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F Okamoto

Publications and source records attributed to F Okamoto.

At least 19 recordsLinked to original sources
PubMed2006

Retention and removal of a new viscous dispersive ophthalmic viscosurgical device during cataract surgery in animal eyes.

AIMS: To assess the retention and removal properties of a new viscous dispersive ophthalmic viscosurgical device (OVD), DisCoVisc, in comparison with those of cohesive (Provisc), dispersive (Viscoat), and viscoadaptive (Healon5) OVDs. METHODS: In 20 porcine eyes, cataract surgery was simulated using one of the four OVDs which were stained with fluorescein for better visualisation. Three parameters were measured. Firstly, the presence/absence of OVDs in the chamber at the completion of phacoemulsification was recorded. Secondly, the time until the OVDs were completely removed from the anterior chamber using the phaco needle was measured. Thirdly, after intraocular lens (IOL) implantation, the time needed to completely remove the OVDs from the chamber with irrigation/aspiration tip was recorded. RESULTS: At the completion of phacoemulsification, the OVDs retained in 0% (0/5) for Provisc, 80% (4/5) for Healon5, 100% (5/5) for DisCoVisc, and 100% (5/5) for Viscoat. The retention of OVDs during phacoemulsification was greatest with Viscoat followed by, in descending order, DisCoVisc, Healon5, and Provisc. The removal of OVDs after IOL implantation took longest with Viscoat followed by Healon5, DisCoVisc, and Provisc. CONCLUSION: The viscous dispersive DisCoVisc showed excellent retention during phacoemulsification, while its removal after IOL implantation was very easy. When compared with the viscoadaptive Healon5, DisCoVisc was retained better in the chamber and was easier to remove. These features of DisCoVisc should be highly advantageous when considering covering the entire cataract surgery procedure with a single OVD.

Animals↗
PubMed2005

Importance of early repair of isolated abdominal aortic dissecting aneurysm.

BACKGROUND: Since the available information on isolated abdominal aortic dissecting aneurysm (AADA) is mainly related to case reports or reports of small groups of patients, its natural history remains undetermined and there is no agreement on its optimal management. The purpose of this study is to define the features and pattern of development of this unusual entity as well as to propose criteria for treatment based on our own experience and previously published data. PATIENTS AND METHODS: We retrospectively evaluated the history of 6 patients diagnosed with AADA. The patients were 5 males and 1 female. The mean age was 71 +/- 8 years (range: 61-80 years), and the mean aneurysm diameter was 54 +/- 14 mm (range: 35-70 mm). All of these patients were hypertensive (100%). History of cerebrovascular accident, ischemic heart disease, peripheral arterial disease, or diabetes mellitus was present in 1 patient, respectively. Two patients developed mycotic AADA. RESULTS: Emergency operations had been performed in 3 cases, and scheduled surgical reconstruction in the remaining 3 cases. Operation consisted of aneurysmectomy and graft replacement of the diseased aortic segment in all cases. One patient treated in an emergency setting died subsequently of multisystem organ failure, but the others did well. CONCLUSION: Symptomatic patients or patients at good risk should undergo surgical repair earlier than in the case of abdominal aortic aneurysm without dissection (AAA). Dissection in addition to an AAA will further increase the weakness of the aortic wall and the possibility of aortic rupture will become higher.

Aged↗
PubMed2004

Comparison of corneal thickness measurements using Orbscan II, non-contact specular microscopy, and ultrasonic pachymetry in eyes after laser in situ keratomileusis.

