sub HR-->BP/ correspond to the baroreflex system and the mechanical hemodynamics, respectively. The results revealed that K/sup 2//sub BP-->HR/ at the Mayer wave-band (around 0.1 Hz) of the subjects prone to motion sickness decreased gradually and was significantly lower than that of the subjects not prone to in later scenes. This result has never been obtained from conventional methods dealing with a cardiovascular system as an open-loop system.

[Mediastinal lymph node adenocarcinoma with unknown primary site; report of a case]

A 78-year-old man with old tuberculosis was pointed out the high CEA (347 ng/ml) and a mass shadow in right side of middle mediastinum. Examination by bronchoscopy showed no abnormal finding, cytological diagnosis of sputum was negative. In computed tomography (CT), there was tumor-like shadow in the right upper lobe and mass shadow in the right side of middle mediastinum, and we suspected of lung cancer. We performed a wedge resection in the right upper lobe with regional lymph node dissection. In the histological diagnosis, there were no malignant finding in the right lung, and mediastinal lymph nodes showed poorly differentiated adenocarcinoma. In immunohistochemistry staining, CEA was positive, surfactant apoprotein and thyroid transcription factor-1 (TTF 1) were negative. Postoperative course was uneventful and 50 Gy radiotherapy were given. CEA was decreased to 2.1 ng/ml 6 months after the operation. This case was highly suspected to be a rare case of T0N2M0 lung cancer.

Effect of the alternative magnetic stimulation on peripheral circulation for regenerative medicine

Regenerative medicine for patients with peripheral atherosclerosis attracts considerable attention around the world. However, ethical problems persist in gene therapy. This study evaluates the effect of alterative magnetic stimulation on peripheral circulation. The effect of magnetic stimulation as a medical treatment was examined using a thermograph for 11 healthy volunteers. The thermograph was used to measure the rise in skin temperature. The experimental results suggested an improvement in the peripheral circulation. The results of our study suggest the effectiveness of alternative magnetic stimulation on atherosclerosis. We intend to extend our study in order to establish a methodology for regenerative medical treatment for patients with peripheral atherosclerosis. Further, we wish to advance the current research in the field of angiogenesis.

Cardio-ankle vascular index (CAVI) for the monitoring of the atherosclerosis after heart transplantation

Atherosclerosis has been reported to progress rapidly after heart transplantation. A quantitative diagnosis is required for the diagnosis of atherosclerosis after heart transplantation. In this study, we compared brachial-ankle pulse wave velocity (baPWV) and cardio-ankle vascular index (CAVI) for the diagnosis. The average values of both baPWV and CAVI in the seven cases after heart transplantation were found to be signif-icantly large in comparison to the average values of the normal healthy people of the same age group. When comparisons were made before and after the heart transplantation in a particular case, CAVI was stable and baPWV changed sharply. A lot of parameters such as blood pressure, blood volume, etc. have been reported to influence baPWV. The results of this study suggested that CAVI was a stable parameter in comparison to baPWV even after heart transplantation. Thus, CAVI may be useful in the diagnosis of arteriosclerosis after heart transplantation.

Chaos analysis of electro encephalography and control of seizure attack of epilepsy patients

In order to evaluate the EEG of patients with epilepsy, chaos analysis was performed for the subdural EEG time series data. The chaos attractor was reconstructed in the phase space and the correlation dimension. KS entropy calculated from the Lyapunov exponents was evaluated. Before the seizure attack, the KS entropy showed a lower value when compared with the time series data recorded during healthy condition. The results of our study suggest that it is possible to predict the seizure attack by the chaos analysis of the EEG signal. Further, we aim at developing an automatic control system for predicting a seizure attack by the use of local cooling of the focus with Peltier elements.

Effects of neuromuscular-blocking drugs in rats in vivo: direct measurements in the diaphragm and tibialis anterior muscle

BACKGROUND

Effects of neuromuscular-blocking drugs are often investigated in rodents using both the diaphragm in vitro and the tibialis anterior muscle in vivo. Differences in the properties of these muscles cannot be neglected. We evaluated the neuromuscular effects of drugs on the rat diaphragm in vivo in comparison with the tibialis anterior muscle, directly measuring twitch tension with a force transducer.

