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Biomedical subjects

Y Hamada

Publications and source records attributed to Y Hamada.

At least 163 records · Page 9Linked to original sources
PubMed1999

Effect of vitamin E and allylamine on the proliferation of cultured aortic smooth muscle cells from streptozotocin-induced diabetic rats.

To investigate the effect of vitamin E on the proliferation activity of vascular smooth muscle cells (SMCs) in diabetes mellitus, [3H]-thymidine incorporation was measured in cultured SMCs isolated from normal and streptozotocin-induced diabetic rats treated with or without vitamin E and/or allylamine. Untreated diabetic rats demonstrated significantly elevated concentrations of serum total cholesterol, triglycerides and malondialdehyde (MDA). Allylamine caused a further increase in serum MDA. Treatment with vitamin E decreased the serum concentrations of triglycerides and MDA in both allylamine-treated and -untreated diabetic rats. [3H]-Thymidine incorporation in cultured SMCs from diabetic rats was significantly increased compared with that from normal rats. SMCs from allylamine-treated diabetic rats showed an enhanced increase in thymidine incorporation compared with that from untreated diabetic rats. The increase in thymidine incorporation in SMCs from untreated and allylamine-treated diabetic rats was significantly reduced by the treatment with vitamin E. These observations suggest that vitamin E has a preventive effect on the proliferation of vascular SMCs in diabetes, and that this effect may be mediated through an enhancement of free radical scavenging.

Allylamine↗
PubMed1999

Subcellular distribution of tetrodotoxin in puffer fish liver.

The liver homogenate of puffer fish was fractionated into blood cell, nuclear, mitochondrial, microsomal and cytosol fractions by the differential centrifugation method. All the five fractions were toxic to mice, although the toxin amount was significantly high in the cytosol fraction. Analyses by HPLC and LC-FABMS demonstrated that tetrodotoxin is the major toxic principle in each fraction. These results reveal that tetrodotoxin is widely distributed in organelles in liver cells, though predominantly in the cytosol fraction.

Adult↗
PubMed1999

Gamma-band oscillations in the "barrel cortex" precede rat's exploratory whisking.

Cortical oscillations have been reported in relation to animal behavior and may have important roles in neuronal information processing such as "binding". We considered oscillatory activities in the primary somatosensory cortex of rats as a preparatory state for sensory processing and investigated the temporal relationship between gamma oscillation (25-45 Hz) onset in the somatosensory cortex (the barrel cortex) and rat's whisking as tactile exploratory behavior. The gamma oscillations of local field potentials preceded the whisking in 52/83 cases (63%). The mean lead time of the oscillations, defined as time from the oscillation onset to the whisking, was 268 ms (+/- 123, S.D.). These preceding gamma oscillations lasted to the onset of whisking. Furthermore, we investigated the temporal relationship during the other two behavioral states: a still but alert state and a state with tactile stimulation of the whiskers. In the state with tactile stimulation, gamma oscillations followed the stimulation, and in the still but alert state, significant gamma oscillation was not observed. The gamma oscillations that precede the whisking are thought to reflect anticipatory activities in the barrel cortex for the subsequent somatosensory input from the whiskers, which could represent a mechanism for rapid processing of expected sensory information.

Animals↗
PubMed1999

Relationship between the sperm motility index assessed by the sperm quality analyzer and the outcome of intracytoplasmic sperm injection.

