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Biomedical subjects

M Yoshizawa

Publications and source records attributed to M Yoshizawa.

At least 19 recordsLinked to original sources
PubMed2000

Post-implantation development of mouse androgenetic embryos produced by in-vitro fertilization of enucleated oocytes.

We report here on the precise ability of mouse androgenetic embryos produced by in-vitro fertilization of enucleated oocytes to develop to day 9.5 of gestation when cultured with M16 and CZB media. Androgenetic embryos cultured with CZB rather than M16 medium developed to the blastocyst stage in a more significant proportion (56.6% versus 45.0%, P < 0.001). However, after cavitation, the rate of cell proliferation of androgenetic embryos cultured with CZB medium was significantly decreased (P < 0.05). Embryo transfer experiments showed that blastocysts cultured with M16 medium were superior to those cultured with CZB medium in their ability to develop to 9.5-day-old fetuses (28.1% versus 11.1%, P < 0.001). These results showed that the present procedure for producing androgenetic mouse embryos is reliable and that M16 medium is superior for culturing the embryos. Fetal sexing by polymerase chain reaction (PCR) also demonstrated that both XX and XY embryos develop to 9.5-day fetuses at theoretical rates (1:2). This is the first finding that mouse XX androgenones survive after implantation.

Animals↗
PubMed1999

Induction of heme oxygenase-1 as a response in sensing the signals evoked by distinct nitric oxide donors.

To gain insights into the cellular responses evoked by nitric oxide (NO), we have studied the effects of NO donors with distinct chemistries on the expression of heme oxygenase-1 mRNA by northern blot analysis. The expression levels of heme oxygenase-1 mRNA were increased significantly in DLD-1 human colorectal adenocarcinoma cells by treatment with each of three NO donors: sodium nitroprusside (SNP), S-nitroso-L-glutathione (GSNO), and 3-morpholinosydnonimine (SIN-1). A combination of SIN-1 plus SNP or GSNO additively increased heme oxygenase-1 mRNA expression, whereas synergistic induction was seen with SNP plus GSNO. The SNP-mediated induction was not affected noticeably by extracellular superoxide dismutase, catalase, or mannitol, while the induction by SIN-1 was attenuated by superoxide dismutase. Thus, the SNP-mediated induction of heme oxygenase-1 mRNA expression may be independent of reactive oxygen species, and the induction by SIN-1 is mediated partly by peroxynitrite, which is generated by immediate reaction of NO and superoxide anion. Transient transfection assays suggested that treatment with SNP, but not with GSNO or SIN-1, increased the expression of a reporter gene through a cis-acting element, including the cadmium-responsive element, of the human heme oxygenase-1 gene. These results suggest that SNP induces heme oxygenase-1 mRNA expression through a mechanism different from that for GSNO or SIN-1. We therefore propose that induction of heme oxygenase-1 represents a common cellular response in sensing the signals evoked by distinct NO donors.

Adenocarcinoma↗
PubMed1999

Chromosomal diagnosis in each individual blastomere of 5- to 10-cell bovine embryos derived from in vitro fertilization.

Chromosomal normality and sex were diagnosed in each blastomere of bovine embryos derived from in vitro fertilization (IVF). Bovine embryos developing to the 5- to 10-cell stage were separated into individual blastomeres with 0.5% protease. After treatment with 100 ng/mL vinblastine sulfate for 8 to 10 h, they were prepared for chromosome samples. In total, 33 bovine embryos and 185 blastomeres were examined. Chromosomal normality was analyzed in 43.8% (81/185) of the blastomeres and 60.6% (20/33) of the embryos; while chromosomal anomalies were found in 16 (80%, 16/20) of the embryos, 5 haploid embryos and 11 mosaic (n/2n) embryos. Mosaicism characteristic of the opposite sex in X-and Y-chromosomes was found in 2 haploid embryos, and that of a Y-chromosome and of XX chromosomes in 1 n/2n embryo. Various sex-chromosome compositions were also observed in the other 10 chromosomal mosaic n/2n embryos.

Animals↗
PubMed1999

Chaotic dynamics in circulation with Tohoku University vibrating flow pump.

