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Biomedical subjects

Y Yoshii

Publications and source records attributed to Y Yoshii.

At least 109 records · Page 6Linked to original sources
PubMed1986

Regrowth patterns of supratentorial gliomas: estimation from computed tomographic scans.

To clarify the regrowth patterns of benign and malignant gliomas, we chose 27 intervals (between two operations or between an operation and autopsy) from 21 patients with pathologically verified recurrent supratentorial gliomas. Serial computed tomographic (CT) scans of these cases were analyzed to determine the doubling time (Td) calculated from the change in volume of enhanced and low density areas, the enhancement effect graded from 0 to 4 according to the Hounsfield number, and the presence of dissemination and contralateral extension. We studied 5 benign gliomas (including 1 case of radiation necrosis), 8 malignant astrocytomas, and 8 glioblastomas. The Td's of enhanced areas on CT scans of benign gliomas, malignant astrocytomas, and glioblastomas were 937 +/- 66.5 days, 65.1 +/- 29.4 days, and 48.1 +/- 20.9 days, respectively. The Td's of low density areas were 895 +/- 130.6 days, 70.8 +/- 22.2 days, and 50.5 +/- 14.7 days. There was a significant correlation between the Td's of the enhanced and low density areas (0.97). The enhancement effect increased at recurrence in 55% of the cases, with an average increase of 1.1 grades. The increase in enhancement effect at recurrence showed a tendency to become smaller as the tumor's degree of anaplasia increased. Radiotherapy was effective in significantly retarding the growth rate of malignant gliomas, whose Td's were doubled. Although the Td's of both enhanced and low density areas of benign gliomas were significantly longer than those of malignant gliomas, there was no significant difference in the Td's of enhanced areas between malignant astrocytomas and glioblastomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Estimation of growth fraction with bromodeoxyuridine in human central nervous system tumors.

Twenty-five patients with tumors of the central nervous system received bromodeoxyuridine (BUdR), 200 mg/sq m, by intravenous infusion every 8 hours for 3 days before surgery. Excised tumor specimens were fixed in chilled 70% ethanol, embedded in paraffin, and cut into 6-micron sections. Each section was reacted with monoclonal antibodies against BUdR and stained with immunoperoxidase to identify nuclei that had incorporated BUdR. The growth fraction of each tumor was estimated by calculating the ratio of BUdR-positive nuclei to the total number of tumor cells in three to six microscopic fields in viable areas of the tumor. In seven cases, the tumor doubling time was measured from the serial computerized tomography scans and an attempt was made to estimate the cell cycle time. The growth fractions ranged from 9.1% to 46.5% in malignant gliomas, 2.0% to 6.7% in low-grade gliomas, 11.2% to 43.2% in metastatic brain tumors, 0.8% to 1.9% in pituitary adenomas, 3.9% to 4.6% in acoustic neurinomas, and 6.2% to 8.2% in meningiomas and cerebellar hemangioblastomas. The estimated cell cycle time was 5 to 12 days in most malignant gliomas and brain metastases; however, the actual cell cycle time should be substantially shorter because cell loss was not considered in the calculation. Although the growth fraction appeared to correlate with the biological malignancy of each tumor, the tumor doubling time did not reflect growth potential. It is possible that unpredictable cell loss plays an important role in tumor growth at certain sizes. Therefore, the cell cycle times calculated in this study are considerably overestimated and should be interpreted with caution.

Bromodeoxyuridine↗
PubMed1985

[Quantitative assessment of regurgitant fraction in aortic regurgitation: comparison of two-dimensional Doppler echocardiography with other methods].

To determine proper operative procedures for aortic regurgitation (AR), we attempted to evaluate the severity of AR by two-dimensional Doppler echocardiography (TDE), using 15 mongrel dogs with experimentally-induced AR. Furthermore, the left ventricular (LV) suction method was investigated for the significance in estimating the severity of AR, cardiac outputs were measured by the thermodilution technique, TDE, and electromagnetic flowmeter (EMF). The values obtained by each method were compared. In dogs with AR, regurgitant fraction (RF) was calculated from stroke volumes obtained by TDE and EMF, as follows: RF [TDE] = (LVO-RVO)/LVO (LVO: left ventricular output; RVO: right ventricular output) RF [EMF] = [total stroke volume (T)-effective stroke volume (E)]/T The effects of alterations in afterload and pump flow rates on regurgitant fractions and regurgitant volumes measured by the LV suction method were also studied. The following results were obtained: Good correlations were observed between RVO and LVO measured by TDE, and those measured by the thermodilution technique and EMF, respectively. In dogs with AR, regurgitant fractions measured by TDE correlated well with those measured by EMF. These results strongly suggested that the Doppler index (RF) was accurate and useful for estimating the severity of AR clinically. Regurgitant volumes measured by the LV suction method were not influenced by the pump flow rate, and they correlated well with square root values of the mean diastolic pressure in the aorta. In the LV suction method, Bernoulli's theorem held good between the regurgitant volumes and the mean diastolic pressures in the aorta of the dogs with AR. Considering the factors of mean diastolic pressure in the aorta and diastolic time, regurgitant volumes measured by EMF in the beating heart showed excellent agreement with those measured by the LV suction method in ventricular fibrillation. Therefore, to evaluate quantitatively the pathophysiological changes of the aortic valve in patients with AR, we should estimate the severity of AR using regurgitant volumes corrected for the cardiac cycle at the same mean diastolic pressure in the aorta.

