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Biomedical subjects

Y Ohkita

Publications and source records attributed to Y Ohkita.

At least 19 recordsLinked to original sources
PubMed2001

Estimation of an unexpected-overlooking error by means of the single eye fixation related potential analysis with wavelet transform filter.

An unexpected-overlooking error that caused failure to notice near the peripheral vision is one of the accident factors in driving behavior. We estimated how the unexpected-overlooking error affected the amplitude of the lambda wave in the eye fixation related potential (EFRP). Four subjects participated in the experiment. Each subject was required press the right or left switch according to the given task, which was that he/she pressed the right switch when the blue dot appeared in the right detected area or he/she pressed the left switch when the red dot appeared in the right. The single trial data from Pz, which referred to both earlobes, were analyzed by means of a wavelet transform (WT) filter. The difference of the lambda amplitude between the corrected data was applied for analysis of variance. Three subjects showed a significant effect (P<0.01 or P<0.05), and the remaining one subject did not show a significant consequence of only two errors. The unexpected-overlooking errors had a low amplitude compared to the mean of amplitude throughout the task. It was concluded that the amplitude of the lambda wave might reflect the attention level of a subject.

Algorithms↗
PubMed2001

Acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension.

OBJECTIVE: To assess acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension (CTEPH). DESIGN: Cardiopulmonary exercise testing was performed in 20 patients with CTEPH before thromboendarterectomy (baseline), one month after (early phase), and four months after (late phase). Peak oxygen uptake (peak VO(2)) and the ventilatory response to carbon dioxide production (VE-VCO(2) slope) were measured for assessment of exercise capacity and ventilatory efficiency. Right heart catheterisation was performed in all patients before and one month after surgery. RESULTS: Baseline peak VO(2) decreased and VE-VCO(2) slope increased along with the increase in pulmonary vascular resistance in patients with CTEPH. After thromboendarterectomy, the VE-VCO(2) slope decreased greatly from baseline to the early phase (mean (SD), 50 (9) to 37 (7), p < 0.05) and reached a steady level thereafter. In contrast, a continued increase in peak VO(2) was noted from the early to the late phase (16.9 (4.1) to 21.1 (5.0) ml/kg/min, p < 0.05). The decrease in the VE-VCO(2) slope from baseline to the early phase, but not the increase in peak VO(2), correlated strongly with the decrease in pulmonary vascular resistance after surgery (r = 0.75, p < 0.01). CONCLUSIONS: Thromboendarterectomy may cause an immediate improvement in ventilatory efficiency, possibly through its beneficial haemodynamic effects. In contrast, exercise capacity may continue to improve towards the late phase, reflecting peripheral adaptation to exercise.

Acute Disease↗
PubMed2000

Needlescopic surgery for palmar hyperhidrosis.

OBJECTIVE: The aim of this study was to develop a less invasive technique for video-assisted thoracic sympathectomy. METHODS: A newly designed trocar was used. A skin incision of 2.0 to 2.5 mm in length was made in the third or fourth intercostal space at the midaxillary line. After insertion of the trocar, thoracic sympathectomy with electrocautery was carried out at the level of the second and third ribs. RESULTS: From October 1998 to March 1999, 180 patients with palmar hyperhidrosis underwent this technique. No complications related to the technique occurred, and within 1 week the operative wound had almost completely disappeared. There were recurrences necessitating reapplication of the technique. CONCLUSION: The technique allowed healing without a scar and improved the patient's cosmesis.

Adolescent↗
PubMed1998

[Subsegmental transcatheter hepatic arterial embolization under balloon occlusion of the corresponding hepatic vein with SMANCS].

Recently, subsegmental transcatheter hepatic arterial embolization under balloon occlusion of the corresponding hepatic vein has been performed to treat hepatic infarction in subregion hepatocellular carcinoma (HCC). Here, we report subsegmental transcatheter hepatic arterial embolization under balloon occlusion of the corresponding hepatic vein with styrene maleic acid neocarzinostatin lipiodol (SMANCS) (SMANCS-TAE under balloon occlusion of the corresponding hepatic vein). This study included 9 patients with HCC who underwent SMANCS-TAE under balloon occlusion of the corresponding hepatic vein. In all patients, the therapeutic effects (TE) were evaluated according to the criteria of direct response to liver cancer treatment on abdominal computed tomography (CT) 3 weeks after surgery. In 7 patients who could be followed for more than one year, there was no postoperative relapse at the site of treatment. Furthermore, this procedure facilitated the detection of accumulation of SMANCS not only in the tumor but also in the subregion of the tumor in patients with HCC involving immature arterial tumor neoplastic vessels. In patients with large HCC complicated by severe heart failure showing a poor general condition, this procedure allowed treatment to be completed without complication. SMANCS-TAE under balloon occlusion of the corresponding hepatic vein, which can also embolize the portal vein by applying targeting chemotherapy with SMANCS, may cause necrosis not only in the tumor but also in noncancerous liver tissues. This procedure may be an indication for a larger number of cases than standard TAE, facilitating more complete local treatment.

