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Biomedical subjects

K Shimamoto

Publications and source records attributed to K Shimamoto.

At least 253 records · Page 14Linked to original sources
PubMed1993

A wheat histone H3 promoter confers cell division-dependent and -independent expression of the gus A gene in transgenic rice plants.

To investigate developmental regulation of wheat histone H3 gene expression, the H3 promoter, which has its upstream sequence to -1711 (relative to the cap site as +1), was fused to the coding region of the gus A gene (-1711H3/GUS) and introduced into a monocot plant, rice. Detailed histochemical analysis revealed two distinct types of GUS expression in transgenic rice plants; one is cell division-dependent found in the apical meristem of shoots and roots and in young leaves, and another is cell division-independent detected in flower tissues including the anther wall and the pistil. In this study, replication-dependent expression occurring in non-dividing cells which undergo endoreduplication could not be discriminated from strict replication-independent expression. The observed expression pattern in different parts of roots suggested that the level of the H3/GUS gene expression is well correlated with activity of cell division in roots. To identify 5' sequences of the H3 promoter necessary for an accurate regulation of the GUS expression, two constructs containing truncated promoters, -908H3/GUS and -185H3/GUS, were analyzed in transiently expressed protoplasts, stably transformed calli and transgenic plants. The results indicated that the region from -909 to -1711 contains the positive cis-acting element(s) and that the proximal promoter region (up to -185) containing the conserved hexamer, octamer and nonamer motifs is sufficient to direct both cell division-dependent and -independent expression. The use of the meristem of roots regenerated from transformed calli for the analysis of cell division-dependent expression of plant genes is discussed.

Base Sequence↗
PubMed1993

Inhibition of plasma kallikrein with aprotinin in porcine endotoxin shock.

Activation of the contact phase of coagulation has been implicated in the pathogenesis of septic shock. We wanted to determine if inhibition of plasma kallikrein can prevent arterial hypotension and liberation of kinins from kininogen, induced by an infusion of bacterial lipopolysaccharide (LPS) in anesthetized, ventilated 20-kg pigs. The LPS was given IV in a dose of 5 micrograms/kg/h for 8 hours. The plasma kallikrein inhibitor aprotinin, 537 mumol, was given IV during 8 hours, resulting in plasma levels above 10 mumol/L. Ten animals (SA) received LPS and aprotinin and ten randomized controls (SC) received LPS and saline. Kinin-containing kininogen was determined on the basis of the amount of kinin releasable in plasma samples by incubation with trypsin. Kininogen decreased to 58% +/- 4% of the baseline value without any difference between groups. This may indicate participation of other processes than degradation by plasma kallikrein in the decrease of kininogen. Arterial blood pressure was higher at 7 hours in the SA animals than in the SC group (101% +/- 11% vs. 68% +/- 8%; mean +/- SEM; p = 0.026). Fibrin monomer and C3adesArg plasma levels were attenuated by aprotinin treatment. These findings underscore the important role of the contact system in LPS shock.

Animals↗
PubMed1993

Light-regulated and cell-specific expression of tomato rbcS-gusA and rice rbcS-gusA fusion genes in transgenic rice.

A previously isolated rice (Oryza sativa) rbcS gene was further characterized. This analysis revealed specific sequences in the 5' regulatory region of the rice rbcS gene that are conserved in rbcS genes of other monocotyledonous species. In transgenic rice plants, we examined the expression of the beta-glucuronidase (gusA) reporter gene directed by the 2.8-kb promoter region of the rice rbcS gene. To examine differences in the regulation of monocotyledonous and dicotyledonous rbcS promoters, the activity of a tomato rbcS promoter was also investigated in transgenic rice plants. Our results indicated that both rice and tomato rbcS promoters confer mesophyll-specific expression of the gusA reporter gene in transgenic rice plants and that this expression is induced by light. However, the expression level of the rice rbcS-gusA gene was higher than that of the tomato rbcS-gusA gene, suggesting the presence of quantitative differences in the activity of these particular monocotyledonous and dicotyledonous rbcS promoters in transgenic rice. Histochemical analysis of rbcS-gusA gene expression showed that the observed light induction was only found in mesophyll cells. Furthermore, it was demonstrated that the light regulation of rice rbcS-gusA gene expression was primarily at the level of mRNA accumulation. We show that the rice rbcS gene promoter should be useful for expression of agronomically important genes for genetic engineering of monocotyledonous species.

