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Biomedical subjects

Y Toyama

Publications and source records attributed to Y Toyama.

At least 127 records · Page 7Linked to original sources
PubMed1992

Changes in the distribution of filipin-sterol complexes in the boar sperm head plasma membrane during epididymal maturation and in the uterus.

The distribution of filipin-sterol complexes (FSCs) and intramembranous particles (IMPs) in the plasma membrane of the late spermatid of the boar and of the sperm obtained from the epididymides, ejaculates, and uterus 2 hours after mating was examined by a freeze-fracture replica technique. In the late spermatid, the FSC density was found to be very low. A majority of the FSCs in the acrosomal plasma membrane (APM) appeared as protuberances on the E face in the epididymal, ejaculate, and uterine sperm. The density of the FSCs in the principal segment (PS) of the APM was 291 +/- 44 FSC/microns2 (mean +/- standard deviation, S.D.), 322 +/- 41 FSC/microns2 and 355 +/- 31 FSC/microns2 in the caput, corpus, and cauda epididymidis, respectively. In comparison with the cauda epididymal sperm, the FSC density gradually decreased in the PS of the ejaculated (277 +/- 39 FSC/microns2) and uterine sperm (243 +/- 50 FSC/microns2). The reduction was especially remarkable in the equatorial segment (ES), where the density of FSCs in ejaculated and uterine sperm decreased to about half and less than half of that in the cauda epididymal sperm, respectively. Large (13 nm) and small (8 nm) IMPs were distributed evenly and densely in the P face of the APM in the late spermatid, epididymal, and ejaculated sperm. In the uterine sperm, IMP-free areas were observed in the P face of the plasma membrane, a feature thought to represent one of the capacitation changes of the boar sperm.

Animals↗
PubMed1992

Chromosome abnormalities and rare fragile sites detected in azoospermia patients.

We have examined constitutional chromosome abnormalities and fragile sites in 40 patients with azoospermia. Chromosome abnormalities were found in four cases. Three cases showed a deletion of the long arm of the Y chromosome 46,X,del(Yq) and the other case had a ring of G group chromosome 46,XY,r(G). In a rare fragile sites test, four fragile site carriers were detected and three rare autosomal fragile sites were identified; fra(8)(q24.1), fra(11)(p15.1), and fra(17)(p12). The expression of these fragile sites were induced specifically by AT-specific DNA ligands, such as distamycin A and Hoechst 33258. In addition, one patient was found to be the case of double ascertainment of fragile sites, fra(8)(q24.1) and fra(17)(p12). The overall frequency of distamycin A-inducible fragile sites in azoospermia patients appeared to be higher than those reported for Japanese healthy subjects and cancer patients. However, no significant relation among fragile sites, clinical and histological findings has been detected so far.

Chromosome Aberrations↗
PubMed1992

Spontaneous fracture of the odontoid process in rheumatoid arthritis.

Six cases of spontaneous fracture of the odontoid process in rheumatoid arthritis are presented. Fifty-one patients with atlantoaxial subluxation in rheumatoid arthritis underwent surgery between 1981 and 1990. This included six patients (in 10%) who had subluxation accompanied by fracture of the odontoid without apparent trauma. The mean patient age was 58 years and all had a long history of rheumatoid arthritis. No trauma was considered to be the cause of the fracture. This is a fracture caused by erosion and osteoporosis of the odontoid process due to rheumatoid synovitis, aging and steroid therapy. In addition, another cause is a dynamic load produced from the instability accompanying atlantoaxial subluxation working on the odontoid in cervical extension. It is important remember that the odontoid process is susceptible to spontaneous fracture.

Aged↗
PubMed1992

A clinical study of degenerative spondylolisthesis. Radiographic analysis and choice of treatment.

Surgical treatment of degenerative spondylolisthesis in 27 patients by means of anterior lumbar interbody fusion and in 14 patients by means of posterior decompression yielded average degrees of recovery of 77% and 56%, respectively. Preoperative analysis of myelograms, and computed tomographies after myelography indicated that anterior shifting of the inferior articular process of the slipping vertebra was the main factor responsible for compression of the nervous tissue in the early stages of degenerative spondylolisthesis. Patients in these stages should be treated by anterior lumbar interbody fusion. In the later stages of degenerative spondylolisthesis, osteophytes on the superior articular processes of the lower vertebra were an additional factor in compression, and patients should be treated by posterior decompression. Computed tomographies after myelography provided the key images for identifying pathologic processes in degenerative spondylolisthesis and selecting appropriate surgical procedures.

