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Biomedical subjects

Y Asai

Publications and source records attributed to Y Asai.

At least 163 records · Page 9Linked to original sources
PubMed1993

Effect of a Ca2+ entry blocker, nilvadipine, on hearing disturbances and equilibrium dysfunction caused by microcirculatory disorders of the rat inner ear.

We evaluated the effects of Ca2+ entry blockers, nilvadipine and flunarizine, on microcirculatory disorders of the inner ear and on blood flow in the inner ear of rats. Under sodium pentobarbital anesthesia, the middle ear was opened by a ventrolateral approach. A green light (wave length 540 nm) was applied to the cochlea or the vestibule to induce a hearing disturbance or equilibrium dysfunction as a result of inner ear microcirculatory disorders, while rose bengal solution was infused intravenously. In a hearing disturbance model, a compound cochlear nerve action potential was recorded by electrocochleography every minute after the beginning of illumination. The sound stimulus was an 8 kHz sine wave 100 dB normal hearing level. The action potential was calculated 128 times. The action potential disappeared about 12 min after the beginning of illumination. In another model of equilibrium dysfunction, the photoillumination was applied for 40 min under the infusion of rose bengal. The behavior of rats was observed in the swimming test and nystagmus was recorded 24 h after the completion of photoillumination. In a separate experiment, blood flow in the inner ear was measured with a laser Doppler flowmeter under sodium pentobarbital anesthesia. In this study, both nilvadipine and flunarizine prolonged the time required for complete suppression of the action potential, prevented equilibrium dysfunction in the swimming test and reduced the occurrence of nystagmus. Flunarizine significantly increased inner ear blood flow and nilvadipine failed to decrease blood flow in the inner ear, despite a reduced systemic blood pressure. In conclusion, Ca2+ entry blockers may prevent microcirculatory disorders of the inner ear in rats.

Acoustic Stimulation↗
PubMed1993

An animal model for hearing disturbance due to inner ear ischemia: photochemically induced thrombotic occlusion of the rat anterior inferior cerebellar artery.

A photochemical reaction between intravenous rose bengal and xenon light was used to induce a selective thrombus in the rat anterior inferior cerebellar artery (AICA). Compound action potentials (CAPs) were recorded by electrocochleography and cochlear blood flow (CBF) was monitored by laser Doppler flowmetry. Photothrombotic occlusion of the AICA caused inner ear ischemia to various degrees with or without alterations of the CAP. With use of this model we investigated the critical range of the CBF for preserving cochlear function, represented by the CAPs induced with 8 kHz half-wave of sinusoid at 100 dB SPL. Results then showed that a CBF range between 26.7% and 42.9% of baseline was somewhat critical for maintenance of cochlear function in an acute phase of ischemia. Pretreatment with heparin significantly delayed thrombotic occlusion of the AICA in a dose-dependent manner. Further use of our model for inner ear ischemia may be useful for studying pathophysiology and pharmacological therapy of cochlear disturbances subsequent to circulatory disorders.

Action Potentials↗
PubMed1993

Role of thromboxane A2 in a microcirculation disorder of the rat inner ear.

Since thromboxane (TX) A2 causes vasoconstriction and platelet aggregation, we evaluation the effect of a TXA2 receptor antagonist (vapiprost) and a TXA2 synthetase inhibitor (Y-20811) on a microcirculation disorder in the rat inner ear that was induced by a photochemical reaction between an intravenous injection of rose bengal (RB) and green light. A gradual decrease of the cochlear action potential (CAP) to an 8 kHz sound stimulus was measured with an electrocochleogram and occurred after the RB injection. The CAP then disappeared 5 min after the injection of RB. Both vapiprost and Y-20811 significantly prolonged the time required to complete suppression of the CAP as compared with saline as control. These findings indicate that TXA2 may play an important role in microcirculation disorders in the rat inner ear.

Action Potentials↗
PubMed1993

A simple and reproducible cerebral thrombosis model in rats induced by a photochemical reaction and the effect of a plasminogen-plasminogen activator chimera in this model.

