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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 487 records · Page 27Linked to original sources
PubMed1990

Synthetic anthracyclines: regiospecific total synthesis of D-ring thiophene analogues of daunomycin.

The key anhydride 2-acetoxy-[2-carboxy-5-(trimethylsilyl)thiophen-3-yl]acetic acid anhydride (8), prepared from (2-carboxythiophen-3-yl)acetic acid (5), underwent a strong base-induced cycloaddition reaction with the chloroquinone acetal (11) to give the 7,7-ethylenedioxy-2-trimethylsilyl-6,7,8,9- tetrahydroanthra[2,3-b]thiophene-5,10-dione (12) regioselectively. Similarly, the regioisomeric 8,8-ethylenedioxy-2-trimethylsilyl-6,7,8,9-tetrahydroanthra[2,3-b] thiophene- 5,10-dione (30) was obtained by the strong base-induced cycloaddition reaction of 8 with the chloroquinone acetal (29). These cycloadducts (12 and 30) were converted to D-ring thiophene analogues (28 and 38) of daunomycin (1a). Another D-ring thiophene analogue (42) which has a trimethylsilyl substituent in the D-ring was also prepared.

Animals↗
PubMed1990

Synthetic anthracyclines: regiospecific total synthesis of a D-ring indole analogue of daunomycin.

The 4-methoxy-5-methylpyrano[4,3-b]indole-1,3(4H,5H)-dione (9), prepared from methyl 3-methoxycarbonyl-1-methylindol-2-yl acetate (6), underwent a strong base-induced cycloaddition reaction with 2-chloro-6,6-ethylenedioxy-5,6,7,8-tetrahydro-1,4-naphthoquinone (11) to give the tetrahydronaphtho[2,3-b]carbazole-7,12-dione (10), regioselectively. The cycloadduct (10) was successfully converted to a D-ring indole analogue of daunomycin (1a).

Animals↗
PubMed1990

Clinical characteristics and possible role of coronary artery spasm in syncope and/or aborted sudden death.

We investigated the clinical and pathophysiologic characteristics in patients with vasospastic angina who developed syncope and/or experienced aborted sudden death (SD). Vasospastic angina was diagnosed using the methylergonovine test. Syncope was found in 32 (10.4%) patients among 309 who were admitted to our institute in a one-year period. The most frequent cause of syncope was ventricular tachycardia which was found in 10 (31.2%) of the 32 patients. The next important cause of syncope was vasospastic angina which was found in 7 patients (21.8%). Among the 7 patients with vasospastic angina who experienced one or more syncopal episodes, there were 3 patients with aborted SD, 3 with syncope and one with shock. Cardiovascular collapse was observed in 4. Interior wall ischemia was found in 5 and anterior wall ischemia in 2 during the methylergonovine test. None of the 7 patients had significant coronary stenosis. Two patients had no prodromal symptom such as chest pain. Our results suggest that coronary artery spasm may be one of the most frequent cardiovascular diseases that causes syncope which is not always accompanied by a prodromal symptom. Therefore, coronary spasm should be distinguished in patients with unexplained syncope or aborted SD.

Coronary Angiography↗
PubMed1990

The participation of sterol carrier protein2 in cholesterol esterification in rat adrenal microsomes.

The effect of sterol carrier protein2 (SCP2) purified from rat liver on the formation of cholesterol esters by acyl-CoA: cholesterol acyl-transferase (ACAT: EC 2.3.1.26) in rat adrenal microsomes was studied. The rate of incorporation of [1-14C]oleoyl-CoA into cholesteryl oleate was determined in the presence or absence of exogenously added cholesterol or SCP2, or both. The addition of SCP2 had no effect on the formation of cholesterol esters from endogenous cholesterol by ACAT in rat adrenal microsomes. In contrast, the formation of cholesterol esters from exogenous cholesterol by ACAT was dose-dependently increased by the addition of SCP2. These experiments showed that SCP2 had an enhancing effect on cholesterol esterification by ACAT in rat adrenal microsomes most likely by modulating the availability of exogenous cholesterol and that SCP2 may participate in the formation of cholesterol esters in the rat adrenal gland.

