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Biomedical subjects

M Tsunoda

Publications and source records attributed to M Tsunoda.

At least 73 records · Page 4Linked to original sources
PubMed1995

Electrostatic potential in aminoacylation by aspartyl-tRNAs synthetase.

Based upon the X-ray structures of complexes between tRNAAsp and aspRS including ATP or Asp-AMP, several electrostatic potentials were calculated by solving the Poisson-Boltzmann equation. The potentials indicate clearly that a Mg2+ ion is essential for binding of ATP and that aspartate is identified electrostatically. The alpha-carboxyl group is forced to contact with the alpha-phosphorus atom of ATP, suggesting its inversion to form an Asp-AMP. When the cognate tRNA is bound to the aspRS:Asp-AMP complex, the 3'-hydroxyl group is located in an electrostatically favorable position to transfer the amino acid as a class II aminoacylation.

Acylation↗
PubMed1994

Evidence for the accumulation of oxidative stress during cellular ageing of human diploid fibroblasts.

We have examined the level of 8-hydroxydeoxyguanosine (8-OH-dG) in the DNA of human diploid fibroblast TIG-1 cells at various stages of cellular ageing. Cellular DNA was obtained from cell lysates by simple precipitation with ethanol and analyzed 8-OH-dG levels by an electrochemical detection system. The data reveals that this method is valid for the detection of 8-OH-dG at levels of 1 x 10(-6) 8-OH-dG/dG without altering the recovery of other deoxynucleosides. Using this method, we demonstrate a significant increase in 8-OH-dG content during cellular ageing up to a 50 population doubling level (PDL) of TIG-1 cells, with levels of 0.5 x 10(-6) and 1.6 x 10(-6) 8-OH-dG/dG in young (22 PDL) and old (50 PDL) cells, respectively. The level decreases with further ageing and is 1.3 x 10(-6) 8-OH-dG/dG in senescent cells. We also show that the repair activity for the 8-OH-dG lesion declines significantly during cellular ageing, a phenomenon that might be associated with the increase in 8-OH-dG levels.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1994

Cloning and expression in Enterobacteriaceae of the extended-spectrum beta-lactamase gene from a Pseudomonas aeruginosa plasmid.

An extended-spectrum beta-lactamase, the gene for which is located on plasmid pMS350 in Pseudomonas aeruginosa strains, hydrolyzes carbapenems and other extended-spectrum beta-lactam antibiotics. We cloned the pMS350 beta-lactamase gene in an Escherichia coli K-12 strain using the vector plasmid pHSG398, and subcloned it into pMS360, a plasmid with a wide host-range. This resulted in the formation of the recombinant plasmid, pMS363, containing a 4.1-kb DNA insert that includes the extended-spectrum beta-lactamase gene. Plasmid pMS363 was introduced into the P. aeruginosa PAO strain or into six species of Enterobacteriaceae, and the specific activities of the beta-lactamase and MICs of various beta-lactam antibiotics were estimated. The cloned gene was capable of expression in these strains and caused resistance to carbapenem, penem and other beta-lactam antibiotics, with the exception of aztreonam.

Cloning, Molecular↗
PubMed1994

Limited visual search on the WAIS Picture Completion test in patients with schizophrenia.

The Wechsler Adult Intelligence Scale was examined in 39 patients with schizophrenia, the visual cognitive task of Picture Completion showing the most impairment. In order to clarify the role of eye movements in Picture Completion, searching eye movements in 12 schizophrenic patients and 12 normal controls were recorded using an infrared eye-mark recorder. Schizophrenic patients as a group showed fewer eye fixations, and shorter total length of scan path than normal controls during the last 10 s of exposure to the picture. However, the patients who responded correctly, did so with a similar number of fixations and similar length of total scan path to those of normal controls. The patients who failed in the task took a significantly longer time for the first survey of the picture than the successful patients and normal controls. The less efficient strategy of visual search seen in the patients who failed might be a manifestation of poor reality testing and be related to frontal lobe dysfunction.

Adult↗
PubMed1994

Quantitative measurement of portal blood flow by magnetic resonance phase contrast: comparative study of flow phantom and Doppler ultrasound in vivo.

A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flowmetry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow.

Adult↗
PubMed1994

The relation between cubital tunnel syndrome and the elbow alignment.

The authors reviewed forty-three surgically managed cases of cubital tunnel syndrome treated during the past twelve years. Surgery had been performed on thirty-one men and twelve women. Their average age was 46.8 years old. The etiology of cubital tunnel syndrome had been determined as follows: There were twenty-three cases of osteoarthritis of the elbow joint. There were four cases of isolated cubitus valgus deformity. There were three cases of isolated cubitus varus deformity. There were three cases of rheumatoid arthritis. One patient had sustained trauma to the cubital tunnel. In nine other patients there were various causes but no joint malalignment. The selection of the surgical technique for the correction of cubital tunnel syndrome was a function of the etiology of the condition. Cubital tunnel syndrome from osteoarthritis was surgically managed with a modified King technique. Ulnar neuropathy with a cubitus valgus deformity was managed with an ulnar nerve anterior transposition. Ulnar neuropathy with a cubitus varus deformity was managed with a neurolysis. The surgical outcome for cubital tunnel syndrome in patients with an angular deformity at the elbow frequently was not optimum. However, although some patients remained symptomatic, the majority of postoperative patients did obtain improved motor strength and conduction velocities. This confirmed the efficacy of surgical management regardless of the cubital tunnel syndrome etiology.