Animals↗
PubMed1984

Use of evoked responses to measure laser photoradiation tissue effects.

The amount of argon laser irradiation necessary to first produce marked changes in somatosensory evoked potentials when applied to the dorsal columns of cats was used to measure the enhancement of tissue response by fluorescein previously injected intravenously. The mean radiant exposure was roughly 2700 J/cm2 in normal control animals compared to a mean radiant exposure of only about 560 J/cm2 in animals given fluorescein. Thus, the presence of fluorescein in these tissues enhanced the laser's effectiveness by a factor of 5. We suggest the use of evoked responses as a measure of laser photobiological effectiveness.

Animals↗
PubMed1984

[An evaluation of antimicrobial removal device to isolate bacteria from bacteremic patients with hematological disorders].

Antibiotics contained in blood specimens often inhibit bacterial growth in culture media. Recently, the antimicrobial removal device (ARD) containing resins to absorb antibiotics has been made available. To evaluate the effectiveness of the ARD, we investigated how much the antibiotics were removed by the ARD. The ARD method was compared to the conventional culturing method in isolating organisms from blood specimens of patients with hematological disorders receiving antimicrobial agents. The antibiotics, including cefotiam, cefsulodin, cefmenoxime, cefazolin and sulbenicillin, were proved to be almost completely removed by the ARD. Bacteria were detected only by use of the ARD in the blood cultures from 2 of 21 blood specimens (11 patients) entered in the study, while all of the blood cultures were negative by the conventional method. These isolated bacteria were S. aureus and P. aeruginosa, of which septicemias were cured by intensive antibiotic therapy for these bacteria. It is suggested that pretreatment with the ARD makes detection of bacteria easier in blood from the patients receiving antibiotics. Literatures were reviewed concerning improvement and shortened time for isolation of organisms by using the ARD.

Adult↗
PubMed1983

Possible significance of the pharmacological differentiation of beta-blocking agents in hemodynamic effects in essential hypertension.

Thirteen beta-blocking agents with different pharmacological properties were administered orally to 161 outpatients with essential hypertension for 5 weeks to assess their hemodynamic effects. Cardioselective ones, such as atenolol, metoprolol and acebutolol, reduced mean blood pressure (MBP) and the cardiac index. (CI) without any changes of the total peripheral resistance index. (TPRI). In the total 44 patients treated with these drugs, a positive correlation (r = 0.529, p less than 0.005) was found between the decrease in MBP and that of TPRI, but the decrease in MBP did not correlate with that of CI. Effects of non-cardioselective ones were classified arbitrarily into the following 3 patterns: 1) reduction of CI of more than 0.50 L/min/m2 and a slight increase of TPRI by more than 150 dyne . sec . cm-5 . m2 (nadolol, propranolol, o.prenolol and penbutolol), 2) reduction of TPRI by more than 150 dyne . sec . cm-5 . m2 (pindolol, bunitrolol and labetalol) and 3) the intermediate hemodynamic responses between the two patterns described above (carteolol, bupranolol and bufetolol). In all these 3 groups, the decrease in MBP correlated with that of TPRI (the first group, n = 45, r = 0.557, p less than 0.005; the second, n = 37, r = 0.525, p less than 0.005; the third, n = 35, r = 0.612, p less than 0.005), but did not correlate with the decrease of CI. These results suggest that the antihypertensive effects of beta-blocking agents mainly depend on the reduction of peripheral resistance, although their pharmacological properties are not uniform and their cardiodepressant effects are variable. Reduction of cardiac performance with these beta-blocking agents seemed to be a consequence of overall pharmacological actions including beta-receptor blockade, central effects and membrane stabilizing effects, and it may be antagonized by intrinsic sympathomimetic activity and the reduction in afterload for the heart. Vascular beta-receptor blocking action may play a part in decreasing the degree of reduction of the total peripheral resistance index, while their intrinsic sympathomimetic action on the vascular site may induce vasodilating effects.

Acebutolol↗
PubMed1983

Periodic acid-Schiff positive deposits associated with aging in mouse brains.

Deposits which were heavily stained with periodic acid-Schiff's solution were observed in a serial study of mouse brain section. Their histochemical reactions to ferric acid, calcium, glycogen, amyloid, and mucopolysaccharide were negative. Many deposits were observed within 100 microns from the midline of the dorsal part of the ventral thalamic nucleus. The deposit sizes were directly related to the age of the mice (r2 = 0.99).

Aging↗