Biomedical subjects

N Tanigawa

Publications and source records attributed to N Tanigawa.

At least 19 recordsLinked to original sources

PubMed1995

Optimal cycles of hepatic ischemia and reperfusion for intermittent pedicle clamping during liver surgery.

OBJECTIVES: To evaluate the intermittent clamping of hepatic vessels during liver surgery and to determine the optimal duration of ischemia and reperfusion. PARTICIPANTS: One hundred nine adult male Sprague-Dawley rats. METHODS: Partial (70%) ischemia of the rat liver was induced by clamping of the left pedicle. To assess the influence of a single period of ischemia, the rats were divided into three groups for 15, 20, or 30 minutes of ischemia. To evaluate the influence of reperfusion duration, reperfusion following 15-minute ischemia was repeated 10 times in three groups for 5, 10, or 15 minutes of reperfusion duration. Hepatic tissue blood flow (HTBF) and hepatic beta-adenosine triphosphate (beta-ATP) levels were measured serially, and histopathological specimens were studied following single episodes of ischemia. In the reperfusion experiments, hepatic enzyme levels, survival rates, HTBF, beta-ATP, and histopathological findings were analyzed. RESULTS: When the single period of ischemia was 15 minutes, HTBF and beta-ATP levels recovered after 1 hour of reperfusion. However, both HTBF and beta-ATP levels did not return to preischemic levels when the duration of the ischemia was 20 or 30 minutes. Levels of beta-ATP and HTBF were higher, with improvement in both the histopathological findings and the survival rate, when the duration of the repeated reperfusion periods was 15 minutes, compared with 5 or 10 minutes. CONCLUSIONS: The maximum period of ischemia without irreversible damage was 15 minutes in rat liver. The damage was less severe when the duration of the repeated reperfusion periods was 15 minutes rather than 5 or 10 minutes.

Adenosine Triphosphate↗

PubMed1995

Water jet angioplasty--an experimental study.

The usefulness and safety of water jet angioplasty was studied in vitro, using agar phantom and autopsied aorta, and in vivo in acute and chronic arterial occlusions in mongrel dogs. At an injection rate of 1.0 ml/s, the water jet produced erosion of the agar surface when the distance between the catheter and the agar was 1 mm. With an injection rate of 1.5 ml/s, erosion was produced at a distance of 15 mm from the catheter tip. When the water jet was directed at an arterial wall, intimal ablation and ruptured elastic fibers were found histopathologically. A smaller angle between the vascular wall and the catheter was associated with less vascular damage. In vivo, water jet angioplasty was effective against acute obstructions, but not against chronic obstructions. These results suggest that water jet angioplasty may be effective against arterial obstruction due to acute thrombus.

Agar↗

PubMed1995

[Establishment of signal-averaged electrocardiographic system and system specific criteria].

Signal-averaging of high resolution electrocardiographic data to identify ventricular late potentials, associated with ventricular tachycardia, has emerged as a useful technique for risk stratification following myocardial infarction. Multiple lead system, filters and criteria have been used in clinical trials. As variations in data analysis are introduced, it is important to assess the impact of the final results and to ensure that criteria for normalcy, appropriate for these variation, are developed if needed. This study compares the results produced by four systems and one system with a different filter used for determination of late potential parameters in the time domain. It is concluded that varying technique and filters significant changes in the values used to identify late potentials on high-resolution electrocardiographic records. These change may have clinical impact. When using this technique in a clinical situation, parameters values, appropriate for the device, and its components should be developed, if needed.

Arrhythmias, Cardiac↗

PubMed1995

[Comparison of parameters of ventricular late potentials by using four commercial high-resolution ECG systems].

