Carrier kinetics and electron-polar-optical-phonon interaction in ZnSe studied by optically detected cyclotron resonance.
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Journal Article↗
Biomedical subjects
T Tomaru
Publications and source records attributed to T Tomaru.
Salvage of infarcted myocardium by angiogenic action of basic fibroblast growth factor.
Coronary collateral vessels reduce damage to ischemic myocardium after coronary obstruction. Factors that stimulate collateral formation are expected to have ameliorating effects on myocardial infarction. In a canine experimental myocardial infarct model, intracoronary injection of basic fibroblast growth factor (bFGF) improved cardiac systolic function and reduced infarct size. Treatment with bFGF increased the number of arterioles and capillaries in the infarct. Thus, the angiogenic action of bFGF might lead to a reduction in infarct size. The application of bFGF might bring about a therapeutic modality for the salvage of infarcted myocardium.
Animals↗
Comparison of ablation efficacy of excimer, pulsed-dye, and holmium-YAG lasers relevant to shock waves.
Ablation efficacy of pulsed lasers on human arterial tissue and associated shock waves have been investigated by means of excimer laser at 308 nm, pulsed-dye laser at 480 nm, and holmium-YAG laser at 2.1 microns. A multifiber catheter was used for lasing at 420 mjoules/pulse with holmium-YAG, 18.9 mjoules/pulse with excimer, and 100 mjoules/pulse with pulsed-dye laser. Ablation efficiency (ablated volume/energy) was greatest with pulsed-dye laser in blood and excimer laser in saline solution. There was selectivity for atheroma with pulsed-dye laser (ablation efficiency in atheroma versus normal tissue, 58 versus 27 x 10(-2) mm3/joule in blood; p less than 0.005) and holmium-YAG laser (12.6 versus 5.6 x 10(-2) mm3/joule in blood; p less than 0.001). Ablation efficiency of pulsed-dye laser was enhanced by blood (0.58 in blood versus 0.17 mm3/joules in saline for atheroma; p less than 0.005). Shock waves were correlated with ablation efficiency (r = 0.63 and 0.74 for pulsed-dye laser and holmium-YAG laser, respectively). There was neither selectivity for atheroma nor influence of blood medium with excimer laser. Only holmium-YAG laser could ablate tissue at a distance from the target in the blood medium. Histologic findings showed that all lasers could create smooth-edged craters with minimal coagulation necrosis. In conclusion, laser irradiation with holmium-YAG and pulsed-dye lasers could selectively ablate atheromatous tissue with minimal thermal injury, whereas excimer laser could not. Ablation efficiency was correlated with shock waves. Efficiency of pulsed-dye laser was enhanced by blood.
Angioplasty, Laser↗
Characteristics of shock waves induced by pulsed lasers and their effects on arterial tissue: comparison of excimer, pulse dye, and holmium YAG lasers.
Shock waves were investigated using an excimer laser at 308 nm with 18.9 mjoules/pulse, a pulsed dye laser at 480 nm with 100 mjoules/pulse, and a holmium YAG (yttrium-aluminum-garnet) laser at 2.1 microns with 420 mjoules/pulse. At a distance from the target tissue, excimer lasing resulted in no shock waves in saline, while the other lasers produced smaller shock waves than those recorded when the laser was in contact with tissue (0.22 versus 2.0 mm Hg with the pulsed dye laser, 0 versus 0.23 mm Hg with the excimer laser, and 0.44 versus 6.9 mm Hg with the holmium YAG laser; p less than 0.001, respectively). In blood, excimer laser irradiation at a distance from the tissue produced shock waves as great as those produced when the laser was in contact with the tissue (0.19 versus 0.24 mm Hg with the excimer laser, 1.8 versus 3.0 mm Hg with the pulsed dye laser, and 3.1 versus 5.9 mm Hg with the holmium YAG laser; p less than 0.001 with the pulsed dye and holmium YAG lasers, respectively). When lasing was done at 60 mjoules/mm2, the pulsed dye and excimer lasers produced similar shock waves when the lasers were in contact with tissue; however, the holmium YAG laser did not produce shock waves. Thus pulsed lasers can produce shock waves of different characteristics according to the laser source.
Analysis of Variance↗
Percutaneous angioplasty of chronic obstruction of peripheral arteries by a temperature-controlled Nd:YAG laser system.
