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Biomedical subjects

J Suzuki

Publications and source records attributed to J Suzuki.

At least 451 records · Page 25Linked to original sources
PubMed1991

Evaluation of valvular heart disease with cine gradient echo magnetic resonance imaging.

Electrocardiographic referenced repetitive gradient echo magnetic resonance imaging (cine GRE) has been used to detect and quantify valvular regurgitation. Regurgitation is recognized as a signal void in the high intensity blood pool on these images. Mitral regurgitation causes a signal void in the left atrium in systole, and aortic regurgitation produces one in the left ventricle in diastole. The specificity, sensitivity, and diagnostic accuracy of cine GRE for the detection of mitral and aortic regurgitation was greater than 0.93, 0.89, and 0.92, respectively. The severity of regurgitation has been quantified as the difference in the stroke volume between the two ventricles by measuring the volume of the blood pool, as shown in the stack of magnetic resonance tomograms. Severity has also been assessed by measuring the volume of the signal void. Finally, measurements of the volume of aortic regurgitation have recently been achieved by using velocity-encoded cine GRE. This technique provides a direct measurement of retrograde flow in the aorta during diastole. New cine GRE imaging techniques provide a noninvasive means for quantification of valvular as well as ventricular function.

Aortic Valve↗
PubMed1991

[Usefulness of transesophageal echocardiography in thoracic aortic disease: comparison with computed tomography and angiography].

To evaluate the usefulness of transesophageal echocardiography in thoracic aortic disease, transesophageal echocardiography was performed in 11 patients with thoracic aortic disease (true aortic aneurysm in two patients, aortic dissection in nine patients). Findings obtained by transesophageal echocardiography were compared with those obtained by computed tomography (nine patients) and angiography (six patients). Results were as follows: 1. True aortic aneurysm: Although transesophageal echocardiography and computed tomography could evaluate the size of the aorta and detect mural thrombus, angiography underestimated degree of aortic dilatation because of the presence of mural thrombus. 2. Aortic dissection: Although computed tomography could not differentiate thrombus in the false lumen from mural thrombus in two patients, transesophageal echocardiography could discriminate those two easily in one patient from properties and motion of the intimal flap, and flow information in the false lumen. Angiography could not evaluate the range of dissection in any patients with thrombus in the false lumen. With transesophageal echocardiography we could detect the entry in all six patients with aortic dissection of DeBakey type III except 1 patient with aortic dissection of DeBakey type I. Transesophageal echocardiography could obtain real-time image of most of the aorta except for a part of the ascending aorta. Therefore, transesophageal echocardiography was useful for diagnosing thoracic aortic disease and distinguishing between true aortic aneurysm and aortic dissection.

Aged↗
PubMed1991

Bilateral congenital atresia. Auditory and vestibular testing and surgical approach.

Bilateral congenital atresia presents various problems of hearing, education, psychology and surgery. The complexity of these problems needs a systematic approach, from the initial evaluation to the rehabilitative recommendation. It is very important for infants and children with bilateral aural atresia to be provided with sufficient hearing either through surgical correction of the ear or by a hearing aid or both because bilateral aural atresia gives moderate hearing loss. This paper describes our preoperative assessment of auditory and vestibular function at very early age and the surgical technique for meatoplasty.

Bone Conduction↗
PubMed1990

Follow-up in mitral valve prolapse by phonocardiography, M-mode and two-dimensional echocardiography and Doppler echocardiography.

To assess the serial phonocardiographic and echocardiographic change in patients with mitral valve prolapse (MVP), phonocardiograms and echocardiograms were reviewed retrospectively in 116 patients (48 men and 68 women, mean age 27 years) who had been determined to have MVP and were reexamined 4.3 years (range 1 to 14) later by phonocardiography and echocardiography between 1971 and 1988. Follow-up phonocardiograms showed periods when 5 of 18 patients with silent MVP developed mid- or late systolic clicks. Of 57 patients with mid- or late systolic clicks, 15 had silent MVP, 6 developed a late systolic murmur with or without systolic clicks and 1 developed a pansystolic murmur. Two of 9 patients with an isolated late systolic murmur developed a pansystolic murmur. M-mode echocardiograms showed that left atrial and left ventricular dimensions at end-diastole and end-systole increased in patients with systolic murmur (33 +/- 10 vs 35 +/- 11, 46 +/- 6 vs 50 +/- 7 and 29 +/- 4 vs 31 +/- 5 mm, respectively, all p less than 0.001) and no statistically significant changes in any of these dimensions were found in patients without a systolic murmur. The degree of MVP evaluated by the anteroposterior mitral leaflet angle on the 2-dimensional echocardiogram was more severe in patients with a systolic murmur than in patients without systolic murmur (157 +/- 12 vs 131 +/- 16 degrees, p less than 0.001). The degree of prolapse did not change during the follow-up periods. The number of patients with mitral regurgitation detected by pulsed Doppler echocardiography increased from 21 of 72 (29%) to 31 of 72 (43%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

