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Biomedical subjects

K Ojima

Publications and source records attributed to K Ojima.

At least 73 records · Page 4Linked to original sources

[Studies on structure of light degradation products of (-)-(S)-10-(1-aminocyclopropyl)-9-fluoro-3-methyl-7-oxo-2,3-dihyd ro-7H- pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (T-3761) in aqueous solution and solid state].

The structures of light degradation products of (-)-(S)-10-(1-aminocyclopropyl)-9-fluoro-3-methyl-7-oxo-2,3-dih ydr o-7H- pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (T-3761) in aqueous solution and in the solid state were investigated. In aqueous solution, ten products were detected using HPLC and in the solid state, one main product was detected. All these light degradation products were isolated and their structures were elucidated. It was revealed that in almost all light degradation products only the 1-aminocyclopropyl side chain at the 10-position of T-3761 is changed to various structures by light oxidation. Surprisingly we found a unique light degradation product, in which carboxylic acid at the 6-position of T-3761 is changed to the hydroxy moiety.

Anti-Infective Agents↗

Nicorandil suppresses a hump on the monophasic action potential and torsade de pointes in a patient with idiopathic long QT syndrome.

The patient was a 71-year-old female with Torsade de Pointes (TdP) associated with idiopathic long QT syndrome. TdP and polymorphic nonsustained VT were frequently observed at bedside and an electrophysiologic study was performed. The QT (and QTU) interval was abnormally prolonged, and alteration of the QT interval was also recorded on the electrocardiogram. Monophasic action potential (MAP) from the right ventricle showed a hump on the falling limb of the MAP following a long RR interval of more than 1.0 sec. Intravenous administration of nicorandil (2 mg) resulted in disappearance of the hump, and ventricular arrhythmia was no longer observed. The QT interval at a PP interval of 720 msec was slightly shortened. She was treated with a DDD-pacemaker and given nicorandil. No recurrence of TdP was observed during the follow-up period of 8 months. This drug might be effective in patients with idiopathic long QT syndrome.

Action Potentials↗

Autopsy cases among patients with mental disorders: an unusual case of asphyxia caused by the iron roller of a garbage truck.

A case of asphyxia of a young man suffering from "Identity Disorder" as delineated by the DSM-III-R (American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders revised in 1987) is reported. The patient jumped into the drum of a garbage truck and the iron roller in the drum asphyxiated him by compression. In addition to the presentation of this rare category of the DSM-III-R disorders as an autopsy case and an unusual means of asphyxia, we briefly reviewed other autopsy cases of the patients with mental disorders who died in Japan between 1988 and 1992.

Accidental Falls↗

An autopsy case of osteogenesis imperfecta initially suspected as child abuse.

Osteogenesis imperfecta (OI) is an uncommon congenital disease of collagen synthesis. It has a wide range of phenotypic expressions, but it is classically characterized by varying degrees of bone fragility. Consequently, individuals with OI frequently suffer repeated severe bone injuries from otherwise innocuous traumatic events. In the evaluation of suspected child abuse cases with suspicious fractures, clinicians are taught to rule out the possibility of OI. However, because OI is quite rare, this possible diagnosis may be overlooked in situations where the child seems to have clearly suffered non-accidental trauma. OI may potentially be mistaken for child abuse by an inexperienced examiner. An autopsy case of osteogenesis imperfecta that was initially diagnosed as child abuse is presented.

Cardiac Output, Low↗

Beta 2- but not beta 1-adrenoceptors are involved in desipramine enhancement of aggressive behavior in long-term isolated mice.