In this study a new model of cerebral ischemia, based on a middle cerebral artery (MCA) thrombosis in rats is described. Furthermore, the effect of the novel plasminogen activator (SUN9216), a plasminogen-plasminogen activator chimera, comprising the fibrin kringle 1 domain of a plasminogen, and the two kringles, and the serine protease domains of wild-type tissue plasminogen activator (t-PA), including a modification of the mannose glycosylation site on the kringle 1 of t-PA (PK1de1FE1X), was studied in this model. In the newly described model of thrombotic cerebral ischemia, an occlusive thrombus occurred usually within 8 min in the MCA as a consequence of an endothelial injury subsequent to a photochemical reaction between a systemically administered photosensitive dye (rose bengal) and a transillumination of the MCA with a high-intensity green light with a wavelength of 540 nm. The study was quantitated by means of pathological examination of the MCA and the brain. A platelet-rich thrombus was observed in the MCA using electron microscopical analysis based on ion beam bombardment. At 24 hr after induction of the thrombus, the brain was removed from 13 control animals, nine coronal sections were stained from each brain with triphenyltetrazoliumchloride (TTC), and the ischemic area was quantitated. A constant area of infarction was observed in the cortex and the lateral part of the basal ganglia. In a second group (n = 8), at 1 or 8 weeks after induction of the thrombosis in the MCA, the coronal sections were stained with hematoxylin and eosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Regulation of hsp70 synthesis induced by cupric sulfate and zinc sulfate in thermotolerant HeLa cells.

Upon exposure to the heavy metals copper and zinc, a large amount of 70,000-Da heat shock protein (hsp70) was synthesized in normal, non-thermotolerant (NT) HeLa cells, whereas only a little increase of hsp70 synthesis was observed in thermotolerant (TT) cells. To determine the inhibition mechanism of hsp70 induction in the TT cells, we first analyzed the hsp70 mRNA of these cells. Hsp70 mRNA in the NT cells increased immediately after exposure to these metals. In TT cells, however, the increase of hsp70 mRNA was delayed, even though it eventually increased to a similar or slightly lower level compared with NT cells. Further analysis of the activation of heat shock transcription factor (HSF) showed that a significant activation of HSF was observed immediately after exposure to these metals in the NT cells, whereas the activation of HSF was initially repressed in the TT cells. Thus, the decreased induction of hsp70 synthesis observed in the TT cells seemed to be due to the reduced translation of hsp70 mRNA and also in part to the reduced activation of HSF. Furthermore, by the gel mobility shift assay using anti-hsp70 antibody, the association of copper- and zinc-activated HSF with hsp70 was observed in both NT and TT cells. The amount of HSF-hsp70 complex was prominent in TT cells, in which the hsp70 content was 5 to 10 times higher than that in the NT cells. These findings strongly suggest that the activity of HSF is negatively regulated by hsp70 in the TT cells.

Base Sequence↗
PubMed1993

Effect of ibudilast on microcirculation thrombosis in rat inner ear.

The effect of ibudilast (0.1, 0.3 mg/kg), which has cerebral vasodilating and antiplatelet effects, was evaluated in two models of rat inner ear microcirculation thrombosis by using the photochemical reaction between green light (wave length: 540 nm) and intravenous injection of rose bengal. Furthermore, the inner ear blood flow was measured by a laser-Doppler flowmeter. In the hearing disturbance model, under anesthesia, the compound action potential of the cochlear nerve (AP) was measured by an electrocochleogram. The sound stimulus was an 8-kHz sine wave at 80 dB SPL. The AP was calculated 128 times. In the controls, the AP disappeared about 4 min after the intravenous injection of rose bengal (20 mg/kg). The time required to completely suppress the AP in the animals treated with ibudilast (0.1, 0.3 mg/kg) was significantly prolonged as compared with that in the controls. In the equilibrium dysfunction model, ibudilast (0.1, 0.3 mg/kg) reduced the time of abnormal swimming in the swimming test 24 hr after the completion of photo-illumination. Ibudilast (0.3 mg/kg) increased the inner ear blood flow during the 10-min observation period as compared with the controls, while it did not affect the mean blood pressure. In conclusion, ibudilast increased the inner ear blood flow and was effective in two models of rat inner ear microcirculation thrombosis.

