Biomedical subjects

S Homma

Publications and source records attributed to S Homma.

At least 73 records · Page 4Linked to original sources

PubMed2000

Determination of left ventricular mass by real-time three-dimensional echocardiography: in vitro validation.

Twenty-one explanted fixed hearts (14 dogs and 7 pigs) were examined to validate newly developed real-time three-dimensional (RT3D) echocardiography for measurement of left ventricular (LV) mass in vitro and to compare its accuracy and variability with those of conventional echocardiographic measurements. There was an excellent correlation and high degree of agreement for the determination of LV mass between RT3D echocardiography and true mass measurement (r = 0.98; standard error of the estimate [SEE] = 7.3 g; absolute difference [AD] = 2.8 g; y = 1.00 x -4.0, interobserver variability; 5.0%). The conventional echocardiographic methods yielded weaker correlations, larger standard errors, and interobserver variability (area-length method: r = 0.90; SEE = 13.3 g; AD = 13.2 g; 13.3 % / truncated ellipsoid method: r = 0.91; SEE = 14.7 g; AD = 10.5 g; 7. 9% / M-mode: r = 0.91; SEE = 16.2 g; AD = 9.4 g; 15.3%). Determination of LV mass by RT3D echocardiography has a high degree of accuracy and is superior to conventional one- and two-dimensional echocardiographic methods.

Animals↗

PubMed2000

Aortic atheroma morphology and the risk of ischemic stroke in a multiethnic population.

BACKGROUND: Protruding atheromas in the aortic arch are an independent risk factor for ischemic stroke in the elderly. However, the role of atheroma morphologic characteristics (ulceration and mobility) has been less well characterized. Moreover, data have been obtained in predominantly white populations, and little is known about the association between atheromas and stroke in minorities. METHODS AND RESULTS: We performed transesophageal echocardiography in 152 elderly patients with stroke (58 white, 45 black, 49 Hispanic) and in 152 age- and race/ethnicity-matched control patients. Atheromas were classified as small (<4 mm in thickness), large noncomplex (> or =4 mm, no ulceration or mobility), and complex (ulcerated or mobile). Logistic regression analysis was performed to assess the risk of stroke associated with different definitions of atheroma in the overall group and in the race-ethnic strata after adjusting for the presence of other stroke risk factors. Complex atheromas were strongly associated with stroke in the overall group (22.4% in cases, 2.6% in control patients; adjusted odds ratio [OR] 17.1, 95% confidence intervals [CI] 5.1 to 57.3), whereas large noncomplex atheromas conferred a mildly increased stroke risk (22.4% vs 16.5%; adjusted OR 2.4, 95% CI 1.1 to 5.1). Complex atheromas also were strongly associated with stroke in whites (adjusted OR 24. 3, 95% CI 3.9 to 150.6) and Hispanics (adjusted OR 13.9, 95% CI 1.4 to 136). In blacks, complex atheromas were significantly more frequent in cases (15.6% vs 0%; P =.006), but their absence in control patients precluded the calculation of the OR. Complex atheromas were twice as frequent in white patients with stroke (32. 3%) than in black or Hispanic patients (15.6% and 16.3%, respectively; P =.05). CONCLUSIONS: Aortic atheroma complexity rather than size is strongly associated with ischemic stroke in the elderly. Complex atheromas are significantly associated with stroke in all 3 race-ethnic subgroups.

Black or African American↗

PubMed2000

Noninvasive assessment and necropsy validation of changes in left ventricular mass in ascending aortic banded mice.

Although left ventricular (LV) hypertrophy can be induced by aortic banding, noninvasive assessment of changes in LV mass in mice with a banded ascending aorta by using 2-dimensional (2D) images has not been previously performed. In this study we serially assessed changes in LV mass by 2D echocardiography with a newly available 12-MHz transducer in mice with a banded ascending aorta and validated measurements at necropsy. Estimated by echocardiography, LV mass increased from 74+/- 17 mg before banding to 191.08+/-54 mg at 8 weeks after banding (P <.0001), and excellent correlation was shown with postmortem measurements (r = 0.97). Furthermore, with the use of pulsed Doppler 2-dimensionally guided echocardiography, noninvasive measurement of flow velocities in the ascending aorta before and after the band at the various time points was possible. We propose that 2D echocardiography with a 12-MHz transducer is a powerful tool for serial noninvasive evaluations as an adjunct to the study of cardiac hypertrophy in the murine model.

