Biomedical subjects

Y Sagara

Publications and source records attributed to Y Sagara.

At least 163 records · Page 9Linked to original sources

PubMed1992

Thapsigargin inhibits contraction and Ca2+ transient in cardiac cells by specific inhibition of the sarcoplasmic reticulum Ca2+ pump.

Regulation of the level of ionized calcium, [Ca2+]i, is critical for its use as an important intracellular signal. In cardiac and skeletal muscle the control of fluctuations of [Ca2+]i depend on sarcolemmal and sarcoplasmic reticulum ion channels and transporters. We have investigated the sesquiterpine lactone, thapsigargin (TG), because of its reported action to alter cellular calcium regulation in diverse cell types, including striated muscle cells. We have combined biochemical and physiological methods at the cellular level to determine the site of action of this agent, its specificity, and its cellular effects. Using a patch-clamp method in whole cell configuration while measuring [Ca2+]i with Indo-1 salt, we find that TG (100 nM) largely blocks the contraction and the [Ca2+]i transient in rat ventricular myocytes. Analysis of these data indicate that no sarcolemmal current or transport system is directly altered by TG, although indirect [Ca2+]i-dependent processes are affected. In permeabilized myocytes, TG blocked oxalate-stimulated calcium uptake (half-maximal effect at 10 nM) into the SR. However, TG (100 microM) had no effect on Ca(2+)-induced Ca(2+)-release in purified muscle (ryanodine-receptor enriched) vesicles while clearly blocking Ca(2+)-ATPase activity in purified (longitudinal SR) vesicles. We conclude that in striated muscle TG markedly alters calcium metabolism and thus alters contractile function only by its direct action on the Ca(2+)-ATPase.

Animals↗

PubMed1992

Characterization of the inhibition of intracellular Ca2+ transport ATPases by thapsigargin.

The effects of thapsigargin (TG), a specific inhibitor of intracellular Ca(2+)-ATPases, were studied on vesicular fragments of sarcoplasmic reticulum (SR) membranes. Inhibition of Ca2+ transport and ATPase activity was observed following stoichiometric titration of the membrane bound enzyme with TG. When Ca2+ binding to the enzyme was measured in the absence of ATP, or when one cycle of Ca(2+)-dependent enzyme phosphorylation by ATP was measured under conditions preventing turnover, protection against TG by Ca2+ was observed. The protection by Ca2+ disappeared if the phosphoenzyme was allowed to undergo turnover, indicating that a state reactive to TG is produced during enzyme turnover, whereby a dead end complex with TG is formed. Enzyme phosphorylation with Pi, ATP synthesis, and Ca2+ efflux by the ATPase in its reverse cycling were also inhibited by TG. However, under selected conditions (millimolar Ca2+ in the lumen of the vesicles, and 20% dimethyl sulfoxide in the medium) TG permitted very low rates of enzyme phosphorylation with Pi and ATP synthesis in the presence of ADP. It is concluded that the mechanism of ATPase inhibition by TG involves mutual exclusion of TG and high affinity binding of external Ca2+, as well as strong (but not total) inhibition of other partial reactions of the ATPase cycle. TG reacts selectively with the state acquired by the ATPase in the absence of Ca2+. This state is obtained either by enzyme exposure to EGTA, or by utilization of ATP and consequent displacement of bound Ca2+ during catalytic turnover.

Adenosine Triphosphate↗

PubMed1992

Direct expression in Escherichia coli and characterization of bovine adrenodoxins with modified amino-terminal regions.

Four forms of bovine adrenodoxin with modified amino-termini obtained by direct expression of cDNAs in Escherichia coli are Ad(Met1), Ad(Met-1), Ad(Met-12), and Ad(Met6). The shoulder numbers represent the site of translation initiator Met at the amino-termini. The adrenodoxins, except for Ad(Met-1), were purified from the cell lysate and the ratios of A414-to-A276 of the purified proteins were over 0.92. NADPH-cytochrome c reductase activities of the three forms of adrenodoxin in the presence of adrenodoxin reductase were the same as that of purified bovine adrenocortical adrenodoxin. However, as cytochrome P-450SCC reduction catalyzed by Ad(Met6) was about 60% of that by Ad(Met1), the contribution of the amino-terminal region for the electron transfer or binding to cytochrome P-450SCC would need to be considered.

Adrenodoxin↗

PubMed1992

Characterization of a cis-acting regulatory element involved in human-aromatase P-450 gene expression.

