Biomedical subjects

A Uemura

Publications and source records attributed to A Uemura.

At least 19 recordsLinked to original sources

PubMed2002

High signal of the striatum in sporadic Creutzfeldt-Jakob disease: sequential change on T2-weighted MRI.

The object of this study is to describe the sequential change of high signal of the striatum on T2-weighted MRI in sporadic Creutzfeldt-Jakob disease (CJD). Three cases of autopsy-proven sporadic CJD and a total of 18 serial MR images are included in this study. The degree of high signal of the striatum on T2-weighted MRI was evaluated by two neuroradiologists and divided into four grades by mutual agreement. Initial MRI of all three cases showed a slightly high signal of the bilateral striatum, and the conspicuity of the high signal became more prominent as the disease progressed. In each case the pathological change of striatum and globus pallidus was compared with the high signal on the last MR image.

Aged↗

PubMed2002

Inhaled olprinone improves contractility of fatigued canine diaphragm.

BACKGROUND: Diaphragmatic fatigue is implicated as a cause of respiratory failure. This study was undertaken to evaluate the effects of inhaled olprinone, a newly developed phosphodiesterase III inhibitor, on the contractility of fatigued diaphragm in dogs. METHODS: Diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz stimulation applied for 30 min. When fatigue was established, group I (n=8) received inhaled vehicle; group II (n=8) received inhaled olprinone 1 mg; group III (n=8) received inhaled olprinone 2 mg. Diaphragmatic contractility was assessed by transdiaphragmatic pressure (Pdi, cm H2O). RESULTS: In the presence of fatigue, in each group, Pdi at low-frequency (20 Hz) stimulation decreased from baseline values (P<0.05), whereas Pdi at high-frequency (100 Hz) stimulation did not change. In groups II and III, during olprinone administration, Pdi at both stimuli increased from fatigued values (20 Hz stimulation: group II (mean (SD)) 10.8 (1.0) to 12.5 (1.3), group III 10.9 (1.7) to 15.0 (3.0); 100 Hz stimulation: group II 20.1 (1.9) to 22.6 (1.3), group III 20.6 (2.0) to 24.5 (2.0), P<0.05). The increase in Pdi was larger in group III than in group II (P<0.05). CONCLUSIONS: Inhaled olprinone produces a dose-dependent improvement in contractility of fatigued canine diaphragm.

Administration, Inhalation↗

PubMed2002

Clinicopathological correlation of polypoidal choroidal vasculopathy revealed by ultrastructural study.

AIMS: To describe the clinical and histopathological findings in a patient with polypoidal choroidal vasculopathy. METHODS: A 76 year old Japanese man had a discrete, orange-red lesion of 1 disc diameter in the macula, with the fluorescein and indocyanine green angiographic and optical coherence tomographic findings compatible with polypoidal choroidal vasculopathy. He underwent a surgical removal of the macular lesion, followed by light and electron microscopic examinations. RESULTS: The histopathological examination revealed that the specimen consisted of degenerated retinal pigment epithelium-Bruch's membrane-choriocapillaris complex and inner choroid. A tortuous, unusually dilated venule was present adjacent to an arteriole with marked sclerotic changes, appearing to form arteriovenous crossing. These vessels seemed to represent native inner choroidal vessels, and had haemorrhage per diapedesis. Blood cells and fibrin filled the lumina of the vessels and accumulated in the extravascular spaces, indicating vascular stasis. CONCLUSION: Hyperpermeability and haemorrhage due to stasis of a dilated venule and an arteriole involved by sclerosis at the site where they cross in the inner choroid might cause oedema and degeneration of the tissue. Voluminous accumulation of blood cells and fibrin might generate elevation of tissue pressure sufficient to displace the weakened lesion anteriorly. The result suggests that the polypoidal vessels in this case represent abnormality in the inner choroidal vasculature.

Aged↗

PubMed2001

Initial stages of posterior vitreous detachment in healthy eyes of older persons evaluated by optical coherence tomography.