For the development of a totally implantable ventricular assist system (VAS), we have been developing the vibrating flow pump (VFP), which can generate oscillated blood flow with a relative high frequency (10-50 Hz) for a totally implantable system. In this study, the effects of left ventricular assistance with this unique oscillated blood flow were analyzed by the use of nonlinear mathematics for evaluation as the whole circulatory regulatory system, not as the decomposed parts of the system. Left heart bypasses using the VFP from the left atrium to the descending aorta were performed in chronic animal experiments using healthy adult goats. The ECG, arterial blood pressure, VFP pump flow, and the flow of the descending aorta were recorded in the data recorder during awake conditions and analyzed in a personal computer system through an A-D convertor. By the use of nonlinear mathematics, time series data were embedded into the phase space, the Lyapunov numerical method, fractal dimension analysis, and power spectrum analysis were performed to evaluate nonlinear dynamics. During left ventricular assistance with the VFP, Mayer wave fluctuations were decreased in the power spectrum, the fractal dimension of the hemodynamics was significantly decreased, and peripheral vascular resistance was significantly decreased. These results suggest that nonlinear dynamics, which mediate the cardiovascular dynamics, may be affected during left ventricular (LV) bypass with oscillated flow. The decreased power of the Mayer wave in the spectrum caused the limit cycle attractor of the hemodynamics and decreased peripheral resistance. Decreased sympathetic discharges may be the origin of the decreased Mayer wave and fractal dimension. These nonlinear dynamic analyses may be useful to design optimal VAS control.

Analog-Digital Conversion↗
PubMed1999

A future prediction type artificial heart system.

The demand of the biological system needs to be predicted to consider the quality of life (QOL) of a patient with an artificial heart system. The purpose of this study was the prediction of the imminent cardiac output and the predictive control for an artificial heart. For that purpose, autonomic nerve information was applied in this study. Nervous sympathicus action potentials were measured, and a prediction function of cardiac output was made using the sympathetic tone and preload and after-load measurement with multiple regression analysis. The predicted value showed significant correlation with the measured value after 2.9 s. Currently, however, long-term instrumentation of the nervous sympathicus potential is difficult. Thus, hemodynamic fluctuations, which recently have attracted attention, were used in this study. A prediction function using the Mayer wave, which represented nervous sympathicus, was determined. As a result, mid-term prediction became possible. Furthermore, a measurement of the vagal nerve was used as a possible long-term prediction parameter. For long-term prediction, Hurst exponent analysis was used in this study. Vagal nerve discharges in the changing position showed alteration of long-term determination. In conclusion, the future prediction control of an artificial heart takes shape using these prediction functions.

Action Potentials↗
PubMed1999

Vagal nerve activity recording in the awake condition for the control of an artificial heart system.

To detect useful information for an artificial heart control system, we paid attention to the autonomic nervous system. For stable recording, we used vagal nerve activity in chronic animal experiments using healthy adult goats in an awake condition because this nerve was sufficiently bold and large enough. Vagal nerve discharges were successfully recorded from awake goats. They were synchronized with respiration and responded to the hemodynamic changes induced by drug administration, suggesting that they may provide useful information for an artificial heart control algorithm. For automatic control, some time delay plays a vitally important role. Thus, predictive control for an artificial heart system may be desirable. It may be embodied by the use of autonomic nerve information.

Action Potentials↗
PubMed1999

Peripheral vascular resistances during total left heart bypass with an oscillated blood flow.

For development aimed at a totally implantable type ventricular assist device (VAD), the vibrating flow pump (VFP) has been developed at Tohoku University. A transcutaneous energy transmission system (TETS) using amorphous fibers was developed to power the totally implantable VAD system. The VFP works at a high frequency compared to that of a natural heart of a biological system. It is a frequency of 10-50 Hz. In this research, animal experiments with left heart bypass were carried out with healthy adult goats. For comparison between nonpulsatile flow and oscillated flow, a rotary pump (RP) and the VFP were used in the experiments. For the achievement of total left heart bypass, left ventricular approaches were carried out, and blood was pumped from the left ventricle to the descending aorta. Adequate support of the left heart was provided by both pumps. In terms of the results, the vascular resistances tended to decrease during the use of both pumps during 100% bypass driving. When we compared these pumps at the same flow rate, the resistances during RP driving were significantly smaller than those during VFP driving. These results may suggest that the influences of the VFP upon the peripheral vessels may be relatively small compared to those of the RP. This may be an important result when a stable hemodynamic condition is required during artificial circulation. The VFP was considered as a candidate for a totally implantable VAD as a result.