PURPOSE: Intracytoplasmic sperm injection (ICSI) has been validated as a useful treatment in severe male-factor patients who could not achieve fertilization and live births by conventional in vitro fertilization treatment. To examine the impact of male factors on ICSI outcome, clinical laboratory data were retrospectively analyzed. METHODS: One hundred two cycles of ICSI treatment indicated by severe male-factor infertility were entered into this study. Sperm parameters including sperm motility, sperm concentration, and sperm motility index assessed by the Sperm Quality Analyzer were evaluated. RESULTS: Five hundred seventy-six metaphase II oocytes retrieved were manipulated. The normal fertilization (2 PN) rate per oocyte was 64.9 +/- 26.0% (mean +/- SD). Of the 99 transfers, 31 clinical pregnancies were obtained, yielding an average pregnancy rate of 31.3% per transfer. The mean sperm motility, sperm concentration, and sperm motility index were 20.3 +/- 16.1% (range, 0 to 50%), 18.2 +/- 25.1 x 10(6)/ml (range, < 1 to 150 x 10(6)/ml), and 31.2 +/- 45.0 (range, 0 to 220), respectively. Sperm concentration did not have a significant impact on fertilization rate by ICSI. In four cases, ICSI was performed using totally immotile sperm and the fertilization rate was 43.5%, which was significantly lower than that of some of the other sperm motility groups, and no pregnancy could be achieved. In 14 cases in which the sperm motility index assessed by the Sperm Quality Analyzer was 0, the fertilization rate (50.0%) was significantly lower than in most of the other sperm motility index groups. CONCLUSIONS: These findings suggest that in severe male-factor cases with totally immotile sperm or a sperm motility index of 0, the selection of good-quality sperm should be verified before injection.

Female↗
PubMed1999

Correlation between the motility of frozen-thawed epididymal spermatozoa and the outcome of intracytoplasmic sperm injection.

The purpose of this study was to investigate if the outcome of ICSI was influenced by epididymal sperm motility in frozen-thawed specimens. A total of 18 ICSI treatment cycles using spermatozoa retrieved by microsurgical epididymal sperm aspiration (MESA) were analysed retrospectively. Cryopreservation of epididymal spermatozoa was performed when enough epididymal aspirates were collected. Sixty-nine out of 126 oocytes injected with spermatozoa retrieved by MESA were fertilized, giving a fertilization rate of 54.8%. Out of 18 embryo transfer cycles, 6 (33.3%) achieved pregnancies. Fresh epididymal spermatozoa were used in 5 cycles while frozen-thawed epididymal spermatozoa were used in 13 cycles for ICSI. The fertilization rates were 68.6% (35/51) in the former group and 45.3% (34/75) in the latter group, respectively. There was a significant difference between the two groups (p < 0.05). In ICSI treatments using fresh epididymal spermatozoa, the cells used for injection were all motile. However, motile epididymal spermatozoa could be used in only five ICSI treatment cycles after freeze-thawing. In 6 cycles, only immotile sperm were used for injection of frozen-thawed spermatozoa. The fertilization rate in each group was 68.4% (13/19) and 31.6% (12/38), respectively. There was a significant difference between these groups (p < 0.01). These results indicate that the outcome of ICSI was influenced by sperm motility in frozen-thawed epididymal specimens. When no sperm motility could be recovered after freeze-thawing even with chemical treatments, consideration should be given to retrieving fresh epididymal spermatozoa again to achieve a better fertilization rate in such patients.

Epididymis↗
PubMed1999

Immunohistochemical expression of trk receptor proteins in focal cortical dysplasia with intractable epilepsy.

Focal cortical dysplasia (FCD), which is often associated with intractable epilepsy, is a form of abnormal structure of the cerebral cortex caused by a disorder of normal neocortical development. In such cerebral lesions obtained from four patients (two male, two female; average age 32.3 years at operation), the immunohistochemical expression of Trk receptors, which interact with neurotrophins and result in both growth and maturational changes in neuronal cells, was investigated in relation to the possible histogenesis of these lesions. In all cases, a derangement of the cortical laminar structure, dysplastic cytomegalic neurones, and large round balloon cells were the characteristic histological features. Immunohistochemically, the TrkA expression was localized in large dysplastic cytomegalic neurones, and TrkB expression was observed in large dysplastic and relatively small neuronal cells within the affected cortex. Although the exact roles of neurotrophins and their receptors in the pathogenesis of FCD remain uncertain, its development might be governed by such neurotrophic influences, and thus possibly prevent the death of abnormal neuronal cells. In addition, Trk receptors in FCDs may also play a role in establishing in the intrinsic epileptogenicity of FCDs.

Adult↗
PubMed1999

Two-dimensional autoregressive analysis of carotid artery blood flow waveform in children with isolated atrial septal defect.