AIMS: To compare central corneal thickness measurements of three pachymetry devices in eyes after laser in situ keratomileusis (LASIK). METHODS: Central corneal thickness was measured in 203 eyes after myopic LASIK. Orbscan II scanning slit topography (Bausch & Lomb), SP-2000P non-contact specular microscopy (Topcon), and ultrasonic pachymetry (Tomey) were used in this sequence. RESULTS: Three devices gave significantly different corneal thickness readings (p<0.0001, repeated measure analysis of variance). The measurements of Orbscan II (445.6 (SD 60.0) microm) were significantly smaller than those of noncontact specular microscopy (467.9 (SD 40.2) micro m; p<0.0001, Tukey multiple comparison) and ultrasonic pachymetry (478.8 (SD 41.9) microm; p<0.0001). The value obtained with SP-2000P non-contact specular microscopy was significantly smaller than that taken with ultrasonic pachymetry (p<0.001). There were significant linear correlations between scanning slit topography and non-contact specular microscopy (Pearson's correlation coefficient r = 0.912, p<0.0001), non-contact specular microscopy and ultrasonic pachymetry (r = 0.968, p<0.0001), and ultrasonic pachymetry and scanning slit topography (r = 0.933, p<0.0001). CONCLUSION: In post-LASIK eyes, Orbscan II scanning slit topography significantly underestimated corneal thickness. Non-contact specular microscopy gave smaller thickness readings than ultrasonic pachymetry, but these two units showed an excellent linear correlation.

Adult↗
PubMed2002

[Assessment of saphenous vein grafts flow by Doppler echocardiography].

In an effort to evaluate flow characteristics of the saphenous vein grafts (SVG) after coronary artery bypass grafting, we performed duplex scanning of SVG which were anastomosed to the left anterior descending artery in 12 patients, and compared those indexes with 34 internal thoracic artery grafts (ITAG). The SVG were observed with a 7.5 MHz duplex scanner through the anterior intercostal space. The diameter of the vessel, systolic peak velocity, and diastolic peak velocity were recorded in both groups, and systolic flow volume, diastolic flow volume, and velocity ratio were calculated. The systolic and diastolic peak velocity of SVG were predominantly lower than ITAG. No difference in the diameter and flow ratio could not be demonstrated between 2 groups. The flow volume of SVG were also predominantly lower than that of ITAG throughout cardiac cycle. This study reveals that advanced stenotic change were caused in the SVG group and suggest the occurrence of vein grafts disease long after coronary artery bypass grafting.

Aged↗
PubMed2001

Genistein, a soybean isoflavone, inhibits inward rectifier K(+) channels in rat osteoclasts.

Genistein, a soybean-derived isoflavone with an inhibitory effect on protein tyrosine kinases (PTKs), has been shown to suppress osteoclastic bone resorption. To clarify the mechanisms underlying this action, we investigated the effects of genistein on inward rectifier K(+) current (I(Kir)) in rat osteoclasts by using the whole-cell patch-clamp technique. Extracellularly applied genistein inhibited I(Kir) in a concentration-dependent manner. Physiologically attainable concentrations of genistein inhibited I(Kir). IC(50) values obtained 5 and 10 min after the application of genistein were 54 and 27 microM, respectively. The removal of genistein partially restored the current. Daidzein, an isoflavone without PTK-inhibiting activity, also showed a weak inhibitory effect on I(Kir), but genistin had no effect. Other PTK inhibitors, tyrphostin A25, tyrphostin B42, and tyrphostin B46, inhibited I(Kir), whereas herbimycin A and lavendustin A were without effect. The inactive tyrphostin, A1, showed a similar inhibitory effect as tyrphostin A25. The tyrosine phosphatase inhibitor, orthovanadate, did not affect the inhibitory potency of genistein on I(Kir). The inhibitory action of genistein was unaffected by changing intracellular Ca(2+) concentration ([Ca(2+)]i) or by pretreatment of the cell with GDPbetaS, Rp-cAMPS, okadaic acid, or staurosporine. Therefore the inhibition of I(Kir) by genistein does not depend on PTK inhibition, involvement of changes in [Ca(2+)]i, or secondary interaction with protein kinase A or protein kinase C. Genistein-induced inhibition of I(Kir) would cause membrane depolarization, elevation of [Ca(2+)]i, and inhibition of osteoclastic bone resorption.

Animals↗
PubMed2001

Defect in human myocardial long-chain fatty acid uptake is caused by FAT/CD36 mutations.

