Investigation of SO3 absorption line for in situ gas detection inside combustion plants using a 4-µm-band laser source.

We have investigated 4-µm-band SO3 absorption lines for in situSO3 detection using a mid-infrared laser source based on difference frequency generation in a quasi-phase-matched LiNbO3 waveguide. In the wavelength range of 4.09400-4.10600 µm, there were strong SO3 absorption lines. The maximum absorption coefficient at a concentration of 170 ppmv was estimated to be about 3.2×10-5 cm-1 at a gas temperature of 190°C. In coexistence with H2O, the reduction of the SO3 absorption peak height was observed, which was caused by sulfuric acid formation. We discuss a method of using an SO3 equilibrium curve to derive the total SO3 molecule concentration.

Noninvasive detection of total occlusion of the left anterior descending coronary artery with transthoracic Doppler echocardiography.

OBJECTIVES: The purpose of this study was to evaluate the value of transthoracic Doppler echocardiography (TTDE) for the noninvasive detection of total left anterior descending coronary artery (LAD) occlusion. BACKGROUND: Total coronary occlusion is associated with an adverse long-term prognosis, and mechanical revascularization may be required for the patient with total coronary occlusion. However, a noninvasive diagnosis of total coronary occlusion before coronary angiography (CAG) has been difficult, especially in patients without clinical signs. METHODS: We studied 103 consecutive patients who underwent CAG for the evaluation of coronary artery disease. The study group consisted of 16 patients with total LAD occlusion (group A) and 87 patients without total LAD occlusion (group B). Coronary flow velocity in the mid-portion of the LAD was recorded by TTDE. RESULTS: Adequate spectral Doppler recordings of diastolic flow in the LAD were obtained in 98 study patients (95%; 15 patients in group A and 83 patients in group B). In group A, retrograde LAD flow was obtained in 14 (93%) of 15 patients. The mean diastolic velocity of the retrograde flow was 21.0 +/- 6.1 cm/s. In group B, antegrade LAD flow was obtained in all 83 patients (100%). The mean diastolic velocity of the antegrade flow was 21.5 +/- 7.1 cm/s. Retrograde LAD flow by TTDE had a sensitivity of 93% and a specificity of 100% for the detection of total LAD occlusion. CONCLUSIONS: Retrograde flow in the LAD by TTDE is a highly sensitive and specific finding that can be used to noninvasively diagnose total LAD occlusion.

Real-time blood-pool images of contrast enhanced ultrasound with Definity in the detection of tumour nodules in the liver.

Lower mechanical index (MI) technique with newer microbubble agents has been introduced into clinical practice as a newer ultrasound (US) imaging. However, the efficacy in detecting tumour nodules has not been proven scientifically. The aim of this study was to elucidate the efficacy of a blood-pool image of real-time contrast-enhanced US under low MI in detecting liver tumours. 15 rabbits with VX-2 tumour were used; the number of implantations was none in two rabbits, one in four, two in five and three in four. US equipment was APLIO (Toshiba) with linear probe (3.5/7.0 MHz). The number, location and size of tumour nodules were examined by non-contrast tissue harmonic imaging (NC-US) or contrast-enhanced pulse subtraction harmonic imaging (C-US) under extra-low MI (MI 0.065) with the injection of Definity (30 microl kg(-1)). The number of tumour nodules detected by both NC-US and C-US were consistent with the histopathological results in five rabbits - two with none, two with one nodule and one with two nodules. In the other 10 rabbits, C-US showed all the implanted tumours and small daughter nodules around them that were confirmed by histopathology. However, NC-US failed to demonstrate two implanted nodules and all the daughter nodules. On the basis of the histopathological results, detectability of implanted tumour was not significantly different between NC-US (24/26, 92.3%) and C-US (26/26, 100%). However C-US was superior to NC-US in delineating the nodules and in detecting small daughter nodules. The sizes of the implanted tumour nodules measured by histopathology correlated closely with those measured by C-US. Real-time blood-pool images by pulse subtraction harmonic imaging under extra-low MI with Definity will contribute to the improvement of the ultrasound delineation and detection of liver tumours.

