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Biomedical subjects

T Takano

Publications and source records attributed to T Takano.

At least 181 records · Page 10Linked to original sources
PubMed1999

A new control method that estimates the backflow in a centrifugal pump.

The rotary blood pump will be widely used in the near future as an implantable left ventricular assist device (LVAD). However, one obstacle for the centrifugal pump is a control method that can maintain an optimum flow rate in a physiological condition. Thus, the object of this study is to develop this optimum control system for the centrifugal pump. If the heart function and pump efficiency are stable, the ratio of the systole current to the the diastole current (S/D) will be a fixed value. However, if the heart function and pump efficiency are unstable, S/D will not be a fixed value. This control system was investigated with a calf that was subjected to an ex vivo LVAD study. The LVAD was a Gyro C1E3 centrifugal pump. The pump flow rate was changed to 1.5, 3.5, 5.2, and 6.2 L/min. According to the changes of the pump flow rates, the S/D values were 1.01 +/- 0.01, 1.06 +/- 0.05, 1.03 +/- 0.01, and 1.03 +/- 0.01, respectively. There was no statistical difference among the 3 groups. In a separate experiment, the backflow condition S/D was 1.88 +/- 0.6, and the normal condition S/D was 1.35 +/- 0.5. There was a statistical difference between the 2 groups. The results of this study suggest that S/D is not influenced by the pump flow rate. However, the S/D was changed when the pump was in a backflow condition. This method will be useful in controlling a centrifugal pump requiring only electrical current information.

Analysis of Variance↗
PubMed1999

An emergency balloon occlusion system for a rotary blood pump left ventricular assist system.

A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary blood pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute pump failure. To solve this problem, a passive mechanical clamping system at the outflow graft of a rotary blood pump was developed together with Fuji Systems, Inc., Yokohama, Japan. The system consisted of an emergency clamp port and an occlusion balloon. The balloon was fixed around the outlet graft of the LVAS. In an in vitro study, a fail-safe clamping operation with 2 ml saline injection under 7 L/min flow against 140 mm Hg pressure reduced the flow to 0.5 L/min while the pressure in the system increased to 190 mm Hg. The systems were also applied to 2 in vivo LVAD studies. When the pumps were stopped, there were approximately 3.0 L/min regurgitant flows. The balloon occluder prevented this regurgitant flow effectively against a 100/80 mm Hg arterial pressure. In conclusion, this emergency balloon occlusion system is relatively easy to operate and will work efficiently in all possible clinically encountered malfunctions of the rotary blood pump LVAS.

Animals↗
PubMed1999

Feasibility of a tiny Gyro centrifugal pump as an implantable ventricular assist device.

The Gyro pumps were developed for long-term circulatory support. The first generation Gyro pump (C1E3) achieved 1 month paracorporeal circulatory support in chronic animal experiments; the second generation (PI702) implantable ventricular assist device (VAD) was successful for over 6 months. The objective of the next generation Gyro pump is for use as a long-term totally implantable VAD and for pediatric circulatory support. This tiny Gyro pump (KP101) was fabricated with the same design concept as the other Gyro pumps. The possibility of an implantable VAD was determined after performance and hemolysis test results were compared to those of the other Gyro pumps. The pump housing and impeller were fabricated from polycarbonate with an impeller diameter of 35 mm. The diameter and height of the pump housings are 52.3 mm and 29.9 mm, respectively. At this time, a DC brushless motor drives the KP101, which is the same as that for the C1E3. The pump performance was measured in 37% glycerin water at 37 degrees C. Hemolysis tests were performed utilizing a compact mock loop filled with fresh bovine blood in a left ventricular assist device (LVAD) condition at 37 degrees C. The KP101 achieved the LVAD conditions of 5 L/min and 100 mm Hg at 2,900 rpm; generated 10 L/min against 100 mm Hg at 3,200 rpm; 3 L/min against 90 mm Hg at 2,600 rpm; and 2 L/min against 80 mm Hg at 2,400 rpm. In addition, the pump efficiency during this experiment was 12.5%. The other Gyro pumps. that is, the C1E3, PI601, and PI701, in an LVAD condition require 1,600, 2,000, and 2,000 rpm, respectively. The KP101 produced a normalized index of hemolysis (NIH) value of 0.005 g/100 L. With regard to the NIH, the other Gyro pumps, namely the C1E3, PI601, and PI701 demonstrated 0.0007, 0.0028, and 0.004 g/100 L, respectively. The KP101 produced an acceptable pressure flow curve for a VAD. The NIH value was higher than that of other Gyro pumps, but is in an acceptable range.

