Biomedical subjects

O Yamada

Publications and source records attributed to O Yamada.

298 records · Page 17Linked to original sources

PubMedDate not supplied

A three-dimensional cell culture model for bovine endometrium: regeneration of a multicellular spheroid using ascorbate.

The development of a multicellular spheroid comprising bovine endometrial epithelial cells (BEE) and bovine endometrial stromal cells (BES) is described in this study. The BES were cultured to confluence in medium with L -ascorbic acid phosphate magnesium salt n -hydrate (AsA-P) which stimulates collagen synthesis in BES. The BEE were co-cultured on a BES cell-sheet for 24h before detachment of the cell-sheet to generate a hetero-spheroid. After EDTA treatment and agitating with pipette, the floating cell-sheet shrank and became an aggregated cell mass in a few days; it finally formed a round-shaped hetero-spheroid composed of BES and BEE. Histological examination found that hetero-spheroids were covered with BEE on the outer layer. When cell viability was examined with TUNEL (terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling), no positive signal was detected in the spheroid for up to 10 days. Immunofluorescence observations showed that spheroids contained abundant extracellular matrices, including type-I, -III, -IV collagen, fibronectin, and laminin. PGF(2alpha) produced by hetero-spheroids in response to oxytocin was significantly higher than those produced by monolayer cultured BEE (P< 0.05). MMPs were not detected in media from spheroids cultured for 5 days after detachment of the cell sheet. These results indicate that bovine endometrial cells have the capacity to regenerate as a multicellular spheroid after treatment with ascorbate in vitro. The spheroid displays an endometrium-mimic feature. Thus, we conclude that spheroids formed by BES and BEE are a useful in vitro model of bovine endometrium.

Animals↗

PubMedDate not supplied

Generators of the frequency-following response in the guinea pig.

Generators of the frequency-following response (FFR) were assessed in 13 guinea pigs by cooling of the whole body and by experimental lesions of the brain stem. In the temperature study, the amplitude-temperature function of the FFR contained a significant cubic component that was absent from that of the cochlear microphonic potential (CM) recorded from the round window. The phase shift of the FFR increased with decreasing body temperature. In experimental lesions of the brain stem, a significant phase shift of the FFR was obtained following contralateral postcollicular section. The FFR amplitude with transection of the auditory nerve was similar to that found before surgical sections of the brain stem. The duration of the FFR after the transection corresponded precisely to that of the round window CM. These results indicate that the origin of the FFR contains both nonneural (ie, cochlea) and neural (ie, involving the inferior colliculus) generators.

Animals↗

PubMedDate not supplied

Brain stem response audiometry at speech frequencies.

Auditory-evoked brain stem response (BSR; wave V) was studied, using tone pips at three speech frequencies (500, 1 000 and 2 000 Hz) as stimuli. The tone pips consisted of 5-ms rise-decay times without a plateau. BSR recordings were made in 10 normal subjects and in 16 subjects with impaired hearing. In the normal subjects, BSR thresholds ranged from 10 to 20 dB SL at these three frequencies. In the subjects with impaired hearing, BSR thresholds corresponded well to conventional pure-tone thresholds at each frequency in cases of low- as well as high-frequency hearing loss. In all subjects with impaired hearing, the BSR thresholds were higher by as much as 25 dB than the pure-tone thresholds. The mean differences between these two thresholds at 500, 1 000 and 2 000 Hz were 11.3 +/- 8.0, 10.9 +/- 6.2 and 10.9 +/- 7.3 dB, respectively. Thus, we conclude that the BSR is useful for objective assessment of hearing thresholds at each of these speech frequencies.

Acoustic Stimulation↗

PubMedDate not supplied

Cochlear initiation site of the frequency-following response: a study of patients with sensorineural hearing loss.