Adolescent↗
PubMed1993

Evidence for involvement of phospholipase C-gamma 2 in signal transduction of platelet-derived growth factor in vascular smooth-muscle cells.

In order to examine the mechanisms underlying smooth-muscle cell proliferation, we investigated effect of platelet-derived growth factor (PDGF) dimers on proliferation of rabbit vascular smooth-muscle cells (VSMCs) and also involvement of phospholipase C (PLC) isoforms in the signal transduction. PDGF-BB and -AB, but not -AA, stimulated cell proliferation and intracellular production of inositol trisphosphate. Northern and Western analyses demonstrated that VSMCs mainly expressed PLC-gamma 2 and PLC-delta 1 among four PLC isoforms tested. A number of cellular proteins, including PLC-gamma 2, but not PLC-delta 1, were phosphorylated on a tyrosine residue by the stimulation of either PDGF-BB or -AB. These results suggest a functional association of PDGF receptor and PLC-gamma 2 that might be responsible for PDGF-dependent VSMC growth. In addition, the expression of PLC-gamma 2 was extremely low in the primary VSMC cultures and was induced during further cultivation of the primary cultures, indicating that an acquisition of PDGF-signal-transducing components, including PLC-gamma 2, may be an important step for proliferation of smooth-muscle cells.

Animals↗
PubMed1993

A single universal primer for the T-cell receptor (TCR) variable genes enables enzymatic amplification and direct sequencing of TCR beta cDNA of various T-cell clones.

We designed a primer for the PCR directed against a highly conserved sequence of the TCR V beta gene. The V beta-universal primer, in combination with a constant region-specific primer, enabled us to amplify TCR beta cDNA of allo-HLA class-II-reactive T-cell clones by PCR without prior knowledge of their V beta sequences. The amplified TCR cDNA was purified by agarose gel electrophoresis and subjected to direct sequencing. In nine of ten T-cell clones analyzed, direct TCR sequencing gave readable sequence ladders, including two-thirds of V beta, junctional, and J beta regions. One T-cell clone gave an unreadable mixed-profile sequence ladder, indicating that this clone expressed more than one major TCR beta transcript. Even in this case, however, it was possible to determine two different TCR beta sequences separately using sequence primers specific to one of the 13 J beta segments deduced from the mixed ladder. Thus, direct sequencing utilizing the single V beta-universal primer enabled a simple, rapid, and reliable sequence determination of TCR beta cDNA of all T-cell clones analyzed.

Amino Acid Sequence↗
PubMed1993

Simultaneous determination of organotin compounds in fish and shellfish by gas chromatography with a flame photometric detector.

In the present study the levels of the organotin compounds were determined in fish and shellfish which were purchased from retail markets in Niigata, Japan. The concentrations of dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPT) and triphenyltin (TPT) compounds were separately determined by FPD-gas chromatography. Eight species (yellowtail, tuna, cuttlefish, olive flounder, northern shrimp, cinnamon flounder, Japanese sea bass and oyster) were studied and five samples of each species were analyzed in each season, which meant 40 samples in one season, and 160 in total. Among the compounds of interest, DBT, TBT and TPT were detected. The highest concentrations detected were 0.674 microgram/g for DBT, 0.669 microgram/g for TBT and 0.186 microgram/g for TPT. DBT was detected as much as TBT, however, its concentration was not correlated with that of TBT. Seasonal changes of the mean value of the concentration of DBT and TBT were observed. In some species, such as yellowtail and Japanese sea bass, combined contaminations of these organotin compounds were also evident. This study is the first step to elucidate possible health hazards by environmental pollution of organotin compounds on human beings.

Animals↗
PubMed1993

The osteogenic potential of fracture hematoma and its mechanism on bone formation--through fracture hematoma culture and transplantation of freeze-dried hematoma.

This study was conducted to provide further evidence of the inherent osteogenic potential of the fracture hematoma. The fracture hematoma was separated into its cellular and extracellular elements. The hematoma cells were cultured to study bone formation by the cellular elements alone. Bone formation acceleration factor was added to the cultured fracture hematoma cells. The cell responded to this stimulation by differentiation into chondrocytes. Fracture hematoma was freeze-dried to study the presence of osteoinduction by the extracellular factors in the fracture hematoma. The freeze-dried fracture hematoma was packaged in methylmethacrylate pellets and within capsules of hydroxyapatite. These pellets and capsules in response to extracellular humoral factors from the freeze-dried fracture hematoma. The results of experimental implantation of the cultured fracture hematoma cells revealed that these cells had the potential to differentiate into chondroblasts or osteoblasts when bone induction factors and bone acceleration factor was added to their media. These extracellular humoral factors are known to be present in the fracture hematoma.