The feasibility of an Nd:YAG laser system with automatic control of hot-tip probe temperature was examined in 15 segments (14.7 +/- 6 cm in length) of iliofemoral arteries from 13 patients. The hot-tip temperature to be attained and the upper limit temperature at which lasing was to be stopped were preset. A catheter with a 1.8-mm hot-tip probe was introduced into the obstructed segment and angioplasty (lasing time 5-10 sec) was performed under angioscopic guidance. Recanalization was observed in all segments without obvious complications. No thermal effects below 50 degrees C, coagulation at 100 degrees C, carbonization at 200 degrees C, or sticking of the hot-tip to the luminal surface at 300 degrees C or over, were observed by angioscopy. Rapid recanalization was obtained between 200 degrees C and 300 degrees C. The results indicate that this novel laser system is feasible and hot-tip temperature between 200 degrees C and 300 degrees C is ideal for treatment of chronic arterial obstruction in Japanese patients.
Aged↗
Laser recanalization of thrombosed arteries using thermal and/or modified optical probes; angiographic and angioscopic study.
The degree of residual stenosis by fresh thrombus after laser recanalization was compared by use of angiography and angioscopy. Fifteen NZW rabbits were used. Occlusive fresh thrombus in rabbit aorta was produced by mechanical deendothelialization and external constrictions simulating clinical situations. Argon laser angioplasty using microlens-tipped optical fiber and/or 2 mm hot-tip probe was done to recanalize thrombosed aorta in 10 animals. Two-mm hybrid probe was used in 5. Percent area stenosis (% AST) was derived by use of the mean radius method obtained by angiography of stenotic segments in two orthogonal views and/or from angioscopy. All 15 totally occluded vessels with fresh thrombus were recanalized. Four minor perforations occurred. Following argon laser angioplasty with the microlens optical fiber, percent stenosis was reduced to 53% in diameter by angiography and 66 in % AST by angioscopy, and to 48% and 55 respectively following hot-tip probe. After laser angioplasty with the hybrid probe, residual stenosis by fresh thrombus was 37% in diameter on angiography and 63 in % AST on angioscopy. Mean percent AST was 62% with angiography and 52% with angioscopy, and there was no correlation between them (r = -0.028). Angioscopy provided cross-sectional topographic views of thrombosed lumen and showed charring and shrinkage of thrombus following laser angioplasty. This study suggests that (1) continuous-wave laser angioplasty using modified optical fibers can recanalize thrombotic vascular occlusion, (2) laser angioplasty by hot-tip probe could evacuate fresh thrombus more than microlens fiber on angioscopy, and (3) angiographic % AST did not correlate with angioscopic % AST.
Angiography↗
[The vasospasmolytic effects of nicorandil, cromakalim and pinacidil on 3,4-diaminopyridine-induced phasic contractions in canine coronary arteries as an experimental vasospasm model].
The spasmolytic mechanisms of nicorandil, a novel antianginal drug, were investigated using 3,4-diaminopyridine (3,4-DAP)-induced phasic contractions of isolated canine coronary arteries in comparison with those of cromakalim and pinacidil. Nicorandil (10(-4) M), cromakalim (10(-6) M) and pinacidil (10(-5) M) suppressed the phasic contractions. Pretreatment with glibenclamide (10(-6) M), a specific blocking agent of ATP-sensitive K+ channel, eliminated the suppression of phasic contractions by these drugs; glibenclamide completely eliminated the suppression by cromakalim, while the eliminations against nicorandil and pinacidil were incomplete. The recoveries of peak tensions were only 56.8% and 76.1% for nicorandil and pinacidil, respectively. Nicorandil and pinacidil may suppress the phasic contractions via K+ channel opening and additional mechanisms. Methylene blue (10(-7)-10(-5) M) alone, a guanylate cyclase inhibitor, had no effect on the suppression of phasic contractions by nicorandil. In the presence of glibenclamide (10(-6) M), however, the pretreatment with methylene blue significantly augmented the recovery of peak tension for nicorandil. These results indicate that K+ channel openers may suppress the phasic contractions induced by 3,4-DAP via ATP-sensitive K+ channels, and that additionally, nicorandil may suppress the phasic contractility through guanylate cyclase stimulation, as a nitrate.
4-Aminopyridine↗
[Herpes zoster of the right cervical region associated with right facial nerve palsy and hoarseness].
