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Biomedical subjects

Y Shigematsu

Publications and source records attributed to Y Shigematsu.

At least 91 records · Page 5Linked to original sources
PubMed1997

[Mitral prosthetic valve replaced twice due to repeated prosthetic valve endocarditis: a case report].

A 38-year-old man was admitted to our hospital for detailed examination of fever, cough and yellow sputum. At the age of 32, be had mitral prosthesis for the first time, because of mitral regurgitation due to mitral valve prolapse. Four years previously, he had again undergone mitral prosthetic valve replacement due to prosthetic valve endocarditis due to staphylococcus epidemidis. This occasion, staphylococcus aureus was isolated by arterial blood culture. Transesophageal echocardiography detected vegetation attached to the mitral prosthetic valve and paravalvular leakage. The diagnosis was prosthetic valve endocarditis. He underwent a third mitral prosthetic valve replacement. Detection of the source of infection was difficult only by transthoracic echocardiography, and immediate transesophageal echocardiography seemed mandatory to diagnose bacterial endocarditis.

Adult↗
PubMed1997

MR changes in the calcarine area resulting from retinal degeneration.

PURPOSE: To study MR images for atrophic changes in the calcarine area resulting from retinal degeneration. METHODS: MR images from nine patients with retinal degeneration confirmed by ophthalmologic examination and from 30 healthy volunteers were reviewed. The causes of retinal degeneration were hereditary pigmentary degeneration of the retina (four patients), high myopia (two patients), and chorioretinal atrophy (three patients); all patients had visual disturbances and visual field abnormalities. To estimate the morphological changes of the calcarine area, the widths of the right and left calcarine fissures were measured on T1-weighted sagittal images and compared with images from age-matched control subjects. RESULTS: The calcarine fissures were significantly dilated in the patients with retinal degeneration. The anterior and middle points, which represent the peripheral visual field center, were more dilated than the posterior point. CONCLUSION: The MR findings suggested calcarine atrophy related to retinal degeneration. Transneuronal degenerative changes may occur in the calcarine area after retinal degeneration.

Aged↗
PubMed1997

MR of epidermoids with a variety of pulse sequences.

PURPOSE: To assess the usefulness of fluid-attenuated inversion recovery (FLAIR) and constructive interference in steady state (CISS) sequences in depicting epidermoid tumors. METHODS: Six patients with surgically confirmed epidermoid tumors in the subarachnoid space were examined with T1-weighted MR imaging with a spin-echo sequence, and with T2- and proton density-weighted imaging with a fast spin-echo sequence, a FLAIR sequence, and a CISS sequence. In the qualitative analysis, three observers compared the five sequences for visibility of tumors and presence of artifacts. A quantitative analysis was also performed by measuring the contrast-to-noise ratio. RESULTS: On visual assessment, the FLAIR sequence depicted all tumors as hyperintense relative to cerebrospinal fluid. The CISS sequence depicted all tumors as hypointense relative to cerebrospinal fluid and was considered to show tumor extension better than the FLAIR sequence. At quantitative analysis, the mean contrast-to-noise ratios of tumor to cerebrospinal fluid on T1-, T2-, and proton density-weighted images, and on FLAIR and CISS sequences were 2.85, 3.41, 4.42, 16.13, and 20.23, respectively. The contrast-to-noise ratios for the FLAIR and CISS sequences were significantly higher than those for the T1-, T2-, and proton density-weighted sequences. The contrast-to-noise ratio was not significantly different between FLAIR and CISS sequences, although the CISS sequence was slightly superior. CONCLUSION: CISS and FLAIR sequences depicted epidermoid tumors in the subarachnoid spaces better than conventional spin-echo images did. The CISS sequence produced a relatively constant contrast between the tumors and less artifactual interference.

Adolescent↗
PubMed1996

Estimation of aortic wall sclerosis in hypertension by use of carotid pulse tracing and cine magnetic resonance.