Gray-scale second harmonic imaging of the liver with galactose-based microbubbles.

RATIONALE AND OBJECTIVES: The authors evaluate the efficacy of SHU 508A, a galactose-based contrast agent used in gray-scale second harmonic imaging in vitro and in vivo experiments. METHODS: A Toshiba prototype harmonic imaging system (2.5/5.0 MHz) was used with SHU 508A in a phantom experiment and to image the liver in five healthy rabbits and one rabbit that had VX-2 tumors in the liver. RESULTS: In the second harmonic imaging, most of the fundamental components of the backscattered echo were eliminated, and good images with high contrast were obtained in the phantom experiment. Liver parenchyma was enhanced clearly in all rabbits at 0.3 mL/kg, an effect that lasted for 90 seconds. The tumor, which was mostly necrotic, was depicted clearly as a negative enhanced area surrounded by enhanced healthy liver. CONCLUSIONS: Gray-scale second harmonic imaging is a promising new method for visualization of perfusion of organs.

Potential advantage of flash echocardiography for digital subtraction of B-mode images acquired during myocardial contrast echocardiography.

Optimal assessment of myocardial perfusion with contrast echocardiography by using B-mode imaging often requires image alignment and background subtraction, which are time consuming and need extensive expertise. Flash echocardiography is a new technique in which primary images are gated to the electrocardiogram and secondary images are obtained by transmitting ultrasound pulses in rapid succession after each primary image. Myocardial opacification is seen in the primary image and not in the secondary images because of ultrasound-induced bubble destruction. Because the interval between the primary and first few secondary images is very short, cardiac motion between these images should be minimal. Therefore we hypothesized that 1 or more secondary images could be subtracted from the primary image without the need for image alignment. The ability of ultrasound to destroy microbubbles was assessed by varying the sampling rate, line density, and mechanical index in 6 open-chest dogs. The degree of translation between images was quantified in the x and y directions with the use of computer cross-correlation. At sampling rates of 158 Hz or less and a mechanical index of more than 0.6, videointensity rapidly declined to baseline levels by 25 ms. Significant translation between images was noted only at intervals of more than 112 ms. It is concluded that flash echocardiography can be used for digital subtraction of baseline from contrast-enhanced B-mode images without image alignment. Background subtraction is therefore feasible on-line, potentially eliminating the need for off-line image processing in the future.

Analysis of flash echo from contrast agent for designing optimal ultrasound diagnostic systems.

Microbubble-based contrast agents can enhance echoes in areas of low blood flow, but the bubbles are extremely sensitive and collapse easily when exposed to ultrasound (US) irradiation. An experimental study of bubble collapse was carried out to design new functions for US diagnostic systems to detect echoes from microbubbles more efficiently. For contrast agent (Levovist) solution, a high-intensity, but momentary, echo (flash echo), was observed in the first frame image after a several-second suspension of transmission, but was not seen in the second frame image. These "flash echo" signals were analyzed and categorized based on microscopic observation, and the results showed that the longevity of the microbubbles was reduced by conditions such as B-mode imaging. Next, a numerical simulation of the bubbles in liquid was performed under the same conditions as in the in vitro experiment. The results showed that even bubbles less than 1 microm in diameter expand and collapse within one pulse drive, which would generate flash echoes. The flash echo imaging system described here permits flexible intermittent scanning with variable intervals, with a variable number of frames at the trigger, and with simultaneous monitoring at low power output. Animal experiments were also conducted to evaluate the system. As the interval between frames was increased, the flash echoes gradually increased, and perfusion in the parenchyma was clearly observed with an interval of 4 s.

Grey-scale contrast enhancement in rabbit liver with DMP115 at different acoustic power levels.