Amino Acid Sequence↗
PubMed1993

Do angiotensin converting enzyme inhibitors limit myocardial infarct size?

1. Effects of captopril, ramiprilat and Hoe 140, a specific bradykinin receptor antagonist, on infarct size were assessed in a rabbit model of myocardial infarction. 2. Rabbits were untreated or pretreated with 0.5 mg/kg of captopril, 0.05 mg/kg of ramiprilat or 20 nmol/kg of Hoe 140 before 30 min coronary artery occlusion and 72 h reperfusion. 3. Captopril and ramiprilat treatment reduced systemic blood pressure by about 10 mmHg without alteration of heart rate, and the dose of Hoe 140 almost completely blocked hypotensive response to intravenous injection of bradykinin (100 ng/kg). 4. Infarct size expressed as percentage of area at risk was 44.5 +/- 3.3% in the control group, 41.9 +/- 1.6% in the captopril group, 51.8 +/- 2.7% in the ramiprilat group and 46.7 +/- 2.2% in the Hoe 140 group. All percentages were not significantly different. 5. These data suggest that angiotensin converting enzymes (ACE), with or without sulfhydryl groups do not limit myocardial infarct size and that endogenous bradykinin in ischaemic myocardium does not play a major protective role against ischaemic myocardial necrosis.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1993

Effect of nicorandil on post-ischaemic contractile dysfunction in the heart: roles of its ATP-sensitive K+ channel opening property and nitrate property.

1. This study aimed to characterize the effect of nicorandil (NC) on myocardial stunning and the role of ATP-sensitive K+ (KATP) channel opening property in its cardioprotective action. 2. In open-chest anaesthetized rabbits, myocardial stunning was induced by 10 min of coronary occlusion followed by 30 min of reperfusion. As an index of regional contractile function, systolic thickening fraction (TF) was measured by an epicardial Doppler sensor. The doses of NC (10 micrograms/kg per min) and nitroglycerin (TNG) (1 micrograms/kg per min) were selected not to lower the systemic blood pressure significantly. 3. In the untreated controls, TF at 30 min after reperfusion was 46.4 +/- 2.9% of the baseline value, indicating myocardial stunning. Both NC and TNG significantly improved post-ischaemic recovery of TF when administered during the pre-ischaemic and post-ischaemic periods (TF = 68.2 +/- 6.4%, 64.7 +/- 2.3%, respectively). However, when their infusion was restricted to a pre-ischaemic 10 min period, TF recovery was improved by NC, but not by TNG (63.4 +/- 7.9%, 40.9 +/- 6.2%, respectively). 4. Pretreatment with glibenclamide (GL; 0.3 mg/kg) did not influence the recovery of TF after the 10 min ischaemia (TF = 52.4 +/- 3.9% at 30 min after reperfusion). However, after the GL injection, a cardioprotective effect from nicorandil pretreatment was not detected (TF = 51.3 +/- 1.7%). 5. These results suggest that nicorandil protects the myocardium against stunning by opening the KATP channel when it is given before ischaemia, and that the nitrate property of nicorandil may also play a role during the reperfusion period in attenuation of post-ischaemic contractile dysfunction.

Adenosine Triphosphate↗
PubMed1993

A novel metabotropic glutamate receptor agonist: marked depression of monosynaptic excitation in the newborn rat isolated spinal cord.