Equipment Design↗
PubMed1999

Measurement of the expression of oncofetal fibronectin mRNA in thyroid carcinomas by competitive reverse transcription-polymerase chain reaction.

Abundant expression of oncofetal fibronectin mRNA has been observed in thyroid papillary and anaplastic carcinomas. In this study, we measured relative expression levels of oncofetal fibronectin mRNA in thyroid cancer tissues by competitive reverse transcription polymerase chain reaction (RT-PCR) using thyroglobulin mRNA as an internal control. By this method, all papillary and anaplastic carcinomas and 3 of 6 follicular carcinomas were distinguished from benign tissues, such as normal thyroid tissues, follicular adenomas, and adenomatous goiters. Furthermore, 2 anaplastic carcinomas were clearly distinguished from differentiated carcinomas. These results suggest the possibility of establishing a more accurate preoperative or postoperative diagnosis of papillary and anaplastic carcinomas by measuring the relative expression level of oncofetal fibronectin to thyroglobulin in thyroid tumors.

Adenoma↗
PubMed1999

Metabolism of oxidized phosphatidylcholines formed in oxidized low density lipoprotein by lecithin-cholesterol acyltransferase.

The possible involvement of lecithin-cholesterol acyltransferase (LCAT) in the metabolism of oxidized phosphatidylcholine (PC) in plasma was investigated. A variety of oxidized products are formed from PC following oxidation of low density lipoproteins (LDL). A significant increase in LDL oxidation levels in patients with familial LCAT deficiency (FLD) has been previously demonstrated by a sensitive sandwich ELISA for oxidized LDL using the monoclonal antibody DLH3 which recognizes oxidized products of PC. In the present study, we found that LCAT produces various metabolites from oxidized PC and that oxidized PC molecules in LDL particles serve as substrates. When the neutral lipid fraction was separated by TLC after the incubation of oxidized 1-palmitoyl-2-[1-14C]linoleoyl PC with human plasma, a number of radioactive bands were formed in addition to cholesteryl ester. These products were not formed from native 1-palmitoyl-2-[1-14C]linoleoyl PC. Plasma from FLD patients also failed to form the additional products from oxidized PC. The addition of dithio-bis(nitrobenzoate) (DTNB), an LCAT inhibitor, or the inactivation of LCAT activity by treating the plasma at 56 degrees C for 30 min abolished the generation of these products from oxidized PC. The activity was recovered in the high density lipoprotein (HDL) fraction but not in the LDL fraction separated from normal plasma. When 1-palmitoyl-2-[1-14C](9-oxononanoyl) PC and 1-stearoyl-2-[1-14C](5-oxovaleroyl)PC, PC oxidation products that contain short chain aldehydes, were incubated with human plasma, radioactive products in the neutral lipid fraction were observed on TLC. LDL containing oxidized PC was measured by sandwich ELISA using an anti-apolipoprotein B antibody and DLH3. The reconstituted oxidized PC-LDL particles were found to have lost their ability to bind DLH3 upon incubation with HDL, while the reactivity of the reconstituted oxidized PC-LDL remained unchanged in the presence of DTNB. These results suggest that LCAT is capable of metabolizing a variety of oxidized products of PC and preventing the accumulation of oxidized PC in circulating LDL particles.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1999

The effectiveness of videophones in home healthcare for the elderly.

OBJECTIVES: This study evaluates the effectiveness of telecare, the use of videophones in healthcare for the elderly in communities, and proposes an effective application of telecare in home healthcare. METHODS: An intervention study design was applied to evaluate the add-on benefits to home healthcare from a videophone system using Integrated Services Digital Network (ISDN) installed in individual homes of clients and service providers. An intervention group of home healthcare cases were provided with videophones (VHHC group), and it was compared to a reference group of regular healthcare cases (HHC group). Persons from the 2 groups were individually matched according to sex, age, and their independence in activities of daily living. The functional independence of the individuals in the 2 groups was assessed before and 3 months after home healthcare was started, with and without videophones. The effectiveness of videophones was assessed by analyzing the improvements in functional independence using a paired t test. RESULTS: Improvements in functional independence of 5 pairs of males and 11 pairs of females were analyzed. Improvements in ADL, communication, and social cognition independence of the VHHC group over the 3-month trial period measured by the Functional Independence Measure were 1.5 points, 0.7 points, and 1.9 points, respectively; statistically, these were significantly greater than those of the HHC group (individually P < 0.05). CONCLUSIONS: The effectiveness of the videophones in home healthcare service was found to be significant. This evidence supports the use of videophones in home healthcare to improve the quality of service.