Animals↗

PubMed2000

Real-time three-dimensional stress echocardiography: a Review of current applications.

Cardiovascular stress testing plays a crucial role in the initial detection of coronary artery disease. In exercise stress echocardiography, the rapid acquisition of echocardiographic images is critical for accuracy. Real-time three-dimensional echocardiography permits the rapid acquisition of a volumetric data set that includes the entire left ventricle and allows the review of multiple, standard two-dimensional images from a single volumetric data set. Volumetric data can be obtained using both apical and parasternal windows. Often, satisfactory images are obtained in the majority of both prestress and poststress imaging using only an apical volume set. The following is a review of the current applications of real-time three-dimensional echocardiography in stress testing.

Coronary Disease↗

PubMed2000

Oxygen supply-consumption balance in the thigh muscles during exhausting knee-extension exercise.

The purpose of this study was to investigate the difference in muscle oxygenation between the individual muscles involved in an exhaustive knee-extension exercise. Eight active women performed exercise by extending the knee joint from 90 degrees to 30 degrees (60 extensions min-1) at 20%, 30%, and 40% maximum voluntary contraction (MVC). Changes in oxy-(delta HbO2), deoxy-(delta Hb), and total (delta HbT) hemoglobin concentrations, and oxygen saturation (delta SO2NIRS = HbO2/HbT) in the vastus lateralis (VL) and rectus femoris (RF) muscles were measured with a spatially resolved near-infrared spectrometer (NIRS). The delta SO2NIRS in the VL and RF decreased rapidly from the pre-exercise control value (VL: 75.6 +/- 0.9%; RF: 81.6 +/- 1.6%) at the onset of exercise at three different intensities, although no significant difference in delta SO2NIRS was found between the two muscles at this time. However, the delta SO2NIRS decreased more rapidly thereafter and reached a lower value at exhaustion in the VL than in the RF. The difference in delta SO2NIRS between the VL (-10.3 +/- 1.7%) and RF (-4.0 +/- 1.0%) was significant (p < 0.05) when exercise intensity was 30% MVC. When the decreases in delta HbO2 and delta HbT (p < 0.05) were compared at different exercise intensities, the values at 30% and 40% MVC were significantly lower (delta HbO2: p < 0.01; delta HbT: p < 0.05) than those at 20% MVC in the VL, but there was no significant difference in any of the parameters in the RF, or in delta Hb in the VL. These results suggest that the muscle oxidative response to exhaustive knee-extension exercise differed between the VL and RF muscles. At exhaustion, oxygen saturation decreased to a lower level in the VL than in the RF, and an intensity-dependent difference in muscle oxygenation parameters was observed at 30% MVC in the VL but not in the RF muscles.

Adult↗

PubMed2000

Acute elevations of plasma asymmetric dimethylarginine and impaired endothelial function in response to a high-fat meal in patients with type 2 diabetes.

Asymmetric dimethylarginine (ADMA), a compound detectable in human plasma, is an endogenous inhibitor of NO synthase. Endothelial dysfunction is an early event in atherogenesis, and large-vessel atherosclerosis is a major cause of morbidity and mortality in patients with type 2 diabetes mellitus. Fifty patients with type 2 diabetes mellitus were studied at baseline and 5 hours after ingestion of a high-fat meal. Plasma ADMA measured by using high-performance liquid chromatography increased from 1.04+/-0.99 to 2.51+/-2.27 micromol/L (P:<0.0005). Brachial arterial vasodilation after reactive hyperemia, a NO-dependent function, measured by high-resolution ultrasound, decreased from 6.9+/-3.9% at baseline to 1.3+/-4.5% (P:<0.0001). These changes occurred in association with increased plasma levels of triglycerides and very low density lipoprotein triglycerides, with reduced low density lipoprotein cholesterol and high density lipoprotein cholesterol, and with no changes in total cholesterol. The increase in plasma ADMA in response to a high-fat meal was significantly and inversely related to the decrease in percent vasodilation. In 10 of the subjects studied with a similar protocol on another day, no significant changes in the brachial artery flow responses or in plasma ADMA were observed 5 hours after ingestion of a nonfat isocaloric meal. The data suggest that ADMA may contribute to abnormal blood flow responses and to atherogenesis in type 2 diabetics.