Animals↗
PubMed1993

[Statistical analysis on the cases of thyroid papillary carcinoma].

Statistical analysis was performed on the postoperative recurrence of forty four patients with thyroid papillary adenocarcinoma, who underwent radical surgery in the Department of Otolaryngology, Hamamatsu University Hospital from January 1978 to March 1991. In this study, we defined a new factor called "Operative Radicality index (OR index)" and analyzed the data with a multivariate analysis (Cox model). The result showed that the risk of postoperative recurrence was significantly affected by the age, the size of tumor and the OR index. The postoperative five-year cumulative recurrence rate was approximately 10% in the group of patients whose lateral neck regions were systematically dissected only when any metastatic lymph nodes were clinically detected within the region, in addition to the routine anterior neck dissection, and 70% in the group of patients whose metastatic lymph nodes in the lateral neck region were partially removed, but 6% in the group of N0 patients who did not undergo lateral neck dissection because no nodal metastases were detected even in the operative findings. Considering the quality of postoperative life, we concluded that in the primary surgery for the thyroid papillary adenocarcinoma, the lateral neck dissection should be applied to only the regions with metastatic nodes detected preoperatively or during operation, in addition to the routine anterior neck dissection. And the OR index was useful for the statistical analysis with regard to the policies of treatment and the prognosis.

Adenocarcinoma, Papillary↗
PubMed1992

A new model of equilibrium dysfunction in the rat induced by photochemical damage to the inner ear's microcirculation.

A new photochemical method was employed to damage the inner ear microcirculation in the rat. Under pentobarbital anesthesia, the middle ear was exposed by a ventral approach and the tympanic membrane and the malleus and incus were removed. The vestibule was then illuminated by a filtered xenon light (wave length: 540 nm) while rose bengal was infused intravenously. Microscopic examination revealed disintegration of the hair cells in the vestibule. Changes could be prevented by pretreatment with intravenous acetylsalicylic acid (ASA) or heparin. Twenty-four hours after the completion of photo-illumination the rats exhibited nystagmus toward the intact ear and showed rolling during the swimming test, both signs of equilibrium dysfunction. These findings were inhibited by ASA or heparin pretreatment. Our present results indicate that our method causes a photochemically induced occlusion in the rat's inner ear microcirculation and may be useful for evaluating the various effects of drugs on the inner ear.

Animals↗
PubMed1992

[A case report of patch aortoplasty for supravalvular aortic stenosis associated with Williams syndrome].

A 15-year-old girl underwent patch aortoplasty for supravalvular aortic stenosis in association with Williams syndrome. Pressure gradient of before and after stenosis of the aorta decreased from 104 mmHg to 16 mmHg at the postoperative catheterization. Angiography after the operation showed no stenosis. Postoperative course was excellent and discharged on 14th postoperative day. The problems of the operation of supravalvular aortic stenosis were discussed.

Adolescent↗
PubMed1992

[Closure of median sternotomy incision with EPTFE sutures].

EPTFE (CV-0) suture was utilized for closure of median sternotomy incision in 100 patients under 6 years of age who underwent open heart surgery. During 3 years follow up, except for one dislocation of sternum, all patients have healed without complication. EPTFE suture is swanged to a needle that has the same diameter as the thread, which reduces bleeding from the needle hole. It is radiologically lucent, and therefore does not disrupt chest X-ray, angiography or MRI investigations, in contrast to sternal wires. In addition, in the case of life threatening postoperative complication, EPTFE suture allows rapid and simple access to the heart, without the need to cut wires. We concluded that EPTFE suture can be utilized for closure of median sternotomy in patients under the age of six, without an increased risk of postoperative or long-term complications.

Child, Preschool↗
PubMed1991

Clinico-pathological studies on the tissue reactions of human pulp treated with various kinds of calcium phosphate ceramics.