OBJECTIVE: To promote understanding of the development of posterior vitreous detachment (PVD) in healthy eyes using optical coherence tomography (OCT). METHODS: We studied 209 eyes of 209 healthy volunteers (165 men and 44 women; mean age, 52.3 years [range, 31-74 years]). In addition to biomicroscopy and ophthalmoscopy, OCT was performed to obtain high-resolution cross-sectional images of the vitreoretinal interface in the posterior fundus. RESULTS: The condition of the posterior vitreoretinal interface was classified as 1 of 5 stages, according to biomicroscopic findings and OCT images relative to discrete linear signals indicating a detached posterior vitreous face: stage 0, no PVD (61 eyes [29.2%]); stage 1, incomplete perifoveal PVD in up to 3 quadrants (100 eyes [47.8%]); stage 2, incomplete perifoveal PVD in all quadrants, with residual attachment to the fovea and optic disc (26 eyes [12.4%]); stage 3, incomplete PVD over the posterior pole, with residual attachment to the optic disc (4 eyes [1.9%]); or stage 4, complete PVD identified with biomicroscopy, but not with OCT because of instrument limitations (18 eyes [8.6%]). Stage 1, 2, and 3 incomplete PVD without subjective symptoms was not recognizable on contact lens biomicroscopy. There was a significant age-related progression in the condition of the vitreoretinal interface from stage 0 to stage 4. The superior quadrant was usually the initial site of incomplete PVD. CONCLUSIONS: Optical coherence tomography demonstrates that healthy human eyes have incomplete or partial PVD beginning as early as the fourth decade of life. Age-related PVD occurs initially as a focal detachment in the perifovea of 1 quadrant, with persistent attachment to the fovea and optic nerve head, with a predilection for the superior quadrant. It extends its range slowly for years and eventually results in complete PVD, associated with release of vitreopapillary adhesion.

Adult↗

PubMed2001

Transcatheter arterial embolization for bone metastases from hepatocellular carcinoma.

The objective of this study was to determine which of the following three methods is the most effective for the treatment of bone metastases from hepatocellular carcinoma (HCC): transcatheter arterial embolization (TAE); combination of TAE and external radiotherapy; or external radiotherapy alone. Thirty-nine metastatic bone lesions from HCC in 33 patients were retrospectively reviewed. Each lesion underwent either TAE alone (group A, n = 11), TAE followed by radiotherapy (group B, n = 17), or radiotherapy alone (group C, n = 11). They were evaluated on the following subjects: pain relief; improvement of daily activities; and complications. Each treatment was effective for pain relief (89-94%) and improvement of daily activities (73-82%). The mean time interval from the beginning of each treatment to the onset of initial pain relief was 4.7 days in group A, 4.8 days in group B, and 15 days in group C. Recurrence of the pain after the initial pain relief was noted in 75% in group A, 20% in group B, and 88% in group C. Pyrexia and local pain commonly occurred after TAE. In conclusion, TAE is effective in relieving pain immediately and in improving the patients' daily activities. The combination of TAE and radiotherapy is recommended for permanent pain relief.

Aged↗

PubMed2001

Postsurgical evaluation of idiopathic vitreomacular traction syndrome by optical coherence tomography.

PURPOSE: To report a case of idiopathic vitreomacular traction syndrome with preoperative and postoperative evaluation by optical coherence tomography. DESIGN: Interventional case report. METHODS: A 62-year-old woman presented with blurred vision in the left eye because of idiopathic vitreomacular traction syndrome, and she underwent a pars plana vitrectomy. Optical coherence tomography was performed before and after surgery. RESULTS: Preoperative optical coherence tomography, right eye, revealed residual adhesion of incomplete posterior vitreous detachment and edematous, thickened outer retina in the macula. A successful vitrectomy relieved vitreoretinal traction with nearly complete resolution of cystoid macular edema within 1 month after surgery, followed in subsequent months by gradual foveal depression resembling a lamellar macular hole. Resolution of subretinal serous fluid was delayed with complete disappearance, some 12 months after surgery, which correlated with a gradual improvement in visual acuity. CONCLUSION: Optical coherence tomography provides a sensitive anatomical evaluation of vitreomacular traction syndrome. Reorganization of retinal tissue after surgical intervention for vitreoretinal traction may be slower than is apparent from conventional examinations.

Diagnostic Techniques, Ophthalmological↗

PubMed2001

Fate alteration of neuroepithelial cells from neurogenesis to astrocytogenesis by bone morphogenetic proteins.