A quantitative analysis of the mesangium in children with IgA nephropathy: sequential study.

Quantitative analysis of the mesangial matrix and cells was performed on serial renal biopsies from 41 children with IgA nephropathy. In the repeat renal biopsy, nine patients showed a significant increase of mesangial matrix, 29 showed no change and in three there was a significant decrease. Eight of the nine patients (89 per cent) with a matrix increase had persistent proteinuria at the second biopsy, whereas only 14 of the 32 (44 per cent) without a matrix increase had persistent proteinuria (P less than 0.05). Although the mesangial matrix increased in patients with persistent proteinuria, there was no decrease in patients with clinical remission. In contrast to the mesangial matrix, mesangial cells significantly decreased in 23 patients, did not change in 16, and significantly increased in only two in the second biopsy. These findings suggest that mesangial matrix increase is usually an irreversible change and that persistent proteinuria is associated with matrix increase with worsening in glomerular morphology and clinical outcome. This study indicates the importance of serial renal biopsy in children with IgA nephropathy with persistent proteinuria.

Adolescent↗
PubMed1990

Cerebral blood flow in moyamoya disease. Part 1: Correlation with age and regional distribution.

A study has been made of the cerebral blood flow (CBF) in moyamoya disease from the perspective of hemispheric cerebral blood flow and regional CBF (rCBF). The material includes 21 children between the ages of 5 and 15 years with moyamoya disease, and 19 adult moyamoya cases--all of which had virtually no neurological symptoms at the time of the study. CBF was measured using the 133Xe intravenous injection method. Comparison was made with the measurements from 16 normal children and 14 normal adults. Study was also made of the relationship between the angiographic stage of the disease and the CBF. With the exception of the more elderly patients, CBF was found to be significantly lower in the moyamoya cases than in normal subjects of the same age group. In all age groups, the distribution of rCBF showed a dominant posterior distribution, dissimilar to the dominant anterior distribution found in the normals. Among the juvenile moyamoya cases, there was a tendency toward decreasing hemispheric blood flow together with advancing disease--as determined angiographically. Moreover, with advancing stages of the disease, there was a continuing transition from the normal pattern of frontal dominance to one of occipital dominance. This dominance of posterior rCBF is thought to be a characteristic feature of moyamoya disease.

Adolescent↗
PubMed1990

Cerebral blood flow in moyamoya disease. Part 2: Autoregulation and CO2 response.

In order to clarify the cerebrovascular response in Moyamoya disease, the autoregulation and CO2 response was investigated using the 81mKr continuous cerebral blood flow (CBF) measurement technique. A total of 32 measurements were made over the anterior and posterior circulation in 16 Moyamoya patients (seven adults, nine children). CBF measurements were made during four loading trials (hypertension, hypotension, CO2 inhalation and hyperventilation). Study was then made of the vascular response of the frontal lobe, perfused by the internal carotid artery (ICA), and the occipital lobe and cerebellum, perfused by the vertebral artery (VA). Deficits of autoregulation were more severe among the juvenile cases in response to hypotension than to hypertension in both the ICA and VA regions, but the deficits were mild. The CO2 response to hypercapnea in the juvenile cases tended to be abnormal in both the ICA and VA regions. Both adult and juvenile patients showed deficits in the ICA region in response to hyperventilation, some of whom exhibited paradoxial responses. Notable differences in the severity of the deficits of the vascular response in adult and juvenile cases were seen, with the deficits in the response being more severe among the juvenile cases. Moreover, significant regional differences in the deficits were also found.

Adolescent↗
PubMed1990

Cell proliferation on hydrogels.