A 69-year-old man was suffering from herpes zoster on his 2nd and 3rd right cervical spinal segments and 3rd branch of the trigeminal nerve. He came to our hospital on his 10th illness day and was treated with continuous cervical epidural block, intravenous infusion of acyclovir for five days, and oral paramethasone and Vitamin B12. Oh his 18th illness day, right facial nerve palsy and hoarseness became clear. His cerebrospinal fluid showed no abnormality except cell count 23 x 3 mm-2. No clear paralysis of vocal cords was detected on laryngoscopy. He was also treated with right stellate ganglion block starting on his 21st illness day. His pain and facial nerve palsy recovered completely by his 68th illness day, but hoarseness continued about two months. The hoarseness might be a result of spread of the disease 1) by cerebrospinal fluid, 2) by contact with the 3rd cervical nerve and vagal nerve via accessory nerve, and 3) direct effect on the vocal cords and the muscles controlling them. Herpes zoster on the head and neck region shows various complications and we should follow its course cautiously.
Aged↗
[Hemodynamic effects of infusions of alpha-human atrial natriuretic peptide in anesthetized dogs].
The purpose of this study is to investigate and compare the hemodynamic effects of infusion of alpha-human atrial natriuretic peptide (alpha-hANP) at three different doses. Mongrel dogs were anesthetized with 0.87% halothane in oxygen. alpha-hANP was infused for one hour with a constant rate at either 0.3, 1.0, or 10.0 micrograms.kg-1.min-1, respectively. They were randomly divided into four groups. Group A-1 received 0.3 micrograms.kg-1.min-1 of alpha-hANP; Group A-2 received 1.0 micrograms.kg-1.min-1 of alpha-hANP; Group A-3 received 10.0 micrograms.kg-1.min-1 of alpha-hANP; and Group C received normal saline as the vehicle and served as the control. Control values were obtained before infusion of alpha-hANP or vehicle was started, and hemodynamic variables were measured at 30 minutes intervals for two hours. Mean arterial pressure (MAP) of the group C showed no significant changes from control value. During and after infusion of alpha-hANP, MAP in the group A-2 and A-3 was significantly lower than the control values. The decrease in MAP of the group A-2 was the greatest. Heart rate decreased significantly at 60 minutes after termination of the infusion in all four groups. The reduction of cardiac index (CI) in the group-3 was the greatest. In the group A-3, it decreased for 31% from the control value at 60 minutes during infusion. However, this change was not significant. In contrast, the reduction in CI of the group A-2 was minimal. Mean pulmonary artery pressure (MPAP) of the group C showed no significant change from the control value. The patterns of changes in MPAP were similar to those of the alpha-hANP infused groups. It decreased progressively during the infusion. Systemic vascular resistance (SVR) was essentially unchanged in the group C. In the group A-2, SVR decreased slightly during the infusion period and then tended to increase after the infusion of alpha-hANP. In contrast, in the group A-1 and A-3, SVR increased progressively. The changes in left ventricular maximum dp/dt (LV dp/dt max) of the group C were minimal. The reduction in LV dp/dt max was more pronounced in group A-2 than in group A-3. In conclusion, our data show that hypotensive effects of alpha-hANP are associated with the reduction in cardiac output due to the decrease of cardiac contractility. However, the changes of hemodynamic variable are not dose-dependent.
Animals↗
[Hemodynamic effects of induced hypotension by ketanserin in anesthetized dogs].
Hemodynamic effects of hypotension induced by ketanserin were investigated in 18 mongrel dogs under 0.87% halothane in oxygen (1 MAC). They were randomly allocated to one of two groups. Group C (n = 9) received no vasodilator therapy and served as a control and group K (n = 9) received 0.1% ketanserin solution. Mean arterial pressure decreased and was maintained at 60 mmHg for 60 minutes in group K. No change was noted in hemodynamic variables measured in group C throughout the experiment. During and after induced hypotension in group K, stroke volume index increased significantly compared with the control value. On the other hand, systemic vascular resistance was significantly reduced, reaching 50% of the control value at the end of the hypotensive period. Left ventricular maximum dp/dt showed a significant reduction during hypotension but then increased gradually to the control value. In addition, heart rate decreased significantly during and after induced hypotension, therefore these vasodilator effects were not accompanied by reflex tachycardia. Cardiac index remained unchanged throughout the experiment. Further, no changes in central venous pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure and pulmonary vascular resistance were observed. In conclusion, the data indicate that ketanserin is a potent systemic vasodilator producing stable hemodynamics. It also reduces systemic vascular resistance without reflex tachycardia and this is a favorable effect of ketanserin.
Animals↗
[Endocrine effects of induced hypotension by ketanserin in anesthetized dogs].