The characteristics of a cis-acting regulatory region involved in the human-aromatase P-450 gene have been examined by transient expression analysis. The region spans from -242 - -166 relative to the cap site of the gene. A fragment containing the region excised from the gene enhances heterologous promoter activity as well as its own promoter activity in a position-independent and orientation-independent manner. The fragment exerts its enhancer activity in human BeWo choriocarcinoma cells in which the aromatase P-450 gene is expressed, but not in other cell lines tested. Deletion of 38 bp from the 3' end of the fragment results in a complete loss of enhancer activity. A gel-retardation assay with nuclear extracts from BeWo cells suggests the existence of a nuclear factor(s) which interacts with the fragment. These results suggest that the regulatory element in the fragment is involved in efficient transcription of the human-aromatase P-450 gene.

Animals↗

PubMed1992

A conformational mechanism for formation of a dead-end complex by the sarcoplasmic reticulum ATPase with thapsigargin.

Thapsigargin (TG), a plant sesquiterpene lactone extract, interacts tightly with the sarcoplasmic reticulum (SR) Ca2+ transport ATPase yielding a 1:1 stoichiometric complex. In addition to inhibiting steady state enzyme activity, TG can be shown to inhibit two individual partial reactions of the ATPase cycle (i.e. Ca2+ binding in the absence of ATP and enzyme phosphorylation by Pi in the absence of Ca2+) even when these reactions are studied separately without interdependence. As the two partial reactions occur at domains relatively distant from each other in the protein structure, it is apparent that the TG induced perturbation involves the entire enzyme. The rate of TG interaction with the ATPase, as estimated by the onset of functional inhibition and by the development of an intrinsic fluorescence signal, is relatively low in the presence of Ca2+. The interaction is much faster when Ca2+ is removed from the medium by the addition of EGTA or is dissociated from the enzyme by utilization of ATP. When the TG interaction with the ATPase is studied in the presence of Ca2+ as a function of temperature (15-35 degrees C) and pH (6.0-8.0), two distinct kinetic components are observed: a fast component which is prevalent at high temperature and low pH, and a slow component which is prevalent at low temperature and high pH. This pattern suggests that the enzyme resides in two states, whose relatively slow equilibration is temperature- and pH-dependent. As only one state is reactive to TG, the enzyme population residing in this state reacts immediately with TG. On the other hand, the enzyme population residing in the alternate state must undergo slow conversion to the reactive state before being affected by TG. It can be also demonstrated that in the presence of Ca2+ TG shifts the ATPase from a refractory state to a state which is able to form bidimensional crystalline arrays stabilized by decavanadate. It is concluded that TG reacts specifically with the ATPase conformation which is prevalent in the absence of Ca2+, thereby forming a catalytically inactive dead-end complex.

Adenosine Triphosphatases↗

PubMed1992

Immunohistochemical studies on oncogene products (EGF-R, c-erbB-2) and growth factors (EGF, TGF-alpha) in human breast cancer: their relationship to oestrogen receptor status, histological grade, mitotic index and nodal status.

In this investigation, 83 human mammary carcinomas were examined for the expression of oestrogen receptor (ER), epidermal growth factor receptor (EGF-R), epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), c-erbB-2, histological grade, mitotic index and nodal status, all of which are reportedly prognostically significant factors (Bloom and Richardson 1957; Baak et al. 1985; Wright et al. 1989). ER expression was biochemically recognized in 43.4% of mammary carcinomas, and EGF-R, EGF, TGF-alpha and c-erbB-2 were histochemically recognized in 25.3, 14.5, 27.7 and 18.0% of mammary carcinomas examined respectively, using conventional sections of buffered formalin-fixed, paraffin-embedded tissue and monoclonal or polyclonal antibodies. There were significant relationships between negative ER and positive EGF-R or TGF-alpha; positive EGF-R and TGF-alpha; positive EGF-R and c-erbB-2; and positive c-erbB-2 and TGF-alpha. The single changes which were the negative ER and the positive c-erbB-2 correlated with histological grade and mitotic index. Co-expression of EGF-R and TGF-alpha correlated with positive nodal status. Therefore, the present investigation indicates that the negative ER, single expression of c-erbB-2 and co-expression of EGF-R and TGF-alpha are important markers which contribute indirectly to prognosis, which reconfirms previous findings on the former two while adding the new finding that immunohistochemical demonstration of expression of EGF-R and TGF-alpha may provide useful information for selecting the appropriate treatment.

Biomarkers, Tumor↗

PubMed1992

Role of afferent neural input in regression of sensory paralysis during epidural analgesia.