The aim of this study was to evaluate the clinical values of calcium phosphate ceramics from the biological point of view. Two kinds of calcium phosphate ceramics, tricalcium phosphate (TCP) and hydroxyapatite (HAP) ceramics with a low sintering temperature (LT) and a high sintering temperature (HT), were applied to exposed pulp wounds in ninety healthy human teeth. Each group was further subdivided into 2 groups with selected granule diameters of 5 microns (S) and 40 microns (L), and investigated clinico-pathologically. Clinically, cases showing some kinds of discomfort symptoms comprised 3/15 of the TCP (S) group, 3/15 of the TCP(L) group, 3/15 of the LT(S) group, 4/15 of the LT(L) group, 2/15 of the HT(S) group, and 3/15 of the HT(L) group. The symptoms were generally slight or very slight and disappeared within eight days in the LT(S) group. Histo-pathologically, inflammatory reactions were observed within 2 weeks. Traumatic injury caused by surgical wound or by mechanical irritation from the materials produced various pathological changes. After the treatment, pulp manifested reparative changes such as cicatrization, formation of new denticles, and dentin apposition on pulp-chamber walls. In many cases, TCP and HAP produced similar effects on human dental pulp. In the TCP(S), the LT(S), and HT(S) groups, a calcified matrix had appended by 3 weeks. In TCP(L), LT(L), and HT(L) groups, the matrix had appended from 3 to 6 weeks. Calcified matrix formation in the LT group was slightly less than in that in the HT of HAP group. In a few cases, complete dentin bridges formed over the exposed pulp surfaces. These results suggest that HAP (both LT and HT) and TCP ceramics are biocompatible and do not harm human dental pulp. These ceramics were found to be clinicopathologically effective in biologically protecting exposed human dental pulp and useful as basic materials in endodontic therapy.

Adolescent↗
PubMed1991

[Experience of extracorporeal shock-wave lithotripsy for the urolithiasis in horseshoe kidney].

At Osaka City University, 1,987 patients with urolithiasis have been treated by extra-corporeal shockwave lithotripsy (ESWL) during a four-year period. We treated 5 patients with horseshoe kidney and the obtained results were analyzed retrospectively. Three of these patients, who had a solitary stone could successfully be treated by ESWL as monotherapy. One who had multiple stones required transurethral lithotripsy after ESWL due to stone-street. The remaining 1 patient who had undergone heminephrectomy developed perirenal hematoma after ESWL, which spontaneously disappeared without any specific treatment. We discuss the special care related to the use of ESWL in the horseshoe kidney.

Adult↗
PubMed1991

[Surgical treatment of pulmonary atresia with intact ventricular septum in infancy--analysis of right ventricular growth potential after pulmonary valvotomy].

Our surgical experience involving pulmonary atresia with intact ventricular septum (PPA) between the years 1981 and 1989 is reviewed. Twelve infants aged 3 days to 11 months were studied for right ventricular growth potential with angiocardiography and hemodynamics after transventricular pulmonary valvotomy (TVPV). Ten infants were divided into two groups, 5 infants (Group I) were treated with TVPV only, and the other 5 infants (Group II) required additional surgery after the initial operation (TVPV in 2 cases and TVPV with shunt in 3 cases). Post-operative RV growth potential was evaluated with right ventricular index (RVI) based on the tricuspid valve annulus, right ventricular inlet, and right ventricular outlet dimensions, and with tricuspid annular index (TVI) based on the tricuspid valve annulus normalized by aortic diameter. Follow-up (3-69 months after initial operation) studies demonstrated that the RV cavity increased in Group I (RVI of 15.75 +/- 2.92 preoperatively versus 17.00 +/- 1.57 postoperatively, TVI of 3.04 +/- 0.63 versus 3.85 +/- 0.40). In contrast, the RV cavity in Group II demonstrated a lack of growth (RVI of 9.24 +/- 2.60 versus 9.85 +/- 2.76, TVI of 1.46 +/- 0.46 versus 1.70 +/- 0.80). PPA infants with RVI greater than 11 have been treated successfully with TVPV alone, which may maximize the potential for RV growth, but infants with RVI less than 11 have not experienced RV growth + postoperatively and, therefore, have required second intracardiac operations.

Angiocardiography↗
PubMed1990

[Histopathological studies of periodontal tissue reactions following apical plugging with autogenous dentin chips].