Activities of Daily Living↗
PubMed1999

Preoperative diagnosis of medullary thyroid carcinoma by RT-PCR using RNA extracted from leftover cells within a needle used for fine needle aspiration biopsy.

Fine needle aspiration Biopsy (FNAB) is commonly used to diagnose thyroid tumors. In some clinical situations, however, accurate diagnosis requires a more objective method than cytological examination alone. Medullary thyroid carcinomas (MTC) derive from C cells in the thyroid and express some specific messenger RNAs (mRNA), such as those transcribed from the RET proto-oncogene, the calcitonin gene, and the gene for carcinoembryonic antigen (CEA), which usually do not exist in normal thyroid follicular cells or thyroid tumors of follicular epithelial descent. Recently, we established a new method for the molecular diagnosis of thyroid tumors without additional invasion to the patient by extracting RNA for RT-PCR from the leftover cells inside the needles used for fine needle aspiration biopsy (Aspiration Biopsy-Reverse Transcription-Polymerase Chain Reaction, ABRP). By applying the ABRP method to the detection of RET, calcitonin, and CEA mRNAs, an accurate molecular-based diagnosis for MTC maybe established as an adjunct to cytological diagnosis. In this study, 35 aspirates were obtained at the time of surgery from thyroid tumors, including 11 MTCs. The expression of these mRNAs in the leftover cells inside the needles used for the aspiration was then examined. Transcripts from all three genes were detected in the samples from all 11 MTCs, but none of these mRNAs were detected in the other tumors or normal thyroid tissues. Furthermore, MTC was preoperatively diagnosed in three patients by ABRP detection of these mRNAs, and these diagnoses were confirmed by subsequent cytological and histopathological analyses. Thus RT-PCR detection of RET, calcitonin, and CEA mRNAs in FNABs may be an efficient molecular adjunct for diagnosing MTC.

Adult↗
PubMed1999

Incidence and clinical significance of junctional rhythm remaining after termination of radiofrequency current delivery in patients with atrioventricular nodal reentrant tachycardia.

The aim of this study was to elucidate the electrophysiologic characteristics and clinical significance of the accelerated junctional rhythm (JR) that remains after termination of radiofrequency (RF) current delivery during catheter ablation (CA) for atrioventricular nodal reentrant tachycardia (AVNRT). Fifty consecutive patients with AVNRT (21M, 29F, age 48 years) underwent RF-CA targeting the slow pathway. JR occurred at 124 out of a total of 236 ablation sites (53%) during the RF delivery. With 15 RF deliveries (6.4%, n=10), JR remained after termination of the RF delivery (Post-JR). The mean cycle length of the Post-JR immediately after termination of the RF delivery was 639+/-124 ms and its duration was widely distributed from 3 s to more than 1 h. The Post-JR exhibited a spontaneous rate deceleration and overdrive suppression by rapid atrial pacing. The JR during the RF delivery followed by Post-JR had a greater time span in which the JR appeared, compared with that without Post-JR. The Post-JR had less sensitivity(18 vs 96%), but greater specificity (97 vs 59%) and a positive predictive value (60 vs 39%) in predicting successful ablation compared with JR seen only during the RF delivery. It is concluded that the presence of Post-JR might be a reflection of the intense effect of RF energy on the nodal or peri-nodal tissue.

Adolescent↗
PubMed1999

Correlation between atrial natriuretic peptide and baroreflex sensitivity in patients with congestive heart failure.

The aim of this study was to investigate the relationship between baroreflex sensitivity (BRS) and humoral factors in patients with congestive heart failure (CHF). BRS was assessed by the phenylephrine method in 16 patients with CHF and in 13 healthy controls. The CHF group was subdivided into 2 groups according to BRS (group A: <6 ms/mmHg, n=9; group B: > or =6 ms/mmHg, n=7). BRS was markedly depressed in CHF than in the controls (4.8+/-2.0 vs 8.3+/-3.6 ms/mmHg, p<0.01), and lower in group A than group B (3.3+/-1.3 vs 6.7+/-0.6 ms/mmHg, p<0.01). The plasma human atrial natriuretic peptide (h-ANP) level in group A was significantly higher than in group B (54.6+/-27.6 vs 18.0+/-7.4 pg/ml, p<0.01), and a significant inverse correlation was observed between plasma h-ANP and BRS (r=-0.635, p<0.01). However, there were no significant differences between the 2 groups in plasma catecholamine concentration, plasma renin activity and cardiac function by echocardiogram. These findings suggest that the elevation of endogenous ANP may also serve to compensate for impaired BRS in patients with CHF, in addition to its principal actions, such as diuresis and vasodilation.

