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Biomedical subjects

K Kimura

Publications and source records attributed to K Kimura.

At least 19 recordsLinked to original sources
PubMed1992

[Changes in mammographic features of breast cancer--comparison with previous films].

Mammographic features of 87 breast cancer patients were studied in comparison with their previous survey films. Changes in the mammographic features included microcalicification (28 cases), tumor shadow (35 cases) and intratumorous microcalicifications (6 cases). Seven cases had several extremely faint calcifications on the previous films, and three of six cases with clustered and scattered microcalcifications that extended over an entire breast quadrant had increased in number, density and extent. Eight cases in which clustered microcalcifications had increased in number, density and extent suggested a relationship between the increase in the extent of microcalcifications and length of time between visits. In most cases with tumor shadow, a slight localized increase in mammary gland density, irregular margins and straightened trabeculae were overlooked because of breast density.

Aged↗
PubMed1992

[Echocardiography-guided transseptal left atrial puncture: a safe approach to percutaneous transvenous mitral commissurotomy].

Transseptal left atrial puncture has generally been carried out under fluoroscopic control. In our experience, cardiac tamponade occurred in 3 of 83 cases during transseptal puncture for percutaneous transvenous mitral commissurotomy (PTMC) and percutaneous transvenous aortic valvuloplasty (PTAV). We tried to perform the puncture under simultaneous fluoroscopic and 2DE guidance to decrease the rate of complications. As a result, no complication has occurred in 55 cases. Furthermore, 2DE indicated that directing the puncture needle towards 4 or 5 o'clock was inappropriate, but that 3 o'clock was an appropriate direction for puncture of the fossa ovalis of a left atrium dilated because of mitral stenosis. In conclusion, transseptal left atrial puncture can safely and easily be carried out under a combination of fluoroscopic and 2DE guidance, as this procedure displays the correct position and direction of the needle tip for interatrial septal puncture.

Adolescent↗
PubMed1992

Application of a novel apparatus, the quartz chemical analyzer, to the determination of endotoxin in blood.

A novel apparatus called a quartz chemical analyzer (QCA) has been developed using a quartz crystal resonator. This apparatus measures sample viscosity changes based on resonant frequency changes of the quartz crystal. The apparatus was used to determine bacterial endotoxin concentrations by monitoring the gelation reaction of Limulus amebocyte lysate. The QCA determined endotoxin concentrations with good accuracy and reproducibility in the range of 0.001-3 EU/ml for endotoxin standard (JP XII). For endotoxin determination in human whole blood and plasma samples, the inhibitory reaction was eliminated by pretreatment of a fourfold dilution at 60 degrees C and incubation for 30 min. There are many advantages of the QCA method compared with the turbidimetric and chromogenic methods. For example, QCA can measure sample viscosity changes with high sensitivity and accuracy because QCA detects minor resonant frequency changes and the frequency data give a numerical value for easy quantitation. QCA can examine turbid samples, and the required quantities of samples and reagents are small, since the quartz crystal detects sample viscosity changes directly. The endotoxin determination time may be shortened by raising the reaction temperature, and QCA can detect other types of coagulation reactions.

Antithrombin III↗
PubMed1992

Alterations in biodistribution of 11C-methamphetamine (MAP), 14C-MAP, and 123I-N-isopropyl-iodoamphetamine (IMP) in MAP- and cocaine-sensitized animals.

Alterations in brain distribution of 11C-MAP, 14C-MAP, and 123I-IMP in MAP- and cocaine-sensitized animals were examined to investigate the mechanism involved in increased dopaminergic transmission and behavioral sensitization. First, a significant increase in 11C-MAP radioactivity in the striatum and hypothalamus was found in the mice pretreated with MAP for 7 days. Secondly, in MAP-sensitized rats, marked increases in 14C-MAP radioactivity were found in the striatum and limbic forebrain, respectively (370% and 650%). These findings may propose a new hypothesis that subchronic MAP administration may result in a long-term change in the presynaptic cell membrane at the nerve terminal which may in turn cause an increase in both MAP and DA uptake accompanied by an increased release of DA at the synaptic cleft.

Amphetamines↗
PubMed1992

Different preparations of zymosan induce glycogenolysis independently in the perfused rat liver. Involvement of mannose receptors, peptide-leukotrienes and prostaglandins.