The contrast enhancement effect of ultrasound (US) contrast agent DMP-115 (YM454, Definity) in rabbit liver at two acoustic transmit power levels was studied. A total of 12 rabbits with healthy livers and 7 rabbits with VX-2 tumors were used. Grey-scale ultrasonograms in both fundamental (3.75 MHz) and harmonic (2.5/5.0 MHz) imaging modes were performed at a frame rate of 26 Hz under baseline acoustic power (MI = 0.6) or lower acoustic power (MI = 0.2). The contrast enhancement depended on the contrast agent dose and the acoustic power. The video intensity change was higher in the portal vein under the baseline acoustic power and higher in the liver parenchyma under the lower acoustic power. The contrast-enhanced US observation of the VX-2 tumor in the arterial phase correlated well with the angiographic and histopathological appearance of the tumor. In the parenchymal phase, the borderline of the tumor could be clearly delineated from the surrounding liver parenchyma. Continuous fundamental and harmonic grey-scale imaging with DMP115 has the capability of making peripheral circulation images of liver parenchyma and tumors.

In vivo kinetics of microbubbles of SH U 508 A (Levovist): comparison with indocyanine green in rabbits.

The aim of this study was to evaluate in vivo kinetics of microbubbles of SH U 508 A, in comparison with Indocyanine Green, a dye used as an indicator of blood flow. Microbubble kinetics were evaluated in various vessels (i.e., vena cava, aorta, renal artery, renal vein and portal vein) in rabbits after injection of SH U 508 A by measuring Doppler signals (n = 5). The kinetics of Indocyanine Green were evaluated by measuring absorbance using a photodiode (n = 5). Test substances (SH U 508 A 300 mg/mL and Indocyanine Green 1.25 mg/mL) were injected IV at a dose of 0.1 mL/kg B.W. Peak signal intensity was observed immediately after injection of SH U 508 A, followed by biphasic decay. The rates of biphasic decay were similar in all vessels. A second peak of the signal, which indicated recirculation of the microbubbles, was observed in the vena cava. The circulation and recirculation times of the microbubbles after injection of SH U 508 A were similar to that of Indocyanine Green. These findings suggest that the majority of SH U 508 A microbubbles circulate through the body similarly to blood flow, without retention, in the vasculature.

Liposteroid (dexamethasone palmitate) therapy for West syndrome: a comparative study with ACTH therapy.

Dexamethasone palmitate (liposteroid) was used for the treatment of West syndrome and compared with adrenocorticotropic hormone (ACTH) therapy. A single intravenous injection of liposteroid (0.25 mg/kg) was administered seven times in 3 months (total dosage = 1.75 mg/kg) to five symptomatic patients with West syndrome, aged 4-11 months. ACTH (0.025 mg/kg/day) was administered intramuscularly for 6 weeks according to the conventional therapy in Japan (total dosage = 0.625 mg/kg) to five symptomatic patients with West syndrome, aged 6-10 months. Nodding spasm and hypsarrhythmia on EEG disappeared in all patients in the liposteroid therapy group within four doses; however, partial seizures and focal spikes on EEG reappeared in three patients 2 months after the end of liposteroid therapy. In the ACTH therapy group, nodding spasm and hypsarrhythmia on EEG similarly disappeared during treatment in all patients, but nodding spasm reappeared 2 months after therapy in two patients and partial seizures reappeared in one patient 3 months after therapy. No notable adverse reactions occurred in the liposteroid group, but transient dysfunction of the thyroid and anterior pituitary gland and increased levels of serum cortisol were experienced in the ACTH group. These results suggest that glucocorticoid incorporated in a lipid emulsion is useful for the treatment of West syndrome.

[Hypoplastic leukemia successfully treated with low-dose aclarubicin: a case report].