BACKGROUND: The aim of the present study was to analyze the carotid artery blood flow waveform, using a two-dimensional autoregressive modeling approach and component analysis, and to determine the relation between cardiac contractility, peripheral and cerebral circulation and characteristic values of component activities of carotid artery blood flow waveform in patients with atrial septal defect (ASD), with or without congestive heart failure. METHODS AND RESULTS: We analyzed the carotid artery blood flow waveform of nine patients with ASD and 35 normal controls using a two-dimensional autoregressive modeling approach. The component of impulse response was divided into six groups according to the damping frequency: (i) group I, 0 Hz; (ii) group II, 1-5 Hz; (iii) group III, 5-8 Hz; (iv) group IV, 8-13 Hz; (v) group V, 13-17 Hz and (vi) group VI, > 17 Hz. The decrease of impulse response power-density in patients of groups I, II, III and IV and the prolongation of damping time for patients in groups I and II were particularly noticeable in two ASD patients, whose pulmonary to systemic blood flow ratio was more than 2.7 and whose left ventricular stroke volume was less than 33.1 mL/m2. The power-density of groups I and II varied with cardiac contractility and the power-density of groups III and IV varied with cerebral circulation. In contrast, the damping time of groups I and II changed with the reflection velocity from the position of arterial reflection against blood flow from left ventricle. CONCLUSIONS: These results may be influenced by the decrease in left ventricular stroke volume and velocity in arterial reflection.

Blood Circulation↗
PubMed1999

Advantage of the uncemented total hip system with three spiked socket.

Atotal hip arthroplasty was performed on 112 joints of 110 patients from November 1983 to January 1998 using three different types of uncemented total hip systems with a three spiked socket. The clinical results of 87 joints of 85 patients, followed up 5 years or more after operation, were evaluated with the comparison among the three different types (original type [JIAT] in 6, type Y in 24, and type Y2 in 57). In 73 of the 87 patients, the age at the time of the operation was more than 60. The preoperative diagnosis was osteoarthritis with acetabular hypoplasia in 61, rapidly destructive coxarthrosis in 17, and so on. We have been receiving excellent clinical results of patients who were implanted with type Y2 compared with the other types. There was no different clinical results between patients who were less than 60 and patients who were over 60. Injuries of neurovascular bundle relating to the penetration of the tip of the spike, which was a concern in this type of socket, were not encountered. The type Y2 uncemented total hip system shows an indication of being successful even if the patients have poor bone stock in acetabulum or are elderly.

Acetabulum↗
PubMed1999

Effect of a new immunosuppressant, FTY720, on joint allografts.

The immunosuppressive effects of a new agent, FTY720, on joint allografts were studied histologically in a rat model. Favorable results without side effects were obtained at a dose of 3.0 mg/kg/day. The authors believe that this agent is one of the most useful immunosuppressants in the reported experimental model.

Anastomosis, Surgical↗
PubMed1999

Relationship between severity of middle ear mucosal lesion and middle ear pneumatic space volume in patients with otitis media with effusion.

If we assume that the state of suppression of pneumatic cells is the result of suppression of pneumatic cell growth by inflammatory stimulation in the middle ear pneumatic space, it is possible to improve the state of suppression by performing sufficient treatment during the growth period of the pneumatic cells. We indwelt a tympanic membrane ventilation tube (hereinafter referred to as tube) for treatment of otitis media with effusion (OME) in child patients aged 3-13 years and investigated the following points: i) relationship between the severity of inflammation of the lamina propria of middle ear mucosal specimens (hereinafter referred to as lamina propria) collected at the time of tube indwelling and the degree of growth of the pneumatic space; and ii) changes in the pneumatic space associated with treatment by tube indwelling, which was studied by comparing the above-described mucosal severity with the pneumatic space area of 2 years after tube indwelling, and with increase in the pneumatic space volume measured periodically after tube indwelling. The results indicated that mastoid cell growth suppression is higher in patients with a higher degree of inflammatory changes in the lamina propria. In association with treatment by tube indwelling, effusion accumulated in the pneumatic space and mucosal swelling disappeared early after the treatment, or 2 months of tube indwelling. After that, in patients with severe mucosal lesion, a long time, 1.5-2 years, was found to be required for repneumatization accompanying regrowth of the temporal bone. We confirmed that the severity of inflammation of the lamina propria is deeply involved in the growth and repneumatization of the pneumatic cells.

Adolescent↗
PubMed1999

Immunohistochemical analysis of proteoglycan biosynthesis during early development of the chicken cornea.