1. Neuropharmacological actions of a novel metabotropic glutamate receptor agonist, (2S,1'R,2'R,3'R)-2(2,3-dicarboxycyclopropyl)glycine (DCG-IV), were examined in the isolated spinal cord of the newborn rat, and compared with those of the established agonists of (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine (L-CCG-I) or (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1S,3R)-ACPD). 2. At concentrations higher than 10 microM, DCG-IV caused a depolarization which was completely blocked by selective N-methyl-D-aspartate (NMDA) antagonists. The depolarization was pharmacologically quite different from that caused by L-CCG-I and (1S,3R)-ACPD. 3. DCG-IV reduced the monosynaptic excitation of motoneurones rather than polysynaptic discharges in the nanomolar range without causing postsynaptic depolarization of motoneurones. DCG-IV was more effective than L-CCG-I, (1S,3R)-ACPD or L-2-amino-4-phosphonobutanoic acid (L-AP4) in reducing the monosynaptic excitation of motoneurones. 4. DCG-IV (30 nM-1 microM) did not depress the depolarization induced by known excitatory amino acids in the newborn rat motoneurones, but depressed the baseline fluctuation of the potential derived from ventral roots. Therefore, DCG-IV seems to reduce preferentially transmitter release from primary afferent nerve terminals. 5. Depression of monosynaptic excitation caused by DCG-IV was not affected by any known pharmacological agents, including 2-amino-3-phosphonopropanoic acid (AP3), diazepam, 2-hydroxysaclofen, picrotoxin and strychnine. 6. DCG-IV has the potential of providing further useful information on the physiological function of metabotropic glutamate receptors.

Amino Acids↗
PubMed1993

Massive myocardial calcification of right and left ventricles following acute myocarditis complicated with rhabdomyolysis-induced acute renal failure.

A 26-year-old man was admitted with a high fever, oliguria, skeletal muscle weakness, and cardiogenic shock which led to a diagnosis of acute myocarditis and acute rhabdomyolysis. During treatment with hemodialysis and calcium supplementation, because of severe hypocalcemia, a massive calcification of both right and left ventricular myocardium gradually became apparent with repeated computed tomographic (CT) examinations. Technetium-99m scannings more clearly delineated the markedly accumulated calcium in the myocardium, while significant activity was not detected in other soft tissues. Histopathological examinations by myocardial biopsy revealed a large amount of fibrosis and calcium deposits, and serial CT scans showed a gradual regression of the calcium deposition, suggesting that this rare form of massive dystrophic calcification may parallel changes in the severity of myocarditis, and may be associated with abnormalities in calcium metabolism secondary to rhabdomyolysis-induced acute renal failure.

Acute Disease↗
PubMed1993

Thyroid nodules: evaluation with color Doppler ultrasonography.

Forty-seven patients with thyroid nodules (13 papillary carcinomas, 14 adenomas, and 20 adenomatous goiters) underwent color Doppler sonography with a 7.5 MHz transducer. Perinodular or intranodular color flow signals were depicted in 10 of 13 papillary carcinomas, in 10 of 14 follicular adenomas, and in 14 of 20 adenomatous goiters. No correlation existed between the presence of color signals and pathology, whereas the detection rate of color signals had a dependence on the size of the lesions. No specific flow pattern for malignancy could be found. Color Doppler sonography would not improve the ability to differentiate benign from malignant nodules significantly.

Adenoma↗
PubMed1993

Digital radiology and PACS.

Future hospital information systems should permit the systematic storage of all information generalized within the hospital, including medical diagnostic images. For such a system to be realized, implementation of a picture archiving and communication system (PACS) is needed. The development of computed radiography with an imaging plate (CR) has made it possible for digitalization of all kinds of projection radiographs, and thus for PACS to be realized. In this paper the clinical usefulness of CR and many factors required to realize PACS are described.