Zymosan (non-boiled) induced glycogenolysis biphasically, with no lag time, in the perfused rat liver. After the zymosan was boiled, it could be separated into two fractions, both of which stimulated glycogenolysis independently. The soluble fraction of boiled zymosan (zymosan sup) showed homologous desensitization, indicating that zymosan sup-induced glycogenolysis is a receptor-mediated event. Mannan (polymannose), which is known to be a biologically active component of zymosan, induced a glycogenolytic response similar to that produced by zymosan sup, and desensitized the response to the latter. Preinfusion of platelet-activating factor (PAF, 20 nM) or isoprenaline (10 microM) did not extinguish the glycogenolytic response to zymosan sup, while the response to a secondary infusion of PAF was blocked. The glycogenolytic response to zymosan sup was completely inhibited by nordihydroguaiaretic acid (NDGA, 10 microM), a lipoxygenase inhibitor, and by ONO-1078 (100 ng/ml), a leukotriene (LT) D4 receptor antagonist. On the other hand, the glycogenolytic effect of zymosan pellet (the particulate fraction of boiled zymosan) was not affected by preinfusion of zymosan sup, and was inhibited by ibuprofen (20 microM), a cyclo-oxygenase inhibitor. Prostaglandins (PGs) detected in the perfusate were augmented with infusion of zymosan pellet. Opsonization of the zymosan pellet by serum (complement) enhanced the glycogenolytic response without a lag period, and with a concomitant enhancement of PG output. Correlations between glucose production and PGs were r = 0.832 (PGD2), r = 0.872 (PGF2 alpha), r = 0.752 (PGE2) and r = 0.349 (6-oxo-PGF1 alpha). The glycogenolytic response to non-boiled zymosan was delayed and the biphasic glycogenolytic response was not observed when mannan was infused first. NDGA mimicked the effects of the preinfusion of mannan, while ibuprofen had no effect on the non-boiled-zymosan-induced glycogenolysis. These results suggest: (1) that non-boiled zymosan stimulates glycogenolysis through a mannose receptor-dependent, but unidentified, pathway, (2) that zymosan sup induces glycogenolysis via mannose receptor activation through the production of peptide-LTs but not PAF, and (3) that zymosan pellet causes glycogenolysis through the production of prostanoids, which is enhanced in the presence of complement.

Animals↗
PubMed1992

Identity determinants of E. coli threonine tRNA.

To investigate the identity determinants of E. coli threonine tRNA, various transcripts were prepared by in vitro transcription system with T7 RNA polymerase. Substitutions of the anticodon second letter G35 and the third letter U36 to other nucleotides led to a remarkable decrease of threonine charging activity. Charging experiments with a series of anticodon-deletion transcripts also suggest the importance of the G35U36 sequence. A mutation at either the G1-C72 or C2-G71 base pair in the acceptor stem seriously affected the threonine charging activity. These results indicate that the second and third positions of the anticodon and the first and second base pairs in the acceptor stem are the recognition sites of E. coli tRNA(THR) for threonyl-tRNA synthetase. Discriminator base, A73, is not involved in threonine charging activity.

Base Sequence↗
PubMed1992

The complete nucleotide sequence of the gene coding for the nontoxic-nonhemagglutinin component of Clostridium botulinum type C progenitor toxin.

The structural gene for a nontoxic-nonhemagglutinin component of Clostridium botulinum type C progenitor toxin was found to exist on a 7.8 kb DNA fragment obtained from a type C phage DNA. The gene existed between the neurotoxin and hemagglutinin genes, and consisted of an 3588 bp open reading frame (1196 amino acid residues). It was speculated that this gene and the neurotoxin gene were transcribed by the same mRNA (polycistronic transcription) in C. botulinum organisms.

Amino Acid Sequence↗
PubMed1992

Fluorescence quenching measurements of the membrane bound lipid haptens with different length spacers.

Dansyl lipid haptens with three different length (short, intermediate and long) spacers have been incorporated into DMPC or DPPC liposomes. Anti-DNS-IgG bound most efficiently to these liposomes containing lipid haptens with an intermediate length spacer, although the binding efficiency became more increased when liposomes were made of a mixture of phospholipid (DMPC or DPPC) and cholesterol. To explain these results we have measured the accessibility of dansyl lipid haptens in liposomal membranes by the fluorescence quenching method. It was found that the dansyl haptens located on the surfaces of DMPC (or DPPC) membranes and fluorescence quenchers (iodide ions) possessed almost similar accessibility for the dansyl haptens with different length spacers. However, in the DMPC (or DPPC) membranes with 50% cholesterol, a part of the dansyl haptens became buried into the interior of the liposomal membranes depending on the length of the spacer and another part removed into the aqueous solution with greater affinity for antibody. These results were explained well by our recent model for antibody binding to the membrane-bound lipid haptens.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

Biosynthesis of cholic acid accelerated by diabetes: its mechanism and effect of vanadate administration.