Animals↗
PubMed1999

Detection of the cardiac function by fractal dimension analysis.

Nonlinearity in circulation control attracts attention because nonlinearity is thought to be essential in the function of the living body. Many investigators have pointed out that the analysis of heart rate variability in particular is important in the analysis of autonomic nerve and cardiac function evaluation. Heart rate variability shows nonlinear behavior. However, until the present, many reports have been premised on linearity; linear correlation by frequency analysis has been used by many studies. However, in terms of this methodology, there is a problem applying it to the nonlinear living body. Therefore, fractal and chaos methodology has been used. The ascertainment of cardiac function has become important in allowing the clinical stage of a ventricular assist system to be successful. The purpose of this study was cardiac function evaluation by a methodology that was premised on nonlinearity. Chaos and fractal theory was used as a nonlinear dynamic theory. As a methodology of measurement, the volume of the left ventricle was used rather than an electrocardiogram, the waveform of arterial blood pressure. The volume was measured using acoustic quantification (AQ) ultrasonic echocardiography. Using these methodologies, the time series of many patients were analyzed. For example, drug administration was attempted in this study, and it was found that some drugs like ACE inhibitors showed a significant effect upon nonlinear dynamics in the cardiovascular system. The result, which attempted cardiac function evaluation by these various methodologies, is reported.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Successful metaphase chromosome analysis of human elongated spermatids using mouse oocytes.

Human elongated spermatids from azoospermic patients were inserted into mouse oocytes by intracytoplasmic sperm injection (ICSI). The injection resulted in survival rates of 46.5% (180 out of 387) and activation rates of 36.1% (65 out of 180). The rate of two pronuclear (2PN) formation was 35.4% (23 out of 65). Only 34.8% (eight out of 23) metaphase chromosome spreads from 2PN zygotes could be analysed; however, all were of normal karyotype. Cytogenetic analysis at the first metaphase revealed that human elongated spermatid chromosomes were able to undergo replication in a heterogeneous environment.

Animals↗
PubMed1999

Molecular cloning of cDNA encoding a novel microphthalmia-associated transcription factor isoform with a distinct amino-terminus.

Microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix-leucine zipper protein, and plays an important role in the development of various cell types, such as neural-crest-derived melanocytes and optic-cup-derived retinal pigment epithelium. Three isoforms of MITF with distinct amino-termini have been described. These include melanocyte lineage-specific MITF-M, heart-type MITF-H, and the recently identified MITF-A. Here we identify a fourth isoform, MITF-C, with a unique amino-terminus of 34 amino acid residues, which shares about 43% sequence identity with putative transactivation segments of two previously identified leukemogenic factors, ENL and AF-9. Reverse transcription-polymerase chain reaction analysis revealed that MITF-C mRNA is expressed in many cell types, including retinal pigment epithelium, but is undetectable in melanocyte-lineage cells. In contrast, MITF-A and MITF-H mRNAs are coexpressed in all cell types examined. Transient cotransfection assays suggested that MITF-C, like other MITF isoforms, functions as a transcriptional activator of certain target genes, but its transactivation specificity for the target promoters is different from those of other MITF isoforms. Therefore, isoform multiplicity provides MITF with differential expression patterns as well as functional diversity.

Amino Acid Sequence↗
PubMed1999

Isolation of 9Z beta-carotene from Dunaliella bardawil and its stereoselective synthesis.

An isolation of 9Z beta-carotene from Dunaliella bardawil was accomplished by low-pressure column chromatography with Ca(OH)2 column. Furthermore, it was stereoselectively synthesized by Wittig reaction between the C10-phosphonium salt 2 and 9Z beta-apo-8'-carotenal 1, which was prepared by Emmons-Horner reaction of 9Z beta-ionylideneacetaldehyde 3 with phosphonates 6 and 7 or 8a and 9.

Chlorophyta↗
PubMed1999

Vagal nerve activity and the high frequency peak of the heart rate variability.