The methodologic problems of non-invasive registration of ventricular late potentials (LP) were studied. Four commercially available high resolution ECG devices were used. Method A was MAC 1 from Marquette, Method B was MAC 12 (15) from Marquette. Method C was ART 101 PC from Arrhythmia Technology Research. Method D was Fukuda VCM3000 from Fukuda Denshi in Japan. Our study showed the good correlation of the filtered QRS duration (FQRSd) between method B (fast Fourier transform filter) and method C (bidirectional digital filter). However the poor correlation between method B, C (digital filter) and D (analogue filter) was obtained. When late potentials positive patients who had high frequency and low amplitude signals were compared, the worse correlation of FQRSd among method B, C and D was obtained. FQRSd in method B was longer than that in method C, and that in method D was longer than that in method B. The differences were statistically significant. The measurements of low amplitude signals [Root mean square voltage in last 40 msec (V40) and High Frequency and low amplitude signals duration under 40 microV (HFLAD)] in various methods were much difference. We concluded that the standardization of the filter and leads to evaluate the late potentials was needed. The system specific criteria to detect the sustained ventricular tachycardia have to be redefined in VCM 3000. It was important to evaluate visually LP, as LP far from QRS offset could not be registered with vector magnitude methods in individual cases.

Body Surface Potential Mapping↗

PubMed1995

[Physical properties of Strecker stents].

Strecker stent is a balloon-expandable metallic stent that is made of knitted tantalum wire mesh in order to Maintain flexibility. Therefore, the prosthesis is well suited to irregular and tortuous tube organs. We performed several physical experiments using 8 mm and 6 mm diameter stents made of 0.1 mm diameter wire filament. The bearing power of the 8 mm diameter stent against the circumferential compression pressure was divided into two groups, that is, 77-100% and under 66% of expansile rate. The capacity bearing the circumferential compression pressure of the latter group was greater than that of the former. Further, the bearing power of the 6 mm diameter stent was greater than that of the 56% expansile rate of the 8 mm diameter stent. The smaller the expansile rate of the stent, the smaller the minimum radius of curvature within the limits of the stent's plastic. To evaluate the suitability of the stent in clinical use, we made two projections on the inner surface of rubber tubes, and the stents were placed into the rubber tubes at different expansile rates. We evaluated the degree of contact of the stents against the rubber wall by taking soft X-ray photographs. The stents showed good suitability under the condition of incomplete expansion. For the above reasons, we concluded that, from the view-point of bearing power, the stent should be placed in the full expansile state. From the viewpoint of contact against the vessel wall, the stent should be placed in the incomplete expansile state.

Physical Phenomena↗

PubMed1992

[Experimental study of water jet angioplasty].

A newly invented angioplasty by using water jet energy was investigated for evaluating its safety and effectiveness in 3 dogs. The water jet was produced from a small tip nozzle (0.2 mm in diameter) of catheter by injecting 20 ml of diluted contrast medium. By using this method recanalization of femoral arterial occlusion produced by fresh thrombi was achieved in all 3 dogs. Post recanalization angiography showed no apparent small vessel occlusions. Injection apart more than 5 mm from the inner surface of human aorta provoked no apparent changes histopathologically. Water jet angioplasty may be useful in treating vascular occlusive disease.

Animals↗

PubMed1992

[Usefulness of dopamine administration after transcatheter hepatic arterial embolization based upon portal hemodynamics].

We evaluated usefulness of dopamine administration after transcatheter hepatic arterial embolization (TAE) for the prevention of hepatic failure in experimental and clinical study. In experimental study we measured portal blood flow in dogs with doppler catheter before and after TAE. Administration of dopamine after TAE increased portal blood flow significantly. In a clinical study the usefulness of dopamine was investigated in a clinical laboratory test. It revealed that serum GOT and GPT improved earlier with dopamine administration after TAE. In conclusion dopamine increased portal blood flow and decreased hepatic parenchymal damage after TAE.

Animals↗

PubMed1992

Chemosensitivity of head and neck cancer with the rapid thymidine incorporation assay and its clinical application.

The chemosensitivity of various head and neck cancers was investigated with the 5-day rapid thymidine incorporation assay in soft agar culture. The evaluability rate was 56%. Head and neck cancers were sensitive in vitro, in decreasing order, to peplomycin, cisplatin, bleomycin, 5-fluorouracil, mitomycin C, and doxorubicin. Primary tumors and neck metastases exhibited the same sensitivity, with 21% of all specimens tested responding. In vitro chemosensitivities were similar among patients younger than 69 years of age and those older than 70. The predictive accuracy for sensitivity tested prospectively in five cases was 80% and that for resistance in four was 75%.