Because of the importance of long-chain fatty acids (LCFAs) as a myocardial energy substrate, myocardial LCFA metabolism has been of particular interest for the understanding of cardiac pathophysiology. Recently, by using radiolabeled LCFA analogues, myocardial LCFA metabolism has been clinically evaluated, which revealed a total defect of myocardial LCFA accumulation in a small number of subjects. The mechanism for the cellular LCFA uptake process is still disputable, but recent results suggest that fatty acid translocase (FAT)/CD36 is a transporter in the heart. In the present study, we analyzed mutations and protein expression of the FAT/CD36 gene in 47 patients who showed total lack of the accumulation of a radiolabeled LCFA analogue in the heart. All the patients carried two mutations in the FAT/CD36 gene, and expression of the FAT/CD36 protein was not detected on either platelet or monocyte membranes. Our results showed the link between mutations of the FAT/CD36 gene and a defect in the accumulation of LCFAs in the human heart.

Adolescent↗
PubMed2001

[Assessment of left internal thoracic artery graft by exercise Doppler echocardiography].

Doppler echocardiography has several advantages such as frequent use, noninvasive approach, and physiological evaluation. Supine bicycle exercise testing was conducted for 30 patients undergoing CABG with LITA to LAD. Doppler echocardiography studies were performed before and after exercise to observe the change. On the basis of the angiographic data, patients were divided into two groups: 27 patients with a patent LITA graft, 3 patients with mildly stenosed LITA graft. In the patients who had patent grafts, diastolic flow velocity were increased higher than systolic after exercise. In the stenotic group, the flow pattern was changed to further systolic one. Doppler echocardiography during exercise is thought to be a reliable method to assess the LITA flow.

Adult↗
PubMed2000

Protein tyrosine kinase inhibitors increase cytosolic calcium and inhibit actin organization as resorbing activity in rat osteoclasts.

Although there is evidence that protein tyrosine kinase inhibitors (PTKIs) suppress bone resorption activity, the mechanism of action of these compounds on osteoclastic bone resorption remains obscure. In the present study, we investigated the effect of PTKIs on cytosolic Ca(2+) concentration ([Ca(2+)](i)) and on the cytoskeleton in rat osteoclasts. The PTKIs, genistein and herbimycin A, reversibly elevated [Ca(2+)](i) measured by fura-2 microfluorimetry. The PTKI-induced increase was abolished by omission of extracellular Ca(2+), but was not attenuated by depletion of Ca(2+) stores. The PTKI-induced increase was inhibited by addition of La(3+) and Ni(2+), but not abolished by dihydropyridine (DHP) Ca(2+) channel blockers. Genistin, an inactive analogue of genistein, had no effect on [Ca(2+)](i). In the cytoskeleton assay, genistein rapidly disrupted the actin ring formation that serves as a marker for the resorbing state of osteoclasts. Disruption of the actin ring formation was also diminished in Ca(2+)-free extracellular solution. These results suggest that PTKIs in rat osteoclasts elevate [Ca(2+)](i) via activation of a DHP-insensitive, nonspecific Ca(2+) entry pathway and disrupt the formation of actin rings, resulting in suppression of bone resorption activity. The regulation of this Ca(2+)-influx by PTKIs is likely to contribute to inhibition of bone resorption by these compounds.

Actin Cytoskeleton↗
PubMed2000

Estrogen directly acts on osteoclasts via inhibition of inward rectifier K+ channels.

Using the whole-cell patch-clamp technique in freshly isolated rat osteoclasts we examined the effects of estrogen on ionic channels. The predominant current was an inward rectifier K+ current (IKir). In the absence of non-osteoclastic cells, extracellularly applied 17beta-estradiol (>0.1 microM) inhibited IKir, indicating that estrogen acts directly on osteoclasts. Application of 17beta-estradiol (10 microM) for 10 min reduced IKir at the membrane potential of -120 mV to 70 +/- 15% of control. Removal of 17beta-estradiol partially restored the inhibition. The inhibition of IKir was dependent on concentration and application time. Intracellularly applied 17beta-estradiol had no effect on IKir. 17alpha-estradiol also inhibited the IKir, whereas progesterone and testosterone had no effect. The inhibitory action of 17beta-estradiol was not affected by guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), adenosine 3',5'-cyclic monophosphothioate Rp diastereomer (Rp-cAMPS), okadaic acid, staurosporine and phorbol ester, and was independent of intracellular Ca2+ concentration ([Ca2+]i). With no influence from soluble factors secreted from non-osteoclastic cells, preincubation of the osteoclasts for more than 60 min with much lower concentrations of 17beta-estradiol (1 and 10 nM) caused a reduction of IKir. In current-clamp configuration, application of 17beta-estradiol (10 microM) depolarized the membrane associated with a decrease in a membrane conductance, indicating that 17beta-estradiol inhibits IKir and depolarizes the membrane of osteoclasts. These results suggest that the 17beta-estradiol-induced inhibition of IKir might be mediated via non-genomic mechanisms. This direct action of 17beta-estradiol on osteoclasts may contribute to the regulation of [Ca2+]i and partially account for the protective effects of estrogen against bone loss.