Animals↗
PubMed1992

Scanning eye movements in schizophrenic patients. Relationship to clinical symptoms and regional cerebral blood flow using 123I-IMP SPECT.

Eye movements during the Benton Visual Retention Test were examined using an eye-mark recorder in 32 schizophrenic patients and 32 normal controls. The patients had significantly fewer eye fixations, longer mean duration of fixation and shorter length of mean scan path than the controls. In the patients, these eye movement parameters were significantly correlated with the negative symptom score but not with the positive symptom score on the Positive and Negative Syndrome Scale. These parameters had a significant correlation with the composite score on the Scale for the Assessment of Negative Symptoms (SANS). In particular, they were highly correlated with avolition-apathy and affective flattening or blunting scores on SANS subscales. Thus, examination of scanning eye movements seemed to be a good objective index of negative symptoms. Secondly, regional cerebral blood flow (rCBF) was examined using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) and single photon emission computer tomography in 17 of 32 patients. With regard to the relationship between the eye movement parameters and rCBF, the mean duration of fixation was negatively correlated with 123I-IMP uptake in the left superior frontal area and left basal ganglia. The mean length of the scan path was correlated with uptake in the left superior frontal area. These findings suggest that the characteristic eye movements of schizophrenic patients are likely to be related with dysfunction of the frontal-basal ganglia neural circuit.

Adult↗
PubMed1992

[Studies on insulin secretion and clearance in obese and diabetic children (7-11 years old) and adolescents (12-16 years old) investigation by oral glucose tolerance tests (O-GTT)].

We analyzed O-GTT obtained from 375 children (group A; 7-11 years old) and adolescents (group B; 12-16 years old), including 96 normal non-obese cases, 266 simple obese cases (172 with normal O-GTT, 79 with border line type O-GTT and 15 with diabetic type O-GTT), 8 obese NIDDM cases and 5 non-obese NIDDM cases. The results were as follows; 1) The levels of epsilon CPR (in terms of total sum of the values measured at 0, 30, 60, 120 and 180 minutes on O-GTT) in the obese children and adolescents were only 1.5 and 1.2 times as high as in the control group. The levels of epsilon CPR/epsilon IRI molar ratio in the control group were 2.0 and 2.3 times as high as in the obese children and adolescents. These data suggest that hyperinsulinemia in the obese children and adolescents is caused mainly by decreased hepatic insulin extraction rather than by increased insulin secretion. 2) In the non-obese NIDDM adolescents, the levels of epsilon CPR decreased to about 3/4 of those in the control group; in contrast, the epsilon CPR/epsilon IRI molar ratio increased. Therefore, it seems that there is increased hepatic insulin extraction as well as decreased insulin secretion in the non-obese NIDDM adolescents. 3) In the obese NIDDM adolescents, the levels of epsilon CPR were nearly the same as in the control group and the epsilon CPR/epsilon IRI molar ratios were slightly lower as the disease state of NIDDM counterbalanced obesity.

Adolescent↗
PubMed1992

Acute toxicity of tri-n-butyltin chloride (TBTC) in the Syrian golden hamster.

The effects of tri-n-butyltin chloride (TBTC) on Syrian golden hamsters were studied. TBTC in single doses of 0, 29.6, 44.4, 66.7, 100 or 150 mg/kg were given to 10 male hamsters in each group and the mortality rates were determined two weeks thereafter. They were 0% (0/10), 0% (0/10), 10% (1/10), 10% (1/10), 30% (3/10) and 70% (7/10) for 0, 29.6, 44.4, 66.7, 100 and 150 mg/kg groups, respectively. In the case of females, seven groups consisting of 10 animals each were given TBTC at doses of 0, 29.6, 44.4, 66.7, 100, 150, or 225 mg/kg. The mortality rates determined two weeks after the TBTC treatment were 0% (0/10), 10% (1/10), 10% (1/10), 0% (0/10), 40% (4/10), 30% (3/10) and 90% (9/10) for 0, 29.6, 44.4, 66.7, 100, and 225 mg/kg groups, respectively. Based on these mortality data, the LD50s via oral administration were determined as 146.9 mg/kg (95% C.I. 111.8-193.3 mg/kg) for the male and 172 mg/kg (95% C.I. 127.2-233.4 mg/kg) for the female. Regarding pathological changes, animals experienced lesions in the bile duct, such as the dilatation of the common bile duct and cholestasis, and/or adhesion of the bile duct to the liver, gallbladder, pancreas and duodenum. In a separate experiment, a single dose of 44.4 mg/kg TBTC was administered orally to 12 male hamsters, then the concentrations of TBTC and its metabolite, di-n-butyltin chloride (DBTC), in the liver were analyzed by means of gas chromatography for 14 days after the treatment. The maximum concentrations of TBTC and DBTC appeared one day after the administration, and decreased rapidly thereafter. The concentration of DBTC was found to be higher than that of TBTC throughout the experimental period.

Alanine Transaminase↗