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Biomedical subjects

Y Abe

Publications and source records attributed to Y Abe.

At least 1,351 records · Page 75Linked to original sources
PubMedDate not supplied

Development of a new circulatory assist method with the combined effects of intra-aortic balloon pumping and counter pulsation. First report.

Current circulatory assist methods, such as intra-aortic balloon pumping (IABP), are not always adequate to save acute circulatory failure patients. Therefore, a stronger, percutaneously accessible method is required. We found that the combination of IABP and CP generated a profound circulatory assist effect, and we have consequently developed a new assist system in this study. A sac type blood pump with a volume of 20 ml and a single port without a valve, was developed for CP. In the mock circulatory test, a 20 ml stroke volume was obtained using a cannula with a 5 mm diameter under the following driving conditions: air pressure = 200/-100 mmHg; S/D = 50%; pulse rate = 100 bpm. In vivo experiments were performed using four mongrel dogs with body weights of 12-20 kg. A cannula for CP was inserted via the brachial artery or subclavian artery into the aortic root. The pump flow (PF), coronary artery flow (CF), renal arterial flow (RF), and aortic pressure (AP) were measured, and the combined effects of IABP and CP were compared with their individual effects. In the most effective case, a marked increase in diastolic AP (60%), cardiac output (40%), and CF (100%) was obtained by the combination of IABP and CP, which produced a remarkable effect compared with the single use of IABP and CP. There was no negative effect on RF by this assist method. As this new circulatory support system has many circulatory assist effects, and is percutaneously accessible, it will be available for clinical use.

Animals↗
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Fabrication of a jellyfish valve for use in an artificial heart.

For a valve to be fabricated seamlessly into an artificial heart (AH) blood pump, a jellyfish valve has been developed, in which a thin membrane is fixed at the center of a valve seat having several spokes to protect against prolapse of the membrane. The valve is superior in performances to a Björk-Shiley valve, and reveals good blood compatibility. The valve would be very useful not only for AH animal study, but for future clinical use in infants to adults. Several institutions are already trying the valve. In this paper, the fabrication of the jellyfish valve is introduced, and in vitro and in vivo results summarized. A computer aided design (CAD) system was developed to cut a male wax mold of the valve seat. The input parameters to the CAD are diameter, height, thickness of rim, number of spokes, width and thickness of spokes, etc. Jellyfish valves with diameters of 4 to 27 mm have already been fabricated for many types of AHs and assist pumps.

Animals↗
PubMedDate not supplied

Changes with respect to time in the in vivo adsorption of plasma proteins onto artificial heart blood pumps.

The distribution of adsorbed plasma proteins (albumin, IgG, and fibrinogen) on 10 artificial heart blood pumps coated with 2 segmented polyurethanes was evaluated quantitatively after long-term in vivo experiments with goats to determine how the adsorption of plasma proteins on the pumps was affected by the kinds of biomaterials used, and by the pumping duration. The adsorbed plasma proteins on the materials were determined quantitatively using the iodine-125 conjugated antibody method. Microscopically, the adsorbed plasma proteins were marked by the gold colloid conjugated antibody method, and analyzed using a field emission scanning electron microscope. The macroscopic results showed that: 1) the adsorbed plasma proteins on KP-13 were more evenly and finely distributed than those on Cardiothane; 2) with KP-13, the adsorption of IgG and albumin at the center of the pumps was significantly less than in the peripheral areas, and the adsorbed IgG and albumin decreased significantly as the pumping duration increased; 3) in contrast, the adsorbed fibrinogen increased significantly with time; and 4) with Cardiothane, the tendencies for adsorbed IgG and albumin to decrease, and for adsorbed fibrinogen to increase, were less significant than with KP-13. Microscopically, the gold colloids marking plasma proteins were found to not cover the whole of the surface, but were found scattered randomly or in clusters, with no relationship observed between the distributions of the three plasma proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
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The second and third model of the flow transformed pulsatile total artificial heart.

