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Biomedical subjects

A Fujisawa

Publications and source records attributed to A Fujisawa.

At least 37 records · Page 2Linked to original sources
PubMed1999

A new vitamin E (alpha-tocomonoenol) from eggs of the Pacific salmon Oncorhynchus keta.

A novel alpha-tocomonoenol 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyl-12-tridecenyl )-2H-1- benzopyran-6-ol[ having an unusual methylene unsaturation at the isoprenoid-chain terminus of alpha-tocopherol was isolated from the lipophilic fraction of chum salmon eggs. The structure of this marine-derived tocopherol (MDT) was established by spectral analyses. The peroxyl radical-trapping activities of MDT and alpha-tocopherol were compared in aqueous phosphatidylcholine liposomal suspension and in methanolic solution at 37 degrees C. The antioxidant activity of MDT was found to be identical to that of alpha-tocopherol under the experimental conditions of measurement.

Animals↗
PubMed1999

Long-term in vivo left ventricular assist device study for 284 days with Gyro PI pump.

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, the Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart (TAH), 2 week screening tests for anti-thrombogenecity, and a 1 month system feasibility study. Based upon these results, a metallic prototype, the Gyro PI 700 series, was subjected to long-term in vivo left ventricular assist device (LVAD) studies of over 1 month. The Gyro PI 700 series has the same inner dimension and same characteristics of the Gyro PI 601 such as an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI metallic pump is also driven with the Vienna DC brushless motor actuator like the PI 601. The pump-actuator package was implanted in 3 calves in the preperitoneal space, bypassing from the left ventricular (LV) apex to the descending aorta. Case 1 achieved a 284 day survival. Case 2 was euthanized early at 72 postoperative days as a result of the functional obstruction of the inlet port due to the excessive growth of the calf. There was no blood clot inside the pumps of either case. Case 3 is on-going (22 days on July 24, 1998). During these periods, all cases showed no physiological abnormalities. In conclusion, the PI 700 series pump has excellent results as a long-term implantable LVAD.

Animals↗
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

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↗
PubMed1998

Oxidative stress in patients with hepatitis, cirrhosis, and hepatoma evaluated by plasma antioxidants.

We have applied our method for the simultaneous detection of plasma ubiquinol-10 (reduced form) and ubiquinone-10 (oxidized form) (S. Yamashita and Y. Yamamoto, Anal. Biochem. 250, 66-73, 1997) to plasmas of normal subjects (n = 16) and patients with chronic active hepatitis (n = 28), liver cirrhosis (n = 16), and hepatocellular carcinoma (n = 20) to evaluate the pressure of oxidative stress in these patients. The average ubiquinone-10 percentages (+/- S.D.) in total ubiquinone-10 and ubiquinol-10 in the four groups were 6.4 +/- 3.3, 12.9 +/- 10.3, 10.6 +/- 6.8, and 18.9 +/- 11.1, respectively, indicating a significant increase in ubiquinone-10 percentage in patient groups in comparison to normal subjects. These results and a significant decrease in the plasma ascorbate level in patient groups indicate that oxidative stress is evident after the onset of hepatitis and the subsequent cirrhosis and liver cancer.

Adult↗
PubMed1998

[Relationship between cognitive function and discharge place among stroke patients after rehabilitation].

One hundred and ninety-nine elderly stroke patients, who received rehabilitation treatment, were examined, to clarify the relationship between cognitive function and discharge place. The patients who moved to long-term care facilities showed more severe disabilities of basic activities of daily living (ADL), more frequent incontinence, and lower functional impairments (Brunnstrom stage), compared with those discharged to their home. Multivariate regression analysis was done with discharge place as the dependent variable. Independent variables were age, sex, kind of stroke, rehabilitation period, level of ADL and IQ on Kohs test, or performance IQ on the Wechsler Adult Intelligence Scale. Older age, higher levels of ADLs, and higher scores on Kohs test IQ or Wechsler Adult Intelligence Scale Performance IQ were all significantly linked with home discharge. These results suggest that non-verbal cognitive dysfunction may affect discharge place in elderly stroke patients after rehabilitation therapy.