[7 beta-3H]3 alpha,7 alpha-Dihydroxy-5 beta-cholestane was infused into the femoral vein of bile-fistula rats. The main metabolites in bile were cholic, chenodeoxycholic, and alpha-muricholic acids. Cholic acid accounted for only 7.5% of the total biliary [3H]bile acids in the normal rats, but 51.8% in the diabetic rats. This increased proportion of cholic acid was partially cancelled by treatment of the diabetic rats with insulin (29.8%) or vanadate (28.8%). These results clearly confirm that an alternative biosynthetic pathway of cholic acid via 3 alpha,7 alpha-dihydroxy-5 beta-cholestane is accelerated by diabetes, and indicate that vanadate has an insulin-like effect on the formation of cholic acid in an insulin-deficient state.

Animals↗
PubMed1992

Functional relationships between cyclodextrin glucanotransferase from an alkalophilic Bacillus and alpha-amylases. Site-directed mutagenesis of the conserved two Asp and one Glu residues.

Comparison of the amino acid sequences of cyclodextrin glucanotransferases (CGTases) with those of alpha-amylases revealed that two Asp and one Glu residues, which are considered to be the catalytic residues in alpha-amylases, were also conserved in CGTases. To analyze the function of the three conserved amino acid residues in CGTases, site-directed mutagenesis was carried out. The three mutant CGTases, in which Asp229, Glu257 and Asp328 were individually replaced by Asn or Gln, completely lost both their starch-degrading and beta-cyclodextrin-forming activities, whereas another mutant CGTase, in which Glu264 was replaced by Gln, retained these activities. The three inactive enzymes retained the ability to be bound to starch. These results suggest that Asp229, Glu257 and Asp328 play an important role in the enzymatic reaction catalyzed by CGTase and that a similar catalytic mechanism is present in both CGTases and alpha-amylases.

Aspartic Acid↗
PubMed1992

Correlation between killing activity towards the murine L929 cell line and expression of membrane-associated lymphotoxin-related molecule of human lymphokine-activated killer cells.

Human lymphokine-activated killer (LAK) cells expressed a membrane-associated lymphotoxin-related molecule (mLT) which was detected by flow cytometric analysis with anti-lymphotoxin antibody. Upon removal of exogenous interleukin-2 from LAK cell culture medium and another 24 h cultivation, the expression of mLT was decreased. Corresponding to the decrease of mLT expression, the killing activity of LAK cells towards L929 cells was remarkably reduced and killing of MIA PaCa-2 and U937 cells was moderately reduced, whereas killing of Daudi and K562 cells was fully restored. The supernatant of mLT-expressing LAK cells had no cytotoxic activity towards L929 cells in the absence of actinomycin D. Moreover, not only the killing of L929 cells but also that of human tumor cell lines (MIA PaCa-2, U937) by mLT-expressing LAK cells was partially inhibited in the presence of anti-lymphotoxin antibody. These results suggest an involvement of mLT in the killing of some tumor target cells by LAK cells.

Animals↗
PubMed1992

Direct secretion from left atrium and pulmonary extraction of human atrial natriuretic peptide.

To evaluate direct secretion from the left atrium and pulmonary extraction of human atrial natriuretic peptide (hANP), we measured plasma hANP levels in the pulmonary artery, pulmonary vein, and left atrium in patients with either mitral stenosis or atrial septal defect. Left atrial pressure in patients with mitral stenosis was significantly higher than that in patients with atrial septal defect (7.5 +/- 1.0 mm Hg vs 3.1 +/- 0.5 mm Hg, p less than 0.01). The significant increase in the hANP level in the left atrium was recognized only in patients with mitral stenosis (149 +/- 33 pg/ml in the left atrium vs 130 +/- 28 pg/ml in the pulmonary vein, p less than 0.05). The plasma hANP level in the pulmonary vein was significantly lower than that in the pulmonary artery in both patients with mitral stenosis and those with atrial septal defect, which suggests that hANP is extracted in the lung. We conclude that hANP is secreted not only through the coronary sinus but also directly from the left atrium, stimulated by high left atrial pressure, and that circulating hANP is partially extracted in the pulmonary circulation.

Adult↗
PubMed1992

Statistical analysis of clinical risk factors for coronary artery spasm: identification of the most important determinant.