Adult↗

PubMed2000

Gender differences in the risk of ischemic stroke associated with aortic atheromas.

BACKGROUND AND PURPOSE: Atherosclerotic plaque of the proximal portion of the aorta is associated with an increased risk of ischemic stroke in the elderly. Different cutoffs of plaque thickness have been used in the literature for risk stratification and have been applied to both men and women. However, the assumption that the relationship between plaque thickness and stroke risk is the same in the 2 genders has not been proven. The aim of this study was to evaluate whether the prevalence of different degrees of aortic plaque thickness differed in men and women with ischemic stroke. METHODS: We performed transesophageal echocardiography in 152 patients aged >59 years with acute ischemic stroke (76 men and 76 women) and in 152 control subjects of similar age (70 men and 82 women). Odds ratios (ORs) for ischemic stroke with 95% CIs for different plaque thickness definitions were calculated for the overall group and separately for men and women by logistic regression analysis after adjusting for age, arterial hypertension, and hypercholesterolemia. RESULTS: Aortic plaques >/=4 mm were significantly more frequent in men than in women (31.5% versus 20.3%, respectively; P:=0.025) and were associated with ischemic stroke in both men (adjusted OR 6.0, CI 2.1 to 16.8) and women (adjusted OR 3. 2, CI 1.2 to 8.8). However, plaques 3 to 3.9 mm in thickness had a significant association with stroke in women (adjusted OR 4.8, CI 1. 7 to 15.0) but not in men (adjusted OR 0.8, CI 0.2 to 3.0). Plaques <3 mm were not associated with a significantly increased stroke risk for either sex. CONCLUSIONS: Smaller aortic plaques are significantly associated with ischemic stroke in women but not in men. If the increased prevalence of smaller plaques in women is confirmed to be associated with increased risk for embolic stroke, different cutoff points may have to be adopted in men and women for risk stratification and for decisions regarding medical intervention.

Aged↗

PubMed2000

Effects of trimebutine on intestinal motility after massive small bowel resection.

Effects of trimebutine maleate (TM) on intestinal motility in short bowel syndrome (SBS) were studied in conscious canines in both acute and chronic phases following 80% massive distal small bowel resection (MSBR). TM was administered orally to beagles with MSBR or as controls in the postprandial and fasting states, and given simultaneously with meals. Intestinal motility was measured using bipolar electrodes for approximately 1 month after the electrodes were implanted in each beagle and the data compared between treatment groups. When TM was given with meals, the postprandial period without duodenal migrating myoelectric (or motor) complexes (MMCs) was shorter than in those given meals only. When TM was given in the postprandial state in short bowel beagles, the initial duodenal MMCs occurred earlier, i.e. the postprandial period was shorter. Diarrhea did not occur in these beagles. When TM was given in the fasting state, duodenal MMCs occurred and propagated to the distal intestine. In conclusion, oral TM administration can produce a more appropriate intestinal condition for the next food intake and make enteral nutrition possible even in the acute phase after MSBR. Such feeding can be carried out without overloading gut function as a result of the modulation of gastrointestinal motility by TM.

Anastomosis, Surgical↗

PubMed2000

Effects of intestinal muscular wrapping on remnant intestinal motility after massive small bowel resection in conscious canines.