METHODS

Respectively using sternotomy and an approach via the gluteal space, transducers were attached to the diaphragm and the tibialis anterior muscle. Phrenic and sciatic nerves were stimulated supramaximally by single square pulses to record isometric contraction of muscles. Pancuronium, vecuronium, or rocuronium was infused continuously at a rate adjusted repeatedly until stable tension was obtained. Effective doses for 50% (ED 50) and 90% (ED 90) depression of tension were calculated, using a cumulative infusion dosing method.

RESULTS

Isometric contraction of the diaphragm could be recorded despite movements of the heart and lungs. For all three drugs, both mean ED 50 and ED 90 were more than twice as large for the diaphragm as for the tibialis anterior (P<0.05). In addition, slopes of dose-response curves for the diaphragm were significantly less steep than those of the tibialis anterior for the three drugs.

CONCLUSION

Neuromuscular-blocking effects on the diaphragm can be recorded in vivo. According to direct contractile force measurement, the diaphragm is more resistant to non-depolarizing neuromuscular-blocking drugs than the tibialis anterior muscle.

Miniature vibrating flow blood pump using a cross-slider mechanism for external shunt catheter

The prototype of the miniature vibrating flow pump (VFP) is developed for the external shunt catheter. The cross-slider mechanism is applied to vibrate the tube, which causes the pumping effect. This mechanism results in successful development of the miniature and lightweight VFP. By the use of the prototype VFP, the experiment of the basic pump performance is made in detail based on the authorized procedure in the research field of fluids engineering. The typical H-Q curve of VFP, which is the relationship between the pump head and the flow rate, can be obtained. This result suggests that the miniature VFP developed here can be expected to be used as the booster pump for the external shunt catheter in clinical applications.

[Recurrent pulmonary embolism with prolonged right heart failure and hypoxia after cerebral bleeding; report of a case]

A 56-year-old woman with right hemiplegia for recent cerebral bleeding suddenly complained of dyspnea and chest pain with hypoxia during rehabilitation. Eight days after this first attack, she suffered prolonged right heart failure and hypoxia due to recurrent pulmonary embolism. Arterial blood gas analysis of room air showed 34.5 mmHg of PaO2 and 29.2 mmHg of PaCO2. Echocardiography showed enlargement of the right atrium and ventricle with pulmonary hypertension. Enhanced chest computed tomography revealed pulmonary emboli from the main pulmonary artery to the periphery. Despite intensive treatment, heart failure and hypoxia did not improve. We conducted pulmonary embolectomy under cardiopulmonary bypass requiring percutaneous cardiopulmonary bypass support for 2 days due to right heart failure. She is currently doing well in the 9 months following surgery.

Fluctuations of Emax of the left ventricle: effect of atrial natriuretic polypeptide

Recently the circadian rhythm of fluctuations in heart rate variability (HRV) has gained increasing attention, and the use of appropriate treatment corresponding to the circadian rhythm has become an important issue. However, the question has been raised as to whether the rhythm of fluctuation is only limited to HRV, and if a rhythm is also present in the contraction of the heart. The mathematical technique of electrical circuit simulation of the cardiovascular system was used to observe the Emax rhythm. In this study, the therapeutic effect of various drugs, including atrial natriuretic polypeptide (ANP), was confirmed. The effect of inotropic drugs including ANP on Emax was observed, and the results based on an old and a new method of determining Emax . were examined. Furthermore, the chaos analysis of Emax was also made. The time series of Emax showed an increased complexity due to the administration of ANP. In conclusion, it might be important to consider not only the fluctuation of HRV, but also an analysis of the fluctuation in the contraction of the heart.

[Total aortic arch replacement for distal aortic arch aneurysm with adhered left lung: report of a case]

A 76-year-old man with a history of pleuritis and a cerebral infarct underwent a total arch replacement for an aneurysm of the distal aortic arch. Computed tomography revealed a true aneurysm having a maximum diameter of 70 mm as well as pleural thickening and calcification. Total arch replacement with selective cerebral perfusion was performed through median sternotomy and left thoracotomy. The myocardial ischemic time was shortened by reperfusion from the right axillary artery after the anastomosis of the proximal ascending aorta and the brachiocephalic artery. After the other branches of the arch were anastomosed, a distal anastomosis through the left thoracotomy was then performed using the pull-through method, enabling minimal decortication of the adhered lung. Our surgical procedure for distal arch aneurysm with adhered lung involves the addition of a left thoracotomy, but the reduction in the myocardial ischemic time and lung injury are of benefit.