This study was designed to determine the role of the afferent peripheral neural input in the regression of sensory analgesia during epidural analgesia. Eighteen patients who underwent minor obstetric or gynecologic surgery under lumbar epidural analgesia with lidocaine were divided into three groups. Group A received electrical single twitch stimulation at the spinal nerve dermatome one segment rostrad of the proximal extent of sensory paralysis. Group B received electrical twitch stimulation at the anterior crural region where nerve block may have been most profound in this study. Group C was assigned as a control and did not receive any stimulation. The patients received the stimulation for 60 min (i.e., from 80 to 140 min after the epidural injection). The range of sensory analgesia at 140 min was compared with that at 80 min. The regression of sensory analgesia in group B or C was 1 +/- 0 (mean +/- SD) spinal nerve segments, but in group A it was 5 +/- 1, which was significantly (P less than 0.0025) larger than the others. We conclude that the afferent peripheral neural input to a spinal segment where the nerve block is incomplete may accelerate the regression of sensory analgesia from epidural analgesia.

Adult↗

PubMed1992

Amplification of nocturnal melatonin secretion in women with nocturnal hyperprolactinemia.

In order to assess the pathophysiological role of melatonin (MLT) in nocturnal hyperprolactinemia (NH), nocturnal serum MLT and prolactin (PRL) levels were measured in samples collected every 2h over a 12-hour period (2000h-0800h) from 5 normal women and 9 women with NH under physiological light/dark condition (lights off from 2100h to 0600h). Furthermore, differences in the PRL response to acute oral administration of MLT (1 mg or 5 mg) during the daytime between the 2 groups was studied. Nocturnal MLT levels in patients with NH were significantly higher (p < 0.02) than in normal women. The maximal PRL levels (52.6 +/- 26.7 ng/ml at 2400h) during the night in patients with NH were significantly higher (p < 0.05) and were reached 4h earlier than in normal women. The response to administration of 1 mg of MLT was not different between the 2 groups. However, administration of 5 mg of MLT to normal women resulted in a rapid and prominent PRL release, similar to that observed at nighttime in patients with NH. These results indicate that the abnormal PRL release in patients with NH is not due to higher sensitivity to MLT. However, the elevated MLT levels in patients with NH may be related to the neuroendocrine disorder.

Adult↗

PubMed1992

[Changes in right ventricular function with unilateral pulmonary artery occlusion test for pre-operative evaluation prior to lung resection].

We measured the right ventricular ejection fraction (RVEF) before and during unilateral pulmonary artery occlusion test (UPAO) by thermodilution method. We also measured the right ventricular end-diastolic volume index (RVEDVI), right ventricular end-systolic volume index (RVESVI), and right ventricular stroke volume index (RVSVI). RVEF and RVSVI were significantly decreased by UPAO (p less than 0.05), but there were no obvious changes in RVEDVI and RVESVI. Some cases showed only a small decrease in RVEF by UPAO, even though their total pulmonary vascular resistance indices were over 700 dyne.sec.cm-5/m2 during UPAO. On the other hand, some cases had a decreased in RVEF of more than 10% by UPAO, even though their total pulmonary vascular resistance indices were under 400 dyne.sec.cm-5/m2 during UPAO. We consider that it is important to measure right ventricular functions such as RVEF together with pulmonary vascular hemodynamics in the pre-operative evaluation of cases of lung resection.

Aged↗

PubMed1992

[Application of laser in the treatment of spontaneous pneumothorax and emphysema].

From August 1990 to August 1991, sixteen patients with bullae or blebs (pneumothorax 9, giant bullae 5, bullous emphysema 2) were treated by CO2 laser ablation under limited thoracotomy. We found the irradiation of bullae or blebs by CO2 laser quite effective in eliminating these bullous lesions which were often multiple and inoperable by conventional methods. Histological examination revealed the wall of bullae where CO2 laser was applied became thick with dense fibrous tissues and degenerated collagen fibers which, however, were not disrupted. The procedure was safe and we were able to operate patients with disabling emphysema. Because CO2 laser can penetrate only 0.2-0.3 mm of tissue thickness, it is suitable for the ablation of bullous lesions which have thin walls and rapidly shrink and collapse by irradiation leaving thick walled scar tissues. Removing multiple bullae and blebs in patients with bullous emphysema can improve gas exchange by reducing dead spaces and elevating the diaphragm which is often flat and downward displaced because of hyperinflation in these patients. We are planning to incorporate thoracoscopy for this operation to make the procedure less invasive.

Adolescent↗

PubMed1991

Nucleotide sequences of avian cardiac and brain SR/ER Ca(2+)-ATPases and functional comparisons with fast twitch Ca(2+)-ATPase. Calcium affinities and inhibitor effects.