Low-dose aclarubicin (LDACR) therapy is one of the differentiation induction therapy, such as low-dose cytosine arabinoside therapy, 1 alpha, 25 dihydroxy-vitamin D3 or retinoic acid therapy, for myelodysplastic syndrome and atypical leukemias. A 36-year-old female with hypoplastic acute myelogenous leukemia was treated with this atypical leukemias. A 36-year-old female with hypoplastic acute myelogenous leukemia was treated with this LDACR therapy. On admission, she was suffered from general fatigue and her peripheral blood smear showed pancytopenia with 23% of myeloblasts. Bone marrow examination revealed a moderately hypoplastic marrow with 35.4% of myeloblasts. She was diagnosed as having hypoplastic acute myelogenous leukemia. Thereafter, 20 mg of aclarubicin was given daily by one-shot intravenous injection for 10 days. After this LDACR therapy, myeloblasts disappeared from her peripheral blood and pancytopenia improved. Bone marrow examination showed increase in nuclear cell counts and she achieved complete remission. In this article, we report the clinical course of this patient and discuss the effect of LDACR therapy as useful chemotherapy for this patient.

[Thrombus entrapped in a patent foramen ovale of the atrial septum].

A 59-year-old women was referred to our hospital due to severe dyspnea and shock status 12 days after intracranial hematoma evacuation for the hypertensive right putaminal hemorrhage. Transthoracic echocardiography revealed right ventricular dilatation and floating structures in the right atrium. Transesophageal echocardiography demonstrated a large, snake-like structure crossing her foramen ovale of the interatrial septum, and impending paradoxical embolism was diagnosed. She did not receive any anticoagulation and surgery due to recent cerebral hemorrhage. Follow-up TEE showed complete disappearance of the thrombus in the atrium two weeks after the onset. Phlebogram of deep vein demonstrated several thrombus in her leg. She underwent placement of inferior vena cava filter and was discharged from our hospital without any symptom of paradoxical embolism.

[Flash echo imaging].

Ultrasound transmission sometimes limits the lifetime of microbubble-based contrast agents. At this time, a very large echo signal (like a flash) is obtained for the initial transmission of the ultrasound after several seconds' suspension. Flash Echo Imaging (FEI) is a new technique which uses the signals of the bubble's collapse. This paper explains a principle of FEI and functions of the FEI's application for ultrasound diagnostic system. It is also shown that perfusion of the tissue can be visualized by using FEI methods.

Expression of cell adhesion molecules and the appearance of adherent leukocytes on the left atrial endothelium with atrial fibrillation: rabbit experimental model.

To assess the expression of cell adhesion molecules and the appearance of leukocytes adhering to the left atrial endothelium with atrial fibrillation (AF), 10 Japanese white rabbits were anesthetized and 3 pacing leads were placed in the right atrium. For the AF model, the right atrium was stimulated by electrical pacing (the stimulation frequency of each lead being adjusted to different intervals) for 8h while the control model was subjected to a sham operation without atrial stimulation. The left atrial appendage was excised from the heart and examined immunohistochemically. P-selectin staining of the endothelium in both models was linear and regional, and intracellular adhesion molecule-1 (ICAM-1) in the AF model was confined to leukocytes and endothelial cells with adherent leukocytes. The expression of P-selectin (p<0.05) and the appearance of positively ICAM-1 stained adherent leukocytes (p<0.05) were significantly greater in the AF model than in the control model. In conclusion, AF could regulate the expression of at least 2 critical adhesion molecules, P-selectin and ICAM-1, and the appearance of adherent leukocytes; suggesting that these molecules may play an important role in left atrial thrombus formation with AF. Although anticoagulant therapy has generally been carried out with warfarin in AF patients, neutralizing antibodies to cell adhesion molecules should be tried to prevent thromboembolic complications.

Pulse dispersion due to atrial fibrillation causes arterial thrombosis in a rabbit experimental model.

