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T Tamura

Publications and source records attributed to T Tamura.

At least 901 records · Page 50Linked to original sources
PubMed1990

Distribution and classification of acylphosphatase isozymes.

Distributions of acylphosphatase isozymes among organs of several animal species were investigated. Organ extracts of pig and chicken were treated with isozyme-specific antibodies, subjected to electrophoresis on a polyacrylamide gel, then the gel was stained for acylphosphatase activity. Both animals showed three activity bands; one band was named common type isozyme because of its wide distribution in testis, muscle, brain, heart, spleen, kidney, liver, and erythrocyte, and the other two bands were named muscle type isozymes because of their localization in skeletal muscle. This classification was supported by selective and quantitative reactions of the isozymes to the isozyme-specific antibodies. Because the two bands of the muscle type have the same amino acid sequence and differ only in modifications on an -SH group, it is suggested that pig and chicken have only the two major types of acylphosphatase. This conclusion was supported by similar experiments on dog, human, rabbit, and pigeon.

Acid Anhydride Hydrolases↗
PubMed1990

Core promoter of the mouse myelin basic protein gene governs brain-specific transcription in vitro.

The core promoter of the mouse myelin basic protein (MBP) gene from -36 to +12 was preferentially transcribed in brain nuclear extracts. Both the TATA at -34 and downstream elements to +12 were required for efficient, accurate and brain-specific transcription. From brain and liver nuclear extracts, we have partially purified the general transcription factor TFIID. The partially purified fractions contained TATA element binding factors of the MBP promoter as well as adenovirus major late promoter (MLP). The tissue-derived TFIID was functionally exchangeable for the HeLa TFIID, and directed transcription from the MLP. Surprisingly, the brain TFIID activated transcription from the MBP core promoter while the liver TFIID did to a much lesser extent. Exchange of the TATA-containing short DNA stretch to the MBP core promoter for a corresponding region of the mouse albumin promoter or MLP abolished the brain specificity. We found that several tissue-specific promoters other than MBP, such as mouse neurofilament and human alpha-1-antitrypsin promoters were also transcribed much more efficiently by the brain and liver TFIID, respectively. We suggest that different tissues contain functionally non-equivalent TFIID or TFIID-like activities.

Animals↗
PubMed1990

Cellular swelling during cerebral ischaemia demonstrated by microdialysis in vivo: preliminary data indicating the role of excitatory amino acids.

When rapid cellular swelling occurs, water moves from the extracellular space (ECS) into the cells and the concentration of ECS markers which do not move into the cells increases. Cellular swelling during cerebral ischaemia has therefore been demonstrated in vivo as an increase in ECS markers which is measurable with intracerebral electrodes. We attempted to detect the cellular swelling by brain microdialysis employing a similar principle. Dialysis probes were placed in the hippocampus, and perfused for 20 min with 14C-sucrose as an ECS marker. The probes were subsequently perfused without 14C-sucrose and the dialysate concentration of 14C-sucrose was determined at 1-min intervals. The dialysate concentrations of 14C-sucrose suddenly became elevated 1-3 min after the onset of cerebral ischaemia, indicating the occurrence of cellular swelling. The present technique is useful because it enables the mechanism of cellular swelling to be analyzed by observing the effects of pharmacological agents administered through a dialysis probe. Preliminary data indicating the role of excitatory amino acids in producing cellular swelling during cerebral ischaemia are presented as an example.

Amino Acids↗
PubMed1990

Early cellular swelling in experimental traumatic brain injury: a phenomenon mediated by excitatory amino acids.

Early cellular swelling following fluid-percussion brain injury was demonstrated in vivo by means of microdialysis in the rat. When rapid cellular swelling occurs, water moves from the extracellular space (ECS) into the cells and the extracellular concentration of ECS marker which does not move into the cells increases. Cellular swelling was therefore demonstrated in vivo as an increase in the dialysate concentration of 14C-sucrose ([14C-sucrose]d) pre-perfused as an ECS marker. The increase in [14C-sucrose]d occurred concomitantly with an increase in the dialysate concentration of K+ ([K+]d) representing large ionic fluxes. The increases in [K+]d and [14C-sucrose]d were both inhibited by kynurenic acid, a broad spectrum antagonist of excitatory amino acids (EAAs), which was administered through the dialysis probe. These findings suggest that early cellular swelling following traumatic brain injury is a result of ionic fluxes mediated by EAAs.

