Biomedical subjects

H Watari

Publications and source records attributed to H Watari.

At least 19 recordsLinked to original sources

PubMed1997

MLN64 contains a domain with homology to the steroidogenic acute regulatory protein (StAR) that stimulates steroidogenesis.

MLN64 is a protein that is highly expressed in certain breast carcinomas. The C terminus of MLN64 shares significant homology with the steroidogenic acute regulatory protein (StAR), which plays a key role in steroid hormone biosynthesis by enhancing the intramitochondrial translocation of cholesterol to the cholesterol side-chain cleavage enzyme. We tested the ability of MLN64 to stimulate steroidogenesis by using COS-1 cells cotransfected with plasmids expressing the human cholesterol side-chain cleavage enzyme system and wild-type and mutant MLN64 proteins. Wild-type MLN64 increased pregnenolone secretion in this system 2-fold. The steroidogenic activity of MLN64 was found to reside in the C terminus of the protein, because constructs from which the C-terminal StAR homology domain was deleted had no steroidogenic activity. In contrast, removal of N-terminal sequences increased MLN64's steroidogenesis-enhancing activity. MLN64 mRNA was found in many human tissues, including the placenta and brain, which synthesize steroid hormones but do not express StAR. Western blot analysis revealed the presence of lower molecular weight immunoreactive MLN64 species that contain the C-terminal sequences in human tissues. Homologs of both MLN64 and StAR were identified in Caenorhabditis elegans, indicating that the two proteins are ancient. Mutations that inactivate StAR were correlated with amino acid residues that are identical or similar among StAR and MLN64, indicating that conserved motifs are important for steroidogenic activity. We conclude that MLN64 stimulates steroidogenesis by virtue of its homology to StAR.

Amino Acid Sequence↗

PubMed1997

Effect of circulatory occlusion on human muscle metabolism during exercise and recovery.

To assess muscle metabolism and inorganic phosphate (P(i)) peak splitting during exercise, 31-phosphorus nuclear magnetic resonance spectroscopy was performed during ramp incremental and submaximal step exercise with and without circulatory occlusion. Seven healthy men performed calf flexion in a superconducting magnet. There was no P(i) splitting during ramp incremental exercise with the circulation present and phosphocreatine (PCr) decreased linearly by 0.07 (SEM 0.01) mmol.l-1.s-1, while exercise with the circulation occluded caused the P(i) peak to split into a high and a low pH peak. The rate of PCr decrease during exercise with the circulation occluded was 0.15 (SEM 0.03) mmol.l-1.s-1 which with the efficiency of the adenosine 5'-triphosphate (ATP) hydrolysis reaction corresponded well to the mechanical energy. Both with and without occlusion of the circulation PCr decreased with some time lag which may reflect the consumption of residual oxygen. In submaximal step exercise PCr decreased exponentially at the onset of exercise with the circulation open whereas it decreased linearly by 0.15 mmol.l-1.s-1 when the circulation was occluded. After exercise, occlusion of the circulation was maintained for 1 min more and there was no PCr resynthesis. It is suggested that ATP synthesis was limited by the availability of oxygen.

Adenosine Triphosphate↗

PubMed1996

A case of intrauterine medical treatment for cystic hygroma.

We report the first case of an intrauterine treatment for cystic hygroma. Guided by ultrasonography, we first removed intracystic fluid from two cysts and then injected OK-432 into each fetal cyst at 21 and 28 weeks of gestation. No re-enlargement of the cysts was subsequently observed. At 38 weeks of gestation, a male infant was delivered transvaginally. Only a slight skin fold was observed in the nuchal area of the neonate, indicating the effectiveness of OK-432 for the intrauterine treatment of cystic hygroma.

Adult↗

PubMed1996

Comparative 1H-NMR studies on the physical state of water in soft contact lens and mouse lens.

The physical state of water in mouse lenses (2-, 4- or 8-wk-old) and soft contact lenses (SCLs, water content from 18.4 to 79.2%) were studied by measuring spin-lattice relaxation times (T1) and apparent intermolecular cross-relaxation times (TIS) from irradiated protein or polymer protons to water protons, using 360 MHz 1H-NMR spectrometer at 25 degrees C. (1) 1/T1 values of SCLs increased gradually with increasing dry weight (W(%)). 1/TIS values of SCLs were approximately zero at W of 20.8 and 26.8%, increased gradually from 26.8% and then steeply above approximately 50%. (2) A plot of 1/T1 vs. W(%) of mouse lenses was almost equal to that of SCLs. However, a plot of 1/TIS vs. W(%) was an approximately straight line with the intercept at W of 23% and with the slope which is almost equal to that of SCLs above W of approximately 50%. The plot of 1/TIS vs. W(%) of mouse lenses might indicate the significant change in the physical state of water and/or protein-water interactions above W of 23%.