Aged↗

PubMed1992

Detection of late potentials. Comparison of two commercial high-resolution ECG systems.

Signal-averaged electrocardiogram (SAECG) is used for detection of ventricular late potentials (LPs) in cardiac patients. As many commercial SAECG systems become available, it is essential to determine if they provide equivalent diagnostic information. Two high-resolution (Hi-Res) ECG systems (MAC-12, Marquette Electronics, Inc (MEI), Milwaukee, WI and LVP101, Arrhythmia Research Technology (ART), Austin, TX) were tested on 143 subjects (13 controls and 130 cardiac patients, 21 of whom were tested for inducible ventricular tachycardia [VT]). Late potential measurements (total QRS duration, high-frequency low-amplitude signal duration, and root-mean-square voltage) obtained from the two systems were in good agreement in most of the controls and patients. Application of Multicenter criteria for the MEI system and Gomes criteria for the ART system yielded very good agreement in LP diagnosis (at least 2 parameters abnormal). The two Hi-Res systems predicted inducible VT with good accuracy. The MEI system gave slightly higher sensitivity (90% vs 70%) and specificity (91% vs 82%) than the ART system in patients tested for inducible VT. In controls, both systems gave the same specificity (92%) and the LP diagnosis agreed in all controls (100%). Although the number of patients was small, neither sensitivity nor specificity were significantly different between the two systems at p < 0.05. To conclude, MEI and ART Hi-Res systems gave very similar LP diagnoses when appropriate criteria were applied.

Cardiac Pacing, Artificial↗

PubMed1992

In vitro growth ability and chemosensitivity of gastric and colorectal cancer cells assessed with the human tumour clonogenic assay and the thymidine incorporation assay.

A human tumour cloning assay (HTCA) has been performed on 191 samples of gastric and 152 samples of colorectal cancers, and a thymidine incorporation assay (TIA) on 178 samples of gastric and 109 samples of colorectal cancers. The rate of evaluable assays was significantly higher in the TIA than in the HTCA (P less than 0.01). In terms of in vitro growth potential in the two assays, gastric cancer cells were less active than the colorectal cancer cells (P less than 0.05). In frequency of in vitro sensitivity to drugs, gastric cancer was more chemosensitive than colorectal cancer in both assays. The in vitro/in vivo correlations of high resistance-predictive ratios and low sensitivity-predictive ratios were similar in both assays. The results indicate that the TIA is more applicable than the HTCA to screening of active agents against fresh gastrointestinal cancers.

Colorectal Neoplasms↗

PubMed1992

[Repeated arterial infusion chemotherapy for inoperable hepatocellular carcinoma using implantable drug delivery system].

We performed a clinical evaluation of repeated arterial infusion chemotherapy using an implantable drug delivery system for 41 patients with inoperable hepatocellular carcinoma (HCC). About half of our patients could not undergo transcatheter arterial embolization (TAE) because of extreme tumor extension and/or accompanying advanced cirrhosis. In most patients we implanted a 5 Fr. catheter non-surgically and connected it to an implanted injection port through a subcutaneous tunnel. The treatment schedule was weekly or biweekly intrahepatic one-shot administration of mitomycin C, adriamycin, 5-fluorouracil and epirubicin. The response rate (CR + PR) was 24.4%. The median survival period was 401.1 days. The 6 month, 1-year and 2-year survival rates were 73%, 48% and 24%, respectively. There were no severe side effects nor complications. The implantable drug delivery system will contribute not only to improved therapeutic efficacy for inoperable HCC but also improve the quality of life for patients.

Adult↗

PubMed1992

[The influence of atrioventricular asynchronous contraction on left and right ventricular performance].