Adult↗
PubMed1992

A simple noninvasive measurement of stenotic mitral valve area: an alternative approach using M-mode and Doppler echocardiography.

Doppler echocardiography is a widely used noninvasive technique to examine the mitral valve area (MVA) by obtaining mitral pressure half-time (PHT) and to assess the severity of the stenosis. However, several hemodynamic factors influence the PHT and may render the PHT data inaccurate in any measurement of MVA under certain conditions. Using a simple echo-Doppler (E-D) method, we assessed the MVA in a physiological equation. The mitral flow volume (MFV) is represented by MVA x transmitral mean flow velocity (mV) x diastolic filling time (DFT). Thus, the formula can be restated as MVA (cm2) = MFV (cm3)/mV (cm/sec) x DFT (sec). We measured MFV by M-mode, and mV and DFT by continuous wave Doppler echocardiography. This formula was tested in 43 patients with isolated mitral stenosis. MVA was obtained by the PHT and E-D methods, and the data obtained were validated against the results of cardiac catheterization. The results obtained using the E-D method showed much better correlation (r = 0.82) with those of catheterization than those with the PHT method (r = 0.52). The inter- and intraobserver variabilities were checked. The results obtained with the E-D method were found to be reproducible. To further validate the accuracy of the E-D method, MVA was measured by both methods at different R-R intervals after exercise and the results were compared. The MVA obtained by the PHT method showed marked variations; whereas, that obtained by the E-D method remained nearly constant. Similarly, in a patient with atrial fibrillation, the MVA assessed by the PHT method varied from beat to beat; whereas, the fluctuations in MVA were minimal using the E-D method. We concluded that the E-D method can be reliable and clinically easily applicable for the accurate assessment of MVA.

Adult↗
PubMed1991

Semiquantitative regional cerebral blood flow evaluation using 123I-IMP SPECT in a case showing transient ischemic attack caused by putaminal hemorrhage.

A 69-year-old woman presented a transient cerebral ischemic attack, showing left arm weakness and slurred speech which recovered within 4 h of onset, while computed tomography indicated a putaminal hemorrhage. The regional cerebral blood flow distribution, measured semiquantitatively by use of 123I amphetamine emission tomography, was disturbed, which persisted more than one month up to a maximum of 4.5 months from the onset of symptoms. This case illustrates a variety of putaminal hemorrhage of good functional and vital prognosis, and provides an example in which the regional cerebral blood flow disturbances might persist for more than one month up to 4.5 months after the occurrence of a transient ischemic attack caused by a putaminal hemorrhage.

Aged↗
PubMed1990

Ultrastructural study of crystalloids in Sertoli cells of the three-toed sloth (Bradypus tridactylus).

Crystalloids were found in Sertoli cells of the testis of the three-toed sloth by examination at the light- and electron-microscopic levels. Needle-, or spindle-shaped crystalloids, varying in length, were located in the basal part of the Sertoli cells. They consisted of bundles of filaments each measuring approximately 11 nm in diameter. Several filaments were packed hexagonally to form a bundle. The center-to-center distance between individual filaments of a bundle was approximately 17 nm. Periodical lateral projections emanated from the filaments. Cross sections of crystalloids showed that the projections radiated from each filament in three directions, forming an equilateral triangle with a side length of approximately 15 nm. Scattered polyribosomes were found between and around the bundles.

Animals↗
PubMed1990

Effect of electric field on erythrocyte sedimentation rate. II. Dependence on electric current.

