Biomedical subjects

T Aoki

Publications and source records attributed to T Aoki.

At least 649 records · Page 36Linked to original sources

PubMed1994

Ventilation-perfusion inequality and diffusion impairment in acutely injured lungs.

To assess the significant role of diffusion impairment and its unequal distribution in acutely injured lungs with alveolar flooding, oleic acid was intravenously injected into twenty-five mongrel dogs. The animals were divided into two groups, A and B. 0.1% CO in air was delivered, as an inspired gas, to the animals of group A. Simultaneously, saline containing a trace amount of six foreign inert gases was infused through a peripheral vein. While allowing the animals in group B to breathe air, saline containing ethylene, acetylene and freon 22 was infused. After injection of oleic acid, group A revealed increase in intrapulmonary shunt accompanied by a marked broadening of ventilation-perfusion (VA/Q) and diffusing capacity-perfusion (G/Q) distributions. A considerable amount of total cardiac output was received by the lung areas with low G/Q ratios where significant diffusion limitation was predicted to occur. Group B showed that excretion of freon 22 (gas with lower diffusivity) in injured lungs was considerably distorted as compared to those of ethylene and acetylene (gases with higher diffusivities), again ascertaining the importance of diffusion limitation in lungs with exudate in alveolar regions.

Animals↗

PubMed1994

Sequence comparison between the flavoprotein subunit of the fumarate reductase (complex II) of the anaerobic parasitic nematode, Ascaris suum and the succinate dehydrogenase of the aerobic, free-living nematode, Caenorhabditis elegans.

Complex II in adult mitochondria of the parasitic nematode, Ascaris suum, exhibits high fumarate reductase activity and plays a key role in the anaerobic electron-transport observed in these organelles. In the present study, cDNAs for the flavoprotein (Fp) subunits of complex II have been isolated, cloned and sequenced from both A. suum and the aerobic, free-living nematode, Caenorhabditis elegans. Additional sequence at the 3' end of the mRNAs was determined by the Rapid Amplification of cDNA Ends (RACE). Nucleotide sequence analysis of the A. suum cDNAs revealed a 22-nucleotide trans-spliced leader sequence characteristic of many nematode mRNAs, an open reading frame of 1935 nucleotides and a 3' untranslated region of 616 nucleotides including a poly (A) tail from a polyadenylation signal (AATAAA). The open reading frame encoded a 645 amino acid sequence, including a 30 amino acid mitochondrial presequence. The amino acid sequences for the Fp subunits from both organisms were very similar, even though the ascarid enzyme functions physiologically as a fumarate reductase and the C. elegans enzyme a succinate dehydrogenase. The ascarid sequence was much less similar to the Escherichia coli fumarate reductase. The sensitivity of other Fp subunits to sulfhydryl reagents appears to reside in a cysteine immediately preceding a conserved arginine in the putative active site. In both nematode sequences, this cysteine is replaced by serine even though the succinate dehydrogenase activity of both enzymes is still sensitive to sulfhydryl inhibition. A cysteine six residues upstream of the serine may be involved in the sulfhydryl sensitivity of the nematode enzymes. Surprisingly, in contrast to succinate dehydrogenase activity, the fumarate reductase activity of the ascarid enzyme was not sensitive to sulfhydryl inhibition, suggesting that the mechanism of the two reactions involves separate catalytic processes.

Amino Acid Sequence↗

PubMed1994

Demonstration of sweat allergy in cholinergic urticaria.

Twenty patients with cholinergic urticaria, 11 sex- and age-unmatched patients with acute or chronic urticaria and 20 sex- and age-matched non-atopic control subjects were skin tested with autologous sweat. All cholinergic urticaria patients showed positive immediate-type skin reactions at 2(0)-2(9) dilutions of sweat (geometric mean of maximal positive dilutions +/- S.D. was 2(4.6 +/- 2.6), while in acute and chronic urticaria only three patients showed positive reactions at low dilutions (two 2(0) and one 2(1)) and none of 20 controls showed positive reactions. Prausnitz-Küstner (P-K) tests performed with the serum and sweat from six patients were all positive at 2(3)-2(8) dilutions. Percent histamine release from peripheral leukocytes of five patients challenged with the standard sweat samples was significantly higher than in five control subjects. Histamine release from leukocytes of the patient on sweat challenging was abandoned by acid treatment of leukocytes. Leukocytes, from a healthy subject sensitized with the patient's serum, released histamine on sweat challenging. These results seem to indicate that cholinergic urticaria patients have a type I allergy to their own sweat.