Amino Acids↗
PubMed1990

Measurement of calcium content of gallstones by computed tomography and the relationship between gallbladder function and calcification of gallstones.

To evaluate the relationship between gallbladder function and calcification of gallstones, we studied gallbladder contractility by oral cholecystography, the computed tomography (CT) number of stones for 30 gallstone patients, calcium content of 13 stones operatively extirpated, and the degree of inflammatory change in 13 surgical gallbladder specimens. There was significant correlation between the calcium content and CT numbers of stones, and 1% of the calcium content of gallstone was approximately equal to 40 Hounsfield Units (HU) of the CT number. The calcium content of stones in patients with normal gallbladder contractility was extrapolated to be below 1.5%, while that with poor contractility ranged from 0% to 21%. Additionally there is a possibility that calcium content increases, related to the inflammatory change of gallbladder. Hence our results suggested that measurement of the CT number of stones is useful to evaluate the calcium content of gallstones, and that the gallbladder contractility could be one of the factors to influence calcification of stones.

Cholecystography↗
PubMed1990

Phase II study of (glycolate-O,O') diammineplatinum(II), a novel platinum complex, in the treatment of non-small-cell lung cancer.

A total of 68 patients with non-small-cell lung cancer who either had not previously been treated (38) or had undergone prior therapy (30) were treated in a phase II study of (glycolate-O,O') diammineplatinum(II) (NSC 375 101D; 254-S), a new platinum complex. The drug was given as a single intravenous infusion at a dose of 100 mg/m2 every 4 weeks. All 68 patients could be evaluated for response and 62, for toxicity. Objective responses were seen in 10 of 68 cases (14.7%; 95% confidence interval, 7.3%-25.4%), and the median duration of response was 15 weeks (range, 8-23 weeks). The response rates were similar for previously untreated and treated patients (13% and 17%, respectively), including three previously treated with cisplatin. Myelosuppression was the dose-limiting toxicity. Thrombocytopenia (less than 100,000 platelets/mm3) and leukocytopenia (less than 3,000 WBC/mm3) were observed in 22 (35%) and 18 (29%) patients, respectively. Mild to moderate nausea and vomiting occurred in 45 cases (73%). No significant renal or neurotoxicity was observed. We conclude that as a single agent, 254-S is well tolerated but appears to have marginal activity against non-small-cell lung cancer.

Adenocarcinoma↗
PubMed1990

Palliative reconstruction of right ventricular outflow tract in tetralogy with hypoplastic pulmonary arteries.

Twenty-five symptomatic patients with tetralogy of Fallot underwent palliative reconstruction of the right ventricular outflow tract without closure of the ventricular septal defect. Their ages ranged from 5 months to 20 years (mean age, 3.5 years). Eight patients had had 13 prior systemic-pulmonary arterial shunts. There were six hospital deaths (24%). Three patients needed a repeat right ventricular outflow reconstruction. There was one late death. The other patients manifested clinical improvement; hematocrit decreased from 0.54 to 0.43 (p less than 0.01) and arterial oxygen saturation increased from 63.0% to 83.2% (p less than 0.01). The size of the pulmonary artery, defined as the ratio of the sum of the diameter of the right and left pulmonary arteries to the diameter of the descending aorta, increased from 0.72 to 2.06 (p less than 0.01). Sixteen patients underwent a corrective operation 2.4 years after palliation. The results of palliative right ventricular outflow tract reconstruction suggest that it may be an optional strategy for the treatment of symptomatic patients who have tetralogy of Fallot with severely hypoplastic pulmonary arteries.

Adolescent↗
PubMed1990

Multiple congenital aneurysms of the atria.

Aneurysms of both the left and right atria are very rare congenital abnormalities. A 3-year-old boy underwent operation with preoperative diagnosis of aneurysms of both atria and supraventricular tachyarrhythmia. The multiple aneurysms were resected during cardiopulmonary bypass. The patient was asymptomatic after operation and has maintained sinus rhythm.

Child, Preschool↗
PubMed1990

Determination of volume of vortices in poststenotic pulsatile flow by ultrasonic Doppler power ratio and spectrum analysis.