Animals↗
PubMed2000

Refractive changes in diabetic patients during intensive glycaemic control.

AIMS: To evaluate the clinical course and the characteristics of transient refractive error occurring during intensive glycaemic control of severe hyperglycaemia. METHODS: 28 eyes of patients with persistent diabetes were included in this prospective study. During the observation period, patients underwent general ophthalmological examination and A-mode scan ultrasonography was performed at each examination-at days 1, 3, and 7, and then once every week or every other week until recovery of hyperopia. RESULTS: A transient hyperopic change occurred in all patients receiving improved control after hyperglycaemia. Hyperopic change developed a mean of 3.4 (SD 2. 0) days after the onset of treatment, and reached a peak at 10.3 (6. 1) days, where the maximum hyperopic change in an eye was 1.47 (0. 87) D (range 0.50-3.75 D). Recovery of the previous refraction occurred between 14 and 84 days after the initial assessment. There was a positive correlation between the magnitude of the maximum hyperopic change and (1) the plasma glucose concentration on admission (p<0.01), (2) the HbA(1c) level on admission (p<0.005), (3) the daily rate of plasma glucose reduction over the first 7 days of treatment (p<0.001), (4) the number of days required for hyperopia to reach its peak (p<0.001), and (5) the number of days required for the development and resolution of hyperopic changes (p<0.0001). There was a negative correlation between the maximum hyperopic change of an eye and baseline value of refraction (p<0.01). During transient hyperopia, no significant changes were observed in the radius of the anterior corneal curvature, axial length, lens thickness, or depth of anterior chamber. CONCLUSIONS: The degree of transient hyperopia associated with rapid correction of hyperglycaemia is highly dependent on the rate of reduction of the plasma glucose level. A reduction of refractive index in intraocular tissues, especially in lens, appears to be responsible for this hyperopic change.

Adult↗
PubMed2000

Human heart-type cytoplasmic fatty acid-binding protein (H-FABP) for the diagnosis of acute myocardial infarction. Clinical evaluation of H-FABP in comparison with myoglobin and creatine kinase isoenzyme MB.

