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.

Insight into the performance of multi-color InGaN/GaN nanorod light emitting diodes.

We report on the thorough investigation of light emitting diodes (LEDs) made of core-shell nanorods (NRs) with InGaN/GaN quantum wells (QWs) in the outer shell, which are grown on patterned substrates by metal-organic vapor phase epitaxy. The multi-bands emission of the LEDs covers nearly the whole visible region, including UV, blue, green, and orange ranges. The intensity of each emission is strongly dependent on the current density, however the LEDs demonstrate a rather low color saturation. Based on transmission electron microscopy data and comparing them with electroluminescence and photoluminescence spectra measured at different excitation powers and temperatures, we could identify the spatial origination of each of the emission bands. We show that their wavelengths and intensities are governed by different thicknesses of the QWs grown on different crystal facets of the NRs as well as corresponding polarization-induced electric fields. Also the InGaN incorporation strongly varies along the NRs, increasing at their tips and corners, which provides the red shift of emission. With increasing the current, the different QW regions are activated successively from the NR tips to the side-walls, resulting in different LED colors. Our findings can be used as a guideline to design effectively emitting multi-color NR-LEDs.

[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.

Study of stimulation-secretion coupling in a flow culture system: periodic secretion of hepatocyte growth factor by interleukin-1 alpha-stimulated human embryonic lung fibroblasts.

In order to closely examine stimulation-secretion coupling, the authors developed a 'flow culture system' in which it is possible to continuously replace the culture medium. This lessens the effects of cell-derived products observed in the conventional culture system. We compared our flow culture system and the conventional culture system based on the secretion patterns and concentrations of human hepatocyte growth factor (HGF) produced by interleukin 1 alpha (IL-1 alpha)-stimulated human embryonic lung fibroblasts (MRC-5). While the cells in the conventional culture system secreted HGF at a nearly constant rate, the cells in the flow culture system secreted HGF periodically. Even short-term stimulation with IL-1 alpha for 4 h resulted in significant HGF secretion continuing for at least 46 h. Thus the inflammatory cytokine IL-1 alpha was shown to modulate fibroblast secretion of HGF. The periodic secretion of HGF may play an important role in tissue repair and regeneration. Based on the results of actually applying it, we conclude that our flow culture system is an efficient and accurate model for the detailed examination of stimulation-secretion coupling.

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.

Alterations in modulation of acetylcholine release following lesion of hippocampal cholinergic neurons with the neurotoxin AF64A.

Accumulation of acetylcholine (ACh) following administration of physostigmine or tetrahydroaminoacridine (THA) normally inhibits further evoked release of ACh through presynaptic muscarinic receptors. However, in cerebral cortical slices from patients with Alzheimer's disease, ACh release is enhanced by THA, an effect mediated via nicotinic receptors. In this study, the effects of THA and physostigmine were examined in hippocampal slices from rats in which cholinergic neurons were lesioned with the neurotoxin ethylcholine mustard aziridinium (AF64A). Physostigmine and THA did not reduce the evoked release of ACh in lesioned tissues as they did in controls, and THA significantly increased release. The enhancement of release by THA was blocked by the nicotinic antagonist mecamylamine, suggesting that it was mediated through nicotinic receptors. Direct stimulation of muscarinic receptors with oxotremorine significantly reduced ACh release in control tissues, but had no effect in lesioned slices, indicating that presynaptic muscarinic receptors were no longer operative. These results suggest that adaptive changes in nicotinic and muscarinic receptors occur in AF64A-treated rats which are similar to those reported in Alzheimer's disease.

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.

Degree of severity of pectus excavatum and pulmonary function in preoperative and postoperative periods.

Pulmonary function was evaluated in 138 patients with pectus excavatum, paying particular attention to the degree of severity of chest deformity. We defined the severity of deformity quantitatively based upon a computed tomographic index obtained from a computed tomogram. We recognized a positive relationship between computed tomographic index (x) and percent vital capacity (y), as follows: y = 137x + 58 (n = 138, r = 0.61, p < 0.05). Pulmonary function tests were performed from 2 to 42 months postoperatively. Vital capacity decreased about 10% from the baseline value during the initial 2 months after surgical treatment and recovered to the preoperative level by 1 year after surgery. At 42 months after surgical correction, the pulmonary function was maintained at the baseline level and the severity of deformity was significantly improved. Surgical procedures for the treatment of pectus excavatum--sternocostal elevation and sternal turnover--resulted in an excellent cosmetic result but did not importantly affect respiratory function.

Sound spectral analysis of prosthetic valvular clicks for diagnosis of thrombosed Björk-Shiley tilting standard disc valve prostheses.

