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Biomedical subjects

K Yamamura

Publications and source records attributed to K Yamamura.

At least 289 records · Page 16Linked to original sources
PubMed1984

Suprasellar germinoma occurring two years after total removal of pineal teratoma.

A rare case of a suprasellar germinoma occurring 2 years after total removal of a pineal benign teratoma is presented. The suprasellar germinoma was not considered a recurrence or dissemination from the pineal tumor, but to have been transformed from germ cells present in the suprasellar region. Although it is controversial whether radiation treatment should be given to a patient with a totally removed benign teratoma, careful follow-up computed tomography scans are indispensable for detecting a possible occurrence of other germ cell tumors.

Brain Neoplasms↗
PubMed1984

An experimental study of the effects of lead acetate on hearing. Cochlear microphonics and action potential of the guinea pig.

Guinea pigs were poisoned with repeated i.p. injections of 1% lead acetate. After 5 weeks, the animals were examined electrophysiologically by using cochlear microphonics (CM) and action potential (AP). The thresholds of maximum voltage of N1 in the AP of the animals injected with a total of 100 mg lead acetate were elevated about 15 dB and increased N1 latency was also observed. However, no significant changes in those of CM were found. The results suggest that lead acetate not only induces damage to the peripheral nerves, but also to the cranial nerves.

Action Potentials↗
PubMed1984

Introduction of human gamma 1 immunoglobulin genes into fertilized mouse eggs.

A rearranged human gamma 1 immunoglobulin gene was introduced into fertilized mouse eggs. The phage Ch4A-VCE-gamma 1 was constructed by ligating an EcoRI and BglII fragment of pBR322-CESSV(CE-1) containing the VDJ region with an EcoRI and BamHI fragment of Ch4A-HIg gamma 1-10 containing the gamma 1 constant region. About 200 copies of Ch4A-VCE-gamma 1 genes were introduced into fertilized mouse eggs. Of 489 eggs injected with these genes, 319 survived and were transferred to oviducts of foster mothers. Thirtyeight mice were born and were screened for the presence of human gamma 1 immunoglobulin genes by Southern blot hybridization. Five of these 38 mice had integrated human gamma 1 immunoglobulin genes. None of the human gamma 1 copies in each mouse had undergone deletions or rearrangements as judged by the Southern blotting patterns for several restriction enzymes. Human gamma 1 gene was present in several different tissues. All the mice tested so far transmit the human gamma 1 gene to a fraction of their offspring in an autosomal dominant manner. Spleen cells from transgenic mice were analyzed for immunoglobulin production by reverse plaque assay or immunofluorescence staining of cytoplasmic immunoglobulin, but synthesis and secretion of human gamma 1 chains could not be detected. No human gamma 1 immunoglobulin mRNA was detected in the liver and spleen of a transgenic mouse. The presence of the human gamma 1 immunoglobulin gene appeared to have no effect on the expression of endogenous mouse immunoglobulin genes.

Animals↗
PubMed1983

Simultaneous determinations of cefsulodin and cefotiam in serum and bone marrow blood by high-performance liquid chromatography.

A high-performance liquid chromatographic method is described for the simultaneous determinations of cefsulodin and cefotiam in serum and bone marrow blood samples. After extraction with acetonitrile, the cephalosporins were applied to a reverse-phase column with an internal standard, cefazolin; the mobile phase was a mixture of 0.005 M tetrabutylammonium phosphate and methanol (35:65, v/v). The method yielded satisfactory resolutions for these agents, and the results were compared with those obtained using the microbiological method. The statistical analysis of the relationship between the methods gave a good correlation for all of these agents and samples. The concentrations of cefsulodin and cefotiam, concurrently administered by the intravenous route to patients subjected to artificial total joint prosthesis, in serum and bone marrow blood collected at 0.5 and 1 hr postinjection were almost equivalent.

Biological Assay↗
PubMed1983

Effects of trichloroethylene exposure on hearing. An investigation of cochlear microphonics and action potential of the guinea pig.