The cochlear initiation of the frequency-following response (FFR) was assessed by comparing the FFR thresholds to the pure-tone thresholds in four groups of patients suffering from different forms of sensorineural hearing loss. The groups consisted of patients suffering from (1) pure high-frequency hearing losses; (2) high-frequency hearing losses mixed with moderate low-frequency losses; (3) flat hearing losses, and (4)low-frequency hearing losses. Across groups, the pattern of thresholds of the FFR evoked by 500-Hz tome bursts paralleled the pattern of pure-tone thresholds only for the low frequencies- not the high frequencies. In order to clarify the interpretation of this result, a high-pass masking experiment was performed on patients with low-frequency hearing losses. High-pass masking noise did not affect the FFR thresholds to 500-Hz tone burst, but it produced a phase shift of the FFR at stronger intensity levels. The data are interpreted as strongly supporting the view that the FFR at low levels is initiated primarily by activity in the apical portion of the cochlea.

Acoustic Stimulation↗

PubMedDate not supplied

Effects of number and interstimulus interval of tone pips on fast responses.

Effects of stimulus number and interstimulus interval on auditory-evoked fast responses (BSR: Jewett's V, and middle-latency components: Na, Pa and Nb) were studied by using 1000- and 500-Hz tone pips in 6 normal human adults. At a stimulus intensity of 50 dB SL, 500 stimuli evoked BSRs and the middle-latency components in all cases. At a stimulus intensity of 30 dB SL, 1000 stimuli were necessary to evoke BSRs and Na in all 6 subjects. Even 4000 stimuli were not sufficient for identifying Pa in 1 subject and Nb in 3 subjects. The largest mean peak-to-peak amplitude was the Na-Pa amplitude, but, differences across subjects were large. On the other hand, the BSR-Na amplitude showed relatively small differences across subjects. The BSR latencies were highly stable across subjects. These characteristics indicate that the BSR-Na component is more suitable as an indicator for objective audiometry than either the Na-Pa or Pa-Nb component. The BSR-Na amplitude did not show a decrease as the interstimulus interval was decreased from 104 to 32 ms. On the other hand, the Na-Pa amplitude significantly decreased as the interstimulus interval was decreased from 104 to 42 ms, and the Pa-Nb amplitude also significantly decreased as the interstimulus interval was decreased from 104 to 73 ms. Therefore, because of its resistance to the effects of high rates of stimulation, the BSR-Na component appears to be a suitable audiometric index in the clinical situation where time constraints are a consideration.

Acoustic Stimulation↗

PubMedDate not supplied

Altered erythropoiesis and increased hemolysis in hemoglobin M Akita (M Hyde Park beta92 His replaced by Tyr) disease.

Hb M Akita disease is a cyanotic hemoglobinopathy found in Akita Prefecture, Japan. The abnormal hemoglobin was found to be the same as Hb M Hyde Park (beta92 His replaced by Tyr) by chemical analysis in 1967. In this disease signs of accelerated hemolysis (serum bilirubin, 2.4 mg/dl; splenomegaly, 2 finger breadths; Hb, 10.7 g/dl; reticulocyte index, 2.7) were noted, but the causes of its slight anemia were revealed to be fairly complex by ferrokinetic study, RBC life-span measurement, and 99mTc myeloscintigram. The anemia in this disease is caused not only by shortened erythrocyte survival (T 1/2 = 11.5 days by 51Cr-tagging method) and sequestration of red cells in the spleen (Spleen: liver ratio = 2.5 approximately 3.0 by 51Cr-surface counting), but also by slow supply of erythrocytes to the peripheral blood from the bone marrow, presumably, related to the existence of unstable Hb M Akita and its derivative (Hb Akita) in the erythroid cells. Both Carrell's isopropanol test and Heinz body formation test were positive. In spite of maximally increased total erythropoiesis (8 times as high as the normal level; M:E ratio = 0.22:1.0), supply of red cells from the bone marrow to the peripheral blood was significantly decreased. The distribution of hematopoietic sites throughout the body was reasonably uniform.

Adult↗

PubMedDate not supplied

Effect of the nitrosourea anti-tumor chemotherapeutical agent MCNU on five human myeloma cell lines.