To investigate the influence of atrioventricular asynchronous contraction on left and right ventricular performance, pulsed Doppler echocardiographic studies were performed in 10 patients who received permanent pacemaker (VVI mode), but without significant heart disease except for complete heart block. After setting the pacing rate at 40 per min, the performance was analyzed during the patient's own slow ventricular rate. Flow velocity patterns at the left (LVOT) and right ventricular outflow tracts (RVOT) were recorded by pulsed Doppler echocardiography, and ejection time (EjT), acceleration time (AcT), peak velocity (PV) and flow velocity integral (FVI), which is proportional to stroke volume, were measured for each outflow tract. When the patient's own atrial contraction occurred during ventricular systole, EjT, AcT, PV and FVI of flow at the LVOT and EjT, AcT and FVI of flow at the RVOT were decreased. Percent change of the FVI of flow at the RVOT (-34.6%) was significantly greater than that of flow at the LVOT (-16.2%, p < 0.01). These results indicate that the loss of right ventricular performance might play a prominent role in the genesis of the hemodynamic deterioration with atrioventricular asynchronous contraction.

Adult↗

PubMed1992

[Detection of ventricular late potentials comparison of 4 commercial high-resolution systems].

UNLABELLED: The purpose of this study was to evaluate the methodologic problems of noninvasive registration of ventricular late potentials. METHODS: we compared the results obtained in the same patients with four different systems which were Marquette MAC1, MAC12, ART LP101 and FUKUDA VCM 3000. Filtering was employed digital forward direction, 100-300 Hz in MAC1, digital FFT, 40-250 Hz in MAC12, digital, bidirectional, 40-250 Hz in ART and analogue, forward direction 40-300 Hz in FUKUDA VCM 3000. DEFINITION OF LATE POTENTIALS (LPs): Filtered QRS duration (FQRSD) was 120 msec or more, root mean square voltage in the last 40 msec (RMSV) was 15 microV or less in MAC12 and ART. FQRSD was 130 msec or more, RMSV was 15 microV or less in FUKUDA. FQRSD was 20 msec or more after QRS obtained from low resolution leads in MAC1. SUBJECTS: 163 patients [control 13, PVCs 23, myocardial infarction 55, others 51, IVCD (RBBB, LBBB, IVCD) 21] were included in this study. RESULTS: 17.6% of all patients (except for IVCD) showed LPs with MAC12, 20.0% with ART, 30.3% with FUKUDA, and 14.1% with MAC1. 23.1% of the control group showed LPs with MAC12 and FUKUDA, but no cases showed LPs with ART and FUKUDA. 4.3% of the PVC group showed LPs with MAC12, 13.0% with ART and FUKUDA, but no cases showed LPs with MAC1. 25.5% of the myocardial infarction group showed LPs with MAC12 and MAC1, 30.9% with ART and 36.3% with FUKUDA. All four methods gave corresponding results in 65.4% of patients, 7.0% positive and 58.4% negative findings. FQRSD of MAC12, ART and FUKUDA was 110.2 +/- 18.1 msec, 105.2 +/- 20.4 msec and 125.8 +/- 22.8 msec respectively. Correlation coefficient (r value) in FQRSD was 0.90 between ART and MAC12, 0.74 between ART and FUKUDA, and 0.75 between FUKUDA and MAC12. RMSV of MAC12, ART and FUKUDA was 49.2 +/- 30.2 microV, 43.7 +/- 37.8 microV and 22.5 +/- 10.6 microV respectively. R value in RMSV was 0.59 between ART and MAC12, 0.38 between ART and FUKUDA and 0.43 between FUKUDA and MAC12. R value in high frequency low amplitude signals duration under 40 microV of LPs positive patients in MAC1 was 0.51 between ART and MAC 12, 0.18 between MAC12 and MAC1, and 0.32 between ART and MAC1. Most of the differences result from a different interpretation of the tracings. Especially LPs far from QRS offset could be registered with neither MAC12, ART nor FUKUDA.

Action Potentials↗

PubMed1992

Application of expandable metallic stents to the venous system.

