Biomedical subjects

Y Yazawa

Publications and source records attributed to Y Yazawa.

At least 55 records · Page 3Linked to original sources

PubMed1995

[The influence of rates of pressure change on pressure-induced vestibular response in guinea pigs].

Ambient pressure changes are known to induce vertigo and bodily disequilibrium, e.g. alternobaric vertigo. It is predicted, based on clinical observations of such vertigo, that the rates of pressure change are responsible for alternobaric vertigo. The aim of the present study was to clarify the influence of the rates of pressure change on the activities of primary vestibular neurons using an animal model of alternobaric vertigo. The responses of primary vestibular neurons to middle ear pressure stimuli were investigated in guinea pigs under 2 different rates of pressure change (+/- 50, +/- 100 mmH2O/sec). The following results were obtained. 1. The response rates and the gains of firing rates with pressure stimuli were larger under +/- 100 mmH2O/sec than under +/- 50 mmH2O/sec. 2. The onsets of responses to pressure stimuli were faster under +/- 100 mmH2O/sec than under +/- 50 mmH2O/sec. The results obtained in the present study reveal that vestibular activities are altered by the rates of ambient pressure change.

Animals↗

PubMed1994

Swimming test for evaluating vestibular function in guinea pigs.

A swimming test was used to evaluate vestibular function in guinea pigs. We first observed tracings of the swimming patterns of 20 healthy guinea pigs to establish the normal range. Then the same test was used in a group of 49 guinea pigs with endolymphatic hydrops induced by immunologic techniques. They did not show spontaneous nystagmus or body deviation while walking, but a total of 20 out of 49 animals displayed abnormal swimming patterns, with 8 swimming clockwise and 4 counterclockwise. This swimming test is easily able to detect mild vestibular dysfunction in guinea pigs, and can be repeated, so that we consider it useful for examining vestibular function in these animals.

Animals↗

PubMed1994

Electrocochleography in experimental endolymphatic hydrops.

This study investigated whether dominant negative summating potential (DNSP) is absent at all stages of induced hydrops development, including the early stages of hydrops formations. Electrocochleography (ECoG) was done 3 days to 20 weeks after obliteration of the endolymphatic sac in guinea pigs, by electrodes attached to the cochlear bony wall on the scala vestibuli of the basal turn. DNSP was noticed only during the early stages of endolymphatic hydrops formation, before hydrops was fully developed. There was no DNSP when the distension of Reissner's membrane was marked. Increased endolymphatic pressure and/or changes in biochemical composition were thought to be the causes of DNSP.

Action Potentials↗

PubMed1994

Endolymphatic sac blood flow versus cochlear blood flow following intravenous administration of isosorbide in guinea pigs.

Endolymphatic sac (ES) blood flow (ESBF) and cochlear blood flow (CBF) were measured in different groups of guinea pigs by laser-Doppler flowmetry (Advance Laser Flowmeter, Model ALF 2100) after the intravenous administration of 70% isosorbide (1.6 ml/kg). The measurements were made under general anesthesia with intraperitoneal pentobarbital sodium. Respiration was controlled by a respirator after tracheotomy, and blood pressure was monitored through the femoral artery (Gould Statham P23 ID Pressure Transducer). For ESBF measurements, a probe was placed on the right ES after entering the posterior cranial fossa via the dorsal approach. For CBF measurements, a probe was placed on the basal turn of the right cochlea via the ventral approach. Isosorbide was administered intravenously through the jugular vein for 60 s. Both ESBF and CBF increased immediately after administration, reached a peak within 3-6 min and decreased gradually to their initial baseline levels in 11-15 min. Both blood flow changes almost always corresponded to systemic blood pressure changes, although a slight delay was observed in blood pressure compared to the blood flow. The magnitude of the CBF response tended to be greater than that of the ESBF response (p < 0.1). This may result from the anatomical differences in the two blood supplies, i.e., from the vertebral artery (CBF) and the external carotid artery (ESBF).

Animals↗

PubMed1994

Computerized tomography of the petrous bone in Menière's disease.