Antineoplastic Agents↗
PubMed1996

[Review of results after surgery for pulmonary embolism].

The results of direct pulmonary embolectomy in 20 cases of pulmonary embolism treated in our facility from 1982 to May, 1995 was analyzed. The ages of the patients ranged from 25 to 72 years (mean: 46 years). The male-to-female ratio was 12:8. The 20 cases were divided into three groups based on the type of pulmonary embolism: Group I (4 cases of acute massive pulmonary thrombo-embolism). Group II (12 cases of chronic pulmonary thrombo-embolism) and Group III (4 cases of tumor embolism). In Group I, 2 patients developed shock and 2 developed severe right heart failure. Emergency thrombectomy using cardiopulmonary bypass succeeded in saving the lives of 3 patients in this group. In Group II, the preoperative NYHA grade was II in 1 case, III in 9 cases, and IV in 2 cases. The preoperative systolic pressure of the pulmonary artery ranged from 24 to 90 mmHg (mean: 74 mmHg). Surgery through a thoracotomy was carried out on 7 cases (on the right side in 4 cases on the left in 3 cases). Of these 7 patients, 2 died of heart failure and respiratory failure because thromboendarterectomy was inadequate. In another 2 patients, symptoms improved enough to allow them to resume their previous lives. The other three patients showed no change in their symptoms after surgery, but they could be discharged. The remaining 5 patients in Group II underwent surgery through the median approach. Deep hypothermia with circulatory arrest was used in the latter 4 of these 5 patients during surgery. 3 patients died during the perioperative period because adequate thromboendarterectomy was not possible and because their preoperative condition was very poor. 2 patients who were able to be performed adequate thromboendarterectomy showed good postoperative courses. Of the 4 patients in Group III, one patient survived 11 months after surgery, but the other 3 died during the preoperative period because very little embolus could be removed. These results allow us to conclude that the lives of patients with acute pulmonary thromboembolism can be saved by early detection and prompt surgery, but that management of chronic pulmonary thromboembolism involves difficulties in selecting surgical cases and in performing thromboendarterectomy.

Adult↗
PubMed1996

A 90-year old patient with atrial septal defect and sinus rhythm.

A 90-year old patient with an atrial septal defect (ASD) and sinus rhythm, but no history of atrial fibrillation of heart failure is presented. Literature searches revealed no similar report of such a case. In addition, this patient represents the oldest documented patients with ASD associated and sinus rhythm.

Age Factors↗
PubMed1995

Structural studies on the hexasaccharide alditols isolated from the carbohydrate-protein linkage region of dermatan sulfate proteoglycans of bovine aorta. Demonstration of iduronic acid-containing components.

Five major hexasaccharide alditols were isolated from the carbohydrate-protein linkage region of bovine aorta dermatan sulfate peptidoglycans after reductive beta-elimination and subsequent chondroitinase ABC digestion. These molecules account for at least 55.3% of the total linkage region. Their structures were analyzed by enzymatic digestion in conjunction with high performance liquid chromatography, electrospray ionization mass spectrometry, and 500-MHz one- and two-dimensional 1H NMR spectroscopy. Three of these compounds have the conventional hexasaccharide core; delta HexA alpha 1-3Gal-NAc beta 1-4GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl-ol. One is nonsulfated, and the other two are monosulfated on C6 or C4 of the GalNAc residue. They represent at least 6.3, 5.2, and 28.8% of the total linkage region, respectively. The other two compounds have the following hitherto unreported hexasaccharide core with an internal iduronic acid residue in common; delta HexA alpha 1-3GalNAc beta 1-4IdoA alpha 1-3Gal beta 1-3Gal beta 1-4Xyl-ol. One is monosulfated on C4 of the GalNAc, and the other is disulfated on C4 of the GalNAc and of the galactose residue substituted by the iduronic acid residue. These two compounds account for 35% of the five isolated hexasaccharide alditols and at least 4.3 and 10.7% of the total linkage region, respectively. The latter two structures form a striking contrast to the currently accepted conception that heparin, heparan sulfate, and chondroitin/dermatan sulfate share the common linkage tetrasaccharide core GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl. The biological significance of the isolated structures is discussed in relation to the biological functions and the biosynthetic mechanisms of dermatan sulfate.