For the purpose of future total implantation, a new pulsatile total artificial heart, a flow transformed pulsatile total artificial heart (FTPTAH), in which the continuous flow from a single centrifugal pump (CFP) was converted to pulsatile flow by switching two three-way valves that could alternately perfuse the systemic and pulmonary circulation, was proposed, and the data from the prototype model were reported. As the next step, the second model, in which a CFP and a spool valve (SV) driven with a solenoid were fabricated in one piece, was made and tested in a mock circulatory system. The system could send 4.7 L/min of pulsatile output alternately to the pulmonary artery and aorta, with 30 and 100 mmHg afterload, respectively, at 3000 rpm CFP. However, three problems were encountered: the output was not enough, mixture or inversion of venous and arterial blood in the CFP would occur, and heat generation at the solenoid was very severe. To solve these problems, a third model was designed in the current study. To increase pump output, hydrodynamic analysis was performed. The SV was divided into inlet and outlet to control the blood mixture or inversion. To suppress heat generation, each SV was driven back and forth by two solenoids, one on each side of the SV. The model revealed satisfactory results in a mock circulatory system.

Biomedical Engineering↗
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Use of the Nippon-Zeon pneumatic ventricular assist device as a bridge to cardiac transplantation.

The Nippon-Zeon (NZ) ventricular assist device is a sac type, air driven, heterotopic, external pump. Its performance has been evaluated in Japan as a bridge to myocardial recovery. Few data are available on the device as a bridge to heart transplantation. Since 1991, 10 patients (9 men) were bridged to heart transplantation with NZ, all in biventricular support. The mean age was 39 +/- 13 years (range, 21-60 years), mean body weight was 75 +/- 13 kg (range, 51-95 kg). Five patients had a dilated cardiopathy, and five were ischemic (three acute myocardial infarctions). Despite maximal inotropic support, including enoximone in seven, epinephrine in three, and intraaortic balloon pumping in one, eight patients were anuric, three were in acute hepatic failure, and three were intubated. Preoperative hemodynamic and biologic values were: cardiac index, 1.57 +/- 0.4 l/min/m2; pulmonary capillary wedge pressure, 34 +/- 5 mmHg; creatinine, 200 +/- 80 mumol/l; blood urea nitrogen, 17.5 +/- 8 mmol/l; total bilirubin 36 +/- 6 mumol/l; aspartate aminotransferase, 1,000 +/- 2,000 IU/l. In all patients, a biventricular assist device was implanted without the use of cardiopulmonary bypass. Improvement occurred immediately in all but one. Mean left ventricular flow was 4.5 +/- 0.8 l/min. Anticoagulation was maintained with intravenous heparin. Recently for bleeding was required in one case (10%), and two patients had positive blood cultures that were successfully treated. There was no mechanical failure. Hemolysis was not significant (lactate dehydrogenase, 378 +/- 50 IU/l; plasma-free hemoglobin below 10 mg/dl). Each device was free of thrombi and deposits at time of explantation. One patient died while on assist. Nine patients (90%) were transplanted after 11 +/- 8 days (range, 1-32 days). Three died early after transplantation, one of graft failure, two of sepsis. Six patients (66%) could be discharged. The follow-up ranges from 7 to 28 months. NZ is a simple, reliable, pneumatic device driven by a light, silent console; it can be rapidly implanted without cardiopulmonary bypass in patients in desperate condition who are awaiting cardiac transplantation. The difficulty of patient rehabilitation while using this device should limit the duration of support to weeks to allow the patient to be in optimal condition for heart transplantation.

Adult↗
PubMedDate not supplied

A new apparatus for chronic observation of the microcirculation in situ to evaluate artificial organ performance.

Chronic study of the peripheral circulation and metabolism is very important in evaluation of artificial organ performance. However, there has been no way to observe the microcirculation in situ, chronically and continuously, without restriction. In this study, the authors developed a new apparatus that could be implanted and connected to an artificial organ that would allow continuous observation of the microcirculation while the subject is awake. The apparatus uses a charge coupled device (CCD) under a new principle: thin living tissue, such as mesentery, is put directly on a highly integrated CCD and transilluminated with a light emitting diode (LED). The vascular nets in the tissue are projected onto the CCD like a contact photograph, which is sent to a television screen and can be analyzed for motion and function. A 0.5 inch CCD with 25K pixels was used in this study. The cover glass of the CCD was removed so the tissue would be able to directly contact the CCD surface. The CCD, as well as LED, were molded with hard polyurethane as electrical insulation. The apparatus is 35 mm in diameter and 10 mm high with a micro stand for lighting with the LED, which is easy to implant in a goat or calf. The resolution of this apparatus was tested by putting a micro scale on the CCD surface. Several tenths of micrometers could be seen. In an animal experiment with a rabbit, configurations of arterioles and venules and their motions could be observed continuously for a night until the electrical insulation was broken. This method might be a strong weapon in artificial organs research.