Based on the principle of ultrasonic Doppler flowmetry, a power ratio was derived from independent forward and reverse flow Doppler shift signals to measure a ratio of the volume of vortices to the total vessel volume in poststenotic separated flow. The ratio was also proportional to the ratio of the cross-sectional areas of vortices to the vessel lumen. In vitro pulsatile flow experiments were performed to test the methodology and to study flow separation and vortex shedding downstream from model stenoses. The averaged flow cross-sectional area ratio linearly correlated (r = 0.91) with the actual area reduction of the stenosis.

Carotid Artery Diseases↗
PubMed1990

Transformation of chicken fibroblasts by the v-fms oncogene.

The v-fms oncogene of the McDonough strain of feline sarcoma virus (SM-FeSV) encodes a plasma-membrane-associated tyrosine kinase (gp140v-fms) which is closely related, both structurally and functionally, to the c-fms-specified receptor for the macrophage colony stimulating factor (CSF-1). In mammalian fibroblasts, the natural producers of CSF-1, expression of v-fms leads to cell transformation. To study the interaction between CSF-1 and gp140v-fms molecules in a cell system that does not produce endogenous cross-reactive CSF-1, we have expressed the entire v-fms gene as well as a nontransforming deletion mutant (SC2) in chicken embryo cells (CEC). For this purpose the avian retroviral vectors pDS3 and pREP, based on Rous sarcoma virus, were used to isolate recombinant virus particles. CEC infected with virus that carried the entire v-fms gene expressed high amounts of gp140v-fms, comparable to those in SM-FeSV transformed NRK cells. However, these CEC remained flat, retained their fibronectin network, and did not produce enhanced levels of plasminogen activator. The cells grew faster than control CEC for more than 8 weeks but failed to form colonies in soft agar. Within 2 days after addition of CSF-1 to the growth medium, a transformed cell phenotype was induced, as judged by loss of the fibronectin network, again with a growth rate fourfold faster than that of the parental cells and with colony formation in soft agar. Moreover, human CSF-1 caused a rapid tyrosine phosphorylation of v-fms molecules detectable within 5 min after addition of the growth factor. In contrast, CSF-1 had none of the above effects on cells that expressed the SC2 v-fms deletion mutant.

Animals↗
PubMed1990

Evaluation of the deoxyuridine suppression test by using whole blood samples from folic acid-supplemented subjects.

We performed the deoxyuridine suppression test (dUST) along with assessment of folate and vitamin B-12 status in blood specimens from 136 normal women and 109 women with cervical dysplasia. All tests were repeated at 2, 4, and 6 mo in subjects with dysplasia during a randomized, double-blind intervention trial in which 50 received a 10-mg daily oral folic acid supplement (F group) and 59 received a placebo (P group). Median folate concentration increased fivefold in plasma and threefold in erythrocytes of F group beginning at the second months and remained elevated whereas concentrations of the P group remained unchanged. Vitamin B-12 values did not vary significantly in either group. The dUST value decreased from 10.4 +/- 4.6% (means +/- SD) pretreatment to 4.5 +/- 4.7% in F group after 2 mo (p less than 0.001). The dUST values had significant negative correlation with plasma and erythrocyte folate concentrations. However, erythrocyte folate had the greatest power to distinguish P group from F group.

Adult↗
PubMed1990

Less body fat accumulation in rats fed a safflower oil diet than in rats fed a beef tallow diet.

The effects on body fat accumulation of long-term feeding of high fat diets of differing fatty acid composition were studied in rats. The rats were meal-fed isoenergetic diets based on safflower oil or beef tallow for 4 mo. Each diet was freshly prepared every day throughout the experimental period. Oxygen consumption and carbon dioxide production for 6 h after meals were measured between the 50th and 54th d of the experimental period. Oxygen consumption for 3 h after meals was significantly greater in the safflower oil diet group than in the beef tallow diet group, indicating greater diet-induced thermogenesis in the former group. From the assessment of respiratory quotient, the fat oxidation rate was also higher in the former. After the experimental period (4 mo), body fat accumulation was significantly less in the rats fed safflower oil. This difference was, at least in part, ascribed to increased diet-induced thermogenesis and fat oxidation. Serum triacylglycerol level was markedly lower in the rats fed safflower oil than in those fed beef tallow. The lipoprotein lipase activities in heart and soleus muscle after meals appeared to be higher in the former than in the latter. These results suggest that the consumption of the safflower oil diet increased lipoprotein lipase activity in heart and skeletal muscle, resulting in the elevation of fat oxidation rate and the depression of serum triacylglycerol level.