We searched the effect of the muscular valve on the management of short bowel syndrome. The motility of the remnant intestine with a special muscular valve after 80% massive distal small bowel resection (MSBR) was evaluated in conscious dogs. The valve (muscular ring) was made by the autointestinal muscle layer holding vascular pedicle. Interdigestive and postprandial bowel motility using bipolar electrodes and/or contractile strain gauge force transducers 2-4 weeks after the surgery, and data of this group (Group I) were compared to the motility in dogs after MSBR without valve construction (Group II) and in controls (Control). Results; Fasting duodenal migrating myoelectric (or motor) complexes (MMCs) in Group I occurred at longer intervals than in Control and almost similarly to those in Group II. MMCs arising from the duodenum were often interrupted before the jejunum above the valve and the anastomosis. The velocity of duodenal MMC propagation was slowed in every intestinal segment including that from the duodenum to the proximal jejunum, and to the jejunum above the anastomosis. Transit time in MSBR group (I and II) from the duodenum to the terminal ileum was extremely shorter than in Control, but there were no differences between in Groups I and II. The duration of the postprandial period without duodenal MMCs in Group I was significantly prolonged than in Control, but was shorter than that in Group II. The muscular valve was frequently activated, and the jejunum covered with the valve was contracted frequently which synchronized with the valve activity. It seemed the valve worked as sphincter. However, intestinal obstruction was not occurred through the jejunum covered by the valve. In conclusion, changes in gut motility after MSBR with the valve construction compensate for the shortened intestine and maintain the bowel content earlier postoperatively in comparison with the MSBR alone, and also contribute to the adaptive increase in the remnant intestinal absorption.

Animals↗

PubMed2000

[Evaluation of the activity and effects of combinations of various antibacterial agents against methicillin-resistant Staphylococcus aureus in vitro].

MICs of various antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA) were measured. Furthermore, we evaluated the effects of combinations of antibacterial agents against MRSA in vitro. In 24 cases out of 37, in which MRSA was isolated from inpatients, other microorganisms, such as Candida spp., Entrococcus spp., and Pseudomonas aeruginosa, were simultaneously isolated. From the results of minimum inhibitory concentrations (MICs), obtained from micro broth-dilution method, of various antibacterial agents against MRSA, range of MICs of arbekacin (ABK), vancomycin (VCM) and teicoplanin (TEIC) were < or = 0.25-4.0, 0.5-1.0 and 0.25-4.0 micrograms/ml respectively, and no strains of MRSA showed resistance to ABK, VCM and TEIC, so that we concluded that these three antibacterial agents were effective for MRSA infection. On the in vitro study of combination-effect of antibacterial agents, significant synergistic effects were achieved in the combination of VCM and flomoxef (FMOX) (Synergism rate was 97.3%) or VCM and imipenem (IPM) (Synergism rate was 97.2%). From the results that the fractional inhibitory concentration index in the combination of VCM with IPM was smaller than that with FMOX and that P. aeruginosa or Enterococcus spp. were simultaneously isolated in high frequency in the MRSA-isolated cases, we thought that the combination of VCM with IPM is more useful, because IPM is effective against P. aeruginosa but FMOX is not.

Aminoglycosides↗

PubMed2000

Microvascular blood is distributed more to venules than to arterioles in patients with Buerger's disease. Observation of bulbar conjunctiva by intravital microscope system.

BACKGROUND: It has been a matter of controversy whether abnormalities of organs other than extremities may be a clinical manifestation of Buerger's disease (thromboangiitis obliterans; TAO). In the present investigation, our aim was to quantitatively characterise the configuration of microvascular networks in bulbar conjunctiva, which is not affected apparently, in patients with thromboangiitis obliterans. METHODS: Nine men with thromboangiitis obliterans attended our hospital and nine male volunteers as normal controls were enrolled in this study. We observed and analysed the configuration of the network of a bulbar conjunctiva by use of intravital microscope system with computer assisted image processing functions. Microvessel density was defined as a summation of vessel length in a ROI area and tortuosity was evaluated by a ratio of vessel length to direct distance of both terminals. RESULTS: In the microcirculation of bulbar conjunctiva in thromboangiitis obliterans, arteriole diameter was significantly decreased and density of venules was significantly increased. Increased venular density was mainly explained by increased tortuosity of venules. CONCLUSIONS: Consequently, microvascular blood was distributed more to venules than to arterioles in patients with thromboangiitis obliterans. Venule/arteriole ratios of diameter, tortuosity and microvessel density may be useful parameters to characterize the configuration of microvascular networks in thromboangiitis obliterans.

Adult↗

PubMed2000

[A clinicopathological study of pulmonary cryptococcosis--chest CT and pathologic correlation].