Thoracoscopic surgery for pneumothorax in older patients

BACKGROUND

Secondary pneumothorax is more common in older pneumothorax patients. Therefore, we set out to investigate the usefulness of thoracoscopic surgery in this group.

METHODS

A total of 59 operations were performed on patients aged > or = 50 years, with the goal of excising only the lesions responsible for air leaks by using the minimum degree of dissection. If the patients were found to have numerous bullae, the lesions responsible were identified by pleurography. The duration of chest tube drainage, hospital stay, and recurrence were assessed.

RESULTS

The air leaks stopped and all patients were discharged without drains. Postoperative drainage time was 3.8 +/- 3.0 days. Postoperative hospital stay was 10.8 +/- 9.2 days. Six patients died of other diseases, but there was only one recurrence of pneumothorax.

CONCLUSION

We consider video-assisted thoracic surgery (VATS), with the goal of excising only the lesions responsible for air leaks, to be particularly efficacious in older pneumothorax patients.

Difference in sensitivity to vecuronium between patients with ocular and generalized myasthenia gravis

Patients with myasthenia gravis show sensitivity to non-depolarizing neuromuscular blocking drugs, but little is known about differences in this sensitivity between types of myasthenia. In 10 patients with ocular myasthenia gravis and 10 with generalized myasthenia gravis, twitch tension was monitored in the adductor pollicis muscle by supramaximal train-of-four stimulation of the ulnar nerve during anaesthesia with sevoflurane 2.5% and nitrous oxide 60%. After baseline measurement, an initial dose of vecuronium 10 microg kg(-1) was given. When the twitch height stabilized (maximum block after the first 10 microg kg(-1)), the next incremental dose of 10 microg kg(-1) was given and repeated until block, defined as [1-(first twitch/baseline first twitch)] x 100 reached 90%. Maximum block after the first dose of vecuronium in ocular patients was significantly less than that in generalized patients (median 51 vs 91%; P<0.05). Onset of block after the first dose of vecuronium was significantly slower in ocular than in generalized myasthenic patients (mean 300 vs 200 s; P<0.05). Doses required to attain a block of 90% or more were significantly higher in ocular than in generalized patients (median 20 vs 10 microg kg(-1); P<0.05). Clinicians should consider the type of disease according to the Osserman classification when using non-depolarizing neuromuscular. blocking drugs in patients with myasthenia gravis.

Measurement of antiacetylcholine receptor antibody in patients with thymoma without myasthenia gravis complications

OBJECTIVE

Some patients with thymoma reported to show higher antiacetylcholine receptor antibody titers without the preoperative occurrence of myasthenia gravis and some have suffered postoperative complications of myasthenia gravis despite being negative for antiacetylcholine receptor antibody preoperatively. We evaluated changes in antiacetylcholine receptor antibody titers and the occurrence of myasthenia gravis in thymoma patients.

METHODS

Subjects were 31 of 44 patients with thymoma undergoing thymothymectomy at Tokyo Women's Medical University Hospital between 1987 to 1999 in whom antiacetylcholine receptor antibody titers were measured preoperatively. We studied postoperative changes in antiacetylcholine receptor antibody titers and the presence or absence of myasthenia gravis.

RESULTS

Eight patients were positive for antiacetylcholine receptor antibody preoperatively, suggesting the presence of subclinical myasthenia gravis. Neither postoperative changes in antiacetylcholine receptor antibody titers nor the occurrence of myasthenia gravis was observed in these 8 patients. Recurrent thymoma and rapid elevation of antiacetylcholine receptor antibody titers were observed postoperatively in 1 patient negative for antiacetylcholine receptor antibody preoperatively, resulting in manifestation of myasthenia gravis symptoms.

CONCLUSION

We found no correlation between preoperative titers and myasthenia gravis symptoms. Rapid titer elevation indicates the occurrence of myasthenia gravis symptoms or the recurrence of thymoma.