In order to evaluate aortic wall sclerosis in hypertension, the authors studied the following two parameters of carotid pulse tracing and ascending aortic wall distensibility by using cine magnetic resonance (MR) in 15 age- and sex-matched normal volunteers (NC) (mean age, fifty-four years old) and 15 hypertensive patients (HT) (mean age, fifty-four years old). As the parameters of carotid pulse tracing, they measured the interval from aortic second heart sound to dicrotic notch (A2-DN), and the height from dicrotic notch to top/total height of carotid pulse tracing (b/a ratio). Ascending aortic distensibility was calculated from the following formula: (max area - min area)/(min area x pulse pressure). A2-DN interval was lower in HT than in NC (18.4 +/- 7.9 vs 31.5 +/- 9.2 ms, P < 0.01). The b/a ratio was lower in HT than in NC (0.34 +/- 0.07 vs 0.44 +/- 0.09, P < 0.01). Ascending aortic distensibility was lower in HT than in NC (2.08 +/- 1.37 vs 7.26 +/- 2.51 x 10(-3) mmHg(-1), P < 0.01). In conclusion, ascending aortic wall sclerosis is advanced in hypertension. A2-DN interval and b/a ratio measured by carotid pulse tracing are useful indicators in evaluating the ascending aortic wall distensibility in hypertension.

Aorta↗
PubMed1996

Morphologic and histologic characterization of cardiac myxomas by magnetic resonance imaging.

The purpose of this study was to assess the role of ECG-gated spin-echo (SE) magnetic resonance (MR) images, cine MR images, and gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA)-enhanced MR images for the morphologic and histologic diagnosis of atrial myxomas. Four patients with left atrial myxoma were imaged with a 1.5-T MR imager. The T1-weighted images and the cine MR images were obtained before injection of Gd-DTPA. After the injection of Gd-DTPA, the T1-weighted images were obtained again. Gd-DTPA-enhanced images of the myxomas were histologically compared with the extracted specimens. The tumors were represented more clearly on the cine MR images as low-intensity areas than on the SE images as high-intensity areas. On post-Gd-DTPA images, the 2 tumors were homogeneously enhanced and the other 2 were inhomogeneously enhanced. The locus of enhancement on post-Gd-DTPA images fitted with histologic myxoma or inflammation, and the unenhanced region reflected the necrosis or cystic changes in the specimens, respectively. The morphologic diagnosis of cardiac myxomas by MRI first should be done with SE images, and when the images are unclear, the cine MR images must be supplemented to depict the tumor clearly. Moreover, Gd-DTPA-enhanced MRI could elucidate histologic characteristics in myxomas.

Adult↗
PubMed1996

Prenatal diagnosis of organic acidemias based on amniotic fluid levels of acylcarnitines.

Acylcarnitines in amniotic fluid samples were analyzed for the prenatal diagnosis of propionic acidemia, methylmalonic aciduria, isovaleric acidemia, and glutaric aciduria by electrospray tandem mass spectrometry. Although the levels of the specific acylcarnitine between affected and unaffected cases showed an overlap, the ratios of propionylcarnitine to 4-carbon acylcarnitine levels for propionic acidemia and methylmalonic aciduria, those of isovalerylcarnitine to propionylcarnitine for isovaleric acidemia, and those of glutarylcarnitine to propionylcarnitine for glutaric aciduria type I were shown to be reliable indicators in the prenatal diagnosis. In addition, it is suggested that the combination of the ratios of glutarylcarnitine, isovaleryl-carnitine, and hexanoylcarnitine to propionylcarnitine may be useful for the prenatal diagnosis of glutaric aciduria type II.

Acetylcarnitine↗
PubMed1996

Case report: varicella-zoster virus myelitis--serial MR findings.