Coronary artery spasm plays an important role in acute ischemic events, and it has a close relationship with coronary atherosclerosis. Thus we attempted to determine the most significant risk factor for coronary artery spasm. Among 3000 consecutive patients who underwent coronary cineangiography with ergonovine maleate testing, 330 with typical angina pectoris (group 1) and 294 with old myocardial infarction (group 2) were studied. We divided each group into three or four subgroups according to the presence of fixed organic stenosis (FOS+) or a positive reaction to ergonovine maleate (coronary artery spasm [CAS]+). We examined the relationship between coronary artery spasm and eight coronary risk factors: age, sex, hypertension, diabetes mellitus, smoking, and serum cholesterol, uric acid, and high-density lipoprotein cholesterol levels. The proportion of smokers in the subgroups with CAS(+) was significantly higher than in the subgroups with CAS(-)(p less than 0.01). There was no correlation between smoking and fixed organic stenosis. According to the results of multiple regression analysis, there was a positive correlation between smoking and CAS(+) and between serum high-density lipoprotein cholesterol levels and CAS(+)(p less than 0.01). Thus we concluded that smoking is the most significant risk factor in discriminating between patients with and without coronary artery spasm.

Cholesterol, HDL↗
PubMed1992

Development of gap junctions between gastric surface mucous cells during cell maturation in rats.

The development of gap junctions in rat gastric surface mucous cells during their maturation were examined by indirect immunofluorescence and freeze-fracture methods. Monoclonal antibody against liver gap junction protein stained in large spots along the intercellular junctions between mature gastric surface mucous cells. On the other hand, relatively small fluorescent spots were present over the immature surface mucous cells. The freeze-fracture method showed many large irregular gap junctions between mature surface mucous cells. In immature surface mucous cells, the gap junctions were less developed than those of mature cells, and small gap junctions were occasionally associated with tight junctional strands. Quantitatively, the gap junctions in mature cells were larger and more numerous than those in immature cells. These findings show that gap junctions develop during the maturation of surface mucous cells and suggest that the intercellular communication mediated by gap junctions between gastric surface mucous cells plays an important role in the regulation of cell differentiation and in tissue homeostasis.

Animals↗
PubMed1992

Characteristics and management of patients with fetal neuroblastoma.

At 35 weeks 6 days of gestational age, ultrasound evaluation of the fetal abdomen showed a mixed cystic mass in the superior pole of the left kidney. The mass was suspected to be an adrenal hemorrhage or neuroblastoma. The diagnosis was fetal neuroblastoma. Differential diagnosis enabled the fetal neuroblastoma to be distinguished from adrenal hemorrhage. The parameters of diagnosis of fetal neuroblastoma include no specific ultrasonographic pattern, lack of palpability, and no tumor markers. However, certain features do characterize fetal neuroblastoma, such as little metastases, complete resection at operation, and excellent prognosis. In cases of suspected neuroblastoma, a laparotomy performed as soon as possible is generally regarded as the best course of treatment. Nonetheless, biological analyses of the tumor may prove in the future to be necessary for determining whether or not laparotomy is the best treatment.

Adrenal Gland Diseases↗
PubMed1992

Mucosal morphology in isolated bowel segments: importance of exposure to luminal contents.

An isolated bowel segment (IBS) is a loop of intestine that has been freed from its mesenteric attachment after the development of vascular collaterals between the antimesenteric surface of the gut and the host organ. Surgical creation of such artificially vascularized isolated bowel segments is of interest to researchers for a variety of studies, and may be useful in the treatment of short bowel syndrome, allowing longitudinal division of the remaining small bowel to double its length. We created four surgical variants to study the ability of the collateral blood supply to maintain mucosal integrity in the presence or absence of normal luminal contents. In all groups, a collateral blood supply was created in a 5- to 7-cm segment of adult rat jejunum by hepatoenteropexy (Iowa model II). In Thiry-Vella (T-V) and isolated bowel segment (IBS) rats, this segment was exteriorized at both ends to exclude luminal contents. Control and IBS in continuity (IBS-C) loops were left in continuity. The mesentery of IBS and IBS-C rats was divided 5 weeks later, leaving the experimental segment entirely dependent on the collateral circulation. All animals were harvested at 7 weeks after the initial surgery. Tissues were analyzed for mucosal weight, protein content per centimeter of bowel, length of villi, depth of crypts, DNA content, and sucrase activity. We found that segments retaining luminal continuity had significantly higher mucosal weight and DNA content per centimeter of bowel compared with exteriorized loops.

Animals↗
PubMed1992

Inhibition of norepinephrine secretion from digitonin permeabilized PC12 cells by botulinum type D toxin.

Botulinum type D neurotoxin inhibited Ca(2+)-evoked norepinephrine secretion in digitonin permeabilized PC12 cells. Inhibition by the toxin required prior incubation with dithiothreitol (DTT). The inhibition was dependent on both concentration and incubation times of the toxin, and was affected by Ca2+ concentration. With less than 0.7 microM Ca2+ almost complete inhibition was observed; however, above 0.7 microM, Ca2+ stimulated additional norepinephrine release in a dose-dependent manner.

Animals↗