For the Quality of life (QOL) of patients with an artificial heart system, monitoring an information of the cardiovascular control system may be important. We have been evaluating the autonomic nervous system for that purpose. Recently, fluctuations in hemodynamic parameters including heart rate variability (HRV) were evaluated by means of spectral analysis and nonlinear mathematical analysis. Respiratory wavers in HRV were thought to reflect ongoing information of the parasympathetic nerve activity. Is it true? In order to confirm this hypothesis, we recorded vagal nerve activity directly in the chronic animal experiments. Six healthy adult goats were anesthetized with Halothene inhalation and thoracotomy were performed by the fourth lib resection during mechanical ventilation. Arterial blood pressure, right and left atrial pressures were continuously monitored with the catheter insertion. Cardiac output was measured by the electromagnetic flowmeter attached to the ascending aorta. After the chest was closed, incision was made to the left neck and left vagal nerve was separated. Stainless steel electrodes were inserted into the vagal nerve and fixed by the plasticizer. After the incision was closed, the goats were transferred to the cage and extubated after waking. Hemodynamic parameters and vagal nerve activity were measured in the awake condition. The results showed that clear observation of the autonomic nerve discharges were embodied by this experimental system. The vagal nerve discharges were synchronized with heart beat and respiration. The vagal nerve tonus was significantly influenced by the hemodynamic alteration. However in some condition, the respiratory wave was not always consistent with tonus of the vagal nerve activity, thus suggesting that we should check another information to evaluate the parasympathetic tone. We must continue this study to evaluate an autonomic nerve during artificial heart circulation.

Animals↗
PubMed1998

Retinoids potentiate transforming growth factor-beta activity in bovine endothelial cells through up-regulating the expression of transforming growth factor-beta receptors.

Retinoic acid (RA) induces the activation of latent transforming growth factor-beta (TGF-beta) in bovine aortic endothelial cells (BAECs) via enhancement of cellular plasminogen activator (PA)/plasmin levels. The resultant TGF-beta suppresses the excessive fibrinolytic activity by decreasing PA expression and stimulating expression of the PA inhibitor, PA inhibitor-1 (PAI-1), and inhibits cell proliferation. Here, we report that, in this regulatory system, RA simultaneously up-regulates the expression of TGF-beta receptor types I and II, resulting in enhancement of TGF-beta activity in the cells. RA increased the numbers of high- and low-affinity binding sites for 125I-TGF-beta1 2.1-fold and 1.5-fold, respectively, without alteration of their Kd values. Affinity labeling and Western and Northern blotting studies showed that, following RA treatment, surface levels of both type I and type II receptors increased due to augmentation in their mRNA levels. The effect was dose- and time-dependent. Treatment with 1 microM RA for 15 hr increased mRNA levels of type I and II receptor threefold and eightfold, respectively. Pretreatment of BAECs with either RA or retinol lowered the concentration of TGF-beta1 required to suppress PA levels, to enhance PAI-1 levels, and to inhibit cell proliferation. Thus, retinoids may regulate cellular functions of BAECs not only by inducing the formation of active TGF-beta but also by stimulating TGF-beta receptor expression. This regulatory mechanism may sustain TGF-beta-mediated regulation of EC function at a focal site where RA is acting.

Actins↗
PubMed1998

Elevated serum levels of soluble vascular cell adhesion molecule-1 in NIDDM patients with proliferative diabetic retinopathy.

We studied 68 Japanese NIDDM patients (38 men and 30 women), aged 56.9+/-1.2 years (range 33-75 years), with a BMI of 23.1+/-0.5 kg/m2 without hypertension, dyslipidemia, and diabetic macroangiopathy for evaluating the relationship between serum soluble vascular cell adhesion molecule-1 (sVCAM-1) levels and the severity of diabetic retinopathy. Fundus examination was performed by an ophthalmologist using an ophthalmoscope, and the findings were graded as: (1) no signs of diabetic retinopathy (NDR), (2) background diabetic retinopathy (BDR), or (3) proliferative diabetic retinopathy (PDR). Serum sVCAM-1 levels were measured in duplicate by enzyme-linked immunosorbent assay using the soluble VCAM-1 KIT (R&D Systems Ltd., Ablingdon, Oxfordshire, UK). There was no difference in serum sVCAM-1 levels between patients with BDR (n = 17) and patients with NDR (n = 40) (1035.3+/-104.4 and 978.8+/-48.9 ng/ml, respectively, P = 0.8), but patients with PDR (n = 11) showed a significant increase of serum sVCAM-1 levels compared with patients with NDR (1281.8+/-166.3 and 978.8+/-48.9 ng/ml, respectively, P = 0.02). Although serum sVCAM-1 levels were correlated, not only with age but also with the known diabetic duration (r = 0.39, P = 0.001, and r = 0.40, P = 0.0007, respectively), age-adjusted sVCAM-1 levels were still significantly higher in the PDR group than in the NDR group. In contrast. serum sVCAM-1 levels were not related to the presence of diabetic nephropathy or HbA1c levels. Our results suggest that sVCAM-1 might be implicated in the development of the diabetic retinopathy, and measurement of serum sVCAM-1 levels in NIDDM patients maybe clinically useful for assessing the severity and possibly the activity of diabetic retinopathy.