After treating the infected canals, we investigated to determine the influence of autogenous dentin chips accidentally applied as filling in the root apexes. Materials were 15 mandibular premolars and molars obtained from healthy, mature dogs. According to standard procedures, after pulp extirpation, canals were temporarily filled with sandarac cotton pellets and left otherwise untreated for 4 weeks. At this time, the degree of infection was ascertained. After root-canal enlargement, root canals were filled with No. 55 gutta-percha points; and a sealer (Neotriozinc Paste, AH26, or Sealapex) was applied. The animals were sacrificed at the conclusion of either a short term (2 weeks) or a long term (16 weeks), and histological studies were performed. Conclusions In short-term specimens, no formation of new hard tissue was observed at the apical dentino-cemental junction; and inflammatory changes in the periapical soft tissue were remarkable. In long-term specimens, hard-tissue formation had resulted in apical closure in 6 out of 8 instances; and periapical inflammatory changes had decreased. Relations between dentin-chip density and histopathological conditions were as follows: In most of the specimens that were evaluated as good, dentin chips were very densely applied. Insufficient numbers of dentin chips produced poor results. In other words, dense applications of dentin chips result in good prognoses. Consequently, when root-canal enlargement has been adequately performed, application of dentin chips to the apex of infected canals stimulates hard-tissue formation resulting in biological apical closure. In infected canals, however, the degree to which dentin chips are infected can be a major factor.

Animals↗
PubMed1990

[Consideration of management of type B dissecting aneurysms of the thoracic aorta: clinical comparative study between surgical and medical treatments].

Between 1970 and 1989, 116 patients with type B dissecting aneurysms of the thoracic aorta were seen in our institution and affiliated hospitals. The patients were classified into 5 groups according to the acuity (acute vs chronic) and modes of therapy (surgical vs medical). Group I: 24 patients with acute B dissection were treated surgically during the acute stage. Group II: 21 patients with acute B dissection were initially treated with intensive medical therapy and followed by elective operation during the subacute stage. Group III: 22 patients with acute B dissection were treated medically. Group IV: 42 patients with chronic dissection were treated surgically. Group V: 7 patients with chronic B dissection were treated medically. The 5-year survival rates including early mortality were 70.5 +/- 9.4% for Group I, 88.9 +/- 7.5% for Group II, 68.3 +/- 11.2% for Group III, 64.6 +/- 8.4% for Group IV and 71.4 +/- 17.1% for Group V. The 5-year survival rates of Group II was significantly better than those of Group I, III and IV, respectively. The present data suggests that acute type B dissection without complications (bleeding, visceral or lower limbs ischemia) should be treated initially with intensive medical therapy and then followed by elective operation during the subacute stage, if the false lumen were not thrombosed.

Adult↗
PubMed1989

[The c protein fractions of group B streptococci: its distribution and relation to heat-labile antigens for the agglutination method].

Distribution of the c protein fractions of group B streptococci and relation to heat-labile antigens for agglutination were investigated. The results were summarized as follows: 1. Analysis of antigenicity of the c protein in group B streptococcal strains isolated revealed that 74% of the type Ia/c strains carried only alpha antigen, and 76% of the type Ib/c strains contained both alpha and beta antigens. Component of the c protein fractions in most of type Ia/c strains isolated was different from that in reference strains. 2. Of 37 Ia/c alpha strains, 45.9% were determined non-typable, 32.4% were Ia/W, 13.5% were Ia/S, and 8.1% were Ia/Q in the agglutination for heat-labile antigens. Of 8 Ia/c alpha beta strains, 87.5% were Ia/Q, and 12.5% were Ia/SW. Of 5 Ia/c beta strains, 60% were Ia/Q, and 40% were Ia/QW. Of 19 Ib/c alpha beta strains, 68.4% were Ib/-, and 31.6% were Ib/S. Of 5 Ib/c alpha strains, 60% were Ib/-, and 40% were Ib/S. One Ib/c beta strain was Ib/-. 3. Because trypsin-sensitive portions of the beta antigens were lost, preparation of antigens for agglutination by pancreatic digestion could not exactly reflect results of the precipitation method.

Agglutination Tests↗