Aged↗
PubMed1999

Screening of specific changes in mRNAs in thyroid tumors by sequence specific differential display: decreased expression of c-fos mRNA in papillary carcinoma.

To examine the specific changes in gene expression in thyroid carcinomas, we performed sequence specific-differential display (SS-DD) analysis by using a specific degenerate primer for the superfamily of the small G protein. After subcloning and sequencing analysis, one of the genes that showed decreased expression in thyroid papillary carcinomas was revealed to be the proto-oncogene c-fos. Expression of c-fos mRNA in benign and malignant tissues was examined by reverse transcription-polymerase chain reaction (RT-PCR) and Northern blotting. The expression of c-fos was detected in all twelve normal thyroid tissues, whereas it decreased in thirteen of fifteen papillary carcinomas. These results indicate that the increased expression of c-fos mRNA is not necessarily to be an oncogenic feature of thyroid tumors. Further, its constant expression in normal thyroid tissues may play a role in the maintenance of thyroid function.

Adenoma↗
PubMed1999

Lipoxin and aspirin-triggered 15-epi-lipoxin cellular interactions anti-inflammatory lipid mediators.

Eicosanoids are known to play important roles in inflammation. Recent findings have given rise to several new concepts regulating the generation of eicosanoids, illustrated in Figure 1. Lipoxins (LX) are trihydroxytetraene-containing eicosanoids that are generated within vascular lumen by platelet-leukocyte interactions and at mucosal surfaces by leukocyte-epithelial cell interactions. During these cell-cell interactions, transcellular biosynthetic pathways are used as major routes, and thus, in humans, LX are formed in vivo during multicellular responses such as inflammation, atherosclerosis, and thrombosis. This branch of the eicosanoid cascade generates specific tetraene-containing products that appear to function as stop signals, since they inhibit key steps in leukocyte-mediated inflammation. Of special interest, it appears that aspirin also functions in part via production of novel epimers of lipoxins or 15-epi-lipoxins (Figure 1). Here, we review recent developments on the cellular interactions of these novel anti-inflammatory mediators.

Amino Acid Sequence↗
PubMed1999

Purification and characterization of an antihypertensive peptide from a yogurt-like product fermented by Lactobacillus helveticus CPN4.

Whey peptides in a yogurt-like product fermented by Lactobacillus helveticus CPN4 were fractionated by a Sep-pak C-18 cartridge followed by two-step reverse-phase HPLC. The antihypertensive activity was measured by systolic blood pressure in spontaneously hypertensive rats after oral administration of each fraction. Five major peptides in the final fraction were further purified by reverse-phase HPLC and were measured for these antihypertensive activities in spontaneously hypertensive rats. The only peptide in the final fraction that showed strong antihypertensive activity had a sequence of Tyr-Pro, which is found in alpha s1-casein (CN), beta-CN, and kappa-CN. The synthetic peptide Tyr-Pro yielded significant antihypertensive activity from 2 to 8 h after oral administration of 1 mg of peptide/kg of body weight, and the effect was maximal at 6 h after oral administration. The antihypertensive effect of the peptide was dependent on the peptide dosage from 0.1 to 10 mg of peptide/kg of body weight. The concentration of Tyr-Pro peptide increased during fermentation and reached about 8.1 micrograms/ml of whey in the pH 4.3 yogurt-like product. The antihypertensive peptide had a low inhibitory activity against angiotensin I-converting enzyme. The inhibition of 50% of the angiotensin I-converting enzyme (IC50) was 720 microM.

Administration, Oral↗
PubMed1999

Oral administration of cholic acid promotes growth of liver tumors initiated by diethylnitrosamine in rats.

The effect of dietary administration of cholic acid on tumorigenesis in the liver was investigated in male Fischer-344 rats after carcinogenic initiation by diethylnitrosamine (DEN); progression of liver tumors was examined in the rats fed 0.4% cholic acid-containing diet (CA group) and the rats fed standard diet (C group) at 15, 20 and 25 weeks after administration of DEN. The total bile acids and cholic acid in serum of CA group were 150 nmol/ml and 117 nmol/ml, being 31-fold and 51-fold higher than those in C group (p<0.0001, each). Serum AST and ALT were significantly higher in CA group than in C group at 15 weeks (p<0.01). Serum ALP was significantly higher in CA group than C group at each time point (p<0.01, each). Liver tumors, whose histology was hepatocellular carcinoma, developed at 15 weeks in both CA and C groups. However, tumor volume and tumor weight were significantly increased in CA group, compared to those in C group at each time point (p<0.001, p<0. 001, p<0.01, p<0.001, p<0.01 and p<0.05). The percentage of apoptotic cells in CA group at each time point was significantly lower than C group (p<0.05, p<0.01 and p<0.05). The percentage of bcl-2 positive tumor cells in C group at 20 weeks was 1.88+/-2.59%. However, it dramatically increased to 34.00+/-13.67% in CA group (p<0.0001). It was also higher in CA group than in C group at 15 and 25 weeks (p<0.05 and p<0.01). In addition, the bax-positive cells were higher in CA group than in C group at 20 weeks (p<0.05). These data suggest that oral administration of cholic acid promotes liver tumorigenesis initiated by DEN through reducing apoptosis mediated by overexpression of bcl-2.