Application of scanning acoustic microscopy for assessing stress distribution in atherosclerotic plaque

Scanning acoustic microscopy (SAM) was equipped to assess the acoustic properties of normal and atherosclerotic coronary arteries. The SAM image in the atherosclerotic lesion clearly demonstrated that the sound speed was higher than that in the normal intima, and that the variation of elasticity was found within the fibrous cap of the plaque. Young's elastic modulus of each region was calculated and the finite element analysis was applied to derive the stress distribution in these arterial walls. In a case of normal coronary artery, the stress was dominant in the intima and the distribution was rather homogeneous and in a case of atherosclerosis, high stress was concentrated to the relatively soft lesion in the fibrous cap overlying lipid pool. SAM provides information on the physical properties, which cannot be obtained by the optical microscope. The results would help in understanding the pathological features of atherosclerosis.

Role of hydrophilic interaction in binding of hydroxylated 3-deoxy C(19) steroids to the active site of aromatase

As part of our investigation into the structure-activity relationship of a novel class of aromatase inhibitors, C(19) steroids having no oxygen function at C-3, we tested aromatase inhibition activity of polar diol compounds 4,19-dihydroxyandrost-5-en-17-ones (25 and 27) and 6,19-dihydroxyandrost-4-en-17-ones (36 and 37). 4alpha,19-Diol 25 was synthesized from tert-butyldimethylsilyoxyandrost-4-ene steroid (9) through its OsO(4) oxidation, giving the 4alpha,5alpha-dihydroxy derivative 12, as a key reaction. Acetylation of 5beta,6alpha-dihydroxy-19-acetate 30 and its 5alpha,6beta-analogue 31 followed by dehydration with SOCl(2) and alkaline hydroxysis gave 6alpha,19-diol 36 and its 6beta-isomer 37, respectively. The stereochemistry of a hydroxy group at C-4 of compound 25 and that at C-6 of compounds 36 and 37 were determined on the basis of (1)H NMR spectroscopy in each case. 4beta,19-Diol 27, previously synthesized, was identified as an extremely powerful competitive inhibitor of aromatase (K(i) = 3.4 nM). In contrast, its 4alpha,19-dihydroxy isomer 25 and other series of diol compounds, 6,19-dihydroxy-4-en-17-one steroids, were moderate to poor competitive inhibitors (K(i) = 110-800 nM). Through this series of analyses, it was concluded that hydrophilic interaction of a 4beta,19-diol function with the active site of aromatase plays a critical role in the tight binding of 3-deoxy-5-ene steroids.

Automatic monitoring system for artificial hearts using self organizing map

This study presents an automatic monitoring system for artificial hearts. The self organizing map (SOM) was applied to monitoring and analysis of an aortic pressure (AoP) signal measured from an adult goat equipped with a total artificial heart. In the proposed system, two different SOMs were used to detect and classify abnormalities in the measured AoP signal. In the first stage, an ordinary SOM, taught with only normal AoP data, was used for detection of abnormalities on the basis of the quantization error in the real-time monitoring task. In the second stage, a supervised SOM was used for classification of abnormalities. The supervised SOM can be regarded as an ordinary SOM with an extra class vector for solving the classification problem. The class vector is assigned to every node in the second SOM as an output weight learned according to Kohonen's learning rule. The effectiveness of detection and classification of abnormalities using these two SOMs was confirmed.

Discrimination of ameloblastomas from odontogenic keratocysts by cytokine levels and gelatinase species of the intracystic fluids

In the present study, we measured the levels of the cytokines and gelatinase species in the fluids of ameloblastomas and odontogenic keratocysts, and showed that ameloblastomas can be distinguished from odontogenic keratocysts by the use of these biochemical data. We found that interleukin (IL)-1alpha and IL-1beta levels in the intracystic fluids of ameloblastomas were significantly lower than those in the fluids of odontogenic keratocysts, while IL-6 levels in the fluids of ameloblastomas were significantly higher than those in the fluids of odontogenic keratocysts. On the other hand, no significant differences in tumor necrosis factor (TNF)-alpha levels of the fluids were detected between ameloblastomas and odontogenic keratocysts. An immunohistochemical study revealed that the staining intensity of IL-1alpha, IL-1beta and TNF-alpha in the tumor cells of ameloblastomas was significantly weaker than that in the epithelial cells of odontogenic keratocysts, while the staining intensity of IL-6 in the tumor cells was significantly stronger than that in the epithelial cells of odontogenic keratocysts. Gelatin zymography of the fluids showed that only a small amount of pro-MMP-9 was detected in ameloblastomas, while both pro-MMP-9 and the active form of MMP-9 were detected in 8 of 10 cases of odontogenic keratocysts. Thus, ameloblastomas can be distinguished from odontogenic keratocysts by measuring IL-1alpha and IL-6 levels, and gelatinase species in the fluids.