Age Factors↗

PubMed1996

Effects of active and passive recoveries on splitting of the inorganic phosphate peak determined by 31P-nuclear magnetic resonance spectroscopy.

Six male long-distance runners performed knee flexion exercises in a 2.1 T superconducting magnet. 31P MRS was used to investigate the splitting pattern of the inorganic phosphate (Pi) peak during active and passive recovery. During exercise splitting of the Pi peak into two was observed (high and low pH) and after exercise the manner in which the Pi peak disappeared was different in passive and active recoveries. During passive recovery, in which exercise was not performed at all, the high-pH Pi peak disappeared more rapidly than the low-pH Pi peak. The low-pH Pi peak remained at a similar acidified chemical shift as during exercise, and then gradually disappeared during passive recovery. Conversely, during active recovery in which unloaded exercise was followed, the high-pH Pi peak was reduced, but remained, whereas the low-pH Pi peak returned very quickly to the pre-exercise level and then disappeared. Teh recovery rate of the low pH during active recovery (0.095 +/- 0.019 pH units/min) was significantly faster than that during passive recovery (0.014 +/- 0.019 pH units/min) (p < 0.01). The slow disappearance of the low pH Pi peak during passive recovery can be explained by the halting of glycogenolysis and an insufficient oxygen supply to resting glycolytic fibers, whereas the quick disappearance observed with active recovery would have been due to elevated sufficient oxygen supply and efficient removal of lactate as a result of the maintained blood flow. Oxy-myoglobin and hemoglobin was also measured with near infrared spectroscopy.

Adult↗

PubMed1996

Dome formation induced by v-H-ras oncogene in a human choriocarcinoma cell line.

To investigate the role of ras genes in trophoblastic cell lineage, we transfected the viral H- or K-ras oncogene into a human choriocarcinoma cell line, CCI, and analysed the biological properties of CCI cells expressing an activated ras oncogene. All v-H-ras-expressing clones distinctively formed the hemispherical domes, which represents an in vitro morphological expression of vectorial transport function and are characteristic of the polarized epithelial cells, but none of v-K-ras-expressing clones and control clones did. Microscopic observation demonstrated that those domes were cavities filled with fluid which accumulated between the cell layer and the surface of culture dish. Scanning electron microscopy revealed that the domes were aggregates of round cells with long numerous microvilli and were morphologically similar to a blastocyst. Furthermore, Na(+)-K(+)-ATPase activity, which is associated with the vectorial fluid transport in transporting epithelial cells, was significantly higher in the v-H-ras-expressing clones than that in the v-K-ras-expressing clones and the parental cells. Those domes flattened within 24 h after treatment with a specific inhibitor of Na(+)-K(+)-ATPase, ouabain, and the number of domes decreased in dose-dependent manner, indicating that Na(+)-K(+)-ATPase activity was required for maintainance of domes. These results suggest that up-regulated activity of H-ras but not of K-ras facilitates the vectorial fluid transport through a chorionic cell layer and leads to the dome formation. The function of II-ras in trophoblasts, may therefore, be essential for embryogenesis, especially for supplying the nutrients.

Biological Transport↗

PubMed1995

Spin-lattice relaxation times of water in polarized and depolarized rabbit vagus nerves.

Spin-lattice relaxation times (T1) of intracellular water of the nonmyelinated fibers of rabbit cervical vagus nerve were measured using a paramagnetic shift reagent, s-FDF. Spin-lattice relaxation decay curves were composed of the fast (T1,F) and slow (T1,S) relaxation components. The mean values of T1,F and T1,S in the polarized nerve fibers at 25 degrees C were 0.12 +/- 0.04 and 0.61 +/- 0.13 sec., respectively, and their fractions were 0.71 +/- 0.07 and 0.29 +/- 0.07, respectively (n = 21). On the other hand, those values in the depolarized nerve fibers were 0.16 +/- 0.01 sec., 0.77 +/- 0.17 sec., 0.77 +/- 0.10 and 0.23 +/- 0.10, respectively (n = 15). T1,F and T1,S for the depolarized nerve fibers were significantly elongated (P < 0.01).