Administration, Oral↗
PubMed1999

[Survey of infective endocarditis in the last 10 years: analysis of clinical, microbiological and therapeutic features].

Infective endocarditis still presents problems with early diagnosis, selection of antibiotics and timing of surgical procedure despite modern antibiotics and investigative procedures. A retrospective study was performed to clarify the clinical and microbiological spectrum of recent infective endocarditis in the Japanese population in 38 patients with infective endocarditis (mean age 42.7 +/- 12.5 years) treated from March 1986 to March 1996. The portal of entry to bacteremia was unknown in most cases (57.9%), but the commonest identified portal was dental procedure (18.4%). Overall, the aortic valve was infected most frequently (44.7%) and followed by the mitral valve (36.8%). The most common complication of infective endocarditis were emboli (11/38, 28.9%) and congestive heart failure, NYHA class III and IV (14/38, 36.8%). Organisms were isolated from 26 of the 38 (68.4%) patients. Streptococcus viridans was the most frequent organism (34.2%), and then Staphylococcus aureus (13.2%). The blood culture positivity of microorganism was significantly higher in patients not receiving antibiotics than in those the received antibiotics (87.5% vs 50%, p < 0.05). The prevalence of streptococcal endocarditis decreased in the 1990s (1992-1996) in comparison with those in the 1980s (1986-1988). Multiple antibiotics were used frequently in 1990s and the sensitivity titer to piperacillin reduced from 3.0 in the 1980s to 1.8 in the 1990s. In contrast to reduction of streptococcal endocarditis, Staphylococcus aureus endocarditis has increased recently from 12.5% to 30.8%. The most common clinical features are valve destruction, low sensitivity of penicillin, and significantly higher in-hospital mortality. Surgical treatment was indicated most commonly in cases of uncontrollable heart failure, and infected valves were replaced during the active stage in 11/23 cases (47.8%). In-hospital mortality was higher in the medical treatment group than in the surgical group, but a long-term mortality of mean observation term 4.2 +/- 3.2 years was identical in the chronic phase. In patients with infective endocarditis and successful treatment in the acute stage, a long-term survival rate in medically treated patients was found almost comparable to surgically treated patients in our series. However, it should be emphasized that streptococcal endocarditis is being replaced by infection by Staphylococcus aureus, which is resistant to penicillin and requires intensive chemotherapy and proper decision at suitable timing for surgical therapy in the early stage.

Adult↗
PubMed1999

Left coronary artery-left ventricular fistula with acute myocardial infarction, representing the coronary steal phenomenon: a case report.

A 59-year-old man presented with a left anterior descending coronary artery to left ventricular fistula manifesting as myocardial infarction, representing the coronary steal phenomenon. Electrocardiography showed poor R progression in leads V1 through V3. The biochemical markers of myocardial injury were elevated. Creatine kinase level was 509 IU/l, creatine kinase MB isoenzyme (CK-MB)47 IU/l, cardiac troponin T 0.62 ng/ml, myosin light chain 6.1 ng/ml, and myoglobin 142 ng/ml. Thallium-201 myocardial perfusion imaging with dobutamine stress showed a dobutamine-induced perfusion deficit of the anteroseptal wall of the left ventricle with 0.1 mV ST-segment depression in II, III, aVF, V5, and V6. The mean left anterior descending blood flow measured with the Doppler guidewire was increased from 211 to 378 ml/min. Selective coronary arteriography showed dominant left coronary artery with the contrast medium streaming into the left ventricle via a maze of fine vessels from the distal left anterior descending coronary artery. No critical stenosis of the left anterior descending coronary artery was observed. Administration of acetylcholine 100 micrograms into the left coronary artery did not induce vasoconstriction of that artery. The fistula terminating in the left ventricle was ligated surgically and the patient became free of chest pain. Thallium-201 myocardial perfusion imaging with dobutamine stress revealed no perfusion deficit of the anteroseptal wall of the left ventricle. The presence of coronary steal phenomenon was detected by dobutamine stress myocardial imaging.

Coronary Vessel Anomalies↗