The adhesion and proliferation of mammalian fibroblasts (Flow 7000) on the surface of hydrophilic (copolymer of N-vinyl-2-pyrrolidone and methyl methacrylate) and hydrophobic [polymethylmethacrylate (PMMA) stereocomplex] hydrogels with a wide range in water content were studied morphologically and quantitatively. It was demonstrated that cell proliferation on hydrogels by a static culture method decreased as the water content of the gels increased. However, it is remarkable that the cell proliferation on PMMA hydrogels with a high water content is equivalent to that on glass Petri dishes. The results obtained in the proliferation of cells on the surface of these hydrogels closely correspond to the state of cell adhesion. When fresh medium or air was perfused from the opposite side of the PMMA hydrogel membrane on which the cells were proliferating (perfusion method), the cells continued to grow into a higher density than with the conventional static culture method. In the case of fresh medium perfusion, the amount of proliferated cell was dependent on both the permeability of the membrane and the density of the membrane "scaffolding." Virus multiplication in the cultured cells increased in proportion to the cell density, whereas the cell function was similar in both culture methods.

Cell Adhesion↗
PubMed1990

Purification and properties of several phospholipases A2 from the venom of Australian king brown snake (Pseudechis australis).

Thirteen isoenzymes of phospholipases A2 were purified from the venom of Australian king brown snake, Pseudechis australis. They (except phospholipase A2 Pa-9C) showed normal properties of snake venom phospholipases A2; the apparent mol. wts were about 13,000, the optimum pH values were around 8, calcium ion was indispensable for the enzymatic activity and the optimum calcium ion concentrations were more than 5 mM. Phospholipase A2 Pa-9C had a lag period at the initial stage of the enzymatic reaction. The enzymatic activities determined by the titration method using 1,2-dipalmitoylglycerophosphocholine as a substrate at 37 degrees C were 10,500 units/mg for Pa-1G and 75 units/mg for Pa-13. The lethal activities measured by i.v. injections in mice were 0.09 micrograms/g body wt for Pa-5 and 6.8 micrograms/g body wt for Pa-13. The lethal activity correlates with the enzymatic activity (correlation coefficient of 0.92), and both activities showed no relationship to the basicity of the enzyme. Pa-1G is the first acidic phospholipase A2 (pI = 6.4) with high neurotoxicity (0.13 micrograms/g body wt).

Animals↗
PubMed1990

Pathology of excessive iron storage in the Afghan pika (Ochotona rufescens rufescens).

Iron deposition in the tissues of 30 Afghan pikas (Ochotona rufescens rufescens) was examined histopathologically. In all cases, iron deposits were present in the liver and in two-thirds of cases, there was portal fibrosis with tissue injury. In animals, in general, tissue injury induced by iron overload is usually mild and only in a few exceptional species does hepatic haemochromatosis occur. Thus, Afghan pikas are a rare example of reaction to iron overloading.

Animals↗
PubMed1990

Dose-response relationship of ozone-induced airway hyperresponsiveness in unanesthetized guinea pigs.

The effect of ozone dose (the product of ozone concentration and exposure time) on airway responsiveness was examined in unanesthetized, spontaneously breathing guinea pigs. Airway responsiveness was assessed by measuring specific airway resistance (sRaw) as a function of increasing concentration of inhaled methacholine (Mch) aerosol (the concentration of Mch required in order to double the baseline sRaw: PC200Mch). The airway responsiveness was measured before and at 5 min, 5 h, and 24 h after exposure. A 30-min exposure to 1 ppm ozone (dose 30 ppm.min) did not change PC200Mch at any time after exposure. Both a 90-min exposure to 1 ppm ozone and a 30-min exposure to 3 ppm ozone, which are identical in terms of ozone dose (90 ppm.min), decreased PC200Mch to a similar degree. A 120-min exposure to 3 ppm ozone (360 ppm.min) produced a much greater decrease of PC200Mch at 5 min and 5 h after exposure, compared with low-dose exposure. There was a significant correlation between ozone dose and the change in airway responsiveness. In all groups, the baseline sRaw was increased by approximately 50% at 5 min after exposure, but there was no correlation between the changes in PC200Mch and the baseline sRaw. This study suggests that ozone-induced airway hyperresponsiveness in guinea pigs is closely related to ozone dose.

Aerosols↗
PubMed1990

An associated molecule, p64, with high-affinity interleukin 2 receptor.