Four groups of guinea pigs with normal Preyer's reflex were exposed to trichloroethylene (TCE). Each group consisted of nine to 10 naive male albino Hartley guinea pigs of 9 weeks of age with a body weight of approximately 400 g. To test the suggestion that TCE causes damage to the cochlear system, a study was conducted involving four experiments. The results were as follows: No significant difference was observed between the intensity functions of the CM (4 kHz) and AP (7 kHz) potentials of the control groups and those of the TCE-exposed groups by analysis of variance. It was considered that there was no difference in the cochlear reaction to high frequency sound between guinea pig and man. It therefore might be suggested that acute exposure to TCE of a high concentration does not always induce dysfunction of the organ of Corti and the 8th nerve in man.

Action Potentials↗
PubMed1983

Effect of acute stresses on Zn-thionein production in rat liver.

Male Wistar strain rats were exposed to acute stress from broad-band noise [100 dB (A) for 1 h] or cold (4 degrees C for 24 h). Following exposure to noise for 1 h, serum and adrenal gland showed about 1.8 times and 2.5 times the corticosterone levels of the control group, but this enhancement was not observed after exposure to cole. Both stresses increased Zn-thionein significantly in the liver. Furthermore, the two stresses increased the content of Zn in the 30,000 g supernatant fraction of the liver, though serum Zn concentration was not altered. It is believed that thionein is a regulatory protein with a specific function for Zn metabolism in organs. Although it is known that corticosterone affects Zn metabolism in man and animals, there is little investigation of the effect of environmental stresses on Zn metabolism. The present data suggest that Zn metabolism may be important in the investigation of the effects of repeated and long term exposure to environmental stresses involving noise and cold.

Acute Disease↗
PubMed1983

Electrophysiological responses in guinea pig cochlea to low frequency sound stimuli: distortion of cochlear microphonic (CM) wave form.

The present experiment investigated whether or not auditory responses of the middle and/or inner ear in guinea pigs to low frequency sound stimuli [ 60 Hz-2 kHz at 90-120 dB(SPL) ] exhibited the harmonic distortion phenomenon resulting from cochlear microphonics (CM). Measurement of CM leading in turn I by the differential electrode recording method involved measurement of 50 microV isopotential responses, output voltages and CM wave form distortion at each constant sound pressure. The results obtained were as follows: (1) On the 50 microV isopotential response curve and the output voltage curves, the changes at 60-90 Hz were different from those at higher frequencies. (2) At stimuli of 90 or 100 dB(SPL), CM wave form distortion appeared frequently at frequencies below 120 Hz, but were less pronounced above approximately 200 Hz. (3) When raised to 110 and 120 dB(SPL), almost all CM wave forms were distorted at all test frequencies between 60 and 500 Hz. (4) The patterns of CM wave form distortion at frequencies below approximately 120 Hz showed peak clipping and triangular wave distortions, while those at frequencies above approximately 200 Hz showed little of these distortions.

Acoustic Stimulation↗
PubMed1982

Effect of intermittent (traffic) noise on man--temporary threshold shift, and change in urinary 17-OHCS and saliva cortisol levels.

Eight healthy male college students were selected and eight noise exposure conditions were planned. The noise exposure time of all the experiments was 14 h. Measurement of the TTS growth at 4 kHz was investigated during these 14 h. Saliva collected every 3 h was also examined for cortisol throughout the 24-h period. The exposure noises used in this experiment were pink noise and pure tone of 3 kHz. The time patterns of trapezoidal noise were as follows. The rise and decay times were 1 s respectively and the peak level was 1 s for the (A I type), being 500 ms and 1.5 s respectively for the (A II type). Three measurements were made: 1. TTS. Under intermittent noise exposure at 80 dB(A), exposure of 20% of the on fraction induced significant TTS growth, but exposure of 13% of the on fraction did not induce TTS growth. Under exposure at 75 dB(A), exposure of 66% of the on fraction did not induce TTS growth. Under pure tone exposure of 3 kHz at 75 dB(A), exposures of 20% and 30% of the on fraction did not induce TTS growth. There was a significant difference between the TTS induced by a steady state of of 73 dB (A) (Leq of Exp. 2) and that of Exp 2. 2. Urinary 17-OHCS Level. During the noise exposure period (14h), there was a statistically significant difference between the urinary 17-OHCS level of the control condition and that of Exp. 3. In addition, there was no statistically significant difference among the urinary 17-OHCS levels of post-noise exposure. 3. Saliva Cortisol. With intermittent "pink noise" of 75 or 80 dB(A) (Exp. 2, 3, and 4), however, temporary elevation of the saliva cortisol level occurred only at the initial stage of exposure, and lasted for only one hour. Moreover, with steady state noise exposure, evanescent elevation occurred at the lower level of 71 dB(A).