Adolescent↗

PubMed1994

Movement of single myosin filaments and myosin step size on an actin filament suspended in solution by a laser trap.

Movement of single myosin filaments, synthesized by copolymerization of intact myosin and fluorescently labeled light meromyosin, were observed along a single actin filament suspended in solution by a dual laser trap in a fluorescence microscope. The sliding velocity of the myosin filaments was 11.0 +/- 0.2 micron/s at 27 degrees C. This is similar to that of actin moving toward the center from the tip (the physiological direction) of myosin filaments bound to a glass surface but several times larger than that in the opposite direction (Ishijima and Yanagida, 1991; Yanagida, 1993). This indicates that the movement of myosin filaments is dominated by the myosin heads on one side of the myosin filament, which are correctly oriented relative to the actin filament. The incorrectly oriented myosin heads on the other side do not interfere with the fast movement. The step size (displacement produced during one ATPase cycle) of correctly oriented myosin was estimated from the minimum number of myosin heads necessary to produce the maximum velocity. This was determined by measuring the velocities of various lengths of myosin filaments. The minimum length of the myosin filaments moving near the maximum velocity was 0.30-0.40 microns, which contains 20 +/- 5 correctly oriented myosin heads. This number leads to a myosin step size of 71 +/- 22 nm. This value probably represents the lower limit, because all of the myosin heads on the filament would not always interact with the actin filament. Thus, the myosin step size is considerably larger than the length of a power stroke expected from the physical size of a myosin head, 10-20 nm (Huxley, 1957, 1969).

Actins↗

PubMed1994

Temperature modulated solubility-activity alterations for poly(N-isopropylacrylamide)-lipase conjugates.

Chemical modification of proteins by use of functional polymers is expected to endow them with new properties without destroying their native functions, thus providing useful materials for application in different fields. We have synthesized poly(N-isopropylacrylamide) [poly(IPAAm)] co-oligomer with N,N-dimethylacrylamide (DMAAm) and reactive end groups by telomerization of IPAAm. This co-oligomer exhibits a lower critical solution temperature (LCST) at 37 degrees C. Using this temperature-responsive semitelechelic co-oligomer, we prepared polymer-enzyme conjugates of lipase by covalent coupling via carboxyl end-groups. This bioconjugate exhibits a LCST at 37 degrees C, having rapid, reversible hydration-dehydration changes due to highly mobile free polymer end groups. The conjugate retained its native enzymatic activity below this critical temperature, above which it precipitated and its catalytic function was shut off. This conjugate can be readily separated from reaction mixtures as a precipitate by simple temperature changes after reaction and reused in cycles without denaturation. Such a modulated system is attractive for application as a novel bioreactor system.

Acrylic Resins↗

PubMed1994

Acute urticaria: history and natural course of 50 cases.

Fifty patients with acute urticaria who visited within a week after the onset were interviewed and the history around the onset of urticaria was carefully taken. It was known that the majority of the patients had experienced some symptoms suggestive of infection. The patients were followed up for a year to determine the last efflorescence. It was disclosed that 43 cases were cured within two weeks and 5 other cases were cured between 2 weeks and 3 months. The remaining 2 cases persisted over a year. These results seem to suggest that urticaria is an immunologically erroneous reaction to foreign body innoculation, a large majority of which is acute infection.

Acute Disease↗

PubMed1994

The transposon-like structure of IS26-tetracycline, and kanamycin resistance determinant derived from transferable R plasmid of fish pathogen, Pasteurella piscicida.

Tetracycline (pp-tet), and kanamycin (pp-kan) resistance genes were cloned from a transferable R plasmid of fish pathogen Pasteurella piscicida, and complete nucleotide sequences were determined. The pp-tet was a class D Tet determinant constructed with the tetA resistance gene of 1,182 bp encoding a protein with a deduced molecular mass of 41 kDa and the tetR repressor gene of 654 bp encoding a product of 24 kDa. The pp-tet was highly homologous to the tet(D) of plasmid RA1 isolated from Aeromonas hydrophila with two nucleotide differences in the tetR, and of plasmid pIP173 from Salmonella ordonez with two nucleotide differences in the tetA. The pp-kan contained 813 bp encoding a 31 kDa protein of 271 amino acids, and was classified into type aph-Ic. It was identical to the aphA7 in the IAB operon of pBWH77, in which was originally found an isolate of Klebsiella pneumoniae, in its nucleotide sequences and hybrid promoter construction. The genes were connected by an insertion sequence IS26 of 820 bp, and were flanked by repeated copies in direct orientation at the 3' flanking region of the pp-tetA and in inverted orientation at the 3' flanking region of the pp-kan. The genetic elements are organized like a complex transposon by close linkage of the IS26 and the pp-tet and -kan.