Animals↗

PubMed1995

High-resolution MRI of the human cochlea.

The majority of magnetic resonance imaging (MRI) studies in neurotology concern the evaluation of retrocochlear pathologies or temporal bone lesions. Recently, quite a number of investigators have attempted to use imaging diagnosis to obtain a diagnosis and manifest the pathological findings of Meniere's disease. However, there is no evidence that endolymphatic hydrops in patients with Meniere's disease can be identified by imaging techniques. In this study we could depict Reissner's membrane clearer than before with the use of image processing. At the present time, we cannot apply the 2.11T MRI machine to patients under FDA regulation. We believe that MRI diagnoses of endolymphatic hydrops and small lesions of the internal structures of the inner ear will be possible in the near future.

Adult↗

PubMed1995

[Roles of ras genes on biological properties of human choriocarcinoma cells].

Human choriocarcinoma cell lines, preserving many biological properties of normal trophoblasts, are good models for investigating of trophoblastic cell biology. Most of these cells express various oncogenes, which might have essential roles for biological characteristics of choriocarcinoma cells. Of these oncogenes, ras gene family has been known to play the key roles in cell growth, transformation and differentiation. In order to investigate the roles of ras genes on various unique characters of trophoblasts, the author transfected the viral H- or K-ras oncogene into a human choriocarcinoma cell line, CC1, and established choriocarcinoma cell lines acquired up-regulated activity of ras genes. v-ras-expressing clones exhibited almost the same growth capacities as control clones, but only v-H-ras clones formed the many fluid-filled hemispherical "domes" in a cell layer. Microscopic observation of these domes clarified that the accumulation of fluid between cell layer and the surface of culture dish has resulted in dome formation, which is characteristic of the polarized epithelial cells and represents an in vitro morphologic expression of vectorial transport function. Since these clones exhibited higher Na(+)-K(+)-ATPase activity than other clones and dome formation was inhibited with the treatment of ouabain, a specific inhibitor of Na(+)-K(+)-ATPase, dome formation may be due to the augmentation of the vectorial fluid transport driven by Na(+)-K(+)-ATPase. In addition, the expression of human chorionic gonadotropin (hCG) beta was examined to investigate the effects of ras genes on peptide hormone production which is one of the differentiated functions of trophoblasts. v-K-ras-expressing clones secreted significantly more hCG than controls, while v-H-ras did not seem to affect hCG-producing activity. These results obtained in this study indicate that H-ras gene may facilitate the vectorial transcellular fluid transport from maternal site to fetus, while K-ras gene is associated with some endocrine functions such as hCG production in trophoblasts.

Biological Transport↗

PubMed1994

Induction of apoptosis by a dominant negative H-RAS mutant (116Y) in K562 cells.

Recent extensive work on apoptosis has begun to reveal its molecular mechanisms. Several genes that regulate apoptosis have been identified. Among them, the BCL2 gene is considered to be an important gene that inhibits apoptosis. However, there must be other genes, yet to be identified, which suppress apoptosis. It has been suggested that the activation of RAS function by BCR-ABL fusion protein in chronic myelogenous leukemia may be an important mechanism in the BCR-ABL mediated transformation. Therefore, in this study we have investigated whether the suppression of endogenous H-RAS function inhibits the BCR-ABL mediated transforming activity in a K562 human chronic myelogenous leukemia cell line. The induced expression of a dominant negative v-H-RAS mutant (116Y) in K562 cells has resulted in cell death. The morphological characteristics and the detection of fragmented DNA by gel electrophoresis in the dead cells have revealed that this cell death is apoptosis. These results directly indicate that the RAS gene as well as the BCL2 gene has an ability to suppress apoptosis.

Apoptosis↗

PubMed1994

Exercise-induced splitting of the inorganic phosphate peak: investigation by time-resolved 31P-nuclear magnetic resonance spectroscopy.