An approach to acoustic properties of biological tissues using acoustic micrographs of attenuation constant and sound speed

OBJECTIVE

To develop a method for two-dimensional measurement of acoustic properties of biological tissue elements at the microscopic level for specimens with a thickness of approximately 10 microm.

METHODS

The procedure was developed on the basis of mechanically scanned acoustic microscopic techniques in the frequency range of 100 to 200 MHz and the theory of interference phenomena. Various tissues and samples were prepared to evaluate the method and to interpret sound propagation properties.

RESULTS

Tissues with high protein content, low water content, or both had a high attenuation constant and sound speed. The exponent n of attenuation against frequency was almost unity at the microscopic level, whereas it was greater than unity when the specimen thickness was greater. Sound speed dispersion was not observed.

CONCLUSIONS

The method was shown to be reproducible, and the data were interpreted acoustically and pathologically with reference to tissue type and specimen thickness.

Development of an implantable artificial anal sphincter by the use of the shape memory alloy

In this study, we developed and assessed an artificial anal sphincter driven by an shape memory alloy actuator (AS-SMA). The performance characteristics of the device were analyzed with a measurement system. Assessment showed that the AS-SMA could generate a pressure of 55 mm Hg at an atmospheric temperature of 36 degrees C, and displacement of the SMA actuator was 7.5 mm when the temperature of the SMA plate was 55 degrees C. To evaluate opening and closing, we studied a piglet colostomy model, in which the AS-SMA was implanted around the colostomy in the extraperitoneal space. Flow control tests using living porcine intestine revealed that the AS-SMA could maintain fecal continence against an intestinal pressure of 75 mm Hg. The high pressure zone corresponding to the location of the device was demonstrated in a manometric examination. For 6 days after surgery, we activated the AS-SMA twice a day and observed the bowel movements. The animal experiment indicated that the AS-SMA is able to control the bowel movements of patients with fecal incontinence if several problems, such as burning of tissue around the device and compression injury of the intestine, are resolved.

The role of video-assisted thoracoscopic surgery in the diagnosis of the small peripheral pulmonary nodule

BACKGROUND

The use of imaging techniques to detect small peripheral pulmonary nodules often results in a missed diagnosis. Thoracoscopy had limited application until recently, when advances in technology allowed thoracic surgeons greater visualization and mobility within the chest.

METHODS

Between September 1992 and June 1997, 81 patients were treated for small peripheral pulmonary nodules by pulmonary wedge excision using video-assisted thoracoscopic techniques. The patients were 39 men and 42 women with an average age of 59.5 years.

RESULTS

A definitive diagnosis was obtained in all cases. Malignancies were found in 44 patients (55%), which involved primary lung cancer in 28 patients and metastatic lesions in 16 patients. The rate of malignancy in nodules measuring 1 cm or less was 18%. There was no operative mortality or morbidity.

CONCLUSIONS

We conclude that video-assisted thoracoscopic lung biopsy is a more effective and less invasive diagnostic tool for small peripheral pulmonary nodules.

Neuromuscular monitoring in myasthenic syndrome

We describe the anaesthetic management of a 72-year-old man with myasthenic syndrome. Pre-operatively, he was treated with 3,4-diaminopyridine and showed a strong hand grip. During general anaesthesia with nitrous oxide and sevoflurane in oxygen, a mechanomyograph and two accelerographs were set up for the hands and left foot to monitor neuromuscular function. Insufficient force and acceleration of contraction with 1 Hz stimulation was observed in the hands. In the foot, the twitches produced by 1 Hz and train-of-four stimulation could barely be detected using the accelerograph, and the train-of-four ratio fluctuated between 70 and 100%. No neuromuscular blocking drugs were used during surgery. After discontinuation of sevoflurane, responses to train-of-four stimulation remained small, but a strong response to tetanic stimulation was observed, with post-tetanic facilitation. Extubation was successful, and recovery from anaesthesia was uneventful. Tetanic stimulation and post-tetanic facilitation are important in monitoring neuromuscular function in patients with myasthenic syndrome whose train-of-four responses are insufficient.