Amino Acid Sequence↗

PubMed1994

Characterization and localization of mouse hypothalamic growth hormone-releasing factor and effect of gold thioglucose-induced hypothalamic lesions.

Hypothalamic growth hormone-releasing factor (GRF) in higher mammals, including human GRF, is a 44 amino acid residue peptide and is highly homologous in structure. By contrast, mouse GRF (mGRF) recently deduced by cDNA cloning consists of only 42 residues and shows relatively low homology to the GRFs of higher mammals and the same rodent species, rat. To characterize and localize the predicted mature mGRF peptide in the hypothalamus, we have generated its antiserum and developed a homologous radioimmunoassay. Immunoreactive mGRF in the acid hypothalamic extract was eluted as a single peak at a position identical to that of synthetic peptide on both gel filtration chromatography and reverse-phase high-performance liquid chromatography (HPLC). Secretion of immunoreactive mGRF from incubated hypothalami increased several fold in response to 50 mM K+, and this rise was abolished in the absence of medium Ca2+. Only a single peak of immunoreactive mGRF that coeluted with synthetic replicate was observed after the K(+)-stimulated medium was extracted on Bond Elut C18 cartridges and applied on reverse-phase HPLC. Immunohistochemistry identified many mGRF-positive cell bodies in the arcuate nucleus and dense bundles of immunoreactive fibers in the median eminence. Treatment of mice with gold thioglucose (GTG), a chemical agent known to cause hypothalamic lesions, markedly depleted both content and in vitro secretion of immunoreactive mGRF. The decline in mGRF secretion was greater in GTG obese than in nonobese mice, whereas somatostatin secretion was not affected by GTG treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Cerebrospinal fluid concentrations of interleukin-1 beta, tumour necrosis factor-alpha, and interferon gamma in bacterial meningitis.

To investigate the role of the inflammatory cytokines, the cerebrospinal fluid concentrations of interleukin (IL)-1 beta, tumour necrosis factor-alpha (TNF-alpha), and interferon gamma (IFN-gamma) were measured in 11 children with bacterial meningitis and two with mycoplasmic meningoencephalitis and compared with those in 50 children with aseptic meningitis and 15 with non-pleocytotic cerebrospinal fluid. Concentrations of IL-1 beta and TNF-alpha were each significantly higher in the cerebrospinal fluid of patients with bacterial meningitis than in those with aseptic meningitis or those with non-pleocytotic cerebrospinal fluid. IFN-gamma was detected at low concentrations in the cerebrospinal fluid of only 2/11 of those with bacterial meningitis. On the other hand, the IFN-gamma concentration was the highest in the cerebrospinal fluid of patients with aseptic meningitis. These results suggest that the inflammatory cytokines are differently released in the intrathecal space infected with viruses or bacteria.

Adolescent↗

PubMed1994

Empyema and mediastinitis complicating retropharyngeal abscess.

A 21 year old man with a retropharyngeal abscess complained of right sided chest pain, and chest radiography and thoracocentesis revealed an empyema. A computed tomographic scan of the chest showed a posterior mediastinal abscess communicating with the right pleural cavity. Emergency thoracotomy was performed and the mediastinal abscess and empyema were drained.

Acute Disease↗

PubMed1994

Serum concentration of 7S collagen and prognosis in patients with the adult respiratory distress syndrome.

BACKGROUND--7S collagen, an N-terminal peptide of type IV collagen, is a primary constituent of the basement membrane. To evaluate whether the serum concentration of 7S collagen reflects the severity of inflammatory lung disease, the serum concentration of 7S collagen was measured in patients with adult respiratory distress syndrome (ARDS) and idiopathic pulmonary fibrosis (IPF). METHODS--A radioimmunoassay was used for the measurement of 7S collagen. Gas exchange abnormality was expressed as the arterial oxygen tension (PaO2) divided by the fractional concentration of inspired oxygen (FiO2). RESULTS--The mean (SD) concentration of 7S collagen was 2.7 (0.9) ng/ml in 10 healthy subjects, 5.0 (1.5) ng/ml in 11 patients with IPF, and 14.8 (9.7) ng/ml in 13 patients with ARDS. Significant differences were observed between the patients with ARDS and both healthy subjects and the patients with IPF. In the patients with ARDS serum concentrations of 7S collagen were strongly related to PaO2/FiO2 (r = -0.61). Moreover, the mean (SD) serum concentration of 7S collagen in the eight patients with ARDS who died (19.5 (10.2) ng/ml) was considerably higher than that of the five who survived (7.1 (2.1) ng/ml). CONCLUSION--These results suggest that serum levels of the 7S fragment of type IV collagen may have some prognostic value in ARDS.