To investigate the splitting of the inorganic phosphate (Pi) peak during exercise and recovery, a time-resolved 31phosphorus nuclear magnetic resonance spectroscopy (31P-MRS) technique was used. Seven healthy young sedentary male subjects performed knee flexion exercise in the prone position inside a 2.1-T magnet, with the surface coil for 31P-MRS being placed on the biceps femoris muscle. After a 1-min warm-up without loading, the exercise intensity was increased by 0.41 W at 15-s intervals until exhaustion, followed by a 5-min recovery period. The 31P-MRS were recorded every 5 s during the rest-exercise-recovery sequence. Computer-aided contour analysis and pixel imaging of the Pi and phosphocreatine peaks were performed. Five of the seven subjects showed two distinct Pi peaks during exercise, suggesting two different pH distributions in exercising muscle (high pH and low pH region). In these five subjects, the high-pH increased rapidly just after the onset of exercise, while the low-pH peak increased gradually approximately 60 s after the onset of exercise. During recovery, the disappearance of the high-pH peak was more rapid than that of the low-pH peak. These findings suggest that our method 31P-MRS provides a simple approach for studying the kinetics of the Pi peak and intramuscular pH during exercise and recovery.

Adult↗

PubMed1994

Suppression of various human tumor cell lines by a dominant negative H-ras mutant.

A dominant negative H-ras mutant, N116Y, was transfected into a variety of human tumor cell lines. N116Y extremely inhibited the proliferation of A431 (vulva), PC3 (prostate), T24 (bladder), MCF7 (breast), NKPS and TMK1 (stomach) cancer cell lines. A431 and PC3 cells were particularly susceptible to N116Y. In order to examine the effects of N116Y on the neoplastic phenotypes, we transfected a less efficient N116Y expression vector into A431 cells. Almost all clones survived after G418 selection. However, they did not retain the N116Y gene and only one clone faintly expressed N116Y. This N116Y-expressing clone had no tumorigenicity in vivo, and revealed deformed morphology and DNA fragmentation, suggesting that N116Y might have induced apoptotic cell death. Thus, N116Y may be applicable for gene therapy of a wide spectrum of human tumors.

Apoptosis↗

PubMed1993

Allergen-induced histamine secretion associated with lactate production in mast cells detected by 1H NMR.

Allergen-induced histamine secretion in mast cells, obtained from rats infected with Nippostrongylus brasiliensis, was detected by a 1H NMR semi-selective excitation technique. Lactate production was also detected in association with histamine secretion as observed in mast cells stimulated with other nonimmunological agents, such as compound 48/80, polymyxin B, and melittin. The assignment of the lactate resonance was confirmed using lactate oxidase. Thus, 1H NMR spectroscopy is a useful method to study the activation of mast cells in allergic reaction.

Animals↗

PubMed1993

Resistance of NIH3T3 cells to v-fes transformation induced by a dominant negative H-ras mutant.

NIH3T3 cells carrying a dominant negative H-ras mutant 116Y acquired resistance to transformation by some PTK oncogenes, i.e., v-fes, v-abl, and v-fms, but were sensitive to viral ras and serine threonine kinase oncogenes, v-raf and v-mos. One clone, designated 1-20, infected with v-fes (1-20 fes) exhibited flat morphology and anchorage-dependent cell growth, as did noninfected 1-20 cells. The 1-20 fes cells expressed v-fes oncogene and produced transforming viruses, although these levels were much lower than those in NIH3T3 cells infected with v-fes (NIH3T3 fes). v-fes mRNAs in NIH3T3 fes cells rapidly increased after infection, while accumulation of the v-fes transcripts in 1-20 fes cells was significantly prolonged. Total tyrosine phosphorylation in both NIH3T3 fes and 1-20 fes cells was correlated with the amounts of pp110v-fes. A few proteins were phosphorylated only in NIH3T3 fes but not in 1-20 fes cells. These results suggest that the cellular ras is involved in a signaling pathway from pp110v-fes and this signal stimulates v-fes expression. Inhibition of the ras function may down-regulate this pathway and result in resistance to transformation by v-fes.

3T3 Cells↗

PubMed1993

31P-nuclear magnetic resonance spectroscopy study of the time course of energy metabolism during exercise and recovery.