Antibodies to core proteins of chicken corneal keratan sulfate proteoglycan and chondroitin sulfate proteoglycan were prepared and purified by use of an affinity column. Using these antibodies and monoclonal antibody 5-D-4 to keratan sulfate (commercial), the localization of proteoglycans in developing corneas (Days 5 to 17 of embryonic age and 2 days after hatching) was determined immunohistochemically. Keratan sulfate proteoglycan antigen was not detected in cornea on Day 5, but it was detected uniformly over the whole stroma on Day 6, ca. 12 h after invasion of the primary stroma by mesenchymal cells. The absence of the antigen in cornea of Day 5 was confirmed by Western blotting of the corneal extract. Immunohistochemistry with 5-D-4 antibody revealed that the keratan sulfate chain was undersulfated in corneas of Days 6 to 7, because the staining was much weaker than that in cornea of Day 8. In addition, keratan sulfate proteoglycan antigen was detected uniformly over the whole stroma on Days 7 to 17 and 2 days after hatching, but not in the epithelial layer on Day 13 and after: because the epithelial layer was clearly not observed on photomicrographs until Day 13, it is not known whether keratan sulfate proteoglycan was synthesized by the epithelium during Days 6 to 12. In contrast, chondroitin sulfate proteoglycan antigen was detected in cornea on Day 5 and also, like keratan sulfate proteoglycan, uniformly over the whole stroma on Day 6 through 2 days after hatching. Furthermore, the chondroitin sulfate proteoglycan was not detected in the epithelial layer on Day 13 and after. These results show that keratan sulfate proteoglycan is synthesized by the stromal cells which invade the primary stroma between Day 5.5 and 6, while chondroitin sulfate proteoglycan is synthesized by epithelial and/or endothelial cells before the invasion, and also by the stromal cells after the invasion.

Animals↗
PubMed1999

Mutation in ankyrin repeats of the mouse Notch2 gene induces early embryonic lethality.

Notch family genes encode transmembrane proteins involved in cell-fate determination. Using gene targeting procedures, we disrupted the mouse Notch2 gene by replacing all but one of the ankyrin repeat sequences in the cytoplasmic domain with the E. coli (beta)-galactosidase gene. The mutant Notch2 gene encodes a 380 kDa Notch2-(beta)-gal fusion protein with (beta)-galactosidase activity. Notch2 homozygous mutant mice die prior to embryonic day 11.5, whereas heterozygotes show no apparent abnormalities and are fully viable. Analysis of Notch2 expression patterns, revealed by X-gal staining, demonstrated that the Notch2 gene is expressed in a wide variety of tissues including neuroepithelia, somites, optic vesicles, otic vesicles, and branchial arches, but not heart. Histological studies, including in situ nick end labeling procedures, showed earlier onset and higher incidence of apoptosis in homozygous mutant mice than in heterozygotes or wild type mice. Dying cells were particularly evident in neural tissues, where they were seen as early as embryonic day 9.5 in Notch2-deficient mice. Cells from Notch2 mutant mice attach and grow normally in culture, demonstrating that Notch2 deficiency does not interfere with cell proliferation and that expression of the Notch2-(beta)-gal fusion protein is not toxic per se. In contrast to Notch1-deficient mice, Notch2 mutant mice did not show disorganized somitogenesis, nor did they fail to properly regulate the expression of neurogenic genes such as Hes-5 or Mash1. In situ hybridization studies show no indication of altered Notch1 expression patterns in Notch2 mutant mice. The results indicate that Notch2 plays an essential role in postimplantation development in mice, probably in some aspect of cell specification and/or differentiation, and that the ankyrin repeats are indispensable for its function.

Animals↗
PubMed1999

Effects of single administration of a phosphodiesterase III inhibitor during cardiopulmonary bypass: comparison of milrinone and amrinone.