Bone morphogenetic proteins (BMPs), a class of cytokines belonging to the transforming growth factor-beta superfamily, have been shown to play a wide variety of roles during development including those in the central nervous system. We here report that BMP2, BMP4 and BMP7 have an equivalent potential to inhibit neurogenesis and concomitantly induce astrocytogenesis of mouse fetal neuroepithelial cells. We further show that these BMPs activate a promoter of the gene for negative helix-loop-helix (HLH) factor, Id1, which is known to inhibit the function of such neurogenic transcription factors as Mash1 and neurogenin. These results suggest that BMP2, BMP4 and BMP7 alternate the fate of neuroepithelial cells from neuronal type to astrocytic one via a common mechanism involving negative HLH factor.

Activin Receptors, Type I↗

PubMed2001

DNA methylation is a critical cell-intrinsic determinant of astrocyte differentiation in the fetal brain.

Astrocyte differentiation, which occurs late in brain development, is largely dependent on the activation of a transcription factor, STAT3. We show that astrocytes, as judged by glial fibrillary acidic protein (GFAP) expression, never emerge from neuroepithelial cells on embryonic day (E) 11.5 even when STAT3 is activated, in contrast to E14.5 neuroepithelial cells. A CpG dinucleotide within a STAT3 binding element in the GFAP promoter is highly methylated in E11.5 neuroepithelial cells, but is demethylated in cells responsive to the STAT3 activation signal to express GFAP. This CpG methylation leads to inaccessibility of STAT3 to the binding element. We suggest that methylation of a cell type-specific gene promoter is a pivotal event in regulating lineage specification in the developing brain.

Animals↗

PubMed2001

Light-use properties in two sun-adapted shrubs with contrasting canopy structures.

We investigated the impact of high solar irradiance and elevated temperature on carbon gain by two, co-occurring, sun-adapted, dwarf shrub species, Planchonella obovata var. dubia (Koidz.) Hatusima and Hibiscus glaber Matsumura, growing on sun-exposed ridges in the Bonin Islands, in the subtropical Pacific Ocean. Planchonella had steeply inclined, longer lived, sclerophyllous leaves, whereas Hibiscus has thinner, more horizontally oriented, and shorter lived leaves. We tested the hypothesis that leaf physiological tolerance to high light is lower in Planchonella than in Hibiscus. Under relatively high irradiances (photosynthetic photon flux density, PPFD, > 500 micromol m(-2) s(-1)), net photosynthetic rate (P(n)) was about 8.0 and 0.4 micromol m(-2) s(-1) in mature and young leaves of Planchonella, and about 12.4 and 10.3 micromol m(-2) s(-1) in mature and young leaves of Hibiscus, respectively. Both P(n) and photosystem II (PSII) quantum yield at a given PPFD were lower in Planchonella than in Hibiscus, whereas non-photochemical quenching (NPQ) at a given PPFD was higher in Planchonella. When leaf discs were exposed to high light (1900 micromol m(-2) s(-1) PPFD) at 37, 40 or 43 degrees C for 3 h, the recovery of PSII quantum yield (F(v)/F(m)) in the following 60-min dark period was slower in Planchonella than in Hibiscus, indicating that the ability of PSII to tolerate high light and high temperature was less in Planchonella than in Hibiscus. We postulate that there is a linkage between leaf display and leaf photochemical ability in sun-adapted shrub species.

Magnoliopsida↗

PubMed2001

Dose-response characteristics of midazolam for reducing diaphragmatic contractility.

A sedative dose of midazolam decreases contractility of the diaphragm, but no data are available concerning the relationship between dose and diaphragmatic contractility. We studied the dose-response characteristics of midazolam for reducing the diaphragmatic contractility in dogs. Animals were divided into three groups of eight each: Group 1 received no study drug, Group 2 was infused with a sedative dose of midazolam (0.1 mg/kg initial dose plus 0.1 mg x kg(-1) x h(-1) maintenance dose), and Group 3 was infused with an anesthetic dose of midazolam (0.1 mg/kg initial dose plus 0.5 mg x kg(-1) x h(-1) maintenance dose). We assessed the diaphragmatic contractility by transdiaphragmatic pressure (Pdi). With an infusion of midazolam in Groups 2 and 3, Pdi at low-frequency (20 Hz) and high-frequency (100 Hz) stimulation decreased from the baseline values (P < 0.05), and the integrated electrical activity of diaphragm (Edi) at 100-Hz stimulation decreased from the baseline values, whereas Edi at 20-Hz stimulation did not change. Compared with Group 1, Pdi and Edi for each stimulus decreased during midazolam infusion in Groups 2 and 3 (P < 0.05). The decrease in Pdi and Edi was more in Group 3 than in Group 2 (P < 0.05). We conclude that midazolam decreases, in a dose-dependent manner, contractility of the diaphragm in dogs.