The effects of several beta-adrenoceptor antagonists on the desipramine-induced increase in aggressive behavior in long-term isolated mice were examined. Desipramine HCl (10 mg/kg, IP) significantly increased the duration of aggressive behavior in isolated mice but did not significantly change the latency to the first attack consistent with our previous reports. Intraperitoneal administration of (+/- )propranolol HCl (2.5-10 mg/kg), a nonselective beta-adrenoceptor antagonist, dose dependently attenuated the desipramine-induced enhancement of aggressive behavior without significantly affecting the basal aggressive responses. ICI118,551 HCl (1.25-5 mg/kg, IP), a selective beta 2-adrenoceptor antagonist, also blocked the desipramine-induced enhancement of aggressive behavior in a dose-dependent manner, whereas metoprolol tartrate (5-20 mg/kg, IP), a selective beta 1-adrenoceptor antagonist, did not affect it. Moreover, clenbuterol HCl (0.1-0.5 mg/kg, IP), a lipophilic beta 2-adrenoceptor agonist, significantly increased the duration of basal aggressive behavior. Taken together with our previous finding that the desipramine-induced enhancement of aggressive behavior can be blocked by yohimbine, an alpha 2-adrenoceptor antagonist, the present results indicate that not only alpha 2- but also beta 2-adrenoceptor stimulation plays important roles in modulation of aggressive behavior in long-term isolated mice.

Aggression↗

Sudden and unexpected death due to undiagnosed pulmonary thromboembolism in an adolescent male without previous history of trauma.

We report a case of sudden death in a 19-year-old adolescent male who had been receiving hospital treatment because of a persistent right calf pain which had started about 18 days previously. The pain had not been relieved by analgesics, and had extended to the right thigh. The post-mortem examination revealed that the cause of death was pulmonary embolism by thrombi which had arisen in the right calf veins. The bilateral pulmonary arteries were packed with thrombi, and many pulmonary branches were occluded with fresh thrombi. The right calf veins contained thrombi of differing ages. In old thrombi, massive collagen formation and hemosiderin granules were present but elastic fibers had not yet formed. Therefore, it was considered that the old thrombi had formed at the time of the patient's first visit to the hospital. The right calf pain for which the deceased had sought medical advice was considered to have been caused by the vein thrombosis. Although various risk factors for the formation of thrombi are known, in the present case no precedent causes other than obesity were identified.

Adult↗

A groove observed in the face of an old man who probably died from acute asphyxia.

A continuous, horizontal groove about 0.7 cm wide was observed on the nape and lower part of the face of a 93-year-old man. The groove started from one corner of the mouth, traversed the nape, and reached the other corner of the mouth. It was most conspicuous at the nape. The mark was considered to have been produced by an electric cord. No facial congestion was noted, however, a few petechiae were present in the conjunctivae. There were no wounds in the front of the neck, while small hemorrhages were noted in the neck muscles. The right 2nd through 6th ribs were fractured and slight hemorrhage was observed in the overlying muscle. There were no pathologic changes accounting for death. The presence of the so-called triad for an acute death suggested strongly that the most likely cause of death was acute asphyxia. The relationship between the cause of death and the mark was the matter at issue. The mark may have been produced by a hanging in an unusual position, but there was no indication that a hanging was performed. For a ligature mark due to strangulation, the level was too high. The possibility that the mark was produced when the victim was gagged seemed to be very low. Thus, it could not be confirmed whether the groove had any relation with a fatal assault. Reflex cardiac arrest by vagal stimulation when the neck was compressed was the most likely cause of death.

Acute Disease↗

Tissue Distribution of Glutamate Synthase and Glutamine Synthetase in Rice Leaves : Occurrence of NADH-Dependent Glutamate Synthase Protein and Activity in the Unexpanded, Nongreen Leaf Blades.