We investigated the effects of MCNU (methyl-6)3-(2-chloroethyl)-3-nitrosoureido)-6-deoxy- alpha-D-glucopyranoside), a nitrosourea anti-tumor agent developed in Japan, on cell growth and differentiation in five human myeloma cell lines and compared it with relative expression levels of MDR-1 gene. Although 10 microg/ml of MCNU inhibited cell growth in KMM-1 and KMS-5 lines, other three cell lines required 20-40 microg/ml of MCNU to obtain similar growth inhibition. Accumulation up to the G2 phase of the cell cycle was observed in KMM-1 and KMS-5 lines and the cloning efficiency of KMS-5 cells was reduced by MCNU. On the other hand, expression of surface markers on these lines was not altered remarkably except for increased expression of CD38 on KMS-5 cells. However, the effect of MCNU on these cell lines did not correlate to relative expression levels of MDR-1 gene analyzed by RT-PCR. MCNU may inhibit the growth of myeloma cells by the accumulation of these cells up to the G2 phase, but may not affect their differentiation.

Antineoplastic Agents↗

PubMedDate not supplied

Emergency graft replacement of the aortic arch for acute type A aortic dissection.

Between May 1988 and December 1990, 7 patients underwent graft replacement of both the ascending aorta and aortic arch for acute type A aortic dissection. Preoperative complications included cardiac tamponade in 5 cases, rupture of the left pleural cavity in 1, and aortic regurgitation in 5. All operations were performed with the aid of extracorporeal circulation and selective cerebral perfusion (SCP) on an emergency basis. Concomitant procedures included aortic cusp suspension in 3 cases, Bentall operation in 2, and CABG in 1. There were no deaths within 1 month of surgery, nor were there serious postoperative cerebral complications. One patient with chronic obstructive lung disease died of pneumonia 5 months after the operation. The other 6 patients are presently leading normal lives with long-term follow-up. The present data suggest that SCP with an open aortic anastomosis is a useful adjunct in aortic arch replacement for acute type A aortic dissection.

Adult↗

PubMedDate not supplied

Graft inclusion technique for thoracoabdominal aortic aneurysms involving visceral branches with the aid of a femoro-femoral bypass.

Eleven patients in our institution with thoracoabdominal aortic aneurysms involving the celiac, superior mesenteric and renal arteries underwent surgical treatment with the aid of a partial femoro-femoral bypass during the last three years. Three patients with expanding aneurysms underwent emergency operations. Another three patients with extensive aneurysms had two-stage operations: initial aortic arch or descending thoracic graft replacement followed by thoracoabdominal graft replacement in the second stage. Exposure of the aneurysms was made through a left transthoracic, retroperitoneal abdominal approach in all patients. The surgical technique employed in most cases in this series was graft inclusion with direct reattachment of the visceral vessels by anastomosis to an opening made in the graft. Pairs of intercostal and lumbar arteries between the levels of the ninth thoracic and fourth lumbar regions were reconstructed in a similar fashion on the basis of monitoring somatosensory evoked potentials. The operations were performed with the aid of a partial femoro-femoral bypass with selective celiac and renal arterial perfusion in most cases. All patients but one survived the operation and are leading normal lives late in the postoperative period. Graft inclusion with the aid of a partial bypass is a valid technique for the treatment of thoracoabdominal aortic aneurysms involving visceral branches.

Abdomen↗

PubMedDate not supplied

Bone and 67Ga scintigraphy in the evaluation of rib lesions in patients with multiple myeloma.

Rib lesions in 14 patients with multiple myeloma were evaluated by 99mTc-phosphorous compound bone scintigraphy and 67Ga scintigraphy. In the present study, in order to accurately detect rib lesions in multiple myeloma, bone and 67Ga scintigraphy were performed in 14 patients with multiple myeloma. The patterns of radionuclide accumulation in rib lesions on bone scintigraphy were classified by their grade, type, and site, and the findings were compared with the results of 67Ga scintigraphy. Thus, in cases of multiple myeloma, it was important to consider carefully both the intensity and the design of bone scintigraphy in combination with follow-up study by 67Ga scintigraphy. As a result of such consideration, we found that bone and 67Ga scintigraphy were useful in distinguishing invasive lesions from benign degenerative changes in the rib cage in cases with suspected rib involvement of multiple myeloma.

Adult↗