Heart-type fatty acid-binding protein (H-FABP) is a low molecular weight cytoplasmic protein and present abundantly in the myocardium. When the myocardium is injured, as in the case of myocardial infarction, low molecular weight cytoplasmic proteins including H-FABP are released into the circulation and H-FABP is detectable in a blood sample. We have already developed a direct sandwich-ELISA for quantification of human H-FABP using two distinct types of monoclonal antibodies specific for human H-FABP. In this study we investigated the clinical validity of H-FABP as a biochemical diagnostic marker in the early phase of acute myocardial infarction (AMI). To evaluate the diagnostic usefulness of H-FABP in the early phase of AMI, blood samples were obtained from the following patients within 12 hours after the appearance of symptoms, and serum levels of H-FABP were compared with those of conventional diagnostic markers, such as myoglobin and creatine kinase isoenzyme MB (CK-MB). Blood samples were collected from patients with confirmed AMI (n=140), patients with chest pain who were afterwards not classified as AMI by normal CK-MB levels (non-AMI) (n=49) and normal healthy volunteers (n=75). The serum concentration of H-FABP was quantified with our direct sandwich-ELISA. The concentration of myoglobin mass was measured with a commercial RIA kit. The serum CK-MB activity was determined with an immuno-inhibition assay kit. The overall sensitivity of H-FABP, within 12 hours after the appearance of symptoms, was 92.9%, while it was 88.6% with myoglobin and 18.6% with CK-MB. The overall specificity of H-FABP was 67.3%, while it was 57.1% with myoglobin and 98.0% with CK-MB. The diagnostic efficacy rates with these markers were 86.2% (H-FABP), 80.4% (myoglobin) and 39.2% (CK-MB), respectively. The diagnostic validity of H-FABP was further assessed by receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) of H-FABP was 0.921, which was significantly greater than with myoglobin (AUC: 0.843) and CK-MB (AUC: 0.654). These parameters, such as sensitivity, specificity, diagnostic efficacy and diagnostic accuracy, obtained for patients with chest pain within 3 hours and/or 6 hours after the onset of symptoms were almost the same as those for patients within 12 hours after symptoms. H-FABP is more sensitive than both myoglobin and CK-MB, more specific than myoglobin for detecting AMI within 12 hours after the onset of symptoms, and shows the highest values for both diagnostic efficacy and ROC curve analysis. Thus, H-FABP has great potential as an excellent biochemical cardiac marker for the diagnosis of AMI in the early phase.

Aged↗
PubMed2000

The effect of modified ultrafiltration in pediatric open heart surgery.

Since 1997 we have performed modified ultrafiltration (MUF) in pediatric open heart operations. To elucidate the clinical effects of MUF, patients under 20 kg in weight who underwent corrective open heart operation since 1997 are divided into 2 cohorts according to the enforcement of MUF (control group versus MUF group) retrospectively. Procedures, age, bodyweight, cardiopulmonary bypass (CPB) time, operation time, amount of donor blood use, postoperative inotrope dose, postoperative intubation time, and postoperative gas exchange capacity of lung expressed with respiratory index (RI) were compared between groups. Furthermore, a multiple linear regression analysis was performed to find independent correlates with postoperative RI. Finally scattergrams of intubation time and RI were drawn against several factors. In univariate analyses, the MUF group had significantly shorter intubation time and better RI. Multivariate analysis revealed that the enforcement of MUF was an independent correlate of postoperative RI. Analyses on the scattergrams revealed that the above mentioned favorable effects of MUF were prominent in the patients younger than 3 years or weighing less than 10 kg. We concluded that MUF had significant effects on pulmonary function preservation in pediatric open heart operations, especially for smaller children.

Body Weight↗
PubMed2000

[A case of ascending aortic aneurysm with intrathoracic goiter].

A case of the successful operation for ascending aortic aneurysm and intrathoracic goiter was described. A 71-year-old woman was admitted to our hospital for the treatment of ascending aortic aneurysm disclosed by the examination in another hospital. Preoperative chest CT showed ascending aortic aneurysm as large as 8 cm in diameter, and an upper mediastinal tumor compressing the main bronchus. The tumor was continuous with the right lobe of the thyroid. The excision of the tumor was performed through median sternotomy with cervical collar incison. After that, the replacement of the ascending aorta was carried out under cardiopulmonary bypass and hypothermic circulatory arrest. The histological examination of the resected specimen revealed adenomatous goiter without malignancy.

Aged↗
PubMed2000

[A case of lateral origin of the left internal mammary artery].

A 66 years old men, with left anterior descending coronary artery (LAD) stenosis and aortic valve stenosis, underwent coronary artery bypass grafting (CABG) to LAD with left internal mammary artery (LIMA) and aortic valve replacement. His postoperative course was uneventful. But, postoperative angiogram showed that his patent LIMA graft was originated from much lateral side of the left subclavian artery. Internal mammary artery is considered the most ideal graft for CABG, but its' anomality is not well known. We present this rare case with the anomalous origin of LIMA.

Aged↗
PubMed1999

Analysis of postoperative complications after esophagectomy for esophageal cancer in patients receiving neoadjuvant therapy.