The authors describe a 32-year-old male in whom herpes zoster of the left upper extremity was complicated by the development of cervical myelitis. Contrast enhancement and abnormal signal intensity on T1 and T2 weighted images was seen at C1-C6 levels in the spinal cord and medulla. There was also slight enlargement of the cord at these levels. On serial MR imaging the degree of enhancement changed from marked to none with corresponding clinical improvement.

Adult↗
PubMed1996

[Familial hypertrophic cardiomyopathy generating a marked left ventricular pressure gradient in an 82-year-old woman].

Familial nonobstructive hypertrophic cardiomyopathy in 78-year-old woman was diagnosed in 1988. Since then she has been treated with a beta-blocking drug and a calcium antagonist. Her clinical condition was NYHA I or II for several years. Echocardiography revealed asymmetric septal hypertrophy in 1988 (interventricular septal thickness = 21 mm, posterior wall thickness = 10 mm). Systolic anterior motion of the mitral valve was first observed at the end of 1992. The left ventricular pressure gradient also gradually increased; it was about 138 mmHg in 1993 (age 82 yrs). The left ventricular ejection time index increased from 376 msec in May, 1992 to 459 msec in May, 1994. In September, 1994, the patient's condition gradually deteriorated (NYHA IV), and she was admitted to our hospital. To attenuate the left ventricular pressure gradient, 150 mg of disopyramide was administered. Her condition markedly improved: the left ventricular pressure gradient decreased from 180 mmHg to 76 mmHg, and the left ventricular ejection time index decreased from 485 msec to 419 msec. These results indicate that a left ventricular pressure gradient can be generated rapidly even in a very old patient, and that disopyramide may be useful to attenuate the left ventricular pressure gradient.

Aged↗
PubMed1996

[A 66-year-old woman with a patent ductus arteriosus and no significant progression of pulmonary arterial pressure over 17 years].

We report the case of a 66-year-old woman with a patent ductus arteriosus and no significant progression of pulmonary arterial pressure over 17 years. She was admitted to our hospital in 1978 because of palpitations on exertion and chest discomfort. Cardiac catheterization was done, and she was given a diagnosis of patent ductus arteriosus. Because the left-to-right shunt was small (15%) and because there was no evidence of pulmonary hypertension (38/18 mmHg), she was treated medically. In 1995 she was admitted again, to determine the cause of a cerebral infarction. The cerebral infarction was believed to have been caused by an embolism due to atrial fibrillation. She underwent cardiac catheterization again. The left-to-right shunt had increased to 41%, but the pulmonary artery pressure had not changed (27/14 mmHg). Intravascular ultrasound imaging was used to evaluate the ductus arteriosus. The diameter of the ductus was 4.4 mm and calcification was not observed. During the 17 years of follow-up, heart size increased slightly, but pulmonary artery pressure did not change. In addition, intravascular ultrasound was very useful for evaluating the condition of the ductus arteriosus.

Aged↗
PubMed1995

Identification of a genetic mutation in a family with fructose-1,6- bisphosphatase deficiency.

Fructose-1,6-bisphosphatase deficiency is an inheritable disorder of gluconeogenesis. Sequence analysis of the cDNA of the fructose-1,6-bisphosphatase mRNA isolated from monocytes from a girl with this disease and her consanguineous parents revealed that the patient and her parents were a homozygote and heterozygotes for an insertion of one G residue at G957GGGG961, respectively. This mutation resulted in translation of a truncated enzyme protein, and the mutant protein showed no fructose-1,6- bisphosphatase activity in an overexpression experiment in Escherichia coli. However, this mutation is located in a region of the amino acid sequence which is not well conserved among mammals. A mutagenized clone was prepared from the normal clone. The extents of substitutions and deletions of the amino acid sequence were predicted to be less in the mutagenized protein than in the mutant protein. This mutagenized clone also expressed no fructose-1,6-bisphosphatase activity, although both of two normal clones from control monocytes and a control liver sample expressed an apparently normal level of fructose-1,6-bisphosphatase activity. Thus, this mutation is concluded to be responsible for fructose-1,6-bisphosphatase deficiency in this patient.