Adrenal Cortex↗
PubMed1990

Possible site of action of 5-hydroperoxyeicosatetraenoic acid derived from arachidonic acid in ACTH-stimulated steroidogenesis in rat adrenal glands.

The site of action of 5-hydroperoxyeicosatetraenoic acid (5-HPETE) in ACTH-induced stimulation of steroidogenesis was examined in rat adrenocortical fasciculata cells. Prior addition of AA861, a specific inhibitor of 5-lipoxygenase, had no significant effect on cyclic AMP-dependent protein kinase activity and cholesterol esterase activities, when stimulated by ACTH in adrenocortical cells, compared with that stimulated by ACTH alone. Cholesterol accumulation in the mitochondria of cells treated with ACTH and cycloheximide was also not altered by pretreatment with AA861. We found, however, that pregnenolone formation, stimulated by ACTH, decreased in a dose-dependent manner when cells were pretreated with AA861. The inhibition of ACTH-stimulated pregnenolone formation by treatment with AA861 was restored only by prior addition of 5-HPETE. Furthermore, addition of AA861 also did not affect the conversion of pregnenolone into corticosterone. In conclusion, 5-HPETE may act at the level of the mitochondria in ACTH-induced steroidogenesis in rat adrenal fasciculata cells.

Adrenal Cortex↗
PubMed1990

Occurrence and tissue distribution of both NADH- and NADPH-linked aquacobalamin reductases in some vertebrates.

To elucidate the synthesis of cobalamin coenzymes in view of comparative biochemistry, tissue distribution of activity of aquacobalamin reductase [EC 1.6.99.8] catalyzing the reduction of hydroxocobalamin to cob(II)alamin was studied in some vertebrates. Activity of NADH- or NADPH-linked aquacobalamin reductase (or both) was found in some tissues of monkey, rat, cow, hog, chicken, fish, and frog. The liver homogenates of these vertebrates contained both NADH- and NADPH-linked enzymes. Monkey and rat livers accounted for more than 80% of total activities of both NADH- and NADPH-linked enzymes. Ratios of activities of the liver NADH- and NADPH-linked enzymes were above 1.0 in some land animals (monkey, rat, cow, and hog) but below 1.0 in water animals (sea and freshwater fishes). These different ratios are presumably due to the difference in the metabolisms of cobalamin and/or in the other cellular components between land and water animals.

Animals↗
PubMed1990

[Renal cell carcinomas. Clinical studies on diagnostic opportunities].

We clinically investigated 150 subjects suffering from renal cellular cancers as to their diagnostic opportunities. They underwent medical treatment after being hospitalized in the urology section of Gunma University from 1961 to 1988. We divided the cases into two groups to be compared: 63 cases in the first period (1961 to 1979) before introduction of ultrasound (US) and scan (CT), and 87 cases in the second period (1980 to 1988) after introduction of the above devices. The number of patients increased in the second period, year by year. Evaluation of symptoms indicated that 62 of the 63 cases in the first period belonged to the suspected category; the remaining one (1.6%) belonged to the incidental category, but its diagnosis followed intravenous pyelography (IVP). Out of the 87 cases in the second period, 29 (33.3%) belonged to the incidental category which was recognized to be increasing; 19 cases were diagnosed based on US findings, and 6 cases on CT. Concerning prognosis, a significantly favorable prognosis was indicated for the second-period cases as compared with those of the first period, from the statistical point of view. With respect to progressive degree and prognosis of 58 suspected cases and 29 incidental cases in the second period, statistically there were significantly more cases of low grade and, therefore, with favorable prognosis in the latter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Severe hypersensitivity to mosquito bites associated with natural killer cell lymphocytosis.

A 2-year-old girl showed exaggerated skin reactions to mosquito bites and associated general symptoms, including a high temperature, lymphadenopathy, and hepatosplenomegaly. Peripheral blood lymphocytes contained a high percentage of CD2+, CD3-, CD4-, CD8-, CD11b+, CD16+, CD38+, CD56+, CD57-, and HLA-DR+ large granular lymphocytes that exhibited a marked natural killer cell activity. Immunohistochemically, biopsy specimens taken from the lesional skin demonstrated an infiltrate of the cells bearing the natural killer cell phenotype, indicating a role of these cells in the development of the abnormal skin reactions to mosquito bites and other systemic manifestations. Our case suggests that natural killer cell lymphocytosis may show severe hypersensitivity to mosquito bites as the most outstanding manifestation.