Postoperative complications were investigated in 72 patients who received neoadjuvant therapy with esophagectomy. Preoperative chemotherapy consisted of 5-fluorouracil (700 mg/m2/day, on days 1 to 5), cisplatinum (70 mg/m2/day, on day 1) and leucovorin (20 mg/m2/day, on days 1 to 5). Preoperative chemoradiotherapy consisted of cisplatinum combined chemotherapy and radiotherapy (total dosage of 30-70 Gy). The incidence of postoperative pneumonia (16%) and anastomotic leakage (24%) in the preoperative chemotherapy group was slightly higher than that in the control group (n = 506), and mortality (6.0%) after esophagectomy in the preoperative chemotherapy group was higher than that (2.4%) of the control group. Postoperative morbidity and mortality were observed more frequently in patients who received two cycles of the chemotherapy than those receiving only one cycle. Postoperative complications occurred more frequently in patients suffering high grade toxicities due to the preoperative chemotherapy. The highest preoperative serum creatinine value correlated to that of postoperative period (r = 0.6494). The use of the preoperative chemoradiotherapy with a total exposure dosage of 60 Gy or more significantly increased the postoperative pneumonia rate (67%; p < 0.05) compared to the group receiving 40 Gy or less. The mortality rate (33%) also increased. The second cycle of the preoperative chemotherapy should be cancelled if patients suffer high grade toxicities during or after the first cycle, and the total exposure dosage of the preoperative chemoradiotherapy should be limited to 40 Gy or less.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Physiological significance of hyperpolarization-activated inward currents (Ih) in smooth muscle cells from the circular layers of pregnant rat myometrium.

The properties of hyperpolarization-activated current in pregnant rat uterus (17-19 days gestation) were investigated using microelectrode and patch-clamp techniques, and isometric tension recording. The resting membrane potentials were -58.4 mV and -48.5 mV in longitudinal and circular muscle cells, respectively. Application of hyperpolarizing current pulses produced a time-dependent anomalous inward rectification of membrane potential only in circular muscle cells. Under voltage-clamp conditions, inward currents (Ih) were activated by long hyperpolarizing pulses below -60 mV in circular but not in longitudinal muscle cells. Application of extracellular but not intracellular Cs+ reduced the amplitude of I(h) in a concentration-dependent manner (an IC50( of 0.15 mM). The reversal potential for Ih was -26.2 mV and the slope conductance was 5 nS/pF. Changes in [K+]o and [Na+]o shifted the reversal potential, and Ih amplitude increased with excess [K+]o and decreased with low [Na+]o. The steady-state activation of Ih was well fitted by a Boltzmann equation with a half-activation potential of -84.3 mV and a slope factor of 9.6 mV. Time courses of activation and deactivation of the current strongly depended on membrane potential, and were well fitted by a single exponential function. The activation time constant of Ih was dependent on temperature. In isometric tension recording, application of extracellular Cs+ to the circular muscles reduced the frequency, but not the amplitude, of spontaneous contractions in a concentration-dependent manner. It is concluded that in pregnant rat uterus Ih channels are predominantly distributed in smooth muscle cells from the circular layer. Since Ih is activated at the resting membrane potential, it is likely that this current contributes to the maintenance of resting membrane potential and spontaneous activity in circular smooth muscle cells of late pregnant rats.

Algorithms↗
PubMed1999

Scintigraphic evidence for a specific long-chain fatty acid transporting system deficit and the genetic background in a patient with hypertrophic cardiomyopathy.

The mechanism of cardiac uptake of long-chain free fatty acids has not been fully determined. We encountered a hypertrophic cardiomyopathy patient who showed a lack of cardiac uptake of 2 different types of long-chain fatty acid analogues on the scintigraphic images. Flow cytometric analysis revealed no platelet or monocyte CD36 molecule expression (type I CD36 deficiency) and his CD36 gene showed homozygous mutation for 478C to T substitution, leading to an abnormal CD36 amino acid sequence. These findings strongly suggest that a specific transporting system rather than a simple diffusion is commonly involved in the cardiac uptake of long-chain free fatty acids in humans, and that the CD36 protein is the most likely candidate for the specific transporter and to explain scintigraphic defects on fatty acid imaging.

Adult↗