This study evaluated the time courses of intracellular pH and the metabolism of phosphocreatine (PCr) and inorganic phosphate (Pi) at the onset of four exercise intensities and recoveries. Non-invasive evaluation of continuous changes in phosphorus metabolites has become possible using 31P-nuclear magnetic resonance spectroscopy (31P-MRS). After measurements at rest, six healthy male subjects performed 4 min of femoral flexion exercise at intensities of 0 ("loadless"), 10, 20 and 30 kg.m.min-1 in a 2.1 T superconducting magnet with a 67-cm bore. Measurements were continuously made during 5 min of recovery. During a series of rest-exercise-recovery procedures, 31P-MRS were accumulated using 32 scans-spectrum-1 requiring 12.8 s each. At the onset of exercise, PCr decreased exponentially with a time constant of 27-32 s regardless of the exercise intensity. The time constant PCr resynthesis during recovery was about 27-40 s. The PCr kinetics were independent of exercise intensity. There were similar Pi kinetics at the onset of all types of exercise, while those of Pi recovery became significantly longer at the higher exercise intensities (P < 0.05). Furthermore, the intracellular pH indicated temporary alkalosis just at the onset of exercise, probably due to absorption of hydrogen ions by PCr hydrolysis, and then decrease at a point about 40%-50% of the pre-exercise PCr. The pH recovery time was longer than that for the Pi or PCr kinetics. By using a more efficient resolution system it was possible to obtain the phosphorus kinetics during exercise and to follow PCr resynthesis within the first few minutes of recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1993

Metabolic consequences of repeated exercise in long distance runners.

To assess the rates of change in muscle metabolites such as phosphocreatine (PCr) and inorganic phosphate (Pi) during repeated exercise sessions with rest periods, 31-phosphorus nuclear magnetic resonance spectroscopy was used for continuous and noninvasive measurements. Five long-distance runners and six healthy male subjects as controls performed a 2-min femoral flexion exercise at 20 kg.m.min-1 in a 2.1 T superconducting magnet with a 67-cm bore; they repeated this exercise four times with a 2-min rest period. At the beginning of exercise, PCr decreased exponentially; at the end, it increased. During exercise and in the early phase of the recovery in every exercise session, the PCr values were significantly higher in the long-distance runners than in the control subjects (P < 0.05). The Pi increases and decreases involved with exercise also revealed exponential changes. The Pi values did not significantly differ during exercise; however, Pi recovery was faster in the long-distance runners than in the control subjects (P < 0.05). The Pi:PCr ratio during exercise increased linearly with exercise; and Pi:PCr during recovery was smaller in the long-distance runners than in the control subjects (P < 0.05). In conclusion, the long-distance runners revealed faster PCr and Pi kinetics after exercise and a smaller Pi:PCr during exercise than did the control subjects. It is suggested that these results were attributable to a greater oxidative capacity of muscles in the long-distance runners.

Adult↗

PubMed1993

Changes in intracellular pH during repeated exercise.

The rates of change in intracellular pH during repeated exercise sessions with rest periods was determined by 31 phosphorus-nuclear magnetic resonance spectroscopy (31P-MRS). Five long-distance runners and six healthy male subjects as controls performed a 2-min femoral flexion at 20 kg.m.min-1 in a 2.1 T superconducting magnet with a 67-cm bore and repeated this exercise four times with 2-min rest periods intervening. In all cases during exercise the inorganic phosphate (Pi) peak split into two, the earlier increased rapidly (high-pH Pi) and the later (low-pH Pi) increased more slowly. The Pi peaks were separated by a fitting procedure using the least square mean method. The high-pH Pi area during exercise decreased as the number of repeated exercise periods increased, while the low-pH Pi area gradually increased. Although the total Pi area decreased exponentially during the recovery period, the high-pH Pi area decreased first and then the low-pH Pi area reduced gradually. The pH values were estimated from the chemical shift between the phosphocreatine peak and each split peak in the Pi. The high-pH in pooled data ranged from 6.6 to 7.0 during exercise and recovery, while the low pH decreased to 6.2 during exercise. As the number of exercise periods increased, each pH value gradually became less acidic, although there was a tendency to more acidity in the control subjects than in the long-distance runners.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Proton nuclear magnetic resonance studies on water structure in peritumoral edematous brain tissue.

Spin-lattice relaxation times (T1) of water protons and cross-relaxation times (TIS) between irradiated protein and water protons were measured to study the water structure in peritumoral edematous brain tissue of rats. Despite small changes in T1, water, and electrolyte contents, TIS values of water protons were significantly reduced in peritumoral edematous brain tissue when compared to those of the controls. Results indicate that the water structure in brain tissues may become altered at an early stage of edemic formation without causing any significant changes in cellular hydration. TIS might serve as a sensitive parameter for studying the water structure in a variety of tissues, such as in edematous brain tissue.

Animals↗