Animals↗
PubMed1990

[Open surgery of elderly patients with benign prostatic hypertrophy].

Thirty three patients with benign prostatic hypertrophy (BPH) over age 80 who had undergone an open prostatectomy at our ward in the period of January of 1968-December of 1987 (20 years), were retrospectively studied for their complications before, during, or after the operation and prognosis. Preoperative complications were observed at a very high rate. When these complications may influence the prognosis, prudent care is required. The incidence of complications during or after the operation seemed also to be slightly high. This is probably because the number of patients with recurring urinary retention or those who had received cystostomy before the operation were relatively high among the elderly people. In such cases especially prudent care is required, for the prognosis may be poor. About 88% of the patients felt better post-operatively and had a good prognosis. In addition, there was no indication of the operation shortening their life. Consequently, an open prostatectomy was considered to be useful for elderly patients.

Aged↗
PubMed1990

[The clinical role of anaerobic threshold in physical training of patients with recent myocardial infarction].

Twenty-seven patients with recent myocardial infarction were studied to evaluate the clinical usefulness of the anaerobic threshold (AT) in physical training as cardiac rehabilitation at home. The 27 patients were divided into trained and control groups. Symptom-limited treadmill exercise tests were conducted before and six weeks after the prescribed aerobic training. Heart rate (HR), systolic blood pressure and respiratory gases (VO2, VCO2 and VE) were noninvasively measured throughout the exercise periods. AT was defined as systemic increase in the ventilatory equivalent O2 (VE/VO2) without an increase in the ventilatory CO2 (VE/VCO2) during the increasing work load. The patients in the trained group were obliged to perform aerobic walking training requiring 90-100% HR of the AT level for 30 min, four to six days per week. 1. In the trained group, exercise time, peak VO2, and AT on treadmill performance were significantly increased compared with those of the pre-training values. However, in the control group, these parameters were not significantly changed. A significant reduction in double products was observed during submaximal workload in the trained group. 2. Factors related to the training effects: The training effect expressed by delta peak VO2 correlated significantly with the initial peak VO2 (pre-training peak VO2) (y = 35.4 - 1.29x, r = 0.70), but there was no correlation between left ventricular function and delta peak VO2. These results indicated that aerobic exercise at home guided by the AT level is safe and beneficial for patients with recent myocardial infarction.

Anaerobic Threshold↗
PubMed1990

[Study on occlusal sounds in children. (1). Influences of the velocity of tooth tapping on the occlusal sound].

The purpose of this study was to evaluate the influence of the maximum velocity of the mouth closing phase on the occlusal sound. Six subjects examined were divided into two groups (children and young adults). Occlusal sounds generated by the tooth tapping were obtained with in microelectronic condenser microphone placed on infra-orbital and external auditory canal. Three parameters were used for the measuring points such as 1) maximum velocity of the closing phase, 2) maximum amplitude of the occlusal sound, 3) duration of the occlusal sound. The results obtained in the present study were as follows: 1) The waveform of occlusal sounds obtained from infra-orbital showed more clearly than that obtained from the external auditory canal. 2) With increasing velocity, both the values of maximum amplitude and duration showed a tendency to increase in both groups. 3) The prolonging of the duration was apparent in the children. The results obtained in the study suggest that the analysis of the occlusal sounds generated by tooth tapping can apply to aid in the functional diagnosis of occlusion in children.

Adult↗
PubMed1990

[Changes in the muscle fiber conduction velocity (MFCV) due to the masticatory muscle development. 1. Preliminary study in adults].