Expandable metallic stents were successfully introduced in 12 patients; 6 with superior vena cava (SVC) obstruction due to tumor invasion or lymph node metastases, 3 with inferior vena cava (IVC) obstruction or stenosis due to lymph node metastases or hepatic tumor, one with common iliac vein (CIV) obstruction due to lymph node metastases, one with idiopathic obstruction of the hepatic IVC and Budd-Chiari syndrome, and one with CIV obstruction following a dialysis shunt. The length of the lesions was between 2 and 15 cm. Multiple (2-7) stents in tandem were inserted percutaneously from a femoral venous approach through a 12 to 16 F (4.0-5.3 mm) Teflon sheath. Postoperatively, all 12 patients became free from symptoms such as SVC syndrome or IVC syndrome. In 11 patients, the symptoms did not recur during the follow-up periods of 1 to 21 months.

Adult↗

PubMed1991

[Clinical experience of expandable metallic stent placement for malignant biliary obstruction].

Expandable metallic stents of modified Gianturco design were used in nine cases of malignant biliary obstruction. Stents were placed through a percutaneous transhepatic approach without any severe complications. Initial patency was obtained seven of nine patients. Of these seven patients, recurrent jaundice was observed in three within four weeks. One patient had recurrent stenosis after four months due to ingrowth of the tumor. Although the expandable metallic stent offers several theoretical advantages over currently available stents, a disadvantage is that tumors may grow through the spaces between the legs of the wire or grow over the stent. We found that multi-modal treatment combined with radiation therapy was indispensable to maintain the patency of the stent in malignant biliary obstruction.

Aged↗

PubMed1991

[An animal experiment on arterial wall reaction to stents coated with gold, silver and copper].

Expandable metallic stents coated with gold, silver, and copper, and bare stainless steel stents were implanted into the abdominal aorta of eight dogs to determine their effect on the vessel wall. The animals were observed for two weeks. Abdominal angiograms were taken every week. The dogs were then killed for macroscopic and histopathological examination. The results were as follows. (1) The stents coated with gold and the noncoated stainless steel stents showed less histopathologic change than the other stents. (2) The stents coated with copper were associated with severe erosion of the vessel wall and marked thrombus formation.

Animals↗

PubMed1991

Significance of surgical adjuvant chemotherapy for gastric cancer.

One hundred and twenty-four specimens (72 primaries and 52 metastases) in 107 patients with gastric cancer were tested using the human tumor clonogenic assay (HTCA). Assays for 64 specimens (52%, 33 primaries and 31 metastases) were considered evaluable. The clonogenicity of the primaries was less than that of the metastases (P less than 0.01). In the primary specimens, well-differentiated tumors were more highly clonogenic than poorly differentiated or signet ring cell tumors (P less than 0.05). Viable malignant cells and clonogenic cells were abundant in the primary tumors with mucosal (m) and submucosal (sm) invasion, i.e., in early gastric cancers by Japanese criteria, and were reduced in numbers as the primary tumors advanced (P less than 0.05). In vitro chemosensitivity corresponded well to the clonogenicity of the primary tumors stratified by the degree of tumor invasion. At the early phase of primary tumor progression and metastasis, clonogenicity and chemosensitivity were high. Aggressive chemotherapy with sensitive drugs after surgery may improve the clinical results for the gastric cancer patients with early phase of metastases.

Adenocarcinoma↗

PubMed1991

Proliferative activity of human tumors: assessment using bromodeoxyuridine and flow cytometry.

Cell kinetics of human carcinoma xenografts and human solid tumors were evaluated by means of two-color flow cytometry using single sampling at appropriate time intervals after bromodeoxyuridine (BrdU) labeling. The tumors were resected several hours after the administration of BrdU, and flow cytometry was used to measure the DNA content and BrdU incorporation. Once the BrdU labeling index (LI) and DNA synthesis time (Ts) were obtained, the potential doubling time (Tpot) was calculated from these values. In 11 xenografts, the cell kinetic data were compared with the actual tumor doubling time (Td), and a good correlation between Tpot and Td was obtained (r = 0.91, P less than 0.005). In a clinical study, 33 patients with gastric cancer, colorectal cancer, lung cancer, or other solid tumors were analyzed. Aneuploid tumors had a significantly higher LI value (P less than 0.01) and a shorter Tpot than diploid tumors. The cell loss rate of human tumors ranged from 40% to 80%. These cell kinetic parameters therefore accurately indicated the level of proliferative activity of human tumors.

Animals↗