To further explore the function of NADH-dependent glutamate synthase (GOGAT), the tissue distribution of NADH-GOGAT protein and activity was investigated in rice (Oryza sativa L.) leaves. The distributions of ferredoxin (Fd)-dependent GOGAT, plastidic glutamine synthetase, and cytosolic glutamine synthetase proteins were also determined in the same tissues. High levels of NADH-GOGAT protein (33.1 mug protein/g fresh weight) and activity were detected in the 10th leaf blade before emergence. The unexpanded, nongreen portion of the 9th leaf blade contained more than 50% of the NADH-GOGAT protein and activity per gram fresh weight when compared with the 10th leaf. The expanding, green portion of the 9th leaf blade outside of the sheath contained a slightly lower abundance of NADH-GOGAT protein than the nongreen portion of the 9th blade on a fresh weight basis. The fully expanded leaf blades at positions lower than the 9th leaf had decreased NADH-GOGAT levels as a function of increasing age, and the oldest, 5th blade contained only 4% of the NADH-GOGAT protein compared with the youngest 10th leaf blade. Fd-GOGAT protein, on the other hand, was the major form of GOGAT in the green tissues, and the highest amount of Fd-GOGAT protein (111 mug protein/g fresh weight) was detected in the 7th leaf blade. In the nongreen 10th leaf blade, the content of Fd-GOGAT protein was approximately 7% of that found in the 7th leaf blade. In addition, the content of NADH-GOGAT protein in the 10th leaf blade was about 4 times higher than that of Fd-GOGAT protein. The content of plastidic glutamine synthetase polypeptide was also the highest in the 7th leaf blade (429 mug/g fresh weight) and lowest in nongreen blades and sheaths. On the other hand, the relative abundance of the cytosolic glutamine synthetase polypeptide was the highest in the oldest leaf blade, decreasing to 10 to 20% of that value in young, nongreen leaves. These results suggest that NADH-GOGAT is important for the synthesis of glutamate from the glutamine that is transported from senescing source tissues through the phloem in the nongreen sink tissues in rice leaves.

Journal Article↗

Distinctive Responses of Ribulose-1,5-Bisphosphate Carboxylase and Carbonic Anhydrase in Wheat Leaves to Nitrogen Nutrition and their Possible Relationships to CO(2)-Transfer Resistance.

The amounts of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), total chlorophyll (Chl), and total leaf nitrogen were measured in fully expanded, young leaves of wheat (Triticum aestivum L.), rice (Oryza sativa L.), spinach (Spinacia oleracea L.), bean (Phaseolus vulgaris L.), and pea (Pisum sativum L.). In addition, the activities of whole-chain electron transport and carbonic anhydrase were measured. All plants were grown hydroponically at different nitrogen concentrations. Although a greater than proportional increase in Rubisco content relative to leaf nitrogen content and Chl was found with increasing nitrogen supply for rice, spinach, bean, and pea, the ratio of Rubisco to total leaf nitrogen or Chl in wheat was essentially independent of nitrogen treatment. In addition, the ratio of Rubisco to electron transport activities remained constant only in wheat. Nevertheless, gas-exchange analysis showed that the in vivo balance between the capacities of Rubisco and electron transport in wheat, rice, and spinach remained almost constant, irrespective of nitrogen treatment. The in vitro carbonic anhydrase activity in wheat was very low and strongly responsive to increasing nitrogen content. Such a response was not found for the other C(3) plants examined, which had 10- to 30-fold higher carbonic anhydrase activity than wheat at any leaf-nitrogen content. These distinctive responses of carbonic anhydrase activity in wheat were discussed in relation to CO(2)-transfer resistance and the in vivo balance between the capacities of Rubisco and electron transport.

Journal Article↗

Purification, Characterization, and Immunological Properties of NADH-Dependent Glutamate Synthase from Rice Cell Cultures.

To obtain a monospecific antibody against NADH-dependent glutamate synthase (NADH-GOGAT; EC 1.4.1.14), the enzyme was purified to homogeneity from cultured rice cells (Oryza sativa) with column chromatography using Butyl Toyopearl 650M, Sephacryl S-300, Blue Sepharose CL-6B, and Butyl Toyopearl 650S. The specific activity at the final stage of the purification was 9.8 micromoles of glutamate formed per minute per milligram of protein. The yield was 6.1% and purification was 815-fold. Analysis by denaturing gel electrophoresis revealed a single polypeptide with an apparent molecular weight of 196,000, similar to the value of 194,000 estimated for the native protein. Apparent K(m) values for l-glutamine, 2-oxoglutarate, and NADH were 811, 76, and 3.0 micromolar, respectively. Neither NADPH nor l-asparagine substituted for NADH and l-glutamine, respectively. The enzyme had its absorption maxima at 273, 373, and 440 nanometers with a shoulder at 475 nanometers, suggesting that the rice NADH-GOGAT is a flavoprotein. Monospecific antibody raised against NADH-GOGAT purified from the rice cells was obtained as the first instance for the enzyme in higher plants. Immunological analyses showed that the antibody for rice cell NADH-GOGAT reacted with only the enzyme in extracts from the cells. The anti-NADH-GOGAT antibody did not recognize the ferredoxin-GOGAT purified from rice leaves, and likewise the anti-rice leaf ferredoxin-GOGAT antibody did not react with the NADH-GOGAT purified from the cultured rice cells.