To evaluate clinical usefulness of sound spectral analysis in the early detection of prosthetic thrombosis, we analyzed specific patterns of thrombus formation in Björk-Shiley tilting standard disc prostheses in relation to the sound spectral analysis of their click sounds. Among a total of 365 Björk-Shiley tilting standard disc prostheses, nine became thrombotic. These consisted of seven prostheses in the mitral position and two in the aortic position, and the affected valves were replaced in all cases. The sound spectral analysis system includes a wide-frequency microphone and a sound spectral analyzer. To quantify the amplitude of the metallic clicks that are specific to the prosthetic valve sounds, we used a normalized maximal frequency as a diagnostic parameter for valve thrombosis. Thrombus formation was localized at the minor strut in two cases, and these demonstrated abnormally low normalized maximal frequency values only on opening clicks. In four cases thrombus formations were noted at both minor and major struts, and these showed abnormally low normalized maximal frequency values on both opening and closing clicks. In two cases with pannus formation, no abnormalities were found by sound spectral analysis. In one case, which had demonstrated abnormally decreased normalized maximal frequency values of both opening and closing clicks, the normalized maximal frequency values were normalized after thrombolytic therapy, suggesting resolved thrombosis. Reoperation, which was performed for concomitant complication of perivalvular leak, revealed no noticeable thrombus formation. The thrombi were seen on the minor strut during surgical procedures in all cases in which valve thrombosis was indicated by the sound spectral analysis. Therefore, the minor strut is considered to be the prevalent area of thrombus formation, and diagnosis could be made after observation of abnormally low normalized maximal frequency on opening clicks. We found the sound spectral analysis to be an extremely useful diagnostic tool for early detection of thrombosis in the Björk-Shiley tilting standard disc prostheses, especially because the opening clicks of the tilting disc valve were too low in amplitude for auscultation to detect the existence of mild abnormality.

Real-time sound spectroanalysis for diagnosis of malfunctioning prosthetic valves.

A newly developed real-time sound spectroanalyzer was found to be capable of diagnosing malfunction of prosthetic heart valves. Sound spectroanalysis is believed to be superior to other methods such as phonocardiography and echocardiography. This system, developed in our institute, allows display on a cathode ray oscilloscope of five different modes of the valvular click, including the sound spectrograph and section pattern. Analysis of the section pattern allows measurement of the high-frequency components of the valvular click, which is normalized so as to be applicable to a click of any intensity. This parameter is called normalized maximal frequency (NMF). Sound spectroanalyses were carried out 228 times on 127 patients having a prosthetic heart valve. NMF values of normally functioning valves differed characteristically according to the type of valve, but did not change during the postoperative time course. Three of seven patients who had cerebral embolism showed significantly lower NMF values than normal, as did all four patients whose valve had become thrombosed.

Multivariate analysis of risk factors for thrombus formation in University of Tokyo ventricular assist device.

Of 77 University of Tokyo ventricular assist devices used in a total of 70 patients at 21 institutions, 13 pumps were found to have macroscopic thrombus formations. Because 19 devices that were used for less than 24 hours showed no thrombus deposition, they were considered not to have been sufficiently exposed to the thrombogenic environment for macroscopic thrombus deposition and were removed from the subsequent multivariate study. A total of eight potential risk factors were assessed in relation to thrombosis. Prevalences of thrombus formation were compared between two groups with or without each of the risk factors. In a univariate analysis, the following categoric variables were demonstrated to be significantly associated with complications, in descending order of significance: use of gabexate mesilate (protease inhibitor) as an anticoagulant (p = 0.005), normal platelet count (p = 0.010), duration of support (p = 0.038), leukocytosis (p = 0.042), and minimum pumping flow (p = 0.042). Use of heparin and the consequent increase in activated clotting time showed no relationship. Multivariate discriminant analysis, which was done to identify risk factors rejecting cross correlation between each variable, demonstrated platelet count (p = 0.006), use of gabexate mesilate (p = 0.007), and minimum flow (p = 0.008) to have significant and independent risks. These results indicate the importance of maintaining pumping flow above a certain minimum level, addition of antiplatelet drugs to the antithrombogenic regimen, and nonuse of gabexate mesitate.

Effects of LF-14, THA and physostigmine in rat hippocampus and cerebral cortex.