Plasma levels of catecholamines, aldosterone and cortisol as well as plasma renin activity during hypotension by ketanserin were studied in 9 mongrel dogs under 0.87% halothane in oxygen (1MAC). Mean arterial pressure was reduced and maintained at 60 mmHg for 60 minutes by the infusion of 0.1% ketanserin solution. Plasma norepinephrine decreased progressively during hypotension to 35% of the control value after induced hypotension. In contrast, plasma epinephrine increased three-four folds compared with the control value during and after induced hypotension, but this change was not statistically significant. Plasma renin activity and plasma aldosterone showed a slight increase during hypotension but returned toward the control value after discontinuing the infusion of ketanserin. Plasma cortisol remained unchanged throughout the experiment. In conclusion, our data show that hypotension by ketanserin is not accompanied by the activation of the renin-angiotensin-sympathetic system or adrenocortical system.
Animals↗
Enhancement of harmonics for optically detected light- and heavy-hole cyclotron resonance in germanium.
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Journal Article↗
Enhancement of pulsed-dye laser ablation of arterial tissues with blood medium: effects of laser-induced shock waves.
The influence of blood medium on tissue ablation by a pulsed dye laser and its selectivity for atheroma were investigated. The role of shock waves on tissue ablation was also evaluated. Normal and atherosclerotic human aortas were irradiated by a 480 nm pulsed dye laser activated at 5 Hz. The laser was coupled with a single 0.2 mm fiber (Uni-guide) (40 mjoules/pulse) or a multifiber catheter (14 x 150 microns) (100 mjoules/pulse). Shock waves were measured using a fluid-filled catheter connected to a strain gauge manometer. With the Uni-guide, pulse-dye lasing resulted in greater ablation of atheroma in blood (11.6 x 10(-3) mm3/joule, p less than 0.001 versus atheroma measured in saline and normal tissue in blood) followed by normal tissue in blood (2.5 x 10(-3)mm3/joule), atheroma in saline (1.71 x 10(-3)mm3/joule, p less than 0.05 versus normal tissue in saline), and normal tissue in saline (0.54 x 10(-3) mm3/joule). With the multifiber catheter, laser ablation was the greatest in atheroma in blood (0.55 +/- 0.26 mm3/joule p less than 0.001 versus atheroma in saline and normal tissue in blood), followed by normal tissue in blood (0.27 +/- 0.12 mm3/joule), atheroma in saline (0.14 +/- 0.15 mm3/joule, p less than 0.001 versus normal tissue in saline), and normal tissue in saline (0 mm3/joule). The ablation efficiency of the multifiber catheter was greater than that of the Uni-guide (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
Angioplasty, Laser↗
The role of shock waves in pulsed-dye laser angioplasty.
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Angioplasty, Laser↗
Holmium YAG laser coronary angioplasty with multifiber catheters.
Excimer lasers are being extensively used for coronary angioplasty along with multifiber over-the-wire catheters. To determine whether another wavelength could be an alternative, the laser-tissue interaction and the clinical usefulness of an infrared laser were studied. The laser consisted of a Holmium YAG pulsed laser coupled into a multifiber catheter. Experimental data from our laboratory showed that this solid state laser had the ability to cut calcified tissue, to be preferentially absorbed by atheroma, and to ablate tissue even when the catheter tip was positioned at a distance from the target. These results were obtained with only minimal thermal effects. After assessment of the efficacy and safety of this technique, laser angioplasty was performed in 53 consecutive patients with totally occluded (40%) or stenosed (mean percent 94) coronary arteries with a mean length of 6 mm. The primary laser and the procedure success rate were 64% and 94%, respectively. Failures were due to inability to advance the catheter against the lesion or to cross the obstruction. Stand-alone laser therapy could be achieved in only 18% of patients. In previous dilatation failures, laser irradiation allowed for subsequent balloon angioplasty to be successfully performed at a lower inflation pressure than that used in the failed dilatation. Complications included abrupt (during the procedure) and early (within 24 hours) vessel closure in 19% of cases, dissection without hemodynamic consequence in 28% and spasm. Reoccluded arteries could all be recanalized with dilatation.(ABSTRACT TRUNCATED AT 250 WORDS)
Angioplasty, Laser↗
Results and follow-up after percutaneous pulsed laser-assisted balloon angioplasty guided by spectroscopy.