Animals↗
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Results of animal experiments using an undulation pump total artificial heart: analysis of 10 day and 19 day survival.

An undulation pump is a special rotary blood pump in which rotation of a brushless DC motor is transformed to an undulating motion by a disc in the pump housing attached by means of a special link mechanism. In the blood pump, a closed line between the disc and housing moves from the inlet to the outlet by this undulating disc motion, which sucks and pushes the blood from the inlet to the outlet. Because the same phenomena occurs at both sides of the disc, a continuous flow is obtained when the motor rotational speed is constant. The pump flow pattern can be easily changed from continuous flow to pulsatile flow by controlling the motor drive current pattern. A seal membrane made of segmented polyurethane protects the blood from invading the link mechanism as well as the motor. UPTAH is fabricated with two undulation pumps and two brushless DC motors. Its size is 75 mm in diameter and 80 mm long, and it has one of the great advantage of no compliance chamber required in the system. UPTAHs were implanted under cardiopulmonary bypass (CPB) into the chest cavities of 16 goats, each weighing between 41 and 72 kg. No anticoagulant and antiplatelet agent was used after the surgery. The left atrial pressure was automatically controlled to prevent its elevation and sucking of the atrial wall into the atrial cuff. The following results were obtained: (1) UPTAHs fit well into all the goats; (2) the longest survival was 19.8 days, the cause of death was bleeding from the aortic anastomosis; (3) No thrombus was observed in the blood pump despite no anticoagulant use. Hemolysis depended upon the length of CPB during surgery. When CPB time was within 2 hours, hemolysis level returned to baseline within a few days of the surgery. UPTAH is a promising implantable TAH, because of its small size and easy controllability.

Animals↗
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Automatic monitoring system for artificial hearts using self organizing map.

This study presents an automatic monitoring system for artificial hearts. The self organizing map (SOM) was applied to monitoring and analysis of an aortic pressure (AoP) signal measured from an adult goat equipped with a total artificial heart. In the proposed system, two different SOMs were used to detect and classify abnormalities in the measured AoP signal. In the first stage, an ordinary SOM, taught with only normal AoP data, was used for detection of abnormalities on the basis of the quantization error in the real-time monitoring task. In the second stage, a supervised SOM was used for classification of abnormalities. The supervised SOM can be regarded as an ordinary SOM with an extra class vector for solving the classification problem. The class vector is assigned to every node in the second SOM as an output weight learned according to Kohonen's learning rule. The effectiveness of detection and classification of abnormalities using these two SOMs was confirmed.

Animals↗
PubMedDate not supplied

Differential diagnosis of solitary pulmonary nodules with positron emission tomography using [11C]L-methionine.

Two patients with solitary pulmonary nodules, 1.5-2.0 cm in diameter, were studied by positron emission tomography using [11C-Methyl]L-methionine (11C-Met). Case 1 showed high accumulation of 11C-Met in the tumor, and a tumor/muscle ratio of 6.0 suggesting malignancy. Tissue obtained by biopsy revealed a squamous cell carcinoma. Case 2 showed nonspecific isotope accumulation in the tumor, and a tumor/muscle ratio of 1.2 suggesting a benign lesion. Lung biopsy demonstrated granuloma. Positron emission tomography with 11C-Met seems to be useful for the differential diagnosis of solitary lung nodules.

Aged↗
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Fast breath-hold T2-weighted MRI of the kidney by means of half-Fourier single-shot turbo spin echo: comparison with high resolution turbo spin echo sequence.

PURPOSE: The value of the fast half-Fourier single-shot turbo spin echo (HASTE) sequence in T2-weighted MRI of the kidney was evaluated as a substitute for the conventional turbo spin echo (TSE) sequence. METHOD: Forty-five patients with suspected abnormalities of the kidney underwent MRI with a 1.5 T system. Breath-hold HASTE and respiratory-triggered TSE sequences were performed. Qualitative and quantitative analyses were performed for comparison of these sequences. RESULTS: The signal-to-noise ratio (SNR) with HASTE was higher than that with TSE. The lesion-to-kidney contrast-to-noise ratio for solid masses with HASTE was almost equal to that with TSE. For cystic masses, the CNR with HASTE was significantly higher than that with TSE (p < 0.05). Respiratory and chemical shift artifacts were significantly smaller on HASTE than on TSE (p < 0.01). However, the blurring artifact was higher on HASTE than on TSE (p = 0.01). CONCLUSION: The HASTE sequence generates high contrast images and is free of motion and chemical shift artifacts, with much better time efficacy. The sequence provides comparable diagnostic information to TSE sequences.