Amino Acid Sequence↗
PubMed1995

MRI findings of Zellweger syndrome.

A patient with Zellweger syndrome, who manifested marked dilatation of the lateral ventricles, observed at 34 weeks gestation by fetal ultrasonography, is reported. Postnatal magnetic resonance imaging revealed marked colpocephaly and hypogenesis of the posterior part of the corpus callosum. However, pachygyria was limited to the perisylvian regions. Biochemical diagnosis was based on increased serum very-long-chain fatty acids, 2-hydroxysebacic aciduria, and the detection of the ghosts of peroxisomal membrane in cultured fibroblasts. The patient was classified as belonging to group B of this syndrome by complementation study.

Female↗
PubMed1995

Blood pressure response to the Valsalva maneuver in pheochromocytoma and pseudopheochromocytoma.

To elucidate whether a difference in blood pressure reactivity exists between patients with pheochromocytoma (n = 8) and pseudopheochromocytoma (n = 22), we evaluated blood pressure changes during a Valsalva maneuver and baroreceptor reflex sensitivity. We also examined the effects of propranolol and prazosin on blood pressure reactivity during a Valsalva maneuver in patients with pseudopheochromocytoma. Pseudopheochromocytoma was defined as a paroxysmal rise in blood pressure accompanying pheochromocytoma-like symptoms and normal catecholamine values. The difference in systolic blood pressure between phase IV of the Valsalva maneuver and baseline (delta SBP) was markedly smaller in the pheochromocytoma patients (8.4 +/- 18.4 mm Hg) than in the essential hypertension patients (n = 30, 30.9 +/- 19.4 mm Hg) and normotensive control subjects (n = 10, 31.3 +/- 11.4 mm Hg), whereas delta SBP in the pseudopheochromocytoma patients (77.8 +/- 11.2 mm Hg) was markedly greater than in the other three groups. delta SBP was markedly suppressed by the administration of both propranolol and prazosin. Baroreceptor reflex sensitivity index was lower in the pheochromocytoma group than in the other three groups. In conclusion, blood pressure reactivity responses to a Valsalva maneuver are disparate between pheochromocytoma and pseudopheochromocytoma. The high blood pressure reactivity to a Valsalva maneuver in pseudopheochromocytoma is due to hyperactivity in both beta- and alpha 1-adrenergic receptor functions, and the low blood pressure reactivity to a Valsalva maneuver in pheochromocytoma seems to be mainly due to the desensitization of both adrenergic systems associated with chronic catecholamine excess. In addition, the impaired baroreceptor function in pheochromocytoma is partially responsible for it.

Adrenal Gland Neoplasms↗
PubMed1995

Acute effect of glyceryl trinitrate on systolic blood pressure and other hemodynamic variables.

The acute effect of glyceryl trinitrate (GTN) is mainly the reduction of systolic blood pressure (SBP) rather than diastolic blood pressure (DBP). To examine the mechanisms for decrease in SBP by GTN, the authors measured arterial compliance (AC), cardiac output (CO), stroke volume (SV), pulmonary capillary wedge pressure, right ventricular end-diastolic pressure, right atrial pressure, and left ventricular end-diastolic pressure before and after administration of GTN. Fourteen patients who underwent cardiac catheterization were included in this study. The change of each variable was estimated by the differences between values just before and at three minutes after GTN. After administration of GTN, SBP was significantly decreased from 158 +/- 21 to 138 +/- 12 mmHg (P < 0.01). AC was significantly increased, and pulmonary capillary wedge pressure, CO, and SV were significantly decreased. The change in SBP was inversely correlated with the change in AC and positively correlated with the change in CO or SV. The authors conclude that the mechanism for decrease in SBP by GTN is associated with both an increase in AC and a decrease in venous return.

Administration, Sublingual↗