TU11 mAb specific for the human interleukin-2 receptor (IL-2R) beta-chain, p75, co-precipitated two molecules, p64 and p55, with the beta-chain in the lysates of cells bearing the high-affinity IL-2R. The co-precipitation was detected in the presence of IL-2 even in the absence of a chemical cross-linker. H-48 mAb specific for the IL-2R alpha-chain completely pre-absorbed p64 as well as p55 and partially pre-absorbed the beta-chain from the lysates. The co-precipitation was also detected in phytohemagglutinin-stimulated normal peripheral blood lymphocytes, which express the high-affinity IL-2R, but not in the cell line cells bearing only the low-affinity IL-2R. The peptide maps indicate that p64 is a molecule distinct from both the alpha- and beta-chains, and that p55 is identical to the alpha-chain. These findings suggest that p64, along with the alpha- and beta-chains, is a component of the high affinity IL-2R complex, and we have tentatively named it the gamma-chain of IL-2R.

Antibodies, Monoclonal↗
PubMed1990

Site-directed mutagenesis reveals functional contribution of Thr218, Lys220 and Asp304 in chymosin.

The functional contributions of amino acid residues Thr218 and Asp304 of chymosin, both of which are highly conserved in the aspartic proteinases, are analysed by means of site-directed mutagenesis. The optimum pH values, milk-clotting (C) and proteolytic (P) activities and kinetic parameters for synthetic oligopeptides as substrates were examined for the mutant enzymes. The mutation Thr218Ser caused a marked increase in the C/P ratio, which seemed to be due to a change in substrate recognition. Although the negative charge of Asp304 had been expected to play a role in lowering the optimum pH values in the aspartic proteinases, this turned out not to be the case in chymosin because both the mutations Asp304Ala and Asp304Glu caused a similar shift of the optimum pH towards the acidic side. In addition, the mutation Lys220Leu, which we generated previously, was found to cause a decrease in the C/P ratio, mainly due to the increase in the proteolytic activity.

Amino Acid Sequence↗
PubMed1990

Carcinosarcoma of the submandibular gland. An autopsy case.

We present a rare case of submandibular gland carcinosarcoma occurring in a 45-year-old male patient. His clinical history revealed that the carcinosarcoma had developed from a carcinoma ex mixed tumor in three years. In spite of repeated resection, intensive chemotherapy and irradiation, the tumor recurred and grew rapidly, and the patient died of hemothorax caused by rupture of a pulmonary metastatic tumor. The fourth recurrent tumor and autopsy specimens showed features of carcinosarcoma consisting of three tumor components, i.e., undifferentiated carcinoma, and chondrosarcomatous and osteosarcomatous growth. The metastatic nodules in both lungs and pulmonary hilar lymph nodes showed the same pattern. Immunohistochemically, the chondrosarcomatous cells were positive for vimentin and S-100 protein, and for epithelial markers such as epithelial membrane antigen (EMA) and cytokeratin (MA-902). Undifferentiated carcinoma cells, on the other hand, were partially positive for muscle actin other than cytokeratin (KL 1). Ultrastructurally, desmosome-like structures were seen in the chondrosarcomatous cells. These findings suggest that the sarcomatous lesions might have originated from epithelial cells.

Actins↗
PubMed1990

Normal left ventricular dimensions and function: interstudy reproducibility of measurements with cine MR imaging.

The authors evaluated the reproducibility of measurements of ventricular dimensions obtained with cine magnetic resonance (MR) imaging performed on two occasions in 11 healthy subjects. Two reviewers analyzed the studies in a blinded fashion to determine interobserver and interstudy variability of measurements of left ventricular (LV) mass, volume, ejection fraction, and systolic wall stress. LV mass showed good reproducibility between studies, with 3.6% and 3.8% variability for LV end-systolic mass for the two observers. LV end-diastolic volume varied by 5.2% and 3.9%, and LV end-systolic volume, by 9.7% and 0.9%. Variability for LV ejection fraction was 5.0% and 4.9%. The largest interstudy variability was end-systolic wall stress, 11.1% and 13.5%, which was due mostly to changes in arterial pressure between the two studies. It is concluded that anatomic and functional measurements from cine MR images are reproducible between studies. The small interstudy variability is likely related to the fact the measurements are derived directly from cine MR images that encompass the entire heart rather than depend on measurements of only sample images and the use of geometric models.

Adult↗