Adolescent↗

PubMed1994

Morphological observation on extrahepatic bile duct of golden hamsters fed a lithogenic diet: histochemical, ultrastructural and cell kinetic studies.

Cholelithiasis is often accompanied with disorders of the extrahepatic bile duct and pancreas. However, studies on changes of the extrahepatic bile duct in cholecystolithiasis have not shown this clearly. We therefore investigated sequential histologic changes, mucous secretion and DNA synthetic activity of the extrahepatic bile duct epithelium in cholecystolithiasis. Serial changes in the mucosal epithelial cells of the extrahepatic bile duct in golden hamsters treated with a lithogenic diet were examined by light and electron microscopy and an ultrastructural quantitative technique. In addition, epithelial cell kinetics were studied using bromodeoxyuridine (BrdU). After the 2nd week of diet, the extrahepatic bile duct showed an increase in goblet cells of the mucosal epithelium, a large number of secretory granules in the upper nuclear area of the epithelial cells and an increase in the BrdU-labeling index compared with the controls. These findings indicate that mucous secretion and cell turnover were enhanced in the mucosal epithelial cells of the extrahepatic bile duct in cholelithiasis, suggesting that the epithelial cells of the bile duct were protected and regenerating.

Animals↗

PubMed1994

Diagnosis of moyamoya disease with magnetic resonance angiography.

BACKGROUND AND PURPOSE: Present criteria for the diagnosis of moyamoya disease emphasize the use of conventional cerebral angiography as an indispensable requirement. However, magnetic resonance angiography (MRA) is fast becoming a reliable diagnostic modality for occlusive cerebrovascular diseases. The purpose of this study is to assess the accuracy of MRA compared with conventional angiography. METHODS: Thirty-nine patients (23 children and 16 adults) with moyamoya disease confirmed by conventional angiography (78 side views) were examined with MRA (three-dimensional time-of-flight technique with a 256 x 256 or 256 x 512 matrix). T1- and T2-weighted MR images were also taken. RESULTS: The stenotic or occlusive change at the carotid fork was clearly revealed by MRA, which correlated well with conventional angiography (83% good correlation, 17% overestimation). Apparent moyamoya vessels were clearly shown as a signal void on the MR image and fine unusual vessels on MRA, particularly in children with moyamoya disease (82%). However, small moyamoya vessels were poorly shown on both MR images and MRA, particularly in adults (63%). CONCLUSIONS: MRA can be an alternative to conventional angiography in typical moyamoya disease cases (the bilateral type of moyamoya disease in children). However, in the early or the end stages of moyamoya disease, diagnosis by means of MRA should be carefully evaluated.

Adolescent↗

PubMed1994

Electrophoretic analysis of a gastric cancer-associated acid proteinase using a highly sensitive detection system.

A highly sensitive detection system for acid proteinase separated on polyacrylamide gel was established. This system consisted of two-dimensional electrophoresis, combined with isoelectric focusing and polyacrylamide gel electrophoresis, and casein clotting (caseogram). Human urine, serum and gastric tissues obtained from normal individuals and gastric cancer patients were analyzed using this system. The previous electrophoretic method was not sufficiently sensitive to detected small amounts of pepsinogen (PG) C in normal urine. However, the new rapid and sensitive method clearly revealed its presence. In gastric tissue containing cancer cells, an additional proteinase, which was not present in normal tissue, was detected and named medium moving proteinase (MMP). MMP resembled PGs in alkaline stability rather than the non-PG proteinase, slow moving proteinase (SMP).

Adult↗

PubMed1994

Serological and clinical characteristics of measles vaccine failure in Japan.