BACKGROUND: Few data are available on the long-term outcome of patients who undergo laser-assisted balloon angioplasty for recanalization of occluded peripheral arteries. Because the cost of laser angioplasty is high, the value of the method should be carefully analyzed before it can be considered a routine method for recanalization. The purpose of this study was to evaluate the early and late results of laser-assisted balloon angioplasty in patients who could not be recanalized by conventional techniques. METHODS AND RESULTS: Laser angioplasty was performed in 66 patients with total occlusion of the iliofemoral artery in whom mechanical techniques failed to recanalize the obstructed vessel. The system consisted of a pulsed dye laser operated at 480 nm, 2 microseconds/pulse, 5 Hz, 50 mJ/pulse coupled into a 0.021-in. laser catheter. The treatment laser was connected with a diagnostic laser to induce tissue fluorescence for spectroscopic analysis via the same fiber. The treatment laser was emitted only when atheromatous tissue was recognized. After a pilot hole was created by laser emission, dilatation was performed to enlarge the channel. The mean length of occlusion was 8.8 +/- 6.1 cm. The primary success rate was 82%. It did not depend on the length of occlusion but was greater in non-calcified than in calcified lesions (88% versus 71%, p less than 0.03). Complications included seven early reocclusions that could be recanalized and eight perforations without clinical sequelae. At a mean 18-month follow-up, 64% of the laser-treated arteries remained patent. The rate of patency was related neither to the length of the occlusion nor to calcifications but was lower in patients who had early reocclusion (p less than 0.02). CONCLUSIONS: Pulsed dye laser-assisted balloon angioplasty is effective for recanalization of totally occluded arteries that cannot be treated by conventional means. The efficacy is limited by calcifications. The long-term patency rate is acceptable given the severity of the lesions.
Angioplasty, Laser↗
Percutaneous fiberoptic cardioscopy of the left ventricle.
The feasibility of percutaneous transluminal cardioscopy of the left ventricle was examined in 35 patients with or without various heart diseases. A guiding balloon catheter (7 or 9 French) was introduced through the right femoral artery into the left ventricle. The balloon was inflated, and a fiberscope (1.6 or 4.3 French) was advanced to the distal tip of the catheter. The balloon was then manipulated against the portion of the ventricle targeted for examination, and heparinized saline (10 U/ml) at body temperature was infused through the catheter at 5 ml/sec for 3 to 6 sec. The images were recorded on videotape and 16 mm cinefilm. In 4 patients without demonstrable heart disease, the endocardial surface of the left ventricle was brown and the trabeculae became prominent during systole. The chordae connected to the mitral leaflets were white. In 3 of 5 patients with dilated cardiomyopathy, the endocardium was light yellow with thin trabeculae which barely contracted during systole. The endocardium was red or reddish-brown in 3 patients with acute myocarditis. In patients with rheumatic mitral stenosis white patches were scattered on the endocardial surface. In 7 of 8 patients the akinetic or dyskinetic segments representing prior infarctions were white. No complications other than transient ventricular arrhythmias were noted. We conclude that percutaneous fiberscopic imaging with a guiding balloon catheter is feasible and safe, and yields highly detailed images of the endocardium.
Acute Disease↗
[Endocrine effects of hypotension induced by diltiazem in rabbits].
Endocrine effects of hypotension induced by diltiazem, a calcium antagonist, were studied in 16 male rabbits under the inhalation of 0.7% halothane in oxygen. They were randomly allocated to one of two groups. Group C (n = 8) received no vasodilator therapy and served as control and group D (n = 8) received infusion of diltiazem. Mean arterial pressure was decreased and was maintained at 60 mmHg for 60 minutes in group D. No change was noted in plasma catecholamines measured in group C throughout the experiment but plasma renin activity decreased progressively. During and after induced hypotension in group D plasma epinephrine showed a dramatic rise compared with the control value. The maximum increase occurred 30 minutes after induction of hypotension but this change was not statistically significant. Plasma norepinephrine in group D was significantly higher than the control value. Compared with the control value (0.19 +/- 0.04 ng.ml-1), plasma norepinephrine was activated 30 and 60 minutes after induction of hypotension (0.71 +/- 0.16 ng.ml-1, P less than 0.05, 0.82 +/- 0.20 ng.ml-1, P less than 0.05, respectively). Plasma renin activity in group D was significantly higher than the control value. The highest level of plasma renin activity was three times the control value 30 minutes after induction of hypotension. In conclusion, our data show that induced hypotension by diltiazem activates the renin-angiotensin-sympathetic nervous system.
Animals↗