Two similar forms of the cardiac/slow Ca(2+)-ATPase (SERCA2a and SERCA2b), differing in sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobility, are expressed in chicken heart and brain (Kaprielian, Z., Campbell, A. M., and Fambrough, D. M. (1989) Mol. Brain Res. 6, 55-60). In the current study, cDNAs encoding each form were cloned and sequenced. Chicken SERCA2a is 94% identical to its rabbit homologue, while SERCA2b has an extended carboxyl terminus with 38 of 49 amino acids identical to mammalian homologues. SERCA2b mRNA contains the SERCA2a encoding sequence within its 3'-untranslated region. Chicken genomic DNA sequence reveals that the alternate RNA splicing used to produced SERCA2a and SERCA2b subtypes involves a splice site within an exon. Tissue culture cells expressing the avian SERCA2a, SERCA2b, and SERCA1, each targetting to the endoplasmic reticulum, were used to measure Ca2+ affinities and inhibitor effects; no differences among the three pumps were detected.

Amino Acid Sequence↗

PubMed1991

Inhibition of the sarcoplasmic reticulum Ca2+ transport ATPase by thapsigargin at subnanomolar concentrations.

ATP-dependent calcium uptake by isolated sarcoplasmic reticulum vesicles is inhibited by concentrations of free thapsigargin as low as 10(-10) M. This effect is due to primary inhibition of the Ca(2+)-dependent ATPase which is coupled to active transport. When binding of calcium to the activating sites of the enzyme is measured under equilibrium conditions in the absence of ATP, addition of thapsigargin produces strong inhibition. On the other hand, if [tau-32P]ATP is added to ATPase preincubated with Ca2+ under favorable conditions, significant levels of 32P-phosphorylated intermediate are still formed transiently, even in the presence of thapsigargin. The phosphoenzyme, however, decays rapidly as the calcium-enzyme complex is destabilized as a consequence of ATP utilization, and formation of the thapsigargin-enzyme complex is favored. Formation of the thapsigargin-enzyme complex is also favored by Ca2+ chelation with EGTA, with consequent inhibition of the enzyme reactivity to Pi (i.e. reverse of the ATPase hydrolytic reaction). Neither the Ca(2+)- and ATP-induced Ca2+ release from junctional sarcoplasmic reticulum nor the Ca(2+)- and calmodulin-dependent ATPase of plasma membranes (erythrocyte ghosts) were found to be altered by thapsigargin at such low concentrations.

Adenosine Triphosphate↗

PubMed1991

The effect of interferon on carcinogenesis by N-ethyl-N'-nitro-N-nitrosoguanidine in the duodenum of mice.

The inhibitory effect of murine interferon alpha/beta (Mu-IFN) on the induction of adenocarcinoma of the duodenum in C57BL/6 mice given N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) was examined. ENNG was given continuously in drinking water for 4 weeks and Mu-IFN was given intraperitoneally for 12 weeks. Then, the duodenal tumors of mice were examined stereomicroscopically and histologically. The level of IFN activity and natural killer (NK) activity were evaluated after an intraperitoneal single injection of Mu-IFN, and the level of NK activity was evaluated 2, 5 and 8 weeks after giving ENNG and Mu-IFN. In the mice given Mu-IFN, the incidence of duodenal tumors was significantly decreased (P less than 0.01), compared with that in mice given ENNG alone. Further, anti-asialo GM1 was given intraperitoneally every 5 days for 8 weeks to depress NK function and the incidence and size of duodenal tumors were examined. The results indicated that NK cells also have an important effect on the process of carcinogenesis. These data suggest that chemoprevention with IFN may be feasible.

Adenocarcinoma↗

PubMed1991

Cisplatin suppository: preparation, release characteristics and clinical evaluation.

Cisplatin (CDDP) has attracted attention as a chemotherapeutic agent for the treatment of uterine endometrial carcinoma but causes serious side effects, including renal toxicity. CDDP suppositories containing NaCl at different concentrations were prepared to enhance the efficacy and to reduce the side effects of CDDP. The release characteristics, melting point and viscosity of the suppositories were first studied. The rate of CDDP release increased as the NaCl concentration increased: it was 12% 12 h after administration of suppositories containing no NaCl, but 32% with 0.2% NaCl. The melting point was raised by addition of NaCl: 35.5 degrees C without NaCl and 36.5 degrees C with 0.2% NaCl. Addition of 0.2% NaCl doubled the viscosity. Clinically, the suppository containing 0.06% NaCl was given to 3 patients with endometrial carcinoma twice a week for 3 weeks to examine serum CDDP levels and endometrial absorption. Patients with endometrial carcinoma showed different peak plasma platinum (Pt) levels which were as low as 0.12, 0.06 and 0.22 micrograms Pt/ml with similar patterns of change in the level. Radiographic analysis revealed many Pt particles in sections of necrosed endometria after 21d of the treatment. No side effects of CDDP were found in biochemical testing or subjective symptoms.