Animals↗
PubMed1988

Mitral valve replacement with preservation of chordae tendineae and papillary muscles.

An operative technique for mitral valve replacement (MVR) with preservation of the chordae tendineae to the anterior leaflet as well as the posterior leaflet is reported. This technique consists of the division of the anterior leaflet into anterior and posterior segments, the shifting and reattachment of the divided segments to the mitral ring of the respective commissural areas, and the use of a low-profile bileaflet prosthetic valve. A comparison of left ventricular function data between patients having operation with this technique and those having operation with the conventional method of MVR revealed significantly better improvement in cardiac index (p less than 0.06), left ventricular end-systolic volume index (p less than 0.05), and left ventricular ejection fraction (p less than 0.10) in the former group. Left ventricular wall motion improved in the anterolateral (p less than 0.01) and apical areas (p less than 0.02) in patients operated on with our technique. Maintenance of continuity between the mitral annulus and papillary muscles is expected to have a beneficial effect on postoperative left ventricular performance in spite of increased afterload.

Adult↗
PubMed1988

Evaluation of corrective surgery for tetralogy of Fallot from late results by multivariate statistical analysis.

From 1966 to 1985, 469 pediatric patients with the tetralogy of Fallot (mean age, 4.9 years) were corrected (hospital mortality 11.9%). There were 9 late deaths (1.9%). In 186 patients, hemodynamic studies were performed 2-14 years postoperatively (mean age, 10.4 years). An increased cardiothoracic ratio (CTR) of 60% or more was found in 42 patients with impaired postoperative physical activity. The factors affecting the late results were investigated in relation to CTR by the quantification method of multivariate analysis. As for the enlarged CTR, pulmonary regurgitation was more of a contributing factor than pulmonary stenosis. In pulmonary regurgitation, the pulmonary artery area index (PAAI) and reconstruction of the right ventricular outflow tract (RVOT) were highly significant factors. For pressure gradient, the VSD site was the most significant factor. These analyses suggest that preservation and/or reconstruction of the pulmonary valve, or trans-annular patching with the necessary minimal area for the RVOT (PAAI) not to exceed 4 cm2/m2 at the time of operation is important for satisfactory late results.

Adolescent↗
PubMed1987

Usefulness of electromagnetic flowmetry in intraoperative evaluation of aortic regurgitation associated with ventricular septal defect.

In 38 patients with aortic regurgitation (AR) associated with ventricular septal defect (VSD), indications for aortic valvuloplasty (AVP) or aortic valve replacement (AVR) were investigated by assessing AR ratio, which was measured by electromagnetic flowmetry of the ascending aorta during the operation. Residual AR was evaluated by auscultation postoperatively. Patients were assigned to group A if they underwent VSD closure alone and to group B if they underwent AVP in addition to VSD closure; patients who had no postoperative AR were assigned to group I and those with persistence of AR to group II. Thus, the patients were separated into 4 subgroups; A-I (9 patients), A-II (5 patients), B-I (20 patients) and B-II (4 patients). In subgroup A-I, mean AR ratio decreased from 9% to 7% postoperatively, in A-II from 19% to 16% (p less than 0.1), in B-I from 36% to 9% (p less than 0.01) and in B-II from 44% to 20% (p less than 0.05). An AR ratio of more than 25% should be regarded as an absolute indication for AVP or AVR. If the AR ratio is between 20 and 25%, the indication of AVP is determined by inspection of the aortic valve. A good correlation was found between AR ratio and the AR rate determined by the aortic angiographic findings (Sellers classification): grade I AR corresponded to an AR ratio of 5 to 15%, grade II to 20 to 35%, grade III to 25 to 50% and grade IV to 45% or higher (r = 0.87, p less than 0.01).

Aortic Valve↗
PubMed1987

Optimal flow of aorta-pulmonary artery shunt in patients with cyanotic heart disease.