Adipose Tissue↗
PubMed1990

Impaired milk folate secretion is not corrected by supplemental folate during iron deficiency in rats.

Decreased milk folate secretion in iron-deficient rat dams contributes to the impairment of folate metabolism in nursing pups. The present study was designed to assess whether impaired milk folate secretion secondary to iron deficiency is due to a decrease in the supply of folate to the mammary gland or to an inability of the mammary gland to effectively use folate. Rats were fed diets containing 0.5, 2.0 or 7.0 mg folate/kg and 8 (-Fe) or 250 (+Fe) mg Fe/kg throughout gestation and until d 17 of lactation. Regardless of dietary Fe content, maternal plasma, red blood cell, liver and kidney folate concentrations correlated with dietary folate content (r = 0.75-0.85, p less than 0.0001). With the exception of plasma folate level, which was 46% lower for -Fe than +Fe dams fed 0.5 mg folate/kg, no other differences in indices of folate status were noted between +Fe and -Fe dams. Dietary folate content had a direct impact on milk folate content in +Fe dams but not in -Fe dams. Mammary tissue methionine synthase and folylpolyglutamate synthetase activities were not depressed in Fe deficiency; rather, mean activities were elevated among -Fe dams fed 0.5 mg folate/kg. In conclusion, the reduction in milk folate secretion during Fe deficiency is not due to a decrease in the amount of folate supplied to the mammary gland; rather, the defect causing this reduction is specific to the mammary gland.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1990

A new transcription element in the JC virus enhancer.

The enhancer of JC virus restricts its gene expression to the brain. In a previous study, we demonstrated an enhancer element, nuclear factor I (NFI) motif, in the middle of the enhancer. Here, we demonstrate that the NFI motif is a tissue-specific element. We further present a new tissue-specific element, SacI motif, just upstream from the NFI motif. These motifs showed transcriptional enhancement both in vitro and in vivo and acted upon a heterologous adenovirus major late promoter. DNase I footprint analyses demonstrated that the SacI motif bound to a brain nuclear factor, and that its binding region overlapped with the NFI motif. Gel shift experiments with the SacI motif revealed that the populations of SacI motif factors in the brain and HeLa cell extracts were different. Together with our previous findings about tissue-specific NFI-like factor(s), cooperation of NFI motif and SacI motif factors may be required for the strong brain specificity of the viral gene expression.

Animals↗
PubMed1990

Adenylate cyclase system in fetal rat keratinizing epidermal cells (FRSK cells) and SV40-transformed human keratinocytes.

The adenylate cyclase system of FRSK cells, a cultured cell line of fetal rat epidermal keratinocytes, and SV40-transformed human keratinocytes was investigated. Stimulators of the human epidermal adenylate cyclase, epinephrine, adenosine, and prostaglandin E2 increased cyclic AMP levels of these cells. There were marked differences in the stimulatory effects; while epinephrine revealed a much stronger effect than the other stimulators in FRSK cells, epinephrine and prostaglandin E2 revealed similarly marked effects in SV40-transformed cells. Histamine had little or only slight effect on the cyclic AMP levels of these cells. Cholera toxin and forskolin, which work on the stimulatory guanine nucleotide binding protein (Gs) and the catalytic component of adenylate cyclase, respectively, also increased cyclic AMP levels. Northern blot hybridization analysis revealed that both FRSK cells and SV40-transformed human keratinocytes express mRNAs for the beta 2-adrenergic receptor, as well as the stimulatory and inhibitory guanine nucleotide binding proteins (Gs and Gi, respectively). The presence of Gs as well as Gi were confirmed by cholera toxin-, and pertussis toxin (IAP)-induced ADP-ribosylation of membranous proteins of these cells. Our results indicate that both FRSK cells and SV40-transformed human keratinocytes express the fundamental components of the adenylate cyclase system. These cell lines might be useful tools for the analysis of the adenylate cyclase system in epidermal keratinocytes.

Adenosine↗