Anesthetics, Intravenous↗

PubMed2001

The dose-range effects of propofol on the contractility of fatigued diaphragm in dogs.

UNLABELLED: Diaphragmatic fatigue may contribute to the development of respiratory failure. We studied the dose-range effects of propofol on the contractility of fatigued diaphragm in dogs. Animals were divided into three groups of eight each. In each group, diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20-Hz stimulation for 30 min. Immediately after the end of a fatigue-producing period, Group 1 received no study drug; Group 2 was infused with small-dose propofol (0.1 mg/kg initial dose plus 1.5 mg x kg(-1) x h(-1) maintenance dose); Group 3 was infused with large-dose propofol (0.1 mg/kg initial dose plus 6.0 mg x kg(-1) x h(-1) maintenance dose). We assessed diaphragmatic contractility by transdiaphragmatic pressure (Pdi). After the fatigue-producing period, in each group, Pdi at low-frequency (20-Hz) stimulation decreased from baseline values (P < 0.05), whereas there was no change in Pdi at high-frequency (100-Hz) stimulation. In Groups 2 and 3, with an infusion of propofol, Pdi at 20-Hz stimulation decreased from fatigued values (P < 0.05). Compared with Group 1, Pdi at 20-Hz stimulation decreased from fatigued values (P < 0.05) during propofol administration in Groups 2 and 3. The decrease in Pdi was more in Group 3 than in Group 2 (P < 0.05). We conclude that propofol decreases the contractility of fatigued canine diaphragm in a dose-related fashion. IMPLICATIONS: Propofol is a widely used IV anesthetic for the induction and maintenance of general anesthesia and sedation. It decreases, in a dose-related fashion, the contractility of fatigued diaphragm in dogs.

Anesthetics, Intravenous↗

PubMed2001

Transient ventricular wall thickening in acute myocarditis: a serial echocardiographic and histopathologic study.

The present study was designed to determine whether the wall thickening seen in acute myocarditis is caused by interstitial edema. The study group comprised 25 patients (idiopathic myocarditis, 17; eosinophilic myocarditis, 8) in whom acute myocarditis was diagnosed histologically and who underwent echocardiography and endomyocardial biopsy during both the acute and convalescent phases. The following echocardiographic parameters were measured: interventricular septum and left ventricular posterior wall thickness, left ventricular end-diastolic dimension, and left ventricular ejection fraction. Based on the myocardial biopsy specimens, the degree of interstitial edema was classified into 3 grades [(-), 1(+), 2(+)] and the transverse diameter of cardiac myocytes was measured using light microscopy. The thickness of both the interventricular septum and left ventricular wall decreased from 14.3+/-3.7 mm and 13.3+/-2.4 mm in the acute phase to 9.7+/-1.7 mm (p<0.001) and 10.2+/-1.7 mm (p<0.0001), respectively, in the convalescent phase. Edema was present in 22 patients (88.0%) in the acute phase, but in the convalescent phase, edema was present in only 7 patients (28.0%), indicating a significant reduction in the degree of edema (p<0.0001). Cardiac myocyte diameter did not differ significantly between the acute (13.6+/-1.1 microm) and convalescent (13.8+/-1.8 microm) phases.

Acute Disease↗

PubMed2001

Endomyocardial biopsy findings in 50 patients with idiopathic atrioventricular block: presence of myocarditis.