The purpose of this study was to investigate the methods involved in observing the muscle fiber conduction velocity (MFCV) both in the masseter muscle and the m. biceps brachii in healthy persons. Three adults were the subjects in this study, none of whom had any gnathofacial dysfunction. The EMG activities were recorded from the m. biceps brachii with the arm bent at right angles and the masseter muscle in the intercuspal position, in both muscles during 50% of maximum voluntary isometric contraction on the habitual side. Three types of surface electrodes were used. Type 1. the disc type electrodes array arranged straight, Type 2. the disc type electrodes array arranged independently, Type 3. the strip type surface electrodes array arranged straight. The EMG activities preamplified at three conditions of time constant, e.g., 0.003, 0.01, 0.03 sec on m. biceps brachii were analyzed through a personal computer system and a FFT analyser. The conduction velocity was calculated by the cross-correlation method. The results obtained in this study were as follows: 1) No differences in the MFCV between the time constant were noticed. 2) The electrode array arranged straight was effective in the measurement of the MFCV in adults and in particular the strip type series electrodes array arranged straight was the most effective to measure the MFCV in the masseter muscle. 3) The average MFCV of the m. biceps brachii and the masseter muscle were 4.13 +/- 0.29 m/sec and 14.28 +/- 1.21 m/sec respectively.

Adult↗
PubMed1990

[Study on occlusal sounds in children. 2. Fast Fourier Transform (FFT) analysis on the occlusal sounds].

The purpose of this study was to evaluate the Fast Fourie Transform (FFT) analysis of the occlusal sounds generated by tooth tapping which may apply in assisting in the functional diagnosis of occlusion in children. The fifteen subjects examined were divided into three groups: the first group with deciduous dentition, the second with mixed dentition and the third with permanent dentition. Occlusal sounds generated by tooth tapping at the rate of 76 times per minute were obtained with a micro-electronic condenser microphone placed on the infra-orbital region. For the time wave, the wave pattern of the occlusal sound was classified into two groups: 1) Impact sound, 2) Slide sound, and the ratio of appearance was examined. For the spectrum, three parameters were chosen for the measuring points such as 1) frequency range, 2) peak frequency, 3) strength of the peak frequency. The results obtained in the present study were summarized as follows: 1) Occlusal sounds in the deciduous dentition, the appearance of sliding sound was noticed in over 50% of the cases while on the permanent dentition, the sliding sound was dominant. 2) The power spectrum of the occlusal sound showed generally two or three peaks. 3) The range of frequency was recognized to be extended on the sliding sound when compared with the impact sound.

Child↗
PubMed1990

[Analysis of occlusal contacts of children by the T-Scan system. (1) The reproducibility of the sensor].

The present study was designed to discuss the reproducibility and the clinical usage of the T-Scan system in children. A plastic model of a normal permanent dentition was used for the study. The model was pressed on the sensor of the T-Scan system in maximum intercuspation under various assigned pressures (10, 20, 30, 40 and 50 kg) which were controlled by a press machine (Auto Graph AG-5000C). The pressings were made under following conditions, such as 1) the sensor handle was fixed, 2) the sensor handle was free and 3) the sensor handle was free but the maxilla arch form was marked on the sensor by the silicone impressional material. The total number of tooth contacts were counted and sagittal and the vertical distance from midline to the tooth contacts were measured. The results obtained in the present study are summarized as follows: 1) The number of tooth contacts became stable, when the pressing sensor was exercised several times. 2) The more pressure raised on the sensor, the more the number of tooth contacts increased, and the more the coefficient of variation tended to decline. 3) The arch model displayed on the T-Scan system was not exactly represented in the actual dental arch. 4) Due to the marking by silicone impressional material on the sensor, the reproducibility of the T-Scan system was further improved.

Bite Force↗
PubMed1990

[Enhancement of cell growth by human interferons].

The effects of human interferons (HuIFN) on the human osteosarcoma cells were examined. HuIFN-alpha, -beta and -gamma enhanced dose-dependently the cell growth. There was no difference in the degree of the enhancement of the cell growth among HuIFN-alpha, -beta and -gamma. The higher the cell density was, the lower the degree of the enhancement of the cell growth. When HuIFN-gamma was neutralized with anti-HuIFN-gamma, the enhancement of cell growth was not found.

Adolescent↗