Activities of Daily Living↗
PubMed1997

The optimum dose of gamma radiation-heavy doses to low wear polyethylene in total hip prostheses.

Wear volume, surface area and coefficient of friction of UHMWPE cup crosslinked with gamma radiation of 0, 50, 75, 100, 125, 150 and 200 Mrad sliding against an alumina ball were measured using a sphere-on-flat reciprocating type tribology testing machine. The effects of gamma radiation were scarcely observed in coefficient of friction. The coefficient of friction under lubricated (distilled water) and non-lubricated testing conditions was 0.08 to 0.12 and 0.20 to 0.25, respectively. The wear volume of UHMWPE with radiation of 50 Mrad, 75 to 150 Mrad, and 200 Mrad was 70 to 80%, 18 to 25%, and 12 to 15%, respectively, in comparison to non-irradiated specimens. Elongation and tensile strength of UHMWPE with radiation of 100 Mrad decreased to 6%, and 50% of that without radiation, respectively. The hardness increased with increase of the radiation dose. From several kinds of tribological findings, mechanical strength tests, and studies of long-term clinical findings, it is concluded that approximately 200 Mrad is the optimum dose of gamma radiation for clinical use in total hip prostheses.

Journal Article↗
PubMed1996

Hip-simulator ranking of polyethylene wear: comparisons between ceramic heads of different sizes.

We carried out simulator studies on ceramic-polyethylene total-hip combinations to determine the volumetric wear-rates of 22 mm, 26 mm and 28 mm femoral-head sizes. Bovine-serum lubrication and 2 kN peak sinusoidal load-profile were used with polyethylene (UHMWPE) cups. Wear was assessed by gravimetric technique. Precision (9%) was ensured by the use of multiple specimens, multiple wear-events, and the linear-regression method of estimating the average wear trend, thereby reducing the inherent, unpredictable nature of each wear-event. Volumetric wear-rates for polyethylene averaged 23 mm3 per 10(6) cycles for the 22 mm ceramic head and up to 32 mm3 per 10(6) cycles for the 28 mm head. The difference between 22 mm and the larger head-sizes was significant. This may well be the first laboratory confirmation of Charnley's original clinical Low-Friction Arthroplasty concept with regard to wear rate. The wear penalty increased linearly at the rate of 6% to 9% per mm of diameter increase.

Ceramics↗
PubMed1994

[Effect of aging on the aerobic capacity measured by a step-test].

The purpose of this study was to develop a step-test in order to evaluate age-related change in aerobic capacity. A total of 149 healthy men of age through 18 to 83 yrs ascended and descended a single step of 0.2 m height in time to a metronome. The step rate increased step-wise through three stages, each of 3 min duration; 15, 20 and 25 (step/min) for subjects aged 59 or less, and 10, 15, and 20 (step/min) for those age 60 and over. Using the linear relationship between load and heart rate, physical work capacity (PWC, watt/kg) was estimated as the work load with maximum heart rate predicted by age (220-age). In the elderly group (n = 34), heart rate at the end of the last stage was within 60-80% of the maximum heart rate for 25 subjects, and more than 80% for the other 9 subjects. No risky arrhythmia or significant ST change on ECG appeared in any subject. A retest of the step-test for 16 elderly subjects showed its repeatability and a linear relationship between heart rate and oxygen consumption. The results suggested that the step-test was applicable to the elderly in regard to appropriate work load and safety. The PWC significantly declined with aging (r = 0.52, p < 0.001). Relative aerobic capacity, taking that at age 20 as 100%, was 60% and 53% for subjects aged 60 and 70, respectively, which was in good agreement with available reports which measured oxygen consumption directly.

Adolescent↗
PubMed1993

Effects of NG-nitro-L-arginine on electrical and mechanical responses to stimulation of non-adrenergic, non-cholinergic inhibitory nerves in circular muscle of the rat gastric fundus.