In patients with primary atrioventricular (AV) conduction disturbances, lesions are commonly believed to be limited to the conduction system. In the present study, myocardial lesions were analyzed histologically in patients with AV conduction disturbances to determine the presence of myocarditis. We studied 50 patients with second or third degree AV block in whom the cause was not clear (AVB group). Endomyocardial biopsy was performed from the right ventricle and examined by light microscopy. Tissue specimens also were obtained from 12 normal hearts at autopsy as a control group (N group). The diagnosis of myocarditis was based on the Dallas criteria. The myocyte transverse diameter was 15.4+/-4.1 microm in the AVB group and 11.7+/-3.1 microm in the N group (P<0.01). The fibrosis area ratio also was significantly higher in the AVB group than in the N group (10.1+/-6.7% vs 5.1+/-2.0%). The mean number of lymphocytes per 400-fold magnified field was significantly greater in the AVB group than in the N group (1.9+/-1.6 vs 1.3+/-0.4). In addition, disorganization of the cardiac myocytes was noted in 8 patients in the AVB group (16%), myocyte disarrangement in 39 patients (78%), myocytolysis in 23 patients (46%), and nuclear deformity in 21 patients (42%). Myocarditis was diagnosed in 3 of the 50 patients (6%). The present study demonstrates that myocardial lesions can be detected in a large proportion of patients with AV conduction disturbances. Furthermore, myocarditis is present in 6% of the cases.

Adolescent↗

PubMed2001

[Follow-up studies of optic neuritis with lymphocytic adenohypophysitis].

BACKGROUND: We report a 38-year-old female suffering from bilateral optic neuritis with lymphocytic adenohypophysitis. CASE: The initial symptom of the 38-year-old-female was diabetes insipidus. Magnetic resonance imaging showed swollen pituitary stalk and disappearance of the T1 shortening of the neurohypophysis. Immunological tests showed that the serum anterior pituitary antibody was positive. These findings suggested lymphocystic adenohypophysitis. Bilateral optic neuritis also occurred and the pattern visual evoked cortical potential (VECP) demonstrated increased P100 peak latency and reduction of amplitude. After steroid pulse therapy, the visual acuity and field improved and the pattern VECP became normal. Temporal hemianopia was not noted. CONCLUSION: A direct infiltration of the inflammatory change in the pituitary gland or some autoimmune problem was considered as a cause of the optic neuritis. In contrast to the VECPs of multiple sclerosis patients, the prolonged peak latency of pattern VECPs of this case were shortened in accordance with the recovery of visual acuity.

Adult↗

PubMed2000

Visual outcome after surgical removal of choroidal neovascularization in pediatric patients.

OBJECTIVE: To assess the visual outcome after surgical removal of choroidal neovascularization (CNV) in pediatric patients. METHODS: A retrospective, noncomparative, consecutive case series of 17 eyes undergoing surgical removal of CNV of various causes in patients aged 18 years and younger. RESULTS: The cause of the CNV was presumed ocular histoplasmosis syndrome in 11 eyes, idiopathic in 3, and optic nerve coloboma, ocular toxoplasmosis, and trauma in 1 eye each. Two eyes had CNV within 100 microm of the center of the foveal avascular zone (juxtafoveal CNV) and 1 eye had peripapillary CNV, while 14 eyes had CNV beneath the geometric center of the foveal avascular zone (subfoveal CNV). In eyes with subfoveal CNV, median preoperative Snellen visual acuity was 20/200 (range, 20/80-3/200). With a median follow-up of 27 months (range, 6-45 months), median final visual acuity was 20/50 (range, 20/20-2/200); 10 (72%) had improvement of 2 or more Snellen lines after surgery, and 6 eyes (43%) had final visual acuity of 20/40 or better. In 3 eyes with juxtafoveal CNV or peripapillary CNV, all eyes had improvement of 4 or more Snellen lines. Postoperative recurrent CNV developed in 6 (35%) of 17 patients; 2 of the eyes underwent a second vitrectomy and 4 received laser treatment for the recurrences. CONCLUSIONS: Pediatric patients may have good recovery of vision after surgical removal of CNV, and the removal of these membranes may be a viable alternative to laser photocoagulation in pediatric patients.

Adolescent↗

PubMed2000

Subretinal surgery for choroidal neovascularization in patients with high myopia.