We measured the electric current dependence of sedimentation curves of swine erythrocytes in a saline solution at the volume fraction of erythrocytes H = 0.091 and 0.220. The sedimentation curve fitted well to the exponential type equation l = a[1-exp(-bt)] at the upward initial electric current I0 = 0.50 mA, 1.01 mA and 1.50 mA, where l is the length of the medium layer at time t, and a and b are phenomenological parameters. The initial slope v0 of sedimentation curve was enhanced from 0.68 mm/hr at I0 = 0 mA to 2.85 mm/hr, 3.87 mm/hr and 5.50 mm/hr at I0 = 0.50 mA, 1.01 mA and 1.50 mA, respectively, for H = 0.220. We also made sedimentation measurements of erythrocytes in their own plasma at H = 0.220 and 0.316. Sedimentation curves coincided with the sigmoidal type equation l = l infinity/[1 + (t50/t)beta] at I0 = 0 mA and 0.50 mA, where l infinity is l at t----infinity, t50 is the time when the plasma level falls to l infinity/2 and beta is a constant. The maximum slope vmax of sedimentation curve increased from 13.29 mm/hr at I0 = 0 mA to 18.65 mm/hr at I0 = 0.50 mA for H = 0.220.

Animals↗
PubMed1990

[Perfusion study of the pulmonary hilar region by SPECT--normal cases].

Alveoli in the hilar region comprise the peripheral area containing daughter branches from subsegmental or one more divisional peripheral bronchi. Pulmonary perfusion in hilar region was examined by SPECT (single photon emission CT) in ten normal volunteers. ROI (region of interest) in the axial images were set in the hilar region, the upper, middle and lower lung fields with 10.8 mm thickness. Counts/one pixel (C/P) were calculated in these ROI. There was a tendency of C/P increase from upper to lower lung field. And there were no significant differences in C/P increase between hilar region and other axial fields. In the chronic obstructive pulmonary diseases, however, ventilation studies in the previous reports using Xe dynamic CT or PET (positron emission tomography) showed differences between outer region and hilar region. This method will be expected to evaluate the pulmonary perfusion not only in the whole lung but in different lung areas, including the hilar region in the chronic obstructive pulmonary diseases.

Adult↗
PubMed1990

[Fracture of the coracoid process: its classification and pathomechanism].

Twenty-eight cases of fractures of the coracoid process were assessed regarding general characteristics, causes of injury, regions of contused wound, fracture types and complications. From the results of the assessment, the fractures were roughly divided into five types: type I; apical, type II; middle, type III; basal, type IV; intraarticular (including upper 1/3-1/4 of the glenoid cavity), and type V; others. Subtypes A and B were present in type III and IV. From the specifics of the contusions and complicated osseous-articular injuries around the shoulder, the mechanisms of injury in each type may be suggests as follows: type I and II; tractive force of attached muscular tendons, type III and IV; shearing force acting between the scapula shifting inward due to blow from the lateral aspect of the shoulder and the clavicle countering this movement, and type V; unspecified. The main cause of fractures of the superior scapular margin was considered to be the tractive force of the superior transverse scapular ligament, because almost all cases of subtype A were complicated with them. For the benefit of the clinical use, they should be classified into two groups: group A; without loss of connection between scapula and clavicle (mainly types I and II), and group B; with loss of the same (majority of types III and IV).

Adolescent↗
PubMed1990

[Mental stress echocardiography for patients with mitral valve prolapse].

Our clinical experience suggests that anxiety may provoke the augmentation of the degree of mitral valve prolapse (MVP) and change the mitral inflow velocity pattern in patients with MVP. To evaluate this systematically, we recorded 2-dimensional (2-D) and pulsed wave Doppler echocardiograms during acute mental stress in eight patients with MVP and eight age-matched normal subjects. Acute mental stress was administered by applying arithmetical task or reminding each patient of their most uncomfortable memories. Heart rate and blood pressure were significantly increased during mental stress and returned to the control level within a few minutes after its release in both groups. 2-D and Doppler echocardiograms were constantly recorded before, during and after acute mental stress. MVP was prominently augmented during mental stress in three of the eight patients. During mental stress, the mitral inflow velocity decreased in the rapid filling phase (R) and increased in the atrial filling phase (A), resulting in significant increase of the A/R in seven of the eight patients with MVP, especially in the patients associated with an increase of MVP. In normal subjects, mitral valve prolapse did not develop and the A/R was minimally increased or remained almost the same during mental stress. In conclusion, mental stress echocardiography seems to be a useful provocation test for the assessment of MVP and it is further expected to propose a lot of potential applications as a new method of stress echocardiography.