Aged↗

PubMed1991

[Surgical indication based on prognostic factors in pT1 tumors of the lung].

Among 385 patients of surgical resected lung cancer, 88 (22.8%) were pT1 tumors. The overall five year survival rate of these patients was 75.8%. There was statistically significant difference in survival rate depending on the pTNM staging, degree of differentiation and cytological atypia (CAT). Among these prognostic factors, CAT was most important. CAT may be an indicator to predict the postoperative prognosis of the patients and may contribute to the determination of the surgical indication.

Adenocarcinoma↗

PubMed1991

[Immunohistochemical study of lung cancer using monoclonal antibody against human pulmonary surfactant apoprotein].

To evaluate the clinical significance of monoclonal antibody against human pulmonary surfactant apoprotein (S-AP), surgically resected lung cancer from 122 patients was studied. Paraffin embedded tissues were used for the immunohistochemical study by the avidin-biotin-peroxidase complex method. The results were as follows. 1. Adenocarcinoma showed highest immunoreactivity for S-AP compared to the other histologic types. Among subtypes of adenocarcinoma, type II alveolar epithelial type, clara cell type and mixed type of these two types were strongly positive (100%, 77.8% and 66.7% respectively). These results indicate that this antibody may be a good marker for the subtyping of adenocarcinoma. 2. There were some positive cases in other histologic types especially in peripheral type of squamous cell carcinoma. These findings suggest that this antibody was useful for the histological differentiation of lung cancer. 3. As to the immunohistochemical reactivity there was a good correlation between tissue and cytological specimens, which indicate cytological studies may be adequate for this kind of histopathological studies. 4. In our study, there were no patients with S-AP positive carcinomas other than patients with lung cancer. These results indicate that this antibody could be used for the differential diagnosis between primary and secondary lung cancer.

Adenocarcinoma↗

PubMed1991

[The role of surgery in cases of diagnostic difficulty].

Pulmonary resections for the treatment of pulmonary tuberculosis are decreasing, and nowadays most of them are for the open lung biopsy to make histological diagnosis, because differentiation between tuberculosis, AM and lung cancer is critical. In 1980-1990 forty-three patients, in whom the diagnosis was not established by conventional diagnostic methods, had pulmonary resections for open lung biopsy because of abnormal chest X-ray shadows. Of these, 31 (72%) were non-tuberculous (lung cancer 8, hamartoma 7, lung abscess 5, fungus infection 3, sclerosing hemangioma 2, bronchogenic cyst 2, and others 4, and 12 (28%) were tuberculous or AM. The type of chest film abnormality was solitary pulmonary nodule (coin lesion) in 9 out of 12 patients with tuberculosis or AM, in all eight patients with lung cancer and in 14 out of 23 patients with other diseases. In patients with coin lesions, the incidence of lung cancer was as high as 50% when the diameter was more than 21mm, while it was only 11% when it was 20mm or less. 24 patients with tuberculosis or AM complicated by lung cancer or other diseases were resected. There were 8 smear or culture positive patients with active pulmonary tuberculosis (or AM) (Group 1), of whom 7 had lung cancer and 1 pneumothorax. Of 8 patients who were wrongly diagnosed as active pulmonary tuberculosis (Group 2), there were 5 lung cancers and 3 other diseases. In the remaining 8 patients (Group 3) both old tuberculosis and lung cancer coexisted and in 3 they were found in the same lobe.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed1991

[The surgical treatment of chronic empyema--from the stand point of preservation and improvement of pulmonary function].

During the period of 1978 to 1990, 247 patients with chronic empyema were operated. The cure rate was 88.3%. The operation was not successful in 29 patients (11.7%), of whom 19 were operative death and 10 were those whose condition never improved to the level of discharge. The pulmonary function improved post-operatively in those patients who underwent decortication and air-plombage, but not in those who underwent pleuropneumonectomy and thoracoplasty (modification of Grow's method). Most remarkable changes of pulmonary function were seen in patients who underwent thoracoplasty. Air-plombage was found effective in controlling empyema and for the preservation and improvement of post-operative pulmonary functions.

Chronic Disease↗