Bullectomy is beneficial in the pulmonary blood flow/driving pressure relationship in bullous emphysema patients

OBJECTIVES

Few physiological studies have been on pulmonary circulation, including the relationship between pulmonary blood flow and driving pressure, and viscosity changes arising from hematocrit changes before versus after lung volume reduction Surgery or bullectomy in emphysematous patients.

METHODS

We studied the relationship between pulmonary blood flow and driving pressure before and after bullectomy using a unilateral pulmonary artery occlusion test based on pulmonary blood flow fractions obtained by pulmonary blood flow scintigraphy in 7 patients with pulmonary emphysema associated with bullae.

RESULTS

Among the 7 undergoing bullectomy, the pulmonary blood flow/driving pressure relationship decreased in 5 and was unchanged in 2. Of the 11 lungs treated by bullectomy, this relationship decreased in 8 lungs, but not 3 (p < 0.01). No significant difference was seen in oxygen partial pressure in arterial and mixed venous blood or hematocrit.

CONCLUSION

We concluded that bullectomy shifted the pulmonary blood flow/driving pressure relationship downword in some cases with significant bullae.

Nitinol stent for the treatment of tracheobronchial stenosis

OBJECTIVE

The purpose of this study was to evaluate the potential utility of implantation of a nickel-titanium alloy (nitinol) stent for the treatment of malignant or benign tracheobronchial stenosis.

METHODS

We evaluated 18 patients (14 men and 4 women) who received 24 nitinol stents, between November 1997 and May 2000. All 18 patients had severe dyspnea caused by tracheobronchial stenosis. The underlying condition was malignant disease in 15 patients, and benign tracheal collapse in the other 3 patients.

RESULTS

Implantation of the stent was successfully performed in all patients. Seventeen patients experienced immediate clinical improvement in respiratory symptoms. The remaining 1 patient with a bronchial fistule after lobectomy did not benefit, and died of pneumonia at 16 days after the implantation. In 15 patients, the procedure was performed using a flexible bronchoscope under local anesthesia alone, while the remaining 3 patients needed intravenous sedation. There was no complication resulting from the stent implantation. Among the 3 patients with benign tracheal collapse, 2 patients were alive at 746 and at 401 days after the stent implantation, at the time of this report. One patient with cicatricial stenosis after intubation died of heart failure due to previous myocardial infarction. Among the 15 patients with malignant disease, 4 patients have survived for 177 to 305 days to date, while the other 11 patients have died of primary malignancy with a mean survival duration of 60.2 days.

CONCLUSION

The nitinol stent was effective in treating malignant or benign tracheobronchial stenosis, and had some remarkable advantages compared with other tracheobronchial stents. In stenting, most procedures can be performed using flexible bronchoscope under local anesthesia.

Wallstent endovascular prosthesis for the treatment of superior vena cava syndrome

OBJECTIVE

We assessed the clinical outcome of self-expanding Wallstent endovascular prosthesis in the treatment of superior vena cava syndrome due to malignant tumors.

METHODS

Eleven patients with malignant superior vena cava syndrome were treated by percutaneous implantation of the self-expanding Wallstent endovascular prosthesis across the stricture site. Patency was defined by the absence of symptoms and signs of superior vena cava syndrome.

RESULTS

Ten of the 11 experienced complete symptomatic relief within 3 days of stent implantation. The remaining 1 did not benefit, and required a second procedure, dying of heart failure 5 days after stent implantation. Ten patients remain symptomatically free of superior vena cava syndrome to date or until death in follow-up lasting 17 to 227 days.

CONCLUSION

Implantation of the self-expanding Wallstent endovascular prosthesis for malignant superior vena cava syndrome provides rapid symptomatic relief and improves the patient's quality of life.

Surgical management of multidrug-resistant tuberculosis

We report surgical resections in 3 patients with active multidrug-resistant tuberculosis. All cases involved strains of Mycobacterium tuberculosis resistant to at least isoniazid and rifampin and patients who were poor candidates for medical therapy alone. We conducted pulmonary resections (partial resection in case 1, lobectomy in case 2, and segmentectomy in case 3). The optimum multiple-drug regimen, based on drug susceptibility studies, was used preoperatively and postoperatively. In all cases, sputum smears and cultures yielded negative results postoperatively, and continue to be negative for Mycobacterium tuberculosis to date. It is recommended that, if localized disease is present and medical treatment is likely to fail, pulmonary resection be conducted for multidrug-resistant Mycobacterium tuberculosis.