Journal Article↗

Changes in Cytosolic Glutamine Synthetase Polypeptide and its mRNA in a Leaf Blade of Rice Plants during Natural Senescence.

Changes in the levels of cytosolic glutamine synthetase (GS1) and chloroplastic glutamine synthetase (GS2) polypeptides and of their corresponding mRNAs have been investigated in segments of the 13th leaf of hydroponically grown rice (Oryza sativa L.) plants during natural senescence. The leaf blade on the main stem at early (0 day), middle (15 days), and late (25 days) stages of senescence was harvested and cut into 18 or 19 segments, 2 centimeters in length from the base to the tip. The amount of GS1 polypeptide, detected with specific antibody for the GS1, was greatest near the middle of the leaf blade (segments 11-13). There was little difference in the GS1 content between corresponding leaf segments obtained at the early and middle stages of senescence. At the late senescence stage, all segments had lost some GS1 polypeptide, but more than 50% of GS1 detected at both the early and middle stages was still detectable in segments. The relative content of mRNA for GS1 in the total RNA in all segments was very low during early senescence but increased in all leaf segments during later senescence. At the late stage of senescence, GS1 mRNA in the total RNA increased about 4.2- to 4.6-fold in segments 12 to 16 in the day-25 samples compared with those in the early stage. The content of the GS2 polypeptide, as well as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) protein, was highest in segment 17 in the 0-day samples. During senescence, this peak became lower and broader, and finally disappeared, i.e. approximately 80% of GS2 polypeptide and Rubisco protein in segment 17 were lost by day 25. In contrast with GS2 polypeptide, the relative level of GS2 mRNA increased 1.8- to 2.9-fold in individual segments at the middle stage of senescence. Even at the late stage, the transcript signals remained slightly higher than those at the early stage in all segments. Thus, GS1 and GS2 polypeptides and corresponding mRNAs responded in a different manner within an attached rice leaf during natural senescence. The contents of GS1 and GS2 polypeptides were not simply determined by the abundance of their corresponding mRNAs in the rice leaf blades during natural senescence.

Journal Article↗

Vascular bundle-specific localization of cytosolic glutamine synthetase in rice leaves.

Tissue localizations of cytosolic glutamine synthetase (GS1; EC 6.3.1.2), chloroplastic GS (GS2), and ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) in rice (Oryza sativa L.) leaf blades were investigated using a tissue-print immunoblot method with specific antibodies. The cross-sections of mature and senescent leaf blades from middle and basal regions were used for tissue printing. The anti-GS1 antibody, raised against a synthetic 17-residue peptide corresponding to the deduced N-terminal amino acid sequence of rice GS1, cross-reacted specifically with native GS1 protein, but not with GS2 after transfer onto a nitrocellulose membrane. Tissue-print immunoblots showed that the GS1 protein was located in large and small vascular bundles in all regions of the leaf blade prepared from either stage of maturity. On the other hand, GS2 and Fd-GOGAT proteins were mainly located in mesophyll cells. The intensity of the developed color on the membrane for GS1 was similar between the two leaf ages, whereas that for GS2 and Fd-GOGAT decreased during senescence. The tissue-specific localization of GS1 suggests that this GS isoform is important in the synthesis of glutamine, which is a major form of nitrogen exported from the senescing leaf in rice plants.

Journal Article↗

A Role for Glutamine Synthetase in the Remobilization of Leaf Nitrogen during Natural Senescence in Rice Leaves.