17-Hydroxycorticosteroids↗
PubMed1981

The effects of variable noise level on man with peak levels below 75 dB(A).

To estimate the effect of variable traffic noise levels by field study, six healthy students were exposed to such noise for 8 h in a building beside a highway. TTS increases and blood pressure changes were observed. A summary of the results is as follows: 1. Noise level slightly exceeded 70 dB(A) (Equivalent Sound Level, Leq). The ninety percent range of the changing noise level was within L50 + 10 dB(A). 2. The Temporary Threshold Shift (TTS) induced by variable noise increased slightly in this field experiment. In particular, regression of the logarithm of exposure time (min) to TTS at the "S" ward office, was statistically significant. Some subjects showed a rise of blood pressure due to noise exposure. 4. Even though noise level is below 75 dB(A), 8 h noise exposure induces TTS increase and elevation of blood pressure.

Auditory Fatigue↗
PubMed1981

Physiological responses induced by 555-min exposure to intermittent noise.

Normal medical college students were exposed to noise for 555 min, while the Temporary Threshold Shift (TTS) and changes in the circulatory system were measured. The exposure noise employed was the so-called pink noise of a trapezoidal form. There were two time patterns, A(I) with 1 s of rise-decay time and 1 s of peak level, and A(II) with 500 ms of rise-decay time and 3.5 s of peak level. Thirteen exposure conditions were examined. The noise exposure time of all experiments was 555 min. The following results were obtained. 1. TTS Growth. Significant TTs increases were obtained following exposure to intermittent noise of 85 dB(A), intermittent noise of 80 dB(A), and steady state noise of various intensities. The TTS growth observed with steady state noise at 80 dB(A) was significantly greater than that of intermittent noise exposure at 85 dB(A). Moreover, TTS growth observed with steady noise at 82 dB(A) was significantly greater than that with intermittent noise exposure of 85 dB(A). However, the levels of TTS growth observed with steady state noise of 75 dB(A) and steady state noise at 77 dB(A) were almost equal to those of 6 s trapezoidal noise at 80 dB(A) (the "on fraction" being 33%), and 8 s trapezoidal noise at 80 dB(d) (the "on fraction' being 50%). In the above-mentioned experiments, significant increases of TTS growth were observed with various cycle times of trapezoidal noise with peak levels of 85 dB(A) and 80 dB(A), and with four exposure noise conditions of steady state. Under exposure conditions of 75 dB(A), trapezoidal noise with a 6 s cycle time (the "on fraction" being 33%) did not show a significant increase in TTS growth. 2. Changes in the Circulatory System. There were no significant differences in systolic and diastolic pressure or pulse rate among the three exposure conditions. The findings on ECG were as follows. Under intermittent noise exposure, decrease in the height of the T wave was observed in all examinees with a depression of the ST segments also being observed in two cases. On exposure to steady state noise, however, slight decrease in the height of the T wave was induced in only two cases, and under control conditions in only one case.

Adult↗
PubMed1981

Effects of toluene exposure on blood pressure and its responsiveness to impulse noise in rats.

Effects of a single exposure to toluene at a concentration of 1000 for 4 h on rats' systolic blood pressure were investigated. 9 rats were used in each group (control and exposed groups). The basic blood pressure of the exposed group was significantly lower than that of the control group. The movement of systolic blood pressure due to impulse noise exposure was significantly smaller in the exposed group than in the control group. Toluene exposure at concentration of 1000 ppm for 4 h produced narcotic and inhibitory actions in the diencephalohypophysial and the adrenal gland system in rats.

Animals↗
PubMed1981

Effects of toluene exposure on the rest-activity cycle of rats.

Rats were exposed to toluene at a concentration of 1000 ppm, 6 h/day, 6 times weekly, for 4 weeks. Functional disturbance of the circadian rhythm of spontaneous activity was found after repeated exposure to toluene, although single exposure under the same conditions did not influence the rhythm. The disturbance was characterized by a significant increase in distribution of activity in the "Light' (L) period, and a significant relationship was observed between the total number of days of exposure and the activity level in the L period. The toluene concentration in the blood immediately after the exposure was 6.8-7.2 microgram/ml after one and 18 days of exposure, respectively.

Animals↗