Adult↗
PubMed1998

Effects of the anticancer drug cocktail "UFT" on metastatic potentials of squamous cell carcinoma (O-1N) in a hamster model.

UFT, a mixture of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) and uracil, is one of the most widely used anticancer agents. The tissue localization and the efficacy of UFT in preventing lymph node metastasis were studied in hamsters transplanted with oral squamous cell carcinoma (termed "O-1N") which has high lymph node metastatic potency. After UFT administration for 14 consecutive days, the incidence of lymph node metastasis was significantly decreased (16% vs 58%). When UFT was administered orally for 3 consecutive days to hamsters bearing O-1N, and tissue concentrations of tegafur and 5-FU were measured by gas chromatography, the value of 5-FU was significantly higher in the primary transplant tumour, cervical lymph nodes with or without metastasis, and liver, than in the normal oral tissues. When 14C-UFT(14C-tegafur + uracil, a uracil/FT molar ratio of 4) was administered orally for 3 consecutive days to hamsters bearing O-1N, the 14C-tegafur level of tissue homogenates in the buccal and metastatic tumours was within the range of normal oral tissues, but the localization of silver grains was significantly higher in tumour cells than in the oral normal tissues. The results suggest that UFT would be useful for treatment and prevention of lymph node metastasis of oral carcinomas because of the high accumulation of active metabolites in metastatic and non-metastatic lymph nodes.

Administration, Oral↗
PubMed1998

Virtual percutaneous transluminal coronary angioplasty system for an educational support system.

With the increase of ischemic diseases of the circulatory system in Japan, the necessity for cardiovascular intervention continues to increase. However, because intervention operations have been developed only recently, the education system for the corresponding specialists in our country has not been established yet. In this study, an intervention educational support system using a virtual reality (VR) technique was developed. Of course, intervention includes percutaneous transluminal coronary angioplasty (PTCA). PTCA is an operation enlarging the stenosis of the coronary artery with a balloon through a guide catheter. The technique that lets the guide wire for the PTCA balloon cross the stenosis is one of the most difficult. A simulation system for the manipulation of a torque device for the PTCA guide wire was developed with this technology for VR. In virtual space, reconstitution of the 3-dimensional coronary artery with atherosclerosis was performed, and the virtual PTCA system was produced experimentally. An interesting system was produced experimentally as a system for the training of doctors studying to become interventional specialists. After the system was combined with an Expert system for treating ischemic heart diseases, its usefulness was steadily increased. With the development of more sophisticated VR methodology in the future, a PTCA training system without using a patient will be embodied.

Angioplasty, Balloon, Coronary↗
PubMed1998

Left heart bypass using the oscillated blood flow with totally implantable vibrating flow pump.

Aiming at a totally implantable ventricular assist device (VAD), a vibrating flow pump (VFP) was developed in Tohoku University. A transcutaneous energy transmission system (TETS) using an amorphous fiber was developed for the totally implantable VAD system. The VFP works with a higher frequency than the natural heart of a biological system, a frequency of 10-50 Hz. In this research, animal experiments on left heart bypass were performed with healthy goats. Blood from the apex of the left ventricle was received and was sent to the aorta so that an adequate supporting effect of the left heart was provided. In particular, the depression effect of the left ventricle was obvious. As a result, sufficient artificial heart flow was provided. For a totally implantable type VAD, left heart bypass of almost 100% may become necessary in some situations. Therefore, apex approaches of left heart bypass may be desirable. From an anatomical consideration, an apex of the heart is suitable for the VFP of this totally implantable type. In the left heart bypass for which the apex of the heart was used, an almost 100% bypass was possible. This is a requirement that is important when waiting for recovery of sufficient cardiac function. It is also important that left heart circulation is maintained fully by an artificial heart of the complete implantation type. The VFP was considered to be useful as a totally implantable type artificial heart from the results.

Animals↗