Changes in the levels of cytosolic glutamine synthetase (GS1) and chloroplastic glutamine synthetase (GS2) polypeptides and of corresponding mRNAs were determined in leaves of hydroponically grown rice (Oryza sativa) plants during natural senescence. The plants were grown in the greenhouse for 105 days at which time the thirteenth leaf was fully expanded. This was counted as zero time for senescence of the twelfth leaf. The twelfth leaf blade on the main stem was analyzed over a time period of -7 days (98 days after germination) to +42 days (147 days after germination). Total GS activity declined to less than a quarter of its initial level during the senescence for 35 days and this decline was mainly caused by a decrease in the amount of GS2 polypeptide. Immunoblotting analyses showed that contents of other chloroplastic enzymes, such as ribulose-1,5-bisphosphate carboxylase/oxygenase and Fd-glutamate synthase, declined in parallel with GS2. In contrast, the GS1 polypeptide remained constant throughout the senescence period. Translatable mRNA for GS1 increased about fourfold during the senescence for 35 days. During senescence, there was a marked decrease in content of glutamate (to about one-sixth of the zero time value); glutamate is the major form of free amino acid in rice leaves. Glutamine, the major transported amino acid, increased about threefold compared to the early phase of the harvest in the senescing rice leaf blades. These observations suggest that GS1 in senescing leaf blades is responsible for the synthesis of glutamine, which is then transferred to the growing tissues in rice plants.

Journal Article↗

Photosynthetic Characteristics of Rice Leaves Aged under Different Irradiances from Full Expansion through Senescence.

Effects of irradiance on photosynthetic characteristics were examined in senescent leaves of rice (Oryza sativa L.). Two irradiance treatments (100 and 20% natural sunlight) were imposed after the full expansion of the 13th leaf through senescence. The photosynthetic rate was measured as a function of intercellular CO(2) pressure with a gas-exchange system. The amounts of cytochrome f, coupling factor 1, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), and chlorophyll were determined. The coupling factor 1 and cytochrome f contents decreased rapidly during senescence, and their rates of decrease were much faster from the 20% sunlight treatment than from the full sunlight treatment. These changes were well correlated with those in the photosynthetic rate at CO(2) pressure = 600 microbars, but not with those under the ambient air condition (350 microbars CO(2)) and 200 microbars CO(2). This suggested that the amounts of coupling factor 1 and cytochrome f from the full sunlight treatment cannot be limiting factors for the photosynthetic rate at ambient air conditions. The Rubisco content also decreased during senescence, but its decrease from the 20% sunlight treatment was appreciably retarded. However, this difference was not reflected in the photosynthetic rates at the ambient and 200 microbars CO(2). This implied that in vivo Rubisco activity may be regulated in the senescent leaves from the 20% sunlight treatment. The chlorophyll content decreased most slowly. In the 20% sunlight treatment, it remained apparently constant with a decline in chlorophyll a/b ratio. These photosynthetic characteristics of the senescent rice leaves under low irradiance were discussed in relation to acclimation of shade plants.

Journal Article↗

Characteristics of ribulose-1,5-bisphosphate carboxylase/oxygenase degradation by lysates of mechanically isolated chloroplasts from wheat leaves.

The lysate from intact chloroplasts mechanically isolated from primary leaves of 9 day old seedlings of wheat (Triticum aestivum L. var Aoba) was incubated in the pH range of 5.5 to 8.5 at 37 degrees C for 5 hours. Proteolytic activity against ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) was estimated by disappearance of the large subunit of Rubisco or the appearance of its degradation products. Although the activity in lysates was weak, the products were detected by applying Western blotting. The degradation products were similar to those obtained when Rubisco was incubated with the lysate of vacuoles isolated from like leaves. Although some of the products were similar to those from vacuole lysates, many were clearly different after incubation of Rubisco with trypsin, V-8 protease, or reactive oxygen (hydroxy radical). Lysates of chloroplasts, pretreated with thermolysin at 4 degrees C for 30 minutes, had no proteolytic activity against Rubisco after incubation at 37 degrees C for 5 hours. These results show that the proteolytic activity against Rubisco found in lysates of our mechanically isolated chloroplasts was mostly due to the contamination of vacuolar proteases adhering to the outer envelope of the chloroplasts during their isolation.

Journal Article↗