We reviewed the clinicopathological features in 12 patients (7 males and 5 females; mean age 54 yr) with pulmonary cryptococcosis. Eleven of the patients were asymptomatic and the disease was detected by chest radiograph abnormalities. The underlying systemic disease had been diagnosed as diabetes mellitus in two. Chest CT scans showed a solitary nodule in 9 of the 12 patients, multiple nodules in 2, and infiltration in 1. The nodular diameter was less than 2 cm in 10 of the 12. All nodules were located in the subpleural region. On the chest CT, cavitary nodules, scattered nodules, or both, and spiculated nodules were difficult to distinguish from pulmonary tuberculosis and primary lung cancer, respectively. According to McDonnell's pathological classification of pulmonary cryptococcosis, the resected 8 lungs revealed peripheral pulmonary granuloma in 5 and granulomatous pneumonia in 3. It is important to perform a pathological examination for the diagnosis of pulmonary cryptococcosis to avoid misdiagnosis as lung cancer or pulmonary tuberculosis.

Adult↗

PubMed2000

A new current dipole tracing method from EEG which is very useful in research of human brain activity in the space station.

The space station is available from 2004 for scientific research including human physiology and medicine. In that instance, non-invasive research of human brain in the microgravity condition was highly required. The present newly developed dipole tracing method fits this research purpose, by determining current source in the brain from EEG activity. EEG is also very helpful to monitor the conditions of subjects in various hazard cases. We strongly recommend to use this apparatus in the space station.

Brain Mapping↗

PubMed1999

Modulation of early but not later stages of programmed cell death in embryonic avian spinal cord by sonic hedgehog.

Sonic hedgehog (Shh) is a secreted glycoprotein expressed by the notochord and floor plate that is involved in the induction and specification of ventral phenotypes in the vertebrate neural tube. Recently, Shh has also been shown to promote the survival of cultured rat embryo ventral brain and spinal cord cells. We have examined whether Shh can promote the survival of chick embryo neurons in vivo or in vitro. In the chick, Shh is expressed in notochord, floor plate, and ventral neural tube/spinal cord at several stages at which programmed cell death (PCD) occurs. However, the administration of exogenous Shh to embryos in vivo or to motoneuron cultures at these stages failed to promote the survival of several different neuronal populations, including spinal motoneurons, spinal interneurons, sympathetic preganglionic neurons, sensory neurons, and neuronal precursor cells. Rather, at the earliest stage of PCD examined here (embryonic day 3) Shh selectively induced the death of ventral neuronal precursors and floor-plate cells, resulting in a net loss of cells in the neural tube. Altered concentrations of Shh induce aberrant phenotypes that are removed by PCD. Accordingly, normal PCD in the early neural tube may play a role in dorsal-ventral patterning.

Animals↗

PubMed1999

Assessment of endothelium-mediated vasodilation of the peripheral circulation by transcutaneous ultrasonography and venous occlusion plethysmography.

Transcutaneous ultrasonography is a non-invasive technique with the ability to measure the volumetric blood flow of the peripheral circulation. Peripheral blood flow can be determined by high-resolution imaging of vessel diameter coupled with Doppler assessment of flow velocity. This method, however, has not been validated in vivo. Accordingly, brachial artery flow in response to intraarterial infusion of vasodilators was assessed by ultrasonography in 16 healthy subjects and compared to values obtained simultaneously by venous occlusion plethysmography. Blood flow calculated from ultrasound-derived vessel diameter and flow velocity was found to highly correlate with plethysmographic flow, with r values ranging from 0.83 to 0.99. Using this ultrasound technique combined with plethysmography, the response of conduit and resistance vessels to endothelium-mediated vasodilation was characterized. Doppler velocity rose dramatically with endothelium-dependent acetylcholine (970%), but only modestly with endothelium-independent vasodilators, nitroglycerin (292%) and nitroprusside (340%). Despite eliciting the greatest overall forearm flow response, acetylcholine resulted in a smaller increase in conduit diameter (15.4%) than nitroglycerin (21.8%), and only a comparable change than nitroprusside (14.6%). Taken together, these results suggest that acetylcholine acts predominantly on resistance vessels, whereas nitrovasodilators affect mainly conduit vessels. In summary, transcutaneous ultrasonography can be used reliably to assess flow changes in the peripheral circulation. Combined with plethysmography, this technique is useful for determining the relative contribution of conduit and resistance vessels to peripheral flow, particularly in the assessment of endothelium-mediated vasodilation.