The effects of physostigmine, tetrahydroaminoacridine (THA) and LF-14 [3,3-dimethyl-1(4- amino-3-pyridyl)urea], a 3,4-diaminopyridine derivative, were compared on inhibition of acetyl- cholinesterase (AChE) activity, and release of [(3)H]acetylcholine (ACh) from rat brain cortical and hippocampal slices. All three compounds caused a concentration dependent inhibition of AChE, with an order of potency physostigmine > THA >LF-14. The electrically stimulated release of ACh from hippocampal and cortical slices was decreased by 10(?5)M physostigmine, although the effect was significant only in cortex. THA (5 x 10(5)M) caused a slight, but not significant, decrease in ACh release from both tissues. In contrast, LF-14 (5 x 10(?5) M) caused an approx. 3-fold enhancement of stimulated release. When AChE was inhibited by prior addition of physostigmine, THA caused only a slight enhancement of ACh release, whereas LF-14 greatly increased release. ACh release was also reduced by stimulation of presynaptic muscarinic receptors with oxotremorine. In this case, THA had no effect on ACh release, while LF-14 was able to reverse the inhibition. This study suggests that LF-14 acts to promote ACh release through blocking K(+) channels, and has a less potent AChE inhibitory effect. It is possible that a compound like LF-14 could be useful in treating diseases of cholinergic dysfunction such as Alzheimer's disease, by both promoting the release of ACh and inhibiting its breakdown.

Effects of surfactant proteins SP-B and SP-C on dynamic and static mechanics of immature lungs.

To investigate the effects of surfactant proteins B (SP-B) and C (SP-C) on lung mechanics, we compared tidal and static lung volumes of immature rabbits anesthetized with pentobarbital sodium and given reconstituted test surfactants (RTS). With a series of RTS having various SP-B concentrations (0-0.7%) but a fixed SP-C concentration (1.4%), both the tidal volume with 25-cmH2O insufflation pressure and the static volume deflated to 5-cmH2O airway pressure increased, significantly correlating with the SP-B concentration: the former increased from 6.5 to 26.0 ml/kg (mean), and the latter increased from 6.4 to 31.8 ml/kg. With another series of RTS having a fixed SP-B concentration (0.7%) but various SP-C concentrations (0-1.4%), the tidal volume increased from 5.1 to 24.8 ml/kg, significantly correlating with the SP-C concentration, whereas the static volume increased from 3.4 to 32.0 ml/kg, the ceiling value, in the presence of a minimal concentration of SP-C (0. 18%). In conclusion, certain doses of SP-B and SP-C were indispensable for optimizing dynamic lung mechanics; the static mechanics, however, required significantly less SP-C.

Production of controlled reversible left ventricular failure in calves using intracoronary lidocaine hydrochloride: a useful method of evaluating left ventricular assist devices.

The experimental production of stable, controlled, short-term left ventricular failure is valuable in the evaluation of implantable circulatory support systems. Acute or chronic left ventricular failure produced by occlusion or embolization of coronary arteries results in muscle dysfunction and degrees of failure that may be difficult to control. The effects of varying amounts of intracoronary lidocaine were studied during short- and long-term evaluations of intracorporeal left ventricular assist pumping. In 8 Hereford calves the left main coronary artery was cannulated with an intracoronary catheter in open and closed chest preparations. Dose-related negative inotropic effects were noted when lidocaine was injected at individual doses of 50, 75, and 100 mg. Following 100 mg doses, mean aortic pressure, cardiac output, and maximum rate of rise of left ventricular pressure decreased; left ventricular end-diastolic pressure increased fourfold. Similar effects were noted with short continuous infusions of lidocaine. The initial responses to injection or continuous infusions, if effective, were noted within 40 to 60 seconds. Several episodes of failure could be produced with either method following recovery periods of 10 to 15 minutes. In all instances, actuation of a left ventricular assist device immediately reversed the hemodynamic effects of the pharmacologically induced failure.

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.

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.

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.

Acoustic properties of atherosclerosis of human aorta obtained with high-frequency ultrasound.

The ultrasonic properties of the tissue elements in the aorta were measured using a scanning acoustic microscope (SAM). Twelve autopsied aortas were formalin-fixed, frozen and sectioned at 10 microm thickness and mounted on glass slides for SAM investigation. A specially developed SAM system operating in the frequency range of 100-200 MHz was employed, and color-coded images of the two-dimensional (2-D) distributions of attenuation and sound speed were displayed. The region-of-interest (ROI) for attenuation and sound speed measurements was determined by comparison of optical and acoustic images. The average value of the slope of attenuation was 0.61 dB/mm/MHz and the sound speed was 1568 m/s in the normal intima; 2.5 dB/mm/MHz, 1760 m/s in the calcificated lesion; 1.7 dB/mm/MHz and 1677 m/s in the fibrosis; and 0.34 dB/mm/MHz, 1526 m/s in the fatty material, respectively. Acoustic microscopy provides the basic data for understanding the IVUS imaging of atherosclerosis, as well as on the pathological features of atherosclerosis.