Adult↗
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Effects of the calcium antagonist nicardipine on renal function and renin release in dogs.

The effects of nicardipine, classed as a calcium antagonist, on renal hemodynamics, renal function, and renin release were investigated in pentobarbital-anesthetized dogs. Intrarenal infusion of this drug at a rate of 5 micrograms/min in both hydrated and hydropenic dogs resulted in a significant increase in renal blood flow, glomerular filtration rate, urine flow, and renin release, with a significant fall in systemic blood pressure. The intrarenal blood flow as measured by the microsphere method indicated a greater increase in flow rate in the juxtamedullary than in the superficial area. During nicardipine infusion, free water reabsorption rate (TcH2O) in hydropenic dogs or free water production (CH2O) in hydrated dogs increased in proportion to the urine flow. Neither TcH2O/CH2O nor CH2O/osmolar clearance were significantly changed throughout the experiments. These data suggest that nicardipine did not inhibit sodium transport at the medullary portion of the ascending limb of Henle, and that the increase in GFR might induce an enhancement of the delivery of sodium to the Henle loop. In addition, an intrarenal hemodynamic alteration may be one possible mechanism involved in the diuretic action of nicardipine. Calcium-antagonistic actions of nicardipine may account for the changes in renal parameters.

Animals↗
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Effect of SA-446, an angiotensin-converting enzyme inhibitor, on renal function in anesthetized dogs: special reference to arachidonic acid metabolites.

Intravenous infusion of SA-446 (1 mg/min) decreased systemic blood pressure and increased renal blood flow in anesthetized dogs. These changes were accompanied by a slight natriuretic response. During the infusion of this dose of SA-446, the pressor response to angiotensin I was abolished and the depressor response to bradykinin was markedly potentiated. Administration of indomethacin (13 mg/kg i.v.) suppressed natriuresis and, to some extent, the renal vasodilation caused by SA-446. Before and after administration of SA-446, four arachidonate metabolites, prostaglandin E2, prostaglandin F2 alpha, 6-keto-prostaglandin F1 alpha, and thromboxane B2, were determined in plasma and urine by radioimmunoassay. There were no remarkable changes in levels of prostaglandins and thromboxane B2 in arterial and renal venous plasma. The urinary excretion of the metabolites varied little, but thromboxane B2 excretion did significantly decrease. Thus, reduction in the biosynthesis of thromboxane B2 in the kidney may relate to the effects of SA-446 on renal hemodynamics and urine formation.

3-Mercaptopropionic Acid↗
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Is paranoid schizophrenia the most common subtype? Comparison of subtype diagnoses by Japanese and European psychiatrists, using the summaries of the same patients.

We compared the subtype diagnoses of schizophrenia (ICD-10) of 58 Japanese and 61 European psychiatrists matched for clinical experience using 10 case summaries. As a result, there are marked differences between Japanese and European psychiatrists in the mode of subtype diagnoses of schizophrenia rather than in the clinical pictures of the patients themselves; the hebephrenic type (F20.1) was more likely to be diagnosed by Japanese psychiatrists, while the paranoid type (F20.0) was more frequently diagnosed by European psychiatrists. Japanese psychiatrists take into account the patient's age at onset and the clinical course of the disease in identifying the subtype, while European psychiatrists tend to focus on the presenting symptoms, particularly paranoid symptoms.

Adolescent↗
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Protective effects of anti-neutrophil antibody against myocardial ischemia/reperfusion injury in rats.

Neutrophil activation initiates myocardial ischemia/reperfusion (I/R) injuries. The aim of this study is to evaluate the in vitro functions of an anti-neutrophil monoclonal antibody, Urge-8, and its therapeutic efficacy against myocardial ischemia (MI) in rats. We measured in vitro functions of rat neutrophils including chemotactic activity, superoxide production, phagocytic function, and neutrophil degranulation. MI was induced in Wistar rats by clamping the left coronary artery for 1 h. Rats received either isotype-negative control IgG(1) (control group, n = 20), 250 microg/kg of Urge-8 before (pre-treatment group, n = 20) or after (post-treatment group, n = 20) MI. The three groups were compared during the first 24 h after reperfusion with respect to changes in mean arterial pressure, heart rate, body temperature, biochemistry, serum cytokines, myocardial neutrophil infiltration, survival rate, and size of MI. Urge-8 effectively suppressed in vitro functions of rat neutrophils including chemotactic activity, superoxide production, phagocytic function, and neutrophil degranulation. The Urge-8 treated groups showed higher levels of arterial pressure and survival rate, lower values of interleukin-6 and interleukin-8, lower grade of myocardial neutrophil infiltration, and smaller MI size as compared to the control group. In conclusion, Urge-8 is effective against myocardial I/R injury by suppressing certain functions and myocardial infiltration of neutrophils in rats.