The effects of phosphodiesterase III (PDE III) inhibitors administered after aortic declamping during cardiopulmonary bypass (CPB) for open heart surgery were investigated. Ten patients (group M) were administered milrinone (50 microg/kg) after aortic declamping during CPB, 10 patients were administered amrinone (1 mg/kg) at the same time during their surgery (group A), and 10 patients served as controls with no drug administered (group C). Soon after bolus infusion of the PDE III inhibitor, perfusion pressure dropped significantly in groups M and A. However, after release of CPB and at the end of surgery, there was no difference in aortic pressure between the 3 groups. There were also no differences between the groups in heart rate, pulmonary artery pressure, and pulmonary capillary wedge pressure. After weaning from CPB, the cardiac index was high and systemic vascular resistance index was low in groups M and A. There were no significant differences in the need for additional catecholamines and time for rewarming between groups. No adverse reactions were observed. A single administration of a PDE III inhibitor during CPB was useful for post-CPB management of patients undergoing open heart surgery. Amrinone reduced perfusion pressures more than milrinone, but cardiac indices and aortic pressures after weaning from CPB showed no differences between group M and group A patients.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Salt water promotes hypertension in Dahl-S rats.

Hypertension was induced in Dahl-salt-sensitive (Dahl-S) rats by administering salt in drinking water. Control rats receiving tap water did not show a significant change in blood pressure or abnormalities in the kidney. Rats receiving 0.5% NaCl solution developed moderate hypertension and renal lesions. Rats receiving 1.0% NaCl solution showed prominent and increasing hypertension and severe renal damage. This method of salt administration should be simpler than administration in the diet as a means of promoting renal hypertension. The lower concentration salt water caused chronic mild hypertension in Dahl-S rats, and may serve as a useful model for progressive hypertension.

Animals↗
PubMed1999

A protein kinase C-beta-selective inhibitor ameliorates neural dysfunction in streptozotocin-induced diabetic rats.

Increased protein kinase C (PKC) activity has been implicated in the pathogenesis of diabetic retinopathy and nephropathy. However, the role of PKC in diabetic neuropathy remains unclear. The present study was conducted to compare the effect of PKC inhibition by a PKC-beta-selective inhibitor, LY333531 (LY), on diabetic nerve dysfunction with that of an aldose reductase inhibitor, NZ-314 (NZ). Streptozotocin-induced diabetic rats were treated with or without LY and/or NZ for 4 weeks, and motor nerve conduction velocity (MNCV), coefficient of variation of R-R interval (CVR-R), sciatic nerve blood flow (SNBF), peak latencies of oscillatory potentials on electroretinogram, PKC activities in membranous and cytosolic fractions of sciatic nerves, and polyol contents in the tail nerves were measured. Untreated diabetic rats demonstrated delayed MNCV, decreased CVR-R, reduced SNBF, and prolonged peak latencies of oscillatory potentials. Treatment with LY as well as NZ prevented all these deficits in diabetic rats. There were no significant differences in PKC activities in membranous or cytosolic fractions of sciatic nerves between normal and diabetic rats. Treatment with neither LY nor NZ altered PKC activities. Nerve myo-inositol depletion in diabetic rats was ameliorated not only by NZ, but also by LY. These observations suggest that inhibition of PKC-beta by LY may have a beneficial effect in preventing the development of diabetic nerve dysfunction, and that this effect may be mediated through its action on the endoneurial micro-vasculature.

Aldehyde Reductase↗
PubMed1999

[Eustachian tube function of adhesive tympanum--pre and post operative evaluation].

We examined the eustachian tube function of 48 patients with adhesive tympanum who had undergone operations. Preoperative tubal openings were observed and determined in 57% of these cases by the dynamic movement of the tympanic membrane, 35% by the impedance method, and 74% by the sonotubometry and was found to be lower than in healthy subject. Furthermore the tubal opening duration in sonotubometry was significantly shortened in patients with adhesive tympanum as compared to healthy subjects. However, in a few cases of adhesive tympanum, tubal opening was prolonged remarkably, and indicated a mixed tendency of stenotic and patulous types. Postoperative tubal opening was not seen in 90.9% of the cases as determined by the inflation-deflation test. Mucociliary function was poor in 81.3% of the cases. No remarkable differences were seen between cases of total adhesion and those of posterosuperior quadrant adhesion by any method. The condition of the tympanic membrane and the tympanic cavity after operation, and the eustachian tube function were not correlated in some cases and indicated possible involvement of other factors.

Adolescent↗
PubMed1999

[Aldose reductase].

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Aldehyde Reductase↗