High resolution transverse axial computerized tomograph (CT) encompassing the lateral semicircular canal (LSC) was used to measure the size of the petrous bone in ears with bilateral (n = 13) and unilateral (n = 38) Menière's disease, and in ears with unilateral chronic otitis media (n = 25) as a control group. Measurements were made of the following 4 distances in the petrous bone; A: the distance between the posterior semicircular canal (PSC) and the posterior petrous surface (PPS) (P-P distance), B: the distance between the PSC and the LSC (P-L distance), C: the distance between the vestibule and the PPS (V-P distance), and D: the distance between the PSC and the anterior margin of the sigmoid sinus (P-S distance). The P-P and the V-P distances were significantly shorter in ears with Menière's disease, especially in ears with bilateral Menière's disease compared to the nonaffected ears in unilateral Menière's disease or ears with chronic otitis media. This tendency was clearer in the P-P distance than in the V-P distance. The P-L and P-S distances did not show any statistical difference between groups. The results indicate that bone development between the PSC and the PPS and between the vestibule and the PPS, which usually contains the endolymphatic duct and sac, is significantly poorer in ears with Menière's disease than in ears with chronic otitis media. Hypoplasia of the retrolabyrinthine region may be an important factor in the pathogenesis of endolymphatic hydrops.

Cephalometry↗

PubMed1994

Computerized tomographic findings in endolymphatic sac surgery in Menière's disease.

We correlated the surgical findings and the findings of computerized tomographic scans of the temporal bone in 38 ears from 38 patients with Menière's disease (31 unilateral and 7 bilateral) treated by endolymphatic sac (ES) drainage surgery between 1986 and 1991. At surgery, the position and size of the ES were recorded. The position of the ES was classified as one of three types according to Arenberg's parameters (type I, type II and type III) and the size of the ES was classified as large, intermediate or small. Scans encompassing the lateral semicircular canal were used to measure the minimum distance between the posterior semicircular canal and the posterior petrous surface (P-P distance). The P-P distance in 23 type III cases was significantly shorter (2.25 mm) than in 13 type II cases (3.39 mm). The P-P distance in 9 large-sized ES cases was significantly longer (3.99 mm) than in 20 intermediate-sized ES cases (2.40 mm) and in 9 small-sized ES cases (1.92 mm). Significant correlations were found in patients with Menière's disease between a short P-P distance and type III ES position, and also between a short P-P distance and an intermediate or small-sized ES.

Cephalometry↗

PubMed1992

Fibrinolysis and fibrinogenolysis in patients with thrombotic disease.

In order to assess the fibrinolytic state in thrombotic disease, plasma levels of fibrin degradation products (FbDP) and fibrinogen degradation products (FgDP) were measured in 126 patients with a variety of thrombotic diseases. Mean plasma concentrations of both FbDP and FgDP were significantly elevated in patients with thrombotic disease as compared with healthy subjects. Plasma concentrations of FgDP were positively correlated with FbDP (r = 0.667, P less than 0.001). When analysed according to the disease categories, the magnitude of elevations of FbDP and FgDP was most prominent in venous thrombotic disease such as deep vein thrombosis and pulmonary embolism. These findings indicate that fibrinolysis is accelerated in patients with thrombotic disease and that fibrinolysis is frequently accompanied by some fibrinogenolysis in these patients.

Enzyme-Linked Immunosorbent Assay↗

PubMed1991

Computed tomographic findings around the vestibular aqueduct in Menière's disease.

High resolution transverse axial CT encompassing the lateral semicircular canal was used to study the visualization of the vestibular aqueduct and to measure the minimum distance between the posterior semicircular canal and the posterior petrous surface (P-P distance) in Meniere's disease and chronic otitis media. The results indicate that the development of the bone between the posterior semicircular canal and the posterior petrous surface, which usually contains the endolymphatic sac, is significantly poorer in affected ears than in nonaffected ears in unilateral Meniere's disease, and much poorer than in chronic otitis media.

Female↗

PubMed1990

Clinical factors relating to the positive glycerol test for Ménière's disease.

In order to investigate the clinical factors relating to positive glycerol tests, 51 patients with Ménière's disease were subjected to a complete battery of audiometric examinations, including the short increment sensitivity index, Bekesy, alternate binaural loudness balance, speech discrimination and pure-tone audiometry tests, both before and after glycerol ingestion. The correlation between positive glycerol tests and vestibular response, cochlear symptoms, age at onset and disease duration was investigated. High ratios of positive tests were obtained in the following categories of patients with Ménière's disease: elderly patients with vertiginous attacks; patients with high-level hearing loss; nystagmus patients, and patients with fluctuating hearing loss.