Thrombosis associated with atrial fibrillation (AF) is usually caused by a left atrial (LA) thrombus, but it is not always detected. The present study was based on the hypothesis that abnormalities in peripheral artery are responsible for the ischemic stroke associated with AF. Peripheral arterial coagulability was investigated in a rabbit experimental model in which AF was induced by high-frequency stimulation of the right atrium, creating stenosis of the carotid artery together with endothelial damage. The rabbits were classified into 4 groups: (i) sinus rhythm only (group 1), (ii) sinus rhythm after 6 h of pacing (group 2), (iii) short AF (continuous pacing for 5 min; group 3) and (iv) long AF (continuous pacing for 6 h: group 4). The carotid blood flow developed a typical pattern, called cyclic flow reductions (CFRs), the frequency of which (CFRF) was 18.59+/-2.85 in AF (group 3+4) compared with 14.46+/-2.1 in sinus rhythm (group 1+2) (p<0.0005). Among the groups with AF, correlation analysis showed an association between CFRF and pulse dispersion (p<0.02, r=0.58). This study suggests that the distinctive hemodynamic effects with AF, in particular pulse dispersion, substantively influence thrombus formation on injured vascular endothelium.

A new method, distribution-analyzing latex immunoassay (DALIA), to measure specific immunoglobulin G against mite and wheat allergen in human sera.

A distribution-analyzing latex immunoassay (DALIA), based on the agglutination of latex particles coupled with mite or wheat allergen, was developed to determine allergen-specific IgG in human sera. The immune complex between chemically coupled-allergen latex and specific IgG was agglutinated specifically and efficiently by employing an IgM-type monoclonal second antibody with strong amplification activity. The extent of agglutination was evaluated by determining the relative ratio of volumes (RV) of agglutinates to residual nonagglutinating particles with a particle counter. This method exhibited a high sensitivity (detection limit < or = 5 units/ml) in the determination of allergen-specific IgG, and no influence of inhibitory factors such as competitive antibodies (specific-IgA, -IgM) and nonspecific IgG (< or = 320 mg/ml) was observed. The concentrations of specific IgG against mite allergen in the sera of 130 allergy patients with atopic dermatitis and 52 normal subjects were 22.3 +/- 12.3 and 16.5 +/- 4.2 units/ml, respectively, and the concentrations of specific IgG against wheat allergen in the same two groups were 5.4 +/- 4.2 and 2.1 +/- 2.2 units/ml, respectively. The coefficients of variation of intra- and interassay ranged from 3.4% to 11.2% in both cases. The present method is an excellent homogeneous immunoassay which may be used as a routine assay that can measure 50 samples per hour without prior treatment.

Electrocardiographic features differentiating dilated cardiomyopathy from hypertrophic cardiomyopathy.

To determine the usefulness of electrocardiographic (ECG) features in differentiating between hypertrophic cardiomyopathy with features mimicking dilated cardiomyopathy (D-HCM) and true dilated cardiomyopathy (DCM), we compared ECGs of 52 consecutive patients (11 with D-HCM, 41 with DCM). Left atrial dimension, left ventricular internal dimension, and septal and posterior wall thickness were employed as echocardiographic indexes, while QRS duration, amplitude of RV5 or V6 + SV1, number of abnormal Q waves, P-terminal force in V1, and frontal plane QRS axis were used as ECG parameters. The patients with D-HCM demonstrated a larger number of abnormal Q waves (P < .0001), greater prolongation of QRS duration (P < .0001), and lower amplitude of RV5 or V6 + SV1 (P < .0001). In all cases of D-HCM, atrial overload was observed and abnormal QRS axis in 9 (82%) of the 11 patients. These features were noted in 21 (51%) and 17 (41%), respectively, of the 41 DCM patients (P < .005 and P < .05, respectively). Despite significant differences in the echocardiographic parameters between D-HCM and DCM, excluding left ventricular end-diastolic dimension, ECG abnormalities were more significant between the two groups. The results indicate that ECG features are extremely useful in differentiation between DCM and D-HCM.