An aorta-pulmonary artery shunt with an expanded polytetrafluoroethylene (Gore-Tex) tube graft (3 to 6 mm in diameter) was done in 33 cyanotic patients with complex congenital heart disease. The patients ranged from 14 days to 22 years old. In 28, the shunt flow (QB) was measured, and the optimal QB and graft size were determined. Nine patients had severe heart failure because of an excessively large shunt. Seven of these patients died, 5 early and 2 late after operation. The QBS in these 9 patients were extremely high; the QB index and the ratio of shunt flow to systemic flow (QB/QS) were 3.86 +/- 0.91 L/min/m2 (mean +/- standard deviation) and 52.4 +/- 9.7%, respectively. The QB index and the QB/QS of patients without severe cardiac failure were 1.49 +/- 0.92 L/min/m2 and 27.2 +/- 11.4%, respectively. In conclusion, the QB index, the QB/QS, or both should be maintained in the range of 1.6 to 2.4 L/min/m2 and 30 to 40%, respectively. In infants, however, it is advisable to control the flow at less than the range just given. Analysis of graft size in relation to body weight (BW, in kilograms) and body surface area (BSA, in square meters) showed that the optimal diameter (D, in millimeters) could be calculated by the following formulas: D = 1.88 In(BW) + 1.8 (r = .86) D = 0.87 In(BSA) + 5.3 (r = .73).

Aorta, Thoracic↗
PubMed1987

[Quantitative evaluation of regional myocardial blood flow by digital subtraction angiography: correlations with exercise electrocardiography and Tl-201 myocardial scintigraphy].

We previously reported that the contrast disappearance half-life (T1/2) derived by the computerized washout analysis of digital subtraction coronary arteriograms provides a useful index for quantitatively evaluating regional myocardial blood flow. In the present study, we further evaluated the clinical usefulness of T1/2, comparing it with exercise electrocardiography and exercise thallium-201 myocardial scintigraphy. The study subjects consisted of 25 patients with angina pectoris and 14 patients with normal coronary arteries. Following the manual injection of contrast media into the left anterior descending coronary artery (LAD), a time-density curve was generated in the sectors of the myocardium which were perfused by the LAD and the T1/2 was calculated. T1/2 values correlated closely with double product (r = -0.73). They were significantly greater in patients with exercise-induced ST depression (8.3 +/- 1.0 vs 5.8 +/- 0.7, p less than 0.005). In addition, there was a good correlation between T1/2 values and washout ratio as determined by exercise thallium-201 myocardial scintigraphy, with r = -0.83. Although T1/2 values were within the normal range (mean +/- 2SD of control subjects) in all patients with LAD stenosis of 50 percent or less, these values were abnormally increased, exceeding the normal range, in 11 of the 12 patients with stenosis of 90 percent or more. Compared with exercise electrocardiography, T1/2 values were abnormally prolonged in 11 of the 13 patients with exercise-induced ST depression. Compared with exercise thallium-201 myocardial scintigraphy, T1/2 values were abnormally prolonged in seven of the nine patients with transient perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

[Videodensitometric assessment of right and left ventricular functions by digital subtraction angiography].

Right and left ventricular volumes and systolic indices were determined by intravenous digital subtraction ventriculography in 50 patients with various heart diseases. Using a constant injection speed of 35 ml Renografin-76 contrast medium, serial right and left ventriculograms were obtained in the 30 degree right anterior oblique projection. Right ventriculograms were also obtained in the 60 degree left anterior oblique projection. The videotape recordings of subtracted images were continuously digitized into 128 X 128 eight bit (256 gray scales) pixel matrices using an image-processing computer. The endocardial outlines of the right and left ventricles were drawn manually using a joystick, frame by frame, for each cardiac cycle. By integrating overall the pixel densitometric counts within this outline for each frame, the computer generated a time-density curve with maxima and minima represented in the end-diastolic and end-systolic frames, respectively. Systolic indices including ejection fraction (EF), one-third ejection fraction (1/3 EF) and the peak ejection rate (PER) were derived from the time-density curve. Right ventricular volume was determined by the single-plane or biplane mathematical formulae of Ferlinz et al., and left ventricular volume was calculated by the area-length method in the 30 degree right anterior oblique projection. Results by the two geometric methods correlated well for right ventricular volume (r = 0.84) and for EF (r = 0.80). Right ventricular densitometric counts correlated closely with single-plane volume (r = 0.91). Right ventricular ejection fraction (RVEF) determined by videodensitometry also correlated satisfactorily with that by single-plane angiography (r = 0.74).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