Data Display↗
PubMed1993

The presequence of a precursor to the delta-subunit of sweet potato mitochondrial F1ATPase is not sufficient for the transport of beta-glucuronidase (GUS) into mitochondria of tobacco, rice and yeast cells.

A precursor to the delta-subunit of sweet potato mitochondrial F1ATPase (pre-F1 delta) has an amino-terminal (N-terminal) presequence of 45 amino acid residues and its N-terminal 18 residues may form an amphiphilic alpha-helix, which is typical of mitochondrial targeting signals [Kimura et al. (1990) J. Biol. Chem. 265: 6079]. Fusion genes consisting of sequences that encoded the 25 (DG25), 46 (DG46) and 73 (DG73) N-terminal amino acids from pre-F1 delta fused to the N-terminus of the coding sequence of bacterial beta-glucuronidase (GUS) were placed downstream of the 35S promoter of cauliflower mosaic virus and used to transform suspension-cultured tobacco cells, rice calli and tobacco plants. Fusion genes were also placed downstream of the yeast GAL10 promoter and introduced into Saccharomyces cerevisiae cells. In these transformed cells, only the DG73 GUS-fusion protein was transported into mitochondria and subjected to proteolytic cleavage of the presequence. Neither transport to mitochondria nor processing of the presequence of the DG46 GUS-fusion protein, which contained the entire presequence and the processing site, occurred in either plant or yeast cells. These results indicate that the presequence of pre-F1 delta is not sufficient for the transport of the GUS protein into mitochondria in tobacco, rice and yeast cells. The requirement for the longer polypeptide from pre-F1 delta in the transport of the GUS protein into mitochondria could be due either to the lack of sufficient information for mitochondrial targeting within the presequence or to the nature of the passenger protein, GUS, used in this study.

Amino Acid Sequence↗
PubMed1993

Late rupture of left ventricular true aneurysm after acute myocardial infarction.

Left ventricular (LV) free wall rupture complicated with acute myocardial infarction (AMI) usually occurs in the early phase of AMI. True aneurysm of the LV is sometimes a complication of AMI but rarely ruptures. In our patient, a 72-year-old woman, the LV free wall ruptured on Day 49 after the onset of AMI and the ruptured site was the thinnest wall of large true aneurysm of the LV. The large aneurysmal formation probably was due to corticosteroids used for pericarditis. More attention should be paid to late cardiac rupture and the use of corticosteroids.

Adrenal Cortex Hormones↗
PubMed1992

Genetically engineered rice resistant to rice stripe virus, an insect-transmitted virus.

The coat protein (CP) gene of rice stripe virus was introduced into two japonica varieties of rice by electroporation of protoplasts. The resultant transgenic plants expressed the CP at high levels (up to 0.5% of total soluble protein) and exhibited a significant level of resistance to virus infection. Plants derived from selfed progeny of the primary transformants also expressed the CP and showed viral resistance, indicating stable transmission of the CP gene and the trait of resistance to the next generation. Moreover, the virally encoded strip disease-specific protein was not detected in transgenic plants expressing CP 8 weeks after inoculation, indicating protection before viral multiplication. These studies demonstrated that CP-mediated resistance to virus infection can be extended to cereals and to the viruses transmitted by an insect vector (planthopper).

Base Sequence↗
PubMed1992

Protective effect of a selective endothelin receptor antagonist, BQ-123, in ischemic acute renal failure in rats.