Adult↗

PubMed1999

A randomized double-blind study of the effect of triiodothyronine on cardiac function and morbidity after coronary bypass surgery.

BACKGROUND: Although triiodothyronine deficiency has been described after cardiopulmonary bypass, data supporting its use have been conflicting. A double-blind, randomized, placebo-controlled study was undertaken to further define the effect of triiodothyronine on hemodynamics and outcome after coronary artery bypass grafting. METHODS: A total of 170 patients undergoing elective coronary artery bypass grafting were enrolled and completed the study from November 1996 through March 1998. On removal of the aortic crossclamp, patients were randomized to receive either intravenous triiodothyronine (0.4 microgram/kg bolus plus 0.1 microgram/kg infusion administered over a 6-hour period, n = 81) or placebo (n = 89). Outcome variables included hemodynamic profile and inotropic drug/pressor requirements at several time points (mean +/- standard error of the mean), perioperative morbidity (arrhythmia/ischemia/infarction), and mortality. RESULTS: Despite similar baseline characteristics, patients randomized to triiodothyronine had a higher cardiac index and lower inotropic requirements after the operation. Subjects receiving triiodothyronine demonstrated a significantly lower incidence of postoperative myocardial ischemia (4% vs 18%, P =.007) and pacemaker dependence (14% vs 25%, P =.013). Seven patients in the placebo group required postoperative mechanical assistance (intra-aortic balloon pump, n = 4; left ventricular assist device, n = 3), compared with none in the triiodothyronine group (P =.01). There were 2 deaths in the placebo group and no deaths in the triiodothyronine group. CONCLUSIONS: Parenteral triiodothyronine given after crossclamp removal during elective coronary artery bypass grafting significantly improved postoperative ventricular function, reduced the need for treatment with inotropic agents and mechanical devices, and decreased the incidence of myocardial ischemia. The incidence of atrial fibrillation was slightly decreased, and the need for postoperative pacemaker support was reduced.

Aged↗

PubMed1999

Immunological and molecular comparison of polyphenol oxidase in Rosaceae fruit trees.

An antibody raised against apple polyphenol oxidase (PPO) cross-reacted with PPOs from Japanese pear (Pyrus pyrifolia), pear (Pyrus communis), peach (Prunus persica), Chinese quince (Pseudocydonia sinensis) and Japanese loquat (Eriobotrya japonica). Core fragments (681 bp) of the corresponding PPO genes were amplified and characterized. The deduced protein sequences showed identities of 85.3 to 97.5%. Chlorogenic acid oxidase activity of these PPOs showed higher activities when assayed at pH 4 than at pH 6. These results indicate that PPOs in Rosaceae plants are structurally and enzymatically similar.

Amino Acid Sequence↗

PubMed1999

Feasibility of real-time 3-dimensional treadmill stress echocardiography.

Rapid acquisition of echocardiographic images is critical for the predictive accuracy of stress echocardiography. Real-time 3-dimensional echocardiography (RT3D) allows review of several standard 2-dimensional images from a single volumetric data set. To assess the feasibility of RT3D for treadmill stress echocardiography, we performed treadmill stress RT3D on 20 volunteers (10 men and 10 women; mean age 32 +/- 6 years) with a device that uses a matrix phased-array transducer in a 60-degree pyramidal volume. Images are displayed as 2 steerable, intersecting B-scan sectors with adjustable C-scan planes parallel to the transducer face. At pre-exercise and immediate postexercise assessment, the volumetric data were obtained from apical and parasternal windows, respectively. Left ventricular segments were divided into 16 standard segments according to criteria defined by the American Society of Echocardiography. The use of both volume sets resulted in visualization of 98% of the segments at peak exercise. Even with only an apical volume set, 89% of the segments were adequately visualized. Image optimization and acquisition time at peak exercise was 35 +/- 18 seconds from the apical window and 50 +/- 28 seconds from the parasternal window. This preliminary study indicates that RT3D treadmill stress echocardiography is feasible and may be an important application of this new 3-dimensional device.

Adult↗