Adult↗

PubMed1990

Bilateral endolymphatic hydrops in Menière's disease: review of temporal bone autopsies.

The wide range in incidence rates reported for bilateral Meniere's disease results mainly from the lack of established clinical criteria for bilaterality, and from follow-ups of varying duration. In order to help determine a reasonable bilateral involvement rate, we examined histologic reports of temporal bones with endolymphatic hydrops. We reviewed the literature on temporal bone autopsies from 1938 to 1988, and selected 72 cases for histologic examination. Of the 72 cases, 67 (93%) showed endolymphatic hydrops, 2 (2.8%) showed collapse, and 3 (4.2%) showed membranous labyrinths of normal appearance. Twenty of the 67 endolymphatic hydrops cases (29.9%) displayed bilateral involvement, suggesting a rate of bilaterality in Meniere's disease of approximately 30%.

Edema↗

PubMed1990

The relevance of psychosocial factors in acute ischemic heart disease. A case-control study of a Japanese population.

We investigated, by case-control study, the relevance of psychosocial factors on the prevalence of acute ischemic heart disease (IHD) in middle aged Japanese men. We questioned 109 acute IHD patients and 80 individuals in an age-adjusted sampled control group. Multiple logistic regression analysis showed the following statistically significant factors: hypertension (odds ratio 4.01, p less than 0.001), Type A behavior pattern (2.25, p less than 0.05) and high job demand (2.23, p less than 0.02). No direct influence of family function or social support to the prevalence of acute IHD was apparent. These results suggest that, among men in Japan, Type A behavior pattern and high job demand represent psychosocial risk factors of IHD. Due to the case-control protocol, causal relationships cannot be decided. The limitation of the study design is discussed within that context.

Coronary Disease↗

PubMed1990

[An echocardiographic study of alcoholic cardiomyopathy after total abstinence].

Left ventricular function of alcoholic cardiomyopathy with congestive heart failure was investigated by echocardiography during total abstinence for six months. In five of 13 cases, left ventricular ejection fraction (LVEF) was normalized to 55% or more and left ventricular end-diastolic dimension (LVEDd) was reduced to 5.7 cm or less during the study. In the remaining eight patients, no improvement was observed. In the responsive group, two patients showed an increase of LVEF and a reduction of LVEDd simultaneously, but three showed an earlier change in LVEDd. This normalization of LVEF and LVEDd was recognized from three to 12 weeks after abstinence. No significant differences were detected between the responsive and non-responsive groups concerning their age, daily intake of alcohol and period of drinking, NYHA cardiac functional class, the period of experiencing cardiac symptoms and the cardiothoracic ratio by chest radiography. The ratio of left ventricular radius to wall thickness (R/Th) remained 2.9 or less in all of the responsive group, but seven of eight in the non-responsive group showed 2.9 or more. Left atrial dimension was reduced to the normal range except in one, but its normalization did not correlate with the change of left ventricular function. Consequently, after total abstinence from alcohol intake, both left ventricular end-diastolic dimension and ejection fraction improved rapidly, and their normalization could be highly expected. Echocardiography is very helpful in predicting the effect of total abstinence on left ventricular function in alcoholic cardiomyopathy.

Adult↗

PubMed1990

Simple maneuver for closing traumatic eardrum perforation by micropore strip tape patching.

The purpose of this paper is to introduce a simple and reliable method to close traumatic tympanic membrane ruptures. Traumatic eardrum perforations without ossicular discontinuity were treated by patching with a piece of micropore tape (3M Micropore Strip Tape). A retrospective study of 108 cases treated by this method over a 7-year period revealed that 107 (99.1%) of the perforations were healed completely by the procedure. The authors stress that this is a simple and reliable method for treating fresh traumatic eardrum perforation. This method does not require anesthesia or any averting manipulation of the perforation.

Adolescent↗

PubMed1990

Metastatic bone disease. A study of the surgical treatment of 166 pathologic humeral and femoral fractures.