In 1991, in Fukuoka, Japan, a measles outbreak occurred in which we observed 15 cases of measles vaccine failure (MVF). We examined these patients both clinically and serologically. Seven of them, with a response pattern of an early rise in and attainment of a high hemagglutination inhibition (HI) antibody titre, were considered to be secondary vaccine failures (EH group). Eight others showed a normal (relatively late rise and low titre) HI antibody response pattern and were considered to be primary vaccine failures (LL group). In both MVF groups, measles-specific IgM antibody was detected by enzyme immunoassay. The EH group had a milder rash than did the LL group and unvaccinated controls. We believe they had an immunological memory that modified the clinical manifestations of measles. Two cases of encephalitis were observed in the EH group; both patients recovered without sequelae. These data suggest that the mere presence or absence of IgM antibody is not sufficient to differentiate primary from secondary MVFs. A two-dose measles vaccination scheme should be recommended to secure a booster effect, because immunity is waning in the population in which the measles vaccination rate is not high enough and in which natural measles still exists.

Antibodies, Viral↗

PubMed1994

Metabolism and pharmacokinetics of dihydrocodeine in dog.

1. The metabolism and pharmacokinetics of dihydrocodeine have been studied in dog. Urinary metabolites after oral administration of dihydrocodeine were identified using hplc with diode-array and ms. 2. In urine, dihydronorcodeine, dihydromorphine and dihydrocodeine glucuronide were identified in comparison with their authentic standards, and dihydronorcodeine 6-glucuronide also appeared to be excreted as a metabolite. 3. The major urinary metabolite was dihydrocodeine glucuronide, recovered as 49% of the dose, and other metabolites were found to be 0.1-3%, 24 h after 3 mg/kg oral administration of dihydrocodeine. Plasma concentrations of unchanged dihydrocodeine were significantly lower after oral rather than intramuscular administration; the maximum concentrations were 40 and 549 ng/ml after oral and intramuscular administration, respectively. This suggests that dihydrocodeine was metabolized via a hepatic first-pass effect after oral administration. 4. Overall, our results indicate that the metabolic pathways of dihydrocodeine in dog were similar to that of codeine metabolism in animals and man.

Administration, Oral↗

PubMed1994

The role of hemolysate in the facilitation of oxyhemoglobin-induced contraction in rabbit basilar arteries.

The importance of factors within hemolysate in modulating oxyhemoglobin (oxyHb)-induced contraction was examined in an in vitro model of rabbit basilar arteries. When the basilar arteries were exposed to purified oxyHb alone, the contractile response observed was significantly weaker than that seen in arteries exposed to hemolysate containing an equal concentration of oxyHb. In order to delineate the nature of the factors within hemolysate that facilitate contraction, hemolysate was fractionated, and various components were tested individually for their ability to elicit this effect. A low-molecular-weight fraction of hemolysate, ranging from 0.5 to 2.0 kD, elicited only a mild contraction. However, when this fraction was combined with purified oxyHb, the contractile response was comparable in magnitude to that of unfractionated hemolysate. These studies confirm that purified oxyHb is capable of inducing contraction in vitro. The data also demonstrate that oxyHb elicits a significantly weaker contraction than does hemolysate. In addition, the results suggest that low-molecular-weight components in hemolysate (in the 0.5- to 2.0-kD range), while incapable of inducing a potent contraction alone, may act in concert with oxyHb to elicit the vasoconstriction seen following subarachnoid hemorrhage.

Acetylcholine↗

PubMed1994

Leishmania major-like parasite, a pathogenic agent of cutaneous leishmaniasis in Paraguay.

Leishmania parasites isolated from two patients with cutaneous leishmaniasis from geographically different localities in Paraguay have been characterized by enzyme electrophoresis (zymodeme) and digestion profiles of kinetoplast DNA with restriction enzymes (schizodeme). Both Paraguayan isolates showed identical zymodeme profiles to each other using 14 enzymes (glutamic pyruvate transaminase, glutamic oxaloacetic transaminase, enolase, fumarate hydratase, glucose phosphate isomerase, glucose-6-phosphate dehydrogenase, malate dehydrogenase, malic enzyme, mannose phosphate isomerase, nucleoside phosphorylase, peptidase-D, 6-phosphogluconate dehydrogenase, phosphoglucomutase, and pyruvate kinase). Although two Paraguayan isolates showed different zymodeme profiles from those of six Leishmania reference strains of Old and New World Leishmania species, they showed identical zymodeme profiles to those of an L. major-like parasite from Ecuador. These observations were confirmed by schizodeme analysis using three restriction endonucleases (Msp I, Hae III, and Taq I). These results indicate that Leishmania parasites isolated in Paraguay are identified as an L. major-like parasite, and it is necessary to consider the existence of L. major-like parasites when classifying Leishmania isolates from the New World.

Alanine Transaminase↗