OBJECTIVE: To analyze the visual outcome in patients undergoing surgical removal of subfoveal choroidal neovascularization (CNV) in eyes with high myopia. METHODS: We retrospectively reviewed the medical records of 48 consecutive patients with high myopia (> or =6 diopters [D]) who underwent vitrectomy with surgical removal of subfoveal CNV. The patient population consisted of 2 groups. Group 1 included 23 patients with findings only of myopic degeneration, and group 2 included 25 patients with presumed ocular histoplasmosis syndrome and myopia of 6 D or more. RESULTS: In group 1, the visual acuity improved by 2 or more Snellen lines in 9 eyes (39%), decreased in 8 eyes (35%), and remained unchanged in 6 (26%), with a mean follow-up of 24 months (range, 8-60 months). The preoperative visual acuity was 20/40 or better in only 1 eye (4%), but 8 (35%) achieved a final visual acuity of 20/40 or better. In group 2, the visual acuity improved in 16 eyes (64%), was stable in 4 (16%), and deteriorated in 5 (20%), with a mean follow-up of 18 months (range, 6-44 months). Only 3 eyes (12%) had a preoperative visual acuity of 20/40 or better, but 11 (44%) achieved a final visual acuity of 20/40 or better. Recurrence occurred in 13 (57%) of the 23 eyes in group 1 and in 9 (36%) of the 25 eyes in group 2. Univariate analysis demonstrated a significant relation between younger patient age (group 1) and absence of postoperative CNV recurrence (group 2) and an improvement of visual acuity (P<.01). CONCLUSIONS: Surgical removal of CNV may provide visual benefit in selected cases of subfoveal CNV associated with high myopia. The determination of whether surgical intervention is appropriate in these cases requires a prospective, randomized, clinical trial.

Adolescent↗

PubMed2000

Contribution of cardiac muscle cell disorganization to the clinical features of hypertrophic cardiomyopathy.

Heart failure rarely develops in the setting of hypertrophic cardiomyopathy (HCM). Because of this, cardiac muscle cell disorganization (CD), which is a histologic characteristic of HCM, is not believed to be responsible for the development of systolic dysfunction. The aim of the present study was to clarify whether CD can cause systolic dysfunction and ventricular dilation in patients with HCM. Sixteen hearts from patients with HCM obtained at autopsy were divided into two groups: group A (n = 11), without biventricular dilation, and group B (n = 5), with dilation. Specimens consisting of transverse and longitudinal tissue sections of the ventricles were prepared, and the extent of CD and interstitial fibrosis was quantified, using light microscopy. None of the patients in group A had had chronic congestive heart failure, while all of the patients in group B had died of congestive heart failure. In group B, CD was not limited to the interventricular septum. Rather, diffuse CD was observed in both ventricular free walls. The extent of CD was significantly greater in group B than in group A, while the degree of interstitial fibrosis was similar in the two groups (13.6% in group A vs 14.6% in group B). These results suggest that CD may be responsible for systolic dysfunction and ventricular dilation.

Adolescent↗

PubMed2000

Acclimation of leaf characteristics of Fagus species to previous-year and current-year solar irradiances.

To examine the effects of different solar irradiances on leaf characteristics at the leaf primordium and expansion stages, we shaded parts of branches in the upper canopies of two adult beech trees, Fagus crenata Blume and Fagus japonica Maxim., for 4 years. The treatments during the leaf primordium and leaf expansion stages, respectively, were: (1) high light and high light (H, control), (2) high light and low light (HL), (3) low light and low light (LL), and (4) low light and high light (LH). Both number of cell layers in palisade tissue and individual leaf area were affected by the previous-year irradiance, whereas cell length of palisade tissue was larger in LH leaves than in LL leaves, suggesting determination by current-year irradiance. Lamina chlorophyll/nitrogen ratio was higher in HL and LL leaves than in LH leaves, suggesting determination by current-year irradiance. Diurnal minimum values of leaf water potential measured under sunlit conditions were lower in H and LH leaves than in HL and LL leaves. Effective osmotic adjustment was found in H and LH leaves, suggesting that leaf water relations were affected by current-year irradiance. Net photosynthetic rate and stomatal conductance measured under sunlight conditions were higher in H and LH leaves than in HL and LL leaves. Thus, effects of current-year irradiance had a greater effect on leaf-area-based daily carbon gain than previous-year irradiance.

Acclimatization↗