A retrospective study of the surgical treatment of 166 metastatic lesions of the humerus and femur in 147 patients was performed. There were 106 women and 41 men whose average age was 62 years. Two-thirds of the patients were treated for complete fractures, while one-third were treated for impending fractures. Breast, lung, and kidney carcinoma accounted for the majority of the primary lesions. One-half of the patients died within nine months of surgery, while one-quarter were alive 19.1 months after surgery. The patients with breast cancer had the best prognosis, while the patients with lung cancer had the worst. The probability of implant failure increased linearly with time to 33% at 60 months. The probability of failure for the femoral lesions was greater, with 44% at 60 months. The average survival in the patients with failed fixation in the femoral lesions was 34.5 months with a mean interval to failure at 17.7 months. The failure rate was high (23%) in proximal femoral lesions treated with a compression screw or nail plate. Common reasons for failure included poor initial fixation, improper implant selection, and progression of disease within the operative field. Bone cement augmentation should be used with the fixation device when possible. Complications due to hip-screw cut-out from the head may also be reduced by applying bone cement around the screw threads.

Adolescent↗

PubMed1990

[Surgical treatment of bone metastasis in advanced renal cell carcinoma].

Operative treatments for bone metastases were performed in 7 patients with an advanced renal cell carcinoma. Spinal instrumentation using a Harrington's rod and Luque's wire was the method employed in 4 cases as the initial treatment. In one other case, an anterior fusion by an autologus bone transplantation was used, followed by a posterior fusion. In the 2 remaining cases an endoprosthetic replacement for a metastasis in the right femur and a transplantation of a Kotz's knee joint was done for a metastasis in the left tibia, respectively. In 5 patients with vertebral column lesions, the stabilization of spinal instability was effected by the spinal instrumentation. Three patients with vertebral metastases recovered sufficiently to walk by themselves. This beneficial result was invaluable from the viewpoints of physiotherapy and nursing care.

Aged↗

PubMed1989

Genetic characterization of the spaA1 determinant of the surface protein antigen gene from Streptococcus sobrinus 6715.

1. The surface protein antigen-encoding gene spaA1, previously cloned from Streptococcus sobrinus 6715 (serotype g) into the plasmid pACYC184, was examined. 2. The gene product of pYA726 was identified both by the minicell method and by in vitro transcription-translation system as a protein whose mol. wt was estimated to be 140,000. 3. The spaA1 gene was localized on the 3.75 kb AvaI-BamHI fragment of the cloned DNA. 4. An internal spaA1 promoter located close to one end of the 1.25 kb AvaI fragment within the 3.75 kb AvaI-BamHI fragment initiated the transcription for the insert DNA of S. sobrinus autonomously.

Bacterial Proteins↗

PubMed1989

Immunofluorescent study of the endolymphatic sac in Menière's disease.

Immunofluorescent and light microscopic studies were performed on 21 small endolymphatic sac specimens biopsied during endolymphatic sac drainage surgery. The biopsies were taken from the extraosseous portions of the lateral side of the sac. Of the 21 specimens, only 5 displayed prominent histologic signs, including 1 with brown pigmentation and 4 with positive immunofluorescent reactions to either IgG, IgA, or IgM. No such histologic signs were seen in any of the other 16 specimens, although severe fibrous tissue change was found. One of the 4 specimens showing immunofluorescent reactions displayed a triple-layered ring structure in which the outer layer was IgM positive, the middle layer IgG positive, and the inner layer IgA positive (case 1). This ring-like structure, located in the fibrous tissue, appeared to be an occluded blood vessel. Another specimen showed positive reactions to IgG and IgA in a section which appeared to be part of the lumen, and which contained a macrophage-like cell and a lymphocyte. These results tend to support the idea that certain types of Meniere's disease are caused by immunologic injuries to the endolymphatic sac.

Adult↗

PubMed1987

Endolymphatic sac surgery for Menière's disease: eighteen years' experience with the Kitahara sac operation.

From 1968 to 1983, 162 cases of Meniere's disease were treated surgically with our intramastoid drainage technique. One hundred forty of these cases could be followed up for two years or more. Treatment results were calculated according to the 1972 AAOO criteria and the 1985 AAO-HNS criteria. Using our technique, definitive vertigo spells could be controlled completely in 78% of cases and substantially controlled in 94%. Hearing worsened in only 15% of all cases. Therefore, prevention of worsening of hearing, especially in bilateral cases, and control of vertigo spells in patients with frequent attacks were considered absolute indications for our technique. In this study critical observations were made based on the number of cases hitherto reported by surgeons (the average number of patients undergoing surgery in our clinic was fourteen per year). The need for careful selection of patients for surgery is emphasized.

Adult↗