Automatic detection and classification of abnormalities for artificial hearts using a hierarchical self-organizing map

A hierarchical self-organizing map (SOM) has been developed for automatic detection and classification of abnormalities for artificial hearts. The hierarchical SOM has been applied to the monitoring and analysis of an aortic pressure (AoP) signal measured from an adult goat equipped with a total artificial heart. The architecture of the network actually consists of 2 different SOMs. The first SOM clusters the AoP beat patterns in an unsupervised way. Afterward, the outputs of the first SOM combined with the original time-domain features of beat-to-beat data are fed to the second SOM for final classification. Each input vector of the second SOM is associated with a class vector. This class vector is assigned to every node in the second map as an output weight and learned according to Kohonen's learning rule. Some experimental results revealed that a certain abnormality caused by breakage of sensors could be identified and detected correctly and that the change in the state of the circulatory system could be recognized and predicted to some extent.

Clinical assessment of unilateral pulmonary artery occlusion test with dobutamine infusion. Expansion of surgical indications in patients with primary lung cancer and impaired cardiopulmonary functions

OBJECTIVES

We evaluated the possibility of expanding indications for pulmonary resection based on an assessment of the pressure-flow relationship in pulmonary circulation.

METHODS

In 6 of 28 lung cancer patients whose total pulmonary vascular resistance index exceeded the threshold during unilateral pulmonary artery occlusion testing, we conducted unilateral pulmonary artery occlusion testing with dobutamine administration, followed by lung resection. We studied hemodynamics during testing and derived a new indication for pulmonary resection from the postoperative course.

RESULTS

Cardiac output was 3.82 +/- 0.74 l/min before testing, 3.66 +/- 0.76 l/min during pulmonary artery occlusion testing, and 5.92 +/- 1.78 l/min during unilateral pulmonary artery occlusion testing with dobutamine infusion. The total pulmonary vascular resistance index was 890 +/- 350 dyne.sec.cm-5.m2 before testing, 1170 +/- 320 dyne.sec.cm-5.m2 during testing, and 800 +/- 160 dyne.sec.cm-5.m2 during testing with dobutamine infusion. Cardiac output increased (p = 0.014) during unilateral pulmonary artery occlusion testing with dobutamine infusion, and the total pulmonary vascular resistance index significantly decreased (p = 0.034). Of the 4 patients eligible for lobectomy, 2 underwent the procedure--one undergoing segmentectomy in which pulmonary metastasis was found during surgery and the other undergoing radiotherapy for cN2 disease with chest wall invasion. Of the 2 initially ineligible for lobectomy, one underwent partial pulmonary resection and the other underwent lobectomy because the total pulmonary vascular resistance index was less than 800 dyne.sec.cm-5.m2 during selective pulmonary artery occlusion testing with dobutamine infusion, indicating eligibility for lobectomy. No severe complications of cardiopulmonary function failure after surgery occurred in any of the 5 cases.

CONCLUSIONS

Unilateral pulmonary artery occlusion testing with dobutamine infusion is useful in determining patient eligibility for pulmonary resection.

Pulmonary multiple metastases of ovarian granulosa cell tumor 15 years after initial diagnosis

We report a case of multiple pulmonary metastases occurring 15 years after an ovarian granulosa cell tumor was initially diagnosed. A 62-year-old woman undergoing left salpingo-oophorectomy for a granulosa cell tumor of the left ovary 15 years earlier presented with abnormal chest shadows. Computed tomography of the chest confirmed the presence of 3 well-defined nodular lesions, and Computed tomography of the abdomen and pelvis revealed a 3.5 x 2.5 cm partially solid, cystic pelvic mass. Left thoracotomy was conducted and tumors diagnosed a pulmonary metastases of a granulosa cell tumor. The pelvic mass was resected and infracolic omentectomy then conducted with total hysterectomy and right salpingo-oophorectomy including the adherent rectal segment. The pelvic mass proved to be a granulosa cell tumor. Adjuvant combination chemotherapy was started every 3 weeks and the woman has remained disease-free for 9 months.