The effects of L-nitroarginine (L-NNA), an inhibitor of nitric oxide (NO) synthesis, on non-adrenergic, non-cholinergic inhibitory transmission in the circular smooth muscle of the rat gastric fundus were studied. The relaxation in response to nerve stimulation in the presence of guanethidine and atropine was depressed by the application of L-NNA (10(-4) M), and the depression was reversed by the addition of L-arginine (10(-4) M). The time course of the relaxation was altered from a monophasic to biphasic one, both of which were depressed. Stimulation of non-adrenergic, non-cholinergic nerves initiated inhibitory junctional potentials (i.j.p.). In addition, slow after-hyperpolarization was observed when stimuli were applied repeatedly at frequencies higher than 0.5 Hz. L-NNA reduced the i.j.p. partially and abolished the after-hyperpolarization, indicating the partial involvement of NO in non-adrenergic, non-cholinergic inhibitory transmission. The effects of L-NNA on the nerve-mediated relaxation are thought to be due to changes in the i.j.p. and slow after-hyperpolarization.

Animals↗
PubMed1993

Cloning and DNA sequence of a 29 kilodalton polypeptide gene of Mycoplasma gallisepticum as a possible protective antigen.

A lambda gt11 clone, designated M1 and having a 0.8 kilobase (kb) insert, was selected by screening a Mycoplasma gallisepticum (M.g.) genomic DNA library with antisera against M.g. cells and their membrane proteins. The sequence of a 1.7 kb EcoRI fragment of genomic DNA covering the entire M1 insert revealed a long open reading frame, TM-1, that encoded a polypeptide with a deduced molecular weight of 29 kDa. An antiserum raised in chicken against the TM-1 polypeptide, which was produced by recombinant Escherichia coli cells and purified by column chromatography, inhibited growth of M.g. cells in vitro. Moreover, chickens immunized with this polypeptide were partially protected from a challenge with virulent M.g. This polypeptide may serve as the basis for a vaccine against M.g. infection.

Amino Acid Sequence↗
PubMed1993

Is white coat hypertension innocent? Structure and function of the heart in the elderly.

To evaluate the morphological and functional characteristics of the heart in elderly patients with white coat hypertension, we performed an echocardiographic study in 67 elderly individuals older than 60 years: 17 patients with white coat hypertension, 34 patients with true hypertension, and 16 normotensive control subjects. White coat hypertension was defined as a mean 24-hour ambulatory systolic blood pressure of less than 140 mm Hg associated with office hypertension. Cardiac responses to an isometric handgrip exercise test were used to evaluate left ventricular functional reserve. Left atrial dimension and left ventricular mass index were significantly greater in the white coat hypertension group than in the normotension group (P < .05) but were similar to values in the true hypertension group. Left ventricular diastolic function, expressed by peak late-early filling ratio of diastolic mitral flow, showed increasing impairment in the order of the normotension, white coat hypertension, and true hypertension groups (analysis of variance, P < .05); the ratio in the white coat hypertension group tended to be higher than that in the normotension group (unpaired t test, P = .054). The relation between fractional shortening and end-systolic stress did not shift downward after handgrip exercise in the white coat hypertension group, indicating that functional reserve in the left ventricle was maintained. Thus, patients with white coat hypertension had a moderately increased left atrial dimension and left ventricular mass in association with a tendency for disturbed diastolic function, although systolic functional reserve remained the same. These findings suggest that white coat hypertension in the elderly may not be innocent.

Aged↗
PubMed1988

Soluble interleukin-2 receptors in the serum of patients with chronic renal failure.

The levels of soluble form of the interleukin-2 receptor (sIL-2R) were evaluated in the peripheral blood of 29 patients with chronic renal failure (CRF) using enzyme-linked immunosorbent assay. All patients had undergone hemodialysis and the mean (+/- S.D.) BUN was before hemodialysis was 80.9 +/- 22.4 mg/100 ml. The mean level of sIL-2R was 1146 +/- 258 U/ml, which was significantly higher than the level (288 +/- 118 U/ml) in 12 individuals with a normal BUN level (p = 0.01). In patients with CRF, the elevated sIL-2R level was not influenced by hemodialysis, and not correlated with creatinine or beta 2-microglobulin levels. The kidneys may play an important role in the catabolism of serum sIL-2R. The elevated sIL-2R level may be related to compromised immunoregulation in CRF.

Biomarkers↗