To elucidate the pathophysiological role of endogenous endothelin (ET), we examined the effects of the newly synthesized ETA receptor-selective antagonist, BQ-123, on ischemic acute renal failure induced by bilateral clamping of renal artery and vein followed by reperfusion in rats. BQ-123, when given by i.v. infusion of 0.5 mg/kg per min for 2.5 h during the pre- and post-ischemic period, was found to prevent the decrease in creatinine clearance and increases in blood urea nitrogen, plasma creatinine and the fractional excretion of sodium. Morphological observation also showed an effect of BQ-123, i.e. prevention of proximal tubular (S3 segment) necrosis. At 2 h after the start of reperfusion, the ET-1 content in the kidney increased to its maximal level. At this time, the Ca2+ content in the mitochondrial fraction of the renal cortex increased, with a concomitant increase in blood urea nitrogen. However, these increases were limited by treatment with BQ-123. Thus, BQ-123 was effective to both prevent mitochondrial Ca2+ accumulation in the early phase of ischemic acute renal failure and protect proximal tubular cells from post-ischemic degeneration. We conclude that ET may be at least partially involved in the pathogenesis of tubular cell injury in this acute renal failure model.

Acute Kidney Injury↗
PubMed1992

2-(Carboxycyclopropyl)glycines: binding, neurotoxicity and induction of intracellular free Ca2+ increase.

The excitatory actions of the eight stereoisomers of 2-(carboxycyclopropyl)glycine (CCG), conformationally rigid glutamate analogues, were analyzed for the glutamate receptor subtypes by means of binding assays with rat brain membranes. All CCG isomers inhibited the binding of [3H]3-(2-carboxypiperazine-4-yl)propyl-1-phosphonic acid ([3H]CPP) to N-methyl-D-aspartate (NMDA) receptors. The (2S,3R,4S) isomer (L-CCG-IV) was the most potent agonist for the NMDA receptor and its binding potency was 17- and 790-fold higher than that of L-glutamate and NMDA, respectively. The (2S,3S,4R) isomer (L-CCG-III) showed a potent inhibitory activity for [3H]D-aspartate uptake. Further, L-CCG-IV caused a marked increase of intracellular free Ca2+ concentration [( Ca2+]i) and potent neurotoxicity in the single rat cerebral cortical neurons in vitro, and both were blocked effectively by the NMDA antagonists. Significant correlations were observed between neurotoxicity and the increase of [Ca2+]i and [3H]CPP binding affinity to the NMDA receptor.

Amino Acids, Dicarboxylic↗
PubMed1992

Immunoassays for the determination of human tissue kallikrein (TK) in different body fluids based on monoclonal antibodies.

A monoclonal antibody produced against human tissue kallikrein was used to develop solid phase immunoassays for the determination of total immunoreactive tissue kallikrein, of the complex of tissue kallikrein with alpha 1-proteinase inhibitor, and of enzymatically active tissue kallikrein. The assays permit the specific determination of various forms of tissue kallikrein in body fluids and should be very useful in studies on the biological function of tissue kallikrein-kinin systems.

Amino Acid Sequence↗
PubMed1992

Influence of CRT workstation on observer's performance.

The effects of the operability of the prototype CRT workstation and room illumination upon observer's performance were studied. In the experiment of reading CT images as a routine daily work at the CRT workstation, the average time required to analyse one CT image under a room illuminance of 100 lux was longer than that on the film viewbox. Prolongation occurred due mainly to the longer time required to retrieve and to arrange images as observers desired, and the limitation to the number of images simultaneously displayed on two CRT monitors. In the ROC studies to detect small pulmonary nodules on CRT images of computed radiography with imaging plate, illuminance around 170 lux showed the best result and a statistically significant difference (P less than 0.05) as compared with that of 480 lux. In addition to the radiologist's visual performance, room illumination must also be taken into consideration as it influences the observer's performance and diagnostic efficiency.

Computer Systems↗
PubMed1992

Budd-Chiari syndrome with long segmental inferior vena cava obstruction: treatment with thrombolysis, angioplasty, and intravascular stents.

The authors describe a patient with Budd-Chiari syndrome caused by long segmental thrombotic obstruction of the inferior vena cava associated with paroxysmal nocturnal hemoglobinuria. The patient was successfully treated with a combination of local thrombolytic therapy, balloon angioplasty, and placement of Gianturco expandable metallic stents.

Adult↗