Adult↗
PubMed1989

Appearance of osteoclasts by injections of lipopolysaccharides in rat periodontal tissue.

The effect of lipopolysaccharides (LPS) on periodontal tissue was studied in 11-week-old Wistar rats. Four injections of 500 micrograms LPS induced marked osteoclastic alveolar bone resorption, whereas no alveolar bone resorption occurred after four injections of physiological saline. The osteoclast count increased progressively during the four injections of 500 micrograms LPS. After eight injections, however, the osteoclast count fell from the maximum level after four injections, although osteoclasts continued to increase in size and demonstrate an increased number of nuclei. Comparison of the osteoclast number between a series of four injections of 5, 50 or 500 micrograms LPS each revealed a dose-dependent increase. This strongly suggests LPS induction of osteoclastic bone resorption in vivo. Combined use of indomethacin, a prostaglandin synthesis inhibitor, with LPS injections inhibited both the LPS-induced alveolar bone resorption and osteoclast increase, suggesting a possible participation of prostaglandins in osteoclast-mediated bone resorption.

Animals↗
PubMed1989

In utero changes of the plasma membrane in the head region of the rat spermatozoa.

The plasma membrane of the head of the rat spermatozoa was observed by deep-etch, surface replica, and freeze-fracture methods. The spermatozoa were from three experiments: 1) incubation in Hepes buffer, 2) natural coition, and 3) insemination. The spermatozoa used for experiments 1) and 3) were obtained from the ductus deferens. No change in ultrastructure was observed in the incubation experiment. Randomly oriented rows of particles were observed on the plasma membrane of the ejaculated spermatozoa in the deep-etch replicas. The surface replicas showed a similar structure on the plasma membrane. The surface of the inseminated spermatozoa was smooth. This study shows that the plasma membrane changes in the uterus.

Acrosome↗
PubMed1988

Maturation changes of the plasma membrane of rat spermatozoa observed by surface replica, rapid-freeze and deep-etch, and freeze-fracture methods.

Rat spermatozoa from the epididymis and ductus deferens were observed by surface replica, rapid-freeze and deep-etch, and conventional freeze-fracture methods. By the surface replica method, parallel periodical ridges were observed in the acrosomal region of the spermatozoa from the distal part of the cauda epididymis (zone 6) and from the ductus deferens. The periodicity of the ridges forming a domain was about 35 nm. A quantitative analysis of the spermatozoa along the reproductive tract indicated that 39.4% and 73.5% of the population in zone 6 of the epididymis and in the ductus deferens, respectively, had the domain. None of the spermatozoa from zone 1 through zone 5 had the domain. The results of the rapid-freeze and deep-etch procedure showed that the ridges observed by the surface replica method consisted of linear arrangements of elliptical particles on the ES face of the plasma membrane. The particles were about 30 nm in length and 15 nm in width. On the corresponding PF face of the plasma membrane, linear arrangements of the intramembrane particles (IMPs) of about 8 nm in diameter were observed by both the deep-etch and freeze-fracture methods. The IMPs tended to run in paired parallel lines. A close relationship was observed between the lines of the elliptical particles on the ES and of the IMPs on the PF faces. The elliptical particle may be a protruded part of the IMP(s) or other protein(s) bound to the IMP(s).

Animals↗
PubMed1988

Erythrocyte sedimentation rate III tube diameter dependence in saline solution.

Erythrocyte sedimentation rate was measured in a physiological saline solution as a function of both the tube diameter d and the initial suspension length iota 0. All the sedimentation curves in the vertical tubes were found to overlap over the range 1 mm less than d less than 7 mm and 100 mm less than iota 0 less than 330 mm, within the precision of 8 %. The sedimentation curves in the tilted tubes fit well to an exponential equation of iota = a [1 - exp (-bt)], where iota and t are the medium length along the tube and the elapsed time from sample injection respectively: At fixed tilt angle theta and iota 0, a was roughly constant and b was roughly proportional to l/d, while at fixed theta and d, a was linearly proportional to iota 0 and b was constant. The initial slope ESR (theta) = (d iota/dt) t----0 = ab was represented by a unique straight line as a function of iota 0/d for each fixed tilt angle. The experimental results were compared with some recent theories.

Animals↗