Animals↗
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Effects of smoking on regional cerebral blood flow in neurologically normal subjects.

The chronic effects of smoking on regional cerebral blood flow (CBF), and on serum lipids and lipoprotein levels in neurologically normal subjects, were studied. CBF was studied by the 133-Xenon inhalation method and gray matter flow was calculated following the method of Obrist et al. One hundred and eleven subjects, who had no abnormalities in neurological examinations nor in CT scans, were divided into two groups: smokers (37) and non-smokers (74). Those who had a smoking index (Number of cigarettes/day) X (years of smoking history) greater than 200 were designated as smokers. The mean smoking index of smokers was 760. Sixty-two of the 74 subjects in the non-smoking group had never smoked, and the mean smoking index of non-smokers was 17. In the male, CBF was significantly lower in smokers than in non-smokers (mean CBF, 12.5% lower in smokers, p less than 0.001). Increased reduction of CBF with advancing age was also observed. Compared to non-smokers, CBF in smokers was found to be significantly lower than the expected age matched value. Serum high density lipoprotein cholesterol values in smokers were significantly lower, and total cholesterol levels significantly higher than in non-smokers. We concluded that smoking chronically reduces CBF. Decrease of CBF in smokers was probably due to advanced atherosclerosis which produces vascular narrowing and raised resistance in cerebral blood vessels.

Adult↗
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Increased energy expenditure after intravenous administration of amino acids.

Nutrient-induced thermogenesis (NIT) after parenteral administration of amino acids (AAs) was investigated in rats and compared with result obtained with intragastric administration. Resting energy expenditure was measured with a new type of open-circuit indirect calorimeter. The NIT increased shortly after parenteral AAs administration and reached a steady state in 30 minutes. The change in resting energy expenditure (the increment of resting energy expenditure over preinfusion baseline values) showed a significant relationship not only with the amount of infused AAs but also with the AA concentration in the portal vein. Furthermore, the increase in plasma AA concentrations in the portal vein was proportional to the amount of the particular AA infused. This relationship held true over the entire range tested. NIT with parenteral infusion (11% to 12%) was lower than that with intragastric infusion (20% to 23%). Plasma insulin, corticosterone, and glucagon levels increased after both parenteral and intragastric AAs administration, but the two methods did not show any significant differences in hormonal changes. The plasma aminogram of the portal vein after intragastric infusion was compared with that after parenteral infusion. Total plasma AA concentration and the levels of glutamine, lysine, arginine, glutamate, aspartate, and histidine were lower but the level of isoleucine was higher after intragastric infusion. On the basis of these results, it is believed that parenteral administration of AAs can induce thermogenesis, which may be regulated by the intraportal AA concentration. Considering the remarkable decrease in glutamine in the portal vein after intragastric infusion, the cost of intestinal metabolism may predominantly contribute to the NIT resulting from intragastric infusion.

Amino Acids↗
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Accumulation of new quinolones in the blood of elderly patients.

The correlation between serum levels of five new quinolones (norfloxacin, ofloxacin, enoxacin, ciprofloxacin and lomefloxacin), age and 24 h creatinine clearance was studied in 180 patients. One of five new quinolones was orally administered, before transurethral resection of the prostate, at the dosage of 200 mg three times daily for 3 consecutive days. Serum levels were checked 5.5 h or about 17 h after the final administration. Creatinine clearance was found to be negatively correlated with aging (P < 0.001). After oral administration, the level of certain accumulated new quinolones in serum increased with the age of patients (P < 0.001-0.1). This tendency was more marked for ofloxacin, lomefloxacin and enoxacin than for ciprofloxacin and norfloxacin. The investigators concluded that the level of accumulated new quinolones in serum with aging is correlated to the 24 h urinary excretion rate of each new quinolone. These results indicate that ofloxacin, lomefloxacin and enoxacin, which have higher 24 h urinary excretion rates, should be administered at lower doses according to the age of the patient, in order to prevent adverse reactions.

Aged↗